Adding upstream version 6.1.22-dfsg.upstream/6.1.22-dfsgupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

204 files changed, 53868 insertions, 0 deletions

diff --git a/src/VBox/Runtime/r0drv/Makefile.kup b/src/VBox/Runtime/r0drv/Makefile.kup
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/Makefile.kup
diff --git a/src/VBox/Runtime/r0drv/RTR0DbgKrnlInfoGetSymbol.cpp b/src/VBox/Runtime/r0drv/RTR0DbgKrnlInfoGetSymbol.cpp
new file mode 100644
index 00000000..d0861ea9
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/RTR0DbgKrnlInfoGetSymbol.cpp
@@ -0,0 +1,46 @@
+/* $Id: RTR0DbgKrnlInfoGetSymbol.cpp $ */
+/** @file
+ * IPRT - RTR0DbgKrnlInfoGetSymbol, ring-0 drivers.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "internal/iprt.h"
+#include <iprt/dbg.h>
+
+#include <iprt/errcore.h>
+
+
+RTR0DECL(void *) RTR0DbgKrnlInfoGetSymbol(RTDBGKRNLINFO hKrnlInfo, const char *pszModule, const char *pszSymbol)
+{
+    void *pvSymbol = NULL;
+    int rc = RTR0DbgKrnlInfoQuerySymbol(hKrnlInfo, pszModule, pszSymbol, &pvSymbol);
+    if (RT_SUCCESS(rc))
+        return pvSymbol;
+    return NULL;
+}
+RT_EXPORT_SYMBOL(RTR0DbgKrnlInfoGetSymbol);
+
diff --git a/src/VBox/Runtime/r0drv/alloc-ef-r0drv.cpp b/src/VBox/Runtime/r0drv/alloc-ef-r0drv.cpp
new file mode 100644
index 00000000..41ccf1ad
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/alloc-ef-r0drv.cpp
@@ -0,0 +1,1009 @@
+/* $Id: alloc-ef-r0drv.cpp $ */
+/** @file
+ * IPRT - Memory Allocation, electric fence for ring-0 drivers.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTMEM_NO_WRAP_TO_EF_APIS
+#include "internal/iprt.h"
+#include <iprt/mem.h>
+
+#include <iprt/alloc.h>
+#include <iprt/asm.h>
+#include <iprt/asm-amd64-x86.h>
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+#include <iprt/log.h>
+#include <iprt/memobj.h>
+#include <iprt/param.h>
+#include <iprt/string.h>
+#include <iprt/thread.h>
+
+#include "internal/mem.h"
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+#if defined(DOXYGEN_RUNNING)
+# define RTR0MEM_EF_IN_FRONT
+#endif
+
+/** @def RTR0MEM_EF_SIZE
+ * The size of the fence. This must be page aligned.
+ */
+#define RTR0MEM_EF_SIZE             PAGE_SIZE
+
+/** @def RTR0MEM_EF_ALIGNMENT
+ * The allocation alignment, power of two of course.
+ *
+ * Use this for working around misaligned sizes, usually stemming from
+ * allocating a string or something after the main structure.  When you
+ * encounter this, please fix the allocation to RTMemAllocVar or RTMemAllocZVar.
+ */
+#if 0
+# define RTR0MEM_EF_ALIGNMENT       (ARCH_BITS / 8)
+#else
+# define RTR0MEM_EF_ALIGNMENT       1
+#endif
+
+/** @def RTR0MEM_EF_IN_FRONT
+ * Define this to put the fence up in front of the block.
+ * The default (when this isn't defined) is to up it up after the block.
+ */
+//# define RTR0MEM_EF_IN_FRONT
+
+/** @def RTR0MEM_EF_FREE_DELAYED
+ * This define will enable free() delay and protection of the freed data
+ * while it's being delayed. The value of RTR0MEM_EF_FREE_DELAYED defines
+ * the threshold of the delayed blocks.
+ * Delayed blocks does not consume any physical memory, only virtual address space.
+ */
+#define RTR0MEM_EF_FREE_DELAYED     (20 * _1M)
+
+/** @def RTR0MEM_EF_FREE_FILL
+ * This define will enable memset(,RTR0MEM_EF_FREE_FILL,)'ing the user memory
+ * in the block before freeing/decommitting it. This is useful in GDB since GDB
+ * appears to be able to read the content of the page even after it's been
+ * decommitted.
+ */
+#define RTR0MEM_EF_FREE_FILL        'f'
+
+/** @def RTR0MEM_EF_FILLER
+ * This define will enable memset(,RTR0MEM_EF_FILLER,)'ing the allocated
+ * memory when the API doesn't require it to be zero'd.
+ */
+#define RTR0MEM_EF_FILLER           0xef
+
+/** @def RTR0MEM_EF_NOMAN_FILLER
+ * This define will enable memset(,RTR0MEM_EF_NOMAN_FILLER,)'ing the
+ * unprotected but not allocated area of memory, the so called no man's land.
+ */
+#define RTR0MEM_EF_NOMAN_FILLER     0xaa
+
+/** @def RTR0MEM_EF_FENCE_FILLER
+ * This define will enable memset(,RTR0MEM_EF_FENCE_FILLER,)'ing the
+ * fence itself, as debuggers can usually read them.
+ */
+#define RTR0MEM_EF_FENCE_FILLER     0xcc
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#ifdef RT_OS_WINDOWS
+# include <iprt/win/windows.h>
+#elif !defined(RT_OS_FREEBSD)
+# include <sys/mman.h>
+#endif
+#include <iprt/avl.h>
+#include <iprt/thread.h>
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Allocation types.
+ */
+typedef enum RTMEMTYPE
+{
+    RTMEMTYPE_RTMEMALLOC,
+    RTMEMTYPE_RTMEMALLOCZ,
+    RTMEMTYPE_RTMEMREALLOC,
+    RTMEMTYPE_RTMEMFREE,
+    RTMEMTYPE_RTMEMFREEZ,
+
+    RTMEMTYPE_NEW,
+    RTMEMTYPE_NEW_ARRAY,
+    RTMEMTYPE_DELETE,
+    RTMEMTYPE_DELETE_ARRAY
+} RTMEMTYPE;
+
+/**
+ * Node tracking a memory allocation.
+ */
+typedef struct RTR0MEMEFBLOCK
+{
+    /** Avl node code, key is the user block pointer. */
+    AVLPVNODECORE   Core;
+    /** Allocation type. */
+    RTMEMTYPE       enmType;
+    /** The memory object. */
+    RTR0MEMOBJ      hMemObj;
+    /** The unaligned size of the block. */
+    size_t          cbUnaligned;
+    /** The aligned size of the block. */
+    size_t          cbAligned;
+    /** The allocation tag (read-only string). */
+    const char     *pszTag;
+    /** The return address of the allocator function. */
+    void           *pvCaller;
+    /** Line number of the alloc call. */
+    unsigned        iLine;
+    /** File from within the allocation was made. */
+    const char     *pszFile;
+    /** Function from within the allocation was made. */
+    const char     *pszFunction;
+} RTR0MEMEFBLOCK, *PRTR0MEMEFBLOCK;
+
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/** Spinlock protecting the all the block's globals. */
+static volatile uint32_t        g_BlocksLock;
+/** Tree tracking the allocations. */
+static AVLPVTREE                g_BlocksTree;
+
+#ifdef RTR0MEM_EF_FREE_DELAYED
+/** Tail of the delayed blocks. */
+static volatile PRTR0MEMEFBLOCK g_pBlocksDelayHead;
+/** Tail of the delayed blocks. */
+static volatile PRTR0MEMEFBLOCK g_pBlocksDelayTail;
+/** Number of bytes in the delay list (includes fences). */
+static volatile size_t          g_cbBlocksDelay;
+#endif /* RTR0MEM_EF_FREE_DELAYED */
+
+/** Array of pointers free watches for. */
+void   *gapvRTMemFreeWatch[4] = {NULL, NULL, NULL, NULL};
+/** Enable logging of all freed memory. */
+bool    gfRTMemFreeLog = false;
+
+
+/*********************************************************************************************************************************
+*   Internal Functions                                                                                                           *
+*********************************************************************************************************************************/
+
+
+/**
+ * @callback_method_impl{FNRTSTROUTPUT}
+ */
+static DECLCALLBACK(size_t) rtR0MemEfWrite(void *pvArg, const char *pachChars, size_t cbChars)
+{
+    RT_NOREF1(pvArg);
+    if (cbChars)
+    {
+        RTLogWriteDebugger(pachChars, cbChars);
+        RTLogWriteStdOut(pachChars, cbChars);
+        RTLogWriteUser(pachChars, cbChars);
+    }
+    return cbChars;
+}
+
+
+/**
+ * Complains about something.
+ */
+static void rtR0MemComplain(const char *pszOp, const char *pszFormat, ...)
+{
+    va_list args;
+    RTStrFormat(rtR0MemEfWrite, NULL, NULL, NULL, "RTMem error: %s: ", pszOp);
+    va_start(args, pszFormat);
+    RTStrFormatV(rtR0MemEfWrite, NULL, NULL, NULL, pszFormat, args);
+    va_end(args);
+    RTAssertDoPanic();
+}
+
+/**
+ * Log an event.
+ */
+DECLINLINE(void) rtR0MemLog(const char *pszOp, const char *pszFormat, ...)
+{
+#if 0
+    va_list args;
+    RTStrFormat(rtR0MemEfWrite, NULL, NULL, NULL, "RTMem info: %s: ", pszOp);
+    va_start(args, pszFormat);
+    RTStrFormatV(rtR0MemEfWrite, NULL, NULL, NULL, pszFormat, args);
+    va_end(args);
+#else
+    NOREF(pszOp); NOREF(pszFormat);
+#endif
+}
+
+
+
+/**
+ * Acquires the lock.
+ */
+DECLINLINE(RTCCUINTREG) rtR0MemBlockLock(void)
+{
+    RTCCUINTREG uRet;
+    unsigned c = 0;
+    if (RTThreadPreemptIsEnabled(NIL_RTTHREAD))
+    {
+        for (;;)
+        {
+            uRet = ASMIntDisableFlags();
+            if (ASMAtomicCmpXchgU32(&g_BlocksLock, 1, 0))
+                break;
+            ASMSetFlags(uRet);
+            RTThreadSleepNoLog(((++c) >> 2) & 31);
+        }
+    }
+    else
+    {
+        for (;;)
+        {
+            uRet = ASMIntDisableFlags();
+            if (ASMAtomicCmpXchgU32(&g_BlocksLock, 1, 0))
+                break;
+            ASMSetFlags(uRet);
+            ASMNopPause();
+            if (++c & 3)
+                ASMNopPause();
+        }
+    }
+    return uRet;
+}
+
+
+/**
+ * Releases the lock.
+ */
+DECLINLINE(void) rtR0MemBlockUnlock(RTCCUINTREG fSavedIntFlags)
+{
+    Assert(g_BlocksLock == 1);
+    ASMAtomicXchgU32(&g_BlocksLock, 0);
+    ASMSetFlags(fSavedIntFlags);
+}
+
+
+/**
+ * Creates a block.
+ */
+DECLINLINE(PRTR0MEMEFBLOCK) rtR0MemBlockCreate(RTMEMTYPE enmType, size_t cbUnaligned, size_t cbAligned,
+                                               const char *pszTag, void *pvCaller, RT_SRC_POS_DECL)
+{
+    PRTR0MEMEFBLOCK pBlock = (PRTR0MEMEFBLOCK)RTMemAlloc(sizeof(*pBlock));
+    if (pBlock)
+    {
+        pBlock->enmType     = enmType;
+        pBlock->cbUnaligned = cbUnaligned;
+        pBlock->cbAligned   = cbAligned;
+        pBlock->pszTag      = pszTag;
+        pBlock->pvCaller    = pvCaller;
+        pBlock->iLine       = iLine;
+        pBlock->pszFile     = pszFile;
+        pBlock->pszFunction = pszFunction;
+    }
+    return pBlock;
+}
+
+
+/**
+ * Frees a block.
+ */
+DECLINLINE(void) rtR0MemBlockFree(PRTR0MEMEFBLOCK pBlock)
+{
+    RTMemFree(pBlock);
+}
+
+
+/**
+ * Insert a block from the tree.
+ */
+DECLINLINE(void) rtR0MemBlockInsert(PRTR0MEMEFBLOCK pBlock, void *pv, RTR0MEMOBJ hMemObj)
+{
+    pBlock->Core.Key = pv;
+    pBlock->hMemObj  = hMemObj;
+    RTCCUINTREG fSavedIntFlags = rtR0MemBlockLock();
+    bool fRc = RTAvlPVInsert(&g_BlocksTree, &pBlock->Core);
+    rtR0MemBlockUnlock(fSavedIntFlags);
+    AssertRelease(fRc);
+}
+
+
+/**
+ * Remove a block from the tree and returns it to the caller.
+ */
+DECLINLINE(PRTR0MEMEFBLOCK) rtR0MemBlockRemove(void *pv)
+{
+    RTCCUINTREG fSavedIntFlags = rtR0MemBlockLock();
+    PRTR0MEMEFBLOCK pBlock = (PRTR0MEMEFBLOCK)RTAvlPVRemove(&g_BlocksTree, pv);
+    rtR0MemBlockUnlock(fSavedIntFlags);
+    return pBlock;
+}
+
+
+/**
+ * Gets a block.
+ */
+DECLINLINE(PRTR0MEMEFBLOCK) rtR0MemBlockGet(void *pv)
+{
+    RTCCUINTREG fSavedIntFlags = rtR0MemBlockLock();
+    PRTR0MEMEFBLOCK pBlock = (PRTR0MEMEFBLOCK)RTAvlPVGet(&g_BlocksTree, pv);
+    rtR0MemBlockUnlock(fSavedIntFlags);
+    return pBlock;
+}
+
+
+/**
+ * Dumps one allocation.
+ */
+static DECLCALLBACK(int) RTMemDumpOne(PAVLPVNODECORE pNode, void *pvUser)
+{
+    PRTR0MEMEFBLOCK pBlock = (PRTR0MEMEFBLOCK)pNode;
+    RTStrFormat(rtR0MemEfWrite, NULL, NULL, NULL, "%p %08lx(+%02lx) %p\n",
+                pBlock->Core.Key,
+                (unsigned long)pBlock->cbUnaligned,
+                (unsigned long)(pBlock->cbAligned - pBlock->cbUnaligned),
+                pBlock->pvCaller);
+    NOREF(pvUser);
+    return 0;
+}
+
+
+/**
+ * Dumps the allocated blocks.
+ * This is something which you should call from gdb.
+ */
+RT_C_DECLS_BEGIN
+void RTMemDump(void);
+RT_C_DECLS_END
+
+void RTMemDump(void)
+{
+    RTStrFormat(rtR0MemEfWrite, NULL, NULL, NULL, "address  size(alg)     caller\n");
+    RTAvlPVDoWithAll(&g_BlocksTree, true, RTMemDumpOne, NULL);
+}
+
+#ifdef RTR0MEM_EF_FREE_DELAYED
+
+/**
+ * Insert a delayed block.
+ */
+DECLINLINE(void) rtR0MemBlockDelayInsert(PRTR0MEMEFBLOCK pBlock)
+{
+    size_t cbBlock = RT_ALIGN_Z(pBlock->cbAligned, PAGE_SIZE) + RTR0MEM_EF_SIZE;
+    pBlock->Core.pRight = NULL;
+    pBlock->Core.pLeft = NULL;
+    RTCCUINTREG fSavedIntFlags = rtR0MemBlockLock();
+    if (g_pBlocksDelayHead)
+    {
+        g_pBlocksDelayHead->Core.pLeft = (PAVLPVNODECORE)pBlock;
+        pBlock->Core.pRight = (PAVLPVNODECORE)g_pBlocksDelayHead;
+        g_pBlocksDelayHead = pBlock;
+    }
+    else
+    {
+        g_pBlocksDelayTail = pBlock;
+        g_pBlocksDelayHead = pBlock;
+    }
+    g_cbBlocksDelay += cbBlock;
+    rtR0MemBlockUnlock(fSavedIntFlags);
+}
+
+/**
+ * Removes a delayed block.
+ */
+DECLINLINE(PRTR0MEMEFBLOCK) rtR0MemBlockDelayRemove(void)
+{
+    PRTR0MEMEFBLOCK pBlock = NULL;
+    RTCCUINTREG fSavedIntFlags = rtR0MemBlockLock();
+    if (g_cbBlocksDelay > RTR0MEM_EF_FREE_DELAYED)
+    {
+        pBlock = g_pBlocksDelayTail;
+        if (pBlock)
+        {
+            g_pBlocksDelayTail = (PRTR0MEMEFBLOCK)pBlock->Core.pLeft;
+            if (pBlock->Core.pLeft)
+                pBlock->Core.pLeft->pRight = NULL;
+            else
+                g_pBlocksDelayHead = NULL;
+            g_cbBlocksDelay -= RT_ALIGN_Z(pBlock->cbAligned, PAGE_SIZE) + RTR0MEM_EF_SIZE;
+        }
+    }
+    rtR0MemBlockUnlock(fSavedIntFlags);
+    return pBlock;
+}
+
+#endif  /* RTR0MEM_EF_FREE_DELAYED */
+
+
+static void rtR0MemFreeBlock(PRTR0MEMEFBLOCK pBlock, const char *pszOp)
+{
+    void  *pv      = pBlock->Core.Key;
+# ifdef RTR0MEM_EF_IN_FRONT
+    void  *pvBlock = (char *)pv - RTR0MEM_EF_SIZE;
+# else
+    void  *pvBlock = (void *)((uintptr_t)pv & ~(uintptr_t)PAGE_OFFSET_MASK);
+# endif
+    size_t cbBlock = RT_ALIGN_Z(pBlock->cbAligned, PAGE_SIZE) + RTR0MEM_EF_SIZE;
+
+    int rc = RTR0MemObjProtect(pBlock->hMemObj, 0 /*offSub*/, RT_ALIGN_Z(cbBlock, PAGE_SIZE), RTMEM_PROT_READ | RTMEM_PROT_WRITE);
+    if (RT_FAILURE(rc))
+        rtR0MemComplain(pszOp, "RTR0MemObjProtect([%p], 0, %#x, RTMEM_PROT_READ | RTMEM_PROT_WRITE) -> %Rrc\n",
+                        pvBlock, cbBlock, rc);
+
+    rc = RTR0MemObjFree(pBlock->hMemObj, true /*fFreeMappings*/);
+    if (RT_FAILURE(rc))
+        rtR0MemComplain(pszOp, "RTR0MemObjFree([%p LB %#x]) -> %Rrc\n", pvBlock, cbBlock, rc);
+    pBlock->hMemObj = NIL_RTR0MEMOBJ;
+
+    rtR0MemBlockFree(pBlock);
+}
+
+
+/**
+ * Initialize call, we shouldn't fail here.
+ */
+void rtR0MemEfInit(void)
+{
+
+}
+
+/**
+ * @callback_method_impl{AVLPVCALLBACK}
+ */
+static DECLCALLBACK(int) rtR0MemEfDestroyBlock(PAVLPVNODECORE pNode, void *pvUser)
+{
+    PRTR0MEMEFBLOCK pBlock = (PRTR0MEMEFBLOCK)pNode;
+
+    /* Note! pszFile and pszFunction may be invalid at this point. */
+    rtR0MemComplain("rtR0MemEfDestroyBlock", "Leaking %zu bytes at %p (iLine=%u pvCaller=%p)\n",
+                    pBlock->cbAligned, pBlock->Core.Key, pBlock->iLine, pBlock->pvCaller);
+
+    rtR0MemFreeBlock(pBlock, "rtR0MemEfDestroyBlock");
+
+    NOREF(pvUser);
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Termination call.
+ *
+ * Will check and free memory.
+ */
+void rtR0MemEfTerm(void)
+{
+#ifdef RTR0MEM_EF_FREE_DELAYED
+    /*
+     * Release delayed frees.
+     */
+    RTCCUINTREG fSavedIntFlags = rtR0MemBlockLock();
+    for (;;)
+    {
+        PRTR0MEMEFBLOCK pBlock = g_pBlocksDelayTail;
+        if (pBlock)
+        {
+            g_pBlocksDelayTail = (PRTR0MEMEFBLOCK)pBlock->Core.pLeft;
+            if (pBlock->Core.pLeft)
+                pBlock->Core.pLeft->pRight = NULL;
+            else
+                g_pBlocksDelayHead = NULL;
+            rtR0MemBlockUnlock(fSavedIntFlags);
+
+            rtR0MemFreeBlock(pBlock, "rtR0MemEfTerm");
+
+            rtR0MemBlockLock();
+        }
+        else
+            break;
+    }
+    g_cbBlocksDelay = 0;
+    rtR0MemBlockUnlock(fSavedIntFlags);
+#endif
+
+    /*
+     * Complain about leaks. Then release them.
+     */
+    RTAvlPVDestroy(&g_BlocksTree, rtR0MemEfDestroyBlock, NULL);
+}
+
+
+/**
+ * Internal allocator.
+ */
+static void * rtR0MemAlloc(const char *pszOp, RTMEMTYPE enmType, size_t cbUnaligned, size_t cbAligned,
+                           const char *pszTag, void *pvCaller, RT_SRC_POS_DECL)
+{
+    /*
+     * Sanity.
+     */
+    if (    RT_ALIGN_Z(RTR0MEM_EF_SIZE, PAGE_SIZE) != RTR0MEM_EF_SIZE
+        &&  RTR0MEM_EF_SIZE <= 0)
+    {
+        rtR0MemComplain(pszOp, "Invalid E-fence size! %#x\n", RTR0MEM_EF_SIZE);
+        return NULL;
+    }
+    if (!cbUnaligned)
+    {
+#if 1
+        rtR0MemComplain(pszOp, "Request of ZERO bytes allocation!\n");
+        return NULL;
+#else
+        cbAligned = cbUnaligned = 1;
+#endif
+    }
+
+#ifndef RTR0MEM_EF_IN_FRONT
+    /* Alignment decreases fence accuracy, but this is at least partially
+     * counteracted by filling and checking the alignment padding. When the
+     * fence is in front then then no extra alignment is needed. */
+    cbAligned = RT_ALIGN_Z(cbAligned, RTR0MEM_EF_ALIGNMENT);
+#endif
+
+    /*
+     * Allocate the trace block.
+     */
+    PRTR0MEMEFBLOCK pBlock = rtR0MemBlockCreate(enmType, cbUnaligned, cbAligned, pszTag, pvCaller, RT_SRC_POS_ARGS);
+    if (!pBlock)
+    {
+        rtR0MemComplain(pszOp, "Failed to allocate trace block!\n");
+        return NULL;
+    }
+
+    /*
+     * Allocate a block with page alignment space + the size of the E-fence.
+     */
+    void       *pvBlock = NULL;
+    RTR0MEMOBJ  hMemObj;
+    size_t      cbBlock = RT_ALIGN_Z(cbAligned, PAGE_SIZE) + RTR0MEM_EF_SIZE;
+    int rc = RTR0MemObjAllocPage(&hMemObj, cbBlock, false /*fExecutable*/);
+    if (RT_SUCCESS(rc))
+        pvBlock = RTR0MemObjAddress(hMemObj);
+    if (pvBlock)
+    {
+        /*
+         * Calc the start of the fence and the user block
+         * and then change the page protection of the fence.
+         */
+#ifdef RTR0MEM_EF_IN_FRONT
+        void *pvEFence = pvBlock;
+        void *pv       = (char *)pvEFence + RTR0MEM_EF_SIZE;
+# ifdef RTR0MEM_EF_NOMAN_FILLER
+        memset((char *)pv + cbUnaligned, RTR0MEM_EF_NOMAN_FILLER, cbBlock - RTR0MEM_EF_SIZE - cbUnaligned);
+# endif
+#else
+        void *pvEFence = (char *)pvBlock + (cbBlock - RTR0MEM_EF_SIZE);
+        void *pv       = (char *)pvEFence - cbAligned;
+# ifdef RTR0MEM_EF_NOMAN_FILLER
+        memset(pvBlock, RTR0MEM_EF_NOMAN_FILLER, cbBlock - RTR0MEM_EF_SIZE - cbAligned);
+        memset((char *)pv + cbUnaligned, RTR0MEM_EF_NOMAN_FILLER, cbAligned - cbUnaligned);
+# endif
+#endif
+
+#ifdef RTR0MEM_EF_FENCE_FILLER
+        memset(pvEFence, RTR0MEM_EF_FENCE_FILLER, RTR0MEM_EF_SIZE);
+#endif
+        rc = RTR0MemObjProtect(hMemObj, (uint8_t *)pvEFence - (uint8_t *)pvBlock, RTR0MEM_EF_SIZE, RTMEM_PROT_NONE);
+        if (!rc)
+        {
+            rtR0MemBlockInsert(pBlock, pv, hMemObj);
+            if (enmType == RTMEMTYPE_RTMEMALLOCZ)
+                memset(pv, 0, cbUnaligned);
+#ifdef RTR0MEM_EF_FILLER
+            else
+                memset(pv, RTR0MEM_EF_FILLER, cbUnaligned);
+#endif
+
+            rtR0MemLog(pszOp, "returns %p (pvBlock=%p cbBlock=%#x pvEFence=%p cbUnaligned=%#x)\n", pv, pvBlock, cbBlock, pvEFence, cbUnaligned);
+            return pv;
+        }
+        rtR0MemComplain(pszOp, "RTMemProtect failed, pvEFence=%p size %d, rc=%d\n", pvEFence, RTR0MEM_EF_SIZE, rc);
+        RTR0MemObjFree(hMemObj, true /*fFreeMappings*/);
+    }
+    else
+    {
+        rtR0MemComplain(pszOp, "Failed to allocated %zu (%zu) bytes (rc=%Rrc).\n", cbBlock, cbUnaligned, rc);
+        if (RT_SUCCESS(rc))
+            RTR0MemObjFree(hMemObj, true /*fFreeMappings*/);
+    }
+
+    rtR0MemBlockFree(pBlock);
+    return NULL;
+}
+
+
+/**
+ * Internal free.
+ */
+static void rtR0MemFree(const char *pszOp, RTMEMTYPE enmType, void *pv, size_t cbUser, void *pvCaller, RT_SRC_POS_DECL)
+{
+    NOREF(enmType); RT_SRC_POS_NOREF();
+
+    /*
+     * Simple case.
+     */
+    if (!pv)
+        return;
+
+    /*
+     * Check watch points.
+     */
+    for (unsigned i = 0; i < RT_ELEMENTS(gapvRTMemFreeWatch); i++)
+        if (gapvRTMemFreeWatch[i] == pv)
+            RTAssertDoPanic();
+
+    /*
+     * Find the block.
+     */
+    PRTR0MEMEFBLOCK pBlock = rtR0MemBlockRemove(pv);
+    if (pBlock)
+    {
+        if (gfRTMemFreeLog)
+            RTLogPrintf("RTMem %s: pv=%p pvCaller=%p cbUnaligned=%#x\n", pszOp, pv, pvCaller, pBlock->cbUnaligned);
+
+#ifdef RTR0MEM_EF_NOMAN_FILLER
+        /*
+         * Check whether the no man's land is untouched.
+         */
+# ifdef RTR0MEM_EF_IN_FRONT
+        void *pvWrong = ASMMemFirstMismatchingU8((char *)pv + pBlock->cbUnaligned,
+                                                 RT_ALIGN_Z(pBlock->cbAligned, PAGE_SIZE) - pBlock->cbUnaligned,
+                                                 RTR0MEM_EF_NOMAN_FILLER);
+# else
+        /* Alignment must match allocation alignment in rtMemAlloc(). */
+        void *pvWrong = ASMMemFirstMismatchingU8((char *)pv + pBlock->cbUnaligned,
+                                                 pBlock->cbAligned - pBlock->cbUnaligned,
+                                                 RTR0MEM_EF_NOMAN_FILLER);
+        if (pvWrong)
+            RTAssertDoPanic();
+        pvWrong = ASMMemFirstMismatchingU8((void *)((uintptr_t)pv & ~(uintptr_t)PAGE_OFFSET_MASK),
+                                           RT_ALIGN_Z(pBlock->cbAligned, PAGE_SIZE) - pBlock->cbAligned,
+                                           RTR0MEM_EF_NOMAN_FILLER);
+# endif
+        if (pvWrong)
+            RTAssertDoPanic();
+#endif
+
+        /*
+         * Fill the user part of the block.
+         */
+        AssertMsg(enmType != RTMEMTYPE_RTMEMFREEZ || cbUser == pBlock->cbUnaligned,
+                  ("cbUser=%#zx cbUnaligned=%#zx\n", cbUser, pBlock->cbUnaligned));
+        RT_NOREF(cbUser);
+        if (enmType == RTMEMTYPE_RTMEMFREEZ)
+            RT_BZERO(pv, pBlock->cbUnaligned);
+#ifdef RTR0MEM_EF_FREE_FILL
+        else
+            memset(pv, RTR0MEM_EF_FREE_FILL, pBlock->cbUnaligned);
+#endif
+
+#if defined(RTR0MEM_EF_FREE_DELAYED) && RTR0MEM_EF_FREE_DELAYED > 0
+        /*
+         * We're doing delayed freeing.
+         * That means we'll expand the E-fence to cover the entire block.
+         */
+        int rc = RTR0MemObjProtect(pBlock->hMemObj,
+# ifdef RTR0MEM_EF_IN_FRONT
+                                   RTR0MEM_EF_SIZE,
+# else
+                                   0 /*offSub*/,
+# endif
+                                   RT_ALIGN_Z(pBlock->cbAligned, PAGE_SIZE),
+                                   RTMEM_PROT_NONE);
+        if (RT_SUCCESS(rc))
+        {
+            /*
+             * Insert it into the free list and process pending frees.
+             */
+            rtR0MemBlockDelayInsert(pBlock);
+            while ((pBlock = rtR0MemBlockDelayRemove()) != NULL)
+                rtR0MemFreeBlock(pBlock, pszOp);
+        }
+        else
+            rtR0MemComplain(pszOp, "Failed to expand the efence of pv=%p cb=%d, rc=%d.\n", pv, pBlock, rc);
+
+#else  /* !RTR0MEM_EF_FREE_DELAYED */
+        rtR0MemFreeBlock(pBlock, pszOp);
+#endif /* !RTR0MEM_EF_FREE_DELAYED */
+    }
+    else
+        rtR0MemComplain(pszOp, "pv=%p not found! Incorrect free!\n", pv);
+}
+
+
+/**
+ * Internal realloc.
+ */
+static void *rtR0MemRealloc(const char *pszOp, RTMEMTYPE enmType, void *pvOld, size_t cbNew,
+                            const char *pszTag, void *pvCaller, RT_SRC_POS_DECL)
+{
+    /*
+     * Allocate new and copy.
+     */
+    if (!pvOld)
+        return rtR0MemAlloc(pszOp, enmType, cbNew, cbNew, pszTag, pvCaller, RT_SRC_POS_ARGS);
+    if (!cbNew)
+    {
+        rtR0MemFree(pszOp, RTMEMTYPE_RTMEMREALLOC, pvOld, 0, pvCaller, RT_SRC_POS_ARGS);
+        return NULL;
+    }
+
+    /*
+     * Get the block, allocate the new, copy the data, free the old one.
+     */
+    PRTR0MEMEFBLOCK pBlock = rtR0MemBlockGet(pvOld);
+    if (pBlock)
+    {
+        void *pvRet = rtR0MemAlloc(pszOp, enmType, cbNew, cbNew, pszTag, pvCaller, RT_SRC_POS_ARGS);
+        if (pvRet)
+        {
+            memcpy(pvRet, pvOld, RT_MIN(cbNew, pBlock->cbUnaligned));
+            rtR0MemFree(pszOp, RTMEMTYPE_RTMEMREALLOC, pvOld, 0, pvCaller, RT_SRC_POS_ARGS);
+        }
+        return pvRet;
+    }
+    rtR0MemComplain(pszOp, "pvOld=%p was not found!\n", pvOld);
+    return NULL;
+}
+
+
+
+
+RTDECL(void *)  RTMemEfTmpAlloc(size_t cb, const char *pszTag, RT_SRC_POS_DECL) RT_NO_THROW_DEF
+{
+    return rtR0MemAlloc("TmpAlloc", RTMEMTYPE_RTMEMALLOC, cb, cb, pszTag, ASMReturnAddress(), RT_SRC_POS_ARGS);
+}
+
+
+RTDECL(void *)  RTMemEfTmpAllocZ(size_t cb, const char *pszTag, RT_SRC_POS_DECL) RT_NO_THROW_DEF
+{
+    return rtR0MemAlloc("TmpAlloc", RTMEMTYPE_RTMEMALLOCZ, cb, cb, pszTag, ASMReturnAddress(), RT_SRC_POS_ARGS);
+}
+
+
+RTDECL(void)    RTMemEfTmpFree(void *pv, RT_SRC_POS_DECL) RT_NO_THROW_DEF
+{
+    if (pv)
+        rtR0MemFree("Free", RTMEMTYPE_RTMEMFREE, pv, 0, ASMReturnAddress(), RT_SRC_POS_ARGS);
+}
+
+
+RTDECL(void)    RTMemEfTmpFreeZ(void *pv, size_t cb, RT_SRC_POS_DECL) RT_NO_THROW_DEF
+{
+    if (pv)
+        rtR0MemFree("FreeZ", RTMEMTYPE_RTMEMFREEZ, pv, cb, ASMReturnAddress(), RT_SRC_POS_ARGS);
+}
+
+
+RTDECL(void *)  RTMemEfAlloc(size_t cb, const char *pszTag, RT_SRC_POS_DECL) RT_NO_THROW_DEF
+{
+    return rtR0MemAlloc("Alloc", RTMEMTYPE_RTMEMALLOC, cb, cb, pszTag, ASMReturnAddress(), RT_SRC_POS_ARGS);
+}
+
+
+RTDECL(void *)  RTMemEfAllocZ(size_t cb, const char *pszTag, RT_SRC_POS_DECL) RT_NO_THROW_DEF
+{
+    return rtR0MemAlloc("AllocZ", RTMEMTYPE_RTMEMALLOCZ, cb, cb, pszTag, ASMReturnAddress(), RT_SRC_POS_ARGS);
+}
+
+
+RTDECL(void *)  RTMemEfAllocVar(size_t cbUnaligned, const char *pszTag, RT_SRC_POS_DECL) RT_NO_THROW_DEF
+{
+    size_t cbAligned;
+    if (cbUnaligned >= 16)
+        cbAligned = RT_ALIGN_Z(cbUnaligned, 16);
+    else
+        cbAligned = RT_ALIGN_Z(cbUnaligned, sizeof(void *));
+    return rtR0MemAlloc("Alloc", RTMEMTYPE_RTMEMALLOC, cbUnaligned, cbAligned, pszTag, ASMReturnAddress(), RT_SRC_POS_ARGS);
+}
+
+
+RTDECL(void *)  RTMemEfAllocZVar(size_t cbUnaligned, const char *pszTag, RT_SRC_POS_DECL) RT_NO_THROW_DEF
+{
+    size_t cbAligned;
+    if (cbUnaligned >= 16)
+        cbAligned = RT_ALIGN_Z(cbUnaligned, 16);
+    else
+        cbAligned = RT_ALIGN_Z(cbUnaligned, sizeof(void *));
+    return rtR0MemAlloc("AllocZ", RTMEMTYPE_RTMEMALLOCZ, cbUnaligned, cbAligned, pszTag, ASMReturnAddress(), RT_SRC_POS_ARGS);
+}
+
+
+RTDECL(void *)  RTMemEfRealloc(void *pvOld, size_t cbNew, const char *pszTag, RT_SRC_POS_DECL) RT_NO_THROW_DEF
+{
+    return rtR0MemRealloc("Realloc", RTMEMTYPE_RTMEMREALLOC, pvOld, cbNew, pszTag, ASMReturnAddress(), RT_SRC_POS_ARGS);
+}
+
+RTDECL(void *)  RTMemEfReallocZ(void *pvOld, size_t cbOld, size_t cbNew, const char *pszTag, RT_SRC_POS_DECL) RT_NO_THROW_DEF
+{
+    void *pvDst = rtR0MemRealloc("Realloc", RTMEMTYPE_RTMEMREALLOC, pvOld, cbNew, pszTag, ASMReturnAddress(), RT_SRC_POS_ARGS);
+    if (pvDst && cbNew > cbOld)
+        memset((uint8_t *)pvDst + cbOld, 0, cbNew - cbOld);
+    return pvDst;
+}
+
+
+RTDECL(void)    RTMemEfFree(void *pv, RT_SRC_POS_DECL) RT_NO_THROW_DEF
+{
+    if (pv)
+        rtR0MemFree("Free", RTMEMTYPE_RTMEMFREE, pv, 0, ASMReturnAddress(), RT_SRC_POS_ARGS);
+}
+
+
+RTDECL(void)    RTMemEfFreeZ(void *pv, size_t cb, RT_SRC_POS_DECL) RT_NO_THROW_DEF
+{
+    if (pv)
+        rtR0MemFree("Free", RTMEMTYPE_RTMEMFREEZ, pv, cb, ASMReturnAddress(), RT_SRC_POS_ARGS);
+}
+
+
+RTDECL(void *) RTMemEfDup(const void *pvSrc, size_t cb, const char *pszTag, RT_SRC_POS_DECL) RT_NO_THROW_DEF
+{
+    void *pvDst = RTMemEfAlloc(cb, pszTag, RT_SRC_POS_ARGS);
+    if (pvDst)
+        memcpy(pvDst, pvSrc, cb);
+    return pvDst;
+}
+
+
+RTDECL(void *) RTMemEfDupEx(const void *pvSrc, size_t cbSrc, size_t cbExtra, const char *pszTag, RT_SRC_POS_DECL) RT_NO_THROW_DEF
+{
+    void *pvDst = RTMemEfAlloc(cbSrc + cbExtra, pszTag, RT_SRC_POS_ARGS);
+    if (pvDst)
+    {
+        memcpy(pvDst, pvSrc, cbSrc);
+        memset((uint8_t *)pvDst + cbSrc, 0, cbExtra);
+    }
+    return pvDst;
+}
+
+
+
+
+/*
+ *
+ * The NP (no position) versions.
+ *
+ */
+
+
+
+RTDECL(void *)  RTMemEfTmpAllocNP(size_t cb, const char *pszTag) RT_NO_THROW_DEF
+{
+    return rtR0MemAlloc("TmpAlloc", RTMEMTYPE_RTMEMALLOC, cb, cb, pszTag, ASMReturnAddress(), NULL, 0, NULL);
+}
+
+
+RTDECL(void *)  RTMemEfTmpAllocZNP(size_t cb, const char *pszTag) RT_NO_THROW_DEF
+{
+    return rtR0MemAlloc("TmpAllocZ", RTMEMTYPE_RTMEMALLOCZ, cb, cb, pszTag, ASMReturnAddress(), NULL, 0, NULL);
+}
+
+
+RTDECL(void)    RTMemEfTmpFreeNP(void *pv) RT_NO_THROW_DEF
+{
+    if (pv)
+        rtR0MemFree("Free", RTMEMTYPE_RTMEMFREE, pv, 0, ASMReturnAddress(), NULL, 0, NULL);
+}
+
+
+RTDECL(void)    RTMemEfTmpFreeZNP(void *pv, size_t cb) RT_NO_THROW_DEF
+{
+    if (pv)
+        rtR0MemFree("FreeZ", RTMEMTYPE_RTMEMFREEZ, pv, cb, ASMReturnAddress(), NULL, 0, NULL);
+}
+
+
+RTDECL(void *)  RTMemEfAllocNP(size_t cb, const char *pszTag) RT_NO_THROW_DEF
+{
+    return rtR0MemAlloc("Alloc", RTMEMTYPE_RTMEMALLOC, cb, cb, pszTag, ASMReturnAddress(), NULL, 0, NULL);
+}
+
+
+RTDECL(void *)  RTMemEfAllocZNP(size_t cb, const char *pszTag) RT_NO_THROW_DEF
+{
+    return rtR0MemAlloc("AllocZ", RTMEMTYPE_RTMEMALLOCZ, cb, cb, pszTag, ASMReturnAddress(), NULL, 0, NULL);
+}
+
+
+RTDECL(void *)  RTMemEfAllocVarNP(size_t cbUnaligned, const char *pszTag) RT_NO_THROW_DEF
+{
+    size_t cbAligned;
+    if (cbUnaligned >= 16)
+        cbAligned = RT_ALIGN_Z(cbUnaligned, 16);
+    else
+        cbAligned = RT_ALIGN_Z(cbUnaligned, sizeof(void *));
+    return rtR0MemAlloc("Alloc", RTMEMTYPE_RTMEMALLOC, cbUnaligned, cbAligned, pszTag, ASMReturnAddress(), NULL, 0, NULL);
+}
+
+
+RTDECL(void *)  RTMemEfAllocZVarNP(size_t cbUnaligned, const char *pszTag) RT_NO_THROW_DEF
+{
+    size_t cbAligned;
+    if (cbUnaligned >= 16)
+        cbAligned = RT_ALIGN_Z(cbUnaligned, 16);
+    else
+        cbAligned = RT_ALIGN_Z(cbUnaligned, sizeof(void *));
+    return rtR0MemAlloc("AllocZ", RTMEMTYPE_RTMEMALLOCZ, cbUnaligned, cbAligned, pszTag, ASMReturnAddress(), NULL, 0, NULL);
+}
+
+
+RTDECL(void *)  RTMemEfReallocNP(void *pvOld, size_t cbNew, const char *pszTag) RT_NO_THROW_DEF
+{
+    return rtR0MemRealloc("Realloc", RTMEMTYPE_RTMEMREALLOC, pvOld, cbNew, pszTag, ASMReturnAddress(), NULL, 0, NULL);
+}
+
+
+RTDECL(void *)  RTMemEfReallocZNP(void *pvOld, size_t cbOld, size_t cbNew, const char *pszTag) RT_NO_THROW_DEF
+{
+    void *pvDst = rtR0MemRealloc("ReallocZ", RTMEMTYPE_RTMEMREALLOC, pvOld, cbNew, pszTag, ASMReturnAddress(), NULL, 0, NULL);
+    if (pvDst && cbNew > cbOld)
+        memset((uint8_t *)pvDst + cbOld, 0, cbNew - cbOld);
+    return pvDst;
+}
+
+
+RTDECL(void)    RTMemEfFreeNP(void *pv) RT_NO_THROW_DEF
+{
+    if (pv)
+        rtR0MemFree("Free", RTMEMTYPE_RTMEMFREE, pv, 0, ASMReturnAddress(), NULL, 0, NULL);
+}
+
+
+RTDECL(void)    RTMemEfFreeZNP(void *pv, size_t cb) RT_NO_THROW_DEF
+{
+    if (pv)
+        rtR0MemFree("FreeZ", RTMEMTYPE_RTMEMFREEZ, pv, cb, ASMReturnAddress(), NULL, 0, NULL);
+}
+
+
+RTDECL(void *) RTMemEfDupNP(const void *pvSrc, size_t cb, const char *pszTag) RT_NO_THROW_DEF
+{
+    void *pvDst = RTMemEfAlloc(cb, pszTag, NULL, 0, NULL);
+    if (pvDst)
+        memcpy(pvDst, pvSrc, cb);
+    return pvDst;
+}
+
+
+RTDECL(void *) RTMemEfDupExNP(const void *pvSrc, size_t cbSrc, size_t cbExtra, const char *pszTag) RT_NO_THROW_DEF
+{
+    void *pvDst = RTMemEfAlloc(cbSrc + cbExtra, pszTag, NULL, 0, NULL);
+    if (pvDst)
+    {
+        memcpy(pvDst, pvSrc, cbSrc);
+        memset((uint8_t *)pvDst + cbSrc, 0, cbExtra);
+    }
+    return pvDst;
+}
+
diff --git a/src/VBox/Runtime/r0drv/alloc-r0drv.cpp b/src/VBox/Runtime/r0drv/alloc-r0drv.cpp
new file mode 100644
index 00000000..2b8c9abb
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/alloc-r0drv.cpp
@@ -0,0 +1,476 @@
+/* $Id: alloc-r0drv.cpp $ */
+/** @file
+ * IPRT - Memory Allocation, Ring-0 Driver.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTMEM_NO_WRAP_TO_EF_APIS
+#include <iprt/mem.h>
+#include "internal/iprt.h"
+
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#ifdef RT_MORE_STRICT
+# include <iprt/mp.h>
+#endif
+#include <iprt/param.h>
+#include <iprt/string.h>
+#include <iprt/thread.h>
+#include "r0drv/alloc-r0drv.h"
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+#ifdef RT_STRICT
+# define RTR0MEM_STRICT
+#endif
+
+#ifdef RTR0MEM_STRICT
+# define RTR0MEM_FENCE_EXTRA    16
+#else
+# define RTR0MEM_FENCE_EXTRA    0
+#endif
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+#ifdef RTR0MEM_STRICT
+/** Fence data. */
+static uint8_t const g_abFence[RTR0MEM_FENCE_EXTRA] =
+{
+    0x77, 0x88, 0x66, 0x99,  0x55, 0xaa, 0x44, 0xbb,
+    0x33, 0xcc, 0x22, 0xdd,  0x11, 0xee, 0x00, 0xff
+};
+#endif
+
+
+/**
+ * Wrapper around rtR0MemAllocEx.
+ *
+ * @returns Pointer to the allocated memory block header.
+ * @param   cb                  The number of bytes to allocate (sans header).
+ * @param   fFlags              The allocation flags.
+ */
+DECLINLINE(PRTMEMHDR) rtR0MemAlloc(size_t cb, uint32_t fFlags)
+{
+    PRTMEMHDR pHdr;
+    int rc = rtR0MemAllocEx(cb, fFlags, &pHdr);
+    if (RT_FAILURE(rc))
+        return NULL;
+    return pHdr;
+}
+
+
+RTDECL(void *)  RTMemTmpAllocTag(size_t cb, const char *pszTag) RT_NO_THROW_DEF
+{
+    return RTMemAllocTag(cb, pszTag);
+}
+RT_EXPORT_SYMBOL(RTMemTmpAllocTag);
+
+
+RTDECL(void *)  RTMemTmpAllocZTag(size_t cb, const char *pszTag) RT_NO_THROW_DEF
+{
+    return RTMemAllocZTag(cb, pszTag);
+}
+RT_EXPORT_SYMBOL(RTMemTmpAllocZTag);
+
+
+RTDECL(void)    RTMemTmpFree(void *pv) RT_NO_THROW_DEF
+{
+    return RTMemFree(pv);
+}
+RT_EXPORT_SYMBOL(RTMemTmpFree);
+
+
+RTDECL(void)    RTMemTmpFreeZ(void *pv, size_t cb) RT_NO_THROW_DEF
+{
+    return RTMemFreeZ(pv, cb);
+}
+RT_EXPORT_SYMBOL(RTMemTmpFreeZ);
+
+
+
+
+
+RTDECL(void *)  RTMemAllocTag(size_t cb, const char *pszTag) RT_NO_THROW_DEF
+{
+    PRTMEMHDR pHdr;
+    RT_ASSERT_INTS_ON();
+    RT_NOREF_PV(pszTag);
+
+    pHdr = rtR0MemAlloc(cb + RTR0MEM_FENCE_EXTRA, 0);
+    if (pHdr)
+    {
+#ifdef RTR0MEM_STRICT
+        pHdr->cbReq = (uint32_t)cb; Assert(pHdr->cbReq == cb);
+        memcpy((uint8_t *)(pHdr + 1) + cb, &g_abFence[0], RTR0MEM_FENCE_EXTRA);
+#endif
+        return pHdr + 1;
+    }
+    return NULL;
+}
+RT_EXPORT_SYMBOL(RTMemAllocTag);
+
+
+RTDECL(void *)  RTMemAllocZTag(size_t cb, const char *pszTag) RT_NO_THROW_DEF
+{
+    PRTMEMHDR pHdr;
+    RT_ASSERT_INTS_ON();
+    RT_NOREF_PV(pszTag);
+
+    pHdr = rtR0MemAlloc(cb + RTR0MEM_FENCE_EXTRA, RTMEMHDR_FLAG_ZEROED);
+    if (pHdr)
+    {
+#ifdef RTR0MEM_STRICT
+        pHdr->cbReq = (uint32_t)cb; Assert(pHdr->cbReq == cb);
+        memcpy((uint8_t *)(pHdr + 1) + cb, &g_abFence[0], RTR0MEM_FENCE_EXTRA);
+        return memset(pHdr + 1, 0, cb);
+#else
+        return memset(pHdr + 1, 0, pHdr->cb);
+#endif
+    }
+    return NULL;
+}
+RT_EXPORT_SYMBOL(RTMemAllocZTag);
+
+
+RTDECL(void *) RTMemAllocVarTag(size_t cbUnaligned, const char *pszTag)
+{
+    size_t cbAligned;
+    if (cbUnaligned >= 16)
+        cbAligned = RT_ALIGN_Z(cbUnaligned, 16);
+    else
+        cbAligned = RT_ALIGN_Z(cbUnaligned, sizeof(void *));
+    return RTMemAllocTag(cbAligned, pszTag);
+}
+RT_EXPORT_SYMBOL(RTMemAllocVarTag);
+
+
+RTDECL(void *) RTMemAllocZVarTag(size_t cbUnaligned, const char *pszTag)
+{
+    size_t cbAligned;
+    if (cbUnaligned >= 16)
+        cbAligned = RT_ALIGN_Z(cbUnaligned, 16);
+    else
+        cbAligned = RT_ALIGN_Z(cbUnaligned, sizeof(void *));
+    return RTMemAllocZTag(cbAligned, pszTag);
+}
+RT_EXPORT_SYMBOL(RTMemAllocZVarTag);
+
+
+RTDECL(void *) RTMemReallocTag(void *pvOld, size_t cbNew, const char *pszTag) RT_NO_THROW_DEF
+{
+    PRTMEMHDR pHdrOld;
+
+    /* Free. */
+    if (!cbNew && pvOld)
+    {
+        RTMemFree(pvOld);
+        return NULL;
+    }
+
+    /* Alloc. */
+    if (!pvOld)
+        return RTMemAllocTag(cbNew, pszTag);
+
+    /*
+     * Realloc.
+     */
+    pHdrOld = (PRTMEMHDR)pvOld - 1;
+    RT_ASSERT_PREEMPTIBLE();
+
+    if (pHdrOld->u32Magic == RTMEMHDR_MAGIC)
+    {
+        PRTMEMHDR pHdrNew;
+
+        /* If there is sufficient space in the old block and we don't cause
+           substantial internal fragmentation, reuse the old block. */
+        if (   pHdrOld->cb >= cbNew + RTR0MEM_FENCE_EXTRA
+            && pHdrOld->cb - (cbNew + RTR0MEM_FENCE_EXTRA) <= 128)
+        {
+            pHdrOld->cbReq = (uint32_t)cbNew; Assert(pHdrOld->cbReq == cbNew);
+#ifdef RTR0MEM_STRICT
+            memcpy((uint8_t *)(pHdrOld + 1) + cbNew, &g_abFence[0], RTR0MEM_FENCE_EXTRA);
+#endif
+            return pvOld;
+        }
+
+        /* Allocate a new block and copy over the content. */
+        pHdrNew = rtR0MemAlloc(cbNew + RTR0MEM_FENCE_EXTRA, 0);
+        if (pHdrNew)
+        {
+            size_t cbCopy = RT_MIN(pHdrOld->cb, pHdrNew->cb);
+            memcpy(pHdrNew + 1, pvOld, cbCopy);
+#ifdef RTR0MEM_STRICT
+            pHdrNew->cbReq = (uint32_t)cbNew; Assert(pHdrNew->cbReq == cbNew);
+            memcpy((uint8_t *)(pHdrNew + 1) + cbNew, &g_abFence[0], RTR0MEM_FENCE_EXTRA);
+            AssertReleaseMsg(!memcmp((uint8_t *)(pHdrOld + 1) + pHdrOld->cbReq, &g_abFence[0], RTR0MEM_FENCE_EXTRA),
+                             ("pHdr=%p pvOld=%p cbReq=%u cb=%u cbNew=%zu fFlags=%#x\n"
+                              "fence:    %.*Rhxs\n"
+                              "expected: %.*Rhxs\n",
+                              pHdrOld, pvOld, pHdrOld->cbReq, pHdrOld->cb, cbNew, pHdrOld->fFlags,
+                              RTR0MEM_FENCE_EXTRA, (uint8_t *)(pHdrOld + 1) + pHdrOld->cbReq,
+                              RTR0MEM_FENCE_EXTRA, &g_abFence[0]));
+#endif
+            rtR0MemFree(pHdrOld);
+            return pHdrNew + 1;
+        }
+    }
+    else
+        AssertMsgFailed(("pHdrOld->u32Magic=%RX32 pvOld=%p cbNew=%#zx\n", pHdrOld->u32Magic, pvOld, cbNew));
+
+    return NULL;
+}
+RT_EXPORT_SYMBOL(RTMemReallocTag);
+
+
+RTDECL(void) RTMemFree(void *pv) RT_NO_THROW_DEF
+{
+    PRTMEMHDR pHdr;
+    RT_ASSERT_INTS_ON();
+
+    if (!pv)
+        return;
+    pHdr = (PRTMEMHDR)pv - 1;
+    if (pHdr->u32Magic == RTMEMHDR_MAGIC)
+    {
+        Assert(!(pHdr->fFlags & RTMEMHDR_FLAG_ALLOC_EX));
+        Assert(!(pHdr->fFlags & RTMEMHDR_FLAG_EXEC));
+#ifdef RTR0MEM_STRICT
+        AssertReleaseMsg(!memcmp((uint8_t *)(pHdr + 1) + pHdr->cbReq, &g_abFence[0], RTR0MEM_FENCE_EXTRA),
+                         ("pHdr=%p pv=%p cbReq=%u cb=%u fFlags=%#x\n"
+                          "fence:    %.*Rhxs\n"
+                          "expected: %.*Rhxs\n",
+                          pHdr, pv, pHdr->cbReq, pHdr->cb, pHdr->fFlags,
+                          RTR0MEM_FENCE_EXTRA, (uint8_t *)(pHdr + 1) + pHdr->cbReq,
+                          RTR0MEM_FENCE_EXTRA, &g_abFence[0]));
+#endif
+        rtR0MemFree(pHdr);
+    }
+    else
+        AssertMsgFailed(("pHdr->u32Magic=%RX32 pv=%p\n", pHdr->u32Magic, pv));
+}
+RT_EXPORT_SYMBOL(RTMemFree);
+
+
+RTDECL(void) RTMemFreeZ(void *pv, size_t cb) RT_NO_THROW_DEF
+{
+    PRTMEMHDR pHdr;
+    RT_ASSERT_INTS_ON();
+
+    if (!pv)
+        return;
+    pHdr = (PRTMEMHDR)pv - 1;
+    if (pHdr->u32Magic == RTMEMHDR_MAGIC)
+    {
+        Assert(!(pHdr->fFlags & RTMEMHDR_FLAG_ALLOC_EX));
+        Assert(!(pHdr->fFlags & RTMEMHDR_FLAG_EXEC));
+#ifdef RTR0MEM_STRICT
+        AssertReleaseMsg(!memcmp((uint8_t *)(pHdr + 1) + pHdr->cbReq, &g_abFence[0], RTR0MEM_FENCE_EXTRA),
+                         ("pHdr=%p pv=%p cbReq=%u cb=%u fFlags=%#x\n"
+                          "fence:    %.*Rhxs\n"
+                          "expected: %.*Rhxs\n",
+                          pHdr, pv, pHdr->cbReq, pHdr->cb, pHdr->fFlags,
+                          RTR0MEM_FENCE_EXTRA, (uint8_t *)(pHdr + 1) + pHdr->cbReq,
+                          RTR0MEM_FENCE_EXTRA, &g_abFence[0]));
+#endif
+        AssertMsgStmt(cb == pHdr->cbReq, ("cb=%#zx cbReq=%#x\n", cb, pHdr->cbReq), cb = pHdr->cbReq);
+        RT_BZERO(pv, cb);
+        rtR0MemFree(pHdr);
+    }
+    else
+        AssertMsgFailed(("pHdr->u32Magic=%RX32 pv=%p\n", pHdr->u32Magic, pv));
+}
+RT_EXPORT_SYMBOL(RTMemFreeZ);
+
+
+
+
+
+
+RTDECL(void *)    RTMemExecAllocTag(size_t cb, const char *pszTag) RT_NO_THROW_DEF
+{
+    PRTMEMHDR pHdr;
+#ifdef RT_OS_SOLARIS /** @todo figure out why */
+    RT_ASSERT_INTS_ON();
+#else
+    RT_ASSERT_PREEMPTIBLE();
+#endif
+    RT_NOREF_PV(pszTag);
+
+
+    pHdr = rtR0MemAlloc(cb + RTR0MEM_FENCE_EXTRA, RTMEMHDR_FLAG_EXEC);
+    if (pHdr)
+    {
+#ifdef RTR0MEM_STRICT
+        pHdr->cbReq = (uint32_t)cb; Assert(pHdr->cbReq == cb);
+        memcpy((uint8_t *)(pHdr + 1) + cb, &g_abFence[0], RTR0MEM_FENCE_EXTRA);
+#endif
+        return pHdr + 1;
+    }
+    return NULL;
+}
+RT_EXPORT_SYMBOL(RTMemExecAllocTag);
+
+
+RTDECL(void)      RTMemExecFree(void *pv, size_t cb) RT_NO_THROW_DEF
+{
+    PRTMEMHDR pHdr;
+    RT_ASSERT_INTS_ON();
+    RT_NOREF_PV(cb);
+
+    if (!pv)
+        return;
+    pHdr = (PRTMEMHDR)pv - 1;
+    if (pHdr->u32Magic == RTMEMHDR_MAGIC)
+    {
+        Assert(!(pHdr->fFlags & RTMEMHDR_FLAG_ALLOC_EX));
+#ifdef RTR0MEM_STRICT
+        AssertReleaseMsg(!memcmp((uint8_t *)(pHdr + 1) + pHdr->cbReq, &g_abFence[0], RTR0MEM_FENCE_EXTRA),
+                         ("pHdr=%p pv=%p cbReq=%u cb=%u fFlags=%#x\n"
+                          "fence:    %.*Rhxs\n"
+                          "expected: %.*Rhxs\n",
+                          pHdr, pv, pHdr->cbReq, pHdr->cb, pHdr->fFlags,
+                          RTR0MEM_FENCE_EXTRA, (uint8_t *)(pHdr + 1) + pHdr->cbReq,
+                          RTR0MEM_FENCE_EXTRA, &g_abFence[0]));
+#endif
+        rtR0MemFree(pHdr);
+    }
+    else
+        AssertMsgFailed(("pHdr->u32Magic=%RX32 pv=%p\n", pHdr->u32Magic, pv));
+}
+RT_EXPORT_SYMBOL(RTMemExecFree);
+
+
+
+
+RTDECL(int) RTMemAllocExTag(size_t cb, size_t cbAlignment, uint32_t fFlags, const char *pszTag, void **ppv) RT_NO_THROW_DEF
+{
+    uint32_t    fHdrFlags = RTMEMHDR_FLAG_ALLOC_EX;
+    PRTMEMHDR   pHdr;
+    int         rc;
+    RT_NOREF_PV(pszTag);
+
+    RT_ASSERT_PREEMPT_CPUID_VAR();
+    if (!(fFlags & RTMEMALLOCEX_FLAGS_ANY_CTX_ALLOC))
+        RT_ASSERT_INTS_ON();
+
+    /*
+     * Fake up some alignment support.
+     */
+    AssertMsgReturn(cbAlignment <= sizeof(void *), ("%zu (%#x)\n", cbAlignment, cbAlignment), VERR_UNSUPPORTED_ALIGNMENT);
+    if (cb < cbAlignment)
+        cb = cbAlignment;
+
+    /*
+     * Validate and convert flags.
+     */
+    AssertMsgReturn(!(fFlags & ~RTMEMALLOCEX_FLAGS_VALID_MASK_R0), ("%#x\n", fFlags), VERR_INVALID_PARAMETER);
+    if (fFlags & RTMEMALLOCEX_FLAGS_ZEROED)
+        fHdrFlags |= RTMEMHDR_FLAG_ZEROED;
+    if (fFlags & RTMEMALLOCEX_FLAGS_EXEC)
+        fHdrFlags |= RTMEMHDR_FLAG_EXEC;
+    if (fFlags & RTMEMALLOCEX_FLAGS_ANY_CTX_ALLOC)
+        fHdrFlags |= RTMEMHDR_FLAG_ANY_CTX_ALLOC;
+    if (fFlags & RTMEMALLOCEX_FLAGS_ANY_CTX_FREE)
+        fHdrFlags |= RTMEMHDR_FLAG_ANY_CTX_FREE;
+
+    /*
+     * Do the allocation.
+     */
+    rc = rtR0MemAllocEx(cb + RTR0MEM_FENCE_EXTRA, fHdrFlags, &pHdr);
+    if (RT_SUCCESS(rc))
+    {
+        void *pv;
+
+        Assert(pHdr->cbReq  == cb + RTR0MEM_FENCE_EXTRA);
+        Assert((pHdr->fFlags & fFlags) == fFlags);
+
+        /*
+         * Calc user pointer, initialize the memory if requested, and if
+         * memory strictness is enable set up the fence.
+         */
+        pv = pHdr + 1;
+        *ppv = pv;
+        if (fFlags & RTMEMHDR_FLAG_ZEROED)
+            memset(pv, 0, pHdr->cb);
+
+#ifdef RTR0MEM_STRICT
+        pHdr->cbReq = (uint32_t)cb;
+        memcpy((uint8_t *)pv + cb, &g_abFence[0], RTR0MEM_FENCE_EXTRA);
+#endif
+    }
+    else if (rc == VERR_NO_MEMORY && (fFlags & RTMEMALLOCEX_FLAGS_EXEC))
+        rc = VERR_NO_EXEC_MEMORY;
+
+    RT_ASSERT_PREEMPT_CPUID();
+    return rc;
+}
+RT_EXPORT_SYMBOL(RTMemAllocExTag);
+
+
+RTDECL(void) RTMemFreeEx(void *pv, size_t cb) RT_NO_THROW_DEF
+{
+    PRTMEMHDR pHdr;
+    RT_NOREF_PV(cb);
+
+    if (!pv)
+        return;
+
+    AssertPtr(pv);
+    pHdr = (PRTMEMHDR)pv - 1;
+    if (pHdr->u32Magic == RTMEMHDR_MAGIC)
+    {
+        RT_ASSERT_PREEMPT_CPUID_VAR();
+
+        Assert(pHdr->fFlags & RTMEMHDR_FLAG_ALLOC_EX);
+        if (!(pHdr->fFlags & RTMEMHDR_FLAG_ANY_CTX_FREE))
+            RT_ASSERT_INTS_ON();
+        AssertMsg(pHdr->cbReq == cb, ("cbReq=%zu cb=%zu\n", pHdr->cb, cb));
+
+#ifdef RTR0MEM_STRICT
+        AssertReleaseMsg(!memcmp((uint8_t *)(pHdr + 1) + pHdr->cbReq, &g_abFence[0], RTR0MEM_FENCE_EXTRA),
+                         ("pHdr=%p pv=%p cbReq=%u cb=%u fFlags=%#x\n"
+                          "fence:    %.*Rhxs\n"
+                          "expected: %.*Rhxs\n",
+                          pHdr, pv, pHdr->cbReq, pHdr->cb, pHdr->fFlags,
+                          RTR0MEM_FENCE_EXTRA, (uint8_t *)(pHdr + 1) + pHdr->cbReq,
+                          RTR0MEM_FENCE_EXTRA, &g_abFence[0]));
+#endif
+        rtR0MemFree(pHdr);
+        RT_ASSERT_PREEMPT_CPUID();
+    }
+    else
+        AssertMsgFailed(("pHdr->u32Magic=%RX32 pv=%p\n", pHdr->u32Magic, pv));
+}
+RT_EXPORT_SYMBOL(RTMemFreeEx);
+
diff --git a/src/VBox/Runtime/r0drv/alloc-r0drv.h b/src/VBox/Runtime/r0drv/alloc-r0drv.h
new file mode 100644
index 00000000..df91750a
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/alloc-r0drv.h
@@ -0,0 +1,107 @@
+/* $Id: alloc-r0drv.h $ */
+/** @file
+ * IPRT - Memory Allocation, Ring-0 Driver.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+#ifndef IPRT_INCLUDED_SRC_r0drv_alloc_r0drv_h
+#define IPRT_INCLUDED_SRC_r0drv_alloc_r0drv_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <iprt/cdefs.h>
+#include <iprt/types.h>
+#include <iprt/mem.h>
+#include "internal/magics.h"
+
+RT_C_DECLS_BEGIN
+
+/**
+ * Header which heading all memory blocks.
+ */
+typedef struct RTMEMHDR
+{
+    /** Magic (RTMEMHDR_MAGIC). */
+    uint32_t    u32Magic;
+    /** Block flags (RTMEMHDR_FLAG_*). */
+    uint32_t    fFlags;
+    /** The actual size of the block, header not included. */
+    uint32_t    cb;
+    /** The requested allocation size. */
+    uint32_t    cbReq;
+} RTMEMHDR, *PRTMEMHDR;
+
+
+/** @name RTMEMHDR::fFlags.
+ * @{ */
+/** Clear the allocated memory. */
+#define RTMEMHDR_FLAG_ZEROED        RT_BIT(0)
+/** Executable flag. */
+#define RTMEMHDR_FLAG_EXEC          RT_BIT(1)
+/** Use allocation method suitable for any context. */
+#define RTMEMHDR_FLAG_ANY_CTX_ALLOC RT_BIT(2)
+/** Use allocation method which allow for freeing in any context. */
+#define RTMEMHDR_FLAG_ANY_CTX_FREE  RT_BIT(3)
+/** Both alloc and free in any context (or we're just darn lazy). */
+#define RTMEMHDR_FLAG_ANY_CTX       (RTMEMHDR_FLAG_ANY_CTX_ALLOC | RTMEMHDR_FLAG_ANY_CTX_FREE)
+/** Indicate that it was allocated by rtR0MemAllocExTag. */
+#define RTMEMHDR_FLAG_ALLOC_EX      RT_BIT(4)
+#ifdef RT_OS_LINUX
+/** Linux: Allocated using vm_area hacks. */
+# define RTMEMHDR_FLAG_EXEC_VM_AREA RT_BIT(29)
+/** Linux: Allocated from the special heap for executable memory. */
+# define RTMEMHDR_FLAG_EXEC_HEAP    RT_BIT(30)
+/** Linux: Allocated by kmalloc() instead of vmalloc(). */
+# define RTMEMHDR_FLAG_KMALLOC      RT_BIT(31)
+#elif defined(RT_OS_WINDOWS)
+/** Windows: Untagged allocation by ExAllocatePool, freed using ExFreePool. */
+# define RTMEMHDR_FLAG_UNTAGGED     RT_BIT(31)
+#endif
+/** @} */
+
+
+/**
+ * Heap allocation back end for ring-0.
+ *
+ * @returns IPRT status code.  VERR_NO_MEMORY suffices for RTMEMHDR_FLAG_EXEC,
+ *          the caller will change it to VERR_NO_EXEC_MEMORY when appropriate.
+ *
+ * @param   cb          The amount of memory requested by the user.  This does
+ *                      not include the header.
+ * @param   fFlags      The allocation flags and more.  These should be
+ *                      assigned to RTMEMHDR::fFlags together with any flags
+ *                      the backend might be using.
+ * @param   ppHdr       Where to return the memory header on success.
+ */
+DECLHIDDEN(int)     rtR0MemAllocEx(size_t cb, uint32_t fFlags, PRTMEMHDR *ppHdr);
+
+/**
+ * Free memory allocated by rtR0MemAllocEx.
+ * @param   pHdr        The memory block to free.  (Never NULL.)
+ */
+DECLHIDDEN(void)    rtR0MemFree(PRTMEMHDR pHdr);
+
+RT_C_DECLS_END
+#endif /* !IPRT_INCLUDED_SRC_r0drv_alloc_r0drv_h */
+
diff --git a/src/VBox/Runtime/r0drv/darwin/Makefile.kup b/src/VBox/Runtime/r0drv/darwin/Makefile.kup
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/Makefile.kup
diff --git a/src/VBox/Runtime/r0drv/darwin/RTLogWriteDebugger-r0drv-darwin.cpp b/src/VBox/Runtime/r0drv/darwin/RTLogWriteDebugger-r0drv-darwin.cpp
new file mode 100644
index 00000000..86ff6acd
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/RTLogWriteDebugger-r0drv-darwin.cpp
@@ -0,0 +1,42 @@
+/* $Id: RTLogWriteDebugger-r0drv-darwin.cpp $ */
+/** @file
+ * IPRT - Log To Debugger, Ring-0 Driver, Darwin.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-darwin-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/log.h>
+
+
+RTDECL(void) RTLogWriteDebugger(const char *pch, size_t cb)
+{
+    IPRT_DARWIN_SAVE_EFL_AC();
+    kprintf("%.*s", (int)cb, pch);
+    IPRT_DARWIN_RESTORE_EFL_AC();
+}
+
diff --git a/src/VBox/Runtime/r0drv/darwin/RTLogWriteStdOut-r0drv-darwin.cpp b/src/VBox/Runtime/r0drv/darwin/RTLogWriteStdOut-r0drv-darwin.cpp
new file mode 100644
index 00000000..b9400f47
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/RTLogWriteStdOut-r0drv-darwin.cpp
@@ -0,0 +1,42 @@
+/* $Id: RTLogWriteStdOut-r0drv-darwin.cpp $ */
+/** @file
+ * IPRT - Log To StdOut, Ring-0 Driver, Darwin.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-darwin-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/log.h>
+
+
+RTDECL(void) RTLogWriteStdOut(const char *pch, size_t cb)
+{
+    IPRT_DARWIN_SAVE_EFL_AC();
+    printf("%.*s", (int)cb, pch);
+    IPRT_DARWIN_RESTORE_EFL_AC();
+}
+
diff --git a/src/VBox/Runtime/r0drv/darwin/alloc-r0drv-darwin.cpp b/src/VBox/Runtime/r0drv/darwin/alloc-r0drv-darwin.cpp
new file mode 100644
index 00000000..822c090a
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/alloc-r0drv-darwin.cpp
@@ -0,0 +1,191 @@
+/* $Id: alloc-r0drv-darwin.cpp $ */
+/** @file
+ * IPRT - Memory Allocation, Ring-0 Driver, Darwin.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations" /* (IOMallocContiguous et al are deprecated) */
+#include "the-darwin-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/mem.h>
+#include <iprt/memobj.h>
+
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+#include <iprt/thread.h>
+#include "r0drv/alloc-r0drv.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Extended header used for headers marked with RTMEMHDR_FLAG_EXEC.
+ *
+ * This is used with allocating executable memory, for things like generated
+ * code and loaded modules.
+ */
+typedef struct RTMEMDARWINHDREX
+{
+    /** The associated memory object. */
+    RTR0MEMOBJ          hMemObj;
+    /** Alignment padding. */
+    uint8_t             abPadding[ARCH_BITS == 32 ? 12 : 8];
+    /** The header we present to the generic API. */
+    RTMEMHDR            Hdr;
+} RTMEMDARWINHDREX;
+AssertCompileSize(RTMEMDARWINHDREX, 32);
+/** Pointer to an extended memory header. */
+typedef RTMEMDARWINHDREX *PRTMEMDARWINHDREX;
+
+
+/**
+ * OS specific allocation function.
+ */
+DECLHIDDEN(int) rtR0MemAllocEx(size_t cb, uint32_t fFlags, PRTMEMHDR *ppHdr)
+{
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    if (RT_UNLIKELY(fFlags & RTMEMHDR_FLAG_ANY_CTX))
+        return VERR_NOT_SUPPORTED;
+
+    PRTMEMHDR pHdr;
+    if (fFlags & RTMEMHDR_FLAG_EXEC)
+    {
+        RTR0MEMOBJ hMemObj;
+        int rc = RTR0MemObjAllocPage(&hMemObj, cb + sizeof(RTMEMDARWINHDREX), true /*fExecutable*/);
+        if (RT_FAILURE(rc))
+        {
+            IPRT_DARWIN_RESTORE_EFL_AC();
+            return rc;
+        }
+        PRTMEMDARWINHDREX pExHdr = (PRTMEMDARWINHDREX)RTR0MemObjAddress(hMemObj);
+        pExHdr->hMemObj = hMemObj;
+        pHdr = &pExHdr->Hdr;
+#if 1 /*fExecutable isn't currently honored above. */
+        rc = RTR0MemObjProtect(hMemObj, 0, RTR0MemObjSize(hMemObj), RTMEM_PROT_READ | RTMEM_PROT_WRITE | RTMEM_PROT_EXEC);
+        AssertRC(rc);
+#endif
+    }
+    else
+    {
+        pHdr = (PRTMEMHDR)IOMalloc(cb + sizeof(*pHdr));
+        if (RT_UNLIKELY(!pHdr))
+        {
+            printf("rtR0MemAllocEx(%#zx, %#x) failed\n", cb + sizeof(*pHdr), fFlags);
+            IPRT_DARWIN_RESTORE_EFL_AC();
+            return VERR_NO_MEMORY;
+        }
+    }
+
+    pHdr->u32Magic  = RTMEMHDR_MAGIC;
+    pHdr->fFlags    = fFlags;
+    pHdr->cb        = cb;
+    pHdr->cbReq     = cb;
+    *ppHdr = pHdr;
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * OS specific free function.
+ */
+DECLHIDDEN(void) rtR0MemFree(PRTMEMHDR pHdr)
+{
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    pHdr->u32Magic += 1;
+    if (pHdr->fFlags & RTMEMHDR_FLAG_EXEC)
+    {
+        PRTMEMDARWINHDREX pExHdr = RT_FROM_MEMBER(pHdr, RTMEMDARWINHDREX, Hdr);
+        int rc = RTR0MemObjFree(pExHdr->hMemObj, false /*fFreeMappings*/);
+        AssertRC(rc);
+    }
+    else
+        IOFree(pHdr, pHdr->cb + sizeof(*pHdr));
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+}
+
+
+RTR0DECL(void *) RTMemContAlloc(PRTCCPHYS pPhys, size_t cb)
+{
+    /*
+     * validate input.
+     */
+    AssertPtr(pPhys);
+    Assert(cb > 0);
+    RT_ASSERT_PREEMPTIBLE();
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    /*
+     * Allocate the memory and ensure that the API is still providing
+     * memory that's always below 4GB.
+     */
+    cb = RT_ALIGN_Z(cb, PAGE_SIZE);
+    IOPhysicalAddress PhysAddr;
+    void *pv = IOMallocContiguous(cb, PAGE_SIZE, &PhysAddr);
+    if (pv)
+    {
+        if (PhysAddr + (cb - 1) <= (IOPhysicalAddress)0xffffffff)
+        {
+            if (!((uintptr_t)pv & PAGE_OFFSET_MASK))
+            {
+                *pPhys = PhysAddr;
+                IPRT_DARWIN_RESTORE_EFL_AC();
+                return pv;
+            }
+            AssertMsgFailed(("IOMallocContiguous didn't return a page aligned address - %p!\n", pv));
+        }
+        else
+            AssertMsgFailed(("IOMallocContiguous returned high address! PhysAddr=%RX64 cb=%#zx\n", (uint64_t)PhysAddr, cb));
+        IOFreeContiguous(pv, cb);
+    }
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return NULL;
+}
+
+
+RTR0DECL(void) RTMemContFree(void *pv, size_t cb)
+{
+    RT_ASSERT_PREEMPTIBLE();
+    if (pv)
+    {
+        Assert(cb > 0);
+        AssertMsg(!((uintptr_t)pv & PAGE_OFFSET_MASK), ("pv=%p\n", pv));
+        IPRT_DARWIN_SAVE_EFL_AC();
+
+        cb = RT_ALIGN_Z(cb, PAGE_SIZE);
+        IOFreeContiguous(pv, cb);
+
+        IPRT_DARWIN_RESTORE_EFL_AC();
+    }
+}
+
diff --git a/src/VBox/Runtime/r0drv/darwin/assert-r0drv-darwin.cpp b/src/VBox/Runtime/r0drv/darwin/assert-r0drv-darwin.cpp
new file mode 100644
index 00000000..432bf46c
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/assert-r0drv-darwin.cpp
@@ -0,0 +1,77 @@
+/* $Id: assert-r0drv-darwin.cpp $ */
+/** @file
+ * IPRT -  Assertion Workers, Ring-0 Drivers, Darwin.
+ */
+
+/*
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-darwin-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/assert.h>
+
+#include <iprt/asm.h>
+#include <iprt/log.h>
+#include <iprt/stdarg.h>
+#include <iprt/string.h>
+
+#include "internal/assert.h"
+
+
+DECLHIDDEN(void) rtR0AssertNativeMsg1(const char *pszExpr, unsigned uLine, const char *pszFile, const char *pszFunction)
+{
+    IPRT_DARWIN_SAVE_EFL_AC();
+    kprintf("\r\n!!Assertion Failed!!\r\n"
+            "Expression: %s\r\n"
+            "Location  : %s(%u) %s\r\n",
+            pszExpr, pszFile, uLine, pszFunction);
+    printf("\r\n!!Assertion Failed!!\r\n"
+           "Expression: %s\r\n"
+           "Location  : %s(%u) %s\r\n",
+           pszExpr, pszFile, uLine, pszFunction);
+    IPRT_DARWIN_RESTORE_EFL_AC();
+}
+
+
+DECLHIDDEN(void) rtR0AssertNativeMsg2V(bool fInitial, const char *pszFormat, va_list va)
+{
+    IPRT_DARWIN_SAVE_EFL_AC();
+    char szMsg[256];
+
+    RTStrPrintfV(szMsg, sizeof(szMsg) - 1, pszFormat, va);
+    szMsg[sizeof(szMsg) - 1] = '\0';
+    kprintf("%s", szMsg);
+    printf("%s", szMsg);
+
+    NOREF(fInitial);
+    IPRT_DARWIN_RESTORE_EFL_AC();
+}
+
+
+RTR0DECL(void) RTR0AssertPanicSystem(void)
+{
+    panic("%s%s", g_szRTAssertMsg1, g_szRTAssertMsg2);
+}
+
diff --git a/src/VBox/Runtime/r0drv/darwin/dbgkrnlinfo-r0drv-darwin.cpp b/src/VBox/Runtime/r0drv/darwin/dbgkrnlinfo-r0drv-darwin.cpp
new file mode 100644
index 00000000..56226b96
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/dbgkrnlinfo-r0drv-darwin.cpp
@@ -0,0 +1,1551 @@
+/* $Id: dbgkrnlinfo-r0drv-darwin.cpp $ */
+/** @file
+ * IPRT - Kernel Debug Information, R0 Driver, Darwin.
+ */
+
+/*
+ * Copyright (C) 2011-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#ifdef IN_RING0
+# include "the-darwin-kernel.h"
+# include <sys/kauth.h>
+RT_C_DECLS_BEGIN /* Buggy 10.4 headers, fixed in 10.5. */
+# include <sys/kpi_mbuf.h>
+# include <net/kpi_interfacefilter.h>
+# include <sys/kpi_socket.h>
+# include <sys/kpi_socketfilter.h>
+RT_C_DECLS_END
+# include <sys/buf.h>
+# include <sys/vm.h>
+# include <sys/vnode_if.h>
+/*# include <sys/sysctl.h>*/
+# include <sys/systm.h>
+# include <vfs/vfs_support.h>
+/*# include <miscfs/specfs/specdev.h>*/
+#else
+# include <stdio.h> /* for printf */
+#endif
+
+#if !defined(IN_RING0) && !defined(DOXYGEN_RUNNING) /* A linking tweak for the testcase: */
+# include <iprt/cdefs.h>
+# undef  RTR0DECL
+# define RTR0DECL(type) DECLHIDDEN(type) RTCALL
+#endif
+
+#include "internal/iprt.h"
+#include <iprt/dbg.h>
+
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/assert.h>
+#include <iprt/file.h>
+#include <iprt/log.h>
+#include <iprt/mem.h>
+#include <iprt/string.h>
+#include <iprt/formats/mach-o.h>
+#include "internal/magics.h"
+
+/** @def MY_CPU_TYPE
+ * The CPU type targeted by the compiler. */
+/** @def MY_CPU_TYPE
+ * The "ALL" CPU subtype targeted by the compiler. */
+/** @def MY_MACHO_HEADER
+ * The Mach-O header targeted by the compiler.  */
+/** @def MY_MACHO_MAGIC
+ * The Mach-O header magic we're targeting.  */
+/** @def MY_SEGMENT_COMMAND
+ * The segment command targeted by the compiler.  */
+/** @def MY_SECTION
+ * The section struture targeted by the compiler.  */
+/** @def MY_NLIST
+ * The symbol table entry targeted by the compiler.  */
+#ifdef RT_ARCH_X86
+# define MY_CPU_TYPE            CPU_TYPE_I386
+# define MY_CPU_SUBTYPE_ALL     CPU_SUBTYPE_I386_ALL
+# define MY_MACHO_HEADER        mach_header_32_t
+# define MY_MACHO_MAGIC         IMAGE_MACHO32_SIGNATURE
+# define MY_SEGMENT_COMMAND     segment_command_32_t
+# define MY_SECTION             section_32_t
+# define MY_NLIST               macho_nlist_32_t
+
+#elif defined(RT_ARCH_AMD64)
+# define MY_CPU_TYPE            CPU_TYPE_X86_64
+# define MY_CPU_SUBTYPE_ALL     CPU_SUBTYPE_X86_64_ALL
+# define MY_MACHO_HEADER        mach_header_64_t
+# define MY_MACHO_MAGIC         IMAGE_MACHO64_SIGNATURE
+# define MY_SEGMENT_COMMAND     segment_command_64_t
+# define MY_SECTION             section_64_t
+# define MY_NLIST               macho_nlist_64_t
+
+#else
+# error "Port me!"
+#endif
+
+/** @name Return macros for make it simpler to track down too paranoid code.
+ * @{
+ */
+#ifdef DEBUG
+# define RETURN_VERR_BAD_EXE_FORMAT \
+    do { Assert(!g_fBreakpointOnError);         return VERR_BAD_EXE_FORMAT; } while (0)
+# define RETURN_VERR_LDR_UNEXPECTED \
+    do { Assert(!g_fBreakpointOnError);         return VERR_LDR_UNEXPECTED; } while (0)
+# define RETURN_VERR_LDR_ARCH_MISMATCH \
+    do { Assert(!g_fBreakpointOnError);         return VERR_LDR_ARCH_MISMATCH; } while (0)
+#else
+# define RETURN_VERR_BAD_EXE_FORMAT     do {    return VERR_BAD_EXE_FORMAT; } while (0)
+# define RETURN_VERR_LDR_UNEXPECTED     do {    return VERR_LDR_UNEXPECTED; } while (0)
+# define RETURN_VERR_LDR_ARCH_MISMATCH  do {    return VERR_LDR_ARCH_MISMATCH; } while (0)
+#endif
+#if defined(DEBUG_bird) && !defined(IN_RING3)
+# define LOG_MISMATCH(...)                      kprintf(__VA_ARGS__)
+# define LOG_NOT_PRESENT(...)                   kprintf(__VA_ARGS__)
+# define LOG_BAD_SYM(...)                       kprintf(__VA_ARGS__)
+# define LOG_SUCCESS(...)                       kprintf(__VA_ARGS__)
+#else
+# define LOG_MISMATCH(...)                      Log((__VA_ARGS__))
+# define LOG_NOT_PRESENT(...)                   Log((__VA_ARGS__))
+# define LOG_BAD_SYM(...)                       printf(__VA_ARGS__)
+# define LOG_SUCCESS(...)                       printf(__VA_ARGS__)
+#endif
+/** @} */
+
+#define VERR_LDR_UNEXPECTED     (-641)
+
+#ifndef RT_OS_DARWIN
+# define MAC_OS_X_VERSION_MIN_REQUIRED 1050
+#endif
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Our internal representation of the mach_kernel after loading it's symbols
+ * and successfully resolving their addresses.
+ */
+typedef struct RTDBGKRNLINFOINT
+{
+    /** Magic value (RTDBGKRNLINFO_MAGIC). */
+    uint32_t            u32Magic;
+    /** Reference counter.  */
+    uint32_t volatile   cRefs;
+
+    /** Set if this is an in-memory rather than on-disk instance. */
+    bool                fIsInMem;
+    bool                afAlignment[7];
+
+    /** @name Result.
+     * @{ */
+    /** Pointer to the string table. */
+    char               *pachStrTab;
+    /** The size of the string table. */
+    uint32_t            cbStrTab;
+    /** The file offset of the string table. */
+    uint32_t            offStrTab;
+    /** The link address of the string table. */
+    uintptr_t           uStrTabLinkAddr;
+    /** Pointer to the symbol table. */
+    MY_NLIST           *paSyms;
+    /** The size of the symbol table. */
+    uint32_t            cSyms;
+    /** The file offset of the symbol table. */
+    uint32_t            offSyms;
+    /** The link address of the symbol table. */
+    uintptr_t           uSymTabLinkAddr;
+    /** The link address of the text segment. */
+    uintptr_t           uTextSegLinkAddr;
+    /** Size of the text segment. */
+    uintptr_t           cbTextSeg;
+    /** Offset between link address and actual load address of the text segment. */
+    uintptr_t           offLoad;
+    /** The minimum OS version (A.B.C; A is 16 bits, B & C each 8 bits). */
+    uint32_t            uMinOsVer;
+    /** The SDK version (A.B.C; A is 16 bits, B & C each 8 bits). */
+    uint32_t            uSdkVer;
+    /** The source version (A.B.C.D.E; A is 24 bits, the rest 10 each). */
+    uint64_t            uSrcVer;
+    /** @} */
+
+    /** @name Used during loading.
+     * @{ */
+    /** The file handle.  */
+    RTFILE              hFile;
+    /** The architecture image offset (fat_arch_t::offset). */
+    uint64_t            offArch;
+    /** The architecture image size (fat_arch_t::size). */
+    uint32_t            cbArch;
+    /** The number of load commands (mach_header_XX_t::ncmds). */
+    uint32_t            cLoadCmds;
+    /** The size of the load commands. */
+    uint32_t            cbLoadCmds;
+    /** The load commands. */
+    load_command_t     *pLoadCmds;
+    /** The number of segments. */
+    uint32_t            cSegments;
+    /** The number of sections. */
+    uint32_t            cSections;
+    /** Section pointer table (points into the load commands). */
+    MY_SEGMENT_COMMAND const *apSegments[MACHO_MAX_SECT / 2];
+    /** Load displacement table for each segment. */
+    uintptr_t          aoffLoadSegments[MACHO_MAX_SECT / 2];
+    /** Section pointer table (points into the load commands). */
+    MY_SECTION const   *apSections[MACHO_MAX_SECT];
+    /** Mapping table to quickly get to a segment from MY_NLIST::n_sect. */
+    uint8_t            auSections2Segment[MACHO_MAX_SECT];
+    /** @} */
+
+    /** Buffer space. */
+    char                abBuf[_4K];
+} RTDBGKRNLINFOINT;
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+#ifdef DEBUG
+static bool g_fBreakpointOnError = false;
+#endif
+
+
+/**
+ * Close and free up resources we no longer needs.
+ *
+ * @param   pThis               The internal scratch data.
+ */
+static void rtR0DbgKrnlDarwinLoadDone(RTDBGKRNLINFOINT *pThis)
+{
+    if (!pThis->fIsInMem)
+        RTFileClose(pThis->hFile);
+    pThis->hFile = NIL_RTFILE;
+
+    if (!pThis->fIsInMem)
+        RTMemFree(pThis->pLoadCmds);
+    pThis->pLoadCmds = NULL;
+    RT_ZERO(pThis->apSections);
+    RT_ZERO(pThis->apSegments);
+}
+
+
+/**
+ * Looks up a kernel symbol record.
+ *
+ * @returns Pointer to the symbol record or NULL if not found.
+ * @param   pThis               The internal scratch data.
+ * @param   pszSymbol           The symbol to resolve.  Automatically prefixed
+ *                              with an underscore.
+ */
+static MY_NLIST const *rtR0DbgKrnlDarwinLookupSym(RTDBGKRNLINFOINT *pThis, const char *pszSymbol)
+{
+    uint32_t const  cSyms = pThis->cSyms;
+    MY_NLIST const *pSym = pThis->paSyms;
+
+#if 1
+    /* linear search. */
+    for (uint32_t iSym = 0; iSym < cSyms; iSym++, pSym++)
+    {
+        if (pSym->n_type & MACHO_N_STAB)
+            continue;
+
+        const char *pszTabName= &pThis->pachStrTab[(uint32_t)pSym->n_un.n_strx];
+        if (   *pszTabName == '_'
+            && strcmp(pszTabName + 1, pszSymbol) == 0)
+            return pSym;
+    }
+#else
+    /** @todo binary search. */
+#endif
+
+    return NULL;
+}
+
+
+/**
+ * Looks up a kernel symbol.
+ *
+ * @returns The symbol address on success, 0 on failure.
+ * @param   pThis               The internal scratch data.
+ * @param   pszSymbol           The symbol to resolve.  Automatically prefixed
+ *                              with an underscore.
+ */
+static uintptr_t rtR0DbgKrnlDarwinLookup(RTDBGKRNLINFOINT *pThis, const char *pszSymbol)
+{
+    MY_NLIST const *pSym = rtR0DbgKrnlDarwinLookupSym(pThis, pszSymbol);
+    if (pSym)
+    {
+        uint8_t idxSeg = pThis->auSections2Segment[pSym->n_sect];
+        if (pThis->aoffLoadSegments[idxSeg] != UINTPTR_MAX)
+            return pSym->n_value + pThis->aoffLoadSegments[idxSeg];
+    }
+
+    return 0;
+}
+
+
+/* Rainy day: Find the right headers for these symbols ... if there are any. */
+extern "C" void ev_try_lock(void);
+extern "C" void OSMalloc(void);
+extern "C" void OSlibkernInit(void);
+extern "C" void kdp_set_interface(void);
+
+
+/*
+ * Determine the load displacement (10.8 kernels are PIE).
+ *
+ * Starting with 11.0 (BigSur) all segments can have different load displacements
+ * so determine the displacements from known symbols.
+ *
+ * @returns IPRT status code
+ * @param   pThis               The internal scratch data.
+ */
+static int rtR0DbgKrnlDarwinInitLoadDisplacements(RTDBGKRNLINFOINT *pThis)
+{
+    static struct
+    {
+        const char *pszName;
+        uintptr_t   uAddr;
+    } const s_aStandardSyms[] =
+    {
+#ifdef IN_RING0
+# define KNOWN_ENTRY(a_Sym)  { #a_Sym, (uintptr_t)&a_Sym }
+#else
+# define KNOWN_ENTRY(a_Sym)  { #a_Sym, 0 }
+#endif
+        KNOWN_ENTRY(vm_map_unwire),   /* __TEXT */
+        KNOWN_ENTRY(kernel_map),      /* __HIB */
+        KNOWN_ENTRY(gIOServicePlane), /* __DATA (__HIB on ElCapitan) */
+        KNOWN_ENTRY(page_mask)        /* __DATA on ElCapitan */
+#undef KNOWN_ENTRY
+    };
+
+    for (unsigned i = 0; i < RT_ELEMENTS(s_aStandardSyms); i++)
+    {
+        MY_NLIST const *pSym = rtR0DbgKrnlDarwinLookupSym(pThis, s_aStandardSyms[i].pszName);
+        if (RT_UNLIKELY(!pSym))
+            return VERR_INTERNAL_ERROR_2;
+
+        uint8_t idxSeg = pThis->auSections2Segment[pSym->n_sect];
+#ifdef IN_RING0
+        /*
+         * The segment should either not have the load displacement determined or it should
+         * be the same for all symbols in the same segment.
+         */
+        if (   pThis->aoffLoadSegments[idxSeg] != UINTPTR_MAX
+            && pThis->aoffLoadSegments[idxSeg] != s_aStandardSyms[i].uAddr - pSym->n_value)
+            return VERR_INTERNAL_ERROR_2;
+
+        pThis->aoffLoadSegments[idxSeg] = s_aStandardSyms[i].uAddr - pSym->n_value;
+#elif defined(IN_RING3)
+        pThis->aoffLoadSegments[idxSeg] = 0;
+#else
+# error "Either IN_RING0 or IN_RING3 msut be defined"
+#endif
+    }
+
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Check the symbol table against symbols we known symbols.
+ *
+ * This is done to detect whether the on disk image and the in
+ * memory images matches.  Mismatches could stem from user
+ * replacing the default kernel image on disk.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The internal scratch data.
+ * @param   pszKernelFile       The name of the kernel file.
+ */
+static int rtR0DbgKrnlDarwinCheckStandardSymbols(RTDBGKRNLINFOINT *pThis, const char *pszKernelFile)
+{
+    static struct
+    {
+        const char *pszName;
+        uintptr_t   uAddr;
+    } const s_aStandardCandles[] =
+    {
+#ifdef IN_RING0
+# define KNOWN_ENTRY(a_Sym)  { #a_Sym, (uintptr_t)&a_Sym }
+#else
+# define KNOWN_ENTRY(a_Sym)  { #a_Sym, 0 }
+#endif
+        /* IOKit: */
+        KNOWN_ENTRY(IOMalloc),
+        KNOWN_ENTRY(IOFree),
+        KNOWN_ENTRY(IOSleep),
+        KNOWN_ENTRY(IORWLockAlloc),
+        KNOWN_ENTRY(IORecursiveLockLock),
+        KNOWN_ENTRY(IOSimpleLockAlloc),
+        KNOWN_ENTRY(PE_cpu_halt),
+        KNOWN_ENTRY(gIOKitDebug),
+        KNOWN_ENTRY(gIOServicePlane),
+        KNOWN_ENTRY(ev_try_lock),
+
+        /* Libkern: */
+        KNOWN_ENTRY(OSAddAtomic),
+        KNOWN_ENTRY(OSBitAndAtomic),
+        KNOWN_ENTRY(OSBitOrAtomic),
+        KNOWN_ENTRY(OSBitXorAtomic),
+        KNOWN_ENTRY(OSCompareAndSwap),
+        KNOWN_ENTRY(OSMalloc),
+        KNOWN_ENTRY(OSlibkernInit),
+        KNOWN_ENTRY(bcmp),
+        KNOWN_ENTRY(copyout),
+        KNOWN_ENTRY(copyin),
+        KNOWN_ENTRY(kprintf),
+        KNOWN_ENTRY(printf),
+        KNOWN_ENTRY(lck_grp_alloc_init),
+        KNOWN_ENTRY(lck_mtx_alloc_init),
+        KNOWN_ENTRY(lck_rw_alloc_init),
+        KNOWN_ENTRY(lck_spin_alloc_init),
+        KNOWN_ENTRY(osrelease),
+        KNOWN_ENTRY(ostype),
+        KNOWN_ENTRY(panic),
+        KNOWN_ENTRY(strprefix),
+        //KNOWN_ENTRY(sysctlbyname), - we get kernel_sysctlbyname from the 10.10+ kernels.
+        KNOWN_ENTRY(vsscanf),
+        KNOWN_ENTRY(page_mask),
+
+        /* Mach: */
+        KNOWN_ENTRY(absolutetime_to_nanoseconds),
+        KNOWN_ENTRY(assert_wait),
+        KNOWN_ENTRY(clock_delay_until),
+        KNOWN_ENTRY(clock_get_uptime),
+        KNOWN_ENTRY(current_task),
+        KNOWN_ENTRY(current_thread),
+        KNOWN_ENTRY(kernel_task),
+        KNOWN_ENTRY(lck_mtx_sleep),
+        KNOWN_ENTRY(lck_rw_sleep),
+        KNOWN_ENTRY(lck_spin_sleep),
+        KNOWN_ENTRY(mach_absolute_time),
+        KNOWN_ENTRY(semaphore_create),
+        KNOWN_ENTRY(task_reference),
+        KNOWN_ENTRY(thread_block),
+        KNOWN_ENTRY(thread_reference),
+        KNOWN_ENTRY(thread_terminate),
+        KNOWN_ENTRY(thread_wakeup_prim),
+
+        /* BSDKernel: */
+        KNOWN_ENTRY(buf_size),
+        KNOWN_ENTRY(copystr),
+        KNOWN_ENTRY(current_proc),
+        KNOWN_ENTRY(ifnet_hdrlen),
+        KNOWN_ENTRY(ifnet_set_promiscuous),
+        KNOWN_ENTRY(kauth_getuid),
+#if MAC_OS_X_VERSION_MIN_REQUIRED >= 1050
+        KNOWN_ENTRY(kauth_cred_unref),
+#else
+        KNOWN_ENTRY(kauth_cred_rele),
+#endif
+        KNOWN_ENTRY(mbuf_data),
+        KNOWN_ENTRY(msleep),
+        KNOWN_ENTRY(nanotime),
+        KNOWN_ENTRY(nop_close),
+        KNOWN_ENTRY(proc_pid),
+        KNOWN_ENTRY(sock_accept),
+        KNOWN_ENTRY(sockopt_name),
+        //KNOWN_ENTRY(spec_write),
+        KNOWN_ENTRY(suword),
+        //KNOWN_ENTRY(sysctl_int),
+        KNOWN_ENTRY(uio_rw),
+        KNOWN_ENTRY(vfs_flags),
+        KNOWN_ENTRY(vfs_name),
+        KNOWN_ENTRY(vfs_statfs),
+        KNOWN_ENTRY(VNOP_READ),
+        KNOWN_ENTRY(uio_create),
+        KNOWN_ENTRY(uio_addiov),
+        KNOWN_ENTRY(uio_free),
+        KNOWN_ENTRY(vnode_get),
+        KNOWN_ENTRY(vnode_open),
+        KNOWN_ENTRY(vnode_ref),
+        KNOWN_ENTRY(vnode_rele),
+        KNOWN_ENTRY(vnop_close_desc),
+        KNOWN_ENTRY(wakeup),
+        KNOWN_ENTRY(wakeup_one),
+
+        /* Unsupported: */
+        KNOWN_ENTRY(kdp_set_interface),
+        KNOWN_ENTRY(pmap_find_phys),
+        KNOWN_ENTRY(vm_map),
+        KNOWN_ENTRY(vm_protect),
+        KNOWN_ENTRY(vm_region),
+        KNOWN_ENTRY(vm_map_unwire), /* vm_map_wire has an alternative symbol, vm_map_wire_external, in 10.11  */
+        KNOWN_ENTRY(PE_kputc),
+        KNOWN_ENTRY(kernel_map),
+        KNOWN_ENTRY(kernel_pmap),
+#undef KNOWN_ENTRY
+    };
+
+    for (unsigned i = 0; i < RT_ELEMENTS(s_aStandardCandles); i++)
+    {
+        uintptr_t uAddr = rtR0DbgKrnlDarwinLookup(pThis, s_aStandardCandles[i].pszName);
+#ifdef IN_RING0
+        if (uAddr != s_aStandardCandles[i].uAddr)
+#else
+        if (uAddr == 0)
+#endif
+        {
+#if defined(IN_RING0) && defined(DEBUG_bird)
+            kprintf("RTR0DbgKrnlInfoOpen: error: %s (%p != %p) in %s\n",
+                    s_aStandardCandles[i].pszName, (void *)uAddr, (void *)s_aStandardCandles[i].uAddr, pszKernelFile);
+#endif
+            printf("RTR0DbgKrnlInfoOpen: error: %s (%p != %p) in %s\n",
+                   s_aStandardCandles[i].pszName, (void *)uAddr, (void *)s_aStandardCandles[i].uAddr, pszKernelFile);
+            return VERR_INTERNAL_ERROR_2;
+        }
+    }
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Loads and validates the symbol and string tables.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The internal scratch data.
+ * @param   pszKernelFile       The name of the kernel file.
+ */
+static int rtR0DbgKrnlDarwinParseSymTab(RTDBGKRNLINFOINT *pThis, const char *pszKernelFile)
+{
+    /*
+     * The first string table symbol must be a zero length name.
+     */
+    if (pThis->pachStrTab[0] != '\0')
+        RETURN_VERR_BAD_EXE_FORMAT;
+
+    /*
+     * Validate the symbol table.
+     */
+    const char     *pszPrev = "";
+    uint32_t const  cSyms   = pThis->cSyms;
+    MY_NLIST const  *pSym   = pThis->paSyms;
+    for (uint32_t iSym = 0; iSym < cSyms; iSym++, pSym++)
+    {
+        if ((uint32_t)pSym->n_un.n_strx >= pThis->cbStrTab)
+        {
+            LOG_BAD_SYM("RTR0DbgKrnlInfoOpen: %s: Symbol #%u has a bad string table index: %#x vs cbStrTab=%#x\n",
+                        pszKernelFile, iSym, pSym->n_un.n_strx, pThis->cbStrTab);
+            RETURN_VERR_BAD_EXE_FORMAT;
+        }
+        const char *pszSym = &pThis->pachStrTab[(uint32_t)pSym->n_un.n_strx];
+#ifdef IN_RING3
+        RTAssertMsg2("%05i: %02x:%08llx %02x %04x %s\n", iSym, pSym->n_sect, (uint64_t)pSym->n_value, pSym->n_type, pSym->n_desc, pszSym);
+#endif
+
+        if (strcmp(pszSym, pszPrev) < 0)
+            RETURN_VERR_BAD_EXE_FORMAT; /* not sorted */
+
+        if (!(pSym->n_type & MACHO_N_STAB))
+        {
+            switch (pSym->n_type & MACHO_N_TYPE)
+            {
+                case MACHO_N_SECT:
+                    if (pSym->n_sect == MACHO_NO_SECT)
+                    {
+                        LOG_BAD_SYM("RTR0DbgKrnlInfoOpen: %s: Symbol #%u '%s' problem: n_sect = MACHO_NO_SECT\n",
+                                    pszKernelFile, iSym, pszSym);
+                        RETURN_VERR_BAD_EXE_FORMAT;
+                    }
+                    if (pSym->n_sect > pThis->cSections)
+                    {
+                        LOG_BAD_SYM("RTR0DbgKrnlInfoOpen: %s: Symbol #%u '%s' problem: n_sect (%u) is higher than cSections (%u)\n",
+                                    pszKernelFile, iSym, pszSym, pSym->n_sect, pThis->cSections);
+                        RETURN_VERR_BAD_EXE_FORMAT;
+                    }
+                    if (pSym->n_desc & ~(REFERENCED_DYNAMICALLY | N_WEAK_DEF))
+                    {
+                        LOG_BAD_SYM("RTR0DbgKrnlInfoOpen: %s: Symbol #%u '%s' problem: Unexpected value n_desc=%#x\n",
+                                    pszKernelFile, iSym, pszSym, pSym->n_desc);
+                        RETURN_VERR_BAD_EXE_FORMAT;
+                    }
+                    if (   pSym->n_value < pThis->apSections[pSym->n_sect - 1]->addr
+                        && strcmp(pszSym, "__mh_execute_header"))    /* in 10.8 it's no longer absolute (PIE?). */
+                    {
+                        LOG_BAD_SYM("RTR0DbgKrnlInfoOpen: %s: Symbol #%u '%s' problem: n_value (%#llx) < section addr (%#llx)\n",
+                                    pszKernelFile, iSym, pszSym, pSym->n_value, pThis->apSections[pSym->n_sect - 1]->addr);
+                        RETURN_VERR_BAD_EXE_FORMAT;
+                    }
+                    if (      pSym->n_value - pThis->apSections[pSym->n_sect - 1]->addr
+                           > pThis->apSections[pSym->n_sect - 1]->size
+                        && strcmp(pszSym, "__mh_execute_header"))    /* see above. */
+                    {
+                        LOG_BAD_SYM("RTR0DbgKrnlInfoOpen: %s: Symbol #%u '%s' problem: n_value (%#llx) >= end of section (%#llx + %#llx)\n",
+                                    pszKernelFile, iSym, pszSym, pSym->n_value, pThis->apSections[pSym->n_sect - 1]->addr,
+                                    pThis->apSections[pSym->n_sect - 1]->size);
+                        RETURN_VERR_BAD_EXE_FORMAT;
+                    }
+                    break;
+
+                case MACHO_N_ABS:
+                    if (   pSym->n_sect != MACHO_NO_SECT
+                        && (   strcmp(pszSym, "__mh_execute_header") /* n_sect=1 in 10.7/amd64 */
+                            || pSym->n_sect > pThis->cSections) )
+                    {
+                        LOG_BAD_SYM("RTR0DbgKrnlInfoOpen: %s: Abs symbol #%u '%s' problem: n_sect (%u) is not MACHO_NO_SECT (cSections is %u)\n",
+                                    pszKernelFile, iSym, pszSym, pSym->n_sect, pThis->cSections);
+                        RETURN_VERR_BAD_EXE_FORMAT;
+                    }
+                    if (pSym->n_desc & ~(REFERENCED_DYNAMICALLY | N_WEAK_DEF))
+                    {
+                        LOG_BAD_SYM("RTR0DbgKrnlInfoOpen: %s: Abs symbol #%u '%s' problem: Unexpected value n_desc=%#x\n",
+                                    pszKernelFile, iSym, pszSym, pSym->n_desc);
+                        RETURN_VERR_BAD_EXE_FORMAT;
+                    }
+                    break;
+
+                case MACHO_N_UNDF:
+                    /* No undefined or common symbols in the kernel. */
+                    LOG_BAD_SYM("RTR0DbgKrnlInfoOpen: %s: Unexpected undefined symbol #%u '%s'\n", pszKernelFile, iSym, pszSym);
+                    RETURN_VERR_BAD_EXE_FORMAT;
+
+                case MACHO_N_INDR:
+                    /* No indirect symbols in the kernel. */
+                    LOG_BAD_SYM("RTR0DbgKrnlInfoOpen: %s: Unexpected indirect symbol #%u '%s'\n", pszKernelFile, iSym, pszSym);
+                    RETURN_VERR_BAD_EXE_FORMAT;
+
+                case MACHO_N_PBUD:
+                    /* No prebound symbols in the kernel. */
+                    LOG_BAD_SYM("RTR0DbgKrnlInfoOpen: %s: Unexpected prebound symbol #%u '%s'\n", pszKernelFile, iSym, pszSym);
+                    RETURN_VERR_BAD_EXE_FORMAT;
+
+                default:
+                    LOG_BAD_SYM("RTR0DbgKrnlInfoOpen: %s: Unexpected symbol n_type %#x for symbol #%u '%s'\n",
+                                pszKernelFile, pSym->n_type, iSym, pszSym);
+                    RETURN_VERR_BAD_EXE_FORMAT;
+            }
+        }
+        /* else: Ignore debug symbols. */
+    }
+
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Uses the segment table to translate a file offset into a virtual memory
+ * address.
+ *
+ * @returns The virtual memory address on success, 0 if not found.
+ * @param   pThis               The instance.
+ * @param   offFile             The file offset to translate.
+ */
+static uintptr_t rtR0DbgKrnlDarwinFileOffToVirtAddr(RTDBGKRNLINFOINT *pThis, uint64_t offFile)
+{
+    uint32_t iSeg = pThis->cSegments;
+    while (iSeg-- > 0)
+    {
+        uint64_t offSeg = offFile - pThis->apSegments[iSeg]->fileoff;
+        if (offSeg < pThis->apSegments[iSeg]->vmsize)
+            return pThis->apSegments[iSeg]->vmaddr + (uintptr_t)offSeg;
+    }
+    return 0;
+}
+
+
+/**
+ * Parses and validates the load commands.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The internal scratch data.
+ */
+static int rtR0DbgKrnlDarwinParseCommands(RTDBGKRNLINFOINT *pThis)
+{
+    Assert(pThis->pLoadCmds);
+
+    /*
+     * Reset the state.
+     */
+    pThis->offStrTab        = 0;
+    pThis->cbStrTab         = 0;
+    pThis->offSyms          = 0;
+    pThis->cSyms            = 0;
+    pThis->cSections        = 0;
+    pThis->uTextSegLinkAddr = 0;
+    pThis->cbTextSeg        = 0;
+    pThis->uMinOsVer        = 0;
+    pThis->uSdkVer          = 0;
+    pThis->uSrcVer          = 0;
+
+    /*
+     * Validate the relevant commands, picking up sections and the symbol
+     * table location.
+     */
+    load_command_t const   *pCmd = pThis->pLoadCmds;
+    for (uint32_t iCmd = 0; ; iCmd++)
+    {
+        /* cmd index & offset. */
+        uintptr_t offCmd = (uintptr_t)pCmd - (uintptr_t)pThis->pLoadCmds;
+        if (offCmd == pThis->cbLoadCmds && iCmd == pThis->cLoadCmds)
+            break;
+        if (offCmd + sizeof(*pCmd) > pThis->cbLoadCmds)
+            RETURN_VERR_BAD_EXE_FORMAT;
+        if (iCmd >= pThis->cLoadCmds)
+            RETURN_VERR_BAD_EXE_FORMAT;
+
+        /* cmdsize */
+        if (pCmd->cmdsize < sizeof(*pCmd))
+            RETURN_VERR_BAD_EXE_FORMAT;
+        if (pCmd->cmdsize > pThis->cbLoadCmds)
+            RETURN_VERR_BAD_EXE_FORMAT;
+        if (RT_ALIGN_32(pCmd->cmdsize, 4) != pCmd->cmdsize)
+            RETURN_VERR_BAD_EXE_FORMAT;
+
+        /* cmd */
+        switch (pCmd->cmd & ~LC_REQ_DYLD)
+        {
+            /* Validate and store the symbol table details. */
+            case LC_SYMTAB:
+            {
+                struct symtab_command const *pSymTab = (struct symtab_command const *)pCmd;
+                if (pSymTab->cmdsize != sizeof(*pSymTab))
+                    RETURN_VERR_BAD_EXE_FORMAT;
+                if (pSymTab->nsyms > _1M)
+                    RETURN_VERR_BAD_EXE_FORMAT;
+                if (pSymTab->strsize > _2M)
+                    RETURN_VERR_BAD_EXE_FORMAT;
+
+                pThis->offStrTab = pSymTab->stroff;
+                pThis->cbStrTab  = pSymTab->strsize;
+                pThis->offSyms   = pSymTab->symoff;
+                pThis->cSyms     = pSymTab->nsyms;
+                break;
+            }
+
+            /* Validate the segment. */
+#if ARCH_BITS == 32
+            case LC_SEGMENT_32:
+#elif ARCH_BITS == 64
+            case LC_SEGMENT_64:
+#else
+# error ARCH_BITS
+#endif
+            {
+                MY_SEGMENT_COMMAND const *pSeg = (MY_SEGMENT_COMMAND const *)pCmd;
+                if (pSeg->cmdsize < sizeof(*pSeg))
+                    RETURN_VERR_BAD_EXE_FORMAT;
+
+                if (pSeg->segname[0] == '\0')
+                    RETURN_VERR_BAD_EXE_FORMAT;
+
+                if (pSeg->nsects > MACHO_MAX_SECT)
+                    RETURN_VERR_BAD_EXE_FORMAT;
+                if (pSeg->nsects * sizeof(MY_SECTION) + sizeof(*pSeg) != pSeg->cmdsize)
+                    RETURN_VERR_BAD_EXE_FORMAT;
+
+                if (pSeg->flags & ~(SG_HIGHVM | SG_FVMLIB | SG_NORELOC | SG_PROTECTED_VERSION_1))
+                    RETURN_VERR_BAD_EXE_FORMAT;
+
+                if (   pSeg->vmaddr != 0
+                    || !strcmp(pSeg->segname, "__PAGEZERO"))
+                {
+                    if (pSeg->vmaddr + RT_ALIGN_Z(pSeg->vmsize, RT_BIT_32(12)) < pSeg->vmaddr)
+                        RETURN_VERR_BAD_EXE_FORMAT;
+                }
+                else if (pSeg->vmsize)
+                    RETURN_VERR_BAD_EXE_FORMAT;
+
+                if (pSeg->maxprot & ~VM_PROT_ALL)
+                    RETURN_VERR_BAD_EXE_FORMAT;
+                if (pSeg->initprot & ~VM_PROT_ALL)
+                    RETURN_VERR_BAD_EXE_FORMAT;
+
+                /* Validate the sections. */
+                uint32_t            uAlignment = 0;
+                MY_SECTION const   *paSects    = (MY_SECTION const *)(pSeg + 1);
+                for (uint32_t i = 0; i < pSeg->nsects; i++)
+                {
+                    if (paSects[i].sectname[0] == '\0')
+                        RETURN_VERR_BAD_EXE_FORMAT;
+                    if (memcmp(paSects[i].segname, pSeg->segname, sizeof(pSeg->segname)))
+                        RETURN_VERR_BAD_EXE_FORMAT;
+
+                    switch (paSects[i].flags & SECTION_TYPE)
+                    {
+                        case S_REGULAR:
+                        case S_CSTRING_LITERALS:
+                        case S_NON_LAZY_SYMBOL_POINTERS:
+                        case S_MOD_INIT_FUNC_POINTERS:
+                        case S_MOD_TERM_FUNC_POINTERS:
+                        case S_COALESCED:
+                        case S_4BYTE_LITERALS:
+                            if (  pSeg->filesize != 0
+                                ? paSects[i].offset - pSeg->fileoff >= pSeg->filesize
+                                : paSects[i].offset - pSeg->fileoff != pSeg->filesize)
+                                RETURN_VERR_BAD_EXE_FORMAT;
+                            if (   paSects[i].addr != 0
+                                && paSects[i].offset - pSeg->fileoff != paSects[i].addr - pSeg->vmaddr)
+                                RETURN_VERR_BAD_EXE_FORMAT;
+                            break;
+
+                        case S_ZEROFILL:
+                            if (paSects[i].offset != 0)
+                                RETURN_VERR_BAD_EXE_FORMAT;
+                            break;
+
+                        /* not observed */
+                        case S_SYMBOL_STUBS:
+                        case S_INTERPOSING:
+                        case S_8BYTE_LITERALS:
+                        case S_16BYTE_LITERALS:
+                        case S_DTRACE_DOF:
+                        case S_LAZY_SYMBOL_POINTERS:
+                        case S_LAZY_DYLIB_SYMBOL_POINTERS:
+                            RETURN_VERR_LDR_UNEXPECTED;
+                        case S_GB_ZEROFILL:
+                            RETURN_VERR_LDR_UNEXPECTED;
+                        default:
+                            RETURN_VERR_BAD_EXE_FORMAT;
+                    }
+
+                    if (paSects[i].align > 12)
+                        RETURN_VERR_BAD_EXE_FORMAT;
+                    if (paSects[i].align > uAlignment)
+                        uAlignment = paSects[i].align;
+
+                    /* Add to the section table. */
+                    if (pThis->cSections >= RT_ELEMENTS(pThis->apSections))
+                        RETURN_VERR_BAD_EXE_FORMAT;
+                    pThis->auSections2Segment[pThis->cSections] = pThis->cSegments;
+                    pThis->apSections[pThis->cSections++] = &paSects[i];
+                }
+
+                if (RT_ALIGN_Z(pSeg->vmaddr, RT_BIT_32(uAlignment)) != pSeg->vmaddr)
+                    RETURN_VERR_BAD_EXE_FORMAT;
+                if (   pSeg->filesize > RT_ALIGN_Z(pSeg->vmsize, RT_BIT_32(uAlignment))
+                    && pSeg->vmsize != 0)
+                    RETURN_VERR_BAD_EXE_FORMAT;
+
+                /*
+                 * Add to the segment table.
+                 */
+                if (pThis->cSegments >= RT_ELEMENTS(pThis->apSegments))
+                    RETURN_VERR_BAD_EXE_FORMAT;
+                pThis->apSegments[pThis->cSegments++] = pSeg;
+
+                /*
+                 * Take down the text segment size and link address (for in-mem variant):
+                 */
+                if (!strcmp(pSeg->segname, "__TEXT"))
+                {
+                    if (pThis->cbTextSeg != 0)
+                        RETURN_VERR_BAD_EXE_FORMAT;
+                    pThis->uTextSegLinkAddr = pSeg->vmaddr;
+                    pThis->cbTextSeg        = pSeg->vmsize;
+                }
+                break;
+            }
+
+            case LC_UUID:
+                if (pCmd->cmdsize != sizeof(uuid_command))
+                    RETURN_VERR_BAD_EXE_FORMAT;
+                break;
+
+            case LC_DYSYMTAB:
+            case LC_UNIXTHREAD:
+            case LC_CODE_SIGNATURE:
+            case LC_VERSION_MIN_MACOSX:
+            case LC_FUNCTION_STARTS:
+            case LC_MAIN:
+            case LC_DATA_IN_CODE:
+            case LC_ENCRYPTION_INFO_64:
+            case LC_LINKER_OPTION:
+            case LC_LINKER_OPTIMIZATION_HINT:
+            case LC_VERSION_MIN_TVOS:
+            case LC_VERSION_MIN_WATCHOS:
+            case LC_NOTE:
+            case LC_SEGMENT_SPLIT_INFO:
+                break;
+
+            case LC_BUILD_VERSION:
+                if (pCmd->cmdsize >= RT_UOFFSETOF(build_version_command_t, aTools))
+                {
+                    build_version_command_t *pBldVerCmd = (build_version_command_t *)pCmd;
+                    pThis->uMinOsVer = pBldVerCmd->minos;
+                    pThis->uSdkVer   = pBldVerCmd->sdk;
+                }
+                break;
+
+            case LC_SOURCE_VERSION:
+                if (pCmd->cmdsize == sizeof(source_version_command_t))
+                {
+                    source_version_command_t *pSrcVerCmd = (source_version_command_t *)pCmd;
+                    pThis->uSrcVer = pSrcVerCmd->version;
+                }
+                break;
+
+            /* not observed */
+            case LC_SYMSEG:
+#if ARCH_BITS == 32
+            case LC_SEGMENT_64:
+#elif ARCH_BITS == 64
+            case LC_SEGMENT_32:
+#endif
+            case LC_ROUTINES_64:
+            case LC_ROUTINES:
+            case LC_THREAD:
+            case LC_LOADFVMLIB:
+            case LC_IDFVMLIB:
+            case LC_IDENT:
+            case LC_FVMFILE:
+            case LC_PREPAGE:
+            case LC_TWOLEVEL_HINTS:
+            case LC_PREBIND_CKSUM:
+            case LC_ENCRYPTION_INFO:
+                RETURN_VERR_LDR_UNEXPECTED;
+
+            /* no phones here yet */
+            case LC_VERSION_MIN_IPHONEOS:
+                RETURN_VERR_LDR_UNEXPECTED;
+
+            /* dylib */
+            case LC_LOAD_DYLIB:
+            case LC_ID_DYLIB:
+            case LC_LOAD_DYLINKER:
+            case LC_ID_DYLINKER:
+            case LC_PREBOUND_DYLIB:
+            case LC_LOAD_WEAK_DYLIB & ~LC_REQ_DYLD:
+            case LC_SUB_FRAMEWORK:
+            case LC_SUB_UMBRELLA:
+            case LC_SUB_CLIENT:
+            case LC_SUB_LIBRARY:
+            case LC_RPATH:
+            case LC_REEXPORT_DYLIB:
+            case LC_LAZY_LOAD_DYLIB:
+            case LC_DYLD_INFO:
+            case LC_DYLD_INFO_ONLY:
+            case LC_LOAD_UPWARD_DYLIB:
+            case LC_DYLD_ENVIRONMENT:
+            case LC_DYLIB_CODE_SIGN_DRS:
+                RETURN_VERR_LDR_UNEXPECTED;
+
+            default:
+                RETURN_VERR_BAD_EXE_FORMAT;
+        }
+
+        /* next */
+        pCmd = (load_command_t *)((uintptr_t)pCmd + pCmd->cmdsize);
+    }
+
+    /*
+     * Try figure out the virtual addresses for the symbol and string tables.
+     */
+    if (pThis->cbStrTab > 0)
+        pThis->uStrTabLinkAddr = rtR0DbgKrnlDarwinFileOffToVirtAddr(pThis, pThis->offStrTab);
+    if (pThis->cSyms > 0)
+        pThis->uSymTabLinkAddr = rtR0DbgKrnlDarwinFileOffToVirtAddr(pThis, pThis->offSyms);
+
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Loads and validates the symbol and string tables.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The internal scratch data.
+ * @param   pszKernelFile       The name of the kernel file.
+ */
+static int rtR0DbgKrnlDarwinLoadSymTab(RTDBGKRNLINFOINT *pThis, const char *pszKernelFile)
+{
+    /*
+     * Load the tables.
+     */
+    int rc;
+    pThis->paSyms = (MY_NLIST *)RTMemAllocZ(pThis->cSyms * sizeof(MY_NLIST));
+    if (pThis->paSyms)
+    {
+        rc = RTFileReadAt(pThis->hFile, pThis->offArch + pThis->offSyms, pThis->paSyms, pThis->cSyms * sizeof(MY_NLIST), NULL);
+        if (RT_SUCCESS(rc))
+        {
+            pThis->pachStrTab = (char *)RTMemAllocZ(pThis->cbStrTab + 1);
+            if (pThis->pachStrTab)
+            {
+                rc = RTFileReadAt(pThis->hFile, pThis->offArch + pThis->offStrTab, pThis->pachStrTab, pThis->cbStrTab, NULL);
+                if (RT_SUCCESS(rc))
+                {
+                    /*
+                     * Join paths with the in-memory code path.
+                     */
+                    rc = rtR0DbgKrnlDarwinParseSymTab(pThis, pszKernelFile);
+                }
+            }
+            else
+                rc = VERR_NO_MEMORY;
+        }
+    }
+    else
+        rc = VERR_NO_MEMORY;
+    return rc;
+}
+
+
+/**
+ * Loads the load commands and validates them.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The internal scratch data.
+ */
+static int rtR0DbgKrnlDarwinLoadCommands(RTDBGKRNLINFOINT *pThis)
+{
+    int rc;
+    pThis->pLoadCmds = (load_command_t *)RTMemAlloc(pThis->cbLoadCmds);
+    if (pThis->pLoadCmds)
+    {
+        rc = RTFileReadAt(pThis->hFile, pThis->offArch + sizeof(MY_MACHO_HEADER), pThis->pLoadCmds, pThis->cbLoadCmds, NULL);
+        if (RT_SUCCESS(rc))
+            rc = rtR0DbgKrnlDarwinParseCommands(pThis);
+    }
+    else
+        rc = VERR_NO_MEMORY;
+   return rc;
+}
+
+
+/**
+ * Loads the FAT and MACHO headers, noting down the relevant info.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The internal scratch data.
+ */
+static int rtR0DbgKrnlDarwinLoadFileHeaders(RTDBGKRNLINFOINT *pThis)
+{
+    uint32_t i;
+
+    pThis->offArch = 0;
+    pThis->cbArch  = 0;
+
+    /*
+     * Read the first bit of the file, parse the FAT if found there.
+     */
+    int rc = RTFileReadAt(pThis->hFile, 0, pThis->abBuf, sizeof(fat_header_t) + sizeof(fat_arch_t) * 16, NULL);
+    if (RT_FAILURE(rc))
+        return rc;
+
+    fat_header_t   *pFat        = (fat_header *)pThis->abBuf;
+    fat_arch_t     *paFatArches = (fat_arch_t *)(pFat + 1);
+
+    /* Correct FAT endian first. */
+    if (pFat->magic == IMAGE_FAT_SIGNATURE_OE)
+    {
+        pFat->magic     = RT_BSWAP_U32(pFat->magic);
+        pFat->nfat_arch = RT_BSWAP_U32(pFat->nfat_arch);
+        i = RT_MIN(pFat->nfat_arch, 16);
+        while (i-- > 0)
+        {
+            paFatArches[i].cputype    = RT_BSWAP_U32(paFatArches[i].cputype);
+            paFatArches[i].cpusubtype = RT_BSWAP_U32(paFatArches[i].cpusubtype);
+            paFatArches[i].offset     = RT_BSWAP_U32(paFatArches[i].offset);
+            paFatArches[i].size       = RT_BSWAP_U32(paFatArches[i].size);
+            paFatArches[i].align      = RT_BSWAP_U32(paFatArches[i].align);
+        }
+    }
+
+    /* Lookup our architecture in the FAT. */
+    if (pFat->magic == IMAGE_FAT_SIGNATURE)
+    {
+        if (pFat->nfat_arch > 16)
+            RETURN_VERR_BAD_EXE_FORMAT;
+
+        for (i = 0; i < pFat->nfat_arch; i++)
+        {
+            if (   paFatArches[i].cputype == MY_CPU_TYPE
+                && paFatArches[i].cpusubtype == MY_CPU_SUBTYPE_ALL)
+            {
+                pThis->offArch = paFatArches[i].offset;
+                pThis->cbArch  = paFatArches[i].size;
+                if (!pThis->cbArch)
+                    RETURN_VERR_BAD_EXE_FORMAT;
+                if (pThis->offArch < sizeof(fat_header_t) + sizeof(fat_arch_t) * pFat->nfat_arch)
+                    RETURN_VERR_BAD_EXE_FORMAT;
+                if (pThis->offArch + pThis->cbArch <= pThis->offArch)
+                    RETURN_VERR_LDR_ARCH_MISMATCH;
+                break;
+            }
+        }
+        if (i >= pFat->nfat_arch)
+            RETURN_VERR_LDR_ARCH_MISMATCH;
+    }
+
+    /*
+     * Read the Mach-O header and validate it.
+     */
+    rc = RTFileReadAt(pThis->hFile, pThis->offArch, pThis->abBuf, sizeof(MY_MACHO_HEADER), NULL);
+    if (RT_FAILURE(rc))
+        return rc;
+    MY_MACHO_HEADER const *pHdr = (MY_MACHO_HEADER const *)pThis->abBuf;
+    if (pHdr->magic != MY_MACHO_MAGIC)
+    {
+        if (   pHdr->magic == IMAGE_MACHO32_SIGNATURE
+            || pHdr->magic == IMAGE_MACHO32_SIGNATURE_OE
+            || pHdr->magic == IMAGE_MACHO64_SIGNATURE
+            || pHdr->magic == IMAGE_MACHO64_SIGNATURE_OE)
+            RETURN_VERR_LDR_ARCH_MISMATCH;
+        RETURN_VERR_BAD_EXE_FORMAT;
+    }
+
+    if (pHdr->cputype    != MY_CPU_TYPE)
+        RETURN_VERR_LDR_ARCH_MISMATCH;
+    if (pHdr->cpusubtype != MY_CPU_SUBTYPE_ALL)
+        RETURN_VERR_LDR_ARCH_MISMATCH;
+    if (pHdr->filetype   != MH_EXECUTE)
+        RETURN_VERR_LDR_UNEXPECTED;
+    if (pHdr->ncmds      < 4)
+        RETURN_VERR_LDR_UNEXPECTED;
+    if (pHdr->ncmds      > 256)
+        RETURN_VERR_LDR_UNEXPECTED;
+    if (pHdr->sizeofcmds <= pHdr->ncmds * sizeof(load_command_t))
+        RETURN_VERR_LDR_UNEXPECTED;
+    if (pHdr->sizeofcmds >= _1M)
+        RETURN_VERR_LDR_UNEXPECTED;
+    if (pHdr->flags & ~MH_VALID_FLAGS)
+        RETURN_VERR_LDR_UNEXPECTED;
+
+    pThis->cLoadCmds  = pHdr->ncmds;
+    pThis->cbLoadCmds = pHdr->sizeofcmds;
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Destructor.
+ *
+ * @param   pThis               The instance to destroy.
+ */
+static void rtR0DbgKrnlDarwinDtor(RTDBGKRNLINFOINT *pThis)
+{
+    pThis->u32Magic = ~RTDBGKRNLINFO_MAGIC;
+
+    if (!pThis->fIsInMem)
+        RTMemFree(pThis->pachStrTab);
+    pThis->pachStrTab = NULL;
+
+    if (!pThis->fIsInMem)
+        RTMemFree(pThis->paSyms);
+    pThis->paSyms = NULL;
+
+    RTMemFree(pThis);
+}
+
+
+/**
+ * Completes a handle, logging details.
+ *
+ * @returns VINF_SUCCESS
+ * @param   phKrnlInfo      Where to return the handle.
+ * @param   pThis           The instance to complete.
+ * @param   pszKernelFile   What kernel file it's based on.
+ */
+static int rtR0DbgKrnlDarwinSuccess(PRTDBGKRNLINFO phKrnlInfo, RTDBGKRNLINFOINT *pThis, const char *pszKernelFile)
+{
+    pThis->u32Magic = RTDBGKRNLINFO_MAGIC;
+    pThis->cRefs    = 1;
+
+#if defined(DEBUG) || defined(IN_RING3)
+    LOG_SUCCESS("RTR0DbgKrnlInfoOpen: Found: %#zx + %#zx - %s\n", pThis->uTextSegLinkAddr, pThis->offLoad, pszKernelFile);
+#else
+    LOG_SUCCESS("RTR0DbgKrnlInfoOpen: Found: %s\n", pszKernelFile);
+#endif
+    LOG_SUCCESS("RTR0DbgKrnlInfoOpen: SDK version: %u.%u.%u  MinOS version: %u.%u.%u  Source version: %u.%u.%u.%u.%u\n",
+                pThis->uSdkVer   >> 16, (pThis->uSdkVer   >> 8) & 0xff, pThis->uSdkVer   & 0xff,
+                pThis->uMinOsVer >> 16, (pThis->uMinOsVer >> 8) & 0xff, pThis->uMinOsVer & 0xff,
+                (uint32_t)(pThis->uSrcVer >> 40),
+                (uint32_t)(pThis->uSrcVer >> 30) & 0x3ff,
+                (uint32_t)(pThis->uSrcVer >> 20) & 0x3ff,
+                (uint32_t)(pThis->uSrcVer >> 10) & 0x3ff,
+                (uint32_t)(pThis->uSrcVer)       & 0x3ff);
+
+    *phKrnlInfo = pThis;
+    return VINF_SUCCESS;
+}
+
+
+static int rtR0DbgKrnlDarwinOpen(PRTDBGKRNLINFO phKrnlInfo, const char *pszKernelFile)
+{
+    RTDBGKRNLINFOINT *pThis = (RTDBGKRNLINFOINT *)RTMemAllocZ(sizeof(*pThis));
+    if (!pThis)
+        return VERR_NO_MEMORY;
+    pThis->hFile = NIL_RTFILE;
+
+    for (uint32_t i = 0; i < RT_ELEMENTS(pThis->aoffLoadSegments); i++)
+        pThis->aoffLoadSegments[i] = UINTPTR_MAX;
+
+    int rc = RTFileOpen(&pThis->hFile, pszKernelFile, RTFILE_O_READ | RTFILE_O_OPEN | RTFILE_O_DENY_WRITE);
+    if (RT_SUCCESS(rc))
+        rc = rtR0DbgKrnlDarwinLoadFileHeaders(pThis);
+    if (RT_SUCCESS(rc))
+        rc = rtR0DbgKrnlDarwinLoadCommands(pThis);
+    if (RT_SUCCESS(rc))
+        rc = rtR0DbgKrnlDarwinLoadSymTab(pThis, pszKernelFile);
+    if (RT_SUCCESS(rc))
+    {
+        rc = rtR0DbgKrnlDarwinInitLoadDisplacements(pThis);
+        if (RT_SUCCESS(rc))
+            rc = rtR0DbgKrnlDarwinCheckStandardSymbols(pThis, pszKernelFile);
+    }
+
+    rtR0DbgKrnlDarwinLoadDone(pThis);
+    if (RT_SUCCESS(rc))
+        rtR0DbgKrnlDarwinSuccess(phKrnlInfo, pThis, pszKernelFile);
+    else
+        rtR0DbgKrnlDarwinDtor(pThis);
+    return rc;
+}
+
+
+#ifdef IN_RING0
+
+/**
+ * Checks if a page is present.
+ * @returns true if it is, false if it isn't.
+ * @param   uPageAddr   The address of/in the page to check.
+ */
+static bool rtR0DbgKrnlDarwinIsPagePresent(uintptr_t uPageAddr)
+{
+    /** @todo the dtrace code subjects the result to pmap_is_valid, but that
+     *        isn't exported, so we'll have to make to with != 0 here. */
+    return pmap_find_phys(kernel_pmap, uPageAddr) != 0;
+}
+
+
+/**
+ * Used to check whether a memory range is present or not.
+ *
+ * This is applied to the to the load commands and selected portions of the link
+ * edit segment.
+ *
+ * @returns true if all present, false if not.
+ * @param   uAddress    The start address.
+ * @param   cb          Number of bytes to check.
+ * @param   pszWhat     What we're checking, for logging.
+ * @param   pHdr        The header address (for logging).
+ */
+static bool rtR0DbgKrnlDarwinIsRangePresent(uintptr_t uAddress, size_t cb,
+                                            const char *pszWhat, MY_MACHO_HEADER const volatile *pHdr)
+{
+    uintptr_t const uStartAddress = uAddress;
+    intptr_t        cPages        = RT_ALIGN_Z(cb + (uAddress & PAGE_OFFSET_MASK), PAGE_SIZE);
+    RT_NOREF(uStartAddress, pszWhat, pHdr);
+    for (;;)
+    {
+        if (!rtR0DbgKrnlDarwinIsPagePresent(uAddress))
+        {
+            LOG_NOT_PRESENT("RTR0DbgInfo: %p: Page in %s is not present: %#zx - rva %#zx; in structure %#zx (%#zx LB %#zx)\n",
+                            pHdr, pszWhat, uAddress, uAddress - (uintptr_t)pHdr, uAddress - uStartAddress, uStartAddress, cb);
+            return false;
+        }
+
+        cPages -= 1;
+        if (cPages <= 0)
+            uAddress += PAGE_SIZE;
+        else
+            return true;
+    }
+}
+
+
+/**
+ * Try "open" the in-memory kernel image
+ *
+ * @returns IPRT stauts code
+ * @param   phKrnlInfo          Where to return the info instance on success.
+ */
+static int rtR0DbgKrnlDarwinOpenInMemory(PRTDBGKRNLINFO phKrnlInfo)
+{
+    RTDBGKRNLINFOINT *pThis = (RTDBGKRNLINFOINT *)RTMemAllocZ(sizeof(*pThis));
+    if (!pThis)
+        return VERR_NO_MEMORY;
+    pThis->hFile    = NIL_RTFILE;
+    pThis->fIsInMem = true;
+
+    for (uint32_t i = 0; i < RT_ELEMENTS(pThis->aoffLoadSegments); i++)
+        pThis->aoffLoadSegments[i] = UINTPTR_MAX;
+
+    /*
+     * Figure the search range based on a symbol that is supposed to be in
+     * kernel text segment, using it as the upper boundrary.  The lower boundary
+     * is determined by subtracting a max kernel size of 64MB (the largest kernel
+     * file, kernel.kasan, is around 45MB, but the end of __TEXT is about 27 MB,
+     * which means we should still have plenty of room for future growth with 64MB).
+     */
+    uintptr_t  const    uSomeKernelAddr   = (uintptr_t)&absolutetime_to_nanoseconds;
+    uintptr_t  const    uLowestKernelAddr = uSomeKernelAddr - _64M;
+
+    /*
+     * The kernel is probably aligned at some boundrary larger than a page size,
+     * so to speed things up we start by assuming the alignment is page directory
+     * sized.  In case we're wrong and it's smaller, we decrease the alignment till
+     * we've reach the page size.
+     */
+    uintptr_t           fPrevAlignMask    = ~(uintptr_t)0;
+    uintptr_t           uCurAlign         = _2M;                    /* ASSUMES the kernel is typically 2MB aligned. */
+    while (uCurAlign >= PAGE_SIZE)
+    {
+        /*
+         * Search down from the symbol address looking for a mach-O header that
+         * looks like it might belong to the kernel.
+         */
+        for (uintptr_t uCur = uSomeKernelAddr & ~(uCurAlign - 1); uCur >= uLowestKernelAddr; uCur -= uCurAlign)
+        {
+            /* Skip pages we've checked in previous iterations and pages that aren't present: */
+            /** @todo This is a little bogus in case the header is paged out. */
+            if (   (uCur & fPrevAlignMask)
+                && rtR0DbgKrnlDarwinIsPagePresent(uCur))
+            {
+                /*
+                 * Look for valid mach-o header (we skip cpusubtype on purpose here).
+                 */
+                MY_MACHO_HEADER const volatile *pHdr = (MY_MACHO_HEADER const volatile *)uCur;
+                if (   pHdr->magic    == MY_MACHO_MAGIC
+                    && pHdr->filetype == MH_EXECUTE
+                    && pHdr->cputype  == MY_CPU_TYPE)
+                {
+                    /* More header validation: */
+                    pThis->cLoadCmds  = pHdr->ncmds;
+                    pThis->cbLoadCmds = pHdr->sizeofcmds;
+                    if (pHdr->ncmds < 4)
+                        LOG_MISMATCH("RTR0DbgInfo: %p: ncmds=%u is too small\n", pHdr, pThis->cLoadCmds);
+                    else if (pThis->cLoadCmds > 256)
+                        LOG_MISMATCH("RTR0DbgInfo: %p: ncmds=%u is too big\n", pHdr, pThis->cLoadCmds);
+                    else if (pThis->cbLoadCmds <= pThis->cLoadCmds * sizeof(load_command_t))
+                        LOG_MISMATCH("RTR0DbgInfo: %p: sizeofcmds=%u is too small for ncmds=%u\n",
+                                     pHdr, pThis->cbLoadCmds, pThis->cLoadCmds);
+                    else if (pThis->cbLoadCmds >= _1M)
+                        LOG_MISMATCH("RTR0DbgInfo: %p: sizeofcmds=%u is too big\n", pHdr, pThis->cbLoadCmds);
+                    else if (pHdr->flags & ~MH_VALID_FLAGS)
+                        LOG_MISMATCH("RTR0DbgInfo: %p: invalid flags=%#x\n", pHdr, pHdr->flags);
+                    /*
+                     * Check that we can safely read the load commands, then parse & validate them.
+                     */
+                    else if (rtR0DbgKrnlDarwinIsRangePresent((uintptr_t)(pHdr + 1), pThis->cbLoadCmds, "load commands", pHdr))
+                    {
+                        pThis->pLoadCmds = (load_command_t *)(pHdr + 1);
+                        int rc = rtR0DbgKrnlDarwinParseCommands(pThis);
+                        if (RT_SUCCESS(rc))
+                        {
+                            /* Calculate the slide value.  This is typically zero as the
+                               load commands has been relocated (the case with 10.14.0 at least). */
+                            /** @todo ASSUMES that the __TEXT segment comes first and includes the
+                             *        mach-o header and load commands and all that. */
+                            pThis->offLoad = uCur - pThis->uTextSegLinkAddr;
+
+                            /* Check that the kernel symbol is in the text segment: */
+                            uintptr_t const offSomeKernAddr = uSomeKernelAddr - uCur;
+                            if (offSomeKernAddr >= pThis->cbTextSeg)
+                                LOG_MISMATCH("RTR0DbgInfo: %p: Our symbol at %zx (off %zx) isn't within the text segment (size %#zx)\n",
+                                             pHdr, uSomeKernelAddr, offSomeKernAddr, pThis->cbTextSeg);
+                            /*
+                             * Parse the symbol+string tables.
+                             */
+                            else if (pThis->uSymTabLinkAddr == 0)
+                                LOG_MISMATCH("RTR0DbgInfo: %p: No symbol table VA (off %#x L %#x)\n",
+                                             pHdr, pThis->offSyms, pThis->cSyms);
+                            else if (pThis->uStrTabLinkAddr == 0)
+                                LOG_MISMATCH("RTR0DbgInfo: %p: No string table VA (off %#x LB %#x)\n",
+                                             pHdr, pThis->offSyms, pThis->cbStrTab);
+                            else if (   rtR0DbgKrnlDarwinIsRangePresent(pThis->uStrTabLinkAddr + pThis->offLoad,
+                                                                        pThis->cbStrTab, "string table", pHdr)
+                                     && rtR0DbgKrnlDarwinIsRangePresent(pThis->uSymTabLinkAddr + pThis->offLoad,
+                                                                        pThis->cSyms * sizeof(pThis->paSyms),
+                                                                        "symbol table", pHdr))
+                            {
+                                pThis->pachStrTab = (char *)pThis->uStrTabLinkAddr + pThis->offLoad;
+                                pThis->paSyms = (MY_NLIST *)pThis->uSymTabLinkAddr + pThis->offLoad;
+                                rc = rtR0DbgKrnlDarwinParseSymTab(pThis, "in-memory");
+                                if (RT_SUCCESS(rc))
+                                {
+                                    rc = rtR0DbgKrnlDarwinInitLoadDisplacements(pThis);
+                                    if (RT_SUCCESS(rc))
+                                    {
+                                        /*
+                                         * Finally check the standard candles.
+                                         */
+                                        rc = rtR0DbgKrnlDarwinCheckStandardSymbols(pThis, "in-memory");
+                                        rtR0DbgKrnlDarwinLoadDone(pThis);
+                                        if (RT_SUCCESS(rc))
+                                            return rtR0DbgKrnlDarwinSuccess(phKrnlInfo, pThis, "in-memory");
+                                    }
+                                }
+                            }
+                        }
+
+                        RT_ZERO(pThis->apSections);
+                        RT_ZERO(pThis->apSegments);
+                        pThis->pLoadCmds = NULL;
+                    }
+                }
+            }
+        }
+
+        fPrevAlignMask = uCurAlign - 1;
+        uCurAlign >>= 1;
+    }
+
+    RTMemFree(pThis);
+    return VERR_GENERAL_FAILURE;
+}
+
+#endif /* IN_RING0 */
+
+RTR0DECL(int) RTR0DbgKrnlInfoOpen(PRTDBGKRNLINFO phKrnlInfo, uint32_t fFlags)
+{
+    AssertPtrReturn(phKrnlInfo, VERR_INVALID_POINTER);
+    *phKrnlInfo = NIL_RTDBGKRNLINFO;
+    AssertReturn(!fFlags, VERR_INVALID_PARAMETER);
+
+#ifdef IN_RING0
+    /*
+     * Try see if we can use the kernel memory directly.  This depends on not
+     * having the __LINKEDIT segment jettisoned or swapped out.  For older
+     * kernels this is typically the case, unless kallsyms=1 is in boot-args.
+     */
+    int rc = rtR0DbgKrnlDarwinOpenInMemory(phKrnlInfo);
+    if (RT_SUCCESS(rc))
+    {
+        Log(("RTR0DbgKrnlInfoOpen: Using in-memory kernel.\n"));
+        return rc;
+    }
+#else
+    int rc = VERR_WRONG_ORDER; /* shut up stupid MSC */
+#endif
+
+    /*
+     * Go thru likely kernel locations
+     *
+     * Note! Check the OS X version and reorder the list?
+     * Note! We should try fish kcsuffix out of bootargs or somewhere one day.
+     */
+    static bool s_fFirstCall = true;
+#ifdef IN_RING3
+    extern const char *g_pszTestKernel;
+#endif
+    struct
+    {
+        const char *pszLocation;
+        int         rc;
+    } aKernels[] =
+    {
+#ifdef IN_RING3
+        { g_pszTestKernel, VERR_WRONG_ORDER },
+#endif
+        { "/System/Library/Kernels/kernel", VERR_WRONG_ORDER },
+        { "/System/Library/Kernels/kernel.development", VERR_WRONG_ORDER },
+        { "/System/Library/Kernels/kernel.debug", VERR_WRONG_ORDER },
+        { "/mach_kernel", VERR_WRONG_ORDER },
+    };
+    for (uint32_t i = 0; i < RT_ELEMENTS(aKernels); i++)
+    {
+        aKernels[i].rc = rc = rtR0DbgKrnlDarwinOpen(phKrnlInfo, aKernels[i].pszLocation);
+        if (RT_SUCCESS(rc))
+        {
+            if (s_fFirstCall)
+            {
+                printf("RTR0DbgKrnlInfoOpen: Using kernel file '%s'\n", aKernels[i].pszLocation);
+                s_fFirstCall = false;
+            }
+            return rc;
+        }
+    }
+
+    /*
+     * Failed.
+     */
+    /* Pick the best error code. */
+    for (uint32_t i = 0; rc == VERR_FILE_NOT_FOUND && i < RT_ELEMENTS(aKernels); i++)
+        if (aKernels[i].rc != VERR_FILE_NOT_FOUND)
+            rc = aKernels[i].rc;
+
+    /* Bitch about it. */
+    printf("RTR0DbgKrnlInfoOpen: failed to find matching kernel file! rc=%d\n", rc);
+    if (s_fFirstCall)
+    {
+        for (uint32_t i = 0; i < RT_ELEMENTS(aKernels); i++)
+            printf("RTR0DbgKrnlInfoOpen: '%s' -> %d\n", aKernels[i].pszLocation, aKernels[i].rc);
+        s_fFirstCall = false;
+    }
+
+    return rc;
+}
+
+
+RTR0DECL(uint32_t) RTR0DbgKrnlInfoRetain(RTDBGKRNLINFO hKrnlInfo)
+{
+    RTDBGKRNLINFOINT *pThis = hKrnlInfo;
+    AssertPtrReturn(pThis, UINT32_MAX);
+    AssertMsgReturn(pThis->u32Magic == RTDBGKRNLINFO_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), UINT32_MAX);
+
+    uint32_t cRefs = ASMAtomicIncU32(&pThis->cRefs);
+    Assert(cRefs && cRefs < 100000);
+    return cRefs;
+}
+
+
+RTR0DECL(uint32_t) RTR0DbgKrnlInfoRelease(RTDBGKRNLINFO hKrnlInfo)
+{
+    RTDBGKRNLINFOINT *pThis = hKrnlInfo;
+    if (pThis == NIL_RTDBGKRNLINFO)
+        return 0;
+    AssertPtrReturn(pThis, UINT32_MAX);
+    AssertMsgReturn(pThis->u32Magic == RTDBGKRNLINFO_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), UINT32_MAX);
+
+    uint32_t cRefs = ASMAtomicDecU32(&pThis->cRefs);
+    if (cRefs == 0)
+        rtR0DbgKrnlDarwinDtor(pThis);
+    return cRefs;
+}
+
+
+RTR0DECL(int) RTR0DbgKrnlInfoQueryMember(RTDBGKRNLINFO hKrnlInfo, const char *pszModule, const char *pszStructure,
+                                         const char *pszMember, size_t *poffMember)
+{
+    RTDBGKRNLINFOINT *pThis = hKrnlInfo;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTDBGKRNLINFO_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+    AssertPtrReturn(pszMember, VERR_INVALID_POINTER);
+    AssertPtrReturn(pszModule, VERR_INVALID_POINTER);
+    AssertPtrReturn(pszStructure, VERR_INVALID_POINTER);
+    AssertPtrReturn(poffMember, VERR_INVALID_POINTER);
+    return VERR_NOT_FOUND;
+}
+
+
+RTR0DECL(int) RTR0DbgKrnlInfoQuerySymbol(RTDBGKRNLINFO hKrnlInfo, const char *pszModule,
+                                         const char *pszSymbol, void **ppvSymbol)
+{
+    RTDBGKRNLINFOINT *pThis = hKrnlInfo;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTDBGKRNLINFO_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+    AssertPtrReturn(pszSymbol, VERR_INVALID_PARAMETER);
+    AssertPtrNullReturn(ppvSymbol, VERR_INVALID_PARAMETER);
+    AssertReturn(!pszModule, VERR_MODULE_NOT_FOUND);
+
+    uintptr_t uValue = rtR0DbgKrnlDarwinLookup(pThis, pszSymbol);
+    if (ppvSymbol)
+        *ppvSymbol = (void *)uValue;
+    if (uValue)
+        return VINF_SUCCESS;
+    return VERR_SYMBOL_NOT_FOUND;
+}
+
diff --git a/src/VBox/Runtime/r0drv/darwin/fileio-r0drv-darwin.cpp b/src/VBox/Runtime/r0drv/darwin/fileio-r0drv-darwin.cpp
new file mode 100644
index 00000000..3a4f7a7d
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/fileio-r0drv-darwin.cpp
@@ -0,0 +1,311 @@
+/* $Id: fileio-r0drv-darwin.cpp $ */
+/** @file
+ * IPRT - File I/O, R0 Driver, Darwin.
+ */
+
+/*
+ * Copyright (C) 2011-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-darwin-kernel.h"
+
+#include <iprt/file.h>
+#include "internal/iprt.h"
+
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/log.h>
+#include <iprt/mem.h>
+#include <iprt/string.h>
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/** Default file permissions for newly created files. */
+#if defined(S_IRUSR) && defined(S_IWUSR)
+# define RT_FILE_PERMISSION  (S_IRUSR | S_IWUSR)
+#else
+# define RT_FILE_PERMISSION  (00600)
+#endif
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Darwin kernel file handle data.
+ */
+typedef struct RTFILEINT
+{
+    /** Magic value (RTFILE_MAGIC). */
+    uint32_t        u32Magic;
+    /** The open mode flags passed to the kernel API. */
+    int             fOpenMode;
+    /** The open flags passed to RTFileOpen. */
+    uint64_t        fOpen;
+    /** The VFS context in which the file was opened. */
+    vfs_context_t   hVfsCtx;
+    /** The vnode returned by vnode_open. */
+    vnode_t         hVnode;
+    /** The current file offset. */
+    uint64_t        offFile;
+} RTFILEINT;
+/** Magic number for RTFILEINT::u32Magic (To Be Determined). */
+#define RTFILE_MAGIC                    UINT32_C(0x01020304)
+
+
+RTDECL(int) RTFileOpen(PRTFILE phFile, const char *pszFilename, uint64_t fOpen)
+{
+    RTFILEINT *pThis = (RTFILEINT *)RTMemAllocZ(sizeof(*pThis));
+    if (!pThis)
+        return VERR_NO_MEMORY;
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    errno_t rc;
+    pThis->u32Magic = RTFILE_MAGIC;
+    pThis->fOpen    = fOpen;
+    pThis->hVfsCtx  = vfs_context_current();
+    if (pThis->hVfsCtx != NULL)
+    {
+        int             fCMode    = (fOpen & RTFILE_O_CREATE_MODE_MASK)
+                                  ? (fOpen & RTFILE_O_CREATE_MODE_MASK) >> RTFILE_O_CREATE_MODE_SHIFT
+                                  : RT_FILE_PERMISSION;
+        int             fVnFlags  = 0; /* VNODE_LOOKUP_XXX */
+        int             fOpenMode = 0;
+        if (fOpen & RTFILE_O_NON_BLOCK)
+            fOpenMode |= O_NONBLOCK;
+        if (fOpen & RTFILE_O_WRITE_THROUGH)
+            fOpenMode |= O_SYNC;
+
+        /* create/truncate file */
+        switch (fOpen & RTFILE_O_ACTION_MASK)
+        {
+            case RTFILE_O_OPEN:             break;
+            case RTFILE_O_OPEN_CREATE:      fOpenMode |= O_CREAT; break;
+            case RTFILE_O_CREATE:           fOpenMode |= O_CREAT | O_EXCL; break;
+            case RTFILE_O_CREATE_REPLACE:   fOpenMode |= O_CREAT | O_TRUNC; break; /** @todo replacing needs fixing, this is *not* a 1:1 mapping! */
+        }
+        if (fOpen & RTFILE_O_TRUNCATE)
+            fOpenMode |= O_TRUNC;
+
+        switch (fOpen & RTFILE_O_ACCESS_MASK)
+        {
+            case RTFILE_O_READ:
+                fOpenMode |= FREAD;
+                break;
+            case RTFILE_O_WRITE:
+                fOpenMode |= fOpen & RTFILE_O_APPEND ? O_APPEND | FWRITE : FWRITE;
+                break;
+            case RTFILE_O_READWRITE:
+                fOpenMode |= fOpen & RTFILE_O_APPEND ? O_APPEND | FWRITE | FREAD : FWRITE | FREAD;
+                break;
+            default:
+                AssertMsgFailed(("RTFileOpen received an invalid RW value, fOpen=%#x\n", fOpen));
+                IPRT_DARWIN_RESTORE_EFL_AC();
+                return VERR_INVALID_PARAMETER;
+        }
+
+        pThis->fOpenMode = fOpenMode;
+        rc = vnode_open(pszFilename, fOpenMode, fCMode, fVnFlags, &pThis->hVnode, pThis->hVfsCtx);
+        if (rc == 0)
+        {
+            *phFile = pThis;
+            IPRT_DARWIN_RESTORE_EFL_AC();
+            return VINF_SUCCESS;
+        }
+
+        rc = RTErrConvertFromErrno(rc);
+    }
+    else
+        rc = VERR_INTERNAL_ERROR_5;
+    RTMemFree(pThis);
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return rc;
+}
+
+
+RTDECL(int) RTFileClose(RTFILE hFile)
+{
+    if (hFile == NIL_RTFILE)
+        return VINF_SUCCESS;
+
+    RTFILEINT *pThis = hFile;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertReturn(pThis->u32Magic == RTFILE_MAGIC, VERR_INVALID_HANDLE);
+    pThis->u32Magic = ~RTFILE_MAGIC;
+
+    IPRT_DARWIN_SAVE_EFL_AC();
+    errno_t rc = vnode_close(pThis->hVnode, pThis->fOpenMode & (FREAD | FWRITE), pThis->hVfsCtx);
+    IPRT_DARWIN_RESTORE_EFL_AC();
+
+    RTMemFree(pThis);
+    return RTErrConvertFromErrno(rc);
+}
+
+
+RTDECL(int) RTFileReadAt(RTFILE hFile, RTFOFF off, void *pvBuf, size_t cbToRead, size_t *pcbRead)
+{
+    RTFILEINT *pThis = hFile;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertReturn(pThis->u32Magic == RTFILE_MAGIC, VERR_INVALID_HANDLE);
+
+    off_t offNative = (off_t)off;
+    AssertReturn((RTFOFF)offNative == off, VERR_OUT_OF_RANGE);
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+#if 0 /* Added in 10.6, grr. */
+    errno_t rc;
+    if (!pcbRead)
+        rc = vn_rdwr(UIO_READ, pThis->hVnode, (char *)pvBuf, cbToRead, offNative, UIO_SYSSPACE, 0 /*ioflg*/,
+                     vfs_context_ucred(pThis->hVfsCtx), NULL, vfs_context_proc(pThis->hVfsCtx));
+    else
+    {
+        int cbLeft = 0;
+        rc = vn_rdwr(UIO_READ, pThis->hVnode, (char *)pvBuf, cbToRead, offNative, UIO_SYSSPACE, 0 /*ioflg*/,
+                     vfs_context_ucred(pThis->hVfsCtx), &cbLeft, vfs_context_proc(pThis->hVfsCtx));
+        *pcbRead = cbToRead - cbLeft;
+    }
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return !rc ? VINF_SUCCESS : RTErrConvertFromErrno(rc);
+
+#else
+    uio_t hUio = uio_create(1, offNative, UIO_SYSSPACE, UIO_READ);
+    if (!hUio)
+    {
+        IPRT_DARWIN_RESTORE_EFL_AC();
+        return VERR_NO_MEMORY;
+    }
+    errno_t rc;
+    if (uio_addiov(hUio, (user_addr_t)(uintptr_t)pvBuf, cbToRead) == 0)
+    {
+        rc = VNOP_READ(pThis->hVnode, hUio, 0 /*ioflg*/, pThis->hVfsCtx);
+        off_t const cbActual = cbToRead - uio_resid(hUio);
+        if (pcbRead)
+            *pcbRead = cbActual;
+        if (rc == 0)
+        {
+            pThis->offFile += (uint64_t)cbActual;
+            if (cbToRead != (uint64_t)cbActual)
+                rc = VERR_FILE_IO_ERROR;
+        }
+        else
+            rc = RTErrConvertFromErrno(rc);
+    }
+    else
+        rc = VERR_INTERNAL_ERROR_3;
+    uio_free(hUio);
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return rc;
+#endif
+}
+
+
+RTDECL(int) RTFileRead(RTFILE hFile, void *pvBuf, size_t cbToRead, size_t *pcbRead)
+{
+    RTFILEINT *pThis = hFile;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertReturn(pThis->u32Magic == RTFILE_MAGIC, VERR_INVALID_HANDLE);
+
+    return RTFileReadAt(hFile, pThis->offFile, pvBuf, cbToRead, pcbRead);
+}
+
+
+RTDECL(int) RTFileQuerySize(RTFILE hFile, uint64_t *pcbSize)
+{
+    RTFILEINT *pThis = hFile;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertReturn(pThis->u32Magic == RTFILE_MAGIC, VERR_INVALID_HANDLE);
+
+    /*
+     * Query the data size attribute.
+     * Note! Allocate extra attribute buffer space to be on the safe side.
+     */
+    union
+    {
+        struct vnode_attr VAttr;
+        uint8_t             abPadding[sizeof(struct vnode_attr) * 2];
+    } uBuf;
+    RT_ZERO(uBuf);
+    struct vnode_attr *pVAttr = &uBuf.VAttr;
+
+    VATTR_INIT(pVAttr);
+    VATTR_WANTED(pVAttr, va_data_size);
+
+    errno_t rc = vnode_getattr(pThis->hVnode, pVAttr, pThis->hVfsCtx);
+    if (!rc)
+    {
+        *pcbSize = pVAttr->va_data_size;
+        return VINF_SUCCESS;
+    }
+    return RTErrConvertFromErrno(rc);
+}
+
+
+RTDECL(int) RTFileSeek(RTFILE hFile, int64_t offSeek, unsigned uMethod, uint64_t *poffActual)
+{
+    RTFILEINT *pThis = hFile;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertReturn(pThis->u32Magic == RTFILE_MAGIC, VERR_INVALID_HANDLE);
+
+    uint64_t offNew;
+    switch (uMethod)
+    {
+        case RTFILE_SEEK_BEGIN:
+            AssertReturn(offSeek >= 0, VERR_NEGATIVE_SEEK);
+            offNew = offSeek;
+            break;
+
+        case RTFILE_SEEK_CURRENT:
+            offNew = pThis->offFile + offSeek;
+            break;
+
+        case RTFILE_SEEK_END:
+        {
+            uint64_t cbFile = 0;
+            int rc = RTFileQuerySize(hFile, &cbFile);
+            if (RT_SUCCESS(rc))
+                offNew = cbFile + offSeek;
+            else
+                return rc;
+            break;
+        }
+
+        default:
+            return VERR_INVALID_PARAMETER;
+    }
+
+    if ((RTFOFF)offNew >= 0)
+    {
+        pThis->offFile = offNew;
+        if (poffActual)
+            *poffActual = offNew;
+        return VINF_SUCCESS;
+    }
+    return VERR_NEGATIVE_SEEK;
+}
+
diff --git a/src/VBox/Runtime/r0drv/darwin/initterm-r0drv-darwin.cpp b/src/VBox/Runtime/r0drv/darwin/initterm-r0drv-darwin.cpp
new file mode 100644
index 00000000..bb83efb9
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/initterm-r0drv-darwin.cpp
@@ -0,0 +1,123 @@
+/* $Id: initterm-r0drv-darwin.cpp $ */
+/** @file
+ * IPRT - Initialization & Termination, R0 Driver, Darwin.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-darwin-kernel.h"
+#include "internal/iprt.h"
+
+#include <iprt/errcore.h>
+#include <iprt/assert.h>
+#include <iprt/dbg.h>
+#include "internal/initterm.h"
+
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/** Pointer to the lock group used by IPRT. */
+lck_grp_t                  *g_pDarwinLockGroup = NULL;
+/** Pointer to the ast_pending function, if found. */
+PFNR0DARWINASTPENDING       g_pfnR0DarwinAstPending = NULL;
+/** Pointer to the cpu_interrupt function, if found. */
+PFNR0DARWINCPUINTERRUPT     g_pfnR0DarwinCpuInterrupt = NULL;
+#ifdef DEBUG
+/** Pointer to the vm_fault_external function - used once for debugging @bugref{9466}. */
+PFNR0DARWINVMFAULTEXTERNAL  g_pfnR0DarwinVmFaultExternal = NULL;
+#endif
+
+
+DECLHIDDEN(int) rtR0InitNative(void)
+{
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    /*
+     * Create the lock group.
+     */
+    g_pDarwinLockGroup = lck_grp_alloc_init("IPRT", LCK_GRP_ATTR_NULL);
+    AssertReturn(g_pDarwinLockGroup, VERR_NO_MEMORY);
+
+    /*
+     * Initialize the preemption hacks.
+     */
+    int rc = rtThreadPreemptDarwinInit();
+    if (RT_SUCCESS(rc))
+    {
+        /*
+         * Try resolve kernel symbols we need but apple don't wish to give us.
+         */
+        RTDBGKRNLINFO hKrnlInfo;
+        rc = RTR0DbgKrnlInfoOpen(&hKrnlInfo, 0 /*fFlags*/);
+        if (RT_SUCCESS(rc))
+        {
+            RTR0DbgKrnlInfoQuerySymbol(hKrnlInfo, NULL, "ast_pending",   (void **)&g_pfnR0DarwinAstPending);
+            printf("ast_pending=%p\n", g_pfnR0DarwinAstPending);
+            RTR0DbgKrnlInfoQuerySymbol(hKrnlInfo, NULL, "cpu_interrupt", (void **)&g_pfnR0DarwinCpuInterrupt);
+            printf("cpu_interrupt=%p\n", g_pfnR0DarwinCpuInterrupt);
+#ifdef DEBUG
+            RTR0DbgKrnlInfoQuerySymbol(hKrnlInfo, NULL, "vm_fault_external", (void **)&g_pfnR0DarwinVmFaultExternal);
+            printf("vm_fault_external=%p\n", g_pfnR0DarwinVmFaultExternal);
+#endif
+            RTR0DbgKrnlInfoRelease(hKrnlInfo);
+        }
+        if (RT_FAILURE(rc))
+        {
+            printf("rtR0InitNative: warning! failed to resolve special kernel symbols\n");
+            rc = VINF_SUCCESS;
+        }
+    }
+    if (RT_FAILURE(rc))
+        rtR0TermNative();
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return rc;
+}
+
+
+DECLHIDDEN(void) rtR0TermNative(void)
+{
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    /*
+     * Preemption hacks before the lock group.
+     */
+    rtThreadPreemptDarwinTerm();
+
+    /*
+     * Free the lock group.
+     */
+    if (g_pDarwinLockGroup)
+    {
+        lck_grp_free(g_pDarwinLockGroup);
+        g_pDarwinLockGroup = NULL;
+    }
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+}
+
diff --git a/src/VBox/Runtime/r0drv/darwin/memobj-r0drv-darwin.cpp b/src/VBox/Runtime/r0drv/darwin/memobj-r0drv-darwin.cpp
new file mode 100644
index 00000000..2c31df56
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/memobj-r0drv-darwin.cpp
@@ -0,0 +1,1536 @@
+/* $Id: memobj-r0drv-darwin.cpp $ */
+/** @file
+ * IPRT - Ring-0 Memory Objects, Darwin.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTMEM_NO_WRAP_TO_EF_APIS /* circular dependency otherwise. */
+#include "the-darwin-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/memobj.h>
+
+#include <iprt/asm.h>
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/x86.h>
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/assert.h>
+#include <iprt/log.h>
+#include <iprt/mem.h>
+#include <iprt/param.h>
+#include <iprt/process.h>
+#include <iprt/semaphore.h>
+#include <iprt/string.h>
+#include <iprt/thread.h>
+#include "internal/memobj.h"
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+#define MY_PRINTF(...) do { printf(__VA_ARGS__); kprintf(__VA_ARGS__); } while (0)
+
+/*#define USE_VM_MAP_WIRE - may re-enable later when non-mapped allocations are added. */
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * The Darwin version of the memory object structure.
+ */
+typedef struct RTR0MEMOBJDARWIN
+{
+    /** The core structure. */
+    RTR0MEMOBJINTERNAL  Core;
+    /** Pointer to the memory descriptor created for allocated and locked memory. */
+    IOMemoryDescriptor *pMemDesc;
+    /** Pointer to the memory mapping object for mapped memory. */
+    IOMemoryMap        *pMemMap;
+} RTR0MEMOBJDARWIN, *PRTR0MEMOBJDARWIN;
+
+/**
+ * Common thread_call_allocate/thread_call_enter argument package.
+ */
+typedef struct RTR0MEMOBJDARWINTHREADARGS
+{
+    int32_t volatile        rc;
+    RTSEMEVENTMULTI         hEvent;
+} RTR0MEMOBJDARWINTHREADARGS;
+
+
+/**
+ * Arguments for rtR0MemObjNativeAllockWorkOnKernelThread.
+ */
+typedef struct RTR0MEMOBJDARWINALLOCARGS
+{
+    RTR0MEMOBJDARWINTHREADARGS Core;
+    PPRTR0MEMOBJINTERNAL    ppMem;
+    size_t                  cb;
+    bool                    fExecutable;
+    bool                    fContiguous;
+    mach_vm_address_t       PhysMask;
+    uint64_t                MaxPhysAddr;
+    RTR0MEMOBJTYPE          enmType;
+    size_t                  uAlignment;
+} RTR0MEMOBJDARWINALLOCARGS;
+
+/**
+ * Arguments for rtR0MemObjNativeProtectWorkOnKernelThread.
+ */
+typedef struct RTR0MEMOBJDARWINPROTECTARGS
+{
+    RTR0MEMOBJDARWINTHREADARGS Core;
+    PRTR0MEMOBJINTERNAL     pMem;
+    size_t                  offSub;
+    size_t                  cbSub;
+    uint32_t                fProt;
+} RTR0MEMOBJDARWINPROTECTARGS;
+
+
+/*********************************************************************************************************************************
+*   Internal Functions                                                                                                           *
+*********************************************************************************************************************************/
+static void rtR0MemObjNativeAllockWorkerOnKernelThread(void *pvUser0, void *pvUser1);
+static int  rtR0MemObjNativeProtectWorker(PRTR0MEMOBJINTERNAL pMem, size_t offSub, size_t cbSub, uint32_t fProt);
+static void rtR0MemObjNativeProtectWorkerOnKernelThread(void *pvUser0, void *pvUser1);
+
+
+/**
+ * Touch the pages to force the kernel to create or write-enable the page table
+ * entries.
+ *
+ * This is necessary since the kernel gets upset if we take a page fault when
+ * preemption is disabled and/or we own a simple lock (same thing).  It has no
+ * problems with us disabling interrupts when taking the traps, weird stuff.
+ *
+ * (This is basically a way of invoking vm_fault on a range of pages.)
+ *
+ * @param  pv           Pointer to the first page.
+ * @param  cb           The number of bytes.
+ */
+static void rtR0MemObjDarwinTouchPages(void *pv, size_t cb)
+{
+    uint32_t volatile  *pu32 = (uint32_t volatile *)pv;
+    for (;;)
+    {
+        ASMAtomicCmpXchgU32(pu32, 0xdeadbeef, 0xdeadbeef);
+        if (cb <= PAGE_SIZE)
+            break;
+        cb -= PAGE_SIZE;
+        pu32 += PAGE_SIZE / sizeof(uint32_t);
+    }
+}
+
+
+/**
+ * Read (sniff) every page in the range to make sure there are some page tables
+ * entries backing it.
+ *
+ * This is just to be sure vm_protect didn't remove stuff without re-adding it
+ * if someone should try write-protect something.
+ *
+ * @param  pv           Pointer to the first page.
+ * @param  cb           The number of bytes.
+ */
+static void rtR0MemObjDarwinSniffPages(void const *pv, size_t cb)
+{
+    uint32_t volatile  *pu32 = (uint32_t volatile *)pv;
+    uint32_t volatile   u32Counter = 0;
+    for (;;)
+    {
+        u32Counter += *pu32;
+
+        if (cb <= PAGE_SIZE)
+            break;
+        cb -= PAGE_SIZE;
+        pu32 += PAGE_SIZE / sizeof(uint32_t);
+    }
+}
+
+
+/**
+ * Gets the virtual memory map the specified object is mapped into.
+ *
+ * @returns VM map handle on success, NULL if no map.
+ * @param   pMem                The memory object.
+ */
+DECLINLINE(vm_map_t) rtR0MemObjDarwinGetMap(PRTR0MEMOBJINTERNAL pMem)
+{
+    switch (pMem->enmType)
+    {
+        case RTR0MEMOBJTYPE_PAGE:
+        case RTR0MEMOBJTYPE_LOW:
+        case RTR0MEMOBJTYPE_CONT:
+            return kernel_map;
+
+        case RTR0MEMOBJTYPE_PHYS:
+        case RTR0MEMOBJTYPE_PHYS_NC:
+            if (pMem->pv)
+                return kernel_map;
+            return NULL;
+
+        case RTR0MEMOBJTYPE_LOCK:
+            return pMem->u.Lock.R0Process == NIL_RTR0PROCESS
+                ? kernel_map
+                : get_task_map((task_t)pMem->u.Lock.R0Process);
+
+        case RTR0MEMOBJTYPE_RES_VIRT:
+            return pMem->u.ResVirt.R0Process == NIL_RTR0PROCESS
+                ? kernel_map
+                : get_task_map((task_t)pMem->u.ResVirt.R0Process);
+
+        case RTR0MEMOBJTYPE_MAPPING:
+            return pMem->u.Mapping.R0Process == NIL_RTR0PROCESS
+                ? kernel_map
+                : get_task_map((task_t)pMem->u.Mapping.R0Process);
+
+        default:
+            return NULL;
+    }
+}
+
+#if 0 /* not necessary after all*/
+/* My vm_map mockup. */
+struct my_vm_map
+{
+    struct { char pad[8]; } lock;
+    struct my_vm_map_header
+    {
+        struct vm_map_links
+        {
+            void            *prev;
+            void            *next;
+            vm_map_offset_t start;
+            vm_map_offset_t end;
+        }                   links;
+        int                 nentries;
+        boolean_t           entries_pageable;
+    }                       hdr;
+    pmap_t                  pmap;
+    vm_map_size_t           size;
+};
+
+
+/**
+ * Gets the minimum map address, this is similar to get_map_min.
+ *
+ * @returns The start address of the map.
+ * @param   pMap                The map.
+ */
+static vm_map_offset_t rtR0MemObjDarwinGetMapMin(vm_map_t pMap)
+{
+    /* lazy discovery of the correct offset. The apple guys is a wonderfully secretive bunch. */
+    static int32_t volatile s_offAdjust = INT32_MAX;
+    int32_t                 off         = s_offAdjust;
+    if (off == INT32_MAX)
+    {
+        for (off = 0; ; off += sizeof(pmap_t))
+        {
+            if (*(pmap_t *)((uint8_t *)kernel_map + off) == kernel_pmap)
+                break;
+            AssertReturn(off <= RT_MAX(RT_OFFSETOF(struct my_vm_map, pmap) * 4, 1024), 0x1000);
+        }
+        ASMAtomicWriteS32(&s_offAdjust, off - RT_OFFSETOF(struct my_vm_map, pmap));
+    }
+
+    /* calculate it. */
+    struct my_vm_map *pMyMap = (struct my_vm_map *)((uint8_t *)pMap + off);
+    return pMyMap->hdr.links.start;
+}
+#endif /* unused */
+
+#ifdef RT_STRICT
+# if 0 /* unused */
+
+/**
+ * Read from a physical page.
+ *
+ * @param   HCPhys      The address to start reading at.
+ * @param   cb          How many bytes to read.
+ * @param   pvDst       Where to put the bytes. This is zero'd on failure.
+ */
+static void rtR0MemObjDarwinReadPhys(RTHCPHYS HCPhys, size_t cb, void *pvDst)
+{
+    memset(pvDst, '\0', cb);
+
+    IOAddressRange      aRanges[1]  = { { (mach_vm_address_t)HCPhys, RT_ALIGN_Z(cb, PAGE_SIZE) } };
+    IOMemoryDescriptor *pMemDesc    = IOMemoryDescriptor::withAddressRanges(&aRanges[0], RT_ELEMENTS(aRanges),
+                                                                            kIODirectionIn, NULL /*task*/);
+    if (pMemDesc)
+    {
+#if MAC_OS_X_VERSION_MIN_REQUIRED >= 1050
+        IOMemoryMap *pMemMap = pMemDesc->createMappingInTask(kernel_task, 0, kIOMapAnywhere | kIOMapDefaultCache);
+#else
+        IOMemoryMap *pMemMap = pMemDesc->map(kernel_task, 0, kIOMapAnywhere | kIOMapDefaultCache);
+#endif
+        if (pMemMap)
+        {
+            void const *pvSrc = (void const *)(uintptr_t)pMemMap->getVirtualAddress();
+            memcpy(pvDst, pvSrc, cb);
+            pMemMap->release();
+        }
+        else
+            MY_PRINTF("rtR0MemObjDarwinReadPhys: createMappingInTask failed; HCPhys=%llx\n", HCPhys);
+
+        pMemDesc->release();
+    }
+    else
+        MY_PRINTF("rtR0MemObjDarwinReadPhys: withAddressRanges failed; HCPhys=%llx\n", HCPhys);
+}
+
+
+/**
+ * Gets the PTE for a page.
+ *
+ * @returns the PTE.
+ * @param   pvPage      The virtual address to get the PTE for.
+ */
+static uint64_t rtR0MemObjDarwinGetPTE(void *pvPage)
+{
+    RTUINT64U   u64;
+    RTCCUINTREG cr3 = ASMGetCR3();
+    RTCCUINTREG cr4 = ASMGetCR4();
+    bool        fPAE = false;
+    bool        fLMA = false;
+    if (cr4 & X86_CR4_PAE)
+    {
+        fPAE = true;
+        uint32_t fExtFeatures = ASMCpuId_EDX(0x80000001);
+        if (fExtFeatures & X86_CPUID_EXT_FEATURE_EDX_LONG_MODE)
+        {
+            uint64_t efer = ASMRdMsr(MSR_K6_EFER);
+            if (efer & MSR_K6_EFER_LMA)
+                fLMA = true;
+        }
+    }
+
+    if (fLMA)
+    {
+        /* PML4 */
+        rtR0MemObjDarwinReadPhys((cr3 & ~(RTCCUINTREG)PAGE_OFFSET_MASK) | (((uint64_t)(uintptr_t)pvPage >> X86_PML4_SHIFT) & X86_PML4_MASK) * 8, 8, &u64);
+        if (!(u64.u & X86_PML4E_P))
+        {
+            MY_PRINTF("rtR0MemObjDarwinGetPTE: %p -> PML4E !p\n", pvPage);
+            return 0;
+        }
+
+        /* PDPTR */
+        rtR0MemObjDarwinReadPhys((u64.u & ~(uint64_t)PAGE_OFFSET_MASK) | (((uintptr_t)pvPage >> X86_PDPT_SHIFT) & X86_PDPT_MASK_AMD64) * 8, 8, &u64);
+        if (!(u64.u & X86_PDPE_P))
+        {
+            MY_PRINTF("rtR0MemObjDarwinGetPTE: %p -> PDPTE !p\n", pvPage);
+            return 0;
+        }
+        if (u64.u & X86_PDPE_LM_PS)
+            return (u64.u & ~(uint64_t)(_1G -1)) | ((uintptr_t)pvPage & (_1G -1));
+
+        /* PD */
+        rtR0MemObjDarwinReadPhys((u64.u & ~(uint64_t)PAGE_OFFSET_MASK) | (((uintptr_t)pvPage >> X86_PD_PAE_SHIFT) & X86_PD_PAE_MASK) * 8, 8, &u64);
+        if (!(u64.u & X86_PDE_P))
+        {
+            MY_PRINTF("rtR0MemObjDarwinGetPTE: %p -> PDE !p\n", pvPage);
+            return 0;
+        }
+        if (u64.u & X86_PDE_PS)
+            return (u64.u & ~(uint64_t)(_2M -1)) | ((uintptr_t)pvPage & (_2M -1));
+
+        /* PT */
+        rtR0MemObjDarwinReadPhys((u64.u & ~(uint64_t)PAGE_OFFSET_MASK) | (((uintptr_t)pvPage >> X86_PT_PAE_SHIFT) & X86_PT_PAE_MASK) * 8, 8, &u64);
+        if (!(u64.u &  X86_PTE_P))
+        {
+            MY_PRINTF("rtR0MemObjDarwinGetPTE: %p -> PTE !p\n", pvPage);
+            return 0;
+        }
+        return u64.u;
+    }
+
+    if (fPAE)
+    {
+        /* PDPTR */
+        rtR0MemObjDarwinReadPhys((u64.u & X86_CR3_PAE_PAGE_MASK) | (((uintptr_t)pvPage >> X86_PDPT_SHIFT) & X86_PDPT_MASK_PAE) * 8, 8, &u64);
+        if (!(u64.u & X86_PDE_P))
+            return 0;
+
+        /* PD */
+        rtR0MemObjDarwinReadPhys((u64.u & ~(uint64_t)PAGE_OFFSET_MASK) | (((uintptr_t)pvPage >> X86_PD_PAE_SHIFT) & X86_PD_PAE_MASK) * 8, 8, &u64);
+        if (!(u64.u & X86_PDE_P))
+            return 0;
+        if (u64.u & X86_PDE_PS)
+            return (u64.u & ~(uint64_t)(_2M -1)) | ((uintptr_t)pvPage & (_2M -1));
+
+        /* PT */
+        rtR0MemObjDarwinReadPhys((u64.u & ~(uint64_t)PAGE_OFFSET_MASK) | (((uintptr_t)pvPage >> X86_PT_PAE_SHIFT) & X86_PT_PAE_MASK) * 8, 8, &u64);
+        if (!(u64.u & X86_PTE_P))
+            return 0;
+        return u64.u;
+    }
+
+    /* PD */
+    rtR0MemObjDarwinReadPhys((u64.au32[0] & ~(uint32_t)PAGE_OFFSET_MASK) | (((uintptr_t)pvPage >> X86_PD_SHIFT) & X86_PD_MASK) * 4, 4, &u64);
+    if (!(u64.au32[0] & X86_PDE_P))
+        return 0;
+    if (u64.au32[0] & X86_PDE_PS)
+        return (u64.u & ~(uint64_t)(_2M -1)) | ((uintptr_t)pvPage & (_2M -1));
+
+    /* PT */
+    rtR0MemObjDarwinReadPhys((u64.au32[0] & ~(uint32_t)PAGE_OFFSET_MASK) | (((uintptr_t)pvPage >> X86_PT_SHIFT) & X86_PT_MASK) * 4, 4, &u64);
+    if (!(u64.au32[0] & X86_PTE_P))
+        return 0;
+    return u64.au32[0];
+
+    return 0;
+}
+
+# endif /* unused */
+#endif /* RT_STRICT */
+
+DECLHIDDEN(int) rtR0MemObjNativeFree(RTR0MEMOBJ pMem)
+{
+    PRTR0MEMOBJDARWIN pMemDarwin = (PRTR0MEMOBJDARWIN)pMem;
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    /*
+     * Release the IOMemoryDescriptor or/and IOMemoryMap associated with the object.
+     */
+    if (pMemDarwin->pMemDesc)
+    {
+        pMemDarwin->pMemDesc->complete();
+        pMemDarwin->pMemDesc->release();
+        pMemDarwin->pMemDesc = NULL;
+    }
+
+    if (pMemDarwin->pMemMap)
+    {
+        pMemDarwin->pMemMap->release();
+        pMemDarwin->pMemMap = NULL;
+    }
+
+    /*
+     * Release any memory that we've allocated or locked.
+     */
+    switch (pMemDarwin->Core.enmType)
+    {
+        case RTR0MEMOBJTYPE_LOW:
+        case RTR0MEMOBJTYPE_PAGE:
+        case RTR0MEMOBJTYPE_CONT:
+            break;
+
+        case RTR0MEMOBJTYPE_LOCK:
+        {
+#ifdef USE_VM_MAP_WIRE
+            vm_map_t Map = pMemDarwin->Core.u.Lock.R0Process != NIL_RTR0PROCESS
+                         ? get_task_map((task_t)pMemDarwin->Core.u.Lock.R0Process)
+                         : kernel_map;
+            kern_return_t kr = vm_map_unwire(Map,
+                                             (vm_map_offset_t)pMemDarwin->Core.pv,
+                                             (vm_map_offset_t)pMemDarwin->Core.pv + pMemDarwin->Core.cb,
+                                             0 /* not user */);
+            AssertRC(kr == KERN_SUCCESS); /** @todo don't ignore... */
+#endif
+            break;
+        }
+
+        case RTR0MEMOBJTYPE_PHYS:
+            /*if (pMemDarwin->Core.u.Phys.fAllocated)
+                IOFreePhysical(pMemDarwin->Core.u.Phys.PhysBase, pMemDarwin->Core.cb);*/
+            Assert(!pMemDarwin->Core.u.Phys.fAllocated);
+            break;
+
+        case RTR0MEMOBJTYPE_PHYS_NC:
+            AssertMsgFailed(("RTR0MEMOBJTYPE_PHYS_NC\n"));
+            IPRT_DARWIN_RESTORE_EFL_AC();
+            return VERR_INTERNAL_ERROR;
+
+        case RTR0MEMOBJTYPE_RES_VIRT:
+            AssertMsgFailed(("RTR0MEMOBJTYPE_RES_VIRT\n"));
+            IPRT_DARWIN_RESTORE_EFL_AC();
+            return VERR_INTERNAL_ERROR;
+
+        case RTR0MEMOBJTYPE_MAPPING:
+            /* nothing to do here. */
+            break;
+
+        default:
+            AssertMsgFailed(("enmType=%d\n", pMemDarwin->Core.enmType));
+            IPRT_DARWIN_RESTORE_EFL_AC();
+            return VERR_INTERNAL_ERROR;
+    }
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * This is a helper function to executes @a pfnWorker in the context of the
+ * kernel_task
+ *
+ * @returns IPRT status code - result from pfnWorker or dispatching error.
+ * @param   pfnWorker       The function to call.
+ * @param   pArgs           The arguments to pass to the function.
+ */
+static int rtR0MemObjDarwinDoInKernelTaskThread(thread_call_func_t pfnWorker, RTR0MEMOBJDARWINTHREADARGS *pArgs)
+{
+    pArgs->rc     = VERR_IPE_UNINITIALIZED_STATUS;
+    pArgs->hEvent = NIL_RTSEMEVENTMULTI;
+    int rc = RTSemEventMultiCreate(&pArgs->hEvent);
+    if (RT_SUCCESS(rc))
+    {
+        thread_call_t hCall = thread_call_allocate(pfnWorker, (void *)pArgs);
+        if (hCall)
+        {
+            boolean_t fRc = thread_call_enter(hCall);
+            AssertLogRel(fRc == FALSE);
+
+            rc = RTSemEventMultiWaitEx(pArgs->hEvent, RTSEMWAIT_FLAGS_INDEFINITE | RTSEMWAIT_FLAGS_UNINTERRUPTIBLE,
+                                       RT_INDEFINITE_WAIT);
+            AssertLogRelRC(rc);
+
+            rc = pArgs->rc;
+            thread_call_free(hCall);
+        }
+        else
+            rc = VERR_NO_MEMORY;
+        RTSemEventMultiDestroy(pArgs->hEvent);
+    }
+    return rc;
+}
+
+
+/**
+ * Signals result to thread waiting in rtR0MemObjDarwinDoInKernelTaskThread.
+ *
+ * @param   pArgs           The argument structure.
+ * @param   rc              The IPRT status code to signal.
+ */
+static void rtR0MemObjDarwinSignalThreadWaitinOnTask(RTR0MEMOBJDARWINTHREADARGS volatile *pArgs, int rc)
+{
+    if (ASMAtomicCmpXchgS32(&pArgs->rc, rc, VERR_IPE_UNINITIALIZED_STATUS))
+    {
+        rc = RTSemEventMultiSignal(pArgs->hEvent);
+        AssertLogRelRC(rc);
+    }
+}
+
+
+/**
+ * Kernel memory alloc worker that uses inTaskWithPhysicalMask.
+ *
+ * @returns IPRT status code.
+ * @retval  VERR_ADDRESS_TOO_BIG try another way.
+ *
+ * @param   ppMem           Where to return the memory object.
+ * @param   cb              The page aligned memory size.
+ * @param   fExecutable     Whether the mapping needs to be executable.
+ * @param   fContiguous     Whether the backing memory needs to be contiguous.
+ * @param   PhysMask        The mask for the backing memory (i.e. range). Use 0 if
+ *                          you don't care that much or is speculating.
+ * @param   MaxPhysAddr     The max address to verify the result against. Use
+ *                          UINT64_MAX if it doesn't matter.
+ * @param   enmType         The object type.
+ * @param   uAlignment      The allocation alignment (in bytes).
+ * @param   fOnKernelThread Set if we're already on the kernel thread.
+ */
+static int rtR0MemObjNativeAllocWorker(PPRTR0MEMOBJINTERNAL ppMem, size_t cb,
+                                       bool fExecutable, bool fContiguous,
+                                       mach_vm_address_t PhysMask, uint64_t MaxPhysAddr,
+                                       RTR0MEMOBJTYPE enmType, size_t uAlignment, bool fOnKernelThread)
+{
+    int rc;
+
+    /*
+     * Because of process code signing properties leaking into kernel space in
+     * in XNU's vm_fault.c code, we have to defer allocations of exec memory to
+     * a thread running in the kernel_task to get consistent results here.
+     *
+     * Trouble strikes in vm_fault_enter() when cs_enforcement_enabled is determined
+     * to be true because current process has the CS_ENFORCEMENT flag, the page flag
+     * vmp_cs_validated is clear, and the protection mask includes VM_PROT_EXECUTE
+     * (pmap_cs_enforced does not apply to macOS it seems).  This test seems to go
+     * back to 10.5, though I'm not sure whether it's enabled for macOS that early
+     * on.  Only VM_PROT_EXECUTE is problematic for kernel memory, (though
+     * VM_PROT_WRITE on code signed pages is also problematic in theory).  As long as
+     * kernel_task doesn't have CS_ENFORCEMENT enabled, we'll be fine switching to it.
+     */
+    if (!fExecutable || fOnKernelThread)
+    { /* likely */ }
+    else
+    {
+        RTR0MEMOBJDARWINALLOCARGS Args;
+        Args.ppMem          = ppMem;
+        Args.cb             = cb;
+        Args.fExecutable    = fExecutable;
+        Args.fContiguous    = fContiguous;
+        Args.PhysMask       = PhysMask;
+        Args.MaxPhysAddr    = MaxPhysAddr;
+        Args.enmType        = enmType;
+        Args.uAlignment     = uAlignment;
+        return rtR0MemObjDarwinDoInKernelTaskThread(rtR0MemObjNativeAllockWorkerOnKernelThread, &Args.Core);
+    }
+
+    /*
+     * Try inTaskWithPhysicalMask first, but since we don't quite trust that it
+     * actually respects the physical memory mask (10.5.x is certainly busted),
+     * we'll use rtR0MemObjNativeAllocCont as a fallback for dealing with that.
+     *
+     * The kIOMemoryKernelUserShared flag just forces the result to be page aligned.
+     *
+     * The kIOMemoryMapperNone flag is required since 10.8.2 (IOMMU changes?).
+     */
+
+    /* This is an old fudge from the snow leoard days: "Is it only on snow leopard?
+       Seen allocating memory for the VM structure, last page corrupted or
+       inaccessible."  Made it only apply to snow leopard and older for now. */
+    size_t cbFudged = cb;
+    if (version_major >= 11 /* 10 = 10.7.x = Lion. */)
+    { /* likely */ }
+    else
+         cbFudged += PAGE_SIZE;
+
+    IOOptionBits fOptions = kIOMemoryKernelUserShared | kIODirectionInOut;
+    if (fContiguous)
+    {
+        fOptions |= kIOMemoryPhysicallyContiguous;
+        if (   version_major > 12
+            || (version_major == 12 && version_minor >= 2) /* 10.8.2 = Mountain Kitten */ )
+            fOptions |= kIOMemoryHostPhysicallyContiguous; /* (Just to make ourselves clear, in case the xnu code changes.)  */
+    }
+    if (version_major >= 12 /* 12 = 10.8.x = Mountain Kitten */)
+        fOptions |= kIOMemoryMapperNone;
+
+#if __MAC_OS_X_VERSION_MAX_ALLOWED >= 1070 && 0 /* enable when/if necessary */
+    /* Paranoia: Don't misrepresent our intentions, we won't map kernel executable memory into ring-0. */
+    if (fExecutable && version_major >= 11 /* 10.7.x = Lion, as below */)
+    {
+        fOptions &= ~kIOMemoryKernelUserShared;
+        if (uAlignment < PAGE_SIZE)
+            uAlignment = PAGE_SIZE;
+    }
+#endif
+
+    /* The public initWithPhysicalMask virtual method appeared in 10.7.0, in
+       versions 10.5.0 up to 10.7.0 it was private, and 10.4.8-10.5.0 it was
+       x86 only and didn't have the alignment parameter (slot was different too). */
+    uint64_t uAlignmentActual = uAlignment;
+    IOBufferMemoryDescriptor *pMemDesc;
+#if __MAC_OS_X_VERSION_MAX_ALLOWED >= 1070
+    if (version_major >= 11 /* 11 = 10.7.x = Lion, could probably allow 10.5.0+ here if we really wanted to. */)
+    {
+        /* Starting with 10.6.x the physical mask is ignored if alignment is higher
+           than 1.  The assumption seems to be that inTaskWithPhysicalMask() should
+           be used and the alignment inferred from the PhysMask argument. */
+        if (MaxPhysAddr != UINT64_MAX)
+        {
+            Assert(RT_ALIGN_64(PhysMask, uAlignment) == PhysMask);
+            uAlignmentActual = 1;
+        }
+
+        pMemDesc = new IOBufferMemoryDescriptor;
+        if (pMemDesc)
+        {
+            if (pMemDesc->initWithPhysicalMask(kernel_task, fOptions, cbFudged, uAlignmentActual, PhysMask))
+            { /* likely */ }
+            else
+            {
+                pMemDesc->release();
+                pMemDesc = NULL;
+            }
+        }
+    }
+    else
+#endif
+        pMemDesc = IOBufferMemoryDescriptor::inTaskWithPhysicalMask(kernel_task, fOptions, cbFudged, PhysMask);
+    if (pMemDesc)
+    {
+        IOReturn IORet = pMemDesc->prepare(kIODirectionInOut);
+        if (IORet == kIOReturnSuccess)
+        {
+            void *pv = pMemDesc->getBytesNoCopy(0, cbFudged);
+            if (pv)
+            {
+                /*
+                 * Check if it's all below 4GB.
+                 */
+                addr64_t AddrPrev = 0;
+                MaxPhysAddr &= ~(uint64_t)PAGE_OFFSET_MASK;
+                for (IOByteCount off = 0; off < cb; off += PAGE_SIZE)
+                {
+#ifdef __LP64__
+                    addr64_t Addr = pMemDesc->getPhysicalSegment(off, NULL, kIOMemoryMapperNone);
+#else
+                    addr64_t Addr = pMemDesc->getPhysicalSegment64(off, NULL);
+#endif
+                    if (    Addr > MaxPhysAddr
+                        ||  !Addr
+                        || (Addr & PAGE_OFFSET_MASK)
+                        ||  (   fContiguous
+                             && !off
+                             && Addr == AddrPrev + PAGE_SIZE))
+                    {
+                        /* Buggy API, try allocate the memory another way. */
+                        pMemDesc->complete();
+                        pMemDesc->release();
+                        if (PhysMask)
+                        {
+                            kprintf("rtR0MemObjNativeAllocWorker: off=%zx Addr=%llx AddrPrev=%llx MaxPhysAddr=%llx PhysMas=%llx fContiguous=%d fOptions=%#x - buggy API!\n",
+                                    (size_t)off, Addr, AddrPrev, MaxPhysAddr, PhysMask, fContiguous, fOptions);
+                            LogRel(("rtR0MemObjNativeAllocWorker: off=%zx Addr=%llx AddrPrev=%llx MaxPhysAddr=%llx PhysMas=%llx fContiguous=%RTbool fOptions=%#x - buggy API!\n",
+                                    (size_t)off, Addr, AddrPrev, MaxPhysAddr, PhysMask, fContiguous, fOptions));
+                        }
+                        return VERR_ADDRESS_TOO_BIG;
+                    }
+                    AddrPrev = Addr;
+                }
+
+                /*
+                 * Check that it's aligned correctly.
+                 */
+                if ((uintptr_t)pv & (uAlignment - 1))
+                {
+                    pMemDesc->complete();
+                    pMemDesc->release();
+                    if (PhysMask)
+                    {
+                        kprintf("rtR0MemObjNativeAllocWorker: pv=%p uAlignment=%#zx (MaxPhysAddr=%llx PhysMas=%llx fContiguous=%d fOptions=%#x) - buggy API!!\n",
+                                pv, uAlignment, MaxPhysAddr, PhysMask, fContiguous, fOptions);
+                        LogRel(("rtR0MemObjNativeAllocWorker: pv=%p uAlignment=%#zx (MaxPhysAddr=%llx PhysMas=%llx fContiguous=%RTbool fOptions=%#x) - buggy API!\n",
+                                pv, uAlignment, MaxPhysAddr, PhysMask, fContiguous, fOptions));
+                    }
+                    return VERR_NOT_SUPPORTED;
+                }
+
+#ifdef RT_STRICT
+                /* check that the memory is actually mapped. */
+                //addr64_t Addr = pMemDesc->getPhysicalSegment64(0, NULL);
+                //printf("rtR0MemObjNativeAllocWorker: pv=%p %8llx %8llx\n", pv, rtR0MemObjDarwinGetPTE(pv), Addr);
+                RTTHREADPREEMPTSTATE State = RTTHREADPREEMPTSTATE_INITIALIZER;
+                RTThreadPreemptDisable(&State);
+                rtR0MemObjDarwinTouchPages(pv, cb);
+                RTThreadPreemptRestore(&State);
+#endif
+
+                /*
+                 * Create the IPRT memory object.
+                 */
+                PRTR0MEMOBJDARWIN pMemDarwin = (PRTR0MEMOBJDARWIN)rtR0MemObjNew(sizeof(*pMemDarwin), enmType, pv, cb);
+                if (pMemDarwin)
+                {
+                    if (fContiguous)
+                    {
+#ifdef __LP64__
+                        addr64_t PhysBase64 = pMemDesc->getPhysicalSegment(0, NULL, kIOMemoryMapperNone);
+#else
+                        addr64_t PhysBase64 = pMemDesc->getPhysicalSegment64(0, NULL);
+#endif
+                        RTHCPHYS PhysBase = PhysBase64; Assert(PhysBase == PhysBase64);
+                        if (enmType == RTR0MEMOBJTYPE_CONT)
+                            pMemDarwin->Core.u.Cont.Phys = PhysBase;
+                        else if (enmType == RTR0MEMOBJTYPE_PHYS)
+                            pMemDarwin->Core.u.Phys.PhysBase = PhysBase;
+                        else
+                            AssertMsgFailed(("enmType=%d\n", enmType));
+                    }
+
+                    if (fExecutable)
+                    {
+                        rc = rtR0MemObjNativeProtectWorker(&pMemDarwin->Core, 0, cb,
+                                                           RTMEM_PROT_READ | RTMEM_PROT_WRITE | RTMEM_PROT_EXEC);
+#ifdef RT_STRICT
+                        if (RT_SUCCESS(rc))
+                        {
+                            /* check that the memory is actually mapped. */
+                            RTTHREADPREEMPTSTATE State2 = RTTHREADPREEMPTSTATE_INITIALIZER;
+                            RTThreadPreemptDisable(&State2);
+                            rtR0MemObjDarwinTouchPages(pv, cb);
+                            RTThreadPreemptRestore(&State2);
+                        }
+#endif
+                        /* Bug 6226: Ignore KERN_PROTECTION_FAILURE on Leopard and older. */
+                        if (   rc == VERR_PERMISSION_DENIED
+                            && version_major <= 10 /* 10 = 10.6.x = Snow Leopard. */)
+                            rc = VINF_SUCCESS;
+                    }
+                    else
+                        rc = VINF_SUCCESS;
+                    if (RT_SUCCESS(rc))
+                    {
+                        pMemDarwin->pMemDesc = pMemDesc;
+                        *ppMem = &pMemDarwin->Core;
+                        return VINF_SUCCESS;
+                    }
+
+                    rtR0MemObjDelete(&pMemDarwin->Core);
+                }
+
+                if (enmType == RTR0MEMOBJTYPE_PHYS_NC)
+                    rc = VERR_NO_PHYS_MEMORY;
+                else if (enmType == RTR0MEMOBJTYPE_LOW)
+                    rc = VERR_NO_LOW_MEMORY;
+                else if (enmType == RTR0MEMOBJTYPE_CONT)
+                    rc = VERR_NO_CONT_MEMORY;
+                else
+                    rc = VERR_NO_MEMORY;
+            }
+            else
+                rc = VERR_MEMOBJ_INIT_FAILED;
+
+            pMemDesc->complete();
+        }
+        else
+            rc = RTErrConvertFromDarwinIO(IORet);
+        pMemDesc->release();
+    }
+    else
+        rc = VERR_MEMOBJ_INIT_FAILED;
+    Assert(rc != VERR_ADDRESS_TOO_BIG);
+    return rc;
+}
+
+
+/**
+ * rtR0MemObjNativeAllocWorker kernel_task wrapper function.
+ */
+static void rtR0MemObjNativeAllockWorkerOnKernelThread(void *pvUser0, void *pvUser1)
+{
+    AssertPtr(pvUser0); Assert(pvUser1 == NULL); NOREF(pvUser1);
+    RTR0MEMOBJDARWINALLOCARGS volatile *pArgs = (RTR0MEMOBJDARWINALLOCARGS volatile *)pvUser0;
+    int rc = rtR0MemObjNativeAllocWorker(pArgs->ppMem, pArgs->cb, pArgs->fExecutable, pArgs->fContiguous, pArgs->PhysMask,
+                                         pArgs->MaxPhysAddr, pArgs->enmType, pArgs->uAlignment, true /*fOnKernelThread*/);
+    rtR0MemObjDarwinSignalThreadWaitinOnTask(&pArgs->Core, rc);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocPage(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    int rc = rtR0MemObjNativeAllocWorker(ppMem, cb, fExecutable, false /* fContiguous */, 0 /* PhysMask */, UINT64_MAX,
+                                         RTR0MEMOBJTYPE_PAGE, PAGE_SIZE, false /*fOnKernelThread*/);
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return rc;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocLow(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    /*
+     * Try IOMallocPhysical/IOMallocAligned first.
+     * Then try optimistically without a physical address mask, which will always
+     * end up using IOMallocAligned.
+     *
+     * (See bug comment in the worker and IOBufferMemoryDescriptor::initWithPhysicalMask.)
+     */
+    int rc = rtR0MemObjNativeAllocWorker(ppMem, cb, fExecutable, false /* fContiguous */, ~(uint32_t)PAGE_OFFSET_MASK,
+                                         _4G - PAGE_SIZE, RTR0MEMOBJTYPE_LOW, PAGE_SIZE, false /*fOnKernelThread*/);
+    if (rc == VERR_ADDRESS_TOO_BIG)
+        rc = rtR0MemObjNativeAllocWorker(ppMem, cb, fExecutable, false /* fContiguous */, 0 /* PhysMask */,
+                                         _4G - PAGE_SIZE, RTR0MEMOBJTYPE_LOW, PAGE_SIZE, false /*fOnKernelThread*/);
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return rc;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocCont(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    int rc = rtR0MemObjNativeAllocWorker(ppMem, cb, fExecutable, true /* fContiguous */,
+                                         ~(uint32_t)PAGE_OFFSET_MASK, _4G - PAGE_SIZE,
+                                         RTR0MEMOBJTYPE_CONT, PAGE_SIZE, false /*fOnKernelThread*/);
+
+    /*
+     * Workaround for bogus IOKernelAllocateContiguous behavior, just in case.
+     * cb <= PAGE_SIZE allocations take a different path, using a different allocator.
+     */
+    if (RT_FAILURE(rc) && cb <= PAGE_SIZE)
+        rc = rtR0MemObjNativeAllocWorker(ppMem, cb + PAGE_SIZE, fExecutable, true /* fContiguous */,
+                                         ~(uint32_t)PAGE_OFFSET_MASK, _4G - PAGE_SIZE,
+                                         RTR0MEMOBJTYPE_CONT, PAGE_SIZE, false /*fOnKernelThread*/);
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return rc;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocPhys(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, RTHCPHYS PhysHighest, size_t uAlignment)
+{
+    if (uAlignment != PAGE_SIZE)
+    {
+        /* See rtR0MemObjNativeAllocWorker: */
+        if (version_major < 9 /* 9 = 10.5.x = Snow Leopard */)
+            return VERR_NOT_SUPPORTED;
+    }
+
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    /*
+     * Translate the PhysHighest address into a mask.
+     */
+    int rc;
+    if (PhysHighest == NIL_RTHCPHYS)
+        rc = rtR0MemObjNativeAllocWorker(ppMem, cb, false /* fExecutable */, true /* fContiguous */,
+                                         uAlignment <= PAGE_SIZE ? 0 : ~(mach_vm_address_t)(uAlignment - 1) /* PhysMask*/,
+                                         UINT64_MAX, RTR0MEMOBJTYPE_PHYS, uAlignment, false /*fOnKernelThread*/);
+    else
+    {
+        mach_vm_address_t PhysMask = 0;
+        PhysMask = ~(mach_vm_address_t)0;
+        while (PhysMask > (PhysHighest | PAGE_OFFSET_MASK))
+            PhysMask >>= 1;
+        AssertReturn(PhysMask + 1 <= cb, VERR_INVALID_PARAMETER);
+        PhysMask &= ~(mach_vm_address_t)(uAlignment - 1);
+
+        rc = rtR0MemObjNativeAllocWorker(ppMem, cb, false /* fExecutable */, true /* fContiguous */,
+                                         PhysMask, PhysHighest, RTR0MEMOBJTYPE_PHYS, uAlignment, false /*fOnKernelThread*/);
+    }
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return rc;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocPhysNC(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, RTHCPHYS PhysHighest)
+{
+    /** @todo rtR0MemObjNativeAllocPhys / darwin.
+     * This might be a bit problematic and may very well require having to create our own
+     * object which we populate with pages but without mapping it into any address space.
+     * Estimate is 2-3 days.
+     */
+    RT_NOREF(ppMem, cb, PhysHighest);
+    return VERR_NOT_SUPPORTED;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeEnterPhys(PPRTR0MEMOBJINTERNAL ppMem, RTHCPHYS Phys, size_t cb, uint32_t uCachePolicy)
+{
+    AssertReturn(uCachePolicy == RTMEM_CACHE_POLICY_DONT_CARE, VERR_NOT_SUPPORTED);
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    /*
+     * Create a descriptor for it (the validation is always true on intel macs, but
+     * as it doesn't harm us keep it in).
+     */
+    int rc = VERR_ADDRESS_TOO_BIG;
+    IOAddressRange aRanges[1] = { { Phys, cb } };
+    if (    aRanges[0].address == Phys
+        &&  aRanges[0].length == cb)
+    {
+        IOMemoryDescriptor *pMemDesc = IOMemoryDescriptor::withAddressRanges(&aRanges[0], RT_ELEMENTS(aRanges),
+                                                                             kIODirectionInOut, NULL /*task*/);
+        if (pMemDesc)
+        {
+#ifdef __LP64__
+            Assert(Phys == pMemDesc->getPhysicalSegment(0, NULL, kIOMemoryMapperNone));
+#else
+            Assert(Phys == pMemDesc->getPhysicalSegment64(0, NULL));
+#endif
+
+            /*
+             * Create the IPRT memory object.
+             */
+            PRTR0MEMOBJDARWIN pMemDarwin = (PRTR0MEMOBJDARWIN)rtR0MemObjNew(sizeof(*pMemDarwin), RTR0MEMOBJTYPE_PHYS, NULL, cb);
+            if (pMemDarwin)
+            {
+                pMemDarwin->Core.u.Phys.PhysBase = Phys;
+                pMemDarwin->Core.u.Phys.fAllocated = false;
+                pMemDarwin->Core.u.Phys.uCachePolicy = uCachePolicy;
+                pMemDarwin->pMemDesc = pMemDesc;
+                *ppMem = &pMemDarwin->Core;
+                IPRT_DARWIN_RESTORE_EFL_AC();
+                return VINF_SUCCESS;
+            }
+
+            rc = VERR_NO_MEMORY;
+            pMemDesc->release();
+        }
+        else
+            rc = VERR_MEMOBJ_INIT_FAILED;
+    }
+    else
+        AssertMsgFailed(("%#llx %llx\n", (unsigned long long)Phys, (unsigned long long)cb));
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return rc;
+}
+
+
+/**
+ * Internal worker for locking down pages.
+ *
+ * @return IPRT status code.
+ *
+ * @param   ppMem           Where to store the memory object pointer.
+ * @param   pv              First page.
+ * @param   cb              Number of bytes.
+ * @param   fAccess         The desired access, a combination of RTMEM_PROT_READ
+ *                          and RTMEM_PROT_WRITE.
+ * @param   Task            The task \a pv and \a cb refers to.
+ */
+static int rtR0MemObjNativeLock(PPRTR0MEMOBJINTERNAL ppMem, void *pv, size_t cb, uint32_t fAccess, task_t Task)
+{
+    IPRT_DARWIN_SAVE_EFL_AC();
+    NOREF(fAccess);
+#ifdef USE_VM_MAP_WIRE
+    vm_map_t Map = get_task_map(Task);
+    Assert(Map);
+
+    /*
+     * First try lock the memory.
+     */
+    int rc = VERR_LOCK_FAILED;
+    kern_return_t kr = vm_map_wire(get_task_map(Task),
+                                   (vm_map_offset_t)pv,
+                                   (vm_map_offset_t)pv + cb,
+                                   VM_PROT_DEFAULT,
+                                   0 /* not user */);
+    if (kr == KERN_SUCCESS)
+    {
+        /*
+         * Create the IPRT memory object.
+         */
+        PRTR0MEMOBJDARWIN pMemDarwin = (PRTR0MEMOBJDARWIN)rtR0MemObjNew(sizeof(*pMemDarwin), RTR0MEMOBJTYPE_LOCK, pv, cb);
+        if (pMemDarwin)
+        {
+            pMemDarwin->Core.u.Lock.R0Process = (RTR0PROCESS)Task;
+            *ppMem = &pMemDarwin->Core;
+
+            IPRT_DARWIN_RESTORE_EFL_AC();
+            return VINF_SUCCESS;
+        }
+
+        kr = vm_map_unwire(get_task_map(Task), (vm_map_offset_t)pv, (vm_map_offset_t)pv + cb, 0 /* not user */);
+        Assert(kr == KERN_SUCCESS);
+        rc = VERR_NO_MEMORY;
+    }
+
+#else
+
+    /*
+     * Create a descriptor and try lock it (prepare).
+     */
+    int rc = VERR_MEMOBJ_INIT_FAILED;
+    IOMemoryDescriptor *pMemDesc = IOMemoryDescriptor::withAddressRange((vm_address_t)pv, cb, kIODirectionInOut, Task);
+    if (pMemDesc)
+    {
+        IOReturn IORet = pMemDesc->prepare(kIODirectionInOut);
+        if (IORet == kIOReturnSuccess)
+        {
+            /*
+             * Create the IPRT memory object.
+             */
+            PRTR0MEMOBJDARWIN pMemDarwin = (PRTR0MEMOBJDARWIN)rtR0MemObjNew(sizeof(*pMemDarwin), RTR0MEMOBJTYPE_LOCK, pv, cb);
+            if (pMemDarwin)
+            {
+                pMemDarwin->Core.u.Lock.R0Process = (RTR0PROCESS)Task;
+                pMemDarwin->pMemDesc = pMemDesc;
+                *ppMem = &pMemDarwin->Core;
+
+                IPRT_DARWIN_RESTORE_EFL_AC();
+                return VINF_SUCCESS;
+            }
+
+            pMemDesc->complete();
+            rc = VERR_NO_MEMORY;
+        }
+        else
+            rc = VERR_LOCK_FAILED;
+        pMemDesc->release();
+    }
+#endif
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return rc;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeLockUser(PPRTR0MEMOBJINTERNAL ppMem, RTR3PTR R3Ptr, size_t cb, uint32_t fAccess, RTR0PROCESS R0Process)
+{
+    return rtR0MemObjNativeLock(ppMem, (void *)R3Ptr, cb, fAccess, (task_t)R0Process);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeLockKernel(PPRTR0MEMOBJINTERNAL ppMem, void *pv, size_t cb, uint32_t fAccess)
+{
+    return rtR0MemObjNativeLock(ppMem, pv, cb, fAccess, kernel_task);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeReserveKernel(PPRTR0MEMOBJINTERNAL ppMem, void *pvFixed, size_t cb, size_t uAlignment)
+{
+    RT_NOREF(ppMem, pvFixed, cb, uAlignment);
+    return VERR_NOT_SUPPORTED;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeReserveUser(PPRTR0MEMOBJINTERNAL ppMem, RTR3PTR R3PtrFixed, size_t cb, size_t uAlignment, RTR0PROCESS R0Process)
+{
+    RT_NOREF(ppMem, R3PtrFixed, cb, uAlignment, R0Process);
+    return VERR_NOT_SUPPORTED;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeMapKernel(PPRTR0MEMOBJINTERNAL ppMem, RTR0MEMOBJ pMemToMap, void *pvFixed, size_t uAlignment,
+                                          unsigned fProt, size_t offSub, size_t cbSub)
+{
+    RT_NOREF(fProt);
+    AssertReturn(pvFixed == (void *)-1, VERR_NOT_SUPPORTED);
+
+    /*
+     * Check that the specified alignment is supported.
+     */
+    if (uAlignment > PAGE_SIZE)
+        return VERR_NOT_SUPPORTED;
+    Assert(!offSub || cbSub);
+
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    /*
+     * Must have a memory descriptor that we can map.
+     */
+    int rc = VERR_INVALID_PARAMETER;
+    PRTR0MEMOBJDARWIN pMemToMapDarwin = (PRTR0MEMOBJDARWIN)pMemToMap;
+    if (pMemToMapDarwin->pMemDesc)
+    {
+        /* The kIOMapPrefault option was added in 10.10.0; causes PTEs to be populated with
+           INTEL_PTE_WIRED to be set, just like we desire (see further down).  However, till
+           10.13.0 it was not available for use on kernel mappings. Oh, fudge. */
+#if MAC_OS_X_VERSION_MIN_REQUIRED >= 1050
+        static uint32_t volatile s_fOptions = UINT32_MAX;
+        uint32_t fOptions = s_fOptions;
+        if (RT_UNLIKELY(fOptions == UINT32_MAX))
+            s_fOptions = fOptions = version_major >= 17 ? 0x10000000 /*kIOMapPrefault*/ : 0; /* Since 10.13.0 (High Sierra). */
+
+        IOMemoryMap *pMemMap = pMemToMapDarwin->pMemDesc->createMappingInTask(kernel_task,
+                                                                              0,
+                                                                              kIOMapAnywhere | kIOMapDefaultCache | fOptions,
+                                                                              offSub,
+                                                                              cbSub);
+#else
+        IOMemoryMap *pMemMap = pMemToMapDarwin->pMemDesc->map(kernel_task,
+                                                              0,
+                                                              kIOMapAnywhere | kIOMapDefaultCache,
+                                                              offSub,
+                                                              cbSub);
+#endif
+        if (pMemMap)
+        {
+            IOVirtualAddress VirtAddr = pMemMap->getVirtualAddress();
+            void *pv = (void *)(uintptr_t)VirtAddr;
+            if ((uintptr_t)pv == VirtAddr && pv != NULL)
+            {
+//#ifdef __LP64__
+//                addr64_t Addr = pMemToMapDarwin->pMemDesc->getPhysicalSegment(offSub, NULL, kIOMemoryMapperNone);
+//#else
+//                addr64_t Addr = pMemToMapDarwin->pMemDesc->getPhysicalSegment64(offSub, NULL);
+//#endif
+//                MY_PRINTF("pv=%p: %8llx %8llx\n", pv, rtR0MemObjDarwinGetPTE(pv), Addr);
+
+//                /*
+//                 * Explicitly lock it so that we're sure it is present and that
+//                 * its PTEs cannot be recycled.
+//                 * Note! withAddressRange() doesn't work as it adds kIOMemoryTypeVirtual64
+//                 *       to the options which causes prepare() to not wire the pages.
+//                 *       This is probably a bug.
+//                 */
+//                IOAddressRange Range = { (mach_vm_address_t)pv, cbSub };
+//                IOMemoryDescriptor *pMemDesc = IOMemoryDescriptor::withOptions(&Range,
+//                                                                               1 /* count */,
+//                                                                               0 /* offset */,
+//                                                                               kernel_task,
+//                                                                               kIODirectionInOut | kIOMemoryTypeVirtual,
+//                                                                               kIOMapperSystem);
+//                if (pMemDesc)
+//                {
+//                    IOReturn IORet = pMemDesc->prepare(kIODirectionInOut);
+//                    if (IORet == kIOReturnSuccess)
+//                    {
+                        /* HACK ALERT! On kernels older than 10.10 (xnu version 14), we need to fault in
+                                       the pages here so they can safely be accessed from inside simple
+                                       locks and when preemption is disabled (no page-ins allowed).
+                           Note! This touching does not cause INTEL_PTE_WIRED (bit 10) to be set as we go
+                                 thru general #PF and vm_fault doesn't figure it should be wired or something.  */
+                        rtR0MemObjDarwinTouchPages(pv, cbSub ? cbSub : pMemToMap->cb);
+                        /** @todo First, the memory should've been mapped by now, and second, it
+                         *        should have the wired attribute in the PTE (bit 10). Neither seems to
+                         *        be the case. The disabled locking code doesn't make any difference,
+                         *        which is extremely odd, and breaks rtR0MemObjNativeGetPagePhysAddr
+                         *        (getPhysicalSegment64 -> 64 for the lock descriptor. */
+//#ifdef __LP64__
+//                        addr64_t Addr2 = pMemToMapDarwin->pMemDesc->getPhysicalSegment(offSub, NULL, kIOMemoryMapperNone);
+//#else
+//                        addr64_t Addr2 = pMemToMapDarwin->pMemDesc->getPhysicalSegment64(offSub, NULL);
+//#endif
+//                        MY_PRINTF("pv=%p: %8llx %8llx (%d)\n", pv, rtR0MemObjDarwinGetPTE(pv), Addr2, 2);
+
+                        /*
+                         * Create the IPRT memory object.
+                         */
+                        PRTR0MEMOBJDARWIN pMemDarwin = (PRTR0MEMOBJDARWIN)rtR0MemObjNew(sizeof(*pMemDarwin), RTR0MEMOBJTYPE_MAPPING,
+                                                                                        pv, cbSub ? cbSub : pMemToMap->cb);
+                        if (pMemDarwin)
+                        {
+                            pMemDarwin->Core.u.Mapping.R0Process = NIL_RTR0PROCESS;
+                            pMemDarwin->pMemMap = pMemMap;
+//                            pMemDarwin->pMemDesc = pMemDesc;
+                            *ppMem = &pMemDarwin->Core;
+
+                            IPRT_DARWIN_RESTORE_EFL_AC();
+                            return VINF_SUCCESS;
+                        }
+
+//                        pMemDesc->complete();
+//                        rc = VERR_NO_MEMORY;
+//                    }
+//                    else
+//                        rc = RTErrConvertFromDarwinIO(IORet);
+//                    pMemDesc->release();
+//                }
+//                else
+//                    rc = VERR_MEMOBJ_INIT_FAILED;
+            }
+            else if (pv)
+                rc = VERR_ADDRESS_TOO_BIG;
+            else
+                rc = VERR_MAP_FAILED;
+            pMemMap->release();
+        }
+        else
+            rc = VERR_MAP_FAILED;
+    }
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return rc;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeMapUser(PPRTR0MEMOBJINTERNAL ppMem, RTR0MEMOBJ pMemToMap, RTR3PTR R3PtrFixed, size_t uAlignment,
+                                        unsigned fProt, RTR0PROCESS R0Process, size_t offSub, size_t cbSub)
+{
+    RT_NOREF(fProt);
+
+    /*
+     * Check for unsupported things.
+     */
+    AssertReturn(R3PtrFixed == (RTR3PTR)-1, VERR_NOT_SUPPORTED);
+    if (uAlignment > PAGE_SIZE)
+        return VERR_NOT_SUPPORTED;
+    Assert(!offSub || cbSub);
+
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    /*
+     * Must have a memory descriptor.
+     */
+    int rc = VERR_INVALID_PARAMETER;
+    PRTR0MEMOBJDARWIN pMemToMapDarwin = (PRTR0MEMOBJDARWIN)pMemToMap;
+    if (pMemToMapDarwin->pMemDesc)
+    {
+#if MAC_OS_X_VERSION_MIN_REQUIRED >= 101000 /* The kIOMapPrefault option was added in 10.10.0. */
+         IOMemoryMap *pMemMap = pMemToMapDarwin->pMemDesc->createMappingInTask((task_t)R0Process,
+                                                                              0,
+                                                                              kIOMapAnywhere | kIOMapDefaultCache | kIOMapPrefault,
+                                                                              offSub,
+                                                                              cbSub);
+#elif MAC_OS_X_VERSION_MIN_REQUIRED >= 1050
+        static uint32_t volatile s_fOptions = UINT32_MAX;
+        uint32_t fOptions = s_fOptions;
+        if (RT_UNLIKELY(fOptions == UINT32_MAX))
+            s_fOptions = fOptions = version_major >= 14 ? 0x10000000 /*kIOMapPrefault*/ : 0; /* Since 10.10.0. */
+        IOMemoryMap *pMemMap = pMemToMapDarwin->pMemDesc->createMappingInTask((task_t)R0Process,
+                                                                              0,
+                                                                              kIOMapAnywhere | kIOMapDefaultCache | fOptions,
+                                                                              offSub,
+                                                                              cbSub);
+#else
+        IOMemoryMap *pMemMap = pMemToMapDarwin->pMemDesc->map((task_t)R0Process,
+                                                              0,
+                                                              kIOMapAnywhere | kIOMapDefaultCache,
+                                                              offSub,
+                                                              cbSub);
+#endif
+        if (pMemMap)
+        {
+            IOVirtualAddress VirtAddr = pMemMap->getVirtualAddress();
+            void *pv = (void *)(uintptr_t)VirtAddr;
+            if ((uintptr_t)pv == VirtAddr && pv != NULL)
+            {
+                /*
+                 * Create the IPRT memory object.
+                 */
+                PRTR0MEMOBJDARWIN pMemDarwin = (PRTR0MEMOBJDARWIN)rtR0MemObjNew(sizeof(*pMemDarwin), RTR0MEMOBJTYPE_MAPPING,
+                                                                                pv, cbSub ? cbSub : pMemToMap->cb);
+                if (pMemDarwin)
+                {
+                    pMemDarwin->Core.u.Mapping.R0Process = R0Process;
+                    pMemDarwin->pMemMap = pMemMap;
+                    *ppMem = &pMemDarwin->Core;
+
+                    IPRT_DARWIN_RESTORE_EFL_AC();
+                    return VINF_SUCCESS;
+                }
+
+                rc = VERR_NO_MEMORY;
+            }
+            else if (pv)
+                rc = VERR_ADDRESS_TOO_BIG;
+            else
+                rc = VERR_MAP_FAILED;
+            pMemMap->release();
+        }
+        else
+            rc = VERR_MAP_FAILED;
+    }
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return rc;
+}
+
+
+/**
+ * Worker for rtR0MemObjNativeProtect that's typically called in a different
+ * context.
+ */
+static int rtR0MemObjNativeProtectWorker(PRTR0MEMOBJINTERNAL pMem, size_t offSub, size_t cbSub, uint32_t fProt)
+{
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    /* Get the map for the object. */
+    vm_map_t pVmMap = rtR0MemObjDarwinGetMap(pMem);
+    if (!pVmMap)
+    {
+        IPRT_DARWIN_RESTORE_EFL_AC();
+        return VERR_NOT_SUPPORTED;
+    }
+
+    /*
+     * Convert the protection.
+     */
+    vm_prot_t fMachProt;
+    switch (fProt)
+    {
+        case RTMEM_PROT_NONE:
+            fMachProt = VM_PROT_NONE;
+            break;
+        case RTMEM_PROT_READ:
+            fMachProt = VM_PROT_READ;
+            break;
+        case RTMEM_PROT_READ | RTMEM_PROT_WRITE:
+            fMachProt = VM_PROT_READ | VM_PROT_WRITE;
+            break;
+        case RTMEM_PROT_READ | RTMEM_PROT_WRITE | RTMEM_PROT_EXEC:
+            fMachProt = VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE;
+            break;
+        case RTMEM_PROT_WRITE:
+            fMachProt = VM_PROT_WRITE | VM_PROT_READ;                   /* never write-only */
+            break;
+        case RTMEM_PROT_WRITE | RTMEM_PROT_EXEC:
+            fMachProt = VM_PROT_WRITE | VM_PROT_EXECUTE | VM_PROT_READ; /* never write-only or execute-only */
+            break;
+        case RTMEM_PROT_EXEC:
+            fMachProt = VM_PROT_EXECUTE | VM_PROT_READ;                 /* never execute-only */
+            break;
+        default:
+            AssertFailedReturn(VERR_INVALID_PARAMETER);
+    }
+
+    /*
+     * Do the job.
+     */
+    vm_offset_t Start = (uintptr_t)pMem->pv + offSub;
+    kern_return_t krc = vm_protect(pVmMap,
+                                   Start,
+                                   cbSub,
+                                   false,
+                                   fMachProt);
+    if (krc != KERN_SUCCESS)
+    {
+        static int s_cComplaints = 0;
+        if (s_cComplaints < 10)
+        {
+            s_cComplaints++;
+            printf("rtR0MemObjNativeProtect: vm_protect(%p,%p,%p,false,%#x) -> %d\n",
+                   pVmMap, (void *)Start, (void *)cbSub, fMachProt, krc);
+
+            kern_return_t               krc2;
+            vm_offset_t                 pvReal = Start;
+            vm_size_t                   cbReal = 0;
+            mach_msg_type_number_t      cInfo  = VM_REGION_BASIC_INFO_COUNT;
+            struct vm_region_basic_info Info;
+            RT_ZERO(Info);
+            krc2 = vm_region(pVmMap, &pvReal, &cbReal, VM_REGION_BASIC_INFO, (vm_region_info_t)&Info, &cInfo, NULL);
+            printf("rtR0MemObjNativeProtect: basic info - krc2=%d pv=%p cb=%p prot=%#x max=%#x inh=%#x shr=%d rvd=%d off=%#x behavior=%#x wired=%#x\n",
+                   krc2, (void *)pvReal, (void *)cbReal, Info.protection, Info.max_protection,  Info.inheritance,
+                   Info.shared, Info.reserved, Info.offset, Info.behavior, Info.user_wired_count);
+        }
+        IPRT_DARWIN_RESTORE_EFL_AC();
+        return RTErrConvertFromDarwinKern(krc);
+    }
+
+    /*
+     * Touch the pages if they should be writable afterwards and accessible
+     * from code which should never fault. vm_protect() may leave pages
+     * temporarily write protected, possibly due to pmap no-upgrade rules?
+     *
+     * This is the same trick (or HACK ALERT if you like) as applied in
+     * rtR0MemObjNativeMapKernel.
+     */
+    if (   pMem->enmType != RTR0MEMOBJTYPE_MAPPING
+        || pMem->u.Mapping.R0Process == NIL_RTR0PROCESS)
+    {
+        if (fProt & RTMEM_PROT_WRITE)
+            rtR0MemObjDarwinTouchPages((void *)Start, cbSub);
+        /*
+         * Sniff (read) read-only pages too, just to be sure.
+         */
+        else if (fProt & (RTMEM_PROT_READ | RTMEM_PROT_EXEC))
+            rtR0MemObjDarwinSniffPages((void const *)Start, cbSub);
+    }
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * rtR0MemObjNativeProtect kernel_task wrapper function.
+ */
+static void rtR0MemObjNativeProtectWorkerOnKernelThread(void *pvUser0, void *pvUser1)
+{
+    AssertPtr(pvUser0); Assert(pvUser1 == NULL); NOREF(pvUser1);
+    RTR0MEMOBJDARWINPROTECTARGS *pArgs = (RTR0MEMOBJDARWINPROTECTARGS *)pvUser0;
+    int rc = rtR0MemObjNativeProtectWorker(pArgs->pMem, pArgs->offSub, pArgs->cbSub, pArgs->fProt);
+    rtR0MemObjDarwinSignalThreadWaitinOnTask(&pArgs->Core, rc);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeProtect(PRTR0MEMOBJINTERNAL pMem, size_t offSub, size_t cbSub, uint32_t fProt)
+{
+    /*
+     * The code won't work right because process codesigning properties leaks
+     * into kernel_map memory management.  So, if the user process we're running
+     * in has CS restrictions active, we cannot play around with the EXEC
+     * protection because some vm_fault.c think we're modifying the process map
+     * or something.
+     */
+    int rc;
+    if (rtR0MemObjDarwinGetMap(pMem) == kernel_map)
+    {
+        RTR0MEMOBJDARWINPROTECTARGS Args;
+        Args.pMem       = pMem;
+        Args.offSub     = offSub;
+        Args.cbSub      = cbSub;
+        Args.fProt      = fProt;
+        rc = rtR0MemObjDarwinDoInKernelTaskThread(rtR0MemObjNativeProtectWorkerOnKernelThread, &Args.Core);
+    }
+    else
+        rc = rtR0MemObjNativeProtectWorker(pMem, offSub, cbSub, fProt);
+    return rc;
+}
+
+
+DECLHIDDEN(RTHCPHYS) rtR0MemObjNativeGetPagePhysAddr(PRTR0MEMOBJINTERNAL pMem, size_t iPage)
+{
+    RTHCPHYS            PhysAddr;
+    PRTR0MEMOBJDARWIN   pMemDarwin = (PRTR0MEMOBJDARWIN)pMem;
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+#ifdef USE_VM_MAP_WIRE
+    /*
+     * Locked memory doesn't have a memory descriptor and
+     * needs to be handled differently.
+     */
+    if (pMemDarwin->Core.enmType == RTR0MEMOBJTYPE_LOCK)
+    {
+        ppnum_t PgNo;
+        if (pMemDarwin->Core.u.Lock.R0Process == NIL_RTR0PROCESS)
+            PgNo = pmap_find_phys(kernel_pmap, (uintptr_t)pMemDarwin->Core.pv + iPage * PAGE_SIZE);
+        else
+        {
+            /*
+             * From what I can tell, Apple seems to have locked up the all the
+             * available interfaces that could help us obtain the pmap_t of a task
+             * or vm_map_t.
+
+             * So, we'll have to figure out where in the vm_map_t  structure it is
+             * and read it our selves. ASSUMING that kernel_pmap is pointed to by
+             * kernel_map->pmap, we scan kernel_map to locate the structure offset.
+             * Not nice, but it will hopefully do the job in a reliable manner...
+             *
+             * (get_task_pmap, get_map_pmap or vm_map_pmap is what we really need btw.)
+             */
+            static int s_offPmap = -1;
+            if (RT_UNLIKELY(s_offPmap == -1))
+            {
+                pmap_t const *p = (pmap_t *)kernel_map;
+                pmap_t const * const pEnd = p + 64;
+                for (; p < pEnd; p++)
+                    if (*p == kernel_pmap)
+                    {
+                        s_offPmap = (uintptr_t)p - (uintptr_t)kernel_map;
+                        break;
+                    }
+                AssertReturn(s_offPmap >= 0, NIL_RTHCPHYS);
+            }
+            pmap_t Pmap = *(pmap_t *)((uintptr_t)get_task_map((task_t)pMemDarwin->Core.u.Lock.R0Process) + s_offPmap);
+            PgNo = pmap_find_phys(Pmap, (uintptr_t)pMemDarwin->Core.pv + iPage * PAGE_SIZE);
+        }
+
+        IPRT_DARWIN_RESTORE_EFL_AC();
+        AssertReturn(PgNo, NIL_RTHCPHYS);
+        PhysAddr = (RTHCPHYS)PgNo << PAGE_SHIFT;
+        Assert((PhysAddr >> PAGE_SHIFT) == PgNo);
+    }
+    else
+#endif /* USE_VM_MAP_WIRE */
+    {
+        /*
+         * Get the memory descriptor.
+         */
+        IOMemoryDescriptor *pMemDesc = pMemDarwin->pMemDesc;
+        if (!pMemDesc)
+            pMemDesc = pMemDarwin->pMemMap->getMemoryDescriptor();
+        AssertReturn(pMemDesc, NIL_RTHCPHYS);
+
+        /*
+         * If we've got a memory descriptor, use getPhysicalSegment64().
+         */
+#ifdef __LP64__
+        addr64_t Addr = pMemDesc->getPhysicalSegment(iPage * PAGE_SIZE, NULL, kIOMemoryMapperNone);
+#else
+        addr64_t Addr = pMemDesc->getPhysicalSegment64(iPage * PAGE_SIZE, NULL);
+#endif
+        IPRT_DARWIN_RESTORE_EFL_AC();
+        AssertMsgReturn(Addr, ("iPage=%u\n", iPage), NIL_RTHCPHYS);
+        PhysAddr = Addr;
+        AssertMsgReturn(PhysAddr == Addr, ("PhysAddr=%RHp Addr=%RX64\n", PhysAddr, (uint64_t)Addr), NIL_RTHCPHYS);
+    }
+
+    return PhysAddr;
+}
+
diff --git a/src/VBox/Runtime/r0drv/darwin/memuserkernel-r0drv-darwin.cpp b/src/VBox/Runtime/r0drv/darwin/memuserkernel-r0drv-darwin.cpp
new file mode 100644
index 00000000..78617cae
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/memuserkernel-r0drv-darwin.cpp
@@ -0,0 +1,118 @@
+/* $Id: memuserkernel-r0drv-darwin.cpp $ */
+/** @file
+ * IPRT - User & Kernel Memory, Ring-0 Driver, Darwin.
+ */
+
+/*
+ * Copyright (C) 2009-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-darwin-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/mem.h>
+#include <iprt/assert.h>
+
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/errcore.h>
+
+
+RTR0DECL(int) RTR0MemUserCopyFrom(void *pvDst, RTR3PTR R3PtrSrc, size_t cb)
+{
+    RT_ASSERT_INTS_ON();
+    IPRT_DARWIN_SAVE_EFL_AC();
+    int rc = copyin((const user_addr_t)R3PtrSrc, pvDst, cb);
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    if (RT_LIKELY(rc == 0))
+        return VINF_SUCCESS;
+    return VERR_ACCESS_DENIED;
+}
+
+
+RTR0DECL(int) RTR0MemUserCopyTo(RTR3PTR R3PtrDst, void const *pvSrc, size_t cb)
+{
+    RT_ASSERT_INTS_ON();
+    IPRT_DARWIN_SAVE_EFL_AC();
+    int rc = copyout(pvSrc, R3PtrDst, cb);
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    if (RT_LIKELY(rc == 0))
+        return VINF_SUCCESS;
+    return VERR_ACCESS_DENIED;
+}
+
+
+RTR0DECL(bool) RTR0MemUserIsValidAddr(RTR3PTR R3Ptr)
+{
+    /* the commpage is above this. */
+#ifdef RT_ARCH_X86
+    return R3Ptr < VM_MAX_ADDRESS;
+#else
+    return R3Ptr < VM_MAX_PAGE_ADDRESS;
+#endif
+}
+
+
+RTR0DECL(bool) RTR0MemKernelIsValidAddr(void *pv)
+{
+    /* Found no public #define or symbol for checking this, so we'll
+       have to make do with thing found in the debugger and the sources. */
+#ifdef RT_ARCH_X86
+    NOREF(pv);
+    return true;    /* Almost anything is a valid kernel address here. */
+
+#elif defined(RT_ARCH_AMD64)
+    return (uintptr_t)pv >= UINT64_C(0xffff800000000000);
+
+#else
+# error "PORTME"
+#endif
+}
+
+
+RTR0DECL(bool) RTR0MemAreKrnlAndUsrDifferent(void)
+{
+    /* As mentioned in RTR0MemKernelIsValidAddr, found no way of checking
+       this at compiler or runtime. */
+#ifdef RT_ARCH_X86
+    return false;
+#else
+    return true;
+#endif
+}
+
+
+RTR0DECL(int) RTR0MemKernelCopyFrom(void *pvDst, void const *pvSrc, size_t cb)
+{
+    RT_NOREF(pvDst, pvSrc, cb);
+    return VERR_NOT_SUPPORTED;
+}
+
+
+RTR0DECL(int) RTR0MemKernelCopyTo(void *pvDst, void const *pvSrc, size_t cb)
+{
+    RT_NOREF(pvDst, pvSrc, cb);
+    return VERR_NOT_SUPPORTED;
+}
+
diff --git a/src/VBox/Runtime/r0drv/darwin/mp-r0drv-darwin.cpp b/src/VBox/Runtime/r0drv/darwin/mp-r0drv-darwin.cpp
new file mode 100644
index 00000000..a1b0af1d
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/mp-r0drv-darwin.cpp
@@ -0,0 +1,314 @@
+/* $Id: mp-r0drv-darwin.cpp $ */
+/** @file
+ * IPRT - Multiprocessor, Ring-0 Driver, Darwin.
+ */
+
+/*
+ * Copyright (C) 2008-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-darwin-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/mp.h>
+
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/cpuset.h>
+#include <iprt/err.h>
+#include "r0drv/mp-r0drv.h"
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+static int32_t volatile g_cMaxCpus = -1;
+
+
+static int rtMpDarwinInitMaxCpus(void)
+{
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    int32_t cCpus = -1;
+    size_t  oldLen = sizeof(cCpus);
+    int rc = sysctlbyname("hw.ncpu", &cCpus, &oldLen, NULL, NULL);
+    if (rc)
+    {
+        printf("IPRT: sysctlbyname(hw.ncpu) failed with rc=%d!\n", rc);
+        cCpus = 64; /* whatever */
+    }
+
+    ASMAtomicWriteS32(&g_cMaxCpus, cCpus);
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return cCpus;
+}
+
+
+DECLINLINE(int) rtMpDarwinMaxCpus(void)
+{
+    int cCpus = g_cMaxCpus;
+    if (RT_UNLIKELY(cCpus <= 0))
+        return rtMpDarwinInitMaxCpus();
+    return cCpus;
+}
+
+
+RTDECL(RTCPUID) RTMpCpuId(void)
+{
+    return cpu_number();
+}
+
+
+RTDECL(int) RTMpCurSetIndex(void)
+{
+    return cpu_number();
+}
+
+
+RTDECL(int) RTMpCurSetIndexAndId(PRTCPUID pidCpu)
+{
+    return *pidCpu = cpu_number();
+}
+
+
+RTDECL(int) RTMpCpuIdToSetIndex(RTCPUID idCpu)
+{
+    return idCpu < RTCPUSET_MAX_CPUS ? (int)idCpu : -1;
+}
+
+
+RTDECL(RTCPUID) RTMpCpuIdFromSetIndex(int iCpu)
+{
+    return (unsigned)iCpu < RTCPUSET_MAX_CPUS ? (RTCPUID)iCpu : NIL_RTCPUID;
+}
+
+
+RTDECL(RTCPUID) RTMpGetMaxCpuId(void)
+{
+    return rtMpDarwinMaxCpus() - 1;
+}
+
+
+RTDECL(bool) RTMpIsCpuPossible(RTCPUID idCpu)
+{
+    return idCpu < RTCPUSET_MAX_CPUS
+        && idCpu < (RTCPUID)rtMpDarwinMaxCpus();
+}
+
+
+RTDECL(PRTCPUSET) RTMpGetSet(PRTCPUSET pSet)
+{
+    RTCPUID idCpu;
+
+    RTCpuSetEmpty(pSet);
+    idCpu = RTMpGetMaxCpuId();
+    do
+    {
+        if (RTMpIsCpuPossible(idCpu))
+            RTCpuSetAdd(pSet, idCpu);
+    } while (idCpu-- > 0);
+    return pSet;
+}
+
+
+RTDECL(RTCPUID) RTMpGetCount(void)
+{
+    return rtMpDarwinMaxCpus();
+}
+
+
+RTDECL(PRTCPUSET) RTMpGetOnlineSet(PRTCPUSET pSet)
+{
+    /** @todo darwin R0 MP */
+    return RTMpGetSet(pSet);
+}
+
+
+RTDECL(RTCPUID) RTMpGetOnlineCount(void)
+{
+    /** @todo darwin R0 MP */
+    return RTMpGetCount();
+}
+
+
+RTDECL(bool) RTMpIsCpuOnline(RTCPUID idCpu)
+{
+    /** @todo darwin R0 MP */
+    return RTMpIsCpuPossible(idCpu);
+}
+
+
+RTDECL(uint32_t) RTMpGetCurFrequency(RTCPUID idCpu)
+{
+    /** @todo darwin R0 MP (rainy day) */
+    RT_NOREF(idCpu);
+    return 0;
+}
+
+
+RTDECL(uint32_t) RTMpGetMaxFrequency(RTCPUID idCpu)
+{
+    /** @todo darwin R0 MP (rainy day) */
+    RT_NOREF(idCpu);
+    return 0;
+}
+
+
+RTDECL(bool) RTMpIsCpuWorkPending(void)
+{
+    /** @todo (not used on non-Windows platforms yet). */
+    return false;
+}
+
+
+/**
+ * Wrapper between the native darwin per-cpu callback and PFNRTWORKER
+ * for the RTMpOnAll API.
+ *
+ * @param   pvArg   Pointer to the RTMPARGS package.
+ */
+static void rtmpOnAllDarwinWrapper(void *pvArg)
+{
+    PRTMPARGS pArgs = (PRTMPARGS)pvArg;
+    IPRT_DARWIN_SAVE_EFL_AC();
+    pArgs->pfnWorker(cpu_number(), pArgs->pvUser1, pArgs->pvUser2);
+    IPRT_DARWIN_RESTORE_EFL_AC();
+}
+
+
+RTDECL(int) RTMpOnAll(PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    RT_ASSERT_INTS_ON();
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    RTMPARGS Args;
+    Args.pfnWorker = pfnWorker;
+    Args.pvUser1 = pvUser1;
+    Args.pvUser2 = pvUser2;
+    Args.idCpu = NIL_RTCPUID;
+    Args.cHits = 0;
+    mp_rendezvous_no_intrs(rtmpOnAllDarwinWrapper, &Args);
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Wrapper between the native darwin per-cpu callback and PFNRTWORKER
+ * for the RTMpOnOthers API.
+ *
+ * @param   pvArg   Pointer to the RTMPARGS package.
+ */
+static void rtmpOnOthersDarwinWrapper(void *pvArg)
+{
+    PRTMPARGS pArgs = (PRTMPARGS)pvArg;
+    RTCPUID idCpu = cpu_number();
+    if (pArgs->idCpu != idCpu)
+    {
+        IPRT_DARWIN_SAVE_EFL_AC();
+        pArgs->pfnWorker(idCpu, pArgs->pvUser1, pArgs->pvUser2);
+        IPRT_DARWIN_RESTORE_EFL_AC();
+    }
+}
+
+
+RTDECL(int) RTMpOnOthers(PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    RT_ASSERT_INTS_ON();
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    RTMPARGS Args;
+    Args.pfnWorker = pfnWorker;
+    Args.pvUser1 = pvUser1;
+    Args.pvUser2 = pvUser2;
+    Args.idCpu = RTMpCpuId();
+    Args.cHits = 0;
+    mp_rendezvous_no_intrs(rtmpOnOthersDarwinWrapper, &Args);
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Wrapper between the native darwin per-cpu callback and PFNRTWORKER
+ * for the RTMpOnSpecific API.
+ *
+ * @param   pvArg   Pointer to the RTMPARGS package.
+ */
+static void rtmpOnSpecificDarwinWrapper(void *pvArg)
+{
+    PRTMPARGS pArgs = (PRTMPARGS)pvArg;
+    RTCPUID idCpu = cpu_number();
+    if (pArgs->idCpu == idCpu)
+    {
+        IPRT_DARWIN_SAVE_EFL_AC();
+        pArgs->pfnWorker(idCpu, pArgs->pvUser1, pArgs->pvUser2);
+        ASMAtomicIncU32(&pArgs->cHits);
+        IPRT_DARWIN_RESTORE_EFL_AC();
+    }
+}
+
+
+RTDECL(int) RTMpOnSpecific(RTCPUID idCpu, PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    RT_ASSERT_INTS_ON();
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    RTMPARGS Args;
+    Args.pfnWorker = pfnWorker;
+    Args.pvUser1 = pvUser1;
+    Args.pvUser2 = pvUser2;
+    Args.idCpu = idCpu;
+    Args.cHits = 0;
+    mp_rendezvous_no_intrs(rtmpOnSpecificDarwinWrapper, &Args);
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return Args.cHits == 1
+         ? VINF_SUCCESS
+         : VERR_CPU_NOT_FOUND;
+}
+
+
+RTDECL(int) RTMpPokeCpu(RTCPUID idCpu)
+{
+    RT_ASSERT_INTS_ON();
+
+    if (g_pfnR0DarwinCpuInterrupt == NULL)
+        return VERR_NOT_SUPPORTED;
+    IPRT_DARWIN_SAVE_EFL_AC(); /* paranoia */
+    /// @todo use mp_cpus_kick() when available (since 10.10)?  It's probably slower (locks, mask iteration, checks), though...
+    g_pfnR0DarwinCpuInterrupt(idCpu);
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(bool) RTMpOnAllIsConcurrentSafe(void)
+{
+    return true;
+}
+
diff --git a/src/VBox/Runtime/r0drv/darwin/process-r0drv-darwin.cpp b/src/VBox/Runtime/r0drv/darwin/process-r0drv-darwin.cpp
new file mode 100644
index 00000000..4dad7c8a
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/process-r0drv-darwin.cpp
@@ -0,0 +1,46 @@
+/* $Id: process-r0drv-darwin.cpp $ */
+/** @file
+ * IPRT - Process, Ring-0 Driver, Darwin.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-darwin-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/process.h>
+
+
+RTDECL(RTPROCESS) RTProcSelf(void)
+{
+    return proc_selfpid();
+}
+
+
+RTR0DECL(RTR0PROCESS) RTR0ProcHandleSelf(void)
+{
+    return (RTR0PROCESS)current_task();
+}
+
diff --git a/src/VBox/Runtime/r0drv/darwin/rtStrFormatKernelAddress-r0drv-darwin.cpp b/src/VBox/Runtime/r0drv/darwin/rtStrFormatKernelAddress-r0drv-darwin.cpp
new file mode 100644
index 00000000..0a9d547d
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/rtStrFormatKernelAddress-r0drv-darwin.cpp
@@ -0,0 +1,50 @@
+/* $Id: rtStrFormatKernelAddress-r0drv-darwin.cpp $ */
+/** @file
+ * IPRT - IPRT String Formatter, ring-0 addresses.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define LOG_GROUP RTLOGGROUP_STRING
+#include "the-darwin-kernel.h"
+#include "internal/iprt.h"
+
+#include <iprt/assert.h>
+#include <iprt/string.h>
+
+#include "internal/string.h"
+
+
+DECLHIDDEN(size_t) rtStrFormatKernelAddress(char *pszBuf, size_t cbBuf, RTR0INTPTR uPtr, signed int cchWidth,
+                                            signed int cchPrecision, unsigned int fFlags)
+{
+    /*
+     * Kernel addresses don't need obfuscation in R0 because the kernel log is only accessible
+     * as root.
+     */
+    Assert(cbBuf >= 64); RT_NOREF(cbBuf);
+    return RTStrFormatNumber(pszBuf, uPtr, 16, cchWidth, cchPrecision, fFlags);
+}
diff --git a/src/VBox/Runtime/r0drv/darwin/semevent-r0drv-darwin.cpp b/src/VBox/Runtime/r0drv/darwin/semevent-r0drv-darwin.cpp
new file mode 100644
index 00000000..482673ac
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/semevent-r0drv-darwin.cpp
@@ -0,0 +1,427 @@
+/* $Id: semevent-r0drv-darwin.cpp $ */
+/** @file
+ * IPRT - Single Release Event Semaphores, Ring-0 Driver, Darwin.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTSEMEVENT_WITHOUT_REMAPPING
+#include "the-darwin-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/semaphore.h>
+
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/err.h>
+#include <iprt/list.h>
+#include <iprt/lockvalidator.h>
+#include <iprt/mem.h>
+#include <iprt/mp.h>
+#include <iprt/thread.h>
+#include <iprt/time.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Waiter entry.  Lives on the stack.
+ */
+typedef struct RTSEMEVENTDARWINENTRY
+{
+    /** The list node. */
+    RTLISTNODE  Node;
+    /** Flag set when waking up the thread by signal or destroy. */
+    bool volatile fWokenUp;
+} RTSEMEVENTDARWINENTRY;
+/** Pointer to waiter entry. */
+typedef RTSEMEVENTDARWINENTRY *PRTSEMEVENTDARWINENTRY;
+
+
+/**
+ * Darwin event semaphore.
+ */
+typedef struct RTSEMEVENTINTERNAL
+{
+    /** Magic value (RTSEMEVENT_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** Reference counter. */
+    uint32_t volatile   cRefs;
+    /** Set if there are blocked threads. */
+    bool volatile       fHaveBlockedThreads;
+    /** Set if the event object is signaled. */
+    bool volatile       fSignaled;
+    /** List of waiting and woken up threads. */
+    RTLISTANCHOR        WaitList;
+    /** The spinlock protecting us. */
+    lck_spin_t         *pSpinlock;
+} RTSEMEVENTINTERNAL, *PRTSEMEVENTINTERNAL;
+
+
+
+RTDECL(int)  RTSemEventCreate(PRTSEMEVENT phEventSem)
+{
+    return RTSemEventCreateEx(phEventSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, NULL);
+}
+
+
+RTDECL(int)  RTSemEventCreateEx(PRTSEMEVENT phEventSem, uint32_t fFlags, RTLOCKVALCLASS hClass, const char *pszNameFmt, ...)
+{
+    RT_NOREF(hClass, pszNameFmt);
+    AssertCompile(sizeof(RTSEMEVENTINTERNAL) > sizeof(void *));
+    AssertReturn(!(fFlags & ~(RTSEMEVENT_FLAGS_NO_LOCK_VAL | RTSEMEVENT_FLAGS_BOOTSTRAP_HACK)), VERR_INVALID_PARAMETER);
+    Assert(!(fFlags & RTSEMEVENT_FLAGS_BOOTSTRAP_HACK) || (fFlags & RTSEMEVENT_FLAGS_NO_LOCK_VAL));
+    AssertPtrReturn(phEventSem, VERR_INVALID_POINTER);
+    RT_ASSERT_PREEMPTIBLE();
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    PRTSEMEVENTINTERNAL pThis = (PRTSEMEVENTINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (pThis)
+    {
+        pThis->u32Magic = RTSEMEVENT_MAGIC;
+        pThis->cRefs                = 1;
+        pThis->fHaveBlockedThreads  = false;
+        pThis->fSignaled            = false;
+        RTListInit(&pThis->WaitList);
+        Assert(g_pDarwinLockGroup);
+        pThis->pSpinlock = lck_spin_alloc_init(g_pDarwinLockGroup, LCK_ATTR_NULL);
+        if (pThis->pSpinlock)
+        {
+            *phEventSem = pThis;
+            IPRT_DARWIN_RESTORE_EFL_AC();
+            return VINF_SUCCESS;
+        }
+
+        pThis->u32Magic = 0;
+        RTMemFree(pThis);
+    }
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return VERR_NO_MEMORY;
+}
+
+
+/**
+ * Retain a reference to the semaphore.
+ *
+ * @param   pThis       The semaphore.
+ */
+DECLINLINE(void) rtR0SemEventDarwinRetain(PRTSEMEVENTINTERNAL pThis)
+{
+    uint32_t cRefs = ASMAtomicIncU32(&pThis->cRefs);
+    Assert(cRefs && cRefs < 100000); RT_NOREF_PV(cRefs);
+}
+
+
+/**
+ * Release a reference, destroy the thing if necessary.
+ *
+ * @param   pThis       The semaphore.
+ */
+DECLINLINE(void) rtR0SemEventDarwinRelease(PRTSEMEVENTINTERNAL pThis)
+{
+    if (RT_UNLIKELY(ASMAtomicDecU32(&pThis->cRefs) == 0))
+    {
+        Assert(pThis->u32Magic != RTSEMEVENT_MAGIC);
+        IPRT_DARWIN_SAVE_EFL_AC();
+
+        lck_spin_destroy(pThis->pSpinlock, g_pDarwinLockGroup);
+        RTMemFree(pThis);
+
+        IPRT_DARWIN_RESTORE_EFL_AC();
+    }
+}
+
+RTDECL(int)  RTSemEventDestroy(RTSEMEVENT hEventSem)
+{
+    PRTSEMEVENTINTERNAL pThis = hEventSem;
+    if (pThis == NIL_RTSEMEVENT)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+    RT_ASSERT_INTS_ON();
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    RTCCUINTREG const fIntSaved = ASMIntDisableFlags();
+    lck_spin_lock(pThis->pSpinlock);
+
+    ASMAtomicWriteU32(&pThis->u32Magic, ~RTSEMEVENT_MAGIC); /* make the handle invalid */
+    ASMAtomicWriteBool(&pThis->fSignaled, false);
+
+    /* abort waiting threads. */
+    PRTSEMEVENTDARWINENTRY pWaiter;
+    RTListForEach(&pThis->WaitList, pWaiter, RTSEMEVENTDARWINENTRY, Node)
+    {
+        pWaiter->fWokenUp = true;
+        thread_wakeup_prim((event_t)pWaiter, FALSE /* all threads */, THREAD_RESTART);
+    }
+
+    lck_spin_unlock(pThis->pSpinlock);
+    ASMSetFlags(fIntSaved);
+    rtR0SemEventDarwinRelease(pThis);
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemEventSignal(RTSEMEVENT hEventSem)
+{
+    PRTSEMEVENTINTERNAL pThis = (PRTSEMEVENTINTERNAL)hEventSem;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC,
+                    ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic),
+                    VERR_INVALID_HANDLE);
+    RT_ASSERT_PREEMPT_CPUID_VAR();
+
+    /*
+     * Coming here with interrupts disabled should be okay.  The thread_wakeup_prim KPI is used
+     * by the interrupt handler IOFilterInterruptEventSource::disableInterruptOccurred() via
+     * signalWorkAvailable().  The only problem is if we have to destroy the event structure,
+     * as RTMemFree does not work with interrupts disabled (IOFree/kfree takes zone mutex).
+     */
+    //RT_ASSERT_INTS_ON(); - we may be called from interrupt context, which seems to be perfectly fine.
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    RTCCUINTREG const fIntSaved = ASMIntDisableFlags();
+    rtR0SemEventDarwinRetain(pThis);
+    lck_spin_lock(pThis->pSpinlock);
+
+    /*
+     * Wake up one thread.
+     */
+    ASMAtomicWriteBool(&pThis->fSignaled, true);
+
+    PRTSEMEVENTDARWINENTRY pWaiter;
+    RTListForEach(&pThis->WaitList, pWaiter, RTSEMEVENTDARWINENTRY, Node)
+    {
+        if (!pWaiter->fWokenUp)
+        {
+            pWaiter->fWokenUp = true;
+            thread_wakeup_prim((event_t)pWaiter, FALSE /* all threads */, THREAD_AWAKENED);
+            ASMAtomicWriteBool(&pThis->fSignaled, false);
+            break;
+        }
+    }
+
+    lck_spin_unlock(pThis->pSpinlock);
+    ASMSetFlags(fIntSaved);
+    rtR0SemEventDarwinRelease(pThis);
+
+    RT_ASSERT_PREEMPT_CPUID();
+    AssertMsg((fSavedEfl & X86_EFL_IF) == (ASMGetFlags() & X86_EFL_IF), ("fSavedEfl=%#x cur=%#x\n",(uint32_t)fSavedEfl, ASMGetFlags()));
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Worker for RTSemEventWaitEx and RTSemEventWaitExDebug.
+ *
+ * @returns VBox status code.
+ * @param   pThis           The event semaphore.
+ * @param   fFlags          See RTSemEventWaitEx.
+ * @param   uTimeout        See RTSemEventWaitEx.
+ * @param   pSrcPos         The source code position of the wait.
+ */
+static int rtR0SemEventDarwinWait(PRTSEMEVENTINTERNAL pThis, uint32_t fFlags, uint64_t uTimeout,
+                                  PCRTLOCKVALSRCPOS pSrcPos)
+{
+    RT_NOREF(pSrcPos);
+
+    /*
+     * Validate the input.
+     */
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    AssertReturn(RTSEMWAIT_FLAGS_ARE_VALID(fFlags), VERR_INVALID_PARAMETER);
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    RTCCUINTREG const fIntSaved = ASMIntDisableFlags();
+    rtR0SemEventDarwinRetain(pThis);
+    lck_spin_lock(pThis->pSpinlock);
+
+    /*
+     * In the signaled state?
+     */
+    int rc;
+    if (ASMAtomicCmpXchgBool(&pThis->fSignaled, false, true))
+        rc = VINF_SUCCESS;
+    else
+    {
+        /*
+         * We have to wait. So, we'll need to convert the timeout and figure
+         * out if it's indefinite or not.
+         */
+        uint64_t uNsAbsTimeout = 1;
+        if (!(fFlags & RTSEMWAIT_FLAGS_INDEFINITE))
+        {
+            if (fFlags & RTSEMWAIT_FLAGS_MILLISECS)
+                uTimeout = uTimeout < UINT64_MAX / UINT32_C(1000000) * UINT32_C(1000000)
+                         ? uTimeout * UINT32_C(1000000)
+                         : UINT64_MAX;
+            if (uTimeout == UINT64_MAX)
+                fFlags |= RTSEMWAIT_FLAGS_INDEFINITE;
+            else
+            {
+                uint64_t u64Now;
+                if (fFlags & RTSEMWAIT_FLAGS_RELATIVE)
+                {
+                    if (uTimeout != 0)
+                    {
+                        u64Now = RTTimeSystemNanoTS();
+                        uNsAbsTimeout = u64Now + uTimeout;
+                        if (uNsAbsTimeout < u64Now) /* overflow */
+                            fFlags |= RTSEMWAIT_FLAGS_INDEFINITE;
+                    }
+                }
+                else
+                {
+                    uNsAbsTimeout = uTimeout;
+                    u64Now        = RTTimeSystemNanoTS();
+                    uTimeout      = u64Now < uTimeout ? uTimeout - u64Now : 0;
+                }
+            }
+        }
+
+        if (   !(fFlags & RTSEMWAIT_FLAGS_INDEFINITE)
+            && uTimeout == 0)
+        {
+            /*
+             * Poll call, we already checked the condition above so no need to
+             * wait for anything.
+             */
+            rc = VERR_TIMEOUT;
+        }
+        else
+        {
+            RTSEMEVENTDARWINENTRY Waiter;
+            Waiter.fWokenUp = false;
+            RTListAppend(&pThis->WaitList, &Waiter.Node);
+
+            for (;;)
+            {
+                /*
+                 * Do the actual waiting.
+                 */
+                ASMAtomicWriteBool(&pThis->fHaveBlockedThreads, true);
+                wait_interrupt_t fInterruptible = fFlags & RTSEMWAIT_FLAGS_INTERRUPTIBLE ? THREAD_ABORTSAFE : THREAD_UNINT;
+                wait_result_t    rcWait;
+                if (fFlags & RTSEMWAIT_FLAGS_INDEFINITE)
+                    rcWait = lck_spin_sleep(pThis->pSpinlock, LCK_SLEEP_DEFAULT, (event_t)&Waiter, fInterruptible);
+                else
+                {
+                    uint64_t u64AbsTime;
+                    nanoseconds_to_absolutetime(uNsAbsTimeout, &u64AbsTime);
+                    rcWait = lck_spin_sleep_deadline(pThis->pSpinlock, LCK_SLEEP_DEFAULT,
+                                                     (event_t)&Waiter, fInterruptible, u64AbsTime);
+                }
+
+                /*
+                 * Deal with the wait result.
+                 */
+                if (RT_LIKELY(pThis->u32Magic == RTSEMEVENT_MAGIC))
+                {
+                    switch (rcWait)
+                    {
+                        case THREAD_AWAKENED:
+                            if (RT_LIKELY(Waiter.fWokenUp))
+                                rc = VINF_SUCCESS;
+                            else if (fFlags & RTSEMWAIT_FLAGS_INTERRUPTIBLE)
+                                rc = VERR_INTERRUPTED;
+                            else
+                                continue; /* Seen this happen after fork/exec/something. */
+                            break;
+
+                        case THREAD_TIMED_OUT:
+                            Assert(!(fFlags & RTSEMWAIT_FLAGS_INDEFINITE));
+                            rc = !Waiter.fWokenUp ? VERR_TIMEOUT : VINF_SUCCESS;
+                            break;
+
+                        case THREAD_INTERRUPTED:
+                            Assert(fInterruptible != THREAD_UNINT);
+                            rc = !Waiter.fWokenUp ? VERR_INTERRUPTED : VINF_SUCCESS;
+                            break;
+
+                        case THREAD_RESTART:
+                            AssertMsg(pThis->u32Magic == ~RTSEMEVENT_MAGIC, ("%#x\n", pThis->u32Magic));
+                            rc = VERR_SEM_DESTROYED;
+                            break;
+
+                        default:
+                            AssertMsgFailed(("rcWait=%d\n", rcWait));
+                            rc = VERR_INTERNAL_ERROR_3;
+                            break;
+                    }
+                }
+                else
+                    rc = VERR_SEM_DESTROYED;
+                break;
+            }
+
+            RTListNodeRemove(&Waiter.Node);
+        }
+    }
+
+    lck_spin_unlock(pThis->pSpinlock);
+    ASMSetFlags(fIntSaved);
+    rtR0SemEventDarwinRelease(pThis);
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return rc;
+}
+
+
+RTDECL(int)  RTSemEventWaitEx(RTSEMEVENT hEventSem, uint32_t fFlags, uint64_t uTimeout)
+{
+#ifndef RTSEMEVENT_STRICT
+    return rtR0SemEventDarwinWait(hEventSem, fFlags, uTimeout, NULL);
+#else
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
+    return rtR0SemEventDarwinWait(hEventSem, fFlags, uTimeout, &SrcPos);
+#endif
+}
+
+
+RTDECL(int)  RTSemEventWaitExDebug(RTSEMEVENT hEventSem, uint32_t fFlags, uint64_t uTimeout,
+                                   RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
+    return rtR0SemEventDarwinWait(hEventSem, fFlags, uTimeout, &SrcPos);
+}
+
+
+RTDECL(uint32_t) RTSemEventGetResolution(void)
+{
+    uint64_t cNs;
+    absolutetime_to_nanoseconds(1, &cNs);
+    return (uint32_t)cNs ? (uint32_t)cNs : 0;
+}
+
diff --git a/src/VBox/Runtime/r0drv/darwin/semeventmulti-r0drv-darwin.cpp b/src/VBox/Runtime/r0drv/darwin/semeventmulti-r0drv-darwin.cpp
new file mode 100644
index 00000000..220f5007
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/semeventmulti-r0drv-darwin.cpp
@@ -0,0 +1,450 @@
+/* $Id: semeventmulti-r0drv-darwin.cpp $ */
+/** @file
+ * IPRT - Multiple Release Event Semaphores, Ring-0 Driver, Darwin.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTSEMEVENTMULTI_WITHOUT_REMAPPING
+#define RTMEM_NO_WRAP_TO_EF_APIS /* rtR0MemObjNativeProtect depends on this code, so no electrical fences here or we'll \#DF. */
+#include "the-darwin-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/semaphore.h>
+
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/err.h>
+#include <iprt/lockvalidator.h>
+#include <iprt/mem.h>
+#include <iprt/mp.h>
+#include <iprt/thread.h>
+#include <iprt/time.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+/** @name fStateAndGen values
+ * @{ */
+/** The state bit number. */
+#define RTSEMEVENTMULTIDARWIN_STATE_BIT         0
+/** The state mask. */
+#define RTSEMEVENTMULTIDARWIN_STATE_MASK        RT_BIT_32(RTSEMEVENTMULTIDARWIN_STATE_BIT)
+/** The generation mask. */
+#define RTSEMEVENTMULTIDARWIN_GEN_MASK          ~RTSEMEVENTMULTIDARWIN_STATE_MASK
+/** The generation shift. */
+#define RTSEMEVENTMULTIDARWIN_GEN_SHIFT         1
+/** The initial variable value. */
+#define RTSEMEVENTMULTIDARWIN_STATE_GEN_INIT    UINT32_C(0xfffffffc)
+/** @}  */
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Darwin multiple release event semaphore.
+ */
+typedef struct RTSEMEVENTMULTIINTERNAL
+{
+    /** Magic value (RTSEMEVENTMULTI_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** The object state bit and generation counter.
+     * The generation counter is incremented every time the object is
+     * signalled. */
+    uint32_t volatile   fStateAndGen;
+    /** Reference counter. */
+    uint32_t volatile   cRefs;
+    /** Set if there are blocked threads. */
+    bool volatile       fHaveBlockedThreads;
+    /** The spinlock protecting us. */
+    lck_spin_t         *pSpinlock;
+} RTSEMEVENTMULTIINTERNAL, *PRTSEMEVENTMULTIINTERNAL;
+
+
+
+RTDECL(int)  RTSemEventMultiCreate(PRTSEMEVENTMULTI phEventMultiSem)
+{
+    return RTSemEventMultiCreateEx(phEventMultiSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, NULL);
+}
+
+
+RTDECL(int)  RTSemEventMultiCreateEx(PRTSEMEVENTMULTI phEventMultiSem, uint32_t fFlags, RTLOCKVALCLASS hClass,
+                                     const char *pszNameFmt, ...)
+{
+    RT_NOREF(hClass, pszNameFmt);
+    AssertReturn(!(fFlags & ~RTSEMEVENTMULTI_FLAGS_NO_LOCK_VAL), VERR_INVALID_PARAMETER);
+    AssertCompile(sizeof(RTSEMEVENTMULTIINTERNAL) > sizeof(void *));
+    AssertPtrReturn(phEventMultiSem, VERR_INVALID_POINTER);
+    RT_ASSERT_PREEMPTIBLE();
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (pThis)
+    {
+        pThis->u32Magic             = RTSEMEVENTMULTI_MAGIC;
+        pThis->fStateAndGen         = RTSEMEVENTMULTIDARWIN_STATE_GEN_INIT;
+        pThis->cRefs                = 1;
+        pThis->fHaveBlockedThreads  = false;
+        Assert(g_pDarwinLockGroup);
+        pThis->pSpinlock = lck_spin_alloc_init(g_pDarwinLockGroup, LCK_ATTR_NULL);
+        if (pThis->pSpinlock)
+        {
+            *phEventMultiSem = pThis;
+            IPRT_DARWIN_RESTORE_EFL_AC();
+            return VINF_SUCCESS;
+        }
+
+        pThis->u32Magic = 0;
+        RTMemFree(pThis);
+    }
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return VERR_NO_MEMORY;
+}
+
+
+/**
+ * Retain a reference to the semaphore.
+ *
+ * @param   pThis       The semaphore.
+ */
+DECLINLINE(void) rtR0SemEventMultiDarwinRetain(PRTSEMEVENTMULTIINTERNAL pThis)
+{
+    uint32_t cRefs = ASMAtomicIncU32(&pThis->cRefs);
+    Assert(cRefs && cRefs < 100000);
+    RT_NOREF_PV(cRefs);
+}
+
+
+/**
+ * Release a reference, destroy the thing if necessary.
+ *
+ * @param   pThis       The semaphore.
+ */
+DECLINLINE(void) rtR0SemEventMultiDarwinRelease(PRTSEMEVENTMULTIINTERNAL pThis)
+{
+    if (RT_UNLIKELY(ASMAtomicDecU32(&pThis->cRefs) == 0))
+    {
+        IPRT_DARWIN_SAVE_EFL_AC();
+        Assert(pThis->u32Magic != RTSEMEVENTMULTI_MAGIC);
+
+        lck_spin_destroy(pThis->pSpinlock, g_pDarwinLockGroup);
+        RTMemFree(pThis);
+
+        IPRT_DARWIN_RESTORE_EFL_AC();
+    }
+}
+
+
+RTDECL(int)  RTSemEventMultiDestroy(RTSEMEVENTMULTI hEventMultiSem)
+{
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    if (pThis == NIL_RTSEMEVENTMULTI)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+    Assert(pThis->cRefs > 0);
+    RT_ASSERT_INTS_ON();
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    RTCCUINTREG const fIntSaved = ASMIntDisableFlags();
+    lck_spin_lock(pThis->pSpinlock);
+
+    ASMAtomicWriteU32(&pThis->u32Magic, ~RTSEMEVENTMULTI_MAGIC); /* make the handle invalid */
+    ASMAtomicAndU32(&pThis->fStateAndGen, RTSEMEVENTMULTIDARWIN_GEN_MASK);
+    if (pThis->fHaveBlockedThreads)
+    {
+        /* abort waiting threads. */
+        thread_wakeup_prim((event_t)pThis, FALSE /* all threads */, THREAD_RESTART);
+    }
+
+    lck_spin_unlock(pThis->pSpinlock);
+    ASMSetFlags(fIntSaved);
+    rtR0SemEventMultiDarwinRelease(pThis);
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemEventMultiSignal(RTSEMEVENTMULTI hEventMultiSem)
+{
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+    RT_ASSERT_PREEMPT_CPUID_VAR();
+
+    /*
+     * Coming here with interrupts disabled should be okay.  The thread_wakeup_prim KPI is used
+     * by the interrupt handler IOFilterInterruptEventSource::disableInterruptOccurred() via
+     * signalWorkAvailable().  The only problem is if we have to destroy the event structure,
+     * as RTMemFree does not work with interrupts disabled (IOFree/kfree takes zone mutex).
+     */
+    //RT_ASSERT_INTS_ON(); - we may be called from interrupt context, which seems to be perfectly fine if we disable interrupts.
+
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    RTCCUINTREG const fIntSaved = ASMIntDisableFlags();
+    rtR0SemEventMultiDarwinRetain(pThis);
+    lck_spin_lock(pThis->pSpinlock);
+
+    /*
+     * Set the signal and increment the generation counter.
+     */
+    uint32_t fNew = ASMAtomicUoReadU32(&pThis->fStateAndGen);
+    fNew += 1 << RTSEMEVENTMULTIDARWIN_GEN_SHIFT;
+    fNew |= RTSEMEVENTMULTIDARWIN_STATE_MASK;
+    ASMAtomicWriteU32(&pThis->fStateAndGen, fNew);
+
+    /*
+     * Wake up all sleeping threads.
+     */
+    if (pThis->fHaveBlockedThreads)
+    {
+        ASMAtomicWriteBool(&pThis->fHaveBlockedThreads, false);
+        thread_wakeup_prim((event_t)pThis, FALSE /* all threads */, THREAD_AWAKENED);
+    }
+
+    lck_spin_unlock(pThis->pSpinlock);
+    ASMSetFlags(fIntSaved);
+    rtR0SemEventMultiDarwinRelease(pThis);
+
+    RT_ASSERT_PREEMPT_CPUID();
+    AssertMsg((fSavedEfl & X86_EFL_IF) == (ASMGetFlags() & X86_EFL_IF), ("fSavedEfl=%#x cur=%#x\n",(uint32_t)fSavedEfl, ASMGetFlags()));
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemEventMultiReset(RTSEMEVENTMULTI hEventMultiSem)
+{
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+    RT_ASSERT_PREEMPT_CPUID_VAR();
+    RT_ASSERT_INTS_ON();
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    RTCCUINTREG const fIntSaved = ASMIntDisableFlags();
+    rtR0SemEventMultiDarwinRetain(pThis);
+    lck_spin_lock(pThis->pSpinlock);
+
+    ASMAtomicAndU32(&pThis->fStateAndGen, ~RTSEMEVENTMULTIDARWIN_STATE_MASK);
+
+    lck_spin_unlock(pThis->pSpinlock);
+    ASMSetFlags(fIntSaved);
+    rtR0SemEventMultiDarwinRelease(pThis);
+
+    RT_ASSERT_PREEMPT_CPUID();
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Worker for RTSemEventMultiWaitEx and RTSemEventMultiWaitExDebug.
+ *
+ * @returns VBox status code.
+ * @param   pThis           The event semaphore.
+ * @param   fFlags          See RTSemEventMultiWaitEx.
+ * @param   uTimeout        See RTSemEventMultiWaitEx.
+ * @param   pSrcPos         The source code position of the wait.
+ */
+static int rtR0SemEventMultiDarwinWait(PRTSEMEVENTMULTIINTERNAL pThis, uint32_t fFlags, uint64_t uTimeout,
+                                       PCRTLOCKVALSRCPOS pSrcPos)
+{
+    RT_NOREF(pSrcPos);
+
+    /*
+     * Validate input.
+     */
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+    AssertReturn(RTSEMWAIT_FLAGS_ARE_VALID(fFlags), VERR_INVALID_PARAMETER);
+    if (uTimeout != 0 || (fFlags & RTSEMWAIT_FLAGS_INDEFINITE))
+        RT_ASSERT_PREEMPTIBLE();
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    RTCCUINTREG const fIntSaved = ASMIntDisableFlags();
+    rtR0SemEventMultiDarwinRetain(pThis);
+    lck_spin_lock(pThis->pSpinlock);
+
+    /*
+     * Is the event already signalled or do we have to wait?
+     */
+    int rc;
+    uint32_t const fOrgStateAndGen = ASMAtomicUoReadU32(&pThis->fStateAndGen);
+    if (fOrgStateAndGen & RTSEMEVENTMULTIDARWIN_STATE_MASK)
+        rc = VINF_SUCCESS;
+    else
+    {
+        /*
+         * We have to wait. So, we'll need to convert the timeout and figure
+         * out if it's indefinite or not.
+         */
+        uint64_t uNsAbsTimeout = 1;
+        if (!(fFlags & RTSEMWAIT_FLAGS_INDEFINITE))
+        {
+            if (fFlags & RTSEMWAIT_FLAGS_MILLISECS)
+                uTimeout = uTimeout < UINT64_MAX / UINT32_C(1000000) * UINT32_C(1000000)
+                         ? uTimeout * UINT32_C(1000000)
+                         : UINT64_MAX;
+            if (uTimeout == UINT64_MAX)
+                fFlags |= RTSEMWAIT_FLAGS_INDEFINITE;
+            else
+            {
+                uint64_t u64Now;
+                if (fFlags & RTSEMWAIT_FLAGS_RELATIVE)
+                {
+                    if (uTimeout != 0)
+                    {
+                        u64Now = RTTimeSystemNanoTS();
+                        uNsAbsTimeout = u64Now + uTimeout;
+                        if (uNsAbsTimeout < u64Now) /* overflow */
+                            fFlags |= RTSEMWAIT_FLAGS_INDEFINITE;
+                    }
+                }
+                else
+                {
+                    uNsAbsTimeout = uTimeout;
+                    u64Now        = RTTimeSystemNanoTS();
+                    uTimeout      = u64Now < uTimeout ? uTimeout - u64Now : 0;
+                }
+            }
+        }
+
+        if (   !(fFlags & RTSEMWAIT_FLAGS_INDEFINITE)
+            && uTimeout == 0)
+        {
+            /*
+             * Poll call, we already checked the condition above so no need to
+             * wait for anything.
+             */
+            rc = VERR_TIMEOUT;
+        }
+        else
+        {
+            for (;;)
+            {
+                /*
+                 * Do the actual waiting.
+                 */
+                ASMAtomicWriteBool(&pThis->fHaveBlockedThreads, true);
+                wait_interrupt_t fInterruptible = fFlags & RTSEMWAIT_FLAGS_INTERRUPTIBLE ? THREAD_ABORTSAFE : THREAD_UNINT;
+                wait_result_t    rcWait;
+                if (fFlags & RTSEMWAIT_FLAGS_INDEFINITE)
+                    rcWait = lck_spin_sleep(pThis->pSpinlock, LCK_SLEEP_DEFAULT, (event_t)pThis, fInterruptible);
+                else
+                {
+                    uint64_t u64AbsTime;
+                    nanoseconds_to_absolutetime(uNsAbsTimeout, &u64AbsTime);
+                    rcWait = lck_spin_sleep_deadline(pThis->pSpinlock, LCK_SLEEP_DEFAULT,
+                                                     (event_t)pThis, fInterruptible, u64AbsTime);
+                }
+
+                /*
+                 * Deal with the wait result.
+                 */
+                if (RT_LIKELY(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC))
+                {
+                    switch (rcWait)
+                    {
+                        case THREAD_AWAKENED:
+                            if (RT_LIKELY(ASMAtomicUoReadU32(&pThis->fStateAndGen) != fOrgStateAndGen))
+                                rc = VINF_SUCCESS;
+                            else if (fFlags & RTSEMWAIT_FLAGS_INTERRUPTIBLE)
+                                rc = VERR_INTERRUPTED;
+                            else
+                                continue; /* Seen this happen after fork/exec/something. */
+                            break;
+
+                        case THREAD_TIMED_OUT:
+                            Assert(!(fFlags & RTSEMWAIT_FLAGS_INDEFINITE));
+                            rc = VERR_TIMEOUT;
+                            break;
+
+                        case THREAD_INTERRUPTED:
+                            Assert(fInterruptible != THREAD_UNINT);
+                            rc = VERR_INTERRUPTED;
+                            break;
+
+                        case THREAD_RESTART:
+                            AssertMsg(pThis->u32Magic == ~RTSEMEVENTMULTI_MAGIC, ("%#x\n", pThis->u32Magic));
+                            rc = VERR_SEM_DESTROYED;
+                            break;
+
+                        default:
+                            AssertMsgFailed(("rcWait=%d\n", rcWait));
+                            rc = VERR_INTERNAL_ERROR_3;
+                            break;
+                    }
+                }
+                else
+                    rc = VERR_SEM_DESTROYED;
+                break;
+            }
+        }
+    }
+
+    lck_spin_unlock(pThis->pSpinlock);
+    ASMSetFlags(fIntSaved);
+    rtR0SemEventMultiDarwinRelease(pThis);
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return rc;
+}
+
+RTDECL(int)  RTSemEventMultiWaitEx(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout)
+{
+#ifndef RTSEMEVENT_STRICT
+    return rtR0SemEventMultiDarwinWait(hEventMultiSem, fFlags, uTimeout, NULL);
+#else
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
+    return rtR0SemEventMultiDarwinWait(hEventMultiSem, fFlags, uTimeout, &SrcPos);
+#endif
+}
+
+
+RTDECL(int)  RTSemEventMultiWaitExDebug(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout,
+                                        RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
+    return rtR0SemEventMultiDarwinWait(hEventMultiSem, fFlags, uTimeout, &SrcPos);
+}
+
+
+RTDECL(uint32_t) RTSemEventMultiGetResolution(void)
+{
+    uint64_t cNs;
+    absolutetime_to_nanoseconds(1, &cNs);
+    return (uint32_t)cNs ? (uint32_t)cNs : 0;
+}
+
diff --git a/src/VBox/Runtime/r0drv/darwin/semfastmutex-r0drv-darwin.cpp b/src/VBox/Runtime/r0drv/darwin/semfastmutex-r0drv-darwin.cpp
new file mode 100644
index 00000000..06875384
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/semfastmutex-r0drv-darwin.cpp
@@ -0,0 +1,140 @@
+/* $Id: semfastmutex-r0drv-darwin.cpp $ */
+/** @file
+ * IPRT - Fast Mutex Semaphores, Ring-0 Driver, Darwin.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-darwin-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/semaphore.h>
+
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/errcore.h>
+#include <iprt/mem.h>
+#include <iprt/mp.h>
+#include <iprt/thread.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Wrapper for the darwin semaphore structure.
+ */
+typedef struct RTSEMFASTMUTEXINTERNAL
+{
+    /** Magic value (RTSEMFASTMUTEX_MAGIC). */
+    uint32_t            u32Magic;
+    /** The mutex. */
+    lck_mtx_t          *pMtx;
+} RTSEMFASTMUTEXINTERNAL, *PRTSEMFASTMUTEXINTERNAL;
+
+
+
+RTDECL(int)  RTSemFastMutexCreate(PRTSEMFASTMUTEX phFastMtx)
+{
+    AssertCompile(sizeof(RTSEMFASTMUTEXINTERNAL) > sizeof(void *));
+    AssertPtrReturn(phFastMtx, VERR_INVALID_POINTER);
+    RT_ASSERT_PREEMPTIBLE();
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    PRTSEMFASTMUTEXINTERNAL pThis = (PRTSEMFASTMUTEXINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (pThis)
+    {
+        pThis->u32Magic = RTSEMFASTMUTEX_MAGIC;
+        Assert(g_pDarwinLockGroup);
+        pThis->pMtx = lck_mtx_alloc_init(g_pDarwinLockGroup, LCK_ATTR_NULL);
+        if (pThis->pMtx)
+        {
+            *phFastMtx = pThis;
+            IPRT_DARWIN_RESTORE_EFL_AC();
+            return VINF_SUCCESS;
+        }
+
+        RTMemFree(pThis);
+    }
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return VERR_NO_MEMORY;
+}
+
+
+RTDECL(int)  RTSemFastMutexDestroy(RTSEMFASTMUTEX hFastMtx)
+{
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    if (pThis == NIL_RTSEMFASTMUTEX)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+    RT_ASSERT_INTS_ON();
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    ASMAtomicWriteU32(&pThis->u32Magic, RTSEMFASTMUTEX_MAGIC_DEAD);
+    Assert(g_pDarwinLockGroup);
+    lck_mtx_free(pThis->pMtx, g_pDarwinLockGroup);
+    pThis->pMtx = NULL;
+    RTMemFree(pThis);
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemFastMutexRequest(RTSEMFASTMUTEX hFastMtx)
+{
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+    RT_ASSERT_PREEMPTIBLE();
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    lck_mtx_lock(pThis->pMtx);
+
+    IPRT_DARWIN_RESTORE_EFL_ONLY_AC();
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemFastMutexRelease(RTSEMFASTMUTEX hFastMtx)
+{
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+    RT_ASSERT_PREEMPTIBLE();
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    lck_mtx_unlock(pThis->pMtx);
+
+    IPRT_DARWIN_RESTORE_EFL_ONLY_AC();
+    return VINF_SUCCESS;
+}
+
diff --git a/src/VBox/Runtime/r0drv/darwin/semmutex-r0drv-darwin.cpp b/src/VBox/Runtime/r0drv/darwin/semmutex-r0drv-darwin.cpp
new file mode 100644
index 00000000..cfb3d04b
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/semmutex-r0drv-darwin.cpp
@@ -0,0 +1,407 @@
+/* $Id: semmutex-r0drv-darwin.cpp $ */
+/** @file
+ * IPRT - Mutex Semaphores, Ring-0 Driver, Darwin.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTSEMMUTEX_WITHOUT_REMAPPING
+#include "the-darwin-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/semaphore.h>
+
+#include <iprt/asm.h>
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/mem.h>
+#include <iprt/thread.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Darwin mutex semaphore.
+ */
+typedef struct RTSEMMUTEXINTERNAL
+{
+    /** Magic value (RTSEMMUTEX_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** The number of waiting threads. */
+    uint32_t            cWaiters;
+    /** The number of references. */
+    uint32_t volatile   cRefs;
+    /** The number of recursions. */
+    uint32_t            cRecursions;
+    /** The handle of the owner thread. */
+    RTNATIVETHREAD      hNativeOwner;
+    /** The spinlock protecting us. */
+    lck_spin_t         *pSpinlock;
+} RTSEMMUTEXINTERNAL, *PRTSEMMUTEXINTERNAL;
+
+
+
+RTDECL(int)  RTSemMutexCreate(PRTSEMMUTEX phMutexSem)
+{
+    return RTSemMutexCreateEx(phMutexSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, RTLOCKVAL_SUB_CLASS_NONE, NULL);
+}
+
+
+RTDECL(int) RTSemMutexCreateEx(PRTSEMMUTEX phMutexSem, uint32_t fFlags,
+                               RTLOCKVALCLASS hClass, uint32_t uSubClass, const char *pszNameFmt, ...)
+{
+    RT_NOREF(hClass, uSubClass, pszNameFmt);
+    AssertReturn(!(fFlags & ~RTSEMMUTEX_FLAGS_NO_LOCK_VAL), VERR_INVALID_PARAMETER);
+    RT_ASSERT_PREEMPTIBLE();
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    AssertCompile(sizeof(RTSEMMUTEXINTERNAL) > sizeof(void *));
+    PRTSEMMUTEXINTERNAL pThis = (PRTSEMMUTEXINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (pThis)
+    {
+        pThis->u32Magic     = RTSEMMUTEX_MAGIC;
+        pThis->cWaiters     = 0;
+        pThis->cRefs        = 1;
+        pThis->cRecursions  = 0;
+        pThis->hNativeOwner = NIL_RTNATIVETHREAD;
+        Assert(g_pDarwinLockGroup);
+        pThis->pSpinlock = lck_spin_alloc_init(g_pDarwinLockGroup, LCK_ATTR_NULL);
+        if (pThis->pSpinlock)
+        {
+            *phMutexSem = pThis;
+            IPRT_DARWIN_RESTORE_EFL_AC();
+            return VINF_SUCCESS;
+        }
+
+        RTMemFree(pThis);
+    }
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return VERR_NO_MEMORY;
+}
+
+
+/**
+ * Called when the refcount reaches zero.
+ */
+static void rtSemMutexDarwinFree(PRTSEMMUTEXINTERNAL pThis)
+{
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    lck_spin_unlock(pThis->pSpinlock);
+    lck_spin_destroy(pThis->pSpinlock, g_pDarwinLockGroup);
+    RTMemFree(pThis);
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+}
+
+
+RTDECL(int)  RTSemMutexDestroy(RTSEMMUTEX hMutexSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMMUTEXINTERNAL pThis = (PRTSEMMUTEXINTERNAL)hMutexSem;
+    if (pThis == NIL_RTSEMMUTEX)
+        return VERR_INVALID_PARAMETER;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+    RT_ASSERT_INTS_ON();
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    /*
+     * Kill it, wake up all waiting threads and release the reference.
+     */
+    AssertReturn(ASMAtomicCmpXchgU32(&pThis->u32Magic, ~RTSEMMUTEX_MAGIC, RTSEMMUTEX_MAGIC), VERR_INVALID_HANDLE);
+    lck_spin_lock(pThis->pSpinlock);
+
+    if (pThis->cWaiters > 0)
+        thread_wakeup_prim((event_t)pThis, FALSE /* one_thread */, THREAD_RESTART);
+
+    if (ASMAtomicDecU32(&pThis->cRefs) == 0)
+        rtSemMutexDarwinFree(pThis);
+    else
+        lck_spin_unlock(pThis->pSpinlock);
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Internal worker for the sleep scenario.
+ *
+ * Called owning the spinlock, returns without it.
+ *
+ * @returns IPRT status code.
+ * @param   pThis               The mutex instance.
+ * @param   cMillies            The timeout.
+ * @param   fInterruptible      Whether it's interruptible
+ *                              (RTSemMutexRequestNoResume) or not
+ *                              (RTSemMutexRequest).
+ * @param   hNativeSelf         The thread handle of the caller.
+ */
+static int rtR0SemMutexDarwinRequestSleep(PRTSEMMUTEXINTERNAL pThis, RTMSINTERVAL cMillies,
+                                          wait_interrupt_t fInterruptible, RTNATIVETHREAD hNativeSelf)
+{
+    /*
+     * Grab a reference and indicate that we're waiting.
+     */
+    pThis->cWaiters++;
+    ASMAtomicIncU32(&pThis->cRefs);
+
+    /*
+     * Go to sleep, use the address of the mutex instance as sleep/blocking/event id.
+     */
+    wait_result_t rcWait;
+    if (cMillies == RT_INDEFINITE_WAIT)
+        rcWait = lck_spin_sleep(pThis->pSpinlock, LCK_SLEEP_DEFAULT, (event_t)pThis, fInterruptible);
+    else
+    {
+        uint64_t u64AbsTime;
+        nanoseconds_to_absolutetime(cMillies * UINT64_C(1000000), &u64AbsTime);
+        u64AbsTime += mach_absolute_time();
+
+        rcWait = lck_spin_sleep_deadline(pThis->pSpinlock, LCK_SLEEP_DEFAULT,
+                                         (event_t)pThis, fInterruptible, u64AbsTime);
+    }
+
+    /*
+     * Translate the rc.
+     */
+    int rc;
+    switch (rcWait)
+    {
+        case THREAD_AWAKENED:
+            if (RT_LIKELY(pThis->u32Magic == RTSEMMUTEX_MAGIC))
+            {
+                if (RT_LIKELY(   pThis->cRecursions  == 0
+                              && pThis->hNativeOwner == NIL_RTNATIVETHREAD))
+                {
+                    pThis->cRecursions  = 1;
+                    pThis->hNativeOwner = hNativeSelf;
+                    rc = VINF_SUCCESS;
+                }
+                else
+                {
+                    Assert(pThis->cRecursions  == 0);
+                    Assert(pThis->hNativeOwner == NIL_RTNATIVETHREAD);
+                    rc = VERR_INTERNAL_ERROR_3;
+                }
+            }
+            else
+                rc = VERR_SEM_DESTROYED;
+            break;
+
+        case THREAD_TIMED_OUT:
+            Assert(cMillies != RT_INDEFINITE_WAIT);
+            rc = VERR_TIMEOUT;
+            break;
+
+        case THREAD_INTERRUPTED:
+            Assert(fInterruptible);
+            rc = VERR_INTERRUPTED;
+            break;
+
+        case THREAD_RESTART:
+            Assert(pThis->u32Magic == ~RTSEMMUTEX_MAGIC);
+            rc = VERR_SEM_DESTROYED;
+            break;
+
+        default:
+            AssertMsgFailed(("rcWait=%d\n", rcWait));
+            rc = VERR_GENERAL_FAILURE;
+            break;
+    }
+
+    /*
+     * Dereference it and quit the lock.
+     */
+    Assert(pThis->cWaiters > 0);
+    pThis->cWaiters--;
+
+    Assert(pThis->cRefs > 0);
+    if (RT_UNLIKELY(ASMAtomicDecU32(&pThis->cRefs) == 0))
+        rtSemMutexDarwinFree(pThis);
+    else
+        lck_spin_unlock(pThis->pSpinlock);
+    return rc;
+}
+
+
+/**
+ * Internal worker for RTSemMutexRequest and RTSemMutexRequestNoResume
+ *
+ * @returns IPRT status code.
+ * @param   hMutexSem           The mutex handle.
+ * @param   cMillies            The timeout.
+ * @param   fInterruptible      Whether it's interruptible
+ *                              (RTSemMutexRequestNoResume) or not
+ *                              (RTSemMutexRequest).
+ */
+DECLINLINE(int) rtR0SemMutexDarwinRequest(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, wait_interrupt_t fInterruptible)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMMUTEXINTERNAL pThis = (PRTSEMMUTEXINTERNAL)hMutexSem;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, VERR_INVALID_HANDLE);
+    RT_ASSERT_PREEMPTIBLE();
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    /*
+     * Grab the lock and check out the state.
+     */
+    RTNATIVETHREAD  hNativeSelf = RTThreadNativeSelf();
+    int             rc          = VINF_SUCCESS;
+    lck_spin_lock(pThis->pSpinlock);
+
+    /* Recursive call? */
+    if (pThis->hNativeOwner == hNativeSelf)
+    {
+        Assert(pThis->cRecursions > 0);
+        Assert(pThis->cRecursions < 256);
+        pThis->cRecursions++;
+    }
+
+    /* Is it free and nobody ahead of us in the queue? */
+    else if (   pThis->hNativeOwner == NIL_RTNATIVETHREAD
+             && pThis->cWaiters     == 0)
+    {
+        pThis->hNativeOwner = hNativeSelf;
+        pThis->cRecursions  = 1;
+    }
+
+    /* Polling call? */
+    else if (cMillies == 0)
+        rc = VERR_TIMEOUT;
+
+    /* Yawn, time for a nap... */
+    else
+    {
+        rc = rtR0SemMutexDarwinRequestSleep(pThis, cMillies, fInterruptible, hNativeSelf);
+        IPRT_DARWIN_RESTORE_EFL_ONLY_AC();
+        return rc;
+    }
+
+    lck_spin_unlock(pThis->pSpinlock);
+    IPRT_DARWIN_RESTORE_EFL_ONLY_AC();
+    return rc;
+}
+
+
+RTDECL(int) RTSemMutexRequest(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies)
+{
+    return rtR0SemMutexDarwinRequest(hMutexSem, cMillies, THREAD_UNINT);
+}
+
+
+RTDECL(int) RTSemMutexRequestDebug(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RT_SRC_POS_NOREF(); RT_NOREF(uId);
+    return RTSemMutexRequest(hMutexSem, cMillies);
+}
+
+
+RTDECL(int) RTSemMutexRequestNoResume(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies)
+{
+    return rtR0SemMutexDarwinRequest(hMutexSem, cMillies, THREAD_ABORTSAFE);
+}
+
+
+RTDECL(int) RTSemMutexRequestNoResumeDebug(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RT_SRC_POS_NOREF(); RT_NOREF(uId);
+    return RTSemMutexRequestNoResume(hMutexSem, cMillies);
+}
+
+
+RTDECL(int)  RTSemMutexRelease(RTSEMMUTEX hMutexSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMMUTEXINTERNAL pThis = (PRTSEMMUTEXINTERNAL)hMutexSem;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, VERR_INVALID_HANDLE);
+    RT_ASSERT_PREEMPTIBLE();
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    /*
+     * Take the lock and do the job.
+     */
+    RTNATIVETHREAD  hNativeSelf = RTThreadNativeSelf();
+    int             rc          = VINF_SUCCESS;
+    lck_spin_lock(pThis->pSpinlock);
+
+    if (pThis->hNativeOwner == hNativeSelf)
+    {
+        Assert(pThis->cRecursions > 0);
+        if (--pThis->cRecursions == 0)
+        {
+            pThis->hNativeOwner = NIL_RTNATIVETHREAD;
+            if (pThis->cWaiters > 0)
+                thread_wakeup_prim((event_t)pThis, TRUE /* one_thread */, THREAD_AWAKENED);
+
+        }
+    }
+    else
+        rc = VERR_NOT_OWNER;
+
+    lck_spin_unlock(pThis->pSpinlock);
+
+    AssertRC(rc);
+    IPRT_DARWIN_RESTORE_EFL_ONLY_AC();
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(bool) RTSemMutexIsOwned(RTSEMMUTEX hMutexSem)
+{
+    /*
+     * Validate.
+     */
+    RTSEMMUTEXINTERNAL *pThis = hMutexSem;
+    AssertPtrReturn(pThis, false);
+    AssertReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, false);
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    /*
+     * Take the lock and do the check.
+     */
+    lck_spin_lock(pThis->pSpinlock);
+    bool fRc = pThis->hNativeOwner != NIL_RTNATIVETHREAD;
+    lck_spin_unlock(pThis->pSpinlock);
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return fRc;
+}
+
diff --git a/src/VBox/Runtime/r0drv/darwin/spinlock-r0drv-darwin.cpp b/src/VBox/Runtime/r0drv/darwin/spinlock-r0drv-darwin.cpp
new file mode 100644
index 00000000..3d7e0fb8
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/spinlock-r0drv-darwin.cpp
@@ -0,0 +1,177 @@
+/* $Id: spinlock-r0drv-darwin.cpp $ */
+/** @file
+ * IPRT - Spinlocks, Ring-0 Driver, Darwin.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-darwin-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/spinlock.h>
+
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/errcore.h>
+#include <iprt/mem.h>
+#include <iprt/thread.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Wrapper for the KSPIN_LOCK type.
+ */
+typedef struct RTSPINLOCKINTERNAL
+{
+    /** Spinlock magic value (RTSPINLOCK_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** Saved interrupt flag. */
+    uint32_t volatile   fIntSaved;
+    /** Creation flags. */
+    uint32_t            fFlags;
+    /** The Darwin spinlock structure. */
+    lck_spin_t         *pSpinLock;
+    /** The spinlock name. */
+    const char         *pszName;
+} RTSPINLOCKINTERNAL, *PRTSPINLOCKINTERNAL;
+
+
+
+RTDECL(int)  RTSpinlockCreate(PRTSPINLOCK pSpinlock, uint32_t fFlags, const char *pszName)
+{
+    RT_ASSERT_PREEMPTIBLE();
+    AssertReturn(fFlags == RTSPINLOCK_FLAGS_INTERRUPT_SAFE || fFlags == RTSPINLOCK_FLAGS_INTERRUPT_UNSAFE, VERR_INVALID_PARAMETER);
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    /*
+     * Allocate.
+     */
+    AssertCompile(sizeof(RTSPINLOCKINTERNAL) > sizeof(void *));
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (pThis)
+    {
+        /*
+         * Initialize & return.
+         */
+        pThis->u32Magic  = RTSPINLOCK_MAGIC;
+        pThis->fIntSaved = 0;
+        pThis->fFlags    = fFlags;
+        pThis->pszName   = pszName;
+        Assert(g_pDarwinLockGroup);
+        pThis->pSpinLock = lck_spin_alloc_init(g_pDarwinLockGroup, LCK_ATTR_NULL);
+        if (pThis->pSpinLock)
+        {
+            *pSpinlock = pThis;
+            IPRT_DARWIN_RESTORE_EFL_AC();
+            return VINF_SUCCESS;
+        }
+
+        RTMemFree(pThis);
+    }
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return VERR_NO_MEMORY;
+}
+
+
+RTDECL(int)  RTSpinlockDestroy(RTSPINLOCK Spinlock)
+{
+    /*
+     * Validate input.
+     */
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
+    if (!pThis)
+        return VERR_INVALID_PARAMETER;
+    AssertMsgReturn(pThis->u32Magic == RTSPINLOCK_MAGIC,
+                    ("Invalid spinlock %p magic=%#x\n", pThis, pThis->u32Magic),
+                    VERR_INVALID_PARAMETER);
+
+    /*
+     * Make the lock invalid and release the memory.
+     */
+    ASMAtomicIncU32(&pThis->u32Magic);
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    Assert(g_pDarwinLockGroup);
+    lck_spin_free(pThis->pSpinLock, g_pDarwinLockGroup);
+    pThis->pSpinLock = NULL;
+
+    RTMemFree(pThis);
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(void) RTSpinlockAcquire(RTSPINLOCK Spinlock)
+{
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
+    AssertPtr(pThis);
+    Assert(pThis->u32Magic == RTSPINLOCK_MAGIC);
+
+    if (pThis->fFlags & RTSPINLOCK_FLAGS_INTERRUPT_SAFE)
+    {
+        uint32_t fIntSaved = ASMGetFlags();
+        ASMIntDisable();
+        lck_spin_lock(pThis->pSpinLock);
+        pThis->fIntSaved = fIntSaved;
+        IPRT_DARWIN_RESTORE_EFL_ONLY_AC_EX(fIntSaved);
+    }
+    else
+    {
+        IPRT_DARWIN_SAVE_EFL_AC();
+        lck_spin_lock(pThis->pSpinLock);
+        IPRT_DARWIN_RESTORE_EFL_ONLY_AC();
+    }
+}
+
+
+RTDECL(void) RTSpinlockRelease(RTSPINLOCK Spinlock)
+{
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
+    AssertPtr(pThis);
+    Assert(pThis->u32Magic == RTSPINLOCK_MAGIC);
+
+    if (pThis->fFlags & RTSPINLOCK_FLAGS_INTERRUPT_SAFE)
+    {
+        uint32_t fIntSaved = pThis->fIntSaved;
+        pThis->fIntSaved = 0;
+        lck_spin_unlock(pThis->pSpinLock);
+        ASMSetFlags(fIntSaved);
+    }
+    else
+    {
+        IPRT_DARWIN_SAVE_EFL_AC();
+        lck_spin_unlock(pThis->pSpinLock);
+        IPRT_DARWIN_RESTORE_EFL_ONLY_AC();
+    }
+}
+
diff --git a/src/VBox/Runtime/r0drv/darwin/the-darwin-kernel.h b/src/VBox/Runtime/r0drv/darwin/the-darwin-kernel.h
new file mode 100644
index 00000000..f0b03c24
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/the-darwin-kernel.h
@@ -0,0 +1,249 @@
+/* $Id: the-darwin-kernel.h $ */
+/** @file
+ * IPRT - Include all necessary headers for the Darwing kernel.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+#ifndef IPRT_INCLUDED_SRC_r0drv_darwin_the_darwin_kernel_h
+#define IPRT_INCLUDED_SRC_r0drv_darwin_the_darwin_kernel_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+/* Problematic header(s) containing conflicts with IPRT first. (FreeBSD has fixed these ages ago.) */
+#define __STDC_CONSTANT_MACROS
+#define __STDC_LIMIT_MACROS
+#include <sys/param.h>
+#include <mach/vm_param.h>
+#undef ALIGN
+#undef MIN
+#undef MAX
+#undef PAGE_SIZE
+#undef PAGE_SHIFT
+#undef PVM
+
+
+/* Include the IPRT definitions of the conflicting #defines & typedefs. */
+#include <iprt/cdefs.h>
+#include <iprt/types.h>
+#include <iprt/param.h>
+
+
+/* After including cdefs, we can check that this really is Darwin. */
+#ifndef RT_OS_DARWIN
+# error "RT_OS_DARWIN must be defined!"
+#endif
+
+#if defined(__clang__) || RT_GNUC_PREREQ(4, 4)
+# pragma GCC diagnostic push
+#endif
+#if defined(__clang__) || RT_GNUC_PREREQ(4, 2)
+# pragma GCC diagnostic ignored "-Wc++11-extensions"
+# pragma GCC diagnostic ignored "-Wc99-extensions"
+# pragma GCC diagnostic ignored "-Wextra-semi"
+# pragma GCC diagnostic ignored "-Wzero-length-array"
+# pragma GCC diagnostic ignored "-Wgnu-zero-variadic-macro-arguments"
+#endif
+
+/* now we're ready for including the rest of the Darwin headers. */
+#include <kern/thread.h>
+#include <kern/clock.h>
+#include <kern/sched_prim.h>
+#include <kern/locks.h>
+#if defined(RT_ARCH_X86) && MAC_OS_X_VERSION_MIN_REQUIRED < 1060
+# include <i386/mp_events.h>
+#endif
+#include <libkern/libkern.h>
+#include <libkern/sysctl.h>
+#include <libkern/version.h>
+#include <mach/thread_act.h>
+#include <mach/vm_map.h>
+#include <mach/vm_region.h>
+#include <pexpert/pexpert.h>
+#include <sys/conf.h>
+#include <sys/errno.h>
+#include <sys/ioccom.h>
+#include <sys/malloc.h>
+#include <sys/proc.h>
+#include <sys/vnode.h>
+#include <sys/fcntl.h>
+#include <IOKit/IOTypes.h>
+#include <IOKit/IOLib.h> /* Note! Has Assert down as a function. */
+#include <IOKit/IOMemoryDescriptor.h>
+#include <IOKit/IOBufferMemoryDescriptor.h>
+#include <IOKit/IOMapper.h>
+
+#if defined(__clang__) || RT_GNUC_PREREQ(4, 4)
+# pragma GCC diagnostic pop
+#endif
+
+
+/* See osfmk/kern/ast.h. */
+#ifndef AST_PREEMPT
+# define AST_PREEMPT    UINT32_C(1)
+# define AST_QUANTUM    UINT32_C(2)
+# define AST_URGENT     UINT32_C(4)
+#endif
+
+/* This flag was added in 10.6, it seems.  Should be harmless in earlier
+   releases... */
+#if __MAC_OS_X_VERSION_MAX_ALLOWED < 1060
+# define kIOMemoryMapperNone UINT32_C(0x800)
+#endif
+
+/* This flag was added in 10.8.2, it seems. */
+#if __MAC_OS_X_VERSION_MAX_ALLOWED < 1082
+# define kIOMemoryHostPhysicallyContiguous UINT32_C(0x00000080)
+#endif
+
+/** @name Macros for preserving EFLAGS.AC (despair / paranoid)
+ * @remarks Unlike linux, we have to restore it unconditionally on darwin.
+ * @{ */
+#include <iprt/asm-amd64-x86.h>
+#include <iprt/x86.h>
+#define IPRT_DARWIN_SAVE_EFL_AC()                       RTCCUINTREG const fSavedEfl = ASMGetFlags();
+#define IPRT_DARWIN_RESTORE_EFL_AC()                    ASMSetFlags(fSavedEfl)
+#define IPRT_DARWIN_RESTORE_EFL_ONLY_AC()               ASMChangeFlags(~X86_EFL_AC, fSavedEfl & X86_EFL_AC)
+#define IPRT_DARWIN_RESTORE_EFL_ONLY_AC_EX(a_fSavedEfl) ASMChangeFlags(~X86_EFL_AC, (a_fSavedEfl) & X86_EFL_AC)
+/** @} */
+
+
+RT_C_DECLS_BEGIN
+
+/* mach/vm_types.h */
+typedef struct pmap *pmap_t;
+
+/* vm/vm_kern.h */
+extern vm_map_t kernel_map;
+
+/* vm/pmap.h */
+extern pmap_t kernel_pmap;
+
+/* kern/task.h */
+extern vm_map_t get_task_map(task_t);
+
+/* osfmk/i386/pmap.h */
+extern ppnum_t pmap_find_phys(pmap_t, addr64_t);
+
+/* vm/vm_map.h */
+extern kern_return_t vm_map_wire(vm_map_t, vm_map_offset_t, vm_map_offset_t, vm_prot_t, boolean_t);
+extern kern_return_t vm_map_unwire(vm_map_t, vm_map_offset_t, vm_map_offset_t, boolean_t);
+
+/* mach/i386/thread_act.h */
+extern kern_return_t thread_terminate(thread_t);
+
+/* osfmk/i386/mp.h */
+extern void mp_rendezvous(void (*)(void *), void (*)(void *), void (*)(void *), void *);
+extern void mp_rendezvous_no_intrs(void (*)(void *), void *);
+
+/* osfmk/i386/cpu_data.h */
+struct my_cpu_data_x86
+{
+    struct my_cpu_data_x86 *cpu_this;
+    thread_t                cpu_active_thread;
+    void                   *cpu_int_state;
+    vm_offset_t             cpu_active_stack;
+    vm_offset_t             cpu_kernel_stack;
+    vm_offset_t             cpu_int_stack_top;
+    int                     cpu_preemption_level;
+    int                     cpu_simple_lock_count;
+    int                     cpu_interrupt_level;
+    int                     cpu_number;
+    int                     cpu_phys_number;
+    cpu_id_t                cpu_id;
+    int                     cpu_signals;
+    int                     cpu_mcount_off;
+    /*ast_t*/uint32_t       cpu_pending_ast;
+    int                     cpu_type;
+    int                     cpu_subtype;
+    int                     cpu_threadtype;
+    int                     cpu_running;
+};
+
+/* osfmk/i386/cpu_number.h */
+extern int cpu_number(void);
+
+/* osfmk/vm/vm_user.c */
+extern kern_return_t vm_protect(vm_map_t, vm_offset_t, vm_size_t, boolean_t, vm_prot_t);
+/*extern kern_return_t vm_region(vm_map_t, vm_address_t *, vm_size_t *, vm_region_flavor_t, vm_region_info_t,
+                               mach_msg_type_number_t *, mach_port_t *);*/
+
+/* i386/machine_routines.h */
+extern int ml_get_max_cpus(void);
+
+RT_C_DECLS_END
+
+
+/*
+ * Internals of the Darwin Ring-0 IPRT.
+ */
+RT_C_DECLS_BEGIN
+
+/* initterm-r0drv-darwin.cpp. */
+typedef uint32_t *  (*PFNR0DARWINASTPENDING)(void);
+typedef void        (*PFNR0DARWINCPUINTERRUPT)(int);
+extern lck_grp_t                  *g_pDarwinLockGroup;
+extern PFNR0DARWINASTPENDING       g_pfnR0DarwinAstPending;
+extern PFNR0DARWINCPUINTERRUPT     g_pfnR0DarwinCpuInterrupt;
+#ifdef DEBUG /* Used once for debugging memory issues (see #9466). */
+typedef kern_return_t (*PFNR0DARWINVMFAULTEXTERNAL)(vm_map_t, vm_map_offset_t, vm_prot_t, boolean_t, int, pmap_t, vm_map_offset_t);
+extern PFNR0DARWINVMFAULTEXTERNAL  g_pfnR0DarwinVmFaultExternal;
+#endif
+
+/* threadpreempt-r0drv-darwin.cpp */
+int  rtThreadPreemptDarwinInit(void);
+void rtThreadPreemptDarwinTerm(void);
+
+RT_C_DECLS_END
+
+
+/**
+ * Converts from nanoseconds to Darwin absolute time units.
+ * @returns Darwin absolute time.
+ * @param   u64Nano     Time interval in nanoseconds
+ */
+DECLINLINE(uint64_t) rtDarwinAbsTimeFromNano(const uint64_t u64Nano)
+{
+    uint64_t u64AbsTime;
+    nanoseconds_to_absolutetime(u64Nano, &u64AbsTime);
+    return u64AbsTime;
+}
+
+
+#include <iprt/err.h>
+
+/**
+ * Convert from mach kernel return code to IPRT status code.
+ * @todo put this where it belongs! (i.e. in a separate file and prototype in iprt/err.h)
+ */
+DECLINLINE(int) RTErrConvertFromMachKernReturn(kern_return_t rc)
+{
+    switch (rc)
+    {
+        case KERN_SUCCESS:      return VINF_SUCCESS;
+        default:                return VERR_GENERAL_FAILURE;
+    }
+}
+
+#endif /* !IPRT_INCLUDED_SRC_r0drv_darwin_the_darwin_kernel_h */
+
diff --git a/src/VBox/Runtime/r0drv/darwin/thread-r0drv-darwin.cpp b/src/VBox/Runtime/r0drv/darwin/thread-r0drv-darwin.cpp
new file mode 100644
index 00000000..c7545d15
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/thread-r0drv-darwin.cpp
@@ -0,0 +1,82 @@
+/* $Id: thread-r0drv-darwin.cpp $ */
+/** @file
+ * IPRT - Threads, Ring-0 Driver, Darwin.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-darwin-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/thread.h>
+
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+
+
+
+RTDECL(RTNATIVETHREAD) RTThreadNativeSelf(void)
+{
+    return (RTNATIVETHREAD)current_thread();
+}
+
+
+static int rtR0ThreadDarwinSleepCommon(RTMSINTERVAL cMillies)
+{
+    RT_ASSERT_PREEMPTIBLE();
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    uint64_t u64Deadline;
+    clock_interval_to_deadline(cMillies, kMillisecondScale, &u64Deadline);
+    clock_delay_until(u64Deadline);
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTThreadSleep(RTMSINTERVAL cMillies)
+{
+    return rtR0ThreadDarwinSleepCommon(cMillies);
+}
+
+
+RTDECL(int) RTThreadSleepNoLog(RTMSINTERVAL cMillies)
+{
+    return rtR0ThreadDarwinSleepCommon(cMillies);
+}
+
+
+RTDECL(bool) RTThreadYield(void)
+{
+    RT_ASSERT_PREEMPTIBLE();
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    thread_block(THREAD_CONTINUE_NULL);
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return true; /* this is fishy */
+}
+
diff --git a/src/VBox/Runtime/r0drv/darwin/thread2-r0drv-darwin.cpp b/src/VBox/Runtime/r0drv/darwin/thread2-r0drv-darwin.cpp
new file mode 100644
index 00000000..650bfd89
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/thread2-r0drv-darwin.cpp
@@ -0,0 +1,192 @@
+/* $Id: thread2-r0drv-darwin.cpp $ */
+/** @file
+ * IPRT - Threads (Part 2), Ring-0 Driver, Darwin.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-darwin-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/thread.h>
+
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+#include "internal/thread.h"
+
+
+DECLHIDDEN(int) rtThreadNativeInit(void)
+{
+    /* No TLS in Ring-0. :-/ */
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(RTTHREAD) RTThreadSelf(void)
+{
+    return rtThreadGetByNative((RTNATIVETHREAD)current_thread());
+}
+
+
+DECLHIDDEN(int) rtThreadNativeSetPriority(PRTTHREADINT pThread, RTTHREADTYPE enmType)
+{
+    /*
+     * Convert the priority type to scheduling policies.
+     * (This is really just guess work.)
+     */
+    bool                            fSetExtended = false;
+    thread_extended_policy          Extended = { true };
+    bool                            fSetTimeContstraint = false;
+    thread_time_constraint_policy   TimeConstraint = { 0, 0, 0, true };
+    thread_precedence_policy        Precedence = { 0 };
+    switch (enmType)
+    {
+        case RTTHREADTYPE_INFREQUENT_POLLER:
+            Precedence.importance = 1;
+            break;
+
+        case RTTHREADTYPE_EMULATION:
+            Precedence.importance = 30;
+            break;
+
+        case RTTHREADTYPE_DEFAULT:
+            Precedence.importance = 31;
+            break;
+
+        case RTTHREADTYPE_MSG_PUMP:
+            Precedence.importance = 34;
+            break;
+
+        case RTTHREADTYPE_IO:
+            Precedence.importance = 98;
+            break;
+
+        case RTTHREADTYPE_TIMER:
+            Precedence.importance = 0x7fffffff;
+
+            fSetExtended = true;
+            Extended.timeshare = FALSE;
+
+            fSetTimeContstraint = true;
+            TimeConstraint.period = 0; /* not really true for a real timer thread, but we've really no idea. */
+            TimeConstraint.computation = rtDarwinAbsTimeFromNano(100000); /* 100 us*/
+            TimeConstraint.constraint = rtDarwinAbsTimeFromNano(500000);  /* 500 us */
+            TimeConstraint.preemptible = FALSE;
+            break;
+
+        default:
+            AssertMsgFailed(("enmType=%d\n", enmType));
+            return VERR_INVALID_PARAMETER;
+    }
+    RT_ASSERT_INTS_ON();
+
+    /*
+     * Do the actual modification.
+     */
+    kern_return_t kr = thread_policy_set((thread_t)pThread->Core.Key, THREAD_PRECEDENCE_POLICY,
+                                         (thread_policy_t)&Precedence, THREAD_PRECEDENCE_POLICY_COUNT);
+    AssertMsg(kr == KERN_SUCCESS, ("%rc\n", kr)); NOREF(kr);
+
+    if (fSetExtended)
+    {
+        kr = thread_policy_set((thread_t)pThread->Core.Key, THREAD_EXTENDED_POLICY,
+                               (thread_policy_t)&Extended, THREAD_EXTENDED_POLICY_COUNT);
+        AssertMsg(kr == KERN_SUCCESS, ("%rc\n", kr));
+    }
+
+    if (fSetTimeContstraint)
+    {
+        kr = thread_policy_set((thread_t)pThread->Core.Key, THREAD_TIME_CONSTRAINT_POLICY,
+                               (thread_policy_t)&TimeConstraint, THREAD_TIME_CONSTRAINT_POLICY_COUNT);
+        AssertMsg(kr == KERN_SUCCESS, ("%rc\n", kr));
+    }
+
+    return VINF_SUCCESS; /* ignore any errors for now */
+}
+
+
+DECLHIDDEN(int) rtThreadNativeAdopt(PRTTHREADINT pThread)
+{
+    RT_NOREF(pThread);
+    return VERR_NOT_IMPLEMENTED;
+}
+
+
+DECLHIDDEN(void) rtThreadNativeWaitKludge(PRTTHREADINT pThread)
+{
+    RT_NOREF(pThread);
+    /** @todo fix RTThreadWait/RTR0Term race on darwin. */
+    RTThreadSleep(1);
+}
+
+
+DECLHIDDEN(void) rtThreadNativeDestroy(PRTTHREADINT pThread)
+{
+    RT_NOREF(pThread);
+}
+
+
+/**
+ * Native kernel thread wrapper function.
+ *
+ * This will forward to rtThreadMain and do termination upon return.
+ *
+ * @param pvArg         Pointer to the argument package.
+ * @param Ignored       Wait result, which we ignore.
+ */
+static void rtThreadNativeMain(void *pvArg, wait_result_t Ignored)
+{
+    RT_NOREF(Ignored);
+    const thread_t Self = current_thread();
+    PRTTHREADINT pThread = (PRTTHREADINT)pvArg;
+
+    rtThreadMain(pThread, (RTNATIVETHREAD)Self, &pThread->szName[0]);
+
+    kern_return_t kr = thread_terminate(Self);
+    AssertFatalMsgFailed(("kr=%d\n", kr));
+}
+
+
+DECLHIDDEN(int) rtThreadNativeCreate(PRTTHREADINT pThreadInt, PRTNATIVETHREAD pNativeThread)
+{
+    RT_ASSERT_PREEMPTIBLE();
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    thread_t NativeThread;
+    kern_return_t kr = kernel_thread_start(rtThreadNativeMain, pThreadInt, &NativeThread);
+    if (kr == KERN_SUCCESS)
+    {
+        *pNativeThread = (RTNATIVETHREAD)NativeThread;
+        thread_deallocate(NativeThread);
+        IPRT_DARWIN_RESTORE_EFL_AC();
+        return VINF_SUCCESS;
+    }
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return RTErrConvertFromMachKernReturn(kr);
+}
+
diff --git a/src/VBox/Runtime/r0drv/darwin/threadpreempt-r0drv-darwin.cpp b/src/VBox/Runtime/r0drv/darwin/threadpreempt-r0drv-darwin.cpp
new file mode 100644
index 00000000..0358e7de
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/threadpreempt-r0drv-darwin.cpp
@@ -0,0 +1,203 @@
+/* $Id: threadpreempt-r0drv-darwin.cpp $ */
+/** @file
+ * IPRT - Thread Preemption, Ring-0 Driver, Darwin.
+ */
+
+/*
+ * Copyright (C) 2009-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-darwin-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/thread.h>
+
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/assert.h>
+#include <iprt/cpuset.h>
+#include <iprt/errcore.h>
+#include <iprt/mp.h>
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+typedef struct RTDARWINPREEMPTHACK
+{
+    /** The spinlock we exploit for disabling preemption. */
+    lck_spin_t         *pSpinLock;
+    /** The preemption count for this CPU, to guard against nested calls. */
+    uint32_t            cRecursion;
+} RTDARWINPREEMPTHACK;
+typedef RTDARWINPREEMPTHACK *PRTDARWINPREEMPTHACK;
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+static RTDARWINPREEMPTHACK  g_aPreemptHacks[RTCPUSET_MAX_CPUS];
+
+
+/**
+ * Allocates the per-cpu spin locks used to disable preemption.
+ *
+ * Called by rtR0InitNative.
+ */
+int rtThreadPreemptDarwinInit(void)
+{
+    Assert(g_pDarwinLockGroup);
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    for (size_t i = 0; i < RT_ELEMENTS(g_aPreemptHacks); i++)
+    {
+        g_aPreemptHacks[i].pSpinLock = lck_spin_alloc_init(g_pDarwinLockGroup, LCK_ATTR_NULL);
+        if (!g_aPreemptHacks[i].pSpinLock)
+            return VERR_NO_MEMORY; /* (The caller will invoke rtThreadPreemptDarwinTerm) */
+    }
+    IPRT_DARWIN_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Frees the per-cpu spin locks used to disable preemption.
+ *
+ * Called by rtR0TermNative.
+ */
+void rtThreadPreemptDarwinTerm(void)
+{
+    IPRT_DARWIN_SAVE_EFL_AC();
+
+    for (size_t i = 0; i < RT_ELEMENTS(g_aPreemptHacks); i++)
+        if (g_aPreemptHacks[i].pSpinLock)
+        {
+            lck_spin_free(g_aPreemptHacks[i].pSpinLock, g_pDarwinLockGroup);
+            g_aPreemptHacks[i].pSpinLock = NULL;
+        }
+
+    IPRT_DARWIN_RESTORE_EFL_AC();
+}
+
+
+RTDECL(bool) RTThreadPreemptIsEnabled(RTTHREAD hThread)
+{
+    RT_NOREF(hThread);
+    Assert(hThread == NIL_RTTHREAD);
+    return preemption_enabled();
+}
+
+
+RTDECL(bool) RTThreadPreemptIsPending(RTTHREAD hThread)
+{
+    RT_NOREF(hThread);
+    if (!g_pfnR0DarwinAstPending)
+        return false;
+    uint32_t volatile *pfAstPending = g_pfnR0DarwinAstPending(); AssertPtr(pfAstPending);
+    uint32_t  const    fAstPending = *pfAstPending;
+
+    AssertMsg(!(fAstPending & UINT32_C(0xfffe0000)), ("%#x\n", fAstPending));
+    return (fAstPending & (AST_PREEMPT | AST_QUANTUM | AST_URGENT)) != 0;
+}
+
+
+RTDECL(bool) RTThreadPreemptIsPendingTrusty(void)
+{
+    /* yes, we think that RTThreadPreemptIsPending is reliable... */
+    return g_pfnR0DarwinAstPending != NULL;
+}
+
+
+RTDECL(bool) RTThreadPreemptIsPossible(void)
+{
+    /* yes, kernel preemption is possible. */
+    return true;
+}
+
+
+RTDECL(void) RTThreadPreemptDisable(PRTTHREADPREEMPTSTATE pState)
+{
+    AssertPtr(pState);
+    Assert(pState->u32Reserved == 0);
+    pState->u32Reserved = 42;
+
+    /*
+     * Disable to prevent preemption while we grab the per-cpu spin lock.
+     * Note! Only take the lock on the first call or we end up spinning for ever.
+     */
+    RTCCUINTREG fSavedFlags = ASMIntDisableFlags();
+    RTCPUID     idCpu       = RTMpCpuId();
+    if (RT_UNLIKELY(idCpu < RT_ELEMENTS(g_aPreemptHacks)))
+    {
+        Assert(g_aPreemptHacks[idCpu].cRecursion < UINT32_MAX / 2);
+        if (++g_aPreemptHacks[idCpu].cRecursion == 1)
+        {
+            lck_spin_t *pSpinLock = g_aPreemptHacks[idCpu].pSpinLock;
+            if (pSpinLock)
+                lck_spin_lock(pSpinLock);
+            else
+                AssertFailed();
+        }
+    }
+    ASMSetFlags(fSavedFlags);
+    Assert(!RTThreadPreemptIsEnabled(NIL_RTTHREAD));
+    RT_ASSERT_PREEMPT_CPUID_DISABLE(pState);
+}
+
+
+RTDECL(void) RTThreadPreemptRestore(PRTTHREADPREEMPTSTATE pState)
+{
+    AssertPtr(pState);
+    Assert(pState->u32Reserved == 42);
+    pState->u32Reserved = 0;
+    RT_ASSERT_PREEMPT_CPUID_RESTORE(pState);
+
+    RTCPUID idCpu = RTMpCpuId();
+    if (RT_UNLIKELY(idCpu < RT_ELEMENTS(g_aPreemptHacks)))
+    {
+        Assert(g_aPreemptHacks[idCpu].cRecursion > 0);
+        if (--g_aPreemptHacks[idCpu].cRecursion == 0)
+        {
+            lck_spin_t *pSpinLock = g_aPreemptHacks[idCpu].pSpinLock;
+            if (pSpinLock)
+            {
+                IPRT_DARWIN_SAVE_EFL_AC();
+                lck_spin_unlock(pSpinLock);
+                IPRT_DARWIN_RESTORE_EFL_AC();
+            }
+            else
+                AssertFailed();
+        }
+    }
+}
+
+
+RTDECL(bool) RTThreadIsInInterrupt(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD); NOREF(hThread);
+    /** @todo Darwin: Implement RTThreadIsInInterrupt. Required for guest
+     *        additions! */
+    return !ASMIntAreEnabled();
+}
+
diff --git a/src/VBox/Runtime/r0drv/darwin/time-r0drv-darwin.cpp b/src/VBox/Runtime/r0drv/darwin/time-r0drv-darwin.cpp
new file mode 100644
index 00000000..28c6b3a8
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/darwin/time-r0drv-darwin.cpp
@@ -0,0 +1,98 @@
+/* $Id: time-r0drv-darwin.cpp $ */
+/** @file
+ * IPRT - Time, Ring-0 Driver, Darwin.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define LOG_GROUP RTLOGGROUP_TIME
+#include "the-darwin-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/time.h>
+
+#include <iprt/asm.h>
+
+
+DECLINLINE(uint64_t) rtTimeGetSystemNanoTS(void)
+{
+    static int8_t s_fSimple = -1;
+
+    /* first call: check if life is simple or not. */
+    if (s_fSimple < 0)
+    {
+        struct mach_timebase_info Info;
+        clock_timebase_info(&Info);
+        ASMAtomicXchgS8((int8_t * volatile)&s_fSimple, Info.denom == 1 && Info.numer == 1);
+    }
+
+    /* special case: absolute time is in nanoseconds */
+    if (s_fSimple)
+        return mach_absolute_time();
+
+    /* general case: let mach do the mult/div for us. */
+    uint64_t u64;
+    absolutetime_to_nanoseconds(mach_absolute_time(), &u64);
+    return u64;
+}
+
+
+RTDECL(uint64_t) RTTimeNanoTS(void)
+{
+    return rtTimeGetSystemNanoTS();
+}
+
+
+RTDECL(uint64_t) RTTimeMilliTS(void)
+{
+    return rtTimeGetSystemNanoTS() / RT_NS_1MS;
+}
+
+
+RTDECL(uint64_t) RTTimeSystemNanoTS(void)
+{
+    return rtTimeGetSystemNanoTS();
+}
+
+
+RTDECL(uint64_t) RTTimeSystemMilliTS(void)
+{
+    return rtTimeGetSystemNanoTS() / RT_NS_1MS;
+}
+
+
+RTDECL(PRTTIMESPEC) RTTimeNow(PRTTIMESPEC pTime)
+{
+#if MAC_OS_X_VERSION_MIN_REQUIRED < 1060
+    uint32_t        uSecs;
+    uint32_t        uNanosecs;
+#else
+    clock_sec_t     uSecs;
+    clock_nsec_t    uNanosecs;
+#endif
+    clock_get_calendar_nanotime(&uSecs, &uNanosecs);
+    return RTTimeSpecSetNano(pTime, (uint64_t)uSecs * RT_NS_1SEC + uNanosecs);
+}
+
diff --git a/src/VBox/Runtime/r0drv/freebsd/Makefile.kup b/src/VBox/Runtime/r0drv/freebsd/Makefile.kup
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/freebsd/Makefile.kup
diff --git a/src/VBox/Runtime/r0drv/freebsd/alloc-r0drv-freebsd.c b/src/VBox/Runtime/r0drv/freebsd/alloc-r0drv-freebsd.c
new file mode 100644
index 00000000..1e904202
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/freebsd/alloc-r0drv-freebsd.c
@@ -0,0 +1,209 @@
+/* $Id: alloc-r0drv-freebsd.c $ */
+/** @file
+ * IPRT - Memory Allocation, Ring-0 Driver, FreeBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-freebsd-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/mem.h>
+
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/param.h>
+
+#include "r0drv/alloc-r0drv.h"
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/* These two statements will define two globals and add initializers
+   and destructors that will be called at load/unload time (I think). */
+MALLOC_DEFINE(M_IPRTHEAP, "iprtheap", "IPRT - heap");
+MALLOC_DEFINE(M_IPRTCONT, "iprtcont", "IPRT - contiguous");
+
+
+DECLHIDDEN(int) rtR0MemAllocEx(size_t cb, uint32_t fFlags, PRTMEMHDR *ppHdr)
+{
+    size_t      cbAllocated = cb;
+    PRTMEMHDR   pHdr        = NULL;
+
+#ifdef RT_ARCH_AMD64
+    /*
+     * Things are a bit more complicated on AMD64 for executable memory
+     * because we need to be in the ~2GB..~0 range for code.
+     */
+    if (fFlags & RTMEMHDR_FLAG_EXEC)
+    {
+        if (fFlags & RTMEMHDR_FLAG_ANY_CTX)
+            return VERR_NOT_SUPPORTED;
+
+# ifdef USE_KMEM_ALLOC_PROT
+        pHdr = (PRTMEMHDR)kmem_alloc_prot(kernel_map, cb + sizeof(*pHdr),
+                                          VM_PROT_ALL, VM_PROT_ALL, KERNBASE);
+# else
+        vm_object_t pVmObject = NULL;
+        vm_offset_t Addr = KERNBASE;
+        cbAllocated = RT_ALIGN_Z(cb + sizeof(*pHdr), PAGE_SIZE);
+
+        pVmObject = vm_object_allocate(OBJT_DEFAULT, cbAllocated >> PAGE_SHIFT);
+        if (!pVmObject)
+            return VERR_NO_EXEC_MEMORY;
+
+        /* Addr contains a start address vm_map_find will start searching for suitable space at. */
+#if __FreeBSD_version >= 1000055
+        int rc = vm_map_find(kernel_map, pVmObject, 0, &Addr,
+                             cbAllocated, 0, VMFS_ANY_SPACE, VM_PROT_ALL, VM_PROT_ALL, 0);
+#else
+        int rc = vm_map_find(kernel_map, pVmObject, 0, &Addr,
+                             cbAllocated, TRUE, VM_PROT_ALL, VM_PROT_ALL, 0);
+#endif
+        if (rc == KERN_SUCCESS)
+        {
+            rc = vm_map_wire(kernel_map, Addr, Addr + cbAllocated,
+                             VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
+            if (rc == KERN_SUCCESS)
+            {
+                pHdr = (PRTMEMHDR)Addr;
+
+                if (fFlags & RTMEMHDR_FLAG_ZEROED)
+                    bzero(pHdr, cbAllocated);
+            }
+            else
+                vm_map_remove(kernel_map,
+                              Addr,
+                              Addr + cbAllocated);
+        }
+        else
+            vm_object_deallocate(pVmObject);
+# endif
+    }
+    else
+#endif
+    {
+        pHdr = (PRTMEMHDR)malloc(cb + sizeof(RTMEMHDR), M_IPRTHEAP,
+                                 fFlags & RTMEMHDR_FLAG_ZEROED ? M_NOWAIT | M_ZERO : M_NOWAIT);
+    }
+
+    if (RT_UNLIKELY(!pHdr))
+        return VERR_NO_MEMORY;
+
+    pHdr->u32Magic   = RTMEMHDR_MAGIC;
+    pHdr->fFlags     = fFlags;
+    pHdr->cb         = cbAllocated;
+    pHdr->cbReq      = cb;
+
+    *ppHdr = pHdr;
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(void) rtR0MemFree(PRTMEMHDR pHdr)
+{
+    pHdr->u32Magic += 1;
+
+#ifdef RT_ARCH_AMD64
+    if (pHdr->fFlags & RTMEMHDR_FLAG_EXEC)
+# ifdef USE_KMEM_ALLOC_PROT
+        kmem_free(kernel_map, (vm_offset_t)pHdr, pHdr->cb);
+# else
+        vm_map_remove(kernel_map, (vm_offset_t)pHdr, ((vm_offset_t)pHdr) + pHdr->cb);
+# endif
+    else
+#endif
+        free(pHdr, M_IPRTHEAP);
+}
+
+
+RTR0DECL(void *) RTMemContAlloc(PRTCCPHYS pPhys, size_t cb)
+{
+    void *pv;
+
+    /*
+     * Validate input.
+     */
+    AssertPtr(pPhys);
+    Assert(cb > 0);
+
+    /*
+     * This API works in pages, so no need to do any size aligning.
+     */
+    pv = contigmalloc(cb,                   /* size */
+                      M_IPRTCONT,           /* type */
+                      M_NOWAIT | M_ZERO,    /* flags */
+                      0,                    /* lowest physical address*/
+                      _4G-1,                /* highest physical address */
+                      PAGE_SIZE,            /* alignment. */
+                      0);                   /* boundary */
+    if (pv)
+    {
+        Assert(!((uintptr_t)pv & PAGE_OFFSET_MASK));
+        *pPhys = vtophys(pv);
+        Assert(!(*pPhys & PAGE_OFFSET_MASK));
+    }
+    return pv;
+}
+
+
+RTR0DECL(void) RTMemContFree(void *pv, size_t cb)
+{
+    if (pv)
+    {
+        AssertMsg(!((uintptr_t)pv & PAGE_OFFSET_MASK), ("pv=%p\n", pv));
+        contigfree(pv, cb, M_IPRTCONT);
+    }
+}
+
diff --git a/src/VBox/Runtime/r0drv/freebsd/assert-r0drv-freebsd.c b/src/VBox/Runtime/r0drv/freebsd/assert-r0drv-freebsd.c
new file mode 100644
index 00000000..d4d17d8c
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/freebsd/assert-r0drv-freebsd.c
@@ -0,0 +1,94 @@
+/* $Id: assert-r0drv-freebsd.c $ */
+/** @file
+ * IPRT - Assertion Workers, Ring-0 Drivers, FreeBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-freebsd-kernel.h"
+
+#include <iprt/assert.h>
+#include <iprt/log.h>
+#include <iprt/string.h>
+#include <iprt/stdarg.h>
+
+#include "internal/assert.h"
+
+
+DECLHIDDEN(void) rtR0AssertNativeMsg1(const char *pszExpr, unsigned uLine, const char *pszFile, const char *pszFunction)
+{
+    printf("\r\n!!Assertion Failed!!\r\n"
+           "Expression: %s\r\n"
+           "Location  : %s(%d) %s\r\n",
+           pszExpr, pszFile, uLine, pszFunction);
+}
+
+
+DECLHIDDEN(void) rtR0AssertNativeMsg2V(bool fInitial, const char *pszFormat, va_list va)
+{
+    char szMsg[256];
+
+    RTStrPrintfV(szMsg, sizeof(szMsg) - 1, pszFormat, va);
+    szMsg[sizeof(szMsg) - 1] = '\0';
+    printf("%s", szMsg);
+
+    NOREF(fInitial);
+}
+
+
+RTR0DECL(void) RTR0AssertPanicSystem(void)
+{
+    /** @todo implement RTR0AssertPanicSystem. */
+}
+
diff --git a/src/VBox/Runtime/r0drv/freebsd/initterm-r0drv-freebsd.c b/src/VBox/Runtime/r0drv/freebsd/initterm-r0drv-freebsd.c
new file mode 100644
index 00000000..40f7aac6
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/freebsd/initterm-r0drv-freebsd.c
@@ -0,0 +1,77 @@
+/* $Id: initterm-r0drv-freebsd.c $ */
+/** @file
+ * IPRT - Initialization & Termination, Ring-0 Driver, FreeBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-freebsd-kernel.h"
+
+#include <iprt/errcore.h>
+
+#include "internal/initterm.h"
+
+
+DECLHIDDEN(int) rtR0InitNative(void)
+{
+    /* nothing to do */
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(void) rtR0TermNative(void)
+{
+    /* nothing to undo */
+}
+
diff --git a/src/VBox/Runtime/r0drv/freebsd/memobj-r0drv-freebsd.c b/src/VBox/Runtime/r0drv/freebsd/memobj-r0drv-freebsd.c
new file mode 100644
index 00000000..0971624e
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/freebsd/memobj-r0drv-freebsd.c
@@ -0,0 +1,892 @@
+/* $Id: memobj-r0drv-freebsd.c $ */
+/** @file
+ * IPRT - Ring-0 Memory Objects, FreeBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen, Andriy Gapon.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ * Copyright (c) 2011 Andriy Gapon <avg@FreeBSD.org>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-freebsd-kernel.h"
+
+#include <iprt/memobj.h>
+#include <iprt/mem.h>
+#include <iprt/err.h>
+#include <iprt/assert.h>
+#include <iprt/log.h>
+#include <iprt/param.h>
+#include <iprt/process.h>
+#include "internal/memobj.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * The FreeBSD version of the memory object structure.
+ */
+typedef struct RTR0MEMOBJFREEBSD
+{
+    /** The core structure. */
+    RTR0MEMOBJINTERNAL  Core;
+    /** The VM object associated with the allocation. */
+    vm_object_t         pObject;
+} RTR0MEMOBJFREEBSD, *PRTR0MEMOBJFREEBSD;
+
+
+MALLOC_DEFINE(M_IPRTMOBJ, "iprtmobj", "IPRT - R0MemObj");
+
+
+/**
+ * Gets the virtual memory map the specified object is mapped into.
+ *
+ * @returns VM map handle on success, NULL if no map.
+ * @param   pMem                The memory object.
+ */
+static vm_map_t rtR0MemObjFreeBSDGetMap(PRTR0MEMOBJINTERNAL pMem)
+{
+    switch (pMem->enmType)
+    {
+        case RTR0MEMOBJTYPE_PAGE:
+        case RTR0MEMOBJTYPE_LOW:
+        case RTR0MEMOBJTYPE_CONT:
+            return kernel_map;
+
+        case RTR0MEMOBJTYPE_PHYS:
+        case RTR0MEMOBJTYPE_PHYS_NC:
+            return NULL; /* pretend these have no mapping atm. */
+
+        case RTR0MEMOBJTYPE_LOCK:
+            return pMem->u.Lock.R0Process == NIL_RTR0PROCESS
+                ? kernel_map
+                : &((struct proc *)pMem->u.Lock.R0Process)->p_vmspace->vm_map;
+
+        case RTR0MEMOBJTYPE_RES_VIRT:
+            return pMem->u.ResVirt.R0Process == NIL_RTR0PROCESS
+                ? kernel_map
+                : &((struct proc *)pMem->u.ResVirt.R0Process)->p_vmspace->vm_map;
+
+        case RTR0MEMOBJTYPE_MAPPING:
+            return pMem->u.Mapping.R0Process == NIL_RTR0PROCESS
+                ? kernel_map
+                : &((struct proc *)pMem->u.Mapping.R0Process)->p_vmspace->vm_map;
+
+        default:
+            return NULL;
+    }
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeFree(RTR0MEMOBJ pMem)
+{
+    PRTR0MEMOBJFREEBSD pMemFreeBSD = (PRTR0MEMOBJFREEBSD)pMem;
+    int rc;
+
+    switch (pMemFreeBSD->Core.enmType)
+    {
+        case RTR0MEMOBJTYPE_PAGE:
+        case RTR0MEMOBJTYPE_LOW:
+        case RTR0MEMOBJTYPE_CONT:
+            rc = vm_map_remove(kernel_map,
+                                (vm_offset_t)pMemFreeBSD->Core.pv,
+                                (vm_offset_t)pMemFreeBSD->Core.pv + pMemFreeBSD->Core.cb);
+            AssertMsg(rc == KERN_SUCCESS, ("%#x", rc));
+            break;
+
+        case RTR0MEMOBJTYPE_LOCK:
+        {
+            vm_map_t pMap = kernel_map;
+
+            if (pMemFreeBSD->Core.u.Lock.R0Process != NIL_RTR0PROCESS)
+                pMap = &((struct proc *)pMemFreeBSD->Core.u.Lock.R0Process)->p_vmspace->vm_map;
+
+            rc = vm_map_unwire(pMap,
+                               (vm_offset_t)pMemFreeBSD->Core.pv,
+                               (vm_offset_t)pMemFreeBSD->Core.pv + pMemFreeBSD->Core.cb,
+                               VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
+            AssertMsg(rc == KERN_SUCCESS, ("%#x", rc));
+            break;
+        }
+
+        case RTR0MEMOBJTYPE_RES_VIRT:
+        {
+            vm_map_t pMap = kernel_map;
+            if (pMemFreeBSD->Core.u.ResVirt.R0Process != NIL_RTR0PROCESS)
+                pMap = &((struct proc *)pMemFreeBSD->Core.u.ResVirt.R0Process)->p_vmspace->vm_map;
+            rc = vm_map_remove(pMap,
+                               (vm_offset_t)pMemFreeBSD->Core.pv,
+                               (vm_offset_t)pMemFreeBSD->Core.pv + pMemFreeBSD->Core.cb);
+            AssertMsg(rc == KERN_SUCCESS, ("%#x", rc));
+            break;
+        }
+
+        case RTR0MEMOBJTYPE_MAPPING:
+        {
+            vm_map_t pMap = kernel_map;
+
+            if (pMemFreeBSD->Core.u.Mapping.R0Process != NIL_RTR0PROCESS)
+                pMap = &((struct proc *)pMemFreeBSD->Core.u.Mapping.R0Process)->p_vmspace->vm_map;
+            rc = vm_map_remove(pMap,
+                               (vm_offset_t)pMemFreeBSD->Core.pv,
+                               (vm_offset_t)pMemFreeBSD->Core.pv + pMemFreeBSD->Core.cb);
+            AssertMsg(rc == KERN_SUCCESS, ("%#x", rc));
+            break;
+        }
+
+        case RTR0MEMOBJTYPE_PHYS:
+        case RTR0MEMOBJTYPE_PHYS_NC:
+        {
+            VM_OBJECT_WLOCK(pMemFreeBSD->pObject);
+            vm_page_t pPage = vm_page_find_least(pMemFreeBSD->pObject, 0);
+#if __FreeBSD_version < 1000000
+            vm_page_lock_queues();
+#endif
+            for (vm_page_t pPage = vm_page_find_least(pMemFreeBSD->pObject, 0);
+                 pPage != NULL;
+                 pPage = vm_page_next(pPage))
+            {
+                vm_page_unwire(pPage, 0);
+            }
+#if __FreeBSD_version < 1000000
+            vm_page_unlock_queues();
+#endif
+            VM_OBJECT_WUNLOCK(pMemFreeBSD->pObject);
+            vm_object_deallocate(pMemFreeBSD->pObject);
+            break;
+        }
+
+        default:
+            AssertMsgFailed(("enmType=%d\n", pMemFreeBSD->Core.enmType));
+            return VERR_INTERNAL_ERROR;
+    }
+
+    return VINF_SUCCESS;
+}
+
+
+static vm_page_t rtR0MemObjFreeBSDContigPhysAllocHelper(vm_object_t pObject, vm_pindex_t iPIndex,
+                                                        u_long cPages, vm_paddr_t VmPhysAddrHigh,
+                                                        u_long uAlignment, bool fWire)
+{
+    vm_page_t pPages;
+    int cTries = 0;
+
+#if __FreeBSD_version > 1000000
+    int fFlags = VM_ALLOC_INTERRUPT | VM_ALLOC_NOBUSY;
+    if (fWire)
+        fFlags |= VM_ALLOC_WIRED;
+
+    while (cTries <= 1)
+    {
+        VM_OBJECT_WLOCK(pObject);
+        pPages = vm_page_alloc_contig(pObject, iPIndex, fFlags, cPages, 0,
+                                      VmPhysAddrHigh, uAlignment, 0, VM_MEMATTR_DEFAULT);
+        VM_OBJECT_WUNLOCK(pObject);
+        if (pPages)
+            break;
+#if __FreeBSD_version >= 1100092
+        if (!vm_page_reclaim_contig(cTries, cPages, 0, VmPhysAddrHigh, PAGE_SIZE, 0))
+            break;
+#else
+        vm_pageout_grow_cache(cTries, 0, VmPhysAddrHigh);
+#endif
+        cTries++;
+    }
+
+    return pPages;
+#else
+    while (cTries <= 1)
+    {
+        pPages = vm_phys_alloc_contig(cPages, 0, VmPhysAddrHigh, uAlignment, 0);
+        if (pPages)
+            break;
+        vm_contig_grow_cache(cTries, 0, VmPhysAddrHigh);
+        cTries++;
+    }
+
+    if (!pPages)
+        return pPages;
+    VM_OBJECT_WLOCK(pObject);
+    for (vm_pindex_t iPage = 0; iPage < cPages; iPage++)
+    {
+        vm_page_t pPage = pPages + iPage;
+        vm_page_insert(pPage, pObject, iPIndex + iPage);
+        pPage->valid = VM_PAGE_BITS_ALL;
+        if (fWire)
+        {
+            pPage->wire_count = 1;
+            atomic_add_int(&cnt.v_wire_count, 1);
+        }
+    }
+    VM_OBJECT_WUNLOCK(pObject);
+    return pPages;
+#endif
+}
+
+static int rtR0MemObjFreeBSDPhysAllocHelper(vm_object_t pObject, u_long cPages,
+                                            vm_paddr_t VmPhysAddrHigh, u_long uAlignment,
+                                            bool fContiguous, bool fWire, int rcNoMem)
+{
+    if (fContiguous)
+    {
+        if (rtR0MemObjFreeBSDContigPhysAllocHelper(pObject, 0, cPages, VmPhysAddrHigh,
+                                                   uAlignment, fWire) != NULL)
+            return VINF_SUCCESS;
+        return rcNoMem;
+    }
+
+    for (vm_pindex_t iPage = 0; iPage < cPages; iPage++)
+    {
+        vm_page_t pPage = rtR0MemObjFreeBSDContigPhysAllocHelper(pObject, iPage, 1, VmPhysAddrHigh,
+                                                                 uAlignment, fWire);
+        if (!pPage)
+        {
+            /* Free all allocated pages */
+            VM_OBJECT_WLOCK(pObject);
+            while (iPage-- > 0)
+            {
+                pPage = vm_page_lookup(pObject, iPage);
+#if __FreeBSD_version < 1000000
+                vm_page_lock_queues();
+#endif
+                if (fWire)
+                    vm_page_unwire(pPage, 0);
+                vm_page_free(pPage);
+#if __FreeBSD_version < 1000000
+                vm_page_unlock_queues();
+#endif
+            }
+            VM_OBJECT_WUNLOCK(pObject);
+            return rcNoMem;
+        }
+    }
+    return VINF_SUCCESS;
+}
+
+static int rtR0MemObjFreeBSDAllocHelper(PRTR0MEMOBJFREEBSD pMemFreeBSD, bool fExecutable,
+                                        vm_paddr_t VmPhysAddrHigh, bool fContiguous, int rcNoMem)
+{
+    vm_offset_t MapAddress = vm_map_min(kernel_map);
+    size_t      cPages = atop(pMemFreeBSD->Core.cb);
+    int         rc;
+
+    pMemFreeBSD->pObject = vm_object_allocate(OBJT_PHYS, cPages);
+
+    /* No additional object reference for auto-deallocation upon unmapping. */
+#if __FreeBSD_version >= 1000055
+    rc = vm_map_find(kernel_map, pMemFreeBSD->pObject, 0,
+                     &MapAddress, pMemFreeBSD->Core.cb, 0, VMFS_ANY_SPACE,
+                     fExecutable ? VM_PROT_ALL : VM_PROT_RW, VM_PROT_ALL, 0);
+#else
+    rc = vm_map_find(kernel_map, pMemFreeBSD->pObject, 0,
+                     &MapAddress, pMemFreeBSD->Core.cb, VMFS_ANY_SPACE,
+                     fExecutable ? VM_PROT_ALL : VM_PROT_RW, VM_PROT_ALL, 0);
+#endif
+
+    if (rc == KERN_SUCCESS)
+    {
+        rc = rtR0MemObjFreeBSDPhysAllocHelper(pMemFreeBSD->pObject, cPages,
+                                              VmPhysAddrHigh, PAGE_SIZE, fContiguous,
+                                              false, rcNoMem);
+        if (RT_SUCCESS(rc))
+        {
+            vm_map_wire(kernel_map, MapAddress, MapAddress + pMemFreeBSD->Core.cb,
+                        VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
+
+            /* Store start address */
+            pMemFreeBSD->Core.pv = (void *)MapAddress;
+            return VINF_SUCCESS;
+        }
+
+        vm_map_remove(kernel_map, MapAddress, MapAddress + pMemFreeBSD->Core.cb);
+    }
+    else
+    {
+        rc = rcNoMem; /** @todo fix translation (borrow from darwin) */
+        vm_object_deallocate(pMemFreeBSD->pObject);
+    }
+
+    rtR0MemObjDelete(&pMemFreeBSD->Core);
+    return rc;
+}
+DECLHIDDEN(int) rtR0MemObjNativeAllocPage(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    PRTR0MEMOBJFREEBSD pMemFreeBSD = (PRTR0MEMOBJFREEBSD)rtR0MemObjNew(sizeof(*pMemFreeBSD),
+                                                                       RTR0MEMOBJTYPE_PAGE, NULL, cb);
+    if (!pMemFreeBSD)
+        return VERR_NO_MEMORY;
+
+    int rc = rtR0MemObjFreeBSDAllocHelper(pMemFreeBSD, fExecutable, ~(vm_paddr_t)0, false, VERR_NO_MEMORY);
+    if (RT_FAILURE(rc))
+    {
+        rtR0MemObjDelete(&pMemFreeBSD->Core);
+        return rc;
+    }
+
+    *ppMem = &pMemFreeBSD->Core;
+    return rc;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocLow(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    PRTR0MEMOBJFREEBSD pMemFreeBSD = (PRTR0MEMOBJFREEBSD)rtR0MemObjNew(sizeof(*pMemFreeBSD),
+                                                                       RTR0MEMOBJTYPE_LOW, NULL, cb);
+    if (!pMemFreeBSD)
+        return VERR_NO_MEMORY;
+
+    int rc = rtR0MemObjFreeBSDAllocHelper(pMemFreeBSD, fExecutable, _4G - 1, false, VERR_NO_LOW_MEMORY);
+    if (RT_FAILURE(rc))
+    {
+        rtR0MemObjDelete(&pMemFreeBSD->Core);
+        return rc;
+    }
+
+    *ppMem = &pMemFreeBSD->Core;
+    return rc;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocCont(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    PRTR0MEMOBJFREEBSD pMemFreeBSD = (PRTR0MEMOBJFREEBSD)rtR0MemObjNew(sizeof(*pMemFreeBSD),
+                                                                       RTR0MEMOBJTYPE_CONT, NULL, cb);
+    if (!pMemFreeBSD)
+        return VERR_NO_MEMORY;
+
+    int rc = rtR0MemObjFreeBSDAllocHelper(pMemFreeBSD, fExecutable, _4G - 1, true, VERR_NO_CONT_MEMORY);
+    if (RT_FAILURE(rc))
+    {
+        rtR0MemObjDelete(&pMemFreeBSD->Core);
+        return rc;
+    }
+
+    pMemFreeBSD->Core.u.Cont.Phys = vtophys(pMemFreeBSD->Core.pv);
+    *ppMem = &pMemFreeBSD->Core;
+    return rc;
+}
+
+
+static int rtR0MemObjFreeBSDAllocPhysPages(PPRTR0MEMOBJINTERNAL ppMem, RTR0MEMOBJTYPE enmType,
+                                           size_t cb,
+                                           RTHCPHYS PhysHighest, size_t uAlignment,
+                                           bool fContiguous, int rcNoMem)
+{
+    uint32_t   cPages = atop(cb);
+    vm_paddr_t VmPhysAddrHigh;
+
+    /* create the object. */
+    PRTR0MEMOBJFREEBSD pMemFreeBSD = (PRTR0MEMOBJFREEBSD)rtR0MemObjNew(sizeof(*pMemFreeBSD),
+                                                                       enmType, NULL, cb);
+    if (!pMemFreeBSD)
+        return VERR_NO_MEMORY;
+
+    pMemFreeBSD->pObject = vm_object_allocate(OBJT_PHYS, atop(cb));
+
+    if (PhysHighest != NIL_RTHCPHYS)
+        VmPhysAddrHigh = PhysHighest;
+    else
+        VmPhysAddrHigh = ~(vm_paddr_t)0;
+
+    int rc = rtR0MemObjFreeBSDPhysAllocHelper(pMemFreeBSD->pObject, cPages, VmPhysAddrHigh,
+                                              uAlignment, fContiguous, true, rcNoMem);
+    if (RT_SUCCESS(rc))
+    {
+        if (fContiguous)
+        {
+            Assert(enmType == RTR0MEMOBJTYPE_PHYS);
+            VM_OBJECT_WLOCK(pMemFreeBSD->pObject);
+            pMemFreeBSD->Core.u.Phys.PhysBase = VM_PAGE_TO_PHYS(vm_page_find_least(pMemFreeBSD->pObject, 0));
+            VM_OBJECT_WUNLOCK(pMemFreeBSD->pObject);
+            pMemFreeBSD->Core.u.Phys.fAllocated = true;
+        }
+
+        *ppMem = &pMemFreeBSD->Core;
+    }
+    else
+    {
+        vm_object_deallocate(pMemFreeBSD->pObject);
+        rtR0MemObjDelete(&pMemFreeBSD->Core);
+    }
+
+    return rc;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocPhys(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, RTHCPHYS PhysHighest, size_t uAlignment)
+{
+    return rtR0MemObjFreeBSDAllocPhysPages(ppMem, RTR0MEMOBJTYPE_PHYS, cb, PhysHighest, uAlignment, true, VERR_NO_MEMORY);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocPhysNC(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, RTHCPHYS PhysHighest)
+{
+    return rtR0MemObjFreeBSDAllocPhysPages(ppMem, RTR0MEMOBJTYPE_PHYS_NC, cb, PhysHighest, PAGE_SIZE, false, VERR_NO_PHYS_MEMORY);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeEnterPhys(PPRTR0MEMOBJINTERNAL ppMem, RTHCPHYS Phys, size_t cb, uint32_t uCachePolicy)
+{
+    AssertReturn(uCachePolicy == RTMEM_CACHE_POLICY_DONT_CARE, VERR_NOT_SUPPORTED);
+
+    /* create the object. */
+    PRTR0MEMOBJFREEBSD pMemFreeBSD = (PRTR0MEMOBJFREEBSD)rtR0MemObjNew(sizeof(*pMemFreeBSD), RTR0MEMOBJTYPE_PHYS, NULL, cb);
+    if (!pMemFreeBSD)
+        return VERR_NO_MEMORY;
+
+    /* there is no allocation here, it needs to be mapped somewhere first. */
+    pMemFreeBSD->Core.u.Phys.fAllocated = false;
+    pMemFreeBSD->Core.u.Phys.PhysBase = Phys;
+    pMemFreeBSD->Core.u.Phys.uCachePolicy = uCachePolicy;
+    *ppMem = &pMemFreeBSD->Core;
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Worker locking the memory in either kernel or user maps.
+ */
+static int rtR0MemObjNativeLockInMap(PPRTR0MEMOBJINTERNAL ppMem, vm_map_t pVmMap,
+                                     vm_offset_t AddrStart, size_t cb, uint32_t fAccess,
+                                     RTR0PROCESS R0Process, int fFlags)
+{
+    int rc;
+    NOREF(fAccess);
+
+    /* create the object. */
+    PRTR0MEMOBJFREEBSD pMemFreeBSD = (PRTR0MEMOBJFREEBSD)rtR0MemObjNew(sizeof(*pMemFreeBSD), RTR0MEMOBJTYPE_LOCK, (void *)AddrStart, cb);
+    if (!pMemFreeBSD)
+        return VERR_NO_MEMORY;
+
+    /*
+     * We could've used vslock here, but we don't wish to be subject to
+     * resource usage restrictions, so we'll call vm_map_wire directly.
+     */
+    rc = vm_map_wire(pVmMap,                                         /* the map */
+                     AddrStart,                                      /* start */
+                     AddrStart + cb,                                 /* end */
+                     fFlags);                                        /* flags */
+    if (rc == KERN_SUCCESS)
+    {
+        pMemFreeBSD->Core.u.Lock.R0Process = R0Process;
+        *ppMem = &pMemFreeBSD->Core;
+        return VINF_SUCCESS;
+    }
+    rtR0MemObjDelete(&pMemFreeBSD->Core);
+    return VERR_NO_MEMORY;/** @todo fix mach -> vbox error conversion for freebsd. */
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeLockUser(PPRTR0MEMOBJINTERNAL ppMem, RTR3PTR R3Ptr, size_t cb, uint32_t fAccess, RTR0PROCESS R0Process)
+{
+    return rtR0MemObjNativeLockInMap(ppMem,
+                                     &((struct proc *)R0Process)->p_vmspace->vm_map,
+                                     (vm_offset_t)R3Ptr,
+                                     cb,
+                                     fAccess,
+                                     R0Process,
+                                     VM_MAP_WIRE_USER | VM_MAP_WIRE_NOHOLES);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeLockKernel(PPRTR0MEMOBJINTERNAL ppMem, void *pv, size_t cb, uint32_t fAccess)
+{
+    return rtR0MemObjNativeLockInMap(ppMem,
+                                     kernel_map,
+                                     (vm_offset_t)pv,
+                                     cb,
+                                     fAccess,
+                                     NIL_RTR0PROCESS,
+                                     VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
+}
+
+
+/**
+ * Worker for the two virtual address space reservers.
+ *
+ * We're leaning on the examples provided by mmap and vm_mmap in vm_mmap.c here.
+ */
+static int rtR0MemObjNativeReserveInMap(PPRTR0MEMOBJINTERNAL ppMem, void *pvFixed, size_t cb, size_t uAlignment, RTR0PROCESS R0Process, vm_map_t pMap)
+{
+    int rc;
+
+    /*
+     * The pvFixed address range must be within the VM space when specified.
+     */
+    if (   pvFixed != (void *)-1
+        && (    (vm_offset_t)pvFixed      < vm_map_min(pMap)
+            ||  (vm_offset_t)pvFixed + cb > vm_map_max(pMap)))
+        return VERR_INVALID_PARAMETER;
+
+    /*
+     * Check that the specified alignment is supported.
+     */
+    if (uAlignment > PAGE_SIZE)
+        return VERR_NOT_SUPPORTED;
+
+    /*
+     * Create the object.
+     */
+    PRTR0MEMOBJFREEBSD pMemFreeBSD = (PRTR0MEMOBJFREEBSD)rtR0MemObjNew(sizeof(*pMemFreeBSD), RTR0MEMOBJTYPE_RES_VIRT, NULL, cb);
+    if (!pMemFreeBSD)
+        return VERR_NO_MEMORY;
+
+    vm_offset_t MapAddress = pvFixed != (void *)-1
+                           ? (vm_offset_t)pvFixed
+                           : vm_map_min(pMap);
+    if (pvFixed != (void *)-1)
+        vm_map_remove(pMap,
+                      MapAddress,
+                      MapAddress + cb);
+
+    rc = vm_map_find(pMap,                          /* map */
+                     NULL,                          /* object */
+                     0,                             /* offset */
+                     &MapAddress,                   /* addr (IN/OUT) */
+                     cb,                            /* length */
+#if __FreeBSD_version >= 1000055
+                     0,                             /* max addr */
+#endif
+                     pvFixed == (void *)-1 ? VMFS_ANY_SPACE : VMFS_NO_SPACE,
+                                                    /* find_space */
+                     VM_PROT_NONE,                  /* protection */
+                     VM_PROT_ALL,                   /* max(_prot) ?? */
+                     0);                            /* cow (copy-on-write) */
+    if (rc == KERN_SUCCESS)
+    {
+        if (R0Process != NIL_RTR0PROCESS)
+        {
+            rc = vm_map_inherit(pMap,
+                                MapAddress,
+                                MapAddress + cb,
+                                VM_INHERIT_SHARE);
+            AssertMsg(rc == KERN_SUCCESS, ("%#x\n", rc));
+        }
+        pMemFreeBSD->Core.pv = (void *)MapAddress;
+        pMemFreeBSD->Core.u.ResVirt.R0Process = R0Process;
+        *ppMem = &pMemFreeBSD->Core;
+        return VINF_SUCCESS;
+    }
+
+    rc = VERR_NO_MEMORY; /** @todo fix translation (borrow from darwin) */
+    rtR0MemObjDelete(&pMemFreeBSD->Core);
+    return rc;
+
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeReserveKernel(PPRTR0MEMOBJINTERNAL ppMem, void *pvFixed, size_t cb, size_t uAlignment)
+{
+    return rtR0MemObjNativeReserveInMap(ppMem, pvFixed, cb, uAlignment, NIL_RTR0PROCESS, kernel_map);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeReserveUser(PPRTR0MEMOBJINTERNAL ppMem, RTR3PTR R3PtrFixed, size_t cb, size_t uAlignment, RTR0PROCESS R0Process)
+{
+    return rtR0MemObjNativeReserveInMap(ppMem, (void *)R3PtrFixed, cb, uAlignment, R0Process,
+                                        &((struct proc *)R0Process)->p_vmspace->vm_map);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeMapKernel(PPRTR0MEMOBJINTERNAL ppMem, RTR0MEMOBJ pMemToMap, void *pvFixed, size_t uAlignment,
+                                          unsigned fProt, size_t offSub, size_t cbSub)
+{
+//  AssertMsgReturn(!offSub && !cbSub, ("%#x %#x\n", offSub, cbSub), VERR_NOT_SUPPORTED);
+    AssertMsgReturn(pvFixed == (void *)-1, ("%p\n", pvFixed), VERR_NOT_SUPPORTED);
+
+    /*
+     * Check that the specified alignment is supported.
+     */
+    if (uAlignment > PAGE_SIZE)
+        return VERR_NOT_SUPPORTED;
+    Assert(!offSub || cbSub);
+
+    int                rc;
+    PRTR0MEMOBJFREEBSD pMemToMapFreeBSD = (PRTR0MEMOBJFREEBSD)pMemToMap;
+
+    /* calc protection */
+    vm_prot_t       ProtectionFlags = 0;
+    if ((fProt & RTMEM_PROT_NONE) == RTMEM_PROT_NONE)
+        ProtectionFlags = VM_PROT_NONE;
+    if ((fProt & RTMEM_PROT_READ) == RTMEM_PROT_READ)
+        ProtectionFlags |= VM_PROT_READ;
+    if ((fProt & RTMEM_PROT_WRITE) == RTMEM_PROT_WRITE)
+        ProtectionFlags |= VM_PROT_WRITE;
+    if ((fProt & RTMEM_PROT_EXEC) == RTMEM_PROT_EXEC)
+        ProtectionFlags |= VM_PROT_EXECUTE;
+
+    vm_offset_t  Addr = vm_map_min(kernel_map);
+    if (cbSub == 0)
+        cbSub = pMemToMap->cb - offSub;
+
+    vm_object_reference(pMemToMapFreeBSD->pObject);
+    rc = vm_map_find(kernel_map,            /* Map to insert the object in */
+                     pMemToMapFreeBSD->pObject, /* Object to map */
+                     offSub,                /* Start offset in the object */
+                     &Addr,                 /* Start address IN/OUT */
+                     cbSub,                 /* Size of the mapping */
+#if __FreeBSD_version >= 1000055
+                     0,                     /* Upper bound of mapping */
+#endif
+                     VMFS_ANY_SPACE,        /* Whether a suitable address should be searched for first */
+                     ProtectionFlags,       /* protection flags */
+                     VM_PROT_ALL,           /* Maximum protection flags */
+                     0);                    /* copy-on-write and similar flags */
+
+    if (rc == KERN_SUCCESS)
+    {
+        rc = vm_map_wire(kernel_map, Addr, Addr + cbSub, VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES);
+        AssertMsg(rc == KERN_SUCCESS, ("%#x\n", rc));
+
+        PRTR0MEMOBJFREEBSD pMemFreeBSD = (PRTR0MEMOBJFREEBSD)rtR0MemObjNew(sizeof(RTR0MEMOBJFREEBSD),
+                                                                           RTR0MEMOBJTYPE_MAPPING,
+                                                                           (void *)Addr,
+                                                                           cbSub);
+        if (pMemFreeBSD)
+        {
+            Assert((vm_offset_t)pMemFreeBSD->Core.pv == Addr);
+            pMemFreeBSD->Core.u.Mapping.R0Process = NIL_RTR0PROCESS;
+            *ppMem = &pMemFreeBSD->Core;
+            return VINF_SUCCESS;
+        }
+        rc = vm_map_remove(kernel_map, Addr, Addr + cbSub);
+        AssertMsg(rc == KERN_SUCCESS, ("Deleting mapping failed\n"));
+    }
+    else
+        vm_object_deallocate(pMemToMapFreeBSD->pObject);
+
+    return VERR_NO_MEMORY;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeMapUser(PPRTR0MEMOBJINTERNAL ppMem, RTR0MEMOBJ pMemToMap, RTR3PTR R3PtrFixed, size_t uAlignment,
+                                        unsigned fProt, RTR0PROCESS R0Process, size_t offSub, size_t cbSub)
+{
+    /*
+     * Check for unsupported stuff.
+     */
+    AssertMsgReturn(R0Process == RTR0ProcHandleSelf(), ("%p != %p\n", R0Process, RTR0ProcHandleSelf()), VERR_NOT_SUPPORTED);
+    if (uAlignment > PAGE_SIZE)
+        return VERR_NOT_SUPPORTED;
+    Assert(!offSub || cbSub);
+
+    int                rc;
+    PRTR0MEMOBJFREEBSD pMemToMapFreeBSD = (PRTR0MEMOBJFREEBSD)pMemToMap;
+    struct proc       *pProc            = (struct proc *)R0Process;
+    struct vm_map     *pProcMap         = &pProc->p_vmspace->vm_map;
+
+    /* calc protection */
+    vm_prot_t       ProtectionFlags = 0;
+    if ((fProt & RTMEM_PROT_NONE) == RTMEM_PROT_NONE)
+        ProtectionFlags = VM_PROT_NONE;
+    if ((fProt & RTMEM_PROT_READ) == RTMEM_PROT_READ)
+        ProtectionFlags |= VM_PROT_READ;
+    if ((fProt & RTMEM_PROT_WRITE) == RTMEM_PROT_WRITE)
+        ProtectionFlags |= VM_PROT_WRITE;
+    if ((fProt & RTMEM_PROT_EXEC) == RTMEM_PROT_EXEC)
+        ProtectionFlags |= VM_PROT_EXECUTE;
+
+    /* calc mapping address */
+    vm_offset_t AddrR3;
+    if (R3PtrFixed == (RTR3PTR)-1)
+    {
+        /** @todo is this needed?. */
+        PROC_LOCK(pProc);
+        AddrR3 = round_page((vm_offset_t)pProc->p_vmspace->vm_daddr + MY_LIM_MAX_PROC(pProc, RLIMIT_DATA));
+        PROC_UNLOCK(pProc);
+    }
+    else
+        AddrR3 = (vm_offset_t)R3PtrFixed;
+
+    if (cbSub == 0)
+        cbSub = pMemToMap->cb - offSub;
+
+    /* Insert the pObject in the map. */
+    vm_object_reference(pMemToMapFreeBSD->pObject);
+    rc = vm_map_find(pProcMap,              /* Map to insert the object in */
+                     pMemToMapFreeBSD->pObject, /* Object to map */
+                     offSub,                /* Start offset in the object */
+                     &AddrR3,               /* Start address IN/OUT */
+                     cbSub,                 /* Size of the mapping */
+#if __FreeBSD_version >= 1000055
+                     0,                     /* Upper bound of the mapping */
+#endif
+                     R3PtrFixed == (RTR3PTR)-1 ? VMFS_ANY_SPACE : VMFS_NO_SPACE,
+                                            /* Whether a suitable address should be searched for first */
+                     ProtectionFlags,       /* protection flags */
+                     VM_PROT_ALL,           /* Maximum protection flags */
+                     0);                    /* copy-on-write and similar flags */
+
+    if (rc == KERN_SUCCESS)
+    {
+        rc = vm_map_wire(pProcMap, AddrR3, AddrR3 + pMemToMap->cb, VM_MAP_WIRE_USER|VM_MAP_WIRE_NOHOLES);
+        AssertMsg(rc == KERN_SUCCESS, ("%#x\n", rc));
+
+        rc = vm_map_inherit(pProcMap, AddrR3, AddrR3 + pMemToMap->cb, VM_INHERIT_SHARE);
+        AssertMsg(rc == KERN_SUCCESS, ("%#x\n", rc));
+
+        /*
+         * Create a mapping object for it.
+         */
+        PRTR0MEMOBJFREEBSD pMemFreeBSD = (PRTR0MEMOBJFREEBSD)rtR0MemObjNew(sizeof(RTR0MEMOBJFREEBSD),
+                                                                           RTR0MEMOBJTYPE_MAPPING,
+                                                                           (void *)AddrR3,
+                                                                           pMemToMap->cb);
+        if (pMemFreeBSD)
+        {
+            Assert((vm_offset_t)pMemFreeBSD->Core.pv == AddrR3);
+            pMemFreeBSD->Core.u.Mapping.R0Process = R0Process;
+            *ppMem = &pMemFreeBSD->Core;
+            return VINF_SUCCESS;
+        }
+
+        rc = vm_map_remove(pProcMap, AddrR3, AddrR3 + pMemToMap->cb);
+        AssertMsg(rc == KERN_SUCCESS, ("Deleting mapping failed\n"));
+    }
+    else
+        vm_object_deallocate(pMemToMapFreeBSD->pObject);
+
+    return VERR_NO_MEMORY;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeProtect(PRTR0MEMOBJINTERNAL pMem, size_t offSub, size_t cbSub, uint32_t fProt)
+{
+    vm_prot_t          ProtectionFlags = 0;
+    vm_offset_t        AddrStart       = (uintptr_t)pMem->pv + offSub;
+    vm_offset_t        AddrEnd         = AddrStart + cbSub;
+    vm_map_t           pVmMap          = rtR0MemObjFreeBSDGetMap(pMem);
+
+    if (!pVmMap)
+        return VERR_NOT_SUPPORTED;
+
+    if ((fProt & RTMEM_PROT_NONE) == RTMEM_PROT_NONE)
+        ProtectionFlags = VM_PROT_NONE;
+    if ((fProt & RTMEM_PROT_READ) == RTMEM_PROT_READ)
+        ProtectionFlags |= VM_PROT_READ;
+    if ((fProt & RTMEM_PROT_WRITE) == RTMEM_PROT_WRITE)
+        ProtectionFlags |= VM_PROT_WRITE;
+    if ((fProt & RTMEM_PROT_EXEC) == RTMEM_PROT_EXEC)
+        ProtectionFlags |= VM_PROT_EXECUTE;
+
+    int krc = vm_map_protect(pVmMap, AddrStart, AddrEnd, ProtectionFlags, FALSE);
+    if (krc == KERN_SUCCESS)
+        return VINF_SUCCESS;
+
+    return VERR_NOT_SUPPORTED;
+}
+
+
+DECLHIDDEN(RTHCPHYS) rtR0MemObjNativeGetPagePhysAddr(PRTR0MEMOBJINTERNAL pMem, size_t iPage)
+{
+    PRTR0MEMOBJFREEBSD pMemFreeBSD = (PRTR0MEMOBJFREEBSD)pMem;
+
+    switch (pMemFreeBSD->Core.enmType)
+    {
+        case RTR0MEMOBJTYPE_LOCK:
+        {
+            if (    pMemFreeBSD->Core.u.Lock.R0Process != NIL_RTR0PROCESS
+                &&  pMemFreeBSD->Core.u.Lock.R0Process != (RTR0PROCESS)curproc)
+            {
+                /* later */
+                return NIL_RTHCPHYS;
+            }
+
+            vm_offset_t pb = (vm_offset_t)pMemFreeBSD->Core.pv + ptoa(iPage);
+
+            struct proc    *pProc     = (struct proc *)pMemFreeBSD->Core.u.Lock.R0Process;
+            struct vm_map  *pProcMap  = &pProc->p_vmspace->vm_map;
+            pmap_t pPhysicalMap       = vm_map_pmap(pProcMap);
+
+            return pmap_extract(pPhysicalMap, pb);
+        }
+
+        case RTR0MEMOBJTYPE_MAPPING:
+        {
+            vm_offset_t pb = (vm_offset_t)pMemFreeBSD->Core.pv + ptoa(iPage);
+
+            if (pMemFreeBSD->Core.u.Mapping.R0Process != NIL_RTR0PROCESS)
+            {
+                struct proc    *pProc     = (struct proc *)pMemFreeBSD->Core.u.Mapping.R0Process;
+                struct vm_map  *pProcMap  = &pProc->p_vmspace->vm_map;
+                pmap_t pPhysicalMap       = vm_map_pmap(pProcMap);
+
+                return pmap_extract(pPhysicalMap, pb);
+            }
+            return vtophys(pb);
+        }
+
+        case RTR0MEMOBJTYPE_PAGE:
+        case RTR0MEMOBJTYPE_LOW:
+        case RTR0MEMOBJTYPE_PHYS_NC:
+        {
+            RTHCPHYS addr;
+
+            VM_OBJECT_WLOCK(pMemFreeBSD->pObject);
+            addr = VM_PAGE_TO_PHYS(vm_page_lookup(pMemFreeBSD->pObject, iPage));
+            VM_OBJECT_WUNLOCK(pMemFreeBSD->pObject);
+            return addr;
+        }
+
+        case RTR0MEMOBJTYPE_PHYS:
+            return pMemFreeBSD->Core.u.Cont.Phys + ptoa(iPage);
+
+        case RTR0MEMOBJTYPE_CONT:
+            return pMemFreeBSD->Core.u.Phys.PhysBase + ptoa(iPage);
+
+        case RTR0MEMOBJTYPE_RES_VIRT:
+        default:
+            return NIL_RTHCPHYS;
+    }
+}
+
diff --git a/src/VBox/Runtime/r0drv/freebsd/memuserkernel-r0drv-freebsd.c b/src/VBox/Runtime/r0drv/freebsd/memuserkernel-r0drv-freebsd.c
new file mode 100644
index 00000000..078c548e
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/freebsd/memuserkernel-r0drv-freebsd.c
@@ -0,0 +1,83 @@
+/* $Id: memuserkernel-r0drv-freebsd.c $ */
+/** @file
+ * IPRT - User & Kernel Memory, Ring-0 Driver, FreeBSD.
+ */
+
+/*
+ * Copyright (C) 2009-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-freebsd-kernel.h"
+
+#include <iprt/mem.h>
+#include <iprt/errcore.h>
+
+
+RTR0DECL(int) RTR0MemUserCopyFrom(void *pvDst, RTR3PTR R3PtrSrc, size_t cb)
+{
+    int rc = copyin((const void *)R3PtrSrc, pvDst, cb);
+    if (RT_LIKELY(rc == 0))
+        return VINF_SUCCESS;
+    return VERR_ACCESS_DENIED;
+}
+
+
+RTR0DECL(int) RTR0MemUserCopyTo(RTR3PTR R3PtrDst, void const *pvSrc, size_t cb)
+{
+    int rc = copyout(pvSrc, (void *)R3PtrDst, cb);
+    if (RT_LIKELY(rc == 0))
+        return VINF_SUCCESS;
+    return VERR_ACCESS_DENIED;
+}
+
+
+RTR0DECL(bool) RTR0MemUserIsValidAddr(RTR3PTR R3Ptr)
+{
+    return R3Ptr < VM_MAXUSER_ADDRESS;
+}
+
+
+RTR0DECL(bool) RTR0MemKernelIsValidAddr(void *pv)
+{
+    return (uintptr_t)pv >= VM_MAXUSER_ADDRESS;
+}
+
+
+RTR0DECL(bool) RTR0MemAreKrnlAndUsrDifferent(void)
+{
+    return true;
+}
+
+
+RTR0DECL(int) RTR0MemKernelCopyFrom(void *pvDst, void const *pvSrc, size_t cb)
+{
+    return VERR_NOT_SUPPORTED;
+}
+
+
+RTR0DECL(int) RTR0MemKernelCopyTo(void *pvDst, void const *pvSrc, size_t cb)
+{
+    return VERR_NOT_SUPPORTED;
+}
+
diff --git a/src/VBox/Runtime/r0drv/freebsd/mp-r0drv-freebsd.c b/src/VBox/Runtime/r0drv/freebsd/mp-r0drv-freebsd.c
new file mode 100644
index 00000000..e8b86960
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/freebsd/mp-r0drv-freebsd.c
@@ -0,0 +1,312 @@
+/* $Id: mp-r0drv-freebsd.c $ */
+/** @file
+ * IPRT - Multiprocessor, Ring-0 Driver, FreeBSD.
+ */
+
+/*
+ * Copyright (C) 2008-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-freebsd-kernel.h"
+
+#include <iprt/mp.h>
+#include <iprt/err.h>
+#include <iprt/asm.h>
+#include <iprt/cpuset.h>
+#include "r0drv/mp-r0drv.h"
+
+
+#if __FreeBSD_version < 1200028
+# define smp_no_rendezvous_barrier smp_no_rendevous_barrier
+#endif
+
+RTDECL(RTCPUID) RTMpCpuId(void)
+{
+    return curcpu;
+}
+
+
+RTDECL(int) RTMpCurSetIndex(void)
+{
+    return curcpu;
+}
+
+
+RTDECL(int) RTMpCurSetIndexAndId(PRTCPUID pidCpu)
+{
+    return *pidCpu = curcpu;
+}
+
+
+RTDECL(int) RTMpCpuIdToSetIndex(RTCPUID idCpu)
+{
+    return idCpu < RTCPUSET_MAX_CPUS && idCpu <= mp_maxid ? (int)idCpu : -1;
+}
+
+
+RTDECL(RTCPUID) RTMpCpuIdFromSetIndex(int iCpu)
+{
+    return (unsigned)iCpu <= mp_maxid ? (RTCPUID)iCpu : NIL_RTCPUID;
+}
+
+
+RTDECL(RTCPUID) RTMpGetMaxCpuId(void)
+{
+    return mp_maxid;
+}
+
+
+RTDECL(bool) RTMpIsCpuPossible(RTCPUID idCpu)
+{
+    return idCpu <= mp_maxid;
+}
+
+
+RTDECL(PRTCPUSET) RTMpGetSet(PRTCPUSET pSet)
+{
+    RTCPUID idCpu;
+
+    RTCpuSetEmpty(pSet);
+    idCpu = RTMpGetMaxCpuId();
+    do
+    {
+        if (RTMpIsCpuPossible(idCpu))
+            RTCpuSetAdd(pSet, idCpu);
+    } while (idCpu-- > 0);
+    return pSet;
+}
+
+
+RTDECL(RTCPUID) RTMpGetCount(void)
+{
+    return mp_maxid + 1;
+}
+
+
+RTDECL(RTCPUID) RTMpGetCoreCount(void)
+{
+    return mp_maxid + 1;
+}
+
+RTDECL(bool) RTMpIsCpuOnline(RTCPUID idCpu)
+{
+    return idCpu <= mp_maxid
+        && !CPU_ABSENT(idCpu);
+}
+
+
+RTDECL(PRTCPUSET) RTMpGetOnlineSet(PRTCPUSET pSet)
+{
+    RTCPUID idCpu;
+
+    RTCpuSetEmpty(pSet);
+    idCpu = RTMpGetMaxCpuId();
+    do
+    {
+        if (RTMpIsCpuOnline(idCpu))
+            RTCpuSetAdd(pSet, idCpu);
+    } while (idCpu-- > 0);
+
+    return pSet;
+}
+
+
+RTDECL(RTCPUID) RTMpGetOnlineCount(void)
+{
+    return mp_ncpus;
+}
+
+
+/**
+ * Wrapper between the native FreeBSD per-cpu callback and PFNRTWORKER
+ * for the RTMpOnAll API.
+ *
+ * @param   pvArg   Pointer to the RTMPARGS package.
+ */
+static void rtmpOnAllFreeBSDWrapper(void *pvArg)
+{
+    PRTMPARGS pArgs = (PRTMPARGS)pvArg;
+    pArgs->pfnWorker(curcpu, pArgs->pvUser1, pArgs->pvUser2);
+}
+
+
+RTDECL(int) RTMpOnAll(PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    RTMPARGS Args;
+    Args.pfnWorker = pfnWorker;
+    Args.pvUser1 = pvUser1;
+    Args.pvUser2 = pvUser2;
+    Args.idCpu = NIL_RTCPUID;
+    Args.cHits = 0;
+    smp_rendezvous(NULL, rtmpOnAllFreeBSDWrapper, smp_no_rendezvous_barrier, &Args);
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Wrapper between the native FreeBSD per-cpu callback and PFNRTWORKER
+ * for the RTMpOnOthers API.
+ *
+ * @param   pvArg   Pointer to the RTMPARGS package.
+ */
+static void rtmpOnOthersFreeBSDWrapper(void *pvArg)
+{
+    PRTMPARGS pArgs = (PRTMPARGS)pvArg;
+    RTCPUID idCpu = curcpu;
+    if (pArgs->idCpu != idCpu)
+        pArgs->pfnWorker(idCpu, pArgs->pvUser1, pArgs->pvUser2);
+}
+
+
+RTDECL(int) RTMpOnOthers(PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    /* Will panic if no rendezvousing cpus, so check up front. */
+    if (RTMpGetOnlineCount() > 1)
+    {
+#if __FreeBSD_version >= 900000
+        cpuset_t    Mask;
+#elif  __FreeBSD_version >= 700000
+        cpumask_t   Mask;
+#endif
+        RTMPARGS    Args;
+
+        Args.pfnWorker = pfnWorker;
+        Args.pvUser1 = pvUser1;
+        Args.pvUser2 = pvUser2;
+        Args.idCpu = RTMpCpuId();
+        Args.cHits = 0;
+#if __FreeBSD_version >= 700000
+# if __FreeBSD_version >= 900000
+        Mask = all_cpus;
+        CPU_CLR(curcpu, &Mask);
+# else
+        Mask = ~(cpumask_t)curcpu;
+# endif
+        smp_rendezvous_cpus(Mask, NULL, rtmpOnOthersFreeBSDWrapper, smp_no_rendezvous_barrier, &Args);
+#else
+        smp_rendezvous(NULL, rtmpOnOthersFreeBSDWrapper, NULL, &Args);
+#endif
+    }
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Wrapper between the native FreeBSD per-cpu callback and PFNRTWORKER
+ * for the RTMpOnSpecific API.
+ *
+ * @param   pvArg   Pointer to the RTMPARGS package.
+ */
+static void rtmpOnSpecificFreeBSDWrapper(void *pvArg)
+{
+    PRTMPARGS   pArgs = (PRTMPARGS)pvArg;
+    RTCPUID     idCpu = curcpu;
+    if (pArgs->idCpu == idCpu)
+    {
+        pArgs->pfnWorker(idCpu, pArgs->pvUser1, pArgs->pvUser2);
+        ASMAtomicIncU32(&pArgs->cHits);
+    }
+}
+
+
+RTDECL(int) RTMpOnSpecific(RTCPUID idCpu, PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+#if __FreeBSD_version >= 900000
+    cpuset_t    Mask;
+#elif  __FreeBSD_version >= 700000
+    cpumask_t   Mask;
+#endif
+    RTMPARGS    Args;
+
+    /* Will panic if no rendezvousing cpus, so make sure the cpu is online. */
+    if (!RTMpIsCpuOnline(idCpu))
+        return VERR_CPU_NOT_FOUND;
+
+    Args.pfnWorker = pfnWorker;
+    Args.pvUser1 = pvUser1;
+    Args.pvUser2 = pvUser2;
+    Args.idCpu = idCpu;
+    Args.cHits = 0;
+#if __FreeBSD_version >= 700000
+# if __FreeBSD_version >= 900000
+    CPU_SETOF(idCpu, &Mask);
+# else
+    Mask = (cpumask_t)1 << idCpu;
+# endif
+    smp_rendezvous_cpus(Mask, NULL, rtmpOnSpecificFreeBSDWrapper, smp_no_rendezvous_barrier, &Args);
+#else
+    smp_rendezvous(NULL, rtmpOnSpecificFreeBSDWrapper, NULL, &Args);
+#endif
+    return Args.cHits == 1
+         ? VINF_SUCCESS
+         : VERR_CPU_NOT_FOUND;
+}
+
+
+#if __FreeBSD_version >= 700000
+/**
+ * Dummy callback for RTMpPokeCpu.
+ * @param   pvArg   Ignored
+ */
+static void rtmpFreeBSDPokeCallback(void *pvArg)
+{
+    NOREF(pvArg);
+}
+
+
+RTDECL(int) RTMpPokeCpu(RTCPUID idCpu)
+{
+#if __FreeBSD_version >= 900000
+    cpuset_t    Mask;
+#elif  __FreeBSD_version >= 700000
+    cpumask_t   Mask;
+#endif
+
+    /* Will panic if no rendezvousing cpus, so make sure the cpu is online. */
+    if (!RTMpIsCpuOnline(idCpu))
+        return VERR_CPU_NOT_FOUND;
+
+# if __FreeBSD_version >= 900000
+    CPU_SETOF(idCpu, &Mask);
+# else
+    Mask = (cpumask_t)1 << idCpu;
+# endif
+    smp_rendezvous_cpus(Mask, NULL, rtmpFreeBSDPokeCallback, smp_no_rendezvous_barrier, NULL);
+
+    return VINF_SUCCESS;
+}
+
+#else  /* < 7.0 */
+RTDECL(int) RTMpPokeCpu(RTCPUID idCpu)
+{
+    return VERR_NOT_SUPPORTED;
+}
+#endif /* < 7.0 */
+
+
+RTDECL(bool) RTMpOnAllIsConcurrentSafe(void)
+{
+    return true;
+}
+
diff --git a/src/VBox/Runtime/r0drv/freebsd/process-r0drv-freebsd.c b/src/VBox/Runtime/r0drv/freebsd/process-r0drv-freebsd.c
new file mode 100644
index 00000000..a00cf566
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/freebsd/process-r0drv-freebsd.c
@@ -0,0 +1,75 @@
+/* $Id: process-r0drv-freebsd.c $ */
+/** @file
+ * IPRT - Process Management, Ring-0 Driver, FreeBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-freebsd-kernel.h"
+
+#include <iprt/process.h>
+
+
+RTDECL(RTPROCESS) RTProcSelf(void)
+{
+    struct proc *pSelf = curproc;
+    return pSelf->p_pid;
+}
+
+
+RTR0DECL(RTR0PROCESS) RTR0ProcHandleSelf(void)
+{
+    return (RTR0PROCESS)curproc;
+}
+
diff --git a/src/VBox/Runtime/r0drv/freebsd/semevent-r0drv-freebsd.c b/src/VBox/Runtime/r0drv/freebsd/semevent-r0drv-freebsd.c
new file mode 100644
index 00000000..bd208a93
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/freebsd/semevent-r0drv-freebsd.c
@@ -0,0 +1,280 @@
+/* $Id: semevent-r0drv-freebsd.c $ */
+/** @file
+ * IPRT - Single Release Event Semaphores, Ring-0 Driver, FreeBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTSEMEVENT_WITHOUT_REMAPPING
+#include "the-freebsd-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/semaphore.h>
+
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/lockvalidator.h>
+#include <iprt/mem.h>
+
+#include "sleepqueue-r0drv-freebsd.h"
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * FreeBSD event semaphore.
+ */
+typedef struct RTSEMEVENTINTERNAL
+{
+    /** Magic value (RTSEMEVENT_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** The object status - !0 when signaled and 0 when reset. */
+    uint32_t volatile   fState;
+    /** Reference counter. */
+    uint32_t volatile   cRefs;
+} RTSEMEVENTINTERNAL, *PRTSEMEVENTINTERNAL;
+
+
+RTDECL(int)  RTSemEventCreate(PRTSEMEVENT phEventSem)
+{
+    return RTSemEventCreateEx(phEventSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, NULL);
+}
+
+
+RTDECL(int)  RTSemEventCreateEx(PRTSEMEVENT phEventSem, uint32_t fFlags, RTLOCKVALCLASS hClass, const char *pszNameFmt, ...)
+{
+    AssertCompile(sizeof(RTSEMEVENTINTERNAL) > sizeof(void *));
+    AssertReturn(!(fFlags & ~(RTSEMEVENT_FLAGS_NO_LOCK_VAL | RTSEMEVENT_FLAGS_BOOTSTRAP_HACK)), VERR_INVALID_PARAMETER);
+    Assert(!(fFlags & RTSEMEVENT_FLAGS_BOOTSTRAP_HACK) || (fFlags & RTSEMEVENT_FLAGS_NO_LOCK_VAL));
+    AssertPtrReturn(phEventSem, VERR_INVALID_POINTER);
+
+    PRTSEMEVENTINTERNAL pThis = (PRTSEMEVENTINTERNAL)RTMemAllocZ(sizeof(*pThis));
+    if (!pThis)
+        return VERR_NO_MEMORY;
+
+    pThis->u32Magic  = RTSEMEVENT_MAGIC;
+    pThis->cRefs     = 1;
+    pThis->fState    = 0;
+
+    *phEventSem = pThis;
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Retains a reference to the event semaphore.
+ *
+ * @param   pThis       The event semaphore.
+ */
+DECLINLINE(void) rtR0SemEventBsdRetain(PRTSEMEVENTINTERNAL pThis)
+{
+    uint32_t cRefs = ASMAtomicIncU32(&pThis->cRefs);
+    Assert(cRefs < 100000); NOREF(cRefs);
+}
+
+
+/**
+ * Releases a reference to the event semaphore.
+ *
+ * @param   pThis       The event semaphore.
+ */
+DECLINLINE(void) rtR0SemEventBsdRelease(PRTSEMEVENTINTERNAL pThis)
+{
+    if (RT_UNLIKELY(ASMAtomicDecU32(&pThis->cRefs) == 0))
+        RTMemFree(pThis);
+}
+
+
+RTDECL(int)  RTSemEventDestroy(RTSEMEVENT hEventSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTINTERNAL pThis = hEventSem;
+    if (pThis == NIL_RTSEMEVENT)
+        return VINF_SUCCESS;
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("pThis->u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+    Assert(pThis->cRefs > 0);
+
+    /*
+     * Invalidate it and signal the object just in case.
+     */
+    ASMAtomicWriteU32(&pThis->u32Magic, ~RTSEMEVENT_MAGIC);
+    ASMAtomicWriteU32(&pThis->fState, 0);
+    rtR0SemBsdBroadcast(pThis);
+    rtR0SemEventBsdRelease(pThis);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemEventSignal(RTSEMEVENT hEventSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTINTERNAL pThis = (PRTSEMEVENTINTERNAL)hEventSem;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("pThis->u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+    rtR0SemEventBsdRetain(pThis);
+
+    /*
+     * Signal the event object.
+     */
+    ASMAtomicWriteU32(&pThis->fState, 1);
+    rtR0SemBsdSignal(pThis);
+    rtR0SemEventBsdRelease(pThis);
+    return VINF_SUCCESS;
+}
+
+/**
+ * Worker for RTSemEventWaitEx and RTSemEventWaitExDebug.
+ *
+ * @returns VBox status code.
+ * @param   pThis           The event semaphore.
+ * @param   fFlags          See RTSemEventWaitEx.
+ * @param   uTimeout        See RTSemEventWaitEx.
+ * @param   pSrcPos         The source code position of the wait.
+ */
+static int rtR0SemEventWait(PRTSEMEVENTINTERNAL pThis, uint32_t fFlags, uint64_t uTimeout,
+                            PCRTLOCKVALSRCPOS pSrcPos)
+{
+    int rc;
+
+    /*
+     * Validate the input.
+     */
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    AssertReturn(RTSEMWAIT_FLAGS_ARE_VALID(fFlags), VERR_INVALID_PARAMETER);
+    rtR0SemEventBsdRetain(pThis);
+
+    /*
+     * Try grab the event without setting up the wait.
+     */
+    if (ASMAtomicCmpXchgU32(&pThis->fState, 0, 1))
+        rc = VINF_SUCCESS;
+    else
+    {
+        /*
+         * We have to wait.
+         */
+        RTR0SEMBSDSLEEP Wait;
+        rc = rtR0SemBsdWaitInit(&Wait, fFlags, uTimeout, pThis);
+        if (RT_SUCCESS(rc))
+        {
+            for (;;)
+            {
+                /* The destruction test. */
+                if (RT_UNLIKELY(pThis->u32Magic != RTSEMEVENT_MAGIC))
+                    rc = VERR_SEM_DESTROYED;
+                else
+                {
+                    rtR0SemBsdWaitPrepare(&Wait);
+
+                    /* Check the exit conditions. */
+                    if (RT_UNLIKELY(pThis->u32Magic != RTSEMEVENT_MAGIC))
+                        rc = VERR_SEM_DESTROYED;
+                    else if (ASMAtomicCmpXchgU32(&pThis->fState, 0, 1))
+                        rc = VINF_SUCCESS;
+                    else if (rtR0SemBsdWaitHasTimedOut(&Wait))
+                        rc = VERR_TIMEOUT;
+                    else if (rtR0SemBsdWaitWasInterrupted(&Wait))
+                        rc = VERR_INTERRUPTED;
+                    else
+                    {
+                        /* Do the wait and then recheck the conditions. */
+                        rtR0SemBsdWaitDoIt(&Wait);
+                        continue;
+                    }
+                }
+                break;
+            }
+
+            rtR0SemBsdWaitDelete(&Wait);
+        }
+    }
+
+    rtR0SemEventBsdRelease(pThis);
+    return rc;
+}
+
+
+RTDECL(int)  RTSemEventWaitEx(RTSEMEVENT hEventSem, uint32_t fFlags, uint64_t uTimeout)
+{
+#ifndef RTSEMEVENT_STRICT
+    return rtR0SemEventWait(hEventSem, fFlags, uTimeout, NULL);
+#else
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
+    return rtR0SemEventWait(hEventSem, fFlags, uTimeout, &SrcPos);
+#endif
+}
+RT_EXPORT_SYMBOL(RTSemEventWaitEx);
+
+
+RTDECL(int)  RTSemEventWaitExDebug(RTSEMEVENT hEventSem, uint32_t fFlags, uint64_t uTimeout,
+                                   RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
+    return rtR0SemEventWait(hEventSem, fFlags, uTimeout, &SrcPos);
+}
+RT_EXPORT_SYMBOL(RTSemEventWaitExDebug);
+
+
+RTDECL(uint32_t) RTSemEventGetResolution(void)
+{
+    return 1000000000 / hz;
+}
+
diff --git a/src/VBox/Runtime/r0drv/freebsd/semeventmulti-r0drv-freebsd.c b/src/VBox/Runtime/r0drv/freebsd/semeventmulti-r0drv-freebsd.c
new file mode 100644
index 00000000..56a5ef14
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/freebsd/semeventmulti-r0drv-freebsd.c
@@ -0,0 +1,344 @@
+/* $Id: semeventmulti-r0drv-freebsd.c $ */
+/** @file
+ * IPRT - Multiple Release Event Semaphores, Ring-0 Driver, FreeBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTSEMEVENTMULTI_WITHOUT_REMAPPING
+#include "the-freebsd-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/semaphore.h>
+
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+#include <iprt/err.h>
+#include <iprt/mem.h>
+#include <iprt/lockvalidator.h>
+
+#include "sleepqueue-r0drv-freebsd.h"
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+/** @name fStateAndGen values
+ * @{ */
+/** The state bit number. */
+#define RTSEMEVENTMULTIBSD_STATE_BIT        0
+/** The state mask. */
+#define RTSEMEVENTMULTIBSD_STATE_MASK       RT_BIT_32(RTSEMEVENTMULTIBSD_STATE_BIT)
+/** The generation mask. */
+#define RTSEMEVENTMULTIBSD_GEN_MASK         ~RTSEMEVENTMULTIBSD_STATE_MASK
+/** The generation shift. */
+#define RTSEMEVENTMULTIBSD_GEN_SHIFT        1
+/** The initial variable value. */
+#define RTSEMEVENTMULTIBSD_STATE_GEN_INIT   UINT32_C(0xfffffffc)
+/** @}  */
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * FreeBSD multiple release event semaphore.
+ */
+typedef struct RTSEMEVENTMULTIINTERNAL
+{
+    /** Magic value (RTSEMEVENTMULTI_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** The object state bit and generation counter.
+     * The generation counter is incremented every time the object is
+     * signalled. */
+    uint32_t volatile   fStateAndGen;
+    /** Reference counter. */
+    uint32_t volatile   cRefs;
+} RTSEMEVENTMULTIINTERNAL, *PRTSEMEVENTMULTIINTERNAL;
+
+
+RTDECL(int)  RTSemEventMultiCreate(PRTSEMEVENTMULTI phEventMultiSem)
+{
+    return RTSemEventMultiCreateEx(phEventMultiSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, NULL);
+}
+
+
+RTDECL(int)  RTSemEventMultiCreateEx(PRTSEMEVENTMULTI phEventMultiSem, uint32_t fFlags, RTLOCKVALCLASS hClass,
+                                     const char *pszNameFmt, ...)
+{
+    PRTSEMEVENTMULTIINTERNAL pThis;
+
+    AssertReturn(!(fFlags & ~RTSEMEVENTMULTI_FLAGS_NO_LOCK_VAL), VERR_INVALID_PARAMETER);
+    pThis = (PRTSEMEVENTMULTIINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (pThis)
+    {
+        pThis->u32Magic     = RTSEMEVENTMULTI_MAGIC;
+        pThis->fStateAndGen = RTSEMEVENTMULTIBSD_STATE_GEN_INIT;
+        pThis->cRefs        = 1;
+
+        *phEventMultiSem = pThis;
+        return VINF_SUCCESS;
+    }
+    return VERR_NO_MEMORY;
+}
+
+
+/**
+ * Retain a reference to the semaphore.
+ *
+ * @param   pThis       The semaphore.
+ */
+DECLINLINE(void) rtR0SemEventMultiBsdRetain(PRTSEMEVENTMULTIINTERNAL pThis)
+{
+    uint32_t cRefs = ASMAtomicIncU32(&pThis->cRefs);
+    Assert(cRefs && cRefs < 100000);
+}
+
+
+/**
+ * Release a reference, destroy the thing if necessary.
+ *
+ * @param   pThis       The semaphore.
+ */
+DECLINLINE(void) rtR0SemEventMultiBsdRelease(PRTSEMEVENTMULTIINTERNAL pThis)
+{
+    if (RT_UNLIKELY(ASMAtomicDecU32(&pThis->cRefs) == 0))
+    {
+        Assert(pThis->u32Magic != RTSEMEVENTMULTI_MAGIC);
+        RTMemFree(pThis);
+    }
+}
+
+
+RTDECL(int)  RTSemEventMultiDestroy(RTSEMEVENTMULTI hEventMultiSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    if (pThis == NIL_RTSEMEVENTMULTI)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    Assert(pThis->cRefs > 0);
+
+    /*
+     * Invalidate it and signal the object just in case.
+     */
+    ASMAtomicWriteU32(&pThis->u32Magic, ~RTSEMEVENTMULTI_MAGIC);
+    ASMAtomicAndU32(&pThis->fStateAndGen, RTSEMEVENTMULTIBSD_GEN_MASK);
+    rtR0SemBsdBroadcast(pThis);
+    rtR0SemEventMultiBsdRelease(pThis);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemEventMultiSignal(RTSEMEVENTMULTI hEventMultiSem)
+{
+    uint32_t fNew;
+    uint32_t fOld;
+
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    if (!pThis)
+        return VERR_INVALID_PARAMETER;
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    rtR0SemEventMultiBsdRetain(pThis);
+
+    /*
+     * Signal the event object.  The cause of the parnoia here is racing to try
+     * deal with racing RTSemEventMultiSignal calls (should probably be
+     * forbidden, but it's relatively easy to handle).
+     */
+    do
+    {
+        fNew = fOld = ASMAtomicUoReadU32(&pThis->fStateAndGen);
+        fNew += 1 << RTSEMEVENTMULTIBSD_GEN_SHIFT;
+        fNew |= RTSEMEVENTMULTIBSD_STATE_MASK;
+    }
+    while (!ASMAtomicCmpXchgU32(&pThis->fStateAndGen, fNew, fOld));
+
+    rtR0SemBsdBroadcast(pThis);
+    rtR0SemEventMultiBsdRelease(pThis);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemEventMultiReset(RTSEMEVENTMULTI hEventMultiSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    if (!pThis)
+        return VERR_INVALID_PARAMETER;
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    rtR0SemEventMultiBsdRetain(pThis);
+
+    /*
+     * Reset it.
+     */
+    ASMAtomicAndU32(&pThis->fStateAndGen, ~RTSEMEVENTMULTIBSD_STATE_MASK);
+
+    rtR0SemEventMultiBsdRelease(pThis);
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Worker for RTSemEventMultiWaitEx and RTSemEventMultiWaitExDebug.
+ *
+ * @returns VBox status code.
+ * @param   pThis           The event semaphore.
+ * @param   fFlags          See RTSemEventMultiWaitEx.
+ * @param   uTimeout        See RTSemEventMultiWaitEx.
+ * @param   pSrcPos         The source code position of the wait.
+ */
+static int rtR0SemEventMultiBsdWait(PRTSEMEVENTMULTIINTERNAL pThis, uint32_t fFlags, uint64_t uTimeout,
+                                    PCRTLOCKVALSRCPOS pSrcPos)
+{
+    uint32_t    fOrgStateAndGen;
+    int         rc;
+
+    /*
+     * Validate the input.
+     */
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    AssertReturn(RTSEMWAIT_FLAGS_ARE_VALID(fFlags), VERR_INVALID_PARAMETER);
+    rtR0SemEventMultiBsdRetain(pThis);
+
+    /*
+     * Is the event already signalled or do we have to wait?
+     */
+    fOrgStateAndGen = ASMAtomicUoReadU32(&pThis->fStateAndGen);
+    if (fOrgStateAndGen & RTSEMEVENTMULTIBSD_STATE_MASK)
+        rc = VINF_SUCCESS;
+    else
+    {
+        /*
+         * We have to wait.
+         */
+        RTR0SEMBSDSLEEP Wait;
+        rc = rtR0SemBsdWaitInit(&Wait, fFlags, uTimeout, pThis);
+        if (RT_SUCCESS(rc))
+        {
+            for (;;)
+            {
+                /* The destruction test. */
+                if (RT_UNLIKELY(pThis->u32Magic != RTSEMEVENTMULTI_MAGIC))
+                    rc = VERR_SEM_DESTROYED;
+                else
+                {
+                    rtR0SemBsdWaitPrepare(&Wait);
+
+                    /* Check the exit conditions. */
+                    if (RT_UNLIKELY(pThis->u32Magic != RTSEMEVENTMULTI_MAGIC))
+                        rc = VERR_SEM_DESTROYED;
+                    else if (ASMAtomicUoReadU32(&pThis->fStateAndGen) != fOrgStateAndGen)
+                        rc = VINF_SUCCESS;
+                    else if (rtR0SemBsdWaitHasTimedOut(&Wait))
+                        rc = VERR_TIMEOUT;
+                    else if (rtR0SemBsdWaitWasInterrupted(&Wait))
+                        rc = VERR_INTERRUPTED;
+                    else
+                    {
+                        /* Do the wait and then recheck the conditions. */
+                        rtR0SemBsdWaitDoIt(&Wait);
+                        continue;
+                    }
+                }
+                break;
+            }
+
+            rtR0SemBsdWaitDelete(&Wait);
+        }
+    }
+
+    rtR0SemEventMultiBsdRelease(pThis);
+    return rc;
+}
+
+
+RTDECL(int)  RTSemEventMultiWaitEx(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout)
+{
+#ifndef RTSEMEVENT_STRICT
+    return rtR0SemEventMultiBsdWait(hEventMultiSem, fFlags, uTimeout, NULL);
+#else
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
+    return rtR0SemEventMultiBsdWait(hEventMultiSem, fFlags, uTimeout, &SrcPos);
+#endif
+}
+RT_EXPORT_SYMBOL(RTSemEventMultiWaitEx);
+
+
+RTDECL(int)  RTSemEventMultiWaitExDebug(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout,
+                                        RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
+    return rtR0SemEventMultiBsdWait(hEventMultiSem, fFlags, uTimeout, &SrcPos);
+}
+RT_EXPORT_SYMBOL(RTSemEventMultiWaitExDebug);
+
+
+RTDECL(uint32_t) RTSemEventMultiGetResolution(void)
+{
+    return rtR0SemBsdWaitGetResolution();
+}
+RT_EXPORT_SYMBOL(RTSemEventMultiGetResolution);
+
diff --git a/src/VBox/Runtime/r0drv/freebsd/semfastmutex-r0drv-freebsd.c b/src/VBox/Runtime/r0drv/freebsd/semfastmutex-r0drv-freebsd.c
new file mode 100644
index 00000000..53035200
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/freebsd/semfastmutex-r0drv-freebsd.c
@@ -0,0 +1,139 @@
+/* $Id: semfastmutex-r0drv-freebsd.c $ */
+/** @file
+ * IPRT - Fast Mutex Semaphores, Ring-0 Driver, FreeBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-freebsd-kernel.h"
+
+#include <iprt/semaphore.h>
+#include <iprt/errcore.h>
+#include <iprt/alloc.h>
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Wrapper for the FreeBSD (sleep) mutex.
+ */
+typedef struct RTSEMFASTMUTEXINTERNAL
+{
+    /** Magic value (RTSEMFASTMUTEX_MAGIC). */
+    uint32_t            u32Magic;
+    /** The FreeBSD shared/exclusive lock mutex. */
+    struct sx           SxLock;
+} RTSEMFASTMUTEXINTERNAL, *PRTSEMFASTMUTEXINTERNAL;
+
+
+RTDECL(int)  RTSemFastMutexCreate(PRTSEMFASTMUTEX phFastMtx)
+{
+    AssertCompile(sizeof(RTSEMFASTMUTEXINTERNAL) > sizeof(void *));
+    AssertPtrReturn(phFastMtx, VERR_INVALID_POINTER);
+
+    PRTSEMFASTMUTEXINTERNAL pThis = (PRTSEMFASTMUTEXINTERNAL)RTMemAllocZ(sizeof(*pThis));
+    if (pThis)
+    {
+        pThis->u32Magic = RTSEMFASTMUTEX_MAGIC;
+        sx_init_flags(&pThis->SxLock, "IPRT Fast Mutex Semaphore", SX_DUPOK);
+
+        *phFastMtx = pThis;
+        return VINF_SUCCESS;
+    }
+    return VERR_NO_MEMORY;
+}
+
+
+RTDECL(int)  RTSemFastMutexDestroy(RTSEMFASTMUTEX hFastMtx)
+{
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    if (pThis == NIL_RTSEMFASTMUTEX)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    ASMAtomicWriteU32(&pThis->u32Magic, RTSEMFASTMUTEX_MAGIC_DEAD);
+    sx_destroy(&pThis->SxLock);
+    RTMemFree(pThis);
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemFastMutexRequest(RTSEMFASTMUTEX hFastMtx)
+{
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    sx_xlock(&pThis->SxLock);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemFastMutexRelease(RTSEMFASTMUTEX hFastMtx)
+{
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    sx_xunlock(&pThis->SxLock);
+    return VINF_SUCCESS;
+}
+
diff --git a/src/VBox/Runtime/r0drv/freebsd/semmutex-r0drv-freebsd.c b/src/VBox/Runtime/r0drv/freebsd/semmutex-r0drv-freebsd.c
new file mode 100644
index 00000000..ec6ac89d
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/freebsd/semmutex-r0drv-freebsd.c
@@ -0,0 +1,219 @@
+/* $Id: semmutex-r0drv-freebsd.c $ */
+/** @file
+ * IPRT - Mutex Semaphores, Ring-0 Driver, FreeBSD.
+ */
+
+/*
+ * Copyright (C) 2010-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTSEMMUTEX_WITHOUT_REMAPPING
+#include "the-freebsd-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/semaphore.h>
+
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+#include <iprt/mem.h>
+#include <iprt/thread.h>
+#include <iprt/time.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Wrapper for the FreeBSD (sleep) mutex.
+ */
+typedef struct RTSEMMUTEXINTERNAL
+{
+    /** Magic value (RTSEMMUTEX_MAGIC). */
+    uint32_t            u32Magic;
+    /** The FreeBSD shared/exclusive lock mutex. */
+    struct sx           SxLock;
+} RTSEMMUTEXINTERNAL, *PRTSEMMUTEXINTERNAL;
+
+
+RTDECL(int)  RTSemMutexCreate(PRTSEMMUTEX phMutexSem)
+{
+    AssertCompile(sizeof(RTSEMMUTEXINTERNAL) > sizeof(void *));
+    AssertPtrReturn(phMutexSem, VERR_INVALID_POINTER);
+
+    PRTSEMMUTEXINTERNAL pThis = (PRTSEMMUTEXINTERNAL)RTMemAllocZ(sizeof(*pThis));
+    if (pThis)
+    {
+        pThis->u32Magic = RTSEMMUTEX_MAGIC;
+        sx_init_flags(&pThis->SxLock, "IPRT Mutex Semaphore", SX_RECURSE);
+
+        *phMutexSem = pThis;
+        return VINF_SUCCESS;
+    }
+    return VERR_NO_MEMORY;
+}
+
+
+RTDECL(int)  RTSemMutexDestroy(RTSEMMUTEX hMutexSem)
+{
+    PRTSEMMUTEXINTERNAL pThis = hMutexSem;
+    if (pThis == NIL_RTSEMMUTEX)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    AssertReturn(ASMAtomicCmpXchgU32(&pThis->u32Magic, RTSEMMUTEX_MAGIC_DEAD, RTSEMMUTEX_MAGIC), VERR_INVALID_HANDLE);
+
+    sx_destroy(&pThis->SxLock);
+    RTMemFree(pThis);
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemMutexRequest(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies)
+{
+    PRTSEMMUTEXINTERNAL pThis = hMutexSem;
+    int                 rc;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    if (cMillies == RT_INDEFINITE_WAIT)
+    {
+        sx_xlock(&pThis->SxLock);
+        rc = VINF_SUCCESS;
+    }
+    else if (!cMillies)
+    {
+        if (sx_try_xlock(&pThis->SxLock))
+            rc = VINF_SUCCESS;
+        else
+            rc = VERR_TIMEOUT;
+    }
+    /*
+     * GROSS HACK: poll implementation of timeout.
+     */
+    /** @todo Implement timeouts in RTSemMutexRequest. */
+    else if (sx_try_xlock(&pThis->SxLock))
+        rc = VINF_SUCCESS;
+    else
+    {
+        uint64_t StartTS = RTTimeSystemMilliTS();
+        rc = VERR_TIMEOUT;
+        do
+        {
+            RTThreadSleep(1);
+            if (sx_try_xlock(&pThis->SxLock))
+            {
+                rc = VINF_SUCCESS;
+                break;
+            }
+        } while (RTTimeSystemMilliTS() - StartTS < cMillies);
+    }
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTSemMutexRequestDebug(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    return RTSemMutexRequest(hMutexSem, cMillies);
+}
+
+
+RTDECL(int)  RTSemMutexRequestNoResume(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies)
+{
+    PRTSEMMUTEXINTERNAL pThis = hMutexSem;
+    int                 rc;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    if (cMillies == RT_INDEFINITE_WAIT)
+    {
+        if (!sx_xlock_sig(&pThis->SxLock))
+            rc = VINF_SUCCESS;
+        else
+            rc = VERR_INTERRUPTED;
+    }
+    else if (!cMillies)
+    {
+        if (sx_try_xlock(&pThis->SxLock))
+            rc = VINF_SUCCESS;
+        else
+            rc = VERR_TIMEOUT;
+    }
+    /*
+     * GROSS HACK: poll implementation of timeout.
+     */
+    /** @todo Implement timeouts and interrupt checks in
+     *        RTSemMutexRequestNoResume. */
+    else if (sx_try_xlock(&pThis->SxLock))
+        rc = VINF_SUCCESS;
+    else
+    {
+        uint64_t StartTS = RTTimeSystemMilliTS();
+        rc = VERR_TIMEOUT;
+        do
+        {
+            RTThreadSleep(1);
+            if (sx_try_xlock(&pThis->SxLock))
+            {
+                rc = VINF_SUCCESS;
+                break;
+            }
+        } while (RTTimeSystemMilliTS() - StartTS < cMillies);
+    }
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTSemMutexRequestNoResumeDebug(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    return RTSemMutexRequestNoResume(hMutexSem, cMillies);
+}
+
+
+RTDECL(int)  RTSemMutexRelease(RTSEMMUTEX hMutexSem)
+{
+    PRTSEMMUTEXINTERNAL pThis = hMutexSem;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    sx_xunlock(&pThis->SxLock);
+    return VINF_SUCCESS;
+}
+
+
+
+RTDECL(bool) RTSemMutexIsOwned(RTSEMMUTEX hMutexSem)
+{
+    PRTSEMMUTEXINTERNAL pThis = hMutexSem;
+    AssertPtrReturn(pThis, false);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), false);
+
+    return sx_xlocked(&pThis->SxLock);
+}
+
diff --git a/src/VBox/Runtime/r0drv/freebsd/sleepqueue-r0drv-freebsd.h b/src/VBox/Runtime/r0drv/freebsd/sleepqueue-r0drv-freebsd.h
new file mode 100644
index 00000000..dd13d487
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/freebsd/sleepqueue-r0drv-freebsd.h
@@ -0,0 +1,334 @@
+/* $Id: sleepqueue-r0drv-freebsd.h $ */
+/** @file
+ * IPRT - FreeBSD Ring-0 Driver Helpers for Abstracting Sleep Queues,
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+#ifndef IPRT_INCLUDED_SRC_r0drv_freebsd_sleepqueue_r0drv_freebsd_h
+#define IPRT_INCLUDED_SRC_r0drv_freebsd_sleepqueue_r0drv_freebsd_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include "the-freebsd-kernel.h"
+
+#include <iprt/asm-math.h>
+#include <iprt/err.h>
+#include <iprt/string.h>
+#include <iprt/time.h>
+
+/**
+ * Kernel mode FreeBSD wait state structure.
+ */
+typedef struct RTR0SEMBSDSLEEP
+{
+    /** The absolute timeout given as nano seconds since the start of the
+     *  monotonic clock. */
+    uint64_t        uNsAbsTimeout;
+    /** The timeout in ticks. Updated after waiting. */
+    int             iTimeout;
+    /** Set if it's an indefinite wait. */
+    bool            fIndefinite;
+    /** Set if we've already timed out.
+     * Set by rtR0SemBsdWaitDoIt and read by rtR0SemBsdWaitHasTimedOut. */
+    bool            fTimedOut;
+    /** Flag whether the wait was interrupted. */
+    bool            fInterrupted;
+    /** flag whether the wait is interruptible or not. */
+    bool            fInterruptible;
+    /** Opaque wait channel id. */
+    void            *pvWaitChan;
+} RTR0SEMBSDSLEEP;
+/** Pointer to a FreeBSD wait state. */
+typedef RTR0SEMBSDSLEEP *PRTR0SEMBSDSLEEP;
+
+
+/**
+ * Updates the timeout of the FreeBSD wait.
+ *
+ * @returns RTSEMWAIT_FLAGS_INDEFINITE if the timeout value is too big.
+ *          0 otherwise
+ * @param   pWait               The wait structure.
+ * @param   uTimeout            The relative timeout in nanoseconds.
+ */
+DECLINLINE(uint32_t) rtR0SemBsdWaitUpdateTimeout(PRTR0SEMBSDSLEEP pWait, uint64_t uTimeout)
+{
+#if 0
+    struct timeval tv;
+
+    tv.tv_sec = uTimeout / UINT64_C(1000000000);
+    tv.tv_usec = (uTimeout % UINT64_C(1000000000)) / UINT64_C(1000);
+
+    pWait->iTimeout = tvtohz(&tv);
+#else
+    uint64_t cTicks = ASMMultU64ByU32DivByU32(uTimeout, hz, UINT32_C(1000000000));
+    if (cTicks >= INT_MAX)
+        return RTSEMWAIT_FLAGS_INDEFINITE;
+    else
+        pWait->iTimeout     = (int)cTicks;
+#endif
+
+    return 0;
+}
+
+/**
+ * Initializes a wait.
+ *
+ * The caller MUST check the wait condition BEFORE calling this function or the
+ * timeout logic will be flawed.
+ *
+ * @returns VINF_SUCCESS or VERR_TIMEOUT.
+ * @param   pWait               The wait structure.
+ * @param   fFlags              The wait flags.
+ * @param   uTimeout            The timeout.
+ * @param   pvWaitChan          The opaque wait channel.
+ */
+DECLINLINE(int) rtR0SemBsdWaitInit(PRTR0SEMBSDSLEEP pWait, uint32_t fFlags, uint64_t uTimeout,
+                                   void *pvWaitChan)
+{
+    pWait->iTimeout = 0;
+    pWait->uNsAbsTimeout = 0; /* shut up gcc */
+
+    /*
+     * Process the flags and timeout.
+     */
+    if (!(fFlags & RTSEMWAIT_FLAGS_INDEFINITE))
+    {
+/** @todo optimize: millisecs -> nanosecs -> millisec -> jiffies */
+        if (fFlags & RTSEMWAIT_FLAGS_MILLISECS)
+            uTimeout = uTimeout < UINT64_MAX / UINT32_C(1000000) * UINT32_C(1000000)
+                     ? uTimeout * UINT32_C(1000000)
+                     : UINT64_MAX;
+        if (uTimeout == UINT64_MAX)
+            fFlags |= RTSEMWAIT_FLAGS_INDEFINITE;
+        else
+        {
+            uint64_t u64Now;
+            if (fFlags & RTSEMWAIT_FLAGS_RELATIVE)
+            {
+                if (uTimeout == 0)
+                    return VERR_TIMEOUT;
+
+                u64Now = RTTimeSystemNanoTS();
+                if (u64Now + uTimeout < u64Now) /* overflow */
+                    fFlags |= RTSEMWAIT_FLAGS_INDEFINITE;
+                else
+                    pWait->uNsAbsTimeout = u64Now + uTimeout;
+            }
+            else
+            {
+                u64Now = RTTimeSystemNanoTS();
+                if (u64Now >= uTimeout)
+                    return VERR_TIMEOUT;
+
+                pWait->uNsAbsTimeout = uTimeout;
+                uTimeout -= u64Now; /* Get a relative value. */
+            }
+        }
+    }
+
+    if (!(fFlags & RTSEMWAIT_FLAGS_INDEFINITE))
+    {
+        pWait->fIndefinite      = false;
+        fFlags |= rtR0SemBsdWaitUpdateTimeout(pWait, uTimeout);
+    }
+
+    if (fFlags & RTSEMWAIT_FLAGS_INDEFINITE)
+    {
+        pWait->fIndefinite      = true;
+        pWait->iTimeout         = INT_MAX;
+        pWait->uNsAbsTimeout    = UINT64_MAX;
+    }
+
+    pWait->fTimedOut   = false;
+
+    /*
+     * Initialize the wait queue related bits.
+     */
+    pWait->fInterruptible = fFlags & RTSEMWAIT_FLAGS_INTERRUPTIBLE
+                            ? true : false;
+    pWait->pvWaitChan     = pvWaitChan;
+    pWait->fInterrupted   = false;
+
+    return VINF_SUCCESS;
+}
+
+/**
+ * Prepares the next wait.
+ *
+ * This must be called before rtR0SemBsdWaitDoIt, and the caller should check
+ * the exit conditions inbetween the two calls.
+ *
+ * @param   pWait               The wait structure.
+ */
+DECLINLINE(void) rtR0SemBsdWaitPrepare(PRTR0SEMBSDSLEEP pWait)
+{
+    /* Lock the queues. */
+    sleepq_lock(pWait->pvWaitChan);
+}
+
+/**
+ * Do the actual wait.
+ *
+ * @param   pWait               The wait structure.
+ */
+DECLINLINE(void) rtR0SemBsdWaitDoIt(PRTR0SEMBSDSLEEP pWait)
+{
+    int rcBsd;
+    int fSleepqFlags = SLEEPQ_CONDVAR;
+
+    if (pWait->fInterruptible)
+        fSleepqFlags |= SLEEPQ_INTERRUPTIBLE;
+
+    sleepq_add(pWait->pvWaitChan, NULL, "VBoxIS", fSleepqFlags, 0);
+
+    if (!pWait->fIndefinite)
+    {
+        sleepq_set_timeout(pWait->pvWaitChan, pWait->iTimeout);
+
+        if (pWait->fInterruptible)
+            rcBsd = SLEEPQ_TIMEDWAIT_SIG(pWait->pvWaitChan);
+        else
+            rcBsd = SLEEPQ_TIMEDWAIT(pWait->pvWaitChan);
+    }
+    else
+    {
+        if (pWait->fInterruptible)
+            rcBsd = SLEEPQ_WAIT_SIG(pWait->pvWaitChan);
+        else
+        {
+            rcBsd = 0;
+            SLEEPQ_WAIT(pWait->pvWaitChan);
+        }
+    }
+
+    switch (rcBsd)
+    {
+        case 0:
+            break;
+        case ERESTART:
+        {
+            if (!pWait->fIndefinite)
+            {
+                /* Recalc timeout. */
+                uint64_t u64Now = RTTimeSystemNanoTS();
+                if (u64Now >= pWait->uNsAbsTimeout)
+                    pWait->fTimedOut = true;
+                else
+                {
+                    u64Now = pWait->uNsAbsTimeout - u64Now;
+                    rtR0SemBsdWaitUpdateTimeout(pWait, u64Now);
+                }
+            }
+            break;
+        }
+        case EWOULDBLOCK:
+            pWait->fTimedOut = true;
+            break;
+        case EINTR:
+            Assert(pWait->fInterruptible);
+            pWait->fInterrupted = true;
+            break;
+        default:
+            AssertMsgFailed(("sleepq_* -> %d\n", rcBsd));
+            break;
+    }
+}
+
+
+/**
+ * Checks if a FreeBSD wait was interrupted.
+ *
+ * @returns true / false
+ * @param   pWait               The wait structure.
+ * @remarks This shall be called before the first rtR0SemBsdWaitDoIt().
+ */
+DECLINLINE(bool) rtR0SemBsdWaitWasInterrupted(PRTR0SEMBSDSLEEP pWait)
+{
+    return pWait->fInterrupted;
+}
+
+
+/**
+ * Checks if a FreeBSD wait has timed out.
+ *
+ * @returns true / false
+ * @param   pWait               The wait structure.
+ */
+DECLINLINE(bool) rtR0SemBsdWaitHasTimedOut(PRTR0SEMBSDSLEEP pWait)
+{
+    return pWait->fTimedOut;
+}
+
+
+/**
+ * Deletes a FreeBSD wait.
+ *
+ * @param   pWait               The wait structure.
+ */
+DECLINLINE(void) rtR0SemBsdWaitDelete(PRTR0SEMBSDSLEEP pWait)
+{
+    sleepq_release(pWait->pvWaitChan);
+}
+
+
+/**
+ * Signals the wait channel.
+ *
+ * @param  pvWaitChan           The opaque wait channel handle.
+ */
+DECLINLINE(void) rtR0SemBsdSignal(void *pvWaitChan)
+{
+    sleepq_lock(pvWaitChan);
+    int fWakeupSwapProc = sleepq_signal(pvWaitChan, SLEEPQ_CONDVAR, 0, 0);
+    sleepq_release(pvWaitChan);
+    if (fWakeupSwapProc)
+        kick_proc0();
+}
+
+/**
+ * Wakes up all waiters on the wait channel.
+ *
+ * @param  pvWaitChan           The opaque wait channel handle.
+ */
+DECLINLINE(void) rtR0SemBsdBroadcast(void *pvWaitChan)
+{
+    sleepq_lock(pvWaitChan);
+    sleepq_broadcast(pvWaitChan, SLEEPQ_CONDVAR, 0, 0);
+#if __FreeBSD_version >= 800000 /* Broadcast releases the sleep queue lock on FreeBSD 7.x */
+    sleepq_release(pvWaitChan);
+#endif
+}
+
+/**
+ * Gets the max resolution of the timeout machinery.
+ *
+ * @returns Resolution specified in nanoseconds.
+ */
+DECLINLINE(uint32_t) rtR0SemBsdWaitGetResolution(void)
+{
+    return 1000000000 / hz; /* ns */
+}
+
+#endif /* !IPRT_INCLUDED_SRC_r0drv_freebsd_sleepqueue_r0drv_freebsd_h */
+
diff --git a/src/VBox/Runtime/r0drv/freebsd/spinlock-r0drv-freebsd.c b/src/VBox/Runtime/r0drv/freebsd/spinlock-r0drv-freebsd.c
new file mode 100644
index 00000000..d5d56188
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/freebsd/spinlock-r0drv-freebsd.c
@@ -0,0 +1,234 @@
+/* $Id: spinlock-r0drv-freebsd.c $ */
+/** @file
+ * IPRT - Spinlocks, Ring-0 Driver, FreeBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-freebsd-kernel.h"
+#include "internal/iprt.h"
+
+#include <iprt/spinlock.h>
+#include <iprt/errcore.h>
+#include <iprt/alloc.h>
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+#include <iprt/asm-amd64-x86.h>
+#include <iprt/thread.h>
+#include <iprt/mp.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Wrapper for the struct mtx type.
+ */
+typedef struct RTSPINLOCKINTERNAL
+{
+    /** Spinlock magic value (RTSPINLOCK_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** The spinlock. */
+    uint32_t volatile   fLocked;
+    /** Saved interrupt flag. */
+    uint32_t volatile   fIntSaved;
+    /** The spinlock creation flags. */
+    uint32_t            fFlags;
+#ifdef RT_MORE_STRICT
+    /** The idAssertCpu variable before acquring the lock for asserting after
+     *  releasing the spinlock. */
+    RTCPUID volatile    idAssertCpu;
+    /** The CPU that owns the lock. */
+    RTCPUID volatile    idCpuOwner;
+#endif
+} RTSPINLOCKINTERNAL, *PRTSPINLOCKINTERNAL;
+
+
+RTDECL(int)  RTSpinlockCreate(PRTSPINLOCK pSpinlock, uint32_t fFlags, const char *pszName)
+{
+    RT_ASSERT_PREEMPTIBLE();
+    AssertReturn(fFlags == RTSPINLOCK_FLAGS_INTERRUPT_SAFE || fFlags == RTSPINLOCK_FLAGS_INTERRUPT_UNSAFE, VERR_INVALID_PARAMETER);
+
+    /*
+     * Allocate.
+     */
+    AssertCompile(sizeof(RTSPINLOCKINTERNAL) > sizeof(void *));
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)RTMemAllocZ(sizeof(*pThis));
+    if (!pThis)
+        return VERR_NO_MEMORY;
+
+    /*
+     * Initialize & return.
+     */
+    pThis->u32Magic  = RTSPINLOCK_MAGIC;
+    pThis->fLocked   = 0;
+    pThis->fFlags    = fFlags;
+    pThis->fIntSaved = 0;
+
+    *pSpinlock = pThis;
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSpinlockDestroy(RTSPINLOCK Spinlock)
+{
+    /*
+     * Validate input.
+     */
+    RT_ASSERT_INTS_ON();
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
+    if (!pThis)
+        return VERR_INVALID_PARAMETER;
+    AssertMsgReturn(pThis->u32Magic == RTSPINLOCK_MAGIC,
+                    ("Invalid spinlock %p magic=%#x\n", pThis, pThis->u32Magic),
+                    VERR_INVALID_PARAMETER);
+
+    /*
+     * Make the lock invalid and release the memory.
+     */
+    ASMAtomicIncU32(&pThis->u32Magic);
+    RTMemFree(pThis);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(void) RTSpinlockAcquire(RTSPINLOCK Spinlock)
+{
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
+    RT_ASSERT_PREEMPT_CPUID_VAR();
+    AssertPtr(pThis);
+    Assert(pThis->u32Magic == RTSPINLOCK_MAGIC);
+
+    if (pThis->fFlags & RTSPINLOCK_FLAGS_INTERRUPT_SAFE)
+    {
+        for (;;)
+        {
+            uint32_t fIntSaved = ASMIntDisableFlags();
+            critical_enter();
+
+            int c = 50;
+            for (;;)
+            {
+                if (ASMAtomicCmpXchgU32(&pThis->fLocked, 1, 0))
+                {
+                    RT_ASSERT_PREEMPT_CPUID_SPIN_ACQUIRED(pThis);
+                    pThis->fIntSaved = fIntSaved;
+                    return;
+                }
+                if (--c <= 0)
+                    break;
+                cpu_spinwait();
+            }
+
+            /* Enable interrupts while we sleep. */
+            ASMSetFlags(fIntSaved);
+            critical_exit();
+            DELAY(1);
+        }
+    }
+    else
+    {
+        for (;;)
+        {
+            critical_enter();
+
+            int c = 50;
+            for (;;)
+            {
+                if (ASMAtomicCmpXchgU32(&pThis->fLocked, 1, 0))
+                {
+                    RT_ASSERT_PREEMPT_CPUID_SPIN_ACQUIRED(pThis);
+                    return;
+                }
+                if (--c <= 0)
+                    break;
+                cpu_spinwait();
+            }
+
+            critical_exit();
+            DELAY(1);
+        }
+    }
+}
+
+
+RTDECL(void) RTSpinlockRelease(RTSPINLOCK Spinlock)
+{
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
+    RT_ASSERT_PREEMPT_CPUID_SPIN_RELEASE_VARS();
+
+    AssertPtr(pThis);
+    Assert(pThis->u32Magic == RTSPINLOCK_MAGIC);
+    RT_ASSERT_PREEMPT_CPUID_SPIN_RELEASE(pThis);
+
+    if (pThis->fFlags & RTSPINLOCK_FLAGS_INTERRUPT_SAFE)
+    {
+        uint32_t fIntSaved = pThis->fIntSaved;
+        pThis->fIntSaved = 0;
+        if (ASMAtomicCmpXchgU32(&pThis->fLocked, 0, 1))
+            ASMSetFlags(fIntSaved);
+        else
+            AssertMsgFailed(("Spinlock %p was not locked!\n", pThis));
+    }
+    else
+    {
+        if (!ASMAtomicCmpXchgU32(&pThis->fLocked, 0, 1))
+            AssertMsgFailed(("Spinlock %p was not locked!\n", pThis));
+    }
+
+    critical_exit();
+}
+
diff --git a/src/VBox/Runtime/r0drv/freebsd/the-freebsd-kernel.h b/src/VBox/Runtime/r0drv/freebsd/the-freebsd-kernel.h
new file mode 100644
index 00000000..01d89963
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/freebsd/the-freebsd-kernel.h
@@ -0,0 +1,160 @@
+/* $Id: the-freebsd-kernel.h $ */
+/** @file
+ * IPRT - Ring-0 Driver, The FreeBSD Kernel Headers.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef IPRT_INCLUDED_SRC_r0drv_freebsd_the_freebsd_kernel_h
+#define IPRT_INCLUDED_SRC_r0drv_freebsd_the_freebsd_kernel_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <iprt/types.h>
+
+/* Deal with conflicts first. */
+#include <sys/param.h>
+#undef PVM
+#include <sys/bus.h>
+#include <sys/types.h>
+#include <sys/errno.h>
+#include <sys/kernel.h>
+#include <sys/uio.h>
+#include <sys/libkern.h>
+#include <sys/systm.h>
+#include <sys/malloc.h>
+#include <sys/pcpu.h>
+#include <sys/proc.h>
+#include <sys/limits.h>
+#include <sys/unistd.h>
+#include <sys/kthread.h>
+#include <sys/lock.h>
+#if __FreeBSD_version >= 1000030
+#include <sys/rwlock.h>
+#endif
+#include <sys/mutex.h>
+#include <sys/sched.h>
+#include <sys/callout.h>
+#include <sys/cpu.h>
+#include <sys/smp.h>
+#include <sys/sleepqueue.h>
+#include <sys/sx.h>
+#include <vm/vm.h>
+#include <vm/pmap.h>            /* for vtophys */
+#include <vm/vm_map.h>
+#include <vm/vm_object.h>
+#include <vm/vm_kern.h>
+#include <vm/vm_param.h>        /* KERN_SUCCESS ++ */
+#include <vm/vm_page.h>
+#include <vm/vm_phys.h>         /* vm_phys_alloc_* */
+#include <vm/vm_extern.h>       /* kmem_alloc_attr */
+#include <vm/vm_pageout.h>      /* vm_contig_grow_cache */
+#include <sys/vmmeter.h>        /* cnt */
+#include <sys/resourcevar.h>
+#include <machine/cpu.h>
+
+/**
+ * Wrappers around the sleepq_ KPI.
+ */
+#if __FreeBSD_version >= 800026
+# define SLEEPQ_TIMEDWAIT(EventInt) sleepq_timedwait(EventInt, 0)
+# define SLEEPQ_TIMEDWAIT_SIG(EventInt) sleepq_timedwait_sig(EventInt, 0)
+# define SLEEPQ_WAIT(EventInt) sleepq_wait(EventInt, 0)
+# define SLEEPQ_WAIT_SIG(EventInt) sleepq_wait_sig(EventInt, 0)
+#else
+# define SLEEPQ_TIMEDWAIT(EventInt) sleepq_timedwait(EventInt)
+# define SLEEPQ_TIMEDWAIT_SIG(EventInt) sleepq_timedwait_sig(EventInt)
+# define SLEEPQ_WAIT(EventInt) sleepq_wait(EventInt)
+# define SLEEPQ_WAIT_SIG(EventInt) sleepq_wait_sig(EventInt)
+#endif
+
+/**
+ * Our pmap_enter version
+ */
+#if __FreeBSD_version >= 701105
+# define MY_PMAP_ENTER(pPhysMap, AddrR3, pPage, fProt, fWired) \
+    pmap_enter(pPhysMap, AddrR3, VM_PROT_NONE, pPage, fProt, fWired)
+#else
+# define MY_PMAP_ENTER(pPhysMap, AddrR3, pPage, fProt, fWired) \
+    pmap_enter(pPhysMap, AddrR3, pPage, fProt, fWired)
+#endif
+
+/**
+ * The VM object lock/unlock wrappers for older kernels.
+ */
+#if __FreeBSD_version < 1000030
+# define VM_OBJECT_WLOCK(a_pObject) VM_OBJECT_LOCK((a_pObject))
+# define VM_OBJECT_WUNLOCK(a_pObject) VM_OBJECT_UNLOCK((a_pObject))
+#endif
+
+#if __FreeBSD_version >= 1100077
+# define MY_LIM_MAX_PROC(a_pProc, a_Limit) lim_max_proc((a_pProc), (a_Limit))
+#else
+# define MY_LIM_MAX_PROC(a_pProc, a_Limit) lim_max((a_pProc), (a_Limit))
+#endif
+
+/**
+ * Check whether we can use kmem_alloc_attr for low allocs.
+ */
+#if    (__FreeBSD_version >= 900011) \
+    || (__FreeBSD_version < 900000 && __FreeBSD_version >= 800505) \
+    || (__FreeBSD_version < 800000 && __FreeBSD_version >= 703101)
+# define USE_KMEM_ALLOC_ATTR
+#endif
+
+/**
+ * Check whether we can use kmem_alloc_prot.
+ */
+#if 0 /** @todo Not available yet. */
+# define USE_KMEM_ALLOC_PROT
+#endif
+
+#endif /* !IPRT_INCLUDED_SRC_r0drv_freebsd_the_freebsd_kernel_h */
diff --git a/src/VBox/Runtime/r0drv/freebsd/thread-r0drv-freebsd.c b/src/VBox/Runtime/r0drv/freebsd/thread-r0drv-freebsd.c
new file mode 100644
index 00000000..cbae13fa
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/freebsd/thread-r0drv-freebsd.c
@@ -0,0 +1,186 @@
+/* $Id: thread-r0drv-freebsd.c $ */
+/** @file
+ * IPRT - Threads (Part 1), Ring-0 Driver, FreeBSD.
+ */
+
+/*
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-freebsd-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/thread.h>
+
+#include <iprt/asm.h>
+#include <iprt/asm-amd64-x86.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/mp.h>
+#include "internal/thread.h"
+
+
+RTDECL(RTNATIVETHREAD) RTThreadNativeSelf(void)
+{
+    return (RTNATIVETHREAD)curthread;
+}
+
+
+static int rtR0ThreadFbsdSleepCommon(RTMSINTERVAL cMillies)
+{
+    int rc;
+    int cTicks;
+
+    /*
+     * 0 ms sleep -> yield.
+     */
+    if (!cMillies)
+    {
+        RTThreadYield();
+        return VINF_SUCCESS;
+    }
+
+    /*
+     * Translate milliseconds into ticks and go to sleep.
+     */
+    if (cMillies != RT_INDEFINITE_WAIT)
+    {
+        if (hz == 1000)
+            cTicks = cMillies;
+        else if (hz == 100)
+            cTicks = cMillies / 10;
+        else
+        {
+            int64_t cTicks64 = ((uint64_t)cMillies * hz) / 1000;
+            cTicks = (int)cTicks64;
+            if (cTicks != cTicks64)
+                cTicks = INT_MAX;
+        }
+    }
+    else
+        cTicks = 0;     /* requires giant lock! */
+
+    rc = tsleep((void *)RTThreadSleep,
+                PZERO | PCATCH,
+                "iprtsl",           /* max 6 chars */
+                cTicks);
+    switch (rc)
+    {
+        case 0:
+            return VINF_SUCCESS;
+        case EWOULDBLOCK:
+            return VERR_TIMEOUT;
+        case EINTR:
+        case ERESTART:
+            return VERR_INTERRUPTED;
+        default:
+            AssertMsgFailed(("%d\n", rc));
+            return VERR_NO_TRANSLATION;
+    }
+}
+
+
+RTDECL(int) RTThreadSleep(RTMSINTERVAL cMillies)
+{
+    return rtR0ThreadFbsdSleepCommon(cMillies);
+}
+
+
+RTDECL(int) RTThreadSleepNoLog(RTMSINTERVAL cMillies)
+{
+    return rtR0ThreadFbsdSleepCommon(cMillies);
+}
+
+
+RTDECL(bool) RTThreadYield(void)
+{
+#if __FreeBSD_version >= 900032
+    kern_yield(curthread->td_user_pri);
+#else
+    uio_yield();
+#endif
+    return false; /** @todo figure this one ... */
+}
+
+
+RTDECL(bool) RTThreadPreemptIsEnabled(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD);
+
+    return curthread->td_critnest == 0
+        && ASMIntAreEnabled(); /** @todo is there a native freebsd function/macro for this? */
+}
+
+
+RTDECL(bool) RTThreadPreemptIsPending(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD);
+
+    return curthread->td_owepreempt == 1;
+}
+
+
+RTDECL(bool) RTThreadPreemptIsPendingTrusty(void)
+{
+    /* yes, RTThreadPreemptIsPending is reliable. */
+    return true;
+}
+
+
+RTDECL(bool) RTThreadPreemptIsPossible(void)
+{
+    /* yes, kernel preemption is possible. */
+    return true;
+}
+
+
+RTDECL(void) RTThreadPreemptDisable(PRTTHREADPREEMPTSTATE pState)
+{
+    AssertPtr(pState);
+    Assert(pState->u32Reserved == 0);
+    pState->u32Reserved = 42;
+
+    critical_enter();
+    RT_ASSERT_PREEMPT_CPUID_DISABLE(pState);
+}
+
+
+RTDECL(void) RTThreadPreemptRestore(PRTTHREADPREEMPTSTATE pState)
+{
+    AssertPtr(pState);
+    Assert(pState->u32Reserved == 42);
+    pState->u32Reserved = 0;
+
+    RT_ASSERT_PREEMPT_CPUID_RESTORE(pState);
+    critical_exit();
+}
+
+
+RTDECL(bool) RTThreadIsInInterrupt(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD); NOREF(hThread);
+    /** @todo FreeBSD: Implement RTThreadIsInInterrupt. Required for guest
+     *        additions! */
+    return !ASMIntAreEnabled();
+}
+
diff --git a/src/VBox/Runtime/r0drv/freebsd/thread2-r0drv-freebsd.c b/src/VBox/Runtime/r0drv/freebsd/thread2-r0drv-freebsd.c
new file mode 100644
index 00000000..d46f1d61
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/freebsd/thread2-r0drv-freebsd.c
@@ -0,0 +1,179 @@
+/* $Id: thread2-r0drv-freebsd.c $ */
+/** @file
+ * IPRT - Threads (Part 2), Ring-0 Driver, FreeBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-freebsd-kernel.h"
+
+#include <iprt/thread.h>
+#include <iprt/errcore.h>
+#include <iprt/assert.h>
+
+#include "internal/thread.h"
+
+
+DECLHIDDEN(int) rtThreadNativeInit(void)
+{
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(RTTHREAD) RTThreadSelf(void)
+{
+    return rtThreadGetByNative(RTThreadNativeSelf());
+}
+
+
+DECLHIDDEN(int) rtThreadNativeSetPriority(PRTTHREADINT pThread, RTTHREADTYPE enmType)
+{
+    int iPriority;
+
+    switch (enmType)
+    {
+        case RTTHREADTYPE_INFREQUENT_POLLER:    iPriority = PZERO + 8;      break;
+        case RTTHREADTYPE_EMULATION:            iPriority = PZERO + 4;      break;
+        case RTTHREADTYPE_DEFAULT:              iPriority = PZERO;          break;
+        case RTTHREADTYPE_MSG_PUMP:             iPriority = PZERO - 4;      break;
+        case RTTHREADTYPE_IO:                   iPriority = PRIBIO;         break;
+        case RTTHREADTYPE_TIMER:                iPriority = PRI_MIN_KERN;   break;
+        default:
+            AssertMsgFailed(("enmType=%d\n", enmType));
+            return VERR_INVALID_PARAMETER;
+    }
+
+#if __FreeBSD_version < 700000
+    /* Do like they're doing in subr_ntoskrnl.c... */
+    mtx_lock_spin(&sched_lock);
+#else
+    thread_lock(curthread);
+#endif
+    sched_prio(curthread, iPriority);
+#if __FreeBSD_version < 600000
+    curthread->td_base_pri = iPriority;
+#endif
+#if __FreeBSD_version < 700000
+    mtx_unlock_spin(&sched_lock);
+#else
+    thread_unlock(curthread);
+#endif
+
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtThreadNativeAdopt(PRTTHREADINT pThread)
+{
+    NOREF(pThread);
+    /* There is nothing special that needs doing here, but the
+       user really better know what he's cooking. */
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(void) rtThreadNativeWaitKludge(PRTTHREADINT pThread)
+{
+    /** @todo fix RTThreadWait/RTR0Term race on freebsd. */
+    RTThreadSleep(1);
+}
+
+
+DECLHIDDEN(void) rtThreadNativeDestroy(PRTTHREADINT pThread)
+{
+    NOREF(pThread);
+}
+
+
+/**
+ * Native thread main function.
+ *
+ * @param   pvThreadInt     The thread structure.
+ */
+static void rtThreadNativeMain(void *pvThreadInt)
+{
+    const struct thread *Self = curthread;
+    PRTTHREADINT pThreadInt = (PRTTHREADINT)pvThreadInt;
+    int rc;
+
+    rc = rtThreadMain(pThreadInt, (RTNATIVETHREAD)Self, &pThreadInt->szName[0]);
+
+#if __FreeBSD_version >= 800002
+    kproc_exit(rc);
+#else
+    kthread_exit(rc);
+#endif
+}
+
+
+DECLHIDDEN(int) rtThreadNativeCreate(PRTTHREADINT pThreadInt, PRTNATIVETHREAD pNativeThread)
+{
+    int rc;
+    struct proc *pProc;
+
+#if __FreeBSD_version >= 800002
+    rc = kproc_create(rtThreadNativeMain, pThreadInt, &pProc, RFHIGHPID, 0, "%s", pThreadInt->szName);
+#else
+    rc = kthread_create(rtThreadNativeMain, pThreadInt, &pProc, RFHIGHPID, 0, "%s", pThreadInt->szName);
+#endif
+    if (!rc)
+    {
+        *pNativeThread = (RTNATIVETHREAD)FIRST_THREAD_IN_PROC(pProc);
+        rc = VINF_SUCCESS;
+    }
+    else
+        rc = RTErrConvertFromErrno(rc);
+    return rc;
+}
+
diff --git a/src/VBox/Runtime/r0drv/freebsd/time-r0drv-freebsd.c b/src/VBox/Runtime/r0drv/freebsd/time-r0drv-freebsd.c
new file mode 100644
index 00000000..21a17733
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/freebsd/time-r0drv-freebsd.c
@@ -0,0 +1,98 @@
+/* $Id: time-r0drv-freebsd.c $ */
+/** @file
+ * IPRT - Time, Ring-0 Driver, FreeBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-freebsd-kernel.h"
+#define RTTIME_INCL_TIMESPEC
+
+#include <iprt/time.h>
+
+
+RTDECL(uint64_t) RTTimeNanoTS(void)
+{
+    struct timespec tsp;
+    nanouptime(&tsp);
+    return tsp.tv_sec * RT_NS_1SEC_64
+         + tsp.tv_nsec;
+}
+
+
+RTDECL(uint64_t) RTTimeMilliTS(void)
+{
+    return RTTimeNanoTS() / RT_NS_1MS;
+}
+
+
+RTDECL(uint64_t) RTTimeSystemNanoTS(void)
+{
+    return RTTimeNanoTS();
+}
+
+
+RTDECL(uint64_t) RTTimeSystemMilliTS(void)
+{
+    return RTTimeMilliTS();
+}
+
+
+RTDECL(PRTTIMESPEC) RTTimeNow(PRTTIMESPEC pTime)
+{
+    struct timespec tsp;
+    nanotime(&tsp);
+    return RTTimeSpecSetTimespec(pTime, &tsp);
+}
+
diff --git a/src/VBox/Runtime/r0drv/freebsd/timer-r0drv-freebsd.c b/src/VBox/Runtime/r0drv/freebsd/timer-r0drv-freebsd.c
new file mode 100644
index 00000000..80f99373
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/freebsd/timer-r0drv-freebsd.c
@@ -0,0 +1,310 @@
+/* $Id: timer-r0drv-freebsd.c $ */
+/** @file
+ * IPRT - Memory Allocation, Ring-0 Driver, FreeBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-freebsd-kernel.h"
+
+#include <iprt/timer.h>
+#include <iprt/time.h>
+#include <iprt/spinlock.h>
+#include <iprt/err.h>
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/alloc.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * The internal representation of an FreeBSD timer handle.
+ */
+typedef struct RTTIMER
+{
+    /** Magic.
+     * This is RTTIMER_MAGIC, but changes to something else before the timer
+     * is destroyed to indicate clearly that thread should exit. */
+    uint32_t volatile       u32Magic;
+    /** Flag indicating that the timer is suspended. */
+    uint8_t volatile        fSuspended;
+    /** Whether the timer must run on a specific CPU or not. */
+    uint8_t                 fSpecificCpu;
+    /** The CPU it must run on if fSpecificCpu is set. */
+    uint32_t                iCpu;
+    /** The FreeBSD callout structure. */
+    struct callout          Callout;
+    /** Callback. */
+    PFNRTTIMER              pfnTimer;
+    /** User argument. */
+    void                   *pvUser;
+    /** The timer interval. 0 if one-shot. */
+    uint64_t                u64NanoInterval;
+    /** The start of the current run.
+     * This is used to calculate when the timer ought to fire the next time. */
+    uint64_t volatile       u64StartTS;
+    /** The start of the current run.
+     * This is used to calculate when the timer ought to fire the next time. */
+    uint64_t volatile       u64NextTS;
+    /** The current tick number (since u64StartTS). */
+    uint64_t volatile       iTick;
+} RTTIMER;
+
+
+/*********************************************************************************************************************************
+*   Internal Functions                                                                                                           *
+*********************************************************************************************************************************/
+static void rtTimerFreeBSDCallback(void *pvTimer);
+
+
+
+RTDECL(int) RTTimerCreateEx(PRTTIMER *ppTimer, uint64_t u64NanoInterval, uint32_t fFlags, PFNRTTIMER pfnTimer, void *pvUser)
+{
+    *ppTimer = NULL;
+
+    /*
+     * Validate flags.
+     */
+    if (!RTTIMER_FLAGS_ARE_VALID(fFlags))
+        return VERR_INVALID_PARAMETER;
+    if (    (fFlags & RTTIMER_FLAGS_CPU_SPECIFIC)
+        &&  (fFlags & RTTIMER_FLAGS_CPU_ALL) != RTTIMER_FLAGS_CPU_ALL
+        &&  (fFlags & RTTIMER_FLAGS_CPU_MASK) > mp_maxid)
+        return VERR_CPU_NOT_FOUND;
+
+    /*
+     * Allocate and initialize the timer handle.
+     */
+    PRTTIMER pTimer = (PRTTIMER)RTMemAlloc(sizeof(*pTimer));
+    if (!pTimer)
+        return VERR_NO_MEMORY;
+
+    pTimer->u32Magic = RTTIMER_MAGIC;
+    pTimer->fSuspended = true;
+    pTimer->fSpecificCpu = !!(fFlags & RTTIMER_FLAGS_CPU_SPECIFIC);
+    pTimer->iCpu = fFlags & RTTIMER_FLAGS_CPU_MASK;
+    pTimer->pfnTimer = pfnTimer;
+    pTimer->pvUser = pvUser;
+    pTimer->u64NanoInterval = u64NanoInterval;
+    pTimer->u64StartTS = 0;
+    callout_init(&pTimer->Callout, CALLOUT_MPSAFE);
+
+    *ppTimer = pTimer;
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Validates the timer handle.
+ *
+ * @returns true if valid, false if invalid.
+ * @param   pTimer  The handle.
+ */
+DECLINLINE(bool) rtTimerIsValid(PRTTIMER pTimer)
+{
+    AssertReturn(VALID_PTR(pTimer), false);
+    AssertReturn(pTimer->u32Magic == RTTIMER_MAGIC, false);
+    return true;
+}
+
+
+RTDECL(int) RTTimerDestroy(PRTTIMER pTimer)
+{
+    /* It's ok to pass NULL pointer. */
+    if (pTimer == /*NIL_RTTIMER*/ NULL)
+        return VINF_SUCCESS;
+    if (!rtTimerIsValid(pTimer))
+        return VERR_INVALID_HANDLE;
+
+    /*
+     * Free the associated resources.
+     */
+    pTimer->u32Magic++;
+    callout_stop(&pTimer->Callout);
+    RTMemFree(pTimer);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTTimerStart(PRTTIMER pTimer, uint64_t u64First)
+{
+    struct timeval tv;
+
+    if (!rtTimerIsValid(pTimer))
+        return VERR_INVALID_HANDLE;
+    if (!pTimer->fSuspended)
+        return VERR_TIMER_ACTIVE;
+    if (   pTimer->fSpecificCpu
+        && !RTMpIsCpuOnline(RTMpCpuIdFromSetIndex(pTimer->iCpu)))
+        return VERR_CPU_OFFLINE;
+
+    /*
+     * Calc when it should start firing.
+     */
+    u64First += RTTimeNanoTS();
+
+    pTimer->fSuspended = false;
+    pTimer->iTick = 0;
+    pTimer->u64StartTS = u64First;
+    pTimer->u64NextTS = u64First;
+
+    tv.tv_sec  =  u64First / 1000000000;
+    tv.tv_usec = (u64First % 1000000000) / 1000;
+    callout_reset(&pTimer->Callout, tvtohz(&tv), rtTimerFreeBSDCallback, pTimer);
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTTimerStop(PRTTIMER pTimer)
+{
+    if (!rtTimerIsValid(pTimer))
+        return VERR_INVALID_HANDLE;
+    if (pTimer->fSuspended)
+        return VERR_TIMER_SUSPENDED;
+
+    /*
+     * Suspend the timer.
+     */
+    pTimer->fSuspended = true;
+    callout_stop(&pTimer->Callout);
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTTimerChangeInterval(PRTTIMER pTimer, uint64_t u64NanoInterval)
+{
+    if (!rtTimerIsValid(pTimer))
+        return VERR_INVALID_HANDLE;
+    return VERR_NOT_SUPPORTED;
+}
+
+
+/**
+ * smp_rendezvous action callback.
+ *
+ * This will perform the timer callback if we're on the right CPU.
+ *
+ * @param   pvTimer The timer.
+ */
+static void rtTimerFreeBSDIpiAction(void *pvTimer)
+{
+    PRTTIMER pTimer = (PRTTIMER)pvTimer;
+    if (    pTimer->iCpu == RTTIMER_FLAGS_CPU_MASK
+        ||  (u_int)pTimer->iCpu == curcpu)
+        pTimer->pfnTimer(pTimer, pTimer->pvUser, pTimer->iTick);
+}
+
+
+static void rtTimerFreeBSDCallback(void *pvTimer)
+{
+    PRTTIMER pTimer = (PRTTIMER)pvTimer;
+
+    /* calculate and set the next timeout */
+    pTimer->iTick++;
+    if (!pTimer->u64NanoInterval)
+    {
+        pTimer->fSuspended = true;
+        callout_stop(&pTimer->Callout);
+    }
+    else
+    {
+        struct timeval tv;
+        const uint64_t u64NanoTS = RTTimeNanoTS();
+        pTimer->u64NextTS = pTimer->u64StartTS + pTimer->iTick * pTimer->u64NanoInterval;
+        if (pTimer->u64NextTS < u64NanoTS)
+            pTimer->u64NextTS = u64NanoTS + RTTimerGetSystemGranularity() / 2;
+
+        tv.tv_sec = pTimer->u64NextTS / 1000000000;
+        tv.tv_usec = (pTimer->u64NextTS % 1000000000) / 1000;
+        callout_reset(&pTimer->Callout, tvtohz(&tv), rtTimerFreeBSDCallback, pTimer);
+    }
+
+    /* callback */
+    if (    !pTimer->fSpecificCpu
+        ||  pTimer->iCpu == curcpu)
+        pTimer->pfnTimer(pTimer, pTimer->pvUser, pTimer->iTick);
+    else
+        smp_rendezvous(NULL, rtTimerFreeBSDIpiAction, NULL, pvTimer);
+}
+
+
+RTDECL(uint32_t) RTTimerGetSystemGranularity(void)
+{
+    return 1000000000 / hz; /* ns */
+}
+
+
+RTDECL(int) RTTimerRequestSystemGranularity(uint32_t u32Request, uint32_t *pu32Granted)
+{
+    return VERR_NOT_SUPPORTED;
+}
+
+
+RTDECL(int) RTTimerReleaseSystemGranularity(uint32_t u32Granted)
+{
+    return VERR_NOT_SUPPORTED;
+}
+
+
+RTDECL(bool) RTTimerCanDoHighResolution(void)
+{
+    return false;
+}
+
diff --git a/src/VBox/Runtime/r0drv/generic/Makefile.kup b/src/VBox/Runtime/r0drv/generic/Makefile.kup
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/generic/Makefile.kup
diff --git a/src/VBox/Runtime/r0drv/generic/RTMpIsCpuWorkPending-r0drv-generic.cpp b/src/VBox/Runtime/r0drv/generic/RTMpIsCpuWorkPending-r0drv-generic.cpp
new file mode 100644
index 00000000..1d788e0c
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/generic/RTMpIsCpuWorkPending-r0drv-generic.cpp
@@ -0,0 +1,45 @@
+/* $Id: RTMpIsCpuWorkPending-r0drv-generic.cpp $ */
+/** @file
+ * IPRT - RTMpIsCpuWorkPending, Generic.
+ */
+
+/*
+ * Copyright (C) 2009-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/mp.h>
+#include "internal/iprt.h"
+
+
+/**
+ * Check if there's work (DPCs on Windows) pending on the current CPU.
+ *
+ * @return true if there's pending work on the current CPU, false otherwise.
+ */
+RTDECL(bool) RTMpIsCpuWorkPending(void)
+{
+    return false;
+}
+RT_EXPORT_SYMBOL(RTMpIsCpuWorkPending);
+
diff --git a/src/VBox/Runtime/r0drv/generic/RTMpOn-r0drv-generic.cpp b/src/VBox/Runtime/r0drv/generic/RTMpOn-r0drv-generic.cpp
new file mode 100644
index 00000000..20573f5e
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/generic/RTMpOn-r0drv-generic.cpp
@@ -0,0 +1,94 @@
+/* $Id: RTMpOn-r0drv-generic.cpp $ */
+/** @file
+ * IPRT - Multiprocessor, Ring-0 Driver, Generic Stubs.
+ */
+
+/*
+ * Copyright (C) 2008-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/mp.h>
+#include "internal/iprt.h"
+
+#include <iprt/errcore.h>
+
+
+RTDECL(int) RTMpOnAll(PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    NOREF(pfnWorker);
+    NOREF(pvUser1);
+    NOREF(pvUser2);
+    return VERR_NOT_SUPPORTED;
+}
+RT_EXPORT_SYMBOL(RTMpOnAll);
+
+
+RTDECL(bool) RTMpOnAllIsConcurrentSafe(void)
+{
+    return false;
+}
+RT_EXPORT_SYMBOL(RTMpOnAllIsConcurrentSafe);
+
+
+RTDECL(int) RTMpOnOthers(PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    NOREF(pfnWorker);
+    NOREF(pvUser1);
+    NOREF(pvUser2);
+    return VERR_NOT_SUPPORTED;
+}
+RT_EXPORT_SYMBOL(RTMpOnOthers);
+
+
+RTDECL(int) RTMpOnSpecific(RTCPUID idCpu, PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    NOREF(idCpu);
+    NOREF(pfnWorker);
+    NOREF(pvUser1);
+    NOREF(pvUser2);
+    return VERR_NOT_SUPPORTED;
+}
+RT_EXPORT_SYMBOL(RTMpOnSpecific);
+
+
+RTDECL(int) RTMpOnPair(RTCPUID idCpu1, RTCPUID idCpu2, uint32_t fFlags, PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    NOREF(idCpu1);
+    NOREF(idCpu2);
+    NOREF(fFlags);
+    NOREF(pfnWorker);
+    NOREF(pvUser1);
+    NOREF(pvUser2);
+    return VERR_NOT_SUPPORTED;
+}
+RT_EXPORT_SYMBOL(RTMpOnPair);
+
+
+
+RTDECL(bool) RTMpOnPairIsConcurrentExecSupported(void)
+{
+    return false;
+}
+RT_EXPORT_SYMBOL(RTMpOnPairIsConcurrentExecSupported);
+
diff --git a/src/VBox/Runtime/r0drv/generic/RTMpPokeCpu-r0drv-generic.cpp b/src/VBox/Runtime/r0drv/generic/RTMpPokeCpu-r0drv-generic.cpp
new file mode 100644
index 00000000..5c379408
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/generic/RTMpPokeCpu-r0drv-generic.cpp
@@ -0,0 +1,48 @@
+/* $Id: RTMpPokeCpu-r0drv-generic.cpp $ */
+/** @file
+ * IPRT - RTMpPokeCpu, Generic Implementation.
+ */
+
+/*
+ * Copyright (C) 2009-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/mp.h>
+#include "internal/iprt.h"
+
+
+static DECLCALLBACK(void) rtMpNtPokeCpuDummy(RTCPUID idCpu, void *pvUser1, void *pvUser2)
+{
+    NOREF(idCpu);
+    NOREF(pvUser1);
+    NOREF(pvUser2);
+}
+
+
+RTDECL(int) RTMpPokeCpu(RTCPUID idCpu)
+{
+    return RTMpOnSpecific(idCpu, rtMpNtPokeCpuDummy, NULL, NULL);
+}
+RT_EXPORT_SYMBOL(RTMpPokeCpu);
+
diff --git a/src/VBox/Runtime/r0drv/generic/RTThreadPreemptDisable-r0drv-generic.cpp b/src/VBox/Runtime/r0drv/generic/RTThreadPreemptDisable-r0drv-generic.cpp
new file mode 100644
index 00000000..6482acbd
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/generic/RTThreadPreemptDisable-r0drv-generic.cpp
@@ -0,0 +1,44 @@
+/* $Id: RTThreadPreemptDisable-r0drv-generic.cpp $ */
+/** @file
+ * IPRT - RTThreadPreemptDisable, Generic ring-0 driver implementation.
+ */
+
+/*
+ * Copyright (C) 2008-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/thread.h>
+#include "internal/iprt.h"
+
+#include <iprt/assert.h>
+
+
+RTDECL(void) RTThreadPreemptDisable(PRTTHREADPREEMPTSTATE pState)
+{
+    AssertPtr(pState);
+    Assert(pState->u32Reserved == 0);
+    pState->u32Reserved = 42;
+}
+RT_EXPORT_SYMBOL(RTThreadPreemptDisable);
+
diff --git a/src/VBox/Runtime/r0drv/generic/RTThreadPreemptIsEnabled-r0drv-generic.cpp b/src/VBox/Runtime/r0drv/generic/RTThreadPreemptIsEnabled-r0drv-generic.cpp
new file mode 100644
index 00000000..8fd15fc6
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/generic/RTThreadPreemptIsEnabled-r0drv-generic.cpp
@@ -0,0 +1,43 @@
+/* $Id: RTThreadPreemptIsEnabled-r0drv-generic.cpp $ */
+/** @file
+ * IPRT - RTThreadPreemptIsEnabled, Generic ring-0 driver implementation.
+ */
+
+/*
+ * Copyright (C) 2008-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/thread.h>
+#include "internal/iprt.h"
+
+#include <iprt/assert.h>
+
+
+RTDECL(bool) RTThreadPreemptIsEnabled(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD);
+    return true;
+}
+RT_EXPORT_SYMBOL(RTThreadPreemptIsEnabled);
+
diff --git a/src/VBox/Runtime/r0drv/generic/RTThreadPreemptIsPending-r0drv-generic.cpp b/src/VBox/Runtime/r0drv/generic/RTThreadPreemptIsPending-r0drv-generic.cpp
new file mode 100644
index 00000000..c896559d
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/generic/RTThreadPreemptIsPending-r0drv-generic.cpp
@@ -0,0 +1,43 @@
+/* $Id: RTThreadPreemptIsPending-r0drv-generic.cpp $ */
+/** @file
+ * IPRT - RTThreadPreemptIsPending, Generic ring-0 driver implementation.
+ */
+
+/*
+ * Copyright (C) 2008-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/thread.h>
+#include "internal/iprt.h"
+
+#include <iprt/assert.h>
+
+
+RTDECL(bool) RTThreadPreemptIsPending(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD);
+    return false;
+}
+RT_EXPORT_SYMBOL(RTThreadPreemptIsPending);
+
diff --git a/src/VBox/Runtime/r0drv/generic/RTThreadPreemptIsPendingTrusty-r0drv-generic.cpp b/src/VBox/Runtime/r0drv/generic/RTThreadPreemptIsPendingTrusty-r0drv-generic.cpp
new file mode 100644
index 00000000..1515ba90
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/generic/RTThreadPreemptIsPendingTrusty-r0drv-generic.cpp
@@ -0,0 +1,41 @@
+/* $Id: RTThreadPreemptIsPendingTrusty-r0drv-generic.cpp $ */
+/** @file
+ * IPRT - RTThreadPreemptIsPendingTrusty, Generic ring-0 driver implementation.
+ */
+
+/*
+ * Copyright (C) 2009-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/thread.h>
+#include "internal/iprt.h"
+
+
+RTDECL(bool) RTThreadPreemptIsPendingTrusty(void)
+{
+    /* no, RTThreadPreemptIsPending is not reliable. */
+    return false;
+}
+RT_EXPORT_SYMBOL(RTThreadPreemptIsPendingTrusty);
+
diff --git a/src/VBox/Runtime/r0drv/generic/RTThreadPreemptRestore-r0drv-generic.cpp b/src/VBox/Runtime/r0drv/generic/RTThreadPreemptRestore-r0drv-generic.cpp
new file mode 100644
index 00000000..1683f668
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/generic/RTThreadPreemptRestore-r0drv-generic.cpp
@@ -0,0 +1,44 @@
+/* $Id: RTThreadPreemptRestore-r0drv-generic.cpp $ */
+/** @file
+ * IPRT - RTThreadPreemptRestore, Generic ring-0 driver implementation.
+ */
+
+/*
+ * Copyright (C) 2008-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/thread.h>
+#include "internal/iprt.h"
+
+#include <iprt/assert.h>
+
+
+RTDECL(void) RTThreadPreemptRestore(PRTTHREADPREEMPTSTATE pState)
+{
+    AssertPtr(pState);
+    Assert(pState->u32Reserved == 42);
+    pState->u32Reserved = 0;
+}
+RT_EXPORT_SYMBOL(RTThreadPreemptRestore);
+
diff --git a/src/VBox/Runtime/r0drv/generic/mpnotification-r0drv-generic.cpp b/src/VBox/Runtime/r0drv/generic/mpnotification-r0drv-generic.cpp
new file mode 100644
index 00000000..3ae07820
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/generic/mpnotification-r0drv-generic.cpp
@@ -0,0 +1,65 @@
+/* $Id: mpnotification-r0drv-generic.cpp $ */
+/** @file
+ * IPRT - Multiprocessor Notifications, Ring-0 Driver, Generic Stubs.
+ */
+
+/*
+ * Copyright (C) 2008-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/mp.h>
+#include "internal/iprt.h"
+
+#include <iprt/errcore.h>
+#include "r0drv/mp-r0drv.h"
+
+
+RTDECL(int) RTMpNotificationRegister(PFNRTMPNOTIFICATION pfnCallback, void *pvUser)
+{
+    NOREF(pfnCallback);
+    NOREF(pvUser);
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTMpNotificationRegister);
+
+
+RTDECL(int) RTMpNotificationDeregister(PFNRTMPNOTIFICATION pfnCallback, void *pvUser)
+{
+    NOREF(pfnCallback);
+    NOREF(pvUser);
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTMpNotificationDeregister);
+
+
+DECLHIDDEN(int) rtR0MpNotificationInit(void)
+{
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(void) rtR0MpNotificationTerm(void)
+{
+}
+
diff --git a/src/VBox/Runtime/r0drv/generic/semspinmutex-r0drv-generic.c b/src/VBox/Runtime/r0drv/generic/semspinmutex-r0drv-generic.c
new file mode 100644
index 00000000..57dbe49a
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/generic/semspinmutex-r0drv-generic.c
@@ -0,0 +1,503 @@
+/* $Id: semspinmutex-r0drv-generic.c $ */
+/** @file
+ * IPRT - Spinning Mutex Semaphores, Ring-0 Driver, Generic.
+ */
+
+/*
+ * Copyright (C) 2009-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#ifdef RT_OS_WINDOWS
+# include "../nt/the-nt-kernel.h"
+#endif
+#include "internal/iprt.h"
+
+#include <iprt/semaphore.h>
+#include <iprt/asm.h>
+#include <iprt/asm-amd64-x86.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/mem.h>
+#include <iprt/thread.h>
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Saved state information.
+ */
+typedef struct RTSEMSPINMUTEXSTATE
+{
+    /** Saved flags register. */
+    RTCCUINTREG             fSavedFlags;
+    /** Preemption state.  */
+    RTTHREADPREEMPTSTATE    PreemptState;
+    /** Whether to spin or sleep. */
+    bool                    fSpin;
+    /** Whether the flags have been saved. */
+    bool                    fValidFlags;
+} RTSEMSPINMUTEXSTATE;
+
+/**
+ * Spinning mutex semaphore.
+ */
+typedef struct RTSEMSPINMUTEXINTERNAL
+{
+    /** Magic value (RTSEMSPINMUTEX_MAGIC)
+     * RTCRITSECT_MAGIC is the value of an initialized & operational section. */
+    uint32_t volatile       u32Magic;
+    /** Flags. This is a combination of RTSEMSPINMUTEX_FLAGS_XXX and
+     *  RTSEMSPINMUTEX_INT_FLAGS_XXX. */
+    uint32_t volatile       fFlags;
+    /** The owner thread.
+     * This is NIL if the semaphore is not owned by anyone. */
+    RTNATIVETHREAD volatile hOwner;
+    /** Number of threads that are fighting for the lock. */
+    int32_t volatile        cLockers;
+    /** The semaphore to block on. */
+    RTSEMEVENT              hEventSem;
+    /** Saved state information of the owner.
+     * This will be restored by RTSemSpinRelease. */
+    RTSEMSPINMUTEXSTATE     SavedState;
+} RTSEMSPINMUTEXINTERNAL;
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+/*#define RTSEMSPINMUTEX_INT_FLAGS_MUST*/
+
+/** Validates the handle, returning if invalid. */
+#define RTSEMSPINMUTEX_VALIDATE_RETURN(pThis) \
+    do \
+    { \
+        uint32_t u32Magic; \
+        AssertPtr(pThis); \
+        u32Magic = (pThis)->u32Magic; \
+        if (u32Magic != RTSEMSPINMUTEX_MAGIC) \
+        { \
+            AssertMsgFailed(("u32Magic=%#x pThis=%p\n", u32Magic, pThis)); \
+            return u32Magic == RTSEMSPINMUTEX_MAGIC_DEAD ? VERR_SEM_DESTROYED : VERR_INVALID_HANDLE; \
+        } \
+    } while (0)
+
+
+RTDECL(int) RTSemSpinMutexCreate(PRTSEMSPINMUTEX phSpinMtx, uint32_t fFlags)
+{
+    RTSEMSPINMUTEXINTERNAL *pThis;
+    int                     rc;
+
+    AssertReturn(!(fFlags & ~RTSEMSPINMUTEX_FLAGS_VALID_MASK), VERR_INVALID_PARAMETER);
+    AssertPtr(phSpinMtx);
+
+    /*
+     * Allocate and initialize the structure.
+     */
+    pThis = (RTSEMSPINMUTEXINTERNAL *)RTMemAllocZ(sizeof(*pThis));
+    if (!pThis)
+        return VERR_NO_MEMORY;
+    pThis->u32Magic   = RTSEMSPINMUTEX_MAGIC;
+    pThis->fFlags     = fFlags;
+    pThis->hOwner     = NIL_RTNATIVETHREAD;
+    pThis->cLockers   = 0;
+    rc = RTSemEventCreateEx(&pThis->hEventSem, RTSEMEVENT_FLAGS_NO_LOCK_VAL, NIL_RTLOCKVALCLASS, NULL);
+    if (RT_SUCCESS(rc))
+    {
+        *phSpinMtx = pThis;
+        return VINF_SUCCESS;
+    }
+
+    RTMemFree(pThis);
+    return rc;
+}
+RT_EXPORT_SYMBOL(RTSemSpinMutexCreate);
+
+
+/**
+ * Helper for RTSemSpinMutexTryRequest and RTSemSpinMutexRequest.
+ *
+ * This will check the current context and see if it's usui
+ *
+ * @returns VINF_SUCCESS or VERR_SEM_BAD_CONTEXT.
+ * @param   pState      Output structure.
+ */
+static int rtSemSpinMutexEnter(RTSEMSPINMUTEXSTATE *pState, RTSEMSPINMUTEXINTERNAL *pThis)
+{
+#ifndef RT_OS_WINDOWS
+    RTTHREADPREEMPTSTATE const StateInit = RTTHREADPREEMPTSTATE_INITIALIZER;
+#endif
+    int rc  = VINF_SUCCESS;
+
+    /** @todo Later #1: When entering in interrupt context and we're not able to
+     *        wake up threads from it, we could try switch the lock into pure
+     *        spinlock mode. This would require that there are no other threads
+     *        currently waiting on it and that the RTSEMSPINMUTEX_FLAGS_IRQ_SAFE
+     *        flag is set.
+     *
+     *        Later #2: Similarly, it is possible to turn on the
+     *        RTSEMSPINMUTEX_FLAGS_IRQ_SAFE at run time if we manage to grab the
+     *        semaphore ownership at interrupt time. We might want to try delay the
+     *        RTSEMSPINMUTEX_FLAGS_IRQ_SAFE even, since we're fine if we get it...
+     */
+
+#ifdef RT_OS_WINDOWS
+    /*
+     * NT: IRQL <= DISPATCH_LEVEL for waking up threads; IRQL < DISPATCH_LEVEL for sleeping.
+     */
+    pState->PreemptState.uchOldIrql = KeGetCurrentIrql();
+    if (pState->PreemptState.uchOldIrql > DISPATCH_LEVEL)
+        return VERR_SEM_BAD_CONTEXT;
+
+    if (pState->PreemptState.uchOldIrql >= DISPATCH_LEVEL)
+        pState->fSpin = true;
+    else
+    {
+        pState->fSpin = false;
+        KeRaiseIrql(DISPATCH_LEVEL, &pState->PreemptState.uchOldIrql);
+        Assert(pState->PreemptState.uchOldIrql < DISPATCH_LEVEL);
+    }
+
+#elif defined(RT_OS_SOLARIS)
+    /*
+     * Solaris:  RTSemEventSignal will do bad stuff on S10 if interrupts are disabled.
+     */
+    if (!ASMIntAreEnabled())
+        return VERR_SEM_BAD_CONTEXT;
+
+    pState->fSpin = !RTThreadPreemptIsEnabled(NIL_RTTHREAD);
+    if (RTThreadIsInInterrupt(NIL_RTTHREAD))
+    {
+        if (!(pThis->fFlags & RTSEMSPINMUTEX_FLAGS_IRQ_SAFE))
+            rc = VINF_SEM_BAD_CONTEXT; /* Try, but owner might be interrupted. */
+        pState->fSpin = true;
+    }
+    pState->PreemptState = StateInit;
+    RTThreadPreemptDisable(&pState->PreemptState);
+
+#elif defined(RT_OS_LINUX) || defined(RT_OS_OS2)
+    /*
+     * OSes on which RTSemEventSignal can be called from any context.
+     */
+    pState->fSpin = !RTThreadPreemptIsEnabled(NIL_RTTHREAD);
+    if (RTThreadIsInInterrupt(NIL_RTTHREAD))
+    {
+        if (!(pThis->fFlags & RTSEMSPINMUTEX_FLAGS_IRQ_SAFE))
+            rc = VINF_SEM_BAD_CONTEXT; /* Try, but owner might be interrupted. */
+        pState->fSpin = true;
+    }
+    pState->PreemptState = StateInit;
+    RTThreadPreemptDisable(&pState->PreemptState);
+
+#else /* PORTME: Check for context where we cannot wake up threads. */
+    /*
+     * Default: ASSUME thread can be woken up if interrupts are enabled and
+     *          we're not in an interrupt context.
+     *          ASSUME that we can go to sleep if preemption is enabled.
+     */
+    if (    RTThreadIsInInterrupt(NIL_RTTHREAD)
+        ||  !ASMIntAreEnabled())
+        return VERR_SEM_BAD_CONTEXT;
+
+    pState->fSpin = !RTThreadPreemptIsEnabled(NIL_RTTHREAD);
+    pState->PreemptState = StateInit;
+    RTThreadPreemptDisable(&pState->PreemptState);
+#endif
+
+    /*
+     * Disable interrupts if necessary.
+     */
+    pState->fValidFlags = !!(pThis->fFlags & RTSEMSPINMUTEX_FLAGS_IRQ_SAFE);
+    if (pState->fValidFlags)
+        pState->fSavedFlags = ASMIntDisableFlags();
+    else
+        pState->fSavedFlags = 0;
+
+    return rc;
+}
+
+
+/**
+ * Helper for RTSemSpinMutexTryRequest, RTSemSpinMutexRequest and
+ * RTSemSpinMutexRelease.
+ *
+ * @param  pState
+ */
+DECL_FORCE_INLINE(void) rtSemSpinMutexLeave(RTSEMSPINMUTEXSTATE *pState)
+{
+    /*
+     * Restore the interrupt flag.
+     */
+    if (pState->fValidFlags)
+        ASMSetFlags(pState->fSavedFlags);
+
+#ifdef RT_OS_WINDOWS
+    /*
+     * NT: Lower the IRQL if we raised it.
+     */
+    if (pState->PreemptState.uchOldIrql < DISPATCH_LEVEL)
+        KeLowerIrql(pState->PreemptState.uchOldIrql);
+#else
+    /*
+     * Default: Restore preemption.
+     */
+    RTThreadPreemptRestore(&pState->PreemptState);
+#endif
+}
+
+
+RTDECL(int) RTSemSpinMutexTryRequest(RTSEMSPINMUTEX hSpinMtx)
+{
+    RTSEMSPINMUTEXINTERNAL *pThis = hSpinMtx;
+    RTNATIVETHREAD          hSelf = RTThreadNativeSelf();
+    RTSEMSPINMUTEXSTATE     State;
+    bool                    fRc;
+    int                     rc;
+
+    Assert(hSelf != NIL_RTNATIVETHREAD);
+    RTSEMSPINMUTEX_VALIDATE_RETURN(pThis);
+
+    /*
+     * Check context, disable preemption and save flags if necessary.
+     */
+    rc = rtSemSpinMutexEnter(&State, pThis);
+    if (RT_FAILURE(rc))
+        return rc;
+
+    /*
+     * Try take the ownership.
+     */
+    ASMAtomicCmpXchgHandle(&pThis->hOwner, hSelf, NIL_RTNATIVETHREAD, fRc);
+    if (!fRc)
+    {
+        /* Busy, too bad. Check for attempts at nested access. */
+        rc = VERR_SEM_BUSY;
+        if (RT_UNLIKELY(pThis->hOwner == hSelf))
+        {
+            AssertMsgFailed(("%p attempt at nested access\n"));
+            rc = VERR_SEM_NESTED;
+        }
+
+        rtSemSpinMutexLeave(&State);
+        return rc;
+    }
+
+    /*
+     * We're the semaphore owner.
+     */
+    ASMAtomicIncS32(&pThis->cLockers);
+    pThis->SavedState = State;
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTSemSpinMutexTryRequest);
+
+
+RTDECL(int) RTSemSpinMutexRequest(RTSEMSPINMUTEX hSpinMtx)
+{
+    RTSEMSPINMUTEXINTERNAL *pThis = hSpinMtx;
+    RTNATIVETHREAD          hSelf = RTThreadNativeSelf();
+    RTSEMSPINMUTEXSTATE     State;
+    bool                    fRc;
+    int                     rc;
+
+    Assert(hSelf != NIL_RTNATIVETHREAD);
+    RTSEMSPINMUTEX_VALIDATE_RETURN(pThis);
+
+    /*
+     * Check context, disable preemption and save flags if necessary.
+     */
+    rc = rtSemSpinMutexEnter(&State, pThis);
+    if (RT_FAILURE(rc))
+        return rc;
+
+    /*
+     * Try take the ownership.
+     */
+    ASMAtomicIncS32(&pThis->cLockers);
+    ASMAtomicCmpXchgHandle(&pThis->hOwner, hSelf, NIL_RTNATIVETHREAD, fRc);
+    if (!fRc)
+    {
+        uint32_t cSpins;
+
+        /*
+         * It's busy. Check if it's an attempt at nested access.
+         */
+        if (RT_UNLIKELY(pThis->hOwner == hSelf))
+        {
+            AssertMsgFailed(("%p attempt at nested access\n"));
+            rtSemSpinMutexLeave(&State);
+            return VERR_SEM_NESTED;
+        }
+
+        /*
+         * Return if we're in interrupt context and the semaphore isn't
+         * configure to be interrupt safe.
+         */
+        if (rc == VINF_SEM_BAD_CONTEXT)
+        {
+            rtSemSpinMutexLeave(&State);
+            return VERR_SEM_BAD_CONTEXT;
+        }
+
+        /*
+         * Ok, we have to wait.
+         */
+        if (State.fSpin)
+        {
+            for (cSpins = 0; ; cSpins++)
+            {
+                ASMAtomicCmpXchgHandle(&pThis->hOwner, hSelf, NIL_RTNATIVETHREAD, fRc);
+                if (fRc)
+                    break;
+                ASMNopPause();
+                if (RT_UNLIKELY(pThis->u32Magic != RTSEMSPINMUTEX_MAGIC))
+                {
+                    rtSemSpinMutexLeave(&State);
+                    return VERR_SEM_DESTROYED;
+                }
+
+                /*
+                 * "Yield" once in a while. This may lower our IRQL/PIL which
+                 * may preempting us, and it will certainly stop the hammering
+                 * of hOwner for a little while.
+                 */
+                if ((cSpins & 0x7f) == 0x1f)
+                {
+                    rtSemSpinMutexLeave(&State);
+                    rtSemSpinMutexEnter(&State, pThis);
+                    Assert(State.fSpin);
+                }
+            }
+        }
+        else
+        {
+            for (cSpins = 0;; cSpins++)
+            {
+                ASMAtomicCmpXchgHandle(&pThis->hOwner, hSelf, NIL_RTNATIVETHREAD, fRc);
+                if (fRc)
+                    break;
+                ASMNopPause();
+                if (RT_UNLIKELY(pThis->u32Magic != RTSEMSPINMUTEX_MAGIC))
+                {
+                    rtSemSpinMutexLeave(&State);
+                    return VERR_SEM_DESTROYED;
+                }
+
+                if ((cSpins & 15) == 15) /* spin a bit before going sleep (again). */
+                {
+                    rtSemSpinMutexLeave(&State);
+
+                    rc = RTSemEventWait(pThis->hEventSem, RT_INDEFINITE_WAIT);
+                    ASMCompilerBarrier();
+                    if (RT_SUCCESS(rc))
+                        AssertReturn(pThis->u32Magic == RTSEMSPINMUTEX_MAGIC, VERR_SEM_DESTROYED);
+                    else if (rc == VERR_INTERRUPTED)
+                        AssertRC(rc);       /* shouldn't happen */
+                    else
+                    {
+                        AssertRC(rc);
+                        return rc;
+                    }
+
+                    rc = rtSemSpinMutexEnter(&State, pThis);
+                    AssertRCReturn(rc, rc);
+                    Assert(!State.fSpin);
+                }
+            }
+        }
+    }
+
+    /*
+     * We're the semaphore owner.
+     */
+    pThis->SavedState = State;
+    Assert(pThis->hOwner == hSelf);
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTSemSpinMutexRequest);
+
+
+RTDECL(int) RTSemSpinMutexRelease(RTSEMSPINMUTEX hSpinMtx)
+{
+    RTSEMSPINMUTEXINTERNAL *pThis = hSpinMtx;
+    RTNATIVETHREAD          hSelf = RTThreadNativeSelf();
+    uint32_t                cLockers;
+    RTSEMSPINMUTEXSTATE     State;
+    bool                    fRc;
+
+    Assert(hSelf != NIL_RTNATIVETHREAD);
+    RTSEMSPINMUTEX_VALIDATE_RETURN(pThis);
+
+    /*
+     * Get the saved state and try release the semaphore.
+     */
+    State = pThis->SavedState;
+    ASMCompilerBarrier();
+    ASMAtomicCmpXchgHandle(&pThis->hOwner, NIL_RTNATIVETHREAD, hSelf, fRc);
+    AssertMsgReturn(fRc,
+                    ("hOwner=%p hSelf=%p cLockers=%d\n", pThis->hOwner, hSelf, pThis->cLockers),
+                    VERR_NOT_OWNER);
+
+    cLockers = ASMAtomicDecS32(&pThis->cLockers);
+    rtSemSpinMutexLeave(&State);
+    if (cLockers > 0)
+    {
+        int rc = RTSemEventSignal(pThis->hEventSem);
+        AssertReleaseMsg(RT_SUCCESS(rc), ("RTSemEventSignal -> %Rrc\n", rc));
+    }
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTSemSpinMutexRelease);
+
+
+RTDECL(int) RTSemSpinMutexDestroy(RTSEMSPINMUTEX hSpinMtx)
+{
+    RTSEMSPINMUTEXINTERNAL *pThis;
+    RTSEMEVENT              hEventSem;
+    int                     rc;
+
+    if (hSpinMtx == NIL_RTSEMSPINMUTEX)
+        return VINF_SUCCESS;
+    pThis = hSpinMtx;
+    RTSEMSPINMUTEX_VALIDATE_RETURN(pThis);
+
+    /* No destruction races allowed! */
+    AssertMsg(   pThis->cLockers  == 0
+              && pThis->hOwner    == NIL_RTNATIVETHREAD,
+              ("pThis=%p cLockers=%d hOwner=%p\n", pThis, pThis->cLockers, pThis->hOwner));
+
+    /*
+     * Invalidate the structure, free the mutex and free the structure.
+     */
+    ASMAtomicWriteU32(&pThis->u32Magic, RTSEMSPINMUTEX_MAGIC_DEAD);
+    hEventSem        = pThis->hEventSem;
+    pThis->hEventSem = NIL_RTSEMEVENT;
+    rc = RTSemEventDestroy(hEventSem); AssertRC(rc);
+
+    RTMemFree(pThis);
+    return rc;
+}
+RT_EXPORT_SYMBOL(RTSemSpinMutexDestroy);
+
diff --git a/src/VBox/Runtime/r0drv/generic/threadctxhooks-r0drv-generic.cpp b/src/VBox/Runtime/r0drv/generic/threadctxhooks-r0drv-generic.cpp
new file mode 100644
index 00000000..f268cb02
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/generic/threadctxhooks-r0drv-generic.cpp
@@ -0,0 +1,73 @@
+/* $Id: threadctxhooks-r0drv-generic.cpp $ */
+/** @file
+ * IPRT - Thread Context Switching Hook, Ring-0 Driver, Generic.
+ */
+
+/*
+ * Copyright (C) 2013-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/thread.h>
+#include <iprt/errcore.h>
+
+#include "internal/iprt.h"
+
+RTDECL(int) RTThreadCtxHookCreate(PRTTHREADCTXHOOK phCtxHook, uint32_t fFlags, PFNRTTHREADCTXHOOK pfnCallback, void *pvUser)
+{
+    RT_NOREF4(phCtxHook, fFlags, pfnCallback, pvUser);
+    return VERR_NOT_SUPPORTED;
+}
+RT_EXPORT_SYMBOL(RTThreadCtxHookCreate);
+
+
+RTDECL(int) RTThreadCtxHookDestroy(RTTHREADCTXHOOK hCtxHook)
+{
+    return hCtxHook == NIL_RTTHREADCTXHOOK ? VINF_SUCCESS : VERR_INVALID_HANDLE;
+}
+RT_EXPORT_SYMBOL(RTThreadCtxHookDestroy);
+
+
+RTDECL(int) RTThreadCtxHookEnable(RTTHREADCTXHOOK hCtxHook)
+{
+    NOREF(hCtxHook);
+    return VERR_NOT_SUPPORTED;
+}
+RT_EXPORT_SYMBOL(RTThreadCtxHookEnable);
+
+
+RTDECL(int) RTThreadCtxHookDisable(RTTHREADCTXHOOK hCtxHook)
+{
+    NOREF(hCtxHook);
+    return VERR_NOT_SUPPORTED;
+}
+RT_EXPORT_SYMBOL(RTThreadCtxHookDisable);
+
+
+RTDECL(bool) RTThreadCtxHookIsEnabled(RTTHREADCTXHOOK hCtxHook)
+{
+    NOREF(hCtxHook);
+    return false;
+}
+RT_EXPORT_SYMBOL(RTThreadCtxHookIsEnabled);
+
diff --git a/src/VBox/Runtime/r0drv/haiku/Makefile.kup b/src/VBox/Runtime/r0drv/haiku/Makefile.kup
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/haiku/Makefile.kup
diff --git a/src/VBox/Runtime/r0drv/haiku/RTLogWriteDebugger-r0drv-haiku.c b/src/VBox/Runtime/r0drv/haiku/RTLogWriteDebugger-r0drv-haiku.c
new file mode 100644
index 00000000..015d8b63
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/haiku/RTLogWriteDebugger-r0drv-haiku.c
@@ -0,0 +1,42 @@
+/* $Id: RTLogWriteDebugger-r0drv-haiku.c $ */
+/** @file
+ * IPRT - Log To Debugger, Ring-0 Driver, Haiku.
+ */
+
+/*
+ * Copyright (C) 2012-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-haiku-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/log.h>
+
+
+RTDECL(void) RTLogWriteDebugger(const char *pch, size_t cb)
+{
+    /** @todo implement this */
+    /*kprintf("%.*s", (int)cb, pch);*/
+    return;
+}
+
diff --git a/src/VBox/Runtime/r0drv/haiku/RTLogWriteStdOut-r0drv-haiku.c b/src/VBox/Runtime/r0drv/haiku/RTLogWriteStdOut-r0drv-haiku.c
new file mode 100644
index 00000000..43d92856
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/haiku/RTLogWriteStdOut-r0drv-haiku.c
@@ -0,0 +1,41 @@
+/* $Id: RTLogWriteStdOut-r0drv-haiku.c $ */
+/** @file
+ * IPRT - Log To StdOut, Ring-0 Driver, Haiku.
+ */
+
+/*
+ * Copyright (C) 2012-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-haiku-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/log.h>
+
+
+RTDECL(void) RTLogWriteStdOut(const char *pch, size_t cb)
+{
+    dprintf("%.*s", (int)cb, pch);
+    return;
+}
+
diff --git a/src/VBox/Runtime/r0drv/haiku/alloc-r0drv-haiku.c b/src/VBox/Runtime/r0drv/haiku/alloc-r0drv-haiku.c
new file mode 100644
index 00000000..90fe0cea
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/haiku/alloc-r0drv-haiku.c
@@ -0,0 +1,124 @@
+/* $Id: alloc-r0drv-haiku.c $ */
+/** @file
+ * IPRT - Memory Allocation, Ring-0 Driver, Haiku.
+ */
+
+/*
+ * Copyright (C) 2012-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-haiku-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/mem.h>
+#include <iprt/log.h>
+
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+#include <iprt/thread.h>
+#include "r0drv/alloc-r0drv.h"
+
+
+/**
+ * OS specific allocation function.
+ */
+int rtR0MemAllocEx(size_t cb, uint32_t fFlags, PRTMEMHDR *ppHdr)
+{
+    if (RT_UNLIKELY(fFlags & RTMEMHDR_FLAG_ANY_CTX))
+        return VERR_NOT_SUPPORTED;
+
+    PRTMEMHDR pHdr = (PRTMEMHDR)malloc(cb + sizeof(*pHdr));
+    if (RT_UNLIKELY(!pHdr))
+    {
+        LogRel(("rtR0MemAllocEx(%u, %#x) failed\n",(unsigned)cb + sizeof(*pHdr), fFlags));
+        return VERR_NO_MEMORY;
+    }
+
+    pHdr->u32Magic  = RTMEMHDR_MAGIC;
+    pHdr->fFlags    = fFlags;
+    pHdr->cb        = cb;
+    pHdr->cbReq     = cb;
+    *ppHdr = pHdr;
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * OS specific free function.
+ */
+void rtR0MemFree(PRTMEMHDR pHdr)
+{
+    pHdr->u32Magic += 1;
+    free(pHdr);
+}
+
+
+RTR0DECL(void *) RTMemContAlloc(PRTCCPHYS pPhys, size_t cb) RT_NO_THROW_DEF
+{
+    /*
+     * Validate input.
+     */
+    AssertPtr(pPhys);
+    Assert(cb > 0);
+    RT_ASSERT_PREEMPTIBLE();
+
+    /*
+     * Allocate the memory and ensure that the API is still providing
+     * memory that's always below 4GB.
+     */
+    cb = RT_ALIGN_Z(cb, PAGE_SIZE);
+    void *pv;
+    area_id area = create_area("VirtualBox Contig Alloc", &pv, B_ANY_KERNEL_ADDRESS, cb, B_32_BIT_CONTIGUOUS,
+                               B_READ_AREA | B_WRITE_AREA);
+    if (area >= 0)
+    {
+        physical_entry physMap[2];
+        if (get_memory_map(pv, cb, physMap, 2)>= B_OK)
+        {
+            *pPhys = physMap[0].address;
+            return pv;
+        }
+        delete_area(area);
+        AssertMsgFailed(("Cannot get_memory_map for contig alloc! cb=%u\n",(unsigned)cb));
+    }
+    else
+    AssertMsgFailed(("Cannot create_area for contig alloc! cb=%u error=0x%08lx\n",(unsigned)cb, area));
+    return NULL;
+}
+
+
+RTR0DECL(void) RTMemContFree(void *pv, size_t cb) RT_NO_THROW_DEF
+{
+    RT_ASSERT_PREEMPTIBLE();
+    if (pv)
+    {
+        Assert(cb > 0);
+
+        area_id area = area_for(pv);
+        if (area >= B_OK)
+        delete_area(area);
+        else
+        AssertMsgFailed(("Cannot find area to delete! cb=%u error=0x%08lx\n",(unsigned)cb, area));
+    }
+}
+
diff --git a/src/VBox/Runtime/r0drv/haiku/assert-r0drv-haiku.c b/src/VBox/Runtime/r0drv/haiku/assert-r0drv-haiku.c
new file mode 100644
index 00000000..adbf4b07
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/haiku/assert-r0drv-haiku.c
@@ -0,0 +1,68 @@
+/* $Id: assert-r0drv-haiku.c $ */
+/** @file
+ * IPRT - Assertion Workers, Ring-0 Drivers, Haiku.
+ */
+
+/*
+ * Copyright (C) 2012-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-haiku-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/assert.h>
+
+#include <iprt/asm.h>
+#include <iprt/log.h>
+#include <iprt/stdarg.h>
+#include <iprt/string.h>
+
+#include "internal/assert.h"
+
+
+void rtR0AssertNativeMsg1(const char *pszExpr, unsigned uLine, const char *pszFile, const char *pszFunction)
+{
+    dprintf("\r\n!!Assertion Failed!!\r\n"
+            "Expression: %s\r\n"
+            "Location  : %s(%d) %s\r\n",
+            pszExpr, pszFile, uLine, pszFunction);
+}
+
+
+void rtR0AssertNativeMsg2V(bool fInitial, const char *pszFormat, va_list va)
+{
+    char szMsg[256];
+
+    RTStrPrintfV(szMsg, sizeof(szMsg) - 1, pszFormat, va);
+    szMsg[sizeof(szMsg) - 1] = '\0';
+    dprintf("%s", szMsg);
+
+    NOREF(fInitial);
+}
+
+
+RTR0DECL(void) RTR0AssertPanicSystem(void)
+{
+    panic("%s%s", g_szRTAssertMsg1, g_szRTAssertMsg2);
+}
+
diff --git a/src/VBox/Runtime/r0drv/haiku/initterm-r0drv-haiku.c b/src/VBox/Runtime/r0drv/haiku/initterm-r0drv-haiku.c
new file mode 100644
index 00000000..903f661c
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/haiku/initterm-r0drv-haiku.c
@@ -0,0 +1,48 @@
+/* $Id: initterm-r0drv-haiku.c $ */
+/** @file
+ * IPRT - Initialization & Termination, R0 Driver, Haiku.
+ */
+
+/*
+ * Copyright (C) 2012-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-haiku-kernel.h"
+#include "internal/iprt.h"
+
+#include <iprt/errcore.h>
+#include <iprt/assert.h>
+#include "internal/initterm.h"
+
+
+int rtR0InitNative(void)
+{
+    return VINF_SUCCESS;
+}
+
+
+void rtR0TermNative(void)
+{
+}
+
diff --git a/src/VBox/Runtime/r0drv/haiku/memobj-r0drv-haiku.c b/src/VBox/Runtime/r0drv/haiku/memobj-r0drv-haiku.c
new file mode 100644
index 00000000..864078e7
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/haiku/memobj-r0drv-haiku.c
@@ -0,0 +1,665 @@
+/* $Id: memobj-r0drv-haiku.c $ */
+/** @file
+ * IPRT - Ring-0 Memory Objects, Haiku.
+ */
+
+/*
+ * Copyright (C) 2012-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-haiku-kernel.h"
+
+#include <iprt/memobj.h>
+#include <iprt/mem.h>
+#include <iprt/err.h>
+#include <iprt/assert.h>
+#include <iprt/log.h>
+#include <iprt/param.h>
+#include <iprt/process.h>
+#include "internal/memobj.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * The Haiku version of the memory object structure.
+ */
+typedef struct RTR0MEMOBJHAIKU
+{
+    /** The core structure. */
+    RTR0MEMOBJINTERNAL  Core;
+    /** Area identifier */
+    area_id             AreaId;
+} RTR0MEMOBJHAIKU, *PRTR0MEMOBJHAIKU;
+
+
+//MALLOC_DEFINE(M_IPRTMOBJ, "iprtmobj", "IPRT - R0MemObj");
+#if 0
+/**
+ * Gets the virtual memory map the specified object is mapped into.
+ *
+ * @returns VM map handle on success, NULL if no map.
+ * @param   pMem                The memory object.
+ */
+static vm_map_t rtR0MemObjHaikuGetMap(PRTR0MEMOBJINTERNAL pMem)
+{
+    switch (pMem->enmType)
+    {
+        case RTR0MEMOBJTYPE_PAGE:
+        case RTR0MEMOBJTYPE_LOW:
+        case RTR0MEMOBJTYPE_CONT:
+            return kernel_map;
+
+        case RTR0MEMOBJTYPE_PHYS:
+        case RTR0MEMOBJTYPE_PHYS_NC:
+            return NULL; /* pretend these have no mapping atm. */
+
+        case RTR0MEMOBJTYPE_LOCK:
+            return pMem->u.Lock.R0Process == NIL_RTR0PROCESS
+            ? kernel_map
+            : &((struct proc *)pMem->u.Lock.R0Process)->p_vmspace->vm_map;
+
+        case RTR0MEMOBJTYPE_RES_VIRT:
+            return pMem->u.ResVirt.R0Process == NIL_RTR0PROCESS
+            ? kernel_map
+            : &((struct proc *)pMem->u.ResVirt.R0Process)->p_vmspace->vm_map;
+
+        case RTR0MEMOBJTYPE_MAPPING:
+            return pMem->u.Mapping.R0Process == NIL_RTR0PROCESS
+            ? kernel_map
+            : &((struct proc *)pMem->u.Mapping.R0Process)->p_vmspace->vm_map;
+
+        default:
+            return NULL;
+    }
+}
+#endif
+
+
+int rtR0MemObjNativeFree(RTR0MEMOBJ pMem)
+{
+    PRTR0MEMOBJHAIKU pMemHaiku = (PRTR0MEMOBJHAIKU)pMem;
+    int rc = B_OK;
+
+    switch (pMemHaiku->Core.enmType)
+    {
+        case RTR0MEMOBJTYPE_PAGE:
+        case RTR0MEMOBJTYPE_LOW:
+        case RTR0MEMOBJTYPE_CONT:
+        case RTR0MEMOBJTYPE_MAPPING:
+        case RTR0MEMOBJTYPE_PHYS:
+        case RTR0MEMOBJTYPE_PHYS_NC:
+        {
+            if (pMemHaiku->AreaId > -1)
+                rc = delete_area(pMemHaiku->AreaId);
+
+            AssertMsg(rc == B_OK, ("%#x", rc));
+            break;
+        }
+
+        case RTR0MEMOBJTYPE_LOCK:
+        {
+            team_id team = B_SYSTEM_TEAM;
+
+            if (pMemHaiku->Core.u.Lock.R0Process != NIL_RTR0PROCESS)
+                team = ((team_id)pMemHaiku->Core.u.Lock.R0Process);
+
+            rc = unlock_memory_etc(team, pMemHaiku->Core.pv, pMemHaiku->Core.cb, B_READ_DEVICE);
+            AssertMsg(rc == B_OK, ("%#x", rc));
+            break;
+        }
+
+        case RTR0MEMOBJTYPE_RES_VIRT:
+        {
+            team_id team = B_SYSTEM_TEAM;
+            if (pMemHaiku->Core.u.Lock.R0Process != NIL_RTR0PROCESS)
+                team = ((team_id)pMemHaiku->Core.u.Lock.R0Process);
+
+            rc = vm_unreserve_address_range(team, pMemHaiku->Core.pv, pMemHaiku->Core.cb);
+            AssertMsg(rc == B_OK, ("%#x", rc));
+            break;
+        }
+
+        default:
+            AssertMsgFailed(("enmType=%d\n", pMemHaiku->Core.enmType));
+            return VERR_INTERNAL_ERROR;
+    }
+
+    return VINF_SUCCESS;
+}
+
+
+static int rtR0MemObjNativeAllocArea(PPRTR0MEMOBJINTERNAL ppMem, size_t cb,
+                                     bool fExecutable, RTR0MEMOBJTYPE type, RTHCPHYS PhysHighest, size_t uAlignment)
+{
+    NOREF(fExecutable);
+
+    int rc;
+    void *pvMap         = NULL;
+    const char *pszName = NULL;
+    uint32 addressSpec  = B_ANY_KERNEL_ADDRESS;
+    uint32 fLock        = ~0U;
+    LogFlowFunc(("ppMem=%p cb=%u, fExecutable=%s, type=%08x, PhysHighest=%RX64 uAlignment=%u\n", ppMem,(unsigned)cb,
+                 fExecutable ? "true" : "false", type, PhysHighest,(unsigned)uAlignment));
+
+    switch (type)
+    {
+        case RTR0MEMOBJTYPE_PAGE:
+            pszName = "IPRT R0MemObj Alloc";
+            fLock = B_FULL_LOCK;
+            break;
+        case RTR0MEMOBJTYPE_LOW:
+            pszName = "IPRT R0MemObj AllocLow";
+            fLock = B_32_BIT_FULL_LOCK;
+            break;
+        case RTR0MEMOBJTYPE_CONT:
+            pszName = "IPRT R0MemObj AllocCont";
+            fLock = B_32_BIT_CONTIGUOUS;
+            break;
+#if 0
+        case RTR0MEMOBJTYPE_MAPPING:
+            pszName = "IPRT R0MemObj Mapping";
+            fLock = B_FULL_LOCK;
+            break;
+#endif
+        case RTR0MEMOBJTYPE_PHYS:
+            /** @todo alignment  */
+            if (uAlignment != PAGE_SIZE)
+                return VERR_NOT_SUPPORTED;
+            /** @todo r=ramshankar: no 'break' here?? */
+        case RTR0MEMOBJTYPE_PHYS_NC:
+            pszName = "IPRT R0MemObj AllocPhys";
+            fLock   = (PhysHighest < _4G ? B_LOMEM : B_32_BIT_CONTIGUOUS);
+            break;
+#if 0
+        case RTR0MEMOBJTYPE_LOCK:
+            break;
+#endif
+        default:
+            return VERR_INTERNAL_ERROR;
+    }
+
+    /* Create the object. */
+    PRTR0MEMOBJHAIKU pMemHaiku;
+    pMemHaiku = (PRTR0MEMOBJHAIKU)rtR0MemObjNew(sizeof(RTR0MEMOBJHAIKU), type, NULL, cb);
+    if (RT_UNLIKELY(!pMemHaiku))
+        return VERR_NO_MEMORY;
+
+    rc = pMemHaiku->AreaId = create_area(pszName, &pvMap, addressSpec, cb, fLock, B_READ_AREA | B_WRITE_AREA);
+    if (pMemHaiku->AreaId >= 0)
+    {
+        physical_entry physMap[2];
+        pMemHaiku->Core.pv = pvMap;   /* store start address */
+        switch (type)
+        {
+            case RTR0MEMOBJTYPE_CONT:
+                rc = get_memory_map(pvMap, cb, physMap, 2);
+                if (rc == B_OK)
+                    pMemHaiku->Core.u.Cont.Phys = physMap[0].address;
+                break;
+
+            case RTR0MEMOBJTYPE_PHYS:
+            case RTR0MEMOBJTYPE_PHYS_NC:
+                rc = get_memory_map(pvMap, cb, physMap, 2);
+                if (rc == B_OK)
+                {
+                    pMemHaiku->Core.u.Phys.PhysBase = physMap[0].address;
+                    pMemHaiku->Core.u.Phys.fAllocated = true;
+                }
+                break;
+
+            default:
+                break;
+        }
+        if (rc >= B_OK)
+        {
+            *ppMem = &pMemHaiku->Core;
+            return VINF_SUCCESS;
+        }
+
+        delete_area(pMemHaiku->AreaId);
+    }
+
+    rtR0MemObjDelete(&pMemHaiku->Core);
+    return RTErrConvertFromHaikuKernReturn(rc);
+}
+
+
+int rtR0MemObjNativeAllocPage(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    return rtR0MemObjNativeAllocArea(ppMem, cb, fExecutable, RTR0MEMOBJTYPE_PAGE, 0 /* PhysHighest */, 0 /* uAlignment */);
+}
+
+
+int rtR0MemObjNativeAllocLow(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    return rtR0MemObjNativeAllocArea(ppMem, cb, fExecutable, RTR0MEMOBJTYPE_LOW, 0 /* PhysHighest */, 0 /* uAlignment */);
+}
+
+
+int rtR0MemObjNativeAllocCont(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    return rtR0MemObjNativeAllocArea(ppMem, cb, fExecutable, RTR0MEMOBJTYPE_CONT, 0 /* PhysHighest */, 0 /* uAlignment */);
+}
+
+int rtR0MemObjNativeAllocPhys(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, RTHCPHYS PhysHighest, size_t uAlignment)
+{
+    return rtR0MemObjNativeAllocArea(ppMem, cb, false, RTR0MEMOBJTYPE_PHYS, PhysHighest, uAlignment);
+}
+
+
+int rtR0MemObjNativeAllocPhysNC(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, RTHCPHYS PhysHighest)
+{
+    return rtR0MemObjNativeAllocPhys(ppMem, cb, PhysHighest, PAGE_SIZE);
+}
+
+
+int rtR0MemObjNativeEnterPhys(PPRTR0MEMOBJINTERNAL ppMem, RTHCPHYS Phys, size_t cb, uint32_t uCachePolicy)
+{
+    AssertReturn(uCachePolicy == RTMEM_CACHE_POLICY_DONT_CARE, VERR_NOT_SUPPORTED);
+    LogFlowFunc(("ppMem=%p Phys=%08x cb=%u uCachePolicy=%x\n", ppMem, Phys,(unsigned)cb, uCachePolicy));
+
+    /* Create the object. */
+    PRTR0MEMOBJHAIKU pMemHaiku = (PRTR0MEMOBJHAIKU)rtR0MemObjNew(sizeof(*pMemHaiku), RTR0MEMOBJTYPE_PHYS, NULL, cb);
+    if (!pMemHaiku)
+        return VERR_NO_MEMORY;
+
+    /* There is no allocation here, it needs to be mapped somewhere first. */
+    pMemHaiku->AreaId = -1;
+    pMemHaiku->Core.u.Phys.fAllocated = false;
+    pMemHaiku->Core.u.Phys.PhysBase = Phys;
+    pMemHaiku->Core.u.Phys.uCachePolicy = uCachePolicy;
+    *ppMem = &pMemHaiku->Core;
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Worker locking the memory in either kernel or user maps.
+ *
+ * @returns IPRT status code.
+ * @param   ppMem        Where to store the allocated memory object.
+ * @param   pvStart      The starting address.
+ * @param   cb           The size of the block.
+ * @param   fAccess      The mapping protection to apply.
+ * @param   R0Process    The process to map the memory to (use NIL_RTR0PROCESS
+ *                       for the kernel)
+ * @param   fFlags       Memory flags (B_READ_DEVICE indicates the memory is
+ *                       intended to be written from a "device").
+ */
+static int rtR0MemObjNativeLockInMap(PPRTR0MEMOBJINTERNAL ppMem, void *pvStart, size_t cb, uint32_t fAccess,
+                                     RTR0PROCESS R0Process, int fFlags)
+{
+    NOREF(fAccess);
+    int rc;
+    team_id TeamId = B_SYSTEM_TEAM;
+
+    LogFlowFunc(("ppMem=%p pvStart=%p cb=%u fAccess=%x R0Process=%d fFlags=%x\n", ppMem, pvStart, cb, fAccess, R0Process,
+                 fFlags));
+
+    /* Create the object. */
+    PRTR0MEMOBJHAIKU pMemHaiku = (PRTR0MEMOBJHAIKU)rtR0MemObjNew(sizeof(*pMemHaiku), RTR0MEMOBJTYPE_LOCK, pvStart, cb);
+    if (RT_UNLIKELY(!pMemHaiku))
+        return VERR_NO_MEMORY;
+
+    if (R0Process != NIL_RTR0PROCESS)
+        TeamId = (team_id)R0Process;
+    rc = lock_memory_etc(TeamId, pvStart, cb, fFlags);
+    if (rc == B_OK)
+    {
+        pMemHaiku->AreaId = -1;
+        pMemHaiku->Core.u.Lock.R0Process = R0Process;
+        *ppMem = &pMemHaiku->Core;
+        return VINF_SUCCESS;
+    }
+    rtR0MemObjDelete(&pMemHaiku->Core);
+    return RTErrConvertFromHaikuKernReturn(rc);
+}
+
+
+int rtR0MemObjNativeLockUser(PPRTR0MEMOBJINTERNAL ppMem, RTR3PTR R3Ptr, size_t cb, uint32_t fAccess, RTR0PROCESS R0Process)
+{
+    return rtR0MemObjNativeLockInMap(ppMem, (void *)R3Ptr, cb, fAccess, R0Process, B_READ_DEVICE);
+}
+
+
+int rtR0MemObjNativeLockKernel(PPRTR0MEMOBJINTERNAL ppMem, void *pv, size_t cb, uint32_t fAccess)
+{
+    return rtR0MemObjNativeLockInMap(ppMem, pv, cb, fAccess, NIL_RTR0PROCESS, B_READ_DEVICE);
+}
+
+
+#if 0
+/** @todo Reserve address space */
+/**
+ * Worker for the two virtual address space reservers.
+ *
+ * We're leaning on the examples provided by mmap and vm_mmap in vm_mmap.c here.
+ */
+static int rtR0MemObjNativeReserveInMap(PPRTR0MEMOBJINTERNAL ppMem, void *pvFixed, size_t cb, size_t uAlignment,
+                                        RTR0PROCESS R0Process)
+{
+    int rc;
+    team_id TeamId = B_SYSTEM_TEAM;
+
+    LogFlowFunc(("ppMem=%p pvFixed=%p cb=%u uAlignment=%u R0Process=%d\n", ppMem, pvFixed, (unsigned)cb, uAlignment, R0Process));
+
+    if (R0Process != NIL_RTR0PROCESS)
+    team = (team_id)R0Process;
+
+    /* Check that the specified alignment is supported. */
+    if (uAlignment > PAGE_SIZE)
+    return VERR_NOT_SUPPORTED;
+
+    /* Create the object. */
+    PRTR0MEMOBJHAIKU pMemHaiku = (PRTR0MEMOBJHAIKU)rtR0MemObjNew(sizeof(*pMemHaiku), RTR0MEMOBJTYPE_RES_VIRT, NULL, cb);
+    if (!pMemHaiku)
+    return VERR_NO_MEMORY;
+
+    /* Ask the kernel to reserve the address range. */
+    //XXX: vm_reserve_address_range ?
+    return VERR_NOT_SUPPORTED;
+}
+#endif
+
+
+int rtR0MemObjNativeReserveKernel(PPRTR0MEMOBJINTERNAL ppMem, void *pvFixed, size_t cb, size_t uAlignment)
+{
+    return VERR_NOT_SUPPORTED;
+}
+
+
+int rtR0MemObjNativeReserveUser(PPRTR0MEMOBJINTERNAL ppMem, RTR3PTR R3PtrFixed, size_t cb, size_t uAlignment, RTR0PROCESS R0Process)
+{
+    return VERR_NOT_SUPPORTED;
+}
+
+
+int rtR0MemObjNativeMapKernel(PPRTR0MEMOBJINTERNAL ppMem, RTR0MEMOBJ pMemToMap, void *pvFixed, size_t uAlignment,
+                              unsigned fProt, size_t offSub, size_t cbSub)
+{
+    PRTR0MEMOBJHAIKU pMemToMapHaiku = (PRTR0MEMOBJHAIKU)pMemToMap;
+    PRTR0MEMOBJHAIKU pMemHaiku;
+    area_id area = -1;
+    void *pvMap = pvFixed;
+    uint32 uAddrSpec = B_EXACT_ADDRESS;
+    uint32 fProtect = 0;
+    int rc = VERR_MAP_FAILED;
+    AssertMsgReturn(!offSub && !cbSub, ("%#x %#x\n", offSub, cbSub), VERR_NOT_SUPPORTED);
+    AssertMsgReturn(pvFixed == (void *)-1, ("%p\n", pvFixed), VERR_NOT_SUPPORTED);
+#if 0
+    /** @todo r=ramshankar: Wrong format specifiers, fix later! */
+    dprintf("%s(%p, %p, %p, %d, %x, %u, %u)\n", __FUNCTION__, ppMem, pMemToMap, pvFixed, uAlignment,
+            fProt, offSub, cbSub);
+#endif
+    /* Check that the specified alignment is supported. */
+    if (uAlignment > PAGE_SIZE)
+        return VERR_NOT_SUPPORTED;
+
+    /* We can't map anything to the first page, sorry. */
+    if (pvFixed == 0)
+        return VERR_NOT_SUPPORTED;
+
+    if (fProt & RTMEM_PROT_READ)
+        fProtect |= B_KERNEL_READ_AREA;
+    if (fProt & RTMEM_PROT_WRITE)
+        fProtect |= B_KERNEL_WRITE_AREA;
+
+    /*
+     * Either the object we map has an area associated with, which we can clone,
+     * or it's a physical address range which we must map.
+     */
+    if (pMemToMapHaiku->AreaId > -1)
+    {
+        if (pvFixed == (void *)-1)
+            uAddrSpec = B_ANY_KERNEL_ADDRESS;
+
+        rc = area = clone_area("IPRT R0MemObj MapKernel", &pvMap, uAddrSpec, fProtect, pMemToMapHaiku->AreaId);
+        LogFlow(("rtR0MemObjNativeMapKernel: clone_area uAddrSpec=%d fProtect=%x AreaId=%d rc=%d\n", uAddrSpec, fProtect,
+                 pMemToMapHaiku->AreaId, rc));
+    }
+    else if (pMemToMapHaiku->Core.enmType == RTR0MEMOBJTYPE_PHYS)
+    {
+        /* map_physical_memory() won't let you choose where. */
+        if (pvFixed != (void *)-1)
+            return VERR_NOT_SUPPORTED;
+        uAddrSpec = B_ANY_KERNEL_ADDRESS;
+
+        rc = area = map_physical_memory("IPRT R0MemObj MapKernelPhys", (phys_addr_t)pMemToMapHaiku->Core.u.Phys.PhysBase,
+                                        pMemToMapHaiku->Core.cb, uAddrSpec, fProtect, &pvMap);
+    }
+    else
+        return VERR_NOT_SUPPORTED;
+
+    if (rc >= B_OK)
+    {
+        /* Create the object. */
+        pMemHaiku = (PRTR0MEMOBJHAIKU)rtR0MemObjNew(sizeof(RTR0MEMOBJHAIKU), RTR0MEMOBJTYPE_MAPPING, pvMap,
+                                                    pMemToMapHaiku->Core.cb);
+        if (RT_UNLIKELY(!pMemHaiku))
+            return VERR_NO_MEMORY;
+
+        pMemHaiku->Core.u.Mapping.R0Process = NIL_RTR0PROCESS;
+        pMemHaiku->Core.pv = pvMap;
+        pMemHaiku->AreaId = area;
+        *ppMem = &pMemHaiku->Core;
+        return VINF_SUCCESS;
+    }
+    rc = VERR_MAP_FAILED;
+
+    /** @todo finish the implementation. */
+
+    rtR0MemObjDelete(&pMemHaiku->Core);
+    return rc;
+}
+
+
+int rtR0MemObjNativeMapUser(PPRTR0MEMOBJINTERNAL ppMem, RTR0MEMOBJ pMemToMap, RTR3PTR R3PtrFixed, size_t uAlignment,
+                            unsigned fProt, RTR0PROCESS R0Process, size_t offSub, size_t cbSub)
+{
+#if 0
+    /*
+     * Check for unsupported stuff.
+     */
+    AssertMsgReturn(R0Process == RTR0ProcHandleSelf(), ("%p != %p\n", R0Process, RTR0ProcHandleSelf()), VERR_NOT_SUPPORTED);
+    AssertMsgReturn(R3PtrFixed == (RTR3PTR)-1, ("%p\n", R3PtrFixed), VERR_NOT_SUPPORTED);
+    if (uAlignment > PAGE_SIZE)
+        return VERR_NOT_SUPPORTED;
+    AssertMsgReturn(!offSub && !cbSub, ("%#zx %#zx\n", offSub, cbSub), VERR_NOT_SUPPORTED); /** @todo implement sub maps */
+
+    int                rc;
+    PRTR0MEMOBJHAIKU pMemToMapHaiku = (PRTR0MEMOBJHAIKU)pMemToMap;
+    struct proc       *pProc            = (struct proc *)R0Process;
+    struct vm_map     *pProcMap         = &pProc->p_vmspace->vm_map;
+
+    /* calc protection */
+    vm_prot_t       ProtectionFlags = 0;
+    if ((fProt & RTMEM_PROT_NONE) == RTMEM_PROT_NONE)
+    ProtectionFlags = VM_PROT_NONE;
+    if ((fProt & RTMEM_PROT_READ) == RTMEM_PROT_READ)
+    ProtectionFlags |= VM_PROT_READ;
+    if ((fProt & RTMEM_PROT_WRITE) == RTMEM_PROT_WRITE)
+    ProtectionFlags |= VM_PROT_WRITE;
+    if ((fProt & RTMEM_PROT_EXEC) == RTMEM_PROT_EXEC)
+    ProtectionFlags |= VM_PROT_EXECUTE;
+
+    /* calc mapping address */
+    PROC_LOCK(pProc);
+    vm_offset_t AddrR3 = round_page((vm_offset_t)pProc->p_vmspace->vm_daddr + lim_max(pProc, RLIMIT_DATA));
+    PROC_UNLOCK(pProc);
+
+    /* Insert the object in the map. */
+    rc = vm_map_find(pProcMap,              /* Map to insert the object in */
+                     NULL,                  /* Object to map */
+                     0,                     /* Start offset in the object */
+                     &AddrR3,               /* Start address IN/OUT */
+                     pMemToMap->cb,         /* Size of the mapping */
+                     TRUE,                  /* Whether a suitable address should be searched for first */
+                     ProtectionFlags,       /* protection flags */
+                     VM_PROT_ALL,           /* Maximum protection flags */
+                     0);                    /* Copy on write */
+
+    /* Map the memory page by page into the destination map. */
+    if (rc == KERN_SUCCESS)
+    {
+        size_t         cPages       = pMemToMap->cb >> PAGE_SHIFT;;
+        pmap_t         pPhysicalMap = pProcMap->pmap;
+        vm_offset_t    AddrR3Dst    = AddrR3;
+
+        if (   pMemToMap->enmType == RTR0MEMOBJTYPE_PHYS
+            || pMemToMap->enmType == RTR0MEMOBJTYPE_PHYS_NC
+            || pMemToMap->enmType == RTR0MEMOBJTYPE_PAGE)
+        {
+            /* Mapping physical allocations */
+            Assert(cPages == pMemToMapHaiku->u.Phys.cPages);
+
+            /* Insert the memory page by page into the mapping. */
+            for (uint32_t iPage = 0; iPage < cPages; iPage++)
+            {
+                vm_page_t pPage = pMemToMapHaiku->u.Phys.apPages[iPage];
+
+                MY_PMAP_ENTER(pPhysicalMap, AddrR3Dst, pPage, ProtectionFlags, TRUE);
+                AddrR3Dst += PAGE_SIZE;
+            }
+        }
+        else
+        {
+            /* Mapping cont or low memory types */
+            vm_offset_t AddrToMap = (vm_offset_t)pMemToMap->pv;
+
+            for (uint32_t iPage = 0; iPage < cPages; iPage++)
+            {
+                vm_page_t pPage = PHYS_TO_VM_PAGE(vtophys(AddrToMap));
+
+                MY_PMAP_ENTER(pPhysicalMap, AddrR3Dst, pPage, ProtectionFlags, TRUE);
+                AddrR3Dst += PAGE_SIZE;
+                AddrToMap += PAGE_SIZE;
+            }
+        }
+    }
+
+    if (RT_SUCCESS(rc))
+    {
+        /*
+         * Create a mapping object for it.
+         */
+        PRTR0MEMOBJHAIKU pMemHaiku = (PRTR0MEMOBJHAIKU)rtR0MemObjNew(sizeof(RTR0MEMOBJHAIKU),
+                                                                     RTR0MEMOBJTYPE_MAPPING,
+                                                                     (void *)AddrR3,
+                                                                     pMemToMap->cb);
+        if (pMemHaiku)
+        {
+            Assert((vm_offset_t)pMemHaiku->Core.pv == AddrR3);
+            pMemHaiku->Core.u.Mapping.R0Process = R0Process;
+            *ppMem = &pMemHaiku->Core;
+            return VINF_SUCCESS;
+        }
+
+        rc = vm_map_remove(pProcMap, ((vm_offset_t)AddrR3), ((vm_offset_t)AddrR3) + pMemToMap->cb);
+        AssertMsg(rc == KERN_SUCCESS, ("Deleting mapping failed\n"));
+    }
+#endif
+    return VERR_NOT_SUPPORTED;
+}
+
+
+int rtR0MemObjNativeProtect(PRTR0MEMOBJINTERNAL pMem, size_t offSub, size_t cbSub, uint32_t fProt)
+{
+    return VERR_NOT_SUPPORTED;
+}
+
+
+RTHCPHYS rtR0MemObjNativeGetPagePhysAddr(PRTR0MEMOBJINTERNAL pMem, size_t iPage)
+{
+    PRTR0MEMOBJHAIKU pMemHaiku = (PRTR0MEMOBJHAIKU)pMem;
+    status_t rc;
+
+    /** @todo r=ramshankar: Validate objects */
+
+    LogFlow(("rtR0MemObjNativeGetPagePhysAddr: pMem=%p enmType=%x iPage=%u\n", pMem, pMemHaiku->Core.enmType,(unsigned)iPage));
+
+    switch (pMemHaiku->Core.enmType)
+    {
+        case RTR0MEMOBJTYPE_LOCK:
+        {
+            team_id        TeamId = B_SYSTEM_TEAM;
+            physical_entry aPhysMap[2];
+            int32          cPhysMap = 2;    /** @todo r=ramshankar: why not use RT_ELEMENTS? */
+
+            if (pMemHaiku->Core.u.Lock.R0Process != NIL_RTR0PROCESS)
+                TeamId = (team_id)pMemHaiku->Core.u.Lock.R0Process;
+            void *pb = pMemHaiku->Core.pv + (iPage << PAGE_SHIFT);
+
+            rc = get_memory_map_etc(TeamId, pb, B_PAGE_SIZE, aPhysMap, &cPhysMap);
+            if (rc < B_OK || cPhysMap < 1)
+                return NIL_RTHCPHYS;
+
+            return aPhysMap[0].address;
+        }
+
+#if 0
+        case RTR0MEMOBJTYPE_MAPPING:
+        {
+            vm_offset_t pb = (vm_offset_t)pMemHaiku->Core.pv + (iPage << PAGE_SHIFT);
+
+            if (pMemHaiku->Core.u.Mapping.R0Process != NIL_RTR0PROCESS)
+            {
+                struct proc    *pProc     = (struct proc *)pMemHaiku->Core.u.Mapping.R0Process;
+                struct vm_map  *pProcMap  = &pProc->p_vmspace->vm_map;
+                pmap_t pPhysicalMap       = pProcMap->pmap;
+
+                return pmap_extract(pPhysicalMap, pb);
+            }
+            return vtophys(pb);
+        }
+#endif
+        case RTR0MEMOBJTYPE_CONT:
+            return pMemHaiku->Core.u.Cont.Phys + (iPage << PAGE_SHIFT);
+
+        case RTR0MEMOBJTYPE_PHYS:
+            return pMemHaiku->Core.u.Phys.PhysBase + (iPage << PAGE_SHIFT);
+
+        case RTR0MEMOBJTYPE_LOW:
+        case RTR0MEMOBJTYPE_PAGE:
+        case RTR0MEMOBJTYPE_PHYS_NC:
+        {
+            team_id        TeamId = B_SYSTEM_TEAM;
+            physical_entry aPhysMap[2];
+            int32          cPhysMap = 2;    /** @todo r=ramshankar: why not use RT_ELEMENTS? */
+
+            void *pb = pMemHaiku->Core.pv + (iPage << PAGE_SHIFT);
+            rc = get_memory_map_etc(TeamId, pb, B_PAGE_SIZE, aPhysMap, &cPhysMap);
+            if (rc < B_OK || cPhysMap < 1)
+                return NIL_RTHCPHYS;
+
+            return aPhysMap[0].address;
+        }
+
+        case RTR0MEMOBJTYPE_RES_VIRT:
+        default:
+            return NIL_RTHCPHYS;
+    }
+}
+
diff --git a/src/VBox/Runtime/r0drv/haiku/mp-r0drv-haiku.c b/src/VBox/Runtime/r0drv/haiku/mp-r0drv-haiku.c
new file mode 100644
index 00000000..b4d168df
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/haiku/mp-r0drv-haiku.c
@@ -0,0 +1,236 @@
+/* $Id: mp-r0drv-haiku.c $ */
+/** @file
+ * IPRT - Multiprocessor, Ring-0 Driver, Haiku.
+ */
+
+/*
+ * Copyright (C) 2012-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-haiku-kernel.h"
+
+#include <iprt/mp.h>
+#include <iprt/err.h>
+#include <iprt/asm.h>
+#include <iprt/cpuset.h>
+#include "r0drv/mp-r0drv.h"
+
+
+RTDECL(RTCPUID) RTMpCpuId(void)
+{
+    return smp_get_current_cpu();
+}
+
+
+RTDECL(int) RTMpCurSetIndex(void)
+{
+    return smp_get_current_cpu();
+}
+
+
+RTDECL(int) RTMpCurSetIndexAndId(PRTCPUID pidCpu)
+{
+    return *pidCpu = smp_get_current_cpu();
+}
+
+
+RTDECL(int) RTMpCpuIdToSetIndex(RTCPUID idCpu)
+{
+    return idCpu < smp_get_num_cpus() ? (int)idCpu : -1;
+}
+
+
+RTDECL(RTCPUID) RTMpCpuIdFromSetIndex(int iCpu)
+{
+    return (unsigned)iCpu < smp_get_num_cpus() ? (RTCPUID)iCpu : NIL_RTCPUID;
+}
+
+
+RTDECL(RTCPUID) RTMpGetMaxCpuId(void)
+{
+    return smp_get_num_cpus() - 1;
+}
+
+
+RTDECL(bool) RTMpIsCpuPossible(RTCPUID idCpu)
+{
+    return idCpu < smp_get_num_cpus();
+}
+
+
+RTDECL(PRTCPUSET) RTMpGetSet(PRTCPUSET pSet)
+{
+    RTCPUID idCpu;
+
+    RTCpuSetEmpty(pSet);
+    idCpu = RTMpGetMaxCpuId();
+    do
+    {
+        if (RTMpIsCpuPossible(idCpu))
+            RTCpuSetAdd(pSet, idCpu);
+    } while (idCpu-- > 0);
+    return pSet;
+}
+
+
+RTDECL(RTCPUID) RTMpGetCount(void)
+{
+    return smp_get_num_cpus();
+}
+
+
+RTDECL(bool) RTMpIsCpuOnline(RTCPUID idCpu)
+{
+    return idCpu < smp_get_num_cpus();
+    /** @todo FixMe && !CPU_ABSENT(idCpu) */
+}
+
+
+RTDECL(PRTCPUSET) RTMpGetOnlineSet(PRTCPUSET pSet)
+{
+    RTCPUID idCpu;
+
+    RTCpuSetEmpty(pSet);
+    idCpu = RTMpGetMaxCpuId();
+    do
+    {
+        if (RTMpIsCpuOnline(idCpu))
+            RTCpuSetAdd(pSet, idCpu);
+    } while (idCpu-- > 0);
+
+    return pSet;
+}
+
+
+RTDECL(RTCPUID) RTMpGetOnlineCount(void)
+{
+    return smp_get_num_cpus();
+}
+
+
+/**
+ * Wrapper between the native Haiku per-cpu callback and PFNRTWORKER
+ * for the RTMpOnAll API.
+ *
+ * @param   pvArg   Pointer to the RTMPARGS package.
+ */
+static void rtmpOnAllHaikuWrapper(void *pvArg, int current)
+{
+    PRTMPARGS pArgs = (PRTMPARGS)pvArg;
+    pArgs->pfnWorker(current, pArgs->pvUser1, pArgs->pvUser2);
+}
+
+
+RTDECL(int) RTMpOnAll(PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    RTMPARGS Args;
+    Args.pfnWorker = pfnWorker;
+    Args.pvUser1 = pvUser1;
+    Args.pvUser2 = pvUser2;
+    Args.idCpu = NIL_RTCPUID;
+    Args.cHits = 0;
+    /* is _sync needed ? */
+    call_all_cpus_sync(rtmpOnAllHaikuWrapper, &Args);
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Wrapper between the native Haiku per-cpu callback and PFNRTWORKER
+ * for the RTMpOnOthers API.
+ *
+ * @param   pvArg   Pointer to the RTMPARGS package.
+ */
+static void rtmpOnOthersHaikuWrapper(void *pvArg, int current)
+{
+    PRTMPARGS pArgs = (PRTMPARGS)pvArg;
+    RTCPUID idCpu = current;
+    if (pArgs->idCpu != idCpu)
+        pArgs->pfnWorker(idCpu, pArgs->pvUser1, pArgs->pvUser2);
+}
+
+
+RTDECL(int) RTMpOnOthers(PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    /* Will panic if no rendezvousing cpus, so check up front. */
+    if (RTMpGetOnlineCount() > 1)
+    {
+        RTMPARGS    Args;
+
+        Args.pfnWorker = pfnWorker;
+        Args.pvUser1 = pvUser1;
+        Args.pvUser2 = pvUser2;
+        Args.idCpu = RTMpCpuId();
+        Args.cHits = 0;
+        /* is _sync needed ? */
+        call_all_cpus_sync(rtmpOnOthersHaikuWrapper, &Args);
+    }
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Wrapper between the native Haiku per-cpu callback and PFNRTWORKER
+ * for the RTMpOnSpecific API.
+ *
+ * @param   pvArg   Pointer to the RTMPARGS package.
+ */
+static void rtmpOnSpecificHaikuWrapper(void *pvArg, int current)
+{
+    PRTMPARGS   pArgs = (PRTMPARGS)pvArg;
+    RTCPUID     idCpu = current;
+    if (pArgs->idCpu == idCpu)
+    {
+        pArgs->pfnWorker(idCpu, pArgs->pvUser1, pArgs->pvUser2);
+        ASMAtomicIncU32(&pArgs->cHits);
+    }
+}
+
+
+RTDECL(int) RTMpOnSpecific(RTCPUID idCpu, PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    RTMPARGS    Args;
+
+    /* Will panic if no rendezvousing cpus, so make sure the cpu is online. */
+    if (!RTMpIsCpuOnline(idCpu))
+        return VERR_CPU_NOT_FOUND;
+
+    Args.pfnWorker = pfnWorker;
+    Args.pvUser1 = pvUser1;
+    Args.pvUser2 = pvUser2;
+    Args.idCpu = idCpu;
+    Args.cHits = 0;
+    /* is _sync needed ? */
+    call_all_cpus_sync(rtmpOnSpecificHaikuWrapper, &Args);
+    return Args.cHits == 1
+           ? VINF_SUCCESS
+           : VERR_CPU_NOT_FOUND;
+}
+
+
+RTDECL(bool) RTMpOnAllIsConcurrentSafe(void)
+{
+    return true;
+}
+
diff --git a/src/VBox/Runtime/r0drv/haiku/process-r0drv-haiku.c b/src/VBox/Runtime/r0drv/haiku/process-r0drv-haiku.c
new file mode 100644
index 00000000..e6930f17
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/haiku/process-r0drv-haiku.c
@@ -0,0 +1,46 @@
+/* $Id: process-r0drv-haiku.c $ */
+/** @file
+ * IPRT - Process, Ring-0 Driver, Haiku.
+ */
+
+/*
+ * Copyright (C) 2012-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-haiku-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/process.h>
+
+
+RTDECL(RTPROCESS) RTProcSelf(void)
+{
+    return getpid();
+}
+
+
+RTR0DECL(RTR0PROCESS) RTR0ProcHandleSelf(void)
+{
+    return (RTR0PROCESS)(team_id)getpid();
+}
+
diff --git a/src/VBox/Runtime/r0drv/haiku/semevent-r0drv-haiku.c b/src/VBox/Runtime/r0drv/haiku/semevent-r0drv-haiku.c
new file mode 100644
index 00000000..857ca73f
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/haiku/semevent-r0drv-haiku.c
@@ -0,0 +1,264 @@
+/* $Id: semevent-r0drv-haiku.c $ */
+/** @file
+ * IPRT - Single Release Event Semaphores, Ring-0 Driver, Haiku.
+ */
+
+/*
+ * Copyright (C) 2012-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-haiku-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/semaphore.h>
+
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/lockvalidator.h>
+#include <iprt/mem.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Haiku event semaphore.
+ */
+typedef struct RTSEMEVENTINTERNAL
+{
+    /** Magic value (RTSEMEVENT_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** Reference counter. */
+    uint32_t volatile   cRefs;
+    /** The semaphore Id. */
+    sem_id              SemId;
+} RTSEMEVENTINTERNAL, *PRTSEMEVENTINTERNAL;
+
+
+RTDECL(int)  RTSemEventCreate(PRTSEMEVENT phEventSem)
+{
+    return RTSemEventCreateEx(phEventSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, NULL);
+}
+
+
+RTDECL(int)  RTSemEventCreateEx(PRTSEMEVENT phEventSem, uint32_t fFlags, RTLOCKVALCLASS hClass, const char *pszNameFmt, ...)
+{
+    AssertCompile(sizeof(RTSEMEVENTINTERNAL) > sizeof(void *));
+    AssertReturn(!(fFlags & ~(RTSEMEVENT_FLAGS_NO_LOCK_VAL | RTSEMEVENT_FLAGS_BOOTSTRAP_HACK)), VERR_INVALID_PARAMETER);
+    Assert(!(fFlags & RTSEMEVENT_FLAGS_BOOTSTRAP_HACK) || (fFlags & RTSEMEVENT_FLAGS_NO_LOCK_VAL));
+    AssertPtrReturn(phEventSem, VERR_INVALID_POINTER);
+
+    PRTSEMEVENTINTERNAL pThis = (PRTSEMEVENTINTERNAL)RTMemAllocZ(sizeof(*pThis));
+    if (!pThis)
+        return VERR_NO_MEMORY;
+
+    pThis->u32Magic  = RTSEMEVENT_MAGIC;
+    pThis->cRefs     = 1;
+    pThis->SemId     = create_sem(0, "IPRT Semaphore Event");
+    if (pThis->SemId >= B_OK)
+    {
+        set_sem_owner(pThis->SemId, B_SYSTEM_TEAM);
+        *phEventSem = pThis;
+        return VINF_SUCCESS;
+    }
+
+    RTMemFree(pThis);
+    return VERR_TOO_MANY_SEMAPHORES; /** @todo r=ramshankar: use RTErrConvertFromHaikuKernReturn */
+}
+
+
+/**
+ * Retains a reference to the event semaphore.
+ *
+ * @param   pThis       The event semaphore.
+ */
+DECLINLINE(void) rtR0SemEventHkuRetain(PRTSEMEVENTINTERNAL pThis)
+{
+    uint32_t cRefs = ASMAtomicIncU32(&pThis->cRefs);
+    Assert(cRefs < 100000); NOREF(cRefs);
+}
+
+
+/**
+ * Releases a reference to the event semaphore.
+ *
+ * @param   pThis       The event semaphore.
+ */
+DECLINLINE(void) rtR0SemEventHkuRelease(PRTSEMEVENTINTERNAL pThis)
+{
+    if (RT_UNLIKELY(ASMAtomicDecU32(&pThis->cRefs) == 0))
+        RTMemFree(pThis);
+}
+
+
+RTDECL(int)  RTSemEventDestroy(RTSEMEVENT hEventSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTINTERNAL pThis = hEventSem;
+    if (pThis == NIL_RTSEMEVENT)
+        return VINF_SUCCESS;
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("pThis->u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+    Assert(pThis->cRefs > 0);
+
+    /*
+     * Invalidate it and delete the semaphore to unblock everyone.
+     */
+    ASMAtomicWriteU32(&pThis->u32Magic, ~RTSEMEVENT_MAGIC);
+    delete_sem(pThis->SemId);
+    pThis->SemId = -1;
+    rtR0SemEventHkuRelease(pThis);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemEventSignal(RTSEMEVENT hEventSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTINTERNAL pThis = (PRTSEMEVENTINTERNAL)hEventSem;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("pThis->u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+    rtR0SemEventHkuRetain(pThis);
+
+    /*
+     * Signal the event object.
+     * We must use B_DO_NOT_RESCHEDULE since we are being used from an irq handler.
+     */
+    release_sem_etc(pThis->SemId, 1, B_DO_NOT_RESCHEDULE);
+    rtR0SemEventHkuRelease(pThis);
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Worker for RTSemEventWaitEx and RTSemEventWaitExDebug.
+ *
+ * @returns VBox status code.
+ * @param   pThis           The event semaphore.
+ * @param   fFlags          See RTSemEventWaitEx.
+ * @param   uTimeout        See RTSemEventWaitEx.
+ * @param   pSrcPos         The source code position of the wait.
+ */
+static int rtR0SemEventWait(PRTSEMEVENTINTERNAL pThis, uint32_t fFlags, uint64_t uTimeout,
+                            PCRTLOCKVALSRCPOS pSrcPos)
+{
+    status_t  status;
+    int       rc;
+    int32     flags = 0;
+    bigtime_t timeout; /* in microseconds */
+
+    /*
+     * Validate the input.
+     */
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    AssertReturn(RTSEMWAIT_FLAGS_ARE_VALID(fFlags), VERR_INVALID_PARAMETER);
+
+    if (fFlags & RTSEMWAIT_FLAGS_INDEFINITE)
+        timeout = B_INFINITE_TIMEOUT;
+    else
+    {
+        if (fFlags & RTSEMWAIT_FLAGS_NANOSECS)
+            timeout = uTimeout / 1000;
+        else if (fFlags & RTSEMWAIT_FLAGS_MILLISECS)
+            timeout = uTimeout * 1000;
+        else
+            return VERR_INVALID_PARAMETER;
+
+        if (fFlags & RTSEMWAIT_FLAGS_RELATIVE)
+            flags |= B_RELATIVE_TIMEOUT;
+        else if (fFlags & RTSEMWAIT_FLAGS_ABSOLUTE)
+            flags |= B_ABSOLUTE_TIMEOUT;
+        else
+            return VERR_INVALID_PARAMETER;
+    }
+
+    if (fFlags & RTSEMWAIT_FLAGS_INTERRUPTIBLE)
+        flags |= B_CAN_INTERRUPT;
+    // likely not:
+    //else
+    //    flags |= B_KILL_CAN_INTERRUPT;
+
+    rtR0SemEventHkuRetain(pThis);
+
+    status = acquire_sem_etc(pThis->SemId, 1, flags, timeout);
+
+    switch (status)
+    {
+        case B_OK:
+            rc = VINF_SUCCESS;
+            break;
+        case B_BAD_SEM_ID:
+            rc = VERR_SEM_DESTROYED;
+            break;
+        case B_INTERRUPTED:
+            rc = VERR_INTERRUPTED;
+            break;
+        case B_WOULD_BLOCK:
+            /* fallthrough ? */
+        case B_TIMED_OUT:
+            rc = VERR_TIMEOUT;
+            break;
+        default:
+            rc = RTErrConvertFromHaikuKernReturn(status);
+            break;
+    }
+
+    rtR0SemEventHkuRelease(pThis);
+    return rc;
+}
+
+
+RTDECL(int)  RTSemEventWaitEx(RTSEMEVENT hEventSem, uint32_t fFlags, uint64_t uTimeout)
+{
+#ifndef RTSEMEVENT_STRICT
+    return rtR0SemEventWait(hEventSem, fFlags, uTimeout, NULL);
+#else
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
+    return rtR0SemEventWait(hEventSem, fFlags, uTimeout, &SrcPos);
+#endif
+}
+RT_EXPORT_SYMBOL(RTSemEventWaitEx);
+
+
+RTDECL(int)  RTSemEventWaitExDebug(RTSEMEVENT hEventSem, uint32_t fFlags, uint64_t uTimeout,
+                                   RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
+    return rtR0SemEventWait(hEventSem, fFlags, uTimeout, &SrcPos);
+}
+RT_EXPORT_SYMBOL(RTSemEventWaitExDebug);
+
+
+RTDECL(uint32_t) RTSemEventGetResolution(void)
+{
+    /* At least that's what the API supports. */
+    return 1000;
+}
+
diff --git a/src/VBox/Runtime/r0drv/haiku/semeventmulti-r0drv-haiku.c b/src/VBox/Runtime/r0drv/haiku/semeventmulti-r0drv-haiku.c
new file mode 100644
index 00000000..9c4b121a
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/haiku/semeventmulti-r0drv-haiku.c
@@ -0,0 +1,292 @@
+/* $Id: semeventmulti-r0drv-haiku.c $ */
+/** @file
+ * IPRT - Multiple Release Event Semaphores, Ring-0 Driver, Haiku.
+ */
+
+/*
+ * Copyright (C) 2012-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-haiku-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/semaphore.h>
+
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+#include <iprt/err.h>
+#include <iprt/mem.h>
+#include <iprt/lockvalidator.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Haiku multiple release event semaphore.
+ */
+typedef struct RTSEMEVENTMULTIINTERNAL
+{
+    /** Magic value (RTSEMEVENTMULTI_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** Reference counter. */
+    uint32_t volatile   cRefs;
+    /** The semaphore Id. */
+    sem_id              SemId;
+} RTSEMEVENTMULTIINTERNAL, *PRTSEMEVENTMULTIINTERNAL;
+
+
+RTDECL(int)  RTSemEventMultiCreate(PRTSEMEVENTMULTI phEventMultiSem)
+{
+    return RTSemEventMultiCreateEx(phEventMultiSem, 0 /* fFlags */, NIL_RTLOCKVALCLASS, NULL);
+}
+
+
+RTDECL(int)  RTSemEventMultiCreateEx(PRTSEMEVENTMULTI phEventMultiSem, uint32_t fFlags, RTLOCKVALCLASS hClass,
+                                     const char *pszNameFmt, ...)
+{
+    PRTSEMEVENTMULTIINTERNAL pThis;
+
+    AssertReturn(!(fFlags & ~RTSEMEVENTMULTI_FLAGS_NO_LOCK_VAL), VERR_INVALID_PARAMETER);
+    pThis = (PRTSEMEVENTMULTIINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (!pThis)
+        return VERR_NO_MEMORY;
+
+    pThis->u32Magic  = RTSEMEVENTMULTI_MAGIC;
+    pThis->cRefs     = 1;
+    pThis->SemId     = create_sem(0, "IPRT Semaphore Event Multi");
+    if (pThis->SemId < B_OK)
+    {
+        set_sem_owner(pThis->SemId, B_SYSTEM_TEAM);
+        *phEventMultiSem = pThis;
+        return VINF_SUCCESS;
+    }
+
+    RTMemFree(pThis);
+    return VERR_TOO_MANY_SEMAPHORES;  /** @todo r=ramshankar: use RTErrConvertFromHaikuKernReturn */
+}
+
+
+/**
+ * Retain a reference to the semaphore.
+ *
+ * @param   pThis       The semaphore.
+ */
+DECLINLINE(void) rtR0SemEventMultiHkuRetain(PRTSEMEVENTMULTIINTERNAL pThis)
+{
+    uint32_t cRefs = ASMAtomicIncU32(&pThis->cRefs);
+    Assert(cRefs && cRefs < 100000);
+}
+
+
+/**
+ * Release a reference, destroy the thing if necessary.
+ *
+ * @param   pThis       The semaphore.
+ */
+DECLINLINE(void) rtR0SemEventMultiHkuRelease(PRTSEMEVENTMULTIINTERNAL pThis)
+{
+    if (RT_UNLIKELY(ASMAtomicDecU32(&pThis->cRefs) == 0))
+    {
+        Assert(pThis->u32Magic != RTSEMEVENTMULTI_MAGIC);
+        RTMemFree(pThis);
+    }
+}
+
+
+RTDECL(int)  RTSemEventMultiDestroy(RTSEMEVENTMULTI hEventMultiSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    if (pThis == NIL_RTSEMEVENTMULTI)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    Assert(pThis->cRefs > 0);
+
+    /*
+     * Invalidate it and signal the object just in case.
+     */
+    ASMAtomicWriteU32(&pThis->u32Magic, ~RTSEMEVENTMULTI_MAGIC);
+    delete_sem(pThis->SemId);
+    pThis->SemId = -1;
+    rtR0SemEventMultiHkuRelease(pThis);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemEventMultiSignal(RTSEMEVENTMULTI hEventMultiSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    if (!pThis)
+        return VERR_INVALID_PARAMETER;
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    rtR0SemEventMultiHkuRetain(pThis);
+
+    /*
+     * Signal the event object.
+     * We must use B_DO_NOT_RESCHEDULE since we are being used from an irq handler.
+     */
+    release_sem_etc(pThis->SemId, 1, B_RELEASE_ALL | B_DO_NOT_RESCHEDULE);
+    rtR0SemEventMultiHkuRelease(pThis);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemEventMultiReset(RTSEMEVENTMULTI hEventMultiSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    if (!pThis)
+        return VERR_INVALID_PARAMETER;
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    rtR0SemEventMultiHkuRetain(pThis);
+
+    /*
+     * Reset it.
+     */
+    //FIXME: what should I do ???
+    // delete_sem + create_sem ??
+    rtR0SemEventMultiHkuRelease(pThis);
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Worker for RTSemEventMultiWaitEx and RTSemEventMultiWaitExDebug.
+ *
+ * @returns VBox status code.
+ * @param   pThis           The event semaphore.
+ * @param   fFlags          See RTSemEventMultiWaitEx.
+ * @param   uTimeout        See RTSemEventMultiWaitEx.
+ * @param   pSrcPos         The source code position of the wait.
+ */
+static int rtR0SemEventMultiHkuWait(PRTSEMEVENTMULTIINTERNAL pThis, uint32_t fFlags, uint64_t uTimeout,
+                                    PCRTLOCKVALSRCPOS pSrcPos)
+{
+    status_t    status;
+    int         rc;
+    int32     flags = 0;
+    bigtime_t timeout; /* in microseconds */
+
+    /*
+     * Validate the input.
+     */
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    AssertReturn(RTSEMWAIT_FLAGS_ARE_VALID(fFlags), VERR_INVALID_PARAMETER);
+
+    if (fFlags & RTSEMWAIT_FLAGS_INDEFINITE)
+        timeout = B_INFINITE_TIMEOUT;
+    else
+    {
+        if (fFlags & RTSEMWAIT_FLAGS_NANOSECS)
+            timeout = uTimeout / 1000;
+        else if (fFlags & RTSEMWAIT_FLAGS_MILLISECS)
+            timeout = uTimeout * 1000;
+        else
+            return VERR_INVALID_PARAMETER;
+
+        if (fFlags & RTSEMWAIT_FLAGS_RELATIVE)
+            flags |= B_RELATIVE_TIMEOUT;
+        else if (fFlags & RTSEMWAIT_FLAGS_ABSOLUTE)
+            flags |= B_ABSOLUTE_TIMEOUT;
+        else
+            return VERR_INVALID_PARAMETER;
+    }
+
+    if (fFlags & RTSEMWAIT_FLAGS_INTERRUPTIBLE)
+        flags |= B_CAN_INTERRUPT;
+    // likely not:
+    //else
+    //    flags |= B_KILL_CAN_INTERRUPT;
+
+    rtR0SemEventMultiHkuRetain(pThis);
+
+    status = acquire_sem_etc(pThis->SemId, 1, flags, timeout);
+
+    switch (status)
+    {
+        case B_OK:
+            rc = VINF_SUCCESS;
+            break;
+        case B_BAD_SEM_ID:
+            rc = VERR_SEM_DESTROYED;
+            break;
+        case B_INTERRUPTED:
+            rc = VERR_INTERRUPTED;
+            break;
+        case B_WOULD_BLOCK:
+            /* fallthrough? */
+        case B_TIMED_OUT:
+            rc = VERR_TIMEOUT;
+            break;
+        default:
+            rc = RTErrConvertFromHaikuKernReturn(status);
+            break;
+    }
+
+    rtR0SemEventMultiHkuRelease(pThis);
+    return rc;
+}
+
+
+RTDECL(int)  RTSemEventMultiWaitEx(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout)
+{
+#ifndef RTSEMEVENT_STRICT
+    return rtR0SemEventMultiHkuWait(hEventMultiSem, fFlags, uTimeout, NULL);
+#else
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
+    return rtR0SemEventMultiHkuWait(hEventMultiSem, fFlags, uTimeout, &SrcPos);
+#endif
+}
+RT_EXPORT_SYMBOL(RTSemEventMultiWaitEx);
+
+
+RTDECL(int)  RTSemEventMultiWaitExDebug(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout,
+                                        RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
+    return rtR0SemEventMultiHkuWait(hEventMultiSem, fFlags, uTimeout, &SrcPos);
+}
+RT_EXPORT_SYMBOL(RTSemEventMultiWaitExDebug);
+
+
+RTDECL(uint32_t) RTSemEventMultiGetResolution(void)
+{
+    /* At least that's what the API supports. */
+    return 1000;
+}
+RT_EXPORT_SYMBOL(RTSemEventMultiGetResolution);
+
diff --git a/src/VBox/Runtime/r0drv/haiku/semfastmutex-r0drv-haiku.c b/src/VBox/Runtime/r0drv/haiku/semfastmutex-r0drv-haiku.c
new file mode 100644
index 00000000..cc7f5295
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/haiku/semfastmutex-r0drv-haiku.c
@@ -0,0 +1,120 @@
+/* $Id: semfastmutex-r0drv-haiku.c $ */
+/** @file
+ * IPRT - Fast Mutex Semaphores, Ring-0 Driver, Haiku.
+ */
+
+/*
+ * Copyright (C) 2012-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-haiku-kernel.h"
+
+#include <iprt/semaphore.h>
+#include <iprt/err.h>
+#include <iprt/alloc.h>
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Wrapper for the Haiku (sleep) mutex.
+ */
+typedef struct RTSEMFASTMUTEXINTERNAL
+{
+    /** Magic value (RTSEMFASTMUTEX_MAGIC). */
+    uint32_t            u32Magic;
+    /** A good old Benaphore. */
+    vint32              BenId;
+    sem_id              SemId;
+} RTSEMFASTMUTEXINTERNAL, *PRTSEMFASTMUTEXINTERNAL;
+
+
+RTDECL(int)  RTSemFastMutexCreate(PRTSEMFASTMUTEX phFastMtx)
+{
+    AssertCompile(sizeof(RTSEMFASTMUTEXINTERNAL) > sizeof(void *));
+    AssertPtrReturn(phFastMtx, VERR_INVALID_POINTER);
+
+    PRTSEMFASTMUTEXINTERNAL pThis = (PRTSEMFASTMUTEXINTERNAL)RTMemAllocZ(sizeof(*pThis));
+    if (RT_UNLIKELY(!pThis))
+        return VERR_NO_MEMORY;
+
+    pThis->u32Magic = RTSEMFASTMUTEX_MAGIC;
+    pThis->BenId = 0;
+    pThis->SemId = create_sem(0, "IPRT Fast Mutex Semaphore");
+    if (pThis->SemId >= B_OK)
+    {
+        *phFastMtx = pThis;
+        return VINF_SUCCESS;
+    }
+    RTMemFree(pThis);
+    return VERR_TOO_MANY_SEMAPHORES;     /** @todo r=ramshankar: use RTErrConvertFromHaikuKernReturn */
+}
+
+
+RTDECL(int)  RTSemFastMutexDestroy(RTSEMFASTMUTEX hFastMtx)
+{
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    if (pThis == NIL_RTSEMFASTMUTEX)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    ASMAtomicWriteU32(&pThis->u32Magic, RTSEMFASTMUTEX_MAGIC_DEAD);
+    delete_sem(pThis->SemId);
+    RTMemFree(pThis);
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemFastMutexRequest(RTSEMFASTMUTEX hFastMtx)
+{
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    if (atomic_add(&pThis->BenId, 1) > 0)
+        acquire_sem(pThis->SemId);
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemFastMutexRelease(RTSEMFASTMUTEX hFastMtx)
+{
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    if (atomic_add(&pThis->BenId, -1) > 1)
+        release_sem(pThis->SemId);
+
+    return VINF_SUCCESS;
+}
+
diff --git a/src/VBox/Runtime/r0drv/haiku/semmutex-r0drv-haiku.c b/src/VBox/Runtime/r0drv/haiku/semmutex-r0drv-haiku.c
new file mode 100644
index 00000000..fd6d0b3f
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/haiku/semmutex-r0drv-haiku.c
@@ -0,0 +1,233 @@
+/* $Id: semmutex-r0drv-haiku.c $ */
+/** @file
+ * IPRT - Mutex Semaphores, Ring-0 Driver, Haiku.
+ */
+
+/*
+ * Copyright (C) 2012-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-haiku-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/semaphore.h>
+
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/mem.h>
+#include <iprt/thread.h>
+#include <iprt/time.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Wrapper for the Haiku (sleep) mutex.
+ */
+/* XXX: not optimal, maybe should use the (private)
+   kernel recursive_lock ? (but it's not waitable) */
+typedef struct RTSEMMUTEXINTERNAL
+{
+    /** Magic value (RTSEMMUTEX_MAGIC). */
+    uint32_t            u32Magic;
+    /** Kernel semaphore. */
+    sem_id              SemId;
+    /** Current holder */
+    volatile thread_id  OwnerId;
+    /** Recursion count */
+    int32               cRecursion;
+} RTSEMMUTEXINTERNAL, *PRTSEMMUTEXINTERNAL;
+
+
+RTDECL(int)  RTSemMutexCreate(PRTSEMMUTEX phMutexSem)
+{
+    AssertCompile(sizeof(RTSEMMUTEXINTERNAL) > sizeof(void *));
+    AssertPtrReturn(phMutexSem, VERR_INVALID_POINTER);
+
+    PRTSEMMUTEXINTERNAL pThis = (PRTSEMMUTEXINTERNAL)RTMemAllocZ(sizeof(*pThis));
+    if (RT_UNLIKELY(!pThis))
+        return VERR_NO_MEMORY;
+
+    pThis->u32Magic = RTSEMMUTEX_MAGIC;
+    pThis->SemId = create_sem(0, "IPRT Mutex Semaphore");
+    if (pThis->SemId < B_OK)
+    {
+        pThis->OwnerId = -1;
+        pThis->cRecursion = 0;
+        *phMutexSem = pThis;
+        return VINF_SUCCESS;
+    }
+    RTMemFree(pThis);
+    return VERR_TOO_MANY_SEMAPHORES;    /** @todo r=ramshankar: use RTErrConvertFromHaikuKernReturn */
+}
+
+
+RTDECL(int)  RTSemMutexDestroy(RTSEMMUTEX hMutexSem)
+{
+    PRTSEMMUTEXINTERNAL pThis = hMutexSem;
+    if (pThis == NIL_RTSEMMUTEX)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    AssertReturn(ASMAtomicCmpXchgU32(&pThis->u32Magic, RTSEMMUTEX_MAGIC_DEAD, RTSEMMUTEX_MAGIC), VERR_INVALID_HANDLE);
+
+    delete_sem(pThis->SemId);
+    RTMemFree(pThis);
+
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Worker function for acquiring the mutex.
+ *
+ * @param hMutexSem     The mutex object.
+ * @param fFlags        Mutex flags (see RTSEMWAIT_FLAGS_*)
+ * @param uTimeout      Timeout in units specified by the flags.
+ *
+ * @return IPRT status code.
+ */
+static int rtSemMutexRequestEx(RTSEMMUTEX hMutexSem, uint32_t fFlags, uint64_t uTimeout)
+{
+    PRTSEMMUTEXINTERNAL pThis = hMutexSem;
+    int                 rc;
+    status_t            status;
+    int32               flags = 0;
+    bigtime_t           timeout; /* in microseconds */
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    if (pThis->OwnerId == find_thread(NULL))
+    {
+        pThis->OwnerId++;
+        return VINF_SUCCESS;
+    }
+
+    if (fFlags & RTSEMWAIT_FLAGS_INDEFINITE)
+        timeout = B_INFINITE_TIMEOUT;
+    else
+    {
+        if (fFlags & RTSEMWAIT_FLAGS_NANOSECS)
+            timeout = uTimeout / 1000;
+        else if (fFlags & RTSEMWAIT_FLAGS_MILLISECS)
+            timeout = uTimeout * 1000;
+        else
+            return VERR_INVALID_PARAMETER;
+
+        if (fFlags & RTSEMWAIT_FLAGS_RELATIVE)
+            flags |= B_RELATIVE_TIMEOUT;
+        else if (fFlags & RTSEMWAIT_FLAGS_ABSOLUTE)
+            flags |= B_ABSOLUTE_TIMEOUT;
+        else
+            return VERR_INVALID_PARAMETER;
+    }
+
+    if (fFlags & RTSEMWAIT_FLAGS_INTERRUPTIBLE)
+        flags |= B_CAN_INTERRUPT;
+
+    status = acquire_sem_etc(pThis->SemId, 1, flags, timeout);
+
+    switch (status)
+    {
+        case B_OK:
+            rc = VINF_SUCCESS;
+            pThis->cRecursion = 1;
+            pThis->OwnerId = find_thread(NULL);
+            break;
+        case B_BAD_SEM_ID:
+            rc = VERR_SEM_DESTROYED;
+            break;
+        case B_INTERRUPTED:
+            rc = VERR_INTERRUPTED;
+            break;
+        case B_WOULD_BLOCK:
+            /* fallthrough? */
+        case B_TIMED_OUT:
+            rc = VERR_TIMEOUT;
+            break;
+        default:
+            rc = VERR_INVALID_PARAMETER;
+            break;
+    }
+
+    return rc;
+}
+
+
+RTDECL(int)  RTSemMutexRequest(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies)
+{
+    return rtSemMutexRequestEx(hMutexSem, RTSEMWAIT_FLAGS_RELATIVE | RTSEMWAIT_FLAGS_RESUME | RTSEMWAIT_FLAGS_MILLISECS, cMillies);
+}
+
+
+RTDECL(int) RTSemMutexRequestDebug(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    return RTSemMutexRequest(hMutexSem, cMillies);
+}
+
+
+RTDECL(int)  RTSemMutexRequestNoResume(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies)
+{
+    return rtSemMutexRequestEx(hMutexSem, RTSEMWAIT_FLAGS_RELATIVE | RTSEMWAIT_FLAGS_NORESUME | RTSEMWAIT_FLAGS_MILLISECS, cMillies);
+}
+
+
+RTDECL(int) RTSemMutexRequestNoResumeDebug(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    return RTSemMutexRequestNoResume(hMutexSem, cMillies);
+}
+
+
+RTDECL(int)  RTSemMutexRelease(RTSEMMUTEX hMutexSem)
+{
+    PRTSEMMUTEXINTERNAL pThis = hMutexSem;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    if (pThis->OwnerId != find_thread(NULL))
+        return VERR_INVALID_HANDLE;
+
+    if (--pThis->cRecursion == 0)
+    {
+        pThis->OwnerId == -1;
+        release_sem(pThis->SemId);
+    }
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(bool) RTSemMutexIsOwned(RTSEMMUTEX hMutexSem)
+{
+    PRTSEMMUTEXINTERNAL pThis = hMutexSem;
+    AssertPtrReturn(pThis, false);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), false);
+
+    return pThis->OwnerId != -1;
+}
+
diff --git a/src/VBox/Runtime/r0drv/haiku/spinlock-r0drv-haiku.c b/src/VBox/Runtime/r0drv/haiku/spinlock-r0drv-haiku.c
new file mode 100644
index 00000000..f347e390
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/haiku/spinlock-r0drv-haiku.c
@@ -0,0 +1,138 @@
+/* $Id: spinlock-r0drv-haiku.c $ */
+/** @file
+ * IPRT - Spinlocks, Ring-0 Driver, Haiku.
+ */
+
+/*
+ * Copyright (C) 2012-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-haiku-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/spinlock.h>
+
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+#include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/errcore.h>
+#include <iprt/mem.h>
+#include <iprt/thread.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Wrapper for the KSPIN_LOCK type.
+ */
+typedef struct RTSPINLOCKINTERNAL
+{
+    /** Spinlock magic value (RTSPINLOCK_MAGIC). */
+    uint32_t volatile     u32Magic;
+    /** Spinlock creation flags */
+    uint32_t              fFlags;
+    /** Saved interrupt CPU status. */
+    cpu_status volatile   fIntSaved;
+    /** The Haiku spinlock structure. */
+    spinlock              hSpinLock;
+} RTSPINLOCKINTERNAL, *PRTSPINLOCKINTERNAL;
+
+
+
+RTDECL(int)  RTSpinlockCreate(PRTSPINLOCK pSpinlock, uint32_t fFlags, const char *pszName)
+{
+    RT_ASSERT_PREEMPTIBLE();
+    NOREF(pszName);
+
+    /*
+     * Allocate.
+     */
+    AssertCompile(sizeof(RTSPINLOCKINTERNAL) > sizeof(void *));
+    PRTSPINLOCKINTERNAL pSpinlockInt = (PRTSPINLOCKINTERNAL)RTMemAllocZ(sizeof(*pSpinlockInt));
+    if (RT_UNLIKELY(!pSpinlockInt))
+        return VERR_NO_MEMORY;
+
+    /*
+     * Initialize & return.
+     */
+    pSpinlockInt->u32Magic  = RTSPINLOCK_MAGIC;
+    pSpinlockInt->fFlags    = fFlags;
+    pSpinlockInt->fIntSaved = 0;
+    B_INITIALIZE_SPINLOCK(&pSpinlockInt->hSpinLock);
+
+    *pSpinlock = pSpinlockInt;
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSpinlockDestroy(RTSPINLOCK Spinlock)
+{
+    /*
+     * Validate input.
+     */
+    PRTSPINLOCKINTERNAL pSpinlockInt = (PRTSPINLOCKINTERNAL)Spinlock;
+    if (RT_UNLIKELY(!pSpinlockInt))
+        return VERR_INVALID_PARAMETER;
+    AssertMsgReturn(pSpinlockInt->u32Magic == RTSPINLOCK_MAGIC,
+                    ("Invalid spinlock %p magic=%#x\n", pSpinlockInt, pSpinlockInt->u32Magic),
+                    VERR_INVALID_PARAMETER);
+
+    /*
+     * Make the lock invalid and release the memory.
+     */
+    ASMAtomicIncU32(&pSpinlockInt->u32Magic);
+
+    B_INITIALIZE_SPINLOCK(&pSpinlockInt->hSpinLock);
+
+    RTMemFree(pSpinlockInt);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(void) RTSpinlockAcquire(RTSPINLOCK Spinlock)
+{
+    PRTSPINLOCKINTERNAL pSpinlockInt = (PRTSPINLOCKINTERNAL)Spinlock;
+    AssertPtr(pSpinlockInt);
+    Assert(pSpinlockInt->u32Magic == RTSPINLOCK_MAGIC);
+
+    /* Haiku cannot take spinlocks without disabling interrupts. Ignore our spinlock creation flags. */
+    pSpinlockInt->fIntSaved = disable_interrupts();
+    acquire_spinlock(&pSpinlockInt->hSpinLock);
+}
+
+
+RTDECL(void) RTSpinlockRelease(RTSPINLOCK Spinlock)
+{
+    PRTSPINLOCKINTERNAL pSpinlockInt = (PRTSPINLOCKINTERNAL)Spinlock;
+    AssertPtr(pSpinlockInt);
+    Assert(pSpinlockInt->u32Magic == RTSPINLOCK_MAGIC);
+
+    release_spinlock(&pSpinlockInt->hSpinLock);
+    restore_interrupts(pSpinlockInt->fIntSaved);
+}
+
diff --git a/src/VBox/Runtime/r0drv/haiku/the-haiku-kernel.h b/src/VBox/Runtime/r0drv/haiku/the-haiku-kernel.h
new file mode 100644
index 00000000..602d3aaa
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/haiku/the-haiku-kernel.h
@@ -0,0 +1,116 @@
+/* $Id: the-haiku-kernel.h $ */
+/** @file
+ * IPRT - Include all necessary headers for the Haiku kernel.
+ */
+
+/*
+ * Copyright (C) 2012-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+#ifndef IPRT_INCLUDED_SRC_r0drv_haiku_the_haiku_kernel_h
+#define IPRT_INCLUDED_SRC_r0drv_haiku_the_haiku_kernel_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <sys/time.h>
+
+#include <stdlib.h>
+
+#include <OS.h>
+#include <KernelExport.h>
+
+#include <iprt/cdefs.h>
+#include <iprt/err.h>
+#include <iprt/types.h>
+
+RT_C_DECLS_BEGIN
+
+/* headers/private/kernel/smp.h */
+
+extern int32 smp_get_num_cpus(void);
+extern int32 smp_get_current_cpu(void);
+
+/* headers/private/kernel/vm/vm.h */
+extern status_t vm_unreserve_address_range(team_id team, void *address, addr_t size);
+extern status_t vm_reserve_address_range(team_id team, void **_address, uint32 addressSpec, addr_t size, uint32 flags);
+extern area_id vm_clone_area(team_id team, const char *name, void **address, uint32 addressSpec, uint32 protection,
+                             uint32 mapping, area_id sourceArea, bool kernel);
+
+/* headers/private/kernel/thread_type.h */
+
+extern spinlock gThreadSpinlock;
+#define GRAB_THREAD_LOCK()    acquire_spinlock(&gThreadSpinlock)
+#define RELEASE_THREAD_LOCK() release_spinlock(&gThreadSpinlock)
+typedef struct
+{
+    int32            flags;            /* summary of events relevant in interrupt handlers (signals pending, user debugging
+                                          enabled, etc.) */
+#if 0
+    Thread            *all_next;
+    Thread            *team_next;
+    Thread            *queue_next;    /* i.e. run queue, release queue, etc. */
+    timer            alarm;
+    thread_id        id;
+    char            name[B_OS_NAME_LENGTH];
+    int32            priority;
+    int32            next_priority;
+    int32            io_priority;
+    int32            state;
+    int32            next_state;
+#endif
+    // and a lot more...
+} Thread;
+
+/* headers/private/kernel/thread.h */
+
+extern Thread* thread_get_thread_struct(thread_id id);
+extern Thread* thread_get_thread_struct_locked(thread_id id);
+
+extern void thread_yield(bool force);
+
+RT_C_DECLS_END
+
+/**
+ * Convert from Haiku kernel return code to IPRT status code.
+ * @todo put this where it belongs! (i.e. in a separate file and prototype in iprt/err.h)
+ * Or as generic call since it's not r0 specific.
+ */
+DECLINLINE(int) RTErrConvertFromHaikuKernReturn(status_t rc)
+{
+    switch (rc)
+    {
+        case B_OK:               return VINF_SUCCESS;
+        case B_BAD_SEM_ID:       return VERR_SEM_ERROR;
+        case B_NO_MORE_SEMS:     return VERR_TOO_MANY_SEMAPHORES;
+        case B_BAD_THREAD_ID:    return VERR_INVALID_PARAMETER;
+        case B_NO_MORE_THREADS:  return VERR_MAX_THRDS_REACHED;
+        case B_BAD_TEAM_ID:      return VERR_INVALID_PARAMETER;
+        case B_NO_MORE_TEAMS:    return VERR_MAX_PROCS_REACHED;
+            //default:               return VERR_GENERAL_FAILURE;
+            /** POSIX Errors are defined as a subset of system errors. */
+        default:                 return RTErrConvertFromErrno(rc);
+    }
+}
+
+#endif /* !IPRT_INCLUDED_SRC_r0drv_haiku_the_haiku_kernel_h */
+
diff --git a/src/VBox/Runtime/r0drv/haiku/thread-r0drv-haiku.c b/src/VBox/Runtime/r0drv/haiku/thread-r0drv-haiku.c
new file mode 100644
index 00000000..ec8edeb3
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/haiku/thread-r0drv-haiku.c
@@ -0,0 +1,127 @@
+/* $Id: thread-r0drv-haiku.c $ */
+/** @file
+ * IPRT - Threads, Ring-0 Driver, Haiku.
+ */
+
+/*
+ * Copyright (C) 2012-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-haiku-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/thread.h>
+
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+#include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+#include <iprt/mp.h>
+
+
+RTDECL(RTNATIVETHREAD) RTThreadNativeSelf(void)
+{
+    return (RTNATIVETHREAD)find_thread(NULL);
+}
+
+
+RTDECL(int) RTThreadSleep(RTMSINTERVAL cMillies)
+{
+    RT_ASSERT_PREEMPTIBLE();
+    snooze((bigtime_t)cMillies * 1000);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(bool) RTThreadYield(void)
+{
+    RT_ASSERT_PREEMPTIBLE();
+    //FIXME
+    //snooze(0);
+    thread_yield(true);
+    return true; /* this is fishy */
+}
+
+
+RTDECL(bool) RTThreadPreemptIsEnabled(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD);
+
+    //XXX: can't do this, it might actually be held by another cpu
+    //return !B_SPINLOCK_IS_LOCKED(&gThreadSpinlock);
+    return ASMIntAreEnabled(); /** @todo find a better way. */
+}
+
+
+RTDECL(bool) RTThreadPreemptIsPending(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD);
+    /** @todo check if Thread::next_priority or
+     *        cpu_ent::invoke_scheduler could do. */
+    return false;
+}
+
+
+RTDECL(bool) RTThreadPreemptIsPendingTrusty(void)
+{
+    /* RTThreadPreemptIsPending is not reliable yet. */
+    return false;
+}
+
+
+RTDECL(bool) RTThreadPreemptIsPossible(void)
+{
+    /* yes, kernel preemption is possible. */
+    return true;
+}
+
+
+RTDECL(void) RTThreadPreemptDisable(PRTTHREADPREEMPTSTATE pState)
+{
+    AssertPtr(pState);
+    Assert(pState->uOldCpuState == 0);
+
+    pState->uOldCpuState = (uint32_t)disable_interrupts();
+    RT_ASSERT_PREEMPT_CPUID_DISABLE(pState);
+}
+
+
+RTDECL(void) RTThreadPreemptRestore(PRTTHREADPREEMPTSTATE pState)
+{
+    AssertPtr(pState);
+
+    RT_ASSERT_PREEMPT_CPUID_RESTORE(pState);
+    restore_interrupts((cpu_status)pState->uOldCpuState);
+    pState->uOldCpuState = 0;
+}
+
+
+RTDECL(bool) RTThreadIsInInterrupt(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD); NOREF(hThread);
+    /** @todo Implement RTThreadIsInInterrupt. Required for guest
+     *        additions! */
+    return !ASMIntAreEnabled();
+}
+
diff --git a/src/VBox/Runtime/r0drv/haiku/thread2-r0drv-haiku.c b/src/VBox/Runtime/r0drv/haiku/thread2-r0drv-haiku.c
new file mode 100644
index 00000000..c2c13f92
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/haiku/thread2-r0drv-haiku.c
@@ -0,0 +1,138 @@
+/* $Id: thread2-r0drv-haiku.c $ */
+/** @file
+ * IPRT - Threads (Part 2), Ring-0 Driver, Haiku.
+ */
+
+/*
+ * Copyright (C) 2012-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-haiku-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/thread.h>
+
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+#include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+#include "internal/thread.h"
+
+
+DECLHIDDEN(int) rtThreadNativeInit(void)
+{
+    /* No TLS in Ring-0. :-/ */
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(RTTHREAD) RTThreadSelf(void)
+{
+    return rtThreadGetByNative((RTNATIVETHREAD)find_thread(NULL));
+}
+
+
+DECLHIDDEN(int) rtThreadNativeSetPriority(PRTTHREADINT pThread, RTTHREADTYPE enmType)
+{
+    int32 iPriority;
+    status_t status;
+
+    /*
+     * Convert the priority type to native priorities.
+     * (This is quite naive but should be ok.)
+     */
+    switch (enmType)
+    {
+        case RTTHREADTYPE_INFREQUENT_POLLER: iPriority = B_LOWEST_ACTIVE_PRIORITY;      break;
+        case RTTHREADTYPE_EMULATION:         iPriority = B_LOW_PRIORITY;                break;
+        case RTTHREADTYPE_DEFAULT:           iPriority = B_NORMAL_PRIORITY;             break;
+        case RTTHREADTYPE_MSG_PUMP:          iPriority = B_DISPLAY_PRIORITY;            break;
+        case RTTHREADTYPE_IO:                iPriority = B_URGENT_DISPLAY_PRIORITY;     break;
+        case RTTHREADTYPE_TIMER:             iPriority = B_REAL_TIME_DISPLAY_PRIORITY;  break;
+        default:
+            AssertMsgFailed(("enmType=%d\n", enmType));
+            return VERR_INVALID_PARAMETER;
+    }
+
+    status = set_thread_priority((thread_id)pThread->Core.Key, iPriority);
+
+    return RTErrConvertFromHaikuKernReturn(status);
+}
+
+
+DECLHIDDEN(int) rtThreadNativeAdopt(PRTTHREADINT pThread)
+{
+    return VERR_NOT_IMPLEMENTED;
+}
+
+
+DECLHIDDEN(void) rtThreadNativeWaitKludge(PRTTHREADINT pThread)
+{
+    /** @todo fix RTThreadWait/RTR0Term race on freebsd. */
+    RTThreadSleep(1);
+}
+
+
+DECLHIDDEN(void) rtThreadNativeDestroy(PRTTHREADINT pThread)
+{
+    NOREF(pThread);
+}
+
+
+/**
+ * Native kernel thread wrapper function.
+ *
+ * This will forward to rtThreadMain and do termination upon return.
+ *
+ * @param pvArg         Pointer to the argument package.
+ * @param Ignored       Wait result, which we ignore.
+ */
+static status_t rtThreadNativeMain(void *pvArg)
+{
+    const thread_id Self = find_thread(NULL);
+    PRTTHREADINT pThread = (PRTTHREADINT)pvArg;
+
+    int rc = rtThreadMain(pThread, (RTNATIVETHREAD)Self, &pThread->szName[0]);
+
+    if (rc < 0)
+        return RTErrConvertFromHaikuKernReturn(rc);
+    return rc;
+}
+
+
+DECLHIDDEN(int) rtThreadNativeCreate(PRTTHREADINT pThreadInt, PRTNATIVETHREAD pNativeThread)
+{
+    thread_id NativeThread;
+    RT_ASSERT_PREEMPTIBLE();
+
+    NativeThread = spawn_kernel_thread(rtThreadNativeMain, pThreadInt->szName, B_NORMAL_PRIORITY, pThreadInt);
+    if (NativeThread >= B_OK)
+    {
+        resume_thread(NativeThread);
+        *pNativeThread = (RTNATIVETHREAD)NativeThread;
+        return VINF_SUCCESS;
+    }
+    return RTErrConvertFromHaikuKernReturn(NativeThread);
+}
+
diff --git a/src/VBox/Runtime/r0drv/haiku/time-r0drv-haiku.c b/src/VBox/Runtime/r0drv/haiku/time-r0drv-haiku.c
new file mode 100644
index 00000000..06a985f0
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/haiku/time-r0drv-haiku.c
@@ -0,0 +1,79 @@
+/* $Id: time-r0drv-haiku.c $ */
+/** @file
+ * IPRT - Time, Ring-0 Driver, Haiku.
+ */
+
+/*
+ * Copyright (C) 2012-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define LOG_GROUP RTLOGGROUP_TIME
+#include "the-haiku-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/time.h>
+
+#include <iprt/asm.h>
+
+
+DECLINLINE(uint64_t) rtTimeGetSystemNanoTS(void)
+{
+    return system_time() * RT_NS_1US;
+}
+
+
+DECLINLINE(uint64_t) rtTimeGetSystemMilliTS(void)
+{
+    return system_time() / RT_NS_1US;
+}
+
+
+RTDECL(uint64_t) RTTimeNanoTS(void)
+{
+    return rtTimeGetSystemNanoTS();
+}
+
+
+RTDECL(uint64_t) RTTimeMilliTS(void)
+{
+    return rtTimeGetSystemMilliTS();
+}
+
+
+RTDECL(uint64_t) RTTimeSystemNanoTS(void)
+{
+    return rtTimeGetSystemNanoTS();
+}
+
+
+RTDECL(uint64_t) RTTimeSystemMilliTS(void)
+{
+    return rtTimeGetSystemMilliTS();
+}
+
+
+RTDECL(PRTTIMESPEC) RTTimeNow(PRTTIMESPEC pTime)
+{
+    return RTTimeSpecSetNano(pTime, real_time_clock_usecs() * RT_NS_1US);
+}
+
diff --git a/src/VBox/Runtime/r0drv/initterm-r0drv.cpp b/src/VBox/Runtime/r0drv/initterm-r0drv.cpp
new file mode 100644
index 00000000..2e5a59c3
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/initterm-r0drv.cpp
@@ -0,0 +1,164 @@
+/* $Id: initterm-r0drv.cpp $ */
+/** @file
+ * IPRT - Initialization & Termination, R0 Driver, Common.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/initterm.h>
+#include "internal/iprt.h"
+
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/mp.h>
+#include <iprt/thread.h>
+#ifndef IN_GUEST /* play safe for now */
+# include "r0drv/mp-r0drv.h"
+# include "r0drv/power-r0drv.h"
+#endif
+
+#include "internal/initterm.h"
+#include "internal/mem.h"
+#include "internal/thread.h"
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/** Count of current IPRT users.
+ * In ring-0 several drivers / kmods / kexts / wossnames may share the
+ * same runtime code. So, we need to keep count in order not to terminate
+ * it prematurely. */
+static int32_t volatile g_crtR0Users = 0;
+
+
+/**
+ * Initializes the ring-0 driver runtime library.
+ *
+ * @returns iprt status code.
+ * @param   fReserved       Flags reserved for the future.
+ */
+RTR0DECL(int) RTR0Init(unsigned fReserved)
+{
+    int rc;
+    uint32_t cNewUsers;
+    Assert(fReserved == 0); RT_NOREF_PV(fReserved);
+#ifndef RT_OS_SOLARIS       /* On Solaris our thread preemption information is only obtained in rtR0InitNative().*/
+    RT_ASSERT_PREEMPTIBLE();
+#endif
+
+    /*
+     * The first user initializes it.
+     * We rely on the module loader to ensure that there are no
+     * initialization races should two modules share the IPRT.
+     */
+    cNewUsers = ASMAtomicIncS32(&g_crtR0Users);
+    if (cNewUsers != 1)
+    {
+        if (cNewUsers > 1)
+            return VINF_SUCCESS;
+        ASMAtomicDecS32(&g_crtR0Users);
+        return VERR_INTERNAL_ERROR_3;
+    }
+
+    rc = rtR0InitNative();
+    if (RT_SUCCESS(rc))
+    {
+#ifdef RTR0MEM_WITH_EF_APIS
+        rtR0MemEfInit();
+#endif
+        rc = rtThreadInit();
+        if (RT_SUCCESS(rc))
+        {
+#ifndef IN_GUEST /* play safe for now */
+            rc = rtR0MpNotificationInit();
+            if (RT_SUCCESS(rc))
+            {
+                rc = rtR0PowerNotificationInit();
+                if (RT_SUCCESS(rc))
+                    return rc;
+                rtR0MpNotificationTerm();
+            }
+#else
+            if (RT_SUCCESS(rc))
+                return rc;
+#endif
+            rtThreadTerm();
+        }
+#ifdef RTR0MEM_WITH_EF_APIS
+        rtR0MemEfTerm();
+#endif
+        rtR0TermNative();
+    }
+    return rc;
+}
+RT_EXPORT_SYMBOL(RTR0Init);
+
+
+static void rtR0Term(void)
+{
+    rtThreadTerm();
+#ifndef IN_GUEST /* play safe for now */
+    rtR0PowerNotificationTerm();
+    rtR0MpNotificationTerm();
+#endif
+#ifdef RTR0MEM_WITH_EF_APIS
+    rtR0MemEfTerm();
+#endif
+    rtR0TermNative();
+}
+
+
+/**
+ * Terminates the ring-0 driver runtime library.
+ */
+RTR0DECL(void) RTR0Term(void)
+{
+    int32_t cNewUsers;
+    RT_ASSERT_PREEMPTIBLE();
+
+    cNewUsers = ASMAtomicDecS32(&g_crtR0Users);
+    Assert(cNewUsers >= 0);
+    if (cNewUsers == 0)
+        rtR0Term();
+    else if (cNewUsers < 0)
+        ASMAtomicIncS32(&g_crtR0Users);
+}
+RT_EXPORT_SYMBOL(RTR0Term);
+
+
+/* Note! Should *not* be exported since it's only for static linking. */
+RTR0DECL(void) RTR0TermForced(void)
+{
+    RT_ASSERT_PREEMPTIBLE();
+
+    AssertMsg(g_crtR0Users == 1, ("%d\n", g_crtR0Users));
+    ASMAtomicWriteS32(&g_crtR0Users, 0);
+
+    rtR0Term();
+}
+
diff --git a/src/VBox/Runtime/r0drv/linux/Makefile.kup b/src/VBox/Runtime/r0drv/linux/Makefile.kup
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/Makefile.kup
diff --git a/src/VBox/Runtime/r0drv/linux/RTLogWriteDebugger-r0drv-linux.c b/src/VBox/Runtime/r0drv/linux/RTLogWriteDebugger-r0drv-linux.c
new file mode 100644
index 00000000..460094ef
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/RTLogWriteDebugger-r0drv-linux.c
@@ -0,0 +1,43 @@
+/* $Id: RTLogWriteDebugger-r0drv-linux.c $ */
+/** @file
+ * IPRT - Log To Debugger, Ring-0 Driver, Linux.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-linux-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/log.h>
+
+
+RTDECL(void) RTLogWriteDebugger(const char *pch, size_t cb)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+    printk("%.*s", (int)cb, pch);
+    IPRT_LINUX_RESTORE_EFL_AC();
+}
+RT_EXPORT_SYMBOL(RTLogWriteDebugger);
+
diff --git a/src/VBox/Runtime/r0drv/linux/alloc-r0drv-linux.c b/src/VBox/Runtime/r0drv/linux/alloc-r0drv-linux.c
new file mode 100644
index 00000000..1ae48f9f
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/alloc-r0drv-linux.c
@@ -0,0 +1,497 @@
+/* $Id: alloc-r0drv-linux.c $ */
+/** @file
+ * IPRT - Memory Allocation, Ring-0 Driver, Linux.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-linux-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/mem.h>
+
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+#include "r0drv/alloc-r0drv.h"
+
+
+#if (defined(RT_ARCH_AMD64) || defined(DOXYGEN_RUNNING)) && !defined(RTMEMALLOC_EXEC_HEAP)
+# if RTLNX_VER_MIN(2,6,23) && RTLNX_VER_MAX(5,8,0)
+/**
+ * Starting with 2.6.23 we can use __get_vm_area and map_vm_area to allocate
+ * memory in the moduel range.  This is preferrable to the exec heap below.
+ */
+#  define RTMEMALLOC_EXEC_VM_AREA
+# else
+/**
+ * We need memory in the module range (~2GB to ~0) this can only be obtained
+ * thru APIs that are not exported (see module_alloc()).
+ *
+ * So, we'll have to create a quick and dirty heap here using BSS memory.
+ * Very annoying and it's going to restrict us!
+ */
+#  define RTMEMALLOC_EXEC_HEAP
+# endif
+#endif
+
+#ifdef RTMEMALLOC_EXEC_HEAP
+# include <iprt/heap.h>
+# include <iprt/spinlock.h>
+# include <iprt/errcore.h>
+#endif
+
+#include "internal/initterm.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+#ifdef RTMEMALLOC_EXEC_VM_AREA
+/**
+ * Extended header used for headers marked with RTMEMHDR_FLAG_EXEC_VM_AREA.
+ *
+ * This is used with allocating executable memory, for things like generated
+ * code and loaded modules.
+ */
+typedef struct RTMEMLNXHDREX
+{
+    /** The VM area for this allocation. */
+    struct vm_struct   *pVmArea;
+    void               *pvDummy;
+    /** The header we present to the generic API. */
+    RTMEMHDR            Hdr;
+} RTMEMLNXHDREX;
+AssertCompileSize(RTMEMLNXHDREX, 32);
+/** Pointer to an extended memory header. */
+typedef RTMEMLNXHDREX *PRTMEMLNXHDREX;
+#endif
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+#ifdef RTMEMALLOC_EXEC_HEAP
+/** The heap. */
+static RTHEAPSIMPLE g_HeapExec = NIL_RTHEAPSIMPLE;
+/** Spinlock protecting the heap. */
+static RTSPINLOCK   g_HeapExecSpinlock = NIL_RTSPINLOCK;
+#endif
+
+
+/**
+ * API for cleaning up the heap spinlock on IPRT termination.
+ * This is as RTMemExecDonate specific to AMD64 Linux/GNU.
+ */
+DECLHIDDEN(void) rtR0MemExecCleanup(void)
+{
+#ifdef RTMEMALLOC_EXEC_HEAP
+    RTSpinlockDestroy(g_HeapExecSpinlock);
+    g_HeapExecSpinlock = NIL_RTSPINLOCK;
+#endif
+}
+
+
+/**
+ * Donate read+write+execute memory to the exec heap.
+ *
+ * This API is specific to AMD64 and Linux/GNU. A kernel module that desires to
+ * use RTMemExecAlloc on AMD64 Linux/GNU will have to donate some statically
+ * allocated memory in the module if it wishes for GCC generated code to work.
+ * GCC can only generate modules that work in the address range ~2GB to ~0
+ * currently.
+ *
+ * The API only accept one single donation.
+ *
+ * @returns IPRT status code.
+ * @retval  VERR_NOT_SUPPORTED if the code isn't enabled.
+ * @param   pvMemory    Pointer to the memory block.
+ * @param   cb          The size of the memory block.
+ */
+RTR0DECL(int) RTR0MemExecDonate(void *pvMemory, size_t cb)
+{
+#ifdef RTMEMALLOC_EXEC_HEAP
+    int rc;
+    AssertReturn(g_HeapExec == NIL_RTHEAPSIMPLE, VERR_WRONG_ORDER);
+
+    rc = RTSpinlockCreate(&g_HeapExecSpinlock, RTSPINLOCK_FLAGS_INTERRUPT_SAFE, "RTR0MemExecDonate");
+    if (RT_SUCCESS(rc))
+    {
+        rc = RTHeapSimpleInit(&g_HeapExec, pvMemory, cb);
+        if (RT_FAILURE(rc))
+            rtR0MemExecCleanup();
+    }
+    return rc;
+#else
+    RT_NOREF_PV(pvMemory); RT_NOREF_PV(cb);
+    return VERR_NOT_SUPPORTED;
+#endif
+}
+RT_EXPORT_SYMBOL(RTR0MemExecDonate);
+
+
+
+#ifdef RTMEMALLOC_EXEC_VM_AREA
+/**
+ * Allocate executable kernel memory in the module range.
+ *
+ * @returns Pointer to a allocation header success.  NULL on failure.
+ *
+ * @param   cb          The size the user requested.
+ */
+static PRTMEMHDR rtR0MemAllocExecVmArea(size_t cb)
+{
+    size_t const        cbAlloc = RT_ALIGN_Z(sizeof(RTMEMLNXHDREX) + cb, PAGE_SIZE);
+    size_t const        cPages  = cbAlloc >> PAGE_SHIFT;
+    struct page       **papPages;
+    struct vm_struct   *pVmArea;
+    size_t              iPage;
+
+    pVmArea = __get_vm_area(cbAlloc, VM_ALLOC, MODULES_VADDR, MODULES_END);
+    if (!pVmArea)
+        return NULL;
+    pVmArea->nr_pages = 0;    /* paranoia? */
+    pVmArea->pages    = NULL; /* paranoia? */
+
+    papPages = (struct page **)kmalloc(cPages * sizeof(papPages[0]), GFP_KERNEL | __GFP_NOWARN);
+    if (!papPages)
+    {
+        vunmap(pVmArea->addr);
+        return NULL;
+    }
+
+    for (iPage = 0; iPage < cPages; iPage++)
+    {
+        papPages[iPage] = alloc_page(GFP_KERNEL | __GFP_HIGHMEM | __GFP_NOWARN);
+        if (!papPages[iPage])
+            break;
+    }
+    if (iPage == cPages)
+    {
+        /*
+         * Map the pages.
+         *
+         * Not entirely sure we really need to set nr_pages and pages here, but
+         * they provide a very convenient place for storing something we need
+         * in the free function, if nothing else...
+         */
+# if RTLNX_VER_MAX(3,17,0)
+        struct page **papPagesIterator = papPages;
+# endif
+        pVmArea->nr_pages = cPages;
+        pVmArea->pages    = papPages;
+        if (!map_vm_area(pVmArea, PAGE_KERNEL_EXEC,
+# if RTLNX_VER_MAX(3,17,0)
+                         &papPagesIterator
+# else
+                         papPages
+# endif
+                         ))
+        {
+            PRTMEMLNXHDREX pHdrEx = (PRTMEMLNXHDREX)pVmArea->addr;
+            pHdrEx->pVmArea     = pVmArea;
+            pHdrEx->pvDummy     = NULL;
+            return &pHdrEx->Hdr;
+        }
+        /* bail out */
+# if RTLNX_VER_MAX(3,17,0)
+        pVmArea->nr_pages = papPagesIterator - papPages;
+# endif
+    }
+
+    vunmap(pVmArea->addr);
+
+    while (iPage-- > 0)
+        __free_page(papPages[iPage]);
+    kfree(papPages);
+
+    return NULL;
+}
+#endif /* RTMEMALLOC_EXEC_VM_AREA */
+
+
+/**
+ * OS specific allocation function.
+ */
+DECLHIDDEN(int) rtR0MemAllocEx(size_t cb, uint32_t fFlags, PRTMEMHDR *ppHdr)
+{
+    PRTMEMHDR pHdr;
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    /*
+     * Allocate.
+     */
+    if (fFlags & RTMEMHDR_FLAG_EXEC)
+    {
+        if (fFlags & RTMEMHDR_FLAG_ANY_CTX)
+            return VERR_NOT_SUPPORTED;
+
+#if defined(RT_ARCH_AMD64)
+# ifdef RTMEMALLOC_EXEC_HEAP
+        if (g_HeapExec != NIL_RTHEAPSIMPLE)
+        {
+            RTSpinlockAcquire(g_HeapExecSpinlock);
+            pHdr = (PRTMEMHDR)RTHeapSimpleAlloc(g_HeapExec, cb + sizeof(*pHdr), 0);
+            RTSpinlockRelease(g_HeapExecSpinlock);
+            fFlags |= RTMEMHDR_FLAG_EXEC_HEAP;
+        }
+        else
+            pHdr = NULL;
+
+# elif defined(RTMEMALLOC_EXEC_VM_AREA)
+        pHdr = rtR0MemAllocExecVmArea(cb);
+        fFlags |= RTMEMHDR_FLAG_EXEC_VM_AREA;
+
+# else  /* !RTMEMALLOC_EXEC_HEAP */
+# error "you don not want to go here..."
+        pHdr = (PRTMEMHDR)__vmalloc(cb + sizeof(*pHdr), GFP_KERNEL | __GFP_HIGHMEM | __GFP_NOWARN, MY_PAGE_KERNEL_EXEC);
+# endif /* !RTMEMALLOC_EXEC_HEAP */
+
+#elif defined(PAGE_KERNEL_EXEC) && defined(CONFIG_X86_PAE)
+        pHdr = (PRTMEMHDR)__vmalloc(cb + sizeof(*pHdr), GFP_KERNEL | __GFP_HIGHMEM | __GFP_NOWARN, MY_PAGE_KERNEL_EXEC);
+#else
+        pHdr = (PRTMEMHDR)vmalloc(cb + sizeof(*pHdr));
+#endif
+    }
+    else
+    {
+        if (
+#if 1 /* vmalloc has serious performance issues, avoid it. */
+               cb <= PAGE_SIZE*16 - sizeof(*pHdr)
+#else
+               cb <= PAGE_SIZE
+#endif
+            || (fFlags & RTMEMHDR_FLAG_ANY_CTX)
+           )
+        {
+            fFlags |= RTMEMHDR_FLAG_KMALLOC;
+            pHdr = kmalloc(cb + sizeof(*pHdr),
+                           (fFlags & RTMEMHDR_FLAG_ANY_CTX_ALLOC) ? (GFP_ATOMIC | __GFP_NOWARN)
+                                                                  : (GFP_KERNEL | __GFP_NOWARN));
+            if (RT_UNLIKELY(   !pHdr
+                            && cb > PAGE_SIZE
+                            && !(fFlags & RTMEMHDR_FLAG_ANY_CTX) ))
+            {
+                fFlags &= ~RTMEMHDR_FLAG_KMALLOC;
+                pHdr = vmalloc(cb + sizeof(*pHdr));
+            }
+        }
+        else
+            pHdr = vmalloc(cb + sizeof(*pHdr));
+    }
+    if (RT_UNLIKELY(!pHdr))
+    {
+        IPRT_LINUX_RESTORE_EFL_AC();
+        return VERR_NO_MEMORY;
+    }
+
+    /*
+     * Initialize.
+     */
+    pHdr->u32Magic  = RTMEMHDR_MAGIC;
+    pHdr->fFlags    = fFlags;
+    pHdr->cb        = cb;
+    pHdr->cbReq     = cb;
+
+    *ppHdr = pHdr;
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * OS specific free function.
+ */
+DECLHIDDEN(void) rtR0MemFree(PRTMEMHDR pHdr)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    pHdr->u32Magic += 1;
+    if (pHdr->fFlags & RTMEMHDR_FLAG_KMALLOC)
+        kfree(pHdr);
+#ifdef RTMEMALLOC_EXEC_HEAP
+    else if (pHdr->fFlags & RTMEMHDR_FLAG_EXEC_HEAP)
+    {
+        RTSpinlockAcquire(g_HeapExecSpinlock);
+        RTHeapSimpleFree(g_HeapExec, pHdr);
+        RTSpinlockRelease(g_HeapExecSpinlock);
+    }
+#endif
+#ifdef RTMEMALLOC_EXEC_VM_AREA
+    else if (pHdr->fFlags & RTMEMHDR_FLAG_EXEC_VM_AREA)
+    {
+        PRTMEMLNXHDREX pHdrEx    = RT_FROM_MEMBER(pHdr, RTMEMLNXHDREX, Hdr);
+        size_t         iPage     = pHdrEx->pVmArea->nr_pages;
+        struct page  **papPages  = pHdrEx->pVmArea->pages;
+        void          *pvMapping = pHdrEx->pVmArea->addr;
+
+        vunmap(pvMapping);
+
+        while (iPage-- > 0)
+            __free_page(papPages[iPage]);
+        kfree(papPages);
+    }
+#endif
+    else
+        vfree(pHdr);
+
+    IPRT_LINUX_RESTORE_EFL_AC();
+}
+
+
+
+/**
+ * Compute order. Some functions allocate 2^order pages.
+ *
+ * @returns order.
+ * @param   cPages      Number of pages.
+ */
+static int CalcPowerOf2Order(unsigned long cPages)
+{
+    int             iOrder;
+    unsigned long   cTmp;
+
+    for (iOrder = 0, cTmp = cPages; cTmp >>= 1; ++iOrder)
+        ;
+    if (cPages & ~(1 << iOrder))
+        ++iOrder;
+
+    return iOrder;
+}
+
+
+/**
+ * Allocates physical contiguous memory (below 4GB).
+ * The allocation is page aligned and the content is undefined.
+ *
+ * @returns Pointer to the memory block. This is page aligned.
+ * @param   pPhys   Where to store the physical address.
+ * @param   cb      The allocation size in bytes. This is always
+ *                  rounded up to PAGE_SIZE.
+ */
+RTR0DECL(void *) RTMemContAlloc(PRTCCPHYS pPhys, size_t cb)
+{
+    int             cOrder;
+    unsigned        cPages;
+    struct page    *paPages;
+    void           *pvRet;
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    /*
+     * validate input.
+     */
+    Assert(VALID_PTR(pPhys));
+    Assert(cb > 0);
+
+    /*
+     * Allocate page pointer array.
+     */
+    cb = RT_ALIGN_Z(cb, PAGE_SIZE);
+    cPages = cb >> PAGE_SHIFT;
+    cOrder = CalcPowerOf2Order(cPages);
+#if (defined(RT_ARCH_AMD64) || defined(CONFIG_X86_PAE)) && defined(GFP_DMA32)
+    /* ZONE_DMA32: 0-4GB */
+    paPages = alloc_pages(GFP_DMA32 | __GFP_NOWARN, cOrder);
+    if (!paPages)
+#endif
+#ifdef RT_ARCH_AMD64
+        /* ZONE_DMA; 0-16MB */
+        paPages = alloc_pages(GFP_DMA | __GFP_NOWARN, cOrder);
+#else
+        /* ZONE_NORMAL: 0-896MB */
+        paPages = alloc_pages(GFP_USER | __GFP_NOWARN, cOrder);
+#endif
+    if (paPages)
+    {
+        /*
+         * Reserve the pages and mark them executable.
+         */
+        unsigned iPage;
+        for (iPage = 0; iPage < cPages; iPage++)
+        {
+            Assert(!PageHighMem(&paPages[iPage]));
+            if (iPage + 1 < cPages)
+            {
+                AssertMsg(          (uintptr_t)phys_to_virt(page_to_phys(&paPages[iPage])) + PAGE_SIZE
+                                ==  (uintptr_t)phys_to_virt(page_to_phys(&paPages[iPage + 1]))
+                          &&        page_to_phys(&paPages[iPage]) + PAGE_SIZE
+                                ==  page_to_phys(&paPages[iPage + 1]),
+                          ("iPage=%i cPages=%u [0]=%#llx,%p [1]=%#llx,%p\n", iPage, cPages,
+                           (long long)page_to_phys(&paPages[iPage]),     phys_to_virt(page_to_phys(&paPages[iPage])),
+                           (long long)page_to_phys(&paPages[iPage + 1]), phys_to_virt(page_to_phys(&paPages[iPage + 1])) ));
+            }
+
+            SetPageReserved(&paPages[iPage]);
+        }
+        *pPhys = page_to_phys(paPages);
+        pvRet = phys_to_virt(page_to_phys(paPages));
+    }
+    else
+        pvRet = NULL;
+
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return pvRet;
+}
+RT_EXPORT_SYMBOL(RTMemContAlloc);
+
+
+/**
+ * Frees memory allocated using RTMemContAlloc().
+ *
+ * @param   pv      Pointer to return from RTMemContAlloc().
+ * @param   cb      The cb parameter passed to RTMemContAlloc().
+ */
+RTR0DECL(void) RTMemContFree(void *pv, size_t cb)
+{
+    if (pv)
+    {
+        int             cOrder;
+        unsigned        cPages;
+        unsigned        iPage;
+        struct page    *paPages;
+        IPRT_LINUX_SAVE_EFL_AC();
+
+        /* validate */
+        AssertMsg(!((uintptr_t)pv & PAGE_OFFSET_MASK), ("pv=%p\n", pv));
+        Assert(cb > 0);
+
+        /* calc order and get pages */
+        cb = RT_ALIGN_Z(cb, PAGE_SIZE);
+        cPages = cb >> PAGE_SHIFT;
+        cOrder = CalcPowerOf2Order(cPages);
+        paPages = virt_to_page(pv);
+
+        /*
+         * Restore page attributes freeing the pages.
+         */
+        for (iPage = 0; iPage < cPages; iPage++)
+        {
+            ClearPageReserved(&paPages[iPage]);
+        }
+        __free_pages(paPages, cOrder);
+        IPRT_LINUX_RESTORE_EFL_AC();
+    }
+}
+RT_EXPORT_SYMBOL(RTMemContFree);
+
diff --git a/src/VBox/Runtime/r0drv/linux/assert-r0drv-linux.c b/src/VBox/Runtime/r0drv/linux/assert-r0drv-linux.c
new file mode 100644
index 00000000..ba78b437
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/assert-r0drv-linux.c
@@ -0,0 +1,74 @@
+/* $Id: assert-r0drv-linux.c $ */
+/** @file
+ * IPRT -  Assertion Workers, Ring-0 Drivers, Linux.
+ */
+
+/*
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-linux-kernel.h"
+#include "internal/iprt.h"
+
+#include <iprt/assert.h>
+#include <iprt/log.h>
+#include <iprt/string.h>
+#include <iprt/stdarg.h>
+#include <iprt/asm.h>
+
+#include "internal/assert.h"
+
+
+DECLHIDDEN(void) rtR0AssertNativeMsg1(const char *pszExpr, unsigned uLine, const char *pszFile, const char *pszFunction)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+    printk(KERN_EMERG
+           "\r\n!!Assertion Failed!!\r\n"
+           "Expression: %s\r\n"
+           "Location  : %s(%d) %s\r\n",
+           pszExpr, pszFile, uLine, pszFunction);
+    IPRT_LINUX_RESTORE_EFL_AC();
+}
+
+
+DECLHIDDEN(void) rtR0AssertNativeMsg2V(bool fInitial, const char *pszFormat, va_list va)
+{
+    char szMsg[256];
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    RTStrPrintfV(szMsg, sizeof(szMsg) - 1, pszFormat, va);
+    szMsg[sizeof(szMsg) - 1] = '\0';
+    printk(KERN_EMERG "%s", szMsg);
+
+    NOREF(fInitial);
+    IPRT_LINUX_RESTORE_EFL_AC();
+}
+
+
+RTR0DECL(void) RTR0AssertPanicSystem(void)
+{
+    panic("%s%s", g_szRTAssertMsg1, g_szRTAssertMsg2);
+}
+RT_EXPORT_SYMBOL(RTR0AssertPanicSystem);
+
diff --git a/src/VBox/Runtime/r0drv/linux/initterm-r0drv-linux.c b/src/VBox/Runtime/r0drv/linux/initterm-r0drv-linux.c
new file mode 100644
index 00000000..9d6b4d4e
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/initterm-r0drv-linux.c
@@ -0,0 +1,130 @@
+/* $Id: initterm-r0drv-linux.c $ */
+/** @file
+ * IPRT - Initialization & Termination, R0 Driver, Linux.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-linux-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/errcore.h>
+#include <iprt/assert.h>
+#include "internal/initterm.h"
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/** The IPRT work queue. */
+#if RTLNX_VER_MIN(2,5,41)
+static struct workqueue_struct *g_prtR0LnxWorkQueue;
+#else
+static DECLARE_TASK_QUEUE(g_rtR0LnxWorkQueue);
+#endif
+
+
+/**
+ * Pushes an item onto the IPRT work queue.
+ *
+ * @param   pWork               The work item.
+ * @param   pfnWorker           The callback function.  It will be called back
+ *                              with @a pWork as argument.
+ */
+DECLHIDDEN(void) rtR0LnxWorkqueuePush(RTR0LNXWORKQUEUEITEM *pWork, void (*pfnWorker)(RTR0LNXWORKQUEUEITEM *))
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+
+#if RTLNX_VER_MIN(2,5,41)
+# if RTLNX_VER_MIN(2,6,20)
+    INIT_WORK(pWork, pfnWorker);
+# else
+    INIT_WORK(pWork, (void (*)(void *))pfnWorker, pWork);
+# endif
+    queue_work(g_prtR0LnxWorkQueue, pWork);
+#else
+    INIT_TQUEUE(pWork, (void (*)(void *))pfnWorker, pWork);
+    queue_task(pWork, &g_rtR0LnxWorkQueue);
+#endif
+
+    IPRT_LINUX_RESTORE_EFL_AC();
+}
+
+
+/**
+ * Flushes all items in the IPRT work queue.
+ *
+ * @remarks This is mostly for 2.4.x compatability.  Must not be called from
+ *          atomic contexts or with unncessary locks held.
+ */
+DECLHIDDEN(void) rtR0LnxWorkqueueFlush(void)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+
+#if RTLNX_VER_MIN(2,5,41)
+    flush_workqueue(g_prtR0LnxWorkQueue);
+#else
+    run_task_queue(&g_rtR0LnxWorkQueue);
+#endif
+
+    IPRT_LINUX_RESTORE_EFL_AC();
+}
+
+
+DECLHIDDEN(int) rtR0InitNative(void)
+{
+    int rc = VINF_SUCCESS;
+    IPRT_LINUX_SAVE_EFL_AC();
+
+#if RTLNX_VER_MIN(2,5,41)
+ #if RTLNX_VER_MIN(2,6,13)
+    g_prtR0LnxWorkQueue = create_workqueue("iprt-VBoxWQueue");
+ #else
+    g_prtR0LnxWorkQueue = create_workqueue("iprt-VBoxQ");
+ #endif
+    if (!g_prtR0LnxWorkQueue)
+        rc = VERR_NO_MEMORY;
+#endif
+
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return rc;
+}
+
+
+DECLHIDDEN(void) rtR0TermNative(void)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    rtR0LnxWorkqueueFlush();
+#if RTLNX_VER_MIN(2,5,41)
+    destroy_workqueue(g_prtR0LnxWorkQueue);
+    g_prtR0LnxWorkQueue = NULL;
+#endif
+
+    rtR0MemExecCleanup();
+
+    IPRT_LINUX_RESTORE_EFL_AC();
+}
+
diff --git a/src/VBox/Runtime/r0drv/linux/memobj-r0drv-linux.c b/src/VBox/Runtime/r0drv/linux/memobj-r0drv-linux.c
new file mode 100644
index 00000000..6ae59089
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/memobj-r0drv-linux.c
@@ -0,0 +1,1966 @@
+/* $Id: memobj-r0drv-linux.c $ */
+/** @file
+ * IPRT - Ring-0 Memory Objects, Linux.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-linux-kernel.h"
+
+#include <iprt/memobj.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/log.h>
+#include <iprt/mem.h>
+#include <iprt/process.h>
+#include <iprt/string.h>
+#include "internal/memobj.h"
+#include "internal/iprt.h"
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+/* early 2.6 kernels */
+#ifndef PAGE_SHARED_EXEC
+# define PAGE_SHARED_EXEC PAGE_SHARED
+#endif
+#ifndef PAGE_READONLY_EXEC
+# define PAGE_READONLY_EXEC PAGE_READONLY
+#endif
+
+/** @def IPRT_USE_ALLOC_VM_AREA_FOR_EXEC
+ * Whether we use alloc_vm_area (3.2+) for executable memory.
+ * This is a must for 5.8+, but we enable it all the way back to 3.2.x for
+ * better W^R compliance (fExecutable flag). */
+#if RTLNX_VER_RANGE(3,2,0, 5,10,0) || defined(DOXYGEN_RUNNING)
+# define IPRT_USE_ALLOC_VM_AREA_FOR_EXEC
+#endif
+/** @def IPRT_USE_APPLY_TO_PAGE_RANGE_FOR_EXEC
+ * alloc_vm_area was removed with 5.10 so we have to resort to a different way
+ * to allocate executable memory.
+ * It would be possible to remove IPRT_USE_ALLOC_VM_AREA_FOR_EXEC and use
+ * this path execlusively for 3.2+ but no time to test it really works on every
+ * supported kernel, so better play safe for now.
+ */
+#if RTLNX_VER_MIN(5,10,0) || defined(DOXYGEN_RUNNING)
+# define IPRT_USE_APPLY_TO_PAGE_RANGE_FOR_EXEC
+#endif
+
+/*
+ * 2.6.29+ kernels don't work with remap_pfn_range() anymore because
+ * track_pfn_vma_new() is apparently not defined for non-RAM pages.
+ * It should be safe to use vm_insert_page() older kernels as well.
+ */
+#if RTLNX_VER_MIN(2,6,23)
+# define VBOX_USE_INSERT_PAGE
+#endif
+#if    defined(CONFIG_X86_PAE) \
+    && (   defined(HAVE_26_STYLE_REMAP_PAGE_RANGE) \
+        || RTLNX_VER_RANGE(2,6,0,  2,6,11) )
+# define VBOX_USE_PAE_HACK
+#endif
+
+/* gfp_t was introduced in 2.6.14, define it for earlier. */
+#if RTLNX_VER_MAX(2,6,14)
+# define gfp_t  unsigned
+#endif
+
+/*
+ * Wrappers around mmap_lock/mmap_sem difference.
+ */
+#if RTLNX_VER_MIN(5,8,0)
+# define LNX_MM_DOWN_READ(a_pMm)    down_read(&(a_pMm)->mmap_lock)
+# define LNX_MM_UP_READ(a_pMm)        up_read(&(a_pMm)->mmap_lock)
+# define LNX_MM_DOWN_WRITE(a_pMm)   down_write(&(a_pMm)->mmap_lock)
+# define LNX_MM_UP_WRITE(a_pMm)       up_write(&(a_pMm)->mmap_lock)
+#else
+# define LNX_MM_DOWN_READ(a_pMm)    down_read(&(a_pMm)->mmap_sem)
+# define LNX_MM_UP_READ(a_pMm)        up_read(&(a_pMm)->mmap_sem)
+# define LNX_MM_DOWN_WRITE(a_pMm)   down_write(&(a_pMm)->mmap_sem)
+# define LNX_MM_UP_WRITE(a_pMm)       up_write(&(a_pMm)->mmap_sem)
+#endif
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * The Linux version of the memory object structure.
+ */
+typedef struct RTR0MEMOBJLNX
+{
+    /** The core structure. */
+    RTR0MEMOBJINTERNAL  Core;
+    /** Set if the allocation is contiguous.
+     * This means it has to be given back as one chunk. */
+    bool                fContiguous;
+    /** Set if executable allocation. */
+    bool                fExecutable;
+    /** Set if we've vmap'ed the memory into ring-0. */
+    bool                fMappedToRing0;
+#ifdef IPRT_USE_ALLOC_VM_AREA_FOR_EXEC
+    /** Return from alloc_vm_area() that we now need to use for executable
+     *  memory. */
+    struct vm_struct   *pArea;
+    /** PTE array that goes along with pArea (must be freed). */
+    pte_t             **papPtesForArea;
+#endif
+    /** The pages in the apPages array. */
+    size_t              cPages;
+    /** Array of struct page pointers. (variable size) */
+    struct page        *apPages[1];
+} RTR0MEMOBJLNX;
+/** Pointer to the linux memory object. */
+typedef RTR0MEMOBJLNX *PRTR0MEMOBJLNX;
+
+
+static void rtR0MemObjLinuxFreePages(PRTR0MEMOBJLNX pMemLnx);
+
+
+/**
+ * Helper that converts from a RTR0PROCESS handle to a linux task.
+ *
+ * @returns The corresponding Linux task.
+ * @param   R0Process   IPRT ring-0 process handle.
+ */
+static struct task_struct *rtR0ProcessToLinuxTask(RTR0PROCESS R0Process)
+{
+    /** @todo fix rtR0ProcessToLinuxTask!! */
+    /** @todo many (all?) callers currently assume that we return 'current'! */
+    return R0Process == RTR0ProcHandleSelf() ? current : NULL;
+}
+
+
+/**
+ * Compute order. Some functions allocate 2^order pages.
+ *
+ * @returns order.
+ * @param   cPages      Number of pages.
+ */
+static int rtR0MemObjLinuxOrder(size_t cPages)
+{
+    int     iOrder;
+    size_t  cTmp;
+
+    for (iOrder = 0, cTmp = cPages; cTmp >>= 1; ++iOrder)
+        ;
+    if (cPages & ~((size_t)1 << iOrder))
+        ++iOrder;
+
+    return iOrder;
+}
+
+
+/**
+ * Converts from RTMEM_PROT_* to Linux PAGE_*.
+ *
+ * @returns Linux page protection constant.
+ * @param   fProt       The IPRT protection mask.
+ * @param   fKernel     Whether it applies to kernel or user space.
+ */
+static pgprot_t rtR0MemObjLinuxConvertProt(unsigned fProt, bool fKernel)
+{
+    switch (fProt)
+    {
+        default:
+            AssertMsgFailed(("%#x %d\n", fProt, fKernel)); RT_FALL_THRU();
+        case RTMEM_PROT_NONE:
+            return PAGE_NONE;
+
+        case RTMEM_PROT_READ:
+            return fKernel ? PAGE_KERNEL_RO         : PAGE_READONLY;
+
+        case RTMEM_PROT_WRITE:
+        case RTMEM_PROT_WRITE | RTMEM_PROT_READ:
+            return fKernel ? PAGE_KERNEL            : PAGE_SHARED;
+
+        case RTMEM_PROT_EXEC:
+        case RTMEM_PROT_EXEC | RTMEM_PROT_READ:
+#if defined(RT_ARCH_X86) || defined(RT_ARCH_AMD64)
+            if (fKernel)
+            {
+                pgprot_t fPg = MY_PAGE_KERNEL_EXEC;
+                pgprot_val(fPg) &= ~_PAGE_RW;
+                return fPg;
+            }
+            return PAGE_READONLY_EXEC;
+#else
+            return fKernel ? MY_PAGE_KERNEL_EXEC    : PAGE_READONLY_EXEC;
+#endif
+
+        case RTMEM_PROT_WRITE | RTMEM_PROT_EXEC:
+        case RTMEM_PROT_WRITE | RTMEM_PROT_EXEC | RTMEM_PROT_READ:
+            return fKernel ? MY_PAGE_KERNEL_EXEC    : PAGE_SHARED_EXEC;
+    }
+}
+
+
+/**
+ * Worker for rtR0MemObjNativeReserveUser and rtR0MemObjNativerMapUser that creates
+ * an empty user space mapping.
+ *
+ * We acquire the mmap_sem/mmap_lock of the task!
+ *
+ * @returns Pointer to the mapping.
+ *          (void *)-1 on failure.
+ * @param   R3PtrFixed  (RTR3PTR)-1 if anywhere, otherwise a specific location.
+ * @param   cb          The size of the mapping.
+ * @param   uAlignment  The alignment of the mapping.
+ * @param   pTask       The Linux task to create this mapping in.
+ * @param   fProt       The RTMEM_PROT_* mask.
+ */
+static void *rtR0MemObjLinuxDoMmap(RTR3PTR R3PtrFixed, size_t cb, size_t uAlignment, struct task_struct *pTask, unsigned fProt)
+{
+    unsigned fLnxProt;
+    unsigned long ulAddr;
+
+    Assert(pTask == current); /* do_mmap */
+    RT_NOREF_PV(pTask);
+
+    /*
+     * Convert from IPRT protection to mman.h PROT_ and call do_mmap.
+     */
+    fProt &= (RTMEM_PROT_NONE | RTMEM_PROT_READ | RTMEM_PROT_WRITE | RTMEM_PROT_EXEC);
+    if (fProt == RTMEM_PROT_NONE)
+        fLnxProt = PROT_NONE;
+    else
+    {
+        fLnxProt = 0;
+        if (fProt & RTMEM_PROT_READ)
+            fLnxProt |= PROT_READ;
+        if (fProt & RTMEM_PROT_WRITE)
+            fLnxProt |= PROT_WRITE;
+        if (fProt & RTMEM_PROT_EXEC)
+            fLnxProt |= PROT_EXEC;
+    }
+
+    if (R3PtrFixed != (RTR3PTR)-1)
+    {
+#if RTLNX_VER_MIN(3,5,0)
+        ulAddr = vm_mmap(NULL, R3PtrFixed, cb, fLnxProt, MAP_SHARED | MAP_ANONYMOUS | MAP_FIXED, 0);
+#else
+        LNX_MM_DOWN_WRITE(pTask->mm);
+        ulAddr = do_mmap(NULL, R3PtrFixed, cb, fLnxProt, MAP_SHARED | MAP_ANONYMOUS | MAP_FIXED, 0);
+        LNX_MM_UP_WRITE(pTask->mm);
+#endif
+    }
+    else
+    {
+#if RTLNX_VER_MIN(3,5,0)
+        ulAddr = vm_mmap(NULL, 0, cb, fLnxProt, MAP_SHARED | MAP_ANONYMOUS, 0);
+#else
+        LNX_MM_DOWN_WRITE(pTask->mm);
+        ulAddr = do_mmap(NULL, 0, cb, fLnxProt, MAP_SHARED | MAP_ANONYMOUS, 0);
+        LNX_MM_UP_WRITE(pTask->mm);
+#endif
+        if (    !(ulAddr & ~PAGE_MASK)
+            &&  (ulAddr & (uAlignment - 1)))
+        {
+            /** @todo implement uAlignment properly... We'll probably need to make some dummy mappings to fill
+             * up alignment gaps. This is of course complicated by fragmentation (which we might have cause
+             * ourselves) and further by there begin two mmap strategies (top / bottom). */
+            /* For now, just ignore uAlignment requirements... */
+        }
+    }
+
+
+    if (ulAddr & ~PAGE_MASK) /* ~PAGE_MASK == PAGE_OFFSET_MASK */
+        return (void *)-1;
+    return (void *)ulAddr;
+}
+
+
+/**
+ * Worker that destroys a user space mapping.
+ * Undoes what rtR0MemObjLinuxDoMmap did.
+ *
+ * We acquire the mmap_sem/mmap_lock of the task!
+ *
+ * @param   pv          The ring-3 mapping.
+ * @param   cb          The size of the mapping.
+ * @param   pTask       The Linux task to destroy this mapping in.
+ */
+static void rtR0MemObjLinuxDoMunmap(void *pv, size_t cb, struct task_struct *pTask)
+{
+#if RTLNX_VER_MIN(3,5,0)
+    Assert(pTask == current); RT_NOREF_PV(pTask);
+    vm_munmap((unsigned long)pv, cb);
+#elif defined(USE_RHEL4_MUNMAP)
+    LNX_MM_DOWN_WRITE(pTask->mm);
+    do_munmap(pTask->mm, (unsigned long)pv, cb, 0); /* should it be 1 or 0? */
+    LNX_MM_UP_WRITE(pTask->mm);
+#else
+    LNX_MM_DOWN_WRITE(pTask->mm);
+    do_munmap(pTask->mm, (unsigned long)pv, cb);
+    LNX_MM_UP_WRITE(pTask->mm);
+#endif
+}
+
+
+/**
+ * Internal worker that allocates physical pages and creates the memory object for them.
+ *
+ * @returns IPRT status code.
+ * @param   ppMemLnx    Where to store the memory object pointer.
+ * @param   enmType     The object type.
+ * @param   cb          The number of bytes to allocate.
+ * @param   uAlignment  The alignment of the physical memory.
+ *                      Only valid if fContiguous == true, ignored otherwise.
+ * @param   fFlagsLnx   The page allocation flags (GPFs).
+ * @param   fContiguous Whether the allocation must be contiguous.
+ * @param   fExecutable Whether the memory must be executable.
+ * @param   rcNoMem     What to return when we're out of pages.
+ */
+static int rtR0MemObjLinuxAllocPages(PRTR0MEMOBJLNX *ppMemLnx, RTR0MEMOBJTYPE enmType, size_t cb,
+                                     size_t uAlignment, gfp_t fFlagsLnx, bool fContiguous, bool fExecutable, int rcNoMem)
+{
+    size_t          iPage;
+    size_t const    cPages = cb >> PAGE_SHIFT;
+    struct page    *paPages;
+
+    /*
+     * Allocate a memory object structure that's large enough to contain
+     * the page pointer array.
+     */
+    PRTR0MEMOBJLNX  pMemLnx = (PRTR0MEMOBJLNX)rtR0MemObjNew(RT_UOFFSETOF_DYN(RTR0MEMOBJLNX, apPages[cPages]), enmType, NULL, cb);
+    if (!pMemLnx)
+        return VERR_NO_MEMORY;
+    pMemLnx->cPages = cPages;
+
+     if (cPages > 255)
+     {
+# ifdef __GFP_REPEAT
+         /* Try hard to allocate the memory, but the allocation attempt might fail. */
+        fFlagsLnx |= __GFP_REPEAT;
+# endif
+# ifdef __GFP_NOMEMALLOC
+        /* Introduced with Linux 2.6.12: Don't use emergency reserves */
+        fFlagsLnx |= __GFP_NOMEMALLOC;
+# endif
+     }
+
+    /*
+     * Allocate the pages.
+     * For small allocations we'll try contiguous first and then fall back on page by page.
+     */
+#if RTLNX_VER_MIN(2,4,22)
+    if (    fContiguous
+        ||  cb <= PAGE_SIZE * 2)
+    {
+# ifdef VBOX_USE_INSERT_PAGE
+        paPages = alloc_pages(fFlagsLnx | __GFP_COMP | __GFP_NOWARN, rtR0MemObjLinuxOrder(cPages));
+# else
+        paPages = alloc_pages(fFlagsLnx | __GFP_NOWARN, rtR0MemObjLinuxOrder(cPages));
+# endif
+        if (paPages)
+        {
+            fContiguous = true;
+            for (iPage = 0; iPage < cPages; iPage++)
+                pMemLnx->apPages[iPage] = &paPages[iPage];
+        }
+        else if (fContiguous)
+        {
+            rtR0MemObjDelete(&pMemLnx->Core);
+            return rcNoMem;
+        }
+    }
+
+    if (!fContiguous)
+    {
+        for (iPage = 0; iPage < cPages; iPage++)
+        {
+            pMemLnx->apPages[iPage] = alloc_page(fFlagsLnx | __GFP_NOWARN);
+            if (RT_UNLIKELY(!pMemLnx->apPages[iPage]))
+            {
+                while (iPage-- > 0)
+                    __free_page(pMemLnx->apPages[iPage]);
+                rtR0MemObjDelete(&pMemLnx->Core);
+                return rcNoMem;
+            }
+        }
+    }
+
+#else /* < 2.4.22 */
+    /** @todo figure out why we didn't allocate page-by-page on 2.4.21 and older... */
+    paPages = alloc_pages(fFlagsLnx, rtR0MemObjLinuxOrder(cPages));
+    if (!paPages)
+    {
+        rtR0MemObjDelete(&pMemLnx->Core);
+        return rcNoMem;
+    }
+    for (iPage = 0; iPage < cPages; iPage++)
+    {
+        pMemLnx->apPages[iPage] = &paPages[iPage];
+        if (fExecutable)
+            MY_SET_PAGES_EXEC(pMemLnx->apPages[iPage], 1);
+        if (PageHighMem(pMemLnx->apPages[iPage]))
+            BUG();
+    }
+
+    fContiguous = true;
+#endif /* < 2.4.22 */
+    pMemLnx->fContiguous = fContiguous;
+    pMemLnx->fExecutable = fExecutable;
+
+#if RTLNX_VER_MAX(4,5,0)
+    /*
+     * Reserve the pages.
+     *
+     * Linux >= 4.5 with CONFIG_DEBUG_VM panics when setting PG_reserved on compound
+     * pages. According to Michal Hocko this shouldn't be necessary anyway because
+     * as pages which are not on the LRU list are never evictable.
+     */
+    for (iPage = 0; iPage < cPages; iPage++)
+        SetPageReserved(pMemLnx->apPages[iPage]);
+#endif
+
+    /*
+     * Note that the physical address of memory allocated with alloc_pages(flags, order)
+     * is always 2^(PAGE_SHIFT+order)-aligned.
+     */
+    if (   fContiguous
+        && uAlignment > PAGE_SIZE)
+    {
+        /*
+         * Check for alignment constraints. The physical address of memory allocated with
+         * alloc_pages(flags, order) is always 2^(PAGE_SHIFT+order)-aligned.
+         */
+        if (RT_UNLIKELY(page_to_phys(pMemLnx->apPages[0]) & (uAlignment - 1)))
+        {
+            /*
+             * This should never happen!
+             */
+            printk("rtR0MemObjLinuxAllocPages(cb=0x%lx, uAlignment=0x%lx): alloc_pages(..., %d) returned physical memory at 0x%lx!\n",
+                   (unsigned long)cb, (unsigned long)uAlignment, rtR0MemObjLinuxOrder(cPages), (unsigned long)page_to_phys(pMemLnx->apPages[0]));
+            rtR0MemObjLinuxFreePages(pMemLnx);
+            return rcNoMem;
+        }
+    }
+
+    *ppMemLnx = pMemLnx;
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Frees the physical pages allocated by the rtR0MemObjLinuxAllocPages() call.
+ *
+ * This method does NOT free the object.
+ *
+ * @param   pMemLnx     The object which physical pages should be freed.
+ */
+static void rtR0MemObjLinuxFreePages(PRTR0MEMOBJLNX pMemLnx)
+{
+    size_t iPage = pMemLnx->cPages;
+    if (iPage > 0)
+    {
+        /*
+         * Restore the page flags.
+         */
+        while (iPage-- > 0)
+        {
+#if RTLNX_VER_MAX(4,5,0)
+            /* See SetPageReserved() in rtR0MemObjLinuxAllocPages() */
+            ClearPageReserved(pMemLnx->apPages[iPage]);
+#endif
+#if RTLNX_VER_MAX(2,4,22)
+            if (pMemLnx->fExecutable)
+                MY_SET_PAGES_NOEXEC(pMemLnx->apPages[iPage], 1);
+#endif
+        }
+
+        /*
+         * Free the pages.
+         */
+#if RTLNX_VER_MIN(2,4,22)
+        if (!pMemLnx->fContiguous)
+        {
+            iPage = pMemLnx->cPages;
+            while (iPage-- > 0)
+                __free_page(pMemLnx->apPages[iPage]);
+        }
+        else
+#endif
+            __free_pages(pMemLnx->apPages[0], rtR0MemObjLinuxOrder(pMemLnx->cPages));
+
+        pMemLnx->cPages = 0;
+    }
+}
+
+
+#ifdef IPRT_USE_APPLY_TO_PAGE_RANGE_FOR_EXEC
+/**
+ * User data passed to the apply_to_page_range() callback.
+ */
+typedef struct LNXAPPLYPGRANGE
+{
+    /** Pointer to the memory object. */
+    PRTR0MEMOBJLNX pMemLnx;
+    /** The page protection flags to apply. */
+    pgprot_t       fPg;
+} LNXAPPLYPGRANGE;
+/** Pointer to the user data. */
+typedef LNXAPPLYPGRANGE *PLNXAPPLYPGRANGE;
+/** Pointer to the const user data. */
+typedef const LNXAPPLYPGRANGE *PCLNXAPPLYPGRANGE;
+
+/**
+ * Callback called in apply_to_page_range().
+ *
+ * @returns Linux status code.
+ * @param   pPte                Pointer to the page table entry for the given address.
+ * @param   uAddr               The address to apply the new protection to.
+ * @param   pvUser              The opaque user data.
+ */
+static int rtR0MemObjLinuxApplyPageRange(pte_t *pPte, unsigned long uAddr, void *pvUser)
+{
+    PCLNXAPPLYPGRANGE pArgs = (PCLNXAPPLYPGRANGE)pvUser;
+    PRTR0MEMOBJLNX pMemLnx = pArgs->pMemLnx;
+    size_t idxPg = (uAddr - (unsigned long)pMemLnx->Core.pv) >> PAGE_SHIFT;
+
+    set_pte(pPte, mk_pte(pMemLnx->apPages[idxPg], pArgs->fPg));
+    return 0;
+}
+#endif
+
+
+/**
+ * Maps the allocation into ring-0.
+ *
+ * This will update the RTR0MEMOBJLNX::Core.pv and RTR0MEMOBJ::fMappedToRing0 members.
+ *
+ * Contiguous mappings that isn't in 'high' memory will already be mapped into kernel
+ * space, so we'll use that mapping if possible. If execute access is required, we'll
+ * play safe and do our own mapping.
+ *
+ * @returns IPRT status code.
+ * @param   pMemLnx     The linux memory object to map.
+ * @param   fExecutable Whether execute access is required.
+ */
+static int rtR0MemObjLinuxVMap(PRTR0MEMOBJLNX pMemLnx, bool fExecutable)
+{
+    int rc = VINF_SUCCESS;
+
+    /*
+     * Choose mapping strategy.
+     */
+    bool fMustMap = fExecutable
+                 || !pMemLnx->fContiguous;
+    if (!fMustMap)
+    {
+        size_t iPage = pMemLnx->cPages;
+        while (iPage-- > 0)
+            if (PageHighMem(pMemLnx->apPages[iPage]))
+            {
+                fMustMap = true;
+                break;
+            }
+    }
+
+    Assert(!pMemLnx->Core.pv);
+    Assert(!pMemLnx->fMappedToRing0);
+
+    if (fMustMap)
+    {
+        /*
+         * Use vmap - 2.4.22 and later.
+         */
+#if RTLNX_VER_MIN(2,4,22)
+        pgprot_t fPg;
+        pgprot_val(fPg) = _PAGE_PRESENT | _PAGE_RW;
+# ifdef _PAGE_NX
+        if (!fExecutable)
+            pgprot_val(fPg) |= _PAGE_NX;
+# endif
+
+# ifdef IPRT_USE_ALLOC_VM_AREA_FOR_EXEC
+        if (fExecutable)
+        {
+#  if RTLNX_VER_MIN(3,2,51)
+            pte_t **papPtes = (pte_t **)kmalloc_array(pMemLnx->cPages, sizeof(papPtes[0]), GFP_KERNEL);
+#  else
+            pte_t **papPtes = (pte_t **)kmalloc(pMemLnx->cPages * sizeof(papPtes[0]), GFP_KERNEL);
+#  endif
+            if (papPtes)
+            {
+                pMemLnx->pArea = alloc_vm_area(pMemLnx->Core.cb, papPtes); /* Note! pArea->nr_pages is not set. */
+                if (pMemLnx->pArea)
+                {
+                    size_t i;
+                    Assert(pMemLnx->pArea->size >= pMemLnx->Core.cb);   /* Note! includes guard page. */
+                    Assert(pMemLnx->pArea->addr);
+#  ifdef _PAGE_NX
+                    pgprot_val(fPg) |= _PAGE_NX; /* Uses RTR0MemObjProtect to clear NX when memory ready, W^X fashion. */
+#  endif
+                    pMemLnx->papPtesForArea = papPtes;
+                    for (i = 0; i < pMemLnx->cPages; i++)
+                        *papPtes[i] = mk_pte(pMemLnx->apPages[i], fPg);
+                    pMemLnx->Core.pv = pMemLnx->pArea->addr;
+                    pMemLnx->fMappedToRing0 = true;
+                }
+                else
+                {
+                    kfree(papPtes);
+                    rc = VERR_MAP_FAILED;
+                }
+            }
+            else
+                rc = VERR_MAP_FAILED;
+        }
+        else
+# endif
+        {
+#  if defined(IPRT_USE_APPLY_TO_PAGE_RANGE_FOR_EXEC)
+            if (fExecutable)
+                pgprot_val(fPg) |= _PAGE_NX; /* Uses RTR0MemObjProtect to clear NX when memory ready, W^X fashion. */
+#  endif
+
+# ifdef VM_MAP
+            pMemLnx->Core.pv = vmap(&pMemLnx->apPages[0], pMemLnx->cPages, VM_MAP, fPg);
+# else
+            pMemLnx->Core.pv = vmap(&pMemLnx->apPages[0], pMemLnx->cPages, VM_ALLOC, fPg);
+# endif
+            if (pMemLnx->Core.pv)
+                pMemLnx->fMappedToRing0 = true;
+            else
+                rc = VERR_MAP_FAILED;
+        }
+#else   /* < 2.4.22 */
+        rc = VERR_NOT_SUPPORTED;
+#endif
+    }
+    else
+    {
+        /*
+         * Use the kernel RAM mapping.
+         */
+        pMemLnx->Core.pv = phys_to_virt(page_to_phys(pMemLnx->apPages[0]));
+        Assert(pMemLnx->Core.pv);
+    }
+
+    return rc;
+}
+
+
+/**
+ * Undoes what rtR0MemObjLinuxVMap() did.
+ *
+ * @param   pMemLnx     The linux memory object.
+ */
+static void rtR0MemObjLinuxVUnmap(PRTR0MEMOBJLNX pMemLnx)
+{
+#if RTLNX_VER_MIN(2,4,22)
+# ifdef IPRT_USE_ALLOC_VM_AREA_FOR_EXEC
+    if (pMemLnx->pArea)
+    {
+#  if 0
+        pte_t **papPtes = pMemLnx->papPtesForArea;
+        size_t  i;
+        for (i = 0; i < pMemLnx->cPages; i++)
+            *papPtes[i] = 0;
+#  endif
+        free_vm_area(pMemLnx->pArea);
+        kfree(pMemLnx->papPtesForArea);
+        pMemLnx->pArea = NULL;
+        pMemLnx->papPtesForArea = NULL;
+    }
+    else
+# endif
+    if (pMemLnx->fMappedToRing0)
+    {
+        Assert(pMemLnx->Core.pv);
+        vunmap(pMemLnx->Core.pv);
+        pMemLnx->fMappedToRing0 = false;
+    }
+#else /* < 2.4.22 */
+    Assert(!pMemLnx->fMappedToRing0);
+#endif
+    pMemLnx->Core.pv = NULL;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeFree(RTR0MEMOBJ pMem)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+    PRTR0MEMOBJLNX pMemLnx = (PRTR0MEMOBJLNX)pMem;
+
+    /*
+     * Release any memory that we've allocated or locked.
+     */
+    switch (pMemLnx->Core.enmType)
+    {
+        case RTR0MEMOBJTYPE_LOW:
+        case RTR0MEMOBJTYPE_PAGE:
+        case RTR0MEMOBJTYPE_CONT:
+        case RTR0MEMOBJTYPE_PHYS:
+        case RTR0MEMOBJTYPE_PHYS_NC:
+            rtR0MemObjLinuxVUnmap(pMemLnx);
+            rtR0MemObjLinuxFreePages(pMemLnx);
+            break;
+
+        case RTR0MEMOBJTYPE_LOCK:
+            if (pMemLnx->Core.u.Lock.R0Process != NIL_RTR0PROCESS)
+            {
+                struct task_struct *pTask = rtR0ProcessToLinuxTask(pMemLnx->Core.u.Lock.R0Process);
+                size_t              iPage;
+                Assert(pTask);
+                if (pTask && pTask->mm)
+                    LNX_MM_DOWN_READ(pTask->mm);
+
+                iPage = pMemLnx->cPages;
+                while (iPage-- > 0)
+                {
+                    if (!PageReserved(pMemLnx->apPages[iPage]))
+                        SetPageDirty(pMemLnx->apPages[iPage]);
+#if RTLNX_VER_MIN(4,6,0)
+                    put_page(pMemLnx->apPages[iPage]);
+#else
+                    page_cache_release(pMemLnx->apPages[iPage]);
+#endif
+                }
+
+                if (pTask && pTask->mm)
+                    LNX_MM_UP_READ(pTask->mm);
+            }
+            /* else: kernel memory - nothing to do here. */
+            break;
+
+        case RTR0MEMOBJTYPE_RES_VIRT:
+            Assert(pMemLnx->Core.pv);
+            if (pMemLnx->Core.u.ResVirt.R0Process != NIL_RTR0PROCESS)
+            {
+                struct task_struct *pTask = rtR0ProcessToLinuxTask(pMemLnx->Core.u.Lock.R0Process);
+                Assert(pTask);
+                if (pTask && pTask->mm)
+                    rtR0MemObjLinuxDoMunmap(pMemLnx->Core.pv, pMemLnx->Core.cb, pTask);
+            }
+            else
+            {
+                vunmap(pMemLnx->Core.pv);
+
+                Assert(pMemLnx->cPages == 1 && pMemLnx->apPages[0] != NULL);
+                __free_page(pMemLnx->apPages[0]);
+                pMemLnx->apPages[0] = NULL;
+                pMemLnx->cPages = 0;
+            }
+            pMemLnx->Core.pv = NULL;
+            break;
+
+        case RTR0MEMOBJTYPE_MAPPING:
+            Assert(pMemLnx->cPages == 0); Assert(pMemLnx->Core.pv);
+            if (pMemLnx->Core.u.ResVirt.R0Process != NIL_RTR0PROCESS)
+            {
+                struct task_struct *pTask = rtR0ProcessToLinuxTask(pMemLnx->Core.u.Lock.R0Process);
+                Assert(pTask);
+                if (pTask && pTask->mm)
+                    rtR0MemObjLinuxDoMunmap(pMemLnx->Core.pv, pMemLnx->Core.cb, pTask);
+            }
+            else
+                vunmap(pMemLnx->Core.pv);
+            pMemLnx->Core.pv = NULL;
+            break;
+
+        default:
+            AssertMsgFailed(("enmType=%d\n", pMemLnx->Core.enmType));
+            return VERR_INTERNAL_ERROR;
+    }
+    IPRT_LINUX_RESTORE_EFL_ONLY_AC();
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocPage(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+    PRTR0MEMOBJLNX pMemLnx;
+    int rc;
+
+#if RTLNX_VER_MIN(2,4,22)
+    rc = rtR0MemObjLinuxAllocPages(&pMemLnx, RTR0MEMOBJTYPE_PAGE, cb, PAGE_SIZE, GFP_HIGHUSER,
+                                   false /* non-contiguous */, fExecutable, VERR_NO_MEMORY);
+#else
+    rc = rtR0MemObjLinuxAllocPages(&pMemLnx, RTR0MEMOBJTYPE_PAGE, cb, PAGE_SIZE, GFP_USER,
+                                   false /* non-contiguous */, fExecutable, VERR_NO_MEMORY);
+#endif
+    if (RT_SUCCESS(rc))
+    {
+        rc = rtR0MemObjLinuxVMap(pMemLnx, fExecutable);
+        if (RT_SUCCESS(rc))
+        {
+            *ppMem = &pMemLnx->Core;
+            IPRT_LINUX_RESTORE_EFL_AC();
+            return rc;
+        }
+
+        rtR0MemObjLinuxFreePages(pMemLnx);
+        rtR0MemObjDelete(&pMemLnx->Core);
+    }
+
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return rc;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocLow(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+    PRTR0MEMOBJLNX pMemLnx;
+    int rc;
+
+    /* Try to avoid GFP_DMA. GFM_DMA32 was introduced with Linux 2.6.15. */
+#if (defined(RT_ARCH_AMD64) || defined(CONFIG_X86_PAE)) && defined(GFP_DMA32)
+    /* ZONE_DMA32: 0-4GB */
+    rc = rtR0MemObjLinuxAllocPages(&pMemLnx, RTR0MEMOBJTYPE_LOW, cb, PAGE_SIZE, GFP_DMA32,
+                                   false /* non-contiguous */, fExecutable, VERR_NO_LOW_MEMORY);
+    if (RT_FAILURE(rc))
+#endif
+#ifdef RT_ARCH_AMD64
+        /* ZONE_DMA: 0-16MB */
+        rc = rtR0MemObjLinuxAllocPages(&pMemLnx, RTR0MEMOBJTYPE_LOW, cb, PAGE_SIZE, GFP_DMA,
+                                       false /* non-contiguous */, fExecutable, VERR_NO_LOW_MEMORY);
+#else
+# ifdef CONFIG_X86_PAE
+# endif
+        /* ZONE_NORMAL: 0-896MB */
+        rc = rtR0MemObjLinuxAllocPages(&pMemLnx, RTR0MEMOBJTYPE_LOW, cb, PAGE_SIZE, GFP_USER,
+                                       false /* non-contiguous */, fExecutable, VERR_NO_LOW_MEMORY);
+#endif
+    if (RT_SUCCESS(rc))
+    {
+        rc = rtR0MemObjLinuxVMap(pMemLnx, fExecutable);
+        if (RT_SUCCESS(rc))
+        {
+            *ppMem = &pMemLnx->Core;
+            IPRT_LINUX_RESTORE_EFL_AC();
+            return rc;
+        }
+
+        rtR0MemObjLinuxFreePages(pMemLnx);
+        rtR0MemObjDelete(&pMemLnx->Core);
+    }
+
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return rc;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocCont(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+    PRTR0MEMOBJLNX pMemLnx;
+    int rc;
+
+#if (defined(RT_ARCH_AMD64) || defined(CONFIG_X86_PAE)) && defined(GFP_DMA32)
+    /* ZONE_DMA32: 0-4GB */
+    rc = rtR0MemObjLinuxAllocPages(&pMemLnx, RTR0MEMOBJTYPE_CONT, cb, PAGE_SIZE, GFP_DMA32,
+                                   true /* contiguous */, fExecutable, VERR_NO_CONT_MEMORY);
+    if (RT_FAILURE(rc))
+#endif
+#ifdef RT_ARCH_AMD64
+        /* ZONE_DMA: 0-16MB */
+        rc = rtR0MemObjLinuxAllocPages(&pMemLnx, RTR0MEMOBJTYPE_CONT, cb, PAGE_SIZE, GFP_DMA,
+                                       true /* contiguous */, fExecutable, VERR_NO_CONT_MEMORY);
+#else
+        /* ZONE_NORMAL (32-bit hosts): 0-896MB */
+        rc = rtR0MemObjLinuxAllocPages(&pMemLnx, RTR0MEMOBJTYPE_CONT, cb, PAGE_SIZE, GFP_USER,
+                                       true /* contiguous */, fExecutable, VERR_NO_CONT_MEMORY);
+#endif
+    if (RT_SUCCESS(rc))
+    {
+        rc = rtR0MemObjLinuxVMap(pMemLnx, fExecutable);
+        if (RT_SUCCESS(rc))
+        {
+#if defined(RT_STRICT) && (defined(RT_ARCH_AMD64) || defined(CONFIG_HIGHMEM64G))
+            size_t iPage = pMemLnx->cPages;
+            while (iPage-- > 0)
+                Assert(page_to_phys(pMemLnx->apPages[iPage]) < _4G);
+#endif
+            pMemLnx->Core.u.Cont.Phys = page_to_phys(pMemLnx->apPages[0]);
+            *ppMem = &pMemLnx->Core;
+            IPRT_LINUX_RESTORE_EFL_AC();
+            return rc;
+        }
+
+        rtR0MemObjLinuxFreePages(pMemLnx);
+        rtR0MemObjDelete(&pMemLnx->Core);
+    }
+
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return rc;
+}
+
+
+/**
+ * Worker for rtR0MemObjLinuxAllocPhysSub that tries one allocation strategy.
+ *
+ * @returns IPRT status code.
+ * @param   ppMemLnx    Where to
+ * @param   enmType     The object type.
+ * @param   cb          The size of the allocation.
+ * @param   uAlignment  The alignment of the physical memory.
+ *                      Only valid for fContiguous == true, ignored otherwise.
+ * @param   PhysHighest See rtR0MemObjNativeAllocPhys.
+ * @param   fGfp        The Linux GFP flags to use for the allocation.
+ */
+static int rtR0MemObjLinuxAllocPhysSub2(PPRTR0MEMOBJINTERNAL ppMem, RTR0MEMOBJTYPE enmType,
+                                        size_t cb, size_t uAlignment, RTHCPHYS PhysHighest, gfp_t fGfp)
+{
+    PRTR0MEMOBJLNX pMemLnx;
+    int rc;
+
+    rc = rtR0MemObjLinuxAllocPages(&pMemLnx, enmType, cb, uAlignment, fGfp,
+                                   enmType == RTR0MEMOBJTYPE_PHYS /* contiguous / non-contiguous */,
+                                   false /*fExecutable*/, VERR_NO_PHYS_MEMORY);
+    if (RT_FAILURE(rc))
+        return rc;
+
+    /*
+     * Check the addresses if necessary. (Can be optimized a bit for PHYS.)
+     */
+    if (PhysHighest != NIL_RTHCPHYS)
+    {
+        size_t iPage = pMemLnx->cPages;
+        while (iPage-- > 0)
+            if (page_to_phys(pMemLnx->apPages[iPage]) > PhysHighest)
+            {
+                rtR0MemObjLinuxFreePages(pMemLnx);
+                rtR0MemObjDelete(&pMemLnx->Core);
+                return VERR_NO_MEMORY;
+            }
+    }
+
+    /*
+     * Complete the object.
+     */
+    if (enmType == RTR0MEMOBJTYPE_PHYS)
+    {
+        pMemLnx->Core.u.Phys.PhysBase = page_to_phys(pMemLnx->apPages[0]);
+        pMemLnx->Core.u.Phys.fAllocated = true;
+    }
+    *ppMem = &pMemLnx->Core;
+    return rc;
+}
+
+
+/**
+ * Worker for rtR0MemObjNativeAllocPhys and rtR0MemObjNativeAllocPhysNC.
+ *
+ * @returns IPRT status code.
+ * @param   ppMem       Where to store the memory object pointer on success.
+ * @param   enmType     The object type.
+ * @param   cb          The size of the allocation.
+ * @param   uAlignment  The alignment of the physical memory.
+ *                      Only valid for enmType == RTR0MEMOBJTYPE_PHYS, ignored otherwise.
+ * @param   PhysHighest See rtR0MemObjNativeAllocPhys.
+ */
+static int rtR0MemObjLinuxAllocPhysSub(PPRTR0MEMOBJINTERNAL ppMem, RTR0MEMOBJTYPE enmType,
+                                       size_t cb, size_t uAlignment, RTHCPHYS PhysHighest)
+{
+    int rc;
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    /*
+     * There are two clear cases and that's the <=16MB and anything-goes ones.
+     * When the physical address limit is somewhere in-between those two we'll
+     * just have to try, starting with HIGHUSER and working our way thru the
+     * different types, hoping we'll get lucky.
+     *
+     * We should probably move this physical address restriction logic up to
+     * the page alloc function as it would be more efficient there. But since
+     * we don't expect this to be a performance issue just yet it can wait.
+     */
+    if (PhysHighest == NIL_RTHCPHYS)
+        /* ZONE_HIGHMEM: the whole physical memory */
+        rc = rtR0MemObjLinuxAllocPhysSub2(ppMem, enmType, cb, uAlignment, PhysHighest, GFP_HIGHUSER);
+    else if (PhysHighest <= _1M * 16)
+        /* ZONE_DMA: 0-16MB */
+        rc = rtR0MemObjLinuxAllocPhysSub2(ppMem, enmType, cb, uAlignment, PhysHighest, GFP_DMA);
+    else
+    {
+        rc = VERR_NO_MEMORY;
+        if (RT_FAILURE(rc))
+            /* ZONE_HIGHMEM: the whole physical memory */
+            rc = rtR0MemObjLinuxAllocPhysSub2(ppMem, enmType, cb, uAlignment, PhysHighest, GFP_HIGHUSER);
+        if (RT_FAILURE(rc))
+            /* ZONE_NORMAL: 0-896MB */
+            rc = rtR0MemObjLinuxAllocPhysSub2(ppMem, enmType, cb, uAlignment, PhysHighest, GFP_USER);
+#ifdef GFP_DMA32
+        if (RT_FAILURE(rc))
+            /* ZONE_DMA32: 0-4GB */
+            rc = rtR0MemObjLinuxAllocPhysSub2(ppMem, enmType, cb, uAlignment, PhysHighest, GFP_DMA32);
+#endif
+        if (RT_FAILURE(rc))
+            /* ZONE_DMA: 0-16MB */
+            rc = rtR0MemObjLinuxAllocPhysSub2(ppMem, enmType, cb, uAlignment, PhysHighest, GFP_DMA);
+    }
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return rc;
+}
+
+
+/**
+ * Translates a kernel virtual address to a linux page structure by walking the
+ * page tables.
+ *
+ * @note    We do assume that the page tables will not change as we are walking
+ *          them.  This assumption is rather forced by the fact that I could not
+ *          immediately see any way of preventing this from happening.  So, we
+ *          take some extra care when accessing them.
+ *
+ *          Because of this, we don't want to use this function on memory where
+ *          attribute changes to nearby pages is likely to cause large pages to
+ *          be used or split up. So, don't use this for the linear mapping of
+ *          physical memory.
+ *
+ * @returns Pointer to the page structur or NULL if it could not be found.
+ * @param   pv      The kernel virtual address.
+ */
+RTDECL(struct page *) rtR0MemObjLinuxVirtToPage(void *pv)
+{
+    unsigned long   ulAddr = (unsigned long)pv;
+    unsigned long   pfn;
+    struct page    *pPage;
+    pte_t          *pEntry;
+    union
+    {
+        pgd_t       Global;
+#if RTLNX_VER_MIN(4,12,0)
+        p4d_t       Four;
+#endif
+#if RTLNX_VER_MIN(2,6,11)
+        pud_t       Upper;
+#endif
+        pmd_t       Middle;
+        pte_t       Entry;
+    } u;
+
+    /* Should this happen in a situation this code will be called in?  And if
+     * so, can it change under our feet?  See also
+     * "Documentation/vm/active_mm.txt" in the kernel sources. */
+    if (RT_UNLIKELY(!current->active_mm))
+        return NULL;
+    u.Global = *pgd_offset(current->active_mm, ulAddr);
+    if (RT_UNLIKELY(pgd_none(u.Global)))
+        return NULL;
+#if RTLNX_VER_MIN(2,6,11)
+# if RTLNX_VER_MIN(4,12,0)
+    u.Four  = *p4d_offset(&u.Global, ulAddr);
+    if (RT_UNLIKELY(p4d_none(u.Four)))
+        return NULL;
+    if (p4d_large(u.Four))
+    {
+        pPage = p4d_page(u.Four);
+        AssertReturn(pPage, NULL);
+        pfn   = page_to_pfn(pPage);      /* doing the safe way... */
+        AssertCompile(P4D_SHIFT - PAGE_SHIFT < 31);
+        pfn  += (ulAddr >> PAGE_SHIFT) & ((UINT32_C(1) << (P4D_SHIFT - PAGE_SHIFT)) - 1);
+        return pfn_to_page(pfn);
+    }
+    u.Upper = *pud_offset(&u.Four, ulAddr);
+# else /* < 4.12 */
+    u.Upper = *pud_offset(&u.Global, ulAddr);
+# endif /* < 4.12 */
+    if (RT_UNLIKELY(pud_none(u.Upper)))
+        return NULL;
+# if RTLNX_VER_MIN(2,6,25)
+    if (pud_large(u.Upper))
+    {
+        pPage = pud_page(u.Upper);
+        AssertReturn(pPage, NULL);
+        pfn  = page_to_pfn(pPage);      /* doing the safe way... */
+        pfn += (ulAddr >> PAGE_SHIFT) & ((UINT32_C(1) << (PUD_SHIFT - PAGE_SHIFT)) - 1);
+        return pfn_to_page(pfn);
+    }
+# endif
+    u.Middle = *pmd_offset(&u.Upper, ulAddr);
+#else  /* < 2.6.11 */
+    u.Middle = *pmd_offset(&u.Global, ulAddr);
+#endif /* < 2.6.11 */
+    if (RT_UNLIKELY(pmd_none(u.Middle)))
+        return NULL;
+#if RTLNX_VER_MIN(2,6,0)
+    if (pmd_large(u.Middle))
+    {
+        pPage = pmd_page(u.Middle);
+        AssertReturn(pPage, NULL);
+        pfn  = page_to_pfn(pPage);      /* doing the safe way... */
+        pfn += (ulAddr >> PAGE_SHIFT) & ((UINT32_C(1) << (PMD_SHIFT - PAGE_SHIFT)) - 1);
+        return pfn_to_page(pfn);
+    }
+#endif
+
+#if RTLNX_VER_MIN(2,5,5) || defined(pte_offset_map) /* As usual, RHEL 3 had pte_offset_map earlier. */
+    pEntry = pte_offset_map(&u.Middle, ulAddr);
+#else
+    pEntry = pte_offset(&u.Middle, ulAddr);
+#endif
+    if (RT_UNLIKELY(!pEntry))
+        return NULL;
+    u.Entry = *pEntry;
+#if RTLNX_VER_MIN(2,5,5) || defined(pte_offset_map)
+    pte_unmap(pEntry);
+#endif
+
+    if (RT_UNLIKELY(!pte_present(u.Entry)))
+        return NULL;
+    return pte_page(u.Entry);
+}
+RT_EXPORT_SYMBOL(rtR0MemObjLinuxVirtToPage);
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocPhys(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, RTHCPHYS PhysHighest, size_t uAlignment)
+{
+    return rtR0MemObjLinuxAllocPhysSub(ppMem, RTR0MEMOBJTYPE_PHYS, cb, uAlignment, PhysHighest);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocPhysNC(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, RTHCPHYS PhysHighest)
+{
+    return rtR0MemObjLinuxAllocPhysSub(ppMem, RTR0MEMOBJTYPE_PHYS_NC, cb, PAGE_SIZE, PhysHighest);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeEnterPhys(PPRTR0MEMOBJINTERNAL ppMem, RTHCPHYS Phys, size_t cb, uint32_t uCachePolicy)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    /*
+     * All we need to do here is to validate that we can use
+     * ioremap on the specified address (32/64-bit dma_addr_t).
+     */
+    PRTR0MEMOBJLNX  pMemLnx;
+    dma_addr_t      PhysAddr = Phys;
+    AssertMsgReturn(PhysAddr == Phys, ("%#llx\n", (unsigned long long)Phys), VERR_ADDRESS_TOO_BIG);
+
+    pMemLnx = (PRTR0MEMOBJLNX)rtR0MemObjNew(sizeof(*pMemLnx), RTR0MEMOBJTYPE_PHYS, NULL, cb);
+    if (!pMemLnx)
+    {
+        IPRT_LINUX_RESTORE_EFL_AC();
+        return VERR_NO_MEMORY;
+    }
+
+    pMemLnx->Core.u.Phys.PhysBase = PhysAddr;
+    pMemLnx->Core.u.Phys.fAllocated = false;
+    pMemLnx->Core.u.Phys.uCachePolicy = uCachePolicy;
+    Assert(!pMemLnx->cPages);
+    *ppMem = &pMemLnx->Core;
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+
+/* openSUSE Leap 42.3 detection :-/ */
+#if RTLNX_VER_RANGE(4,4,0,  4,6,0) && defined(FAULT_FLAG_REMOTE)
+# define GET_USER_PAGES_API     KERNEL_VERSION(4, 10, 0) /* no typo! */
+#else
+# define GET_USER_PAGES_API     LINUX_VERSION_CODE
+#endif
+
+DECLHIDDEN(int) rtR0MemObjNativeLockUser(PPRTR0MEMOBJINTERNAL ppMem, RTR3PTR R3Ptr, size_t cb, uint32_t fAccess, RTR0PROCESS R0Process)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+    const int cPages = cb >> PAGE_SHIFT;
+    struct task_struct *pTask = rtR0ProcessToLinuxTask(R0Process);
+    struct vm_area_struct **papVMAs;
+    PRTR0MEMOBJLNX  pMemLnx;
+    int             rc      = VERR_NO_MEMORY;
+    int  const      fWrite  = fAccess & RTMEM_PROT_WRITE ? 1 : 0;
+
+    /*
+     * Check for valid task and size overflows.
+     */
+    if (!pTask)
+        return VERR_NOT_SUPPORTED;
+    if (((size_t)cPages << PAGE_SHIFT) != cb)
+        return VERR_OUT_OF_RANGE;
+
+    /*
+     * Allocate the memory object and a temporary buffer for the VMAs.
+     */
+    pMemLnx = (PRTR0MEMOBJLNX)rtR0MemObjNew(RT_UOFFSETOF_DYN(RTR0MEMOBJLNX, apPages[cPages]), RTR0MEMOBJTYPE_LOCK, (void *)R3Ptr, cb);
+    if (!pMemLnx)
+    {
+        IPRT_LINUX_RESTORE_EFL_AC();
+        return VERR_NO_MEMORY;
+    }
+
+    papVMAs = (struct vm_area_struct **)RTMemAlloc(sizeof(*papVMAs) * cPages);
+    if (papVMAs)
+    {
+        LNX_MM_DOWN_READ(pTask->mm);
+
+        /*
+         * Get user pages.
+         */
+/** @todo r=bird: Should we not force read access too? */
+#if GET_USER_PAGES_API >= KERNEL_VERSION(4, 6, 0)
+        if (R0Process == RTR0ProcHandleSelf())
+            rc = get_user_pages(R3Ptr,                  /* Where from. */
+                                cPages,                 /* How many pages. */
+# if GET_USER_PAGES_API >= KERNEL_VERSION(4, 9, 0)
+                                fWrite ? FOLL_WRITE |   /* Write to memory. */
+                                         FOLL_FORCE     /* force write access. */
+                                       : 0,             /* Write to memory. */
+# else
+                                fWrite,                 /* Write to memory. */
+                                fWrite,                 /* force write access. */
+# endif
+                                &pMemLnx->apPages[0],   /* Page array. */
+                                papVMAs);               /* vmas */
+        /*
+         * Actually this should not happen at the moment as call this function
+         * only for our own process.
+         */
+        else
+            rc = get_user_pages_remote(
+# if GET_USER_PAGES_API < KERNEL_VERSION(5, 9, 0)
+                                pTask,                  /* Task for fault accounting. */
+# endif
+                                pTask->mm,              /* Whose pages. */
+                                R3Ptr,                  /* Where from. */
+                                cPages,                 /* How many pages. */
+# if GET_USER_PAGES_API >= KERNEL_VERSION(4, 9, 0)
+                                fWrite ? FOLL_WRITE |   /* Write to memory. */
+                                         FOLL_FORCE     /* force write access. */
+                                       : 0,             /* Write to memory. */
+# else
+                                fWrite,                 /* Write to memory. */
+                                fWrite,                 /* force write access. */
+# endif
+                                &pMemLnx->apPages[0],   /* Page array. */
+                                papVMAs                 /* vmas */
+# if GET_USER_PAGES_API >= KERNEL_VERSION(4, 10, 0)
+                                , NULL                  /* locked */
+# endif
+                                );
+#else /* GET_USER_PAGES_API < KERNEL_VERSION(4, 6, 0) */
+            rc = get_user_pages(pTask,                  /* Task for fault accounting. */
+                                pTask->mm,              /* Whose pages. */
+                                R3Ptr,                  /* Where from. */
+                                cPages,                 /* How many pages. */
+/* The get_user_pages API change was back-ported to 4.4.168. */
+# if RTLNX_VER_RANGE(4,4,168,  4,5,0)
+                                fWrite ? FOLL_WRITE |   /* Write to memory. */
+                                         FOLL_FORCE     /* force write access. */
+                                       : 0,             /* Write to memory. */
+# else
+                                fWrite,                 /* Write to memory. */
+                                fWrite,                 /* force write access. */
+# endif
+                                &pMemLnx->apPages[0],   /* Page array. */
+                                papVMAs);               /* vmas */
+#endif /* GET_USER_PAGES_API < KERNEL_VERSION(4, 6, 0) */
+        if (rc == cPages)
+        {
+            /*
+             * Flush dcache (required?), protect against fork and _really_ pin the page
+             * table entries. get_user_pages() will protect against swapping out the
+             * pages but it will NOT protect against removing page table entries. This
+             * can be achieved with
+             *   - using mlock / mmap(..., MAP_LOCKED, ...) from userland. This requires
+             *     an appropriate limit set up with setrlimit(..., RLIMIT_MEMLOCK, ...).
+             *     Usual Linux distributions support only a limited size of locked pages
+             *     (e.g. 32KB).
+             *   - setting the PageReserved bit (as we do in rtR0MemObjLinuxAllocPages()
+             *     or by
+             *   - setting the VM_LOCKED flag. This is the same as doing mlock() without
+             *     a range check.
+             */
+            /** @todo The Linux fork() protection will require more work if this API
+             * is to be used for anything but locking VM pages. */
+            while (rc-- > 0)
+            {
+                flush_dcache_page(pMemLnx->apPages[rc]);
+                papVMAs[rc]->vm_flags |= VM_DONTCOPY | VM_LOCKED;
+            }
+
+            LNX_MM_UP_READ(pTask->mm);
+
+            RTMemFree(papVMAs);
+
+            pMemLnx->Core.u.Lock.R0Process = R0Process;
+            pMemLnx->cPages = cPages;
+            Assert(!pMemLnx->fMappedToRing0);
+            *ppMem = &pMemLnx->Core;
+
+            IPRT_LINUX_RESTORE_EFL_AC();
+            return VINF_SUCCESS;
+        }
+
+        /*
+         * Failed - we need to unlock any pages that we succeeded to lock.
+         */
+        while (rc-- > 0)
+        {
+            if (!PageReserved(pMemLnx->apPages[rc]))
+                SetPageDirty(pMemLnx->apPages[rc]);
+#if RTLNX_VER_MIN(4,6,0)
+            put_page(pMemLnx->apPages[rc]);
+#else
+            page_cache_release(pMemLnx->apPages[rc]);
+#endif
+        }
+
+        LNX_MM_UP_READ(pTask->mm);
+
+        RTMemFree(papVMAs);
+        rc = VERR_LOCK_FAILED;
+    }
+
+    rtR0MemObjDelete(&pMemLnx->Core);
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return rc;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeLockKernel(PPRTR0MEMOBJINTERNAL ppMem, void *pv, size_t cb, uint32_t fAccess)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+    void           *pvLast = (uint8_t *)pv + cb - 1;
+    size_t const    cPages = cb >> PAGE_SHIFT;
+    PRTR0MEMOBJLNX  pMemLnx;
+    bool            fLinearMapping;
+    int             rc;
+    uint8_t        *pbPage;
+    size_t          iPage;
+    NOREF(fAccess);
+
+    if (   !RTR0MemKernelIsValidAddr(pv)
+        || !RTR0MemKernelIsValidAddr(pv + cb))
+        return VERR_INVALID_PARAMETER;
+
+    /*
+     * The lower part of the kernel memory has a linear mapping between
+     * physical and virtual addresses. So we take a short cut here.  This is
+     * assumed to be the cleanest way to handle those addresses (and the code
+     * is well tested, though the test for determining it is not very nice).
+     * If we ever decide it isn't we can still remove it.
+     */
+#if 0
+    fLinearMapping = (unsigned long)pvLast < VMALLOC_START;
+#else
+    fLinearMapping = (unsigned long)pv     >= (unsigned long)__va(0)
+                  && (unsigned long)pvLast <  (unsigned long)high_memory;
+#endif
+
+    /*
+     * Allocate the memory object.
+     */
+    pMemLnx = (PRTR0MEMOBJLNX)rtR0MemObjNew(RT_UOFFSETOF_DYN(RTR0MEMOBJLNX, apPages[cPages]), RTR0MEMOBJTYPE_LOCK, pv, cb);
+    if (!pMemLnx)
+    {
+        IPRT_LINUX_RESTORE_EFL_AC();
+        return VERR_NO_MEMORY;
+    }
+
+    /*
+     * Gather the pages.
+     * We ASSUME all kernel pages are non-swappable and non-movable.
+     */
+    rc     = VINF_SUCCESS;
+    pbPage = (uint8_t *)pvLast;
+    iPage  = cPages;
+    if (!fLinearMapping)
+    {
+        while (iPage-- > 0)
+        {
+            struct page *pPage = rtR0MemObjLinuxVirtToPage(pbPage);
+            if (RT_UNLIKELY(!pPage))
+            {
+                rc = VERR_LOCK_FAILED;
+                break;
+            }
+            pMemLnx->apPages[iPage] = pPage;
+            pbPage -= PAGE_SIZE;
+        }
+    }
+    else
+    {
+        while (iPage-- > 0)
+        {
+            pMemLnx->apPages[iPage] = virt_to_page(pbPage);
+            pbPage -= PAGE_SIZE;
+        }
+    }
+    if (RT_SUCCESS(rc))
+    {
+        /*
+         * Complete the memory object and return.
+         */
+        pMemLnx->Core.u.Lock.R0Process = NIL_RTR0PROCESS;
+        pMemLnx->cPages = cPages;
+        Assert(!pMemLnx->fMappedToRing0);
+        *ppMem = &pMemLnx->Core;
+
+        IPRT_LINUX_RESTORE_EFL_AC();
+        return VINF_SUCCESS;
+    }
+
+    rtR0MemObjDelete(&pMemLnx->Core);
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return rc;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeReserveKernel(PPRTR0MEMOBJINTERNAL ppMem, void *pvFixed, size_t cb, size_t uAlignment)
+{
+#if RTLNX_VER_MIN(2,4,22)
+    IPRT_LINUX_SAVE_EFL_AC();
+    const size_t cPages = cb >> PAGE_SHIFT;
+    struct page *pDummyPage;
+    struct page **papPages;
+
+    /* check for unsupported stuff. */
+    AssertMsgReturn(pvFixed == (void *)-1, ("%p\n", pvFixed), VERR_NOT_SUPPORTED);
+    if (uAlignment > PAGE_SIZE)
+        return VERR_NOT_SUPPORTED;
+
+    /*
+     * Allocate a dummy page and create a page pointer array for vmap such that
+     * the dummy page is mapped all over the reserved area.
+     */
+    pDummyPage = alloc_page(GFP_HIGHUSER | __GFP_NOWARN);
+    if (pDummyPage)
+    {
+        papPages = RTMemAlloc(sizeof(*papPages) * cPages);
+        if (papPages)
+        {
+            void *pv;
+            size_t iPage = cPages;
+            while (iPage-- > 0)
+                papPages[iPage] = pDummyPage;
+# ifdef VM_MAP
+            pv = vmap(papPages, cPages, VM_MAP, PAGE_KERNEL_RO);
+# else
+            pv = vmap(papPages, cPages, VM_ALLOC, PAGE_KERNEL_RO);
+# endif
+            RTMemFree(papPages);
+            if (pv)
+            {
+                PRTR0MEMOBJLNX pMemLnx = (PRTR0MEMOBJLNX)rtR0MemObjNew(sizeof(*pMemLnx), RTR0MEMOBJTYPE_RES_VIRT, pv, cb);
+                if (pMemLnx)
+                {
+                    pMemLnx->Core.u.ResVirt.R0Process = NIL_RTR0PROCESS;
+                    pMemLnx->cPages = 1;
+                    pMemLnx->apPages[0] = pDummyPage;
+                    *ppMem = &pMemLnx->Core;
+                    IPRT_LINUX_RESTORE_EFL_AC();
+                    return VINF_SUCCESS;
+                }
+                vunmap(pv);
+            }
+        }
+        __free_page(pDummyPage);
+    }
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return VERR_NO_MEMORY;
+
+#else   /* < 2.4.22 */
+    /*
+     * Could probably use ioremap here, but the caller is in a better position than us
+     * to select some safe physical memory.
+     */
+    return VERR_NOT_SUPPORTED;
+#endif
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeReserveUser(PPRTR0MEMOBJINTERNAL ppMem, RTR3PTR R3PtrFixed, size_t cb, size_t uAlignment, RTR0PROCESS R0Process)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+    PRTR0MEMOBJLNX      pMemLnx;
+    void               *pv;
+    struct task_struct *pTask = rtR0ProcessToLinuxTask(R0Process);
+    if (!pTask)
+        return VERR_NOT_SUPPORTED;
+
+    /*
+     * Check that the specified alignment is supported.
+     */
+    if (uAlignment > PAGE_SIZE)
+        return VERR_NOT_SUPPORTED;
+
+    /*
+     * Let rtR0MemObjLinuxDoMmap do the difficult bits.
+     */
+    pv = rtR0MemObjLinuxDoMmap(R3PtrFixed, cb, uAlignment, pTask, RTMEM_PROT_NONE);
+    if (pv == (void *)-1)
+    {
+        IPRT_LINUX_RESTORE_EFL_AC();
+        return VERR_NO_MEMORY;
+    }
+
+    pMemLnx = (PRTR0MEMOBJLNX)rtR0MemObjNew(sizeof(*pMemLnx), RTR0MEMOBJTYPE_RES_VIRT, pv, cb);
+    if (!pMemLnx)
+    {
+        rtR0MemObjLinuxDoMunmap(pv, cb, pTask);
+        IPRT_LINUX_RESTORE_EFL_AC();
+        return VERR_NO_MEMORY;
+    }
+
+    pMemLnx->Core.u.ResVirt.R0Process = R0Process;
+    *ppMem = &pMemLnx->Core;
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeMapKernel(PPRTR0MEMOBJINTERNAL ppMem, RTR0MEMOBJ pMemToMap,
+                                          void *pvFixed, size_t uAlignment,
+                                          unsigned fProt, size_t offSub, size_t cbSub)
+{
+    int rc = VERR_NO_MEMORY;
+    PRTR0MEMOBJLNX pMemLnxToMap = (PRTR0MEMOBJLNX)pMemToMap;
+    PRTR0MEMOBJLNX pMemLnx;
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    /* Fail if requested to do something we can't. */
+    AssertMsgReturn(pvFixed == (void *)-1, ("%p\n", pvFixed), VERR_NOT_SUPPORTED);
+    if (uAlignment > PAGE_SIZE)
+        return VERR_NOT_SUPPORTED;
+
+    /*
+     * Create the IPRT memory object.
+     */
+    if (!cbSub)
+        cbSub = pMemLnxToMap->Core.cb - offSub;
+    pMemLnx = (PRTR0MEMOBJLNX)rtR0MemObjNew(sizeof(*pMemLnx), RTR0MEMOBJTYPE_MAPPING, NULL, cbSub);
+    if (pMemLnx)
+    {
+        if (pMemLnxToMap->cPages)
+        {
+#if RTLNX_VER_MIN(2,4,22)
+            /*
+             * Use vmap - 2.4.22 and later.
+             */
+            pgprot_t fPg = rtR0MemObjLinuxConvertProt(fProt, true /* kernel */);
+            /** @todo We don't really care too much for EXEC here... 5.8 always adds NX. */
+            Assert(((offSub + cbSub) >> PAGE_SHIFT) <= pMemLnxToMap->cPages);
+# ifdef VM_MAP
+            pMemLnx->Core.pv = vmap(&pMemLnxToMap->apPages[offSub >> PAGE_SHIFT], cbSub >> PAGE_SHIFT, VM_MAP, fPg);
+# else
+            pMemLnx->Core.pv = vmap(&pMemLnxToMap->apPages[offSub >> PAGE_SHIFT], cbSub >> PAGE_SHIFT, VM_ALLOC, fPg);
+# endif
+            if (pMemLnx->Core.pv)
+            {
+                pMemLnx->fMappedToRing0 = true;
+                rc = VINF_SUCCESS;
+            }
+            else
+                rc = VERR_MAP_FAILED;
+
+#else   /* < 2.4.22 */
+            /*
+             * Only option here is to share mappings if possible and forget about fProt.
+             */
+            if (rtR0MemObjIsRing3(pMemToMap))
+                rc = VERR_NOT_SUPPORTED;
+            else
+            {
+                rc = VINF_SUCCESS;
+                if (!pMemLnxToMap->Core.pv)
+                    rc = rtR0MemObjLinuxVMap(pMemLnxToMap, !!(fProt & RTMEM_PROT_EXEC));
+                if (RT_SUCCESS(rc))
+                {
+                    Assert(pMemLnxToMap->Core.pv);
+                    pMemLnx->Core.pv = (uint8_t *)pMemLnxToMap->Core.pv + offSub;
+                }
+            }
+#endif
+        }
+        else
+        {
+            /*
+             * MMIO / physical memory.
+             */
+            Assert(pMemLnxToMap->Core.enmType == RTR0MEMOBJTYPE_PHYS && !pMemLnxToMap->Core.u.Phys.fAllocated);
+#if RTLNX_VER_MIN(2,6,25)
+            /*
+             * ioremap() defaults to no caching since the 2.6 kernels.
+             * ioremap_nocache() has been removed finally in 5.6-rc1.
+             */
+            pMemLnx->Core.pv = pMemLnxToMap->Core.u.Phys.uCachePolicy == RTMEM_CACHE_POLICY_MMIO
+                             ? ioremap(pMemLnxToMap->Core.u.Phys.PhysBase + offSub, cbSub)
+                             : ioremap_cache(pMemLnxToMap->Core.u.Phys.PhysBase + offSub, cbSub);
+#else /* KERNEL_VERSION < 2.6.25 */
+            pMemLnx->Core.pv = pMemLnxToMap->Core.u.Phys.uCachePolicy == RTMEM_CACHE_POLICY_MMIO
+                             ? ioremap_nocache(pMemLnxToMap->Core.u.Phys.PhysBase + offSub, cbSub)
+                             : ioremap(pMemLnxToMap->Core.u.Phys.PhysBase + offSub, cbSub);
+#endif /* KERNEL_VERSION < 2.6.25 */
+            if (pMemLnx->Core.pv)
+            {
+                /** @todo fix protection. */
+                rc = VINF_SUCCESS;
+            }
+        }
+        if (RT_SUCCESS(rc))
+        {
+            pMemLnx->Core.u.Mapping.R0Process = NIL_RTR0PROCESS;
+            *ppMem = &pMemLnx->Core;
+            IPRT_LINUX_RESTORE_EFL_AC();
+            return VINF_SUCCESS;
+        }
+        rtR0MemObjDelete(&pMemLnx->Core);
+    }
+
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return rc;
+}
+
+
+#ifdef VBOX_USE_PAE_HACK
+/**
+ * Replace the PFN of a PTE with the address of the actual page.
+ *
+ * The caller maps a reserved dummy page at the address with the desired access
+ * and flags.
+ *
+ * This hack is required for older Linux kernels which don't provide
+ * remap_pfn_range().
+ *
+ * @returns 0 on success, -ENOMEM on failure.
+ * @param   mm          The memory context.
+ * @param   ulAddr      The mapping address.
+ * @param   Phys        The physical address of the page to map.
+ */
+static int rtR0MemObjLinuxFixPte(struct mm_struct *mm, unsigned long ulAddr, RTHCPHYS Phys)
+{
+    int rc = -ENOMEM;
+    pgd_t *pgd;
+
+    spin_lock(&mm->page_table_lock);
+
+    pgd = pgd_offset(mm, ulAddr);
+    if (!pgd_none(*pgd) && !pgd_bad(*pgd))
+    {
+        pmd_t *pmd = pmd_offset(pgd, ulAddr);
+        if (!pmd_none(*pmd))
+        {
+            pte_t *ptep = pte_offset_map(pmd, ulAddr);
+            if (ptep)
+            {
+                pte_t pte = *ptep;
+                pte.pte_high &= 0xfff00000;
+                pte.pte_high |= ((Phys >> 32) & 0x000fffff);
+                pte.pte_low  &= 0x00000fff;
+                pte.pte_low  |= (Phys & 0xfffff000);
+                set_pte(ptep, pte);
+                pte_unmap(ptep);
+                rc = 0;
+            }
+        }
+    }
+
+    spin_unlock(&mm->page_table_lock);
+    return rc;
+}
+#endif /* VBOX_USE_PAE_HACK */
+
+
+DECLHIDDEN(int) rtR0MemObjNativeMapUser(PPRTR0MEMOBJINTERNAL ppMem, RTR0MEMOBJ pMemToMap, RTR3PTR R3PtrFixed, size_t uAlignment,
+                                        unsigned fProt, RTR0PROCESS R0Process, size_t offSub, size_t cbSub)
+{
+    struct task_struct *pTask        = rtR0ProcessToLinuxTask(R0Process);
+    PRTR0MEMOBJLNX      pMemLnxToMap = (PRTR0MEMOBJLNX)pMemToMap;
+    int                 rc           = VERR_NO_MEMORY;
+    PRTR0MEMOBJLNX      pMemLnx;
+#ifdef VBOX_USE_PAE_HACK
+    struct page        *pDummyPage;
+    RTHCPHYS            DummyPhys;
+#endif
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    /*
+     * Check for restrictions.
+     */
+    if (!pTask)
+        return VERR_NOT_SUPPORTED;
+    if (uAlignment > PAGE_SIZE)
+        return VERR_NOT_SUPPORTED;
+
+#ifdef VBOX_USE_PAE_HACK
+    /*
+     * Allocate a dummy page for use when mapping the memory.
+     */
+    pDummyPage = alloc_page(GFP_USER | __GFP_NOWARN);
+    if (!pDummyPage)
+    {
+        IPRT_LINUX_RESTORE_EFL_AC();
+        return VERR_NO_MEMORY;
+    }
+    SetPageReserved(pDummyPage);
+    DummyPhys = page_to_phys(pDummyPage);
+#endif
+
+    /*
+     * Create the IPRT memory object.
+     */
+    Assert(!offSub || cbSub);
+    if (cbSub == 0)
+        cbSub = pMemLnxToMap->Core.cb;
+    pMemLnx = (PRTR0MEMOBJLNX)rtR0MemObjNew(sizeof(*pMemLnx), RTR0MEMOBJTYPE_MAPPING, NULL, cbSub);
+    if (pMemLnx)
+    {
+        /*
+         * Allocate user space mapping.
+         */
+        void *pv;
+        pv = rtR0MemObjLinuxDoMmap(R3PtrFixed, cbSub, uAlignment, pTask, fProt);
+        if (pv != (void *)-1)
+        {
+            /*
+             * Map page by page into the mmap area.
+             * This is generic, paranoid and not very efficient.
+             */
+            pgprot_t        fPg       = rtR0MemObjLinuxConvertProt(fProt, false /* user */);
+            unsigned long   ulAddrCur = (unsigned long)pv;
+            const size_t    cPages    = (offSub + cbSub) >> PAGE_SHIFT;
+            size_t          iPage;
+
+            LNX_MM_DOWN_WRITE(pTask->mm);
+
+            rc = VINF_SUCCESS;
+            if (pMemLnxToMap->cPages)
+            {
+                for (iPage = offSub >> PAGE_SHIFT; iPage < cPages; iPage++, ulAddrCur += PAGE_SIZE)
+                {
+#if RTLNX_VER_MAX(2,6,11)
+                    RTHCPHYS Phys = page_to_phys(pMemLnxToMap->apPages[iPage]);
+#endif
+#if RTLNX_VER_MIN(2,6,0) || defined(HAVE_26_STYLE_REMAP_PAGE_RANGE)
+                    struct vm_area_struct *vma = find_vma(pTask->mm, ulAddrCur); /* this is probably the same for all the pages... */
+                    AssertBreakStmt(vma, rc = VERR_INTERNAL_ERROR);
+#endif
+#if RTLNX_VER_MAX(2,6,0) && defined(RT_ARCH_X86)
+                    /* remap_page_range() limitation on x86 */
+                    AssertBreakStmt(Phys < _4G, rc = VERR_NO_MEMORY);
+#endif
+
+#if   defined(VBOX_USE_INSERT_PAGE) && RTLNX_VER_MIN(2,6,22)
+                    rc = vm_insert_page(vma, ulAddrCur, pMemLnxToMap->apPages[iPage]);
+                    /* Thes flags help making 100% sure some bad stuff wont happen (swap, core, ++).
+                     * See remap_pfn_range() in mm/memory.c */
+#if    RTLNX_VER_MIN(3,7,0)
+                    vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
+#else
+                    vma->vm_flags |= VM_RESERVED;
+#endif
+#elif RTLNX_VER_MIN(2,6,11)
+                    rc = remap_pfn_range(vma, ulAddrCur, page_to_pfn(pMemLnxToMap->apPages[iPage]), PAGE_SIZE, fPg);
+#elif defined(VBOX_USE_PAE_HACK)
+                    rc = remap_page_range(vma, ulAddrCur, DummyPhys, PAGE_SIZE, fPg);
+                    if (!rc)
+                        rc = rtR0MemObjLinuxFixPte(pTask->mm, ulAddrCur, Phys);
+#elif RTLNX_VER_MIN(2,6,0) || defined(HAVE_26_STYLE_REMAP_PAGE_RANGE)
+                    rc = remap_page_range(vma, ulAddrCur, Phys, PAGE_SIZE, fPg);
+#else /* 2.4 */
+                    rc = remap_page_range(ulAddrCur, Phys, PAGE_SIZE, fPg);
+#endif
+                    if (rc)
+                    {
+                        rc = VERR_NO_MEMORY;
+                        break;
+                    }
+                }
+            }
+            else
+            {
+                RTHCPHYS Phys;
+                if (pMemLnxToMap->Core.enmType == RTR0MEMOBJTYPE_PHYS)
+                    Phys = pMemLnxToMap->Core.u.Phys.PhysBase;
+                else if (pMemLnxToMap->Core.enmType == RTR0MEMOBJTYPE_CONT)
+                    Phys = pMemLnxToMap->Core.u.Cont.Phys;
+                else
+                {
+                    AssertMsgFailed(("%d\n", pMemLnxToMap->Core.enmType));
+                    Phys = NIL_RTHCPHYS;
+                }
+                if (Phys != NIL_RTHCPHYS)
+                {
+                    for (iPage = offSub >> PAGE_SHIFT; iPage < cPages; iPage++, ulAddrCur += PAGE_SIZE, Phys += PAGE_SIZE)
+                    {
+#if RTLNX_VER_MIN(2,6,0) || defined(HAVE_26_STYLE_REMAP_PAGE_RANGE)
+                        struct vm_area_struct *vma = find_vma(pTask->mm, ulAddrCur); /* this is probably the same for all the pages... */
+                        AssertBreakStmt(vma, rc = VERR_INTERNAL_ERROR);
+#endif
+#if RTLNX_VER_MAX(2,6,0) && defined(RT_ARCH_X86)
+                        /* remap_page_range() limitation on x86 */
+                        AssertBreakStmt(Phys < _4G, rc = VERR_NO_MEMORY);
+#endif
+
+#if   RTLNX_VER_MIN(2,6,11)
+                        rc = remap_pfn_range(vma, ulAddrCur, Phys, PAGE_SIZE, fPg);
+#elif defined(VBOX_USE_PAE_HACK)
+                        rc = remap_page_range(vma, ulAddrCur, DummyPhys, PAGE_SIZE, fPg);
+                        if (!rc)
+                            rc = rtR0MemObjLinuxFixPte(pTask->mm, ulAddrCur, Phys);
+#elif RTLNX_VER_MIN(2,6,0) || defined(HAVE_26_STYLE_REMAP_PAGE_RANGE)
+                        rc = remap_page_range(vma, ulAddrCur, Phys, PAGE_SIZE, fPg);
+#else /* 2.4 */
+                        rc = remap_page_range(ulAddrCur, Phys, PAGE_SIZE, fPg);
+#endif
+                        if (rc)
+                        {
+                            rc = VERR_NO_MEMORY;
+                            break;
+                        }
+                    }
+                }
+            }
+
+#ifdef CONFIG_NUMA_BALANCING
+# if RTLNX_VER_MAX(3,13,0) && RTLNX_RHEL_MAX(7,0)
+#  define VBOX_NUMA_HACK_OLD
+# endif
+            if (RT_SUCCESS(rc))
+            {
+                /** @todo Ugly hack! But right now we have no other means to
+                 *        disable automatic NUMA page balancing. */
+# ifdef RT_OS_X86
+#  ifdef VBOX_NUMA_HACK_OLD
+                pTask->mm->numa_next_reset = jiffies + 0x7fffffffUL;
+#  endif
+                pTask->mm->numa_next_scan  = jiffies + 0x7fffffffUL;
+# else
+#  ifdef VBOX_NUMA_HACK_OLD
+                pTask->mm->numa_next_reset = jiffies + 0x7fffffffffffffffUL;
+#  endif
+                pTask->mm->numa_next_scan  = jiffies + 0x7fffffffffffffffUL;
+# endif
+            }
+#endif /* CONFIG_NUMA_BALANCING */
+
+            LNX_MM_UP_WRITE(pTask->mm);
+
+            if (RT_SUCCESS(rc))
+            {
+#ifdef VBOX_USE_PAE_HACK
+                __free_page(pDummyPage);
+#endif
+                pMemLnx->Core.pv = pv;
+                pMemLnx->Core.u.Mapping.R0Process = R0Process;
+                *ppMem = &pMemLnx->Core;
+                IPRT_LINUX_RESTORE_EFL_AC();
+                return VINF_SUCCESS;
+            }
+
+            /*
+             * Bail out.
+             */
+            rtR0MemObjLinuxDoMunmap(pv, cbSub, pTask);
+        }
+        rtR0MemObjDelete(&pMemLnx->Core);
+    }
+#ifdef VBOX_USE_PAE_HACK
+    __free_page(pDummyPage);
+#endif
+
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return rc;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeProtect(PRTR0MEMOBJINTERNAL pMem, size_t offSub, size_t cbSub, uint32_t fProt)
+{
+# ifdef IPRT_USE_ALLOC_VM_AREA_FOR_EXEC
+    /*
+     * Currently only supported when we've got addresses PTEs from the kernel.
+     */
+    PRTR0MEMOBJLNX pMemLnx = (PRTR0MEMOBJLNX)pMem;
+    if (pMemLnx->pArea && pMemLnx->papPtesForArea)
+    {
+        pgprot_t const  fPg     = rtR0MemObjLinuxConvertProt(fProt, true /*fKernel*/);
+        size_t const    cPages  = (offSub + cbSub) >> PAGE_SHIFT;
+        pte_t         **papPtes = pMemLnx->papPtesForArea;
+        size_t          i;
+
+        for (i = offSub >> PAGE_SHIFT; i < cPages; i++)
+        {
+            set_pte(papPtes[i], mk_pte(pMemLnx->apPages[i], fPg));
+        }
+        preempt_disable();
+        __flush_tlb_all();
+        preempt_enable();
+        return VINF_SUCCESS;
+    }
+# elif defined(IPRT_USE_APPLY_TO_PAGE_RANGE_FOR_EXEC)
+    PRTR0MEMOBJLNX pMemLnx = (PRTR0MEMOBJLNX)pMem;
+    if (   pMemLnx->fExecutable
+        && pMemLnx->fMappedToRing0)
+    {
+        LNXAPPLYPGRANGE Args;
+        Args.pMemLnx = pMemLnx;
+        Args.fPg = rtR0MemObjLinuxConvertProt(fProt, true /*fKernel*/);
+        int rcLnx = apply_to_page_range(current->active_mm, (unsigned long)pMemLnx->Core.pv + offSub, cbSub,
+                                        rtR0MemObjLinuxApplyPageRange, (void *)&Args);
+        if (rcLnx)
+            return VERR_NOT_SUPPORTED;
+
+        return VINF_SUCCESS;
+    }
+# endif
+
+    NOREF(pMem);
+    NOREF(offSub);
+    NOREF(cbSub);
+    NOREF(fProt);
+    return VERR_NOT_SUPPORTED;
+}
+
+
+DECLHIDDEN(RTHCPHYS) rtR0MemObjNativeGetPagePhysAddr(PRTR0MEMOBJINTERNAL pMem, size_t iPage)
+{
+    PRTR0MEMOBJLNX  pMemLnx = (PRTR0MEMOBJLNX)pMem;
+
+    if (pMemLnx->cPages)
+        return page_to_phys(pMemLnx->apPages[iPage]);
+
+    switch (pMemLnx->Core.enmType)
+    {
+        case RTR0MEMOBJTYPE_CONT:
+            return pMemLnx->Core.u.Cont.Phys     + (iPage << PAGE_SHIFT);
+
+        case RTR0MEMOBJTYPE_PHYS:
+            return pMemLnx->Core.u.Phys.PhysBase + (iPage << PAGE_SHIFT);
+
+            /* the parent knows */
+        case RTR0MEMOBJTYPE_MAPPING:
+            return rtR0MemObjNativeGetPagePhysAddr(pMemLnx->Core.uRel.Child.pParent, iPage);
+
+            /* cPages > 0 */
+        case RTR0MEMOBJTYPE_LOW:
+        case RTR0MEMOBJTYPE_LOCK:
+        case RTR0MEMOBJTYPE_PHYS_NC:
+        case RTR0MEMOBJTYPE_PAGE:
+        default:
+            AssertMsgFailed(("%d\n", pMemLnx->Core.enmType));
+            /* fall thru */
+
+        case RTR0MEMOBJTYPE_RES_VIRT:
+            return NIL_RTHCPHYS;
+    }
+}
+
diff --git a/src/VBox/Runtime/r0drv/linux/memuserkernel-r0drv-linux.c b/src/VBox/Runtime/r0drv/linux/memuserkernel-r0drv-linux.c
new file mode 100644
index 00000000..f23bd091
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/memuserkernel-r0drv-linux.c
@@ -0,0 +1,181 @@
+/* $Id: memuserkernel-r0drv-linux.c $ */
+/** @file
+ * IPRT - User & Kernel Memory, Ring-0 Driver, Linux.
+ */
+
+/*
+ * Copyright (C) 2009-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-linux-kernel.h"
+#include "internal/iprt.h"
+
+#include <iprt/mem.h>
+#include <iprt/errcore.h>
+
+
+RTR0DECL(int) RTR0MemUserCopyFrom(void *pvDst, RTR3PTR R3PtrSrc, size_t cb)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+    if (RT_LIKELY(copy_from_user(pvDst, (void *)R3PtrSrc, cb) == 0))
+    {
+        IPRT_LINUX_RESTORE_EFL_AC();
+        return VINF_SUCCESS;
+    }
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return VERR_ACCESS_DENIED;
+}
+RT_EXPORT_SYMBOL(RTR0MemUserCopyFrom);
+
+
+RTR0DECL(int) RTR0MemUserCopyTo(RTR3PTR R3PtrDst, void const *pvSrc, size_t cb)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+    if (RT_LIKELY(copy_to_user((void *)R3PtrDst, pvSrc, cb) == 0))
+    {
+        IPRT_LINUX_RESTORE_EFL_AC();
+        return VINF_SUCCESS;
+    }
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return VERR_ACCESS_DENIED;
+}
+RT_EXPORT_SYMBOL(RTR0MemUserCopyTo);
+
+
+RTR0DECL(bool) RTR0MemUserIsValidAddr(RTR3PTR R3Ptr)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+#if RTLNX_VER_MIN(5,0,0) || RTLNX_RHEL_MIN(8,1)
+    bool fRc = access_ok((void *)R3Ptr, 1);
+#else
+    bool fRc = access_ok(VERIFY_READ, (void *)R3Ptr, 1);
+#endif
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return fRc;
+}
+RT_EXPORT_SYMBOL(RTR0MemUserIsValidAddr);
+
+
+RTR0DECL(bool) RTR0MemKernelIsValidAddr(void *pv)
+{
+    /* Couldn't find a straight forward way of doing this... */
+#if defined(RT_ARCH_X86) && defined(CONFIG_X86_HIGH_ENTRY)
+    return true; /* ?? */
+#elif defined(RT_ARCH_X86) || defined(RT_ARCH_AMD64)
+    return (uintptr_t)pv >= PAGE_OFFSET;
+#else
+# error "PORT ME"
+#if RTLNX_VER_MIN(5,0,0) || RTLNX_RHEL_MIN(8,1)
+    return !access_ok(pv, 1);
+#else
+    return !access_ok(VERIFY_READ, pv, 1);
+#endif
+#endif
+}
+RT_EXPORT_SYMBOL(RTR0MemKernelIsValidAddr);
+
+
+RTR0DECL(bool) RTR0MemAreKrnlAndUsrDifferent(void)
+{
+#if defined(RT_ARCH_X86) && defined(CONFIG_X86_HIGH_ENTRY) /* ?? */
+    return false;
+#else
+    return true;
+#endif
+}
+RT_EXPORT_SYMBOL(RTR0MemAreKrnlAndUsrDifferent);
+
+
+/**
+ * Treats both source and destination as unsafe buffers.
+ */
+static int rtR0MemKernelCopyLnxWorker(void *pvDst, void const *pvSrc, size_t cb)
+{
+#if RTLNX_VER_MIN(2,5,55)
+/* _ASM_EXTABLE was introduced in 2.6.25 from what I can tell. Using #ifndef
+   here since it has to be a macro and you never know what someone might have
+   backported to an earlier kernel release. */
+# ifndef _ASM_EXTABLE
+#  if ARCH_BITS == 32
+#   define _ASM_EXTABLE(a_Instr, a_Resume) \
+    ".section __ex_table,\"a\"\n" \
+    ".balign 4\n" \
+    ".long   " #a_Instr "\n" \
+    ".long   " #a_Resume "\n" \
+    ".previous\n"
+#  else
+#   define _ASM_EXTABLE(a_Instr, a_Resume) \
+    ".section __ex_table,\"a\"\n" \
+    ".balign 8\n" \
+    ".quad   " #a_Instr "\n" \
+    ".quad   " #a_Resume "\n" \
+    ".previous\n"
+#  endif
+# endif /* !_ASM_EXTABLE */
+    int rc;
+    IPRT_LINUX_SAVE_EFL_AC(); /* paranoia */
+    if (!cb)
+        return VINF_SUCCESS;
+
+    __asm__ __volatile__ ("cld\n"
+                          "1:\n\t"
+                          "rep; movsb\n"
+                          "2:\n\t"
+                          ".section .fixup,\"ax\"\n"
+                          "3:\n\t"
+                          "movl %4, %0\n\t"
+                          "jmp 2b\n\t"
+                          ".previous\n"
+                          _ASM_EXTABLE(1b, 3b)
+                          : "=r" (rc),
+                            "=D" (pvDst),
+                            "=S" (pvSrc),
+                            "=c" (cb)
+                          : "i" (VERR_ACCESS_DENIED),
+                            "0" (VINF_SUCCESS),
+                            "1" (pvDst),
+                            "2" (pvSrc),
+                            "3" (cb)
+                          : "memory");
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return rc;
+#else
+    return VERR_NOT_SUPPORTED;
+#endif
+}
+
+
+RTR0DECL(int) RTR0MemKernelCopyFrom(void *pvDst, void const *pvSrc, size_t cb)
+{
+    return rtR0MemKernelCopyLnxWorker(pvDst, pvSrc, cb);
+}
+RT_EXPORT_SYMBOL(RTR0MemKernelCopyFrom);
+
+
+RTR0DECL(int) RTR0MemKernelCopyTo(void *pvDst, void const *pvSrc, size_t cb)
+{
+    return rtR0MemKernelCopyLnxWorker(pvDst, pvSrc, cb);
+}
+RT_EXPORT_SYMBOL(RTR0MemKernelCopyTo);
+
diff --git a/src/VBox/Runtime/r0drv/linux/mp-r0drv-linux.c b/src/VBox/Runtime/r0drv/linux/mp-r0drv-linux.c
new file mode 100644
index 00000000..d76fa314
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/mp-r0drv-linux.c
@@ -0,0 +1,630 @@
+/* $Id: mp-r0drv-linux.c $ */
+/** @file
+ * IPRT - Multiprocessor, Ring-0 Driver, Linux.
+ */
+
+/*
+ * Copyright (C) 2008-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-linux-kernel.h"
+#include "internal/iprt.h"
+
+#include <iprt/mp.h>
+#include <iprt/cpuset.h>
+#include <iprt/err.h>
+#include <iprt/asm.h>
+#include <iprt/thread.h>
+#include "r0drv/mp-r0drv.h"
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+#if defined(nr_cpumask_bits) || RTLNX_VER_MIN(2,6,28)
+# define VBOX_NR_CPUMASK_BITS   (nr_cpumask_bits)   /* same as nr_cpu_ids */
+#else
+# define VBOX_NR_CPUMASK_BITS   (NR_CPUS)
+#endif
+
+
+RTDECL(RTCPUID) RTMpCpuId(void)
+{
+    return smp_processor_id();
+}
+RT_EXPORT_SYMBOL(RTMpCpuId);
+
+
+RTDECL(int) RTMpCurSetIndex(void)
+{
+    return smp_processor_id();
+}
+RT_EXPORT_SYMBOL(RTMpCurSetIndex);
+
+
+RTDECL(int) RTMpCurSetIndexAndId(PRTCPUID pidCpu)
+{
+    return *pidCpu = smp_processor_id();
+}
+RT_EXPORT_SYMBOL(RTMpCurSetIndexAndId);
+
+
+RTDECL(int) RTMpCpuIdToSetIndex(RTCPUID idCpu)
+{
+    return idCpu < RTCPUSET_MAX_CPUS && idCpu < VBOX_NR_CPUMASK_BITS ? (int)idCpu : -1;
+}
+RT_EXPORT_SYMBOL(RTMpCpuIdToSetIndex);
+
+
+RTDECL(RTCPUID) RTMpCpuIdFromSetIndex(int iCpu)
+{
+    return (unsigned)iCpu < VBOX_NR_CPUMASK_BITS ? (RTCPUID)iCpu : NIL_RTCPUID;
+}
+RT_EXPORT_SYMBOL(RTMpCpuIdFromSetIndex);
+
+
+RTDECL(RTCPUID) RTMpGetMaxCpuId(void)
+{
+    return VBOX_NR_CPUMASK_BITS - 1;
+}
+RT_EXPORT_SYMBOL(RTMpGetMaxCpuId);
+
+
+RTDECL(bool) RTMpIsCpuPossible(RTCPUID idCpu)
+{
+#if defined(CONFIG_SMP)
+# if RTLNX_VER_MIN(2,6,2) || defined(cpu_possible)
+    return idCpu < VBOX_NR_CPUMASK_BITS && cpu_possible(idCpu);
+# else /* < 2.5.29 */
+    return idCpu < (RTCPUID)(smp_num_cpus);
+# endif
+#else
+    return idCpu == RTMpCpuId();
+#endif
+}
+RT_EXPORT_SYMBOL(RTMpIsCpuPossible);
+
+
+RTDECL(PRTCPUSET) RTMpGetSet(PRTCPUSET pSet)
+{
+    RTCPUID idCpu;
+
+    RTCpuSetEmpty(pSet);
+    idCpu = RTMpGetMaxCpuId();
+    do
+    {
+        if (RTMpIsCpuPossible(idCpu))
+            RTCpuSetAdd(pSet, idCpu);
+    } while (idCpu-- > 0);
+    return pSet;
+}
+RT_EXPORT_SYMBOL(RTMpGetSet);
+
+
+RTDECL(RTCPUID) RTMpGetCount(void)
+{
+#ifdef CONFIG_SMP
+# if RTLNX_VER_MIN(2,6,4) || defined(num_possible_cpus)
+    return num_possible_cpus();
+# elif RTLNX_VER_MAX(2,5,0)
+    return smp_num_cpus;
+# else
+    RTCPUSET Set;
+    RTMpGetSet(&Set);
+    return RTCpuSetCount(&Set);
+# endif
+#else
+    return 1;
+#endif
+}
+RT_EXPORT_SYMBOL(RTMpGetCount);
+
+
+RTDECL(bool) RTMpIsCpuOnline(RTCPUID idCpu)
+{
+#ifdef CONFIG_SMP
+# if RTLNX_VER_MIN(2,6,0) || defined(cpu_online)
+    return idCpu < VBOX_NR_CPUMASK_BITS && cpu_online(idCpu);
+# else /* 2.4: */
+    return idCpu < VBOX_NR_CPUMASK_BITS && cpu_online_map & RT_BIT_64(idCpu);
+# endif
+#else
+    return idCpu == RTMpCpuId();
+#endif
+}
+RT_EXPORT_SYMBOL(RTMpIsCpuOnline);
+
+
+RTDECL(PRTCPUSET) RTMpGetOnlineSet(PRTCPUSET pSet)
+{
+#ifdef CONFIG_SMP
+    RTCPUID idCpu;
+
+    RTCpuSetEmpty(pSet);
+    idCpu = RTMpGetMaxCpuId();
+    do
+    {
+        if (RTMpIsCpuOnline(idCpu))
+            RTCpuSetAdd(pSet, idCpu);
+    } while (idCpu-- > 0);
+#else
+    RTCpuSetEmpty(pSet);
+    RTCpuSetAdd(pSet, RTMpCpuId());
+#endif
+    return pSet;
+}
+RT_EXPORT_SYMBOL(RTMpGetOnlineSet);
+
+
+RTDECL(RTCPUID) RTMpGetOnlineCount(void)
+{
+#ifdef CONFIG_SMP
+# if RTLNX_VER_MIN(2,6,0) || defined(num_online_cpus)
+    return num_online_cpus();
+# else
+    RTCPUSET Set;
+    RTMpGetOnlineSet(&Set);
+    return RTCpuSetCount(&Set);
+# endif
+#else
+    return 1;
+#endif
+}
+RT_EXPORT_SYMBOL(RTMpGetOnlineCount);
+
+
+RTDECL(bool) RTMpIsCpuWorkPending(void)
+{
+    /** @todo (not used on non-Windows platforms yet). */
+    return false;
+}
+RT_EXPORT_SYMBOL(RTMpIsCpuWorkPending);
+
+
+/**
+ * Wrapper between the native linux per-cpu callbacks and PFNRTWORKER.
+ *
+ * @param   pvInfo      Pointer to the RTMPARGS package.
+ */
+static void rtmpLinuxWrapper(void *pvInfo)
+{
+    PRTMPARGS pArgs = (PRTMPARGS)pvInfo;
+    ASMAtomicIncU32(&pArgs->cHits);
+    pArgs->pfnWorker(RTMpCpuId(), pArgs->pvUser1, pArgs->pvUser2);
+}
+
+#ifdef CONFIG_SMP
+
+# if RTLNX_VER_MIN(2,6,27)
+/**
+ * Wrapper between the native linux per-cpu callbacks and PFNRTWORKER, does hit
+ * increment after calling the worker.
+ *
+ * @param   pvInfo      Pointer to the RTMPARGS package.
+ */
+static void rtmpLinuxWrapperPostInc(void *pvInfo)
+{
+    PRTMPARGS pArgs = (PRTMPARGS)pvInfo;
+    pArgs->pfnWorker(RTMpCpuId(), pArgs->pvUser1, pArgs->pvUser2);
+    ASMAtomicIncU32(&pArgs->cHits);
+}
+# endif
+
+
+/**
+ * Wrapper between the native linux all-cpu callbacks and PFNRTWORKER.
+ *
+ * @param   pvInfo      Pointer to the RTMPARGS package.
+ */
+static void rtmpLinuxAllWrapper(void *pvInfo)
+{
+    PRTMPARGS  pArgs      = (PRTMPARGS)pvInfo;
+    PRTCPUSET  pWorkerSet = pArgs->pWorkerSet;
+    RTCPUID    idCpu      = RTMpCpuId();
+    Assert(!RTThreadPreemptIsEnabled(NIL_RTTHREAD));
+
+    if (RTCpuSetIsMember(pWorkerSet, idCpu))
+    {
+        pArgs->pfnWorker(idCpu, pArgs->pvUser1, pArgs->pvUser2);
+        RTCpuSetDel(pWorkerSet, idCpu);
+    }
+}
+
+#endif /* CONFIG_SMP */
+
+RTDECL(int) RTMpOnAll(PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+    RTMPARGS Args;
+    RTCPUSET OnlineSet;
+    RTCPUID  idCpu;
+#ifdef CONFIG_SMP
+    uint32_t cLoops;
+#endif
+
+    RTTHREADPREEMPTSTATE PreemptState = RTTHREADPREEMPTSTATE_INITIALIZER;
+
+    Args.pfnWorker  = pfnWorker;
+    Args.pvUser1    = pvUser1;
+    Args.pvUser2    = pvUser2;
+    Args.idCpu      = NIL_RTCPUID;
+    Args.cHits      = 0;
+
+    RTThreadPreemptDisable(&PreemptState);
+    RTMpGetOnlineSet(&OnlineSet);
+    Args.pWorkerSet = &OnlineSet;
+    idCpu = RTMpCpuId();
+
+#ifdef CONFIG_SMP
+    if (RTCpuSetCount(&OnlineSet) > 1)
+    {
+        /* Fire the function on all other CPUs without waiting for completion. */
+# if RTLNX_VER_MIN(5,3,0)
+        smp_call_function(rtmpLinuxAllWrapper, &Args, 0 /* wait */);
+# elif RTLNX_VER_MIN(2,6,27)
+        int rc = smp_call_function(rtmpLinuxAllWrapper, &Args, 0 /* wait */);
+        Assert(!rc); NOREF(rc);
+# else
+        int rc = smp_call_function(rtmpLinuxAllWrapper, &Args, 0 /* retry */, 0 /* wait */);
+        Assert(!rc); NOREF(rc);
+# endif
+    }
+#endif
+
+    /* Fire the function on this CPU. */
+    Args.pfnWorker(idCpu, Args.pvUser1, Args.pvUser2);
+    RTCpuSetDel(Args.pWorkerSet, idCpu);
+
+#ifdef CONFIG_SMP
+    /* Wait for all of them finish. */
+    cLoops = 64000;
+    while (!RTCpuSetIsEmpty(Args.pWorkerSet))
+    {
+        /* Periodically check if any CPU in the wait set has gone offline, if so update the wait set. */
+        if (!cLoops--)
+        {
+            RTCPUSET OnlineSetNow;
+            RTMpGetOnlineSet(&OnlineSetNow);
+            RTCpuSetAnd(Args.pWorkerSet, &OnlineSetNow);
+
+            cLoops = 64000;
+        }
+
+        ASMNopPause();
+    }
+#endif
+
+    RTThreadPreemptRestore(&PreemptState);
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTMpOnAll);
+
+
+RTDECL(int) RTMpOnOthers(PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+#ifdef CONFIG_SMP
+    IPRT_LINUX_SAVE_EFL_AC();
+    RTMPARGS Args;
+
+    RTTHREADPREEMPTSTATE PreemptState = RTTHREADPREEMPTSTATE_INITIALIZER;
+    Args.pfnWorker = pfnWorker;
+    Args.pvUser1 = pvUser1;
+    Args.pvUser2 = pvUser2;
+    Args.idCpu = NIL_RTCPUID;
+    Args.cHits = 0;
+
+    RTThreadPreemptDisable(&PreemptState);
+# if RTLNX_VER_MIN(5,3,0)
+    smp_call_function(rtmpLinuxWrapper, &Args, 1 /* wait */);
+# elif RTLNX_VER_MIN(2,6,27)
+    int rc = smp_call_function(rtmpLinuxWrapper, &Args, 1 /* wait */);
+    Assert(rc == 0); NOREF(rc);
+# else /* older kernels */
+    int rc = smp_call_function(rtmpLinuxWrapper, &Args, 0 /* retry */, 1 /* wait */);
+    Assert(rc == 0); NOREF(rc);
+# endif /* older kernels */
+    RTThreadPreemptRestore(&PreemptState);
+
+    IPRT_LINUX_RESTORE_EFL_AC();
+#else
+    RT_NOREF(pfnWorker, pvUser1, pvUser2);
+#endif
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTMpOnOthers);
+
+
+#if RTLNX_VER_MAX(2,6,27) && defined(CONFIG_SMP)
+/**
+ * Wrapper between the native linux per-cpu callbacks and PFNRTWORKER
+ * employed by RTMpOnPair on older kernels that lacks smp_call_function_many.
+ *
+ * @param   pvInfo      Pointer to the RTMPARGS package.
+ */
+static void rtMpLinuxOnPairWrapper(void *pvInfo)
+{
+    PRTMPARGS pArgs = (PRTMPARGS)pvInfo;
+    RTCPUID   idCpu = RTMpCpuId();
+
+    if (   idCpu == pArgs->idCpu
+        || idCpu == pArgs->idCpu2)
+    {
+        pArgs->pfnWorker(idCpu, pArgs->pvUser1, pArgs->pvUser2);
+        ASMAtomicIncU32(&pArgs->cHits);
+    }
+}
+#endif
+
+
+RTDECL(int) RTMpOnPair(RTCPUID idCpu1, RTCPUID idCpu2, uint32_t fFlags, PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+#ifdef CONFIG_SMP
+    IPRT_LINUX_SAVE_EFL_AC();
+    int                     rc;
+    RTTHREADPREEMPTSTATE    PreemptState = RTTHREADPREEMPTSTATE_INITIALIZER;
+# if RTLNX_VER_MIN(2,6,28) /* 2.6.28 introduces CONFIG_CPUMASK_OFFSTACK */
+    cpumask_var_t           DstCpuMask;
+# elif RTLNX_VER_MIN(2,6,27)
+    cpumask_t               DstCpuMask;
+# endif
+
+    AssertReturn(idCpu1 != idCpu2, VERR_INVALID_PARAMETER);
+    AssertReturn(!(fFlags & RTMPON_F_VALID_MASK), VERR_INVALID_FLAGS);
+
+    /*
+     * Prepare the CPU mask before we disable preemption.
+     */
+# if RTLNX_VER_MIN(2,6,30)
+    if (!zalloc_cpumask_var(&DstCpuMask, GFP_KERNEL))
+        return VERR_NO_MEMORY;
+    cpumask_set_cpu(idCpu1, DstCpuMask);
+    cpumask_set_cpu(idCpu2, DstCpuMask);
+# elif RTLNX_VER_MIN(2,6,28)
+    if (!alloc_cpumask_var(&DstCpuMask, GFP_KERNEL))
+        return VERR_NO_MEMORY;
+    cpumask_clear(DstCpuMask);
+    cpumask_set_cpu(idCpu1, DstCpuMask);
+    cpumask_set_cpu(idCpu2, DstCpuMask);
+# elif RTLNX_VER_MIN(2,6,27)
+    cpus_clear(DstCpuMask);
+    cpu_set(idCpu1, DstCpuMask);
+    cpu_set(idCpu2, DstCpuMask);
+# endif
+
+    /*
+     * Check that both CPUs are online before doing the broadcast call.
+     */
+    RTThreadPreemptDisable(&PreemptState);
+    if (   RTMpIsCpuOnline(idCpu1)
+        && RTMpIsCpuOnline(idCpu2))
+    {
+        /*
+         * Use the smp_call_function variant taking a cpu mask where available,
+         * falling back on broadcast with filter.  Slight snag if one of the
+         * CPUs is the one we're running on, we must do the call and the post
+         * call wait ourselves.
+         */
+        RTCPUID     idCpuSelf = RTMpCpuId();
+        bool const  fCallSelf = idCpuSelf == idCpu1 || idCpuSelf == idCpu2;
+        RTMPARGS    Args;
+        Args.pfnWorker = pfnWorker;
+        Args.pvUser1 = pvUser1;
+        Args.pvUser2 = pvUser2;
+        Args.idCpu   = idCpu1;
+        Args.idCpu2  = idCpu2;
+        Args.cHits   = 0;
+
+# if RTLNX_VER_MIN(2,6,28)
+        smp_call_function_many(DstCpuMask, rtmpLinuxWrapperPostInc, &Args, !fCallSelf /* wait */);
+        rc = 0;
+# elif RTLNX_VER_MIN(2,6,27)
+        rc = smp_call_function_mask(DstCpuMask, rtmpLinuxWrapperPostInc, &Args, !fCallSelf /* wait */);
+# else /* older kernels */
+        rc = smp_call_function(rtMpLinuxOnPairWrapper, &Args, 0 /* retry */, !fCallSelf /* wait */);
+# endif /* older kernels */
+        Assert(rc == 0);
+
+        /* Call ourselves if necessary and wait for the other party to be done. */
+        if (fCallSelf)
+        {
+            uint32_t cLoops = 0;
+            rtmpLinuxWrapper(&Args);
+            while (ASMAtomicReadU32(&Args.cHits) < 2)
+            {
+                if ((cLoops & 0x1ff) == 0 && !RTMpIsCpuOnline(idCpuSelf == idCpu1 ? idCpu2 : idCpu1))
+                    break;
+                cLoops++;
+                ASMNopPause();
+            }
+        }
+
+        Assert(Args.cHits <= 2);
+        if (Args.cHits == 2)
+            rc = VINF_SUCCESS;
+        else if (Args.cHits == 1)
+            rc = VERR_NOT_ALL_CPUS_SHOWED;
+        else if (Args.cHits == 0)
+            rc = VERR_CPU_OFFLINE;
+        else
+            rc = VERR_CPU_IPE_1;
+    }
+    /*
+     * A CPU must be present to be considered just offline.
+     */
+    else if (   RTMpIsCpuPresent(idCpu1)
+             && RTMpIsCpuPresent(idCpu2))
+        rc = VERR_CPU_OFFLINE;
+    else
+        rc = VERR_CPU_NOT_FOUND;
+
+    RTThreadPreemptRestore(&PreemptState);;
+# if RTLNX_VER_MIN(2,6,28)
+    free_cpumask_var(DstCpuMask);
+# endif
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return rc;
+
+#else /* !CONFIG_SMP */
+    RT_NOREF(idCpu1, idCpu2, fFlags, pfnWorker, pvUser1, pvUser2);
+    return VERR_CPU_NOT_FOUND;
+#endif /* !CONFIG_SMP */
+}
+RT_EXPORT_SYMBOL(RTMpOnPair);
+
+
+RTDECL(bool) RTMpOnPairIsConcurrentExecSupported(void)
+{
+    return true;
+}
+RT_EXPORT_SYMBOL(RTMpOnPairIsConcurrentExecSupported);
+
+
+#if RTLNX_VER_MAX(2,6,19) && defined(CONFIG_SMP)
+/**
+ * Wrapper between the native linux per-cpu callbacks and PFNRTWORKER
+ * employed by RTMpOnSpecific on older kernels that lacks smp_call_function_single.
+ *
+ * @param   pvInfo      Pointer to the RTMPARGS package.
+ */
+static void rtmpOnSpecificLinuxWrapper(void *pvInfo)
+{
+    PRTMPARGS pArgs = (PRTMPARGS)pvInfo;
+    RTCPUID idCpu = RTMpCpuId();
+
+    if (idCpu == pArgs->idCpu)
+    {
+        pArgs->pfnWorker(idCpu, pArgs->pvUser1, pArgs->pvUser2);
+        ASMAtomicIncU32(&pArgs->cHits);
+    }
+}
+#endif
+
+
+RTDECL(int) RTMpOnSpecific(RTCPUID idCpu, PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+    int rc;
+    RTMPARGS Args;
+
+    RTTHREADPREEMPTSTATE PreemptState = RTTHREADPREEMPTSTATE_INITIALIZER;
+    Args.pfnWorker = pfnWorker;
+    Args.pvUser1 = pvUser1;
+    Args.pvUser2 = pvUser2;
+    Args.idCpu = idCpu;
+    Args.cHits = 0;
+
+    if (!RTMpIsCpuPossible(idCpu))
+        return VERR_CPU_NOT_FOUND;
+
+    RTThreadPreemptDisable(&PreemptState);
+    if (idCpu != RTMpCpuId())
+    {
+#ifdef CONFIG_SMP
+        if (RTMpIsCpuOnline(idCpu))
+        {
+# if RTLNX_VER_MIN(2,6,27)
+            rc = smp_call_function_single(idCpu, rtmpLinuxWrapper, &Args, 1 /* wait */);
+# elif RTLNX_VER_MIN(2,6,19)
+            rc = smp_call_function_single(idCpu, rtmpLinuxWrapper, &Args, 0 /* retry */, 1 /* wait */);
+# else /* older kernels */
+            rc = smp_call_function(rtmpOnSpecificLinuxWrapper, &Args, 0 /* retry */, 1 /* wait */);
+# endif /* older kernels */
+            Assert(rc == 0);
+            rc = Args.cHits ? VINF_SUCCESS : VERR_CPU_OFFLINE;
+        }
+        else
+#endif /* CONFIG_SMP */
+            rc = VERR_CPU_OFFLINE;
+    }
+    else
+    {
+        rtmpLinuxWrapper(&Args);
+        rc = VINF_SUCCESS;
+    }
+    RTThreadPreemptRestore(&PreemptState);;
+
+    NOREF(rc);
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return rc;
+}
+RT_EXPORT_SYMBOL(RTMpOnSpecific);
+
+
+#if RTLNX_VER_MIN(2,6,19) && defined(CONFIG_SMP)
+/**
+ * Dummy callback used by RTMpPokeCpu.
+ *
+ * @param   pvInfo      Ignored.
+ */
+static void rtmpLinuxPokeCpuCallback(void *pvInfo)
+{
+    NOREF(pvInfo);
+}
+#endif
+
+
+RTDECL(int) RTMpPokeCpu(RTCPUID idCpu)
+{
+#if RTLNX_VER_MIN(2,6,19)
+    IPRT_LINUX_SAVE_EFL_AC();
+    int rc;
+    if (RTMpIsCpuPossible(idCpu))
+    {
+        if (RTMpIsCpuOnline(idCpu))
+        {
+# ifdef CONFIG_SMP
+#  if RTLNX_VER_MIN(2,6,27)
+            rc = smp_call_function_single(idCpu, rtmpLinuxPokeCpuCallback, NULL, 0 /* wait */);
+#  elif RTLNX_VER_MIN(2,6,19)
+            rc = smp_call_function_single(idCpu, rtmpLinuxPokeCpuCallback, NULL, 0 /* retry */, 0 /* wait */);
+#  else  /* older kernels */
+#   error oops
+#  endif /* older kernels */
+            Assert(rc == 0);
+# endif /* CONFIG_SMP */
+            rc = VINF_SUCCESS;
+        }
+        else
+            rc = VERR_CPU_OFFLINE;
+    }
+    else
+        rc = VERR_CPU_NOT_FOUND;
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return rc;
+
+#else  /* older kernels */
+    /* no unicast here? */
+    return VERR_NOT_SUPPORTED;
+#endif /* older kernels */
+}
+RT_EXPORT_SYMBOL(RTMpPokeCpu);
+
+
+RTDECL(bool) RTMpOnAllIsConcurrentSafe(void)
+{
+    return true;
+}
+RT_EXPORT_SYMBOL(RTMpOnAllIsConcurrentSafe);
+
diff --git a/src/VBox/Runtime/r0drv/linux/mpnotification-r0drv-linux.c b/src/VBox/Runtime/r0drv/linux/mpnotification-r0drv-linux.c
new file mode 100644
index 00000000..9b649b85
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/mpnotification-r0drv-linux.c
@@ -0,0 +1,248 @@
+/* $Id: mpnotification-r0drv-linux.c $ */
+/** @file
+ * IPRT - Multiprocessor Event Notifications, Ring-0 Driver, Linux.
+ */
+
+/*
+ * Copyright (C) 2008-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-linux-kernel.h"
+#include "internal/iprt.h"
+
+#include <iprt/asm-amd64-x86.h>
+#include <iprt/errcore.h>
+#include <iprt/cpuset.h>
+#include <iprt/thread.h>
+#include "r0drv/mp-r0drv.h"
+
+#if RTLNX_VER_MIN(4,10,0)
+
+static enum cpuhp_state g_rtR0MpOnline;
+
+/*
+ * Linux 4.10 completely removed CPU notifiers. So let's switch to CPU hotplug
+ * notification.
+ */
+
+static int rtR0MpNotificationLinuxOnline(unsigned int cpu)
+{
+    RTCPUID idCpu = RTMpCpuIdFromSetIndex(cpu);
+    rtMpNotificationDoCallbacks(RTMPEVENT_ONLINE, idCpu);
+    return 0;
+}
+
+static int rtR0MpNotificationLinuxOffline(unsigned int cpu)
+{
+    RTCPUID idCpu = RTMpCpuIdFromSetIndex(cpu);
+    rtMpNotificationDoCallbacks(RTMPEVENT_OFFLINE, idCpu);
+    return 0;
+}
+
+DECLHIDDEN(int) rtR0MpNotificationNativeInit(void)
+{
+    int rc;
+    IPRT_LINUX_SAVE_EFL_AC();
+    rc = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "vboxdrv:online",
+                                   rtR0MpNotificationLinuxOnline, rtR0MpNotificationLinuxOffline);
+    IPRT_LINUX_RESTORE_EFL_AC();
+    /*
+     * cpuhp_setup_state_nocalls() returns a positive state number for
+     * CPUHP_AP_ONLINE_DYN or -ENOSPC if there is no free slot available
+     * (see cpuhp_reserve_state / definition of CPUHP_AP_ONLINE_DYN).
+     */
+    AssertMsgReturn(rc > 0, ("%d\n", rc), RTErrConvertFromErrno(rc));
+    g_rtR0MpOnline = rc;
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(void) rtR0MpNotificationNativeTerm(void)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+    cpuhp_remove_state_nocalls(g_rtR0MpOnline);
+    IPRT_LINUX_RESTORE_EFL_AC();
+}
+
+#elif RTLNX_VER_MIN(2,5,71) && defined(CONFIG_SMP)
+
+static int rtMpNotificationLinuxCallback(struct notifier_block *pNotifierBlock, unsigned long ulNativeEvent, void *pvCpu);
+
+/**
+ * The notifier block we use for registering the callback.
+ */
+static struct notifier_block g_NotifierBlock =
+{
+    .notifier_call = rtMpNotificationLinuxCallback,
+    .next = NULL,
+    .priority = 0
+};
+
+# ifdef CPU_DOWN_FAILED
+/**
+ * The set of CPUs we've seen going offline recently.
+ */
+static RTCPUSET g_MpPendingOfflineSet;
+# endif
+
+
+/**
+ * The native callback.
+ *
+ * @returns NOTIFY_DONE.
+ * @param   pNotifierBlock  Pointer to g_NotifierBlock.
+ * @param   ulNativeEvent   The native event.
+ * @param   pvCpu           The cpu id cast into a pointer value.
+ *
+ * @remarks This can fire with preemption enabled and on any CPU.
+ */
+static int rtMpNotificationLinuxCallback(struct notifier_block *pNotifierBlock, unsigned long ulNativeEvent, void *pvCpu)
+{
+    bool fProcessEvent = false;
+    RTCPUID idCpu      = (uintptr_t)pvCpu;
+    NOREF(pNotifierBlock);
+
+    /*
+     * Note that redhat/CentOS ported _some_ of the FROZEN macros
+     * back to their 2.6.18-92.1.10.el5 kernel but actually don't
+     * use them. Thus we have to test for both CPU_TASKS_FROZEN and
+     * the individual event variants.
+     */
+    switch (ulNativeEvent)
+    {
+        /*
+         * Pick up online events or failures to go offline.
+         * Ignore failure events for CPUs we didn't see go offline.
+         */
+# ifdef CPU_DOWN_FAILED
+        case CPU_DOWN_FAILED:
+#  if defined(CPU_TASKS_FROZEN) && defined(CPU_DOWN_FAILED_FROZEN)
+        case CPU_DOWN_FAILED_FROZEN:
+#  endif
+            if (!RTCpuSetIsMember(&g_MpPendingOfflineSet, idCpu))
+                break;      /* fProcessEvents = false */
+        /* fall thru */
+# endif
+        case CPU_ONLINE:
+# if defined(CPU_TASKS_FROZEN) && defined(CPU_ONLINE_FROZEN)
+        case CPU_ONLINE_FROZEN:
+# endif
+# ifdef CPU_DOWN_FAILED
+            RTCpuSetDel(&g_MpPendingOfflineSet, idCpu);
+# endif
+            fProcessEvent = true;
+            break;
+
+        /*
+         * Pick the earliest possible offline event.
+         * The only important thing here is that we get the event and that
+         * it's exactly one.
+         */
+# ifdef CPU_DOWN_PREPARE
+        case CPU_DOWN_PREPARE:
+#  if defined(CPU_TASKS_FROZEN) && defined(CPU_DOWN_PREPARE_FROZEN)
+        case CPU_DOWN_PREPARE_FROZEN:
+#  endif
+            fProcessEvent = true;
+# else
+        case CPU_DEAD:
+#  if defined(CPU_TASKS_FROZEN) && defined(CPU_DEAD_FROZEN)
+        case CPU_DEAD_FROZEN:
+#  endif
+            /* Don't process CPU_DEAD notifications. */
+# endif
+# ifdef CPU_DOWN_FAILED
+            RTCpuSetAdd(&g_MpPendingOfflineSet, idCpu);
+# endif
+            break;
+    }
+
+    if (!fProcessEvent)
+        return NOTIFY_DONE;
+
+    switch (ulNativeEvent)
+    {
+# ifdef CPU_DOWN_FAILED
+        case CPU_DOWN_FAILED:
+#  if defined(CPU_TASKS_FROZEN) && defined(CPU_DOWN_FAILED_FROZEN)
+        case CPU_DOWN_FAILED_FROZEN:
+#  endif
+# endif
+        case CPU_ONLINE:
+# if defined(CPU_TASKS_FROZEN) && defined(CPU_ONLINE_FROZEN)
+        case CPU_ONLINE_FROZEN:
+# endif
+            rtMpNotificationDoCallbacks(RTMPEVENT_ONLINE, idCpu);
+            break;
+
+# ifdef CPU_DOWN_PREPARE
+        case CPU_DOWN_PREPARE:
+#  if defined(CPU_TASKS_FROZEN) && defined(CPU_DOWN_PREPARE_FROZEN)
+        case CPU_DOWN_PREPARE_FROZEN:
+#  endif
+            rtMpNotificationDoCallbacks(RTMPEVENT_OFFLINE, idCpu);
+            break;
+# endif
+    }
+
+    return NOTIFY_DONE;
+}
+
+
+DECLHIDDEN(int) rtR0MpNotificationNativeInit(void)
+{
+    int rc;
+    IPRT_LINUX_SAVE_EFL_AC();
+
+# ifdef CPU_DOWN_FAILED
+    RTCpuSetEmpty(&g_MpPendingOfflineSet);
+# endif
+
+    rc = register_cpu_notifier(&g_NotifierBlock);
+    IPRT_LINUX_RESTORE_EFL_AC();
+    AssertMsgReturn(!rc, ("%d\n", rc), RTErrConvertFromErrno(rc));
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(void) rtR0MpNotificationNativeTerm(void)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+    unregister_cpu_notifier(&g_NotifierBlock);
+    IPRT_LINUX_RESTORE_EFL_AC();
+}
+
+#else   /* Not supported / Not needed */
+
+DECLHIDDEN(int) rtR0MpNotificationNativeInit(void)
+{
+    return VINF_SUCCESS;
+}
+
+DECLHIDDEN(void) rtR0MpNotificationNativeTerm(void)
+{
+}
+
+#endif  /* Not supported / Not needed */
+
diff --git a/src/VBox/Runtime/r0drv/linux/process-r0drv-linux.c b/src/VBox/Runtime/r0drv/linux/process-r0drv-linux.c
new file mode 100644
index 00000000..9c2bcd93
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/process-r0drv-linux.c
@@ -0,0 +1,49 @@
+/* $Id: process-r0drv-linux.c $ */
+/** @file
+ * IPRT - Process, Ring-0 Driver, Linux.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-linux-kernel.h"
+#include "internal/iprt.h"
+
+#include <iprt/process.h>
+
+
+RTDECL(RTPROCESS) RTProcSelf(void)
+{
+    return (RTPROCESS)current->tgid;
+}
+RT_EXPORT_SYMBOL(RTProcSelf);
+
+
+RTR0DECL(RTR0PROCESS) RTR0ProcHandleSelf(void)
+{
+    return (RTR0PROCESS)current->tgid;
+}
+RT_EXPORT_SYMBOL(RTR0ProcHandleSelf);
+
diff --git a/src/VBox/Runtime/r0drv/linux/rtStrFormatKernelAddress-r0drv-linux.c b/src/VBox/Runtime/r0drv/linux/rtStrFormatKernelAddress-r0drv-linux.c
new file mode 100644
index 00000000..b9839e64
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/rtStrFormatKernelAddress-r0drv-linux.c
@@ -0,0 +1,56 @@
+/* $Id: rtStrFormatKernelAddress-r0drv-linux.c $ */
+/** @file
+ * IPRT - IPRT String Formatter, ring-0 addresses.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define LOG_GROUP RTLOGGROUP_STRING
+#include "the-linux-kernel.h"
+#include "internal/iprt.h"
+
+#include <iprt/assert.h>
+#include <iprt/string.h>
+
+#include "internal/string.h"
+
+
+DECLHIDDEN(size_t) rtStrFormatKernelAddress(char *pszBuf, size_t cbBuf, RTR0INTPTR uPtr, signed int cchWidth,
+                                            signed int cchPrecision, unsigned int fFlags)
+{
+#if !defined(DEBUG) && RTLNX_VER_MIN(2,6,38)
+    RT_NOREF(cchWidth, cchPrecision);
+    /* use the Linux kernel function which is able to handle "%pK" */
+    static const char s_szFmt[] = "0x%pK";
+    const char *pszFmt = s_szFmt;
+    if (!(fFlags & RTSTR_F_SPECIAL))
+        pszFmt += 2;
+    return scnprintf(pszBuf, cbBuf, pszFmt, uPtr);
+#else
+    Assert(cbBuf >= 64);
+    return RTStrFormatNumber(pszBuf, uPtr, 16, cchWidth, cchPrecision, fFlags);
+#endif
+}
diff --git a/src/VBox/Runtime/r0drv/linux/semevent-r0drv-linux.c b/src/VBox/Runtime/r0drv/linux/semevent-r0drv-linux.c
new file mode 100644
index 00000000..1ccc9eae
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/semevent-r0drv-linux.c
@@ -0,0 +1,279 @@
+/* $Id: semevent-r0drv-linux.c $ */
+/** @file
+ * IPRT - Single Release Event Semaphores, Ring-0 Driver, Linux.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTSEMEVENT_WITHOUT_REMAPPING
+#include "the-linux-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/semaphore.h>
+
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/lockvalidator.h>
+#include <iprt/mem.h>
+
+#include "waitqueue-r0drv-linux.h"
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Linux event semaphore.
+ */
+typedef struct RTSEMEVENTINTERNAL
+{
+    /** Magic value (RTSEMEVENT_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** The object status - !0 when signaled and 0 when reset. */
+    uint32_t volatile   fState;
+    /** Reference counter. */
+    uint32_t volatile   cRefs;
+    /** The wait queue. */
+    wait_queue_head_t   Head;
+} RTSEMEVENTINTERNAL, *PRTSEMEVENTINTERNAL;
+
+
+
+RTDECL(int)  RTSemEventCreate(PRTSEMEVENT phEventSem)
+{
+    return RTSemEventCreateEx(phEventSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, NULL);
+}
+
+
+RTDECL(int)  RTSemEventCreateEx(PRTSEMEVENT phEventSem, uint32_t fFlags, RTLOCKVALCLASS hClass, const char *pszNameFmt, ...)
+{
+    PRTSEMEVENTINTERNAL pThis;
+    IPRT_LINUX_SAVE_EFL_AC();
+    RT_NOREF_PV(hClass); RT_NOREF_PV(pszNameFmt);
+
+    AssertReturn(!(fFlags & ~(RTSEMEVENT_FLAGS_NO_LOCK_VAL | RTSEMEVENT_FLAGS_BOOTSTRAP_HACK)), VERR_INVALID_PARAMETER);
+    Assert(!(fFlags & RTSEMEVENT_FLAGS_BOOTSTRAP_HACK) || (fFlags & RTSEMEVENT_FLAGS_NO_LOCK_VAL));
+
+    pThis = (PRTSEMEVENTINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (!pThis)
+        return VERR_NO_MEMORY;
+
+    pThis->u32Magic = RTSEMEVENT_MAGIC;
+    pThis->fState   = 0;
+    pThis->cRefs    = 1;
+    init_waitqueue_head(&pThis->Head);
+
+    *phEventSem = pThis;
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTSemEventCreate);
+
+
+/**
+ * Retains a reference to the event semaphore.
+ *
+ * @param   pThis       The event semaphore.
+ */
+DECLINLINE(void) rtR0SemEventLnxRetain(PRTSEMEVENTINTERNAL pThis)
+{
+    uint32_t cRefs = ASMAtomicIncU32(&pThis->cRefs);
+    Assert(cRefs < 100000); NOREF(cRefs);
+}
+
+
+/**
+ * Releases a reference to the event semaphore.
+ *
+ * @param   pThis       The event semaphore.
+ */
+DECLINLINE(void) rtR0SemEventLnxRelease(PRTSEMEVENTINTERNAL pThis)
+{
+    if (RT_UNLIKELY(ASMAtomicDecU32(&pThis->cRefs) == 0))
+        RTMemFree(pThis);
+}
+
+
+RTDECL(int)  RTSemEventDestroy(RTSEMEVENT hEventSem)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTINTERNAL pThis = hEventSem;
+    if (pThis == NIL_RTSEMEVENT)
+        return VINF_SUCCESS;
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("pThis->u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+    Assert(pThis->cRefs > 0);
+
+    /*
+     * Invalidate it and signal the object just in case.
+     */
+    ASMAtomicWriteU32(&pThis->u32Magic, ~RTSEMEVENT_MAGIC);
+    ASMAtomicWriteU32(&pThis->fState, 0);
+    Assert(!waitqueue_active(&pThis->Head));
+    wake_up_all(&pThis->Head);
+    rtR0SemEventLnxRelease(pThis);
+
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTSemEventDestroy);
+
+
+RTDECL(int)  RTSemEventSignal(RTSEMEVENT hEventSem)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTINTERNAL pThis = (PRTSEMEVENTINTERNAL)hEventSem;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("pThis->u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+    rtR0SemEventLnxRetain(pThis);
+
+    /*
+     * Signal the event object.
+     */
+    ASMAtomicWriteU32(&pThis->fState, 1);
+    wake_up(&pThis->Head);
+
+    rtR0SemEventLnxRelease(pThis);
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTSemEventSignal);
+
+
+/**
+ * Worker for RTSemEventWaitEx and RTSemEventWaitExDebug.
+ *
+ * @returns VBox status code.
+ * @param   pThis           The event semaphore.
+ * @param   fFlags          See RTSemEventWaitEx.
+ * @param   uTimeout        See RTSemEventWaitEx.
+ * @param   pSrcPos         The source code position of the wait.
+ */
+static int rtR0SemEventLnxWait(PRTSEMEVENTINTERNAL pThis, uint32_t fFlags, uint64_t uTimeout,
+                               PCRTLOCKVALSRCPOS pSrcPos)
+{
+    int rc;
+    RT_NOREF_PV(pSrcPos);
+
+    /*
+     * Validate the input.
+     */
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    AssertReturn(RTSEMWAIT_FLAGS_ARE_VALID(fFlags), VERR_INVALID_PARAMETER);
+    rtR0SemEventLnxRetain(pThis);
+
+    /*
+     * Try grab the event without setting up the wait.
+     */
+    if (   1 /** @todo check if there are someone waiting already - waitqueue_active, but then what do we do below? */
+        && ASMAtomicCmpXchgU32(&pThis->fState, 0, 1))
+        rc = VINF_SUCCESS;
+    else
+    {
+        /*
+         * We have to wait.
+         */
+        IPRT_LINUX_SAVE_EFL_AC();
+        RTR0SEMLNXWAIT Wait;
+        rc = rtR0SemLnxWaitInit(&Wait, fFlags, uTimeout, &pThis->Head);
+        if (RT_SUCCESS(rc))
+        {
+            IPRT_DEBUG_SEMS_STATE(pThis, 'E');
+            for (;;)
+            {
+                /* The destruction test. */
+                if (RT_UNLIKELY(pThis->u32Magic != RTSEMEVENT_MAGIC))
+                    rc = VERR_SEM_DESTROYED;
+                else
+                {
+                    rtR0SemLnxWaitPrepare(&Wait);
+
+                    /* Check the exit conditions. */
+                    if (RT_UNLIKELY(pThis->u32Magic != RTSEMEVENT_MAGIC))
+                        rc = VERR_SEM_DESTROYED;
+                    else if (ASMAtomicCmpXchgU32(&pThis->fState, 0, 1))
+                        rc = VINF_SUCCESS;
+                    else if (rtR0SemLnxWaitHasTimedOut(&Wait))
+                        rc = VERR_TIMEOUT;
+                    else if (rtR0SemLnxWaitWasInterrupted(&Wait))
+                        rc = VERR_INTERRUPTED;
+                    else
+                    {
+                        /* Do the wait and then recheck the conditions. */
+                        rtR0SemLnxWaitDoIt(&Wait);
+                        continue;
+                    }
+                }
+                break;
+            }
+
+            rtR0SemLnxWaitDelete(&Wait);
+            IPRT_DEBUG_SEMS_STATE_RC(pThis, 'E', rc);
+        }
+        IPRT_LINUX_RESTORE_EFL_AC();
+    }
+
+    rtR0SemEventLnxRelease(pThis);
+    return rc;
+}
+
+
+RTDECL(int)  RTSemEventWaitEx(RTSEMEVENT hEventSem, uint32_t fFlags, uint64_t uTimeout)
+{
+#ifndef RTSEMEVENT_STRICT
+    return rtR0SemEventLnxWait(hEventSem, fFlags, uTimeout, NULL);
+#else
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
+    return rtR0SemEventLnxWait(hEventSem, fFlags, uTimeout, &SrcPos);
+#endif
+}
+RT_EXPORT_SYMBOL(RTSemEventWaitEx);
+
+
+RTDECL(int)  RTSemEventWaitExDebug(RTSEMEVENT hEventSem, uint32_t fFlags, uint64_t uTimeout,
+                                   RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
+    return rtR0SemEventLnxWait(hEventSem, fFlags, uTimeout, &SrcPos);
+}
+RT_EXPORT_SYMBOL(RTSemEventWaitExDebug);
+
+
+RTDECL(uint32_t) RTSemEventGetResolution(void)
+{
+    return rtR0SemLnxWaitGetResolution();
+}
+RT_EXPORT_SYMBOL(RTSemEventGetResolution);
+
diff --git a/src/VBox/Runtime/r0drv/linux/semeventmulti-r0drv-linux.c b/src/VBox/Runtime/r0drv/linux/semeventmulti-r0drv-linux.c
new file mode 100644
index 00000000..78ff6572
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/semeventmulti-r0drv-linux.c
@@ -0,0 +1,344 @@
+/* $Id: semeventmulti-r0drv-linux.c $ */
+/** @file
+ * IPRT - Multiple Release Event Semaphores, Ring-0 Driver, Linux.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTSEMEVENTMULTI_WITHOUT_REMAPPING
+#include "the-linux-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/semaphore.h>
+
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+#include <iprt/err.h>
+#include <iprt/mem.h>
+#include <iprt/lockvalidator.h>
+
+#include "waitqueue-r0drv-linux.h"
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+/** @name fStateAndGen values
+ * @{ */
+/** The state bit number. */
+#define RTSEMEVENTMULTILNX_STATE_BIT        0
+/** The state mask. */
+#define RTSEMEVENTMULTILNX_STATE_MASK       RT_BIT_32(RTSEMEVENTMULTILNX_STATE_BIT)
+/** The generation mask. */
+#define RTSEMEVENTMULTILNX_GEN_MASK         ~RTSEMEVENTMULTILNX_STATE_MASK
+/** The generation shift. */
+#define RTSEMEVENTMULTILNX_GEN_SHIFT        1
+/** The initial variable value. */
+#define RTSEMEVENTMULTILNX_STATE_GEN_INIT   UINT32_C(0xfffffffc)
+/** @}  */
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Linux event semaphore.
+ */
+typedef struct RTSEMEVENTMULTIINTERNAL
+{
+    /** Magic value (RTSEMEVENTMULTI_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** The object state bit and generation counter.
+     * The generation counter is incremented every time the object is
+     * signalled. */
+    uint32_t volatile   fStateAndGen;
+    /** Reference counter. */
+    uint32_t volatile   cRefs;
+    /** The wait queue. */
+    wait_queue_head_t   Head;
+} RTSEMEVENTMULTIINTERNAL, *PRTSEMEVENTMULTIINTERNAL;
+
+
+
+
+
+RTDECL(int)  RTSemEventMultiCreate(PRTSEMEVENTMULTI phEventMultiSem)
+{
+    return RTSemEventMultiCreateEx(phEventMultiSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, NULL);
+}
+
+
+RTDECL(int)  RTSemEventMultiCreateEx(PRTSEMEVENTMULTI phEventMultiSem, uint32_t fFlags, RTLOCKVALCLASS hClass,
+                                     const char *pszNameFmt, ...)
+{
+    PRTSEMEVENTMULTIINTERNAL pThis;
+    IPRT_LINUX_SAVE_EFL_AC();
+    RT_NOREF_PV(hClass); RT_NOREF_PV(pszNameFmt);
+
+    AssertReturn(!(fFlags & ~RTSEMEVENTMULTI_FLAGS_NO_LOCK_VAL), VERR_INVALID_PARAMETER);
+    pThis = (PRTSEMEVENTMULTIINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (pThis)
+    {
+        pThis->u32Magic     = RTSEMEVENTMULTI_MAGIC;
+        pThis->fStateAndGen = RTSEMEVENTMULTILNX_STATE_GEN_INIT;
+        pThis->cRefs        = 1;
+        init_waitqueue_head(&pThis->Head);
+
+        *phEventMultiSem = pThis;
+        IPRT_LINUX_RESTORE_EFL_AC();
+        return VINF_SUCCESS;
+    }
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return VERR_NO_MEMORY;
+}
+RT_EXPORT_SYMBOL(RTSemEventMultiCreate);
+
+
+/**
+ * Retain a reference to the semaphore.
+ *
+ * @param   pThis       The semaphore.
+ */
+DECLINLINE(void) rtR0SemEventMultiLnxRetain(PRTSEMEVENTMULTIINTERNAL pThis)
+{
+    uint32_t cRefs = ASMAtomicIncU32(&pThis->cRefs);
+    NOREF(cRefs);
+    Assert(cRefs && cRefs < 100000);
+}
+
+
+/**
+ * Release a reference, destroy the thing if necessary.
+ *
+ * @param   pThis       The semaphore.
+ */
+DECLINLINE(void) rtR0SemEventMultiLnxRelease(PRTSEMEVENTMULTIINTERNAL pThis)
+{
+    if (RT_UNLIKELY(ASMAtomicDecU32(&pThis->cRefs) == 0))
+    {
+        Assert(pThis->u32Magic != RTSEMEVENTMULTI_MAGIC);
+        RTMemFree(pThis);
+    }
+}
+
+
+RTDECL(int) RTSemEventMultiDestroy(RTSEMEVENTMULTI hEventMultiSem)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    if (pThis == NIL_RTSEMEVENTMULTI)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    Assert(pThis->cRefs > 0);
+
+    /*
+     * Invalidate it and signal the object just in case.
+     */
+    ASMAtomicWriteU32(&pThis->u32Magic, ~RTSEMEVENTMULTI_MAGIC);
+    ASMAtomicAndU32(&pThis->fStateAndGen, RTSEMEVENTMULTILNX_GEN_MASK);
+    Assert(!waitqueue_active(&pThis->Head));
+    wake_up_all(&pThis->Head);
+    rtR0SemEventMultiLnxRelease(pThis);
+
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTSemEventMultiDestroy);
+
+
+RTDECL(int) RTSemEventMultiSignal(RTSEMEVENTMULTI hEventMultiSem)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+    uint32_t fNew;
+    uint32_t fOld;
+
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    if (!pThis)
+        return VERR_INVALID_PARAMETER;
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    rtR0SemEventMultiLnxRetain(pThis);
+
+    /*
+     * Signal the event object.  The cause of the paranoia here is racing to try
+     * deal with racing RTSemEventMultiSignal calls (should probably be
+     * forbidden, but it's relatively easy to handle).
+     */
+    do
+    {
+        fNew = fOld = ASMAtomicUoReadU32(&pThis->fStateAndGen);
+        fNew += 1 << RTSEMEVENTMULTILNX_GEN_SHIFT;
+        fNew |= RTSEMEVENTMULTILNX_STATE_MASK;
+    }
+    while (!ASMAtomicCmpXchgU32(&pThis->fStateAndGen, fNew, fOld));
+
+    wake_up_all(&pThis->Head);
+
+    rtR0SemEventMultiLnxRelease(pThis);
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTSemEventMultiSignal);
+
+
+RTDECL(int) RTSemEventMultiReset(RTSEMEVENTMULTI hEventMultiSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    if (!pThis)
+        return VERR_INVALID_PARAMETER;
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    rtR0SemEventMultiLnxRetain(pThis);
+
+    /*
+     * Reset it.
+     */
+    ASMAtomicAndU32(&pThis->fStateAndGen, ~RTSEMEVENTMULTILNX_STATE_MASK);
+
+    rtR0SemEventMultiLnxRelease(pThis);
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTSemEventMultiReset);
+
+
+/**
+ * Worker for RTSemEventMultiWaitEx and RTSemEventMultiWaitExDebug.
+ *
+ * @returns VBox status code.
+ * @param   pThis           The event semaphore.
+ * @param   fFlags          See RTSemEventMultiWaitEx.
+ * @param   uTimeout        See RTSemEventMultiWaitEx.
+ * @param   pSrcPos         The source code position of the wait.
+ */
+static int rtR0SemEventMultiLnxWait(PRTSEMEVENTMULTIINTERNAL pThis, uint32_t fFlags, uint64_t uTimeout,
+                                    PCRTLOCKVALSRCPOS pSrcPos)
+{
+    uint32_t    fOrgStateAndGen;
+    int         rc;
+    RT_NOREF_PV(pSrcPos);
+
+    /*
+     * Validate the input.
+     */
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    AssertReturn(RTSEMWAIT_FLAGS_ARE_VALID(fFlags), VERR_INVALID_PARAMETER);
+    rtR0SemEventMultiLnxRetain(pThis);
+
+    /*
+     * Is the event already signalled or do we have to wait?
+     */
+    fOrgStateAndGen = ASMAtomicUoReadU32(&pThis->fStateAndGen);
+    if (fOrgStateAndGen & RTSEMEVENTMULTILNX_STATE_MASK)
+        rc = VINF_SUCCESS;
+    else
+    {
+        /*
+         * We have to wait.
+         */
+        RTR0SEMLNXWAIT Wait;
+        IPRT_LINUX_SAVE_EFL_AC();
+        rc = rtR0SemLnxWaitInit(&Wait, fFlags, uTimeout, &pThis->Head);
+        if (RT_SUCCESS(rc))
+        {
+            IPRT_DEBUG_SEMS_STATE(pThis, 'E');
+            for (;;)
+            {
+                /* The destruction test. */
+                if (RT_UNLIKELY(pThis->u32Magic != RTSEMEVENTMULTI_MAGIC))
+                    rc = VERR_SEM_DESTROYED;
+                else
+                {
+                    rtR0SemLnxWaitPrepare(&Wait);
+
+                    /* Check the exit conditions. */
+                    if (RT_UNLIKELY(pThis->u32Magic != RTSEMEVENTMULTI_MAGIC))
+                        rc = VERR_SEM_DESTROYED;
+                    else if (ASMAtomicUoReadU32(&pThis->fStateAndGen) != fOrgStateAndGen)
+                        rc = VINF_SUCCESS;
+                    else if (rtR0SemLnxWaitHasTimedOut(&Wait))
+                        rc = VERR_TIMEOUT;
+                    else if (rtR0SemLnxWaitWasInterrupted(&Wait))
+                        rc = VERR_INTERRUPTED;
+                    else
+                    {
+                        /* Do the wait and then recheck the conditions. */
+                        rtR0SemLnxWaitDoIt(&Wait);
+                        continue;
+                    }
+                }
+                break;
+            }
+
+            rtR0SemLnxWaitDelete(&Wait);
+            IPRT_DEBUG_SEMS_STATE_RC(pThis, 'E', rc);
+        }
+        IPRT_LINUX_RESTORE_EFL_AC();
+    }
+
+    rtR0SemEventMultiLnxRelease(pThis);
+    return rc;
+}
+
+
+RTDECL(int)  RTSemEventMultiWaitEx(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout)
+{
+#ifndef RTSEMEVENT_STRICT
+    return rtR0SemEventMultiLnxWait(hEventMultiSem, fFlags, uTimeout, NULL);
+#else
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
+    return rtR0SemEventMultiLnxWait(hEventMultiSem, fFlags, uTimeout, &SrcPos);
+#endif
+}
+RT_EXPORT_SYMBOL(RTSemEventMultiWaitEx);
+
+
+RTDECL(int)  RTSemEventMultiWaitExDebug(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout,
+                                        RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
+    return rtR0SemEventMultiLnxWait(hEventMultiSem, fFlags, uTimeout, &SrcPos);
+}
+RT_EXPORT_SYMBOL(RTSemEventMultiWaitExDebug);
+
+
+RTDECL(uint32_t) RTSemEventMultiGetResolution(void)
+{
+    return rtR0SemLnxWaitGetResolution();
+}
+RT_EXPORT_SYMBOL(RTSemEventMultiGetResolution);
+
diff --git a/src/VBox/Runtime/r0drv/linux/semfastmutex-r0drv-linux.c b/src/VBox/Runtime/r0drv/linux/semfastmutex-r0drv-linux.c
new file mode 100644
index 00000000..affcbe15
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/semfastmutex-r0drv-linux.c
@@ -0,0 +1,157 @@
+/* $Id: semfastmutex-r0drv-linux.c $ */
+/** @file
+ * IPRT - Fast Mutex Semaphores, Ring-0 Driver, Linux.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-linux-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/semaphore.h>
+#include <iprt/alloc.h>
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+#include <iprt/errcore.h>
+#if defined(RT_STRICT) || defined(IPRT_DEBUG_SEMS)
+# include <iprt/thread.h>
+#endif
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Wrapper for the linux semaphore structure.
+ */
+typedef struct RTSEMFASTMUTEXINTERNAL
+{
+    /** Magic value (RTSEMFASTMUTEX_MAGIC). */
+    uint32_t            u32Magic;
+    /** the linux semaphore. */
+    struct semaphore    Semaphore;
+#if defined(RT_STRICT) || defined(IPRT_DEBUG_SEMS)
+    /** For check. */
+    RTNATIVETHREAD volatile Owner;
+#endif
+} RTSEMFASTMUTEXINTERNAL, *PRTSEMFASTMUTEXINTERNAL;
+
+
+RTDECL(int)  RTSemFastMutexCreate(PRTSEMFASTMUTEX phFastMtx)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    /*
+     * Allocate.
+     */
+    PRTSEMFASTMUTEXINTERNAL pThis;
+    pThis = (PRTSEMFASTMUTEXINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (!pThis)
+        return VERR_NO_MEMORY;
+
+    /*
+     * Initialize.
+     */
+    pThis->u32Magic = RTSEMFASTMUTEX_MAGIC;
+    sema_init(&pThis->Semaphore, 1);
+#if defined(RT_STRICT) || defined(IPRT_DEBUG_SEMS)
+    pThis->Owner = NIL_RTNATIVETHREAD;
+#endif
+
+    *phFastMtx = pThis;
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTSemFastMutexCreate);
+
+
+RTDECL(int)  RTSemFastMutexDestroy(RTSEMFASTMUTEX hFastMtx)
+{
+    /*
+     * Validate.
+     */
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    if (pThis == NIL_RTSEMFASTMUTEX)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+
+    ASMAtomicWriteU32(&pThis->u32Magic, RTSEMFASTMUTEX_MAGIC_DEAD);
+    RTMemFree(pThis);
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTSemFastMutexDestroy);
+
+
+RTDECL(int)  RTSemFastMutexRequest(RTSEMFASTMUTEX hFastMtx)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    /*
+     * Validate.
+     */
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+
+    IPRT_DEBUG_SEMS_STATE(pThis, 'd');
+    down(&pThis->Semaphore);
+#if defined(RT_STRICT) || defined(IPRT_DEBUG_SEMS)
+    IPRT_DEBUG_SEMS_STATE(pThis, 'o');
+    AssertRelease(pThis->Owner == NIL_RTNATIVETHREAD);
+    ASMAtomicUoWriteSize(&pThis->Owner, RTThreadNativeSelf());
+#endif
+
+    IPRT_LINUX_RESTORE_EFL_ONLY_AC();
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTSemFastMutexRequest);
+
+
+RTDECL(int)  RTSemFastMutexRelease(RTSEMFASTMUTEX hFastMtx)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    /*
+     * Validate.
+     */
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+
+#if defined(RT_STRICT) || defined(IPRT_DEBUG_SEMS)
+    AssertRelease(pThis->Owner == RTThreadNativeSelf());
+    ASMAtomicUoWriteSize(&pThis->Owner, NIL_RTNATIVETHREAD);
+#endif
+    up(&pThis->Semaphore);
+    IPRT_DEBUG_SEMS_STATE(pThis, 'u');
+
+    IPRT_LINUX_RESTORE_EFL_ONLY_AC();
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTSemFastMutexRelease);
+
diff --git a/src/VBox/Runtime/r0drv/linux/semmutex-r0drv-linux.c b/src/VBox/Runtime/r0drv/linux/semmutex-r0drv-linux.c
new file mode 100644
index 00000000..8f14778a
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/semmutex-r0drv-linux.c
@@ -0,0 +1,421 @@
+/* $Id: semmutex-r0drv-linux.c $ */
+/** @file
+ * IPRT - Mutex Semaphores, Ring-0 Driver, Linux.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTSEMMUTEX_WITHOUT_REMAPPING
+#include "the-linux-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/semaphore.h>
+
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+#include <iprt/mem.h>
+#include <iprt/err.h>
+#include <iprt/list.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+typedef struct RTSEMMUTEXLNXWAITER
+{
+    /** The list entry. */
+    RTLISTNODE                  ListEntry;
+    /** The waiting task. */
+    struct task_struct         *pTask;
+    /** Why did we wake up? */
+    enum
+    {
+        /** Wakeup to take the semaphore. */
+        RTSEMMUTEXLNXWAITER_WAKEUP,
+        /** Mutex is being destroyed. */
+        RTSEMMUTEXLNXWAITER_DESTROYED,
+        /** Some other reason. */
+        RTSEMMUTEXLNXWAITER_OTHER
+    } volatile                  enmReason;
+} RTSEMMUTEXLNXWAITER, *PRTSEMMUTEXLNXWAITER;
+
+/**
+ * Wrapper for the linux semaphore structure.
+ */
+typedef struct RTSEMMUTEXINTERNAL
+{
+    /** Magic value (RTSEMMUTEX_MAGIC). */
+    uint32_t                    u32Magic;
+    /** The number of recursions. */
+    uint32_t                    cRecursions;
+    /** The list of waiting threads. */
+    RTLISTANCHOR                WaiterList;
+    /** The current owner, NULL if none. */
+    struct task_struct         *pOwnerTask;
+    /** The number of references to this piece of memory.  This is used to
+     *  prevent it from being kicked from underneath us while waiting. */
+    uint32_t volatile           cRefs;
+    /** The spinlock protecting the members and falling asleep. */
+    spinlock_t                  Spinlock;
+} RTSEMMUTEXINTERNAL, *PRTSEMMUTEXINTERNAL;
+
+
+RTDECL(int) RTSemMutexCreate(PRTSEMMUTEX phMtx)
+{
+    int rc = VINF_SUCCESS;
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    /*
+     * Allocate.
+     */
+    PRTSEMMUTEXINTERNAL pThis;
+    pThis = (PRTSEMMUTEXINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (pThis)
+    {
+        /*
+         * Initialize.
+         */
+        pThis->u32Magic     = RTSEMMUTEX_MAGIC;
+        pThis->cRecursions  = 0;
+        pThis->pOwnerTask   = NULL;
+        pThis->cRefs        = 1;
+        RTListInit(&pThis->WaiterList);
+        spin_lock_init(&pThis->Spinlock);
+
+        *phMtx = pThis;
+    }
+    else
+        rc = VERR_NO_MEMORY;
+
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return rc;
+}
+RT_EXPORT_SYMBOL(RTSemMutexCreate);
+
+
+RTDECL(int) RTSemMutexDestroy(RTSEMMUTEX hMtx)
+{
+    PRTSEMMUTEXINTERNAL     pThis = hMtx;
+    PRTSEMMUTEXLNXWAITER    pCur;
+    unsigned long           fSavedIrq;
+
+    /*
+     * Validate.
+     */
+    if (pThis == NIL_RTSEMMUTEX)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+
+    /*
+     * Kill it, kick waiters and release it.
+     */
+    AssertReturn(ASMAtomicCmpXchgU32(&pThis->u32Magic, RTSEMMUTEX_MAGIC_DEAD, RTSEMMUTEX_MAGIC), VERR_INVALID_HANDLE);
+
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    spin_lock_irqsave(&pThis->Spinlock, fSavedIrq);
+    RTListForEach(&pThis->WaiterList, pCur, RTSEMMUTEXLNXWAITER, ListEntry)
+    {
+        pCur->enmReason = RTSEMMUTEXLNXWAITER_DESTROYED;
+        wake_up_process(pCur->pTask);
+    }
+
+    if (ASMAtomicDecU32(&pThis->cRefs) != 0)
+        spin_unlock_irqrestore(&pThis->Spinlock, fSavedIrq);
+    else
+    {
+        spin_unlock_irqrestore(&pThis->Spinlock, fSavedIrq);
+        RTMemFree(pThis);
+    }
+
+    IPRT_LINUX_RESTORE_EFL_AC();
+
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTSemMutexDestroy);
+
+
+/**
+ * Worker for rtSemMutexLinuxRequest that handles the case where we go to sleep.
+ *
+ * @returns VINF_SUCCESS, VERR_INTERRUPTED, VERR_TIMEOUT or VERR_SEM_DESTROYED.
+ *          Returns without owning the spinlock.
+ * @param   pThis           The mutex instance.
+ * @param   cMillies        The timeout.
+ * @param   fInterruptible  The wait type.
+ * @param   fSavedIrq       The saved IRQ flags.
+ */
+static int rtSemMutexLinuxRequestSleep(PRTSEMMUTEXINTERNAL pThis, RTMSINTERVAL cMillies,
+                                       bool fInterruptible, unsigned long fSavedIrq)
+{
+    struct task_struct *pSelf    = current;
+    int                 rc       = VERR_TIMEOUT;
+    long                lTimeout = cMillies == RT_INDEFINITE_WAIT ? MAX_SCHEDULE_TIMEOUT : msecs_to_jiffies(cMillies);
+    RTSEMMUTEXLNXWAITER Waiter;
+
+    IPRT_DEBUG_SEMS_STATE(pThis, 'm');
+
+    /*
+     * Grab a reference to the mutex and add ourselves to the waiter list.
+     */
+    ASMAtomicIncU32(&pThis->cRefs);
+
+    Waiter.pTask     = pSelf;
+    Waiter.enmReason = RTSEMMUTEXLNXWAITER_OTHER;
+    RTListAppend(&pThis->WaiterList, &Waiter.ListEntry);
+
+    /*
+     * Do the waiting.
+     */
+    for (;;)
+    {
+        /* Check signal and timeout conditions. */
+        if (    fInterruptible
+            &&  signal_pending(pSelf))
+        {
+            rc = VERR_INTERRUPTED;
+            break;
+        }
+
+        if (!lTimeout)
+            break;
+
+        /* Go to sleep. */
+        set_current_state(fInterruptible ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
+        spin_unlock_irq(&pThis->Spinlock);
+
+        lTimeout = schedule_timeout(lTimeout);
+
+        spin_lock_irq(&pThis->Spinlock);
+        set_current_state(TASK_RUNNING);
+
+        /* Did someone wake us up? */
+        if (Waiter.enmReason == RTSEMMUTEXLNXWAITER_WAKEUP)
+        {
+            Assert(pThis->cRecursions == 0);
+            pThis->cRecursions = 1;
+            pThis->pOwnerTask  = pSelf;
+            rc = VINF_SUCCESS;
+            break;
+        }
+
+        /* Is the mutex being destroyed? */
+        if (RT_UNLIKELY(   Waiter.enmReason == RTSEMMUTEXLNXWAITER_DESTROYED
+                        || pThis->u32Magic != RTSEMMUTEX_MAGIC))
+        {
+            rc = VERR_SEM_DESTROYED;
+            break;
+        }
+    }
+
+    /*
+     * Unlink ourself from the waiter list, dereference the mutex and exit the
+     * lock.  We might have to free the mutex if it was the destroyed.
+     */
+    RTListNodeRemove(&Waiter.ListEntry);
+    IPRT_DEBUG_SEMS_STATE_RC(pThis, 'M', rc);
+
+    if (RT_LIKELY(ASMAtomicDecU32(&pThis->cRefs) != 0))
+        spin_unlock_irqrestore(&pThis->Spinlock, fSavedIrq);
+    else
+    {
+        Assert(RT_FAILURE_NP(rc));
+        spin_unlock_irqrestore(&pThis->Spinlock, fSavedIrq);
+        RTMemFree(pThis);
+    }
+    return rc;
+}
+
+
+/**
+ * Internal worker.
+ */
+DECLINLINE(int) rtSemMutexLinuxRequest(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, bool fInterruptible)
+{
+    PRTSEMMUTEXINTERNAL pThis = hMutexSem;
+    struct task_struct *pSelf = current;
+    unsigned long       fSavedIrq;
+    int                 rc;
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    /*
+     * Validate.
+     */
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+    Assert(pThis->cRefs >= 1);
+
+    /*
+     * Lock it and check if it's a recursion.
+     */
+    spin_lock_irqsave(&pThis->Spinlock, fSavedIrq);
+    if (pThis->pOwnerTask == pSelf)
+    {
+        pThis->cRecursions++;
+        Assert(pThis->cRecursions > 1);
+        Assert(pThis->cRecursions < 256);
+        rc = VINF_SUCCESS;
+    }
+    /*
+     * Not a recursion, maybe it's not owned by anyone then?
+     */
+    else if (   pThis->pOwnerTask == NULL
+             && RTListIsEmpty(&pThis->WaiterList))
+    {
+        Assert(pThis->cRecursions == 0);
+        pThis->cRecursions = 1;
+        pThis->pOwnerTask  = pSelf;
+        rc = VINF_SUCCESS;
+    }
+    /*
+     * Was it a polling call?
+     */
+    else if (cMillies == 0)
+        rc = VERR_TIMEOUT;
+    /*
+     * No, so go to sleep.
+     */
+    else
+    {
+        rc = rtSemMutexLinuxRequestSleep(pThis, cMillies, fInterruptible, fSavedIrq);
+        IPRT_LINUX_RESTORE_EFL_ONLY_AC();
+        return rc;
+    }
+
+    IPRT_DEBUG_SEMS_STATE_RC(pThis, 'M', rc);
+    spin_unlock_irqrestore(&pThis->Spinlock, fSavedIrq);
+    IPRT_LINUX_RESTORE_EFL_ONLY_AC();
+    return rc;
+}
+
+
+RTDECL(int) RTSemMutexRequest(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies)
+{
+    return rtSemMutexLinuxRequest(hMutexSem, cMillies, false /*fInterruptible*/);
+}
+RT_EXPORT_SYMBOL(RTSemMutexRequest);
+
+
+RTDECL(int) RTSemMutexRequestDebug(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RT_NOREF_PV(uId); RT_SRC_POS_NOREF();
+    return RTSemMutexRequest(hMutexSem, cMillies);
+}
+RT_EXPORT_SYMBOL(RTSemMutexRequestDebug);
+
+
+RTDECL(int) RTSemMutexRequestNoResume(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies)
+{
+    return rtSemMutexLinuxRequest(hMutexSem, cMillies, true /*fInterruptible*/);
+}
+RT_EXPORT_SYMBOL(RTSemMutexRequestNoResume);
+
+
+RTDECL(int) RTSemMutexRequestNoResumeDebug(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RT_NOREF_PV(uId); RT_SRC_POS_NOREF();
+    return RTSemMutexRequestNoResume(hMutexSem, cMillies);
+}
+RT_EXPORT_SYMBOL(RTSemMutexRequestNoResumeDebug);
+
+
+RTDECL(int) RTSemMutexRelease(RTSEMMUTEX hMtx)
+{
+    PRTSEMMUTEXINTERNAL pThis = hMtx;
+    struct task_struct *pSelf = current;
+    unsigned long       fSavedIrq;
+    int                 rc;
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    /*
+     * Validate.
+     */
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+    Assert(pThis->cRefs >= 1);
+
+    /*
+     * Take the lock and release one recursion.
+     */
+    spin_lock_irqsave(&pThis->Spinlock, fSavedIrq);
+    if (pThis->pOwnerTask == pSelf)
+    {
+        Assert(pThis->cRecursions > 0);
+        if (--pThis->cRecursions == 0)
+        {
+            pThis->pOwnerTask = NULL;
+
+            /* anyone to wake up? */
+            if (!RTListIsEmpty(&pThis->WaiterList))
+            {
+                PRTSEMMUTEXLNXWAITER pWaiter = RTListGetFirst(&pThis->WaiterList, RTSEMMUTEXLNXWAITER, ListEntry);
+                pWaiter->enmReason = RTSEMMUTEXLNXWAITER_WAKEUP;
+                wake_up_process(pWaiter->pTask);
+            }
+            IPRT_DEBUG_SEMS_STATE(pThis, 'u');
+        }
+        rc = VINF_SUCCESS;
+    }
+    else
+        rc = VERR_NOT_OWNER;
+    spin_unlock_irqrestore(&pThis->Spinlock, fSavedIrq);
+
+    AssertRC(rc);
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return rc;
+}
+RT_EXPORT_SYMBOL(RTSemMutexRelease);
+
+
+RTDECL(bool) RTSemMutexIsOwned(RTSEMMUTEX hMutexSem)
+{
+    PRTSEMMUTEXINTERNAL pThis = hMutexSem;
+    unsigned long       fSavedIrq;
+    bool                fOwned;
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    /*
+     * Validate.
+     */
+    AssertPtrReturn(pThis, false);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), false);
+    Assert(pThis->cRefs >= 1);
+
+    /*
+     * Take the lock and release one recursion.
+     */
+    spin_lock_irqsave(&pThis->Spinlock, fSavedIrq);
+    fOwned = pThis->pOwnerTask != NULL;
+    spin_unlock_irqrestore(&pThis->Spinlock, fSavedIrq);
+
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return fOwned;
+
+}
+RT_EXPORT_SYMBOL(RTSemMutexIsOwned);
+
diff --git a/src/VBox/Runtime/r0drv/linux/spinlock-r0drv-linux.c b/src/VBox/Runtime/r0drv/linux/spinlock-r0drv-linux.c
new file mode 100644
index 00000000..c6ba0ed7
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/spinlock-r0drv-linux.c
@@ -0,0 +1,186 @@
+/* $Id: spinlock-r0drv-linux.c $ */
+/** @file
+ * IPRT - Spinlocks, Ring-0 Driver, Linux.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-linux-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/spinlock.h>
+
+#include <iprt/asm.h>
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+#include <iprt/mem.h>
+#include <iprt/mp.h>
+#include <iprt/thread.h>
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Wrapper for the spinlock_t structure.
+ */
+typedef struct RTSPINLOCKINTERNAL
+{
+    /** Spinlock magic value (RTSPINLOCK_MAGIC). */
+    uint32_t volatile       u32Magic;
+    /** The spinlock creation flags.  */
+    uint32_t                fFlags;
+    /** The saved interrupt flag. */
+    unsigned long volatile  fIntSaved;
+    /** The linux spinlock structure. */
+    spinlock_t              Spinlock;
+#ifdef RT_MORE_STRICT
+    /** The idAssertCpu variable before acquring the lock for asserting after
+     *  releasing the spinlock. */
+    RTCPUID volatile        idAssertCpu;
+    /** The CPU that owns the lock. */
+    RTCPUID volatile        idCpuOwner;
+#endif
+} RTSPINLOCKINTERNAL, *PRTSPINLOCKINTERNAL;
+
+
+
+RTDECL(int)  RTSpinlockCreate(PRTSPINLOCK pSpinlock, uint32_t fFlags, const char *pszName)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+    PRTSPINLOCKINTERNAL pThis;
+    AssertReturn(fFlags == RTSPINLOCK_FLAGS_INTERRUPT_SAFE || fFlags == RTSPINLOCK_FLAGS_INTERRUPT_UNSAFE, VERR_INVALID_PARAMETER);
+    RT_NOREF_PV(pszName);
+
+    /*
+     * Allocate.
+     */
+    Assert(sizeof(RTSPINLOCKINTERNAL) > sizeof(void *));
+    pThis = (PRTSPINLOCKINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (!pThis)
+        return VERR_NO_MEMORY;
+    /*
+     * Initialize and return.
+     */
+    pThis->u32Magic     = RTSPINLOCK_MAGIC;
+    pThis->fFlags       = fFlags;
+    pThis->fIntSaved    = 0;
+#ifdef RT_MORE_STRICT
+    pThis->idCpuOwner   = NIL_RTCPUID;
+    pThis->idAssertCpu  = NIL_RTCPUID;
+#endif
+
+    spin_lock_init(&pThis->Spinlock);
+
+    *pSpinlock = pThis;
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTSpinlockCreate);
+
+
+RTDECL(int)  RTSpinlockDestroy(RTSPINLOCK Spinlock)
+{
+    /*
+     * Validate input.
+     */
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
+    if (!pThis)
+        return VERR_INVALID_PARAMETER;
+    if (pThis->u32Magic != RTSPINLOCK_MAGIC)
+    {
+        AssertMsgFailed(("Invalid spinlock %p magic=%#x\n", pThis, pThis->u32Magic));
+        return VERR_INVALID_PARAMETER;
+    }
+
+    ASMAtomicIncU32(&pThis->u32Magic);
+    RTMemFree(pThis);
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTSpinlockDestroy);
+
+
+RTDECL(void) RTSpinlockAcquire(RTSPINLOCK Spinlock)
+{
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
+    IPRT_LINUX_SAVE_EFL_AC();
+    RT_ASSERT_PREEMPT_CPUID_VAR();
+    AssertMsg(pThis && pThis->u32Magic == RTSPINLOCK_MAGIC,
+              ("pThis=%p u32Magic=%08x\n", pThis, pThis ? (int)pThis->u32Magic : 0));
+
+#ifdef CONFIG_PROVE_LOCKING
+    lockdep_off();
+#endif
+    if (pThis->fFlags & RTSPINLOCK_FLAGS_INTERRUPT_SAFE)
+    {
+        unsigned long fIntSaved;
+        spin_lock_irqsave(&pThis->Spinlock, fIntSaved);
+        pThis->fIntSaved = fIntSaved;
+    }
+    else
+        spin_lock(&pThis->Spinlock);
+#ifdef CONFIG_PROVE_LOCKING
+    lockdep_on();
+#endif
+
+    IPRT_LINUX_RESTORE_EFL_ONLY_AC();
+    RT_ASSERT_PREEMPT_CPUID_SPIN_ACQUIRED(pThis);
+}
+RT_EXPORT_SYMBOL(RTSpinlockAcquire);
+
+
+RTDECL(void) RTSpinlockRelease(RTSPINLOCK Spinlock)
+{
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
+    IPRT_LINUX_SAVE_EFL_AC();           /* spin_unlock* may preempt and trash eflags.ac. */
+    RT_ASSERT_PREEMPT_CPUID_SPIN_RELEASE_VARS();
+    AssertMsg(pThis && pThis->u32Magic == RTSPINLOCK_MAGIC,
+              ("pThis=%p u32Magic=%08x\n", pThis, pThis ? (int)pThis->u32Magic : 0));
+    RT_ASSERT_PREEMPT_CPUID_SPIN_RELEASE(pThis);
+
+#ifdef CONFIG_PROVE_LOCKING
+    lockdep_off();
+#endif
+    if (pThis->fFlags & RTSPINLOCK_FLAGS_INTERRUPT_SAFE)
+    {
+        unsigned long fIntSaved = pThis->fIntSaved;
+        pThis->fIntSaved = 0;
+        spin_unlock_irqrestore(&pThis->Spinlock, fIntSaved);
+    }
+    else
+        spin_unlock(&pThis->Spinlock);
+#ifdef CONFIG_PROVE_LOCKING
+    lockdep_on();
+#endif
+
+    IPRT_LINUX_RESTORE_EFL_ONLY_AC();
+    RT_ASSERT_PREEMPT_CPUID();
+}
+RT_EXPORT_SYMBOL(RTSpinlockRelease);
+
diff --git a/src/VBox/Runtime/r0drv/linux/string.h b/src/VBox/Runtime/r0drv/linux/string.h
new file mode 100644
index 00000000..0560fa1f
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/string.h
@@ -0,0 +1,60 @@
+/* $Id: string.h $ */
+/** @file
+ * IPRT - wrapper for the linux kernel asm/string.h.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+#ifndef IPRT_INCLUDED_SRC_r0drv_linux_string_h
+#define IPRT_INCLUDED_SRC_r0drv_linux_string_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <iprt/cdefs.h>
+
+RT_C_DECLS_BEGIN
+#ifndef bool /* Linux 2.6.19 C++ nightmare */
+#define bool bool_type
+#define true true_type
+#define false false_type
+#define _Bool int
+#define bool_type_r0drv_string_h__
+#endif
+#include <linux/types.h>
+#include <linux/string.h>
+#ifdef bool_type_r0drv_string_h__
+#undef bool
+#undef true
+#undef false
+#undef bool_type_r0drv_string_h__
+#endif
+char *strpbrk(const char *pszStr, const char *pszChars)
+#if defined(__THROW)
+    __THROW
+#endif
+    ;
+
+RT_C_DECLS_END
+
+#endif /* !IPRT_INCLUDED_SRC_r0drv_linux_string_h */
+
diff --git a/src/VBox/Runtime/r0drv/linux/the-linux-kernel.h b/src/VBox/Runtime/r0drv/linux/the-linux-kernel.h
new file mode 100644
index 00000000..138072ad
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/the-linux-kernel.h
@@ -0,0 +1,479 @@
+/* $Id: the-linux-kernel.h $ */
+/** @file
+ * IPRT - Include all necessary headers for the Linux kernel.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+#ifndef IPRT_INCLUDED_SRC_r0drv_linux_the_linux_kernel_h
+#define IPRT_INCLUDED_SRC_r0drv_linux_the_linux_kernel_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+/*
+ * Include iprt/types.h to install the bool wrappers.
+ * Then use the linux bool type for all the stuff include here.
+ */
+#include <iprt/types.h>
+#define bool linux_bool
+
+#if RT_GNUC_PREREQ(4, 6)
+# pragma GCC diagnostic push
+#endif
+#if RT_GNUC_PREREQ(4, 2)
+# pragma GCC diagnostic ignored "-Wunused-parameter"
+# if !defined(__cplusplus) && RT_GNUC_PREREQ(4, 3)
+#  pragma GCC diagnostic ignored "-Wold-style-declaration" /* 2.6.18-411.0.0.0.1.el5/build/include/asm/apic.h:110: warning: 'inline' is not at beginning of declaration [-Wold-style-declaration] */
+# endif
+#endif
+
+
+#include <iprt/linux/version.h>
+#if RTLNX_VER_MIN(2,6,33)
+# include <generated/autoconf.h>
+#else
+# ifndef AUTOCONF_INCLUDED
+#  include <linux/autoconf.h>
+# endif
+#endif
+
+/* We only support 2.4 and 2.6 series kernels */
+#if RTLNX_VER_MAX(2,4,0)
+# error Sorry, we do not support 2.3 and earlier kernels.
+#endif
+#if RTLNX_VER_MIN(2,5,0) && RTLNX_VER_MAX(2,6,0)
+# error Sorry, we do not support 2.5 series kernels (might work though).
+#endif
+
+#if defined(CONFIG_MODVERSIONS) && !defined(MODVERSIONS)
+# define MODVERSIONS
+# if RTLNX_VER_MAX(2,5,71)
+#  include <linux/modversions.h>
+# endif
+#endif
+#ifndef KBUILD_STR
+# if RTLNX_VER_MAX(2,6,16)
+#  define KBUILD_STR(s) s
+# else
+#  define KBUILD_STR(s) #s
+# endif
+#endif
+# if RTLNX_VER_MIN(3,3,0)
+#  include <linux/kconfig.h> /* for macro IS_ENABLED */
+# endif
+#include <linux/string.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#if RTLNX_VER_MIN(2,6,27)
+# include <linux/semaphore.h>
+#else /* older kernels */
+# include <asm/semaphore.h>
+#endif /* older kernels */
+#include <linux/module.h>
+#if RTLNX_VER_MIN(2,6,0)
+# include <linux/moduleparam.h>
+#endif
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#if RTLNX_VER_MIN(2,6,0)
+# include <linux/namei.h>
+#endif
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/slab.h>
+#include <linux/time.h>
+#include <linux/sched.h>
+
+#if RTLNX_VER_RANGE(3,9,23,  3,9,31)
+# include  <linux/splice.h>
+#endif
+
+#if RTLNX_VER_MIN(3,9,0)
+# include <linux/sched/rt.h>
+#endif
+#if RTLNX_VER_MIN(4,11,0)
+# include <linux/sched/signal.h>
+# include <linux/sched/types.h>
+#endif
+#if RTLNX_VER_MIN(2,6,7)
+# include <linux/jiffies.h>
+#endif
+#if RTLNX_VER_MIN(2,6,16)
+# include <linux/ktime.h>
+# include <linux/hrtimer.h>
+#endif
+#include <linux/wait.h>
+#if RTLNX_VER_MIN(2,5,71)
+# include <linux/cpu.h>
+# include <linux/notifier.h>
+#endif
+#if RTLNX_VER_MIN(5,1,0)
+# include <uapi/linux/mman.h>
+#endif
+/* For the basic additions module */
+#include <linux/pci.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/completion.h>
+#include <linux/compiler.h>
+#if RTLNX_VER_MIN(5,9,0) /* linux/fs.h defined HAVE_UNLOCKED_IOCTL from 2.6.11 up to 5.9, when it became an implicit assumption. */
+# define HAVE_UNLOCKED_IOCTL 1 /* We use this in a couple of places, so for now just define it for 5.9+ too. */
+#endif
+#if !defined(HAVE_UNLOCKED_IOCTL) && RTLNX_VER_MAX(2,6,38)
+# include <linux/smp_lock.h>
+#endif
+/* For the shared folders module */
+#include <linux/vmalloc.h>
+#define wchar_t linux_wchar_t
+#include <linux/nls.h>
+#undef wchar_t
+#include <asm/mman.h>
+#include <asm/io.h>
+#include <asm/uaccess.h>
+#include <asm/div64.h>
+
+/* For thread-context hooks. */
+#if RTLNX_VER_MIN(2,6,18) && defined(CONFIG_PREEMPT_NOTIFIERS)
+# include <linux/preempt.h>
+#endif
+
+/* for workqueue / task queues. */
+#if RTLNX_VER_MIN(2,5,41)
+# include <linux/workqueue.h>
+#else
+# include <linux/tqueue.h>
+#endif
+
+#if RTLNX_VER_MIN(2,6,4)
+# include <linux/kthread.h>
+#endif
+
+/* for cr4_init_shadow() / cpu_tlbstate. */
+#if RTLNX_VER_MIN(3,20,0)
+# include <asm/tlbflush.h>
+#endif
+
+/* for set_pages_x() */
+#if RTLNX_VER_MIN(4,12,0)
+# include <asm/set_memory.h>
+#endif
+
+/* for __flush_tlb_all() */
+#if RTLNX_VER_MIN(2,6,28) && (defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86))
+# include <asm/tlbflush.h>
+#endif
+
+#if RTLNX_VER_MIN(3,7,0)
+# include <asm/smap.h>
+#else
+static inline void clac(void) { }
+static inline void stac(void) { }
+#endif
+
+#if RTLNX_VER_MAX(2,6,0)
+# ifndef page_to_pfn
+#  define page_to_pfn(page) ((page) - mem_map)
+# endif
+#endif
+
+#ifndef DEFINE_WAIT
+# define DEFINE_WAIT(name) DECLARE_WAITQUEUE(name, current)
+#endif
+
+#ifndef __GFP_NOWARN
+# define __GFP_NOWARN 0
+#endif
+
+/*
+ * 2.4 / early 2.6 compatibility wrappers
+ */
+#if RTLNX_VER_MAX(2,6,7)
+
+# ifndef MAX_JIFFY_OFFSET
+#  define MAX_JIFFY_OFFSET ((~0UL >> 1)-1)
+# endif
+
+# if RTLNX_VER_MAX(2,4,29) || RTLNX_VER_MIN(2,6,0)
+
+DECLINLINE(unsigned int) jiffies_to_msecs(unsigned long cJiffies)
+{
+#  if HZ <= 1000 && !(1000 % HZ)
+    return (1000 / HZ) * cJiffies;
+#  elif HZ > 1000 && !(HZ % 1000)
+    return (cJiffies + (HZ / 1000) - 1) / (HZ / 1000);
+#  else
+    return (cJiffies * 1000) / HZ;
+#  endif
+}
+
+DECLINLINE(unsigned long) msecs_to_jiffies(unsigned int cMillies)
+{
+#  if HZ > 1000
+    if (cMillies > jiffies_to_msecs(MAX_JIFFY_OFFSET))
+        return MAX_JIFFY_OFFSET;
+#  endif
+#  if HZ <= 1000 && !(1000 % HZ)
+    return (cMillies + (1000 / HZ) - 1) / (1000 / HZ);
+#  elif HZ > 1000 && !(HZ % 1000)
+    return cMillies * (HZ / 1000);
+#  else
+    return (cMillies * HZ + 999) / 1000;
+#  endif
+}
+
+# endif  /* < 2.4.29 || >= 2.6.0 */
+
+#endif /* < 2.6.7 */
+
+/*
+ * 2.4 compatibility wrappers
+ */
+#if RTLNX_VER_MAX(2,6,0)
+
+# define prepare_to_wait(q, wait, state) \
+    do { \
+        add_wait_queue(q, wait); \
+        set_current_state(state); \
+    } while (0)
+
+# define after_wait(wait) \
+    do { \
+        list_del_init(&(wait)->task_list); \
+    } while (0)
+
+# define finish_wait(q, wait) \
+    do { \
+        set_current_state(TASK_RUNNING); \
+        remove_wait_queue(q, wait); \
+    } while (0)
+
+#else /* >= 2.6.0 */
+
+# define after_wait(wait)       do {} while (0)
+
+#endif /* >= 2.6.0 */
+
+/** @def TICK_NSEC
+ * The time between ticks in nsec */
+#ifndef TICK_NSEC
+# define TICK_NSEC (1000000000UL / HZ)
+#endif
+
+/*
+ * This sucks soooo badly on x86! Why don't they export __PAGE_KERNEL_EXEC so PAGE_KERNEL_EXEC would be usable?
+ */
+#if   RTLNX_VER_MIN(2,6,8) && defined(RT_ARCH_AMD64)
+# define MY_PAGE_KERNEL_EXEC    PAGE_KERNEL_EXEC
+#elif RTLNX_VER_MIN(2,6,8) && defined(PAGE_KERNEL_EXEC) && defined(CONFIG_X86_PAE)
+# ifdef __PAGE_KERNEL_EXEC
+   /* >= 2.6.27 */
+#  define MY_PAGE_KERNEL_EXEC   __pgprot(boot_cpu_has(X86_FEATURE_PGE) ? __PAGE_KERNEL_EXEC | _PAGE_GLOBAL : __PAGE_KERNEL_EXEC)
+# else
+#  define MY_PAGE_KERNEL_EXEC   __pgprot(boot_cpu_has(X86_FEATURE_PGE) ? _PAGE_KERNEL_EXEC | _PAGE_GLOBAL : _PAGE_KERNEL_EXEC)
+# endif
+#else
+# define MY_PAGE_KERNEL_EXEC    PAGE_KERNEL
+#endif
+
+
+/*
+ * The redhat hack section.
+ *  - The current hacks are for 2.4.21-15.EL only.
+ */
+#ifndef NO_REDHAT_HACKS
+/* accounting. */
+# if RTLNX_VER_MAX(2,6,0)
+#  ifdef VM_ACCOUNT
+#   define USE_RHEL4_MUNMAP
+#  endif
+# endif
+
+/* backported remap_page_range. */
+# if RTLNX_VER_MAX(2,6,0)
+#  include <asm/tlb.h>
+#  ifdef tlb_vma /* probably not good enough... */
+#   define HAVE_26_STYLE_REMAP_PAGE_RANGE 1
+#  endif
+# endif
+
+# ifndef RT_ARCH_AMD64
+/* In 2.6.9-22.ELsmp we have to call change_page_attr() twice when changing
+ * the page attributes from PAGE_KERNEL to something else, because there appears
+ * to be a bug in one of the many patches that redhat applied.
+ * It should be safe to do this on less buggy linux kernels too. ;-)
+ */
+#  define MY_CHANGE_PAGE_ATTR(pPages, cPages, prot) \
+    do { \
+        if (pgprot_val(prot) != pgprot_val(PAGE_KERNEL)) \
+            change_page_attr(pPages, cPages, prot); \
+        change_page_attr(pPages, cPages, prot); \
+    } while (0)
+# endif  /* !RT_ARCH_AMD64 */
+#endif /* !NO_REDHAT_HACKS */
+
+#ifndef MY_CHANGE_PAGE_ATTR
+# ifdef RT_ARCH_AMD64 /** @todo This is a cheap hack, but it'll get around that 'else BUG();' in __change_page_attr().  */
+#  define MY_CHANGE_PAGE_ATTR(pPages, cPages, prot) \
+    do { \
+        change_page_attr(pPages, cPages, PAGE_KERNEL_NOCACHE); \
+        change_page_attr(pPages, cPages, prot); \
+    } while (0)
+# else
+#  define MY_CHANGE_PAGE_ATTR(pPages, cPages, prot) change_page_attr(pPages, cPages, prot)
+# endif
+#endif
+
+#if RTLNX_VER_MIN(2,6,25)
+# if RTLNX_VER_MAX(5,4,0) /* The interface was removed, but we only need it for < 2.4.22, so who cares. */
+#  define MY_SET_PAGES_EXEC(pPages, cPages)     set_pages_x(pPages, cPages)
+#  define MY_SET_PAGES_NOEXEC(pPages, cPages)   set_pages_nx(pPages, cPages)
+# endif
+#else
+# define MY_SET_PAGES_EXEC(pPages, cPages) \
+    do { \
+        if (pgprot_val(MY_PAGE_KERNEL_EXEC) != pgprot_val(PAGE_KERNEL)) \
+            MY_CHANGE_PAGE_ATTR(pPages, cPages, MY_PAGE_KERNEL_EXEC); \
+    } while (0)
+# define MY_SET_PAGES_NOEXEC(pPages, cPages) \
+    do { \
+        if (pgprot_val(MY_PAGE_KERNEL_EXEC) != pgprot_val(PAGE_KERNEL)) \
+            MY_CHANGE_PAGE_ATTR(pPages, cPages, PAGE_KERNEL); \
+    } while (0)
+#endif
+
+/** @def ONE_MSEC_IN_JIFFIES
+ * The number of jiffies that make up 1 millisecond. Must be at least 1! */
+#if HZ <= 1000
+# define ONE_MSEC_IN_JIFFIES       1
+#elif !(HZ % 1000)
+# define ONE_MSEC_IN_JIFFIES       (HZ / 1000)
+#else
+# define ONE_MSEC_IN_JIFFIES       ((HZ + 999) / 1000)
+# error "HZ is not a multiple of 1000, the GIP stuff won't work right!"
+#endif
+
+/*
+ * Stop using the linux bool type.
+ */
+#undef bool
+
+#if RT_GNUC_PREREQ(4, 6)
+# pragma GCC diagnostic pop
+#endif
+
+/*
+ * There are post-2.6.24 kernels (confusingly with unchanged version number)
+ * which eliminate macros which were marked as deprecated.
+ */
+#ifndef __attribute_used__
+#define __attribute_used__ __used
+#endif
+
+/**
+ * Hack for shortening pointers on linux so we can stuff more stuff into the
+ * task_struct::comm field. This is used by the semaphore code but put here
+ * because we don't have any better place atm. Don't use outside IPRT, please.
+ */
+#ifdef RT_ARCH_AMD64
+# define IPRT_DEBUG_SEMS_ADDRESS(addr)  ( ((long)(addr) & (long)~UINT64_C(0xfffffff000000000)) )
+#else
+# define IPRT_DEBUG_SEMS_ADDRESS(addr)  ( (long)(addr) )
+#endif
+
+/**
+ * Puts semaphore info into the task_struct::comm field if IPRT_DEBUG_SEMS is
+ * defined.
+ */
+#ifdef IPRT_DEBUG_SEMS
+# define IPRT_DEBUG_SEMS_STATE(pThis, chState) \
+    snprintf(current->comm, sizeof(current->comm), "%c%lx", (chState), IPRT_DEBUG_SEMS_ADDRESS(pThis));
+#else
+# define IPRT_DEBUG_SEMS_STATE(pThis, chState)  do {  } while (0)
+#endif
+
+/**
+ * Puts semaphore info into the task_struct::comm field if IPRT_DEBUG_SEMS is
+ * defined.
+ */
+#ifdef IPRT_DEBUG_SEMS
+# define IPRT_DEBUG_SEMS_STATE_RC(pThis, chState, rc) \
+    snprintf(current->comm, sizeof(current->comm), "%c%lx:%d", (chState), IPRT_DEBUG_SEMS_ADDRESS(pThis), rc);
+#else
+# define IPRT_DEBUG_SEMS_STATE_RC(pThis, chState, rc)  do {  } while (0)
+#endif
+
+/** @name Macros for preserving EFLAGS.AC on 3.19+/amd64  paranoid.
+ * The AMD 64 switch_to in macro in arch/x86/include/asm/switch_to.h stopped
+ * restoring flags.
+ * @{ */
+#if (defined(CONFIG_X86_SMAP) || defined(RT_STRICT) || defined(IPRT_WITH_EFLAGS_AC_PRESERVING)) \
+  && !defined(IPRT_WITHOUT_EFLAGS_AC_PRESERVING)
+# include <iprt/asm-amd64-x86.h>
+# define IPRT_X86_EFL_AC                    RT_BIT(18)
+# define IPRT_LINUX_SAVE_EFL_AC()           RTCCUINTREG fSavedEfl = ASMGetFlags()
+# define IPRT_LINUX_RESTORE_EFL_AC()        ASMSetFlags(fSavedEfl)
+# define IPRT_LINUX_RESTORE_EFL_ONLY_AC()   ASMChangeFlags(~IPRT_X86_EFL_AC, fSavedEfl & IPRT_X86_EFL_AC)
+#else
+# define IPRT_LINUX_SAVE_EFL_AC()           do { } while (0)
+# define IPRT_LINUX_RESTORE_EFL_AC()        do { } while (0)
+# define IPRT_LINUX_RESTORE_EFL_ONLY_AC()   do { } while (0)
+#endif
+/** @} */
+
+/*
+ * There are some conflicting defines in iprt/param.h, sort them out here.
+ */
+#ifndef IPRT_INCLUDED_param_h
+# undef PAGE_SIZE
+# undef PAGE_OFFSET_MASK
+# include <iprt/param.h>
+#endif
+
+/*
+ * Some global indicator macros.
+ */
+/** @def IPRT_LINUX_HAS_HRTIMER
+ * Whether the kernel support high resolution timers (Linux kernel versions
+ * 2.6.28 and later (hrtimer_add_expires_ns() & schedule_hrtimeout). */
+#if RTLNX_VER_MIN(2,6,28)
+# define IPRT_LINUX_HAS_HRTIMER
+#endif
+
+/*
+ * Workqueue stuff, see initterm-r0drv-linux.c.
+ */
+#if RTLNX_VER_MIN(2,5,41)
+typedef struct work_struct  RTR0LNXWORKQUEUEITEM;
+#else
+typedef struct tq_struct    RTR0LNXWORKQUEUEITEM;
+#endif
+DECLHIDDEN(void) rtR0LnxWorkqueuePush(RTR0LNXWORKQUEUEITEM *pWork, void (*pfnWorker)(RTR0LNXWORKQUEUEITEM *));
+DECLHIDDEN(void) rtR0LnxWorkqueueFlush(void);
+
+/*
+ * Memory hacks from memobj-r0drv-linux.c that shared folders need.
+ */
+RTDECL(struct page *) rtR0MemObjLinuxVirtToPage(void *pv);
+
+#endif /* !IPRT_INCLUDED_SRC_r0drv_linux_the_linux_kernel_h */
diff --git a/src/VBox/Runtime/r0drv/linux/thread-r0drv-linux.c b/src/VBox/Runtime/r0drv/linux/thread-r0drv-linux.c
new file mode 100644
index 00000000..bda9c789
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/thread-r0drv-linux.c
@@ -0,0 +1,234 @@
+/* $Id: thread-r0drv-linux.c $ */
+/** @file
+ * IPRT - Threads, Ring-0 Driver, Linux.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-linux-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/thread.h>
+
+#include <iprt/asm.h>
+#if RTLNX_VER_MAX(2,5,28) || defined(CONFIG_X86_SMAP)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+#include <iprt/mp.h>
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+#ifndef CONFIG_PREEMPT
+/** Per-cpu preemption counters. */
+static int32_t volatile g_acPreemptDisabled[NR_CPUS];
+#endif
+
+
+RTDECL(RTNATIVETHREAD) RTThreadNativeSelf(void)
+{
+    return (RTNATIVETHREAD)current;
+}
+RT_EXPORT_SYMBOL(RTThreadNativeSelf);
+
+
+static int rtR0ThreadLnxSleepCommon(RTMSINTERVAL cMillies)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+    long cJiffies = msecs_to_jiffies(cMillies);
+    set_current_state(TASK_INTERRUPTIBLE);
+    cJiffies = schedule_timeout(cJiffies);
+    IPRT_LINUX_RESTORE_EFL_AC();
+    if (!cJiffies)
+        return VINF_SUCCESS;
+    return VERR_INTERRUPTED;
+}
+
+
+RTDECL(int) RTThreadSleep(RTMSINTERVAL cMillies)
+{
+    return rtR0ThreadLnxSleepCommon(cMillies);
+}
+RT_EXPORT_SYMBOL(RTThreadSleep);
+
+
+RTDECL(int) RTThreadSleepNoLog(RTMSINTERVAL cMillies)
+{
+    return rtR0ThreadLnxSleepCommon(cMillies);
+}
+RT_EXPORT_SYMBOL(RTThreadSleepNoLog);
+
+
+RTDECL(bool) RTThreadYield(void)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+#if RTLNX_VER_MIN(2,4,20)
+    yield();
+#else
+    /** @todo r=ramshankar: Can we use cond_resched() instead?  */
+    set_current_state(TASK_RUNNING);
+    sys_sched_yield();
+    schedule();
+#endif
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return true;
+}
+RT_EXPORT_SYMBOL(RTThreadYield);
+
+
+RTDECL(bool) RTThreadPreemptIsEnabled(RTTHREAD hThread)
+{
+#ifdef CONFIG_PREEMPT
+    Assert(hThread == NIL_RTTHREAD); RT_NOREF_PV(hThread);
+# ifdef preemptible
+    return preemptible();
+# else
+    return preempt_count() == 0 && !in_atomic() && !irqs_disabled();
+# endif
+#else
+    int32_t c;
+
+    Assert(hThread == NIL_RTTHREAD);
+    c = g_acPreemptDisabled[smp_processor_id()];
+    AssertMsg(c >= 0 && c < 32, ("%d\n", c));
+    if (c != 0)
+        return false;
+# if RTLNX_VER_MIN(2,5,32)
+    if (in_atomic())
+        return false;
+# endif
+# if RTLNX_VER_MIN(2,5,28)
+    if (irqs_disabled())
+        return false;
+# else
+    if (!ASMIntAreEnabled())
+        return false;
+# endif
+    return true;
+#endif
+}
+RT_EXPORT_SYMBOL(RTThreadPreemptIsEnabled);
+
+
+RTDECL(bool) RTThreadPreemptIsPending(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD); RT_NOREF_PV(hThread);
+#if RTLNX_VER_MIN(2,5,4)
+    return !!test_tsk_thread_flag(current, TIF_NEED_RESCHED);
+
+#elif RTLNX_VER_MIN(2,4,20)
+    return !!need_resched();
+
+#elif RTLNX_VER_MIN(2,1,110)
+    return current->need_resched != 0;
+
+#else
+    return need_resched != 0;
+#endif
+}
+RT_EXPORT_SYMBOL(RTThreadPreemptIsPending);
+
+
+RTDECL(bool) RTThreadPreemptIsPendingTrusty(void)
+{
+    /* yes, RTThreadPreemptIsPending is reliable. */
+    return true;
+}
+RT_EXPORT_SYMBOL(RTThreadPreemptIsPendingTrusty);
+
+
+RTDECL(bool) RTThreadPreemptIsPossible(void)
+{
+#ifdef CONFIG_PREEMPT
+    return true;    /* Yes, kernel preemption is possible. */
+#else
+    return false;   /* No kernel preemption (or CONFIG_PREEMPT_VOLUNTARY). */
+#endif
+}
+RT_EXPORT_SYMBOL(RTThreadPreemptIsPossible);
+
+
+RTDECL(void) RTThreadPreemptDisable(PRTTHREADPREEMPTSTATE pState)
+{
+#ifdef CONFIG_PREEMPT
+    AssertPtr(pState);
+    Assert(pState->u32Reserved == 0);
+    pState->u32Reserved = 42;
+    /* This ASSUMES that CONFIG_PREEMPT_COUNT is always defined with CONFIG_PREEMPT. */
+    preempt_disable();
+    RT_ASSERT_PREEMPT_CPUID_DISABLE(pState);
+
+#else /* !CONFIG_PREEMPT */
+    int32_t c;
+    AssertPtr(pState);
+    Assert(pState->u32Reserved == 0);
+
+    /* Do our own accounting. */
+    c = ASMAtomicIncS32(&g_acPreemptDisabled[smp_processor_id()]);
+    AssertMsg(c > 0 && c < 32, ("%d\n", c));
+    pState->u32Reserved = c;
+    RT_ASSERT_PREEMPT_CPUID_DISABLE(pState);
+#endif
+}
+RT_EXPORT_SYMBOL(RTThreadPreemptDisable);
+
+
+RTDECL(void) RTThreadPreemptRestore(PRTTHREADPREEMPTSTATE pState)
+{
+#ifdef CONFIG_PREEMPT
+    IPRT_LINUX_SAVE_EFL_AC(); /* paranoia */
+    AssertPtr(pState);
+    Assert(pState->u32Reserved == 42);
+    RT_ASSERT_PREEMPT_CPUID_RESTORE(pState);
+    preempt_enable();
+    IPRT_LINUX_RESTORE_EFL_ONLY_AC();  /* paranoia */
+
+#else
+    int32_t volatile *pc;
+    AssertPtr(pState);
+    AssertMsg(pState->u32Reserved > 0 && pState->u32Reserved < 32, ("%d\n", pState->u32Reserved));
+    RT_ASSERT_PREEMPT_CPUID_RESTORE(pState);
+
+    /* Do our own accounting. */
+    pc = &g_acPreemptDisabled[smp_processor_id()];
+    AssertMsg(pState->u32Reserved == (uint32_t)*pc, ("u32Reserved=%d *pc=%d \n", pState->u32Reserved, *pc));
+    ASMAtomicUoWriteS32(pc, pState->u32Reserved - 1);
+#endif
+    pState->u32Reserved = 0;
+}
+RT_EXPORT_SYMBOL(RTThreadPreemptRestore);
+
+
+RTDECL(bool) RTThreadIsInInterrupt(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD); NOREF(hThread);
+
+    return in_interrupt() != 0;
+}
+RT_EXPORT_SYMBOL(RTThreadIsInInterrupt);
+
diff --git a/src/VBox/Runtime/r0drv/linux/thread2-r0drv-linux.c b/src/VBox/Runtime/r0drv/linux/thread2-r0drv-linux.c
new file mode 100644
index 00000000..cd01f32a
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/thread2-r0drv-linux.c
@@ -0,0 +1,233 @@
+/* $Id: thread2-r0drv-linux.c $ */
+/** @file
+ * IPRT - Threads (Part 2), Ring-0 Driver, Linux.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-linux-kernel.h"
+#include "internal/iprt.h"
+
+#include <iprt/assert.h>
+#include <iprt/thread.h>
+#include <iprt/errcore.h>
+#include "internal/thread.h"
+
+#if RTLNX_VER_MIN(4,11,0)
+    #include <uapi/linux/sched/types.h>
+#endif /* >= KERNEL_VERSION(4, 11, 0) */
+
+RTDECL(RTTHREAD) RTThreadSelf(void)
+{
+    return rtThreadGetByNative((RTNATIVETHREAD)current);
+}
+
+
+DECLHIDDEN(int) rtThreadNativeInit(void)
+{
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtThreadNativeSetPriority(PRTTHREADINT pThread, RTTHREADTYPE enmType)
+{
+#if RTLNX_VER_MIN(2,5,2)
+    /*
+     * Assignments are partially based on g_aTypesLinuxFree but
+     * scaled up in the high priority end.
+     *
+     * 5.9.0 - :
+     *      The sched_set_normal interfaces does not really check the input,
+     *      whereas sched_set_fifo & sched_set_fifo_low have fixed assignments.
+     * 2.6.11 - 5.9.0:
+     *      Use sched_setscheduler to try effect FIFO scheduling
+     *      for IO and TIMER threads, otherwise use set_user_nice.
+     * 2.5.2 - 5.9.0:
+     *      Use set_user_nice to renice the thread.
+     */
+    int                 iNice       = 0;
+# if RTLNX_VER_MAX(5,9,0)
+    int                 rc;
+#  if RTLNX_VER_MIN(2,6,11)
+    int                 iSchedClass = SCHED_NORMAL;
+    struct sched_param  Param       = { .sched_priority = 0 };
+#  endif
+# endif
+    switch (enmType)
+    {
+        case RTTHREADTYPE_INFREQUENT_POLLER:
+            iNice = +3;
+            break;
+
+        case RTTHREADTYPE_MAIN_HEAVY_WORKER:
+            iNice = +2;
+            break;
+
+        case RTTHREADTYPE_EMULATION:
+            iNice = +1;
+            break;
+
+        case RTTHREADTYPE_DEFAULT:
+        case RTTHREADTYPE_GUI:
+        case RTTHREADTYPE_MAIN_WORKER:
+            iNice =  0;
+            break;
+
+        case RTTHREADTYPE_VRDP_IO:
+        case RTTHREADTYPE_DEBUGGER:
+            iNice = -1;
+            break;
+
+        case RTTHREADTYPE_MSG_PUMP:
+            iNice = -2;
+            break;
+
+        case RTTHREADTYPE_IO:
+# if RTLNX_VER_MIN(5,9,0)
+            sched_set_fifo_low(current);
+            return VINF_SUCCESS;
+# else
+            iNice = -12;
+#  if RTLNX_VER_MIN(2,6,11)
+            iSchedClass = SCHED_FIFO;
+            Param.sched_priority = 1; /* => prio=98; */
+#  endif
+            break;
+# endif
+
+        case RTTHREADTYPE_TIMER:
+# if RTLNX_VER_MIN(5,9,0)
+            sched_set_fifo(current);
+            return VINF_SUCCESS;
+# else
+            iNice = -19;
+#  if RTLNX_VER_MIN(2,6,11)
+            iSchedClass = SCHED_FIFO;
+            Param.sched_priority = MAX_RT_PRIO / 2; /* => prio=49 */
+#  endif
+            break;
+# endif
+        default:
+            AssertMsgFailedReturn(("enmType=%d\n", enmType), VERR_INVALID_PARAMETER);
+    }
+
+# if RTLNX_VER_MIN(5,9,0)
+    /*
+     * We only get here for renice work.
+     */
+    sched_set_normal(current, iNice);
+
+# else  /* < 5.9.0 */
+#  if RTLNX_VER_MIN(2,6,11)
+    /*
+     * Try set scheduler parameters.
+     * Fall back on normal + nice if this fails for FIFO policy.*
+     */
+    rc = sched_setscheduler(current, iSchedClass, &Param);
+    if (rc)
+    {
+        Param.sched_priority = 0;
+        iSchedClass = SCHED_NORMAL;
+        rc = sched_setscheduler(current, iSchedClass, &Param);
+    }
+
+    /*
+     * Renice if using normal scheduling class.
+     */
+    if (iSchedClass == SCHED_NORMAL)
+#  endif /* >= 2.6.11 */
+        set_user_nice(current, iNice);
+
+# endif /* < 5.9.0 */
+#else  /* < 2.5.2 */
+    RT_NOREF_PV(enmType);
+#endif /* < 2.5.2 */
+    RT_NOREF_PV(pThread);
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtThreadNativeAdopt(PRTTHREADINT pThread)
+{
+    RT_NOREF_PV(pThread);
+    return VERR_NOT_IMPLEMENTED;
+}
+
+
+DECLHIDDEN(void) rtThreadNativeWaitKludge(PRTTHREADINT pThread)
+{
+    /** @todo fix RTThreadWait/RTR0Term race on linux. */
+    RTThreadSleep(1); NOREF(pThread);
+}
+
+
+DECLHIDDEN(void) rtThreadNativeDestroy(PRTTHREADINT pThread)
+{
+    NOREF(pThread);
+}
+
+
+#if RTLNX_VER_MIN(2,6,4)
+/**
+ * Native kernel thread wrapper function.
+ *
+ * This will forward to rtThreadMain and do termination upon return.
+ *
+ * @param pvArg         Pointer to the argument package.
+ */
+static int rtThreadNativeMain(void *pvArg)
+{
+    PRTTHREADINT pThread = (PRTTHREADINT)pvArg;
+
+    rtThreadMain(pThread, (RTNATIVETHREAD)current, &pThread->szName[0]);
+    return 0;
+}
+#endif
+
+
+DECLHIDDEN(int) rtThreadNativeCreate(PRTTHREADINT pThreadInt, PRTNATIVETHREAD pNativeThread)
+{
+#if RTLNX_VER_MIN(2,6,4)
+    struct task_struct *NativeThread;
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    RT_ASSERT_PREEMPTIBLE();
+
+    NativeThread = kthread_run(rtThreadNativeMain, pThreadInt, "iprt-%s", pThreadInt->szName);
+
+    if (!IS_ERR(NativeThread))
+    {
+        *pNativeThread = (RTNATIVETHREAD)NativeThread;
+        IPRT_LINUX_RESTORE_EFL_AC();
+        return VINF_SUCCESS;
+    }
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return VERR_GENERAL_FAILURE;
+#else
+    return VERR_NOT_IMPLEMENTED;
+#endif
+}
+
diff --git a/src/VBox/Runtime/r0drv/linux/threadctxhooks-r0drv-linux.c b/src/VBox/Runtime/r0drv/linux/threadctxhooks-r0drv-linux.c
new file mode 100644
index 00000000..089e2ca6
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/threadctxhooks-r0drv-linux.c
@@ -0,0 +1,330 @@
+/* $Id: threadctxhooks-r0drv-linux.c $ */
+/** @file
+ * IPRT - Thread Context Switching Hook, Ring-0 Driver, Linux.
+ */
+
+/*
+ * Copyright (C) 2013-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-linux-kernel.h"
+#include "internal/iprt.h"
+
+#include <iprt/mem.h>
+#include <iprt/assert.h>
+#include <iprt/thread.h>
+#include <iprt/errcore.h>
+#include <iprt/asm.h>
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include "internal/thread.h"
+
+
+/*
+ * Linux kernel 2.6.23 introduced preemption notifiers but RedHat 2.6.18 kernels
+ * got it backported.
+ */
+#if RTLNX_VER_MIN(2,6,18) && defined(CONFIG_PREEMPT_NOTIFIERS)
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * The internal hook object for linux.
+ */
+typedef struct RTTHREADCTXHOOKINT
+{
+    /** Magic value (RTTHREADCTXHOOKINT_MAGIC). */
+    uint32_t volatile           u32Magic;
+    /** The thread handle (owner) for which the hook is registered. */
+    RTNATIVETHREAD              hOwner;
+    /** The preemption notifier object. */
+    struct preempt_notifier     LnxPreemptNotifier;
+    /** Whether the hook is enabled or not.  If enabled, the LnxPreemptNotifier
+     * is linked into the owning thread's list of preemption callouts. */
+    bool                        fEnabled;
+    /** Pointer to the user callback. */
+    PFNRTTHREADCTXHOOK          pfnCallback;
+    /** User argument passed to the callback. */
+    void                       *pvUser;
+    /** The linux callbacks. */
+    struct preempt_ops          PreemptOps;
+#if RTLNX_VER_MIN(3,1,19) && defined(RT_ARCH_AMD64)
+    /** Starting with 3.1.19, the linux kernel doesn't restore kernel RFLAGS during
+     * task switch, so we have to do that ourselves. (x86 code is not affected.) */
+    RTCCUINTREG                 fSavedRFlags;
+#endif
+} RTTHREADCTXHOOKINT;
+typedef RTTHREADCTXHOOKINT *PRTTHREADCTXHOOKINT;
+
+
+/**
+ * Hook function for the thread schedule out event.
+ *
+ * @param   pPreemptNotifier    Pointer to the preempt_notifier struct.
+ * @param   pNext               Pointer to the task that is being scheduled
+ *                              instead of the current thread.
+ *
+ * @remarks Called with the rq (runqueue) lock held and with preemption and
+ *          interrupts disabled!
+ */
+static void rtThreadCtxHooksLnxSchedOut(struct preempt_notifier *pPreemptNotifier, struct task_struct *pNext)
+{
+    PRTTHREADCTXHOOKINT pThis = RT_FROM_MEMBER(pPreemptNotifier, RTTHREADCTXHOOKINT, LnxPreemptNotifier);
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+    RTCCUINTREG fSavedEFlags = ASMGetFlags();
+    stac();
+#endif
+    RT_NOREF_PV(pNext);
+
+    AssertPtr(pThis);
+    AssertPtr(pThis->pfnCallback);
+    Assert(pThis->fEnabled);
+    Assert(!RTThreadPreemptIsEnabled(NIL_RTTHREAD));
+
+    pThis->pfnCallback(RTTHREADCTXEVENT_OUT, pThis->pvUser);
+
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+    ASMSetFlags(fSavedEFlags);
+# if RTLNX_VER_MIN(3,1,19) && defined(RT_ARCH_AMD64)
+    pThis->fSavedRFlags = fSavedEFlags;
+# endif
+#endif
+}
+
+
+/**
+ * Hook function for the thread schedule in event.
+ *
+ * @param   pPreemptNotifier    Pointer to the preempt_notifier struct.
+ * @param   iCpu                The CPU this thread is being scheduled on.
+ *
+ * @remarks Called without holding the rq (runqueue) lock and with preemption
+ *          enabled!
+ * @todo    r=bird: Preemption is of course disabled when it is called.
+ */
+static void rtThreadCtxHooksLnxSchedIn(struct preempt_notifier *pPreemptNotifier, int iCpu)
+{
+    PRTTHREADCTXHOOKINT pThis = RT_FROM_MEMBER(pPreemptNotifier, RTTHREADCTXHOOKINT, LnxPreemptNotifier);
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+    RTCCUINTREG fSavedEFlags = ASMGetFlags();
+    stac();
+#endif
+    RT_NOREF_PV(iCpu);
+
+    AssertPtr(pThis);
+    AssertPtr(pThis->pfnCallback);
+    Assert(pThis->fEnabled);
+
+    pThis->pfnCallback(RTTHREADCTXEVENT_IN, pThis->pvUser);
+
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# if RTLNX_VER_MIN(3,1,19) && defined(RT_ARCH_AMD64)
+    fSavedEFlags &= ~RT_BIT_64(18) /*X86_EFL_AC*/;
+    fSavedEFlags |= pThis->fSavedRFlags & RT_BIT_64(18) /*X86_EFL_AC*/;
+# endif
+    ASMSetFlags(fSavedEFlags);
+#endif
+}
+
+
+/**
+ * Worker function for RTThreadCtxHooks(Deregister|Release)().
+ *
+ * @param   pThis   Pointer to the internal thread-context object.
+ */
+DECLINLINE(void) rtThreadCtxHookDisable(PRTTHREADCTXHOOKINT pThis)
+{
+    Assert(pThis->PreemptOps.sched_out == rtThreadCtxHooksLnxSchedOut);
+    Assert(pThis->PreemptOps.sched_in  == rtThreadCtxHooksLnxSchedIn);
+    preempt_disable();
+    preempt_notifier_unregister(&pThis->LnxPreemptNotifier);
+    pThis->fEnabled = false;
+    preempt_enable();
+}
+
+
+RTDECL(int) RTThreadCtxHookCreate(PRTTHREADCTXHOOK phCtxHook, uint32_t fFlags, PFNRTTHREADCTXHOOK pfnCallback, void *pvUser)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    /*
+     * Validate input.
+     */
+    PRTTHREADCTXHOOKINT pThis;
+    Assert(RTThreadPreemptIsEnabled(NIL_RTTHREAD));
+    AssertPtrReturn(pfnCallback, VERR_INVALID_POINTER);
+    AssertReturn(fFlags == 0, VERR_INVALID_FLAGS);
+
+    /*
+     * Allocate and initialize a new hook.  We don't register it yet, just
+     * create it.
+     */
+    pThis = (PRTTHREADCTXHOOKINT)RTMemAllocZ(sizeof(*pThis));
+    if (RT_UNLIKELY(!pThis))
+    {
+        IPRT_LINUX_RESTORE_EFL_AC();
+        return VERR_NO_MEMORY;
+    }
+    pThis->u32Magic     = RTTHREADCTXHOOKINT_MAGIC;
+    pThis->hOwner       = RTThreadNativeSelf();
+    pThis->fEnabled     = false;
+    pThis->pfnCallback  = pfnCallback;
+    pThis->pvUser       = pvUser;
+    preempt_notifier_init(&pThis->LnxPreemptNotifier, &pThis->PreemptOps);
+    pThis->PreemptOps.sched_out = rtThreadCtxHooksLnxSchedOut;
+    pThis->PreemptOps.sched_in  = rtThreadCtxHooksLnxSchedIn;
+
+#if RTLNX_VER_MIN(4,2,0)
+    preempt_notifier_inc();
+#endif
+
+    *phCtxHook = pThis;
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTThreadCtxHookCreate);
+
+
+RTDECL(int ) RTThreadCtxHookDestroy(RTTHREADCTXHOOK hCtxHook)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    /*
+     * Validate input.
+     */
+    PRTTHREADCTXHOOKINT pThis = hCtxHook;
+    if (pThis == NIL_RTTHREADCTXHOOK)
+        return VINF_SUCCESS;
+    AssertPtr(pThis);
+    AssertMsgReturn(pThis->u32Magic == RTTHREADCTXHOOKINT_MAGIC, ("pThis->u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis),
+                    VERR_INVALID_HANDLE);
+    Assert(RTThreadPreemptIsEnabled(NIL_RTTHREAD));
+    Assert(!pThis->fEnabled || pThis->hOwner == RTThreadNativeSelf());
+
+    /*
+     * If there's still a registered thread-context hook, deregister it now before destroying the object.
+     */
+    if (pThis->fEnabled)
+    {
+        Assert(pThis->hOwner == RTThreadNativeSelf());
+        rtThreadCtxHookDisable(pThis);
+        Assert(!pThis->fEnabled); /* paranoia */
+    }
+
+#if RTLNX_VER_MIN(4,2,0)
+    preempt_notifier_dec();
+#endif
+
+    ASMAtomicWriteU32(&pThis->u32Magic, ~RTTHREADCTXHOOKINT_MAGIC);
+    RTMemFree(pThis);
+
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTThreadCtxHookDestroy);
+
+
+RTDECL(int) RTThreadCtxHookEnable(RTTHREADCTXHOOK hCtxHook)
+{
+    /*
+     * Validate input.
+     */
+    PRTTHREADCTXHOOKINT pThis = hCtxHook;
+    AssertPtr(pThis);
+    AssertMsgReturn(pThis->u32Magic == RTTHREADCTXHOOKINT_MAGIC, ("pThis->u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis),
+                    VERR_INVALID_HANDLE);
+    Assert(pThis->hOwner == RTThreadNativeSelf());
+    Assert(!pThis->fEnabled);
+    if (!pThis->fEnabled)
+    {
+        IPRT_LINUX_SAVE_EFL_AC();
+        Assert(pThis->PreemptOps.sched_out == rtThreadCtxHooksLnxSchedOut);
+        Assert(pThis->PreemptOps.sched_in == rtThreadCtxHooksLnxSchedIn);
+
+        /*
+         * Register the callback.
+         */
+        preempt_disable();
+        pThis->fEnabled = true;
+        preempt_notifier_register(&pThis->LnxPreemptNotifier);
+        preempt_enable();
+
+        IPRT_LINUX_RESTORE_EFL_AC();
+    }
+
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTThreadCtxHookEnable);
+
+
+RTDECL(int) RTThreadCtxHookDisable(RTTHREADCTXHOOK hCtxHook)
+{
+    /*
+     * Validate input.
+     */
+    PRTTHREADCTXHOOKINT pThis = hCtxHook;
+    if (pThis != NIL_RTTHREADCTXHOOK)
+    {
+        AssertPtr(pThis);
+        AssertMsgReturn(pThis->u32Magic == RTTHREADCTXHOOKINT_MAGIC, ("pThis->u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis),
+                        VERR_INVALID_HANDLE);
+        Assert(pThis->hOwner == RTThreadNativeSelf());
+
+        /*
+         * Deregister the callback.
+         */
+        if (pThis->fEnabled)
+        {
+            IPRT_LINUX_SAVE_EFL_AC();
+            rtThreadCtxHookDisable(pThis);
+            IPRT_LINUX_RESTORE_EFL_AC();
+        }
+    }
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTThreadCtxHookDisable);
+
+
+RTDECL(bool) RTThreadCtxHookIsEnabled(RTTHREADCTXHOOK hCtxHook)
+{
+    /*
+     * Validate input.
+     */
+    PRTTHREADCTXHOOKINT pThis = hCtxHook;
+    if (pThis == NIL_RTTHREADCTXHOOK)
+        return false;
+    AssertPtr(pThis);
+    AssertMsgReturn(pThis->u32Magic == RTTHREADCTXHOOKINT_MAGIC, ("pThis->u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis),
+                    false);
+
+    return pThis->fEnabled;
+}
+
+#else    /* Not supported / Not needed */
+# include "../generic/threadctxhooks-r0drv-generic.cpp"
+#endif   /* Not supported / Not needed */
+
diff --git a/src/VBox/Runtime/r0drv/linux/time-r0drv-linux.c b/src/VBox/Runtime/r0drv/linux/time-r0drv-linux.c
new file mode 100644
index 00000000..c72a4e6d
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/time-r0drv-linux.c
@@ -0,0 +1,211 @@
+/* $Id: time-r0drv-linux.c $ */
+/** @file
+ * IPRT - Time, Ring-0 Driver, Linux.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define LOG_GROUP RTLOGGROUP_TIME
+#include "the-linux-kernel.h"
+#include "internal/iprt.h"
+/* Make sure we have the setting functions we need for RTTimeNow: */
+#if RTLNX_VER_MAX(2,6,16)
+# define RTTIME_INCL_TIMEVAL
+#elif RTLNX_VER_MAX(3,17,0)
+# define RTTIME_INCL_TIMESPEC
+#endif
+#include <iprt/time.h>
+#include <iprt/asm.h>
+
+
+
+DECLINLINE(uint64_t) rtTimeGetSystemNanoTS(void)
+{
+#if RTLNX_VER_MIN(5,6,0)
+    /*
+     * Starting with kernel version 5.6-rc3 only 64-bit time interfaces
+     * are allowed in the kernel.
+     */
+    uint64_t u64;
+    struct timespec64 Ts = { 0, 0 };
+
+    ktime_get_ts64(&Ts);
+    u64 = Ts.tv_sec * RT_NS_1SEC_64 + Ts.tv_nsec;
+    return u64;
+
+#elif RTLNX_VER_MIN(2,6,16) /* This must match timer-r0drv-linux.c! */
+    /*
+     * Use ktime_get_ts, this is also what clock_gettime(CLOCK_MONOTONIC,) is using.
+     */
+    uint64_t u64;
+    struct timespec Ts = { 0, 0 };
+    ktime_get_ts(&Ts);
+    u64 = Ts.tv_sec * RT_NS_1SEC_64 + Ts.tv_nsec;
+    return u64;
+
+#elif RTLNX_VER_MIN(2,5,60)
+    /*
+     * Seems there is no way of getting to the exact source of
+     * sys_clock_gettime(CLOCK_MONOTONIC, &ts) here, I think. But
+     * 64-bit jiffies adjusted for the initial value should be pretty
+     * much the same I hope.
+     */
+    uint64_t u64 = get_jiffies_64();
+# ifdef INITIAL_JIFFIES
+    u64 += INITIAL_JIFFIES;
+# endif
+    u64 *= TICK_NSEC;
+    return u64;
+
+#else   /* < 2.5.60 */
+# if BITS_PER_LONG >= 64
+    /*
+     * This is the same as above, except that there is no get_jiffies_64()
+     * here and we rely on long, and therefor jiffies, being 64-bit instead.
+     */
+    uint64_t u64 = jiffies;
+# ifdef INITIAL_JIFFIES
+    u64 += INITIAL_JIFFIES;
+# endif
+    u64 *= TICK_NSEC;
+    return u64;
+
+# else /* 32 bit jiffies */
+    /*
+     * We'll have to try track jiffy rollovers here or we'll be
+     * in trouble every time it flips.
+     *
+     * The high dword of the s_u64Last is the rollover count, the
+     * low dword is the previous jiffies.  Updating is done by
+     * atomic compare & exchange of course.
+     */
+    static uint64_t volatile s_u64Last = 0;
+    uint64_t u64;
+
+    for (;;)
+    {
+        uint64_t u64NewLast;
+        int32_t iDelta;
+        uint32_t cRollovers;
+        uint32_t u32LastJiffies;
+
+        /* sample the values */
+        unsigned long ulNow = jiffies;
+        uint64_t u64Last = s_u64Last;
+        if (ulNow != jiffies)
+            continue; /* try again */
+#  ifdef INITIAL_JIFFIES
+        ulNow += INITIAL_JIFFIES;
+#  endif
+
+        u32LastJiffies = (uint32_t)u64Last;
+        cRollovers = u64Last >> 32;
+
+        /*
+         * Check for rollover and update the static last value.
+         *
+         * We have to make sure we update it successfully to rule out
+         * an underrun because of racing someone.
+         */
+        iDelta = ulNow - u32LastJiffies;
+        if (iDelta < 0)
+        {
+            cRollovers++;
+            u64NewLast = RT_MAKE_U64(ulNow, cRollovers);
+            if (!ASMAtomicCmpXchgU64(&s_u64Last, u64NewLast, u64Last))
+                continue; /* race, try again */
+        }
+        else
+        {
+            u64NewLast = RT_MAKE_U64(ulNow, cRollovers);
+            ASMAtomicCmpXchgU64(&s_u64Last, u64NewLast, u64Last);
+        }
+
+        /* calculate the return value */
+        u64 = ulNow;
+        u64 *= TICK_NSEC;
+        u64 += cRollovers * (_4G * TICK_NSEC);
+        break;
+    }
+
+    return u64;
+# endif /* 32 bit jiffies */
+#endif  /* < 2.5.60 */
+}
+
+
+RTDECL(uint64_t) RTTimeNanoTS(void)
+{
+    return rtTimeGetSystemNanoTS();
+}
+RT_EXPORT_SYMBOL(RTTimeNanoTS);
+
+
+RTDECL(uint64_t) RTTimeMilliTS(void)
+{
+    return rtTimeGetSystemNanoTS() / RT_NS_1MS;
+}
+RT_EXPORT_SYMBOL(RTTimeMilliTS);
+
+
+RTDECL(uint64_t) RTTimeSystemNanoTS(void)
+{
+    return rtTimeGetSystemNanoTS();
+}
+RT_EXPORT_SYMBOL(RTTimeSystemNanoTS);
+
+
+RTDECL(uint64_t) RTTimeSystemMilliTS(void)
+{
+    return rtTimeGetSystemNanoTS() / RT_NS_1MS;
+}
+RT_EXPORT_SYMBOL(RTTimeSystemMilliTS);
+
+
+RTDECL(PRTTIMESPEC) RTTimeNow(PRTTIMESPEC pTime)
+{
+    IPRT_LINUX_SAVE_EFL_AC();
+#if RTLNX_VER_MIN(3,17,0)
+    struct timespec64 Ts;
+    ktime_get_real_ts64(&Ts);   /* ktime_get_real_ts64 was added as a macro in 3.17, function since 4.18. */
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return RTTimeSpecSetTimespec64(pTime, &Ts);
+
+#elif RTLNX_VER_MIN(2,6,16)
+    struct timespec Ts;
+    ktime_get_real_ts(&Ts);     /* ktime_get_real_ts was removed in Linux 4.20. */
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return RTTimeSpecSetTimespec(pTime, &Ts);
+
+#else /* < 2.6.16 */
+    struct timeval Tv;
+    do_gettimeofday(&Tv);
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return RTTimeSpecSetTimeval(pTime, &Tv);
+#endif
+}
+RT_EXPORT_SYMBOL(RTTimeNow);
+
diff --git a/src/VBox/Runtime/r0drv/linux/timer-r0drv-linux.c b/src/VBox/Runtime/r0drv/linux/timer-r0drv-linux.c
new file mode 100644
index 00000000..8d70c1ab
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/timer-r0drv-linux.c
@@ -0,0 +1,1727 @@
+/* $Id: timer-r0drv-linux.c $ */
+/** @file
+ * IPRT - Timers, Ring-0 Driver, Linux.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-linux-kernel.h"
+#include "internal/iprt.h"
+
+#include <iprt/timer.h>
+#include <iprt/time.h>
+#include <iprt/mp.h>
+#include <iprt/cpuset.h>
+#include <iprt/spinlock.h>
+#include <iprt/err.h>
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/alloc.h>
+
+#include "internal/magics.h"
+
+/** @def RTTIMER_LINUX_WITH_HRTIMER
+ * Whether to use high resolution timers.  */
+#if !defined(RTTIMER_LINUX_WITH_HRTIMER) \
+    && defined(IPRT_LINUX_HAS_HRTIMER)
+# define RTTIMER_LINUX_WITH_HRTIMER
+#endif
+
+#if RTLNX_VER_MAX(2,6,31)
+# define mod_timer_pinned               mod_timer
+# define HRTIMER_MODE_ABS_PINNED        HRTIMER_MODE_ABS
+#endif
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Timer state machine.
+ *
+ * This is used to try handle the issues with MP events and
+ * timers that runs on all CPUs. It's relatively nasty :-/
+ */
+typedef enum RTTIMERLNXSTATE
+{
+    /** Stopped. */
+    RTTIMERLNXSTATE_STOPPED = 0,
+    /** Transient state; next ACTIVE. */
+    RTTIMERLNXSTATE_STARTING,
+    /** Transient state; next ACTIVE. (not really necessary) */
+    RTTIMERLNXSTATE_MP_STARTING,
+    /** Active. */
+    RTTIMERLNXSTATE_ACTIVE,
+    /** Active and in callback; next ACTIVE, STOPPED or CALLBACK_DESTROYING. */
+    RTTIMERLNXSTATE_CALLBACK,
+    /** Stopped while in the callback; next STOPPED. */
+    RTTIMERLNXSTATE_CB_STOPPING,
+    /** Restarted while in the callback; next ACTIVE, STOPPED, DESTROYING. */
+    RTTIMERLNXSTATE_CB_RESTARTING,
+    /** The callback shall destroy the timer; next STOPPED. */
+    RTTIMERLNXSTATE_CB_DESTROYING,
+    /** Transient state; next STOPPED. */
+    RTTIMERLNXSTATE_STOPPING,
+    /** Transient state; next STOPPED. */
+    RTTIMERLNXSTATE_MP_STOPPING,
+    /** The usual 32-bit hack. */
+    RTTIMERLNXSTATE_32BIT_HACK = 0x7fffffff
+} RTTIMERLNXSTATE;
+
+
+/**
+ * A Linux sub-timer.
+ */
+typedef struct RTTIMERLNXSUBTIMER
+{
+    /** Timer specific data.  */
+    union
+    {
+#if defined(RTTIMER_LINUX_WITH_HRTIMER)
+        /** High resolution timer. */
+        struct
+        {
+            /** The linux timer structure. */
+            struct hrtimer          LnxTimer;
+        } Hr;
+#endif
+        /** Standard timer. */
+        struct
+        {
+            /** The linux timer structure. */
+            struct timer_list       LnxTimer;
+            /** The start of the current run (ns).
+             * This is used to calculate when the timer ought to fire the next time. */
+            uint64_t                u64NextTS;
+            /** When the timer was started. */
+            uint64_t                nsStartTS;
+            /** The u64NextTS in jiffies. */
+            unsigned long           ulNextJiffies;
+            /** Set when starting or changing the timer so that u64StartTs
+             *  and u64NextTS gets reinitialized (eliminating some jitter). */
+            bool volatile           fFirstAfterChg;
+        } Std;
+    } u;
+    /** The current tick number. */
+    uint64_t                iTick;
+    /** Restart the single shot timer at this specific time.
+     * Used when a single shot timer is restarted from the callback. */
+    uint64_t volatile       uNsRestartAt;
+    /** Pointer to the parent timer. */
+    PRTTIMER                pParent;
+    /** The current sub-timer state. */
+    RTTIMERLNXSTATE volatile enmState;
+} RTTIMERLNXSUBTIMER;
+/** Pointer to a linux sub-timer. */
+typedef RTTIMERLNXSUBTIMER *PRTTIMERLNXSUBTIMER;
+
+
+/**
+ * The internal representation of an Linux timer handle.
+ */
+typedef struct RTTIMER
+{
+    /** Magic.
+     * This is RTTIMER_MAGIC, but changes to something else before the timer
+     * is destroyed to indicate clearly that thread should exit. */
+    uint32_t volatile       u32Magic;
+    /** Spinlock synchronizing the fSuspended and MP event handling.
+     * This is NIL_RTSPINLOCK if cCpus == 1. */
+    RTSPINLOCK              hSpinlock;
+    /** Flag indicating that the timer is suspended. */
+    bool volatile           fSuspended;
+    /** Whether the timer must run on one specific CPU or not. */
+    bool                    fSpecificCpu;
+#ifdef CONFIG_SMP
+    /** Whether the timer must run on all CPUs or not. */
+    bool                    fAllCpus;
+#endif /* else: All -> specific on non-SMP kernels */
+    /** Whether it is a high resolution timer or a standard one. */
+    bool                    fHighRes;
+    /** The id of the CPU it must run on if fSpecificCpu is set. */
+    RTCPUID                 idCpu;
+    /** The number of CPUs this timer should run on. */
+    RTCPUID                 cCpus;
+    /** Callback. */
+    PFNRTTIMER              pfnTimer;
+    /** User argument. */
+    void                   *pvUser;
+    /** The timer interval. 0 if one-shot. */
+    uint64_t volatile       u64NanoInterval;
+    /** This is set to the number of jiffies between ticks if the interval is
+     * an exact number of jiffies. (Standard timers only.) */
+    unsigned long volatile  cJiffies;
+    /** The change interval spinlock for standard timers only. */
+    spinlock_t              ChgIntLock;
+    /** Workqueue item for delayed destruction. */
+    RTR0LNXWORKQUEUEITEM    DtorWorkqueueItem;
+    /** Sub-timers.
+     * Normally there is just one, but for RTTIMER_FLAGS_CPU_ALL this will contain
+     * an entry for all possible cpus. In that case the index will be the same as
+     * for the RTCpuSet. */
+    RTTIMERLNXSUBTIMER      aSubTimers[1];
+} RTTIMER;
+
+
+/**
+ * A rtTimerLinuxStartOnCpu and rtTimerLinuxStartOnCpu argument package.
+ */
+typedef struct RTTIMERLINUXSTARTONCPUARGS
+{
+    /** The current time (RTTimeSystemNanoTS). */
+    uint64_t                u64Now;
+    /** When to start firing (delta). */
+    uint64_t                u64First;
+} RTTIMERLINUXSTARTONCPUARGS;
+/** Pointer to a rtTimerLinuxStartOnCpu argument package. */
+typedef RTTIMERLINUXSTARTONCPUARGS *PRTTIMERLINUXSTARTONCPUARGS;
+
+
+/*********************************************************************************************************************************
+*   Internal Functions                                                                                                           *
+*********************************************************************************************************************************/
+#ifdef CONFIG_SMP
+static DECLCALLBACK(void) rtTimerLinuxMpEvent(RTMPEVENT enmEvent, RTCPUID idCpu, void *pvUser);
+#endif
+
+#if 0
+#define DEBUG_HACKING
+#include <iprt/string.h>
+#include <iprt/asm-amd64-x86.h>
+static void myLogBackdoorPrintf(const char *pszFormat, ...)
+{
+    char        szTmp[256];
+    va_list     args;
+    size_t      cb;
+
+    cb = RTStrPrintf(szTmp, sizeof(szTmp) - 10, "%d: ", RTMpCpuId());
+    va_start(args, pszFormat);
+    cb += RTStrPrintfV(&szTmp[cb], sizeof(szTmp) - cb, pszFormat, args);
+    va_end(args);
+
+    ASMOutStrU8(0x504, (uint8_t *)&szTmp[0], cb);
+}
+# define RTAssertMsg1Weak(pszExpr, uLine, pszFile, pszFunction) \
+    myLogBackdoorPrintf("\n!!Guest Assertion failed!!\n%s(%d) %s\n%s\n", uLine, pszFile, pszFunction, (pszExpr))
+# define RTAssertMsg2Weak myLogBackdoorPrintf
+# define RTTIMERLNX_LOG(a)          myLogBackdoorPrintf a
+#else
+# define RTTIMERLNX_LOG(a)          do { } while (0)
+#endif
+
+/**
+ * Sets the state.
+ */
+DECLINLINE(void) rtTimerLnxSetState(RTTIMERLNXSTATE volatile *penmState, RTTIMERLNXSTATE enmNewState)
+{
+#ifdef DEBUG_HACKING
+    RTTIMERLNX_LOG(("set %d -> %d\n", *penmState, enmNewState));
+#endif
+    ASMAtomicWriteU32((uint32_t volatile *)penmState, enmNewState);
+}
+
+
+/**
+ * Sets the state if it has a certain value.
+ *
+ * @return true if xchg was done.
+ * @return false if xchg wasn't done.
+ */
+#ifdef DEBUG_HACKING
+#define rtTimerLnxCmpXchgState(penmState, enmNewState, enmCurState) rtTimerLnxCmpXchgStateDebug(penmState, enmNewState, enmCurState, __LINE__)
+static bool rtTimerLnxCmpXchgStateDebug(RTTIMERLNXSTATE volatile *penmState, RTTIMERLNXSTATE enmNewState,
+                                        RTTIMERLNXSTATE enmCurState, uint32_t uLine)
+{
+    RTTIMERLNXSTATE enmOldState = enmCurState;
+    bool fRc = ASMAtomicCmpXchgExU32((uint32_t volatile *)penmState, enmNewState, enmCurState, (uint32_t *)&enmOldState);
+    RTTIMERLNX_LOG(("cxg %d -> %d - %d at %u\n", enmOldState, enmNewState, fRc, uLine));
+    return fRc;
+}
+#else
+DECLINLINE(bool) rtTimerLnxCmpXchgState(RTTIMERLNXSTATE volatile *penmState, RTTIMERLNXSTATE enmNewState,
+                                        RTTIMERLNXSTATE enmCurState)
+{
+    return ASMAtomicCmpXchgU32((uint32_t volatile *)penmState, enmNewState, enmCurState);
+}
+#endif
+
+
+/**
+ * Gets the state.
+ */
+DECLINLINE(RTTIMERLNXSTATE) rtTimerLnxGetState(RTTIMERLNXSTATE volatile *penmState)
+{
+    return (RTTIMERLNXSTATE)ASMAtomicUoReadU32((uint32_t volatile *)penmState);
+}
+
+#ifdef RTTIMER_LINUX_WITH_HRTIMER
+
+/**
+ * Converts a nano second time stamp to ktime_t.
+ *
+ * ASSUMES RTTimeSystemNanoTS() is implemented using ktime_get_ts().
+ *
+ * @returns ktime_t.
+ * @param   cNanoSecs   Nanoseconds.
+ */
+DECLINLINE(ktime_t) rtTimerLnxNanoToKt(uint64_t cNanoSecs)
+{
+    /* With some luck the compiler optimizes the division out of this... (Bet it doesn't.) */
+    return ktime_set(cNanoSecs / 1000000000, cNanoSecs % 1000000000);
+}
+
+/**
+ * Converts ktime_t to a nano second time stamp.
+ *
+ * ASSUMES RTTimeSystemNanoTS() is implemented using ktime_get_ts().
+ *
+ * @returns nano second time stamp.
+ * @param   Kt          ktime_t.
+ */
+DECLINLINE(uint64_t) rtTimerLnxKtToNano(ktime_t Kt)
+{
+    return ktime_to_ns(Kt);
+}
+
+#endif /* RTTIMER_LINUX_WITH_HRTIMER */
+
+/**
+ * Converts a nano second interval to jiffies.
+ *
+ * @returns Jiffies.
+ * @param   cNanoSecs   Nanoseconds.
+ */
+DECLINLINE(unsigned long) rtTimerLnxNanoToJiffies(uint64_t cNanoSecs)
+{
+    /* this can be made even better... */
+    if (cNanoSecs > (uint64_t)TICK_NSEC * MAX_JIFFY_OFFSET)
+        return MAX_JIFFY_OFFSET;
+# if ARCH_BITS == 32
+    if (RT_LIKELY(cNanoSecs <= UINT32_MAX))
+        return ((uint32_t)cNanoSecs + (TICK_NSEC-1)) / TICK_NSEC;
+# endif
+    return (cNanoSecs + (TICK_NSEC-1)) / TICK_NSEC;
+}
+
+
+/**
+ * Starts a sub-timer (RTTimerStart).
+ *
+ * @param   pSubTimer   The sub-timer to start.
+ * @param   u64Now      The current timestamp (RTTimeSystemNanoTS()).
+ * @param   u64First    The interval from u64Now to the first time the timer should fire.
+ * @param   fPinned     true = timer pinned to a specific CPU,
+ *                      false = timer can migrate between CPUs
+ * @param   fHighRes    Whether the user requested a high resolution timer or not.
+ * @param   enmOldState The old timer state.
+ */
+static void rtTimerLnxStartSubTimer(PRTTIMERLNXSUBTIMER pSubTimer, uint64_t u64Now, uint64_t u64First,
+                                    bool fPinned, bool fHighRes)
+{
+    /*
+     * Calc when it should start firing.
+     */
+    uint64_t u64NextTS = u64Now + u64First;
+    if (!fHighRes)
+    {
+        pSubTimer->u.Std.u64NextTS = u64NextTS;
+        pSubTimer->u.Std.nsStartTS = u64NextTS;
+    }
+    RTTIMERLNX_LOG(("startsubtimer %p\n", pSubTimer->pParent));
+
+    pSubTimer->iTick = 0;
+
+#ifdef RTTIMER_LINUX_WITH_HRTIMER
+    if (fHighRes)
+        hrtimer_start(&pSubTimer->u.Hr.LnxTimer, rtTimerLnxNanoToKt(u64NextTS),
+                      fPinned ? HRTIMER_MODE_ABS_PINNED : HRTIMER_MODE_ABS);
+    else
+#endif
+    {
+        unsigned long cJiffies = !u64First ? 0 : rtTimerLnxNanoToJiffies(u64First);
+        pSubTimer->u.Std.ulNextJiffies  = jiffies + cJiffies;
+        pSubTimer->u.Std.fFirstAfterChg = true;
+#ifdef CONFIG_SMP
+        if (fPinned)
+        {
+# if RTLNX_VER_MIN(4,8,0)
+            mod_timer(&pSubTimer->u.Std.LnxTimer, pSubTimer->u.Std.ulNextJiffies);
+# else
+            mod_timer_pinned(&pSubTimer->u.Std.LnxTimer, pSubTimer->u.Std.ulNextJiffies);
+# endif
+        }
+        else
+#endif
+            mod_timer(&pSubTimer->u.Std.LnxTimer, pSubTimer->u.Std.ulNextJiffies);
+    }
+
+    /* Be a bit careful here since we could be racing the callback. */
+    if (!rtTimerLnxCmpXchgState(&pSubTimer->enmState, RTTIMERLNXSTATE_ACTIVE, RTTIMERLNXSTATE_STARTING))
+        rtTimerLnxCmpXchgState(&pSubTimer->enmState, RTTIMERLNXSTATE_ACTIVE, RTTIMERLNXSTATE_MP_STARTING);
+}
+
+
+/**
+ * Stops a sub-timer (RTTimerStart and rtTimerLinuxMpEvent()).
+ *
+ * The caller has already changed the state, so we will not be in a callback
+ * situation wrt to the calling thread.
+ *
+ * @param   pSubTimer   The sub-timer.
+ * @param   fHighRes    Whether the user requested a high resolution timer or not.
+ */
+static void rtTimerLnxStopSubTimer(PRTTIMERLNXSUBTIMER pSubTimer, bool fHighRes)
+{
+    RTTIMERLNX_LOG(("stopsubtimer %p %d\n", pSubTimer->pParent, fHighRes));
+#ifdef RTTIMER_LINUX_WITH_HRTIMER
+    if (fHighRes)
+    {
+        /* There is no equivalent to del_timer in the hrtimer API,
+           hrtimer_cancel() == del_timer_sync().  Just like the WARN_ON in
+           del_timer_sync() asserts, waiting for a timer callback to complete
+           is deadlock prone, so don't do it.  */
+        int rc = hrtimer_try_to_cancel(&pSubTimer->u.Hr.LnxTimer);
+        if (rc < 0)
+        {
+            hrtimer_start(&pSubTimer->u.Hr.LnxTimer, ktime_set(KTIME_SEC_MAX, 0), HRTIMER_MODE_ABS);
+            hrtimer_try_to_cancel(&pSubTimer->u.Hr.LnxTimer);
+        }
+    }
+    else
+#endif
+        del_timer(&pSubTimer->u.Std.LnxTimer);
+
+    rtTimerLnxSetState(&pSubTimer->enmState, RTTIMERLNXSTATE_STOPPED);
+}
+
+
+/**
+ * Used by RTTimerDestroy and rtTimerLnxCallbackDestroy to do the actual work.
+ *
+ * @param   pTimer  The timer in question.
+ */
+static void rtTimerLnxDestroyIt(PRTTIMER pTimer)
+{
+    RTSPINLOCK  hSpinlock = pTimer->hSpinlock;
+    RTCPUID     iCpu;
+    Assert(pTimer->fSuspended);
+    RTTIMERLNX_LOG(("destroyit %p\n", pTimer));
+
+    /*
+     * Remove the MP notifications first because it'll reduce the risk of
+     * us overtaking any MP event that might theoretically be racing us here.
+     */
+#ifdef CONFIG_SMP
+    if (    pTimer->cCpus > 1
+        &&  hSpinlock != NIL_RTSPINLOCK)
+    {
+        int rc = RTMpNotificationDeregister(rtTimerLinuxMpEvent, pTimer);
+        AssertRC(rc);
+    }
+#endif /* CONFIG_SMP */
+
+    /*
+     * Invalidate the handle.
+     */
+    ASMAtomicWriteU32(&pTimer->u32Magic, ~RTTIMER_MAGIC);
+
+    /*
+     * Make sure all timers have stopped executing since we're stopping them in
+     * an asynchronous manner up in rtTimerLnxStopSubTimer.
+     */
+    iCpu = pTimer->cCpus;
+    while (iCpu-- > 0)
+    {
+#ifdef RTTIMER_LINUX_WITH_HRTIMER
+        if (pTimer->fHighRes)
+            hrtimer_cancel(&pTimer->aSubTimers[iCpu].u.Hr.LnxTimer);
+        else
+#endif
+            del_timer_sync(&pTimer->aSubTimers[iCpu].u.Std.LnxTimer);
+    }
+
+    /*
+     * Finally, free the resources.
+     */
+    RTMemFreeEx(pTimer, RT_UOFFSETOF_DYN(RTTIMER, aSubTimers[pTimer->cCpus]));
+    if (hSpinlock != NIL_RTSPINLOCK)
+        RTSpinlockDestroy(hSpinlock);
+}
+
+
+/**
+ * Workqueue callback (no DECLCALLBACK!) for deferred destruction.
+ *
+ * @param   pWork        Pointer to the DtorWorkqueueItem member of our timer
+ *                       structure.
+ */
+static void rtTimerLnxDestroyDeferred(RTR0LNXWORKQUEUEITEM *pWork)
+{
+    PRTTIMER pTimer = RT_FROM_MEMBER(pWork, RTTIMER, DtorWorkqueueItem);
+    rtTimerLnxDestroyIt(pTimer);
+}
+
+
+/**
+ * Called when the timer was destroyed by the callback function.
+ *
+ * @param   pTimer      The timer.
+ * @param   pSubTimer   The sub-timer which we're handling, the state of this
+ *                      will be RTTIMERLNXSTATE_CALLBACK_DESTROYING.
+ */
+static void rtTimerLnxCallbackDestroy(PRTTIMER pTimer, PRTTIMERLNXSUBTIMER pSubTimer)
+{
+    /*
+     * If it's an omni timer, the last dude does the destroying.
+     */
+    if (pTimer->cCpus > 1)
+    {
+        uint32_t        iCpu        = pTimer->cCpus;
+        RTSpinlockAcquire(pTimer->hSpinlock);
+
+        Assert(pSubTimer->enmState == RTTIMERLNXSTATE_CB_DESTROYING);
+        rtTimerLnxSetState(&pSubTimer->enmState, RTTIMERLNXSTATE_STOPPED);
+
+        while (iCpu-- > 0)
+            if (rtTimerLnxGetState(&pTimer->aSubTimers[iCpu].enmState) != RTTIMERLNXSTATE_STOPPED)
+            {
+                RTSpinlockRelease(pTimer->hSpinlock);
+                return;
+            }
+
+        RTSpinlockRelease(pTimer->hSpinlock);
+    }
+
+    /*
+     * Destroying a timer from the callback is unsafe since the callout code
+     * might be touching the timer structure upon return (hrtimer does!).  So,
+     * we have to defer the actual destruction to the IRPT workqueue.
+     */
+    rtR0LnxWorkqueuePush(&pTimer->DtorWorkqueueItem, rtTimerLnxDestroyDeferred);
+}
+
+
+#ifdef CONFIG_SMP
+/**
+ * Deal with a sub-timer that has migrated.
+ *
+ * @param   pTimer          The timer.
+ * @param   pSubTimer       The sub-timer.
+ */
+static void rtTimerLnxCallbackHandleMigration(PRTTIMER pTimer, PRTTIMERLNXSUBTIMER pSubTimer)
+{
+    RTTIMERLNXSTATE enmState;
+    if (pTimer->cCpus > 1)
+        RTSpinlockAcquire(pTimer->hSpinlock);
+
+    do
+    {
+        enmState = rtTimerLnxGetState(&pSubTimer->enmState);
+        switch (enmState)
+        {
+            case RTTIMERLNXSTATE_STOPPING:
+            case RTTIMERLNXSTATE_MP_STOPPING:
+                enmState = RTTIMERLNXSTATE_STOPPED;
+            case RTTIMERLNXSTATE_STOPPED:
+                break;
+
+            default:
+                AssertMsgFailed(("%d\n", enmState)); RT_FALL_THRU();
+            case RTTIMERLNXSTATE_STARTING:
+            case RTTIMERLNXSTATE_MP_STARTING:
+            case RTTIMERLNXSTATE_ACTIVE:
+            case RTTIMERLNXSTATE_CALLBACK:
+            case RTTIMERLNXSTATE_CB_STOPPING:
+            case RTTIMERLNXSTATE_CB_RESTARTING:
+                if (rtTimerLnxCmpXchgState(&pSubTimer->enmState, RTTIMERLNXSTATE_STOPPED, enmState))
+                    enmState = RTTIMERLNXSTATE_STOPPED;
+                break;
+
+            case RTTIMERLNXSTATE_CB_DESTROYING:
+            {
+                if (pTimer->cCpus > 1)
+                    RTSpinlockRelease(pTimer->hSpinlock);
+
+                rtTimerLnxCallbackDestroy(pTimer, pSubTimer);
+                return;
+            }
+        }
+    } while (enmState != RTTIMERLNXSTATE_STOPPED);
+
+    if (pTimer->cCpus > 1)
+        RTSpinlockRelease(pTimer->hSpinlock);
+}
+#endif /* CONFIG_SMP */
+
+
+/**
+ * The slow path of rtTimerLnxChangeToCallbackState.
+ *
+ * @returns true if changed successfully, false if not.
+ * @param   pSubTimer       The sub-timer.
+ */
+static bool rtTimerLnxChangeToCallbackStateSlow(PRTTIMERLNXSUBTIMER pSubTimer)
+{
+    for (;;)
+    {
+        RTTIMERLNXSTATE enmState = rtTimerLnxGetState(&pSubTimer->enmState);
+        switch (enmState)
+        {
+            case RTTIMERLNXSTATE_ACTIVE:
+            case RTTIMERLNXSTATE_STARTING:
+            case RTTIMERLNXSTATE_MP_STARTING:
+                if (rtTimerLnxCmpXchgState(&pSubTimer->enmState, RTTIMERLNXSTATE_CALLBACK, enmState))
+                    return true;
+                break;
+
+            case RTTIMERLNXSTATE_CALLBACK:
+            case RTTIMERLNXSTATE_CB_STOPPING:
+            case RTTIMERLNXSTATE_CB_RESTARTING:
+            case RTTIMERLNXSTATE_CB_DESTROYING:
+                AssertMsgFailed(("%d\n", enmState)); RT_FALL_THRU();
+            default:
+                return false;
+        }
+        ASMNopPause();
+    }
+}
+
+
+/**
+ * Tries to change the sub-timer state to 'callback'.
+ *
+ * @returns true if changed successfully, false if not.
+ * @param   pSubTimer       The sub-timer.
+ */
+DECLINLINE(bool) rtTimerLnxChangeToCallbackState(PRTTIMERLNXSUBTIMER pSubTimer)
+{
+    if (RT_LIKELY(rtTimerLnxCmpXchgState(&pSubTimer->enmState, RTTIMERLNXSTATE_CALLBACK, RTTIMERLNXSTATE_ACTIVE)))
+        return true;
+    return rtTimerLnxChangeToCallbackStateSlow(pSubTimer);
+}
+
+
+#ifdef RTTIMER_LINUX_WITH_HRTIMER
+/**
+ * Timer callback function for high resolution timers.
+ *
+ * @returns HRTIMER_NORESTART or HRTIMER_RESTART depending on whether it's a
+ *          one-shot or interval timer.
+ * @param   pHrTimer    Pointer to the sub-timer structure.
+ */
+static enum hrtimer_restart rtTimerLinuxHrCallback(struct hrtimer *pHrTimer)
+{
+    PRTTIMERLNXSUBTIMER     pSubTimer = RT_FROM_MEMBER(pHrTimer, RTTIMERLNXSUBTIMER, u.Hr.LnxTimer);
+    PRTTIMER                pTimer    = pSubTimer->pParent;
+
+
+    RTTIMERLNX_LOG(("hrcallback %p\n", pTimer));
+    if (RT_UNLIKELY(!rtTimerLnxChangeToCallbackState(pSubTimer)))
+        return HRTIMER_NORESTART;
+
+#ifdef CONFIG_SMP
+    /*
+     * Check for unwanted migration.
+     */
+    if (pTimer->fAllCpus || pTimer->fSpecificCpu)
+    {
+        RTCPUID idCpu = RTMpCpuId();
+        if (RT_UNLIKELY(  pTimer->fAllCpus
+                        ? (RTCPUID)(pSubTimer - &pTimer->aSubTimers[0]) != idCpu
+                        : pTimer->idCpu != idCpu))
+        {
+            rtTimerLnxCallbackHandleMigration(pTimer, pSubTimer);
+            return HRTIMER_NORESTART;
+        }
+    }
+#endif
+
+    if (pTimer->u64NanoInterval)
+    {
+        /*
+         * Periodic timer, run it and update the native timer afterwards so
+         * we can handle RTTimerStop and RTTimerChangeInterval from the
+         * callback as well as a racing control thread.
+         */
+        pTimer->pfnTimer(pTimer, pTimer->pvUser, ++pSubTimer->iTick);
+        hrtimer_add_expires_ns(&pSubTimer->u.Hr.LnxTimer, ASMAtomicReadU64(&pTimer->u64NanoInterval));
+        if (RT_LIKELY(rtTimerLnxCmpXchgState(&pSubTimer->enmState, RTTIMERLNXSTATE_ACTIVE, RTTIMERLNXSTATE_CALLBACK)))
+            return HRTIMER_RESTART;
+    }
+    else
+    {
+        /*
+         * One shot timer (no omni), stop it before dispatching it.
+         * Allow RTTimerStart as well as RTTimerDestroy to be called from
+         * the callback.
+         */
+        ASMAtomicWriteBool(&pTimer->fSuspended, true);
+        pTimer->pfnTimer(pTimer, pTimer->pvUser, ++pSubTimer->iTick);
+        if (RT_LIKELY(rtTimerLnxCmpXchgState(&pSubTimer->enmState, RTTIMERLNXSTATE_STOPPED, RTTIMERLNXSTATE_CALLBACK)))
+            return HRTIMER_NORESTART;
+    }
+
+    /*
+     * Some state change occurred while we were in the callback routine.
+     */
+    for (;;)
+    {
+        RTTIMERLNXSTATE enmState = rtTimerLnxGetState(&pSubTimer->enmState);
+        switch (enmState)
+        {
+            case RTTIMERLNXSTATE_CB_DESTROYING:
+                rtTimerLnxCallbackDestroy(pTimer, pSubTimer);
+                return HRTIMER_NORESTART;
+
+            case RTTIMERLNXSTATE_CB_STOPPING:
+                if (rtTimerLnxCmpXchgState(&pSubTimer->enmState, RTTIMERLNXSTATE_STOPPED, RTTIMERLNXSTATE_CB_STOPPING))
+                    return HRTIMER_NORESTART;
+                break;
+
+            case RTTIMERLNXSTATE_CB_RESTARTING:
+                if (rtTimerLnxCmpXchgState(&pSubTimer->enmState, RTTIMERLNXSTATE_ACTIVE, RTTIMERLNXSTATE_CB_RESTARTING))
+                {
+                    pSubTimer->iTick = 0;
+                    hrtimer_set_expires(&pSubTimer->u.Hr.LnxTimer, rtTimerLnxNanoToKt(pSubTimer->uNsRestartAt));
+                    return HRTIMER_RESTART;
+                }
+                break;
+
+            default:
+                AssertMsgFailed(("%d\n", enmState));
+                return HRTIMER_NORESTART;
+        }
+        ASMNopPause();
+    }
+}
+#endif /* RTTIMER_LINUX_WITH_HRTIMER */
+
+
+#if RTLNX_VER_MIN(4,15,0)
+/**
+ * Timer callback function for standard timers.
+ *
+ * @param   pLnxTimer   Pointer to the Linux timer structure.
+ */
+static void rtTimerLinuxStdCallback(struct timer_list *pLnxTimer)
+{
+    PRTTIMERLNXSUBTIMER pSubTimer = from_timer(pSubTimer, pLnxTimer, u.Std.LnxTimer);
+#else
+/**
+ * Timer callback function for standard timers.
+ *
+ * @param   ulUser      Address of the sub-timer structure.
+ */
+static void rtTimerLinuxStdCallback(unsigned long ulUser)
+{
+    PRTTIMERLNXSUBTIMER pSubTimer = (PRTTIMERLNXSUBTIMER)ulUser;
+#endif
+    PRTTIMER            pTimer    = pSubTimer->pParent;
+
+    RTTIMERLNX_LOG(("stdcallback %p\n", pTimer));
+    if (RT_UNLIKELY(!rtTimerLnxChangeToCallbackState(pSubTimer)))
+        return;
+
+#ifdef CONFIG_SMP
+    /*
+     * Check for unwanted migration.
+     */
+    if (pTimer->fAllCpus || pTimer->fSpecificCpu)
+    {
+        RTCPUID idCpu = RTMpCpuId();
+        if (RT_UNLIKELY(  pTimer->fAllCpus
+                        ? (RTCPUID)(pSubTimer - &pTimer->aSubTimers[0]) != idCpu
+                        : pTimer->idCpu != idCpu))
+        {
+            rtTimerLnxCallbackHandleMigration(pTimer, pSubTimer);
+            return;
+        }
+    }
+#endif
+
+    if (pTimer->u64NanoInterval)
+    {
+        /*
+         * Interval timer, calculate the next timeout.
+         *
+         * The first time around, we'll re-adjust the u.Std.u64NextTS to
+         * try prevent some jittering if we were started at a bad time.
+         */
+        const uint64_t  iTick       = ++pSubTimer->iTick;
+        unsigned long   uCurJiffies = jiffies;
+        unsigned long   ulNextJiffies;
+        uint64_t        u64NanoInterval;
+        unsigned long   cJiffies;
+        unsigned long   flFlags;
+
+        spin_lock_irqsave(&pTimer->ChgIntLock, flFlags);
+        u64NanoInterval = pTimer->u64NanoInterval;
+        cJiffies        = pTimer->cJiffies;
+        if (RT_UNLIKELY(pSubTimer->u.Std.fFirstAfterChg))
+        {
+            pSubTimer->u.Std.fFirstAfterChg = false;
+            pSubTimer->u.Std.u64NextTS      = RTTimeSystemNanoTS();
+            pSubTimer->u.Std.nsStartTS      = pSubTimer->u.Std.u64NextTS - u64NanoInterval * (iTick - 1);
+            pSubTimer->u.Std.ulNextJiffies  = uCurJiffies = jiffies;
+        }
+        spin_unlock_irqrestore(&pTimer->ChgIntLock, flFlags);
+
+        pSubTimer->u.Std.u64NextTS += u64NanoInterval;
+        if (cJiffies)
+        {
+            ulNextJiffies = pSubTimer->u.Std.ulNextJiffies + cJiffies;
+            pSubTimer->u.Std.ulNextJiffies = ulNextJiffies;
+            if (time_after_eq(ulNextJiffies, uCurJiffies))
+            { /* likely */ }
+            else
+            {
+                unsigned long cJiffiesBehind = uCurJiffies - ulNextJiffies;
+                ulNextJiffies = uCurJiffies + cJiffies / 2;
+                if (cJiffiesBehind >= HZ / 4) /* Conside if we're lagging too far behind.  Screw the u64NextTS member. */
+                    pSubTimer->u.Std.ulNextJiffies = ulNextJiffies;
+                /*else: Don't update u.Std.ulNextJiffies so we can continue catching up in the next tick. */
+            }
+        }
+        else
+        {
+            const uint64_t u64NanoTS = RTTimeSystemNanoTS();
+            const int64_t  cNsBehind = u64NanoTS - pSubTimer->u.Std.u64NextTS;
+            if (cNsBehind <= 0)
+                ulNextJiffies = uCurJiffies + rtTimerLnxNanoToJiffies(pSubTimer->u.Std.u64NextTS - u64NanoTS);
+            else if (u64NanoInterval >= RT_NS_1SEC_64 * 2 / HZ)
+            {
+                ulNextJiffies = uCurJiffies + rtTimerLnxNanoToJiffies(u64NanoInterval / 2);
+                if (cNsBehind >= RT_NS_1SEC_64 / HZ / 4) /* Conside if we're lagging too far behind. */
+                    pSubTimer->u.Std.u64NextTS = u64NanoTS + u64NanoInterval / 2;
+            }
+            else
+            {
+                ulNextJiffies = uCurJiffies + 1;
+                if (cNsBehind >= RT_NS_1SEC_64 / HZ / 4) /* Conside if we're lagging too far behind. */
+                    pSubTimer->u.Std.u64NextTS = u64NanoTS + RT_NS_1SEC_64 / HZ;
+            }
+            pSubTimer->u.Std.ulNextJiffies = ulNextJiffies;
+        }
+
+        /*
+         * Run the timer and re-arm it unless the state changed                                                                                                        .
+         *                                                                                                                                                             .
+         * We must re-arm it afterwards as we're not in a position to undo this                                                                                        .
+         * operation if for instance someone stopped or destroyed us while we                                                                                          .
+         * were in the callback.  (Linux takes care of any races here.)
+         */
+        pTimer->pfnTimer(pTimer, pTimer->pvUser, iTick);
+        if (RT_LIKELY(rtTimerLnxCmpXchgState(&pSubTimer->enmState, RTTIMERLNXSTATE_ACTIVE, RTTIMERLNXSTATE_CALLBACK)))
+        {
+#ifdef CONFIG_SMP
+            if (pTimer->fSpecificCpu || pTimer->fAllCpus)
+            {
+# if RTLNX_VER_MIN(4,8,0)
+                mod_timer(&pSubTimer->u.Std.LnxTimer, ulNextJiffies);
+# else
+                mod_timer_pinned(&pSubTimer->u.Std.LnxTimer, ulNextJiffies);
+# endif
+            }
+            else
+#endif
+                mod_timer(&pSubTimer->u.Std.LnxTimer, ulNextJiffies);
+            return;
+        }
+    }
+    else
+    {
+        /*
+         * One shot timer, stop it before dispatching it.
+         * Allow RTTimerStart as well as RTTimerDestroy to be called from
+         * the callback.
+         */
+        ASMAtomicWriteBool(&pTimer->fSuspended, true);
+        pTimer->pfnTimer(pTimer, pTimer->pvUser, ++pSubTimer->iTick);
+        if (RT_LIKELY(rtTimerLnxCmpXchgState(&pSubTimer->enmState, RTTIMERLNXSTATE_STOPPED, RTTIMERLNXSTATE_CALLBACK)))
+            return;
+    }
+
+    /*
+     * Some state change occurred while we were in the callback routine.
+     */
+    for (;;)
+    {
+        RTTIMERLNXSTATE enmState = rtTimerLnxGetState(&pSubTimer->enmState);
+        switch (enmState)
+        {
+            case RTTIMERLNXSTATE_CB_DESTROYING:
+                rtTimerLnxCallbackDestroy(pTimer, pSubTimer);
+                return;
+
+            case RTTIMERLNXSTATE_CB_STOPPING:
+                if (rtTimerLnxCmpXchgState(&pSubTimer->enmState, RTTIMERLNXSTATE_STOPPED, RTTIMERLNXSTATE_CB_STOPPING))
+                    return;
+                break;
+
+            case RTTIMERLNXSTATE_CB_RESTARTING:
+                if (rtTimerLnxCmpXchgState(&pSubTimer->enmState, RTTIMERLNXSTATE_ACTIVE, RTTIMERLNXSTATE_CB_RESTARTING))
+                {
+                    uint64_t        u64NanoTS;
+                    uint64_t        u64NextTS;
+                    unsigned long   flFlags;
+
+                    spin_lock_irqsave(&pTimer->ChgIntLock, flFlags);
+                    u64NextTS = pSubTimer->uNsRestartAt;
+                    u64NanoTS = RTTimeSystemNanoTS();
+                    pSubTimer->iTick                = 0;
+                    pSubTimer->u.Std.u64NextTS      = u64NextTS;
+                    pSubTimer->u.Std.fFirstAfterChg = true;
+                    pSubTimer->u.Std.ulNextJiffies  = u64NextTS > u64NanoTS
+                                                    ? jiffies + rtTimerLnxNanoToJiffies(u64NextTS - u64NanoTS)
+                                                    : jiffies;
+                    spin_unlock_irqrestore(&pTimer->ChgIntLock, flFlags);
+
+#ifdef CONFIG_SMP
+                    if (pTimer->fSpecificCpu || pTimer->fAllCpus)
+                    {
+# if RTLNX_VER_MIN(4,8,0)
+                        mod_timer(&pSubTimer->u.Std.LnxTimer, pSubTimer->u.Std.ulNextJiffies);
+# else
+                        mod_timer_pinned(&pSubTimer->u.Std.LnxTimer, pSubTimer->u.Std.ulNextJiffies);
+# endif
+                    }
+                    else
+#endif
+                        mod_timer(&pSubTimer->u.Std.LnxTimer, pSubTimer->u.Std.ulNextJiffies);
+                    return;
+                }
+                break;
+
+            default:
+                AssertMsgFailed(("%d\n", enmState));
+                return;
+        }
+        ASMNopPause();
+    }
+}
+
+
+#ifdef CONFIG_SMP
+
+/**
+ * Per-cpu callback function (RTMpOnAll/RTMpOnSpecific).
+ *
+ * @param   idCpu       The current CPU.
+ * @param   pvUser1     Pointer to the timer.
+ * @param   pvUser2     Pointer to the argument structure.
+ */
+static DECLCALLBACK(void) rtTimerLnxStartAllOnCpu(RTCPUID idCpu, void *pvUser1, void *pvUser2)
+{
+    PRTTIMERLINUXSTARTONCPUARGS pArgs = (PRTTIMERLINUXSTARTONCPUARGS)pvUser2;
+    PRTTIMER pTimer = (PRTTIMER)pvUser1;
+    Assert(idCpu < pTimer->cCpus);
+    rtTimerLnxStartSubTimer(&pTimer->aSubTimers[idCpu], pArgs->u64Now, pArgs->u64First, true /*fPinned*/, pTimer->fHighRes);
+}
+
+
+/**
+ * Worker for RTTimerStart() that takes care of the ugly bits.
+ *
+ * @returns RTTimerStart() return value.
+ * @param   pTimer      The timer.
+ * @param   pArgs       The argument structure.
+ */
+static int rtTimerLnxOmniStart(PRTTIMER pTimer, PRTTIMERLINUXSTARTONCPUARGS pArgs)
+{
+    RTCPUID         iCpu;
+    RTCPUSET        OnlineSet;
+    RTCPUSET        OnlineSet2;
+    int             rc2;
+
+    /*
+     * Prepare all the sub-timers for the startup and then flag the timer
+     * as a whole as non-suspended, make sure we get them all before
+     * clearing fSuspended as the MP handler will be waiting on this
+     * should something happen while we're looping.
+     */
+    RTSpinlockAcquire(pTimer->hSpinlock);
+
+    /* Just make it a omni timer restriction that no stop/start races are allowed. */
+    for (iCpu = 0; iCpu < pTimer->cCpus; iCpu++)
+        if (rtTimerLnxGetState(&pTimer->aSubTimers[iCpu].enmState) != RTTIMERLNXSTATE_STOPPED)
+        {
+            RTSpinlockRelease(pTimer->hSpinlock);
+            return VERR_TIMER_BUSY;
+        }
+
+    do
+    {
+        RTMpGetOnlineSet(&OnlineSet);
+        for (iCpu = 0; iCpu < pTimer->cCpus; iCpu++)
+        {
+            Assert(pTimer->aSubTimers[iCpu].enmState != RTTIMERLNXSTATE_MP_STOPPING);
+            rtTimerLnxSetState(&pTimer->aSubTimers[iCpu].enmState,
+                               RTCpuSetIsMember(&OnlineSet, iCpu)
+                               ? RTTIMERLNXSTATE_STARTING
+                               : RTTIMERLNXSTATE_STOPPED);
+        }
+    } while (!RTCpuSetIsEqual(&OnlineSet, RTMpGetOnlineSet(&OnlineSet2)));
+
+    ASMAtomicWriteBool(&pTimer->fSuspended, false);
+
+    RTSpinlockRelease(pTimer->hSpinlock);
+
+    /*
+     * Start them (can't find any exported function that allows me to
+     * do this without the cross calls).
+     */
+    pArgs->u64Now = RTTimeSystemNanoTS();
+    rc2 = RTMpOnAll(rtTimerLnxStartAllOnCpu, pTimer, pArgs);
+    AssertRC(rc2); /* screw this if it fails. */
+
+    /*
+     * Reset the sub-timers who didn't start up (ALL CPUs case).
+     */
+    RTSpinlockAcquire(pTimer->hSpinlock);
+
+    for (iCpu = 0; iCpu < pTimer->cCpus; iCpu++)
+        if (rtTimerLnxCmpXchgState(&pTimer->aSubTimers[iCpu].enmState, RTTIMERLNXSTATE_STOPPED, RTTIMERLNXSTATE_STARTING))
+        {
+            /** @todo very odd case for a rainy day. Cpus that temporarily went offline while
+             * we were between calls needs to nudged as the MP handler will ignore events for
+             * them because of the STARTING state. This is an extremely unlikely case - not that
+             * that means anything in my experience... ;-) */
+            RTTIMERLNX_LOG(("what!? iCpu=%u -> didn't start\n", iCpu));
+        }
+
+    RTSpinlockRelease(pTimer->hSpinlock);
+
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Worker for RTTimerStop() that takes care of the ugly SMP bits.
+ *
+ * @returns true if there was any active callbacks, false if not.
+ * @param   pTimer      The timer (valid).
+ * @param   fForDestroy Whether this is for RTTimerDestroy or not.
+ */
+static bool rtTimerLnxOmniStop(PRTTIMER pTimer, bool fForDestroy)
+{
+    bool            fActiveCallbacks = false;
+    RTCPUID         iCpu;
+    RTTIMERLNXSTATE enmState;
+
+
+    /*
+     * Mark the timer as suspended and flag all timers as stopping, except
+     * for those being stopped by an MP event.
+     */
+    RTSpinlockAcquire(pTimer->hSpinlock);
+
+    ASMAtomicWriteBool(&pTimer->fSuspended, true);
+    for (iCpu = 0; iCpu < pTimer->cCpus; iCpu++)
+    {
+        for (;;)
+        {
+            enmState = rtTimerLnxGetState(&pTimer->aSubTimers[iCpu].enmState);
+            if (    enmState == RTTIMERLNXSTATE_STOPPED
+                ||  enmState == RTTIMERLNXSTATE_MP_STOPPING)
+                break;
+            if (   enmState == RTTIMERLNXSTATE_CALLBACK
+                || enmState == RTTIMERLNXSTATE_CB_STOPPING
+                || enmState == RTTIMERLNXSTATE_CB_RESTARTING)
+            {
+                Assert(enmState != RTTIMERLNXSTATE_CB_STOPPING || fForDestroy);
+                if (rtTimerLnxCmpXchgState(&pTimer->aSubTimers[iCpu].enmState,
+                                           !fForDestroy ? RTTIMERLNXSTATE_CB_STOPPING : RTTIMERLNXSTATE_CB_DESTROYING,
+                                           enmState))
+                {
+                    fActiveCallbacks = true;
+                    break;
+                }
+            }
+            else
+            {
+                Assert(enmState == RTTIMERLNXSTATE_ACTIVE);
+                if (rtTimerLnxCmpXchgState(&pTimer->aSubTimers[iCpu].enmState, RTTIMERLNXSTATE_STOPPING, enmState))
+                    break;
+            }
+            ASMNopPause();
+        }
+    }
+
+    RTSpinlockRelease(pTimer->hSpinlock);
+
+    /*
+     * Do the actual stopping. Fortunately, this doesn't require any IPIs.
+     * Unfortunately it cannot be done synchronously.
+     */
+    for (iCpu = 0; iCpu < pTimer->cCpus; iCpu++)
+        if (rtTimerLnxGetState(&pTimer->aSubTimers[iCpu].enmState) == RTTIMERLNXSTATE_STOPPING)
+            rtTimerLnxStopSubTimer(&pTimer->aSubTimers[iCpu], pTimer->fHighRes);
+
+    return fActiveCallbacks;
+}
+
+
+/**
+ * Per-cpu callback function (RTMpOnSpecific) used by rtTimerLinuxMpEvent()
+ * to start a sub-timer on a cpu that just have come online.
+ *
+ * @param   idCpu       The current CPU.
+ * @param   pvUser1     Pointer to the timer.
+ * @param   pvUser2     Pointer to the argument structure.
+ */
+static DECLCALLBACK(void) rtTimerLinuxMpStartOnCpu(RTCPUID idCpu, void *pvUser1, void *pvUser2)
+{
+    PRTTIMERLINUXSTARTONCPUARGS pArgs = (PRTTIMERLINUXSTARTONCPUARGS)pvUser2;
+    PRTTIMER pTimer = (PRTTIMER)pvUser1;
+    RTSPINLOCK hSpinlock;
+    Assert(idCpu < pTimer->cCpus);
+
+    /*
+     * We have to be kind of careful here as we might be racing RTTimerStop
+     * (and/or RTTimerDestroy, thus the paranoia.
+     */
+    hSpinlock = pTimer->hSpinlock;
+    if (    hSpinlock != NIL_RTSPINLOCK
+        &&  pTimer->u32Magic == RTTIMER_MAGIC)
+    {
+        RTSpinlockAcquire(hSpinlock);
+
+        if (    !ASMAtomicUoReadBool(&pTimer->fSuspended)
+            &&  pTimer->u32Magic == RTTIMER_MAGIC)
+        {
+            /* We're sane and the timer is not suspended yet. */
+            PRTTIMERLNXSUBTIMER pSubTimer = &pTimer->aSubTimers[idCpu];
+            if (rtTimerLnxCmpXchgState(&pSubTimer->enmState, RTTIMERLNXSTATE_MP_STARTING, RTTIMERLNXSTATE_STOPPED))
+                rtTimerLnxStartSubTimer(pSubTimer, pArgs->u64Now, pArgs->u64First, true /*fPinned*/, pTimer->fHighRes);
+        }
+
+        RTSpinlockRelease(hSpinlock);
+    }
+}
+
+
+/**
+ * MP event notification callback.
+ *
+ * @param   enmEvent    The event.
+ * @param   idCpu       The cpu it applies to.
+ * @param   pvUser      The timer.
+ */
+static DECLCALLBACK(void) rtTimerLinuxMpEvent(RTMPEVENT enmEvent, RTCPUID idCpu, void *pvUser)
+{
+    PRTTIMER            pTimer    = (PRTTIMER)pvUser;
+    PRTTIMERLNXSUBTIMER pSubTimer = &pTimer->aSubTimers[idCpu];
+    RTSPINLOCK          hSpinlock;
+
+    Assert(idCpu < pTimer->cCpus);
+
+    /*
+     * Some initial paranoia.
+     */
+    if (pTimer->u32Magic != RTTIMER_MAGIC)
+        return;
+    hSpinlock = pTimer->hSpinlock;
+    if (hSpinlock == NIL_RTSPINLOCK)
+        return;
+
+    RTSpinlockAcquire(hSpinlock);
+
+    /* Is it active? */
+    if (    !ASMAtomicUoReadBool(&pTimer->fSuspended)
+        &&  pTimer->u32Magic == RTTIMER_MAGIC)
+    {
+        switch (enmEvent)
+        {
+            /*
+             * Try do it without leaving the spin lock, but if we have to, retake it
+             * when we're on the right cpu.
+             */
+            case RTMPEVENT_ONLINE:
+                if (rtTimerLnxCmpXchgState(&pSubTimer->enmState, RTTIMERLNXSTATE_MP_STARTING, RTTIMERLNXSTATE_STOPPED))
+                {
+                    RTTIMERLINUXSTARTONCPUARGS Args;
+                    Args.u64Now = RTTimeSystemNanoTS();
+                    Args.u64First = 0;
+
+                    if (RTMpCpuId() == idCpu)
+                        rtTimerLnxStartSubTimer(pSubTimer, Args.u64Now, Args.u64First, true /*fPinned*/, pTimer->fHighRes);
+                    else
+                    {
+                        rtTimerLnxSetState(&pSubTimer->enmState, RTTIMERLNXSTATE_STOPPED); /* we'll recheck it. */
+                        RTSpinlockRelease(hSpinlock);
+
+                        RTMpOnSpecific(idCpu, rtTimerLinuxMpStartOnCpu, pTimer, &Args);
+                        return; /* we've left the spinlock */
+                    }
+                }
+                break;
+
+            /*
+             * The CPU is (going) offline, make sure the sub-timer is stopped.
+             *
+             * Linux will migrate it to a different CPU, but we don't want this. The
+             * timer function is checking for this.
+             */
+            case RTMPEVENT_OFFLINE:
+            {
+                RTTIMERLNXSTATE enmState;
+                while (   (enmState = rtTimerLnxGetState(&pSubTimer->enmState)) == RTTIMERLNXSTATE_ACTIVE
+                       || enmState == RTTIMERLNXSTATE_CALLBACK
+                       || enmState == RTTIMERLNXSTATE_CB_RESTARTING)
+                {
+                    if (enmState == RTTIMERLNXSTATE_ACTIVE)
+                    {
+                        if (rtTimerLnxCmpXchgState(&pSubTimer->enmState, RTTIMERLNXSTATE_MP_STOPPING, RTTIMERLNXSTATE_ACTIVE))
+                        {
+                            RTSpinlockRelease(hSpinlock);
+
+                            rtTimerLnxStopSubTimer(pSubTimer, pTimer->fHighRes);
+                            return; /* we've left the spinlock */
+                        }
+                    }
+                    else if (rtTimerLnxCmpXchgState(&pSubTimer->enmState, RTTIMERLNXSTATE_CB_STOPPING, enmState))
+                        break;
+
+                    /* State not stable, try again. */
+                    ASMNopPause();
+                }
+                break;
+            }
+        }
+    }
+
+    RTSpinlockRelease(hSpinlock);
+}
+
+#endif /* CONFIG_SMP */
+
+
+/**
+ * Callback function use by RTTimerStart via RTMpOnSpecific to start a timer
+ * running on a specific CPU.
+ *
+ * @param   idCpu       The current CPU.
+ * @param   pvUser1     Pointer to the timer.
+ * @param   pvUser2     Pointer to the argument structure.
+ */
+static DECLCALLBACK(void) rtTimerLnxStartOnSpecificCpu(RTCPUID idCpu, void *pvUser1, void *pvUser2)
+{
+    PRTTIMERLINUXSTARTONCPUARGS pArgs = (PRTTIMERLINUXSTARTONCPUARGS)pvUser2;
+    PRTTIMER pTimer = (PRTTIMER)pvUser1;
+    RT_NOREF_PV(idCpu);
+    rtTimerLnxStartSubTimer(&pTimer->aSubTimers[0], pArgs->u64Now, pArgs->u64First, true /*fPinned*/, pTimer->fHighRes);
+}
+
+
+RTDECL(int) RTTimerStart(PRTTIMER pTimer, uint64_t u64First)
+{
+    RTTIMERLINUXSTARTONCPUARGS Args;
+    int rc2;
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    /*
+     * Validate.
+     */
+    AssertPtrReturn(pTimer, VERR_INVALID_HANDLE);
+    AssertReturn(pTimer->u32Magic == RTTIMER_MAGIC, VERR_INVALID_HANDLE);
+
+    if (!ASMAtomicUoReadBool(&pTimer->fSuspended))
+        return VERR_TIMER_ACTIVE;
+    RTTIMERLNX_LOG(("start %p cCpus=%d\n", pTimer, pTimer->cCpus));
+
+    Args.u64First = u64First;
+#ifdef CONFIG_SMP
+    /*
+     * Omni timer?
+     */
+    if (pTimer->fAllCpus)
+    {
+        rc2 = rtTimerLnxOmniStart(pTimer, &Args);
+        IPRT_LINUX_RESTORE_EFL_AC();
+        return rc2;
+    }
+#endif
+
+    /*
+     * Simple timer - Pretty straight forward if it wasn't for restarting.
+     */
+    Args.u64Now = RTTimeSystemNanoTS();
+    ASMAtomicWriteU64(&pTimer->aSubTimers[0].uNsRestartAt, Args.u64Now + u64First);
+    for (;;)
+    {
+        RTTIMERLNXSTATE enmState = rtTimerLnxGetState(&pTimer->aSubTimers[0].enmState);
+        switch (enmState)
+        {
+            case RTTIMERLNXSTATE_STOPPED:
+                if (rtTimerLnxCmpXchgState(&pTimer->aSubTimers[0].enmState, RTTIMERLNXSTATE_STARTING, RTTIMERLNXSTATE_STOPPED))
+                {
+                    ASMAtomicWriteBool(&pTimer->fSuspended, false);
+                    if (!pTimer->fSpecificCpu)
+                        rtTimerLnxStartSubTimer(&pTimer->aSubTimers[0], Args.u64Now, Args.u64First,
+                                                false /*fPinned*/, pTimer->fHighRes);
+                    else
+                    {
+                        rc2 = RTMpOnSpecific(pTimer->idCpu, rtTimerLnxStartOnSpecificCpu, pTimer, &Args);
+                        if (RT_FAILURE(rc2))
+                        {
+                            /* Suspend it, the cpu id is probably invalid or offline. */
+                            ASMAtomicWriteBool(&pTimer->fSuspended, true);
+                            rtTimerLnxSetState(&pTimer->aSubTimers[0].enmState, RTTIMERLNXSTATE_STOPPED);
+                            return rc2;
+                        }
+                    }
+                    IPRT_LINUX_RESTORE_EFL_AC();
+                    return VINF_SUCCESS;
+                }
+                break;
+
+            case RTTIMERLNXSTATE_CALLBACK:
+            case RTTIMERLNXSTATE_CB_STOPPING:
+                if (rtTimerLnxCmpXchgState(&pTimer->aSubTimers[0].enmState, RTTIMERLNXSTATE_CB_RESTARTING, enmState))
+                {
+                    ASMAtomicWriteBool(&pTimer->fSuspended, false);
+                    IPRT_LINUX_RESTORE_EFL_AC();
+                    return VINF_SUCCESS;
+                }
+                break;
+
+            default:
+                AssertMsgFailed(("%d\n", enmState));
+                IPRT_LINUX_RESTORE_EFL_AC();
+                return VERR_INTERNAL_ERROR_4;
+        }
+        ASMNopPause();
+    }
+}
+RT_EXPORT_SYMBOL(RTTimerStart);
+
+
+/**
+ * Common worker for RTTimerStop and RTTimerDestroy.
+ *
+ * @returns true if there was any active callbacks, false if not.
+ * @param   pTimer              The timer to stop.
+ * @param   fForDestroy         Whether it's RTTimerDestroy calling or not.
+ */
+static bool rtTimerLnxStop(PRTTIMER pTimer, bool fForDestroy)
+{
+    RTTIMERLNX_LOG(("lnxstop %p %d\n", pTimer, fForDestroy));
+#ifdef CONFIG_SMP
+    /*
+     * Omni timer?
+     */
+    if (pTimer->fAllCpus)
+        return rtTimerLnxOmniStop(pTimer, fForDestroy);
+#endif
+
+    /*
+     * Simple timer.
+     */
+    ASMAtomicWriteBool(&pTimer->fSuspended, true);
+    for (;;)
+    {
+        RTTIMERLNXSTATE enmState = rtTimerLnxGetState(&pTimer->aSubTimers[0].enmState);
+        switch (enmState)
+        {
+            case RTTIMERLNXSTATE_ACTIVE:
+                if (rtTimerLnxCmpXchgState(&pTimer->aSubTimers[0].enmState, RTTIMERLNXSTATE_STOPPING, RTTIMERLNXSTATE_ACTIVE))
+                {
+                    rtTimerLnxStopSubTimer(&pTimer->aSubTimers[0], pTimer->fHighRes);
+                    return false;
+                }
+                break;
+
+            case RTTIMERLNXSTATE_CALLBACK:
+            case RTTIMERLNXSTATE_CB_RESTARTING:
+            case RTTIMERLNXSTATE_CB_STOPPING:
+                Assert(enmState != RTTIMERLNXSTATE_CB_STOPPING || fForDestroy);
+                if (rtTimerLnxCmpXchgState(&pTimer->aSubTimers[0].enmState,
+                                           !fForDestroy ? RTTIMERLNXSTATE_CB_STOPPING : RTTIMERLNXSTATE_CB_DESTROYING,
+                                           enmState))
+                    return true;
+                break;
+
+            case RTTIMERLNXSTATE_STOPPED:
+                return VINF_SUCCESS;
+
+            case RTTIMERLNXSTATE_CB_DESTROYING:
+                AssertMsgFailed(("enmState=%d pTimer=%p\n", enmState, pTimer));
+                return true;
+
+            default:
+            case RTTIMERLNXSTATE_STARTING:
+            case RTTIMERLNXSTATE_MP_STARTING:
+            case RTTIMERLNXSTATE_STOPPING:
+            case RTTIMERLNXSTATE_MP_STOPPING:
+                AssertMsgFailed(("enmState=%d pTimer=%p\n", enmState, pTimer));
+                return false;
+        }
+
+        /* State not stable, try again. */
+        ASMNopPause();
+    }
+}
+
+
+RTDECL(int) RTTimerStop(PRTTIMER pTimer)
+{
+    /*
+     * Validate.
+     */
+    IPRT_LINUX_SAVE_EFL_AC();
+    AssertPtrReturn(pTimer, VERR_INVALID_HANDLE);
+    AssertReturn(pTimer->u32Magic == RTTIMER_MAGIC, VERR_INVALID_HANDLE);
+    RTTIMERLNX_LOG(("stop %p\n", pTimer));
+
+    if (ASMAtomicUoReadBool(&pTimer->fSuspended))
+        return VERR_TIMER_SUSPENDED;
+
+    rtTimerLnxStop(pTimer, false /*fForDestroy*/);
+
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTTimerStop);
+
+
+RTDECL(int) RTTimerChangeInterval(PRTTIMER pTimer, uint64_t u64NanoInterval)
+{
+    unsigned long cJiffies;
+    unsigned long flFlags;
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    /*
+     * Validate.
+     */
+    AssertPtrReturn(pTimer, VERR_INVALID_HANDLE);
+    AssertReturn(pTimer->u32Magic == RTTIMER_MAGIC, VERR_INVALID_HANDLE);
+    AssertReturn(u64NanoInterval, VERR_INVALID_PARAMETER);
+    AssertReturn(u64NanoInterval < UINT64_MAX / 8, VERR_INVALID_PARAMETER);
+    AssertReturn(pTimer->u64NanoInterval, VERR_INVALID_STATE);
+    RTTIMERLNX_LOG(("change %p %llu\n", pTimer, u64NanoInterval));
+
+#ifdef RTTIMER_LINUX_WITH_HRTIMER
+    /*
+     * For the high resolution timers it is easy since we don't care so much
+     * about when it is applied to the sub-timers.
+     */
+    if (pTimer->fHighRes)
+    {
+        ASMAtomicWriteU64(&pTimer->u64NanoInterval, u64NanoInterval);
+        IPRT_LINUX_RESTORE_EFL_AC();
+        return VINF_SUCCESS;
+    }
+#endif
+
+    /*
+     * Standard timers have a bit more complicated way of calculating
+     * their interval and such. So, forget omni timers for now.
+     */
+    if (pTimer->cCpus > 1)
+        return VERR_NOT_SUPPORTED;
+
+    cJiffies = u64NanoInterval / (RT_NS_1SEC / HZ);
+    if (cJiffies * (RT_NS_1SEC / HZ) != u64NanoInterval)
+        cJiffies = 0;
+
+    spin_lock_irqsave(&pTimer->ChgIntLock, flFlags);
+    pTimer->aSubTimers[0].u.Std.fFirstAfterChg = true;
+    pTimer->cJiffies = cJiffies;
+    ASMAtomicWriteU64(&pTimer->u64NanoInterval, u64NanoInterval);
+    spin_unlock_irqrestore(&pTimer->ChgIntLock, flFlags);
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTTimerChangeInterval);
+
+
+RTDECL(int) RTTimerDestroy(PRTTIMER pTimer)
+{
+    bool fCanDestroy;
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    /*
+     * Validate. It's ok to pass NULL pointer.
+     */
+    if (pTimer == /*NIL_RTTIMER*/ NULL)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pTimer, VERR_INVALID_HANDLE);
+    AssertReturn(pTimer->u32Magic == RTTIMER_MAGIC, VERR_INVALID_HANDLE);
+    RTTIMERLNX_LOG(("destroy %p\n", pTimer));
+/** @todo We should invalidate the magic here! */
+
+    /*
+     * Stop the timer if it's still active, then destroy it if we can.
+     */
+    if (!ASMAtomicUoReadBool(&pTimer->fSuspended))
+        fCanDestroy = rtTimerLnxStop(pTimer, true /*fForDestroy*/);
+    else
+    {
+        uint32_t        iCpu = pTimer->cCpus;
+        if (pTimer->cCpus > 1)
+            RTSpinlockAcquire(pTimer->hSpinlock);
+
+        fCanDestroy = true;
+        while (iCpu-- > 0)
+        {
+            for (;;)
+            {
+                RTTIMERLNXSTATE enmState = rtTimerLnxGetState(&pTimer->aSubTimers[iCpu].enmState);
+                switch (enmState)
+                {
+                    case RTTIMERLNXSTATE_CALLBACK:
+                    case RTTIMERLNXSTATE_CB_RESTARTING:
+                    case RTTIMERLNXSTATE_CB_STOPPING:
+                        if (!rtTimerLnxCmpXchgState(&pTimer->aSubTimers[iCpu].enmState, RTTIMERLNXSTATE_CB_DESTROYING, enmState))
+                            continue;
+                        fCanDestroy = false;
+                        break;
+
+                    case RTTIMERLNXSTATE_CB_DESTROYING:
+                        AssertMsgFailed(("%d\n", enmState));
+                        fCanDestroy = false;
+                        break;
+                    default:
+                        break;
+                }
+                break;
+            }
+        }
+
+        if (pTimer->cCpus > 1)
+            RTSpinlockRelease(pTimer->hSpinlock);
+    }
+
+    if (fCanDestroy)
+    {
+        /* For paranoid reasons, defer actually destroying the semaphore when
+           in atomic or interrupt context. */
+#if RTLNX_VER_MIN(2,5,32)
+        if (in_atomic() || in_interrupt())
+#else
+        if (in_interrupt())
+#endif
+            rtR0LnxWorkqueuePush(&pTimer->DtorWorkqueueItem, rtTimerLnxDestroyDeferred);
+        else
+            rtTimerLnxDestroyIt(pTimer);
+    }
+
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTTimerDestroy);
+
+
+RTDECL(int) RTTimerCreateEx(PRTTIMER *ppTimer, uint64_t u64NanoInterval, uint32_t fFlags, PFNRTTIMER pfnTimer, void *pvUser)
+{
+    PRTTIMER    pTimer;
+    RTCPUID     iCpu;
+    unsigned    cCpus;
+    int         rc;
+    IPRT_LINUX_SAVE_EFL_AC();
+
+    rtR0LnxWorkqueueFlush();                /* for 2.4 */
+    *ppTimer = NULL;
+
+    /*
+     * Validate flags.
+     */
+    if (!RTTIMER_FLAGS_ARE_VALID(fFlags))
+    {
+        IPRT_LINUX_RESTORE_EFL_AC();
+        return VERR_INVALID_PARAMETER;
+    }
+    if (    (fFlags & RTTIMER_FLAGS_CPU_SPECIFIC)
+        &&  (fFlags & RTTIMER_FLAGS_CPU_ALL) != RTTIMER_FLAGS_CPU_ALL
+        &&  !RTMpIsCpuPossible(RTMpCpuIdFromSetIndex(fFlags & RTTIMER_FLAGS_CPU_MASK)))
+    {
+        IPRT_LINUX_RESTORE_EFL_AC();
+        return VERR_CPU_NOT_FOUND;
+    }
+
+    /*
+     * Allocate the timer handler.
+     */
+    cCpus = 1;
+#ifdef CONFIG_SMP
+    if ((fFlags & RTTIMER_FLAGS_CPU_ALL) == RTTIMER_FLAGS_CPU_ALL)
+    {
+        cCpus = RTMpGetMaxCpuId() + 1;
+        Assert(cCpus <= RTCPUSET_MAX_CPUS); /* On linux we have a 1:1 relationship between cpuid and set index. */
+        AssertReturnStmt(u64NanoInterval, IPRT_LINUX_RESTORE_EFL_AC(), VERR_NOT_IMPLEMENTED); /* We don't implement single shot on all cpus, sorry. */
+    }
+#endif
+
+    rc = RTMemAllocEx(RT_UOFFSETOF_DYN(RTTIMER, aSubTimers[cCpus]), 0,
+                      RTMEMALLOCEX_FLAGS_ZEROED | RTMEMALLOCEX_FLAGS_ANY_CTX_FREE, (void **)&pTimer);
+    if (RT_FAILURE(rc))
+    {
+        IPRT_LINUX_RESTORE_EFL_AC();
+        return rc;
+    }
+
+    /*
+     * Initialize it.
+     */
+    pTimer->u32Magic        = RTTIMER_MAGIC;
+    pTimer->hSpinlock       = NIL_RTSPINLOCK;
+    pTimer->fSuspended      = true;
+    pTimer->fHighRes        = !!(fFlags & RTTIMER_FLAGS_HIGH_RES);
+#ifdef CONFIG_SMP
+    pTimer->fSpecificCpu    = (fFlags & RTTIMER_FLAGS_CPU_SPECIFIC) && (fFlags & RTTIMER_FLAGS_CPU_ALL) != RTTIMER_FLAGS_CPU_ALL;
+    pTimer->fAllCpus        = (fFlags & RTTIMER_FLAGS_CPU_ALL) == RTTIMER_FLAGS_CPU_ALL;
+    pTimer->idCpu           = pTimer->fSpecificCpu
+                            ? RTMpCpuIdFromSetIndex(fFlags & RTTIMER_FLAGS_CPU_MASK)
+                            : NIL_RTCPUID;
+#else
+    pTimer->fSpecificCpu    = !!(fFlags & RTTIMER_FLAGS_CPU_SPECIFIC);
+    pTimer->idCpu           = RTMpCpuId();
+#endif
+    pTimer->cCpus           = cCpus;
+    pTimer->pfnTimer        = pfnTimer;
+    pTimer->pvUser          = pvUser;
+    pTimer->u64NanoInterval = u64NanoInterval;
+    pTimer->cJiffies        = u64NanoInterval / (RT_NS_1SEC / HZ);
+    if (pTimer->cJiffies * (RT_NS_1SEC / HZ) != u64NanoInterval)
+        pTimer->cJiffies    = 0;
+    spin_lock_init(&pTimer->ChgIntLock);
+
+    for (iCpu = 0; iCpu < cCpus; iCpu++)
+    {
+#ifdef RTTIMER_LINUX_WITH_HRTIMER
+        if (pTimer->fHighRes)
+        {
+            hrtimer_init(&pTimer->aSubTimers[iCpu].u.Hr.LnxTimer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
+            pTimer->aSubTimers[iCpu].u.Hr.LnxTimer.function     = rtTimerLinuxHrCallback;
+        }
+        else
+#endif
+        {
+#if RTLNX_VER_MIN(4,15,0)
+            timer_setup(&pTimer->aSubTimers[iCpu].u.Std.LnxTimer, rtTimerLinuxStdCallback, TIMER_PINNED);
+#elif RTLNX_VER_MIN(4,8,0)
+            init_timer_pinned(&pTimer->aSubTimers[iCpu].u.Std.LnxTimer);
+#else
+            init_timer(&pTimer->aSubTimers[iCpu].u.Std.LnxTimer);
+#endif
+#if RTLNX_VER_MAX(4,15,0)
+            pTimer->aSubTimers[iCpu].u.Std.LnxTimer.data        = (unsigned long)&pTimer->aSubTimers[iCpu];
+            pTimer->aSubTimers[iCpu].u.Std.LnxTimer.function    = rtTimerLinuxStdCallback;
+#endif
+            pTimer->aSubTimers[iCpu].u.Std.LnxTimer.expires     = jiffies;
+            pTimer->aSubTimers[iCpu].u.Std.u64NextTS            = 0;
+        }
+        pTimer->aSubTimers[iCpu].iTick      = 0;
+        pTimer->aSubTimers[iCpu].pParent    = pTimer;
+        pTimer->aSubTimers[iCpu].enmState   = RTTIMERLNXSTATE_STOPPED;
+    }
+
+#ifdef CONFIG_SMP
+    /*
+     * If this is running on ALL cpus, we'll have to register a callback
+     * for MP events (so timers can be started/stopped on cpus going
+     * online/offline). We also create the spinlock for synchronizing
+     * stop/start/mp-event.
+     */
+    if (cCpus > 1)
+    {
+        int rc = RTSpinlockCreate(&pTimer->hSpinlock, RTSPINLOCK_FLAGS_INTERRUPT_SAFE, "RTTimerLnx");
+        if (RT_SUCCESS(rc))
+            rc = RTMpNotificationRegister(rtTimerLinuxMpEvent, pTimer);
+        else
+            pTimer->hSpinlock = NIL_RTSPINLOCK;
+        if (RT_FAILURE(rc))
+        {
+            RTTimerDestroy(pTimer);
+            IPRT_LINUX_RESTORE_EFL_AC();
+            return rc;
+        }
+    }
+#endif /* CONFIG_SMP */
+
+    RTTIMERLNX_LOG(("create %p hires=%d fFlags=%#x cCpus=%u\n", pTimer, pTimer->fHighRes, fFlags, cCpus));
+    *ppTimer = pTimer;
+    IPRT_LINUX_RESTORE_EFL_AC();
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTTimerCreateEx);
+
+
+RTDECL(uint32_t) RTTimerGetSystemGranularity(void)
+{
+#if 0 /** @todo Not sure if this is what we want or not... Add new API for
+       *        querying the resolution of the high res timers? */
+    struct timespec Ts;
+    int rc;
+    IPRT_LINUX_SAVE_EFL_AC();
+    rc = hrtimer_get_res(CLOCK_MONOTONIC, &Ts);
+    IPRT_LINUX_RESTORE_EFL_AC();
+    if (!rc)
+    {
+        Assert(!Ts.tv_sec);
+        return Ts.tv_nsec;
+    }
+#endif
+    /* */
+#if RTLNX_VER_MAX(4,9,0) || RTLNX_VER_MIN(4,13,0)
+    /* On 4.9, 4.10 and 4.12 we've observed tstRTR0Timer failures of the omni timer tests
+       where we get about half of the ticks we want.  The failing test is using this value
+       as interval.  So, this is a very very crude hack to try make omni timers work
+       correctly without actually knowing what's going wrong... */
+    return RT_NS_1SEC * 2 / HZ; /* ns */
+#else
+    return RT_NS_1SEC / HZ; /* ns */
+#endif
+}
+RT_EXPORT_SYMBOL(RTTimerGetSystemGranularity);
+
+
+RTDECL(int) RTTimerRequestSystemGranularity(uint32_t u32Request, uint32_t *pu32Granted)
+{
+    RT_NOREF_PV(u32Request); RT_NOREF_PV(*pu32Granted);
+    return VERR_NOT_SUPPORTED;
+}
+RT_EXPORT_SYMBOL(RTTimerRequestSystemGranularity);
+
+
+RTDECL(int) RTTimerReleaseSystemGranularity(uint32_t u32Granted)
+{
+    RT_NOREF_PV(u32Granted);
+    return VERR_NOT_SUPPORTED;
+}
+RT_EXPORT_SYMBOL(RTTimerReleaseSystemGranularity);
+
+
+RTDECL(bool) RTTimerCanDoHighResolution(void)
+{
+#ifdef RTTIMER_LINUX_WITH_HRTIMER
+    return true;
+#else
+    return false;
+#endif
+}
+RT_EXPORT_SYMBOL(RTTimerCanDoHighResolution);
+
diff --git a/src/VBox/Runtime/r0drv/linux/waitqueue-r0drv-linux.h b/src/VBox/Runtime/r0drv/linux/waitqueue-r0drv-linux.h
new file mode 100644
index 00000000..e0f2faf8
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/linux/waitqueue-r0drv-linux.h
@@ -0,0 +1,292 @@
+/* $Id: waitqueue-r0drv-linux.h $ */
+/** @file
+ * IPRT - Linux Ring-0 Driver Helpers for Abstracting Wait Queues,
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+#ifndef IPRT_INCLUDED_SRC_r0drv_linux_waitqueue_r0drv_linux_h
+#define IPRT_INCLUDED_SRC_r0drv_linux_waitqueue_r0drv_linux_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include "the-linux-kernel.h"
+
+#include <iprt/asm-math.h>
+#include <iprt/err.h>
+#include <iprt/string.h>
+#include <iprt/time.h>
+
+/** The resolution (nanoseconds) specified when using
+ *  schedule_hrtimeout_range. */
+#define RTR0SEMLNXWAIT_RESOLUTION   50000
+
+
+/**
+ * Kernel mode Linux wait state structure.
+ */
+typedef struct RTR0SEMLNXWAIT
+{
+    /** The wait queue entry. */
+#if RTLNX_VER_MIN(4,13,0) || RTLNX_SUSE_MAJ_PREREQ(12, 4) || RTLNX_SUSE_MAJ_PREREQ(15, 0)
+    wait_queue_entry_t WaitQE;
+#else
+    wait_queue_t    WaitQE;
+#endif
+    /** The absolute timeout given as nano seconds since the start of the
+     *  monotonic clock. */
+    uint64_t        uNsAbsTimeout;
+    /** The timeout in nano seconds relative to the start of the wait. */
+    uint64_t        cNsRelTimeout;
+    /** The native timeout value. */
+    union
+    {
+#ifdef IPRT_LINUX_HAS_HRTIMER
+        /** The timeout when fHighRes is true. Absolute, so no updating. */
+        ktime_t     KtTimeout;
+#endif
+        /** The timeout when fHighRes is false.  Updated after waiting. */
+        long        lTimeout;
+    } u;
+    /** Set if we use high resolution timeouts. */
+    bool            fHighRes;
+    /** Set if it's an indefinite wait. */
+    bool            fIndefinite;
+    /** Set if we've already timed out.
+     * Set by rtR0SemLnxWaitDoIt and read by rtR0SemLnxWaitHasTimedOut. */
+    bool            fTimedOut;
+    /** TASK_INTERRUPTIBLE or TASK_UNINTERRUPTIBLE. */
+    int             iWaitState;
+    /** The wait queue. */
+    wait_queue_head_t *pWaitQueue;
+} RTR0SEMLNXWAIT;
+/** Pointer to a linux wait state. */
+typedef RTR0SEMLNXWAIT *PRTR0SEMLNXWAIT;
+
+
+/**
+ * Initializes a wait.
+ *
+ * The caller MUST check the wait condition BEFORE calling this function or the
+ * timeout logic will be flawed.
+ *
+ * @returns VINF_SUCCESS or VERR_TIMEOUT.
+ * @param   pWait               The wait structure.
+ * @param   fFlags              The wait flags.
+ * @param   uTimeout            The timeout.
+ * @param   pWaitQueue          The wait queue head.
+ */
+DECLINLINE(int) rtR0SemLnxWaitInit(PRTR0SEMLNXWAIT pWait, uint32_t fFlags, uint64_t uTimeout,
+                                   wait_queue_head_t *pWaitQueue)
+{
+    /*
+     * Process the flags and timeout.
+     */
+    if (!(fFlags & RTSEMWAIT_FLAGS_INDEFINITE))
+    {
+/** @todo optimize: millisecs -> nanosecs -> millisec -> jiffies */
+        if (fFlags & RTSEMWAIT_FLAGS_MILLISECS)
+            uTimeout = uTimeout < UINT64_MAX / RT_US_1SEC * RT_US_1SEC
+                     ? uTimeout * RT_US_1SEC
+                     : UINT64_MAX;
+        if (uTimeout == UINT64_MAX)
+            fFlags |= RTSEMWAIT_FLAGS_INDEFINITE;
+        else
+        {
+            uint64_t u64Now;
+            if (fFlags & RTSEMWAIT_FLAGS_RELATIVE)
+            {
+                if (uTimeout == 0)
+                    return VERR_TIMEOUT;
+
+                u64Now = RTTimeSystemNanoTS();
+                pWait->cNsRelTimeout = uTimeout;
+                pWait->uNsAbsTimeout = u64Now + uTimeout;
+                if (pWait->uNsAbsTimeout < u64Now) /* overflow */
+                    fFlags |= RTSEMWAIT_FLAGS_INDEFINITE;
+            }
+            else
+            {
+                u64Now = RTTimeSystemNanoTS();
+                if (u64Now >= uTimeout)
+                    return VERR_TIMEOUT;
+
+                pWait->cNsRelTimeout = uTimeout - u64Now;
+                pWait->uNsAbsTimeout = uTimeout;
+            }
+        }
+    }
+
+    if (!(fFlags & RTSEMWAIT_FLAGS_INDEFINITE))
+    {
+        pWait->fIndefinite      = false;
+#ifdef IPRT_LINUX_HAS_HRTIMER
+        if (   (fFlags & (RTSEMWAIT_FLAGS_NANOSECS | RTSEMWAIT_FLAGS_ABSOLUTE))
+            || pWait->cNsRelTimeout < RT_NS_1SEC / HZ * 4)
+        {
+            pWait->fHighRes     = true;
+# if BITS_PER_LONG < 64
+            if (   KTIME_SEC_MAX <= LONG_MAX
+                && pWait->uNsAbsTimeout >= KTIME_SEC_MAX * RT_NS_1SEC_64 + (RT_NS_1SEC - 1))
+                fFlags |= RTSEMWAIT_FLAGS_INDEFINITE;
+            else
+# endif
+                pWait->u.KtTimeout  = ns_to_ktime(pWait->uNsAbsTimeout);
+        }
+        else
+#endif
+        {
+            uint64_t cJiffies = ASMMultU64ByU32DivByU32(pWait->cNsRelTimeout, HZ, RT_NS_1SEC);
+            if (cJiffies >= MAX_JIFFY_OFFSET)
+                fFlags |= RTSEMWAIT_FLAGS_INDEFINITE;
+            else
+            {
+                pWait->u.lTimeout   = (long)cJiffies;
+                pWait->fHighRes     = false;
+            }
+        }
+    }
+
+    if (fFlags & RTSEMWAIT_FLAGS_INDEFINITE)
+    {
+        pWait->fIndefinite      = true;
+        pWait->fHighRes         = false;
+        pWait->uNsAbsTimeout    = UINT64_MAX;
+        pWait->cNsRelTimeout    = UINT64_MAX;
+        pWait->u.lTimeout       = LONG_MAX;
+    }
+
+    pWait->fTimedOut   = false;
+
+    /*
+     * Initialize the wait queue related bits.
+     */
+#if RTLNX_VER_MIN(2,5,39)
+    init_wait((&pWait->WaitQE));
+#else
+    RT_ZERO(pWait->WaitQE);
+    init_waitqueue_entry((&pWait->WaitQE), current);
+#endif
+    pWait->pWaitQueue = pWaitQueue;
+    pWait->iWaitState = fFlags & RTSEMWAIT_FLAGS_INTERRUPTIBLE
+                      ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE;
+
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Prepares the next wait.
+ *
+ * This must be called before rtR0SemLnxWaitDoIt, and the caller should check
+ * the exit conditions in-between the two calls.
+ *
+ * @param   pWait               The wait structure.
+ */
+DECLINLINE(void) rtR0SemLnxWaitPrepare(PRTR0SEMLNXWAIT pWait)
+{
+    /* Make everything thru schedule*() atomic scheduling wise. (Is this correct?) */
+    prepare_to_wait(pWait->pWaitQueue, &pWait->WaitQE, pWait->iWaitState);
+}
+
+
+/**
+ * Do the actual wait.
+ *
+ * @param   pWait               The wait structure.
+ */
+DECLINLINE(void) rtR0SemLnxWaitDoIt(PRTR0SEMLNXWAIT pWait)
+{
+    if (pWait->fIndefinite)
+        schedule();
+#ifdef IPRT_LINUX_HAS_HRTIMER
+    else if (pWait->fHighRes)
+    {
+        int rc = schedule_hrtimeout_range(&pWait->u.KtTimeout, HRTIMER_MODE_ABS, RTR0SEMLNXWAIT_RESOLUTION);
+        if (!rc)
+            pWait->fTimedOut = true;
+    }
+#endif
+    else
+    {
+        pWait->u.lTimeout = schedule_timeout(pWait->u.lTimeout);
+        if (pWait->u.lTimeout <= 0)
+            pWait->fTimedOut = true;
+    }
+    after_wait((&pWait->WaitQE));
+}
+
+
+/**
+ * Checks if a linux wait was interrupted.
+ *
+ * @returns true / false
+ * @param   pWait               The wait structure.
+ * @remarks This shall be called before the first rtR0SemLnxWaitDoIt().
+ */
+DECLINLINE(bool) rtR0SemLnxWaitWasInterrupted(PRTR0SEMLNXWAIT pWait)
+{
+    return pWait->iWaitState == TASK_INTERRUPTIBLE
+        && signal_pending(current);
+}
+
+
+/**
+ * Checks if a linux wait has timed out.
+ *
+ * @returns true / false
+ * @param   pWait               The wait structure.
+ */
+DECLINLINE(bool) rtR0SemLnxWaitHasTimedOut(PRTR0SEMLNXWAIT pWait)
+{
+    return pWait->fTimedOut;
+}
+
+
+/**
+ * Deletes a linux wait.
+ *
+ * @param   pWait               The wait structure.
+ */
+DECLINLINE(void) rtR0SemLnxWaitDelete(PRTR0SEMLNXWAIT pWait)
+{
+    finish_wait(pWait->pWaitQueue, &pWait->WaitQE);
+}
+
+
+/**
+ * Gets the max resolution of the timeout machinery.
+ *
+ * @returns Resolution specified in nanoseconds.
+ */
+DECLINLINE(uint32_t) rtR0SemLnxWaitGetResolution(void)
+{
+#ifdef IPRT_LINUX_HAS_HRTIMER
+    return RTR0SEMLNXWAIT_RESOLUTION;
+#else
+    return RT_NS_1SEC / HZ; /* ns */
+#endif
+}
+
+#endif /* !IPRT_INCLUDED_SRC_r0drv_linux_waitqueue_r0drv_linux_h */
+
diff --git a/src/VBox/Runtime/r0drv/memobj-r0drv.cpp b/src/VBox/Runtime/r0drv/memobj-r0drv.cpp
new file mode 100644
index 00000000..c91e9833
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/memobj-r0drv.cpp
@@ -0,0 +1,825 @@
+/* $Id: memobj-r0drv.cpp $ */
+/** @file
+ * IPRT - Ring-0 Memory Objects, Common Code.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define LOG_GROUP RTLOGGROUP_DEFAULT /// @todo RTLOGGROUP_MEM
+#define RTMEM_NO_WRAP_TO_EF_APIS /* circular dependency otherwise. */
+#include <iprt/memobj.h>
+#include "internal/iprt.h"
+
+#include <iprt/alloc.h>
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/log.h>
+#include <iprt/mp.h>
+#include <iprt/param.h>
+#include <iprt/process.h>
+#include <iprt/thread.h>
+
+#include "internal/memobj.h"
+
+
+/**
+ * Internal function for allocating a new memory object.
+ *
+ * @returns The allocated and initialized handle.
+ * @param   cbSelf      The size of the memory object handle. 0 mean default size.
+ * @param   enmType     The memory object type.
+ * @param   pv          The memory object mapping.
+ * @param   cb          The size of the memory object.
+ */
+DECLHIDDEN(PRTR0MEMOBJINTERNAL) rtR0MemObjNew(size_t cbSelf, RTR0MEMOBJTYPE enmType, void *pv, size_t cb)
+{
+    PRTR0MEMOBJINTERNAL pNew;
+
+    /* validate the size */
+    if (!cbSelf)
+        cbSelf = sizeof(*pNew);
+    Assert(cbSelf >= sizeof(*pNew));
+    Assert(cbSelf == (uint32_t)cbSelf);
+    AssertMsg(RT_ALIGN_Z(cb, PAGE_SIZE) == cb, ("%#zx\n", cb));
+
+    /*
+     * Allocate and initialize the object.
+     */
+    pNew = (PRTR0MEMOBJINTERNAL)RTMemAllocZ(cbSelf);
+    if (pNew)
+    {
+        pNew->u32Magic  = RTR0MEMOBJ_MAGIC;
+        pNew->cbSelf    = (uint32_t)cbSelf;
+        pNew->enmType   = enmType;
+        pNew->fFlags    = 0;
+        pNew->cb        = cb;
+        pNew->pv        = pv;
+    }
+    return pNew;
+}
+
+
+/**
+ * Deletes an incomplete memory object.
+ *
+ * This is for cleaning up after failures during object creation.
+ *
+ * @param   pMem    The incomplete memory object to delete.
+ */
+DECLHIDDEN(void) rtR0MemObjDelete(PRTR0MEMOBJINTERNAL pMem)
+{
+    if (pMem)
+    {
+        ASMAtomicUoWriteU32(&pMem->u32Magic, ~RTR0MEMOBJ_MAGIC);
+        pMem->enmType = RTR0MEMOBJTYPE_END;
+        RTMemFree(pMem);
+    }
+}
+
+
+/**
+ * Links a mapping object to a primary object.
+ *
+ * @returns IPRT status code.
+ * @retval  VINF_SUCCESS on success.
+ * @retval  VINF_NO_MEMORY if we couldn't expand the mapping array of the parent.
+ * @param   pParent     The parent (primary) memory object.
+ * @param   pChild      The child (mapping) memory object.
+ */
+static int rtR0MemObjLink(PRTR0MEMOBJINTERNAL pParent, PRTR0MEMOBJINTERNAL pChild)
+{
+    uint32_t i;
+
+    /* sanity */
+    Assert(rtR0MemObjIsMapping(pChild));
+    Assert(!rtR0MemObjIsMapping(pParent));
+
+    /* expand the array? */
+    i = pParent->uRel.Parent.cMappings;
+    if (i >= pParent->uRel.Parent.cMappingsAllocated)
+    {
+        void *pv = RTMemRealloc(pParent->uRel.Parent.papMappings,
+                                (i + 32) * sizeof(pParent->uRel.Parent.papMappings[0]));
+        if (!pv)
+            return VERR_NO_MEMORY;
+        pParent->uRel.Parent.papMappings = (PPRTR0MEMOBJINTERNAL)pv;
+        pParent->uRel.Parent.cMappingsAllocated = i + 32;
+        Assert(i == pParent->uRel.Parent.cMappings);
+    }
+
+    /* do the linking. */
+    pParent->uRel.Parent.papMappings[i] = pChild;
+    pParent->uRel.Parent.cMappings++;
+    pChild->uRel.Child.pParent = pParent;
+
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Checks if this is mapping or not.
+ *
+ * @returns true if it's a mapping, otherwise false.
+ * @param   MemObj      The ring-0 memory object handle.
+ */
+RTR0DECL(bool) RTR0MemObjIsMapping(RTR0MEMOBJ MemObj)
+{
+    /* Validate the object handle. */
+    PRTR0MEMOBJINTERNAL pMem;
+    AssertPtrReturn(MemObj, false);
+    pMem = (PRTR0MEMOBJINTERNAL)MemObj;
+    AssertMsgReturn(pMem->u32Magic == RTR0MEMOBJ_MAGIC, ("%p: %#x\n", pMem, pMem->u32Magic), false);
+    AssertMsgReturn(pMem->enmType > RTR0MEMOBJTYPE_INVALID && pMem->enmType < RTR0MEMOBJTYPE_END, ("%p: %d\n", pMem, pMem->enmType), false);
+
+    /* hand it on to the inlined worker. */
+    return rtR0MemObjIsMapping(pMem);
+}
+RT_EXPORT_SYMBOL(RTR0MemObjIsMapping);
+
+
+/**
+ * Gets the address of a ring-0 memory object.
+ *
+ * @returns The address of the memory object.
+ * @returns NULL if the handle is invalid (asserts in strict builds) or if there isn't any mapping.
+ * @param   MemObj  The ring-0 memory object handle.
+ */
+RTR0DECL(void *) RTR0MemObjAddress(RTR0MEMOBJ MemObj)
+{
+    /* Validate the object handle. */
+    PRTR0MEMOBJINTERNAL pMem;
+    if (RT_UNLIKELY(MemObj == NIL_RTR0MEMOBJ))
+        return NULL;
+    AssertPtrReturn(MemObj, NULL);
+    pMem = (PRTR0MEMOBJINTERNAL)MemObj;
+    AssertMsgReturn(pMem->u32Magic == RTR0MEMOBJ_MAGIC, ("%p: %#x\n", pMem, pMem->u32Magic), NULL);
+    AssertMsgReturn(pMem->enmType > RTR0MEMOBJTYPE_INVALID && pMem->enmType < RTR0MEMOBJTYPE_END, ("%p: %d\n", pMem, pMem->enmType), NULL);
+
+    /* return the mapping address. */
+    return pMem->pv;
+}
+RT_EXPORT_SYMBOL(RTR0MemObjAddress);
+
+
+/**
+ * Gets the ring-3 address of a ring-0 memory object.
+ *
+ * This only applies to ring-0 memory object with ring-3 mappings of some kind, i.e.
+ * locked user memory, reserved user address space and user mappings. This API should
+ * not be used on any other objects.
+ *
+ * @returns The address of the memory object.
+ * @returns NIL_RTR3PTR if the handle is invalid or if it's not an object with a ring-3 mapping.
+ *          Strict builds will assert in both cases.
+ * @param   MemObj  The ring-0 memory object handle.
+ */
+RTR0DECL(RTR3PTR) RTR0MemObjAddressR3(RTR0MEMOBJ MemObj)
+{
+    PRTR0MEMOBJINTERNAL pMem;
+
+    /* Validate the object handle. */
+    if (RT_UNLIKELY(MemObj == NIL_RTR0MEMOBJ))
+        return NIL_RTR3PTR;
+    AssertPtrReturn(MemObj, NIL_RTR3PTR);
+    pMem = (PRTR0MEMOBJINTERNAL)MemObj;
+    AssertMsgReturn(pMem->u32Magic == RTR0MEMOBJ_MAGIC, ("%p: %#x\n", pMem, pMem->u32Magic), NIL_RTR3PTR);
+    AssertMsgReturn(pMem->enmType > RTR0MEMOBJTYPE_INVALID && pMem->enmType < RTR0MEMOBJTYPE_END, ("%p: %d\n", pMem, pMem->enmType), NIL_RTR3PTR);
+    if (RT_UNLIKELY(    (   pMem->enmType != RTR0MEMOBJTYPE_MAPPING
+                         || pMem->u.Mapping.R0Process == NIL_RTR0PROCESS)
+                    &&  (   pMem->enmType != RTR0MEMOBJTYPE_LOCK
+                         || pMem->u.Lock.R0Process == NIL_RTR0PROCESS)
+                    &&  (   pMem->enmType != RTR0MEMOBJTYPE_PHYS_NC
+                         || pMem->u.Lock.R0Process == NIL_RTR0PROCESS)
+                    &&  (   pMem->enmType != RTR0MEMOBJTYPE_RES_VIRT
+                         || pMem->u.ResVirt.R0Process == NIL_RTR0PROCESS)))
+        return NIL_RTR3PTR;
+
+    /* return the mapping address. */
+    return (RTR3PTR)pMem->pv;
+}
+RT_EXPORT_SYMBOL(RTR0MemObjAddressR3);
+
+
+/**
+ * Gets the size of a ring-0 memory object.
+ *
+ * The returned value may differ from the one specified to the API creating the
+ * object because of alignment adjustments.  The minimal alignment currently
+ * employed by any API is PAGE_SIZE, so the result can safely be shifted by
+ * PAGE_SHIFT to calculate a page count.
+ *
+ * @returns The object size.
+ * @returns 0 if the handle is invalid (asserts in strict builds) or if there isn't any mapping.
+ * @param   MemObj  The ring-0 memory object handle.
+ */
+RTR0DECL(size_t) RTR0MemObjSize(RTR0MEMOBJ MemObj)
+{
+    PRTR0MEMOBJINTERNAL pMem;
+
+    /* Validate the object handle. */
+    if (RT_UNLIKELY(MemObj == NIL_RTR0MEMOBJ))
+        return 0;
+    AssertPtrReturn(MemObj, 0);
+    pMem = (PRTR0MEMOBJINTERNAL)MemObj;
+    AssertMsgReturn(pMem->u32Magic == RTR0MEMOBJ_MAGIC, ("%p: %#x\n", pMem, pMem->u32Magic), 0);
+    AssertMsgReturn(pMem->enmType > RTR0MEMOBJTYPE_INVALID && pMem->enmType < RTR0MEMOBJTYPE_END, ("%p: %d\n", pMem, pMem->enmType), 0);
+    AssertMsg(RT_ALIGN_Z(pMem->cb, PAGE_SIZE) == pMem->cb, ("%#zx\n", pMem->cb));
+
+    /* return the size. */
+    return pMem->cb;
+}
+RT_EXPORT_SYMBOL(RTR0MemObjSize);
+
+
+/**
+ * Get the physical address of an page in the memory object.
+ *
+ * @returns The physical address.
+ * @returns NIL_RTHCPHYS if the object doesn't contain fixed physical pages.
+ * @returns NIL_RTHCPHYS if the iPage is out of range.
+ * @returns NIL_RTHCPHYS if the object handle isn't valid.
+ * @param   MemObj  The ring-0 memory object handle.
+ * @param   iPage   The page number within the object.
+ */
+/* Work around gcc bug 55940 */
+#if defined(__GNUC__) && defined(RT_ARCH_X86) && (__GNUC__ * 100 + __GNUC_MINOR__) == 407
+ __attribute__((__optimize__ ("no-shrink-wrap")))
+#endif
+RTR0DECL(RTHCPHYS) RTR0MemObjGetPagePhysAddr(RTR0MEMOBJ MemObj, size_t iPage)
+{
+    /* Validate the object handle. */
+    PRTR0MEMOBJINTERNAL pMem;
+    size_t cPages;
+    AssertPtrReturn(MemObj, NIL_RTHCPHYS);
+    pMem = (PRTR0MEMOBJINTERNAL)MemObj;
+    AssertReturn(pMem->u32Magic == RTR0MEMOBJ_MAGIC, NIL_RTHCPHYS);
+    AssertReturn(pMem->enmType > RTR0MEMOBJTYPE_INVALID && pMem->enmType < RTR0MEMOBJTYPE_END, NIL_RTHCPHYS);
+    AssertMsgReturn(pMem->u32Magic == RTR0MEMOBJ_MAGIC, ("%p: %#x\n", pMem, pMem->u32Magic), NIL_RTHCPHYS);
+    AssertMsgReturn(pMem->enmType > RTR0MEMOBJTYPE_INVALID && pMem->enmType < RTR0MEMOBJTYPE_END, ("%p: %d\n", pMem, pMem->enmType), NIL_RTHCPHYS);
+    cPages = (pMem->cb >> PAGE_SHIFT);
+    if (iPage >= cPages)
+    {
+        /* permit: while (RTR0MemObjGetPagePhysAddr(pMem, iPage++) != NIL_RTHCPHYS) {} */
+        if (iPage == cPages)
+            return NIL_RTHCPHYS;
+        AssertReturn(iPage < (pMem->cb >> PAGE_SHIFT), NIL_RTHCPHYS);
+    }
+
+    /*
+     * We know the address of physically contiguous allocations and mappings.
+     */
+    if (pMem->enmType == RTR0MEMOBJTYPE_CONT)
+        return pMem->u.Cont.Phys + iPage * PAGE_SIZE;
+    if (pMem->enmType == RTR0MEMOBJTYPE_PHYS)
+        return pMem->u.Phys.PhysBase + iPage * PAGE_SIZE;
+
+    /*
+     * Do the job.
+     */
+    return rtR0MemObjNativeGetPagePhysAddr(pMem, iPage);
+}
+RT_EXPORT_SYMBOL(RTR0MemObjGetPagePhysAddr);
+
+
+/**
+ * Frees a ring-0 memory object.
+ *
+ * @returns IPRT status code.
+ * @retval  VERR_INVALID_HANDLE if
+ * @param   MemObj          The ring-0 memory object to be freed. NULL is accepted.
+ * @param   fFreeMappings   Whether or not to free mappings of the object.
+ */
+RTR0DECL(int) RTR0MemObjFree(RTR0MEMOBJ MemObj, bool fFreeMappings)
+{
+    /*
+     * Validate the object handle.
+     */
+    PRTR0MEMOBJINTERNAL pMem;
+    int rc;
+
+    if (MemObj == NIL_RTR0MEMOBJ)
+        return VINF_SUCCESS;
+    AssertPtrReturn(MemObj, VERR_INVALID_HANDLE);
+    pMem = (PRTR0MEMOBJINTERNAL)MemObj;
+    AssertReturn(pMem->u32Magic == RTR0MEMOBJ_MAGIC, VERR_INVALID_HANDLE);
+    AssertReturn(pMem->enmType > RTR0MEMOBJTYPE_INVALID && pMem->enmType < RTR0MEMOBJTYPE_END, VERR_INVALID_HANDLE);
+    RT_ASSERT_PREEMPTIBLE();
+
+    /*
+     * Deal with mappings according to fFreeMappings.
+     */
+    if (    !rtR0MemObjIsMapping(pMem)
+        &&  pMem->uRel.Parent.cMappings > 0)
+    {
+        /* fail if not requested to free mappings. */
+        if (!fFreeMappings)
+            return VERR_MEMORY_BUSY;
+
+        while (pMem->uRel.Parent.cMappings > 0)
+        {
+            PRTR0MEMOBJINTERNAL pChild = pMem->uRel.Parent.papMappings[--pMem->uRel.Parent.cMappings];
+            pMem->uRel.Parent.papMappings[pMem->uRel.Parent.cMappings] = NULL;
+
+            /* sanity checks. */
+            AssertPtr(pChild);
+            AssertFatal(pChild->u32Magic == RTR0MEMOBJ_MAGIC);
+            AssertFatal(pChild->enmType > RTR0MEMOBJTYPE_INVALID && pChild->enmType < RTR0MEMOBJTYPE_END);
+            AssertFatal(rtR0MemObjIsMapping(pChild));
+
+            /* free the mapping. */
+            rc = rtR0MemObjNativeFree(pChild);
+            if (RT_FAILURE(rc))
+            {
+                Log(("RTR0MemObjFree: failed to free mapping %p: %p %#zx; rc=%Rrc\n", pChild, pChild->pv, pChild->cb, rc));
+                pMem->uRel.Parent.papMappings[pMem->uRel.Parent.cMappings++] = pChild;
+                return rc;
+            }
+        }
+    }
+
+    /*
+     * Free this object.
+     */
+    rc = rtR0MemObjNativeFree(pMem);
+    if (RT_SUCCESS(rc))
+    {
+        /*
+         * Ok, it was freed just fine. Now, if it's a mapping we'll have to remove it from the parent.
+         */
+        if (rtR0MemObjIsMapping(pMem))
+        {
+            PRTR0MEMOBJINTERNAL pParent = pMem->uRel.Child.pParent;
+            uint32_t i;
+
+            /* sanity checks */
+            AssertPtr(pParent);
+            AssertFatal(pParent->u32Magic == RTR0MEMOBJ_MAGIC);
+            AssertFatal(pParent->enmType > RTR0MEMOBJTYPE_INVALID && pParent->enmType < RTR0MEMOBJTYPE_END);
+            AssertFatal(!rtR0MemObjIsMapping(pParent));
+            AssertFatal(pParent->uRel.Parent.cMappings > 0);
+            AssertPtr(pParent->uRel.Parent.papMappings);
+
+            /* locate and remove from the array of mappings. */
+            i = pParent->uRel.Parent.cMappings;
+            while (i-- > 0)
+            {
+                if (pParent->uRel.Parent.papMappings[i] == pMem)
+                {
+                    pParent->uRel.Parent.papMappings[i] = pParent->uRel.Parent.papMappings[--pParent->uRel.Parent.cMappings];
+                    break;
+                }
+            }
+            Assert(i != UINT32_MAX);
+        }
+        else
+            Assert(pMem->uRel.Parent.cMappings == 0);
+
+        /*
+         * Finally, destroy the handle.
+         */
+        pMem->u32Magic++;
+        pMem->enmType = RTR0MEMOBJTYPE_END;
+        if (!rtR0MemObjIsMapping(pMem))
+            RTMemFree(pMem->uRel.Parent.papMappings);
+        RTMemFree(pMem);
+    }
+    else
+        Log(("RTR0MemObjFree: failed to free %p: %d %p %#zx; rc=%Rrc\n",
+             pMem, pMem->enmType, pMem->pv, pMem->cb, rc));
+    return rc;
+}
+RT_EXPORT_SYMBOL(RTR0MemObjFree);
+
+
+
+RTR0DECL(int) RTR0MemObjAllocPageTag(PRTR0MEMOBJ pMemObj, size_t cb, bool fExecutable, const char *pszTag)
+{
+    /* sanity checks. */
+    const size_t cbAligned = RT_ALIGN_Z(cb, PAGE_SIZE);
+    AssertPtrReturn(pMemObj, VERR_INVALID_POINTER);
+    *pMemObj = NIL_RTR0MEMOBJ;
+    AssertReturn(cb > 0, VERR_INVALID_PARAMETER);
+    AssertReturn(cb <= cbAligned, VERR_INVALID_PARAMETER);
+    RT_ASSERT_PREEMPTIBLE();
+
+    RT_NOREF_PV(pszTag);
+
+    /* do the allocation. */
+    return rtR0MemObjNativeAllocPage(pMemObj, cbAligned, fExecutable);
+}
+RT_EXPORT_SYMBOL(RTR0MemObjAllocPageTag);
+
+
+RTR0DECL(int) RTR0MemObjAllocLowTag(PRTR0MEMOBJ pMemObj, size_t cb, bool fExecutable, const char *pszTag)
+{
+    /* sanity checks. */
+    const size_t cbAligned = RT_ALIGN_Z(cb, PAGE_SIZE);
+    AssertPtrReturn(pMemObj, VERR_INVALID_POINTER);
+    *pMemObj = NIL_RTR0MEMOBJ;
+    AssertReturn(cb > 0, VERR_INVALID_PARAMETER);
+    AssertReturn(cb <= cbAligned, VERR_INVALID_PARAMETER);
+    RT_ASSERT_PREEMPTIBLE();
+
+    RT_NOREF_PV(pszTag);
+
+    /* do the allocation. */
+    return rtR0MemObjNativeAllocLow(pMemObj, cbAligned, fExecutable);
+}
+RT_EXPORT_SYMBOL(RTR0MemObjAllocLowTag);
+
+
+RTR0DECL(int) RTR0MemObjAllocContTag(PRTR0MEMOBJ pMemObj, size_t cb, bool fExecutable, const char *pszTag)
+{
+    /* sanity checks. */
+    const size_t cbAligned = RT_ALIGN_Z(cb, PAGE_SIZE);
+    AssertPtrReturn(pMemObj, VERR_INVALID_POINTER);
+    *pMemObj = NIL_RTR0MEMOBJ;
+    AssertReturn(cb > 0, VERR_INVALID_PARAMETER);
+    AssertReturn(cb <= cbAligned, VERR_INVALID_PARAMETER);
+    RT_ASSERT_PREEMPTIBLE();
+
+    RT_NOREF_PV(pszTag);
+
+    /* do the allocation. */
+    return rtR0MemObjNativeAllocCont(pMemObj, cbAligned, fExecutable);
+}
+RT_EXPORT_SYMBOL(RTR0MemObjAllocContTag);
+
+
+RTR0DECL(int) RTR0MemObjLockUserTag(PRTR0MEMOBJ pMemObj, RTR3PTR R3Ptr, size_t cb,
+                                    uint32_t fAccess, RTR0PROCESS R0Process, const char *pszTag)
+{
+    /* sanity checks. */
+    const size_t cbAligned = RT_ALIGN_Z(cb + (R3Ptr & PAGE_OFFSET_MASK), PAGE_SIZE);
+    RTR3PTR const R3PtrAligned = (R3Ptr & ~(RTR3PTR)PAGE_OFFSET_MASK);
+    AssertPtrReturn(pMemObj, VERR_INVALID_POINTER);
+    *pMemObj = NIL_RTR0MEMOBJ;
+    AssertReturn(cb > 0, VERR_INVALID_PARAMETER);
+    AssertReturn(cb <= cbAligned, VERR_INVALID_PARAMETER);
+    if (R0Process == NIL_RTR0PROCESS)
+        R0Process = RTR0ProcHandleSelf();
+    AssertReturn(!(fAccess & ~(RTMEM_PROT_READ | RTMEM_PROT_WRITE)), VERR_INVALID_PARAMETER);
+    AssertReturn(fAccess, VERR_INVALID_PARAMETER);
+    RT_ASSERT_PREEMPTIBLE();
+
+    RT_NOREF_PV(pszTag);
+
+    /* do the locking. */
+    return rtR0MemObjNativeLockUser(pMemObj, R3PtrAligned, cbAligned, fAccess, R0Process);
+}
+RT_EXPORT_SYMBOL(RTR0MemObjLockUserTag);
+
+
+RTR0DECL(int) RTR0MemObjLockKernelTag(PRTR0MEMOBJ pMemObj, void *pv, size_t cb, uint32_t fAccess, const char *pszTag)
+{
+    /* sanity checks. */
+    const size_t cbAligned = RT_ALIGN_Z(cb + ((uintptr_t)pv & PAGE_OFFSET_MASK), PAGE_SIZE);
+    void * const pvAligned = (void *)((uintptr_t)pv & ~(uintptr_t)PAGE_OFFSET_MASK);
+    AssertPtrReturn(pMemObj, VERR_INVALID_POINTER);
+    *pMemObj = NIL_RTR0MEMOBJ;
+    AssertReturn(cb > 0, VERR_INVALID_PARAMETER);
+    AssertReturn(cb <= cbAligned, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(pvAligned, VERR_INVALID_POINTER);
+    AssertReturn(!(fAccess & ~(RTMEM_PROT_READ | RTMEM_PROT_WRITE)), VERR_INVALID_PARAMETER);
+    AssertReturn(fAccess, VERR_INVALID_PARAMETER);
+    RT_ASSERT_PREEMPTIBLE();
+
+    RT_NOREF_PV(pszTag);
+
+    /* do the allocation. */
+    return rtR0MemObjNativeLockKernel(pMemObj, pvAligned, cbAligned, fAccess);
+}
+RT_EXPORT_SYMBOL(RTR0MemObjLockKernelTag);
+
+
+RTR0DECL(int) RTR0MemObjAllocPhysTag(PRTR0MEMOBJ pMemObj, size_t cb, RTHCPHYS PhysHighest, const char *pszTag)
+{
+    /* sanity checks. */
+    const size_t cbAligned = RT_ALIGN_Z(cb, PAGE_SIZE);
+    AssertPtrReturn(pMemObj, VERR_INVALID_POINTER);
+    *pMemObj = NIL_RTR0MEMOBJ;
+    AssertReturn(cb > 0, VERR_INVALID_PARAMETER);
+    AssertReturn(cb <= cbAligned, VERR_INVALID_PARAMETER);
+    AssertReturn(PhysHighest >= cb, VERR_INVALID_PARAMETER);
+    RT_ASSERT_PREEMPTIBLE();
+
+    RT_NOREF_PV(pszTag);
+
+    /* do the allocation. */
+    return rtR0MemObjNativeAllocPhys(pMemObj, cbAligned, PhysHighest, PAGE_SIZE /* page aligned */);
+}
+RT_EXPORT_SYMBOL(RTR0MemObjAllocPhysTag);
+
+
+RTR0DECL(int) RTR0MemObjAllocPhysExTag(PRTR0MEMOBJ pMemObj, size_t cb, RTHCPHYS PhysHighest, size_t uAlignment, const char *pszTag)
+{
+    /* sanity checks. */
+    const size_t cbAligned = RT_ALIGN_Z(cb, PAGE_SIZE);
+    AssertPtrReturn(pMemObj, VERR_INVALID_POINTER);
+    *pMemObj = NIL_RTR0MEMOBJ;
+    AssertReturn(cb > 0, VERR_INVALID_PARAMETER);
+    AssertReturn(cb <= cbAligned, VERR_INVALID_PARAMETER);
+    AssertReturn(PhysHighest >= cb, VERR_INVALID_PARAMETER);
+    if (uAlignment == 0)
+        uAlignment = PAGE_SIZE;
+    AssertReturn(    uAlignment == PAGE_SIZE
+                 ||  uAlignment == _2M
+                 ||  uAlignment == _4M
+                 ||  uAlignment == _1G,
+                 VERR_INVALID_PARAMETER);
+#if HC_ARCH_BITS == 32
+    /* Memory allocated in this way is typically mapped into kernel space as well; simply
+       don't allow this on 32 bits hosts as the kernel space is too crowded already. */
+    if (uAlignment != PAGE_SIZE)
+        return VERR_NOT_SUPPORTED;
+#endif
+    RT_ASSERT_PREEMPTIBLE();
+
+    RT_NOREF_PV(pszTag);
+
+    /* do the allocation. */
+    return rtR0MemObjNativeAllocPhys(pMemObj, cbAligned, PhysHighest, uAlignment);
+}
+RT_EXPORT_SYMBOL(RTR0MemObjAllocPhysExTag);
+
+
+RTR0DECL(int) RTR0MemObjAllocPhysNCTag(PRTR0MEMOBJ pMemObj, size_t cb, RTHCPHYS PhysHighest, const char *pszTag)
+{
+    /* sanity checks. */
+    const size_t cbAligned = RT_ALIGN_Z(cb, PAGE_SIZE);
+    AssertPtrReturn(pMemObj, VERR_INVALID_POINTER);
+    *pMemObj = NIL_RTR0MEMOBJ;
+    AssertReturn(cb > 0, VERR_INVALID_PARAMETER);
+    AssertReturn(cb <= cbAligned, VERR_INVALID_PARAMETER);
+    AssertReturn(PhysHighest >= cb, VERR_INVALID_PARAMETER);
+    RT_ASSERT_PREEMPTIBLE();
+
+    RT_NOREF_PV(pszTag);
+
+    /* do the allocation. */
+    return rtR0MemObjNativeAllocPhysNC(pMemObj, cbAligned, PhysHighest);
+}
+RT_EXPORT_SYMBOL(RTR0MemObjAllocPhysNCTag);
+
+
+RTR0DECL(int) RTR0MemObjEnterPhysTag(PRTR0MEMOBJ pMemObj, RTHCPHYS Phys, size_t cb, uint32_t uCachePolicy, const char *pszTag)
+{
+    /* sanity checks. */
+    const size_t cbAligned = RT_ALIGN_Z(cb + (Phys & PAGE_OFFSET_MASK), PAGE_SIZE);
+    const RTHCPHYS PhysAligned = Phys & ~(RTHCPHYS)PAGE_OFFSET_MASK;
+    AssertPtrReturn(pMemObj, VERR_INVALID_POINTER);
+    *pMemObj = NIL_RTR0MEMOBJ;
+    AssertReturn(cb > 0, VERR_INVALID_PARAMETER);
+    AssertReturn(cb <= cbAligned, VERR_INVALID_PARAMETER);
+    AssertReturn(Phys != NIL_RTHCPHYS, VERR_INVALID_PARAMETER);
+    AssertReturn(   uCachePolicy == RTMEM_CACHE_POLICY_DONT_CARE
+                 || uCachePolicy == RTMEM_CACHE_POLICY_MMIO,
+                 VERR_INVALID_PARAMETER);
+    RT_ASSERT_PREEMPTIBLE();
+
+    RT_NOREF_PV(pszTag);
+
+    /* do the allocation. */
+    return rtR0MemObjNativeEnterPhys(pMemObj, PhysAligned, cbAligned, uCachePolicy);
+}
+RT_EXPORT_SYMBOL(RTR0MemObjEnterPhysTag);
+
+
+RTR0DECL(int) RTR0MemObjReserveKernelTag(PRTR0MEMOBJ pMemObj, void *pvFixed, size_t cb, size_t uAlignment, const char *pszTag)
+{
+    /* sanity checks. */
+    const size_t cbAligned = RT_ALIGN_Z(cb, PAGE_SIZE);
+    AssertPtrReturn(pMemObj, VERR_INVALID_POINTER);
+    *pMemObj = NIL_RTR0MEMOBJ;
+    if (uAlignment == 0)
+        uAlignment = PAGE_SIZE;
+    AssertReturn(uAlignment == PAGE_SIZE || uAlignment == _2M || uAlignment == _4M, VERR_INVALID_PARAMETER);
+    AssertReturn(cb > 0, VERR_INVALID_PARAMETER);
+    AssertReturn(cb <= cbAligned, VERR_INVALID_PARAMETER);
+    if (pvFixed != (void *)-1)
+        AssertReturn(!((uintptr_t)pvFixed & (uAlignment - 1)), VERR_INVALID_PARAMETER);
+    RT_ASSERT_PREEMPTIBLE();
+
+    RT_NOREF_PV(pszTag);
+
+    /* do the reservation. */
+    return rtR0MemObjNativeReserveKernel(pMemObj, pvFixed, cbAligned, uAlignment);
+}
+RT_EXPORT_SYMBOL(RTR0MemObjReserveKernelTag);
+
+
+RTR0DECL(int) RTR0MemObjReserveUserTag(PRTR0MEMOBJ pMemObj, RTR3PTR R3PtrFixed, size_t cb,
+                                       size_t uAlignment, RTR0PROCESS R0Process, const char *pszTag)
+{
+    /* sanity checks. */
+    const size_t cbAligned = RT_ALIGN_Z(cb, PAGE_SIZE);
+    AssertPtrReturn(pMemObj, VERR_INVALID_POINTER);
+    *pMemObj = NIL_RTR0MEMOBJ;
+    if (uAlignment == 0)
+        uAlignment = PAGE_SIZE;
+    AssertReturn(uAlignment == PAGE_SIZE || uAlignment == _2M || uAlignment == _4M, VERR_INVALID_PARAMETER);
+    AssertReturn(cb > 0, VERR_INVALID_PARAMETER);
+    AssertReturn(cb <= cbAligned, VERR_INVALID_PARAMETER);
+    if (R3PtrFixed != (RTR3PTR)-1)
+        AssertReturn(!(R3PtrFixed & (uAlignment - 1)), VERR_INVALID_PARAMETER);
+    if (R0Process == NIL_RTR0PROCESS)
+        R0Process = RTR0ProcHandleSelf();
+    RT_ASSERT_PREEMPTIBLE();
+
+    RT_NOREF_PV(pszTag);
+
+    /* do the reservation. */
+    return rtR0MemObjNativeReserveUser(pMemObj, R3PtrFixed, cbAligned, uAlignment, R0Process);
+}
+RT_EXPORT_SYMBOL(RTR0MemObjReserveUserTag);
+
+
+RTR0DECL(int) RTR0MemObjMapKernelTag(PRTR0MEMOBJ pMemObj, RTR0MEMOBJ MemObjToMap, void *pvFixed,
+                                     size_t uAlignment, unsigned fProt, const char *pszTag)
+{
+    return RTR0MemObjMapKernelExTag(pMemObj, MemObjToMap, pvFixed, uAlignment, fProt, 0, 0, pszTag);
+}
+RT_EXPORT_SYMBOL(RTR0MemObjMapKernelTag);
+
+
+RTR0DECL(int) RTR0MemObjMapKernelExTag(PRTR0MEMOBJ pMemObj, RTR0MEMOBJ MemObjToMap, void *pvFixed, size_t uAlignment,
+                                       unsigned fProt, size_t offSub, size_t cbSub, const char *pszTag)
+{
+    PRTR0MEMOBJINTERNAL pMemToMap;
+    PRTR0MEMOBJINTERNAL pNew;
+    int                 rc;
+
+    /* sanity checks. */
+    AssertPtrReturn(pMemObj, VERR_INVALID_POINTER);
+    *pMemObj = NIL_RTR0MEMOBJ;
+    AssertPtrReturn(MemObjToMap, VERR_INVALID_HANDLE);
+    pMemToMap = (PRTR0MEMOBJINTERNAL)MemObjToMap;
+    AssertReturn(pMemToMap->u32Magic == RTR0MEMOBJ_MAGIC, VERR_INVALID_HANDLE);
+    AssertReturn(pMemToMap->enmType > RTR0MEMOBJTYPE_INVALID && pMemToMap->enmType < RTR0MEMOBJTYPE_END, VERR_INVALID_HANDLE);
+    AssertReturn(!rtR0MemObjIsMapping(pMemToMap), VERR_INVALID_PARAMETER);
+    AssertReturn(pMemToMap->enmType != RTR0MEMOBJTYPE_RES_VIRT, VERR_INVALID_PARAMETER);
+    if (uAlignment == 0)
+        uAlignment = PAGE_SIZE;
+    AssertReturn(uAlignment == PAGE_SIZE || uAlignment == _2M || uAlignment == _4M, VERR_INVALID_PARAMETER);
+    if (pvFixed != (void *)-1)
+        AssertReturn(!((uintptr_t)pvFixed & (uAlignment - 1)), VERR_INVALID_PARAMETER);
+    AssertReturn(fProt != RTMEM_PROT_NONE, VERR_INVALID_PARAMETER);
+    AssertReturn(!(fProt & ~(RTMEM_PROT_READ | RTMEM_PROT_WRITE | RTMEM_PROT_EXEC)), VERR_INVALID_PARAMETER);
+    AssertReturn(!(offSub & PAGE_OFFSET_MASK), VERR_INVALID_PARAMETER);
+    AssertReturn(offSub < pMemToMap->cb, VERR_INVALID_PARAMETER);
+    AssertReturn(!(cbSub & PAGE_OFFSET_MASK), VERR_INVALID_PARAMETER);
+    AssertReturn(cbSub <= pMemToMap->cb, VERR_INVALID_PARAMETER);
+    AssertReturn((!offSub && !cbSub) || (offSub + cbSub) <= pMemToMap->cb, VERR_INVALID_PARAMETER);
+    RT_ASSERT_PREEMPTIBLE();
+
+    RT_NOREF_PV(pszTag);
+
+    /* adjust the request to simplify the native code. */
+    if (offSub == 0 && cbSub == pMemToMap->cb)
+        cbSub = 0;
+
+    /* do the mapping. */
+    rc = rtR0MemObjNativeMapKernel(&pNew, pMemToMap, pvFixed, uAlignment, fProt, offSub, cbSub);
+    if (RT_SUCCESS(rc))
+    {
+        /* link it. */
+        rc = rtR0MemObjLink(pMemToMap, pNew);
+        if (RT_SUCCESS(rc))
+            *pMemObj = pNew;
+        else
+        {
+            /* damn, out of memory. bail out. */
+            int rc2 = rtR0MemObjNativeFree(pNew);
+            AssertRC(rc2);
+            pNew->u32Magic++;
+            pNew->enmType = RTR0MEMOBJTYPE_END;
+            RTMemFree(pNew);
+        }
+    }
+
+    return rc;
+}
+RT_EXPORT_SYMBOL(RTR0MemObjMapKernelExTag);
+
+
+RTR0DECL(int) RTR0MemObjMapUserTag(PRTR0MEMOBJ pMemObj, RTR0MEMOBJ MemObjToMap, RTR3PTR R3PtrFixed,
+                                   size_t uAlignment, unsigned fProt, RTR0PROCESS R0Process, const char *pszTag)
+{
+    return RTR0MemObjMapUserExTag(pMemObj, MemObjToMap, R3PtrFixed, uAlignment, fProt, R0Process, 0, 0, pszTag);
+}
+RT_EXPORT_SYMBOL(RTR0MemObjMapUserTag);
+
+
+RTR0DECL(int) RTR0MemObjMapUserExTag(PRTR0MEMOBJ pMemObj, RTR0MEMOBJ MemObjToMap, RTR3PTR R3PtrFixed, size_t uAlignment,
+                                     unsigned fProt, RTR0PROCESS R0Process, size_t offSub, size_t cbSub, const char *pszTag)
+{
+    /* sanity checks. */
+    PRTR0MEMOBJINTERNAL pMemToMap;
+    PRTR0MEMOBJINTERNAL pNew;
+    int rc;
+    AssertPtrReturn(pMemObj, VERR_INVALID_POINTER);
+    pMemToMap = (PRTR0MEMOBJINTERNAL)MemObjToMap;
+    *pMemObj = NIL_RTR0MEMOBJ;
+    AssertPtrReturn(MemObjToMap, VERR_INVALID_HANDLE);
+    AssertReturn(pMemToMap->u32Magic == RTR0MEMOBJ_MAGIC, VERR_INVALID_HANDLE);
+    AssertReturn(pMemToMap->enmType > RTR0MEMOBJTYPE_INVALID && pMemToMap->enmType < RTR0MEMOBJTYPE_END, VERR_INVALID_HANDLE);
+    AssertReturn(!rtR0MemObjIsMapping(pMemToMap), VERR_INVALID_PARAMETER);
+    AssertReturn(pMemToMap->enmType != RTR0MEMOBJTYPE_RES_VIRT, VERR_INVALID_PARAMETER);
+    if (uAlignment == 0)
+        uAlignment = PAGE_SIZE;
+    AssertReturn(uAlignment == PAGE_SIZE || uAlignment == _2M || uAlignment == _4M, VERR_INVALID_PARAMETER);
+    if (R3PtrFixed != (RTR3PTR)-1)
+        AssertReturn(!(R3PtrFixed & (uAlignment - 1)), VERR_INVALID_PARAMETER);
+    AssertReturn(fProt != RTMEM_PROT_NONE, VERR_INVALID_PARAMETER);
+    AssertReturn(!(fProt & ~(RTMEM_PROT_READ | RTMEM_PROT_WRITE | RTMEM_PROT_EXEC)), VERR_INVALID_PARAMETER);
+    AssertReturn(!(offSub & PAGE_OFFSET_MASK), VERR_INVALID_PARAMETER);
+    AssertReturn(offSub < pMemToMap->cb, VERR_INVALID_PARAMETER);
+    AssertReturn(!(cbSub & PAGE_OFFSET_MASK), VERR_INVALID_PARAMETER);
+    AssertReturn(cbSub <= pMemToMap->cb, VERR_INVALID_PARAMETER);
+    AssertReturn((!offSub && !cbSub) || (offSub + cbSub) <= pMemToMap->cb, VERR_INVALID_PARAMETER);
+    if (R0Process == NIL_RTR0PROCESS)
+        R0Process = RTR0ProcHandleSelf();
+    RT_ASSERT_PREEMPTIBLE();
+
+    RT_NOREF_PV(pszTag);
+
+    /* adjust the request to simplify the native code. */
+    if (offSub == 0 && cbSub == pMemToMap->cb)
+        cbSub = 0;
+
+    /* do the mapping. */
+    rc = rtR0MemObjNativeMapUser(&pNew, pMemToMap, R3PtrFixed, uAlignment, fProt, R0Process, offSub, cbSub);
+    if (RT_SUCCESS(rc))
+    {
+        /* link it. */
+        rc = rtR0MemObjLink(pMemToMap, pNew);
+        if (RT_SUCCESS(rc))
+            *pMemObj = pNew;
+        else
+        {
+            /* damn, out of memory. bail out. */
+            int rc2 = rtR0MemObjNativeFree(pNew);
+            AssertRC(rc2);
+            pNew->u32Magic++;
+            pNew->enmType = RTR0MEMOBJTYPE_END;
+            RTMemFree(pNew);
+        }
+    }
+
+    return rc;
+}
+RT_EXPORT_SYMBOL(RTR0MemObjMapUserExTag);
+
+
+RTR0DECL(int) RTR0MemObjProtect(RTR0MEMOBJ hMemObj, size_t offSub, size_t cbSub, uint32_t fProt)
+{
+    PRTR0MEMOBJINTERNAL pMemObj;
+    int                 rc;
+
+    /* sanity checks. */
+    pMemObj = (PRTR0MEMOBJINTERNAL)hMemObj;
+    AssertPtrReturn(pMemObj, VERR_INVALID_HANDLE);
+    AssertReturn(pMemObj->u32Magic == RTR0MEMOBJ_MAGIC, VERR_INVALID_HANDLE);
+    AssertReturn(pMemObj->enmType > RTR0MEMOBJTYPE_INVALID && pMemObj->enmType < RTR0MEMOBJTYPE_END, VERR_INVALID_HANDLE);
+    AssertReturn(rtR0MemObjIsProtectable(pMemObj), VERR_INVALID_PARAMETER);
+    AssertReturn(!(offSub & PAGE_OFFSET_MASK), VERR_INVALID_PARAMETER);
+    AssertReturn(offSub < pMemObj->cb, VERR_INVALID_PARAMETER);
+    AssertReturn(!(cbSub  & PAGE_OFFSET_MASK), VERR_INVALID_PARAMETER);
+    AssertReturn(cbSub <= pMemObj->cb, VERR_INVALID_PARAMETER);
+    AssertReturn(offSub + cbSub <= pMemObj->cb, VERR_INVALID_PARAMETER);
+    AssertReturn(!(fProt & ~(RTMEM_PROT_NONE | RTMEM_PROT_READ | RTMEM_PROT_WRITE | RTMEM_PROT_EXEC)), VERR_INVALID_PARAMETER);
+    RT_ASSERT_PREEMPTIBLE();
+
+    /* do the job */
+    rc = rtR0MemObjNativeProtect(pMemObj, offSub, cbSub, fProt);
+    if (RT_SUCCESS(rc))
+        pMemObj->fFlags |= RTR0MEMOBJ_FLAGS_PROT_CHANGED; /* record it */
+
+    return rc;
+}
+RT_EXPORT_SYMBOL(RTR0MemObjProtect);
+
diff --git a/src/VBox/Runtime/r0drv/mp-r0drv.h b/src/VBox/Runtime/r0drv/mp-r0drv.h
new file mode 100644
index 00000000..149d78f9
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/mp-r0drv.h
@@ -0,0 +1,85 @@
+/* $Id: mp-r0drv.h $ */
+/** @file
+ * IPRT - Multiprocessor, Ring-0 Driver, Internal Header.
+ */
+
+/*
+ * Copyright (C) 2008-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+#ifndef IPRT_INCLUDED_SRC_r0drv_mp_r0drv_h
+#define IPRT_INCLUDED_SRC_r0drv_mp_r0drv_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <iprt/mp.h>
+
+RT_C_DECLS_BEGIN
+
+/**
+ * MP callback
+ *
+ * @param   idCpu       CPU id
+ * @param   pvUser1     The first user argument.
+ * @param   pvUser2     The second user argument.
+ */
+typedef DECLCALLBACK(void) FNMPWORKER(RTCPUID idCpu, void *pvUser1, void *pvUser2);
+/** Pointer to a FNMPWORKER(). */
+typedef FNMPWORKER *PFNMPWORKER;
+
+/**
+ * RTMpOn* argument packet used by the host specific callback
+ * wrapper functions.
+ */
+typedef struct RTMPARGS
+{
+    PFNMPWORKER pfnWorker;
+    void       *pvUser1;
+    void       *pvUser2;
+    RTCPUID     idCpu;
+    RTCPUID     idCpu2;
+    uint32_t volatile cHits;
+#ifdef RT_OS_WINDOWS
+    /** Turns out that KeFlushQueuedDpcs doesn't necessarily wait till all
+     * callbacks are done.  So, do reference counting to make sure we don't free
+     * this structure befor all CPUs have completely handled their requests.  */
+    int32_t volatile  cRefs;
+#endif
+#ifdef RT_OS_LINUX
+    PRTCPUSET   pWorkerSet;
+#endif
+} RTMPARGS;
+/** Pointer to a RTMpOn* argument packet. */
+typedef RTMPARGS *PRTMPARGS;
+
+/* Called from initterm-r0drv.cpp: */
+DECLHIDDEN(int)  rtR0MpNotificationInit(void);
+DECLHIDDEN(void) rtR0MpNotificationTerm(void);
+
+/* The following is only relevant when using mpnotifcation-r0drv.cpp: */
+DECLHIDDEN(int)  rtR0MpNotificationNativeInit(void);
+DECLHIDDEN(void) rtR0MpNotificationNativeTerm(void);
+DECLHIDDEN(void) rtMpNotificationDoCallbacks(RTMPEVENT enmEvent, RTCPUID idCpu);
+
+RT_C_DECLS_END
+
+#endif /* !IPRT_INCLUDED_SRC_r0drv_mp_r0drv_h */
+
diff --git a/src/VBox/Runtime/r0drv/mpnotification-r0drv.c b/src/VBox/Runtime/r0drv/mpnotification-r0drv.c
new file mode 100644
index 00000000..90127976
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/mpnotification-r0drv.c
@@ -0,0 +1,322 @@
+/* $Id: mpnotification-r0drv.c $ */
+/** @file
+ * IPRT - Multiprocessor, Ring-0 Driver, Event Notifications.
+ */
+
+/*
+ * Copyright (C) 2008-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/mp.h>
+#include "internal/iprt.h"
+
+#include <iprt/asm.h>
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/mem.h>
+#include <iprt/spinlock.h>
+#include <iprt/string.h>
+#include <iprt/thread.h>
+#include "r0drv/mp-r0drv.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Notification registration record tracking
+ * RTMpRegisterNotification() calls.
+ */
+typedef struct RTMPNOTIFYREG
+{
+    /** Pointer to the next record. */
+    struct RTMPNOTIFYREG * volatile pNext;
+    /** The callback. */
+    PFNRTMPNOTIFICATION pfnCallback;
+    /** The user argument. */
+    void *pvUser;
+    /** Bit mask indicating whether we've done this callback or not. */
+    uint8_t bmDone[sizeof(void *)];
+} RTMPNOTIFYREG;
+/** Pointer to a registration record. */
+typedef RTMPNOTIFYREG *PRTMPNOTIFYREG;
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/** The spinlock protecting the list. */
+static RTSPINLOCK volatile g_hRTMpNotifySpinLock = NIL_RTSPINLOCK;
+/** List of callbacks, in registration order. */
+static PRTMPNOTIFYREG volatile g_pRTMpCallbackHead = NULL;
+/** The current done bit. */
+static uint32_t volatile g_iRTMpDoneBit;
+/** The list generation.
+ * This is increased whenever the list has been modified. The callback routine
+ * make use of this to avoid having restart at the list head after each callback. */
+static uint32_t volatile g_iRTMpGeneration;
+
+
+
+
+/**
+ * This is called by the native code.
+ *
+ * @param   idCpu           The CPU id the event applies to.
+ * @param   enmEvent        The event.
+ */
+DECLHIDDEN(void) rtMpNotificationDoCallbacks(RTMPEVENT enmEvent, RTCPUID idCpu)
+{
+    PRTMPNOTIFYREG  pCur;
+    RTSPINLOCK      hSpinlock;
+
+    /*
+     * This is a little bit tricky as we cannot be holding the spinlock
+     * while calling the callback. This means that the list might change
+     * while we're walking it, and that multiple events might be running
+     * concurrently (depending on the OS).
+     *
+     * So, the first measure is to employ a 32-bitmask for each
+     * record where we'll use a bit that rotates for each call to
+     * this function to indicate which records that has been
+     * processed. This will take care of both changes to the list
+     * and a reasonable amount of concurrent events.
+     *
+     * In order to avoid having to restart the list walks for every
+     * callback we make, we'll make use a list generation number that is
+     * incremented everytime the list is changed. So, if it remains
+     * unchanged over a callback we can safely continue the iteration.
+     */
+    uint32_t iDone = ASMAtomicIncU32(&g_iRTMpDoneBit);
+    iDone %= RT_SIZEOFMEMB(RTMPNOTIFYREG, bmDone) * 8;
+
+    hSpinlock = g_hRTMpNotifySpinLock;
+    if (hSpinlock == NIL_RTSPINLOCK)
+        return;
+    RTSpinlockAcquire(hSpinlock);
+
+    /* Clear the bit. */
+    for (pCur = g_pRTMpCallbackHead; pCur; pCur = pCur->pNext)
+        ASMAtomicBitClear(&pCur->bmDone[0], iDone);
+
+    /* Iterate the records and perform the callbacks. */
+    do
+    {
+        uint32_t const iGeneration = ASMAtomicUoReadU32(&g_iRTMpGeneration);
+
+        pCur = g_pRTMpCallbackHead;
+        while (pCur)
+        {
+            if (!ASMAtomicBitTestAndSet(&pCur->bmDone[0], iDone))
+            {
+                PFNRTMPNOTIFICATION pfnCallback = pCur->pfnCallback;
+                void *pvUser = pCur->pvUser;
+                pCur = pCur->pNext;
+                RTSpinlockRelease(g_hRTMpNotifySpinLock);
+
+                pfnCallback(enmEvent, idCpu, pvUser);
+
+                /* carefully require the lock here, see RTR0MpNotificationTerm(). */
+                hSpinlock = g_hRTMpNotifySpinLock;
+                if (hSpinlock == NIL_RTSPINLOCK)
+                    return;
+                RTSpinlockAcquire(hSpinlock);
+                if (ASMAtomicUoReadU32(&g_iRTMpGeneration) != iGeneration)
+                    break;
+            }
+            else
+                pCur = pCur->pNext;
+        }
+    } while (pCur);
+
+    RTSpinlockRelease(hSpinlock);
+}
+
+
+
+RTDECL(int) RTMpNotificationRegister(PFNRTMPNOTIFICATION pfnCallback, void *pvUser)
+{
+    PRTMPNOTIFYREG  pCur;
+    PRTMPNOTIFYREG  pNew;
+
+    /*
+     * Validation.
+     */
+    AssertPtrReturn(pfnCallback, VERR_INVALID_POINTER);
+    AssertReturn(g_hRTMpNotifySpinLock != NIL_RTSPINLOCK, VERR_WRONG_ORDER);
+    RT_ASSERT_PREEMPTIBLE();
+
+    RTSpinlockAcquire(g_hRTMpNotifySpinLock);
+    for (pCur = g_pRTMpCallbackHead; pCur; pCur = pCur->pNext)
+        if (    pCur->pvUser == pvUser
+            &&  pCur->pfnCallback == pfnCallback)
+            break;
+    RTSpinlockRelease(g_hRTMpNotifySpinLock);
+    AssertMsgReturn(!pCur, ("pCur=%p pfnCallback=%p pvUser=%p\n", pCur, pfnCallback, pvUser), VERR_ALREADY_EXISTS);
+
+    /*
+     * Allocate a new record and attempt to insert it.
+     */
+    pNew = (PRTMPNOTIFYREG)RTMemAlloc(sizeof(*pNew));
+    if (!pNew)
+        return VERR_NO_MEMORY;
+
+    pNew->pNext = NULL;
+    pNew->pfnCallback = pfnCallback;
+    pNew->pvUser = pvUser;
+    memset(&pNew->bmDone[0], 0xff, sizeof(pNew->bmDone));
+
+    RTSpinlockAcquire(g_hRTMpNotifySpinLock);
+
+    pCur = g_pRTMpCallbackHead;
+    if (!pCur)
+        g_pRTMpCallbackHead = pNew;
+    else
+    {
+        for (pCur = g_pRTMpCallbackHead; ; pCur = pCur->pNext)
+            if (    pCur->pvUser == pvUser
+                &&  pCur->pfnCallback == pfnCallback)
+                break;
+            else if (!pCur->pNext)
+            {
+                pCur->pNext = pNew;
+                pCur = NULL;
+                break;
+            }
+    }
+
+    ASMAtomicIncU32(&g_iRTMpGeneration);
+
+    RTSpinlockRelease(g_hRTMpNotifySpinLock);
+
+    /* duplicate? */
+    if (pCur)
+    {
+        RTMemFree(pCur);
+        AssertMsgFailedReturn(("pCur=%p pfnCallback=%p pvUser=%p\n", pCur, pfnCallback, pvUser), VERR_ALREADY_EXISTS);
+    }
+
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTMpNotificationRegister);
+
+
+RTDECL(int) RTMpNotificationDeregister(PFNRTMPNOTIFICATION pfnCallback, void *pvUser)
+{
+    PRTMPNOTIFYREG  pPrev;
+    PRTMPNOTIFYREG  pCur;
+
+    /*
+     * Validation.
+     */
+    AssertPtrReturn(pfnCallback, VERR_INVALID_POINTER);
+    AssertReturn(g_hRTMpNotifySpinLock != NIL_RTSPINLOCK, VERR_WRONG_ORDER);
+    RT_ASSERT_INTS_ON();
+
+    /*
+     * Find and unlink the record from the list.
+     */
+    RTSpinlockAcquire(g_hRTMpNotifySpinLock);
+    pPrev = NULL;
+    for (pCur = g_pRTMpCallbackHead; pCur; pCur = pCur->pNext)
+    {
+        if (    pCur->pvUser == pvUser
+            &&  pCur->pfnCallback == pfnCallback)
+            break;
+        pPrev = pCur;
+    }
+    if (pCur)
+    {
+        if (pPrev)
+            pPrev->pNext = pCur->pNext;
+        else
+            g_pRTMpCallbackHead = pCur->pNext;
+        ASMAtomicIncU32(&g_iRTMpGeneration);
+    }
+    RTSpinlockRelease(g_hRTMpNotifySpinLock);
+
+    if (!pCur)
+        return VERR_NOT_FOUND;
+
+    /*
+     * Invalidate and free the record.
+     */
+    pCur->pNext = NULL;
+    pCur->pfnCallback = NULL;
+    RTMemFree(pCur);
+
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTMpNotificationDeregister);
+
+
+DECLHIDDEN(int) rtR0MpNotificationInit(void)
+{
+    int rc = RTSpinlockCreate((PRTSPINLOCK)&g_hRTMpNotifySpinLock, RTSPINLOCK_FLAGS_INTERRUPT_SAFE, "RTR0Mp");
+    if (RT_SUCCESS(rc))
+    {
+        rc = rtR0MpNotificationNativeInit();
+        if (RT_SUCCESS(rc))
+            return rc;
+
+        RTSpinlockDestroy(g_hRTMpNotifySpinLock);
+        g_hRTMpNotifySpinLock = NIL_RTSPINLOCK;
+    }
+    return rc;
+}
+
+
+DECLHIDDEN(void) rtR0MpNotificationTerm(void)
+{
+    PRTMPNOTIFYREG  pHead;
+    RTSPINLOCK      hSpinlock = g_hRTMpNotifySpinLock;
+    AssertReturnVoid(hSpinlock != NIL_RTSPINLOCK);
+
+    rtR0MpNotificationNativeTerm();
+
+    /* pick up the list and the spinlock. */
+    RTSpinlockAcquire(hSpinlock);
+    ASMAtomicWriteHandle(&g_hRTMpNotifySpinLock, NIL_RTSPINLOCK);
+    pHead = g_pRTMpCallbackHead;
+    g_pRTMpCallbackHead = NULL;
+    ASMAtomicIncU32(&g_iRTMpGeneration);
+    RTSpinlockRelease(hSpinlock);
+
+    /* free the list. */
+    while (pHead)
+    {
+        PRTMPNOTIFYREG pFree = pHead;
+        pHead = pHead->pNext;
+
+        pFree->pNext = NULL;
+        pFree->pfnCallback = NULL;
+        RTMemFree(pFree);
+    }
+
+    RTSpinlockDestroy(hSpinlock);
+}
+
diff --git a/src/VBox/Runtime/r0drv/netbsd/Makefile.kup b/src/VBox/Runtime/r0drv/netbsd/Makefile.kup
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/netbsd/Makefile.kup
diff --git a/src/VBox/Runtime/r0drv/netbsd/RTLogWriteStdOut-r0drv-netbsd.c b/src/VBox/Runtime/r0drv/netbsd/RTLogWriteStdOut-r0drv-netbsd.c
new file mode 100644
index 00000000..8b003494
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/netbsd/RTLogWriteStdOut-r0drv-netbsd.c
@@ -0,0 +1,39 @@
+/* $Id: RTLogWriteStdOut-r0drv-netbsd.c $ */
+/** @file
+ * IPRT - Log To StdOut, Ring-0 Driver, NetBSD.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-netbsd-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/log.h>
+
+
+RTDECL(void) RTLogWriteStdOut(const char *pch, size_t cb)
+{
+    printf("%.*s", (int)cb, pch);
+}
diff --git a/src/VBox/Runtime/r0drv/netbsd/alloc-r0drv-netbsd.c b/src/VBox/Runtime/r0drv/netbsd/alloc-r0drv-netbsd.c
new file mode 100644
index 00000000..ad067c11
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/netbsd/alloc-r0drv-netbsd.c
@@ -0,0 +1,166 @@
+/* $Id: alloc-r0drv-netbsd.c $ */
+/** @file
+ * IPRT - Memory Allocation, Ring-0 Driver, NetBSD.
+ */
+
+/*
+ * Copyright (C) 2014-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * ---------------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2014 Arto Huusko
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-netbsd-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/mem.h>
+
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+#include <iprt/param.h>
+
+#include "r0drv/alloc-r0drv.h"
+
+
+DECLHIDDEN(int) rtR0MemAllocEx(size_t cb, uint32_t fFlags, PRTMEMHDR *ppHdr)
+{
+    size_t      cbAllocated = cb;
+    PRTMEMHDR   pHdr        = NULL;
+
+    if (fFlags & RTMEMHDR_FLAG_ZEROED)
+        pHdr = kmem_zalloc(cb + sizeof(RTMEMHDR), KM_NOSLEEP);
+    else
+        pHdr = kmem_alloc(cb + sizeof(RTMEMHDR), KM_NOSLEEP);
+
+    if (RT_UNLIKELY(!pHdr))
+        return VERR_NO_MEMORY;
+
+    pHdr->u32Magic   = RTMEMHDR_MAGIC;
+    pHdr->fFlags     = fFlags;
+    pHdr->cb         = cbAllocated;
+    pHdr->cbReq      = cb;
+
+    *ppHdr = pHdr;
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(void) rtR0MemFree(PRTMEMHDR pHdr)
+{
+    pHdr->u32Magic += 1;
+
+    kmem_free(pHdr, pHdr->cb + sizeof(RTMEMHDR));
+}
+
+RTR0DECL(void) RTMemContFree(void *pv, size_t cb)
+{
+    if (pv)
+    {
+        cb = round_page(cb);
+
+        paddr_t pa;
+        pmap_extract(pmap_kernel(), (vaddr_t)pv, &pa);
+
+        /*
+         * Reconstruct pglist to free the physical pages
+         */
+        struct pglist rlist;
+        TAILQ_INIT(&rlist);
+
+        for (paddr_t pa2 = pa ; pa2 < pa + cb ; pa2 += PAGE_SIZE) {
+            struct vm_page *page = PHYS_TO_VM_PAGE(pa2);
+            TAILQ_INSERT_TAIL(&rlist, page, pageq.queue);
+        }
+
+        /* Unmap */
+        pmap_kremove((vaddr_t)pv, cb);
+
+        /* Free the virtual space */
+        uvm_km_free(kernel_map, (vaddr_t)pv, cb, UVM_KMF_VAONLY);
+
+        /* Free the physical pages */
+        uvm_pglistfree(&rlist);
+    }
+}
+
+RTR0DECL(void *) RTMemContAlloc(PRTCCPHYS pPhys, size_t cb)
+{
+    /*
+     * Validate input.
+     */
+    AssertPtr(pPhys);
+    Assert(cb > 0);
+
+    cb = round_page(cb);
+
+    vaddr_t virt = uvm_km_alloc(kernel_map, cb, 0,
+            UVM_KMF_VAONLY | UVM_KMF_WAITVA | UVM_KMF_CANFAIL);
+    if (virt == 0)
+        return NULL;
+
+    struct pglist rlist;
+
+    if (uvm_pglistalloc(cb, 0, (paddr_t)0xFFFFFFFF,
+            PAGE_SIZE, 0, &rlist, 1, 1) != 0)
+    {
+        uvm_km_free(kernel_map, virt, cb, UVM_KMF_VAONLY);
+        return NULL;
+    }
+
+    struct vm_page *page;
+    vaddr_t virt2 = virt;
+    TAILQ_FOREACH(page, &rlist, pageq.queue)
+    {
+        pmap_kenter_pa(virt2, VM_PAGE_TO_PHYS(page),
+                VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE, 0);
+        virt2 += PAGE_SIZE;
+    }
+
+    page = TAILQ_FIRST(&rlist);
+    *pPhys = VM_PAGE_TO_PHYS(page);
+
+    return (void *)virt;
+}
diff --git a/src/VBox/Runtime/r0drv/netbsd/assert-r0drv-netbsd.c b/src/VBox/Runtime/r0drv/netbsd/assert-r0drv-netbsd.c
new file mode 100644
index 00000000..4517841f
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/netbsd/assert-r0drv-netbsd.c
@@ -0,0 +1,85 @@
+/* $Id: assert-r0drv-netbsd.c $ */
+/** @file
+ * IPRT - Assertion Workers, Ring-0 Drivers, NetBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-netbsd-kernel.h"
+
+#include <iprt/assert.h>
+#include <iprt/log.h>
+#include <iprt/stdarg.h>
+
+#include "internal/assert.h"
+
+
+DECLHIDDEN(void) rtR0AssertNativeMsg1(const char *pszExpr, unsigned uLine, const char *pszFile, const char *pszFunction)
+{
+    printf("\r\n!!Assertion Failed!!\r\n"
+           "Expression: %s\r\n"
+           "Location  : %s(%d) %s\r\n",
+           pszExpr, pszFile, uLine, pszFunction);
+}
+
+
+DECLHIDDEN(void) rtR0AssertNativeMsg2V(bool fInitial, const char *pszFormat, va_list va)
+{
+    /** @todo implement rtR0AssertNativeMsg2V. */
+}
+
+
+RTR0DECL(void) RTR0AssertPanicSystem(void)
+{
+    panic("%s%s", g_szRTAssertMsg1, g_szRTAssertMsg2);
+
+}
diff --git a/src/VBox/Runtime/r0drv/netbsd/initterm-r0drv-netbsd.c b/src/VBox/Runtime/r0drv/netbsd/initterm-r0drv-netbsd.c
new file mode 100644
index 00000000..af590d26
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/netbsd/initterm-r0drv-netbsd.c
@@ -0,0 +1,74 @@
+/* $Id: initterm-r0drv-netbsd.c $ */
+/** @file
+ * IPRT - Initialization & Termination, Ring-0 Driver, NetBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-netbsd-kernel.h"
+
+#include <iprt/errcore.h>
+
+#include "internal/initterm.h"
+
+
+DECLHIDDEN(int) rtR0InitNative(void)
+{
+    /* nothing to do */
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(void) rtR0TermNative(void)
+{
+    /* nothing to undo */
+}
diff --git a/src/VBox/Runtime/r0drv/netbsd/memobj-r0drv-netbsd.c b/src/VBox/Runtime/r0drv/netbsd/memobj-r0drv-netbsd.c
new file mode 100644
index 00000000..dc2139b3
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/netbsd/memobj-r0drv-netbsd.c
@@ -0,0 +1,581 @@
+/* $Id: memobj-r0drv-netbsd.c $ */
+/** @file
+ * IPRT - Ring-0 Memory Objects, NetBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen, Andriy Gapon, Arto Huusko.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ * Copyright (c) 2011 Andriy Gapon <avg@FreeBSD.org>
+ * Copyright (c) 2014 Arto Huusko
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-netbsd-kernel.h"
+
+#include <iprt/memobj.h>
+#include <iprt/mem.h>
+#include <iprt/err.h>
+#include <iprt/assert.h>
+#include <iprt/log.h>
+#include <iprt/param.h>
+#include <iprt/process.h>
+#include "internal/memobj.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * The NetBSD version of the memory object structure.
+ */
+typedef struct RTR0MEMOBJNETBSD
+{
+    /** The core structure. */
+    RTR0MEMOBJINTERNAL  Core;
+    size_t              size;
+    struct pglist       pglist;
+} RTR0MEMOBJNETBSD, *PRTR0MEMOBJNETBSD;
+
+
+typedef struct vm_map* vm_map_t;
+
+/**
+ * Gets the virtual memory map the specified object is mapped into.
+ *
+ * @returns VM map handle on success, NULL if no map.
+ * @param   pMem                The memory object.
+ */
+static vm_map_t rtR0MemObjNetBSDGetMap(PRTR0MEMOBJINTERNAL pMem)
+{
+    switch (pMem->enmType)
+    {
+        case RTR0MEMOBJTYPE_PAGE:
+        case RTR0MEMOBJTYPE_LOW:
+        case RTR0MEMOBJTYPE_CONT:
+            return kernel_map;
+
+        case RTR0MEMOBJTYPE_PHYS:
+        case RTR0MEMOBJTYPE_PHYS_NC:
+            return NULL; /* pretend these have no mapping atm. */
+
+        case RTR0MEMOBJTYPE_LOCK:
+            return pMem->u.Lock.R0Process == NIL_RTR0PROCESS
+                ? kernel_map
+                : &((struct proc *)pMem->u.Lock.R0Process)->p_vmspace->vm_map;
+
+        case RTR0MEMOBJTYPE_RES_VIRT:
+            return pMem->u.ResVirt.R0Process == NIL_RTR0PROCESS
+                ? kernel_map
+                : &((struct proc *)pMem->u.ResVirt.R0Process)->p_vmspace->vm_map;
+
+        case RTR0MEMOBJTYPE_MAPPING:
+            return pMem->u.Mapping.R0Process == NIL_RTR0PROCESS
+                ? kernel_map
+                : &((struct proc *)pMem->u.Mapping.R0Process)->p_vmspace->vm_map;
+
+        default:
+            return NULL;
+    }
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeFree(RTR0MEMOBJ pMem)
+{
+    PRTR0MEMOBJNETBSD pMemNetBSD = (PRTR0MEMOBJNETBSD)pMem;
+    int rc;
+
+    switch (pMemNetBSD->Core.enmType)
+    {
+        case RTR0MEMOBJTYPE_PAGE:
+        {
+            kmem_free(pMemNetBSD->Core.pv, pMemNetBSD->Core.cb);
+            break;
+        }
+        case RTR0MEMOBJTYPE_LOW:
+        case RTR0MEMOBJTYPE_CONT:
+        {
+            /* Unmap */
+            pmap_kremove((vaddr_t)pMemNetBSD->Core.pv, pMemNetBSD->Core.cb);
+            /* Free the virtual space */
+            uvm_km_free(kernel_map, (vaddr_t)pMemNetBSD->Core.pv, pMemNetBSD->Core.cb, UVM_KMF_VAONLY);
+            /* Free the physical pages */
+            uvm_pglistfree(&pMemNetBSD->pglist);
+            break;
+        }
+        case RTR0MEMOBJTYPE_PHYS:
+        case RTR0MEMOBJTYPE_PHYS_NC:
+        {
+            /* Free the physical pages */
+            uvm_pglistfree(&pMemNetBSD->pglist);
+            break;
+        }
+        case RTR0MEMOBJTYPE_LOCK:
+            if (pMemNetBSD->Core.u.Lock.R0Process != NIL_RTR0PROCESS)
+            {
+                uvm_map_pageable(
+                        &((struct proc *)pMemNetBSD->Core.u.Lock.R0Process)->p_vmspace->vm_map,
+                        (vaddr_t)pMemNetBSD->Core.pv,
+                        ((vaddr_t)pMemNetBSD->Core.pv) + pMemNetBSD->Core.cb,
+                        1, 0);
+            }
+            break;
+        case RTR0MEMOBJTYPE_RES_VIRT:
+            if (pMemNetBSD->Core.u.Lock.R0Process == NIL_RTR0PROCESS)
+            {
+                uvm_km_free(kernel_map, (vaddr_t)pMemNetBSD->Core.pv, pMemNetBSD->Core.cb, UVM_KMF_VAONLY);
+            }
+            break;
+        case RTR0MEMOBJTYPE_MAPPING:
+            if (pMemNetBSD->Core.u.Lock.R0Process == NIL_RTR0PROCESS)
+            {
+                pmap_kremove((vaddr_t)pMemNetBSD->Core.pv, pMemNetBSD->Core.cb);
+                uvm_km_free(kernel_map, (vaddr_t)pMemNetBSD->Core.pv, pMemNetBSD->Core.cb, UVM_KMF_VAONLY);
+            }
+            break;
+
+        default:
+            AssertMsgFailed(("enmType=%d\n", pMemNetBSD->Core.enmType));
+            return VERR_INTERNAL_ERROR;
+    }
+
+    return VINF_SUCCESS;
+}
+
+static int rtR0MemObjNetBSDAllocHelper(PRTR0MEMOBJNETBSD pMemNetBSD, size_t cb, bool fExecutable,
+                                         paddr_t VmPhysAddrHigh, bool fContiguous)
+{
+    /* Virtual space first */
+    vaddr_t virt = uvm_km_alloc(kernel_map, cb, 0,
+            UVM_KMF_VAONLY | UVM_KMF_WAITVA | UVM_KMF_CANFAIL);
+    if (virt == 0)
+        return VERR_NO_MEMORY;
+
+    struct pglist *rlist = &pMemNetBSD->pglist;
+
+    int nsegs = fContiguous ? 1 : INT_MAX;
+
+    /* Physical pages */
+    if (uvm_pglistalloc(cb, 0, VmPhysAddrHigh,
+            PAGE_SIZE, 0, rlist, nsegs, 1) != 0)
+    {
+        uvm_km_free(kernel_map, virt, cb, UVM_KMF_VAONLY);
+        return VERR_NO_MEMORY;
+    }
+
+    /* Map */
+    struct vm_page *page;
+    vm_prot_t prot = VM_PROT_READ | VM_PROT_WRITE;
+    if (fExecutable)
+        prot |= VM_PROT_EXECUTE;
+    vaddr_t virt2 = virt;
+    TAILQ_FOREACH(page, rlist, pageq.queue)
+    {
+        pmap_kenter_pa(virt2, VM_PAGE_TO_PHYS(page), prot, 0);
+        virt2 += PAGE_SIZE;
+    }
+
+    pMemNetBSD->Core.pv = (void *)virt;
+    if (fContiguous)
+    {
+        page = TAILQ_FIRST(rlist);
+        pMemNetBSD->Core.u.Cont.Phys = VM_PAGE_TO_PHYS(page);
+    }
+    return VINF_SUCCESS;
+}
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocPage(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    PRTR0MEMOBJNETBSD pMemNetBSD = (PRTR0MEMOBJNETBSD)rtR0MemObjNew(sizeof(*pMemNetBSD),
+                                                                       RTR0MEMOBJTYPE_PAGE, NULL, cb);
+    if (!pMemNetBSD)
+        return VERR_NO_MEMORY;
+
+    void *pvMem = kmem_alloc(cb, KM_SLEEP);
+    if (RT_UNLIKELY(!pvMem))
+    {
+        rtR0MemObjDelete(&pMemNetBSD->Core);
+        return VERR_NO_PAGE_MEMORY;
+    }
+    if (fExecutable)
+    {
+        pmap_protect(pmap_kernel(), (vaddr_t)pvMem, ((vaddr_t)pvMem) + cb,
+                VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE);
+    }
+
+    pMemNetBSD->Core.pv = pvMem;
+    *ppMem = &pMemNetBSD->Core;
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocLow(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    PRTR0MEMOBJNETBSD pMemNetBSD = (PRTR0MEMOBJNETBSD)rtR0MemObjNew(sizeof(*pMemNetBSD),
+                                                                       RTR0MEMOBJTYPE_LOW, NULL, cb);
+    if (!pMemNetBSD)
+        return VERR_NO_MEMORY;
+
+    int rc = rtR0MemObjNetBSDAllocHelper(pMemNetBSD, cb, fExecutable, _4G - 1, false);
+    if (rc)
+    {
+        rtR0MemObjDelete(&pMemNetBSD->Core);
+        return rc;
+    }
+
+    *ppMem = &pMemNetBSD->Core;
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocCont(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    PRTR0MEMOBJNETBSD pMemNetBSD = (PRTR0MEMOBJNETBSD)rtR0MemObjNew(sizeof(*pMemNetBSD),
+                                                                       RTR0MEMOBJTYPE_CONT, NULL, cb);
+    if (!pMemNetBSD)
+        return VERR_NO_MEMORY;
+
+    int rc = rtR0MemObjNetBSDAllocHelper(pMemNetBSD, cb, fExecutable, _4G - 1, true);
+    if (rc)
+    {
+        rtR0MemObjDelete(&pMemNetBSD->Core);
+        return rc;
+    }
+
+    *ppMem = &pMemNetBSD->Core;
+    return VINF_SUCCESS;
+}
+
+
+static int rtR0MemObjNetBSDAllocPhysPages(PPRTR0MEMOBJINTERNAL ppMem, RTR0MEMOBJTYPE enmType,
+                                           size_t cb,
+                                           RTHCPHYS PhysHighest, size_t uAlignment,
+                                           bool fContiguous)
+{
+    paddr_t VmPhysAddrHigh;
+
+    /* create the object. */
+    PRTR0MEMOBJNETBSD pMemNetBSD = (PRTR0MEMOBJNETBSD)rtR0MemObjNew(sizeof(*pMemNetBSD),
+                                                                       enmType, NULL, cb);
+    if (!pMemNetBSD)
+        return VERR_NO_MEMORY;
+
+    if (PhysHighest != NIL_RTHCPHYS)
+        VmPhysAddrHigh = PhysHighest;
+    else
+        VmPhysAddrHigh = ~(paddr_t)0;
+
+    int nsegs = fContiguous ? 1 : INT_MAX;
+
+    int error = uvm_pglistalloc(cb, 0, VmPhysAddrHigh, uAlignment, 0, &pMemNetBSD->pglist, nsegs, 1);
+    if (error)
+    {
+        rtR0MemObjDelete(&pMemNetBSD->Core);
+        return VERR_NO_MEMORY;
+    }
+
+    if (fContiguous)
+    {
+        Assert(enmType == RTR0MEMOBJTYPE_PHYS);
+        const struct vm_page * const pg = TAILQ_FIRST(&pMemNetBSD->pglist);
+        pMemNetBSD->Core.u.Phys.PhysBase = VM_PAGE_TO_PHYS(pg);
+        pMemNetBSD->Core.u.Phys.fAllocated = true;
+    }
+    *ppMem = &pMemNetBSD->Core;
+
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocPhys(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, RTHCPHYS PhysHighest, size_t uAlignment)
+{
+    return rtR0MemObjNetBSDAllocPhysPages(ppMem, RTR0MEMOBJTYPE_PHYS, cb, PhysHighest, uAlignment, true);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocPhysNC(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, RTHCPHYS PhysHighest)
+{
+    return rtR0MemObjNetBSDAllocPhysPages(ppMem, RTR0MEMOBJTYPE_PHYS_NC, cb, PhysHighest, PAGE_SIZE, false);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeEnterPhys(PPRTR0MEMOBJINTERNAL ppMem, RTHCPHYS Phys, size_t cb, uint32_t uCachePolicy)
+{
+    AssertReturn(uCachePolicy == RTMEM_CACHE_POLICY_DONT_CARE, VERR_NOT_SUPPORTED);
+
+    /* create the object. */
+    PRTR0MEMOBJNETBSD pMemNetBSD = (PRTR0MEMOBJNETBSD)rtR0MemObjNew(sizeof(*pMemNetBSD), RTR0MEMOBJTYPE_PHYS, NULL, cb);
+    if (!pMemNetBSD)
+        return VERR_NO_MEMORY;
+
+    /* there is no allocation here, it needs to be mapped somewhere first. */
+    pMemNetBSD->Core.u.Phys.fAllocated = false;
+    pMemNetBSD->Core.u.Phys.PhysBase = Phys;
+    pMemNetBSD->Core.u.Phys.uCachePolicy = uCachePolicy;
+    TAILQ_INIT(&pMemNetBSD->pglist);
+    *ppMem = &pMemNetBSD->Core;
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeLockUser(PPRTR0MEMOBJINTERNAL ppMem, RTR3PTR R3Ptr, size_t cb, uint32_t fAccess, RTR0PROCESS R0Process)
+{
+    PRTR0MEMOBJNETBSD pMemNetBSD = (PRTR0MEMOBJNETBSD)rtR0MemObjNew(sizeof(*pMemNetBSD), RTR0MEMOBJTYPE_LOCK, (void *)R3Ptr, cb);
+    if (!pMemNetBSD)
+        return VERR_NO_MEMORY;
+
+    int rc = uvm_map_pageable(
+            &((struct proc *)R0Process)->p_vmspace->vm_map,
+            R3Ptr,
+            R3Ptr + cb,
+            0, 0);
+    if (rc)
+    {
+        rtR0MemObjDelete(&pMemNetBSD->Core);
+        return VERR_NO_MEMORY;
+    }
+
+    pMemNetBSD->Core.u.Lock.R0Process = R0Process;
+    *ppMem = &pMemNetBSD->Core;
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeLockKernel(PPRTR0MEMOBJINTERNAL ppMem, void *pv, size_t cb, uint32_t fAccess)
+{
+    /* Kernel memory (always?) wired; all memory allocated by vbox code is? */
+    PRTR0MEMOBJNETBSD pMemNetBSD = (PRTR0MEMOBJNETBSD)rtR0MemObjNew(sizeof(*pMemNetBSD), RTR0MEMOBJTYPE_LOCK, pv, cb);
+    if (!pMemNetBSD)
+        return VERR_NO_MEMORY;
+
+    pMemNetBSD->Core.u.Lock.R0Process = NIL_RTR0PROCESS;
+    pMemNetBSD->Core.pv = pv;
+    *ppMem = &pMemNetBSD->Core;
+    return VINF_SUCCESS;
+}
+
+DECLHIDDEN(int) rtR0MemObjNativeReserveKernel(PPRTR0MEMOBJINTERNAL ppMem, void *pvFixed, size_t cb, size_t uAlignment)
+{
+    if (pvFixed != (void *)-1)
+    {
+        /* can we support this? or can we assume the virtual space is already reserved? */
+        printf("reserve specified kernel virtual address not supported\n");
+        return VERR_NOT_SUPPORTED;
+    }
+
+    PRTR0MEMOBJNETBSD pMemNetBSD = (PRTR0MEMOBJNETBSD)rtR0MemObjNew(sizeof(*pMemNetBSD), RTR0MEMOBJTYPE_RES_VIRT, NULL, cb);
+    if (!pMemNetBSD)
+        return VERR_NO_MEMORY;
+
+    vaddr_t virt = uvm_km_alloc(kernel_map, cb, uAlignment,
+            UVM_KMF_VAONLY | UVM_KMF_WAITVA | UVM_KMF_CANFAIL);
+    if (virt == 0)
+    {
+        rtR0MemObjDelete(&pMemNetBSD->Core);
+        return VERR_NO_MEMORY;
+    }
+
+    pMemNetBSD->Core.u.ResVirt.R0Process = NIL_RTR0PROCESS;
+    pMemNetBSD->Core.pv = (void *)virt;
+    *ppMem = &pMemNetBSD->Core;
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeReserveUser(PPRTR0MEMOBJINTERNAL ppMem, RTR3PTR R3PtrFixed, size_t cb, size_t uAlignment, RTR0PROCESS R0Process)
+{
+    printf("NativeReserveUser\n");
+    return VERR_NOT_SUPPORTED;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeMapKernel(PPRTR0MEMOBJINTERNAL ppMem, RTR0MEMOBJ pMemToMap, void *pvFixed, size_t uAlignment,
+                                          unsigned fProt, size_t offSub, size_t cbSub)
+{
+    if (pvFixed != (void *)-1)
+    {
+        /* can we support this? or can we assume the virtual space is already reserved? */
+        printf("map to specified kernel virtual address not supported\n");
+        return VERR_NOT_SUPPORTED;
+    }
+
+    PRTR0MEMOBJNETBSD pMemNetBSD0 = (PRTR0MEMOBJNETBSD)pMemToMap;
+    if ((pMemNetBSD0->Core.enmType != RTR0MEMOBJTYPE_PHYS)
+        && (pMemNetBSD0->Core.enmType != RTR0MEMOBJTYPE_PHYS_NC))
+    {
+        printf("memory to map is not physical\n");
+        return VERR_NOT_SUPPORTED;
+    }
+    size_t sz = cbSub > 0 ? cbSub : pMemNetBSD0->Core.cb;
+
+    PRTR0MEMOBJNETBSD pMemNetBSD = (PRTR0MEMOBJNETBSD)rtR0MemObjNew(sizeof(*pMemNetBSD), RTR0MEMOBJTYPE_MAPPING, NULL, sz);
+
+    vaddr_t virt = uvm_km_alloc(kernel_map, sz, uAlignment,
+            UVM_KMF_VAONLY | UVM_KMF_WAITVA | UVM_KMF_CANFAIL);
+    if (virt == 0)
+    {
+        rtR0MemObjDelete(&pMemNetBSD->Core);
+        return VERR_NO_MEMORY;
+    }
+
+    vm_prot_t prot = 0;
+
+    if ((fProt & RTMEM_PROT_READ) == RTMEM_PROT_READ)
+        prot |= VM_PROT_READ;
+    if ((fProt & RTMEM_PROT_WRITE) == RTMEM_PROT_WRITE)
+        prot |= VM_PROT_WRITE;
+    if ((fProt & RTMEM_PROT_EXEC) == RTMEM_PROT_EXEC)
+        prot |= VM_PROT_EXECUTE;
+
+    struct vm_page *page;
+    vaddr_t virt2 = virt;
+    size_t map_pos = 0;
+    TAILQ_FOREACH(page, &pMemNetBSD0->pglist, pageq.queue)
+    {
+        if (map_pos >= offSub)
+        {
+            if (cbSub > 0 && (map_pos >= offSub + cbSub))
+                break;
+
+            pmap_kenter_pa(virt2, VM_PAGE_TO_PHYS(page), prot, 0);
+            virt2 += PAGE_SIZE;
+        }
+        map_pos += PAGE_SIZE;
+    }
+
+    pMemNetBSD->Core.pv = (void *)virt;
+    pMemNetBSD->Core.u.Mapping.R0Process = NIL_RTR0PROCESS;
+    *ppMem = &pMemNetBSD->Core;
+
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeMapUser(PPRTR0MEMOBJINTERNAL ppMem, RTR0MEMOBJ pMemToMap, RTR3PTR R3PtrFixed, size_t uAlignment,
+                                        unsigned fProt, RTR0PROCESS R0Process, size_t offSub, size_t cbSub)
+{
+    printf("NativeMapUser\n");
+    return VERR_NOT_SUPPORTED;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeProtect(PRTR0MEMOBJINTERNAL pMem, size_t offSub, size_t cbSub, uint32_t fProt)
+{
+    vm_prot_t          ProtectionFlags = 0;
+    vaddr_t        AddrStart       = (vaddr_t)pMem->pv + offSub;
+    vm_map_t           pVmMap          = rtR0MemObjNetBSDGetMap(pMem);
+
+    if (!pVmMap)
+        return VERR_NOT_SUPPORTED;
+
+    if ((fProt & RTMEM_PROT_READ) == RTMEM_PROT_READ)
+        ProtectionFlags |= UVM_PROT_R;
+    if ((fProt & RTMEM_PROT_WRITE) == RTMEM_PROT_WRITE)
+        ProtectionFlags |= UVM_PROT_W;
+    if ((fProt & RTMEM_PROT_EXEC) == RTMEM_PROT_EXEC)
+        ProtectionFlags |= UVM_PROT_X;
+
+    int error = uvm_map_protect(pVmMap, AddrStart, AddrStart + cbSub,
+        ProtectionFlags, 0);
+    if (!error)
+        return VINF_SUCCESS;
+
+    return VERR_NOT_SUPPORTED;
+}
+
+
+DECLHIDDEN(RTHCPHYS) rtR0MemObjNativeGetPagePhysAddr(PRTR0MEMOBJINTERNAL pMem, size_t iPage)
+{
+    PRTR0MEMOBJNETBSD pMemNetBSD = (PRTR0MEMOBJNETBSD)pMem;
+
+    switch (pMemNetBSD->Core.enmType)
+    {
+        case RTR0MEMOBJTYPE_PAGE:
+        case RTR0MEMOBJTYPE_LOW:
+        {
+            vaddr_t va = (vaddr_t)pMemNetBSD->Core.pv + ptoa(iPage);
+            paddr_t pa = 0;
+            pmap_extract(pmap_kernel(), va, &pa);
+            return pa;
+        }
+        case RTR0MEMOBJTYPE_CONT:
+            return pMemNetBSD->Core.u.Cont.Phys + ptoa(iPage);
+        case RTR0MEMOBJTYPE_PHYS:
+            return pMemNetBSD->Core.u.Phys.PhysBase + ptoa(iPage);
+        case RTR0MEMOBJTYPE_PHYS_NC:
+        {
+            struct vm_page *page;
+            size_t i = 0;
+            TAILQ_FOREACH(page, &pMemNetBSD->pglist, pageq.queue)
+            {
+                if (i == iPage)
+                    break;
+                i++;
+            }
+            return VM_PAGE_TO_PHYS(page);
+        }
+        case RTR0MEMOBJTYPE_LOCK:
+        case RTR0MEMOBJTYPE_MAPPING:
+        {
+            pmap_t pmap;
+            if (pMem->u.Lock.R0Process == NIL_RTR0PROCESS)
+                pmap = pmap_kernel();
+            else
+                pmap = ((struct proc *)pMem->u.Lock.R0Process)->p_vmspace->vm_map.pmap;
+            vaddr_t va = (vaddr_t)pMemNetBSD->Core.pv + ptoa(iPage);
+            paddr_t pa = 0;
+            pmap_extract(pmap, va, &pa);
+            return pa;
+        }
+        case RTR0MEMOBJTYPE_RES_VIRT:
+            return NIL_RTHCPHYS;
+        default:
+            return NIL_RTHCPHYS;
+    }
+}
+
diff --git a/src/VBox/Runtime/r0drv/netbsd/memuserkernel-r0drv-netbsd.c b/src/VBox/Runtime/r0drv/netbsd/memuserkernel-r0drv-netbsd.c
new file mode 100644
index 00000000..c6cb7d0f
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/netbsd/memuserkernel-r0drv-netbsd.c
@@ -0,0 +1,82 @@
+/* $Id: memuserkernel-r0drv-netbsd.c $ */
+/** @file
+ * IPRT - User & Kernel Memory, Ring-0 Driver, NetBSD.
+ */
+
+/*
+ * Copyright (C) 2009-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-netbsd-kernel.h"
+
+#include <iprt/mem.h>
+#include <iprt/errcore.h>
+
+
+RTR0DECL(int) RTR0MemUserCopyFrom(void *pvDst, RTR3PTR R3PtrSrc, size_t cb)
+{
+    int rc = copyin((const void *)R3PtrSrc, pvDst, cb);
+    if (RT_LIKELY(rc == 0))
+        return VINF_SUCCESS;
+    return VERR_ACCESS_DENIED;
+}
+
+
+RTR0DECL(int) RTR0MemUserCopyTo(RTR3PTR R3PtrDst, void const *pvSrc, size_t cb)
+{
+    int rc = copyout(pvSrc, (void *)R3PtrDst, cb);
+    if (RT_LIKELY(rc == 0))
+        return VINF_SUCCESS;
+    return VERR_ACCESS_DENIED;
+}
+
+
+RTR0DECL(bool) RTR0MemUserIsValidAddr(RTR3PTR R3Ptr)
+{
+    return R3Ptr < VM_MAXUSER_ADDRESS;
+}
+
+
+RTR0DECL(bool) RTR0MemKernelIsValidAddr(void *pv)
+{
+    return (uintptr_t)pv >= VM_MAXUSER_ADDRESS;
+}
+
+
+RTR0DECL(bool) RTR0MemAreKrnlAndUsrDifferent(void)
+{
+    return true;
+}
+
+
+RTR0DECL(int) RTR0MemKernelCopyFrom(void *pvDst, void const *pvSrc, size_t cb)
+{
+    return VERR_NOT_SUPPORTED;
+}
+
+
+RTR0DECL(int) RTR0MemKernelCopyTo(void *pvDst, void const *pvSrc, size_t cb)
+{
+    return VERR_NOT_SUPPORTED;
+}
diff --git a/src/VBox/Runtime/r0drv/netbsd/mp-r0drv-netbsd.c b/src/VBox/Runtime/r0drv/netbsd/mp-r0drv-netbsd.c
new file mode 100644
index 00000000..f5dc52a7
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/netbsd/mp-r0drv-netbsd.c
@@ -0,0 +1,43 @@
+/* $Id: mp-r0drv-netbsd.c $ */
+/** @file
+ * IPRT - Multiprocessor, Ring-0 Driver, NetBSD.
+ */
+
+/*
+ * Copyright (C) 2008-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-netbsd-kernel.h"
+
+#include <iprt/mp.h>
+#include <iprt/errcore.h>
+#include <iprt/asm.h>
+#include <iprt/cpuset.h>
+#include "r0drv/mp-r0drv.h"
+
+
+RTDECL(RTCPUID) RTMpCpuId(void)
+{
+    return cpu_number();
+}
diff --git a/src/VBox/Runtime/r0drv/netbsd/process-r0drv-netbsd.c b/src/VBox/Runtime/r0drv/netbsd/process-r0drv-netbsd.c
new file mode 100644
index 00000000..13a01886
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/netbsd/process-r0drv-netbsd.c
@@ -0,0 +1,73 @@
+/* $Id: process-r0drv-netbsd.c $ */
+/** @file
+ * IPRT - Process Management, Ring-0 Driver, NetBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-netbsd-kernel.h"
+
+#include <iprt/process.h>
+
+
+RTDECL(RTPROCESS) RTProcSelf(void)
+{
+    struct proc *pSelf = curproc;
+    return pSelf->p_pid;
+}
+
+
+RTR0DECL(RTR0PROCESS) RTR0ProcHandleSelf(void)
+{
+    return (RTR0PROCESS)curproc;
+}
+
diff --git a/src/VBox/Runtime/r0drv/netbsd/semevent-r0drv-netbsd.c b/src/VBox/Runtime/r0drv/netbsd/semevent-r0drv-netbsd.c
new file mode 100644
index 00000000..1d72b109
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/netbsd/semevent-r0drv-netbsd.c
@@ -0,0 +1,277 @@
+/* $Id: semevent-r0drv-netbsd.c $ */
+/** @file
+ * IPRT - Single Release Event Semaphores, Ring-0 Driver, NetBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTSEMEVENT_WITHOUT_REMAPPING
+#include "the-netbsd-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/semaphore.h>
+
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/lockvalidator.h>
+#include <iprt/mem.h>
+
+#include "sleepqueue-r0drv-netbsd.h"
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * NetBSD event semaphore.
+ */
+typedef struct RTSEMEVENTINTERNAL
+{
+    /** Magic value (RTSEMEVENT_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** The object status - !0 when signaled and 0 when reset. */
+    uint32_t volatile   fState;
+    /** Reference counter. */
+    uint32_t volatile   cRefs;
+} RTSEMEVENTINTERNAL, *PRTSEMEVENTINTERNAL;
+
+
+RTDECL(int)  RTSemEventCreate(PRTSEMEVENT phEventSem)
+{
+    return RTSemEventCreateEx(phEventSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, NULL);
+}
+
+
+RTDECL(int)  RTSemEventCreateEx(PRTSEMEVENT phEventSem, uint32_t fFlags, RTLOCKVALCLASS hClass, const char *pszNameFmt, ...)
+{
+    AssertCompile(sizeof(RTSEMEVENTINTERNAL) > sizeof(void *));
+    AssertReturn(!(fFlags & ~(RTSEMEVENT_FLAGS_NO_LOCK_VAL | RTSEMEVENT_FLAGS_BOOTSTRAP_HACK)), VERR_INVALID_PARAMETER);
+    Assert(!(fFlags & RTSEMEVENT_FLAGS_BOOTSTRAP_HACK) || (fFlags & RTSEMEVENT_FLAGS_NO_LOCK_VAL));
+    AssertPtrReturn(phEventSem, VERR_INVALID_POINTER);
+
+    PRTSEMEVENTINTERNAL pThis = (PRTSEMEVENTINTERNAL)RTMemAllocZ(sizeof(*pThis));
+    if (!pThis)
+        return VERR_NO_MEMORY;
+
+    pThis->u32Magic  = RTSEMEVENT_MAGIC;
+    pThis->cRefs     = 1;
+    pThis->fState    = 0;
+
+    *phEventSem = pThis;
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Retains a reference to the event semaphore.
+ *
+ * @param   pThis       The event semaphore.
+ */
+DECLINLINE(void) rtR0SemEventBsdRetain(PRTSEMEVENTINTERNAL pThis)
+{
+    uint32_t cRefs = ASMAtomicIncU32(&pThis->cRefs);
+    Assert(cRefs < 100000); NOREF(cRefs);
+}
+
+
+/**
+ * Releases a reference to the event semaphore.
+ *
+ * @param   pThis       The event semaphore.
+ */
+DECLINLINE(void) rtR0SemEventBsdRelease(PRTSEMEVENTINTERNAL pThis)
+{
+    if (RT_UNLIKELY(ASMAtomicDecU32(&pThis->cRefs) == 0))
+        RTMemFree(pThis);
+}
+
+
+RTDECL(int)  RTSemEventDestroy(RTSEMEVENT hEventSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTINTERNAL pThis = hEventSem;
+    if (pThis == NIL_RTSEMEVENT)
+        return VINF_SUCCESS;
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("pThis->u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+    Assert(pThis->cRefs > 0);
+
+    /*
+     * Invalidate it and signal the object just in case.
+     */
+    ASMAtomicWriteU32(&pThis->u32Magic, ~RTSEMEVENT_MAGIC);
+    ASMAtomicWriteU32(&pThis->fState, 0);
+    rtR0SemBsdBroadcast(pThis);
+    rtR0SemEventBsdRelease(pThis);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemEventSignal(RTSEMEVENT hEventSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTINTERNAL pThis = (PRTSEMEVENTINTERNAL)hEventSem;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("pThis->u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+    rtR0SemEventBsdRetain(pThis);
+
+    /*
+     * Signal the event object.
+     */
+    ASMAtomicWriteU32(&pThis->fState, 1);
+    rtR0SemBsdSignal(pThis);
+    rtR0SemEventBsdRelease(pThis);
+    return VINF_SUCCESS;
+}
+
+/**
+ * Worker for RTSemEventWaitEx and RTSemEventWaitExDebug.
+ *
+ * @returns VBox status code.
+ * @param   pThis           The event semaphore.
+ * @param   fFlags          See RTSemEventWaitEx.
+ * @param   uTimeout        See RTSemEventWaitEx.
+ * @param   pSrcPos         The source code position of the wait.
+ */
+static int rtR0SemEventWait(PRTSEMEVENTINTERNAL pThis, uint32_t fFlags, uint64_t uTimeout,
+                            PCRTLOCKVALSRCPOS pSrcPos)
+{
+    int rc;
+
+    /*
+     * Validate the input.
+     */
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    AssertReturn(RTSEMWAIT_FLAGS_ARE_VALID(fFlags), VERR_INVALID_PARAMETER);
+    rtR0SemEventBsdRetain(pThis);
+
+    /*
+     * Try grab the event without setting up the wait.
+     */
+    if (ASMAtomicCmpXchgU32(&pThis->fState, 0, 1))
+        rc = VINF_SUCCESS;
+    else
+    {
+        /*
+         * We have to wait.
+         */
+        RTR0SEMBSDSLEEP Wait;
+        rc = rtR0SemBsdWaitInit(&Wait, fFlags, uTimeout, pThis);
+        if (RT_SUCCESS(rc))
+        {
+            for (;;)
+            {
+                /* The destruction test. */
+                if (RT_UNLIKELY(pThis->u32Magic != RTSEMEVENT_MAGIC))
+                    rc = VERR_SEM_DESTROYED;
+                else
+                {
+                    rtR0SemBsdWaitPrepare(&Wait);
+
+                    /* Check the exit conditions. */
+                    if (RT_UNLIKELY(pThis->u32Magic != RTSEMEVENT_MAGIC))
+                        rc = VERR_SEM_DESTROYED;
+                    else if (ASMAtomicCmpXchgU32(&pThis->fState, 0, 1))
+                        rc = VINF_SUCCESS;
+                    else if (rtR0SemBsdWaitHasTimedOut(&Wait))
+                        rc = VERR_TIMEOUT;
+                    else if (rtR0SemBsdWaitWasInterrupted(&Wait))
+                        rc = VERR_INTERRUPTED;
+                    else
+                    {
+                        /* Do the wait and then recheck the conditions. */
+                        rtR0SemBsdWaitDoIt(&Wait);
+                        continue;
+                    }
+                }
+                break;
+            }
+
+            rtR0SemBsdWaitDelete(&Wait);
+        }
+    }
+
+    rtR0SemEventBsdRelease(pThis);
+    return rc;
+}
+
+
+RTDECL(int)  RTSemEventWaitEx(RTSEMEVENT hEventSem, uint32_t fFlags, uint64_t uTimeout)
+{
+#ifndef RTSEMEVENT_STRICT
+    return rtR0SemEventWait(hEventSem, fFlags, uTimeout, NULL);
+#else
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
+    return rtR0SemEventWait(hEventSem, fFlags, uTimeout, &SrcPos);
+#endif
+}
+RT_EXPORT_SYMBOL(RTSemEventWaitEx);
+
+
+RTDECL(int)  RTSemEventWaitExDebug(RTSEMEVENT hEventSem, uint32_t fFlags, uint64_t uTimeout,
+                                   RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
+    return rtR0SemEventWait(hEventSem, fFlags, uTimeout, &SrcPos);
+}
+RT_EXPORT_SYMBOL(RTSemEventWaitExDebug);
+
+
+RTDECL(uint32_t) RTSemEventGetResolution(void)
+{
+    return 1000000000 / hz;
+}
diff --git a/src/VBox/Runtime/r0drv/netbsd/semeventmulti-r0drv-netbsd.c b/src/VBox/Runtime/r0drv/netbsd/semeventmulti-r0drv-netbsd.c
new file mode 100644
index 00000000..c3669c2d
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/netbsd/semeventmulti-r0drv-netbsd.c
@@ -0,0 +1,341 @@
+/* $Id: semeventmulti-r0drv-netbsd.c $ */
+/** @file
+ * IPRT - Multiple Release Event Semaphores, Ring-0 Driver, NetBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTSEMEVENTMULTI_WITHOUT_REMAPPING
+#include "the-netbsd-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/semaphore.h>
+
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+#include <iprt/err.h>
+#include <iprt/mem.h>
+#include <iprt/lockvalidator.h>
+
+#include "sleepqueue-r0drv-netbsd.h"
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+/** @name fStateAndGen values
+ * @{ */
+/** The state bit number. */
+#define RTSEMEVENTMULTIBSD_STATE_BIT        0
+/** The state mask. */
+#define RTSEMEVENTMULTIBSD_STATE_MASK       RT_BIT_32(RTSEMEVENTMULTIBSD_STATE_BIT)
+/** The generation mask. */
+#define RTSEMEVENTMULTIBSD_GEN_MASK         ~RTSEMEVENTMULTIBSD_STATE_MASK
+/** The generation shift. */
+#define RTSEMEVENTMULTIBSD_GEN_SHIFT        1
+/** The initial variable value. */
+#define RTSEMEVENTMULTIBSD_STATE_GEN_INIT   UINT32_C(0xfffffffc)
+/** @}  */
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * NetBSD multiple release event semaphore.
+ */
+typedef struct RTSEMEVENTMULTIINTERNAL
+{
+    /** Magic value (RTSEMEVENTMULTI_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** The object state bit and generation counter.
+     * The generation counter is incremented every time the object is
+     * signalled. */
+    uint32_t volatile   fStateAndGen;
+    /** Reference counter. */
+    uint32_t volatile   cRefs;
+} RTSEMEVENTMULTIINTERNAL, *PRTSEMEVENTMULTIINTERNAL;
+
+
+RTDECL(int)  RTSemEventMultiCreate(PRTSEMEVENTMULTI phEventMultiSem)
+{
+    return RTSemEventMultiCreateEx(phEventMultiSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, NULL);
+}
+
+
+RTDECL(int)  RTSemEventMultiCreateEx(PRTSEMEVENTMULTI phEventMultiSem, uint32_t fFlags, RTLOCKVALCLASS hClass,
+                                     const char *pszNameFmt, ...)
+{
+    PRTSEMEVENTMULTIINTERNAL pThis;
+
+    AssertReturn(!(fFlags & ~RTSEMEVENTMULTI_FLAGS_NO_LOCK_VAL), VERR_INVALID_PARAMETER);
+    pThis = (PRTSEMEVENTMULTIINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (pThis)
+    {
+        pThis->u32Magic     = RTSEMEVENTMULTI_MAGIC;
+        pThis->fStateAndGen = RTSEMEVENTMULTIBSD_STATE_GEN_INIT;
+        pThis->cRefs        = 1;
+
+        *phEventMultiSem = pThis;
+        return VINF_SUCCESS;
+    }
+    return VERR_NO_MEMORY;
+}
+
+
+/**
+ * Retain a reference to the semaphore.
+ *
+ * @param   pThis       The semaphore.
+ */
+DECLINLINE(void) rtR0SemEventMultiBsdRetain(PRTSEMEVENTMULTIINTERNAL pThis)
+{
+    uint32_t cRefs = ASMAtomicIncU32(&pThis->cRefs);
+    Assert(cRefs && cRefs < 100000);
+}
+
+
+/**
+ * Release a reference, destroy the thing if necessary.
+ *
+ * @param   pThis       The semaphore.
+ */
+DECLINLINE(void) rtR0SemEventMultiBsdRelease(PRTSEMEVENTMULTIINTERNAL pThis)
+{
+    if (RT_UNLIKELY(ASMAtomicDecU32(&pThis->cRefs) == 0))
+    {
+        Assert(pThis->u32Magic != RTSEMEVENTMULTI_MAGIC);
+        RTMemFree(pThis);
+    }
+}
+
+
+RTDECL(int)  RTSemEventMultiDestroy(RTSEMEVENTMULTI hEventMultiSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    if (pThis == NIL_RTSEMEVENTMULTI)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    Assert(pThis->cRefs > 0);
+
+    /*
+     * Invalidate it and signal the object just in case.
+     */
+    ASMAtomicWriteU32(&pThis->u32Magic, ~RTSEMEVENTMULTI_MAGIC);
+    ASMAtomicAndU32(&pThis->fStateAndGen, RTSEMEVENTMULTIBSD_GEN_MASK);
+    rtR0SemBsdBroadcast(pThis);
+    rtR0SemEventMultiBsdRelease(pThis);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemEventMultiSignal(RTSEMEVENTMULTI hEventMultiSem)
+{
+    uint32_t fNew;
+    uint32_t fOld;
+
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    if (!pThis)
+        return VERR_INVALID_PARAMETER;
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    rtR0SemEventMultiBsdRetain(pThis);
+
+    /*
+     * Signal the event object.  The cause of the parnoia here is racing to try
+     * deal with racing RTSemEventMultiSignal calls (should probably be
+     * forbidden, but it's relatively easy to handle).
+     */
+    do
+    {
+        fNew = fOld = ASMAtomicUoReadU32(&pThis->fStateAndGen);
+        fNew += 1 << RTSEMEVENTMULTIBSD_GEN_SHIFT;
+        fNew |= RTSEMEVENTMULTIBSD_STATE_MASK;
+    }
+    while (!ASMAtomicCmpXchgU32(&pThis->fStateAndGen, fNew, fOld));
+
+    rtR0SemBsdBroadcast(pThis);
+    rtR0SemEventMultiBsdRelease(pThis);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemEventMultiReset(RTSEMEVENTMULTI hEventMultiSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    if (!pThis)
+        return VERR_INVALID_PARAMETER;
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    rtR0SemEventMultiBsdRetain(pThis);
+
+    /*
+     * Reset it.
+     */
+    ASMAtomicAndU32(&pThis->fStateAndGen, ~RTSEMEVENTMULTIBSD_STATE_MASK);
+
+    rtR0SemEventMultiBsdRelease(pThis);
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Worker for RTSemEventMultiWaitEx and RTSemEventMultiWaitExDebug.
+ *
+ * @returns VBox status code.
+ * @param   pThis           The event semaphore.
+ * @param   fFlags          See RTSemEventMultiWaitEx.
+ * @param   uTimeout        See RTSemEventMultiWaitEx.
+ * @param   pSrcPos         The source code position of the wait.
+ */
+static int rtR0SemEventMultiBsdWait(PRTSEMEVENTMULTIINTERNAL pThis, uint32_t fFlags, uint64_t uTimeout,
+                                    PCRTLOCKVALSRCPOS pSrcPos)
+{
+    uint32_t    fOrgStateAndGen;
+    int         rc;
+
+    /*
+     * Validate the input.
+     */
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    AssertReturn(RTSEMWAIT_FLAGS_ARE_VALID(fFlags), VERR_INVALID_PARAMETER);
+    rtR0SemEventMultiBsdRetain(pThis);
+
+    /*
+     * Is the event already signalled or do we have to wait?
+     */
+    fOrgStateAndGen = ASMAtomicUoReadU32(&pThis->fStateAndGen);
+    if (fOrgStateAndGen & RTSEMEVENTMULTIBSD_STATE_MASK)
+        rc = VINF_SUCCESS;
+    else
+    {
+        /*
+         * We have to wait.
+         */
+        RTR0SEMBSDSLEEP Wait;
+        rc = rtR0SemBsdWaitInit(&Wait, fFlags, uTimeout, pThis);
+        if (RT_SUCCESS(rc))
+        {
+            for (;;)
+            {
+                /* The destruction test. */
+                if (RT_UNLIKELY(pThis->u32Magic != RTSEMEVENTMULTI_MAGIC))
+                    rc = VERR_SEM_DESTROYED;
+                else
+                {
+                    rtR0SemBsdWaitPrepare(&Wait);
+
+                    /* Check the exit conditions. */
+                    if (RT_UNLIKELY(pThis->u32Magic != RTSEMEVENTMULTI_MAGIC))
+                        rc = VERR_SEM_DESTROYED;
+                    else if (ASMAtomicUoReadU32(&pThis->fStateAndGen) != fOrgStateAndGen)
+                        rc = VINF_SUCCESS;
+                    else if (rtR0SemBsdWaitHasTimedOut(&Wait))
+                        rc = VERR_TIMEOUT;
+                    else if (rtR0SemBsdWaitWasInterrupted(&Wait))
+                        rc = VERR_INTERRUPTED;
+                    else
+                    {
+                        /* Do the wait and then recheck the conditions. */
+                        rtR0SemBsdWaitDoIt(&Wait);
+                        continue;
+                    }
+                }
+                break;
+            }
+
+            rtR0SemBsdWaitDelete(&Wait);
+        }
+    }
+
+    rtR0SemEventMultiBsdRelease(pThis);
+    return rc;
+}
+
+
+RTDECL(int)  RTSemEventMultiWaitEx(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout)
+{
+#ifndef RTSEMEVENT_STRICT
+    return rtR0SemEventMultiBsdWait(hEventMultiSem, fFlags, uTimeout, NULL);
+#else
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
+    return rtR0SemEventMultiBsdWait(hEventMultiSem, fFlags, uTimeout, &SrcPos);
+#endif
+}
+RT_EXPORT_SYMBOL(RTSemEventMultiWaitEx);
+
+
+RTDECL(int)  RTSemEventMultiWaitExDebug(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout,
+                                        RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
+    return rtR0SemEventMultiBsdWait(hEventMultiSem, fFlags, uTimeout, &SrcPos);
+}
+RT_EXPORT_SYMBOL(RTSemEventMultiWaitExDebug);
+
+
+RTDECL(uint32_t) RTSemEventMultiGetResolution(void)
+{
+    return rtR0SemBsdWaitGetResolution();
+}
+RT_EXPORT_SYMBOL(RTSemEventMultiGetResolution);
diff --git a/src/VBox/Runtime/r0drv/netbsd/semfastmutex-r0drv-netbsd.c b/src/VBox/Runtime/r0drv/netbsd/semfastmutex-r0drv-netbsd.c
new file mode 100644
index 00000000..ad3c4d58
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/netbsd/semfastmutex-r0drv-netbsd.c
@@ -0,0 +1,136 @@
+/* $Id: semfastmutex-r0drv-netbsd.c $ */
+/** @file
+ * IPRT - Fast Mutex Semaphores, Ring-0 Driver, NetBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-netbsd-kernel.h"
+
+#include <iprt/semaphore.h>
+#include <iprt/errcore.h>
+#include <iprt/alloc.h>
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Wrapper for the NetBSD (sleep) mutex.
+ */
+typedef struct RTSEMFASTMUTEXINTERNAL
+{
+    /** Magic value (RTSEMFASTMUTEX_MAGIC). */
+    uint32_t            u32Magic;
+    /** The NetBSD shared/exclusive lock mutex. */
+    krwlock_t           Mtx;
+} RTSEMFASTMUTEXINTERNAL, *PRTSEMFASTMUTEXINTERNAL;
+
+
+RTDECL(int)  RTSemFastMutexCreate(PRTSEMFASTMUTEX phFastMtx)
+{
+    AssertCompile(sizeof(RTSEMFASTMUTEXINTERNAL) > sizeof(void *));
+    AssertPtrReturn(phFastMtx, VERR_INVALID_POINTER);
+
+    PRTSEMFASTMUTEXINTERNAL pThis = (PRTSEMFASTMUTEXINTERNAL)RTMemAllocZ(sizeof(*pThis));
+    if (pThis)
+    {
+        pThis->u32Magic = RTSEMFASTMUTEX_MAGIC;
+        rw_init(&pThis->Mtx);
+
+        *phFastMtx = pThis;
+        return VINF_SUCCESS;
+    }
+    return VERR_NO_MEMORY;
+}
+
+
+RTDECL(int)  RTSemFastMutexDestroy(RTSEMFASTMUTEX hFastMtx)
+{
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    if (pThis == NIL_RTSEMFASTMUTEX)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    ASMAtomicWriteU32(&pThis->u32Magic, RTSEMFASTMUTEX_MAGIC_DEAD);
+    rw_destroy(&pThis->Mtx);
+    RTMemFree(pThis);
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemFastMutexRequest(RTSEMFASTMUTEX hFastMtx)
+{
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    rw_enter(&pThis->Mtx, RW_WRITER);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemFastMutexRelease(RTSEMFASTMUTEX hFastMtx)
+{
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    rw_exit(&pThis->Mtx);
+    return VINF_SUCCESS;
+}
diff --git a/src/VBox/Runtime/r0drv/netbsd/semmutex-r0drv-netbsd.c b/src/VBox/Runtime/r0drv/netbsd/semmutex-r0drv-netbsd.c
new file mode 100644
index 00000000..c028bb30
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/netbsd/semmutex-r0drv-netbsd.c
@@ -0,0 +1,218 @@
+/* $Id: semmutex-r0drv-netbsd.c $ */
+/** @file
+ * IPRT - Mutex Semaphores, Ring-0 Driver, NetBSD.
+ */
+
+/*
+ * Copyright (C) 2010-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTSEMMUTEX_WITHOUT_REMAPPING
+#include "the-netbsd-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/semaphore.h>
+
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+#include <iprt/mem.h>
+#include <iprt/thread.h>
+#include <iprt/time.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Wrapper for the NetBSD (sleep) mutex.
+ */
+typedef struct RTSEMMUTEXINTERNAL
+{
+    /** Magic value (RTSEMMUTEX_MAGIC). */
+    uint32_t            u32Magic;
+    /** The NetBSD shared/exclusive lock mutex. */
+    struct sx           SxLock;
+} RTSEMMUTEXINTERNAL, *PRTSEMMUTEXINTERNAL;
+
+
+RTDECL(int)  RTSemMutexCreate(PRTSEMMUTEX phMutexSem)
+{
+    AssertCompile(sizeof(RTSEMMUTEXINTERNAL) > sizeof(void *));
+    AssertPtrReturn(phMutexSem, VERR_INVALID_POINTER);
+
+    PRTSEMMUTEXINTERNAL pThis = (PRTSEMMUTEXINTERNAL)RTMemAllocZ(sizeof(*pThis));
+    if (pThis)
+    {
+        pThis->u32Magic = RTSEMMUTEX_MAGIC;
+        sx_init_flags(&pThis->SxLock, "IPRT Mutex Semaphore", SX_RECURSE);
+
+        *phMutexSem = pThis;
+        return VINF_SUCCESS;
+    }
+    return VERR_NO_MEMORY;
+}
+
+
+RTDECL(int)  RTSemMutexDestroy(RTSEMMUTEX hMutexSem)
+{
+    PRTSEMMUTEXINTERNAL pThis = hMutexSem;
+    if (pThis == NIL_RTSEMMUTEX)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    AssertReturn(ASMAtomicCmpXchgU32(&pThis->u32Magic, RTSEMMUTEX_MAGIC_DEAD, RTSEMMUTEX_MAGIC), VERR_INVALID_HANDLE);
+
+    sx_destroy(&pThis->SxLock);
+    RTMemFree(pThis);
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemMutexRequest(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies)
+{
+    PRTSEMMUTEXINTERNAL pThis = hMutexSem;
+    int                 rc;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    if (cMillies == RT_INDEFINITE_WAIT)
+    {
+        sx_xlock(&pThis->SxLock);
+        rc = VINF_SUCCESS;
+    }
+    else if (!cMillies)
+    {
+        if (sx_try_xlock(&pThis->SxLock))
+            rc = VINF_SUCCESS;
+        else
+            rc = VERR_TIMEOUT;
+    }
+    /*
+     * GROSS HACK: poll implementation of timeout.
+     */
+    /** @todo Implement timeouts in RTSemMutexRequest. */
+    else if (sx_try_xlock(&pThis->SxLock))
+        rc = VINF_SUCCESS;
+    else
+    {
+        uint64_t StartTS = RTTimeSystemMilliTS();
+        rc = VERR_TIMEOUT;
+        do
+        {
+            RTThreadSleep(1);
+            if (sx_try_xlock(&pThis->SxLock))
+            {
+                rc = VINF_SUCCESS;
+                break;
+            }
+        } while (RTTimeSystemMilliTS() - StartTS < cMillies);
+    }
+
+    return rc;
+}
+
+
+RTDECL(int) RTSemMutexRequestDebug(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    return RTSemMutexRequest(hMutexSem, cMillies);
+}
+
+
+RTDECL(int)  RTSemMutexRequestNoResume(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies)
+{
+    PRTSEMMUTEXINTERNAL pThis = hMutexSem;
+    int                 rc;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    if (cMillies == RT_INDEFINITE_WAIT)
+    {
+        if (!sx_xlock_sig(&pThis->SxLock))
+            rc = VINF_SUCCESS;
+        else
+            rc = VERR_INTERRUPTED;
+    }
+    else if (!cMillies)
+    {
+        if (sx_try_xlock(&pThis->SxLock))
+            rc = VINF_SUCCESS;
+        else
+            rc = VERR_TIMEOUT;
+    }
+    /*
+     * GROSS HACK: poll implementation of timeout.
+     */
+    /** @todo Implement timeouts and interrupt checks in
+     *        RTSemMutexRequestNoResume. */
+    else if (sx_try_xlock(&pThis->SxLock))
+        rc = VINF_SUCCESS;
+    else
+    {
+        uint64_t StartTS = RTTimeSystemMilliTS();
+        rc = VERR_TIMEOUT;
+        do
+        {
+            RTThreadSleep(1);
+            if (sx_try_xlock(&pThis->SxLock))
+            {
+                rc = VINF_SUCCESS;
+                break;
+            }
+        } while (RTTimeSystemMilliTS() - StartTS < cMillies);
+    }
+
+    return rc;
+}
+
+
+RTDECL(int) RTSemMutexRequestNoResumeDebug(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    return RTSemMutexRequestNoResume(hMutexSem, cMillies);
+}
+
+
+RTDECL(int)  RTSemMutexRelease(RTSEMMUTEX hMutexSem)
+{
+    PRTSEMMUTEXINTERNAL pThis = hMutexSem;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    sx_xunlock(&pThis->SxLock);
+    return VINF_SUCCESS;
+}
+
+
+
+RTDECL(bool) RTSemMutexIsOwned(RTSEMMUTEX hMutexSem)
+{
+    PRTSEMMUTEXINTERNAL pThis = hMutexSem;
+    AssertPtrReturn(pThis, false);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), false);
+
+    return sx_xlocked(&pThis->SxLock);
+}
diff --git a/src/VBox/Runtime/r0drv/netbsd/sleepqueue-r0drv-netbsd.h b/src/VBox/Runtime/r0drv/netbsd/sleepqueue-r0drv-netbsd.h
new file mode 100644
index 00000000..e90bb7c6
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/netbsd/sleepqueue-r0drv-netbsd.h
@@ -0,0 +1,281 @@
+/* $Id: sleepqueue-r0drv-netbsd.h $ */
+/** @file
+ * IPRT - NetBSD Ring-0 Driver Helpers for Abstracting Sleep Queues,
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+#ifndef IPRT_INCLUDED_SRC_r0drv_netbsd_sleepqueue_r0drv_netbsd_h
+#define IPRT_INCLUDED_SRC_r0drv_netbsd_sleepqueue_r0drv_netbsd_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include "the-netbsd-kernel.h"
+
+#include <iprt/asm-math.h>
+#include <iprt/err.h>
+#include <iprt/time.h>
+
+static syncobj_t vbox_syncobj = {
+        SOBJ_SLEEPQ_SORTED,
+        sleepq_unsleep,
+        sleepq_changepri,
+        sleepq_lendpri,
+        syncobj_noowner,
+};
+
+/**
+ * Kernel mode NetBSD wait state structure.
+ */
+typedef struct RTR0SEMBSDSLEEP
+{
+    /** The absolute timeout given as nano seconds since the start of the
+     *  monotonic clock. */
+    uint64_t        uNsAbsTimeout;
+    /** The timeout in ticks. Updated after waiting. */
+    int             iTimeout;
+    /** Set if it's an indefinite wait. */
+    bool            fIndefinite;
+    /** Set if we've already timed out.
+     * Set by rtR0SemBsdWaitDoIt and read by rtR0SemBsdWaitHasTimedOut. */
+    bool            fTimedOut;
+    /** Flag whether the wait was interrupted. */
+    bool            fInterrupted;
+    /** flag whether the wait is interruptible or not. */
+    bool            fInterruptible;
+    /** Opaque wait channel id. */
+    wchan_t         wchan;
+    sleepq_t *sq;
+    kmutex_t *sq_lock;
+} RTR0SEMBSDSLEEP;
+/** Pointer to a NetBSD wait state. */
+typedef RTR0SEMBSDSLEEP *PRTR0SEMBSDSLEEP;
+
+
+/**
+ * Updates the timeout of the NetBSD wait.
+ *
+ * @returns RTSEMWAIT_FLAGS_INDEFINITE if the timeout value is too big.
+ *          0 otherwise
+ * @param   pWait               The wait structure.
+ * @param   uTimeout            The relative timeout in nanoseconds.
+ */
+DECLINLINE(void) rtR0SemBsdWaitUpdateTimeout(PRTR0SEMBSDSLEEP pWait)
+{
+    /* Convert absolute timeout to ticks */
+    uint64_t now = RTTimeNanoTS();
+    if (now >= pWait->uNsAbsTimeout) {
+        pWait->iTimeout = 0;
+    } else {
+        uint64_t nanos = pWait->uNsAbsTimeout - now;
+        pWait->iTimeout = hz * nanos / 1000000000;
+        /* for 1ms wait, wait at least one tick ?? */
+        if ((pWait->iTimeout == 0) && (nanos >= 1000000)) {
+            pWait->iTimeout = 1;
+        }
+    }
+}
+
+/**
+ * Initializes a wait.
+ *
+ * The caller MUST check the wait condition BEFORE calling this function or the
+ * timeout logic will be flawed.
+ *
+ * @returns VINF_SUCCESS or VERR_TIMEOUT.
+ * @param   pWait               The wait structure.
+ * @param   fFlags              The wait flags.
+ * @param   uTimeout            The timeout.
+ * @param   pvWaitChan          The opaque wait channel.
+ */
+DECLINLINE(int) rtR0SemBsdWaitInit(PRTR0SEMBSDSLEEP pWait, uint32_t fFlags, uint64_t uTimeout,
+                                   void *pvWaitChan)
+{
+    if (fFlags & RTSEMWAIT_FLAGS_INDEFINITE) {
+        pWait->fIndefinite      = true;
+        pWait->iTimeout = 0;
+        pWait->uNsAbsTimeout = 0;
+    } else {
+        if (fFlags & RTSEMWAIT_FLAGS_RELATIVE) {
+            if (fFlags & RTSEMWAIT_FLAGS_MILLISECS) {
+                pWait->uNsAbsTimeout = uTimeout * 1000000 + RTTimeSystemNanoTS();
+            } else {
+                pWait->uNsAbsTimeout = uTimeout + RTTimeSystemNanoTS();
+            }
+        } else {
+            if (fFlags & RTSEMWAIT_FLAGS_MILLISECS) {
+                pWait->uNsAbsTimeout = uTimeout * 1000000;
+            } else {
+                pWait->uNsAbsTimeout = uTimeout;
+            }
+        }
+        rtR0SemBsdWaitUpdateTimeout(pWait);
+        if (pWait->iTimeout == 0) {
+            return VERR_TIMEOUT;
+        }
+    }
+
+    pWait->fTimedOut   = false;
+    /*
+     * Initialize the wait queue related bits.
+     */
+    pWait->fInterruptible = fFlags & RTSEMWAIT_FLAGS_INTERRUPTIBLE
+                            ? true : false;
+    pWait->fInterrupted   = false;
+    pWait->wchan = pvWaitChan;
+    pWait->sq = NULL;
+    pWait->sq_lock = NULL;
+
+    return VINF_SUCCESS;
+}
+
+/**
+ * Prepares the next wait.
+ *
+ * This must be called before rtR0SemBsdWaitDoIt, and the caller should check
+ * the exit conditions inbetween the two calls.
+ *
+ * @param   pWait               The wait structure.
+ */
+DECLINLINE(void) rtR0SemBsdWaitPrepare(PRTR0SEMBSDSLEEP pWait)
+{
+    pWait->sq = sleeptab_lookup(&sleeptab, pWait->wchan, &pWait->sq_lock);
+}
+
+/**
+ * Do the actual wait.
+ *
+ * @param   pWait               The wait structure.
+ */
+DECLINLINE(void) rtR0SemBsdWaitDoIt(PRTR0SEMBSDSLEEP pWait)
+{
+    sleepq_enter(pWait->sq, curlwp, pWait->sq_lock);
+    sleepq_enqueue(pWait->sq, pWait->wchan, "VBoxIS", &vbox_syncobj);
+
+    pWait->sq = NULL;
+    pWait->sq_lock = NULL;
+
+    int error = sleepq_block(pWait->iTimeout, pWait->fInterruptible);
+    if (error == EWOULDBLOCK) {
+        if (!pWait->fIndefinite) {
+            pWait->fTimedOut = true;
+        }
+    } else if (error == ERESTART) {
+        if (pWait->fInterruptible) {
+            pWait->fInterrupted = true;
+        } else if (!pWait->fIndefinite) {
+            rtR0SemBsdWaitUpdateTimeout(pWait);
+            if (pWait->iTimeout == 0) {
+                pWait->fTimedOut = true;
+            }
+        }
+    } else if (error == EINTR) {
+        if (pWait->fInterruptible) {
+            pWait->fInterrupted = true;
+        } else if (!pWait->fIndefinite) {
+            rtR0SemBsdWaitUpdateTimeout(pWait);
+            if (pWait->iTimeout == 0) {
+                pWait->fTimedOut = true;
+            }
+        }
+    } else if (error) {
+        AssertMsgFailed(("sleepq_block -> %d\n", error));
+    }
+}
+
+
+/**
+ * Checks if a NetBSD wait was interrupted.
+ *
+ * @returns true / false
+ * @param   pWait               The wait structure.
+ * @remarks This shall be called before the first rtR0SemLnxWaitDoIt().
+ */
+DECLINLINE(bool) rtR0SemBsdWaitWasInterrupted(PRTR0SEMBSDSLEEP pWait)
+{
+    return pWait->fInterrupted;
+}
+
+
+/**
+ * Checks if a NetBSD wait has timed out.
+ *
+ * @returns true / false
+ * @param   pWait               The wait structure.
+ */
+DECLINLINE(bool) rtR0SemBsdWaitHasTimedOut(PRTR0SEMBSDSLEEP pWait)
+{
+    return pWait->fTimedOut;
+}
+
+
+/**
+ * Deletes a NetBSD wait.
+ *
+ * @param   pWait               The wait structure.
+ */
+DECLINLINE(void) rtR0SemBsdWaitDelete(PRTR0SEMBSDSLEEP pWait)
+{
+    if (pWait->sq_lock != NULL) {
+        mutex_spin_exit(pWait->sq_lock);
+        pWait->sq = NULL;
+        pWait->sq_lock = NULL;
+    }
+}
+
+
+/**
+ * Signals the wait channel.
+ *
+ * @param  pvWaitChan           The opaque wait channel handle.
+ */
+DECLINLINE(void) rtR0SemBsdSignal(void *pvWaitChan)
+{
+    kmutex_t *mp;
+    sleepq_t *sq = sleeptab_lookup(&sleeptab, pvWaitChan, &mp);
+    sleepq_wake(sq, pvWaitChan, 1, mp);
+}
+
+/**
+ * Wakes up all waiters on the wait channel.
+ *
+ * @param  pvWaitChan           The opaque wait channel handle.
+ */
+DECLINLINE(void) rtR0SemBsdBroadcast(void *pvWaitChan)
+{
+    kmutex_t *mp;
+    sleepq_t *sq = sleeptab_lookup(&sleeptab, pvWaitChan, &mp);
+    sleepq_wake(sq, pvWaitChan, ~0u, mp);
+}
+
+/**
+ * Gets the max resolution of the timeout machinery.
+ *
+ * @returns Resolution specified in nanoseconds.
+ */
+DECLINLINE(uint32_t) rtR0SemBsdWaitGetResolution(void)
+{
+    return 1000000000 / hz; /* ns */
+}
+
+#endif /* !IPRT_INCLUDED_SRC_r0drv_netbsd_sleepqueue_r0drv_netbsd_h */
diff --git a/src/VBox/Runtime/r0drv/netbsd/spinlock-r0drv-netbsd.c b/src/VBox/Runtime/r0drv/netbsd/spinlock-r0drv-netbsd.c
new file mode 100644
index 00000000..6d500f9f
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/netbsd/spinlock-r0drv-netbsd.c
@@ -0,0 +1,170 @@
+/* $Id: spinlock-r0drv-netbsd.c $ */
+/** @file
+ * IPRT - Spinlocks, Ring-0 Driver, NetBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-netbsd-kernel.h"
+#include "internal/iprt.h"
+
+#include <iprt/spinlock.h>
+#include <iprt/errcore.h>
+#include <iprt/alloc.h>
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+#include <iprt/asm-amd64-x86.h>
+#include <iprt/thread.h>
+#include <iprt/mp.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Wrapper for the struct mtx type.
+ */
+typedef struct RTSPINLOCKINTERNAL
+{
+    /** Spinlock magic value (RTSPINLOCK_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** The spinlock. */
+    kmutex_t            pSpinLock;
+    /** Saved interrupt flag. */
+    uint32_t volatile   fIntSaved;
+    /** The spinlock creation flags. */
+    uint32_t            fFlags;
+} RTSPINLOCKINTERNAL, *PRTSPINLOCKINTERNAL;
+
+
+RTDECL(int)  RTSpinlockCreate(PRTSPINLOCK pSpinlock, uint32_t fFlags, const char *pszName)
+{
+    RT_ASSERT_PREEMPTIBLE();
+    AssertReturn(fFlags == RTSPINLOCK_FLAGS_INTERRUPT_SAFE || fFlags == RTSPINLOCK_FLAGS_INTERRUPT_UNSAFE, VERR_INVALID_PARAMETER);
+
+    /*
+     * Allocate.
+     */
+    AssertCompile(sizeof(RTSPINLOCKINTERNAL) > sizeof(void *));
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)RTMemAllocZ(sizeof(*pThis));
+    if (!pThis)
+        return VERR_NO_MEMORY;
+
+    /*
+     * Initialize & return.
+     */
+    pThis->u32Magic  = RTSPINLOCK_MAGIC;
+    pThis->fFlags    = fFlags;
+    pThis->fIntSaved = 0;
+    if (fFlags & RTSPINLOCK_FLAGS_INTERRUPT_SAFE) {
+        mutex_init(&pThis->pSpinLock, MUTEX_DEFAULT, IPL_BIO);
+    } else {
+        mutex_init(&pThis->pSpinLock, MUTEX_DEFAULT, IPL_NONE);
+    }
+
+    *pSpinlock = pThis;
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSpinlockDestroy(RTSPINLOCK Spinlock)
+{
+    /*
+     * Validate input.
+     */
+    RT_ASSERT_INTS_ON();
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
+    if (!pThis)
+        return VERR_INVALID_PARAMETER;
+    AssertMsgReturn(pThis->u32Magic == RTSPINLOCK_MAGIC,
+                    ("Invalid spinlock %p magic=%#x\n", pThis, pThis->u32Magic),
+                    VERR_INVALID_PARAMETER);
+
+    /*
+     * Make the lock invalid and release the memory.
+     */
+    ASMAtomicIncU32(&pThis->u32Magic);
+    mutex_destroy(&pThis->pSpinLock);
+    RTMemFree(pThis);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(void) RTSpinlockAcquire(RTSPINLOCK Spinlock)
+{
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
+    RT_ASSERT_PREEMPT_CPUID_VAR();
+    AssertPtr(pThis);
+    Assert(pThis->u32Magic == RTSPINLOCK_MAGIC);
+
+    if (pThis->fFlags & RTSPINLOCK_FLAGS_INTERRUPT_SAFE) {
+        mutex_spin_enter(&pThis->pSpinLock);
+    } else {
+        mutex_enter(&pThis->pSpinLock);
+    }
+}
+
+
+RTDECL(void) RTSpinlockRelease(RTSPINLOCK Spinlock)
+{
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
+    AssertPtr(pThis);
+    Assert(pThis->u32Magic == RTSPINLOCK_MAGIC);
+
+    if (pThis->fFlags & RTSPINLOCK_FLAGS_INTERRUPT_SAFE) {
+        mutex_spin_exit(&pThis->pSpinLock);
+    } else {
+        mutex_exit(&pThis->pSpinLock);
+    }
+}
diff --git a/src/VBox/Runtime/r0drv/netbsd/the-netbsd-kernel.h b/src/VBox/Runtime/r0drv/netbsd/the-netbsd-kernel.h
new file mode 100644
index 00000000..ce6caf85
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/netbsd/the-netbsd-kernel.h
@@ -0,0 +1,97 @@
+/* $Id: the-netbsd-kernel.h $ */
+/** @file
+ * IPRT - Ring-0 Driver, The NetBSD Kernel Headers.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef IPRT_INCLUDED_SRC_r0drv_netbsd_the_netbsd_kernel_h
+#define IPRT_INCLUDED_SRC_r0drv_netbsd_the_netbsd_kernel_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <iprt/types.h>
+
+/* Deal with conflicts first. */
+#include <sys/param.h>
+#undef PVM
+#include <sys/bus.h>
+#include <sys/types.h>
+#include <sys/errno.h>
+#include <sys/kernel.h>
+#include <sys/uio.h>
+#include <sys/systm.h>
+#include <sys/malloc.h>
+#include <sys/proc.h>
+#include <sys/syslimits.h>
+#include <sys/sleepq.h>
+#include <sys/unistd.h>
+#include <sys/kthread.h>
+#include <sys/lock.h>
+#include <sys/mutex.h>
+#include <sys/sched.h>
+#include <sys/callout.h>
+#include <sys/rwlock.h>
+#include <sys/kmem.h>
+#include <sys/cpu.h>
+#include <sys/vmmeter.h>        /* cnt */
+#include <sys/resourcevar.h>
+#include <uvm/uvm.h>
+#include <uvm/uvm_extern.h>
+#include <uvm/uvm_page.h>
+#include <machine/cpu.h>
+
+/**
+ * Check whether we can use kmem_alloc_prot.
+ */
+#if 0 /** @todo Not available yet. */
+# define USE_KMEM_ALLOC_PROT
+#endif
+
+#endif /* !IPRT_INCLUDED_SRC_r0drv_netbsd_the_netbsd_kernel_h */
diff --git a/src/VBox/Runtime/r0drv/netbsd/thread-r0drv-netbsd.c b/src/VBox/Runtime/r0drv/netbsd/thread-r0drv-netbsd.c
new file mode 100644
index 00000000..f36c91f2
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/netbsd/thread-r0drv-netbsd.c
@@ -0,0 +1,183 @@
+/* $Id: thread-r0drv-netbsd.c $ */
+/** @file
+ * IPRT - Threads (Part 1), Ring-0 Driver, NetBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-netbsd-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/thread.h>
+
+#include <iprt/asm.h>
+#include <iprt/asm-amd64-x86.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/mp.h>
+#include "internal/thread.h"
+
+
+RTDECL(RTNATIVETHREAD) RTThreadNativeSelf(void)
+{
+    return (RTNATIVETHREAD)curlwp;
+}
+
+
+static int rtR0ThreadNbsdSleepCommon(RTMSINTERVAL cMillies)
+{
+    int rc;
+    int cTicks;
+
+    /*
+     * 0 ms sleep -> yield.
+     */
+    if (!cMillies)
+    {
+        RTThreadYield();
+        return VINF_SUCCESS;
+    }
+
+    /*
+     * Translate milliseconds into ticks and go to sleep.
+     */
+    if (cMillies != RT_INDEFINITE_WAIT)
+    {
+        if (hz == 1000)
+            cTicks = cMillies;
+        else if (hz == 100)
+            cTicks = cMillies / 10;
+        else
+        {
+            int64_t cTicks64 = ((uint64_t)cMillies * hz) / 1000;
+            cTicks = (int)cTicks64;
+            if (cTicks != cTicks64)
+                cTicks = INT_MAX;
+        }
+    }
+    else
+        cTicks = 0;     /* requires giant lock! */
+
+    rc = tsleep((void *)RTThreadSleep,
+                PZERO | PCATCH,
+                "iprtsl",           /* max 6 chars */
+                cTicks);
+    switch (rc)
+    {
+        case 0:
+            return VINF_SUCCESS;
+        case EWOULDBLOCK:
+            return VERR_TIMEOUT;
+        case EINTR:
+        case ERESTART:
+            return VERR_INTERRUPTED;
+        default:
+            AssertMsgFailed(("%d\n", rc));
+            return VERR_NO_TRANSLATION;
+    }
+}
+
+
+RTDECL(int) RTThreadSleep(RTMSINTERVAL cMillies)
+{
+    return rtR0ThreadNbsdSleepCommon(cMillies);
+}
+
+
+RTDECL(int) RTThreadSleepNoLog(RTMSINTERVAL cMillies)
+{
+    return rtR0ThreadNbsdSleepCommon(cMillies);
+}
+
+
+RTDECL(bool) RTThreadYield(void)
+{
+    yield();
+    return true;
+}
+
+
+RTDECL(bool) RTThreadPreemptIsEnabled(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD);
+
+    return curlwp->l_dopreempt == 0
+        && ASMIntAreEnabled(); /** @todo is there a native netbsd function/macro for this? */
+}
+
+
+RTDECL(bool) RTThreadPreemptIsPending(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD);
+
+    return curlwp->l_dopreempt;
+}
+
+
+RTDECL(bool) RTThreadPreemptIsPendingTrusty(void)
+{
+    /* yes, RTThreadPreemptIsPending is reliable. */
+    return true;
+}
+
+
+RTDECL(bool) RTThreadPreemptIsPossible(void)
+{
+    /* yes, kernel preemption is possible. */
+    return true;
+}
+
+
+RTDECL(void) RTThreadPreemptDisable(PRTTHREADPREEMPTSTATE pState)
+{
+    AssertPtr(pState);
+
+    curlwp->l_nopreempt++;
+    __insn_barrier();
+}
+
+
+RTDECL(void) RTThreadPreemptRestore(PRTTHREADPREEMPTSTATE pState)
+{
+    AssertPtr(pState);
+    __insn_barrier();
+    if (--curlwp->l_nopreempt != 0)
+        return;
+    __insn_barrier();
+    if (__predict_false(curlwp->l_dopreempt))
+        kpreempt(0);
+    __insn_barrier();
+}
+
+
+RTDECL(bool) RTThreadIsInInterrupt(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD); NOREF(hThread);
+    /** @todo NetBSD: Implement RTThreadIsInInterrupt. Required for guest
+     *        additions! */
+    return !ASMIntAreEnabled();
+}
diff --git a/src/VBox/Runtime/r0drv/netbsd/thread2-r0drv-netbsd.c b/src/VBox/Runtime/r0drv/netbsd/thread2-r0drv-netbsd.c
new file mode 100644
index 00000000..2b5ef142
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/netbsd/thread2-r0drv-netbsd.c
@@ -0,0 +1,157 @@
+/* $Id: thread2-r0drv-netbsd.c $ */
+/** @file
+ * IPRT - Threads (Part 2), Ring-0 Driver, NetBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-netbsd-kernel.h"
+
+#include <iprt/thread.h>
+#include <iprt/errcore.h>
+#include <iprt/assert.h>
+
+#include "internal/thread.h"
+
+
+DECLHIDDEN(int) rtThreadNativeInit(void)
+{
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(RTTHREAD) RTThreadSelf(void)
+{
+    return rtThreadGetByNative(RTThreadNativeSelf());
+}
+
+
+DECLHIDDEN(int) rtThreadNativeSetPriority(PRTTHREADINT pThread, RTTHREADTYPE enmType)
+{
+    int iPriority;
+
+    switch (enmType)
+    {
+        case RTTHREADTYPE_INFREQUENT_POLLER:    iPriority = PZERO + 8;      break;
+        case RTTHREADTYPE_EMULATION:            iPriority = PZERO + 4;      break;
+        case RTTHREADTYPE_DEFAULT:              iPriority = PZERO;          break;
+        case RTTHREADTYPE_MSG_PUMP:             iPriority = PZERO - 4;      break;
+        case RTTHREADTYPE_IO:                   iPriority = PRIBIO;         break;
+        case RTTHREADTYPE_TIMER:                iPriority = PSWP;           break;
+        default:
+            AssertMsgFailed(("enmType=%d\n", enmType));
+            return VERR_INVALID_PARAMETER;
+    }
+
+    lwp_lock(curlwp);
+    lwp_changepri(curlwp, iPriority);
+    lwp_unlock(curlwp);
+
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtThreadNativeAdopt(PRTTHREADINT pThread)
+{
+    NOREF(pThread);
+    /* There is nothing special that needs doing here, but the
+       user really better know what he's cooking. */
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(void) rtThreadNativeWaitKludge(PRTTHREADINT pThread)
+{
+    /** @todo fix RTThreadWait/RTR0Term race on netbsd. */
+    RTThreadSleep(1);
+}
+
+
+DECLHIDDEN(void) rtThreadNativeDestroy(PRTTHREADINT pThread)
+{
+    NOREF(pThread);
+}
+
+
+/**
+ * Native thread main function.
+ *
+ * @param   pvThreadInt     The thread structure.
+ */
+static void rtThreadNativeMain(void *pvThreadInt)
+{
+    const struct lwp *Self = curlwp;
+    PRTTHREADINT pThreadInt = (PRTTHREADINT)pvThreadInt;
+    int rc;
+
+    rc = rtThreadMain(pThreadInt, (RTNATIVETHREAD)Self, &pThreadInt->szName[0]);
+
+    kthread_exit(rc);
+}
+
+
+DECLHIDDEN(int) rtThreadNativeCreate(PRTTHREADINT pThreadInt, PRTNATIVETHREAD pNativeThread)
+{
+    int rc;
+    struct lwp *l;
+
+    rc = kthread_create(PRI_NONE, 0, NULL, rtThreadNativeMain, (void *)pThreadInt, &l, "%s", pThreadInt->szName);
+
+    if (!rc)
+    {
+        *pNativeThread = (RTNATIVETHREAD)l;
+        rc = VINF_SUCCESS;
+    }
+    else
+        rc = RTErrConvertFromErrno(rc);
+    return rc;
+}
diff --git a/src/VBox/Runtime/r0drv/netbsd/time-r0drv-netbsd.c b/src/VBox/Runtime/r0drv/netbsd/time-r0drv-netbsd.c
new file mode 100644
index 00000000..90600ba1
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/netbsd/time-r0drv-netbsd.c
@@ -0,0 +1,95 @@
+/* $Id: time-r0drv-netbsd.c $ */
+/** @file
+ * IPRT - Time, Ring-0 Driver, NetBSD.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-netbsd-kernel.h"
+#define RTTIME_INCL_TIMESPEC
+
+#include <iprt/time.h>
+
+
+RTDECL(uint64_t) RTTimeNanoTS(void)
+{
+    struct timespec tsp;
+    nanotime(&tsp);
+    return tsp.tv_sec * RT_NS_1SEC_64
+         + tsp.tv_nsec;
+}
+
+
+RTDECL(uint64_t) RTTimeMilliTS(void)
+{
+    return RTTimeNanoTS() / RT_NS_1MS;
+}
+
+
+RTDECL(uint64_t) RTTimeSystemNanoTS(void)
+{
+    return RTTimeNanoTS();
+}
+
+
+RTDECL(uint64_t) RTTimeSystemMilliTS(void)
+{
+    return RTTimeMilliTS();
+}
+
+
+RTDECL(PRTTIMESPEC) RTTimeNow(PRTTIMESPEC pTime)
+{
+    struct timespec tsp;
+    nanotime(&tsp);
+    return RTTimeSpecSetTimespec(pTime, &tsp);
+}
diff --git a/src/VBox/Runtime/r0drv/nt/Makefile.kup b/src/VBox/Runtime/r0drv/nt/Makefile.kup
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/Makefile.kup
diff --git a/src/VBox/Runtime/r0drv/nt/RTLogWriteDebugger-r0drv-nt.cpp b/src/VBox/Runtime/r0drv/nt/RTLogWriteDebugger-r0drv-nt.cpp
new file mode 100644
index 00000000..1446dec2
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/RTLogWriteDebugger-r0drv-nt.cpp
@@ -0,0 +1,39 @@
+/* $Id: RTLogWriteDebugger-r0drv-nt.cpp $ */
+/** @file
+ * IPRT - Log To Debugger, Ring-0 Driver, NT.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+#include "the-nt-kernel.h"
+#include <iprt/log.h>
+#include <iprt/assert.h>
+
+
+RTDECL(void) RTLogWriteDebugger(const char *pch, size_t cb)
+{
+    if (pch[cb] != '\0')
+        AssertBreakpoint();
+    DbgPrint("%s", pch);
+    return;
+}
+
diff --git a/src/VBox/Runtime/r0drv/nt/RTTimerGetSystemGranularity-r0drv-nt.cpp b/src/VBox/Runtime/r0drv/nt/RTTimerGetSystemGranularity-r0drv-nt.cpp
new file mode 100644
index 00000000..d2c22e5c
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/RTTimerGetSystemGranularity-r0drv-nt.cpp
@@ -0,0 +1,61 @@
+/* $Id: RTTimerGetSystemGranularity-r0drv-nt.cpp $ */
+/** @file
+ * IPRT - RTTimerGetSystemGranularity, Ring-0 Driver, NT.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-nt-kernel.h"
+
+#include <iprt/timer.h>
+#include <iprt/errcore.h>
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+
+#include "internal-r0drv-nt.h"
+#include "internal/magics.h"
+
+
+RTDECL(uint32_t) RTTimerGetSystemGranularity(void)
+{
+    /*
+     * Get the default/max timer increment value, return it if ExSetTimerResolution
+     * isn't available. According to the sysinternals guys NtQueryTimerResolution
+     * is only available in userland and they find it equally annoying.
+     */
+    ULONG ulTimeInc = KeQueryTimeIncrement();
+    if (!g_pfnrtNtExSetTimerResolution)
+        return ulTimeInc * 100; /* The value is in 100ns, the funny NT unit. */
+
+    /*
+     * Use the value returned by ExSetTimerResolution. Since the kernel is keeping
+     * count of these calls, we have to do two calls that cancel each other out.
+     */
+    g_pfnrtNtExSetTimerResolution(ulTimeInc, TRUE);
+    ULONG ulResolution = g_pfnrtNtExSetTimerResolution(0 /*ignored*/, FALSE);
+    return ulResolution * 100; /* NT -> ns */
+}
+
diff --git a/src/VBox/Runtime/r0drv/nt/alloc-r0drv-nt.cpp b/src/VBox/Runtime/r0drv/nt/alloc-r0drv-nt.cpp
new file mode 100644
index 00000000..dd246c77
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/alloc-r0drv-nt.cpp
@@ -0,0 +1,154 @@
+/* $Id: alloc-r0drv-nt.cpp $ */
+/** @file
+ * IPRT - Memory Allocation, Ring-0 Driver, NT.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-nt-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/mem.h>
+
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+#include "r0drv/alloc-r0drv.h"
+#include "internal-r0drv-nt.h"
+
+
+/**
+ * OS specific allocation function.
+ */
+DECLHIDDEN(int) rtR0MemAllocEx(size_t cb, uint32_t fFlags, PRTMEMHDR *ppHdr)
+{
+    if (!(fFlags & RTMEMHDR_FLAG_ANY_CTX))
+    {
+        PRTMEMHDR pHdr;
+        if (g_pfnrtExAllocatePoolWithTag)
+        {
+            if (!(fFlags & RTMEMHDR_FLAG_EXEC) && g_uRtNtVersion >= RTNT_MAKE_VERSION(8,0))
+                pHdr = (PRTMEMHDR)g_pfnrtExAllocatePoolWithTag(NonPagedPoolNx, cb + sizeof(*pHdr), IPRT_NT_POOL_TAG);
+            else
+                pHdr = (PRTMEMHDR)g_pfnrtExAllocatePoolWithTag(NonPagedPool, cb + sizeof(*pHdr), IPRT_NT_POOL_TAG);
+        }
+        else
+        {
+            fFlags |= RTMEMHDR_FLAG_UNTAGGED;
+            pHdr = (PRTMEMHDR)ExAllocatePool(NonPagedPool, cb + sizeof(*pHdr));
+        }
+        if (pHdr)
+        {
+            pHdr->u32Magic  = RTMEMHDR_MAGIC;
+            pHdr->fFlags    = fFlags;
+            pHdr->cb        = (uint32_t)cb; Assert(pHdr->cb == cb);
+            pHdr->cbReq     = (uint32_t)cb;
+            *ppHdr = pHdr;
+            return VINF_SUCCESS;
+        }
+        return VERR_NO_MEMORY;
+    }
+    return VERR_NOT_SUPPORTED;
+}
+
+
+/**
+ * OS specific free function.
+ */
+DECLHIDDEN(void) rtR0MemFree(PRTMEMHDR pHdr)
+{
+    pHdr->u32Magic = RTMEMHDR_MAGIC_DEAD;
+    if (g_pfnrtExFreePoolWithTag && !(pHdr->fFlags & RTMEMHDR_FLAG_UNTAGGED))
+        g_pfnrtExFreePoolWithTag(pHdr, IPRT_NT_POOL_TAG);
+    else
+        ExFreePool(pHdr);
+}
+
+
+/**
+ * Allocates physical contiguous memory (below 4GB).
+ * The allocation is page aligned and its contents is undefined.
+ *
+ * @returns Pointer to the memory block. This is page aligned.
+ * @param   pPhys   Where to store the physical address.
+ * @param   cb      The allocation size in bytes. This is always
+ *                  rounded up to PAGE_SIZE.
+ */
+RTR0DECL(void *) RTMemContAlloc(PRTCCPHYS pPhys, size_t cb)
+{
+    /*
+     * validate input.
+     */
+    Assert(VALID_PTR(pPhys));
+    Assert(cb > 0);
+
+    /*
+     * Allocate and get physical address.
+     * Make sure the return is page aligned.
+     */
+    PHYSICAL_ADDRESS MaxPhysAddr;
+    MaxPhysAddr.HighPart = 0;
+    MaxPhysAddr.LowPart = 0xffffffff;
+    cb = RT_ALIGN_Z(cb, PAGE_SIZE);
+    void *pv = MmAllocateContiguousMemory(cb, MaxPhysAddr);
+    if (pv)
+    {
+        if (!((uintptr_t)pv & PAGE_OFFSET_MASK))    /* paranoia */
+        {
+            PHYSICAL_ADDRESS PhysAddr = MmGetPhysicalAddress(pv);
+            if (!PhysAddr.HighPart)                 /* paranoia */
+            {
+                *pPhys = (RTCCPHYS)PhysAddr.LowPart;
+                return pv;
+            }
+
+            /* failure */
+            AssertMsgFailed(("MMAllocContiguousMemory returned high address! PhysAddr=%RX64\n", (uint64_t)PhysAddr.QuadPart));
+        }
+        else
+            AssertMsgFailed(("MMAllocContiguousMemory didn't return a page aligned address - %p!\n", pv));
+
+        MmFreeContiguousMemory(pv);
+    }
+
+    return NULL;
+}
+
+
+/**
+ * Frees memory allocated ysing RTMemContAlloc().
+ *
+ * @param   pv      Pointer to return from RTMemContAlloc().
+ * @param   cb      The cb parameter passed to RTMemContAlloc().
+ */
+RTR0DECL(void) RTMemContFree(void *pv, size_t cb)
+{
+    if (pv)
+    {
+        Assert(cb > 0); NOREF(cb);
+        AssertMsg(!((uintptr_t)pv & PAGE_OFFSET_MASK), ("pv=%p\n", pv));
+        MmFreeContiguousMemory(pv);
+    }
+}
+
diff --git a/src/VBox/Runtime/r0drv/nt/alloca-x86-r0drv-nt.asm b/src/VBox/Runtime/r0drv/nt/alloca-x86-r0drv-nt.asm
new file mode 100644
index 00000000..b2137e6b
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/alloca-x86-r0drv-nt.asm
@@ -0,0 +1,59 @@
+; $Id: alloca-x86-r0drv-nt.asm $
+;; @file
+; IPRT - Visual C++ __alloca__probe_16.
+;
+
+;
+; Copyright (C) 2020 Oracle Corporation
+;
+; This file is part of VirtualBox Open Source Edition (OSE), as
+; available from http://www.virtualbox.org. This file is free software;
+; you can redistribute it and/or modify it under the terms of the GNU
+; General Public License (GPL) as published by the Free Software
+; Foundation, in version 2 as it comes in the "COPYING" file of the
+; VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+; hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+;
+; The contents of this file may alternatively be used under the terms
+; of the Common Development and Distribution License Version 1.0
+; (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+; VirtualBox OSE distribution, in which case the provisions of the
+; CDDL are applicable instead of those of the GPL.
+;
+; You may elect to license modified versions of this file under the
+; terms and conditions of either the GPL or the CDDL or both.
+;
+
+;*******************************************************************************
+;* Header Files                                                                *
+;*******************************************************************************
+%include "iprt/asmdefs.mac"
+
+BEGINCODE
+
+;;
+; @returns  esp with eax subtracted and aligned to 16 bytes.
+; @param    eax allocation size.
+;
+BEGINPROC _alloca_probe_16
+        ; Sanitycheck the input.
+%ifdef DEBUG
+        cmp     eax, 0
+        jne     .not_zero
+        int3
+.not_zero:
+        cmp     eax, 4096
+        jbe     .four_kb_or_less
+        int3
+.four_kb_or_less:
+%endif
+
+        ; Don't bother probing the stack as the allocation is supposed to be
+        ; a lot smaller than 4KB.
+        neg     eax
+        lea     eax, [esp + eax + 4]
+        and     eax, 0fffffff0h
+        xchg    eax, esp
+        jmp     [eax]
+ENDPROC _alloca_probe_16
+
diff --git a/src/VBox/Runtime/r0drv/nt/assert-r0drv-nt.cpp b/src/VBox/Runtime/r0drv/nt/assert-r0drv-nt.cpp
new file mode 100644
index 00000000..7cab30c5
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/assert-r0drv-nt.cpp
@@ -0,0 +1,66 @@
+/* $Id: assert-r0drv-nt.cpp $ */
+/** @file
+ * IPRT - Assertion Workers, Ring-0 Drivers, NT.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-nt-kernel.h"
+
+#include <iprt/assert.h>
+#include <iprt/log.h>
+#include <iprt/string.h>
+#include <iprt/stdarg.h>
+
+#include "internal/assert.h"
+
+
+DECLHIDDEN(void) rtR0AssertNativeMsg1(const char *pszExpr, unsigned uLine, const char *pszFile, const char *pszFunction)
+{
+    DbgPrint("\n!!Assertion Failed!!\n"
+             "Expression: %s\n"
+             "Location  : %s(%d) %s\n",
+             pszExpr, pszFile, uLine, pszFunction);
+}
+
+
+DECLHIDDEN(void) rtR0AssertNativeMsg2V(bool fInitial, const char *pszFormat, va_list va)
+{
+    char szMsg[256];
+
+    RTStrPrintfV(szMsg, sizeof(szMsg) - 1, pszFormat, va);
+    szMsg[sizeof(szMsg) - 1] = '\0';
+    DbgPrint("%s", szMsg);
+
+    NOREF(fInitial);
+}
+
+
+RTR0DECL(void) RTR0AssertPanicSystem(void)
+{
+    /** @todo implement RTR0AssertPanicSystem. */
+}
+
diff --git a/src/VBox/Runtime/r0drv/nt/dbgkrnlinfo-r0drv-nt.cpp b/src/VBox/Runtime/r0drv/nt/dbgkrnlinfo-r0drv-nt.cpp
new file mode 100644
index 00000000..ca949154
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/dbgkrnlinfo-r0drv-nt.cpp
@@ -0,0 +1,873 @@
+/* $Id: dbgkrnlinfo-r0drv-nt.cpp $ */
+/** @file
+ * IPRT - Kernel Debug Information, R0 Driver, NT.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define IMAGE_NT_HEADERS   NT_IMAGE_NT_HEADERS
+#define IMAGE_NT_HEADERS32 NT_IMAGE_NT_HEADERS32
+#define IMAGE_NT_HEADERS64 NT_IMAGE_NT_HEADERS64
+#define PIMAGE_NT_HEADERS   NT_PIMAGE_NT_HEADERS
+#define PIMAGE_NT_HEADERS32 NT_PIMAGE_NT_HEADERS32
+#define PIMAGE_NT_HEADERS64 NT_PIMAGE_NT_HEADERS64
+#ifndef IPRT_NT_MAP_TO_ZW
+# define IPRT_NT_MAP_TO_ZW
+#endif
+#include "the-nt-kernel.h"
+#include <iprt/dbg.h>
+
+#include <iprt/err.h>
+#include <iprt/log.h>
+#include <iprt/mem.h>
+#include <iprt/string.h>
+#include <iprt/utf16.h>
+#include "internal-r0drv-nt.h"
+#include "internal/magics.h"
+
+#undef IMAGE_NT_HEADERS
+#undef IMAGE_NT_HEADERS32
+#undef IMAGE_NT_HEADERS64
+#undef PIMAGE_NT_HEADERS
+#undef PIMAGE_NT_HEADERS32
+#undef PIMAGE_NT_HEADERS64
+#include <iprt/formats/pecoff.h>
+#include <iprt/formats/mz.h>
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+/** Private logging macro, will use DbgPrint! */
+#ifdef IN_GUEST
+# define RTR0DBG_NT_ERROR_LOG(a) do { RTLogBackdoorPrintf a; DbgPrint a; } while (0)
+# define RTR0DBG_NT_DEBUG_LOG(a) do { RTLogBackdoorPrintf a; DbgPrint a; } while (0)
+#else
+# define RTR0DBG_NT_ERROR_LOG(a) do { DbgPrint a; } while (0)
+# define RTR0DBG_NT_DEBUG_LOG(a) do { DbgPrint a; } while (0)
+#endif
+#ifndef LOG_ENABLED
+# undef RTR0DBG_NT_DEBUG_LOG
+# define RTR0DBG_NT_DEBUG_LOG(a) do { } while (0)
+#endif
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+#define PIMAGE_NT_HEADERS RT_CONCAT(PIMAGE_NT_HEADERS, ARCH_BITS)
+
+/**
+ * Information we cache for a kernel module.
+ */
+typedef struct RTDBGNTKRNLMODINFO
+{
+    /** The module name.   */
+    char                    szName[32];
+
+    /** The image base. */
+    uint8_t const          *pbImageBase;
+    /** The NT headers. */
+    PIMAGE_NT_HEADERS       pNtHdrs;
+    /** Set if this module parsed okay and all fields are valid. */
+    bool                    fOkay;
+    /** The NT header offset/RVA. */
+    uint32_t                offNtHdrs;
+    /** The end of the section headers. */
+    uint32_t                offEndSectHdrs;
+    /** The end of the image. */
+    uint32_t                cbImage;
+    /** Offset of the export directory. */
+    uint32_t                offExportDir;
+    /** Size of the export directory. */
+    uint32_t                cbExportDir;
+
+    /** Exported functions and data by ordinal (RVAs). */
+    uint32_t const         *paoffExports;
+    /** The number of exports. */
+    uint32_t                cExports;
+    /** The number of exported names. */
+    uint32_t                cNamedExports;
+    /** Pointer to the array of exported names (RVAs to strings). */
+    uint32_t const         *paoffNamedExports;
+    /** Array parallel to paoffNamedExports with the corresponding ordinals
+     *  (indexes into paoffExports). */
+    uint16_t const         *pau16NameOrdinals;
+} RTDBGNTKRNLMODINFO;
+/** Pointer to kernel module info. */
+typedef RTDBGNTKRNLMODINFO *PRTDBGNTKRNLMODINFO;
+/** Pointer to const kernel module info. */
+typedef RTDBGNTKRNLMODINFO const *PCRTDBGNTKRNLMODINFO;
+
+
+/**
+ * NT kernel info instance.
+ */
+typedef struct RTDBGKRNLINFOINT
+{
+    /** Magic value (RTDBGKRNLINFO_MAGIC). */
+    uint32_t            u32Magic;
+    /** Reference counter.  */
+    uint32_t volatile   cRefs;
+    /** Number of additional modules in the cache. */
+    uint32_t            cModules;
+    /** Additional modules. */
+    RTDBGNTKRNLMODINFO  aModules[3];
+} RTDBGKRNLINFOINT;
+
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/** Pointer to MmGetSystemRoutineAddress.
+ * @note Added in NT v5.0. */
+static decltype(MmGetSystemRoutineAddress) *g_pfnMmGetSystemRoutineAddress = NULL;
+/** Info about the ntoskrnl.exe mapping. */
+static RTDBGNTKRNLMODINFO   g_NtOsKrnlInfo = { "ntoskrnl.exe", NULL, NULL, false, 0, 0, 0, 0, 0, NULL, 0, 0, NULL, NULL };
+/** Info about the hal.dll mapping. */
+static RTDBGNTKRNLMODINFO   g_HalInfo      = { "hal.dll",      NULL, NULL, false, 0, 0, 0, 0, 0, NULL, 0, 0, NULL, NULL };
+
+
+
+/**
+ * Looks up an symbol int the export table.
+ *
+ * @returns VINF_SUCCESS or VERR_SYMBOL_NOT_FOUND.
+ * @param   pModInfo            The module info.
+ * @param   pszSymbol           The symbol to find.
+ * @param   cForwarders         Forwarder nesting depth.
+ * @param   ppvSymbol           Where to put the symbol address.
+ *
+ * @note    Support library has similar code for in the importless area.
+ */
+static int rtR0DbgKrnlInfoLookupSymbol(PCRTDBGNTKRNLMODINFO pModInfo, const char *pszSymbol, unsigned cForwarders,
+                                       void **ppvSymbol)
+{
+    if (pModInfo->fOkay)
+    {
+        /*
+         * Binary search.
+         */
+        __try
+        {
+            uint32_t iStart = 0;
+            uint32_t iEnd   = pModInfo->cNamedExports;
+            while (iStart < iEnd)
+            {
+                uint32_t iCur        = iStart + (iEnd - iStart) / 2;
+                uint32_t offExpName  = pModInfo->paoffNamedExports[iCur];
+                if (offExpName >= pModInfo->offEndSectHdrs && offExpName < pModInfo->cbImage)
+                { /* likely */ }
+                else
+                {
+                    RTR0DBG_NT_ERROR_LOG(("rtR0DbgKrnlInfoLookupSymbol: %s: Bad export name entry: %#x (iCur=%#x)\n",
+                                          pModInfo->szName, offExpName, iCur));
+                    break;
+                }
+
+                const char *pszExpName = (const char *)&pModInfo->pbImageBase[offExpName];
+                int iDiff = strcmp(pszExpName, pszSymbol);
+                if (iDiff > 0)      /* pszExpName > pszSymbol: search chunck before i */
+                    iEnd = iCur;
+                else if (iDiff < 0) /* pszExpName < pszSymbol: search chunk after i */
+                    iStart = iCur + 1;
+                else                /* pszExpName == pszSymbol */
+                {
+                    uint16_t iExpOrdinal = pModInfo->pau16NameOrdinals[iCur];
+                    if (iExpOrdinal < pModInfo->cExports)
+                    {
+                        uint32_t offExport = pModInfo->paoffExports[iExpOrdinal];
+                        if (offExport - pModInfo->offExportDir >= pModInfo->cbExportDir)
+                        {
+                            *ppvSymbol = (void *)&pModInfo->pbImageBase[offExport];
+                            return VINF_SUCCESS;
+                        }
+
+                        /*
+                         * Deal with forwarders to NT and HAL.  No ordinals.
+                         */
+                        const char *pszForwarder = (const char *)&pModInfo->pbImageBase[offExport];
+                        uint32_t    cbMax        = pModInfo->cbImage - offExpName;
+                        size_t      cchForwarder = RTStrNLen(pszForwarder, cbMax);
+                        if (cchForwarder < cbMax)
+                        {
+                            if (   cchForwarder > 9
+                                && pModInfo != &g_NtOsKrnlInfo
+                                && g_NtOsKrnlInfo.pbImageBase != NULL
+                                && cForwarders < 2
+                                && (pszForwarder[0] == 'n' || pszForwarder[0] == 'N')
+                                && (pszForwarder[1] == 't' || pszForwarder[1] == 'T')
+                                && (pszForwarder[2] == 'o' || pszForwarder[2] == 'O')
+                                && (pszForwarder[3] == 's' || pszForwarder[3] == 'S')
+                                && (pszForwarder[4] == 'k' || pszForwarder[4] == 'K')
+                                && (pszForwarder[5] == 'r' || pszForwarder[5] == 'R')
+                                && (pszForwarder[6] == 'n' || pszForwarder[6] == 'N')
+                                && (pszForwarder[7] == 'l' || pszForwarder[7] == 'L')
+                                &&  pszForwarder[8] == '.')
+                                return rtR0DbgKrnlInfoLookupSymbol(&g_NtOsKrnlInfo, pszForwarder + 9, cForwarders + 1, ppvSymbol);
+
+                            if (   cchForwarder > 4
+                                && pModInfo != &g_HalInfo
+                                && g_HalInfo.pbImageBase != NULL
+                                && cForwarders < 2
+                                && (pszForwarder[0] == 'h' || pszForwarder[0] == 'H')
+                                && (pszForwarder[1] == 'a' || pszForwarder[1] == 'A')
+                                && (pszForwarder[2] == 'l' || pszForwarder[2] == 'L')
+                                &&  pszForwarder[3] == '.')
+                                return rtR0DbgKrnlInfoLookupSymbol(&g_HalInfo, pszForwarder + 4, cForwarders + 1, ppvSymbol);
+                        }
+
+                        RTR0DBG_NT_ERROR_LOG(("rtR0DbgKrnlInfoLookupSymbol: %s: Forwarded symbol '%s': offExport=%#x (dir %#x LB %#x)\n",
+                                              pModInfo->szName, pszSymbol, offExport, pModInfo->offExportDir, pModInfo->cbExportDir));
+                    }
+                    else
+                        RTR0DBG_NT_ERROR_LOG(("rtR0DbgKrnlInfoLookupSymbol: %s: Name ordinal for '%s' is out of bounds: %#x (max %#x)\n",
+                                              pModInfo->szName, iExpOrdinal, pModInfo->cExports));
+                    break;
+                }
+            }
+        }
+        __except(EXCEPTION_EXECUTE_HANDLER)
+        {
+            RTR0DBG_NT_ERROR_LOG(("rtR0DbgKrnlInfoLookupSymbol: Exception searching '%s' for '%s'...\n",
+                                  pModInfo->szName, pszSymbol));
+        }
+    }
+
+    *ppvSymbol = NULL;
+    return VERR_SYMBOL_NOT_FOUND;
+}
+
+
+/**
+ * Parses (PE) module headers and fills in the coresponding module info struct.
+ *
+ * @returns true on if success, false if not.
+ * @param   pModInfo            The module info structure to fill in with parsed
+ *                              data.  The szName and fOkay are set by the
+ *                              caller, this function does the rest.
+ * @param   pbMapping           The image mapping address
+ * @param   cbMapping           The image mapping size.
+ *
+ * @note    Support library has similar code for in the importless area.
+ */
+static bool rtR0DbgKrnlNtParseModule(PRTDBGNTKRNLMODINFO pModInfo, uint8_t const *pbMapping, size_t cbMapping)
+{
+#define MODERR_RETURN(a_LogMsg, ...) \
+        do { RTR0DBG_NT_ERROR_LOG(("rtR0DbgKrnlNtParseModule: " a_LogMsg, __VA_ARGS__)); return false; } while (0)
+
+    pModInfo->pbImageBase = pbMapping;
+
+    /*
+     * Locate the PE header, do some basic validations.
+     */
+    IMAGE_DOS_HEADER const *pMzHdr = (IMAGE_DOS_HEADER const *)pbMapping;
+    uint32_t                offNtHdrs = 0;
+    PIMAGE_NT_HEADERS       pNtHdrs;
+    if (pMzHdr->e_magic == IMAGE_DOS_SIGNATURE)
+    {
+        offNtHdrs = pMzHdr->e_lfanew;
+        if (offNtHdrs > _2K)
+            MODERR_RETURN("%s: e_lfanew=%#x, expected a lower value\n", pModInfo->szName, offNtHdrs);
+    }
+    pModInfo->pNtHdrs = pNtHdrs = (PIMAGE_NT_HEADERS)&pbMapping[offNtHdrs];
+
+    if (pNtHdrs->Signature != IMAGE_NT_SIGNATURE)
+        MODERR_RETURN("%s: Invalid PE signature: %#x", pModInfo->szName, pNtHdrs->Signature);
+    if (pNtHdrs->FileHeader.SizeOfOptionalHeader != sizeof(pNtHdrs->OptionalHeader))
+        MODERR_RETURN("%s: Unexpected optional header size: %#x\n", pModInfo->szName, pNtHdrs->FileHeader.SizeOfOptionalHeader);
+    if (pNtHdrs->OptionalHeader.Magic != RT_CONCAT3(IMAGE_NT_OPTIONAL_HDR,ARCH_BITS,_MAGIC))
+        MODERR_RETURN("%s: Unexpected optional header magic: %#x\n", pModInfo->szName, pNtHdrs->OptionalHeader.Magic);
+    if (pNtHdrs->OptionalHeader.NumberOfRvaAndSizes != IMAGE_NUMBEROF_DIRECTORY_ENTRIES)
+        MODERR_RETURN("%s: Unexpected number of RVA and sizes: %#x\n", pModInfo->szName, pNtHdrs->OptionalHeader.NumberOfRvaAndSizes);
+
+    pModInfo->offNtHdrs      = offNtHdrs;
+    pModInfo->offEndSectHdrs = offNtHdrs
+                             + sizeof(*pNtHdrs)
+                             + pNtHdrs->FileHeader.NumberOfSections * sizeof(IMAGE_SECTION_HEADER);
+    pModInfo->cbImage        = pNtHdrs->OptionalHeader.SizeOfImage;
+    if (pModInfo->cbImage > cbMapping)
+        MODERR_RETURN("%s: The image size %#x is larger than the mapping: %#x\n",
+                      pModInfo->szName, pModInfo->cbImage, cbMapping);
+
+    /*
+     * Find the export directory.
+     */
+    IMAGE_DATA_DIRECTORY ExpDir = pNtHdrs->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT];
+    if (   ExpDir.Size < sizeof(IMAGE_EXPORT_DIRECTORY)
+        || ExpDir.VirtualAddress < pModInfo->offEndSectHdrs
+        || ExpDir.VirtualAddress >= pModInfo->cbImage
+        || ExpDir.VirtualAddress + ExpDir.Size > pModInfo->cbImage)
+        MODERR_RETURN("%s: Missing or invalid export directory: %#lx LB %#x\n", pModInfo->szName, ExpDir.VirtualAddress, ExpDir.Size);
+    pModInfo->offExportDir = ExpDir.VirtualAddress;
+    pModInfo->cbExportDir  = ExpDir.Size;
+
+    IMAGE_EXPORT_DIRECTORY const *pExpDir = (IMAGE_EXPORT_DIRECTORY const *)&pbMapping[ExpDir.VirtualAddress];
+
+    if (   pExpDir->NumberOfFunctions >= _1M
+        || pExpDir->NumberOfFunctions <  1
+        || pExpDir->NumberOfNames     >= _1M
+        || pExpDir->NumberOfNames     <  1)
+        MODERR_RETURN("%s: NumberOfNames or/and NumberOfFunctions are outside the expected range: nof=%#x non=%#x\n",
+                      pModInfo->szName, pExpDir->NumberOfFunctions, pExpDir->NumberOfNames);
+    pModInfo->cNamedExports = pExpDir->NumberOfNames;
+    pModInfo->cExports      = RT_MAX(pExpDir->NumberOfNames,  pExpDir->NumberOfFunctions);
+
+    if (   pExpDir->AddressOfFunctions < pModInfo->offEndSectHdrs
+        || pExpDir->AddressOfFunctions >= pModInfo->cbImage
+        || pExpDir->AddressOfFunctions + pModInfo->cExports * sizeof(uint32_t) > pModInfo->cbImage)
+           MODERR_RETURN("%s: Bad AddressOfFunctions: %#x\n", pModInfo->szName, pExpDir->AddressOfFunctions);
+    pModInfo->paoffExports = (uint32_t const *)&pbMapping[pExpDir->AddressOfFunctions];
+
+    if (   pExpDir->AddressOfNames < pModInfo->offEndSectHdrs
+        || pExpDir->AddressOfNames >= pModInfo->cbImage
+        || pExpDir->AddressOfNames + pExpDir->NumberOfNames * sizeof(uint32_t) > pModInfo->cbImage)
+           MODERR_RETURN("%s: Bad AddressOfNames: %#x\n", pModInfo->szName, pExpDir->AddressOfNames);
+    pModInfo->paoffNamedExports = (uint32_t const *)&pbMapping[pExpDir->AddressOfNames];
+
+    if (   pExpDir->AddressOfNameOrdinals < pModInfo->offEndSectHdrs
+        || pExpDir->AddressOfNameOrdinals >= pModInfo->cbImage
+        || pExpDir->AddressOfNameOrdinals + pExpDir->NumberOfNames * sizeof(uint32_t) > pModInfo->cbImage)
+           MODERR_RETURN("%s: Bad AddressOfNameOrdinals: %#x\n", pModInfo->szName, pExpDir->AddressOfNameOrdinals);
+    pModInfo->pau16NameOrdinals = (uint16_t const *)&pbMapping[pExpDir->AddressOfNameOrdinals];
+
+    /*
+     * Success.
+     */
+    return true;
+#undef MODERR_RETURN
+}
+
+
+/**
+ * Searches the given module information from the kernel for the NT kernel module, the
+ * HAL module, and optionally one more module.
+ *
+ * If the NT kernel or HAL modules have already been found, they'll be skipped.
+ *
+ * @returns IPRT status code.
+ * @retval  VERR_LDR_GENERAL_FAILURE if we failed to parse the NT kernel or HAL.
+ * @retval  VERR_BAD_EXE_FORMAT if we failed to parse @a pModInfo.
+ * @retval  VERR_MODULE_NOT_FOUND if @a pModInfo wasn't found.
+ *
+ * @param   pInfo               Pointer to the module information.
+ * @param   cModules            Number of valid module entries in the module information pointer.
+ * @param   pModInfo            Custom module to search for.  Optional.
+ */
+static int rtR0DbgKrnlNtSearchForModuleWorker(PRTL_PROCESS_MODULES pInfo, uint32_t cModules, PRTDBGNTKRNLMODINFO pModInfo)
+{
+    AssertPtrReturn(pInfo, VERR_INVALID_PARAMETER);
+    AssertReturn(cModules >= 2, VERR_INVALID_PARAMETER);
+
+    /*
+     * Search the info.  The information is ordered with the kernel bits first,
+     * we expect aleast two modules to be returned to us (kernel + hal)!
+     */
+    int rc = VINF_SUCCESS;
+#if ARCH_BITS == 32
+    uintptr_t const uMinKernelAddr = _2G; /** @todo resolve MmSystemRangeStart */
+#else
+    uintptr_t const uMinKernelAddr = (uintptr_t)MM_SYSTEM_RANGE_START;
+#endif
+
+    for (uint32_t iModule = 0; iModule < cModules; iModule++)
+        RTR0DBG_NT_DEBUG_LOG(("rtR0DbgKrnlNtInit: [%u]= %p LB %#x %s\n", iModule, pInfo->Modules[iModule].ImageBase,
+                              pInfo->Modules[iModule].ImageSize, pInfo->Modules[iModule].FullPathName));
+
+    /*
+     * First time around we serch for the NT kernel and HAL.  We'll look for NT
+     * kerneland HAL in the first 16 entries, and if not found, use the first
+     * and second entry respectively.
+     */
+    if (   !g_NtOsKrnlInfo.pbImageBase
+        && !g_HalInfo.pbImageBase)
+    {
+        /* Find them. */
+        RTR0DBG_NT_DEBUG_LOG(("rtR0DbgKrnlNtInit: Looking for kernel and hal...\n"));
+        uint32_t const cMaxModules = RT_MIN(cModules, 16);
+        uint32_t       idxNtOsKrnl = UINT32_MAX;
+        uint32_t       idxHal      = UINT32_MAX;
+        for (uint32_t iModule = 0; iModule < cMaxModules; iModule++)
+        {
+            RTL_PROCESS_MODULE_INFORMATION const * const pModule = &pInfo->Modules[iModule];
+            if (   (uintptr_t)pModule->ImageBase >= uMinKernelAddr
+                && (uintptr_t)pModule->ImageSize >= _4K)
+            {
+                const char *pszName = (const char *)&pModule->FullPathName[pModule->OffsetToFileName];
+                if (   idxNtOsKrnl == UINT32_MAX
+                    && RTStrICmpAscii(pszName, g_NtOsKrnlInfo.szName) == 0)
+                {
+                    idxNtOsKrnl = iModule;
+                    if (idxHal != UINT32_MAX)
+                        break;
+                }
+                else if (   idxHal == UINT32_MAX
+                         && RTStrICmpAscii(pszName, g_HalInfo.szName) == 0)
+                {
+                    idxHal = iModule;
+                    if (idxHal != UINT32_MAX)
+                        break;
+                }
+            }
+        }
+        RTR0DBG_NT_DEBUG_LOG(("rtR0DbgKrnlNtInit: idxNtOsKrnl=%#x idxHal=%#x\n", idxNtOsKrnl, idxHal));
+        if (idxNtOsKrnl == UINT32_MAX)
+        {
+            idxNtOsKrnl = 0;
+            RTR0DBG_NT_ERROR_LOG(("rtR0DbgKrnlNtInit: 'ntoskrnl.exe' not found, picking '%s' instead\n",
+                                  pInfo->Modules[idxNtOsKrnl].FullPathName));
+        }
+        if (idxHal == UINT32_MAX)
+        {
+            idxHal = 1;
+            RTR0DBG_NT_ERROR_LOG(("rtR0DbgKrnlNtInit: 'hal.dll' not found, picking '%s' instead\n",
+                                  pInfo->Modules[idxHal].FullPathName));
+        }
+
+        /* Parse them. */
+        //RTR0DBG_NT_DEBUG_LOG(("rtR0DbgKrnlNtInit: Parsing NT kernel...\n"));
+        __try
+        {
+            g_NtOsKrnlInfo.fOkay = rtR0DbgKrnlNtParseModule(&g_NtOsKrnlInfo,
+                                                            (uint8_t const *)pInfo->Modules[idxNtOsKrnl].ImageBase,
+                                                            pInfo->Modules[idxNtOsKrnl].ImageSize);
+        }
+        __except(EXCEPTION_EXECUTE_HANDLER)
+        {
+            g_NtOsKrnlInfo.fOkay = false;
+            RTR0DBG_NT_ERROR_LOG(("rtR0DbgKrnlNtInit: Exception in rtR0DbgKrnlNtParseModule parsing ntoskrnl.exe...\n"));
+        }
+
+        //RTR0DBG_NT_DEBUG_LOG(("rtR0DbgKrnlNtInit: Parsing HAL...\n"));
+        __try
+        {
+            g_HalInfo.fOkay = rtR0DbgKrnlNtParseModule(&g_HalInfo, (uint8_t const *)pInfo->Modules[idxHal].ImageBase,
+                                                       pInfo->Modules[idxHal].ImageSize);
+        }
+        __except(EXCEPTION_EXECUTE_HANDLER)
+        {
+            g_HalInfo.fOkay = false;
+            RTR0DBG_NT_ERROR_LOG(("rtR0DbgKrnlNtInit: Exception in rtR0DbgKrnlNtParseModule parsing hal.dll...\n"));
+        }
+        if (!g_NtOsKrnlInfo.fOkay || !g_HalInfo.fOkay)
+            rc = VERR_LDR_GENERAL_FAILURE;
+
+        /*
+         * Resolve symbols we may need in the NT kernel (provided it parsed successfully)
+         */
+        if (g_NtOsKrnlInfo.fOkay)
+        {
+            if (!g_pfnMmGetSystemRoutineAddress)
+            {
+                //RTR0DBG_NT_DEBUG_LOG(("rtR0DbgKrnlNtInit: Looking up 'MmGetSystemRoutineAddress'...\n"));
+                rtR0DbgKrnlInfoLookupSymbol(&g_NtOsKrnlInfo, "MmGetSystemRoutineAddress", 0,
+                                            (void **)&g_pfnMmGetSystemRoutineAddress);
+            }
+        }
+    }
+
+    /*
+     * If we're still good, search for the given module (optional).
+     */
+    if (RT_SUCCESS(rc) && pModInfo)
+    {
+        RTR0DBG_NT_DEBUG_LOG(("rtR0DbgKrnlNtInit: Locating module '%s'...\n", pModInfo->szName));
+        rc = VERR_MODULE_NOT_FOUND;
+        for (uint32_t iModule = 0; iModule < cModules; iModule++)
+        {
+            RTL_PROCESS_MODULE_INFORMATION const * const pModule = &pInfo->Modules[iModule];
+            if (   (uintptr_t)pModule->ImageBase >= uMinKernelAddr
+                && (uintptr_t)pModule->ImageSize >= _4K)
+            {
+                const char *pszName = (const char *)&pModule->FullPathName[pModule->OffsetToFileName];
+                if (   pModInfo->pbImageBase == NULL
+                    && RTStrICmpAscii(pszName, pModInfo->szName) == 0)
+                {
+                    /*
+                     * Found the module, try parse it.
+                     */
+                    __try
+                    {
+                        pModInfo->fOkay = rtR0DbgKrnlNtParseModule(pModInfo, (uint8_t const *)pModule->ImageBase,
+                                                                   pModule->ImageSize);
+                        rc = VINF_SUCCESS;
+                    }
+                    __except(EXCEPTION_EXECUTE_HANDLER)
+                    {
+                        pModInfo->fOkay = false;
+                        rc = VERR_BAD_EXE_FORMAT;
+                    }
+                    break;
+                }
+            }
+        }
+    }
+
+    return rc;
+}
+
+
+/**
+ * Queries the given maximum amount of modules and returns a pointer to the
+ * allocation holding the modules.
+ *
+ * @returns IPRT status code.
+ * @param   ppInfo              Where to store the pointer to the module information structure on success.
+ *                              Free with RTMemFree() when done.
+ * @param   cModulesMax         Maximum number of modules to return.
+ * @param   pcModules           Where to store the amount of modules returned upon success,
+ *                              can be lower than the requested maximum.
+ */
+static int rtR0DbgKrnlNtQueryModules(PRTL_PROCESS_MODULES *ppInfo, uint32_t cModulesMax, uint32_t *pcModules)
+{
+    *ppInfo = NULL;
+    *pcModules = 0;
+
+    ULONG                   cbInfo   = RT_UOFFSETOF_DYN(RTL_PROCESS_MODULES, Modules[cModulesMax]);
+    PRTL_PROCESS_MODULES    pInfo    = (PRTL_PROCESS_MODULES)RTMemAllocZ(cbInfo);
+    if (!pInfo)
+    {
+        cModulesMax = cModulesMax / 4;
+        cbInfo      = RT_UOFFSETOF_DYN(RTL_PROCESS_MODULES, Modules[cModulesMax]);
+        pInfo       = (PRTL_PROCESS_MODULES)RTMemAllocZ(cbInfo);
+        if (!pInfo)
+        {
+            RTR0DBG_NT_ERROR_LOG(("rtR0DbgKrnlNtQueryModules: Out of memory!\n"));
+            return VERR_NO_MEMORY;
+        }
+    }
+
+    int      rc;
+    ULONG    cbActual = 0;
+    NTSTATUS rcNt = ZwQuerySystemInformation(SystemModuleInformation, pInfo, cbInfo, &cbActual);
+    RTR0DBG_NT_DEBUG_LOG(("rtR0DbgKrnlNtQueryModules: ZwQuerySystemInformation returned %#x and NumberOfModules=%#x\n",
+                          rcNt, pInfo->NumberOfModules));
+    if (   NT_SUCCESS(rcNt)
+        || rcNt == STATUS_INFO_LENGTH_MISMATCH)
+    {
+        *ppInfo    = pInfo;
+        *pcModules = RT_MIN(cModulesMax, pInfo->NumberOfModules);
+        rc = VINF_SUCCESS;
+    }
+    else
+    {
+        RTMemFree(pInfo);
+        RTR0DBG_NT_ERROR_LOG(("rtR0DbgKrnlNtQueryModules: ZwQuerySystemInformation failed: %#x\n", rcNt));
+        rc = RTErrConvertFromNtStatus(rcNt);
+    }
+
+    return rc;
+}
+
+
+/**
+ * Searches the module information from the kernel for the NT kernel module, the
+ * HAL module, and optionally one more module.
+ *
+ * If the NT kernel or HAL modules have already been found, they'll be skipped.
+ *
+ * @returns IPRT status code.
+ * @retval  VERR_LDR_GENERAL_FAILURE if we failed to parse the NT kernel or HAL.
+ * @retval  VERR_BAD_EXE_FORMAT if we failed to parse @a pModInfo.
+ * @retval  VERR_MODULE_NOT_FOUND if @a pModInfo wasn't found.
+ * @retval  VERR_BUFFER_UNDERFLOW if less that two modules was returned by the
+ *          system.
+ *
+ * @param   pModInfo            Custom module to search for.  Optional.
+ */
+static int rtR0DbgKrnlNtInit(PRTDBGNTKRNLMODINFO pModInfo)
+{
+    RTR0DBG_NT_DEBUG_LOG(("rtR0DbgKrnlNtInit: pModInfo=%p\n", pModInfo));
+
+#ifndef IPRT_TARGET_NT4
+    /*
+     * Must manually initialize g_pfnMmGetSystemRoutineAddress, otherwise compiler
+     * generates its own dynamic init code that might not necessarily be called.
+     */
+    g_pfnMmGetSystemRoutineAddress = MmGetSystemRoutineAddress;
+#endif
+
+    /*
+     * Allocate a reasonably large buffer and get the information we need.  We don't
+     * need everything since the result starts off with the kernel bits in load order.
+     *
+     * Note! ZwQuerySystemInformation requires NT4.  For 3.51 we could possibly emit
+     *       the syscall ourselves, if we cared.
+     */
+    uint32_t             cModules = 0;
+    PRTL_PROCESS_MODULES pInfo    = NULL;
+    int rc = rtR0DbgKrnlNtQueryModules(&pInfo, pModInfo ? 110 /*32KB*/ : 27 /*8KB*/, &cModules);
+    if (RT_SUCCESS(rc))
+    {
+        if (cModules >= 2)
+        {
+            rc = rtR0DbgKrnlNtSearchForModuleWorker(pInfo, cModules, pModInfo);
+            if (   rc == VERR_MODULE_NOT_FOUND
+                && pInfo->NumberOfModules > cModules
+                && pModInfo)
+            {
+                /* Module not found in the first round, reallocate array to maximum size and rerun. */
+                cModules = pInfo->NumberOfModules;
+
+                RTMemFree(pInfo);
+                pInfo = NULL;
+
+                rc = rtR0DbgKrnlNtQueryModules(&pInfo, cModules, &cModules);
+                if (RT_SUCCESS(rc))
+                {
+                    rc = rtR0DbgKrnlNtSearchForModuleWorker(pInfo, cModules, pModInfo);
+                    RTMemFree(pInfo);
+                }
+            }
+        }
+        else
+        {
+            RTMemFree(pInfo);
+            RTR0DBG_NT_ERROR_LOG(("rtR0DbgKrnlNtInit: Error! Only %u module(s) returned!\n", cModules));
+            rc = VERR_BUFFER_UNDERFLOW;
+        }
+    }
+
+    RTR0DBG_NT_DEBUG_LOG(("rtR0DbgKrnlNtInit: returns %d\n", rc));
+    return rc;
+}
+
+
+
+RTR0DECL(int) RTR0DbgKrnlInfoOpen(PRTDBGKRNLINFO phKrnlInfo, uint32_t fFlags)
+{
+    AssertReturn(!fFlags, VERR_INVALID_FLAGS);
+
+    RTDBGKRNLINFOINT *pThis = (RTDBGKRNLINFOINT *)RTMemAllocZ(sizeof(*pThis));
+    if (pThis)
+    {
+        pThis->u32Magic = RTDBGKRNLINFO_MAGIC;
+        pThis->cRefs    = 1;
+        *phKrnlInfo = pThis;
+        return VINF_SUCCESS;
+    }
+    return VERR_NO_MEMORY;
+}
+
+
+RTR0DECL(uint32_t) RTR0DbgKrnlInfoRetain(RTDBGKRNLINFO hKrnlInfo)
+{
+    RTDBGKRNLINFOINT *pThis = hKrnlInfo;
+    AssertPtrReturn(pThis, UINT32_MAX);
+    AssertMsgReturn(pThis->u32Magic == RTDBGKRNLINFO_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), UINT32_MAX);
+
+    uint32_t cRefs = ASMAtomicIncU32(&pThis->cRefs);
+    Assert(cRefs && cRefs < 100000);
+    return cRefs;
+}
+
+
+static void rtR0DbgKrnlNtDtor(RTDBGKRNLINFOINT *pThis)
+{
+    pThis->u32Magic = ~RTDBGKRNLINFO_MAGIC;
+    RTMemFree(pThis);
+}
+
+
+RTR0DECL(uint32_t) RTR0DbgKrnlInfoRelease(RTDBGKRNLINFO hKrnlInfo)
+{
+    RTDBGKRNLINFOINT *pThis = hKrnlInfo;
+    if (pThis == NIL_RTDBGKRNLINFO)
+        return 0;
+    AssertPtrReturn(pThis, UINT32_MAX);
+    AssertMsgReturn(pThis->u32Magic == RTDBGKRNLINFO_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), UINT32_MAX);
+
+    uint32_t cRefs = ASMAtomicDecU32(&pThis->cRefs);
+    if (cRefs == 0)
+        rtR0DbgKrnlNtDtor(pThis);
+    return cRefs;
+}
+
+
+RTR0DECL(int) RTR0DbgKrnlInfoQueryMember(RTDBGKRNLINFO hKrnlInfo, const char *pszModule, const char *pszStructure,
+                                         const char *pszMember, size_t *poffMember)
+{
+    RTDBGKRNLINFOINT *pThis = hKrnlInfo;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTDBGKRNLINFO_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+    AssertPtrReturn(pszMember, VERR_INVALID_POINTER);
+    AssertPtrNullReturn(pszModule, VERR_INVALID_POINTER);
+    AssertPtrReturn(pszStructure, VERR_INVALID_POINTER);
+    AssertPtrReturn(poffMember, VERR_INVALID_POINTER);
+    return VERR_NOT_FOUND;
+}
+
+
+RTR0DECL(int) RTR0DbgKrnlInfoQuerySymbol(RTDBGKRNLINFO hKrnlInfo, const char *pszModule, const char *pszSymbol, void **ppvSymbol)
+{
+    RTDBGKRNLINFOINT *pThis = hKrnlInfo;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTDBGKRNLINFO_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+    AssertPtrReturn(pszSymbol, VERR_INVALID_PARAMETER);
+    AssertPtrNullReturn(ppvSymbol, VERR_INVALID_PARAMETER);
+
+    RTR0DBG_NT_DEBUG_LOG(("RTR0DbgKrnlInfoQuerySymbol: pszModule=%s pszSymbol=%s\n", pszModule ? pszModule : "<null>", pszSymbol));
+
+    void  *pvTmpSymbol = NULL;
+    if (!ppvSymbol)
+        ppvSymbol = &pvTmpSymbol;
+
+    int rc;
+    if (!pszModule)
+    {
+        /*
+         * Search both ntoskrnl and hal, may use MmGetSystemRoutineAddress as fallback.
+         * Note! MmGetSystemRoutineAddress was buggy before XP SP2 according to Geoff Chappell.
+         */
+        if (g_NtOsKrnlInfo.pbImageBase)
+            rc = VINF_SUCCESS;
+        else
+            rc = rtR0DbgKrnlNtInit(NULL);
+        if (RT_SUCCESS(rc))
+        {
+            Assert(g_NtOsKrnlInfo.fOkay);
+            Assert(g_HalInfo.fOkay);
+            //RTR0DBG_NT_DEBUG_LOG(("RTR0DbgKrnlInfoQuerySymbol: Calling RTR0DbgKrnlInfoQuerySymbol on NT kernel...\n"));
+            rc = rtR0DbgKrnlInfoLookupSymbol(&g_NtOsKrnlInfo, pszSymbol, 0, ppvSymbol);
+            if (RT_FAILURE(rc))
+            {
+                //RTR0DBG_NT_DEBUG_LOG(("RTR0DbgKrnlInfoQuerySymbol: Calling RTR0DbgKrnlInfoQuerySymbol on HAL kernel...\n"));
+                rc = rtR0DbgKrnlInfoLookupSymbol(&g_HalInfo, pszSymbol, 0, ppvSymbol);
+            }
+            RTR0DBG_NT_DEBUG_LOG(("RTR0DbgKrnlInfoQuerySymbol: #1 returns %d *ppvSymbol=%p\n", rc, *ppvSymbol));
+        }
+        else
+        {
+            /* Init failed. Try resolve symbol, but preserve the status code up to a point. */
+            int rc2 = VERR_SYMBOL_NOT_FOUND;
+            if (g_NtOsKrnlInfo.fOkay)
+                rc2 = rtR0DbgKrnlInfoLookupSymbol(&g_NtOsKrnlInfo, pszSymbol, 0, ppvSymbol);
+            if (g_HalInfo.fOkay && rc2 == VERR_SYMBOL_NOT_FOUND)
+                rc2 = rtR0DbgKrnlInfoLookupSymbol(&g_HalInfo, pszSymbol, 0, ppvSymbol);
+            if (   rc2 == VERR_SYMBOL_NOT_FOUND
+                && g_pfnMmGetSystemRoutineAddress)
+            {
+                /* We'll overwrite init failure status code here since
+                   MmGetSystemRoutineAddress will do the job for us.  */
+                size_t   cwcSymbol;
+                PRTUTF16 pwszSymbol = NULL;
+                rc = RTStrToUtf16Ex(pszSymbol, RTSTR_MAX, &pwszSymbol, 0, &cwcSymbol);
+                if (RT_SUCCESS(rc))
+                {
+                    UNICODE_STRING UniStr;
+                    UniStr.Buffer = pwszSymbol;
+                    UniStr.Length = (uint16_t)(cwcSymbol * sizeof(RTUTF16));
+                    UniStr.MaximumLength = UniStr.Length + sizeof(RTUTF16);
+                    *ppvSymbol = g_pfnMmGetSystemRoutineAddress(&UniStr);
+                    if (*ppvSymbol)
+                        rc = VINF_SUCCESS;
+                    else
+                        rc = VERR_SYMBOL_NOT_FOUND;
+                    RTUtf16Free(pwszSymbol);
+                    RTR0DBG_NT_DEBUG_LOG(("RTR0DbgKrnlInfoQuerySymbol: #2 returns %d *ppvSymbol=%p\n", rc, *ppvSymbol));
+                }
+            }
+        }
+    }
+    else
+    {
+        /*
+         * Search specified module.
+         */
+        rc = VERR_MODULE_NOT_FOUND;
+        PRTDBGNTKRNLMODINFO pModInfo;
+        if (RTStrICmpAscii(pszModule, g_NtOsKrnlInfo.szName) == 0)
+            pModInfo = &g_NtOsKrnlInfo;
+        else if (RTStrICmpAscii(pszModule, g_HalInfo.szName) == 0)
+            pModInfo = &g_NtOsKrnlInfo;
+        else
+        {
+            pModInfo = NULL;
+            for (unsigned i = 0; i < pThis->cModules; i++)
+                if (RTStrICmpAscii(pszModule, pThis->aModules[i].szName) == 0)
+                {
+                    pModInfo = &pThis->aModules[i];
+                    break;
+                }
+            if (!pModInfo)
+            {
+                /*
+                 * Not found, try load it.  If module table is full, drop the first
+                 * entry and shuffle the other up to make space.
+                 */
+                size_t const        cchModule = strlen(pszModule);
+                RTDBGNTKRNLMODINFO  NewModInfo;
+                if (cchModule < sizeof(NewModInfo.szName))
+                {
+                    RT_ZERO(NewModInfo);
+                    memcpy(NewModInfo.szName, pszModule, cchModule);
+                    NewModInfo.szName[cchModule] = '\0';
+
+                    rc = rtR0DbgKrnlNtInit(&NewModInfo);
+                    if (RT_SUCCESS(rc))
+                    {
+                        Assert(NewModInfo.fOkay);
+                        uint32_t iModule = pThis->cModules;
+                        if (iModule >= RT_ELEMENTS(pThis->aModules))
+                        {
+                            iModule = RT_ELEMENTS(pThis->aModules) - 1;
+                            memmove(&pThis->aModules[0], &pThis->aModules[1], iModule * sizeof(pThis->aModules[0]));
+                        }
+                        pThis->aModules[iModule] = NewModInfo;
+                        pThis->cModules          = iModule + 1;
+                        pModInfo = &pThis->aModules[iModule];
+                        rc = VINF_SUCCESS;
+                    }
+                }
+                else
+                {
+                    AssertMsgFailed(("cchModule=%zu pszModule=%s\n", cchModule, pszModule));
+                    rc = VERR_FILENAME_TOO_LONG;
+                }
+            }
+        }
+        if (pModInfo)
+        {
+            rc = rtR0DbgKrnlInfoLookupSymbol(pModInfo, pszSymbol, 0, ppvSymbol);
+            RTR0DBG_NT_DEBUG_LOG(("RTR0DbgKrnlInfoQuerySymbol: #3 returns %d *ppvSymbol=%p\n", rc, *ppvSymbol));
+        }
+    }
+    return rc;
+}
+
+
+RTR0DECL(int) RTR0DbgKrnlInfoQuerySize(RTDBGKRNLINFO hKrnlInfo, const char *pszModule, const char *pszType, size_t *pcbType)
+{
+    RTDBGKRNLINFOINT *pThis = hKrnlInfo;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTDBGKRNLINFO_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+    AssertPtrNullReturn(pszModule, VERR_INVALID_POINTER);
+    AssertPtrReturn(pszType, VERR_INVALID_POINTER);
+    AssertPtrReturn(pcbType, VERR_INVALID_POINTER);
+    return VERR_NOT_FOUND;
+}
+
diff --git a/src/VBox/Runtime/r0drv/nt/initterm-r0drv-nt.cpp b/src/VBox/Runtime/r0drv/nt/initterm-r0drv-nt.cpp
new file mode 100644
index 00000000..171d7754
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/initterm-r0drv-nt.cpp
@@ -0,0 +1,507 @@
+/* $Id: initterm-r0drv-nt.cpp $ */
+/** @file
+ * IPRT - Initialization & Termination, R0 Driver, NT.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-nt-kernel.h"
+#include <iprt/asm-amd64-x86.h>
+#include <iprt/dbg.h>
+#include <iprt/errcore.h>
+#include <iprt/string.h>
+#include "internal/initterm.h"
+#include "internal-r0drv-nt.h"
+#include "symdb.h"
+#include "symdbdata.h"
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/** ExAllocatePoolWithTag, introduced in W2K. */
+decltype(ExAllocatePoolWithTag)        *g_pfnrtExAllocatePoolWithTag;
+/** ExFreePoolWithTag, introduced in W2K. */
+decltype(ExFreePoolWithTag)            *g_pfnrtExFreePoolWithTag;
+/** ExSetTimerResolution, introduced in W2K. */
+PFNMYEXSETTIMERRESOLUTION               g_pfnrtNtExSetTimerResolution;
+/** KeFlushQueuedDpcs, introduced in XP. */
+PFNMYKEFLUSHQUEUEDDPCS                  g_pfnrtNtKeFlushQueuedDpcs;
+/** HalRequestIpi, version introduced with windows 7. */
+PFNHALREQUESTIPI_W7PLUS                 g_pfnrtHalRequestIpiW7Plus;
+/** HalRequestIpi, version valid up to windows vista?? */
+PFNHALREQUESTIPI_PRE_W7                 g_pfnrtHalRequestIpiPreW7;
+/** Worker for RTMpPokeCpu. */
+PFNRTSENDIPI                            g_pfnrtMpPokeCpuWorker;
+/** KeIpiGenericCall - Introduced in Windows Server 2003. */
+PFNRTKEIPIGENERICCALL                   g_pfnrtKeIpiGenericCall;
+/** KeSetTargetProcessorDpcEx - Introduced in Windows 7. */
+PFNKESETTARGETPROCESSORDPCEX            g_pfnrtKeSetTargetProcessorDpcEx;
+/** KeInitializeAffinityEx - Introducted in Windows 7. */
+PFNKEINITIALIZEAFFINITYEX               g_pfnrtKeInitializeAffinityEx;
+/** KeAddProcessorAffinityEx - Introducted in Windows 7. */
+PFNKEADDPROCESSORAFFINITYEX             g_pfnrtKeAddProcessorAffinityEx;
+/** KeGetProcessorIndexFromNumber - Introducted in Windows 7. */
+PFNKEGETPROCESSORINDEXFROMNUMBER        g_pfnrtKeGetProcessorIndexFromNumber;
+/** KeGetProcessorNumberFromIndex - Introducted in Windows 7. */
+PFNKEGETPROCESSORNUMBERFROMINDEX        g_pfnrtKeGetProcessorNumberFromIndex;
+/** KeGetCurrentProcessorNumberEx - Introducted in Windows 7. */
+PFNKEGETCURRENTPROCESSORNUMBEREX        g_pfnrtKeGetCurrentProcessorNumberEx;
+/** KeQueryActiveProcessors - Introducted in Windows 2000. */
+PFNKEQUERYACTIVEPROCESSORS              g_pfnrtKeQueryActiveProcessors;
+/** KeQueryMaximumProcessorCount   - Introducted in Vista and obsoleted W7. */
+PFNKEQUERYMAXIMUMPROCESSORCOUNT         g_pfnrtKeQueryMaximumProcessorCount;
+/** KeQueryMaximumProcessorCountEx - Introducted in Windows 7. */
+PFNKEQUERYMAXIMUMPROCESSORCOUNTEX       g_pfnrtKeQueryMaximumProcessorCountEx;
+/** KeQueryMaximumGroupCount - Introducted in Windows 7. */
+PFNKEQUERYMAXIMUMGROUPCOUNT             g_pfnrtKeQueryMaximumGroupCount;
+/** KeQueryActiveProcessorCount   - Introducted in Vista and obsoleted W7. */
+PFNKEQUERYACTIVEPROCESSORCOUNT          g_pfnrtKeQueryActiveProcessorCount;
+/** KeQueryActiveProcessorCountEx - Introducted in Windows 7. */
+PFNKEQUERYACTIVEPROCESSORCOUNTEX        g_pfnrtKeQueryActiveProcessorCountEx;
+/** KeQueryLogicalProcessorRelationship - Introducted in Windows 7. */
+PFNKEQUERYLOGICALPROCESSORRELATIONSHIP  g_pfnrtKeQueryLogicalProcessorRelationship;
+/** KeRegisterProcessorChangeCallback - Introducted in Windows 7. */
+PFNKEREGISTERPROCESSORCHANGECALLBACK    g_pfnrtKeRegisterProcessorChangeCallback;
+/** KeDeregisterProcessorChangeCallback - Introducted in Windows 7. */
+PFNKEDEREGISTERPROCESSORCHANGECALLBACK  g_pfnrtKeDeregisterProcessorChangeCallback;
+/** KeSetImportanceDpc - Introducted in NT 3.51. */
+decltype(KeSetImportanceDpc)           *g_pfnrtKeSetImportanceDpc;
+/** KeSetTargetProcessorDpc - Introducted in NT 3.51. */
+decltype(KeSetTargetProcessorDpc)      *g_pfnrtKeSetTargetProcessorDpc;
+/** KeInitializeTimerEx - Introduced in NT 4. */
+decltype(KeInitializeTimerEx)          *g_pfnrtKeInitializeTimerEx;
+/** KeShouldYieldProcessor - Introduced in Windows 10. */
+PFNKESHOULDYIELDPROCESSOR               g_pfnrtKeShouldYieldProcessor;
+/** Pointer to the MmProtectMdlSystemAddress kernel function if it's available.
+ * This API was introduced in XP. */
+decltype(MmProtectMdlSystemAddress)    *g_pfnrtMmProtectMdlSystemAddress;
+/** MmAllocatePagesForMdl - Introduced in Windows 2000. */
+decltype(MmAllocatePagesForMdl)        *g_pfnrtMmAllocatePagesForMdl;
+/** MmFreePagesFromMdl - Introduced in Windows 2000. */
+decltype(MmFreePagesFromMdl)           *g_pfnrtMmFreePagesFromMdl;
+/** MmMapLockedPagesSpecifyCache - Introduced in Windows NT4 SP4. */
+decltype(MmMapLockedPagesSpecifyCache) *g_pfnrtMmMapLockedPagesSpecifyCache;
+/** MmAllocateContiguousMemorySpecifyCache - Introduced in Windows 2000. */
+decltype(MmAllocateContiguousMemorySpecifyCache) *g_pfnrtMmAllocateContiguousMemorySpecifyCache;
+/** MmSecureVirtualMemory - Introduced in NT 3.51.   */
+decltype(MmSecureVirtualMemory)        *g_pfnrtMmSecureVirtualMemory;
+/** MmUnsecureVirtualMemory - Introduced in NT 3.51.   */
+decltype(MmUnsecureVirtualMemory)      *g_pfnrtMmUnsecureVirtualMemory;
+/** RtlGetVersion, introduced in ??. */
+PFNRTRTLGETVERSION                      g_pfnrtRtlGetVersion;
+#ifdef RT_ARCH_X86
+/** KeQueryInterruptTime - exported/new in Windows 2000. */
+PFNRTKEQUERYINTERRUPTTIME               g_pfnrtKeQueryInterruptTime;
+#endif
+/** KeQueryInterruptTimePrecise - new in Windows 8. */
+PFNRTKEQUERYINTERRUPTTIMEPRECISE        g_pfnrtKeQueryInterruptTimePrecise;
+/** KeQuerySystemTimePrecise - new in Windows 8. */
+PFNRTKEQUERYSYSTEMTIMEPRECISE           g_pfnrtKeQuerySystemTimePrecise;
+
+/** Offset of the _KPRCB::QuantumEnd field. 0 if not found. */
+uint32_t                                g_offrtNtPbQuantumEnd;
+/** Size of the _KPRCB::QuantumEnd field. 0 if not found. */
+uint32_t                                g_cbrtNtPbQuantumEnd;
+/** Offset of the _KPRCB::DpcQueueDepth field. 0 if not found. */
+uint32_t                                g_offrtNtPbDpcQueueDepth;
+
+/** The combined NT version, see RTNT_MAKE_VERSION. */
+uint32_t                                g_uRtNtVersion = RTNT_MAKE_VERSION(4, 0);
+/** The major version number. */
+uint8_t                                 g_uRtNtMajorVer;
+/** The minor version number. */
+uint8_t                                 g_uRtNtMinorVer;
+/** The build number. */
+uint32_t                                g_uRtNtBuildNo;
+
+/** Pointer to the MmHighestUserAddress kernel variable - can be NULL. */
+uintptr_t const                        *g_puRtMmHighestUserAddress;
+/** Pointer to the MmSystemRangeStart kernel variable - can be NULL. */
+uintptr_t const                        *g_puRtMmSystemRangeStart;
+
+
+/**
+ * Determines the NT kernel verison information.
+ *
+ * @param   pOsVerInfo          Where to return the version information.
+ *
+ * @remarks pOsVerInfo->fSmp is only definitive if @c true.
+ * @remarks pOsVerInfo->uCsdNo is set to MY_NIL_CSD if it cannot be determined.
+ */
+static void rtR0NtGetOsVersionInfo(PRTNTSDBOSVER pOsVerInfo)
+{
+    ULONG       ulMajorVersion = 0;
+    ULONG       ulMinorVersion = 0;
+    ULONG       ulBuildNumber  = 0;
+
+    pOsVerInfo->fChecked    = PsGetVersion(&ulMajorVersion, &ulMinorVersion, &ulBuildNumber, NULL) == TRUE;
+    pOsVerInfo->uMajorVer   = (uint8_t)ulMajorVersion;
+    pOsVerInfo->uMinorVer   = (uint8_t)ulMinorVersion;
+    pOsVerInfo->uBuildNo    = ulBuildNumber;
+#define MY_NIL_CSD      0x3f
+    pOsVerInfo->uCsdNo      = MY_NIL_CSD;
+
+    if (g_pfnrtRtlGetVersion)
+    {
+        RTL_OSVERSIONINFOEXW VerInfo;
+        RT_ZERO(VerInfo);
+        VerInfo.dwOSVersionInfoSize = sizeof(VerInfo);
+
+        NTSTATUS rcNt = g_pfnrtRtlGetVersion(&VerInfo);
+        if (NT_SUCCESS(rcNt))
+            pOsVerInfo->uCsdNo = VerInfo.wServicePackMajor;
+    }
+
+    /* Note! We cannot quite say if something is MP or UNI. So, fSmp is
+             redefined to indicate that it must be MP.
+       Note! RTMpGetCount is not available here. */
+    pOsVerInfo->fSmp = ulMajorVersion >= 6; /* Vista and later has no UNI kernel AFAIK. */
+    if (!pOsVerInfo->fSmp)
+    {
+        if (   g_pfnrtKeQueryMaximumProcessorCountEx
+            && g_pfnrtKeQueryMaximumProcessorCountEx(ALL_PROCESSOR_GROUPS) > 1)
+            pOsVerInfo->fSmp = true;
+        else if (   g_pfnrtKeQueryMaximumProcessorCount
+                 && g_pfnrtKeQueryMaximumProcessorCount() > 1)
+            pOsVerInfo->fSmp = true;
+        else if (   g_pfnrtKeQueryActiveProcessors
+                 && g_pfnrtKeQueryActiveProcessors() > 1)
+            pOsVerInfo->fSmp = true;
+        else if (KeNumberProcessors > 1)
+            pOsVerInfo->fSmp = true;
+    }
+}
+
+
+/**
+ * Tries a set against the current kernel.
+ *
+ * @retval  true if it matched up, global variables are updated.
+ * @retval  false otherwise (no globals updated).
+ * @param   pSet                The data set.
+ * @param   pbPrcb              Pointer to the processor control block.
+ * @param   pszVendor           Pointer to the processor vendor string.
+ * @param   pOsVerInfo          The OS version info.
+ */
+static bool rtR0NtTryMatchSymSet(PCRTNTSDBSET pSet, uint8_t *pbPrcb, const char *pszVendor, PCRTNTSDBOSVER pOsVerInfo)
+{
+    /*
+     * Don't bother trying stuff where the NT kernel version number differs, or
+     * if the build type or SMPness doesn't match up.
+     */
+    if (   pSet->OsVerInfo.uMajorVer != pOsVerInfo->uMajorVer
+        || pSet->OsVerInfo.uMinorVer != pOsVerInfo->uMinorVer
+        || pSet->OsVerInfo.fChecked  != pOsVerInfo->fChecked
+        || (!pSet->OsVerInfo.fSmp && pOsVerInfo->fSmp /*must-be-smp*/) )
+    {
+        //DbgPrint("IPRT: #%d Version/type mismatch.\n", pSet - &g_artNtSdbSets[0]);
+        return false;
+    }
+
+    /*
+     * Do the CPU vendor test.
+     *
+     * Note! The MmIsAddressValid call is the real #PF security here as the
+     *       __try/__except has limited/no ability to catch everything we need.
+     */
+    char *pszPrcbVendorString = (char *)&pbPrcb[pSet->KPRCB.offVendorString];
+    if (!MmIsAddressValid(&pszPrcbVendorString[4 * 3 - 1]))
+    {
+        //DbgPrint("IPRT: #%d invalid vendor string address.\n", pSet - &g_artNtSdbSets[0]);
+        return false;
+    }
+    __try
+    {
+        if (memcmp(pszPrcbVendorString, pszVendor, RT_MIN(4 * 3, pSet->KPRCB.cbVendorString)) != 0)
+        {
+            //DbgPrint("IPRT: #%d Vendor string mismatch.\n", pSet - &g_artNtSdbSets[0]);
+            return false;
+        }
+    }
+    __except(EXCEPTION_EXECUTE_HANDLER)
+    {
+        DbgPrint("IPRT: %#d Exception\n", pSet - &g_artNtSdbSets[0]);
+        return false;
+    }
+
+    /*
+     * Got a match, update the global variables and report succcess.
+     */
+    g_offrtNtPbQuantumEnd    = pSet->KPRCB.offQuantumEnd;
+    g_cbrtNtPbQuantumEnd     = pSet->KPRCB.cbQuantumEnd;
+    g_offrtNtPbDpcQueueDepth = pSet->KPRCB.offDpcQueueDepth;
+
+#if 0
+    DbgPrint("IPRT: Using data set #%u for %u.%usp%u build %u %s %s.\n",
+             pSet - &g_artNtSdbSets[0],
+             pSet->OsVerInfo.uMajorVer,
+             pSet->OsVerInfo.uMinorVer,
+             pSet->OsVerInfo.uCsdNo,
+             pSet->OsVerInfo.uBuildNo,
+             pSet->OsVerInfo.fSmp ? "smp" : "uni",
+             pSet->OsVerInfo.fChecked ? "checked" : "free");
+#endif
+    return true;
+}
+
+
+DECLHIDDEN(int) rtR0InitNative(void)
+{
+    /*
+     * Preinitialize g_uRtNtVersion so RTMemAlloc uses the right kind of pool
+     * when RTR0DbgKrnlInfoOpen calls it.
+     */
+    RTNTSDBOSVER OsVerInfo;
+    rtR0NtGetOsVersionInfo(&OsVerInfo);
+    g_uRtNtVersion  = RTNT_MAKE_VERSION(OsVerInfo.uMajorVer, OsVerInfo.uMinorVer);
+    g_uRtNtMinorVer = OsVerInfo.uMinorVer;
+    g_uRtNtMajorVer = OsVerInfo.uMajorVer;
+    g_uRtNtBuildNo  = OsVerInfo.uBuildNo;
+
+    /*
+     * Initialize the function pointers.
+     */
+    RTDBGKRNLINFO hKrnlInfo;
+    int rc = RTR0DbgKrnlInfoOpen(&hKrnlInfo, 0/*fFlags*/);
+    AssertRCReturn(rc, rc);
+
+#define GET_SYSTEM_ROUTINE_EX(a_Prf, a_Name, a_pfnType) \
+    do { RT_CONCAT3(g_pfnrt, a_Prf, a_Name) = (a_pfnType)RTR0DbgKrnlInfoGetSymbol(hKrnlInfo, NULL, #a_Name); } while (0)
+#define GET_SYSTEM_ROUTINE(a_Name)                 GET_SYSTEM_ROUTINE_EX(RT_NOTHING, a_Name, decltype(a_Name) *)
+#define GET_SYSTEM_ROUTINE_PRF(a_Prf,a_Name)       GET_SYSTEM_ROUTINE_EX(a_Prf, a_Name, decltype(a_Name) *)
+#define GET_SYSTEM_ROUTINE_TYPE(a_Name, a_pfnType) GET_SYSTEM_ROUTINE_EX(RT_NOTHING, a_Name, a_pfnType)
+
+    GET_SYSTEM_ROUTINE(ExAllocatePoolWithTag);
+    GET_SYSTEM_ROUTINE(ExFreePoolWithTag);
+    GET_SYSTEM_ROUTINE_PRF(Nt,ExSetTimerResolution);
+    GET_SYSTEM_ROUTINE_PRF(Nt,KeFlushQueuedDpcs);
+    GET_SYSTEM_ROUTINE(KeIpiGenericCall);
+    GET_SYSTEM_ROUTINE(KeSetTargetProcessorDpcEx);
+    GET_SYSTEM_ROUTINE(KeInitializeAffinityEx);
+    GET_SYSTEM_ROUTINE(KeAddProcessorAffinityEx);
+    GET_SYSTEM_ROUTINE_TYPE(KeGetProcessorIndexFromNumber, PFNKEGETPROCESSORINDEXFROMNUMBER);
+    GET_SYSTEM_ROUTINE(KeGetProcessorNumberFromIndex);
+    GET_SYSTEM_ROUTINE_TYPE(KeGetCurrentProcessorNumberEx, PFNKEGETCURRENTPROCESSORNUMBEREX);
+    GET_SYSTEM_ROUTINE(KeQueryActiveProcessors);
+    GET_SYSTEM_ROUTINE(KeQueryMaximumProcessorCount);
+    GET_SYSTEM_ROUTINE(KeQueryMaximumProcessorCountEx);
+    GET_SYSTEM_ROUTINE(KeQueryMaximumGroupCount);
+    GET_SYSTEM_ROUTINE(KeQueryActiveProcessorCount);
+    GET_SYSTEM_ROUTINE(KeQueryActiveProcessorCountEx);
+    GET_SYSTEM_ROUTINE(KeQueryLogicalProcessorRelationship);
+    GET_SYSTEM_ROUTINE(KeRegisterProcessorChangeCallback);
+    GET_SYSTEM_ROUTINE(KeDeregisterProcessorChangeCallback);
+    GET_SYSTEM_ROUTINE(KeSetImportanceDpc);
+    GET_SYSTEM_ROUTINE(KeSetTargetProcessorDpc);
+    GET_SYSTEM_ROUTINE(KeInitializeTimerEx);
+    GET_SYSTEM_ROUTINE_TYPE(KeShouldYieldProcessor, PFNKESHOULDYIELDPROCESSOR);
+    GET_SYSTEM_ROUTINE(MmProtectMdlSystemAddress);
+    GET_SYSTEM_ROUTINE(MmAllocatePagesForMdl);
+    GET_SYSTEM_ROUTINE(MmFreePagesFromMdl);
+    GET_SYSTEM_ROUTINE(MmMapLockedPagesSpecifyCache);
+    GET_SYSTEM_ROUTINE(MmAllocateContiguousMemorySpecifyCache);
+    GET_SYSTEM_ROUTINE(MmSecureVirtualMemory);
+    GET_SYSTEM_ROUTINE(MmUnsecureVirtualMemory);
+
+    GET_SYSTEM_ROUTINE_TYPE(RtlGetVersion, PFNRTRTLGETVERSION);
+#ifdef RT_ARCH_X86
+    GET_SYSTEM_ROUTINE(KeQueryInterruptTime);
+#endif
+    GET_SYSTEM_ROUTINE_TYPE(KeQueryInterruptTimePrecise, PFNRTKEQUERYINTERRUPTTIMEPRECISE);
+    GET_SYSTEM_ROUTINE_TYPE(KeQuerySystemTimePrecise, PFNRTKEQUERYSYSTEMTIMEPRECISE);
+
+    g_pfnrtHalRequestIpiW7Plus = (PFNHALREQUESTIPI_W7PLUS)RTR0DbgKrnlInfoGetSymbol(hKrnlInfo, NULL, "HalRequestIpi");
+    g_pfnrtHalRequestIpiPreW7 = (PFNHALREQUESTIPI_PRE_W7)g_pfnrtHalRequestIpiW7Plus;
+
+    g_puRtMmHighestUserAddress = (uintptr_t const *)RTR0DbgKrnlInfoGetSymbol(hKrnlInfo, NULL, "MmHighestUserAddress");
+    g_puRtMmSystemRangeStart   = (uintptr_t const *)RTR0DbgKrnlInfoGetSymbol(hKrnlInfo, NULL, "MmSystemRangeStart");
+
+#ifdef RT_ARCH_X86
+    rc = rtR0Nt3InitSymbols(hKrnlInfo);
+    RTR0DbgKrnlInfoRelease(hKrnlInfo);
+    if (RT_FAILURE(rc))
+        return rc;
+#else
+    RTR0DbgKrnlInfoRelease(hKrnlInfo);
+#endif
+
+    /*
+     * Get and publish the definitive NT version.
+     */
+    rtR0NtGetOsVersionInfo(&OsVerInfo);
+    g_uRtNtVersion  = RTNT_MAKE_VERSION(OsVerInfo.uMajorVer, OsVerInfo.uMinorVer);
+    g_uRtNtMinorVer = OsVerInfo.uMinorVer;
+    g_uRtNtMajorVer = OsVerInfo.uMajorVer;
+    g_uRtNtBuildNo  = OsVerInfo.uBuildNo;
+
+
+    /*
+     * HACK ALERT! (and déjà vu warning - remember win32k.sys on OS/2?)
+     *
+     * Try find _KPRCB::QuantumEnd and _KPRCB::[DpcData.]DpcQueueDepth.
+     * For purpose of verification we use the VendorString member (12+1 chars).
+     *
+     * The offsets was initially derived by poking around with windbg
+     * (dt _KPRCB, !prcb ++, and such like). Systematic harvesting was then
+     * planned using dia2dump, grep and the symbol pack in a manner like this:
+     *      dia2dump -type _KDPC_DATA -type _KPRCB EXE\ntkrnlmp.pdb | grep -wE "QuantumEnd|DpcData|DpcQueueDepth|VendorString"
+     *
+     * The final solution ended up using a custom harvester program called
+     * ntBldSymDb that recursively searches thru unpacked symbol packages for
+     * the desired structure offsets.  The program assumes that the packages
+     * are unpacked into directories with the same name as the package, with
+     * exception of some of the w2k packages which requires a 'w2k' prefix to
+     * be distinguishable from another.
+     */
+
+    /*
+     * Gather consistent CPU vendor string and PRCB pointers.
+     */
+    KIRQL OldIrql;
+    KeRaiseIrql(DISPATCH_LEVEL, &OldIrql); /* make sure we stay on the same cpu */
+
+    union
+    {
+        uint32_t auRegs[4];
+        char szVendor[4*3+1];
+    } u;
+    ASMCpuId(0, &u.auRegs[3], &u.auRegs[0], &u.auRegs[2], &u.auRegs[1]);
+    u.szVendor[4*3] = '\0';
+
+    uint8_t *pbPrcb;
+    __try /* Warning. This try/except statement may provide some false safety. */
+    {
+#if defined(RT_ARCH_X86)
+        PKPCR    pPcr   = (PKPCR)__readfsdword(RT_UOFFSETOF(KPCR,SelfPcr));
+        pbPrcb = (uint8_t *)pPcr->Prcb;
+#elif defined(RT_ARCH_AMD64)
+        PKPCR    pPcr   = (PKPCR)__readgsqword(RT_UOFFSETOF(KPCR,Self));
+        pbPrcb = (uint8_t *)pPcr->CurrentPrcb;
+#else
+# error "port me"
+        pbPrcb = NULL;
+#endif
+    }
+    __except(EXCEPTION_EXECUTE_HANDLER)
+    {
+        pbPrcb = NULL;
+    }
+
+    /*
+     * Search the database
+     */
+    if (pbPrcb)
+    {
+        /* Find the best matching kernel version based on build number. */
+        uint32_t iBest      = UINT32_MAX;
+        int32_t  iBestDelta = INT32_MAX;
+        for (uint32_t i = 0; i < RT_ELEMENTS(g_artNtSdbSets); i++)
+        {
+            if (g_artNtSdbSets[i].OsVerInfo.fChecked != OsVerInfo.fChecked)
+                continue;
+            if (OsVerInfo.fSmp /*must-be-smp*/ && !g_artNtSdbSets[i].OsVerInfo.fSmp)
+                continue;
+
+            int32_t iDelta = RT_ABS((int32_t)OsVerInfo.uBuildNo - (int32_t)g_artNtSdbSets[i].OsVerInfo.uBuildNo);
+            if (   iDelta == 0
+                && (g_artNtSdbSets[i].OsVerInfo.uCsdNo == OsVerInfo.uCsdNo || OsVerInfo.uCsdNo == MY_NIL_CSD))
+            {
+                /* prefect */
+                iBestDelta = iDelta;
+                iBest      = i;
+                break;
+            }
+            if (   iDelta < iBestDelta
+                || iBest == UINT32_MAX
+                || (   iDelta == iBestDelta
+                    && OsVerInfo.uCsdNo != MY_NIL_CSD
+                    &&   RT_ABS(g_artNtSdbSets[i    ].OsVerInfo.uCsdNo - (int32_t)OsVerInfo.uCsdNo)
+                       < RT_ABS(g_artNtSdbSets[iBest].OsVerInfo.uCsdNo - (int32_t)OsVerInfo.uCsdNo)
+                   )
+                )
+            {
+                iBestDelta = iDelta;
+                iBest      = i;
+            }
+        }
+        if (iBest < RT_ELEMENTS(g_artNtSdbSets))
+        {
+            /* Try all sets: iBest -> End; iBest -> Start. */
+            bool    fDone = false;
+            int32_t i     = iBest;
+            while (   i < RT_ELEMENTS(g_artNtSdbSets)
+                   && !(fDone = rtR0NtTryMatchSymSet(&g_artNtSdbSets[i], pbPrcb, u.szVendor, &OsVerInfo)))
+                i++;
+            if (!fDone)
+            {
+                i = (int32_t)iBest - 1;
+                while (   i >= 0
+                       && !(fDone = rtR0NtTryMatchSymSet(&g_artNtSdbSets[i], pbPrcb, u.szVendor, &OsVerInfo)))
+                    i--;
+            }
+        }
+        else
+            DbgPrint("IPRT: Failed to locate data set.\n");
+    }
+    else
+        DbgPrint("IPRT: Failed to get PCBR pointer.\n");
+
+    KeLowerIrql(OldIrql); /* Lowering the IRQL early in the hope that we may catch exceptions below. */
+
+#ifndef IN_GUEST
+    if (!g_offrtNtPbQuantumEnd && !g_offrtNtPbDpcQueueDepth)
+        DbgPrint("IPRT: Neither _KPRCB::QuantumEnd nor _KPRCB::DpcQueueDepth was not found! Kernel %u.%u %u %s\n",
+                 OsVerInfo.uMajorVer, OsVerInfo.uMinorVer, OsVerInfo.uBuildNo, OsVerInfo.fChecked ? "checked" : "free");
+# ifdef DEBUG
+    else
+        DbgPrint("IPRT: _KPRCB:{.QuantumEnd=%x/%d, .DpcQueueDepth=%x/%d} Kernel %u.%u %u %s\n",
+                 g_offrtNtPbQuantumEnd, g_cbrtNtPbQuantumEnd, g_offrtNtPbDpcQueueDepth, g_offrtNtPbDpcQueueDepth,
+                 OsVerInfo.uMajorVer, OsVerInfo.uMinorVer, OsVerInfo.uBuildNo, OsVerInfo.fChecked ? "checked" : "free");
+# endif
+#endif
+
+    /*
+     * Initialize multi processor stuff.  This registers a callback, so
+     * we call rtR0TermNative to do the deregistration on failure.
+     */
+    rc = rtR0MpNtInit(&OsVerInfo);
+    if (RT_FAILURE(rc))
+    {
+        rtR0TermNative();
+        DbgPrint("IPRT: Fatal: rtR0MpNtInit failed: %d\n", rc);
+        return rc;
+    }
+
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(void) rtR0TermNative(void)
+{
+    rtR0MpNtTerm();
+}
+
diff --git a/src/VBox/Runtime/r0drv/nt/internal-r0drv-nt.h b/src/VBox/Runtime/r0drv/nt/internal-r0drv-nt.h
new file mode 100644
index 00000000..413f5bed
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/internal-r0drv-nt.h
@@ -0,0 +1,139 @@
+/* $Id: internal-r0drv-nt.h $ */
+/** @file
+ * IPRT - Internal Header for the NT Ring-0 Driver Code.
+ */
+
+/*
+ * Copyright (C) 2008-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+#ifndef IPRT_INCLUDED_SRC_r0drv_nt_internal_r0drv_nt_h
+#define IPRT_INCLUDED_SRC_r0drv_nt_internal_r0drv_nt_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <iprt/cpuset.h>
+#include <iprt/nt/nt.h>
+
+RT_C_DECLS_BEGIN
+
+/*******************************************************************************
+*   Structures and Typedefs                                                    *
+*******************************************************************************/
+typedef ULONG (__stdcall *PFNMYEXSETTIMERRESOLUTION)(ULONG, BOOLEAN);
+typedef VOID (__stdcall *PFNMYKEFLUSHQUEUEDDPCS)(VOID);
+typedef VOID (__stdcall *PFNHALSENDSOFTWAREINTERRUPT)(ULONG ProcessorNumber, KIRQL Irql);
+typedef int (__stdcall *PFNRTSENDIPI)(RTCPUID idCpu);
+typedef ULONG_PTR (__stdcall *PFNRTKEIPIGENERICCALL)(PKIPI_BROADCAST_WORKER BroadcastFunction, ULONG_PTR  Context);
+typedef ULONG (__stdcall *PFNRTRTLGETVERSION)(PRTL_OSVERSIONINFOEXW pVerInfo);
+#ifndef RT_ARCH_AMD64
+typedef ULONGLONG (__stdcall *PFNRTKEQUERYINTERRUPTTIME)(VOID);
+typedef VOID (__stdcall *PFNRTKEQUERYSYSTEMTIME)(PLARGE_INTEGER pTime);
+#endif
+typedef ULONG64 (__stdcall *PFNRTKEQUERYINTERRUPTTIMEPRECISE)(PULONG64 pQpcTS);
+typedef VOID (__stdcall *PFNRTKEQUERYSYSTEMTIMEPRECISE)(PLARGE_INTEGER pTime);
+
+
+/*******************************************************************************
+*   Global Variables                                                           *
+*******************************************************************************/
+extern RTCPUSET                                g_rtMpNtCpuSet;
+extern uint32_t                                g_cRtMpNtMaxGroups;
+extern uint32_t                                g_cRtMpNtMaxCpus;
+extern RTCPUID                                 g_aidRtMpNtByCpuSetIdx[RTCPUSET_MAX_CPUS];
+
+extern decltype(ExAllocatePoolWithTag)        *g_pfnrtExAllocatePoolWithTag;
+extern decltype(ExFreePoolWithTag)            *g_pfnrtExFreePoolWithTag;
+extern PFNMYEXSETTIMERRESOLUTION               g_pfnrtNtExSetTimerResolution;
+extern PFNMYKEFLUSHQUEUEDDPCS                  g_pfnrtNtKeFlushQueuedDpcs;
+extern PFNHALREQUESTIPI_W7PLUS                 g_pfnrtHalRequestIpiW7Plus;
+extern PFNHALREQUESTIPI_PRE_W7                 g_pfnrtHalRequestIpiPreW7;
+extern PFNHALSENDSOFTWAREINTERRUPT             g_pfnrtNtHalSendSoftwareInterrupt;
+extern PFNRTSENDIPI                            g_pfnrtMpPokeCpuWorker;
+extern PFNRTKEIPIGENERICCALL                   g_pfnrtKeIpiGenericCall;
+extern PFNKESETTARGETPROCESSORDPCEX            g_pfnrtKeSetTargetProcessorDpcEx;
+extern PFNKEINITIALIZEAFFINITYEX               g_pfnrtKeInitializeAffinityEx;
+extern PFNKEADDPROCESSORAFFINITYEX             g_pfnrtKeAddProcessorAffinityEx;
+extern PFNKEGETPROCESSORINDEXFROMNUMBER        g_pfnrtKeGetProcessorIndexFromNumber;
+extern PFNKEGETPROCESSORNUMBERFROMINDEX        g_pfnrtKeGetProcessorNumberFromIndex;
+extern PFNKEGETCURRENTPROCESSORNUMBEREX        g_pfnrtKeGetCurrentProcessorNumberEx;
+extern PFNKEQUERYACTIVEPROCESSORS              g_pfnrtKeQueryActiveProcessors;
+extern PFNKEQUERYMAXIMUMPROCESSORCOUNT         g_pfnrtKeQueryMaximumProcessorCount;
+extern PFNKEQUERYMAXIMUMPROCESSORCOUNTEX       g_pfnrtKeQueryMaximumProcessorCountEx;
+extern PFNKEQUERYMAXIMUMGROUPCOUNT             g_pfnrtKeQueryMaximumGroupCount;
+extern PFNKEQUERYACTIVEPROCESSORCOUNT          g_pfnrtKeQueryActiveProcessorCount;
+extern PFNKEQUERYACTIVEPROCESSORCOUNTEX        g_pfnrtKeQueryActiveProcessorCountEx;
+extern PFNKEQUERYLOGICALPROCESSORRELATIONSHIP  g_pfnrtKeQueryLogicalProcessorRelationship;
+extern PFNKEREGISTERPROCESSORCHANGECALLBACK    g_pfnrtKeRegisterProcessorChangeCallback;
+extern PFNKEDEREGISTERPROCESSORCHANGECALLBACK  g_pfnrtKeDeregisterProcessorChangeCallback;
+extern decltype(KeSetImportanceDpc)           *g_pfnrtKeSetImportanceDpc;
+extern decltype(KeSetTargetProcessorDpc)      *g_pfnrtKeSetTargetProcessorDpc;
+extern decltype(KeInitializeTimerEx)          *g_pfnrtKeInitializeTimerEx;
+extern PFNKESHOULDYIELDPROCESSOR               g_pfnrtKeShouldYieldProcessor;
+extern decltype(MmProtectMdlSystemAddress)    *g_pfnrtMmProtectMdlSystemAddress;
+extern decltype(MmAllocatePagesForMdl)        *g_pfnrtMmAllocatePagesForMdl;
+extern decltype(MmFreePagesFromMdl)           *g_pfnrtMmFreePagesFromMdl;
+extern decltype(MmMapLockedPagesSpecifyCache) *g_pfnrtMmMapLockedPagesSpecifyCache;
+extern decltype(MmAllocateContiguousMemorySpecifyCache) *g_pfnrtMmAllocateContiguousMemorySpecifyCache;
+extern decltype(MmSecureVirtualMemory)        *g_pfnrtMmSecureVirtualMemory;
+extern decltype(MmUnsecureVirtualMemory)      *g_pfnrtMmUnsecureVirtualMemory;
+
+extern PFNRTRTLGETVERSION                      g_pfnrtRtlGetVersion;
+#ifdef RT_ARCH_X86
+extern PFNRTKEQUERYINTERRUPTTIME               g_pfnrtKeQueryInterruptTime;
+#endif
+extern PFNRTKEQUERYINTERRUPTTIMEPRECISE        g_pfnrtKeQueryInterruptTimePrecise;
+extern PFNRTKEQUERYSYSTEMTIMEPRECISE           g_pfnrtKeQuerySystemTimePrecise;
+
+extern uint32_t                                g_offrtNtPbQuantumEnd;
+extern uint32_t                                g_cbrtNtPbQuantumEnd;
+extern uint32_t                                g_offrtNtPbDpcQueueDepth;
+
+/** Makes an NT version for checking against g_uRtNtVersion. */
+#define RTNT_MAKE_VERSION(uMajor, uMinor)       RT_MAKE_U32(uMinor, uMajor)
+
+extern uint32_t                                g_uRtNtVersion;
+extern uint8_t                                 g_uRtNtMajorVer;
+extern uint8_t                                 g_uRtNtMinorVer;
+extern uint32_t                                g_uRtNtBuildNo;
+
+extern uintptr_t const                        *g_puRtMmHighestUserAddress;
+extern uintptr_t const                        *g_puRtMmSystemRangeStart;
+
+
+int __stdcall rtMpPokeCpuUsingFailureNotSupported(RTCPUID idCpu);
+int __stdcall rtMpPokeCpuUsingDpc(RTCPUID idCpu);
+int __stdcall rtMpPokeCpuUsingBroadcastIpi(RTCPUID idCpu);
+int __stdcall rtMpPokeCpuUsingHalRequestIpiW7Plus(RTCPUID idCpu);
+int __stdcall rtMpPokeCpuUsingHalRequestIpiPreW7(RTCPUID idCpu);
+
+struct RTNTSDBOSVER;
+DECLHIDDEN(int)  rtR0MpNtInit(struct RTNTSDBOSVER const *pOsVerInfo);
+DECLHIDDEN(void) rtR0MpNtTerm(void);
+DECLHIDDEN(int)  rtMpNtSetTargetProcessorDpc(KDPC *pDpc, RTCPUID idCpu);
+#if defined(RT_ARCH_X86) && defined(NIL_RTDBGKRNLINFO)
+DECLHIDDEN(int)  rtR0Nt3InitSymbols(RTDBGKRNLINFO hKrnlInfo);
+#endif
+
+RT_C_DECLS_END
+
+#endif /* !IPRT_INCLUDED_SRC_r0drv_nt_internal_r0drv_nt_h */
+
diff --git a/src/VBox/Runtime/r0drv/nt/memobj-r0drv-nt.cpp b/src/VBox/Runtime/r0drv/nt/memobj-r0drv-nt.cpp
new file mode 100644
index 00000000..4c96927b
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/memobj-r0drv-nt.cpp
@@ -0,0 +1,1123 @@
+/* $Id: memobj-r0drv-nt.cpp $ */
+/** @file
+ * IPRT - Ring-0 Memory Objects, NT.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-nt-kernel.h"
+
+#include <iprt/memobj.h>
+#include <iprt/alloc.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/log.h>
+#include <iprt/param.h>
+#include <iprt/string.h>
+#include <iprt/process.h>
+#include "internal/memobj.h"
+#include "internal-r0drv-nt.h"
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+/** Maximum number of bytes we try to lock down in one go.
+ * This is supposed to have a limit right below 256MB, but this appears
+ * to actually be much lower. The values here have been determined experimentally.
+ */
+#ifdef RT_ARCH_X86
+# define MAX_LOCK_MEM_SIZE   (32*1024*1024) /* 32MB */
+#endif
+#ifdef RT_ARCH_AMD64
+# define MAX_LOCK_MEM_SIZE   (24*1024*1024) /* 24MB */
+#endif
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * The NT version of the memory object structure.
+ */
+typedef struct RTR0MEMOBJNT
+{
+    /** The core structure. */
+    RTR0MEMOBJINTERNAL  Core;
+    /** Used MmAllocatePagesForMdl(). */
+    bool                fAllocatedPagesForMdl;
+    /** Set if this is sub-section of the parent. */
+    bool                fSubMapping;
+    /** Pointer returned by MmSecureVirtualMemory */
+    PVOID               pvSecureMem;
+    /** The number of PMDLs (memory descriptor lists) in the array. */
+    uint32_t            cMdls;
+    /** Array of MDL pointers. (variable size) */
+    PMDL                apMdls[1];
+} RTR0MEMOBJNT;
+/** Pointer to the NT version of the memory object structure. */
+typedef RTR0MEMOBJNT *PRTR0MEMOBJNT;
+
+
+
+DECLHIDDEN(int) rtR0MemObjNativeFree(RTR0MEMOBJ pMem)
+{
+    PRTR0MEMOBJNT pMemNt = (PRTR0MEMOBJNT)pMem;
+
+    /*
+     * Deal with it on a per type basis (just as a variation).
+     */
+    switch (pMemNt->Core.enmType)
+    {
+        case RTR0MEMOBJTYPE_LOW:
+            if (pMemNt->fAllocatedPagesForMdl)
+            {
+                Assert(pMemNt->Core.pv && pMemNt->cMdls == 1 && pMemNt->apMdls[0]);
+                MmUnmapLockedPages(pMemNt->Core.pv, pMemNt->apMdls[0]);
+                pMemNt->Core.pv = NULL;
+                if (pMemNt->pvSecureMem)
+                {
+                    g_pfnrtMmUnsecureVirtualMemory(pMemNt->pvSecureMem);
+                    pMemNt->pvSecureMem = NULL;
+                }
+
+                g_pfnrtMmFreePagesFromMdl(pMemNt->apMdls[0]);
+                ExFreePool(pMemNt->apMdls[0]);
+                pMemNt->apMdls[0] = NULL;
+                pMemNt->cMdls = 0;
+                break;
+            }
+            AssertFailed();
+            break;
+
+        case RTR0MEMOBJTYPE_PAGE:
+            Assert(pMemNt->Core.pv);
+            if (pMemNt->fAllocatedPagesForMdl)
+            {
+                Assert(pMemNt->Core.pv && pMemNt->cMdls == 1 && pMemNt->apMdls[0]);
+                Assert(pMemNt->pvSecureMem == NULL);
+                MmUnmapLockedPages(pMemNt->Core.pv, pMemNt->apMdls[0]);
+                g_pfnrtMmFreePagesFromMdl(pMemNt->apMdls[0]);
+                ExFreePool(pMemNt->apMdls[0]);
+            }
+            else
+            {
+                if (g_pfnrtExFreePoolWithTag)
+                    g_pfnrtExFreePoolWithTag(pMemNt->Core.pv, IPRT_NT_POOL_TAG);
+                else
+                    ExFreePool(pMemNt->Core.pv);
+
+                Assert(pMemNt->cMdls == 1 && pMemNt->apMdls[0]);
+                IoFreeMdl(pMemNt->apMdls[0]);
+            }
+            pMemNt->Core.pv = NULL;
+            pMemNt->apMdls[0] = NULL;
+            pMemNt->cMdls = 0;
+            break;
+
+        case RTR0MEMOBJTYPE_CONT:
+            Assert(pMemNt->Core.pv);
+            MmFreeContiguousMemory(pMemNt->Core.pv);
+            pMemNt->Core.pv = NULL;
+
+            Assert(pMemNt->cMdls == 1 && pMemNt->apMdls[0]);
+            IoFreeMdl(pMemNt->apMdls[0]);
+            pMemNt->apMdls[0] = NULL;
+            pMemNt->cMdls = 0;
+            break;
+
+        case RTR0MEMOBJTYPE_PHYS:
+            /* rtR0MemObjNativeEnterPhys? */
+            if (!pMemNt->Core.u.Phys.fAllocated)
+            {
+                Assert(!pMemNt->fAllocatedPagesForMdl);
+                /* Nothing to do here. */
+                break;
+            }
+            RT_FALL_THRU();
+
+        case RTR0MEMOBJTYPE_PHYS_NC:
+            if (pMemNt->fAllocatedPagesForMdl)
+            {
+                g_pfnrtMmFreePagesFromMdl(pMemNt->apMdls[0]);
+                ExFreePool(pMemNt->apMdls[0]);
+                pMemNt->apMdls[0] = NULL;
+                pMemNt->cMdls = 0;
+                break;
+            }
+            AssertFailed();
+            break;
+
+        case RTR0MEMOBJTYPE_LOCK:
+            if (pMemNt->pvSecureMem)
+            {
+                g_pfnrtMmUnsecureVirtualMemory(pMemNt->pvSecureMem);
+                pMemNt->pvSecureMem = NULL;
+            }
+            for (uint32_t i = 0; i < pMemNt->cMdls; i++)
+            {
+                MmUnlockPages(pMemNt->apMdls[i]);
+                IoFreeMdl(pMemNt->apMdls[i]);
+                pMemNt->apMdls[i] = NULL;
+            }
+            break;
+
+        case RTR0MEMOBJTYPE_RES_VIRT:
+/*            if (pMemNt->Core.u.ResVirt.R0Process == NIL_RTR0PROCESS)
+            {
+            }
+            else
+            {
+            }*/
+            AssertMsgFailed(("RTR0MEMOBJTYPE_RES_VIRT\n"));
+            return VERR_INTERNAL_ERROR;
+            break;
+
+        case RTR0MEMOBJTYPE_MAPPING:
+        {
+            PRTR0MEMOBJNT pMemNtParent = (PRTR0MEMOBJNT)pMemNt->Core.uRel.Child.pParent;
+            Assert(pMemNtParent);
+            Assert(pMemNt->Core.pv);
+            Assert((pMemNt->cMdls == 0 && !pMemNt->fSubMapping) || (pMemNt->cMdls == 1 && pMemNt->fSubMapping));
+            if (pMemNtParent->cMdls)
+            {
+                Assert(pMemNtParent->cMdls == 1 && pMemNtParent->apMdls[0]);
+                Assert(     pMemNt->Core.u.Mapping.R0Process == NIL_RTR0PROCESS
+                       ||   pMemNt->Core.u.Mapping.R0Process == RTR0ProcHandleSelf());
+                if (!pMemNt->cMdls)
+                    MmUnmapLockedPages(pMemNt->Core.pv, pMemNtParent->apMdls[0]);
+                else
+                {
+                    MmUnmapLockedPages(pMemNt->Core.pv, pMemNt->apMdls[0]);
+                    IoFreeMdl(pMemNt->apMdls[0]);
+                    pMemNt->apMdls[0] = NULL;
+                }
+            }
+            else
+            {
+                Assert(     pMemNtParent->Core.enmType == RTR0MEMOBJTYPE_PHYS
+                       &&   !pMemNtParent->Core.u.Phys.fAllocated);
+                Assert(pMemNt->Core.u.Mapping.R0Process == NIL_RTR0PROCESS);
+                Assert(!pMemNt->fSubMapping);
+                MmUnmapIoSpace(pMemNt->Core.pv, pMemNt->Core.cb);
+            }
+            pMemNt->Core.pv = NULL;
+            break;
+        }
+
+        default:
+            AssertMsgFailed(("enmType=%d\n", pMemNt->Core.enmType));
+            return VERR_INTERNAL_ERROR;
+    }
+
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocPage(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    AssertMsgReturn(cb <= _1G, ("%#x\n", cb), VERR_OUT_OF_RANGE); /* for safe size_t -> ULONG */
+    RT_NOREF1(fExecutable);
+
+    /*
+     * Use MmAllocatePagesForMdl if the allocation is a little bit big.
+     */
+    int rc = VERR_NO_PAGE_MEMORY;
+    if (   cb > _1M
+        && g_pfnrtMmAllocatePagesForMdl
+        && g_pfnrtMmFreePagesFromMdl
+        && g_pfnrtMmMapLockedPagesSpecifyCache)
+    {
+        PHYSICAL_ADDRESS Zero;
+        Zero.QuadPart = 0;
+        PHYSICAL_ADDRESS HighAddr;
+        HighAddr.QuadPart = MAXLONGLONG;
+        PMDL pMdl = g_pfnrtMmAllocatePagesForMdl(Zero, HighAddr, Zero, cb);
+        if (pMdl)
+        {
+            if (MmGetMdlByteCount(pMdl) >= cb)
+            {
+                __try
+                {
+                    void *pv = g_pfnrtMmMapLockedPagesSpecifyCache(pMdl, KernelMode, MmCached, NULL /* no base address */,
+                                                                   FALSE /* no bug check on failure */, NormalPagePriority);
+                    if (pv)
+                    {
+#ifdef RT_ARCH_AMD64
+                        if (fExecutable)
+                            MmProtectMdlSystemAddress(pMdl, PAGE_EXECUTE_READWRITE);
+#endif
+
+                        PRTR0MEMOBJNT pMemNt = (PRTR0MEMOBJNT)rtR0MemObjNew(sizeof(*pMemNt), RTR0MEMOBJTYPE_PAGE, pv, cb);
+                        if (pMemNt)
+                        {
+                            pMemNt->fAllocatedPagesForMdl = true;
+                            pMemNt->cMdls = 1;
+                            pMemNt->apMdls[0] = pMdl;
+                            *ppMem = &pMemNt->Core;
+                            return VINF_SUCCESS;
+                        }
+                        MmUnmapLockedPages(pv, pMdl);
+                    }
+                }
+                __except(EXCEPTION_EXECUTE_HANDLER)
+                {
+# ifdef LOG_ENABLED
+                    NTSTATUS rcNt = GetExceptionCode();
+                    Log(("rtR0MemObjNativeAllocLow: Exception Code %#x\n", rcNt));
+# endif
+                    /* nothing */
+                }
+            }
+            g_pfnrtMmFreePagesFromMdl(pMdl);
+            ExFreePool(pMdl);
+        }
+    }
+
+    /*
+     * Try allocate the memory and create an MDL for them so
+     * we can query the physical addresses and do mappings later
+     * without running into out-of-memory conditions and similar problems.
+     */
+    void *pv;
+    if (g_pfnrtExAllocatePoolWithTag)
+        pv = g_pfnrtExAllocatePoolWithTag(NonPagedPool, cb, IPRT_NT_POOL_TAG);
+    else
+        pv = ExAllocatePool(NonPagedPool, cb);
+    if (pv)
+    {
+        PMDL pMdl = IoAllocateMdl(pv, (ULONG)cb, FALSE, FALSE, NULL);
+        if (pMdl)
+        {
+            MmBuildMdlForNonPagedPool(pMdl);
+#ifdef RT_ARCH_AMD64
+            if (fExecutable)
+                MmProtectMdlSystemAddress(pMdl, PAGE_EXECUTE_READWRITE);
+#endif
+
+            /*
+             * Create the IPRT memory object.
+             */
+            PRTR0MEMOBJNT pMemNt = (PRTR0MEMOBJNT)rtR0MemObjNew(sizeof(*pMemNt), RTR0MEMOBJTYPE_PAGE, pv, cb);
+            if (pMemNt)
+            {
+                pMemNt->cMdls = 1;
+                pMemNt->apMdls[0] = pMdl;
+                *ppMem = &pMemNt->Core;
+                return VINF_SUCCESS;
+            }
+
+            rc = VERR_NO_MEMORY;
+            IoFreeMdl(pMdl);
+        }
+        ExFreePool(pv);
+    }
+    return rc;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocLow(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    AssertMsgReturn(cb <= _1G, ("%#x\n", cb), VERR_OUT_OF_RANGE); /* for safe size_t -> ULONG */
+
+    /*
+     * Try see if we get lucky first...
+     * (We could probably just assume we're lucky on NT4.)
+     */
+    int rc = rtR0MemObjNativeAllocPage(ppMem, cb, fExecutable);
+    if (RT_SUCCESS(rc))
+    {
+        size_t iPage = cb >> PAGE_SHIFT;
+        while (iPage-- > 0)
+            if (rtR0MemObjNativeGetPagePhysAddr(*ppMem, iPage) >= _4G)
+            {
+                rc = VERR_NO_LOW_MEMORY;
+                break;
+            }
+        if (RT_SUCCESS(rc))
+            return rc;
+
+        /* The following ASSUMES that rtR0MemObjNativeAllocPage returns a completed object. */
+        RTR0MemObjFree(*ppMem, false);
+        *ppMem = NULL;
+    }
+
+    /*
+     * Use MmAllocatePagesForMdl to specify the range of physical addresses we wish to use.
+     */
+    if (   g_pfnrtMmAllocatePagesForMdl
+        && g_pfnrtMmFreePagesFromMdl
+        && g_pfnrtMmMapLockedPagesSpecifyCache)
+    {
+        PHYSICAL_ADDRESS Zero;
+        Zero.QuadPart = 0;
+        PHYSICAL_ADDRESS HighAddr;
+        HighAddr.QuadPart = _4G - 1;
+        PMDL pMdl = g_pfnrtMmAllocatePagesForMdl(Zero, HighAddr, Zero, cb);
+        if (pMdl)
+        {
+            if (MmGetMdlByteCount(pMdl) >= cb)
+            {
+                __try
+                {
+                    void *pv = g_pfnrtMmMapLockedPagesSpecifyCache(pMdl, KernelMode, MmCached, NULL /* no base address */,
+                                                                   FALSE /* no bug check on failure */, NormalPagePriority);
+                    if (pv)
+                    {
+                        PRTR0MEMOBJNT pMemNt = (PRTR0MEMOBJNT)rtR0MemObjNew(sizeof(*pMemNt), RTR0MEMOBJTYPE_LOW, pv, cb);
+                        if (pMemNt)
+                        {
+                            pMemNt->fAllocatedPagesForMdl = true;
+                            pMemNt->cMdls = 1;
+                            pMemNt->apMdls[0] = pMdl;
+                            *ppMem = &pMemNt->Core;
+                            return VINF_SUCCESS;
+                        }
+                        MmUnmapLockedPages(pv, pMdl);
+                    }
+                }
+                __except(EXCEPTION_EXECUTE_HANDLER)
+                {
+# ifdef LOG_ENABLED
+                    NTSTATUS rcNt = GetExceptionCode();
+                    Log(("rtR0MemObjNativeAllocLow: Exception Code %#x\n", rcNt));
+# endif
+                    /* nothing */
+                }
+            }
+            g_pfnrtMmFreePagesFromMdl(pMdl);
+            ExFreePool(pMdl);
+        }
+    }
+
+    /*
+     * Fall back on contiguous memory...
+     */
+    return rtR0MemObjNativeAllocCont(ppMem, cb, fExecutable);
+}
+
+
+/**
+ * Internal worker for rtR0MemObjNativeAllocCont(), rtR0MemObjNativeAllocPhys()
+ * and rtR0MemObjNativeAllocPhysNC() that takes a max physical address in addition
+ * to what rtR0MemObjNativeAllocCont() does.
+ *
+ * @returns IPRT status code.
+ * @param   ppMem           Where to store the pointer to the ring-0 memory object.
+ * @param   cb              The size.
+ * @param   fExecutable     Whether the mapping should be executable or not.
+ * @param   PhysHighest     The highest physical address for the pages in allocation.
+ * @param   uAlignment      The alignment of the physical memory to allocate.
+ *                          Supported values are PAGE_SIZE, _2M, _4M and _1G.
+ */
+static int rtR0MemObjNativeAllocContEx(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable, RTHCPHYS PhysHighest,
+                                       size_t uAlignment)
+{
+    AssertMsgReturn(cb <= _1G, ("%#x\n", cb), VERR_OUT_OF_RANGE); /* for safe size_t -> ULONG */
+    RT_NOREF1(fExecutable);
+
+    /*
+     * Allocate the memory and create an MDL for it.
+     */
+    PHYSICAL_ADDRESS PhysAddrHighest;
+    PhysAddrHighest.QuadPart = PhysHighest;
+    void *pv;
+    if (g_pfnrtMmAllocateContiguousMemorySpecifyCache)
+    {
+        PHYSICAL_ADDRESS PhysAddrLowest, PhysAddrBoundary;
+        PhysAddrLowest.QuadPart   = 0;
+        PhysAddrBoundary.QuadPart = (uAlignment == PAGE_SIZE) ? 0 : uAlignment;
+        pv = g_pfnrtMmAllocateContiguousMemorySpecifyCache(cb, PhysAddrLowest, PhysAddrHighest, PhysAddrBoundary, MmCached);
+    }
+    else if (uAlignment == PAGE_SIZE)
+        pv = MmAllocateContiguousMemory(cb, PhysAddrHighest);
+    else
+        return VERR_NOT_SUPPORTED;
+    if (!pv)
+        return VERR_NO_MEMORY;
+
+    PMDL pMdl = IoAllocateMdl(pv, (ULONG)cb, FALSE, FALSE, NULL);
+    if (pMdl)
+    {
+        MmBuildMdlForNonPagedPool(pMdl);
+#ifdef RT_ARCH_AMD64
+        if (fExecutable)
+            MmProtectMdlSystemAddress(pMdl, PAGE_EXECUTE_READWRITE);
+#endif
+
+        PRTR0MEMOBJNT pMemNt = (PRTR0MEMOBJNT)rtR0MemObjNew(sizeof(*pMemNt), RTR0MEMOBJTYPE_CONT, pv, cb);
+        if (pMemNt)
+        {
+            pMemNt->Core.u.Cont.Phys = (RTHCPHYS)*MmGetMdlPfnArray(pMdl) << PAGE_SHIFT;
+            pMemNt->cMdls = 1;
+            pMemNt->apMdls[0] = pMdl;
+            *ppMem = &pMemNt->Core;
+            return VINF_SUCCESS;
+        }
+
+        IoFreeMdl(pMdl);
+    }
+    MmFreeContiguousMemory(pv);
+    return VERR_NO_MEMORY;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocCont(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    return rtR0MemObjNativeAllocContEx(ppMem, cb, fExecutable, _4G-1, PAGE_SIZE /* alignment */);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocPhys(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, RTHCPHYS PhysHighest, size_t uAlignment)
+{
+    /*
+     * Try and see if we're lucky and get a contiguous chunk from MmAllocatePagesForMdl.
+     *
+     * This is preferable to using MmAllocateContiguousMemory because there are
+     * a few situations where the memory shouldn't be mapped, like for instance
+     * VT-x control memory. Since these are rather small allocations (one or
+     * two pages) MmAllocatePagesForMdl will probably be able to satisfy the
+     * request.
+     *
+     * If the allocation is big, the chances are *probably* not very good. The
+     * current limit is kind of random...
+     */
+    if (   cb < _128K
+        && uAlignment == PAGE_SIZE
+        && g_pfnrtMmAllocatePagesForMdl
+        && g_pfnrtMmFreePagesFromMdl)
+    {
+        PHYSICAL_ADDRESS Zero;
+        Zero.QuadPart = 0;
+        PHYSICAL_ADDRESS HighAddr;
+        HighAddr.QuadPart = PhysHighest == NIL_RTHCPHYS ? MAXLONGLONG : PhysHighest;
+        PMDL pMdl = g_pfnrtMmAllocatePagesForMdl(Zero, HighAddr, Zero, cb);
+        if (pMdl)
+        {
+            if (MmGetMdlByteCount(pMdl) >= cb)
+            {
+                PPFN_NUMBER paPfns = MmGetMdlPfnArray(pMdl);
+                PFN_NUMBER Pfn = paPfns[0] + 1;
+                const size_t cPages = cb >> PAGE_SHIFT;
+                size_t iPage;
+                for (iPage = 1; iPage < cPages; iPage++, Pfn++)
+                    if (paPfns[iPage] != Pfn)
+                        break;
+                if (iPage >= cPages)
+                {
+                    PRTR0MEMOBJNT pMemNt = (PRTR0MEMOBJNT)rtR0MemObjNew(sizeof(*pMemNt), RTR0MEMOBJTYPE_PHYS, NULL, cb);
+                    if (pMemNt)
+                    {
+                        pMemNt->Core.u.Phys.fAllocated = true;
+                        pMemNt->Core.u.Phys.PhysBase = (RTHCPHYS)paPfns[0] << PAGE_SHIFT;
+                        pMemNt->fAllocatedPagesForMdl = true;
+                        pMemNt->cMdls = 1;
+                        pMemNt->apMdls[0] = pMdl;
+                        *ppMem = &pMemNt->Core;
+                        return VINF_SUCCESS;
+                    }
+                }
+            }
+            g_pfnrtMmFreePagesFromMdl(pMdl);
+            ExFreePool(pMdl);
+        }
+    }
+
+    return rtR0MemObjNativeAllocContEx(ppMem, cb, false, PhysHighest, uAlignment);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocPhysNC(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, RTHCPHYS PhysHighest)
+{
+    if (g_pfnrtMmAllocatePagesForMdl && g_pfnrtMmFreePagesFromMdl)
+    {
+        PHYSICAL_ADDRESS Zero;
+        Zero.QuadPart = 0;
+        PHYSICAL_ADDRESS HighAddr;
+        HighAddr.QuadPart = PhysHighest == NIL_RTHCPHYS ? MAXLONGLONG : PhysHighest;
+        PMDL pMdl = g_pfnrtMmAllocatePagesForMdl(Zero, HighAddr, Zero, cb);
+        if (pMdl)
+        {
+            if (MmGetMdlByteCount(pMdl) >= cb)
+            {
+                PRTR0MEMOBJNT pMemNt = (PRTR0MEMOBJNT)rtR0MemObjNew(sizeof(*pMemNt), RTR0MEMOBJTYPE_PHYS_NC, NULL, cb);
+                if (pMemNt)
+                {
+                    pMemNt->fAllocatedPagesForMdl = true;
+                    pMemNt->cMdls = 1;
+                    pMemNt->apMdls[0] = pMdl;
+                    *ppMem = &pMemNt->Core;
+                    return VINF_SUCCESS;
+                }
+            }
+            g_pfnrtMmFreePagesFromMdl(pMdl);
+            ExFreePool(pMdl);
+        }
+        return VERR_NO_MEMORY;
+    }
+    return VERR_NOT_SUPPORTED;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeEnterPhys(PPRTR0MEMOBJINTERNAL ppMem, RTHCPHYS Phys, size_t cb, uint32_t uCachePolicy)
+{
+    AssertReturn(uCachePolicy == RTMEM_CACHE_POLICY_DONT_CARE || uCachePolicy == RTMEM_CACHE_POLICY_MMIO, VERR_NOT_SUPPORTED);
+
+    /*
+     * Validate the address range and create a descriptor for it.
+     */
+    PFN_NUMBER Pfn = (PFN_NUMBER)(Phys >> PAGE_SHIFT);
+    if (((RTHCPHYS)Pfn << PAGE_SHIFT) != Phys)
+        return VERR_ADDRESS_TOO_BIG;
+
+    /*
+     * Create the IPRT memory object.
+     */
+    PRTR0MEMOBJNT pMemNt = (PRTR0MEMOBJNT)rtR0MemObjNew(sizeof(*pMemNt), RTR0MEMOBJTYPE_PHYS, NULL, cb);
+    if (pMemNt)
+    {
+        pMemNt->Core.u.Phys.PhysBase = Phys;
+        pMemNt->Core.u.Phys.fAllocated = false;
+        pMemNt->Core.u.Phys.uCachePolicy = uCachePolicy;
+        *ppMem = &pMemNt->Core;
+        return VINF_SUCCESS;
+    }
+    return VERR_NO_MEMORY;
+}
+
+
+/**
+ * Internal worker for locking down pages.
+ *
+ * @return IPRT status code.
+ *
+ * @param   ppMem           Where to store the memory object pointer.
+ * @param   pv              First page.
+ * @param   cb              Number of bytes.
+ * @param   fAccess         The desired access, a combination of RTMEM_PROT_READ
+ *                          and RTMEM_PROT_WRITE.
+ * @param   R0Process       The process \a pv and \a cb refers to.
+ */
+static int rtR0MemObjNtLock(PPRTR0MEMOBJINTERNAL ppMem, void *pv, size_t cb, uint32_t fAccess, RTR0PROCESS R0Process)
+{
+    /*
+     * Calc the number of MDLs we need and allocate the memory object structure.
+     */
+    size_t cMdls = cb / MAX_LOCK_MEM_SIZE;
+    if (cb % MAX_LOCK_MEM_SIZE)
+        cMdls++;
+    if (cMdls >= UINT32_MAX)
+        return VERR_OUT_OF_RANGE;
+    PRTR0MEMOBJNT pMemNt = (PRTR0MEMOBJNT)rtR0MemObjNew(RT_UOFFSETOF_DYN(RTR0MEMOBJNT, apMdls[cMdls]),
+                                                        RTR0MEMOBJTYPE_LOCK, pv, cb);
+    if (!pMemNt)
+        return VERR_NO_MEMORY;
+
+    /*
+     * Loop locking down the sub parts of the memory.
+     */
+    int         rc = VINF_SUCCESS;
+    size_t      cbTotal = 0;
+    uint8_t    *pb = (uint8_t *)pv;
+    uint32_t    iMdl;
+    for (iMdl = 0; iMdl < cMdls; iMdl++)
+    {
+        /*
+         * Calc the Mdl size and allocate it.
+         */
+        size_t cbCur = cb - cbTotal;
+        if (cbCur > MAX_LOCK_MEM_SIZE)
+            cbCur = MAX_LOCK_MEM_SIZE;
+        AssertMsg(cbCur, ("cbCur: 0!\n"));
+        PMDL pMdl = IoAllocateMdl(pb, (ULONG)cbCur, FALSE, FALSE, NULL);
+        if (!pMdl)
+        {
+            rc = VERR_NO_MEMORY;
+            break;
+        }
+
+        /*
+         * Lock the pages.
+         */
+        __try
+        {
+            MmProbeAndLockPages(pMdl,
+                                R0Process == NIL_RTR0PROCESS ? KernelMode : UserMode,
+                                fAccess == RTMEM_PROT_READ
+                                ? IoReadAccess
+                                : fAccess == RTMEM_PROT_WRITE
+                                ? IoWriteAccess
+                                : IoModifyAccess);
+
+            pMemNt->apMdls[iMdl] = pMdl;
+            pMemNt->cMdls++;
+        }
+        __except(EXCEPTION_EXECUTE_HANDLER)
+        {
+            IoFreeMdl(pMdl);
+            rc = VERR_LOCK_FAILED;
+            break;
+        }
+
+        if (   R0Process != NIL_RTR0PROCESS
+            && g_pfnrtMmSecureVirtualMemory
+            && g_pfnrtMmUnsecureVirtualMemory)
+        {
+            /* Make sure the user process can't change the allocation. */
+            pMemNt->pvSecureMem = g_pfnrtMmSecureVirtualMemory(pv, cb,
+                                                               fAccess & RTMEM_PROT_WRITE
+                                                               ? PAGE_READWRITE
+                                                               : PAGE_READONLY);
+            if (!pMemNt->pvSecureMem)
+            {
+                rc = VERR_NO_MEMORY;
+                break;
+            }
+        }
+
+        /* next */
+        cbTotal += cbCur;
+        pb      += cbCur;
+    }
+    if (RT_SUCCESS(rc))
+    {
+        Assert(pMemNt->cMdls == cMdls);
+        pMemNt->Core.u.Lock.R0Process = R0Process;
+        *ppMem = &pMemNt->Core;
+        return rc;
+    }
+
+    /*
+     * We failed, perform cleanups.
+     */
+    while (iMdl-- > 0)
+    {
+        MmUnlockPages(pMemNt->apMdls[iMdl]);
+        IoFreeMdl(pMemNt->apMdls[iMdl]);
+        pMemNt->apMdls[iMdl] = NULL;
+    }
+    if (pMemNt->pvSecureMem)
+    {
+        if (g_pfnrtMmUnsecureVirtualMemory)
+            g_pfnrtMmUnsecureVirtualMemory(pMemNt->pvSecureMem);
+        pMemNt->pvSecureMem = NULL;
+    }
+
+    rtR0MemObjDelete(&pMemNt->Core);
+    return rc;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeLockUser(PPRTR0MEMOBJINTERNAL ppMem, RTR3PTR R3Ptr, size_t cb, uint32_t fAccess,
+                                         RTR0PROCESS R0Process)
+{
+    AssertMsgReturn(R0Process == RTR0ProcHandleSelf(), ("%p != %p\n", R0Process, RTR0ProcHandleSelf()), VERR_NOT_SUPPORTED);
+    /* (Can use MmProbeAndLockProcessPages if we need to mess with other processes later.) */
+    return rtR0MemObjNtLock(ppMem, (void *)R3Ptr, cb, fAccess, R0Process);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeLockKernel(PPRTR0MEMOBJINTERNAL ppMem, void *pv, size_t cb, uint32_t fAccess)
+{
+    return rtR0MemObjNtLock(ppMem, pv, cb, fAccess, NIL_RTR0PROCESS);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeReserveKernel(PPRTR0MEMOBJINTERNAL ppMem, void *pvFixed, size_t cb, size_t uAlignment)
+{
+    /*
+     * MmCreateSection(SEC_RESERVE) + MmMapViewInSystemSpace perhaps?
+     */
+    RT_NOREF4(ppMem, pvFixed, cb, uAlignment);
+    return VERR_NOT_SUPPORTED;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeReserveUser(PPRTR0MEMOBJINTERNAL ppMem, RTR3PTR R3PtrFixed, size_t cb, size_t uAlignment,
+                                            RTR0PROCESS R0Process)
+{
+    /*
+     * ZeCreateSection(SEC_RESERVE) + ZwMapViewOfSection perhaps?
+     */
+    RT_NOREF5(ppMem, R3PtrFixed, cb, uAlignment, R0Process);
+    return VERR_NOT_SUPPORTED;
+}
+
+
+/**
+ * Internal worker for rtR0MemObjNativeMapKernel and rtR0MemObjNativeMapUser.
+ *
+ * @returns IPRT status code.
+ * @param   ppMem       Where to store the memory object for the mapping.
+ * @param   pMemToMap   The memory object to map.
+ * @param   pvFixed     Where to map it. (void *)-1 if anywhere is fine.
+ * @param   uAlignment  The alignment requirement for the mapping.
+ * @param   fProt       The desired page protection for the mapping.
+ * @param   R0Process   If NIL_RTR0PROCESS map into system (kernel) memory.
+ *                      If not nil, it's the current process.
+ * @param   offSub      Offset into @a pMemToMap to start mapping.
+ * @param   cbSub       The number of bytes to map from @a pMapToMem.  0 if
+ *                      we're to map everything. Non-zero if @a offSub is
+ *                      non-zero.
+ */
+static int rtR0MemObjNtMap(PPRTR0MEMOBJINTERNAL ppMem, RTR0MEMOBJ pMemToMap, void *pvFixed, size_t uAlignment,
+                           unsigned fProt, RTR0PROCESS R0Process, size_t offSub, size_t cbSub)
+{
+    int rc = VERR_MAP_FAILED;
+
+    /*
+     * Check that the specified alignment is supported.
+     */
+    if (uAlignment > PAGE_SIZE)
+        return VERR_NOT_SUPPORTED;
+
+    /*
+     * There are two basic cases here, either we've got an MDL and can
+     * map it using MmMapLockedPages, or we've got a contiguous physical
+     * range (MMIO most likely) and can use MmMapIoSpace.
+     */
+    PRTR0MEMOBJNT pMemNtToMap = (PRTR0MEMOBJNT)pMemToMap;
+    if (pMemNtToMap->cMdls)
+    {
+        /* don't attempt map locked regions with more than one mdl. */
+        if (pMemNtToMap->cMdls != 1)
+            return VERR_NOT_SUPPORTED;
+
+        /* Need g_pfnrtMmMapLockedPagesSpecifyCache to map to a specific address. */
+        if (pvFixed != (void *)-1 && g_pfnrtMmMapLockedPagesSpecifyCache == NULL)
+            return VERR_NOT_SUPPORTED;
+
+        /* we can't map anything to the first page, sorry. */
+        if (pvFixed == 0)
+            return VERR_NOT_SUPPORTED;
+
+        /* only one system mapping for now - no time to figure out MDL restrictions right now. */
+        if (    pMemNtToMap->Core.uRel.Parent.cMappings
+            &&  R0Process == NIL_RTR0PROCESS)
+        {
+            if (pMemNtToMap->Core.enmType != RTR0MEMOBJTYPE_PHYS_NC)
+                return VERR_NOT_SUPPORTED;
+            uint32_t iMapping = pMemNtToMap->Core.uRel.Parent.cMappings;
+            while (iMapping-- > 0)
+            {
+                PRTR0MEMOBJNT pMapping = (PRTR0MEMOBJNT)pMemNtToMap->Core.uRel.Parent.papMappings[iMapping];
+                if (   pMapping->Core.enmType != RTR0MEMOBJTYPE_MAPPING
+                    || pMapping->Core.u.Mapping.R0Process == NIL_RTR0PROCESS)
+                    return VERR_NOT_SUPPORTED;
+            }
+        }
+
+        /* Create a partial MDL if this is a sub-range request. */
+        PMDL pMdl;
+        if (!offSub && !cbSub)
+            pMdl = pMemNtToMap->apMdls[0];
+        else
+        {
+            pMdl = IoAllocateMdl(NULL, (ULONG)cbSub, FALSE, FALSE, NULL);
+            if (pMdl)
+                IoBuildPartialMdl(pMemNtToMap->apMdls[0], pMdl,
+                                  (uint8_t *)MmGetMdlVirtualAddress(pMemNtToMap->apMdls[0]) + offSub, (ULONG)cbSub);
+            else
+            {
+                IoFreeMdl(pMdl);
+                return VERR_NO_MEMORY;
+            }
+        }
+
+        __try
+        {
+            /** @todo uAlignment */
+            /** @todo How to set the protection on the pages? */
+            void *pv;
+            if (g_pfnrtMmMapLockedPagesSpecifyCache)
+                pv = g_pfnrtMmMapLockedPagesSpecifyCache(pMdl,
+                                                         R0Process == NIL_RTR0PROCESS ? KernelMode : UserMode,
+                                                         MmCached,
+                                                         pvFixed != (void *)-1 ? pvFixed : NULL,
+                                                         FALSE /* no bug check on failure */,
+                                                         NormalPagePriority);
+            else
+                pv = MmMapLockedPages(pMdl, R0Process == NIL_RTR0PROCESS ? KernelMode : UserMode);
+            if (pv)
+            {
+                NOREF(fProt);
+
+                PRTR0MEMOBJNT pMemNt = (PRTR0MEMOBJNT)rtR0MemObjNew(  !offSub && !cbSub
+                                                                    ? sizeof(*pMemNt) : RT_UOFFSETOF_DYN(RTR0MEMOBJNT, apMdls[1]),
+                                                                    RTR0MEMOBJTYPE_MAPPING, pv, pMemNtToMap->Core.cb);
+                if (pMemNt)
+                {
+                    pMemNt->Core.u.Mapping.R0Process = R0Process;
+                    if (!offSub && !cbSub)
+                        pMemNt->fSubMapping = false;
+                    else
+                    {
+                        pMemNt->apMdls[0]   = pMdl;
+                        pMemNt->cMdls       = 1;
+                        pMemNt->fSubMapping = true;
+                    }
+
+                    *ppMem = &pMemNt->Core;
+                    return VINF_SUCCESS;
+                }
+
+                rc = VERR_NO_MEMORY;
+                MmUnmapLockedPages(pv, pMdl);
+            }
+        }
+        __except(EXCEPTION_EXECUTE_HANDLER)
+        {
+#ifdef LOG_ENABLED
+            NTSTATUS rcNt = GetExceptionCode();
+            Log(("rtR0MemObjNtMap: Exception Code %#x\n", rcNt));
+#endif
+
+            /* nothing */
+            rc = VERR_MAP_FAILED;
+        }
+
+    }
+    else
+    {
+        AssertReturn(   pMemNtToMap->Core.enmType == RTR0MEMOBJTYPE_PHYS
+                     && !pMemNtToMap->Core.u.Phys.fAllocated, VERR_INTERNAL_ERROR);
+
+        /* cannot map phys mem to user space (yet). */
+        if (R0Process != NIL_RTR0PROCESS)
+            return VERR_NOT_SUPPORTED;
+
+        /* Cannot sub-mak these (yet). */
+        AssertMsgReturn(!offSub && !cbSub, ("%#zx %#zx\n", offSub, cbSub), VERR_NOT_SUPPORTED);
+
+
+        /** @todo uAlignment */
+        /** @todo How to set the protection on the pages? */
+        PHYSICAL_ADDRESS Phys;
+        Phys.QuadPart = pMemNtToMap->Core.u.Phys.PhysBase;
+        void *pv = MmMapIoSpace(Phys, pMemNtToMap->Core.cb,
+                                pMemNtToMap->Core.u.Phys.uCachePolicy == RTMEM_CACHE_POLICY_MMIO ? MmNonCached : MmCached);
+        if (pv)
+        {
+            PRTR0MEMOBJNT pMemNt = (PRTR0MEMOBJNT)rtR0MemObjNew(sizeof(*pMemNt), RTR0MEMOBJTYPE_MAPPING, pv,
+                                                                pMemNtToMap->Core.cb);
+            if (pMemNt)
+            {
+                pMemNt->Core.u.Mapping.R0Process = R0Process;
+                *ppMem = &pMemNt->Core;
+                return VINF_SUCCESS;
+            }
+
+            rc = VERR_NO_MEMORY;
+            MmUnmapIoSpace(pv, pMemNtToMap->Core.cb);
+        }
+    }
+
+    NOREF(uAlignment); NOREF(fProt);
+    return rc;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeMapKernel(PPRTR0MEMOBJINTERNAL ppMem, RTR0MEMOBJ pMemToMap, void *pvFixed, size_t uAlignment,
+                                          unsigned fProt, size_t offSub, size_t cbSub)
+{
+    return rtR0MemObjNtMap(ppMem, pMemToMap, pvFixed, uAlignment, fProt, NIL_RTR0PROCESS, offSub, cbSub);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeMapUser(PPRTR0MEMOBJINTERNAL ppMem, RTR0MEMOBJ pMemToMap, RTR3PTR R3PtrFixed, size_t uAlignment,
+                                        unsigned fProt, RTR0PROCESS R0Process, size_t offSub, size_t cbSub)
+{
+    AssertReturn(R0Process == RTR0ProcHandleSelf(), VERR_NOT_SUPPORTED);
+    return rtR0MemObjNtMap(ppMem, pMemToMap, (void *)R3PtrFixed, uAlignment, fProt, R0Process, offSub, cbSub);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeProtect(PRTR0MEMOBJINTERNAL pMem, size_t offSub, size_t cbSub, uint32_t fProt)
+{
+#if 0
+    PRTR0MEMOBJNT pMemNt = (PRTR0MEMOBJNT)pMem;
+#endif
+
+    /*
+     * Seems there are some issues with this MmProtectMdlSystemAddress API, so
+     * this code isn't currently enabled until we've tested it with the verifier.
+     */
+#if 0
+    /*
+     * The API we've got requires a kernel mapping.
+     */
+    if (   pMemNt->cMdls
+        && g_pfnrtMmProtectMdlSystemAddress
+        && (g_uRtNtMajorVer > 6 || (g_uRtNtMajorVer == 6 && g_uRtNtMinorVer >= 1)) /* Windows 7 and later. */
+        && pMemNt->Core.pv != NULL
+        && (   pMemNt->Core.enmType == RTR0MEMOBJTYPE_PAGE
+            || pMemNt->Core.enmType == RTR0MEMOBJTYPE_LOW
+            || pMemNt->Core.enmType == RTR0MEMOBJTYPE_CONT
+            || (   pMemNt->Core.enmType             == RTR0MEMOBJTYPE_LOCK
+                && pMemNt->Core.u.Lock.R0Process    == NIL_RTPROCESS)
+            || (   pMemNt->Core.enmType             == RTR0MEMOBJTYPE_MAPPING
+                && pMemNt->Core.u.Mapping.R0Process == NIL_RTPROCESS) ) )
+    {
+        /* Convert the protection. */
+        LOCK_OPERATION enmLockOp;
+        ULONG fAccess;
+        switch (fProt)
+        {
+            case RTMEM_PROT_NONE:
+                fAccess = PAGE_NOACCESS;
+                enmLockOp = IoReadAccess;
+                break;
+            case RTMEM_PROT_READ:
+                fAccess = PAGE_READONLY;
+                enmLockOp = IoReadAccess;
+                break;
+            case RTMEM_PROT_WRITE:
+            case RTMEM_PROT_WRITE | RTMEM_PROT_READ:
+                fAccess = PAGE_READWRITE;
+                enmLockOp = IoModifyAccess;
+                break;
+            case RTMEM_PROT_EXEC:
+                fAccess = PAGE_EXECUTE;
+                enmLockOp = IoReadAccess;
+                break;
+            case RTMEM_PROT_EXEC | RTMEM_PROT_READ:
+                fAccess = PAGE_EXECUTE_READ;
+                enmLockOp = IoReadAccess;
+                break;
+            case RTMEM_PROT_EXEC | RTMEM_PROT_WRITE:
+            case RTMEM_PROT_EXEC | RTMEM_PROT_WRITE | RTMEM_PROT_READ:
+                fAccess = PAGE_EXECUTE_READWRITE;
+                enmLockOp = IoModifyAccess;
+                break;
+            default:
+                AssertFailedReturn(VERR_INVALID_FLAGS);
+        }
+
+        NTSTATUS rcNt = STATUS_SUCCESS;
+# if 0 /** @todo test this against the verifier. */
+        if (offSub == 0 && pMemNt->Core.cb == cbSub)
+        {
+            uint32_t iMdl = pMemNt->cMdls;
+            while (iMdl-- > 0)
+            {
+                rcNt = g_pfnrtMmProtectMdlSystemAddress(pMemNt->apMdls[i], fAccess);
+                if (!NT_SUCCESS(rcNt))
+                    break;
+            }
+        }
+        else
+# endif
+        {
+            /*
+             * We ASSUME the following here:
+             *   - MmProtectMdlSystemAddress can deal with nonpaged pool memory
+             *   - MmProtectMdlSystemAddress doesn't actually store anything in the MDL we pass it.
+             *   - We are not required to call MmProtectMdlSystemAddress with PAGE_READWRITE for the
+             *     exact same ranges prior to freeing them.
+             *
+             * So, we lock the pages temporarily, call the API and unlock them.
+             */
+            uint8_t *pbCur = (uint8_t *)pMemNt->Core.pv + offSub;
+            while (cbSub > 0 && NT_SUCCESS(rcNt))
+            {
+                size_t cbCur = cbSub;
+                if (cbCur > MAX_LOCK_MEM_SIZE)
+                    cbCur = MAX_LOCK_MEM_SIZE;
+                PMDL pMdl = IoAllocateMdl(pbCur, (ULONG)cbCur, FALSE, FALSE, NULL);
+                if (pMdl)
+                {
+                    __try
+                    {
+                        MmProbeAndLockPages(pMdl, KernelMode, enmLockOp);
+                    }
+                    __except(EXCEPTION_EXECUTE_HANDLER)
+                    {
+                        rcNt = GetExceptionCode();
+                    }
+                    if (NT_SUCCESS(rcNt))
+                    {
+                        rcNt = g_pfnrtMmProtectMdlSystemAddress(pMdl, fAccess);
+                        MmUnlockPages(pMdl);
+                    }
+                    IoFreeMdl(pMdl);
+                }
+                else
+                    rcNt = STATUS_NO_MEMORY;
+                pbCur += cbCur;
+                cbSub -= cbCur;
+            }
+        }
+
+        if (NT_SUCCESS(rcNt))
+            return VINF_SUCCESS;
+        return RTErrConvertFromNtStatus(rcNt);
+    }
+#else
+    RT_NOREF4(pMem, offSub, cbSub, fProt);
+#endif
+
+    return VERR_NOT_SUPPORTED;
+}
+
+
+DECLHIDDEN(RTHCPHYS) rtR0MemObjNativeGetPagePhysAddr(PRTR0MEMOBJINTERNAL pMem, size_t iPage)
+{
+    PRTR0MEMOBJNT pMemNt = (PRTR0MEMOBJNT)pMem;
+
+    if (pMemNt->cMdls)
+    {
+        if (pMemNt->cMdls == 1)
+        {
+            PPFN_NUMBER paPfns = MmGetMdlPfnArray(pMemNt->apMdls[0]);
+            return (RTHCPHYS)paPfns[iPage] << PAGE_SHIFT;
+        }
+
+        size_t iMdl = iPage / (MAX_LOCK_MEM_SIZE >> PAGE_SHIFT);
+        size_t iMdlPfn = iPage % (MAX_LOCK_MEM_SIZE >> PAGE_SHIFT);
+        PPFN_NUMBER paPfns = MmGetMdlPfnArray(pMemNt->apMdls[iMdl]);
+        return (RTHCPHYS)paPfns[iMdlPfn] << PAGE_SHIFT;
+    }
+
+    switch (pMemNt->Core.enmType)
+    {
+        case RTR0MEMOBJTYPE_MAPPING:
+            return rtR0MemObjNativeGetPagePhysAddr(pMemNt->Core.uRel.Child.pParent, iPage);
+
+        case RTR0MEMOBJTYPE_PHYS:
+            return pMemNt->Core.u.Phys.PhysBase + (iPage << PAGE_SHIFT);
+
+        case RTR0MEMOBJTYPE_PAGE:
+        case RTR0MEMOBJTYPE_PHYS_NC:
+        case RTR0MEMOBJTYPE_LOW:
+        case RTR0MEMOBJTYPE_CONT:
+        case RTR0MEMOBJTYPE_LOCK:
+        default:
+            AssertMsgFailed(("%d\n", pMemNt->Core.enmType));
+        case RTR0MEMOBJTYPE_RES_VIRT:
+            return NIL_RTHCPHYS;
+    }
+}
+
diff --git a/src/VBox/Runtime/r0drv/nt/memuserkernel-r0drv-nt.cpp b/src/VBox/Runtime/r0drv/nt/memuserkernel-r0drv-nt.cpp
new file mode 100644
index 00000000..e75858f4
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/memuserkernel-r0drv-nt.cpp
@@ -0,0 +1,123 @@
+/* $Id: memuserkernel-r0drv-nt.cpp $ */
+/** @file
+ * IPRT - User & Kernel Memory, Ring-0 Driver, NT.
+ */
+
+/*
+ * Copyright (C) 2009-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-nt-kernel.h"
+
+#include <iprt/mem.h>
+#include <iprt/errcore.h>
+
+#include "internal-r0drv-nt.h"
+
+
+RTR0DECL(int) RTR0MemUserCopyFrom(void *pvDst, RTR3PTR R3PtrSrc, size_t cb)
+{
+    __try
+    {
+        ProbeForRead((PVOID)R3PtrSrc, cb, 1);
+        memcpy(pvDst, (void const *)R3PtrSrc, cb);
+    }
+    __except(EXCEPTION_EXECUTE_HANDLER)
+    {
+        return VERR_ACCESS_DENIED;
+    }
+    return VINF_SUCCESS;
+}
+
+
+RTR0DECL(int) RTR0MemUserCopyTo(RTR3PTR R3PtrDst, void const *pvSrc, size_t cb)
+{
+    __try
+    {
+        ProbeForWrite((PVOID)R3PtrDst, cb, 1);
+        memcpy((void *)R3PtrDst, pvSrc, cb);
+    }
+    __except(EXCEPTION_EXECUTE_HANDLER)
+    {
+        return VERR_ACCESS_DENIED;
+    }
+    return VINF_SUCCESS;
+}
+
+
+RTR0DECL(bool) RTR0MemUserIsValidAddr(RTR3PTR R3Ptr)
+{
+#ifdef IPRT_TARGET_NT4
+    uintptr_t const uLast = g_puRtMmHighestUserAddress ? *g_puRtMmHighestUserAddress : ~(uintptr_t)0 / 2;
+#else
+    uintptr_t const uLast = (uintptr_t)MM_HIGHEST_USER_ADDRESS;
+#endif
+    return R3Ptr <= uLast;
+}
+
+
+RTR0DECL(bool) RTR0MemKernelIsValidAddr(void *pv)
+{
+#ifdef IPRT_TARGET_NT4
+    uintptr_t const uFirst = g_puRtMmSystemRangeStart ? *g_puRtMmSystemRangeStart : ~(uintptr_t)0 / 2 + 1;
+#else
+    uintptr_t const uFirst = (uintptr_t)MM_SYSTEM_RANGE_START;
+#endif
+    return (uintptr_t)pv >= uFirst;
+}
+
+
+RTR0DECL(bool) RTR0MemAreKrnlAndUsrDifferent(void)
+{
+    return true;
+}
+
+
+RTR0DECL(int) RTR0MemKernelCopyFrom(void *pvDst, void const *pvSrc, size_t cb)
+{
+    __try
+    {
+        memcpy(pvDst, pvSrc, cb);
+    }
+    __except(EXCEPTION_EXECUTE_HANDLER)
+    {
+        return VERR_ACCESS_DENIED;
+    }
+    return VINF_SUCCESS;
+}
+
+
+RTR0DECL(int) RTR0MemKernelCopyTo(void *pvDst, void const *pvSrc, size_t cb)
+{
+    __try
+    {
+        memcpy(pvDst, pvSrc, cb);
+    }
+    __except(EXCEPTION_EXECUTE_HANDLER)
+    {
+        return VERR_ACCESS_DENIED;
+    }
+    return VINF_SUCCESS;
+}
+
diff --git a/src/VBox/Runtime/r0drv/nt/mp-r0drv-nt.cpp b/src/VBox/Runtime/r0drv/nt/mp-r0drv-nt.cpp
new file mode 100644
index 00000000..9419e41f
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/mp-r0drv-nt.cpp
@@ -0,0 +1,1979 @@
+/* $Id: mp-r0drv-nt.cpp $ */
+/** @file
+ * IPRT - Multiprocessor, Ring-0 Driver, NT.
+ */
+
+/*
+ * Copyright (C) 2008-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-nt-kernel.h"
+
+#include <iprt/mp.h>
+#include <iprt/cpuset.h>
+#include <iprt/err.h>
+#include <iprt/asm.h>
+#include <iprt/log.h>
+#include <iprt/mem.h>
+#include <iprt/time.h>
+#include "r0drv/mp-r0drv.h"
+#include "symdb.h"
+#include "internal-r0drv-nt.h"
+#include "internal/mp.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+typedef enum
+{
+    RT_NT_CPUID_SPECIFIC,
+    RT_NT_CPUID_PAIR,
+    RT_NT_CPUID_OTHERS,
+    RT_NT_CPUID_ALL
+} RT_NT_CPUID;
+
+
+/**
+ * Used by the RTMpOnSpecific.
+ */
+typedef struct RTMPNTONSPECIFICARGS
+{
+    /** Set if we're executing. */
+    bool volatile       fExecuting;
+    /** Set when done executing. */
+    bool volatile       fDone;
+    /** Number of references to this heap block. */
+    uint32_t volatile   cRefs;
+    /** Event that the calling thread is waiting on. */
+    KEVENT              DoneEvt;
+    /** The deferred procedure call object. */
+    KDPC                Dpc;
+    /** The callback argument package. */
+    RTMPARGS            CallbackArgs;
+} RTMPNTONSPECIFICARGS;
+/** Pointer to an argument/state structure for RTMpOnSpecific on NT. */
+typedef RTMPNTONSPECIFICARGS *PRTMPNTONSPECIFICARGS;
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+/** Inactive bit for g_aidRtMpNtByCpuSetIdx. */
+#define RTMPNT_ID_F_INACTIVE    RT_BIT_32(31)
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/** Maximum number of processor groups. */
+uint32_t                                g_cRtMpNtMaxGroups;
+/** Maximum number of processors. */
+uint32_t                                g_cRtMpNtMaxCpus;
+/** Number of active processors. */
+uint32_t volatile                       g_cRtMpNtActiveCpus;
+/** The NT CPU set.
+ * KeQueryActiveProcssors() cannot be called at all IRQLs and therefore we'll
+ * have to cache it.  Fortunately, NT doesn't really support taking CPUs offline,
+ * and taking them online was introduced with W2K8 where it is intended for virtual
+ * machines and not real HW.  We update this, g_cRtMpNtActiveCpus and
+ * g_aidRtMpNtByCpuSetIdx from the rtR0NtMpProcessorChangeCallback.
+ */
+RTCPUSET                                g_rtMpNtCpuSet;
+
+/** Static per group info.
+ * @remarks  With 256 groups this takes up 33KB.  */
+static struct
+{
+    /** The max CPUs in the group. */
+    uint16_t    cMaxCpus;
+    /** The number of active CPUs at the time of initialization. */
+    uint16_t    cActiveCpus;
+    /** CPU set indexes for each CPU in the group. */
+    int16_t     aidxCpuSetMembers[64];
+}                                       g_aRtMpNtCpuGroups[256];
+/** Maps CPU set indexes to RTCPUID.
+ * Inactive CPUs has bit 31 set (RTMPNT_ID_F_INACTIVE) so we can identify them
+ * and shuffle duplicates during CPU hotplugging.  We assign temporary IDs to
+ * the inactive CPUs starting at g_cRtMpNtMaxCpus - 1, ASSUMING that active
+ * CPUs has IDs from 0 to g_cRtMpNtActiveCpus. */
+RTCPUID                                 g_aidRtMpNtByCpuSetIdx[RTCPUSET_MAX_CPUS];
+/** The handle of the rtR0NtMpProcessorChangeCallback registration. */
+static PVOID                            g_pvMpCpuChangeCallback = NULL;
+/** Size of the KAFFINITY_EX structure.
+ * This increased from 20 to 32 bitmap words in the 2020 H2 windows 10 release
+ * (i.e. 1280 to 2048 CPUs).  We expect this to increase in the future. */
+static size_t                           g_cbRtMpNtKaffinityEx = RT_UOFFSETOF(KAFFINITY_EX, Bitmap)
+                                                              + RT_SIZEOFMEMB(KAFFINITY_EX, Bitmap[0]) * 256;
+/** The size value of the KAFFINITY_EX structure. */
+static uint16_t                         g_cRtMpNtKaffinityExEntries = 256;
+
+
+/*********************************************************************************************************************************
+*   Internal Functions                                                                                                           *
+*********************************************************************************************************************************/
+static VOID __stdcall rtR0NtMpProcessorChangeCallback(void *pvUser, PKE_PROCESSOR_CHANGE_NOTIFY_CONTEXT pChangeCtx,
+                                                      PNTSTATUS prcOperationStatus);
+static int rtR0NtInitQueryGroupRelations(SYSTEM_LOGICAL_PROCESSOR_INFORMATION_EX **ppInfo);
+
+
+
+/**
+ * Initalizes multiprocessor globals (called by rtR0InitNative).
+ *
+ * @returns IPRT status code.
+ * @param   pOsVerInfo          Version information.
+ */
+DECLHIDDEN(int) rtR0MpNtInit(RTNTSDBOSVER const *pOsVerInfo)
+{
+#define MY_CHECK_BREAK(a_Check, a_DbgPrintArgs) \
+        AssertMsgBreakStmt(a_Check, a_DbgPrintArgs, DbgPrint a_DbgPrintArgs; rc = VERR_INTERNAL_ERROR_4 )
+#define MY_CHECK_RETURN(a_Check, a_DbgPrintArgs, a_rcRet) \
+        AssertMsgReturnStmt(a_Check, a_DbgPrintArgs, DbgPrint a_DbgPrintArgs, a_rcRet)
+#define MY_CHECK(a_Check, a_DbgPrintArgs) \
+        AssertMsgStmt(a_Check, a_DbgPrintArgs, DbgPrint a_DbgPrintArgs; rc = VERR_INTERNAL_ERROR_4 )
+
+    /*
+     * API combination checks.
+     */
+    MY_CHECK_RETURN(!g_pfnrtKeSetTargetProcessorDpcEx || g_pfnrtKeGetProcessorNumberFromIndex,
+                    ("IPRT: Fatal: Missing KeSetTargetProcessorDpcEx without KeGetProcessorNumberFromIndex!\n"),
+                    VERR_SYMBOL_NOT_FOUND);
+
+    /*
+     * Get max number of processor groups.
+     *
+     * We may need to upadjust this number below, because windows likes to keep
+     * all options open when it comes to hotplugged CPU group assignments.  A
+     * server advertising up to 64 CPUs in the ACPI table will get a result of
+     * 64 from KeQueryMaximumGroupCount.  That makes sense.  However, when windows
+     * server 2012 does a two processor group setup for it, the sum of the
+     * GroupInfo[*].MaximumProcessorCount members below is 128.  This is probably
+     * because windows doesn't want to make decisions grouping of hotpluggable CPUs.
+     * So, we need to bump the maximum count to 128 below do deal with this as we
+     * want to have valid CPU set indexes for all potential CPUs - how could we
+     * otherwise use the RTMpGetSet() result and also RTCpuSetCount(RTMpGetSet())
+     * should equal RTMpGetCount().
+     */
+    if (g_pfnrtKeQueryMaximumGroupCount)
+    {
+        g_cRtMpNtMaxGroups = g_pfnrtKeQueryMaximumGroupCount();
+        MY_CHECK_RETURN(g_cRtMpNtMaxGroups <= RTCPUSET_MAX_CPUS && g_cRtMpNtMaxGroups > 0,
+                        ("IPRT: Fatal: g_cRtMpNtMaxGroups=%u, max %u\n", g_cRtMpNtMaxGroups, RTCPUSET_MAX_CPUS),
+                        VERR_MP_TOO_MANY_CPUS);
+    }
+    else
+        g_cRtMpNtMaxGroups = 1;
+
+    /*
+     * Get max number CPUs.
+     * This also defines the range of NT CPU indexes, RTCPUID and index into RTCPUSET.
+     */
+    if (g_pfnrtKeQueryMaximumProcessorCountEx)
+    {
+        g_cRtMpNtMaxCpus = g_pfnrtKeQueryMaximumProcessorCountEx(ALL_PROCESSOR_GROUPS);
+        MY_CHECK_RETURN(g_cRtMpNtMaxCpus <= RTCPUSET_MAX_CPUS && g_cRtMpNtMaxCpus > 0,
+                        ("IPRT: Fatal: g_cRtMpNtMaxCpus=%u, max %u [KeQueryMaximumProcessorCountEx]\n",
+                         g_cRtMpNtMaxGroups, RTCPUSET_MAX_CPUS),
+                        VERR_MP_TOO_MANY_CPUS);
+    }
+    else if (g_pfnrtKeQueryMaximumProcessorCount)
+    {
+        g_cRtMpNtMaxCpus = g_pfnrtKeQueryMaximumProcessorCount();
+        MY_CHECK_RETURN(g_cRtMpNtMaxCpus <= RTCPUSET_MAX_CPUS && g_cRtMpNtMaxCpus > 0,
+                        ("IPRT: Fatal: g_cRtMpNtMaxCpus=%u, max %u [KeQueryMaximumProcessorCount]\n",
+                         g_cRtMpNtMaxGroups, RTCPUSET_MAX_CPUS),
+                        VERR_MP_TOO_MANY_CPUS);
+    }
+    else if (g_pfnrtKeQueryActiveProcessors)
+    {
+        KAFFINITY fActiveProcessors = g_pfnrtKeQueryActiveProcessors();
+        MY_CHECK_RETURN(fActiveProcessors != 0,
+                        ("IPRT: Fatal: KeQueryActiveProcessors returned 0!\n"),
+                        VERR_INTERNAL_ERROR_2);
+        g_cRtMpNtMaxCpus = 0;
+        do
+        {
+            g_cRtMpNtMaxCpus++;
+            fActiveProcessors >>= 1;
+        } while (fActiveProcessors);
+    }
+    else
+        g_cRtMpNtMaxCpus = KeNumberProcessors;
+
+    /*
+     * Just because we're a bit paranoid about getting something wrong wrt to the
+     * kernel interfaces, we try 16 times to get the KeQueryActiveProcessorCountEx
+     * and KeQueryLogicalProcessorRelationship information to match up.
+     */
+    for (unsigned cTries = 0;; cTries++)
+    {
+        /*
+         * Get number of active CPUs.
+         */
+        if (g_pfnrtKeQueryActiveProcessorCountEx)
+        {
+            g_cRtMpNtActiveCpus = g_pfnrtKeQueryActiveProcessorCountEx(ALL_PROCESSOR_GROUPS);
+            MY_CHECK_RETURN(g_cRtMpNtActiveCpus <= g_cRtMpNtMaxCpus && g_cRtMpNtActiveCpus > 0,
+                            ("IPRT: Fatal: g_cRtMpNtMaxGroups=%u, max %u [KeQueryActiveProcessorCountEx]\n",
+                             g_cRtMpNtMaxGroups, g_cRtMpNtMaxCpus),
+                            VERR_MP_TOO_MANY_CPUS);
+        }
+        else if (g_pfnrtKeQueryActiveProcessorCount)
+        {
+            g_cRtMpNtActiveCpus = g_pfnrtKeQueryActiveProcessorCount(NULL);
+            MY_CHECK_RETURN(g_cRtMpNtActiveCpus <= g_cRtMpNtMaxCpus && g_cRtMpNtActiveCpus > 0,
+                            ("IPRT: Fatal: g_cRtMpNtMaxGroups=%u, max %u [KeQueryActiveProcessorCount]\n",
+                             g_cRtMpNtMaxGroups, g_cRtMpNtMaxCpus),
+                            VERR_MP_TOO_MANY_CPUS);
+        }
+        else
+            g_cRtMpNtActiveCpus = g_cRtMpNtMaxCpus;
+
+        /*
+         * Query the details for the groups to figure out which CPUs are online as
+         * well as the NT index limit.
+         */
+        for (unsigned i = 0; i < RT_ELEMENTS(g_aidRtMpNtByCpuSetIdx); i++)
+#ifdef IPRT_WITH_RTCPUID_AS_GROUP_AND_NUMBER
+            g_aidRtMpNtByCpuSetIdx[i] = NIL_RTCPUID;
+#else
+            g_aidRtMpNtByCpuSetIdx[i] = i < g_cRtMpNtMaxCpus ? i : NIL_RTCPUID;
+#endif
+        for (unsigned idxGroup = 0; idxGroup < RT_ELEMENTS(g_aRtMpNtCpuGroups); idxGroup++)
+        {
+            g_aRtMpNtCpuGroups[idxGroup].cMaxCpus    = 0;
+            g_aRtMpNtCpuGroups[idxGroup].cActiveCpus = 0;
+            for (unsigned idxMember = 0; idxMember < RT_ELEMENTS(g_aRtMpNtCpuGroups[idxGroup].aidxCpuSetMembers); idxMember++)
+                g_aRtMpNtCpuGroups[idxGroup].aidxCpuSetMembers[idxMember] = -1;
+        }
+
+        if (g_pfnrtKeQueryLogicalProcessorRelationship)
+        {
+            MY_CHECK_RETURN(g_pfnrtKeGetProcessorIndexFromNumber,
+                            ("IPRT: Fatal: Found KeQueryLogicalProcessorRelationship but not KeGetProcessorIndexFromNumber!\n"),
+                            VERR_SYMBOL_NOT_FOUND);
+            MY_CHECK_RETURN(g_pfnrtKeGetProcessorNumberFromIndex,
+                            ("IPRT: Fatal: Found KeQueryLogicalProcessorRelationship but not KeGetProcessorIndexFromNumber!\n"),
+                            VERR_SYMBOL_NOT_FOUND);
+            MY_CHECK_RETURN(g_pfnrtKeSetTargetProcessorDpcEx,
+                            ("IPRT: Fatal: Found KeQueryLogicalProcessorRelationship but not KeSetTargetProcessorDpcEx!\n"),
+                            VERR_SYMBOL_NOT_FOUND);
+
+            SYSTEM_LOGICAL_PROCESSOR_INFORMATION_EX *pInfo = NULL;
+            int rc = rtR0NtInitQueryGroupRelations(&pInfo);
+            if (RT_FAILURE(rc))
+                return rc;
+
+            MY_CHECK(pInfo->Group.MaximumGroupCount == g_cRtMpNtMaxGroups,
+                     ("IPRT: Fatal: MaximumGroupCount=%u != g_cRtMpNtMaxGroups=%u!\n",
+                      pInfo->Group.MaximumGroupCount, g_cRtMpNtMaxGroups));
+            MY_CHECK(pInfo->Group.ActiveGroupCount > 0 && pInfo->Group.ActiveGroupCount <= g_cRtMpNtMaxGroups,
+                     ("IPRT: Fatal: ActiveGroupCount=%u != g_cRtMpNtMaxGroups=%u!\n",
+                      pInfo->Group.ActiveGroupCount, g_cRtMpNtMaxGroups));
+
+            /*
+             * First we need to recalc g_cRtMpNtMaxCpus (see above).
+             */
+            uint32_t cMaxCpus = 0;
+            uint32_t idxGroup;
+            for (idxGroup = 0; RT_SUCCESS(rc) && idxGroup < pInfo->Group.ActiveGroupCount; idxGroup++)
+            {
+                const PROCESSOR_GROUP_INFO *pGrpInfo = &pInfo->Group.GroupInfo[idxGroup];
+                MY_CHECK_BREAK(pGrpInfo->MaximumProcessorCount <= MAXIMUM_PROC_PER_GROUP,
+                               ("IPRT: Fatal: MaximumProcessorCount=%u\n", pGrpInfo->MaximumProcessorCount));
+                MY_CHECK_BREAK(pGrpInfo->ActiveProcessorCount <= pGrpInfo->MaximumProcessorCount,
+                               ("IPRT: Fatal: ActiveProcessorCount=%u > MaximumProcessorCount=%u\n",
+                                pGrpInfo->ActiveProcessorCount, pGrpInfo->MaximumProcessorCount));
+                cMaxCpus += pGrpInfo->MaximumProcessorCount;
+            }
+            if (cMaxCpus > g_cRtMpNtMaxCpus && RT_SUCCESS(rc))
+            {
+                DbgPrint("IPRT: g_cRtMpNtMaxCpus=%u -> %u\n", g_cRtMpNtMaxCpus, cMaxCpus);
+#ifndef IPRT_WITH_RTCPUID_AS_GROUP_AND_NUMBER
+                uint32_t i = RT_MIN(cMaxCpus, RT_ELEMENTS(g_aidRtMpNtByCpuSetIdx));
+                while (i-- > g_cRtMpNtMaxCpus)
+                    g_aidRtMpNtByCpuSetIdx[i] = i;
+#endif
+                g_cRtMpNtMaxCpus = cMaxCpus;
+                if (g_cRtMpNtMaxGroups > RTCPUSET_MAX_CPUS)
+                {
+                    MY_CHECK(g_cRtMpNtMaxGroups <= RTCPUSET_MAX_CPUS && g_cRtMpNtMaxGroups > 0,
+                             ("IPRT: Fatal: g_cRtMpNtMaxGroups=%u, max %u\n", g_cRtMpNtMaxGroups, RTCPUSET_MAX_CPUS));
+                    rc = VERR_MP_TOO_MANY_CPUS;
+                }
+            }
+
+            /*
+             * Calc online mask, partition IDs and such.
+             *
+             * Also check ASSUMPTIONS:
+             *
+             *      1. Processor indexes going from 0 and up to
+             *         KeQueryMaximumProcessorCountEx(ALL_PROCESSOR_GROUPS) - 1.
+             *
+             *      2. Currently valid processor indexes, i.e. accepted by
+             *         KeGetProcessorIndexFromNumber & KeGetProcessorNumberFromIndex, goes
+             *         from 0 thru KeQueryActiveProcessorCountEx(ALL_PROCESSOR_GROUPS) - 1.
+             *
+             *      3. PROCESSOR_GROUP_INFO::MaximumProcessorCount gives the number of
+             *         relevant bits in the ActiveProcessorMask (from LSB).
+             *
+             *      4. Active processor count found in KeQueryLogicalProcessorRelationship
+             *         output matches what KeQueryActiveProcessorCountEx(ALL) returns.
+             *
+             *      5. Active + inactive processor counts in same does not exceed
+             *         KeQueryMaximumProcessorCountEx(ALL).
+             *
+             * Note! Processor indexes are assigned as CPUs come online and are not
+             *       preallocated according to group maximums.  Since CPUS are only taken
+             *       online and never offlined, this means that internal CPU bitmaps are
+             *       never sparse and no time is wasted scanning unused bits.
+             *
+             *       Unfortunately, it means that ring-3 cannot easily guess the index
+             *       assignments when hotswapping is used, and must use GIP when available.
+             */
+            RTCpuSetEmpty(&g_rtMpNtCpuSet);
+            uint32_t cInactive = 0;
+            uint32_t cActive   = 0;
+            uint32_t idxCpuMax = 0;
+            uint32_t idxCpuSetNextInactive = g_cRtMpNtMaxCpus - 1;
+            for (idxGroup = 0; RT_SUCCESS(rc) && idxGroup < pInfo->Group.ActiveGroupCount; idxGroup++)
+            {
+                const PROCESSOR_GROUP_INFO *pGrpInfo = &pInfo->Group.GroupInfo[idxGroup];
+                MY_CHECK_BREAK(pGrpInfo->MaximumProcessorCount <= MAXIMUM_PROC_PER_GROUP,
+                               ("IPRT: Fatal: MaximumProcessorCount=%u\n", pGrpInfo->MaximumProcessorCount));
+                MY_CHECK_BREAK(pGrpInfo->ActiveProcessorCount <= pGrpInfo->MaximumProcessorCount,
+                               ("IPRT: Fatal: ActiveProcessorCount=%u > MaximumProcessorCount=%u\n",
+                                pGrpInfo->ActiveProcessorCount, pGrpInfo->MaximumProcessorCount));
+
+                g_aRtMpNtCpuGroups[idxGroup].cMaxCpus    = pGrpInfo->MaximumProcessorCount;
+                g_aRtMpNtCpuGroups[idxGroup].cActiveCpus = pGrpInfo->ActiveProcessorCount;
+
+                for (uint32_t idxMember = 0; idxMember < pGrpInfo->MaximumProcessorCount; idxMember++)
+                {
+                    PROCESSOR_NUMBER ProcNum;
+                    ProcNum.Group    = (USHORT)idxGroup;
+                    ProcNum.Number   = (UCHAR)idxMember;
+                    ProcNum.Reserved = 0;
+                    ULONG idxCpu = g_pfnrtKeGetProcessorIndexFromNumber(&ProcNum);
+                    if (idxCpu != INVALID_PROCESSOR_INDEX)
+                    {
+                        MY_CHECK_BREAK(idxCpu < g_cRtMpNtMaxCpus && idxCpu < RTCPUSET_MAX_CPUS, /* ASSUMPTION #1 */
+                                       ("IPRT: Fatal: idxCpu=%u >= g_cRtMpNtMaxCpus=%u (RTCPUSET_MAX_CPUS=%u)\n",
+                                        idxCpu, g_cRtMpNtMaxCpus, RTCPUSET_MAX_CPUS));
+                        if (idxCpu > idxCpuMax)
+                            idxCpuMax = idxCpu;
+                        g_aRtMpNtCpuGroups[idxGroup].aidxCpuSetMembers[idxMember] = idxCpu;
+#ifdef IPRT_WITH_RTCPUID_AS_GROUP_AND_NUMBER
+                        g_aidRtMpNtByCpuSetIdx[idxCpu] = RTMPCPUID_FROM_GROUP_AND_NUMBER(idxGroup, idxMember);
+#endif
+
+                        ProcNum.Group    = UINT16_MAX;
+                        ProcNum.Number   = UINT8_MAX;
+                        ProcNum.Reserved = UINT8_MAX;
+                        NTSTATUS rcNt = g_pfnrtKeGetProcessorNumberFromIndex(idxCpu, &ProcNum);
+                        MY_CHECK_BREAK(NT_SUCCESS(rcNt),
+                                       ("IPRT: Fatal: KeGetProcessorNumberFromIndex(%u,) -> %#x!\n", idxCpu, rcNt));
+                        MY_CHECK_BREAK(ProcNum.Group == idxGroup && ProcNum.Number == idxMember,
+                                       ("IPRT: Fatal: KeGetProcessorXxxxFromYyyy roundtrip error for %#x! Group: %u vs %u, Number: %u vs %u\n",
+                                        idxCpu, ProcNum.Group, idxGroup, ProcNum.Number, idxMember));
+
+                        if (pGrpInfo->ActiveProcessorMask & RT_BIT_64(idxMember))
+                        {
+                            RTCpuSetAddByIndex(&g_rtMpNtCpuSet, idxCpu);
+                            cActive++;
+                        }
+                        else
+                            cInactive++; /* (This is a little unexpected, but not important as long as things add up below.) */
+                    }
+                    else
+                    {
+                        /* Must be not present / inactive when KeGetProcessorIndexFromNumber fails. */
+                        MY_CHECK_BREAK(!(pGrpInfo->ActiveProcessorMask & RT_BIT_64(idxMember)),
+                                       ("IPRT: Fatal: KeGetProcessorIndexFromNumber(%u/%u) failed but CPU is active! cMax=%u cActive=%u fActive=%p\n",
+                                        idxGroup, idxMember, pGrpInfo->MaximumProcessorCount, pGrpInfo->ActiveProcessorCount,
+                                        pGrpInfo->ActiveProcessorMask));
+                        cInactive++;
+                        if (idxCpuSetNextInactive >= g_cRtMpNtActiveCpus)
+                        {
+                            g_aRtMpNtCpuGroups[idxGroup].aidxCpuSetMembers[idxMember] = idxCpuSetNextInactive;
+#ifdef IPRT_WITH_RTCPUID_AS_GROUP_AND_NUMBER
+                            g_aidRtMpNtByCpuSetIdx[idxCpuSetNextInactive] = RTMPCPUID_FROM_GROUP_AND_NUMBER(idxGroup, idxMember)
+                                                                          | RTMPNT_ID_F_INACTIVE;
+#endif
+                            idxCpuSetNextInactive--;
+                        }
+                    }
+                }
+            }
+
+            MY_CHECK(cInactive + cActive <= g_cRtMpNtMaxCpus, /* ASSUMPTION #5 (not '==' because of inactive groups) */
+                     ("IPRT: Fatal: cInactive=%u + cActive=%u > g_cRtMpNtMaxCpus=%u\n", cInactive, cActive, g_cRtMpNtMaxCpus));
+
+            /* Deal with inactive groups using KeQueryMaximumProcessorCountEx or as
+               best as we can by as best we can by stipulating maximum member counts
+               from the previous group. */
+            if (   RT_SUCCESS(rc)
+                && idxGroup < pInfo->Group.MaximumGroupCount)
+            {
+                uint16_t cInactiveLeft = g_cRtMpNtMaxCpus - (cInactive + cActive);
+                while (idxGroup < pInfo->Group.MaximumGroupCount)
+                {
+                    uint32_t cMaxMembers = 0;
+                    if (g_pfnrtKeQueryMaximumProcessorCountEx)
+                        cMaxMembers = g_pfnrtKeQueryMaximumProcessorCountEx(idxGroup);
+                    if (cMaxMembers != 0 || cInactiveLeft == 0)
+                        AssertStmt(cMaxMembers <= cInactiveLeft, cMaxMembers = cInactiveLeft);
+                    else
+                    {
+                        uint16_t cGroupsLeft = pInfo->Group.MaximumGroupCount - idxGroup;
+                        cMaxMembers = pInfo->Group.GroupInfo[idxGroup - 1].MaximumProcessorCount;
+                        while (cMaxMembers * cGroupsLeft < cInactiveLeft)
+                            cMaxMembers++;
+                        if (cMaxMembers > cInactiveLeft)
+                            cMaxMembers = cInactiveLeft;
+                    }
+
+                    g_aRtMpNtCpuGroups[idxGroup].cMaxCpus    = (uint16_t)cMaxMembers;
+                    g_aRtMpNtCpuGroups[idxGroup].cActiveCpus = 0;
+                    for (uint16_t idxMember = 0; idxMember < cMaxMembers; idxMember++)
+                        if (idxCpuSetNextInactive >= g_cRtMpNtActiveCpus)
+                        {
+                            g_aRtMpNtCpuGroups[idxGroup].aidxCpuSetMembers[idxMember] = idxCpuSetNextInactive;
+#ifdef IPRT_WITH_RTCPUID_AS_GROUP_AND_NUMBER
+                            g_aidRtMpNtByCpuSetIdx[idxCpuSetNextInactive] = RTMPCPUID_FROM_GROUP_AND_NUMBER(idxGroup, idxMember)
+                                                                          | RTMPNT_ID_F_INACTIVE;
+#endif
+                            idxCpuSetNextInactive--;
+                        }
+                    cInactiveLeft -= cMaxMembers;
+                    idxGroup++;
+                }
+            }
+
+            /* We're done with pInfo now, free it so we can start returning when assertions fail. */
+            RTMemFree(pInfo);
+            if (RT_FAILURE(rc)) /* MY_CHECK_BREAK sets rc. */
+                return rc;
+            MY_CHECK_RETURN(cActive >= g_cRtMpNtActiveCpus,
+                            ("IPRT: Fatal: cActive=%u < g_cRtMpNtActiveCpus=%u - CPUs removed?\n", cActive, g_cRtMpNtActiveCpus),
+                            VERR_INTERNAL_ERROR_3);
+            MY_CHECK_RETURN(idxCpuMax < cActive, /* ASSUMPTION #2 */
+                            ("IPRT: Fatal: idCpuMax=%u >= cActive=%u! Unexpected CPU index allocation. CPUs removed?\n",
+                             idxCpuMax, cActive),
+                            VERR_INTERNAL_ERROR_4);
+
+            /* Retry if CPUs were added. */
+            if (   cActive != g_cRtMpNtActiveCpus
+                && cTries < 16)
+                continue;
+            MY_CHECK_RETURN(cActive == g_cRtMpNtActiveCpus, /* ASSUMPTION #4 */
+                            ("IPRT: Fatal: cActive=%u != g_cRtMpNtActiveCpus=%u\n", cActive, g_cRtMpNtActiveCpus),
+                            VERR_INTERNAL_ERROR_5);
+        }
+        else
+        {
+            /* Legacy: */
+            MY_CHECK_RETURN(g_cRtMpNtMaxGroups == 1, ("IPRT: Fatal: Missing KeQueryLogicalProcessorRelationship!\n"),
+                            VERR_SYMBOL_NOT_FOUND);
+
+            /** @todo Is it possible that the affinity mask returned by
+             *        KeQueryActiveProcessors is sparse? */
+            if (g_pfnrtKeQueryActiveProcessors)
+                RTCpuSetFromU64(&g_rtMpNtCpuSet, g_pfnrtKeQueryActiveProcessors());
+            else if (g_cRtMpNtMaxCpus < 64)
+                RTCpuSetFromU64(&g_rtMpNtCpuSet, (UINT64_C(1) << g_cRtMpNtMaxCpus) - 1);
+            else
+            {
+                MY_CHECK_RETURN(g_cRtMpNtMaxCpus == 64, ("IPRT: Fatal: g_cRtMpNtMaxCpus=%u, expect 64 or less\n", g_cRtMpNtMaxCpus),
+                                VERR_MP_TOO_MANY_CPUS);
+                RTCpuSetFromU64(&g_rtMpNtCpuSet, UINT64_MAX);
+            }
+
+            g_aRtMpNtCpuGroups[0].cMaxCpus    = g_cRtMpNtMaxCpus;
+            g_aRtMpNtCpuGroups[0].cActiveCpus = g_cRtMpNtMaxCpus;
+            for (unsigned i = 0; i < g_cRtMpNtMaxCpus; i++)
+            {
+                g_aRtMpNtCpuGroups[0].aidxCpuSetMembers[i] = i;
+#ifdef IPRT_WITH_RTCPUID_AS_GROUP_AND_NUMBER
+                g_aidRtMpNtByCpuSetIdx[i] = RTMPCPUID_FROM_GROUP_AND_NUMBER(0, i);
+#endif
+            }
+        }
+
+        /*
+         * Register CPU hot plugging callback (it also counts active CPUs).
+         */
+        Assert(g_pvMpCpuChangeCallback == NULL);
+        if (g_pfnrtKeRegisterProcessorChangeCallback)
+        {
+            MY_CHECK_RETURN(g_pfnrtKeDeregisterProcessorChangeCallback,
+                            ("IPRT: Fatal: KeRegisterProcessorChangeCallback without KeDeregisterProcessorChangeCallback!\n"),
+                            VERR_SYMBOL_NOT_FOUND);
+
+            RTCPUSET const ActiveSetCopy = g_rtMpNtCpuSet;
+            RTCpuSetEmpty(&g_rtMpNtCpuSet);
+            uint32_t const cActiveCpus   = g_cRtMpNtActiveCpus;
+            g_cRtMpNtActiveCpus = 0;
+
+            g_pvMpCpuChangeCallback = g_pfnrtKeRegisterProcessorChangeCallback(rtR0NtMpProcessorChangeCallback, NULL /*pvUser*/,
+                                                                               KE_PROCESSOR_CHANGE_ADD_EXISTING);
+            if (g_pvMpCpuChangeCallback)
+            {
+                if (cActiveCpus == g_cRtMpNtActiveCpus)
+                { /* likely */ }
+                else
+                {
+                    g_pfnrtKeDeregisterProcessorChangeCallback(g_pvMpCpuChangeCallback);
+                    if (cTries < 16)
+                    {
+                        /* Retry if CPUs were added. */
+                        MY_CHECK_RETURN(g_cRtMpNtActiveCpus >= cActiveCpus,
+                                        ("IPRT: Fatal: g_cRtMpNtActiveCpus=%u < cActiveCpus=%u! CPUs removed?\n",
+                                         g_cRtMpNtActiveCpus, cActiveCpus),
+                                        VERR_INTERNAL_ERROR_2);
+                        MY_CHECK_RETURN(g_cRtMpNtActiveCpus <= g_cRtMpNtMaxCpus,
+                                        ("IPRT: Fatal: g_cRtMpNtActiveCpus=%u > g_cRtMpNtMaxCpus=%u!\n",
+                                         g_cRtMpNtActiveCpus, g_cRtMpNtMaxCpus),
+                                        VERR_INTERNAL_ERROR_2);
+                        continue;
+                    }
+                    MY_CHECK_RETURN(0, ("IPRT: Fatal: g_cRtMpNtActiveCpus=%u cActiveCpus=%u\n", g_cRtMpNtActiveCpus, cActiveCpus),
+                                    VERR_INTERNAL_ERROR_3);
+                }
+            }
+            else
+            {
+                AssertFailed();
+                g_rtMpNtCpuSet      = ActiveSetCopy;
+                g_cRtMpNtActiveCpus = cActiveCpus;
+            }
+        }
+        break;
+    } /* Retry loop for stable active CPU count. */
+
+#undef MY_CHECK_RETURN
+
+    /*
+     * Special IPI fun for RTMpPokeCpu.
+     *
+     * On Vista and later the DPC method doesn't seem to reliably send IPIs,
+     * so we have to use alternative methods.
+     *
+     * On AMD64 We used to use the HalSendSoftwareInterrupt API (also x86 on
+     * W10+), it looks faster and more convenient to use, however we're either
+     * using it wrong or it doesn't reliably do what we want (see @bugref{8343}).
+     *
+     * The HalRequestIpip API is thus far the only alternative to KeInsertQueueDpc
+     * for doing targetted IPIs.  Trouble with this API is that it changed
+     * fundamentally in Window 7 when they added support for lots of processors.
+     *
+     * If we really think we cannot use KeInsertQueueDpc, we use the broadcast IPI
+     * API KeIpiGenericCall.
+     */
+    if (   pOsVerInfo->uMajorVer > 6
+        || (pOsVerInfo->uMajorVer == 6 && pOsVerInfo->uMinorVer > 0))
+        g_pfnrtHalRequestIpiPreW7 = NULL;
+    else
+        g_pfnrtHalRequestIpiW7Plus = NULL;
+
+    if (   g_pfnrtHalRequestIpiW7Plus
+        && g_pfnrtKeInitializeAffinityEx
+        && g_pfnrtKeAddProcessorAffinityEx
+        && g_pfnrtKeGetProcessorIndexFromNumber)
+    {
+        /* Determine the real size of the KAFFINITY_EX structure. */
+        size_t const  cbAffinity = _8K;
+        PKAFFINITY_EX pAffinity  = (PKAFFINITY_EX)RTMemAllocZ(cbAffinity);
+        AssertReturn(pAffinity, VERR_NO_MEMORY);
+        size_t const cMaxEntries = (cbAffinity - RT_UOFFSETOF(KAFFINITY_EX, Bitmap[0])) / sizeof(pAffinity->Bitmap[0]);
+        g_pfnrtKeInitializeAffinityEx(pAffinity);
+        if (pAffinity->Size > 1 && pAffinity->Size <= cMaxEntries)
+        {
+            g_cRtMpNtKaffinityExEntries = pAffinity->Size;
+            g_cbRtMpNtKaffinityEx       = pAffinity->Size * sizeof(pAffinity->Bitmap[0]) + RT_UOFFSETOF(KAFFINITY_EX, Bitmap[0]);
+            g_pfnrtMpPokeCpuWorker      = rtMpPokeCpuUsingHalRequestIpiW7Plus;
+            RTMemFree(pAffinity);
+            DbgPrint("IPRT: RTMpPoke => rtMpPokeCpuUsingHalRequestIpiW7Plus\n");
+            return VINF_SUCCESS;
+        }
+        DbgPrint("IPRT: RTMpPoke can't use rtMpPokeCpuUsingHalRequestIpiW7Plus! pAffinity->Size=%u\n", pAffinity->Size);
+        AssertReleaseMsg(pAffinity->Size <= cMaxEntries, ("%#x\n", pAffinity->Size)); /* stack is toast if larger (32768 CPUs). */
+        RTMemFree(pAffinity);
+    }
+
+    if (pOsVerInfo->uMajorVer >= 6 && g_pfnrtKeIpiGenericCall)
+    {
+        DbgPrint("IPRT: RTMpPoke => rtMpPokeCpuUsingBroadcastIpi\n");
+        g_pfnrtMpPokeCpuWorker = rtMpPokeCpuUsingBroadcastIpi;
+    }
+    else if (g_pfnrtKeSetTargetProcessorDpc)
+    {
+        DbgPrint("IPRT: RTMpPoke => rtMpPokeCpuUsingDpc\n");
+        g_pfnrtMpPokeCpuWorker = rtMpPokeCpuUsingDpc;
+        /* Windows XP should send always send an IPI -> VERIFY */
+    }
+    else
+    {
+        DbgPrint("IPRT: RTMpPoke => rtMpPokeCpuUsingFailureNotSupported\n");
+        Assert(pOsVerInfo->uMajorVer == 3 && pOsVerInfo->uMinorVer <= 50);
+        g_pfnrtMpPokeCpuWorker = rtMpPokeCpuUsingFailureNotSupported;
+    }
+
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Called by rtR0TermNative.
+ */
+DECLHIDDEN(void) rtR0MpNtTerm(void)
+{
+    /*
+     * Deregister the processor change callback.
+     */
+    PVOID pvMpCpuChangeCallback = g_pvMpCpuChangeCallback;
+    g_pvMpCpuChangeCallback = NULL;
+    if (pvMpCpuChangeCallback)
+    {
+        AssertReturnVoid(g_pfnrtKeDeregisterProcessorChangeCallback);
+        g_pfnrtKeDeregisterProcessorChangeCallback(pvMpCpuChangeCallback);
+    }
+}
+
+
+DECLHIDDEN(int) rtR0MpNotificationNativeInit(void)
+{
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(void) rtR0MpNotificationNativeTerm(void)
+{
+}
+
+
+/**
+ * Implements the NT PROCESSOR_CALLBACK_FUNCTION callback function.
+ *
+ * This maintains the g_rtMpNtCpuSet and works MP notification callbacks.  When
+ * registered, it's called for each active CPU in the system, avoiding racing
+ * CPU hotplugging (as well as testing the callback).
+ *
+ * @param   pvUser              User context (not used).
+ * @param   pChangeCtx          Change context (in).
+ * @param   prcOperationStatus  Operation status (in/out).
+ *
+ * @remarks ASSUMES no concurrent execution of KeProcessorAddCompleteNotify
+ *          notification callbacks.  At least during callback registration
+ *          callout, we're owning KiDynamicProcessorLock.
+ *
+ * @remarks When registering the handler, we first get KeProcessorAddStartNotify
+ *          callbacks for all active CPUs, and after they all succeed we get the
+ *          KeProcessorAddCompleteNotify callbacks.
+ */
+static VOID __stdcall rtR0NtMpProcessorChangeCallback(void *pvUser, PKE_PROCESSOR_CHANGE_NOTIFY_CONTEXT pChangeCtx,
+                                                      PNTSTATUS prcOperationStatus)
+{
+    RT_NOREF(pvUser, prcOperationStatus);
+    switch (pChangeCtx->State)
+    {
+        /*
+         * Check whether we can deal with the CPU, failing the start operation if we
+         * can't.  The checks we are doing here are to avoid complicated/impossible
+         * cases in KeProcessorAddCompleteNotify.  They are really just verify specs.
+         */
+        case KeProcessorAddStartNotify:
+        {
+            NTSTATUS rcNt = STATUS_SUCCESS;
+            if (pChangeCtx->NtNumber < RTCPUSET_MAX_CPUS)
+            {
+                if (pChangeCtx->NtNumber >= g_cRtMpNtMaxCpus)
+                {
+                    DbgPrint("IPRT: KeProcessorAddStartNotify failure: NtNumber=%u is higher than the max CPU count (%u)!\n",
+                             pChangeCtx->NtNumber, g_cRtMpNtMaxCpus);
+                    rcNt = STATUS_INTERNAL_ERROR;
+                }
+
+                /* The ProcessNumber field was introduced in Windows 7. */
+                PROCESSOR_NUMBER ProcNum;
+                if (g_pfnrtKeGetProcessorIndexFromNumber)
+                {
+                    ProcNum = pChangeCtx->ProcNumber;
+                    KEPROCESSORINDEX idxCpu = g_pfnrtKeGetProcessorIndexFromNumber(&ProcNum);
+                    if (idxCpu != pChangeCtx->NtNumber)
+                    {
+                        DbgPrint("IPRT: KeProcessorAddStartNotify failure: g_pfnrtKeGetProcessorIndexFromNumber(%u.%u) -> %u, expected %u!\n",
+                                 ProcNum.Group, ProcNum.Number, idxCpu, pChangeCtx->NtNumber);
+                        rcNt = STATUS_INTERNAL_ERROR;
+                    }
+                }
+                else
+                {
+                    ProcNum.Group  = 0;
+                    ProcNum.Number = pChangeCtx->NtNumber;
+                }
+
+                if (   ProcNum.Group  < RT_ELEMENTS(g_aRtMpNtCpuGroups)
+                    && ProcNum.Number < RT_ELEMENTS(g_aRtMpNtCpuGroups[0].aidxCpuSetMembers))
+                {
+                    if (ProcNum.Group >= g_cRtMpNtMaxGroups)
+                    {
+                        DbgPrint("IPRT: KeProcessorAddStartNotify failure: %u.%u is out of range - max groups: %u!\n",
+                                 ProcNum.Group, ProcNum.Number, g_cRtMpNtMaxGroups);
+                        rcNt = STATUS_INTERNAL_ERROR;
+                    }
+
+                    if (ProcNum.Number < g_aRtMpNtCpuGroups[ProcNum.Group].cMaxCpus)
+                    {
+                        Assert(g_aRtMpNtCpuGroups[ProcNum.Group].aidxCpuSetMembers[ProcNum.Number] != -1);
+                        if (g_aRtMpNtCpuGroups[ProcNum.Group].aidxCpuSetMembers[ProcNum.Number] == -1)
+                        {
+                            DbgPrint("IPRT: KeProcessorAddStartNotify failure: Internal error! %u.%u was assigned -1 as set index!\n",
+                                     ProcNum.Group, ProcNum.Number);
+                            rcNt = STATUS_INTERNAL_ERROR;
+                        }
+
+                        Assert(g_aidRtMpNtByCpuSetIdx[pChangeCtx->NtNumber] != NIL_RTCPUID);
+                        if (g_aidRtMpNtByCpuSetIdx[pChangeCtx->NtNumber] == NIL_RTCPUID)
+                        {
+                            DbgPrint("IPRT: KeProcessorAddStartNotify failure: Internal error! %u (%u.%u) translates to NIL_RTCPUID!\n",
+                                     pChangeCtx->NtNumber, ProcNum.Group, ProcNum.Number);
+                            rcNt = STATUS_INTERNAL_ERROR;
+                        }
+                    }
+                    else
+                    {
+                        DbgPrint("IPRT: KeProcessorAddStartNotify failure: max processors in group %u is %u, cannot add %u to it!\n",
+                                 ProcNum.Group, g_aRtMpNtCpuGroups[ProcNum.Group].cMaxCpus, ProcNum.Group, ProcNum.Number);
+                        rcNt = STATUS_INTERNAL_ERROR;
+                    }
+                }
+                else
+                {
+                    DbgPrint("IPRT: KeProcessorAddStartNotify failure: %u.%u is out of range (max %u.%u)!\n",
+                             ProcNum.Group, ProcNum.Number, RT_ELEMENTS(g_aRtMpNtCpuGroups), RT_ELEMENTS(g_aRtMpNtCpuGroups[0].aidxCpuSetMembers));
+                    rcNt = STATUS_INTERNAL_ERROR;
+                }
+            }
+            else
+            {
+                DbgPrint("IPRT: KeProcessorAddStartNotify failure: NtNumber=%u is outside RTCPUSET_MAX_CPUS (%u)!\n",
+                         pChangeCtx->NtNumber, RTCPUSET_MAX_CPUS);
+                rcNt = STATUS_INTERNAL_ERROR;
+            }
+            if (!NT_SUCCESS(rcNt))
+                *prcOperationStatus = rcNt;
+            break;
+        }
+
+        /*
+         * Update the globals.  Since we've checked out range limits and other
+         * limitations already we just AssertBreak here.
+         */
+        case KeProcessorAddCompleteNotify:
+        {
+            /*
+             * Calc the processor number and assert conditions checked in KeProcessorAddStartNotify.
+             */
+            AssertBreak(pChangeCtx->NtNumber < RTCPUSET_MAX_CPUS);
+            AssertBreak(pChangeCtx->NtNumber < g_cRtMpNtMaxCpus);
+            Assert(pChangeCtx->NtNumber == g_cRtMpNtActiveCpus); /* light assumption */
+            PROCESSOR_NUMBER ProcNum;
+            if (g_pfnrtKeGetProcessorIndexFromNumber)
+            {
+                ProcNum = pChangeCtx->ProcNumber;
+                AssertBreak(g_pfnrtKeGetProcessorIndexFromNumber(&ProcNum) == pChangeCtx->NtNumber);
+                AssertBreak(ProcNum.Group < RT_ELEMENTS(g_aRtMpNtCpuGroups));
+                AssertBreak(ProcNum.Group < g_cRtMpNtMaxGroups);
+            }
+            else
+            {
+                ProcNum.Group  = 0;
+                ProcNum.Number = pChangeCtx->NtNumber;
+            }
+            AssertBreak(ProcNum.Number < RT_ELEMENTS(g_aRtMpNtCpuGroups[ProcNum.Group].aidxCpuSetMembers));
+            AssertBreak(ProcNum.Number < g_aRtMpNtCpuGroups[ProcNum.Group].cMaxCpus);
+            AssertBreak(g_aRtMpNtCpuGroups[ProcNum.Group].aidxCpuSetMembers[ProcNum.Number] != -1);
+            AssertBreak(g_aidRtMpNtByCpuSetIdx[pChangeCtx->NtNumber] != NIL_RTCPUID);
+
+            /*
+             * Add ourselves to the online CPU set and update the active CPU count.
+             */
+            RTCpuSetAddByIndex(&g_rtMpNtCpuSet, pChangeCtx->NtNumber);
+            ASMAtomicIncU32(&g_cRtMpNtActiveCpus);
+
+            /*
+             * Update the group info.
+             *
+             * If the index prediction failed (real hotplugging callbacks only) we
+             * have to switch it around.  This is particularly annoying when we
+             * use the index as the ID.
+             */
+#ifdef IPRT_WITH_RTCPUID_AS_GROUP_AND_NUMBER
+            RTCPUID idCpu = RTMPCPUID_FROM_GROUP_AND_NUMBER(ProcNum.Group, ProcNum.Number);
+            RTCPUID idOld = g_aidRtMpNtByCpuSetIdx[pChangeCtx->NtNumber];
+            if ((idOld & ~RTMPNT_ID_F_INACTIVE) != idCpu)
+            {
+                Assert(idOld & RTMPNT_ID_F_INACTIVE);
+                int idxDest = g_aRtMpNtCpuGroups[ProcNum.Group].aidxCpuSetMembers[ProcNum.Number];
+                g_aRtMpNtCpuGroups[rtMpCpuIdGetGroup(idOld)].aidxCpuSetMembers[rtMpCpuIdGetGroupMember(idOld)] = idxDest;
+                g_aidRtMpNtByCpuSetIdx[idxDest] = idOld;
+            }
+            g_aidRtMpNtByCpuSetIdx[pChangeCtx->NtNumber] = idCpu;
+#else
+            Assert(g_aidRtMpNtByCpuSetIdx[pChangeCtx->NtNumber] == pChangeCtx->NtNumber);
+            int idxDest = g_aRtMpNtCpuGroups[ProcNum.Group].aidxCpuSetMembers[ProcNum.Number];
+            if ((ULONG)idxDest != pChangeCtx->NtNumber)
+            {
+                bool     fFound = false;
+                uint32_t idxOldGroup = g_cRtMpNtMaxGroups;
+                while (idxOldGroup-- > 0 && !fFound)
+                {
+                    uint32_t idxMember = g_aRtMpNtCpuGroups[idxOldGroup].cMaxCpus;
+                    while (idxMember-- > 0)
+                        if (g_aRtMpNtCpuGroups[idxOldGroup].aidxCpuSetMembers[idxMember] == (int)pChangeCtx->NtNumber)
+                        {
+                            g_aRtMpNtCpuGroups[idxOldGroup].aidxCpuSetMembers[idxMember] = idxDest;
+                            fFound = true;
+                            break;
+                        }
+                }
+                Assert(fFound);
+            }
+#endif
+            g_aRtMpNtCpuGroups[ProcNum.Group].aidxCpuSetMembers[ProcNum.Number] = pChangeCtx->NtNumber;
+
+            /*
+             * Do MP notification callbacks.
+             */
+            rtMpNotificationDoCallbacks(RTMPEVENT_ONLINE, pChangeCtx->NtNumber);
+            break;
+        }
+
+        case KeProcessorAddFailureNotify:
+            /* ignore */
+            break;
+
+        default:
+            AssertMsgFailed(("State=%u\n", pChangeCtx->State));
+    }
+}
+
+
+/**
+ * Wrapper around KeQueryLogicalProcessorRelationship.
+ *
+ * @returns IPRT status code.
+ * @param   ppInfo  Where to return the info. Pass to RTMemFree when done.
+ */
+static int rtR0NtInitQueryGroupRelations(SYSTEM_LOGICAL_PROCESSOR_INFORMATION_EX **ppInfo)
+{
+    ULONG    cbInfo = sizeof(SYSTEM_LOGICAL_PROCESSOR_INFORMATION_EX)
+                    + g_cRtMpNtMaxGroups * sizeof(GROUP_RELATIONSHIP);
+    NTSTATUS rcNt;
+    do
+    {
+        SYSTEM_LOGICAL_PROCESSOR_INFORMATION_EX *pInfo = (SYSTEM_LOGICAL_PROCESSOR_INFORMATION_EX *)RTMemAlloc(cbInfo);
+        if (pInfo)
+        {
+            rcNt = g_pfnrtKeQueryLogicalProcessorRelationship(NULL /*pProcNumber*/, RelationGroup, pInfo, &cbInfo);
+            if (NT_SUCCESS(rcNt))
+            {
+                *ppInfo = pInfo;
+                return VINF_SUCCESS;
+            }
+
+            RTMemFree(pInfo);
+            pInfo = NULL;
+        }
+        else
+            rcNt = STATUS_NO_MEMORY;
+    } while (rcNt == STATUS_INFO_LENGTH_MISMATCH);
+    DbgPrint("IPRT: Fatal: KeQueryLogicalProcessorRelationship failed: %#x\n", rcNt);
+    AssertMsgFailed(("KeQueryLogicalProcessorRelationship failed: %#x\n", rcNt));
+    return RTErrConvertFromNtStatus(rcNt);
+}
+
+
+
+
+
+RTDECL(RTCPUID) RTMpCpuId(void)
+{
+    Assert(g_cRtMpNtMaxCpus > 0 && g_cRtMpNtMaxGroups > 0); /* init order */
+
+#ifdef IPRT_WITH_RTCPUID_AS_GROUP_AND_NUMBER
+    PROCESSOR_NUMBER ProcNum;
+    ProcNum.Group = 0;
+    if (g_pfnrtKeGetCurrentProcessorNumberEx)
+    {
+        ProcNum.Number = 0;
+        g_pfnrtKeGetCurrentProcessorNumberEx(&ProcNum);
+    }
+    else
+        ProcNum.Number = KeGetCurrentProcessorNumber(); /* Number is 8-bit, so we're not subject to BYTE -> WORD upgrade in WDK.  */
+    return RTMPCPUID_FROM_GROUP_AND_NUMBER(ProcNum.Group, ProcNum.Number);
+
+#else
+
+    if (g_pfnrtKeGetCurrentProcessorNumberEx)
+    {
+        KEPROCESSORINDEX idxCpu = g_pfnrtKeGetCurrentProcessorNumberEx(NULL);
+        Assert(idxCpu < RTCPUSET_MAX_CPUS);
+        return idxCpu;
+    }
+
+    return (uint8_t)KeGetCurrentProcessorNumber(); /* PCR->Number was changed from BYTE to WORD in the WDK, thus the cast. */
+#endif
+}
+
+
+RTDECL(int) RTMpCurSetIndex(void)
+{
+#ifdef IPRT_WITH_RTCPUID_AS_GROUP_AND_NUMBER
+    Assert(g_cRtMpNtMaxCpus > 0 && g_cRtMpNtMaxGroups > 0); /* init order */
+
+    if (g_pfnrtKeGetCurrentProcessorNumberEx)
+    {
+        KEPROCESSORINDEX idxCpu = g_pfnrtKeGetCurrentProcessorNumberEx(NULL);
+        Assert(idxCpu < RTCPUSET_MAX_CPUS);
+        return idxCpu;
+    }
+    return (uint8_t)KeGetCurrentProcessorNumber(); /* PCR->Number was changed from BYTE to WORD in the WDK, thus the cast. */
+#else
+    return (int)RTMpCpuId();
+#endif
+}
+
+
+RTDECL(int) RTMpCurSetIndexAndId(PRTCPUID pidCpu)
+{
+#ifdef IPRT_WITH_RTCPUID_AS_GROUP_AND_NUMBER
+    Assert(g_cRtMpNtMaxCpus > 0 && g_cRtMpNtMaxGroups > 0); /* init order */
+
+    PROCESSOR_NUMBER ProcNum = { 0 , 0,  0 };
+    KEPROCESSORINDEX idxCpu = g_pfnrtKeGetCurrentProcessorNumberEx(&ProcNum);
+    Assert(idxCpu < RTCPUSET_MAX_CPUS);
+    *pidCpu = RTMPCPUID_FROM_GROUP_AND_NUMBER(ProcNum.Group, ProcNum.Number);
+    return idxCpu;
+#else
+    return *pidCpu = RTMpCpuId();
+#endif
+}
+
+
+RTDECL(int) RTMpCpuIdToSetIndex(RTCPUID idCpu)
+{
+#ifdef IPRT_WITH_RTCPUID_AS_GROUP_AND_NUMBER
+    Assert(g_cRtMpNtMaxCpus > 0 && g_cRtMpNtMaxGroups > 0); /* init order */
+
+    if (idCpu != NIL_RTCPUID)
+    {
+        if (g_pfnrtKeGetProcessorIndexFromNumber)
+        {
+            PROCESSOR_NUMBER ProcNum;
+            ProcNum.Group    = rtMpCpuIdGetGroup(idCpu);
+            ProcNum.Number   = rtMpCpuIdGetGroupMember(idCpu);
+            ProcNum.Reserved = 0;
+            KEPROCESSORINDEX idxCpu = g_pfnrtKeGetProcessorIndexFromNumber(&ProcNum);
+            if (idxCpu != INVALID_PROCESSOR_INDEX)
+            {
+                Assert(idxCpu < g_cRtMpNtMaxCpus);
+                Assert((ULONG)g_aRtMpNtCpuGroups[ProcNum.Group].aidxCpuSetMembers[ProcNum.Number] == idxCpu);
+                return idxCpu;
+            }
+
+            /* Since NT assigned indexes as the CPUs come online, we cannot produce an ID <-> index
+               mapping for not-yet-onlined CPUS that is consistent.  We just have to do our best... */
+            if (   ProcNum.Group < g_cRtMpNtMaxGroups
+                && ProcNum.Number < g_aRtMpNtCpuGroups[ProcNum.Group].cMaxCpus)
+                return g_aRtMpNtCpuGroups[ProcNum.Group].aidxCpuSetMembers[ProcNum.Number];
+        }
+        else if (rtMpCpuIdGetGroup(idCpu) == 0)
+            return rtMpCpuIdGetGroupMember(idCpu);
+    }
+    return -1;
+#else
+    /* 1:1 mapping, just do range checks. */
+    return idCpu < RTCPUSET_MAX_CPUS ? (int)idCpu : -1;
+#endif
+}
+
+
+RTDECL(RTCPUID) RTMpCpuIdFromSetIndex(int iCpu)
+{
+#ifdef IPRT_WITH_RTCPUID_AS_GROUP_AND_NUMBER
+    Assert(g_cRtMpNtMaxCpus > 0 && g_cRtMpNtMaxGroups > 0); /* init order */
+
+    if ((unsigned)iCpu < g_cRtMpNtMaxCpus)
+    {
+        if (g_pfnrtKeGetProcessorIndexFromNumber)
+        {
+            PROCESSOR_NUMBER ProcNum = { 0, 0, 0 };
+            NTSTATUS rcNt = g_pfnrtKeGetProcessorNumberFromIndex(iCpu, &ProcNum);
+            if (NT_SUCCESS(rcNt))
+            {
+                Assert(ProcNum.Group <= g_cRtMpNtMaxGroups);
+                Assert(   (g_aidRtMpNtByCpuSetIdx[iCpu] & ~RTMPNT_ID_F_INACTIVE)
+                       == RTMPCPUID_FROM_GROUP_AND_NUMBER(ProcNum.Group, ProcNum.Number));
+                return RTMPCPUID_FROM_GROUP_AND_NUMBER(ProcNum.Group, ProcNum.Number);
+            }
+        }
+        return g_aidRtMpNtByCpuSetIdx[iCpu];
+    }
+    return NIL_RTCPUID;
+#else
+    /* 1:1 mapping, just do range checks. */
+    return (unsigned)iCpu < RTCPUSET_MAX_CPUS ? iCpu : NIL_RTCPUID;
+#endif
+}
+
+
+RTDECL(int) RTMpSetIndexFromCpuGroupMember(uint32_t idxGroup, uint32_t idxMember)
+{
+    Assert(g_cRtMpNtMaxCpus > 0 && g_cRtMpNtMaxGroups > 0); /* init order */
+
+    if (idxGroup < g_cRtMpNtMaxGroups)
+        if (idxMember < g_aRtMpNtCpuGroups[idxGroup].cMaxCpus)
+            return g_aRtMpNtCpuGroups[idxGroup].aidxCpuSetMembers[idxMember];
+    return -1;
+}
+
+
+RTDECL(uint32_t) RTMpGetCpuGroupCounts(uint32_t idxGroup, uint32_t *pcActive)
+{
+    if (idxGroup < g_cRtMpNtMaxGroups)
+    {
+        if (pcActive)
+            *pcActive = g_aRtMpNtCpuGroups[idxGroup].cActiveCpus;
+        return g_aRtMpNtCpuGroups[idxGroup].cMaxCpus;
+    }
+    if (pcActive)
+        *pcActive = 0;
+    return 0;
+}
+
+
+RTDECL(uint32_t) RTMpGetMaxCpuGroupCount(void)
+{
+    return g_cRtMpNtMaxGroups;
+}
+
+
+RTDECL(RTCPUID) RTMpGetMaxCpuId(void)
+{
+    Assert(g_cRtMpNtMaxCpus > 0 && g_cRtMpNtMaxGroups > 0); /* init order */
+
+#ifdef IPRT_WITH_RTCPUID_AS_GROUP_AND_NUMBER
+    return RTMPCPUID_FROM_GROUP_AND_NUMBER(g_cRtMpNtMaxGroups - 1, g_aRtMpNtCpuGroups[g_cRtMpNtMaxGroups - 1].cMaxCpus - 1);
+#else
+    /* According to MSDN the processor indexes goes from 0 to the maximum
+       number of CPUs in the system.  We've check this in initterm-r0drv-nt.cpp. */
+    return g_cRtMpNtMaxCpus - 1;
+#endif
+}
+
+
+RTDECL(bool) RTMpIsCpuOnline(RTCPUID idCpu)
+{
+    Assert(g_cRtMpNtMaxCpus > 0 && g_cRtMpNtMaxGroups > 0); /* init order */
+    return RTCpuSetIsMember(&g_rtMpNtCpuSet, idCpu);
+}
+
+
+RTDECL(bool) RTMpIsCpuPossible(RTCPUID idCpu)
+{
+    Assert(g_cRtMpNtMaxCpus > 0 && g_cRtMpNtMaxGroups > 0); /* init order */
+
+#ifdef IPRT_WITH_RTCPUID_AS_GROUP_AND_NUMBER
+    if (idCpu != NIL_RTCPUID)
+    {
+        unsigned idxGroup = rtMpCpuIdGetGroup(idCpu);
+        if (idxGroup < g_cRtMpNtMaxGroups)
+            return rtMpCpuIdGetGroupMember(idCpu) < g_aRtMpNtCpuGroups[idxGroup].cMaxCpus;
+    }
+    return false;
+
+#else
+    /* A possible CPU ID is one with a value lower than g_cRtMpNtMaxCpus (see
+       comment in RTMpGetMaxCpuId). */
+    return idCpu < g_cRtMpNtMaxCpus;
+#endif
+}
+
+
+
+RTDECL(PRTCPUSET) RTMpGetSet(PRTCPUSET pSet)
+{
+    Assert(g_cRtMpNtMaxCpus > 0 && g_cRtMpNtMaxGroups > 0); /* init order */
+
+    /* The set of possible CPU IDs(/indexes) are from 0 up to
+       g_cRtMpNtMaxCpus (see comment in RTMpGetMaxCpuId). */
+    RTCpuSetEmpty(pSet);
+    int idxCpu = g_cRtMpNtMaxCpus;
+    while (idxCpu-- > 0)
+        RTCpuSetAddByIndex(pSet, idxCpu);
+    return pSet;
+}
+
+
+RTDECL(RTCPUID) RTMpGetCount(void)
+{
+    Assert(g_cRtMpNtMaxCpus > 0 && g_cRtMpNtMaxGroups > 0); /* init order */
+    return g_cRtMpNtMaxCpus;
+}
+
+
+RTDECL(PRTCPUSET) RTMpGetOnlineSet(PRTCPUSET pSet)
+{
+    Assert(g_cRtMpNtMaxCpus > 0 && g_cRtMpNtMaxGroups > 0); /* init order */
+
+    *pSet = g_rtMpNtCpuSet;
+    return pSet;
+}
+
+
+RTDECL(RTCPUID) RTMpGetOnlineCount(void)
+{
+    RTCPUSET Set;
+    RTMpGetOnlineSet(&Set);
+    return RTCpuSetCount(&Set);
+}
+
+
+RTDECL(RTCPUID) RTMpGetOnlineCoreCount(void)
+{
+    /** @todo fix me */
+    return RTMpGetOnlineCount();
+}
+
+
+
+#if 0
+/* Experiment with checking the undocumented KPRCB structure
+ * 'dt nt!_kprcb 0xaddress' shows the layout
+ */
+typedef struct
+{
+    LIST_ENTRY     DpcListHead;
+    ULONG_PTR      DpcLock;
+    volatile ULONG DpcQueueDepth;
+    ULONG          DpcQueueCount;
+} KDPC_DATA, *PKDPC_DATA;
+
+RTDECL(bool) RTMpIsCpuWorkPending(void)
+{
+    uint8_t *pkprcb;
+    PKDPC_DATA pDpcData;
+
+    _asm {
+        mov eax, fs:0x20
+        mov pkprcb, eax
+    }
+    pDpcData = (PKDPC_DATA)(pkprcb + 0x19e0);
+    if (pDpcData->DpcQueueDepth)
+        return true;
+
+    pDpcData++;
+    if (pDpcData->DpcQueueDepth)
+        return true;
+    return false;
+}
+#else
+RTDECL(bool) RTMpIsCpuWorkPending(void)
+{
+    /** @todo not implemented */
+    return false;
+}
+#endif
+
+
+/**
+ * Wrapper between the native KIPI_BROADCAST_WORKER and IPRT's PFNRTMPWORKER for
+ * the RTMpOnAll case.
+ *
+ * @param   uUserCtx            The user context argument (PRTMPARGS).
+ */
+static ULONG_PTR rtmpNtOnAllBroadcastIpiWrapper(ULONG_PTR uUserCtx)
+{
+    PRTMPARGS pArgs = (PRTMPARGS)uUserCtx;
+    /*ASMAtomicIncU32(&pArgs->cHits); - not needed */
+    pArgs->pfnWorker(RTMpCpuId(), pArgs->pvUser1, pArgs->pvUser2);
+    return 0;
+}
+
+
+/**
+ * Wrapper between the native KIPI_BROADCAST_WORKER and IPRT's PFNRTMPWORKER for
+ * the RTMpOnOthers case.
+ *
+ * @param   uUserCtx            The user context argument (PRTMPARGS).
+ */
+static ULONG_PTR rtmpNtOnOthersBroadcastIpiWrapper(ULONG_PTR uUserCtx)
+{
+    PRTMPARGS pArgs = (PRTMPARGS)uUserCtx;
+    RTCPUID idCpu = RTMpCpuId();
+    if (pArgs->idCpu != idCpu)
+    {
+        /*ASMAtomicIncU32(&pArgs->cHits); - not needed */
+        pArgs->pfnWorker(idCpu, pArgs->pvUser1, pArgs->pvUser2);
+    }
+    return 0;
+}
+
+
+/**
+ * Wrapper between the native KIPI_BROADCAST_WORKER and IPRT's PFNRTMPWORKER for
+ * the RTMpOnPair case.
+ *
+ * @param   uUserCtx            The user context argument (PRTMPARGS).
+ */
+static ULONG_PTR rtmpNtOnPairBroadcastIpiWrapper(ULONG_PTR uUserCtx)
+{
+    PRTMPARGS pArgs = (PRTMPARGS)uUserCtx;
+    RTCPUID idCpu = RTMpCpuId();
+    if (   pArgs->idCpu  == idCpu
+        || pArgs->idCpu2 == idCpu)
+    {
+        ASMAtomicIncU32(&pArgs->cHits);
+        pArgs->pfnWorker(idCpu, pArgs->pvUser1, pArgs->pvUser2);
+    }
+    return 0;
+}
+
+
+/**
+ * Wrapper between the native KIPI_BROADCAST_WORKER and IPRT's PFNRTMPWORKER for
+ * the RTMpOnSpecific case.
+ *
+ * @param   uUserCtx            The user context argument (PRTMPARGS).
+ */
+static ULONG_PTR rtmpNtOnSpecificBroadcastIpiWrapper(ULONG_PTR uUserCtx)
+{
+    PRTMPARGS pArgs = (PRTMPARGS)uUserCtx;
+    RTCPUID idCpu = RTMpCpuId();
+    if (pArgs->idCpu == idCpu)
+    {
+        ASMAtomicIncU32(&pArgs->cHits);
+        pArgs->pfnWorker(idCpu, pArgs->pvUser1, pArgs->pvUser2);
+    }
+    return 0;
+}
+
+
+/**
+ * Internal worker for the RTMpOn* APIs using KeIpiGenericCall.
+ *
+ * @returns VINF_SUCCESS.
+ * @param   pfnWorker           The callback.
+ * @param   pvUser1             User argument 1.
+ * @param   pvUser2             User argument 2.
+ * @param   pfnNativeWrapper    The wrapper between the NT and IPRT callbacks.
+ * @param   idCpu               First CPU to match, ultimately specific to the
+ *                              pfnNativeWrapper used.
+ * @param   idCpu2              Second CPU to match, ultimately specific to the
+ *                              pfnNativeWrapper used.
+ * @param   pcHits              Where to return the number of this. Optional.
+ */
+static int rtMpCallUsingBroadcastIpi(PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2,
+                                     PKIPI_BROADCAST_WORKER pfnNativeWrapper, RTCPUID idCpu, RTCPUID idCpu2,
+                                     uint32_t *pcHits)
+{
+    RTMPARGS Args;
+    Args.pfnWorker = pfnWorker;
+    Args.pvUser1   = pvUser1;
+    Args.pvUser2   = pvUser2;
+    Args.idCpu     = idCpu;
+    Args.idCpu2    = idCpu2;
+    Args.cRefs     = 0;
+    Args.cHits     = 0;
+
+    AssertPtr(g_pfnrtKeIpiGenericCall);
+    g_pfnrtKeIpiGenericCall(pfnNativeWrapper, (uintptr_t)&Args);
+    if (pcHits)
+        *pcHits = Args.cHits;
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Wrapper between the native nt per-cpu callbacks and PFNRTWORKER
+ *
+ * @param   Dpc                 DPC object
+ * @param   DeferredContext     Context argument specified by KeInitializeDpc
+ * @param   SystemArgument1     Argument specified by KeInsertQueueDpc
+ * @param   SystemArgument2     Argument specified by KeInsertQueueDpc
+ */
+static VOID rtmpNtDPCWrapper(IN PKDPC Dpc, IN PVOID DeferredContext, IN PVOID SystemArgument1, IN PVOID SystemArgument2)
+{
+    PRTMPARGS pArgs = (PRTMPARGS)DeferredContext;
+    RT_NOREF3(Dpc, SystemArgument1, SystemArgument2);
+
+    ASMAtomicIncU32(&pArgs->cHits);
+    pArgs->pfnWorker(RTMpCpuId(), pArgs->pvUser1, pArgs->pvUser2);
+
+    /* Dereference the argument structure. */
+    int32_t cRefs = ASMAtomicDecS32(&pArgs->cRefs);
+    Assert(cRefs >= 0);
+    if (cRefs == 0)
+        RTMemFree(pArgs);
+}
+
+
+/**
+ * Wrapper around KeSetTargetProcessorDpcEx / KeSetTargetProcessorDpc.
+ *
+ * This is shared with the timer code.
+ *
+ * @returns IPRT status code (errors are asserted).
+ * @param   pDpc                The DPC.
+ * @param   idCpu               The ID of the new target CPU.
+ */
+DECLHIDDEN(int) rtMpNtSetTargetProcessorDpc(KDPC *pDpc, RTCPUID idCpu)
+{
+    if (g_pfnrtKeSetTargetProcessorDpcEx)
+    {
+        /* Convert to stupid process number (bet KeSetTargetProcessorDpcEx does
+           the reverse conversion internally). */
+        PROCESSOR_NUMBER ProcNum;
+        NTSTATUS rcNt = g_pfnrtKeGetProcessorNumberFromIndex(RTMpCpuIdToSetIndex(idCpu), &ProcNum);
+        AssertMsgReturn(NT_SUCCESS(rcNt),
+                        ("KeGetProcessorNumberFromIndex(%u) -> %#x\n", idCpu, rcNt),
+                        RTErrConvertFromNtStatus(rcNt));
+
+        rcNt = g_pfnrtKeSetTargetProcessorDpcEx(pDpc, &ProcNum);
+        AssertMsgReturn(NT_SUCCESS(rcNt),
+                        ("KeSetTargetProcessorDpcEx(,%u(%u/%u)) -> %#x\n", idCpu, ProcNum.Group, ProcNum.Number, rcNt),
+                        RTErrConvertFromNtStatus(rcNt));
+    }
+    else if (g_pfnrtKeSetTargetProcessorDpc)
+        g_pfnrtKeSetTargetProcessorDpc(pDpc, RTMpCpuIdToSetIndex(idCpu));
+    else
+        return VERR_NOT_SUPPORTED;
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Internal worker for the RTMpOn* APIs.
+ *
+ * @returns IPRT status code.
+ * @param   pfnWorker   The callback.
+ * @param   pvUser1     User argument 1.
+ * @param   pvUser2     User argument 2.
+ * @param   enmCpuid    What to do / is idCpu valid.
+ * @param   idCpu       Used if enmCpuid is RT_NT_CPUID_SPECIFIC or
+ *                      RT_NT_CPUID_PAIR, otherwise ignored.
+ * @param   idCpu2      Used if enmCpuid is RT_NT_CPUID_PAIR, otherwise ignored.
+ * @param   pcHits      Where to return the number of this. Optional.
+ */
+static int rtMpCallUsingDpcs(PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2,
+                             RT_NT_CPUID enmCpuid, RTCPUID idCpu, RTCPUID idCpu2, uint32_t *pcHits)
+{
+#if 0
+    /* KeFlushQueuedDpcs must be run at IRQL PASSIVE_LEVEL according to MSDN, but the
+     * driver verifier doesn't complain...
+     */
+    AssertMsg(KeGetCurrentIrql() == PASSIVE_LEVEL, ("%d != %d (PASSIVE_LEVEL)\n", KeGetCurrentIrql(), PASSIVE_LEVEL));
+#endif
+    /* KeFlushQueuedDpcs is not present in Windows 2000; import it dynamically so we can just fail this call. */
+    if (!g_pfnrtNtKeFlushQueuedDpcs)
+        return VERR_NOT_SUPPORTED;
+
+    /*
+     * Make a copy of the active CPU set and figure out how many KDPCs we really need.
+     * We must not try setup DPCs for CPUs which aren't there, because that may fail.
+     */
+    RTCPUSET  OnlineSet = g_rtMpNtCpuSet;
+    uint32_t  cDpcsNeeded;
+    switch (enmCpuid)
+    {
+        case RT_NT_CPUID_SPECIFIC:
+            cDpcsNeeded = 1;
+            break;
+        case RT_NT_CPUID_PAIR:
+            cDpcsNeeded = 2;
+            break;
+        default:
+            do
+            {
+                cDpcsNeeded = g_cRtMpNtActiveCpus;
+                OnlineSet   = g_rtMpNtCpuSet;
+            } while (cDpcsNeeded != g_cRtMpNtActiveCpus);
+            break;
+    }
+
+    /*
+     * Allocate an RTMPARGS structure followed by cDpcsNeeded KDPCs
+     * and initialize them.
+     */
+    PRTMPARGS pArgs = (PRTMPARGS)RTMemAllocZ(sizeof(RTMPARGS) + cDpcsNeeded * sizeof(KDPC));
+    if (!pArgs)
+        return VERR_NO_MEMORY;
+
+    pArgs->pfnWorker = pfnWorker;
+    pArgs->pvUser1   = pvUser1;
+    pArgs->pvUser2   = pvUser2;
+    pArgs->idCpu     = NIL_RTCPUID;
+    pArgs->idCpu2    = NIL_RTCPUID;
+    pArgs->cHits     = 0;
+    pArgs->cRefs     = 1;
+
+    int rc;
+    KDPC *paExecCpuDpcs = (KDPC *)(pArgs + 1);
+    if (enmCpuid == RT_NT_CPUID_SPECIFIC)
+    {
+        KeInitializeDpc(&paExecCpuDpcs[0], rtmpNtDPCWrapper, pArgs);
+        if (g_pfnrtKeSetImportanceDpc)
+            g_pfnrtKeSetImportanceDpc(&paExecCpuDpcs[0], HighImportance);
+        rc = rtMpNtSetTargetProcessorDpc(&paExecCpuDpcs[0], idCpu);
+        pArgs->idCpu = idCpu;
+    }
+    else if (enmCpuid == RT_NT_CPUID_PAIR)
+    {
+        KeInitializeDpc(&paExecCpuDpcs[0], rtmpNtDPCWrapper, pArgs);
+        if (g_pfnrtKeSetImportanceDpc)
+            g_pfnrtKeSetImportanceDpc(&paExecCpuDpcs[0], HighImportance);
+        rc = rtMpNtSetTargetProcessorDpc(&paExecCpuDpcs[0], idCpu);
+        pArgs->idCpu = idCpu;
+
+        KeInitializeDpc(&paExecCpuDpcs[1], rtmpNtDPCWrapper, pArgs);
+        if (g_pfnrtKeSetImportanceDpc)
+            g_pfnrtKeSetImportanceDpc(&paExecCpuDpcs[1], HighImportance);
+        if (RT_SUCCESS(rc))
+            rc = rtMpNtSetTargetProcessorDpc(&paExecCpuDpcs[1], (int)idCpu2);
+        pArgs->idCpu2 = idCpu2;
+    }
+    else
+    {
+        rc = VINF_SUCCESS;
+        for (uint32_t i = 0; i < cDpcsNeeded && RT_SUCCESS(rc); i++)
+            if (RTCpuSetIsMemberByIndex(&OnlineSet, i))
+            {
+                KeInitializeDpc(&paExecCpuDpcs[i], rtmpNtDPCWrapper, pArgs);
+                if (g_pfnrtKeSetImportanceDpc)
+                    g_pfnrtKeSetImportanceDpc(&paExecCpuDpcs[i], HighImportance);
+                rc = rtMpNtSetTargetProcessorDpc(&paExecCpuDpcs[i], RTMpCpuIdFromSetIndex(i));
+            }
+    }
+    if (RT_FAILURE(rc))
+    {
+        RTMemFree(pArgs);
+        return rc;
+    }
+
+    /*
+     * Raise the IRQL to DISPATCH_LEVEL so we can't be rescheduled to another cpu.
+     * KeInsertQueueDpc must also be executed at IRQL >= DISPATCH_LEVEL.
+     */
+    KIRQL oldIrql;
+    KeRaiseIrql(DISPATCH_LEVEL, &oldIrql);
+
+    /*
+     * We cannot do other than assume a 1:1 relationship between the
+     * affinity mask and the process despite the warnings in the docs.
+     * If someone knows a better way to get this done, please let bird know.
+     */
+    ASMCompilerBarrier(); /* paranoia */
+    if (enmCpuid == RT_NT_CPUID_SPECIFIC)
+    {
+        ASMAtomicIncS32(&pArgs->cRefs);
+        BOOLEAN fRc = KeInsertQueueDpc(&paExecCpuDpcs[0], 0, 0);
+        Assert(fRc); NOREF(fRc);
+    }
+    else if (enmCpuid == RT_NT_CPUID_PAIR)
+    {
+        ASMAtomicIncS32(&pArgs->cRefs);
+        BOOLEAN fRc = KeInsertQueueDpc(&paExecCpuDpcs[0], 0, 0);
+        Assert(fRc); NOREF(fRc);
+
+        ASMAtomicIncS32(&pArgs->cRefs);
+        fRc = KeInsertQueueDpc(&paExecCpuDpcs[1], 0, 0);
+        Assert(fRc); NOREF(fRc);
+    }
+    else
+    {
+        uint32_t iSelf = RTMpCurSetIndex();
+        for (uint32_t i = 0; i < cDpcsNeeded; i++)
+        {
+            if (   (i != iSelf)
+                && RTCpuSetIsMemberByIndex(&OnlineSet, i))
+            {
+                ASMAtomicIncS32(&pArgs->cRefs);
+                BOOLEAN fRc = KeInsertQueueDpc(&paExecCpuDpcs[i], 0, 0);
+                Assert(fRc); NOREF(fRc);
+            }
+        }
+        if (enmCpuid != RT_NT_CPUID_OTHERS)
+            pfnWorker(iSelf, pvUser1, pvUser2);
+    }
+
+    KeLowerIrql(oldIrql);
+
+    /*
+     * Flush all DPCs and wait for completion. (can take long!)
+     */
+    /** @todo Consider changing this to an active wait using some atomic inc/dec
+     *  stuff (and check for the current cpu above in the specific case). */
+    /** @todo Seems KeFlushQueuedDpcs doesn't wait for the DPCs to be completely
+     *        executed. Seen pArgs being freed while some CPU was using it before
+     *        cRefs was added. */
+    if (g_pfnrtNtKeFlushQueuedDpcs)
+        g_pfnrtNtKeFlushQueuedDpcs();
+
+    if (pcHits)
+        *pcHits = pArgs->cHits;
+
+    /* Dereference the argument structure. */
+    int32_t cRefs = ASMAtomicDecS32(&pArgs->cRefs);
+    Assert(cRefs >= 0);
+    if (cRefs == 0)
+        RTMemFree(pArgs);
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTMpOnAll(PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    if (g_pfnrtKeIpiGenericCall)
+        return rtMpCallUsingBroadcastIpi(pfnWorker, pvUser1, pvUser2, rtmpNtOnAllBroadcastIpiWrapper,
+                                         NIL_RTCPUID, NIL_RTCPUID, NULL);
+    return rtMpCallUsingDpcs(pfnWorker, pvUser1, pvUser2, RT_NT_CPUID_ALL, NIL_RTCPUID, NIL_RTCPUID, NULL);
+}
+
+
+RTDECL(int) RTMpOnOthers(PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    if (g_pfnrtKeIpiGenericCall)
+        return rtMpCallUsingBroadcastIpi(pfnWorker, pvUser1, pvUser2, rtmpNtOnOthersBroadcastIpiWrapper,
+                                         NIL_RTCPUID, NIL_RTCPUID, NULL);
+    return rtMpCallUsingDpcs(pfnWorker, pvUser1, pvUser2, RT_NT_CPUID_OTHERS, NIL_RTCPUID, NIL_RTCPUID, NULL);
+}
+
+
+RTDECL(int) RTMpOnPair(RTCPUID idCpu1, RTCPUID idCpu2, uint32_t fFlags, PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    int rc;
+    AssertReturn(idCpu1 != idCpu2, VERR_INVALID_PARAMETER);
+    AssertReturn(!(fFlags & RTMPON_F_VALID_MASK), VERR_INVALID_FLAGS);
+    if ((fFlags & RTMPON_F_CONCURRENT_EXEC) && !g_pfnrtKeIpiGenericCall)
+        return VERR_NOT_SUPPORTED;
+
+    /*
+     * Check that both CPUs are online before doing the broadcast call.
+     */
+    if (   RTMpIsCpuOnline(idCpu1)
+        && RTMpIsCpuOnline(idCpu2))
+    {
+        /*
+         * The broadcast IPI isn't quite as bad as it could have been, because
+         * it looks like windows doesn't synchronize CPUs on the way out, they
+         * seems to get back to normal work while the pair is still busy.
+         */
+        uint32_t cHits = 0;
+        if (g_pfnrtKeIpiGenericCall)
+            rc = rtMpCallUsingBroadcastIpi(pfnWorker, pvUser1, pvUser2, rtmpNtOnPairBroadcastIpiWrapper, idCpu1, idCpu2, &cHits);
+        else
+            rc = rtMpCallUsingDpcs(pfnWorker, pvUser1, pvUser2, RT_NT_CPUID_PAIR, idCpu1, idCpu2, &cHits);
+        if (RT_SUCCESS(rc))
+        {
+            Assert(cHits <= 2);
+            if (cHits == 2)
+                rc = VINF_SUCCESS;
+            else if (cHits == 1)
+                rc = VERR_NOT_ALL_CPUS_SHOWED;
+            else if (cHits == 0)
+                rc = VERR_CPU_OFFLINE;
+            else
+                rc = VERR_CPU_IPE_1;
+        }
+    }
+    /*
+     * A CPU must be present to be considered just offline.
+     */
+    else if (   RTMpIsCpuPresent(idCpu1)
+             && RTMpIsCpuPresent(idCpu2))
+        rc = VERR_CPU_OFFLINE;
+    else
+        rc = VERR_CPU_NOT_FOUND;
+    return rc;
+}
+
+
+RTDECL(bool) RTMpOnPairIsConcurrentExecSupported(void)
+{
+    return g_pfnrtKeIpiGenericCall != NULL;
+}
+
+
+/**
+ * Releases a reference to a RTMPNTONSPECIFICARGS heap allocation, freeing it
+ * when the last reference is released.
+ */
+DECLINLINE(void) rtMpNtOnSpecificRelease(PRTMPNTONSPECIFICARGS pArgs)
+{
+    uint32_t cRefs = ASMAtomicDecU32(&pArgs->cRefs);
+    AssertMsg(cRefs <= 1, ("cRefs=%#x\n", cRefs));
+    if (cRefs == 0)
+        RTMemFree(pArgs);
+}
+
+
+/**
+ * Wrapper between the native nt per-cpu callbacks and PFNRTWORKER
+ *
+ * @param   Dpc                 DPC object
+ * @param   DeferredContext     Context argument specified by KeInitializeDpc
+ * @param   SystemArgument1     Argument specified by KeInsertQueueDpc
+ * @param   SystemArgument2     Argument specified by KeInsertQueueDpc
+ */
+static VOID rtMpNtOnSpecificDpcWrapper(IN PKDPC Dpc, IN PVOID DeferredContext,
+                                       IN PVOID SystemArgument1, IN PVOID SystemArgument2)
+{
+    PRTMPNTONSPECIFICARGS pArgs = (PRTMPNTONSPECIFICARGS)DeferredContext;
+    RT_NOREF3(Dpc, SystemArgument1, SystemArgument2);
+
+    ASMAtomicWriteBool(&pArgs->fExecuting, true);
+
+    pArgs->CallbackArgs.pfnWorker(RTMpCpuId(), pArgs->CallbackArgs.pvUser1, pArgs->CallbackArgs.pvUser2);
+
+    ASMAtomicWriteBool(&pArgs->fDone, true);
+    KeSetEvent(&pArgs->DoneEvt, 1 /*PriorityIncrement*/, FALSE /*Wait*/);
+
+    rtMpNtOnSpecificRelease(pArgs);
+}
+
+
+RTDECL(int) RTMpOnSpecific(RTCPUID idCpu, PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    /*
+     * Don't try mess with an offline CPU.
+     */
+    if (!RTMpIsCpuOnline(idCpu))
+        return !RTMpIsCpuPossible(idCpu)
+              ? VERR_CPU_NOT_FOUND
+              : VERR_CPU_OFFLINE;
+
+    /*
+     * Use the broadcast IPI routine if there are no more than two CPUs online,
+     * or if the current IRQL is unsuitable for KeWaitForSingleObject.
+     */
+    int rc;
+    uint32_t cHits = 0;
+    if (   g_pfnrtKeIpiGenericCall
+        && (   RTMpGetOnlineCount() <= 2
+            || KeGetCurrentIrql()   > APC_LEVEL)
+       )
+    {
+        rc = rtMpCallUsingBroadcastIpi(pfnWorker, pvUser1, pvUser2, rtmpNtOnSpecificBroadcastIpiWrapper,
+                                       idCpu, NIL_RTCPUID, &cHits);
+        if (RT_SUCCESS(rc))
+        {
+            if (cHits == 1)
+                return VINF_SUCCESS;
+            rc = cHits == 0 ? VERR_CPU_OFFLINE : VERR_CPU_IPE_1;
+        }
+        return rc;
+    }
+
+#if 0
+    rc = rtMpCallUsingDpcs(pfnWorker, pvUser1, pvUser2, RT_NT_CPUID_SPECIFIC, idCpu, NIL_RTCPUID, &cHits);
+    if (RT_SUCCESS(rc))
+    {
+        if (cHits == 1)
+            return VINF_SUCCESS;
+        rc = cHits == 0 ? VERR_CPU_OFFLINE : VERR_CPU_IPE_1;
+    }
+    return rc;
+
+#else
+    /*
+     * Initialize the argument package and the objects within it.
+     * The package is referenced counted to avoid unnecessary spinning to
+     * synchronize cleanup and prevent stack corruption.
+     */
+    PRTMPNTONSPECIFICARGS pArgs = (PRTMPNTONSPECIFICARGS)RTMemAllocZ(sizeof(*pArgs));
+    if (!pArgs)
+        return VERR_NO_MEMORY;
+    pArgs->cRefs                  = 2;
+    pArgs->fExecuting             = false;
+    pArgs->fDone                  = false;
+    pArgs->CallbackArgs.pfnWorker = pfnWorker;
+    pArgs->CallbackArgs.pvUser1   = pvUser1;
+    pArgs->CallbackArgs.pvUser2   = pvUser2;
+    pArgs->CallbackArgs.idCpu     = idCpu;
+    pArgs->CallbackArgs.cHits     = 0;
+    pArgs->CallbackArgs.cRefs     = 2;
+    KeInitializeEvent(&pArgs->DoneEvt, SynchronizationEvent, FALSE /* not signalled */);
+    KeInitializeDpc(&pArgs->Dpc, rtMpNtOnSpecificDpcWrapper, pArgs);
+    if (g_pfnrtKeSetImportanceDpc)
+        g_pfnrtKeSetImportanceDpc(&pArgs->Dpc, HighImportance);
+    rc = rtMpNtSetTargetProcessorDpc(&pArgs->Dpc, idCpu);
+    if (RT_FAILURE(rc))
+    {
+        RTMemFree(pArgs);
+        return rc;
+    }
+
+    /*
+     * Disable preemption while we check the current processor and inserts the DPC.
+     */
+    KIRQL bOldIrql;
+    KeRaiseIrql(DISPATCH_LEVEL, &bOldIrql);
+    ASMCompilerBarrier(); /* paranoia */
+
+    if (RTMpCpuId() == idCpu)
+    {
+        /* Just execute the callback on the current CPU. */
+        pfnWorker(idCpu, pvUser1, pvUser2);
+        KeLowerIrql(bOldIrql);
+
+        RTMemFree(pArgs);
+        return VINF_SUCCESS;
+    }
+
+    /* Different CPU, so queue it if the CPU is still online. */
+    if (RTMpIsCpuOnline(idCpu))
+    {
+        BOOLEAN fRc = KeInsertQueueDpc(&pArgs->Dpc, 0, 0);
+        Assert(fRc); NOREF(fRc);
+        KeLowerIrql(bOldIrql);
+
+        uint64_t const nsRealWaitTS = RTTimeNanoTS();
+
+        /*
+         * Wait actively for a while in case the CPU/thread responds quickly.
+         */
+        uint32_t cLoopsLeft = 0x20000;
+        while (cLoopsLeft-- > 0)
+        {
+            if (pArgs->fDone)
+            {
+                rtMpNtOnSpecificRelease(pArgs);
+                return VINF_SUCCESS;
+            }
+            ASMNopPause();
+        }
+
+        /*
+         * It didn't respond, so wait on the event object, poking the CPU if it's slow.
+         */
+        LARGE_INTEGER Timeout;
+        Timeout.QuadPart = -10000; /* 1ms */
+        NTSTATUS rcNt = KeWaitForSingleObject(&pArgs->DoneEvt, Executive, KernelMode, FALSE /* Alertable */, &Timeout);
+        if (rcNt == STATUS_SUCCESS)
+        {
+            rtMpNtOnSpecificRelease(pArgs);
+            return VINF_SUCCESS;
+        }
+
+        /* If it hasn't respondend yet, maybe poke it and wait some more. */
+        if (rcNt == STATUS_TIMEOUT)
+        {
+            if (   !pArgs->fExecuting
+                && (   g_pfnrtMpPokeCpuWorker == rtMpPokeCpuUsingHalRequestIpiW7Plus
+                    || g_pfnrtMpPokeCpuWorker == rtMpPokeCpuUsingHalRequestIpiPreW7))
+                RTMpPokeCpu(idCpu);
+
+            Timeout.QuadPart = -1280000; /* 128ms */
+            rcNt = KeWaitForSingleObject(&pArgs->DoneEvt, Executive, KernelMode, FALSE /* Alertable */, &Timeout);
+            if (rcNt == STATUS_SUCCESS)
+            {
+                rtMpNtOnSpecificRelease(pArgs);
+                return VINF_SUCCESS;
+            }
+        }
+
+        /*
+         * Something weird is happening, try bail out.
+         */
+        if (KeRemoveQueueDpc(&pArgs->Dpc))
+        {
+            RTMemFree(pArgs); /* DPC was still queued, so we can return without further ado. */
+            LogRel(("RTMpOnSpecific(%#x): Not processed after %llu ns: rcNt=%#x\n", idCpu, RTTimeNanoTS() - nsRealWaitTS, rcNt));
+        }
+        else
+        {
+            /* DPC is running, wait a good while for it to complete. */
+            LogRel(("RTMpOnSpecific(%#x): Still running after %llu ns: rcNt=%#x\n", idCpu, RTTimeNanoTS() - nsRealWaitTS, rcNt));
+
+            Timeout.QuadPart = -30*1000*1000*10; /* 30 seconds */
+            rcNt = KeWaitForSingleObject(&pArgs->DoneEvt, Executive, KernelMode, FALSE /* Alertable */, &Timeout);
+            if (rcNt != STATUS_SUCCESS)
+                LogRel(("RTMpOnSpecific(%#x): Giving up on running worker after %llu ns: rcNt=%#x\n", idCpu, RTTimeNanoTS() - nsRealWaitTS, rcNt));
+        }
+        rc = RTErrConvertFromNtStatus(rcNt);
+    }
+    else
+    {
+        /* CPU is offline.*/
+        KeLowerIrql(bOldIrql);
+        rc = !RTMpIsCpuPossible(idCpu) ? VERR_CPU_NOT_FOUND : VERR_CPU_OFFLINE;
+    }
+
+    rtMpNtOnSpecificRelease(pArgs);
+    return rc;
+#endif
+}
+
+
+
+
+static VOID rtMpNtPokeCpuDummy(IN PKDPC Dpc, IN PVOID DeferredContext, IN PVOID SystemArgument1, IN PVOID SystemArgument2)
+{
+    NOREF(Dpc);
+    NOREF(DeferredContext);
+    NOREF(SystemArgument1);
+    NOREF(SystemArgument2);
+}
+
+
+/** Callback used by rtMpPokeCpuUsingBroadcastIpi. */
+static ULONG_PTR rtMpIpiGenericCall(ULONG_PTR Argument)
+{
+    NOREF(Argument);
+    return 0;
+}
+
+
+/**
+ * RTMpPokeCpu worker that uses broadcast IPIs for doing the work.
+ *
+ * @returns VINF_SUCCESS
+ * @param   idCpu           The CPU identifier.
+ */
+int rtMpPokeCpuUsingBroadcastIpi(RTCPUID idCpu)
+{
+    NOREF(idCpu);
+    g_pfnrtKeIpiGenericCall(rtMpIpiGenericCall, 0);
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * RTMpPokeCpu worker that uses the Windows 7 and later version of
+ * HalRequestIpip to get the job done.
+ *
+ * @returns VINF_SUCCESS
+ * @param   idCpu           The CPU identifier.
+ */
+int rtMpPokeCpuUsingHalRequestIpiW7Plus(RTCPUID idCpu)
+{
+    /* idCpu is an HAL processor index, so we can use it directly. */
+    PKAFFINITY_EX pTarget = (PKAFFINITY_EX)alloca(g_cbRtMpNtKaffinityEx);
+    pTarget->Size = g_cRtMpNtKaffinityExEntries; /* (just in case KeInitializeAffinityEx starts using it) */
+    g_pfnrtKeInitializeAffinityEx(pTarget);
+    g_pfnrtKeAddProcessorAffinityEx(pTarget, idCpu);
+
+    g_pfnrtHalRequestIpiW7Plus(0, pTarget);
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * RTMpPokeCpu worker that uses the Vista and earlier version of HalRequestIpip
+ * to get the job done.
+ *
+ * @returns VINF_SUCCESS
+ * @param   idCpu           The CPU identifier.
+ */
+int rtMpPokeCpuUsingHalRequestIpiPreW7(RTCPUID idCpu)
+{
+    __debugbreak(); /** @todo this code needs testing!!  */
+    KAFFINITY Target = 1;
+    Target <<= idCpu;
+    g_pfnrtHalRequestIpiPreW7(Target);
+    return VINF_SUCCESS;
+}
+
+
+int rtMpPokeCpuUsingFailureNotSupported(RTCPUID idCpu)
+{
+    NOREF(idCpu);
+    return VERR_NOT_SUPPORTED;
+}
+
+
+int rtMpPokeCpuUsingDpc(RTCPUID idCpu)
+{
+    Assert(g_cRtMpNtMaxCpus > 0 && g_cRtMpNtMaxGroups > 0); /* init order */
+
+    /*
+     * APC fallback.
+     */
+    static KDPC s_aPokeDpcs[RTCPUSET_MAX_CPUS] = {0};
+    static bool s_fPokeDPCsInitialized = false;
+
+    if (!s_fPokeDPCsInitialized)
+    {
+        for (unsigned i = 0; i < g_cRtMpNtMaxCpus; i++)
+        {
+            KeInitializeDpc(&s_aPokeDpcs[i], rtMpNtPokeCpuDummy, NULL);
+            if (g_pfnrtKeSetImportanceDpc)
+                g_pfnrtKeSetImportanceDpc(&s_aPokeDpcs[i], HighImportance);
+            int rc = rtMpNtSetTargetProcessorDpc(&s_aPokeDpcs[i], idCpu);
+            if (RT_FAILURE(rc))
+                return rc;
+        }
+
+        s_fPokeDPCsInitialized = true;
+    }
+
+    /* Raise the IRQL to DISPATCH_LEVEL so we can't be rescheduled to another cpu.
+       KeInsertQueueDpc must also be executed at IRQL >= DISPATCH_LEVEL. */
+    KIRQL oldIrql;
+    KeRaiseIrql(DISPATCH_LEVEL, &oldIrql);
+
+    if (g_pfnrtKeSetImportanceDpc)
+        g_pfnrtKeSetImportanceDpc(&s_aPokeDpcs[idCpu], HighImportance);
+    g_pfnrtKeSetTargetProcessorDpc(&s_aPokeDpcs[idCpu], (int)idCpu);
+
+    /* Assuming here that high importance DPCs will be delivered immediately; or at least an IPI will be sent immediately.
+       Note! Not true on at least Vista & Windows 7 */
+    BOOLEAN fRet = KeInsertQueueDpc(&s_aPokeDpcs[idCpu], 0, 0);
+
+    KeLowerIrql(oldIrql);
+    return fRet == TRUE ? VINF_SUCCESS : VERR_ACCESS_DENIED /* already queued */;
+}
+
+
+RTDECL(int) RTMpPokeCpu(RTCPUID idCpu)
+{
+    if (!RTMpIsCpuOnline(idCpu))
+        return !RTMpIsCpuPossible(idCpu)
+              ? VERR_CPU_NOT_FOUND
+              : VERR_CPU_OFFLINE;
+    /* Calls rtMpPokeCpuUsingDpc, rtMpPokeCpuUsingHalRequestIpiW7Plus or rtMpPokeCpuUsingBroadcastIpi. */
+    return g_pfnrtMpPokeCpuWorker(idCpu);
+}
+
+
+RTDECL(bool) RTMpOnAllIsConcurrentSafe(void)
+{
+    return false;
+}
+
diff --git a/src/VBox/Runtime/r0drv/nt/nt3fakes-r0drv-nt.cpp b/src/VBox/Runtime/r0drv/nt/nt3fakes-r0drv-nt.cpp
new file mode 100644
index 00000000..ae41f9a3
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/nt3fakes-r0drv-nt.cpp
@@ -0,0 +1,813 @@
+/* $Id: nt3fakes-r0drv-nt.cpp $ */
+/** @file
+ * IPRT - NT 3.x fakes for NT 4.0 KPIs.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define _IMAGE_NT_HEADERS           RT_CONCAT(_IMAGE_NT_HEADERS,ARCH_BITS)
+#include "the-nt-kernel.h"
+#include <iprt/mem.h>
+
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+#include <iprt/ctype.h>
+#include <iprt/dbg.h>
+#include <iprt/err.h>
+#include <iprt/log.h>
+#include <iprt/string.h>
+#include <iprt/utf16.h>
+#include <iprt/x86.h>
+#include <iprt/formats/mz.h>
+#include <iprt/formats/pecoff.h>
+#include "internal-r0drv-nt.h"
+
+typedef uint32_t DWORD;
+#include <VerRsrc.h>
+
+
+/*********************************************************************************************************************************
+*   Internal Functions                                                                                                           *
+*********************************************************************************************************************************/
+DECLASM(void) rtNt3InitSymbolsAssembly(void); /* in nt3fakesA-r0drv-nt.asm */
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+static uint32_t         g_uNt3MajorVer  = 3;
+static uint32_t         g_uNt3MinorVer  = 51;
+static uint32_t         g_uNt3BuildNo   = 1057;
+static bool             g_fNt3Checked   = false;
+static bool             g_fNt3Smp       = false; /**< Not reliable. */
+static bool volatile    g_fNt3VersionInitialized = false;
+
+static uint8_t         *g_pbNt3OsKrnl   = (uint8_t *)UINT32_C(0x80100000);
+static uint32_t         g_cbNt3OsKrnl   = 0x300000;
+static uint8_t         *g_pbNt3Hal      = (uint8_t *)UINT32_C(0x80400000);
+static uint32_t         g_cbNt3Hal      = _512K;
+static bool volatile    g_fNt3ModuleInfoInitialized = false;
+
+
+RT_C_DECLS_BEGIN
+/** @name KPIs we provide fallback implementations for.
+ *
+ * The assembly init routine will point the __imp_xxx variable to the NT
+ * implementation if available, using the fallback if not.
+ * @{  */
+decltype(PsGetVersion)                     *g_pfnrtPsGetVersion;
+decltype(ZwQuerySystemInformation)         *g_pfnrtZwQuerySystemInformation;
+decltype(KeSetTimerEx)                     *g_pfnrtKeSetTimerEx;
+decltype(IoAttachDeviceToDeviceStack)      *g_pfnrtIoAttachDeviceToDeviceStack;
+decltype(PsGetCurrentProcessId)            *g_pfnrtPsGetCurrentProcessId;
+decltype(ZwYieldExecution)                 *g_pfnrtZwYieldExecution;
+decltype(ExAcquireFastMutex)               *g_pfnrtExAcquireFastMutex;
+decltype(ExReleaseFastMutex)               *g_pfnrtExReleaseFastMutex;
+/** @} */
+
+/** @name Fastcall optimizations not present in NT 3.1.
+ *
+ * We try resolve both the stdcall and fastcall variants and patch it up in
+ * assembly. The last four routines are in the hal.
+ *
+ * @{  */
+decltype(IofCompleteRequest)               *g_pfnrtIofCompleteRequest;
+decltype(ObfDereferenceObject)             *g_pfnrtObfDereferenceObject;
+decltype(IofCallDriver)                    *g_pfnrtIofCallDriver;
+decltype(KfAcquireSpinLock)                *g_pfnrtKfAcquireSpinLock;
+decltype(KfReleaseSpinLock)                *g_pfnrtKfReleaseSpinLock;
+decltype(KefAcquireSpinLockAtDpcLevel)     *g_pfnrtKefAcquireSpinLockAtDpcLevel;
+decltype(KefReleaseSpinLockFromDpcLevel)   *g_pfnrtKefReleaseSpinLockFromDpcLevel;
+decltype(KfLowerIrql)                      *g_pfnrtKfLowerIrql;
+decltype(KfRaiseIrql)                      *g_pfnrtKfRaiseIrql;
+
+VOID                            (__stdcall *g_pfnrtIoCompleteRequest)(PIRP, CCHAR);
+LONG_PTR                        (__stdcall *g_pfnrtObDereferenceObject)(PVOID);
+NTSTATUS                        (__stdcall *g_pfnrtIoCallDriver)(PDEVICE_OBJECT, PIRP);
+KIRQL                           (__stdcall *g_pfnrtKeAcquireSpinLock)(PKSPIN_LOCK);
+VOID                            (__stdcall *g_pfnrtKeReleaseSpinLock)(PKSPIN_LOCK, KIRQL);
+KIRQL                           (__stdcall *g_pfnrtKeAcquireSpinLockAtDpcLevel)(PKSPIN_LOCK);
+VOID                            (__stdcall *g_pfnrtKeReleaseSpinLockFromDpcLevel)(PKSPIN_LOCK);
+VOID                            (__stdcall *g_pfnrtKeLowerIrql)(KIRQL);
+KIRQL                           (__stdcall *g_pfnrtKeRaiseIrql)(KIRQL);
+/** @} */
+
+/** @name DATA exports and associated stuff
+ * @{ */
+/** Import address table entry for KeTickCount (defined in asm). */
+extern KSYSTEM_TIME                        *_imp__KeTickCount;
+/** @} */
+
+RT_C_DECLS_END
+
+
+/*********************************************************************************************************************************
+*   Internal Functions                                                                                                           *
+*********************************************************************************************************************************/
+static void rtR0Nt3InitModuleInfo(void);
+
+
+/**
+ * Converts a string to a number, stopping at the first non-digit.
+ *
+ * @returns The value
+ * @param   ppwcValue       Pointer to the string pointer variable.  Updated.
+ * @param   pcwcValue       Pointer to the string length variable.  Updated.
+ */
+static uint32_t rtR0Nt3StringToNum(PCRTUTF16 *ppwcValue, size_t *pcwcValue)
+{
+    uint32_t  uValue   = 0;
+    PCRTUTF16 pwcValue = *ppwcValue;
+    size_t    cwcValue = *pcwcValue;
+
+    while (cwcValue > 0)
+    {
+        RTUTF16 uc = *pwcValue;
+        unsigned uDigit = (unsigned)uc - (unsigned)'0';
+        if (uDigit < (unsigned)10)
+        {
+            uValue *= 10;
+            uValue += uDigit;
+        }
+        else
+            break;
+        pwcValue++;
+        cwcValue--;
+    }
+
+    *ppwcValue = pwcValue;
+    *pcwcValue = cwcValue;
+    return uValue;
+}
+
+
+/**
+ * Implements RTL_QUERY_REGISTRY_ROUTINE for processing
+ * 'HKLM/Software/Microsoft/Window NT/CurrentVersion/CurrentVersion'
+ */
+static NTSTATUS NTAPI rtR0Nt3VerEnumCallback_CurrentVersion(PWSTR pwszValueName, ULONG uValueType,
+                                                            PVOID pvValue, ULONG cbValue, PVOID pvUser, PVOID pvEntryCtx)
+{
+    RT_NOREF(pwszValueName, pvEntryCtx);
+    if (   uValueType == REG_SZ
+        || uValueType == REG_EXPAND_SZ)
+    {
+        PCRTUTF16 pwcValue = (PCRTUTF16)pvValue;
+        size_t    cwcValue  = cbValue / sizeof(*pwcValue);
+        uint32_t uMajor = rtR0Nt3StringToNum(&pwcValue, &cwcValue);
+        uint32_t uMinor = 0;
+        if (cwcValue > 1)
+        {
+            pwcValue++;
+            cwcValue--;
+            uMinor = rtR0Nt3StringToNum(&pwcValue, &cwcValue);
+        }
+
+        if (uMajor >= 3)
+        {
+            g_uNt3MajorVer = uMajor;
+            g_uNt3MinorVer = uMinor;
+            RTLogBackdoorPrintf("rtR0Nt3VerEnumCallback_CurrentVersion found: uMajor=%u uMinor=%u\n", uMajor, uMinor);
+            *(uint32_t *)pvUser |= RT_BIT_32(0);
+            return STATUS_SUCCESS;
+        }
+
+        RTLogBackdoorPrintf("rtR0Nt3VerEnumCallback_CurrentVersion: '%.*ls'\n", cbValue / sizeof(RTUTF16), pvValue);
+    }
+    else
+        RTLogBackdoorPrintf("rtR0Nt3VerEnumCallback_CurrentVersion: uValueType=%u %.*Rhxs\n", uValueType, cbValue, pvValue);
+    return STATUS_SUCCESS;
+}
+
+
+/**
+ * Implements RTL_QUERY_REGISTRY_ROUTINE for processing
+ * 'HKLM/Software/Microsoft/Window NT/CurrentVersion/CurrentBuildNumber'
+ */
+static NTSTATUS NTAPI rtR0Nt3VerEnumCallback_CurrentBuildNumber(PWSTR pwszValueName, ULONG uValueType,
+                                                                PVOID pvValue, ULONG cbValue, PVOID pvUser, PVOID pvEntryCtx)
+{
+    RT_NOREF(pwszValueName, pvEntryCtx);
+    if (   uValueType == REG_SZ
+        || uValueType == REG_EXPAND_SZ)
+    {
+        PCRTUTF16 pwcValue = (PCRTUTF16)pvValue;
+        size_t    cwcValue  = cbValue / sizeof(*pwcValue);
+        uint32_t uBuildNo = rtR0Nt3StringToNum(&pwcValue, &cwcValue);
+
+        if (uBuildNo >= 100 && uBuildNo < _1M)
+        {
+            g_uNt3BuildNo = uBuildNo;
+            RTLogBackdoorPrintf("rtR0Nt3VerEnumCallback_CurrentBuildNumber found: uBuildNo=%u\n", uBuildNo);
+            *(uint32_t *)pvUser |= RT_BIT_32(1);
+            return STATUS_SUCCESS;
+        }
+
+        RTLogBackdoorPrintf("rtR0Nt3VerEnumCallback_CurrentBuildNumber: '%.*ls'\n", cbValue / sizeof(RTUTF16), pvValue);
+    }
+    else
+        RTLogBackdoorPrintf("rtR0Nt3VerEnumCallback_CurrentBuildNumber: uValueType=%u %.*Rhxs\n", uValueType, cbValue, pvValue);
+    return STATUS_SUCCESS;
+}
+
+
+/**
+ * Implements RTL_QUERY_REGISTRY_ROUTINE for processing
+ * 'HKLM/Software/Microsoft/Window NT/CurrentVersion/CurrentType'
+ */
+static NTSTATUS NTAPI rtR0Nt3VerEnumCallback_CurrentType(PWSTR pwszValueName, ULONG uValueType,
+                                                         PVOID pvValue, ULONG cbValue, PVOID pvUser, PVOID pvEntryCtx)
+{
+    RT_NOREF(pwszValueName, pvEntryCtx);
+    if (   uValueType == REG_SZ
+        || uValueType == REG_EXPAND_SZ)
+    {
+        PCRTUTF16 pwcValue = (PCRTUTF16)pvValue;
+        size_t    cwcValue = cbValue / sizeof(*pwcValue);
+
+        int fSmp = -1;
+        if (cwcValue >= 12 && RTUtf16NICmpAscii(pwcValue, "Uniprocessor", 12) == 0)
+        {
+            cwcValue -= 12;
+            pwcValue += 12;
+            fSmp = 0;
+        }
+        else if (cwcValue >= 14 && RTUtf16NICmpAscii(pwcValue, "Multiprocessor", 14) == 0)
+        {
+            cwcValue -= 14;
+            pwcValue += 14;
+            fSmp = 1;
+        }
+        if (fSmp != -1)
+        {
+            while (cwcValue > 0 && RT_C_IS_SPACE(*pwcValue))
+                cwcValue--, pwcValue++;
+
+            int fChecked = -1;
+            if (cwcValue >= 4 && RTUtf16NICmpAscii(pwcValue, "Free", 4) == 0)
+                fChecked = 0;
+            else if (cwcValue >= 7 && RTUtf16NICmpAscii(pwcValue, "Checked", 7) == 0)
+                fChecked = 1;
+            if (fChecked != -1)
+            {
+                g_fNt3Smp     = fSmp     != 0;
+                g_fNt3Checked = fChecked != 0;
+                RTLogBackdoorPrintf("rtR0Nt3VerEnumCallback_CurrentType found: fSmp=%d fChecked=%d\n", fSmp, fChecked);
+                *(uint32_t *)pvUser |= RT_BIT_32(2);
+                return STATUS_SUCCESS;
+            }
+        }
+
+        RTLogBackdoorPrintf("rtR0Nt3VerEnumCallback_CurrentType: '%.*ls'\n", cbValue / sizeof(RTUTF16), pvValue);
+    }
+    else
+        RTLogBackdoorPrintf("rtR0Nt3VerEnumCallback_CurrentType: uValueType=%u %.*Rhxs\n", uValueType, cbValue, pvValue);
+    return STATUS_SUCCESS;
+}
+
+
+/**
+ * Figure out the NT 3 version from the registry.
+ *
+ * @note this will be called before the rtR0Nt3InitSymbols is called.
+ */
+static void rtR0Nt3InitVersion(void)
+{
+    /*
+     * No PsGetVersion, so try the registry.  Unfortunately not necessarily
+     * initialized when we're loaded.
+     */
+    RTL_QUERY_REGISTRY_TABLE aQuery[4];
+    RT_ZERO(aQuery);
+    aQuery[0].QueryRoutine = rtR0Nt3VerEnumCallback_CurrentVersion;
+    aQuery[0].Flags        = 0;
+    aQuery[0].Name         = L"CurrentVersion";
+    aQuery[0].EntryContext = NULL;
+    aQuery[0].DefaultType  = REG_NONE;
+
+    aQuery[1].QueryRoutine = rtR0Nt3VerEnumCallback_CurrentBuildNumber;
+    aQuery[1].Flags        = 0;
+    aQuery[1].Name         = L"CurrentBuildNumber";
+    aQuery[1].EntryContext = NULL;
+    aQuery[1].DefaultType  = REG_NONE;
+
+    aQuery[2].QueryRoutine = rtR0Nt3VerEnumCallback_CurrentType;
+    aQuery[2].Flags        = 0;
+    aQuery[2].Name         = L"CurrentType";
+    aQuery[2].EntryContext = NULL;
+    aQuery[2].DefaultType  = REG_NONE;
+
+    uint32_t fFound = 0;
+    //NTSTATUS rcNt = RtlQueryRegistryValues(RTL_REGISTRY_WINDOWS_NT, NULL, &aQuery[0], &fFound, NULL /*Environment*/);
+    NTSTATUS rcNt = RtlQueryRegistryValues(RTL_REGISTRY_ABSOLUTE,
+                                           L"\\Registry\\Machine\\Software\\Microsoft\\Windows NT\\CurrentVersion",
+                                           &aQuery[0], &fFound, NULL /*Environment*/);
+    if (!NT_SUCCESS(rcNt))
+        RTLogBackdoorPrintf("rtR0Nt3InitVersion: RtlQueryRegistryValues failed: %#x\n", rcNt);
+    else
+        RTLogBackdoorPrintf("rtR0Nt3InitVersion: Didn't get all values: fFound=%#x\n", fFound);
+
+    /*
+     * We really need the version number.  Build, type and SMP is off less importance.
+     * Derive it from the NT kernel PE header.
+     */
+    if (!(fFound & RT_BIT_32(0)))
+    {
+        if (!g_fNt3ModuleInfoInitialized)
+            rtR0Nt3InitModuleInfo();
+
+        PIMAGE_DOS_HEADER   pMzHdr  = (PIMAGE_DOS_HEADER)g_pbNt3OsKrnl;
+        PIMAGE_NT_HEADERS32 pNtHdrs = (PIMAGE_NT_HEADERS32)&g_pbNt3OsKrnl[pMzHdr->e_lfanew];
+        if (pNtHdrs->OptionalHeader.MajorOperatingSystemVersion == 1)
+        {
+            /* NT 3.1 and NT 3.50 both set OS version to 1.0 in the optional header. */
+            g_uNt3MajorVer = 3;
+            if (   pNtHdrs->OptionalHeader.MajorLinkerVersion == 2
+                && pNtHdrs->OptionalHeader.MinorLinkerVersion < 50)
+                g_uNt3MinorVer = 10;
+            else
+                g_uNt3MinorVer = 50;
+        }
+        else
+        {
+            g_uNt3MajorVer = pNtHdrs->OptionalHeader.MajorOperatingSystemVersion;
+            g_uNt3MinorVer = pNtHdrs->OptionalHeader.MinorOperatingSystemVersion;
+        }
+        RTLogBackdoorPrintf("rtR0Nt3InitVersion: guessed %u.%u from PE header\n", g_uNt3MajorVer, g_uNt3MinorVer);
+
+        /* Check out the resource section, looking for VS_FIXEDFILEINFO. */
+        __try /* (pointless) */
+        {
+            PIMAGE_SECTION_HEADER paShdrs = (PIMAGE_SECTION_HEADER)(pNtHdrs + 1);
+            uint32_t const        cShdrs  = pNtHdrs->FileHeader.NumberOfSections;
+            uint32_t              iShdr   = 0;
+            while (iShdr < cShdrs && memcmp(paShdrs[iShdr].Name, ".rsrc", 6) != 0)
+                iShdr++;
+            if (iShdr < cShdrs)
+            {
+                if (   paShdrs[iShdr].VirtualAddress > 0
+                    && paShdrs[iShdr].VirtualAddress < pNtHdrs->OptionalHeader.SizeOfImage)
+                {
+                    uint32_t const  cbRsrc   = RT_MIN(paShdrs[iShdr].Misc.VirtualSize
+                                                      ? paShdrs[iShdr].Misc.VirtualSize : paShdrs[iShdr].SizeOfRawData,
+                                                      pNtHdrs->OptionalHeader.SizeOfImage - paShdrs[iShdr].VirtualAddress);
+                    uint8_t const  *pbRsrc   = &g_pbNt3OsKrnl[paShdrs[iShdr].VirtualAddress];
+                    uint32_t const *puDwords = (uint32_t const *)pbRsrc;
+                    uint32_t        cDWords  = (cbRsrc - sizeof(VS_FIXEDFILEINFO) + sizeof(uint32_t)) / sizeof(uint32_t);
+                    while (cDWords-- > 0)
+                    {
+                        if (   puDwords[0] == VS_FFI_SIGNATURE
+                            && puDwords[1] == VS_FFI_STRUCVERSION)
+                        {
+                            VS_FIXEDFILEINFO const *pVerInfo = (VS_FIXEDFILEINFO const *)puDwords;
+                            g_uNt3MajorVer = pVerInfo->dwProductVersionMS >> 16;
+                            g_uNt3MinorVer = pVerInfo->dwProductVersionMS >> 16;
+                            g_uNt3BuildNo  = pVerInfo->dwProductVersionLS >> 16;
+                            RTLogBackdoorPrintf("rtR0Nt3InitVersion: Found version info %u.%u build %u\n",
+                                                g_uNt3MajorVer, g_uNt3MinorVer, g_uNt3BuildNo);
+                            break;
+                        }
+                        puDwords++;
+                    }
+                }
+            }
+        }
+        __except(EXCEPTION_EXECUTE_HANDLER)
+        {
+            RTLogBackdoorPrintf("rtR0Nt3InitVersion: Exception scanning .rsrc section for version info!\n");
+        }
+    }
+
+    /*
+     * If we've got PsGetVersion, use it to override the above finding!
+     * (We may end up here for reasons other than the PsGetVersion fallback.)
+     */
+    if (g_pfnrtPsGetVersion)
+    {
+        WCHAR          wszCsd[64];
+        UNICODE_STRING UniStr;
+        UniStr.Buffer        = wszCsd;
+        UniStr.MaximumLength = sizeof(wszCsd) - sizeof(WCHAR);
+        UniStr.Length        = 0;
+        RT_ZERO(wszCsd);
+        ULONG   uMajor   = 3;
+        ULONG   uMinor   = 51;
+        ULONG   uBuildNo = 1057;
+        BOOLEAN fChecked = g_pfnrtPsGetVersion(&uMajor, &uMinor, &uBuildNo, &UniStr);
+
+        g_uNt3MajorVer           = uMajor;
+        g_uNt3MinorVer           = uMinor;
+        g_uNt3BuildNo            = uBuildNo;
+        g_fNt3Checked            = fChecked != FALSE;
+    }
+
+    g_fNt3VersionInitialized = true;
+}
+
+
+extern "C" DECLEXPORT(BOOLEAN) __stdcall
+Nt3Fb_PsGetVersion(ULONG *puMajor, ULONG *puMinor, ULONG *puBuildNo, UNICODE_STRING *pCsdStr)
+{
+    if (!g_fNt3VersionInitialized)
+        rtR0Nt3InitVersion();
+    if (puMajor)
+        *puMajor = g_uNt3MajorVer;
+    if (puMinor)
+        *puMinor = g_uNt3MinorVer;
+    if (puBuildNo)
+        *puBuildNo = g_uNt3BuildNo;
+    if (pCsdStr)
+    {
+        pCsdStr->Buffer[0] = '\0';
+        pCsdStr->Length = 0;
+    }
+    return g_fNt3Checked;
+}
+
+
+/**
+ * Worker for rtR0Nt3InitModuleInfo.
+ */
+static bool rtR0Nt3InitModuleInfoOne(const char *pszImage, uint8_t const *pbCode, uint8_t **ppbModule, uint32_t *pcbModule)
+{
+    uintptr_t const uImageAlign = _4K; /* XP may put the kernel at */
+
+    /* Align pbCode. */
+    pbCode = (uint8_t const *)((uintptr_t)pbCode & ~(uintptr_t)(uImageAlign - 1));
+
+    /* Scan backwards till we find a PE signature. */
+    for (uint32_t cbChecked = 0; cbChecked < _64M; cbChecked += uImageAlign, pbCode -= uImageAlign)
+    {
+        if (!MmIsAddressValid((void *)pbCode))
+            continue;
+
+        uint32_t uZero     = 0;
+        uint32_t offNewHdr = 0;
+        __try /* pointless */
+        {
+            uZero     = *(uint32_t const *)pbCode;
+            offNewHdr = *(uint32_t const *)&pbCode[RT_UOFFSETOF(IMAGE_DOS_HEADER, e_lfanew)];
+        }
+        __except(EXCEPTION_EXECUTE_HANDLER)
+        {
+            RTLogBackdoorPrintf("rtR0Nt3InitModuleInfo: Exception at %p scanning for DOS header...\n", pbCode);
+            continue;
+        }
+        if (   (uint16_t)uZero == IMAGE_DOS_SIGNATURE
+            && offNewHdr < _2K
+            && offNewHdr >= sizeof(IMAGE_DOS_HEADER))
+        {
+            RT_CONCAT(IMAGE_NT_HEADERS,ARCH_BITS) NtHdrs;
+            __try /* pointless */
+            {
+                NtHdrs = *(decltype(NtHdrs) const *)&pbCode[offNewHdr];
+            }
+            __except(EXCEPTION_EXECUTE_HANDLER)
+            {
+                RTLogBackdoorPrintf("rtR0Nt3InitModuleInfo: Exception at %p reading NT headers...\n", pbCode);
+                continue;
+            }
+            if (   NtHdrs.Signature == IMAGE_NT_SIGNATURE
+                && NtHdrs.FileHeader.SizeOfOptionalHeader == sizeof(NtHdrs.OptionalHeader)
+                && NtHdrs.FileHeader.NumberOfSections > 2
+                && NtHdrs.FileHeader.NumberOfSections < _4K
+                && NtHdrs.OptionalHeader.Magic == RT_CONCAT3(IMAGE_NT_OPTIONAL_HDR,ARCH_BITS,_MAGIC))
+            {
+                *ppbModule = (uint8_t *)pbCode;
+                *pcbModule = NtHdrs.OptionalHeader.SizeOfImage;
+                RTLogBackdoorPrintf("rtR0Nt3InitModuleInfo: Found %s at %#p LB %#x\n",
+                                    pszImage, pbCode, NtHdrs.OptionalHeader.SizeOfImage);
+                return true;
+            }
+        }
+    }
+    RTLogBackdoorPrintf("rtR0Nt3InitModuleInfo: Warning! Unable to locate %s...\n");
+    return false;
+}
+
+
+/**
+ * Initializes the module information (NTOSKRNL + HAL) using exported symbols.
+ * This only works as long as noone is intercepting the symbols.
+ */
+static void rtR0Nt3InitModuleInfo(void)
+{
+    rtR0Nt3InitModuleInfoOne("ntoskrnl.exe", (uint8_t const *)(uintptr_t)IoGetCurrentProcess, &g_pbNt3OsKrnl, &g_cbNt3OsKrnl);
+    rtR0Nt3InitModuleInfoOne("hal.dll",      (uint8_t const *)(uintptr_t)HalGetBusData,       &g_pbNt3Hal,    &g_cbNt3Hal);
+    g_fNt3ModuleInfoInitialized = true;
+}
+
+
+extern "C" DECLEXPORT(NTSTATUS) __stdcall
+Nt3Fb_ZwQuerySystemInformation(SYSTEM_INFORMATION_CLASS enmClass, PVOID pvBuf, ULONG cbBuf, PULONG pcbActual)
+{
+    switch (enmClass)
+    {
+        case SystemModuleInformation:
+        {
+            PRTL_PROCESS_MODULES pInfo    = (PRTL_PROCESS_MODULES)pvBuf;
+            ULONG                cbNeeded = RT_UOFFSETOF(RTL_PROCESS_MODULES, Modules[2]);
+            if (pcbActual)
+                *pcbActual = cbNeeded;
+            if (cbBuf < cbNeeded)
+                return STATUS_INFO_LENGTH_MISMATCH;
+
+            if (!g_fNt3ModuleInfoInitialized)
+                rtR0Nt3InitModuleInfo();
+
+            pInfo->NumberOfModules = 2;
+
+            /* ntoskrnl.exe */
+            pInfo->Modules[0].Section           = NULL;
+            pInfo->Modules[0].MappedBase        = g_pbNt3OsKrnl;
+            pInfo->Modules[0].ImageBase         = g_pbNt3OsKrnl;
+            pInfo->Modules[0].ImageSize         = g_cbNt3OsKrnl;
+            pInfo->Modules[0].Flags             = 0;
+            pInfo->Modules[0].LoadOrderIndex    = 0;
+            pInfo->Modules[0].InitOrderIndex    = 0;
+            pInfo->Modules[0].LoadCount         = 1024;
+            pInfo->Modules[0].OffsetToFileName  = sizeof("\\SystemRoot\\System32\\") - 1;
+            memcpy(pInfo->Modules[0].FullPathName, RT_STR_TUPLE("\\SystemRoot\\System32\\ntoskrnl.exe"));
+
+            /* hal.dll */
+            pInfo->Modules[1].Section           = NULL;
+            pInfo->Modules[1].MappedBase        = g_pbNt3Hal;
+            pInfo->Modules[1].ImageBase         = g_pbNt3Hal;
+            pInfo->Modules[1].ImageSize         = g_cbNt3Hal;
+            pInfo->Modules[1].Flags             = 0;
+            pInfo->Modules[1].LoadOrderIndex    = 1;
+            pInfo->Modules[1].InitOrderIndex    = 0;
+            pInfo->Modules[1].LoadCount         = 1024;
+            pInfo->Modules[1].OffsetToFileName  = sizeof("\\SystemRoot\\System32\\") - 1;
+            memcpy(pInfo->Modules[1].FullPathName, RT_STR_TUPLE("\\SystemRoot\\System32\\hal.dll"));
+
+            return STATUS_SUCCESS;
+        }
+
+        default:
+            return STATUS_INVALID_INFO_CLASS;
+    }
+}
+
+/**
+ * Calculates the length indicated by an ModR/M sequence.
+ *
+ * @returns Length, including RM byte.
+ * @param   bRm         The RM byte.
+ */
+static uint32_t rtR0Nt3CalcModRmLength(uint8_t bRm)
+{
+    uint32_t cbRm = 1;
+
+    if (   (bRm & X86_MODRM_MOD_MASK) == (3 << X86_MODRM_MOD_SHIFT)
+        || (bRm & (X86_MODRM_MOD_MASK | X86_MODRM_RM_MASK)) == 5)
+        cbRm += 4; /* disp32 */
+    else if ((bRm & X86_MODRM_MOD_MASK) == (1 << X86_MODRM_MOD_SHIFT))
+        cbRm += 1; /* disp8 */
+    else if ((bRm & X86_MODRM_MOD_MASK) == (2 << X86_MODRM_MOD_SHIFT))
+        cbRm += 2; /* disp16 */
+
+    if ((bRm & X86_MODRM_RM_MASK) == 4 && (bRm & X86_MODRM_MOD_MASK) != (3 << X86_MODRM_MOD_SHIFT))
+        cbRm += 1; /* SIB */
+
+    return cbRm;
+}
+
+
+/**
+ * Init symbols.
+ *
+ * This is called after both ZwQuerySystemInformation and PsGetVersion are used
+ * for the first time.
+ *
+ * @returns IPRT status code
+ * @param   hKrnlInfo           Kernel symbol digger handle.
+ */
+DECLHIDDEN(int) rtR0Nt3InitSymbols(RTDBGKRNLINFO hKrnlInfo)
+{
+    /*
+     * Resolve symbols.  (We set C variables (g_pfnrtXxx) here, not the __imp__Xxx ones.)
+     */
+#define GET_SYSTEM_ROUTINE(a_fnName) do { \
+            RT_CONCAT(g_pfnrt, a_fnName) = (decltype(RT_CONCAT(g_pfnrt, a_fnName)))RTR0DbgKrnlInfoGetSymbol(hKrnlInfo, NULL, #a_fnName); \
+        } while (0)
+
+    GET_SYSTEM_ROUTINE(PsGetVersion);
+    GET_SYSTEM_ROUTINE(ZwQuerySystemInformation);
+    GET_SYSTEM_ROUTINE(KeSetTimerEx);
+    GET_SYSTEM_ROUTINE(IoAttachDeviceToDeviceStack);
+    GET_SYSTEM_ROUTINE(PsGetCurrentProcessId);
+    GET_SYSTEM_ROUTINE(ZwYieldExecution);
+    GET_SYSTEM_ROUTINE(ExAcquireFastMutex);
+    GET_SYSTEM_ROUTINE(ExReleaseFastMutex);
+
+#define GET_FAST_CALL_SYSTEM_ROUTINE(a_fnFastcall, a_fnStdcall) do { \
+            GET_SYSTEM_ROUTINE(a_fnFastcall); \
+            GET_SYSTEM_ROUTINE(a_fnStdcall); \
+            AssertLogRelReturn(RT_CONCAT(g_pfnrt,a_fnFastcall) || RT_CONCAT(g_pfnrt,a_fnStdcall), VERR_INTERNAL_ERROR_3); \
+        } while (0)
+    GET_FAST_CALL_SYSTEM_ROUTINE(IofCompleteRequest,                IoCompleteRequest);
+    GET_FAST_CALL_SYSTEM_ROUTINE(ObfDereferenceObject,              ObDereferenceObject);
+    GET_FAST_CALL_SYSTEM_ROUTINE(IofCallDriver,                     IoCallDriver);
+    GET_FAST_CALL_SYSTEM_ROUTINE(KfAcquireSpinLock,                 KeAcquireSpinLock);
+    GET_FAST_CALL_SYSTEM_ROUTINE(KfReleaseSpinLock,                 KeReleaseSpinLock);
+    GET_FAST_CALL_SYSTEM_ROUTINE(KfLowerIrql,                       KeLowerIrql);
+    GET_FAST_CALL_SYSTEM_ROUTINE(KfRaiseIrql,                       KeRaiseIrql);
+    GET_FAST_CALL_SYSTEM_ROUTINE(KefAcquireSpinLockAtDpcLevel,      KeAcquireSpinLockAtDpcLevel);
+    GET_FAST_CALL_SYSTEM_ROUTINE(KefReleaseSpinLockFromDpcLevel,    KeReleaseSpinLockFromDpcLevel);
+
+    /*
+     * We need to call assembly to update the __imp__Xxx entries, since C
+     * doesn't allow '@' in symbols.
+     */
+    rtNt3InitSymbolsAssembly();
+
+    /*
+     * Tick count data.  We disassemble KeQueryTickCount until we find the
+     * first absolute address referenced in it.
+     *      %80105b70 8b 44 24 04             mov eax, dword [esp+004h]
+     *      %80105b74 c7 40 04 00 00 00 00    mov dword [eax+004h], 000000000h
+     *      %80105b7b 8b 0d 88 70 19 80       mov ecx, dword [080197088h]
+     *      %80105b81 89 08                   mov dword [eax], ecx
+     *      %80105b83 c2 04 00                retn 00004h
+     */
+    _imp__KeTickCount = (decltype(_imp__KeTickCount))RTR0DbgKrnlInfoGetSymbol(hKrnlInfo, NULL, "KeTickCount");
+    if (!_imp__KeTickCount)
+    {
+        if (!g_fNt3VersionInitialized)
+            rtR0Nt3InitVersion();
+        Assert(g_uNt3MajorVer == 3 && g_uNt3MinorVer < 50);
+
+        uint8_t const *pbCode = (uint8_t const *)RTR0DbgKrnlInfoGetSymbol(hKrnlInfo, NULL, "KeQueryTickCount");
+        AssertLogRelReturn(pbCode, VERR_INTERNAL_ERROR_2);
+
+        for (uint32_t off = 0; off < 128 && _imp__KeTickCount == NULL;)
+        {
+            uint8_t const b1 = pbCode[off++];
+            switch (b1)
+            {
+                case 0x8b: /* mov reg, r/m     ; We're looking for absolute address in r/m. */
+                    if ((pbCode[off] & (X86_MODRM_MOD_MASK | X86_MODRM_RM_MASK)) == 5 /*disp32*/)
+                        _imp__KeTickCount = *(KSYSTEM_TIME **)&pbCode[off + 1];
+                    RT_FALL_THRU();
+                case 0x89: /* mov r/m, reg */
+                    off += rtR0Nt3CalcModRmLength(pbCode[off]);
+                    break;
+
+                case 0xc7:
+                    if ((pbCode[off] & X86_MODRM_REG_MASK) == 0) /* mov r/m, imm32 */
+                        off += rtR0Nt3CalcModRmLength(pbCode[off]) + 4;
+                    else
+                    {
+                        RTLogBackdoorPrintf("rtR0Nt3InitSymbols: Failed to find KeTickCount! Encountered unknown opcode at %#x! %.*Rhxs\n",
+                                            off - 1, RT_MAX(off + 16, RT_MIN(PAGE_SIZE - ((uintptr_t)pbCode & PAGE_OFFSET_MASK), 128)), pbCode);
+                        return VERR_INTERNAL_ERROR_3;
+                    }
+                    break;
+
+                case 0xc2: /* ret iw */
+                    RTLogBackdoorPrintf("rtR0Nt3InitSymbols: Failed to find KeTickCount! Encountered RET! %.*Rhxs\n",
+                                        off + 2, pbCode);
+                    return VERR_INTERNAL_ERROR_3;
+
+                default:
+                    RTLogBackdoorPrintf("rtR0Nt3InitSymbols: Failed to find KeTickCount! Encountered unknown opcode at %#x! %.*Rhxs\n",
+                                        off - 1, RT_MAX(off + 16, RT_MIN(PAGE_SIZE - ((uintptr_t)pbCode & PAGE_OFFSET_MASK), 128)), pbCode);
+                    return VERR_INTERNAL_ERROR_3;
+
+                /* Just in case: */
+
+                case 0xa1: /* mov eax, [m32] */
+                    _imp__KeTickCount = *(KSYSTEM_TIME **)&pbCode[off];
+                    off += 4;
+                    break;
+
+                case 50: case 51: case 52: case 53: case 54: case 55: case 56: case 57: /* push reg */
+                    break;
+            }
+        }
+        if (!_imp__KeTickCount)
+        {
+            RTLogBackdoorPrintf("rtR0Nt3InitSymbols: Failed to find KeTickCount after 128 bytes! %.*Rhxs\n", 128, pbCode);
+            return VERR_INTERNAL_ERROR_3;
+        }
+    }
+
+    return VINF_SUCCESS;
+}
+
+
+extern "C" DECLEXPORT(VOID)
+Nt3Fb_KeInitializeTimerEx(PKTIMER pTimer, TIMER_TYPE enmType)
+{
+    KeInitializeTimer(pTimer);
+    NOREF(enmType);
+    /** @todo Default is NotificationTimer, for SyncrhonizationTimer we need to
+     *        do more work.  timer-r0drv-nt.cpp is using the latter. :/  */
+}
+
+
+extern "C" DECLEXPORT(BOOLEAN) __stdcall
+Nt3Fb_KeSetTimerEx(PKTIMER pTimer, LARGE_INTEGER DueTime, LONG cMsPeriod, PKDPC pDpc)
+{
+    AssertReturn(cMsPeriod == 0, FALSE);
+    return KeSetTimer(pTimer, DueTime, pDpc);
+}
+
+
+extern "C" DECLEXPORT(PDEVICE_OBJECT)
+Nt3Fb_IoAttachDeviceToDeviceStack(PDEVICE_OBJECT pSourceDevice, PDEVICE_OBJECT pTargetDevice)
+{
+    NOREF(pSourceDevice); NOREF(pTargetDevice);
+    return NULL;
+}
+
+
+extern "C" DECLEXPORT(HANDLE)
+Nt3Fb_PsGetCurrentProcessId(void)
+{
+    if (!g_fNt3VersionInitialized)
+        rtR0Nt3InitVersion();
+
+    uint8_t const *pbProcess = (uint8_t const *)IoGetCurrentProcess();
+    if (   g_uNt3MajorVer > 3
+        || g_uNt3MinorVer >= 50)
+        return *(HANDLE const *)&pbProcess[0x94];
+    return *(HANDLE const *)&pbProcess[0xb0];
+}
+
+
+extern "C" DECLEXPORT(NTSTATUS)
+Nt3Fb_ZwYieldExecution(VOID)
+{
+    LARGE_INTEGER Interval;
+    Interval.QuadPart = 0;
+    KeDelayExecutionThread(KernelMode, FALSE, &Interval);
+    return STATUS_SUCCESS;
+}
+
+
+/**
+ * This is a simple implementation of the fast mutex api introduced in 3.50.
+ */
+extern "C" DECLEXPORT(VOID) FASTCALL
+Nt3Fb_ExAcquireFastMutex(PFAST_MUTEX pFastMtx)
+{
+    PETHREAD pSelf = PsGetCurrentThread();
+    KIRQL    OldIrql;
+    KeRaiseIrql(APC_LEVEL, &OldIrql);
+
+    /* The Count member is initialized to 1.  So if we decrement it to zero, we're
+       the first locker and owns the mutex.  Otherwise we must wait for our turn. */
+    int32_t  cLockers = ASMAtomicDecS32((int32_t volatile *)&pFastMtx->Count);
+    if (cLockers != 0)
+    {
+        ASMAtomicIncU32((uint32_t volatile *)&pFastMtx->Contention);
+        KeWaitForSingleObject(&pFastMtx->Event, Executive, KernelMode, FALSE /*fAlertable*/, NULL /*pTimeout*/);
+    }
+
+    pFastMtx->Owner   = (PKTHREAD)pSelf;
+    pFastMtx->OldIrql = OldIrql;
+}
+
+
+/**
+ * This is a simple implementation of the fast mutex api introduced in 3.50.
+ */
+extern "C" DECLEXPORT(VOID) FASTCALL
+Nt3Fb_ExReleaseFastMutex(PFAST_MUTEX pFastMtx)
+{
+    AssertMsg(pFastMtx->Owner == (PKTHREAD)PsGetCurrentThread(), ("Owner=%p, expected %p\n", pFastMtx->Owner, PsGetCurrentThread()));
+
+    KIRQL    OldIrql  = pFastMtx->OldIrql;
+    pFastMtx->Owner   = NULL;
+    int32_t  cLockers = ASMAtomicIncS32((int32_t volatile *)&pFastMtx->Count);
+    if (cLockers <= 0)
+        KeSetEvent(&pFastMtx->Event, EVENT_INCREMENT, FALSE /*fWait*/);
+    if (OldIrql != APC_LEVEL)
+        KeLowerIrql(OldIrql);
+}
+
diff --git a/src/VBox/Runtime/r0drv/nt/nt3fakes-stub-r0drv-nt.cpp b/src/VBox/Runtime/r0drv/nt/nt3fakes-stub-r0drv-nt.cpp
new file mode 100644
index 00000000..175f60f9
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/nt3fakes-stub-r0drv-nt.cpp
@@ -0,0 +1,42 @@
+/* $Id: nt3fakes-stub-r0drv-nt.cpp $ */
+/** @file
+ * IPRT - NT 3.x fakes for NT 4.0+ KPIs, init stub.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-nt-kernel.h"
+#include <iprt/errcore.h>
+#include <iprt/dbg.h>
+#include "internal-r0drv-nt.h"
+
+
+int rtR0Nt3InitSymbols(RTDBGKRNLINFO hKrnlInfo)
+{
+    NOREF(hKrnlInfo);
+    return VINF_SUCCESS;
+}
+
diff --git a/src/VBox/Runtime/r0drv/nt/nt3fakesA-r0drv-nt.asm b/src/VBox/Runtime/r0drv/nt/nt3fakesA-r0drv-nt.asm
new file mode 100644
index 00000000..851c77cb
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/nt3fakesA-r0drv-nt.asm
@@ -0,0 +1,147 @@
+; $Id: nt3fakesA-r0drv-nt.asm $
+;; @file
+; IPRT - Companion to nt3fakes-r0drv-nt.cpp that provides import stuff to satisfy the linker.
+;
+
+;
+; Copyright (C) 2006-2020 Oracle Corporation
+;
+; This file is part of VirtualBox Open Source Edition (OSE), as
+; available from http://www.virtualbox.org. This file is free software;
+; you can redistribute it and/or modify it under the terms of the GNU
+; General Public License (GPL) as published by the Free Software
+; Foundation, in version 2 as it comes in the "COPYING" file of the
+; VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+; hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+;
+; The contents of this file may alternatively be used under the terms
+; of the Common Development and Distribution License Version 1.0
+; (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+; VirtualBox OSE distribution, in which case the provisions of the
+; CDDL are applicable instead of those of the GPL.
+;
+; You may elect to license modified versions of this file under the
+; terms and conditions of either the GPL or the CDDL or both.
+;
+
+;*******************************************************************************
+;* Header Files                                                                *
+;*******************************************************************************
+%include "iprt/asmdefs.mac"
+
+%undef NAME
+%define NAME(name) NAME_OVERLOAD(name)
+
+BEGINCODE
+
+;;
+; Called from rtR0Nt3InitSymbols after symbols have been resolved.
+BEGINPROC _rtNt3InitSymbolsAssembly
+        push    ebp
+        mov     ebp, esp
+
+;;
+; @param 1  The fastcall name.
+; @param 2  Byte size of arguments.
+%macro DefineImportDataAndInitCode 3
+extern          $%1 %+ Nt3Fb_ %+ %2 %+ @ %+ %3
+BEGINDATA
+extern          _g_pfnrt %+ %2
+GLOBALNAME __imp_ %+ %1 %+ %2 %+ @ %+ %3
+        dd      $%1 %+ Nt3Fb_ %+ %2 %+ @ %+ %3
+BEGINCODE
+        mov     eax, [_g_pfnrt %+ %2]
+        test    eax, eax
+        jz      %%next
+        mov     [__imp_ %+ %1 %+ %2 %+ @ %+ %3], eax
+%%next:
+%endmacro
+
+        DefineImportDataAndInitCode _,PsGetVersion, 16
+        DefineImportDataAndInitCode _,ZwQuerySystemInformation, 16
+        DefineImportDataAndInitCode _,KeSetTimerEx, 20
+        DefineImportDataAndInitCode _,IoAttachDeviceToDeviceStack, 8
+        DefineImportDataAndInitCode _,PsGetCurrentProcessId, 0
+        DefineImportDataAndInitCode _,ZwYieldExecution, 0
+        DefineImportDataAndInitCode @,ExAcquireFastMutex, 4
+        DefineImportDataAndInitCode @,ExReleaseFastMutex, 4
+
+        xor     eax, eax
+        leave
+        ret
+ENDPROC _rtNt3InitSymbolsAssembly
+
+
+;;
+; @param 1  The fastcall name.
+; @param 2  The stdcall name.
+; @param 3  Byte size of arguments.
+; @param 4  Zero if 1:1 mapping;
+;           One if 2nd parameter is a byte pointer that the farcall version
+;           instead returns in al.
+%macro FastOrStdCallWrapper 4
+BEGINCODE
+extern _g_pfnrt %+ %1
+extern _g_pfnrt %+ %2
+BEGINPROC_EXPORTED $@ %+ %1 %+ @ %+ %3
+        mov     eax, [_g_pfnrt %+ %1]
+        cmp     eax, 0
+        jnz     .got_fast_call
+        mov     eax, .stdcall_wrapper
+        mov     [__imp_@ %+ %1 %+ @ %+ %3], eax
+
+.stdcall_wrapper:
+        push    ebp
+        mov     ebp, esp
+%if %4 == 1
+        push    dword 0
+        push    esp
+%else
+        push    edx
+%endif
+        push    ecx
+        call    [_g_pfnrt %+ %2]
+%if %4 == 1
+        movzx   eax, byte [ebp - 4]
+%endif
+        leave
+        ret
+
+.got_fast_call:
+        mov     [__imp_@ %+ %1 %+ @ %+ %3], eax
+        jmp     eax
+ENDPROC $@ %+ %1 %+ @ %+ %3
+
+BEGINDATA
+GLOBALNAME __imp_@ %+ %1 %+ @ %+ %3
+        dd       $@ %+ %1 %+ @ %+ %3
+%endmacro
+
+FastOrStdCallWrapper IofCompleteRequest,            IoCompleteRequest,              8, 0
+FastOrStdCallWrapper IofCallDriver,                 IoCallDriver,                   8, 0
+FastOrStdCallWrapper ObfDereferenceObject,          ObDereferenceObject,            4, 0
+FastOrStdCallWrapper KfAcquireSpinLock,             KeAcquireSpinLock,              4, 1
+FastOrStdCallWrapper KfReleaseSpinLock,             KeReleaseSpinLock,              8, 0
+FastOrStdCallWrapper KfRaiseIrql,                   KeRaiseIrql,                    4, 1
+FastOrStdCallWrapper KfLowerIrql,                   KeLowerIrql,                    4, 0
+FastOrStdCallWrapper KefAcquireSpinLockAtDpcLevel,  KeAcquireSpinLockAtDpcLevel,    4, 0
+FastOrStdCallWrapper KefReleaseSpinLockFromDpcLevel,KeReleaseSpinLockFromDpcLevel,  4, 0
+
+
+BEGINCODE
+; LONG FASTCALL InterlockedExchange(LONG volatile *,LONG );
+BEGINPROC_EXPORTED $@InterlockedExchange@8
+        mov     eax, edx
+        xchg    [ecx], eax
+        ret
+
+BEGINDATA
+GLOBALNAME __imp_@InterlockedExchange@8
+        dd      $@InterlockedExchange@8
+
+
+BEGINDATA
+GLOBALNAME __imp__KeTickCount
+GLOBALNAME _KeTickCount
+        dd      0
+
diff --git a/src/VBox/Runtime/r0drv/nt/ntBldSymDb.cpp b/src/VBox/Runtime/r0drv/nt/ntBldSymDb.cpp
new file mode 100644
index 00000000..fbcb0613
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/ntBldSymDb.cpp
@@ -0,0 +1,1212 @@
+/* $Id: ntBldSymDb.cpp $ */
+/** @file
+ * IPRT - RTDirCreateUniqueNumbered, generic implementation.
+ */
+
+/*
+ * Copyright (C) 2013-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/win/windows.h>
+#include <iprt/win/dbghelp.h>
+
+#include <iprt/alloca.h>
+#include <iprt/dir.h>
+#include <iprt/file.h>
+#include <iprt/err.h>
+#include <iprt/getopt.h>
+#include <iprt/initterm.h>
+#include <iprt/list.h>
+#include <iprt/mem.h>
+#include <iprt/message.h>
+#include <iprt/path.h>
+#include <iprt/stream.h>
+#include <iprt/string.h>
+#include <iprt/utf16.h>
+
+#include "r0drv/nt/symdb.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/** A structure member we're interested in. */
+typedef struct MYMEMBER
+{
+    /** The member name. */
+    const char * const          pszName;
+    /** Reserved.  */
+    uint32_t    const           fFlags;
+    /** The offset of the member. UINT32_MAX if not found. */
+    uint32_t                    off;
+    /** The size of the member. */
+    uint32_t                    cb;
+    /** Alternative names, optional.
+     * This is a string of zero terminated strings, ending with an zero length
+     * string (or double '\\0' if you like). */
+    const char * const          pszzAltNames;
+} MYMEMBER;
+/** Pointer to a member we're interested. */
+typedef MYMEMBER *PMYMEMBER;
+
+/** Members we're interested in. */
+typedef struct MYSTRUCT
+{
+    /** The structure name. */
+    const char * const          pszName;
+    /** Array of members we're interested in. */
+    MYMEMBER                   *paMembers;
+    /** The number of members we're interested in. */
+    uint32_t const              cMembers;
+    /** Reserved.  */
+    uint32_t const              fFlags;
+} MYSTRUCT;
+
+/** Architecture. */
+typedef enum MYARCH
+{
+    MYARCH_X86,
+    MYARCH_AMD64,
+    MYARCH_DETECT
+} MYARCH;
+
+/** Set of structures for one kernel. */
+typedef struct MYSET
+{
+    /** The list entry. */
+    RTLISTNODE      ListEntry;
+    /** The source PDB. */
+    char           *pszPdb;
+    /** The OS version we've harvested structs for */
+    RTNTSDBOSVER    OsVerInfo;
+    /** The architecture. */
+    MYARCH          enmArch;
+    /** The structures and their member. */
+    MYSTRUCT        aStructs[1];
+} MYSET;
+/** Pointer a set of structures for one kernel. */
+typedef MYSET *PMYSET;
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/** Verbosity level (-v, --verbose). */
+static uint32_t g_iOptVerbose = 1;
+/** Set if we should force ahead despite errors. */
+static bool     g_fOptForce = false;
+
+/** The members of the KPRCB structure that we're interested in. */
+static MYMEMBER g_aKprcbMembers[] =
+{
+    { "QuantumEnd",         0,  UINT32_MAX, UINT32_MAX, NULL },
+    { "DpcQueueDepth",      0,  UINT32_MAX, UINT32_MAX, "DpcData[0].DpcQueueDepth\0" },
+    { "VendorString",       0,  UINT32_MAX, UINT32_MAX, NULL },
+};
+
+/** The structures we're interested in. */
+static MYSTRUCT g_aStructs[] =
+{
+    { "_KPRCB", &g_aKprcbMembers[0], RT_ELEMENTS(g_aKprcbMembers), 0 },
+};
+
+/** List of data we've found. This is sorted by version info. */
+static RTLISTANCHOR g_SetList;
+
+
+
+
+
+/**
+ * For debug/verbose output.
+ *
+ * @param   pszFormat           The format string.
+ * @param   ...                 The arguments referenced in the format string.
+ */
+static void MyDbgPrintf(const char *pszFormat, ...)
+{
+    if (g_iOptVerbose > 1)
+    {
+        va_list va;
+        va_start(va, pszFormat);
+        RTPrintf("debug: ");
+        RTPrintfV(pszFormat, va);
+        va_end(va);
+    }
+}
+
+
+/**
+ * Returns the name we wish to use in the C code.
+ * @returns Structure name.
+ * @param   pStruct             The structure descriptor.
+ */
+static const char *figureCStructName(MYSTRUCT const *pStruct)
+{
+    const char *psz = pStruct->pszName;
+    while (*psz == '_')
+        psz++;
+    return psz;
+}
+
+
+/**
+ * Returns the name we wish to use in the C code.
+ * @returns Member name.
+ * @param   pMember             The member descriptor.
+ */
+static const char *figureCMemberName(MYMEMBER const *pMember)
+{
+    return pMember->pszName;
+}
+
+
+/**
+ * Creates a MYSET with copies of all the data and inserts it into the
+ * g_SetList in a orderly fashion.
+ *
+ * @param   pOut        The output stream.
+ */
+static void generateHeader(PRTSTREAM pOut)
+{
+    RTStrmPrintf(pOut,
+                 "/* $" "I" "d" ": $ */\n" /* avoid it being expanded */
+                 "/** @file\n"
+                 " * IPRT - NT kernel type helpers - Autogenerated, do NOT edit.\n"
+                 " */\n"
+                 "\n"
+                 "/*\n"
+                 " * Copyright (C) 2013-2020 Oracle Corporation \n"
+                 " *\n"
+                 " * This file is part of VirtualBox Open Source Edition (OSE), as\n"
+                 " * available from http://www.virtualbox.org. This file is free software;\n"
+                 " * you can redistribute it and/or modify it under the terms of the GNU\n"
+                 " * General Public License (GPL) as published by the Free Software\n"
+                 " * Foundation, in version 2 as it comes in the \"COPYING\" file of the\n"
+                 " * VirtualBox OSE distribution. VirtualBox OSE is distributed in the\n"
+                 " * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.\n"
+                 " *\n"
+                 " * The contents of this file may alternatively be used under the terms\n"
+                 " * of the Common Development and Distribution License Version 1.0\n"
+                 " * (CDDL) only, as it comes in the \"COPYING.CDDL\" file of the\n"
+                 " * VirtualBox OSE distribution, in which case the provisions of the\n"
+                 " * CDDL are applicable instead of those of the GPL.\n"
+                 " *\n"
+                 " * You may elect to license modified versions of this file under the\n"
+                 " * terms and conditions of either the GPL or the CDDL or both.\n"
+                 " */\n"
+                 "\n"
+                 "\n"
+                 "#ifndef IPRT_INCLUDED_SRC_nt_symdbdata_h\n"
+                 "#define IPRT_INCLUDED_SRC_nt_symdbdata_h\n"
+                 "\n"
+                 "#include \"r0drv/nt/symdb.h\"\n"
+                 "\n"
+                 );
+
+    /*
+     * Generate types.
+     */
+    for (uint32_t i = 0; i < RT_ELEMENTS(g_aStructs); i++)
+    {
+        const char *pszStructName = figureCStructName(&g_aStructs[i]);
+
+        RTStrmPrintf(pOut,
+                     "typedef struct RTNTSDBTYPE_%s\n"
+                     "{\n",
+                     pszStructName);
+        PMYMEMBER paMembers = g_aStructs[i].paMembers;
+        for (uint32_t j = 0; j < g_aStructs->cMembers; j++)
+        {
+            const char *pszMemName = figureCMemberName(&paMembers[j]);
+            RTStrmPrintf(pOut,
+                         "    uint32_t off%s;\n"
+                         "    uint32_t cb%s;\n",
+                         pszMemName, pszMemName);
+        }
+
+        RTStrmPrintf(pOut,
+                     "} RTNTSDBTYPE_%s;\n"
+                     "\n",
+                     pszStructName);
+    }
+
+    RTStrmPrintf(pOut,
+                 "\n"
+                 "typedef struct RTNTSDBSET\n"
+                 "{\n"
+                 "    RTNTSDBOSVER%-20s OsVerInfo;\n", "");
+    for (uint32_t i = 0; i < RT_ELEMENTS(g_aStructs); i++)
+    {
+        const char *pszStructName = figureCStructName(&g_aStructs[i]);
+        RTStrmPrintf(pOut, "    RTNTSDBTYPE_%-20s %s;\n", pszStructName, pszStructName);
+    }
+    RTStrmPrintf(pOut,
+                 "} RTNTSDBSET;\n"
+                 "typedef RTNTSDBSET const *PCRTNTSDBSET;\n"
+                 "\n");
+
+    /*
+     * Output the data.
+     */
+    RTStrmPrintf(pOut,
+                 "\n"
+                 "#ifndef RTNTSDB_NO_DATA\n"
+                 "const RTNTSDBSET g_artNtSdbSets[] = \n"
+                 "{\n");
+    PMYSET pSet;
+    RTListForEach(&g_SetList, pSet, MYSET, ListEntry)
+    {
+        const char *pszArch = pSet->enmArch == MYARCH_AMD64 ? "AMD64" : "X86";
+        RTStrmPrintf(pOut,
+                     "# ifdef RT_ARCH_%s\n"
+                     "    {   /* Source: %s */\n"
+                     "        /*.OsVerInfo = */\n"
+                     "        {\n"
+                     "            /* .uMajorVer = */ %u,\n"
+                     "            /* .uMinorVer = */ %u,\n"
+                     "            /* .fChecked  = */ %s,\n"
+                     "            /* .fSmp      = */ %s,\n"
+                     "            /* .uCsdNo    = */ %u,\n"
+                     "            /* .uBuildNo  = */ %u,\n"
+                     "        },\n",
+                     pszArch,
+                     pSet->pszPdb,
+                     pSet->OsVerInfo.uMajorVer,
+                     pSet->OsVerInfo.uMinorVer,
+                     pSet->OsVerInfo.fChecked ? "true" : "false",
+                     pSet->OsVerInfo.fSmp     ? "true" : "false",
+                     pSet->OsVerInfo.uCsdNo,
+                     pSet->OsVerInfo.uBuildNo);
+        for (uint32_t i = 0; i < RT_ELEMENTS(pSet->aStructs); i++)
+        {
+            const char *pszStructName = figureCStructName(&pSet->aStructs[i]);
+            RTStrmPrintf(pOut,
+                         "        /* .%s = */\n"
+                         "        {\n", pszStructName);
+            PMYMEMBER paMembers = pSet->aStructs[i].paMembers;
+            for (uint32_t j = 0; j < pSet->aStructs[i].cMembers; j++)
+            {
+                const char *pszMemName = figureCMemberName(&paMembers[j]);
+                RTStrmPrintf(pOut,
+                             "            /* .off%-25s = */ %#06x,\n"
+                             "            /* .cb%-26s = */ %#06x,\n",
+                             pszMemName, paMembers[j].off,
+                             pszMemName, paMembers[j].cb);
+            }
+            RTStrmPrintf(pOut,
+                         "        },\n");
+        }
+        RTStrmPrintf(pOut,
+                     "    },\n"
+                     "# endif\n"
+                     );
+    }
+
+    RTStrmPrintf(pOut,
+                 "};\n"
+                 "#endif /* !RTNTSDB_NO_DATA */\n"
+                 "\n");
+
+    RTStrmPrintf(pOut, "\n#endif\n\n");
+}
+
+
+/**
+ * Creates a MYSET with copies of all the data and inserts it into the
+ * g_SetList in a orderly fashion.
+ *
+ * @returns Fully complained exit code.
+ * @param   pOsVerInfo      The OS version info.
+ * @param   enmArch         The NT architecture of the incoming PDB.
+ * @param   pszPdb          The PDB file name.
+ */
+static RTEXITCODE saveStructures(PRTNTSDBOSVER pOsVerInfo, MYARCH enmArch, const char *pszPdb)
+{
+    /*
+     * Allocate one big chunk, figure it's size once.
+     */
+    static size_t s_cbNeeded = 0;
+    if (s_cbNeeded == 0)
+    {
+        s_cbNeeded = RT_UOFFSETOF(MYSET, aStructs[RT_ELEMENTS(g_aStructs)]);
+        for (uint32_t i = 0; i < RT_ELEMENTS(g_aStructs); i++)
+            s_cbNeeded += sizeof(MYMEMBER) * g_aStructs[i].cMembers;
+    }
+
+    size_t cbPdb = strlen(pszPdb) + 1;
+    PMYSET pSet = (PMYSET)RTMemAlloc(s_cbNeeded + cbPdb);
+    if (!pSet)
+        return RTMsgErrorExit(RTEXITCODE_FAILURE, "Out of memory!\n");
+
+    /*
+     * Copy over the data.
+     */
+    pSet->enmArch = enmArch;
+    memcpy(&pSet->OsVerInfo, pOsVerInfo, sizeof(pSet->OsVerInfo));
+    memcpy(&pSet->aStructs[0], g_aStructs, sizeof(g_aStructs));
+
+    PMYMEMBER pDst = (PMYMEMBER)&pSet->aStructs[RT_ELEMENTS(g_aStructs)];
+    for (uint32_t i = 0; i < RT_ELEMENTS(g_aStructs); i++)
+    {
+        pSet->aStructs[i].paMembers = pDst;
+        memcpy(pDst, g_aStructs[i].paMembers, g_aStructs[i].cMembers * sizeof(*pDst));
+        pDst += g_aStructs[i].cMembers;
+    }
+
+    pSet->pszPdb = (char *)pDst;
+    memcpy(pDst, pszPdb, cbPdb);
+
+    /*
+     * Link it.
+     */
+    PMYSET pInsertBefore;
+    RTListForEach(&g_SetList, pInsertBefore, MYSET, ListEntry)
+    {
+        int iDiff = rtNtOsVerInfoCompare(&pInsertBefore->OsVerInfo, &pSet->OsVerInfo);
+        if (iDiff >= 0)
+        {
+            if (iDiff > 0 || pInsertBefore->enmArch > pSet->enmArch)
+            {
+                RTListNodeInsertBefore(&pInsertBefore->ListEntry, &pSet->ListEntry);
+                return RTEXITCODE_SUCCESS;
+            }
+        }
+    }
+
+    RTListAppend(&g_SetList, &pSet->ListEntry);
+    return RTEXITCODE_SUCCESS;
+}
+
+
+/**
+ * Checks that we found everything.
+ *
+ * @returns Fully complained exit code.
+ */
+static RTEXITCODE checkThatWeFoundEverything(void)
+{
+    RTEXITCODE rcExit = RTEXITCODE_SUCCESS;
+    for (uint32_t i = 0; i < RT_ELEMENTS(g_aStructs); i++)
+    {
+        PMYMEMBER paMembers = g_aStructs[i].paMembers;
+        uint32_t  j         = g_aStructs[i].cMembers;
+        while (j-- > 0)
+        {
+            if (paMembers[j].off == UINT32_MAX)
+                rcExit = RTMsgErrorExit(RTEXITCODE_FAILURE, " Missing %s::%s\n", g_aStructs[i].pszName, paMembers[j].pszName);
+        }
+    }
+    return rcExit;
+}
+
+
+/**
+ * Matches the member against what we're looking for.
+ *
+ * @returns Number of hits.
+ * @param   cWantedMembers  The number members in paWantedMembers.
+ * @param   paWantedMembers The members we're looking for.
+ * @param   pszPrefix       The member name prefix.
+ * @param   pszMember       The member name.
+ * @param   offMember       The member offset.
+ * @param   cbMember        The member size.
+ */
+static uint32_t matchUpStructMembers(unsigned cWantedMembers, PMYMEMBER paWantedMembers,
+                                     const char *pszPrefix, const char *pszMember,
+                                     uint32_t offMember, uint32_t cbMember)
+{
+    size_t   cchPrefix = strlen(pszPrefix);
+    uint32_t cHits     = 0;
+    uint32_t iMember   = cWantedMembers;
+    while (iMember-- > 0)
+    {
+        if (   !strncmp(pszPrefix, paWantedMembers[iMember].pszName, cchPrefix)
+            && !strcmp(pszMember, paWantedMembers[iMember].pszName + cchPrefix))
+        {
+            paWantedMembers[iMember].off = offMember;
+            paWantedMembers[iMember].cb  = cbMember;
+            cHits++;
+        }
+        else if (paWantedMembers[iMember].pszzAltNames)
+        {
+            char const *pszCur = paWantedMembers[iMember].pszzAltNames;
+            while (*pszCur)
+            {
+                size_t cchCur = strlen(pszCur);
+                if (   !strncmp(pszPrefix, pszCur, cchPrefix)
+                    && !strcmp(pszMember, pszCur + cchPrefix))
+                {
+                    paWantedMembers[iMember].off = offMember;
+                    paWantedMembers[iMember].cb  = cbMember;
+                    cHits++;
+                    break;
+                }
+                pszCur += cchCur + 1;
+            }
+        }
+    }
+    return cHits;
+}
+
+
+#if 0
+/**
+ * Resets the writable structure members prior to processing a PDB.
+ *
+ * While processing the PDB, will fill in the sizes and offsets of what we find.
+ * Afterwards we'll use look for reset values to see that every structure and
+ * member was located successfully.
+ */
+static void resetMyStructs(void)
+{
+    for (uint32_t i = 0; i < RT_ELEMENTS(g_aStructs); i++)
+    {
+        PMYMEMBER paMembers = g_aStructs[i].paMembers;
+        uint32_t  j         = g_aStructs[i].cMembers;
+        while (j-- > 0)
+        {
+            paMembers[j].off = UINT32_MAX;
+            paMembers[j].cb  = UINT32_MAX;
+        }
+    }
+}
+#endif
+
+
+/**
+ * Find members in the specified structure type (@a idxType).
+ *
+ * @returns Fully bitched exit code.
+ * @param   hFake           Fake process handle.
+ * @param   uModAddr        The module address.
+ * @param   idxType         The type index of the structure which members we're
+ *                          going to process.
+ * @param   cWantedMembers  The number of wanted members.
+ * @param   paWantedMembers The wanted members.  This will be modified.
+ * @param   offDisp         Displacement when calculating member offsets.
+ * @param   pszStructNm     The top level structure name.
+ * @param   pszPrefix       The member name prefix.
+ * @param   pszLogTag       The log tag.
+ */
+static RTEXITCODE findMembers(HANDLE hFake, uint64_t uModAddr, uint32_t idxType,
+                              uint32_t cWantedMembers, PMYMEMBER paWantedMembers,
+                              uint32_t offDisp, const char *pszStructNm, const char *pszPrefix, const char *pszLogTag)
+{
+    RTEXITCODE  rcExit   = RTEXITCODE_SUCCESS;
+
+    DWORD cChildren = 0;
+    if (!SymGetTypeInfo(hFake, uModAddr, idxType, TI_GET_CHILDRENCOUNT, &cChildren))
+        return RTMsgErrorExit(RTEXITCODE_FAILURE, "%s: TI_GET_CHILDRENCOUNT failed on _KPRCB: %u\n", pszLogTag, GetLastError());
+
+    MyDbgPrintf(" %s: cChildren=%u (%#x)\n", pszStructNm, cChildren);
+    TI_FINDCHILDREN_PARAMS *pChildren;
+    pChildren = (TI_FINDCHILDREN_PARAMS *)alloca(RT_UOFFSETOF_DYN(TI_FINDCHILDREN_PARAMS, ChildId[cChildren]));
+    pChildren->Start = 0;
+    pChildren->Count = cChildren;
+    if (!SymGetTypeInfo(hFake, uModAddr, idxType, TI_FINDCHILDREN, pChildren))
+        return RTMsgErrorExit(RTEXITCODE_FAILURE, "%s: TI_FINDCHILDREN failed on _KPRCB: %u\n", pszLogTag, GetLastError());
+
+    for (uint32_t i = 0; i < cChildren; i++)
+    {
+        //MyDbgPrintf(" %s: child#%u: TypeIndex=%u\n", pszStructNm, i, pChildren->ChildId[i]);
+        IMAGEHLP_SYMBOL_TYPE_INFO enmErr;
+        PWCHAR      pwszMember = NULL;
+        uint32_t    idxRefType = 0;
+        uint32_t    offMember = 0;
+        uint64_t    cbMember = 0;
+        uint32_t    cMemberChildren = 0;
+        if (   SymGetTypeInfo(hFake, uModAddr, pChildren->ChildId[i], enmErr = TI_GET_SYMNAME, &pwszMember)
+            && SymGetTypeInfo(hFake, uModAddr, pChildren->ChildId[i], enmErr = TI_GET_OFFSET, &offMember)
+            && SymGetTypeInfo(hFake, uModAddr, pChildren->ChildId[i], enmErr = TI_GET_TYPE, &idxRefType)
+            && SymGetTypeInfo(hFake, uModAddr, idxRefType, enmErr = TI_GET_LENGTH, &cbMember)
+            && SymGetTypeInfo(hFake, uModAddr, idxRefType, enmErr = TI_GET_CHILDRENCOUNT, &cMemberChildren)
+            )
+        {
+            offMember += offDisp;
+
+            char *pszMember;
+            int rc = RTUtf16ToUtf8(pwszMember, &pszMember);
+            if (RT_SUCCESS(rc))
+            {
+                matchUpStructMembers(cWantedMembers, paWantedMembers, pszPrefix, pszMember, offMember, cbMember);
+
+                /*
+                 * Gather more info and do some debug printing. We'll use some
+                 * of this info below when recursing into sub-structures
+                 * and arrays.
+                 */
+                uint32_t fNested      = 0; SymGetTypeInfo(hFake, uModAddr, idxRefType, TI_GET_NESTED, &fNested);
+                uint32_t uDataKind    = 0; SymGetTypeInfo(hFake, uModAddr, idxRefType, TI_GET_DATAKIND, &uDataKind);
+                uint32_t uBaseType    = 0; SymGetTypeInfo(hFake, uModAddr, idxRefType, TI_GET_BASETYPE, &uBaseType);
+                uint32_t uMembTag     = 0; SymGetTypeInfo(hFake, uModAddr, pChildren->ChildId[i], TI_GET_SYMTAG, &uMembTag);
+                uint32_t uBaseTag     = 0; SymGetTypeInfo(hFake, uModAddr, idxRefType, TI_GET_SYMTAG, &uBaseTag);
+                uint32_t cElements    = 0; SymGetTypeInfo(hFake, uModAddr, idxRefType, TI_GET_COUNT, &cElements);
+                uint32_t idxArrayType = 0; SymGetTypeInfo(hFake, uModAddr, idxRefType, TI_GET_ARRAYINDEXTYPEID, &idxArrayType);
+                MyDbgPrintf(" %#06x LB %#06llx %c%c %2d %2d %2d %2d %2d %4d %s::%s%s\n",
+                            offMember, cbMember,
+                            cMemberChildren > 0 ? 'c' : '-',
+                            fNested        != 0 ? 'n' : '-',
+                            uDataKind,
+                            uBaseType,
+                            uMembTag,
+                            uBaseTag,
+                            cElements,
+                            idxArrayType,
+                            pszStructNm,
+                            pszPrefix,
+                            pszMember);
+
+                /*
+                 * Recurse into children.
+                 */
+                if (cMemberChildren > 0)
+                {
+                    size_t cbNeeded = strlen(pszMember) + strlen(pszPrefix) + sizeof(".");
+                    char *pszSubPrefix = (char *)RTMemTmpAlloc(cbNeeded);
+                    if (pszSubPrefix)
+                    {
+                        strcat(strcat(strcpy(pszSubPrefix, pszPrefix), pszMember), ".");
+                        RTEXITCODE rcExit2 = findMembers(hFake, uModAddr, idxRefType, cWantedMembers,
+                                                         paWantedMembers, offMember,
+                                                         pszStructNm,
+                                                         pszSubPrefix,
+                                                         pszLogTag);
+                        if (rcExit2 != RTEXITCODE_SUCCESS)
+                            rcExit = rcExit2;
+                        RTMemTmpFree(pszSubPrefix);
+                    }
+                    else
+                        rcExit = RTMsgErrorExit(RTEXITCODE_FAILURE, "out of memory\n");
+                }
+                /*
+                 * Recurse into arrays too.
+                 */
+                else if (cElements > 0 && idxArrayType > 0)
+                {
+                    BOOL fRc;
+                    uint32_t idxElementRefType = 0;
+                    fRc = SymGetTypeInfo(hFake, uModAddr, idxRefType, TI_GET_TYPE, &idxElementRefType); Assert(fRc);
+                    uint64_t cbElement = cbMember / cElements;
+                    fRc = SymGetTypeInfo(hFake, uModAddr, idxElementRefType, TI_GET_LENGTH, &cbElement); Assert(fRc);
+                    MyDbgPrintf("idxArrayType=%u idxElementRefType=%u cbElement=%u\n", idxArrayType, idxElementRefType, cbElement);
+
+                    size_t cbNeeded = strlen(pszMember) + strlen(pszPrefix) + sizeof("[xxxxxxxxxxxxxxxx].");
+                    char *pszSubPrefix = (char *)RTMemTmpAlloc(cbNeeded);
+                    if (pszSubPrefix)
+                    {
+                        for (uint32_t iElement = 0; iElement < cElements; iElement++)
+                        {
+                            RTStrPrintf(pszSubPrefix, cbNeeded, "%s%s[%u].", pszPrefix, pszMember, iElement);
+                            RTEXITCODE rcExit2 = findMembers(hFake, uModAddr, idxElementRefType, cWantedMembers,
+                                                             paWantedMembers,
+                                                             offMember + iElement * cbElement,
+                                                             pszStructNm,
+                                                             pszSubPrefix,
+                                                             pszLogTag);
+                            if (rcExit2 != RTEXITCODE_SUCCESS)
+                                rcExit = rcExit2;
+                        }
+                        RTMemTmpFree(pszSubPrefix);
+                    }
+                    else
+                        rcExit = RTMsgErrorExit(RTEXITCODE_FAILURE, "out of memory\n");
+                }
+
+                RTStrFree(pszMember);
+            }
+            else
+                rcExit = RTMsgErrorExit(RTEXITCODE_FAILURE, "%s: RTUtf16ToUtf8 failed on %s child#%u: %Rrc\n",
+                                        pszLogTag, pszStructNm, i, rc);
+        }
+        /* TI_GET_OFFSET fails on bitfields, so just ignore+skip those. */
+        else if (enmErr != TI_GET_OFFSET || GetLastError() != ERROR_INVALID_FUNCTION)
+            rcExit = RTMsgErrorExit(RTEXITCODE_FAILURE, "%s: SymGetTypeInfo(,,,%d,) failed on %s child#%u: %u\n",
+                                    pszLogTag, enmErr, pszStructNm, i, GetLastError());
+        LocalFree(pwszMember);
+    } /* For each child. */
+
+    return rcExit;
+}
+
+
+/**
+ * Lookup up structures and members in the given module.
+ *
+ * @returns Fully bitched exit code.
+ * @param   hFake           Fake process handle.
+ * @param   uModAddr        The module address.
+ * @param   pszLogTag       The log tag.
+ * @param   pszPdb          The full PDB path.
+ * @param   pOsVerInfo      The OS version info for altering the error handling
+ *                          for older OSes.
+ */
+static RTEXITCODE findStructures(HANDLE hFake, uint64_t uModAddr, const char *pszLogTag, const char *pszPdb,
+                                 PCRTNTSDBOSVER pOsVerInfo)
+{
+    RTEXITCODE   rcExit   = RTEXITCODE_SUCCESS;
+    PSYMBOL_INFO pSymInfo = (PSYMBOL_INFO)alloca(sizeof(*pSymInfo));
+    for (uint32_t iStruct = 0; iStruct < RT_ELEMENTS(g_aStructs); iStruct++)
+    {
+        pSymInfo->SizeOfStruct = sizeof(*pSymInfo);
+        pSymInfo->MaxNameLen   = 0;
+        if (!SymGetTypeFromName(hFake, uModAddr, g_aStructs[iStruct].pszName, pSymInfo))
+        {
+            if (!(pOsVerInfo->uMajorVer == 5 && pOsVerInfo->uMinorVer == 0) /* w2k */)
+                return RTMsgErrorExit(RTEXITCODE_FAILURE, "%s: Failed to find _KPRCB: %u\n", pszPdb, GetLastError());
+            RTMsgInfo("%s: Skipping - failed to find _KPRCB: %u\n", pszPdb, GetLastError());
+            return RTEXITCODE_SKIPPED;
+        }
+
+        MyDbgPrintf(" %s: TypeIndex=%u\n", g_aStructs[iStruct].pszName, pSymInfo->TypeIndex);
+        MyDbgPrintf(" %s: Size=%u (%#x)\n", g_aStructs[iStruct].pszName, pSymInfo->Size, pSymInfo->Size);
+
+        rcExit = findMembers(hFake, uModAddr, pSymInfo->TypeIndex,
+                             g_aStructs[iStruct].cMembers, g_aStructs[iStruct].paMembers, 0 /* offDisp */,
+                             g_aStructs[iStruct].pszName, "", pszLogTag);
+        if (rcExit != RTEXITCODE_SUCCESS)
+            return rcExit;
+    } /* for each struct we want */
+    return rcExit;
+}
+
+
+#if 0 /* unused */
+static bool strIEndsWith(const char *pszString, const char *pszSuffix)
+{
+    size_t cchString = strlen(pszString);
+    size_t cchSuffix = strlen(pszSuffix);
+    if (cchString < cchSuffix)
+        return false;
+    return RTStrICmp(pszString + cchString - cchSuffix, pszSuffix) == 0;
+}
+#endif
+
+
+/**
+ * Use various hysterics to figure out the OS version details from the PDB path.
+ *
+ * This ASSUMES quite a bunch of things:
+ *      -# Working on unpacked symbol packages. This does not work for
+ *         windbg symbol stores/caches.
+ *      -# The symbol package has been unpacked into a directory with the same
+ *       name as the symbol package (sans suffixes).
+ *
+ * @returns Fully complained exit code.
+ * @param   pszPdb              The path to the PDB.
+ * @param   pVerInfo            Where to return the version info.
+ * @param   penmArch            Where to return the architecture.
+ */
+static RTEXITCODE FigurePdbVersionInfo(const char *pszPdb, PRTNTSDBOSVER pVerInfo, MYARCH *penmArch)
+{
+    /*
+     * Split the path.
+     */
+    union
+    {
+        RTPATHSPLIT Split;
+        uint8_t     abPad[RTPATH_MAX + 1024];
+    } u;
+    int rc = RTPathSplit(pszPdb, &u.Split, sizeof(u), 0);
+    if (RT_FAILURE(rc))
+        return RTMsgErrorExit(RTEXITCODE_FAILURE, "RTPathSplit failed on '%s': %Rrc", pszPdb, rc);
+    if (!(u.Split.fProps & RTPATH_PROP_FILENAME))
+        return RTMsgErrorExit(RTEXITCODE_FAILURE, "RTPATH_PROP_FILENAME not set for: '%s'", pszPdb);
+    const char *pszFilename = u.Split.apszComps[u.Split.cComps - 1];
+
+    /*
+     * SMP or UNI kernel?
+     */
+    if (   !RTStrICmp(pszFilename, "ntkrnlmp.pdb")
+        || !RTStrICmp(pszFilename, "ntkrpamp.pdb")
+       )
+        pVerInfo->fSmp = true;
+    else if (   !RTStrICmp(pszFilename, "ntoskrnl.pdb")
+             || !RTStrICmp(pszFilename, "ntkrnlpa.pdb")
+            )
+        pVerInfo->fSmp = false;
+    else
+        return RTMsgErrorExit(RTEXITCODE_FAILURE, "Doesn't recognize the filename '%s'...", pszFilename);
+
+    /*
+     * Look for symbol pack names in the path. This is stuff like:
+     *  - WindowsVista.6002.090410-1830.x86fre
+     *  - WindowsVista.6002.090410-1830.amd64chk
+     *  - Windows_Win7.7600.16385.090713-1255.X64CHK
+     *  - Windows_Win7SP1.7601.17514.101119-1850.AMD64FRE
+     *  - Windows_Win8.9200.16384.120725-1247.X86CHK
+     *  - en_windows_8_1_symbols_debug_checked_x64_2712568
+     */
+    uint32_t i = u.Split.cComps - 1;
+    while (i-- > 0)
+    {
+        static struct
+        {
+            const char *pszPrefix;
+            size_t      cchPrefix;
+            uint8_t     uMajorVer;
+            uint8_t     uMinorVer;
+            uint8_t     uCsdNo;
+            uint32_t    uBuildNo;   /**< UINT32_MAX means the number immediately after the prefix. */
+        } const s_aSymPacks[] =
+        {
+            { RT_STR_TUPLE("w2kSP1SYM"),                        5, 0, 1, 2195 },
+            { RT_STR_TUPLE("w2ksp2srp1"),                       5, 0, 2, 2195 },
+            { RT_STR_TUPLE("w2ksp2sym"),                        5, 0, 2, 2195 },
+            { RT_STR_TUPLE("w2ksp3sym"),                        5, 0, 3, 2195 },
+            { RT_STR_TUPLE("w2ksp4sym"),                        5, 0, 4, 2195 },
+            { RT_STR_TUPLE("Windows2000-KB891861"),             5, 0, 4, 2195 },
+            { RT_STR_TUPLE("windowsxp"),                        5, 1, 0, 2600 },
+            { RT_STR_TUPLE("xpsp1sym"),                         5, 1, 1, 2600 },
+            { RT_STR_TUPLE("WindowsXP-KB835935-SP2-"),          5, 1, 2, 2600 },
+            { RT_STR_TUPLE("WindowsXP-KB936929-SP3-"),          5, 1, 3, 2600 },
+            { RT_STR_TUPLE("Windows2003."),                     5, 2, 0, 3790 },
+            { RT_STR_TUPLE("Windows2003_sp1."),                 5, 2, 1, 3790 },
+            { RT_STR_TUPLE("WindowsServer2003-KB933548-v1"),    5, 2, 1, 3790 },
+            { RT_STR_TUPLE("WindowsVista.6000."),               6, 0, 0, 6000 },
+            { RT_STR_TUPLE("Windows_Longhorn.6001."),           6, 0, 1, 6001 }, /* incl w2k8 */
+            { RT_STR_TUPLE("WindowsVista.6002."),               6, 0, 2, 6002 }, /* incl w2k8 */
+            { RT_STR_TUPLE("Windows_Winmain.7000"),             6, 1, 0, 7000 }, /* Beta */
+            { RT_STR_TUPLE("Windows_Winmain.7100"),             6, 1, 0, 7100 }, /* RC */
+            { RT_STR_TUPLE("Windows_Win7.7600"),                6, 1, 0, 7600 }, /* RC */
+            { RT_STR_TUPLE("Windows_Win7SP1.7601"),             6, 1, 1, 7601 }, /* RC */
+            { RT_STR_TUPLE("Windows_Winmain.8102"),             6, 2, 0, 8102 }, /* preview */
+            { RT_STR_TUPLE("Windows_Winmain.8250"),             6, 2, 0, 8250 }, /* beta */
+            { RT_STR_TUPLE("Windows_Winmain.8400"),             6, 2, 0, 8400 }, /* RC */
+            { RT_STR_TUPLE("Windows_Win8.9200"),                6, 2, 0, 9200 }, /* RTM */
+            { RT_STR_TUPLE("en_windows_8_1"),                   6, 3, 0, 9600 }, /* RTM */
+            { RT_STR_TUPLE("en_windows_10_symbols_"),          10, 0, 0,10240 }, /* RTM */
+            { RT_STR_TUPLE("en_windows_10_symbols_"),          10, 0, 0,10240 }, /* RTM */
+            { RT_STR_TUPLE("en_windows_10_17134_"),            10, 0, 0,17134 }, /* 1803 */
+        };
+
+        const char *pszComp  = u.Split.apszComps[i];
+        uint32_t    iSymPack = RT_ELEMENTS(s_aSymPacks);
+        while (iSymPack-- > 0)
+            if (!RTStrNICmp(pszComp, s_aSymPacks[iSymPack].pszPrefix, s_aSymPacks[iSymPack].cchPrefix))
+                break;
+        if (iSymPack >= RT_ELEMENTS(s_aSymPacks))
+            continue;
+
+        pVerInfo->uMajorVer = s_aSymPacks[iSymPack].uMajorVer;
+        pVerInfo->uMinorVer = s_aSymPacks[iSymPack].uMinorVer;
+        pVerInfo->uCsdNo    = s_aSymPacks[iSymPack].uCsdNo;
+        pVerInfo->fChecked  = false;
+        pVerInfo->uBuildNo  = s_aSymPacks[iSymPack].uBuildNo;
+
+        /* Parse build number if necessary. */
+        if (s_aSymPacks[iSymPack].uBuildNo == UINT32_MAX)
+        {
+            char *pszNext;
+            rc = RTStrToUInt32Ex(pszComp + s_aSymPacks[iSymPack].cchPrefix, &pszNext, 10, &pVerInfo->uBuildNo);
+            if (RT_FAILURE(rc))
+                return RTMsgErrorExit(RTEXITCODE_FAILURE, "Failed to decode build number in '%s': %Rrc", pszComp, rc);
+            if (*pszNext != '.' && *pszNext != '_' && *pszNext != '-')
+                return RTMsgErrorExit(RTEXITCODE_FAILURE, "Failed to decode build number in '%s': '%c'", pszComp, *pszNext);
+        }
+
+        /* Look for build arch and checked/free. */
+        if (   RTStrIStr(pszComp, ".x86.chk.")
+            || RTStrIStr(pszComp, ".x86chk.")
+            || RTStrIStr(pszComp, "_x86_chk_")
+            || RTStrIStr(pszComp, "_x86chk_")
+            || RTStrIStr(pszComp, "-x86-DEBUG")
+            || (RTStrIStr(pszComp, "-x86-") && RTStrIStr(pszComp, "-DEBUG"))
+            || RTStrIStr(pszComp, "_debug_checked_x86")
+           )
+        {
+            pVerInfo->fChecked = true;
+            *penmArch = MYARCH_X86;
+        }
+        else if (   RTStrIStr(pszComp, ".amd64.chk.")
+                 || RTStrIStr(pszComp, ".amd64chk.")
+                 || RTStrIStr(pszComp, ".x64.chk.")
+                 || RTStrIStr(pszComp, ".x64chk.")
+                 || RTStrIStr(pszComp, "_debug_checked_x64")
+                )
+        {
+            pVerInfo->fChecked = true;
+            *penmArch = MYARCH_AMD64;
+        }
+        else if (   RTStrIStr(pszComp, ".amd64.fre.")
+                 || RTStrIStr(pszComp, ".amd64fre.")
+                 || RTStrIStr(pszComp, ".x64.fre.")
+                 || RTStrIStr(pszComp, ".x64fre.")
+                )
+        {
+            pVerInfo->fChecked = false;
+            *penmArch = MYARCH_AMD64;
+        }
+        else if (   RTStrIStr(pszComp, "DEBUG")
+                 || RTStrIStr(pszComp, "_chk")
+                 )
+        {
+            pVerInfo->fChecked = true;
+            *penmArch = MYARCH_X86;
+        }
+        else if (RTStrIStr(pszComp, "_x64"))
+        {
+            pVerInfo->fChecked = false;
+            *penmArch = MYARCH_AMD64;
+        }
+        else
+        {
+            pVerInfo->fChecked = false;
+            *penmArch = MYARCH_X86;
+        }
+        return RTEXITCODE_SUCCESS;
+    }
+
+    return RTMsgErrorExit(RTEXITCODE_FAILURE, "Giving up on '%s'...\n", pszPdb);
+}
+
+
+/**
+ * Process one PDB.
+ *
+ * @returns Fully bitched exit code.
+ * @param   pszPdb              The path to the PDB.
+ */
+static RTEXITCODE processPdb(const char *pszPdb)
+{
+    /*
+     * We need the size later on, so get that now and present proper IPRT error
+     * info if the file is missing or inaccessible.
+     */
+    RTFSOBJINFO ObjInfo;
+    int rc = RTPathQueryInfoEx(pszPdb, &ObjInfo, RTFSOBJATTRADD_NOTHING, RTPATH_F_FOLLOW_LINK);
+    if (RT_FAILURE(rc))
+        return RTMsgErrorExit(RTEXITCODE_FAILURE, "RTPathQueryInfo fail on '%s': %Rrc\n", pszPdb, rc);
+
+    /*
+     * Figure the windows version details for the given PDB.
+     */
+    MYARCH       enmArch;
+    RTNTSDBOSVER OsVerInfo;
+    RTEXITCODE rcExit = FigurePdbVersionInfo(pszPdb, &OsVerInfo, &enmArch);
+    if (rcExit != RTEXITCODE_SUCCESS)
+        return RTMsgErrorExit(RTEXITCODE_FAILURE, "Failed to figure the OS version info for '%s'.\n'", pszPdb);
+
+    /*
+     * Create a fake handle and open the PDB.
+     */
+    static uintptr_t s_iHandle = 0;
+    HANDLE hFake = (HANDLE)++s_iHandle;
+    if (!SymInitialize(hFake, NULL, FALSE))
+        return RTMsgErrorExit(RTEXITCODE_FAILURE, "SymInitialied failed: %u\n", GetLastError());
+
+    uint64_t uModAddr = UINT64_C(0x1000000);
+    uModAddr = SymLoadModuleEx(hFake, NULL /*hFile*/, pszPdb, NULL /*pszModuleName*/,
+                               uModAddr, ObjInfo.cbObject, NULL /*pData*/, 0 /*fFlags*/);
+    if (uModAddr != 0)
+    {
+        MyDbgPrintf("*** uModAddr=%#llx \"%s\" ***\n", uModAddr, pszPdb);
+
+        char szLogTag[32];
+        RTStrCopy(szLogTag, sizeof(szLogTag), RTPathFilename(pszPdb));
+
+        /*
+         * Find the structures.
+         */
+        rcExit = findStructures(hFake, uModAddr, szLogTag, pszPdb, &OsVerInfo);
+        if (rcExit == RTEXITCODE_SUCCESS)
+            rcExit = checkThatWeFoundEverything();
+        if (rcExit == RTEXITCODE_SUCCESS)
+        {
+            /*
+             * Save the details for later when we produce the header.
+             */
+            rcExit = saveStructures(&OsVerInfo, enmArch, pszPdb);
+        }
+    }
+    else
+        rcExit = RTMsgErrorExit(RTEXITCODE_FAILURE, "SymLoadModuleEx failed: %u\n", GetLastError());
+
+    if (!SymCleanup(hFake))
+        rcExit = RTMsgErrorExit(RTEXITCODE_FAILURE, "SymCleanup failed: %u\n", GetLastError());
+
+    if (rcExit == RTEXITCODE_SKIPPED)
+        rcExit = RTEXITCODE_SUCCESS;
+    return rcExit;
+}
+
+
+/** The size of the directory entry buffer we're using.  */
+#define MY_DIRENTRY_BUF_SIZE (sizeof(RTDIRENTRYEX) + RTPATH_MAX)
+
+/**
+ * Checks if the name is of interest to us.
+ *
+ * @returns true/false.
+ * @param   pszName             The name.
+ * @param   cchName             The length of the name.
+ */
+static bool isInterestingName(const char *pszName, size_t cchName)
+{
+    static struct { const char *psz; size_t cch; } const s_aNames[] =
+    {
+        RT_STR_TUPLE("ntoskrnl.pdb"),
+        RT_STR_TUPLE("ntkrnlmp.pdb"),
+        RT_STR_TUPLE("ntkrnlpa.pdb"),
+        RT_STR_TUPLE("ntkrpamp.pdb"),
+    };
+
+    if (   cchName == s_aNames[0].cch
+        && (pszName[0] == 'n' || pszName[0] == 'N')
+        && (pszName[1] == 't' || pszName[1] == 'T')
+       )
+    {
+        int i = RT_ELEMENTS(s_aNames);
+        while (i-- > 0)
+            if (   s_aNames[i].cch == cchName
+                && !RTStrICmp(s_aNames[i].psz, pszName))
+                return true;
+    }
+    return false;
+}
+
+
+/**
+ * Recursively processes relevant files in the specified directory.
+ *
+ * @returns Fully complained exit code.
+ * @param   pszDir              Pointer to the directory buffer.
+ * @param   cchDir              The length of pszDir in pszDir.
+ * @param   pDirEntry           Pointer to the directory buffer.
+ * @param   iLogDepth           The logging depth.
+ */
+static RTEXITCODE processDirSub(char *pszDir, size_t cchDir, PRTDIRENTRYEX pDirEntry, int iLogDepth)
+{
+    Assert(cchDir > 0); Assert(pszDir[cchDir] == '\0');
+
+    /* Make sure we've got some room in the path, to save us extra work further down. */
+    if (cchDir + 3 >= RTPATH_MAX)
+        return RTMsgErrorExit(RTEXITCODE_FAILURE, "Path too long: '%s'\n", pszDir);
+
+    /* Open directory. */
+    RTDIR hDir;
+    int rc = RTDirOpen(&hDir, pszDir);
+    if (RT_FAILURE(rc))
+        return RTMsgErrorExit(RTEXITCODE_FAILURE, "RTDirOpen failed on '%s': %Rrc\n", pszDir, rc);
+
+    /* Ensure we've got a trailing slash (there is space for it see above). */
+    if (!RTPATH_IS_SEP(pszDir[cchDir - 1]))
+    {
+        pszDir[cchDir++] = RTPATH_SLASH;
+        pszDir[cchDir]   = '\0';
+    }
+
+    /*
+     * Process the files and subdirs.
+     */
+    RTEXITCODE rcExit = RTEXITCODE_SUCCESS;
+    for (;;)
+    {
+        /* Get the next directory. */
+        size_t cbDirEntry = MY_DIRENTRY_BUF_SIZE;
+        rc = RTDirReadEx(hDir, pDirEntry, &cbDirEntry, RTFSOBJATTRADD_UNIX, RTPATH_F_ON_LINK);
+        if (RT_FAILURE(rc))
+            break;
+
+        /* Skip the dot and dot-dot links. */
+        if (RTDirEntryExIsStdDotLink(pDirEntry))
+            continue;
+
+        /* Check length. */
+        if (pDirEntry->cbName + cchDir + 3 >= RTPATH_MAX)
+        {
+            rcExit = RTMsgErrorExit(RTEXITCODE_FAILURE, "Path too long: '%s' in '%.*s'\n", pDirEntry->szName, cchDir, pszDir);
+            break;
+        }
+
+        if (RTFS_IS_FILE(pDirEntry->Info.Attr.fMode))
+        {
+            /*
+             * Process debug info files of interest.
+             */
+            if (isInterestingName(pDirEntry->szName, pDirEntry->cbName))
+            {
+                memcpy(&pszDir[cchDir], pDirEntry->szName, pDirEntry->cbName + 1);
+                RTEXITCODE rcExit2 = processPdb(pszDir);
+                if (rcExit2 != RTEXITCODE_SUCCESS)
+                    rcExit = rcExit2;
+            }
+        }
+        else if (RTFS_IS_DIRECTORY(pDirEntry->Info.Attr.fMode))
+        {
+            /*
+             * Recurse into the subdirectory.  In order to speed up Win7+
+             * symbol pack traversals, we skip directories with ".pdb" suffixes
+             * unless they match any of the .pdb files we're looking for.
+             *
+             * Note! When we get back pDirEntry will be invalid.
+             */
+            if (   pDirEntry->cbName <= 4
+                || RTStrICmp(&pDirEntry->szName[pDirEntry->cbName - 4], ".pdb")
+                || isInterestingName(pDirEntry->szName, pDirEntry->cbName))
+            {
+                memcpy(&pszDir[cchDir], pDirEntry->szName, pDirEntry->cbName + 1);
+                if (iLogDepth > 0)
+                    RTMsgInfo("%s%s ...\n", pszDir, RTPATH_SLASH_STR);
+                RTEXITCODE rcExit2 = processDirSub(pszDir, cchDir + pDirEntry->cbName, pDirEntry, iLogDepth - 1);
+                if (rcExit2 != RTEXITCODE_SUCCESS)
+                    rcExit = rcExit2;
+            }
+        }
+    }
+    if (rc != VERR_NO_MORE_FILES)
+        rcExit = RTMsgErrorExit(RTEXITCODE_FAILURE, "RTDirReadEx failed: %Rrc\npszDir=%.*s", rc, cchDir, pszDir);
+
+    rc = RTDirClose(hDir);
+    if (RT_FAILURE(rc))
+        rcExit = RTMsgErrorExit(RTEXITCODE_FAILURE, "RTDirClose failed: %Rrc\npszDir=%.*s", rc, cchDir, pszDir);
+    return rcExit;
+}
+
+
+/**
+ * Recursively processes relevant files in the specified directory.
+ *
+ * @returns Fully complained exit code.
+ * @param   pszDir              The directory to search.
+ */
+static RTEXITCODE processDir(const char *pszDir)
+{
+    char szPath[RTPATH_MAX];
+    int rc = RTPathAbs(pszDir, szPath, sizeof(szPath));
+    if (RT_FAILURE(rc))
+        return RTMsgErrorExit(RTEXITCODE_FAILURE, "RTPathAbs failed on '%s': %Rrc\n", pszDir, rc);
+
+    union
+    {
+        uint8_t         abPadding[MY_DIRENTRY_BUF_SIZE];
+        RTDIRENTRYEX    DirEntry;
+    } uBuf;
+    return processDirSub(szPath, strlen(szPath), &uBuf.DirEntry, g_iOptVerbose);
+}
+
+
+int main(int argc, char **argv)
+{
+    int rc = RTR3InitExe(argc, &argv, 0 /*fFlags*/);
+    if (RT_FAILURE(rc))
+        return RTMsgInitFailure(rc);
+
+    RTListInit(&g_SetList);
+
+    /*
+     * Parse options.
+     */
+    static const RTGETOPTDEF s_aOptions[] =
+    {
+        { "--force",            'f', RTGETOPT_REQ_NOTHING },
+        { "--output",           'o', RTGETOPT_REQ_STRING  },
+        { "--verbose",          'v', RTGETOPT_REQ_NOTHING },
+        { "--quiet",            'q', RTGETOPT_REQ_NOTHING },
+    };
+
+    RTEXITCODE  rcExit      = RTEXITCODE_SUCCESS;
+    const char *pszOutput   = "-";
+
+    int ch;
+    RTGETOPTUNION ValueUnion;
+    RTGETOPTSTATE GetState;
+    RTGetOptInit(&GetState, argc, argv, s_aOptions, RT_ELEMENTS(s_aOptions), 1,
+                 RTGETOPTINIT_FLAGS_OPTS_FIRST);
+    while ((ch = RTGetOpt(&GetState, &ValueUnion)) != 0)
+    {
+        switch (ch)
+        {
+            case 'f':
+                g_fOptForce = true;
+                break;
+
+            case 'v':
+                g_iOptVerbose++;
+                break;
+
+            case 'q':
+                g_iOptVerbose++;
+                break;
+
+            case 'o':
+                pszOutput = ValueUnion.psz;
+                break;
+
+            case 'V':
+                RTPrintf("$Revision: 143400 $");
+                break;
+
+            case 'h':
+                RTPrintf("usage: %s [-v|--verbose] [-q|--quiet] [-f|--force] [-o|--output <file.h>] <dir1|pdb1> [...]\n"
+                         "   or: %s [-V|--version]\n"
+                         "   or: %s [-h|--help]\n",
+                         argv[0], argv[0], argv[0]);
+                return RTEXITCODE_SUCCESS;
+
+            case VINF_GETOPT_NOT_OPTION:
+            {
+                RTEXITCODE rcExit2;
+                if (RTFileExists(ValueUnion.psz))
+                    rcExit2 = processPdb(ValueUnion.psz);
+                else
+                    rcExit2 = processDir(ValueUnion.psz);
+                if (rcExit2 != RTEXITCODE_SUCCESS)
+                {
+                    if (!g_fOptForce)
+                        return rcExit2;
+                    rcExit = rcExit2;
+                }
+                break;
+            }
+
+            default:
+                return RTGetOptPrintError(ch, &ValueUnion);
+        }
+    }
+    if (RTListIsEmpty(&g_SetList))
+        return RTMsgErrorExit(RTEXITCODE_FAILURE, "No usable debug files found.\n");
+
+    /*
+     * Generate the output.
+     */
+    PRTSTREAM pOut = g_pStdOut;
+    if (strcmp(pszOutput, "-"))
+    {
+        rc = RTStrmOpen(pszOutput, "w", &pOut);
+        if (RT_FAILURE(rc))
+            return RTMsgErrorExit(RTEXITCODE_FAILURE, "Error opening '%s' for writing: %Rrc\n", pszOutput, rc);
+    }
+
+    generateHeader(pOut);
+
+    if (pOut != g_pStdOut)
+        rc = RTStrmClose(pOut);
+    else
+        rc = RTStrmFlush(pOut);
+    if (RT_FAILURE(rc))
+        return RTMsgErrorExit(RTEXITCODE_FAILURE, "Error %s '%s': %Rrc\n", pszOutput,
+                              pOut != g_pStdOut ? "closing" : "flushing", rc);
+    return rcExit;
+}
diff --git a/src/VBox/Runtime/r0drv/nt/process-r0drv-nt.cpp b/src/VBox/Runtime/r0drv/nt/process-r0drv-nt.cpp
new file mode 100644
index 00000000..acab821e
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/process-r0drv-nt.cpp
@@ -0,0 +1,45 @@
+/* $Id: process-r0drv-nt.cpp $ */
+/** @file
+ * IPRT - Process, Ring-0 Driver, NT.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-nt-kernel.h"
+#include <iprt/process.h>
+
+
+RTDECL(RTPROCESS) RTProcSelf(void)
+{
+    return (RTPROCESS)(uintptr_t)PsGetCurrentProcessId();
+}
+
+
+RTR0DECL(RTR0PROCESS) RTR0ProcHandleSelf(void)
+{
+    return (RTR0PROCESS)PsGetCurrentProcess();
+}
+
diff --git a/src/VBox/Runtime/r0drv/nt/semevent-r0drv-nt.cpp b/src/VBox/Runtime/r0drv/nt/semevent-r0drv-nt.cpp
new file mode 100644
index 00000000..48d16b67
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/semevent-r0drv-nt.cpp
@@ -0,0 +1,277 @@
+/* $Id: semevent-r0drv-nt.cpp $ */
+/** @file
+ * IPRT -  Single Release Event Semaphores, Ring-0 Driver, NT.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTSEMEVENT_WITHOUT_REMAPPING
+#include "the-nt-kernel.h"
+#include <iprt/semaphore.h>
+
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/lockvalidator.h>
+#include <iprt/mem.h>
+#include <iprt/time.h>
+#include <iprt/timer.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * NT event semaphore.
+ */
+typedef struct RTSEMEVENTINTERNAL
+{
+    /** Magic value (RTSEMEVENT_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** Reference counter. */
+    uint32_t volatile   cRefs;
+    /** The NT Event object. */
+    KEVENT              Event;
+} RTSEMEVENTINTERNAL, *PRTSEMEVENTINTERNAL;
+
+
+RTDECL(int)  RTSemEventCreate(PRTSEMEVENT phEventSem)
+{
+    return RTSemEventCreateEx(phEventSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, NULL);
+}
+
+
+RTDECL(int)  RTSemEventCreateEx(PRTSEMEVENT phEventSem, uint32_t fFlags, RTLOCKVALCLASS hClass, const char *pszNameFmt, ...)
+{
+    AssertReturn(!(fFlags & ~(RTSEMEVENT_FLAGS_NO_LOCK_VAL | RTSEMEVENT_FLAGS_BOOTSTRAP_HACK)), VERR_INVALID_PARAMETER);
+    Assert(!(fFlags & RTSEMEVENT_FLAGS_BOOTSTRAP_HACK) || (fFlags & RTSEMEVENT_FLAGS_NO_LOCK_VAL));
+    AssertCompile(sizeof(RTSEMEVENTINTERNAL) > sizeof(void *));
+    RT_NOREF2(hClass, pszNameFmt);
+
+    PRTSEMEVENTINTERNAL pThis = (PRTSEMEVENTINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (pThis)
+    {
+        pThis->u32Magic = RTSEMEVENT_MAGIC;
+        pThis->cRefs    = 1;
+        KeInitializeEvent(&pThis->Event, SynchronizationEvent, FALSE /* not signalled */);
+
+        *phEventSem = pThis;
+        return VINF_SUCCESS;
+    }
+    return VERR_NO_MEMORY;
+}
+
+
+/**
+ * Retains a reference to the semaphore.
+ *
+ * @param   pThis       The semaphore to retain.
+ */
+DECLINLINE(void) rtR0SemEventNtRetain(PRTSEMEVENTINTERNAL pThis)
+{
+    uint32_t cRefs = ASMAtomicIncU32(&pThis->cRefs);
+    Assert(cRefs < 100000); NOREF(cRefs);
+}
+
+
+/**
+ * Releases a reference to the semaphore.
+ *
+ * @param   pThis       The semaphore to release
+ */
+DECLINLINE(void) rtR0SemEventNtRelease(PRTSEMEVENTINTERNAL pThis)
+{
+    if (ASMAtomicDecU32(&pThis->cRefs) == 0)
+        RTMemFree(pThis);
+}
+
+
+RTDECL(int)  RTSemEventDestroy(RTSEMEVENT hEventSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTINTERNAL pThis = hEventSem;
+    if (pThis == NIL_RTSEMEVENT)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("pThis->u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+
+    /*
+     * Invalidate it and signal the object just in case.
+     */
+    ASMAtomicIncU32(&pThis->u32Magic);
+    KeSetEvent(&pThis->Event, 0xfff, FALSE);
+    rtR0SemEventNtRelease(pThis);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTSemEventSignal(RTSEMEVENT hEventSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTINTERNAL pThis = (PRTSEMEVENTINTERNAL)hEventSem;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("pThis->u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+    rtR0SemEventNtRetain(pThis);
+
+    /*
+     * Signal the event object.
+     */
+    KeSetEvent(&pThis->Event, 1, FALSE);
+
+    rtR0SemEventNtRelease(pThis);
+    return VINF_SUCCESS;
+}
+
+
+
+/**
+ * Worker for RTSemEventWaitEx and RTSemEventWaitExDebug.
+ *
+ * @returns VBox status code.
+ * @param   pThis           The event semaphore.
+ * @param   fFlags          See RTSemEventWaitEx.
+ * @param   uTimeout        See RTSemEventWaitEx.
+ * @param   pSrcPos         The source code position of the wait.
+ */
+DECLINLINE(int) rtR0SemEventNtWait(PRTSEMEVENTINTERNAL pThis, uint32_t fFlags, uint64_t uTimeout,
+                                   PCRTLOCKVALSRCPOS pSrcPos)
+{
+    /*
+     * Validate input.
+     */
+    if (!pThis)
+        return VERR_INVALID_PARAMETER;
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    AssertReturn(RTSEMWAIT_FLAGS_ARE_VALID(fFlags), VERR_INVALID_PARAMETER);
+    NOREF(pSrcPos);
+
+    rtR0SemEventNtRetain(pThis);
+
+    /*
+     * Convert the timeout to a relative one because KeWaitForSingleObject
+     * takes system time instead of interrupt time as input for absolute
+     * timeout specifications.  So, we're best of by giving it relative time.
+     *
+     * Lazy bird converts uTimeout to relative nanoseconds and then to Nt time.
+     */
+    if (!(fFlags & RTSEMWAIT_FLAGS_INDEFINITE))
+    {
+        if (fFlags & RTSEMWAIT_FLAGS_MILLISECS)
+            uTimeout = uTimeout < UINT64_MAX / UINT32_C(1000000) * UINT32_C(1000000)
+                     ? uTimeout * UINT32_C(1000000)
+                     : UINT64_MAX;
+        if (uTimeout == UINT64_MAX)
+            fFlags |= RTSEMWAIT_FLAGS_INDEFINITE;
+        else
+        {
+            if (fFlags & RTSEMWAIT_FLAGS_ABSOLUTE)
+            {
+                uint64_t u64Now = RTTimeSystemNanoTS();
+                uTimeout = u64Now < uTimeout
+                         ? uTimeout - u64Now
+                         : 0;
+            }
+        }
+    }
+
+    /*
+     * Wait for it.
+     * We're assuming interruptible waits should happen at UserMode level.
+     */
+    NTSTATUS        rcNt;
+    BOOLEAN         fInterruptible = !!(fFlags & RTSEMWAIT_FLAGS_INTERRUPTIBLE);
+    KPROCESSOR_MODE WaitMode   = fInterruptible ? UserMode : KernelMode;
+    if (fFlags & RTSEMWAIT_FLAGS_INDEFINITE)
+        rcNt = KeWaitForSingleObject(&pThis->Event, Executive, WaitMode, fInterruptible, NULL);
+    else
+    {
+        LARGE_INTEGER Timeout;
+        Timeout.QuadPart = -(int64_t)(uTimeout / 100);
+        rcNt = KeWaitForSingleObject(&pThis->Event, Executive, WaitMode, fInterruptible, &Timeout);
+    }
+    int rc;
+    if (pThis->u32Magic == RTSEMEVENT_MAGIC)
+    {
+        switch (rcNt)
+        {
+            case STATUS_SUCCESS:
+                rc = VINF_SUCCESS;
+                break;
+            case STATUS_ALERTED:
+                rc = VERR_INTERRUPTED;
+                break;
+            case STATUS_USER_APC:
+                rc = VERR_INTERRUPTED;
+                break;
+            case STATUS_TIMEOUT:
+                rc = VERR_TIMEOUT;
+                break;
+            default:
+                AssertMsgFailed(("pThis->u32Magic=%RX32 pThis=%p: wait returned %lx!\n",
+                                 pThis->u32Magic, pThis, (long)rcNt));
+                rc = VERR_INTERNAL_ERROR_4;
+                break;
+        }
+    }
+    else
+        rc = VERR_SEM_DESTROYED;
+
+    rtR0SemEventNtRelease(pThis);
+    return rc;
+}
+
+
+RTDECL(int)  RTSemEventWaitEx(RTSEMEVENT hEventSem, uint32_t fFlags, uint64_t uTimeout)
+{
+#ifndef RTSEMEVENT_STRICT
+    return rtR0SemEventNtWait(hEventSem, fFlags, uTimeout, NULL);
+#else
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
+    return rtR0SemEventNtWait(hEventSem, fFlags, uTimeout, &SrcPos);
+#endif
+}
+
+
+RTDECL(int)  RTSemEventWaitExDebug(RTSEMEVENT hEventSem, uint32_t fFlags, uint64_t uTimeout,
+                                   RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
+    return rtR0SemEventNtWait(hEventSem, fFlags, uTimeout, &SrcPos);
+}
+
+
+RTDECL(uint32_t) RTSemEventGetResolution(void)
+{
+    return RTTimerGetSystemGranularity();
+}
+
diff --git a/src/VBox/Runtime/r0drv/nt/semeventmulti-r0drv-nt.cpp b/src/VBox/Runtime/r0drv/nt/semeventmulti-r0drv-nt.cpp
new file mode 100644
index 00000000..59ed0e4e
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/semeventmulti-r0drv-nt.cpp
@@ -0,0 +1,300 @@
+/* $Id: semeventmulti-r0drv-nt.cpp $ */
+/** @file
+ * IPRT -  Multiple Release Event Semaphores, Ring-0 Driver, NT.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTSEMEVENTMULTI_WITHOUT_REMAPPING
+#include "the-nt-kernel.h"
+#include <iprt/semaphore.h>
+
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/lockvalidator.h>
+#include <iprt/mem.h>
+#include <iprt/time.h>
+#include <iprt/timer.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * NT event semaphore.
+ */
+typedef struct RTSEMEVENTMULTIINTERNAL
+{
+    /** Magic value (RTSEMEVENTMULTI_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** Reference counter. */
+    uint32_t volatile   cRefs;
+    /** The NT Event object. */
+    KEVENT              Event;
+} RTSEMEVENTMULTIINTERNAL, *PRTSEMEVENTMULTIINTERNAL;
+
+
+RTDECL(int)  RTSemEventMultiCreate(PRTSEMEVENTMULTI phEventMultiSem)
+{
+    return RTSemEventMultiCreateEx(phEventMultiSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, NULL);
+}
+
+
+RTDECL(int)  RTSemEventMultiCreateEx(PRTSEMEVENTMULTI phEventMultiSem, uint32_t fFlags, RTLOCKVALCLASS hClass,
+                                     const char *pszNameFmt, ...)
+{
+    AssertReturn(!(fFlags & ~RTSEMEVENTMULTI_FLAGS_NO_LOCK_VAL), VERR_INVALID_PARAMETER);
+    RT_NOREF2(hClass, pszNameFmt);
+
+    AssertCompile(sizeof(RTSEMEVENTMULTIINTERNAL) > sizeof(void *));
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (pThis)
+    {
+        pThis->u32Magic = RTSEMEVENTMULTI_MAGIC;
+        pThis->cRefs    = 1;
+        KeInitializeEvent(&pThis->Event, NotificationEvent, FALSE /* not signalled */);
+
+        *phEventMultiSem = pThis;
+        return VINF_SUCCESS;
+    }
+    return VERR_NO_MEMORY;
+}
+
+
+/**
+ * Retains a reference to the semaphore.
+ *
+ * @param   pThis       The semaphore to retain.
+ */
+DECLINLINE(void) rtR0SemEventMultiNtRetain(PRTSEMEVENTMULTIINTERNAL pThis)
+{
+    uint32_t cRefs = ASMAtomicIncU32(&pThis->cRefs);
+    Assert(cRefs < 100000); NOREF(cRefs);
+}
+
+
+/**
+ * Releases a reference to the semaphore.
+ *
+ * @param   pThis       The semaphore to release
+ */
+DECLINLINE(void) rtR0SemEventMultiNtRelease(PRTSEMEVENTMULTIINTERNAL pThis)
+{
+    if (ASMAtomicDecU32(&pThis->cRefs) == 0)
+        RTMemFree(pThis);
+}
+
+
+RTDECL(int) RTSemEventMultiDestroy(RTSEMEVENTMULTI hEventMultiSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    if (pThis == NIL_RTSEMEVENTMULTI)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+
+    /*
+     * Invalidate it and signal the object just in case.
+     */
+    ASMAtomicIncU32(&pThis->u32Magic);
+    KeSetEvent(&pThis->Event, 0xfff, FALSE);
+    rtR0SemEventMultiNtRelease(pThis);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTSemEventMultiSignal(RTSEMEVENTMULTI hEventMultiSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    if (!pThis)
+        return VERR_INVALID_PARAMETER;
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    rtR0SemEventMultiNtRetain(pThis);
+
+    /*
+     * Signal the event object.
+     */
+    KeSetEvent(&pThis->Event, 1, FALSE);
+
+    rtR0SemEventMultiNtRelease(pThis);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTSemEventMultiReset(RTSEMEVENTMULTI hEventMultiSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    if (!pThis)
+        return VERR_INVALID_PARAMETER;
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    rtR0SemEventMultiNtRetain(pThis);
+
+    /*
+     * Reset the event object.
+     */
+    KeResetEvent(&pThis->Event);
+
+    rtR0SemEventMultiNtRelease(pThis);
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Worker for RTSemEventMultiWaitEx and RTSemEventMultiWaitExDebug.
+ *
+ * @returns VBox status code.
+ * @param   pThis           The event semaphore.
+ * @param   fFlags          See RTSemEventMultiWaitEx.
+ * @param   uTimeout        See RTSemEventMultiWaitEx.
+ * @param   pSrcPos         The source code position of the wait.
+ */
+DECLINLINE(int) rtR0SemEventMultiNtWait(PRTSEMEVENTMULTIINTERNAL pThis, uint32_t fFlags, uint64_t uTimeout,
+                                        PCRTLOCKVALSRCPOS pSrcPos)
+{
+    /*
+     * Validate input.
+     */
+    if (!pThis)
+        return VERR_INVALID_PARAMETER;
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    AssertReturn(RTSEMWAIT_FLAGS_ARE_VALID(fFlags), VERR_INVALID_PARAMETER);
+    RT_NOREF1(pSrcPos);
+
+    rtR0SemEventMultiNtRetain(pThis);
+
+    /*
+     * Convert the timeout to a relative one because KeWaitForSingleObject
+     * takes system time instead of interrupt time as input for absolute
+     * timeout specifications.  So, we're best of by giving it relative time.
+     *
+     * Lazy bird converts uTimeout to relative nanoseconds and then to Nt time.
+     */
+    if (!(fFlags & RTSEMWAIT_FLAGS_INDEFINITE))
+    {
+        if (fFlags & RTSEMWAIT_FLAGS_MILLISECS)
+            uTimeout = uTimeout < UINT64_MAX / UINT32_C(1000000) * UINT32_C(1000000)
+                     ? uTimeout * UINT32_C(1000000)
+                     : UINT64_MAX;
+        if (uTimeout == UINT64_MAX)
+            fFlags |= RTSEMWAIT_FLAGS_INDEFINITE;
+        else
+        {
+            if (fFlags & RTSEMWAIT_FLAGS_ABSOLUTE)
+            {
+                uint64_t u64Now = RTTimeSystemNanoTS();
+                uTimeout = u64Now < uTimeout
+                         ? uTimeout - u64Now
+                         : 0;
+            }
+        }
+    }
+
+    /*
+     * Wait for it.
+     * We're assuming interruptible waits should happen at UserMode level.
+     */
+    NTSTATUS        rcNt;
+    BOOLEAN         fInterruptible = !!(fFlags & RTSEMWAIT_FLAGS_INTERRUPTIBLE);
+    KPROCESSOR_MODE WaitMode   = fInterruptible ? UserMode : KernelMode;
+    if (fFlags & RTSEMWAIT_FLAGS_INDEFINITE)
+        rcNt = KeWaitForSingleObject(&pThis->Event, Executive, WaitMode, fInterruptible, NULL);
+    else
+    {
+        LARGE_INTEGER Timeout;
+        Timeout.QuadPart = -(int64_t)(uTimeout / 100);
+        rcNt = KeWaitForSingleObject(&pThis->Event, Executive, WaitMode, fInterruptible, &Timeout);
+    }
+    int rc;
+    if (pThis->u32Magic == RTSEMEVENTMULTI_MAGIC)
+    {
+        switch (rcNt)
+        {
+            case STATUS_SUCCESS:
+                rc = VINF_SUCCESS;
+                break;
+            case STATUS_ALERTED:
+                rc = VERR_INTERRUPTED;
+                break;
+            case STATUS_USER_APC:
+                rc = VERR_INTERRUPTED;
+                break;
+            case STATUS_TIMEOUT:
+                rc = VERR_TIMEOUT;
+                break;
+            default:
+                AssertMsgFailed(("pThis->u32Magic=%RX32 pThis=%p: wait returned %lx!\n",
+                                 pThis->u32Magic, pThis, (long)rcNt));
+                rc = VERR_INTERNAL_ERROR_4;
+                break;
+        }
+    }
+    else
+        rc = VERR_SEM_DESTROYED;
+
+    rtR0SemEventMultiNtRelease(pThis);
+    return rc;
+}
+
+
+RTDECL(int)  RTSemEventMultiWaitEx(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout)
+{
+#ifndef RTSEMEVENT_STRICT
+    return rtR0SemEventMultiNtWait(hEventMultiSem, fFlags, uTimeout, NULL);
+#else
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
+    return rtR0SemEventMultiNtWait(hEventMultiSem, fFlags, uTimeout, &SrcPos);
+#endif
+}
+
+
+RTDECL(int)  RTSemEventMultiWaitExDebug(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout,
+                                        RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
+    return rtR0SemEventMultiNtWait(hEventMultiSem, fFlags, uTimeout, &SrcPos);
+}
+
+
+RTDECL(uint32_t) RTSemEventMultiGetResolution(void)
+{
+    return RTTimerGetSystemGranularity();
+}
+
diff --git a/src/VBox/Runtime/r0drv/nt/semfastmutex-r0drv-nt.cpp b/src/VBox/Runtime/r0drv/nt/semfastmutex-r0drv-nt.cpp
new file mode 100644
index 00000000..0780a2dd
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/semfastmutex-r0drv-nt.cpp
@@ -0,0 +1,138 @@
+/* $Id: semfastmutex-r0drv-nt.cpp $ */
+/** @file
+ * IPRT - Fast Mutex Semaphores, Ring-0 Driver, NT.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-nt-kernel.h"
+#include <iprt/semaphore.h>
+#include <iprt/alloc.h>
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+#include <iprt/errcore.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Wrapper for the linux semaphore structure.
+ */
+typedef struct RTSEMFASTMUTEXINTERNAL
+{
+    /** Magic value (RTSEMFASTMUTEX_MAGIC). */
+    uint32_t            u32Magic;
+    /** the NT fast mutex. */
+    FAST_MUTEX          Mutex;
+} RTSEMFASTMUTEXINTERNAL, *PRTSEMFASTMUTEXINTERNAL;
+
+
+
+RTDECL(int)  RTSemFastMutexCreate(PRTSEMFASTMUTEX phFastMtx)
+{
+    /*
+     * Allocate.
+     */
+    PRTSEMFASTMUTEXINTERNAL pThis;
+    Assert(sizeof(*pThis) > sizeof(void *));
+    pThis = (PRTSEMFASTMUTEXINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (!pThis)
+        return VERR_NO_MEMORY;
+
+    /*
+     * Initialize.
+     */
+    pThis->u32Magic = RTSEMFASTMUTEX_MAGIC;
+    ExInitializeFastMutex(&pThis->Mutex);
+
+    *phFastMtx = pThis;
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemFastMutexDestroy(RTSEMFASTMUTEX hFastMtx)
+{
+    /*
+     * Validate.
+     */
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    if (pThis == NIL_RTSEMFASTMUTEX)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    ASMAtomicWriteU32(&pThis->u32Magic, RTSEMFASTMUTEX_MAGIC_DEAD);
+    Assert(pThis->Mutex.Count == 1);
+    RTMemFree(pThis);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemFastMutexRequest(RTSEMFASTMUTEX hFastMtx)
+{
+    /*
+     * Validate.
+     */
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+#if 1
+    /*
+     * ExAcquireFastMutex will set the IRQL to APC regardless of our current
+     * level.  Lowering the IRQL may screw things up, so do not allow this.
+     */
+# if 0 /** @todo enable this when the logger has been fixed. */
+    AssertMsg(KeGetCurrentIrql() <= APC_LEVEL, ("%d\n", KeGetCurrentIrql()), VERR_INVALID_STATE);
+# else  /* the gentler approach. */
+    KIRQL Irql = KeGetCurrentIrql();
+    if (Irql > APC_LEVEL)
+        return VERR_INVALID_STATE;
+# endif
+#endif
+
+    ExAcquireFastMutex(&pThis->Mutex);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemFastMutexRelease(RTSEMFASTMUTEX hFastMtx)
+{
+    /*
+     * Validate.
+     */
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    ExReleaseFastMutex(&pThis->Mutex);
+    return VINF_SUCCESS;
+}
+
diff --git a/src/VBox/Runtime/r0drv/nt/semmutex-r0drv-nt.cpp b/src/VBox/Runtime/r0drv/nt/semmutex-r0drv-nt.cpp
new file mode 100644
index 00000000..91e79605
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/semmutex-r0drv-nt.cpp
@@ -0,0 +1,236 @@
+/* $Id: semmutex-r0drv-nt.cpp $ */
+/** @file
+ * IPRT - Mutex Semaphores, Ring-0 Driver, NT.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTSEMMUTEX_WITHOUT_REMAPPING
+#include "the-nt-kernel.h"
+#include <iprt/semaphore.h>
+#include <iprt/alloc.h>
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+#include <iprt/err.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * NT mutex semaphore.
+ */
+typedef struct RTSEMMUTEXINTERNAL
+{
+    /** Magic value (RTSEMMUTEX_MAGIC). */
+    uint32_t volatile   u32Magic;
+#ifdef RT_USE_FAST_MUTEX
+    /** The fast mutex object. */
+    FAST_MUTEX          Mutex;
+#else
+    /** The NT Mutex object. */
+    KMUTEX              Mutex;
+#endif
+} RTSEMMUTEXINTERNAL, *PRTSEMMUTEXINTERNAL;
+
+
+
+RTDECL(int)  RTSemMutexCreate(PRTSEMMUTEX phMutexSem)
+{
+    return RTSemMutexCreateEx(phMutexSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, RTLOCKVAL_SUB_CLASS_NONE, NULL);
+}
+
+
+RTDECL(int) RTSemMutexCreateEx(PRTSEMMUTEX phMutexSem, uint32_t fFlags,
+                               RTLOCKVALCLASS hClass, uint32_t uSubClass, const char *pszNameFmt, ...)
+{
+    AssertReturn(!(fFlags & ~RTSEMMUTEX_FLAGS_NO_LOCK_VAL), VERR_INVALID_PARAMETER);
+    RT_NOREF3(hClass, uSubClass, pszNameFmt);
+
+    AssertCompile(sizeof(RTSEMMUTEXINTERNAL) > sizeof(void *));
+    PRTSEMMUTEXINTERNAL pThis = (PRTSEMMUTEXINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (!pThis)
+        return VERR_NO_MEMORY;
+
+    pThis->u32Magic = RTSEMMUTEX_MAGIC;
+#ifdef RT_USE_FAST_MUTEX
+    ExInitializeFastMutex(&pThis->Mutex);
+#else
+    KeInitializeMutex(&pThis->Mutex, 0);
+#endif
+
+    *phMutexSem = pThis;
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTSemMutexDestroy(RTSEMMUTEX hMutexSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMMUTEXINTERNAL pThis = (PRTSEMMUTEXINTERNAL)hMutexSem;
+    if (pThis == NIL_RTSEMMUTEX)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, VERR_INVALID_HANDLE);
+
+    /*
+     * Invalidate it and signal the object just in case.
+     */
+    AssertReturn(ASMAtomicCmpXchgU32(&pThis->u32Magic, RTSEMMUTEX_MAGIC_DEAD, RTSEMMUTEX_MAGIC), VERR_INVALID_HANDLE);
+    RTMemFree(pThis);
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Internal worker for RTSemMutexRequest and RTSemMutexRequestNoResume
+ *
+ * @returns IPRT status code.
+ * @param   hMutexSem            The mutex handle.
+ * @param   cMillies            The timeout.
+ * @param   fInterruptible      Whether it's interruptible
+ *                              (RTSemMutexRequestNoResume) or not
+ *                              (RTSemMutexRequest).
+ */
+static int rtSemMutexRequest(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, BOOLEAN fInterruptible)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMMUTEXINTERNAL pThis = (PRTSEMMUTEXINTERNAL)hMutexSem;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, VERR_INVALID_HANDLE);
+
+    /*
+     * Get the mutex.
+     */
+#ifdef RT_USE_FAST_MUTEX
+    AssertMsg(cMillies == RT_INDEFINITE_WAIT, ("timeouts are not supported when using fast mutexes!\n"));
+    ExAcquireFastMutex(&pThis->Mutex);
+    return VINF_SUCCESS;
+
+#else  /* !RT_USE_FAST_MUTEX */
+    NTSTATUS rcNt;
+    if (cMillies == RT_INDEFINITE_WAIT)
+        rcNt = KeWaitForSingleObject(&pThis->Mutex, Executive, KernelMode, fInterruptible, NULL);
+    else
+    {
+        LARGE_INTEGER Timeout;
+        Timeout.QuadPart = -(int64_t)cMillies * 10000;
+        rcNt = KeWaitForSingleObject(&pThis->Mutex, Executive, KernelMode, fInterruptible, &Timeout);
+    }
+    switch (rcNt)
+    {
+        case STATUS_SUCCESS:
+            if (pThis->u32Magic == RTSEMMUTEX_MAGIC)
+                return VINF_SUCCESS;
+            return VERR_SEM_DESTROYED;
+
+        case STATUS_ALERTED:
+        case STATUS_USER_APC:
+            Assert(fInterruptible);
+            return VERR_INTERRUPTED;
+
+        case STATUS_TIMEOUT:
+            return VERR_TIMEOUT;
+
+        default:
+            AssertMsgFailed(("pThis->u32Magic=%RX32 pThis=%p: wait returned %lx!\n",
+                             pThis->u32Magic, pThis, (long)rcNt));
+            return VERR_INTERNAL_ERROR;
+    }
+#endif /* !RT_USE_FAST_MUTEX */
+}
+
+
+RTDECL(int) RTSemMutexRequest(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies)
+{
+    return rtSemMutexRequest(hMutexSem, cMillies, FALSE /*fInterruptible*/);
+}
+
+
+RTDECL(int) RTSemMutexRequestDebug(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RT_NOREF1(uId); RT_SRC_POS_NOREF();
+    return RTSemMutexRequest(hMutexSem, cMillies);
+}
+
+
+RTDECL(int) RTSemMutexRequestNoResume(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies)
+{
+    return rtSemMutexRequest(hMutexSem, cMillies, TRUE /*fInterruptible*/);
+}
+
+
+RTDECL(int) RTSemMutexRequestNoResumeDebug(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RT_NOREF1(uId); RT_SRC_POS_NOREF();
+    return RTSemMutexRequestNoResume(hMutexSem, cMillies);
+}
+
+
+RTDECL(int) RTSemMutexRelease(RTSEMMUTEX hMutexSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMMUTEXINTERNAL pThis = (PRTSEMMUTEXINTERNAL)hMutexSem;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, VERR_INVALID_HANDLE);
+
+    /*
+     * Release the mutex.
+     */
+#ifdef RT_USE_FAST_MUTEX
+    ExReleaseFastMutex(&pThis->Mutex);
+#else
+    KeReleaseMutex(&pThis->Mutex, FALSE /*Wait*/);
+#endif
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(bool) RTSemMutexIsOwned(RTSEMMUTEX hMutexSem)
+{
+    /*
+     * Validate.
+     */
+    RTSEMMUTEXINTERNAL *pThis = hMutexSem;
+    AssertPtrReturn(pThis, false);
+    AssertReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, false);
+
+#ifdef RT_USE_FAST_MUTEX
+    return pThis->Mutex && pThis->Mutex->Owner != NULL;
+#else
+    return KeReadStateMutex(&pThis->Mutex) == 0;
+#endif
+}
+
diff --git a/src/VBox/Runtime/r0drv/nt/spinlock-r0drv-nt.cpp b/src/VBox/Runtime/r0drv/nt/spinlock-r0drv-nt.cpp
new file mode 100644
index 00000000..2398421d
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/spinlock-r0drv-nt.cpp
@@ -0,0 +1,197 @@
+/* $Id: spinlock-r0drv-nt.cpp $ */
+/** @file
+ * IPRT - Spinlocks, Ring-0 Driver, NT.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-nt-kernel.h"
+
+#include <iprt/spinlock.h>
+
+#include <iprt/asm.h>
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+#include <iprt/mem.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+/** Apply the NoIrq hack if defined. */
+#define RTSPINLOCK_NT_HACK_NOIRQ
+
+#ifdef RTSPINLOCK_NT_HACK_NOIRQ
+/** Indicates that the spinlock is taken. */
+# define RTSPINLOCK_NT_HACK_NOIRQ_TAKEN  UINT32(0x00c0ffee)
+/** Indicates that the spinlock is taken. */
+# define RTSPINLOCK_NT_HACK_NOIRQ_FREE   UINT32(0xfe0000fe)
+#endif
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Wrapper for the KSPIN_LOCK type.
+ */
+typedef struct RTSPINLOCKINTERNAL
+{
+    /** Spinlock magic value (RTSPINLOCK_MAGIC). */
+    uint32_t volatile   u32Magic;
+#ifdef RTSPINLOCK_NT_HACK_NOIRQ
+    /** Spinlock hack. */
+    uint32_t volatile   u32Hack;
+#endif
+    /** The saved IRQL. */
+    KIRQL volatile      SavedIrql;
+    /** The saved interrupt flag. */
+    RTCCUINTREG volatile fIntSaved;
+    /** The spinlock creation flags. */
+    uint32_t            fFlags;
+    /** The NT spinlock structure. */
+    KSPIN_LOCK          Spinlock;
+} RTSPINLOCKINTERNAL, *PRTSPINLOCKINTERNAL;
+
+
+RTDECL(int)  RTSpinlockCreate(PRTSPINLOCK pSpinlock, uint32_t fFlags, const char *pszName)
+{
+    AssertReturn(fFlags == RTSPINLOCK_FLAGS_INTERRUPT_SAFE || fFlags == RTSPINLOCK_FLAGS_INTERRUPT_UNSAFE, VERR_INVALID_PARAMETER);
+    RT_NOREF1(pszName);
+
+    /*
+     * Allocate.
+     */
+    Assert(sizeof(RTSPINLOCKINTERNAL) > sizeof(void *));
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (!pThis)
+        return VERR_NO_MEMORY;
+
+    /*
+     * Initialize & return.
+     */
+    pThis->u32Magic     = RTSPINLOCK_MAGIC;
+#ifdef RTSPINLOCK_NT_HACK_NOIRQ
+    pThis->u32Hack      = RTSPINLOCK_NT_HACK_NOIRQ_FREE;
+#endif
+    pThis->SavedIrql    = 0;
+    pThis->fIntSaved    = 0;
+    pThis->fFlags       = fFlags;
+    KeInitializeSpinLock(&pThis->Spinlock);
+
+    *pSpinlock = pThis;
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSpinlockDestroy(RTSPINLOCK Spinlock)
+{
+    /*
+     * Validate input.
+     */
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
+    if (!pThis)
+        return VERR_INVALID_PARAMETER;
+    if (pThis->u32Magic != RTSPINLOCK_MAGIC)
+    {
+        AssertMsgFailed(("Invalid spinlock %p magic=%#x\n", pThis, pThis->u32Magic));
+        return VERR_INVALID_PARAMETER;
+    }
+
+    ASMAtomicIncU32(&pThis->u32Magic);
+    RTMemFree(pThis);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(void) RTSpinlockAcquire(RTSPINLOCK Spinlock)
+{
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
+    AssertMsg(pThis && pThis->u32Magic == RTSPINLOCK_MAGIC, ("magic=%#x\n", pThis->u32Magic));
+
+    KIRQL SavedIrql;
+    if (pThis->fFlags & RTSPINLOCK_FLAGS_INTERRUPT_SAFE)
+    {
+#ifndef RTSPINLOCK_NT_HACK_NOIRQ
+        RTCCUINTREG fIntSaved = ASMGetFlags();
+        ASMIntDisable();
+        KeAcquireSpinLock(&pThis->Spinlock, &SavedIrql);
+#else
+        SavedIrql = KeGetCurrentIrql();
+        if (SavedIrql < DISPATCH_LEVEL)
+        {
+            KeRaiseIrql(DISPATCH_LEVEL, &SavedIrql);
+            Assert(SavedIrql < DISPATCH_LEVEL);
+        }
+        RTCCUINTREG fIntSaved = ASMGetFlags();
+        ASMIntDisable();
+
+        if (!ASMAtomicCmpXchgU32(&pThis->u32Hack, RTSPINLOCK_NT_HACK_NOIRQ_TAKEN, RTSPINLOCK_NT_HACK_NOIRQ_FREE))
+        {
+            while (!ASMAtomicCmpXchgU32(&pThis->u32Hack, RTSPINLOCK_NT_HACK_NOIRQ_TAKEN, RTSPINLOCK_NT_HACK_NOIRQ_FREE))
+                ASMNopPause();
+        }
+#endif
+        pThis->fIntSaved = fIntSaved;
+    }
+    else
+        KeAcquireSpinLock(&pThis->Spinlock, &SavedIrql);
+    pThis->SavedIrql = SavedIrql;
+}
+
+
+RTDECL(void) RTSpinlockRelease(RTSPINLOCK Spinlock)
+{
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
+    AssertMsg(pThis && pThis->u32Magic == RTSPINLOCK_MAGIC, ("magic=%#x\n", pThis->u32Magic));
+
+    KIRQL SavedIrql = pThis->SavedIrql;
+    if (pThis->fFlags & RTSPINLOCK_FLAGS_INTERRUPT_SAFE)
+    {
+        RTCCUINTREG fIntSaved = pThis->fIntSaved;
+        pThis->fIntSaved = 0;
+
+#ifndef RTSPINLOCK_NT_HACK_NOIRQ
+        KeReleaseSpinLock(&pThis->Spinlock, SavedIrql);
+        ASMSetFlags(fIntSaved);
+#else
+        Assert(pThis->u32Hack == RTSPINLOCK_NT_HACK_NOIRQ_TAKEN);
+
+        ASMAtomicWriteU32(&pThis->u32Hack, RTSPINLOCK_NT_HACK_NOIRQ_FREE);
+        ASMSetFlags(fIntSaved);
+        if (SavedIrql < DISPATCH_LEVEL)
+            KeLowerIrql(SavedIrql);
+#endif
+    }
+    else
+        KeReleaseSpinLock(&pThis->Spinlock, SavedIrql);
+}
+
diff --git a/src/VBox/Runtime/r0drv/nt/symdb.h b/src/VBox/Runtime/r0drv/nt/symdb.h
new file mode 100644
index 00000000..7b0468c2
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/symdb.h
@@ -0,0 +1,88 @@
+/* $Id: symdb.h $ */
+/** @file
+ * IPRT - Internal Header for the NT Ring-0 Driver Symbol DB.
+ */
+
+/*
+ * Copyright (C) 2013-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+#ifndef IPRT_INCLUDED_SRC_r0drv_nt_symdb_h
+#define IPRT_INCLUDED_SRC_r0drv_nt_symdb_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <iprt/types.h>
+
+
+/**
+ * NT Version info.
+ */
+typedef struct RTNTSDBOSVER
+{
+    /** The major version number. */
+    uint8_t     uMajorVer;
+    /** The minor version number. */
+    uint8_t     uMinorVer;
+    /** Set if checked build, clear if free (retail) build. */
+    uint8_t     fChecked : 1;
+    /** Set if multi processor kernel. */
+    uint8_t     fSmp : 1;
+    /** The service pack number. */
+    uint8_t     uCsdNo : 6;
+    /** The build number. */
+    uint32_t    uBuildNo;
+} RTNTSDBOSVER;
+/** Pointer to NT version info. */
+typedef RTNTSDBOSVER *PRTNTSDBOSVER;
+/** Pointer to const NT version info. */
+typedef RTNTSDBOSVER const *PCRTNTSDBOSVER;
+
+
+/**
+ * Compare NT OS version structures.
+ *
+ * @retval  0 if equal
+ * @retval  1 if @a pInfo1 is newer/greater than @a pInfo2
+ * @retval  -1 if @a pInfo1 is older/less than @a pInfo2
+ *
+ * @param   pInfo1              The first version info structure.
+ * @param   pInfo2              The second version info structure.
+ */
+DECLINLINE(int) rtNtOsVerInfoCompare(PCRTNTSDBOSVER pInfo1, PCRTNTSDBOSVER pInfo2)
+{
+    if (pInfo1->uMajorVer != pInfo2->uMajorVer)
+        return pInfo1->uMajorVer > pInfo2->uMajorVer ? 1 : -1;
+    if (pInfo1->uMinorVer != pInfo2->uMinorVer)
+        return pInfo1->uMinorVer > pInfo2->uMinorVer ? 1 : -1;
+    if (pInfo1->uBuildNo  != pInfo2->uBuildNo)
+        return pInfo1->uBuildNo  > pInfo2->uBuildNo  ? 1 : -1;
+    if (pInfo1->uCsdNo    != pInfo2->uCsdNo)
+        return pInfo1->uCsdNo    > pInfo2->uCsdNo    ? 1 : -1;
+    if (pInfo1->fSmp      != pInfo2->fSmp)
+        return pInfo1->fSmp      > pInfo2->fSmp      ? 1 : -1;
+    if (pInfo1->fChecked  != pInfo2->fChecked)
+        return pInfo1->fChecked  > pInfo2->fChecked  ? 1 : -1;
+    return 0;
+}
+
+#endif /* !IPRT_INCLUDED_SRC_r0drv_nt_symdb_h */
+
diff --git a/src/VBox/Runtime/r0drv/nt/symdbdata.h b/src/VBox/Runtime/r0drv/nt/symdbdata.h
new file mode 100644
index 00000000..b3492f88
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/symdbdata.h
@@ -0,0 +1,2988 @@
+/* $Id: symdbdata.h $ */
+/** @file
+ * IPRT - NT kernel type helpers - Autogenerated, do NOT edit.
+ */
+
+/*
+ * Copyright (C) 2013-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+#ifndef IPRT_INCLUDED_SRC_r0drv_nt_symdbdata_h
+#define IPRT_INCLUDED_SRC_r0drv_nt_symdbdata_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include "r0drv/nt/symdb.h"
+
+typedef struct RTNTSDBTYPE_KPRCB
+{
+    uint32_t offQuantumEnd;
+    uint32_t cbQuantumEnd;
+    uint32_t offDpcQueueDepth;
+    uint32_t cbDpcQueueDepth;
+    uint32_t offVendorString;
+    uint32_t cbVendorString;
+} RTNTSDBTYPE_KPRCB;
+
+
+typedef struct RTNTSDBSET
+{
+    RTNTSDBOSVER                     OsVerInfo;
+    RTNTSDBTYPE_KPRCB                KPRCB;
+} RTNTSDBSET;
+typedef RTNTSDBSET const *PCRTNTSDBSET;
+
+
+#ifndef RTNTSDB_NO_DATA
+const RTNTSDBSET g_artNtSdbSets[] =
+{
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\w2ksp3sym_nec98\exe\ntkrnlpa.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 3,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\w2ksp3sym_en\exe\ntkrnlpa.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 3,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\w2ksp3sym_en_chk\exe\ntkrnlpa.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 3,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\w2ksp3sym_en_chk\exe\ntoskrnl.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 3,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\w2ksp3sym_nec98\exe\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 3,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\w2ksp3sym_nec98\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 3,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\w2ksp3sym_en\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 3,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\w2ksp3sym_en\exe\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 3,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\w2ksp3sym_en_chk\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 3,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\w2ksp3sym_en_chk\exe\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 3,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\Windows2000-KB891861-x86-Symbols-ENU\symbols\exe\ntkrnlpa.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 4,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\Windows2000-KB891861-x86-Symbols-ENU\symbols\exe\ntoskrnl.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 4,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\w2ksp4sym_en\exe\ntkrnlpa.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 4,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\w2ksp4sym_nec98\exe\ntkrnlpa.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 4,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\Windows2000-KB891861-nec98-Symbols-JPN\symbols\exe\ntkrnlpa.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 4,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\Windows2000-KB891861-nec98-Symbols-JPN\symbols\exe\ntoskrnl.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 4,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\w2ksp4sym_en_chk\exe\ntoskrnl.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 4,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\w2ksp4sym_en_chk\exe\ntkrnlpa.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 4,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\Windows2000-KB891861-x86-Symbols-ENU\symbols\exe\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 4,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\Windows2000-KB891861-x86-Symbols-ENU\symbols\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 4,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\w2ksp4sym_en\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 4,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\w2ksp4sym_en\exe\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 4,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\w2ksp4sym_nec98\exe\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 4,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\w2ksp4sym_nec98\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 4,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\Windows2000-KB891861-nec98-Symbols-JPN\symbols\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 4,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\Windows2000-KB891861-nec98-Symbols-JPN\symbols\exe\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 4,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\w2ksp4sym_en_chk\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 4,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\uold\w2ksp4sym_en_chk\exe\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 4,
+            /* .uBuildNo  = */ 2195,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0750,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x06e8,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x072d,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\windowsxp.x86.fre.rtm.symbols\exe\ntoskrnl.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\windowsxp.x86.fre.rtm.symbols\exe\ntkrnlpa.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\windowsxp.x86.chk.rtm.symbols\exe\ntoskrnl.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\windowsxp.x86.chk.rtm.symbols\exe\ntkrnlpa.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\windowsxp.x86.fre.rtm.symbols\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\windowsxp.x86.fre.rtm.symbols\exe\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\windowsxp.x86.chk.rtm.symbols\exe\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\windowsxp.x86.chk.rtm.symbols\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\xpsp1sym_x86\exe\ntkrnlpa.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\xpsp1sym_x86\exe\ntoskrnl.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\xpsp1sym_x86_chk\exe\ntoskrnl.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\xpsp1sym_x86_chk\exe\ntkrnlpa.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\xpsp1sym_x86\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\xpsp1sym_x86\exe\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\xpsp1sym_x86_chk\exe\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\xpsp1sym_x86_chk\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsXP-KB835935-SP2-slp-Symbols\exe\ntkrnlpa.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 2,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsXP-KB835935-SP2-slp-Symbols\exe\ntoskrnl.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 2,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsXP-KB835935-SP2-Debug-slp-Symbols\exe\ntoskrnl.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 2,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsXP-KB835935-SP2-Debug-slp-Symbols\exe\ntkrnlpa.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 2,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsXP-KB835935-SP2-slp-Symbols\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 2,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsXP-KB835935-SP2-slp-Symbols\exe\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 2,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsXP-KB835935-SP2-Debug-slp-Symbols\exe\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 2,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsXP-KB835935-SP2-Debug-slp-Symbols\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 2,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsXP-KB936929-SP3-x86-symbols-full-ENU\exe\ntoskrnl.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 3,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsXP-KB936929-SP3-x86-symbols-full-ENU\exe\ntkrnlpa.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 3,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsXP-KB936929-SP3-x86-DEBUG-symbols-full-ENU-DEBUG\exe\ntoskrnl.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 3,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsXP-KB936929-SP3-x86-DEBUG-symbols-full-ENU-DEBUG\exe\ntkrnlpa.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 3,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsXP-KB936929-SP3-x86-symbols-full-ENU\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 3,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsXP-KB936929-SP3-x86-symbols-full-ENU\exe\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 3,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsXP-KB936929-SP3-x86-DEBUG-symbols-full-ENU-DEBUG\exe\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 3,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsXP-KB936929-SP3-x86-DEBUG-symbols-full-ENU-DEBUG\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 3,
+            /* .uBuildNo  = */ 2600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x088c,
+            /* .cbQuantumEnd                 = */ 0x0004,
+            /* .offDpcQueueDepth             = */ 0x0870,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0900,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows2003.x86.fre.rtm.symbols\exe\ntoskrnl.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x08c1,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x086c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0a78,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows2003.x86.fre.rtm.symbols\exe\ntkrnlpa.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x08c1,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x086c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0a78,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows2003.x86.chk.rtm.symbols\exe\ntoskrnl.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x08c1,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x086c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0a78,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows2003.x86.chk.rtm.symbols\exe\ntkrnlpa.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x08c1,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x086c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0a78,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows2003.x86.fre.rtm.symbols\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x08c1,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x086c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0a78,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows2003.x86.fre.rtm.symbols\exe\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x08c1,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x086c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0a78,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows2003.x86.chk.rtm.symbols\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x08c1,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x086c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0a78,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows2003.x86.chk.rtm.symbols\exe\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x08c1,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x086c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0a78,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsServer2003-KB933548-v1-x64-symbols-NRL-ENU\exe\ntoskrnl.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1f75,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x1f18,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x22b4,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows2003_sp1.x86.fre.rtm.symbols\exe\ntoskrnl.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0981,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x092c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0b60,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows2003_sp1.x86.fre.rtm.symbols\exe\ntkrnlpa.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0981,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x092c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0b60,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsServer2003-KB933548-v1-x86-symbols-NRL-ENU\exe\ntoskrnl.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0981,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x092c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0b60,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsServer2003-KB933548-v1-x86-symbols-NRL-ENU\exe\ntkrnlpa.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0981,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x092c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0b60,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_AMD64
+    {   /* Source: s:\WinSyms\u\Windows2003_sp1.amd64.fre.rtm.symbols\exe\ntoskrnl.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1f75,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x1f18,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x22b4,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsServer2003-KB933548-v1-x86-symbols-NRL-ENU-DEBUG\exe\ntoskrnl.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0981,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x092c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0b60,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsServer2003-KB933548-v1-x86-symbols-NRL-ENU-DEBUG\exe\ntkrnlpa.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0981,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x092c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0b60,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsServer2003-KB933548-v1-x64-symbols-NRL-ENU-DEBUG\exe\ntoskrnl.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1f75,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x1f18,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x22b4,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows2003_sp1.x86.chk.rtm.symbols\exe\ntoskrnl.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0981,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x092c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0b60,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows2003_sp1.x86.chk.rtm.symbols\exe\ntkrnlpa.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0981,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x092c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0b60,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_AMD64
+    {   /* Source: s:\WinSyms\u\Windows2003_sp1.amd64.chk.rtm.symbols\exe\ntoskrnl.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ false,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1f75,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x1f18,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x22b4,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsServer2003-KB933548-v1-x64-symbols-NRL-ENU\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1f75,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x1f18,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x22b4,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows2003_sp1.x86.fre.rtm.symbols\exe\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0981,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x092c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0b60,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows2003_sp1.x86.fre.rtm.symbols\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0981,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x092c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0b60,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsServer2003-KB933548-v1-x86-symbols-NRL-ENU\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0981,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x092c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0b60,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsServer2003-KB933548-v1-x86-symbols-NRL-ENU\exe\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0981,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x092c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0b60,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_AMD64
+    {   /* Source: s:\WinSyms\u\Windows2003_sp1.amd64.fre.rtm.symbols\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1f75,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x1f18,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x22b4,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsServer2003-KB933548-v1-x86-symbols-NRL-ENU-DEBUG\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0981,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x092c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0b60,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsServer2003-KB933548-v1-x86-symbols-NRL-ENU-DEBUG\exe\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0981,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x092c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0b60,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsServer2003-KB933548-v1-x64-symbols-NRL-ENU-DEBUG\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1f75,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x1f18,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x22b4,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows2003_sp1.x86.chk.rtm.symbols\exe\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0981,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x092c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0b60,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows2003_sp1.x86.chk.rtm.symbols\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x0981,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x092c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x0b60,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_AMD64
+    {   /* Source: s:\WinSyms\u\Windows2003_sp1.amd64.chk.rtm.symbols\exe\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 5,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 3790,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1f75,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x1f18,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x22b4,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsVista.6000.061101-2205.x86fre.Symbols\EXE\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 6000,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x19c1,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x196c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x1bac,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsVista.6000.061101-2205.x86fre.Symbols\EXE\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 6000,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x19c1,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x196c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x1bac,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_AMD64
+    {   /* Source: s:\WinSyms\u\WindowsVista.6000.061101-2205.amd64fre.Symbols\EXE\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 6000,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x3375,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x3318,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x38bc,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsVista.6000.061101-2205.x86chk.Symbols\EXE\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 6000,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x19c1,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x196c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x1bac,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsVista.6000.061101-2205.x86chk.Symbols\EXE\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 6000,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x19c1,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x196c,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x1bac,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_AMD64
+    {   /* Source: s:\WinSyms\u\WindowsVista.6000.061101-2205.amd64chk.Symbols\EXE\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 6000,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x3375,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x3318,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x38bc,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows_Longhorn.6001.080118-1840.x86fre.Symbols\EXE\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 6001,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1a41,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x19ec,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x1c2c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows_Longhorn.6001.080118-1840.x86fre.Symbols\EXE\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 6001,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1a41,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x19ec,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x1c2c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_AMD64
+    {   /* Source: s:\WinSyms\u\Windows_Longhorn.6001.080118-1840.amd64fre.Symbols\EXE\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 6001,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x3475,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x3418,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x399c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows_Longhorn.6001.080118-1840.x86chk.Symbols\EXE\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 6001,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1a41,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x19ec,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x1c2c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows_Longhorn.6001.080118-1840.x86chk.Symbols\EXE\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 6001,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1a41,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x19ec,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x1c2c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_AMD64
+    {   /* Source: s:\WinSyms\u\Windows_Longhorn.6001.080118-1840.amd64chk.Symbols\EXE\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 6001,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x3475,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x3418,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x399c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsVista.6002.090410-1830.x86fre.Symbols\EXE\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 2,
+            /* .uBuildNo  = */ 6002,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1a41,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x19ec,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x1c2c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsVista.6002.090410-1830.x86fre.Symbols\EXE\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 2,
+            /* .uBuildNo  = */ 6002,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1a41,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x19ec,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x1c2c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_AMD64
+    {   /* Source: s:\WinSyms\u\WindowsVista.6002.090410-1830.amd64fre.Symbols\EXE\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 2,
+            /* .uBuildNo  = */ 6002,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x3475,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x3418,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x399c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsVista.6002.090410-1830.x86chk.Symbols\EXE\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 2,
+            /* .uBuildNo  = */ 6002,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1a41,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x19ec,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x1c2c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\WindowsVista.6002.090410-1830.x86chk.Symbols\EXE\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 2,
+            /* .uBuildNo  = */ 6002,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1a41,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x19ec,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x1c2c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_AMD64
+    {   /* Source: s:\WinSyms\u\WindowsVista.6002.090410-1830.amd64chk.Symbols\EXE\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 2,
+            /* .uBuildNo  = */ 6002,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x3475,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x3418,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x399c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows_Win7.7600.16385.090713-1255.X86FRE.Symbols\Symbols\ntkrpamp.pdb\5B308B4ED6464159B87117C711E7340C2\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 7600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1931,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x18ec,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x336c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows_Win7.7600.16385.090713-1255.X86FRE.Symbols\Symbols\ntkrnlmp.pdb\998A3472EEA6405CB8C089DE868F26222\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 7600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1931,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x18ec,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x336c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_AMD64
+    {   /* Source: s:\WinSyms\u\Windows_Win7.7600.16385.090713-1255.X64FRE.Symbols\Symbols\ntkrnlmp.pdb\F8E2A8B5C9B74BF4A6E4A48F180099942\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 7600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x21d9,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x2198,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x4bb8,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows_Win7.7600.16385.090713-1255.X86CHK.Symbols\Symbols\ntkrnlmp.pdb\9E7882E37C3E4AC9BB60F4EAD9DB492A1\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 7600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1931,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x18ec,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x336c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows_Win7.7600.16385.090713-1255.X86CHK.Symbols\Symbols\ntkrpamp.pdb\3269AC66C11B41FC995991F129E95D5C1\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 7600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1931,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x18ec,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x336c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_AMD64
+    {   /* Source: s:\WinSyms\u\Windows_Win7.7600.16385.090713-1255.X64CHK.Symbols\Symbols\ntkrnlmp.pdb\C491E3167994497FA91338D08A7787041\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 7600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x21d9,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x2198,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x4bb8,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows_Win7SP1.7601.17514.101119-1850.X86FRE.Symbols\Symbols\ntkrpamp.pdb\684DA42A30CC450F81C535B4D18944B12\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 7601,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1931,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x18ec,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x336c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows_Win7SP1.7601.17514.101119-1850.X86FRE.Symbols\Symbols\ntkrnlmp.pdb\00625D7D36754CBEBA4533BA9A0F3FE22\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 7601,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1931,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x18ec,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x336c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_AMD64
+    {   /* Source: s:\WinSyms\u\Windows_Win7SP1.7601.17514.101119-1850.AMD64FRE.Symbols\Symbols\ntkrnlmp.pdb\3844DBB920174967BE7AA4A2C20430FA2\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 7601,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x21d9,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x2198,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x4bb8,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows_Win7SP1.7601.17514.101119-1850.X86CHK.Symbols\Symbols\ntkrpamp.pdb\C3355A163C47464183D85DE0B836F83A1\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 7601,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1931,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x18ec,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x336c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows_Win7SP1.7601.17514.101119-1850.X86CHK.Symbols\Symbols\ntkrnlmp.pdb\1477BEA3E003427CB248D5233B0601951\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 7601,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x1931,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x18ec,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x336c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_AMD64
+    {   /* Source: s:\WinSyms\u\Windows_Win7SP1.7601.17514.101119-1850.AMD64CHK.Symbols\Symbols\ntkrnlmp.pdb\FF0DE75C807A4B85A7668D2113A62EF11\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 1,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 1,
+            /* .uBuildNo  = */ 7601,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x21d9,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x2198,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x4bb8,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows_Win8.9200.16384.120725-1247.X86FRE.Symbols\Symbols\ntkrpamp.pdb\E2342527EA214C109CD28A19ED4FBCCE2\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 9200,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x2231,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x21ec,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x3c7c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_AMD64
+    {   /* Source: s:\WinSyms\u\Windows_Win8.9200.16384.120725-1247.x64FRE.Symbols\Symbols\ntkrnlmp.pdb\724821001C1C4A03AED8C4C71C2E8D1D2\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 9200,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x2dd9,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x2d98,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x5948,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\Windows_Win8.9200.16384.120725-1247.X86CHK.Symbols\Symbols\ntkrpamp.pdb\C4F414C9D1854DE495BDAD814A722C4D1\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 9200,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x2231,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x21ec,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x3c7c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_AMD64
+    {   /* Source: s:\WinSyms\u\Windows_Win8.9200.16384.120725-1247.x64CHK.Symbols\Symbols\ntkrnlmp.pdb\FC0361C3243D459496EE02EF1A7ACD271\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 2,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 9200,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x2dd9,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x2d98,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x5948,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\en_windows_8_1_symbols_x86_2712593\ntkrpamp.pdb\9DC1F995475C456C8D1AA9606E3106931\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 3,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 9600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x2239,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x21ec,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x3c7c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_AMD64
+    {   /* Source: s:\WinSyms\u\en_windows_8_1_symbols_x64_2712576\ntkrnlmp.pdb\A9BBA3C139724A738BE17665DB4393CA1\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 3,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 9600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x2de9,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x2d98,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x5958,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\en_windows_8_1_symbols_debug_checked_x86_2712583\ntkrpamp.pdb\77DAB075113647B5888133D3F79B7B171\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 3,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 9600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x2239,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x21ec,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x3c7c,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_AMD64
+    {   /* Source: s:\WinSyms\u\en_windows_8_1_symbols_debug_checked_x64_2712568\ntkrnlmp.pdb\4C5FFE3E839647C5B9471D0C8F9710E11\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 6,
+            /* .uMinorVer = */ 3,
+            /* .fChecked  = */ true,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 9600,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x2de9,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x2d98,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x5958,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_X86
+    {   /* Source: s:\WinSyms\u\en_windows_10_symbols_x86_6903197\ntkrpamp.pdb\3A07902D18FD40CE929445D1777703241\ntkrpamp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 10,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 10240,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x2239,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x21ec,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x3cfc,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_AMD64
+    {   /* Source: s:\WinSyms\u\en_windows_10_symbols_x64_6903177\ntkrnlmp.pdb\C68EE22FDCF6477895C54A862BE165671\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 10,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 10240,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x2de9,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x2d98,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x6258,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+# ifdef RT_ARCH_AMD64
+    {   /* Source: s:\WinSyms\u\en_windows_10_17134_x64_symserv\ntkrnlmp.pdb\1E2C949B928244638C2A7406B9F3824A1\ntkrnlmp.pdb */
+        /*.OsVerInfo = */
+        {
+            /* .uMajorVer = */ 10,
+            /* .uMinorVer = */ 0,
+            /* .fChecked  = */ false,
+            /* .fSmp      = */ true,
+            /* .uCsdNo    = */ 0,
+            /* .uBuildNo  = */ 17134,
+        },
+        /* .KPRCB = */
+        {
+            /* .offQuantumEnd                = */ 0x2e69,
+            /* .cbQuantumEnd                 = */ 0x0001,
+            /* .offDpcQueueDepth             = */ 0x2e18,
+            /* .cbDpcQueueDepth              = */ 0x0004,
+            /* .offVendorString              = */ 0x6290,
+            /* .cbVendorString               = */ 0x000d,
+        },
+    },
+# endif
+};
+#endif /* !RTNTSDB_NO_DATA */
+
+
+#endif /* !IPRT_INCLUDED_SRC_r0drv_nt_symdbdata_h */
+
diff --git a/src/VBox/Runtime/r0drv/nt/the-nt-kernel.h b/src/VBox/Runtime/r0drv/nt/the-nt-kernel.h
new file mode 100644
index 00000000..9dd8c0a0
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/the-nt-kernel.h
@@ -0,0 +1,89 @@
+/* $Id: the-nt-kernel.h $ */
+/** @file
+ * IPRT - Include all necessary headers for the NT kernel.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+#ifndef IPRT_INCLUDED_SRC_r0drv_nt_the_nt_kernel_h
+#define IPRT_INCLUDED_SRC_r0drv_nt_the_nt_kernel_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <iprt/cdefs.h>
+
+#if defined(RT_ARCH_X86) && !defined(NO_INTERLOCKED_INTRINSICS)
+# define NO_INTERLOCKED_INTRINSICS /* avoid trouble */
+#endif
+#if (_MSC_VER >= 1400) && !defined(VBOX_WITH_PATCHED_DDK)
+# include <iprt/asm.h>
+# define _InterlockedExchange           _InterlockedExchange_StupidDDKVsCompilerCrap
+# define _InterlockedExchangeAdd        _InterlockedExchangeAdd_StupidDDKVsCompilerCrap
+# define _InterlockedCompareExchange    _InterlockedCompareExchange_StupidDDKVsCompilerCrap
+# define _InterlockedAddLargeStatistic  _InterlockedAddLargeStatistic_StupidDDKVsCompilerCrap
+# pragma warning(disable : 4163)
+RT_C_DECLS_BEGIN
+# include <iprt/nt/nt.h>
+RT_C_DECLS_END
+# pragma warning(default : 4163)
+# undef  _InterlockedExchange
+# undef  _InterlockedExchangeAdd
+# undef  _InterlockedCompareExchange
+# undef  _InterlockedAddLargeStatistic
+#else
+RT_C_DECLS_BEGIN
+# include <iprt/nt/nt.h>
+RT_C_DECLS_END
+#endif
+
+#include <memory.h>
+#if !defined(RT_OS_WINDOWS)
+# error "RT_OS_WINDOWS must be defined!"
+#endif
+
+#include <iprt/param.h>
+#ifndef PAGE_OFFSET_MASK
+# define PAGE_OFFSET_MASK (PAGE_SIZE - 1)
+#endif
+
+/* Missing if we're compiling against older WDKs. */
+#ifndef NonPagedPoolNx
+# define NonPagedPoolNx     ((POOL_TYPE)512)
+#endif
+
+/*
+ * When targeting NT4 we have to undo some of the nice macros
+ * installed by the later DDKs.
+ */
+#undef ExAllocatePool
+#undef ExFreePool
+
+/** @def IPRT_NT_POOL_TAG
+ * Tag to use with the NT Pool APIs.
+ * In memory and in the various windbg tools it appears in the reverse order of
+ * what it is given as here, so it'll read "IPRT".
+ */
+#define IPRT_NT_POOL_TAG    'TRPI'
+
+#endif /* !IPRT_INCLUDED_SRC_r0drv_nt_the_nt_kernel_h */
+
diff --git a/src/VBox/Runtime/r0drv/nt/thread-r0drv-nt.cpp b/src/VBox/Runtime/r0drv/nt/thread-r0drv-nt.cpp
new file mode 100644
index 00000000..1020a51b
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/thread-r0drv-nt.cpp
@@ -0,0 +1,228 @@
+/* $Id: thread-r0drv-nt.cpp $ */
+/** @file
+ * IPRT - Threads, Ring-0 Driver, NT.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-nt-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/thread.h>
+
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+#include <iprt/mp.h>
+#include "internal-r0drv-nt.h"
+
+
+
+RTDECL(RTNATIVETHREAD) RTThreadNativeSelf(void)
+{
+    return (RTNATIVETHREAD)PsGetCurrentThread();
+}
+
+
+static int rtR0ThreadNtSleepCommon(RTMSINTERVAL cMillies)
+{
+    LARGE_INTEGER Interval;
+    Interval.QuadPart = -(int64_t)cMillies * 10000;
+    NTSTATUS rcNt = KeDelayExecutionThread(KernelMode, TRUE, &Interval);
+    switch (rcNt)
+    {
+        case STATUS_SUCCESS:
+            return VINF_SUCCESS;
+        case STATUS_ALERTED:
+        case STATUS_USER_APC:
+            return VERR_INTERRUPTED;
+        default:
+            return RTErrConvertFromNtStatus(rcNt);
+    }
+}
+
+
+RTDECL(int)   RTThreadSleep(RTMSINTERVAL cMillies)
+{
+    return rtR0ThreadNtSleepCommon(cMillies);
+}
+
+
+RTDECL(bool) RTThreadYield(void)
+{
+    return ZwYieldExecution() != STATUS_NO_YIELD_PERFORMED;
+}
+
+
+RTDECL(bool) RTThreadPreemptIsEnabled(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD); RT_NOREF1(hThread);
+    KIRQL Irql = KeGetCurrentIrql();
+    if (Irql > APC_LEVEL)
+        return false;
+    if (!ASMIntAreEnabled())
+        return false;
+    return true;
+}
+
+
+RTDECL(bool) RTThreadPreemptIsPending(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD); RT_NOREF1(hThread);
+
+    /*
+     * The KeShouldYieldProcessor API introduced in Windows 10 looks like exactly
+     * what we want.  But of course there is a snag.  It may return with interrupts
+     * enabled when called with them disabled.  Let's just hope it doesn't get upset
+     * by disabled interrupts in other ways...
+     */
+    if (g_pfnrtKeShouldYieldProcessor)
+    {
+        RTCCUINTREG fSavedFlags = ASMGetFlags();
+        bool fReturn = g_pfnrtKeShouldYieldProcessor() != FALSE;
+        ASMSetFlags(fSavedFlags);
+        return fReturn;
+    }
+
+    /*
+     * Fallback approach for pre W10 kernels.
+     *
+     * If W10 is anything to go by, we should also check and yield when:
+     *      - pPrcb->NextThread != NULL && pPrcb->NextThread != pPrcb->CurrentThread
+     *        when QuantumEnd is zero.
+     *      - pPrcb->DpcRequestSummary & 1
+     *      - pPrcb->DpcRequestSummary & 0x1e
+     */
+
+    /*
+     * Read the globals and check if they are useful.
+     */
+/** @todo Should we check KPRCB.InterruptRequest and KPRCB.DpcInterruptRequested (older kernels).  */
+    uint32_t const offQuantumEnd     = g_offrtNtPbQuantumEnd;
+    uint32_t const cbQuantumEnd      = g_cbrtNtPbQuantumEnd;
+    uint32_t const offDpcQueueDepth  = g_offrtNtPbDpcQueueDepth;
+    if (!offQuantumEnd && !cbQuantumEnd && !offDpcQueueDepth)
+        return false;
+    Assert((offQuantumEnd && cbQuantumEnd) || (!offQuantumEnd && !cbQuantumEnd));
+
+    /*
+     * Disable interrupts so we won't be messed around.
+     */
+    bool            fPending;
+    RTCCUINTREG     fSavedFlags  = ASMIntDisableFlags();
+
+#ifdef RT_ARCH_X86
+    PKPCR       pPcr   = (PKPCR)__readfsdword(RT_UOFFSETOF(KPCR,SelfPcr));
+    uint8_t    *pbPrcb = (uint8_t *)pPcr->Prcb;
+
+#elif defined(RT_ARCH_AMD64)
+    /* HACK ALERT! The offset is from windbg/vista64. */
+    PKPCR       pPcr   = (PKPCR)__readgsqword(RT_UOFFSETOF(KPCR,Self));
+    uint8_t    *pbPrcb = (uint8_t *)pPcr->CurrentPrcb;
+
+#else
+# error "port me"
+#endif
+
+    /* Check QuantumEnd. */
+    if (cbQuantumEnd == 1)
+    {
+        uint8_t volatile *pbQuantumEnd = (uint8_t volatile *)(pbPrcb + offQuantumEnd);
+        fPending = *pbQuantumEnd == TRUE;
+    }
+    else if (cbQuantumEnd == sizeof(uint32_t))
+    {
+        uint32_t volatile *pu32QuantumEnd = (uint32_t volatile *)(pbPrcb + offQuantumEnd);
+        fPending = *pu32QuantumEnd != 0;
+    }
+    else
+        fPending = false;
+
+    /* Check DpcQueueDepth. */
+    if (    !fPending
+        &&  offDpcQueueDepth)
+    {
+        uint32_t volatile *pu32DpcQueueDepth = (uint32_t volatile *)(pbPrcb + offDpcQueueDepth);
+        fPending = *pu32DpcQueueDepth > 0;
+    }
+
+    ASMSetFlags(fSavedFlags);
+    return fPending;
+}
+
+
+RTDECL(bool) RTThreadPreemptIsPendingTrusty(void)
+{
+    if (g_pfnrtKeShouldYieldProcessor)
+        return true;
+#if 0 /** @todo RTThreadPreemptIsPending isn't good enough on w7 and possibly elsewhere. */
+    /* RTThreadPreemptIsPending is only reliable if we've got both offsets and size. */
+    return g_offrtNtPbQuantumEnd    != 0
+        && g_cbrtNtPbQuantumEnd     != 0
+        && g_offrtNtPbDpcQueueDepth != 0;
+#else
+    return false;
+#endif
+}
+
+
+RTDECL(bool) RTThreadPreemptIsPossible(void)
+{
+    /* yes, kernel preemption is possible. */
+    return true;
+}
+
+
+RTDECL(void) RTThreadPreemptDisable(PRTTHREADPREEMPTSTATE pState)
+{
+    AssertPtr(pState);
+    Assert(pState->uchOldIrql == 255);
+    Assert(KeGetCurrentIrql() <= DISPATCH_LEVEL);
+
+    KeRaiseIrql(DISPATCH_LEVEL, &pState->uchOldIrql);
+    RT_ASSERT_PREEMPT_CPUID_DISABLE(pState);
+}
+
+
+RTDECL(void) RTThreadPreemptRestore(PRTTHREADPREEMPTSTATE pState)
+{
+    AssertPtr(pState);
+
+    RT_ASSERT_PREEMPT_CPUID_RESTORE(pState);
+    KeLowerIrql(pState->uchOldIrql);
+    pState->uchOldIrql = 255;
+}
+
+
+RTDECL(bool) RTThreadIsInInterrupt(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD); NOREF(hThread);
+
+    KIRQL CurIrql = KeGetCurrentIrql();
+    return CurIrql > PASSIVE_LEVEL; /** @todo Is there a more correct way? */
+}
+
diff --git a/src/VBox/Runtime/r0drv/nt/thread2-r0drv-nt.cpp b/src/VBox/Runtime/r0drv/nt/thread2-r0drv-nt.cpp
new file mode 100644
index 00000000..21d74e06
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/thread2-r0drv-nt.cpp
@@ -0,0 +1,157 @@
+/* $Id: thread2-r0drv-nt.cpp $ */
+/** @file
+ * IPRT - Threads (Part 2), Ring-0 Driver, NT.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-nt-kernel.h"
+
+#include <iprt/thread.h>
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+
+#include "internal/thread.h"
+
+
+DECLHIDDEN(int) rtThreadNativeInit(void)
+{
+    /* No TLS in Ring-0. :-/ */
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(RTTHREAD) RTThreadSelf(void)
+{
+    return rtThreadGetByNative((RTNATIVETHREAD)PsGetCurrentThread());
+}
+
+
+DECLHIDDEN(int) rtThreadNativeSetPriority(PRTTHREADINT pThread, RTTHREADTYPE enmType)
+{
+    /*
+     * Convert the IPRT priority type to NT priority.
+     *
+     * The NT priority is in the range 0..32, with realtime starting
+     * at 16 and the default for user processes at 8. (Should try find
+     * the appropriate #defines for some of this...)
+     */
+    KPRIORITY Priority;
+    switch (enmType)
+    {
+        case RTTHREADTYPE_INFREQUENT_POLLER:    Priority = 6; break;
+        case RTTHREADTYPE_EMULATION:            Priority = 7; break;
+        case RTTHREADTYPE_DEFAULT:              Priority = 8; break;
+        case RTTHREADTYPE_MSG_PUMP:             Priority = 9; break;
+        case RTTHREADTYPE_IO:                   Priority = LOW_REALTIME_PRIORITY; break;
+        case RTTHREADTYPE_TIMER:                Priority = MAXIMUM_PRIORITY; break;
+
+        default:
+            AssertMsgFailed(("enmType=%d\n", enmType));
+            return VERR_INVALID_PARAMETER;
+    }
+
+    /*
+     * Do the actual modification.
+     */
+    /*KPRIORITY oldPririty = */KeSetPriorityThread((PKTHREAD)pThread->Core.Key, Priority);
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtThreadNativeAdopt(PRTTHREADINT pThread)
+{
+    RT_NOREF1(pThread);
+    return VERR_NOT_IMPLEMENTED;
+}
+
+
+DECLHIDDEN(void) rtThreadNativeWaitKludge(PRTTHREADINT pThread)
+{
+    PVOID pvThreadObj = pThread->Core.Key;
+    NTSTATUS rcNt = KeWaitForSingleObject(pvThreadObj, Executive, KernelMode, FALSE, NULL);
+    AssertMsg(rcNt == STATUS_SUCCESS, ("rcNt=%#x\n", rcNt)); RT_NOREF1(rcNt);
+}
+
+
+DECLHIDDEN(void) rtThreadNativeDestroy(PRTTHREADINT pThread)
+{
+    NOREF(pThread);
+}
+
+
+/**
+ * Native kernel thread wrapper function.
+ *
+ * This will forward to rtThreadMain and do termination upon return.
+ *
+ * @param pvArg         Pointer to the argument package.
+ */
+static VOID rtThreadNativeMain(PVOID pvArg)
+{
+    PETHREAD Self = PsGetCurrentThread();
+    PRTTHREADINT pThread = (PRTTHREADINT)pvArg;
+
+    rtThreadMain(pThread, (RTNATIVETHREAD)Self, &pThread->szName[0]);
+
+    ObDereferenceObject(Self); /* the rtThreadNativeCreate ref. */
+}
+
+
+DECLHIDDEN(int) rtThreadNativeCreate(PRTTHREADINT pThreadInt, PRTNATIVETHREAD pNativeThread)
+{
+    /*
+     * PsCreateSysemThread create a thread an give us a handle in return.
+     * We requests the object for that handle and then close it, so what
+     * we keep around is the pointer to the thread object and not a handle.
+     * The thread will dereference the object before returning.
+     */
+    HANDLE hThread = NULL;
+    OBJECT_ATTRIBUTES ObjAttr;
+    InitializeObjectAttributes(&ObjAttr, NULL, OBJ_KERNEL_HANDLE, NULL, NULL);
+    NTSTATUS rc = PsCreateSystemThread(&hThread,
+                                       THREAD_ALL_ACCESS,
+                                       &ObjAttr,
+                                       NULL /* ProcessHandle - kernel */,
+                                       NULL /* ClientID - kernel */,
+                                       rtThreadNativeMain,
+                                       pThreadInt);
+    if (NT_SUCCESS(rc))
+    {
+        PVOID pvThreadObj;
+        rc = ObReferenceObjectByHandle(hThread, THREAD_ALL_ACCESS, NULL /* object type */,
+                                       KernelMode, &pvThreadObj, NULL /* handle info */);
+        if (NT_SUCCESS(rc))
+        {
+            ZwClose(hThread);
+            *pNativeThread = (RTNATIVETHREAD)pvThreadObj;
+        }
+        else
+            AssertMsgFailed(("%#x\n", rc));
+    }
+    return RTErrConvertFromNtStatus(rc);
+}
+
diff --git a/src/VBox/Runtime/r0drv/nt/time-r0drv-nt.cpp b/src/VBox/Runtime/r0drv/nt/time-r0drv-nt.cpp
new file mode 100644
index 00000000..65a64af1
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/time-r0drv-nt.cpp
@@ -0,0 +1,149 @@
+/* $Id: time-r0drv-nt.cpp $ */
+/** @file
+ * IPRT - Time, Ring-0 Driver, Nt.
+ */
+
+/*
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define LOG_GROUP RTLOGGROUP_TIME
+#include "the-nt-kernel.h"
+#include "internal-r0drv-nt.h"
+#include <iprt/time.h>
+
+
+/*
+ * The KeQueryTickCount macro isn't compatible with NT 3.1, use the
+ * exported KPI instead.
+ */
+#ifdef RT_ARCH_X86
+# undef KeQueryTickCount
+extern "C" NTKERNELAPI void NTAPI KeQueryTickCount(PLARGE_INTEGER);
+#endif
+
+
+DECLINLINE(uint64_t) rtTimeGetSystemNanoTS(void)
+{
+    /*
+     * Note! The time source we use here must be exactly the same as in
+     *       the ring-3 code!
+     *
+     * Using interrupt time is the simplest and requires the least calculation.
+     * It is also accounting for suspended time. Unfortuantely, there is no
+     * ring-3 for reading it... but that won't stop us.
+     *
+     * Using the tick count is problematic in ring-3 on older windows version
+     * as we can only get the 32-bit tick value, i.e. we'll roll over sooner or
+     * later.
+     */
+#if 1
+    /* Interrupt time. */
+    LARGE_INTEGER InterruptTime;
+    if (g_pfnrtKeQueryInterruptTimePrecise)
+    {
+        ULONG64 QpcTsIgnored;
+        InterruptTime.QuadPart = g_pfnrtKeQueryInterruptTimePrecise(&QpcTsIgnored);
+    }
+# ifdef RT_ARCH_X86
+    else if (g_pfnrtKeQueryInterruptTime) /* W2K+ */
+        InterruptTime.QuadPart = g_pfnrtKeQueryInterruptTime();
+    else if (g_uRtNtVersion >= RTNT_MAKE_VERSION(3, 50))
+    {
+        /* NT 3.50 and later, also pre-init: Use the user shared data. */
+        do
+        {
+            InterruptTime.HighPart = ((KUSER_SHARED_DATA volatile *)SharedUserData)->InterruptTime.High1Time;
+            InterruptTime.LowPart  = ((KUSER_SHARED_DATA volatile *)SharedUserData)->InterruptTime.LowPart;
+        } while (((KUSER_SHARED_DATA volatile *)SharedUserData)->InterruptTime.High2Time != InterruptTime.HighPart);
+    }
+    else
+    {
+        /*
+         * There is no KUSER_SHARED_DATA structure on NT 3.1, so we have no choice
+         * but to use the tick count.  We must also avoid the KeQueryTickCount macro
+         * in the WDK, since NT 3.1 doesn't have the KeTickCount data export either (see above).
+         */
+        static ULONG volatile s_uTimeIncrement = 0;
+        ULONG uTimeIncrement = s_uTimeIncrement;
+        if (!uTimeIncrement)
+        {
+            uTimeIncrement = KeQueryTimeIncrement();
+            Assert(uTimeIncrement != 0);
+            Assert(uTimeIncrement * 100 / 100 == uTimeIncrement);
+            uTimeIncrement *= 100;
+            s_uTimeIncrement = uTimeIncrement;
+        }
+
+        KeQueryTickCount(&InterruptTime);
+        return (uint64_t)InterruptTime.QuadPart * uTimeIncrement;
+    }
+# else
+    else
+        InterruptTime.QuadPart = KeQueryInterruptTime(); /* Macro on AMD64. */
+# endif
+    return (uint64_t)InterruptTime.QuadPart * 100;
+#else
+    /* Tick count.  Works all the way back to NT 3.1 with #undef above.  */
+    LARGE_INTEGER Tick;
+    KeQueryTickCount(&Tick);
+    return (uint64_t)Tick.QuadPart * KeQueryTimeIncrement() * 100;
+#endif
+}
+
+
+RTDECL(uint64_t) RTTimeNanoTS(void)
+{
+    return rtTimeGetSystemNanoTS();
+}
+
+
+RTDECL(uint64_t) RTTimeMilliTS(void)
+{
+    return rtTimeGetSystemNanoTS() / RT_NS_1MS;
+}
+
+
+RTDECL(uint64_t) RTTimeSystemNanoTS(void)
+{
+    return rtTimeGetSystemNanoTS();
+}
+
+
+RTDECL(uint64_t) RTTimeSystemMilliTS(void)
+{
+    return rtTimeGetSystemNanoTS() / RT_NS_1MS;
+}
+
+
+RTDECL(PRTTIMESPEC) RTTimeNow(PRTTIMESPEC pTime)
+{
+    LARGE_INTEGER SystemTime;
+    if (g_pfnrtKeQuerySystemTimePrecise)
+        g_pfnrtKeQuerySystemTimePrecise(&SystemTime);
+    else
+        KeQuerySystemTime(&SystemTime); /* Macro on AMD64, export on X86.  */
+    return RTTimeSpecSetNtTime(pTime, SystemTime.QuadPart);
+}
+
diff --git a/src/VBox/Runtime/r0drv/nt/timer-r0drv-nt.cpp b/src/VBox/Runtime/r0drv/nt/timer-r0drv-nt.cpp
new file mode 100644
index 00000000..c153175f
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/timer-r0drv-nt.cpp
@@ -0,0 +1,597 @@
+/* $Id: timer-r0drv-nt.cpp $ */
+/** @file
+ * IPRT - Timers, Ring-0 Driver, NT.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-nt-kernel.h"
+
+#include <iprt/timer.h>
+#include <iprt/mp.h>
+#include <iprt/cpuset.h>
+#include <iprt/err.h>
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/mem.h>
+#include <iprt/thread.h>
+
+#include "internal-r0drv-nt.h"
+#include "internal/magics.h"
+
+/** This seems to provide better accuracy. */
+#define RTR0TIMER_NT_MANUAL_RE_ARM 1
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * A sub timer structure.
+ *
+ * This is used for keeping the per-cpu tick and DPC object.
+ */
+typedef struct RTTIMERNTSUBTIMER
+{
+    /** The tick counter. */
+    uint64_t                iTick;
+    /** Pointer to the parent timer. */
+    PRTTIMER                pParent;
+    /** Thread active executing the worker function, NIL if inactive. */
+    RTNATIVETHREAD volatile hActiveThread;
+    /** The NT DPC object. */
+    KDPC                    NtDpc;
+} RTTIMERNTSUBTIMER;
+/** Pointer to a NT sub-timer structure. */
+typedef RTTIMERNTSUBTIMER *PRTTIMERNTSUBTIMER;
+
+/**
+ * The internal representation of an Linux timer handle.
+ */
+typedef struct RTTIMER
+{
+    /** Magic.
+     * This is RTTIMER_MAGIC, but changes to something else before the timer
+     * is destroyed to indicate clearly that thread should exit. */
+    uint32_t volatile       u32Magic;
+    /** Suspend count down for single shot omnit timers. */
+    int32_t volatile        cOmniSuspendCountDown;
+    /** Flag indicating the timer is suspended. */
+    bool volatile           fSuspended;
+    /** Whether the timer must run on one specific CPU or not. */
+    bool                    fSpecificCpu;
+    /** Whether the timer must run on all CPUs or not. */
+    bool                    fOmniTimer;
+    /** The CPU it must run on if fSpecificCpu is set.
+     * The master CPU for an omni-timer. */
+    RTCPUID                 idCpu;
+    /** Callback. */
+    PFNRTTIMER              pfnTimer;
+    /** User argument. */
+    void                   *pvUser;
+    /** The timer interval. 0 if one-shot. */
+    uint64_t                u64NanoInterval;
+#ifdef RTR0TIMER_NT_MANUAL_RE_ARM
+    /** The desired NT time of the first tick. */
+    uint64_t                uNtStartTime;
+#endif
+    /** The Nt timer object. */
+    KTIMER                  NtTimer;
+    /** The number of sub-timers. */
+    RTCPUID                 cSubTimers;
+    /** Sub-timers.
+     * Normally there is just one, but for RTTIMER_FLAGS_CPU_ALL this will contain
+     * an entry for all possible cpus. In that case the index will be the same as
+     * for the RTCpuSet. */
+    RTTIMERNTSUBTIMER       aSubTimers[1];
+} RTTIMER;
+
+
+#ifdef RTR0TIMER_NT_MANUAL_RE_ARM
+/**
+ * Get current NT interrupt time.
+ * @return NT interrupt time
+ */
+static uint64_t rtTimerNtQueryInterruptTime(void)
+{
+# ifdef RT_ARCH_AMD64
+    return KeQueryInterruptTime(); /* macro */
+# else
+    if (g_pfnrtKeQueryInterruptTime)
+        return g_pfnrtKeQueryInterruptTime();
+
+    /* NT4 */
+    ULARGE_INTEGER InterruptTime;
+    do
+    {
+        InterruptTime.HighPart = ((KUSER_SHARED_DATA volatile *)SharedUserData)->InterruptTime.High1Time;
+        InterruptTime.LowPart  = ((KUSER_SHARED_DATA volatile *)SharedUserData)->InterruptTime.LowPart;
+    } while (((KUSER_SHARED_DATA volatile *)SharedUserData)->InterruptTime.High2Time != (LONG)InterruptTime.HighPart);
+    return InterruptTime.QuadPart;
+# endif
+}
+#endif /* RTR0TIMER_NT_MANUAL_RE_ARM */
+
+
+/**
+ * Manually re-arms an internval timer.
+ *
+ * Turns out NT doesn't necessarily do a very good job at re-arming timers
+ * accurately.
+ *
+ * @param   pTimer              The timer.
+ * @param   iTick               The current timer tick.
+ * @param   pMasterDpc          The master DPC.
+ */
+DECLINLINE(void) rtTimerNtRearmInternval(PRTTIMER pTimer, uint64_t iTick, PKDPC pMasterDpc)
+{
+#ifdef RTR0TIMER_NT_MANUAL_RE_ARM
+    Assert(pTimer->u64NanoInterval);
+    RT_NOREF1(pMasterDpc);
+
+    uint64_t uNtNext = (iTick * pTimer->u64NanoInterval) / 100 - 10; /* 1us fudge */
+    LARGE_INTEGER DueTime;
+    DueTime.QuadPart = rtTimerNtQueryInterruptTime() - pTimer->uNtStartTime;
+    if (DueTime.QuadPart < 0)
+        DueTime.QuadPart = 0;
+    if ((uint64_t)DueTime.QuadPart < uNtNext)
+        DueTime.QuadPart -= uNtNext;
+    else
+        DueTime.QuadPart = -2500; /* 0.25ms */
+
+    KeSetTimerEx(&pTimer->NtTimer, DueTime, 0, &pTimer->aSubTimers[0].NtDpc);
+#else
+    RT_NOREF3(pTimer, iTick, pMasterDpc);
+#endif
+}
+
+
+/**
+ * Timer callback function for the non-omni timers.
+ *
+ * @returns HRTIMER_NORESTART or HRTIMER_RESTART depending on whether it's a one-shot or interval timer.
+ * @param   pDpc                Pointer to the DPC.
+ * @param   pvUser              Pointer to our internal timer structure.
+ * @param   SystemArgument1     Some system argument.
+ * @param   SystemArgument2     Some system argument.
+ */
+static void _stdcall rtTimerNtSimpleCallback(IN PKDPC pDpc, IN PVOID pvUser, IN PVOID SystemArgument1, IN PVOID SystemArgument2)
+{
+    PRTTIMER pTimer = (PRTTIMER)pvUser;
+    AssertPtr(pTimer);
+#ifdef RT_STRICT
+    if (KeGetCurrentIrql() < DISPATCH_LEVEL)
+        RTAssertMsg2Weak("rtTimerNtSimpleCallback: Irql=%d expected >=%d\n", KeGetCurrentIrql(), DISPATCH_LEVEL);
+#endif
+
+    /*
+     * Check that we haven't been suspended before doing the callout.
+     */
+    if (    !ASMAtomicUoReadBool(&pTimer->fSuspended)
+        &&  pTimer->u32Magic == RTTIMER_MAGIC)
+    {
+        ASMAtomicWriteHandle(&pTimer->aSubTimers[0].hActiveThread, RTThreadNativeSelf());
+
+        if (!pTimer->u64NanoInterval)
+            ASMAtomicWriteBool(&pTimer->fSuspended, true);
+        uint64_t iTick = ++pTimer->aSubTimers[0].iTick;
+        if (pTimer->u64NanoInterval)
+            rtTimerNtRearmInternval(pTimer, iTick, &pTimer->aSubTimers[0].NtDpc);
+        pTimer->pfnTimer(pTimer, pTimer->pvUser, iTick);
+
+        ASMAtomicWriteHandle(&pTimer->aSubTimers[0].hActiveThread, NIL_RTNATIVETHREAD);
+    }
+
+    NOREF(pDpc); NOREF(SystemArgument1); NOREF(SystemArgument2);
+}
+
+
+/**
+ * The slave DPC callback for an omni timer.
+ *
+ * @param   pDpc                The DPC object.
+ * @param   pvUser              Pointer to the sub-timer.
+ * @param   SystemArgument1     Some system stuff.
+ * @param   SystemArgument2     Some system stuff.
+ */
+static void _stdcall rtTimerNtOmniSlaveCallback(IN PKDPC pDpc, IN PVOID pvUser, IN PVOID SystemArgument1, IN PVOID SystemArgument2)
+{
+    PRTTIMERNTSUBTIMER pSubTimer = (PRTTIMERNTSUBTIMER)pvUser;
+    PRTTIMER pTimer = pSubTimer->pParent;
+
+    AssertPtr(pTimer);
+#ifdef RT_STRICT
+    if (KeGetCurrentIrql() < DISPATCH_LEVEL)
+        RTAssertMsg2Weak("rtTimerNtOmniSlaveCallback: Irql=%d expected >=%d\n", KeGetCurrentIrql(), DISPATCH_LEVEL);
+    int iCpuSelf = RTMpCpuIdToSetIndex(RTMpCpuId());
+    if (pSubTimer - &pTimer->aSubTimers[0] != iCpuSelf)
+        RTAssertMsg2Weak("rtTimerNtOmniSlaveCallback: iCpuSelf=%d pSubTimer=%p / %d\n", iCpuSelf, pSubTimer, pSubTimer - &pTimer->aSubTimers[0]);
+#endif
+
+    /*
+     * Check that we haven't been suspended before doing the callout.
+     */
+    if (    !ASMAtomicUoReadBool(&pTimer->fSuspended)
+        &&  pTimer->u32Magic == RTTIMER_MAGIC)
+    {
+        ASMAtomicWriteHandle(&pSubTimer->hActiveThread, RTThreadNativeSelf());
+
+        if (!pTimer->u64NanoInterval)
+            if (ASMAtomicDecS32(&pTimer->cOmniSuspendCountDown) <= 0)
+                ASMAtomicWriteBool(&pTimer->fSuspended, true);
+
+        pTimer->pfnTimer(pTimer, pTimer->pvUser, ++pSubTimer->iTick);
+
+        ASMAtomicWriteHandle(&pSubTimer->hActiveThread, NIL_RTNATIVETHREAD);
+    }
+
+    NOREF(pDpc); NOREF(SystemArgument1); NOREF(SystemArgument2);
+}
+
+
+/**
+ * The timer callback for an omni-timer.
+ *
+ * This is responsible for queueing the DPCs for the other CPUs and
+ * perform the callback on the CPU on which it is called.
+ *
+ * @param   pDpc                The DPC object.
+ * @param   pvUser              Pointer to the sub-timer.
+ * @param   SystemArgument1     Some system stuff.
+ * @param   SystemArgument2     Some system stuff.
+ */
+static void _stdcall rtTimerNtOmniMasterCallback(IN PKDPC pDpc, IN PVOID pvUser, IN PVOID SystemArgument1, IN PVOID SystemArgument2)
+{
+    PRTTIMERNTSUBTIMER pSubTimer = (PRTTIMERNTSUBTIMER)pvUser;
+    PRTTIMER pTimer = pSubTimer->pParent;
+    int iCpuSelf = RTMpCpuIdToSetIndex(RTMpCpuId());
+
+    AssertPtr(pTimer);
+#ifdef RT_STRICT
+    if (KeGetCurrentIrql() < DISPATCH_LEVEL)
+        RTAssertMsg2Weak("rtTimerNtOmniMasterCallback: Irql=%d expected >=%d\n", KeGetCurrentIrql(), DISPATCH_LEVEL);
+    if (pSubTimer - &pTimer->aSubTimers[0] != iCpuSelf)
+        RTAssertMsg2Weak("rtTimerNtOmniMasterCallback: iCpuSelf=%d pSubTimer=%p / %d\n", iCpuSelf, pSubTimer, pSubTimer - &pTimer->aSubTimers[0]);
+#endif
+
+    /*
+     * Check that we haven't been suspended before scheduling the other DPCs
+     * and doing the callout.
+     */
+    if (    !ASMAtomicUoReadBool(&pTimer->fSuspended)
+        &&  pTimer->u32Magic == RTTIMER_MAGIC)
+    {
+        RTCPUSET    OnlineSet;
+        RTMpGetOnlineSet(&OnlineSet);
+
+        ASMAtomicWriteHandle(&pSubTimer->hActiveThread, RTThreadNativeSelf());
+
+        if (pTimer->u64NanoInterval)
+        {
+            /*
+             * Recurring timer.
+             */
+            for (int iCpu = 0; iCpu < RTCPUSET_MAX_CPUS; iCpu++)
+                if (    RTCpuSetIsMemberByIndex(&OnlineSet, iCpu)
+                    &&  iCpuSelf != iCpu)
+                    KeInsertQueueDpc(&pTimer->aSubTimers[iCpu].NtDpc, 0, 0);
+
+            uint64_t iTick = ++pSubTimer->iTick;
+            rtTimerNtRearmInternval(pTimer, iTick, &pTimer->aSubTimers[RTMpCpuIdToSetIndex(pTimer->idCpu)].NtDpc);
+            pTimer->pfnTimer(pTimer, pTimer->pvUser, iTick);
+        }
+        else
+        {
+            /*
+             * Single shot timers gets complicated wrt to fSuspended maintance.
+             */
+            uint32_t cCpus = 0;
+            for (int iCpu = 0; iCpu < RTCPUSET_MAX_CPUS; iCpu++)
+                if (RTCpuSetIsMemberByIndex(&OnlineSet, iCpu))
+                    cCpus++;
+            ASMAtomicAddS32(&pTimer->cOmniSuspendCountDown, cCpus);
+
+            for (int iCpu = 0; iCpu < RTCPUSET_MAX_CPUS; iCpu++)
+                if (    RTCpuSetIsMemberByIndex(&OnlineSet, iCpu)
+                    &&  iCpuSelf != iCpu)
+                    if (!KeInsertQueueDpc(&pTimer->aSubTimers[iCpu].NtDpc, 0, 0))
+                        ASMAtomicDecS32(&pTimer->cOmniSuspendCountDown); /* already queued and counted. */
+
+            if (ASMAtomicDecS32(&pTimer->cOmniSuspendCountDown) <= 0)
+                ASMAtomicWriteBool(&pTimer->fSuspended, true);
+
+            pTimer->pfnTimer(pTimer, pTimer->pvUser, ++pSubTimer->iTick);
+        }
+
+        ASMAtomicWriteHandle(&pSubTimer->hActiveThread, NIL_RTNATIVETHREAD);
+    }
+
+    NOREF(pDpc); NOREF(SystemArgument1); NOREF(SystemArgument2);
+}
+
+
+
+RTDECL(int) RTTimerStart(PRTTIMER pTimer, uint64_t u64First)
+{
+    /*
+     * Validate.
+     */
+    AssertPtrReturn(pTimer, VERR_INVALID_HANDLE);
+    AssertReturn(pTimer->u32Magic == RTTIMER_MAGIC, VERR_INVALID_HANDLE);
+
+    if (!ASMAtomicUoReadBool(&pTimer->fSuspended))
+        return VERR_TIMER_ACTIVE;
+    if (   pTimer->fSpecificCpu
+        && !RTMpIsCpuOnline(pTimer->idCpu))
+        return VERR_CPU_OFFLINE;
+
+    /*
+     * Start the timer.
+     */
+    PKDPC pMasterDpc = pTimer->fOmniTimer
+                     ? &pTimer->aSubTimers[RTMpCpuIdToSetIndex(pTimer->idCpu)].NtDpc
+                     : &pTimer->aSubTimers[0].NtDpc;
+
+#ifndef RTR0TIMER_NT_MANUAL_RE_ARM
+    uint64_t u64Interval = pTimer->u64NanoInterval / 1000000; /* This is ms, believe it or not. */
+    ULONG ulInterval = (ULONG)u64Interval;
+    if (ulInterval != u64Interval)
+        ulInterval = MAXLONG;
+    else if (!ulInterval && pTimer->u64NanoInterval)
+        ulInterval = 1;
+#endif
+
+    LARGE_INTEGER DueTime;
+    DueTime.QuadPart = -(int64_t)(u64First / 100); /* Relative, NT time. */
+    if (!DueTime.QuadPart)
+        DueTime.QuadPart = -1;
+
+    unsigned cSubTimers = pTimer->fOmniTimer ? pTimer->cSubTimers : 1;
+    for (unsigned iCpu = 0; iCpu < cSubTimers; iCpu++)
+        pTimer->aSubTimers[iCpu].iTick = 0;
+    ASMAtomicWriteS32(&pTimer->cOmniSuspendCountDown, 0);
+    ASMAtomicWriteBool(&pTimer->fSuspended, false);
+#ifdef RTR0TIMER_NT_MANUAL_RE_ARM
+    pTimer->uNtStartTime = rtTimerNtQueryInterruptTime() + u64First / 100;
+    KeSetTimerEx(&pTimer->NtTimer, DueTime, 0, pMasterDpc);
+#else
+    KeSetTimerEx(&pTimer->NtTimer, DueTime, ulInterval, pMasterDpc);
+#endif
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Worker function that stops an active timer.
+ *
+ * Shared by RTTimerStop and RTTimerDestroy.
+ *
+ * @param   pTimer      The active timer.
+ */
+static void rtTimerNtStopWorker(PRTTIMER pTimer)
+{
+    /*
+     * Just cancel the timer, dequeue the DPCs and flush them (if this is supported).
+     */
+    ASMAtomicWriteBool(&pTimer->fSuspended, true);
+
+    KeCancelTimer(&pTimer->NtTimer);
+
+    for (RTCPUID iCpu = 0; iCpu < pTimer->cSubTimers; iCpu++)
+        KeRemoveQueueDpc(&pTimer->aSubTimers[iCpu].NtDpc);
+}
+
+
+RTDECL(int) RTTimerStop(PRTTIMER pTimer)
+{
+    /*
+     * Validate.
+     */
+    AssertPtrReturn(pTimer, VERR_INVALID_HANDLE);
+    AssertReturn(pTimer->u32Magic == RTTIMER_MAGIC, VERR_INVALID_HANDLE);
+
+    if (ASMAtomicUoReadBool(&pTimer->fSuspended))
+        return VERR_TIMER_SUSPENDED;
+
+    /*
+     * Call the worker we share with RTTimerDestroy.
+     */
+    rtTimerNtStopWorker(pTimer);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTTimerChangeInterval(PRTTIMER pTimer, uint64_t u64NanoInterval)
+{
+    AssertPtrReturn(pTimer, VERR_INVALID_HANDLE);
+    AssertReturn(pTimer->u32Magic == RTTIMER_MAGIC, VERR_INVALID_HANDLE);
+    RT_NOREF1(u64NanoInterval);
+
+    return VERR_NOT_SUPPORTED;
+}
+
+
+RTDECL(int) RTTimerDestroy(PRTTIMER pTimer)
+{
+    /* It's ok to pass NULL pointer. */
+    if (pTimer == /*NIL_RTTIMER*/ NULL)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pTimer, VERR_INVALID_HANDLE);
+    AssertReturn(pTimer->u32Magic == RTTIMER_MAGIC, VERR_INVALID_HANDLE);
+
+    /*
+     * We do not support destroying a timer from the callback because it is
+     * not 101% safe since we cannot flush DPCs.  Solaris has the same restriction.
+     */
+    AssertReturn(KeGetCurrentIrql() == PASSIVE_LEVEL, VERR_INVALID_CONTEXT);
+
+    /*
+     * Invalidate the timer, stop it if it's running and finally
+     * free up the memory.
+     */
+    ASMAtomicWriteU32(&pTimer->u32Magic, ~RTTIMER_MAGIC);
+    if (!ASMAtomicUoReadBool(&pTimer->fSuspended))
+        rtTimerNtStopWorker(pTimer);
+
+    /*
+     * Flush DPCs to be on the safe side.
+     */
+    if (g_pfnrtNtKeFlushQueuedDpcs)
+        g_pfnrtNtKeFlushQueuedDpcs();
+
+    RTMemFree(pTimer);
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTTimerCreateEx(PRTTIMER *ppTimer, uint64_t u64NanoInterval, uint32_t fFlags, PFNRTTIMER pfnTimer, void *pvUser)
+{
+    *ppTimer = NULL;
+
+    /*
+     * Validate flags.
+     */
+    if (!RTTIMER_FLAGS_ARE_VALID(fFlags))
+        return VERR_INVALID_PARAMETER;
+    if (    (fFlags & RTTIMER_FLAGS_CPU_SPECIFIC)
+        &&  (fFlags & RTTIMER_FLAGS_CPU_ALL) != RTTIMER_FLAGS_CPU_ALL
+        &&  !RTMpIsCpuPossible(RTMpCpuIdFromSetIndex(fFlags & RTTIMER_FLAGS_CPU_MASK)))
+        return VERR_CPU_NOT_FOUND;
+
+    /*
+     * Allocate the timer handler.
+     */
+    RTCPUID cSubTimers = 1;
+    if ((fFlags & RTTIMER_FLAGS_CPU_ALL) == RTTIMER_FLAGS_CPU_ALL)
+    {
+        cSubTimers = RTMpGetMaxCpuId() + 1;
+        Assert(cSubTimers <= RTCPUSET_MAX_CPUS); /* On Windows we have a 1:1 relationship between cpuid and set index. */
+    }
+
+    PRTTIMER pTimer = (PRTTIMER)RTMemAllocZ(RT_UOFFSETOF_DYN(RTTIMER, aSubTimers[cSubTimers]));
+    if (!pTimer)
+        return VERR_NO_MEMORY;
+
+    /*
+     * Initialize it.
+     */
+    pTimer->u32Magic = RTTIMER_MAGIC;
+    pTimer->cOmniSuspendCountDown = 0;
+    pTimer->fSuspended = true;
+    pTimer->fSpecificCpu = (fFlags & RTTIMER_FLAGS_CPU_SPECIFIC) && (fFlags & RTTIMER_FLAGS_CPU_ALL) != RTTIMER_FLAGS_CPU_ALL;
+    pTimer->fOmniTimer = (fFlags & RTTIMER_FLAGS_CPU_ALL) == RTTIMER_FLAGS_CPU_ALL;
+    pTimer->idCpu = pTimer->fSpecificCpu ? RTMpCpuIdFromSetIndex(fFlags & RTTIMER_FLAGS_CPU_MASK) : NIL_RTCPUID;
+    pTimer->cSubTimers = cSubTimers;
+    pTimer->pfnTimer = pfnTimer;
+    pTimer->pvUser = pvUser;
+    pTimer->u64NanoInterval = u64NanoInterval;
+    if (g_pfnrtKeInitializeTimerEx)
+        g_pfnrtKeInitializeTimerEx(&pTimer->NtTimer, SynchronizationTimer);
+    else
+        KeInitializeTimer(&pTimer->NtTimer);
+    int rc = VINF_SUCCESS;
+    if (pTimer->fOmniTimer)
+    {
+        /*
+         * Initialize the per-cpu "sub-timers", select the first online cpu
+         * to be the master.
+         * ASSUMES that no cpus will ever go offline.
+         */
+        pTimer->idCpu = NIL_RTCPUID;
+        for (unsigned iCpu = 0; iCpu < cSubTimers && RT_SUCCESS(rc); iCpu++)
+        {
+            pTimer->aSubTimers[iCpu].iTick = 0;
+            pTimer->aSubTimers[iCpu].pParent = pTimer;
+
+            if (    pTimer->idCpu == NIL_RTCPUID
+                &&  RTMpIsCpuOnline(RTMpCpuIdFromSetIndex(iCpu)))
+            {
+                pTimer->idCpu = RTMpCpuIdFromSetIndex(iCpu);
+                KeInitializeDpc(&pTimer->aSubTimers[iCpu].NtDpc, rtTimerNtOmniMasterCallback, &pTimer->aSubTimers[iCpu]);
+            }
+            else
+                KeInitializeDpc(&pTimer->aSubTimers[iCpu].NtDpc, rtTimerNtOmniSlaveCallback, &pTimer->aSubTimers[iCpu]);
+            if (g_pfnrtKeSetImportanceDpc)
+                g_pfnrtKeSetImportanceDpc(&pTimer->aSubTimers[iCpu].NtDpc, HighImportance);
+            rc = rtMpNtSetTargetProcessorDpc(&pTimer->aSubTimers[iCpu].NtDpc, iCpu);
+        }
+        Assert(pTimer->idCpu != NIL_RTCPUID);
+    }
+    else
+    {
+        /*
+         * Initialize the first "sub-timer", target the DPC on a specific processor
+         * if requested to do so.
+         */
+        pTimer->aSubTimers[0].iTick = 0;
+        pTimer->aSubTimers[0].pParent = pTimer;
+
+        KeInitializeDpc(&pTimer->aSubTimers[0].NtDpc, rtTimerNtSimpleCallback, pTimer);
+        if (g_pfnrtKeSetImportanceDpc)
+            g_pfnrtKeSetImportanceDpc(&pTimer->aSubTimers[0].NtDpc, HighImportance);
+        if (pTimer->fSpecificCpu)
+            rc = rtMpNtSetTargetProcessorDpc(&pTimer->aSubTimers[0].NtDpc, (int)pTimer->idCpu);
+    }
+    if (RT_SUCCESS(rc))
+    {
+        *ppTimer = pTimer;
+        return VINF_SUCCESS;
+    }
+
+    RTMemFree(pTimer);
+    return rc;
+}
+
+
+RTDECL(int) RTTimerRequestSystemGranularity(uint32_t u32Request, uint32_t *pu32Granted)
+{
+    if (!g_pfnrtNtExSetTimerResolution)
+        return VERR_NOT_SUPPORTED;
+
+    ULONG ulGranted = g_pfnrtNtExSetTimerResolution(u32Request / 100, TRUE);
+    if (pu32Granted)
+        *pu32Granted = ulGranted * 100; /* NT -> ns */
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTTimerReleaseSystemGranularity(uint32_t u32Granted)
+{
+    if (!g_pfnrtNtExSetTimerResolution)
+        return VERR_NOT_SUPPORTED;
+
+    g_pfnrtNtExSetTimerResolution(0 /* ignored */, FALSE);
+    NOREF(u32Granted);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(bool) RTTimerCanDoHighResolution(void)
+{
+    return false;
+}
+
diff --git a/src/VBox/Runtime/r0drv/nt/toxic-chkstk-r0drv-nt.asm b/src/VBox/Runtime/r0drv/nt/toxic-chkstk-r0drv-nt.asm
new file mode 100644
index 00000000..d5bb6570
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/nt/toxic-chkstk-r0drv-nt.asm
@@ -0,0 +1,42 @@
+; $Id: toxic-chkstk-r0drv-nt.asm $
+;; @file
+; IPRT - Toxic _chkstk symbol.
+;
+
+;
+; Copyright (C) 2006-2020 Oracle Corporation
+;
+; This file is part of VirtualBox Open Source Edition (OSE), as
+; available from http://www.virtualbox.org. This file is free software;
+; you can redistribute it and/or modify it under the terms of the GNU
+; General Public License (GPL) as published by the Free Software
+; Foundation, in version 2 as it comes in the "COPYING" file of the
+; VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+; hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+;
+; The contents of this file may alternatively be used under the terms
+; of the Common Development and Distribution License Version 1.0
+; (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+; VirtualBox OSE distribution, in which case the provisions of the
+; CDDL are applicable instead of those of the GPL.
+;
+; You may elect to license modified versions of this file under the
+; terms and conditions of either the GPL or the CDDL or both.
+;
+
+;*******************************************************************************
+;* Header Files                                                                *
+;*******************************************************************************
+%include "iprt/asmdefs.mac"
+
+BEGINCODE
+
+;;
+; Bad function to drag into kernel code as you're eating up too much stack.
+;
+BEGINPROC _chkstk
+%define MY_SYM _chkstk_is_considered_toxic_in_kernel_code__you_should_locate_code_using_too_much_stack_and_change_it_to_use_heap
+    extern  MY_SYM
+    jmp     MY_SYM
+ENDPROC _chkstk
+
diff --git a/src/VBox/Runtime/r0drv/os2/Makefile.kup b/src/VBox/Runtime/r0drv/os2/Makefile.kup
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/os2/Makefile.kup
diff --git a/src/VBox/Runtime/r0drv/os2/RTR0AssertPanicSystem-r0drv-os2.asm b/src/VBox/Runtime/r0drv/os2/RTR0AssertPanicSystem-r0drv-os2.asm
new file mode 100644
index 00000000..f499766e
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/os2/RTR0AssertPanicSystem-r0drv-os2.asm
@@ -0,0 +1,128 @@
+; $Id: RTR0AssertPanicSystem-r0drv-os2.asm $
+;; @file
+; IPRT - RTR0AssertPanicSystem, Ring-0 Driver, OS/2.
+;
+
+;
+; Contributed by knut st. osmundsen.
+;
+; Copyright (C) 2007-2020 Oracle Corporation
+;
+; This file is part of VirtualBox Open Source Edition (OSE), as
+; available from http://www.virtualbox.org. This file is free software;
+; you can redistribute it and/or modify it under the terms of the GNU
+; General Public License (GPL) as published by the Free Software
+; Foundation, in version 2 as it comes in the "COPYING" file of the
+; VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+; hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+;
+; The contents of this file may alternatively be used under the terms
+; of the Common Development and Distribution License Version 1.0
+; (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+; VirtualBox OSE distribution, in which case the provisions of the
+; CDDL are applicable instead of those of the GPL.
+;
+; You may elect to license modified versions of this file under the
+; terms and conditions of either the GPL or the CDDL or both.
+; --------------------------------------------------------------------
+;
+; This code is based on:
+;
+; Copyright (c) 1999-2007 knut st. osmundsen <bird-src-spam@anduin.net>
+;
+; Permission is hereby granted, free of charge, to any person
+; obtaining a copy of this software and associated documentation
+; files (the "Software"), to deal in the Software without
+; restriction, including without limitation the rights to use,
+; copy, modify, merge, publish, distribute, sublicense, and/or sell
+; copies of the Software, and to permit persons to whom the
+; Software is furnished to do so, subject to the following
+; conditions:
+;
+; The above copyright notice and this permission notice shall be
+; included in all copies or substantial portions of the Software.
+;
+; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+; EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+; OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+; NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+; HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+; WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+; FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+; OTHER DEALINGS IN THE SOFTWARE.
+;
+
+
+;*******************************************************************************
+;* Header Files                                                                *
+;*******************************************************************************
+%define RT_INCL_16BIT_SEGMENTS
+%include "iprt/asmdefs.mac"
+
+
+;*******************************************************************************
+;* Defined Constants And Macros                                                *
+;*******************************************************************************
+%define DevHlp_InternalError 02bh
+
+
+;*******************************************************************************
+;* External Symbols                                                            *
+;*******************************************************************************
+extern KernThunkStackTo16
+extern KernThunkStackTo32
+extern NAME(g_szRTAssertMsg)
+extern NAME(g_cchRTAssertMsg)
+extern NAME(g_fpfnDevHlp)
+
+
+BEGINCODE
+
+BEGINPROC_EXPORTED RTR0AssertPanicSystem
+    push    ebp
+    mov     ebp, esp
+    push    esi
+    push    edi
+    push    ds
+
+    ;
+    ; Try detect debug kernel... later one day.
+    ;
+
+
+    ;
+    ; Raise an IPE.
+    ;
+    call    KernThunkStackTo16
+    ;jmp far dword NAME(RTR0AssertPanicSystem_16) wrt CODE16
+    db      066h
+    db      0eah
+    dw      NAME(RTR0AssertPanicSystem_16) wrt CODE16
+    dw      CODE16
+BEGINCODE16
+GLOBALNAME RTR0AssertPanicSystem_16
+    ; mov     ax, seg NAME(g_szRTAssertMsg) - makes wlink crash.
+    mov     ax, DATA16
+    mov     ds, ax
+    mov     si, NAME(g_szRTAssertMsg)
+    mov     di, [NAME(g_cchRTAssertMsg)]
+    mov     dl, DevHlp_InternalError
+    call far [NAME(g_fpfnDevHlp)]
+
+    ; Doesn't normally return, but in case it does...
+    ;jmp far dword NAME(RTR0AssertPanicSystem_32)
+    db      066h
+    db      0eah
+    dd      NAME(RTR0AssertPanicSystem_32)
+    dw      TEXT32 wrt FLAT
+BEGINCODE32:
+GLOBALNAME RTR0AssertPanicSystem_32
+    call KernThunkStackTo32
+    mov     eax, 1
+    pop     ds
+    pop     edi
+    pop     esi
+    leave
+    ret
+ENDPROC RTR0AssertPanicSystem
+
diff --git a/src/VBox/Runtime/r0drv/os2/RTR0Os2DHQueryDOSVar.asm b/src/VBox/Runtime/r0drv/os2/RTR0Os2DHQueryDOSVar.asm
new file mode 100644
index 00000000..d1743d14
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/os2/RTR0Os2DHQueryDOSVar.asm
@@ -0,0 +1,207 @@
+; $Id: RTR0Os2DHQueryDOSVar.asm $
+;; @file
+; IPRT - DevHelp_GetDOSVar, Ring-0 Driver, OS/2.
+;
+
+;
+; Contributed by knut st. osmundsen.
+;
+; Copyright (C) 2007-2020 Oracle Corporation
+;
+; This file is part of VirtualBox Open Source Edition (OSE), as
+; available from http://www.virtualbox.org. This file is free software;
+; you can redistribute it and/or modify it under the terms of the GNU
+; General Public License (GPL) as published by the Free Software
+; Foundation, in version 2 as it comes in the "COPYING" file of the
+; VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+; hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+;
+; The contents of this file may alternatively be used under the terms
+; of the Common Development and Distribution License Version 1.0
+; (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+; VirtualBox OSE distribution, in which case the provisions of the
+; CDDL are applicable instead of those of the GPL.
+;
+; You may elect to license modified versions of this file under the
+; terms and conditions of either the GPL or the CDDL or both.
+; --------------------------------------------------------------------
+;
+; This code is based on:
+;
+; Copyright (c) 1999-2007 knut st. osmundsen <bird-src-spam@anduin.net>
+;
+; Permission is hereby granted, free of charge, to any person
+; obtaining a copy of this software and associated documentation
+; files (the "Software"), to deal in the Software without
+; restriction, including without limitation the rights to use,
+; copy, modify, merge, publish, distribute, sublicense, and/or sell
+; copies of the Software, and to permit persons to whom the
+; Software is furnished to do so, subject to the following
+; conditions:
+;
+; The above copyright notice and this permission notice shall be
+; included in all copies or substantial portions of the Software.
+;
+; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+; EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+; OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+; NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+; HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+; WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+; FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+; OTHER DEALINGS IN THE SOFTWARE.
+;
+
+
+;*******************************************************************************
+;* Header Files                                                                *
+;*******************************************************************************
+%define RT_INCL_16BIT_SEGMENTS
+%include "iprt/asmdefs.mac"
+%include "iprt/err.mac"
+
+
+;*******************************************************************************
+;* External Symbols                                                            *
+;*******************************************************************************
+extern KernThunkStackTo32
+extern KernThunkStackTo16
+extern NAME(g_fpfnDevHlp)
+
+
+;*******************************************************************************
+;* Defined Constants And Macros                                                *
+;*******************************************************************************
+%define DevHlp_GetDOSVar    24h
+
+
+BEGINCODE
+
+;
+; Jump table used by RTR0Os2DHQueryDOSVar
+;
+DosVarJumpTab:
+    dd  0                           ; 0 - Reserved
+    dd  Load1600                    ; 1 - GIS
+    dd  Load1616                    ; 2 - LIS
+    dd  0                           ; 3 - Reserved
+    dd  Load1616                    ; 4 - VectorSDF
+    dd  Load1616                    ; 5 - VectorReboot
+    dd  Load1616                    ; 6 - VectorMSATS
+    dd  AsIs                        ; 7 - YieldFlag (Resched)
+    dd  AsIs                        ; 8 - TCYieldFlag (TCResched)
+    dd  AsIs                        ; 9 - DOSTable
+    dd  Load1616                    ; a - VectorDEKKO
+    dd  AsIs                        ; b - CodePgBuff
+    dd  Load1616                    ; c - VectorRIPL
+    dd  AsIs                        ; d - InterruptLevel
+    dd  AsIs                        ; e - DevClassTables
+    dd  AsIs                        ; f - DMQS_Sel
+    dd  AsIs                        ;10 - APMInfo
+    dd  LoadWord                    ;11 - APM_Length (length of above structure)
+DosVarJumpTabEnd:
+%define DosVarJumpTabSize (DosVarJumpTabEnd - DosVarJumpTab) / 4
+
+;;
+; Unified DevHelp_GetDOSVar -> Far 16:16 pointer wrapper.
+;
+; @param    iVar    [ebp + 08h]     Variable.
+; @param    iMember [ebp + 0ch]     Member.
+; @param    pfp     [ebp + 10h]     Where to store the variable address (pointer to 16:16).
+;
+BEGINPROC_EXPORTED RTR0Os2DHQueryDOSVar
+    ; switch stack first.
+    call    KernThunkStackTo16
+
+    ; normal prolog.
+    push    ebp
+    mov     ebp, esp
+    push    dword [NAME(g_fpfnDevHlp)]  ; ebp - 4
+    push    ebx                         ; save ebx
+    push    es                          ; save es
+
+    ; setup the devhelp call and switch to
+    mov     eax, [ebp + 08h]            ; iVar (8-bit)
+    mov     ecx, [ebp + 0ch]            ; iMember (16-bit)
+    mov     dl, DevHlp_GetDOSVar
+
+    ; jump to the 16-bit code.
+    ;jmp far dword NAME(RTR0Os2DHQueryDOSVar_16) wrt CODE16
+    db      066h
+    db      0eah
+    dw      NAME(RTR0Os2DHQueryDOSVar_16) wrt CODE16
+    dw      CODE16
+BEGINCODE16
+GLOBALNAME RTR0Os2DHQueryDOSVar_16
+    call far [ss:ebp - 4]
+
+    ;jmp far dword NAME(RTR0Os2DHQueryDOSVar) wrt FLAT
+    db      066h
+    db      0eah
+    dd      NAME(RTR0Os2DHQueryDOSVar_32) ;wrt FLAT
+    dw      TEXT32 wrt FLAT
+BEGINCODE
+GLOBALNAME RTR0Os2DHQueryDOSVar_32
+    jc  Error1
+
+    ;
+    ; Make ax:ebx contain the pointer and take action according
+    ; to the variable jump table.
+    ;
+    and     ebx, 0000ffffh              ; clean high part of ebx
+    movzx   ecx, byte [ebp + 08]        ; iVar
+    cmp     ecx, DosVarJumpTabSize
+    jg      Error2
+    jmp     [DosVarJumpTab + ecx * 4]
+
+    ; Load Word at ax:ebx.
+LoadWord:
+    mov     es, ax
+    movzx   edx, word [es:ebx]
+    jmp StoreIt
+
+    ; Load selector at ax:ebx.
+Load1600:
+    mov     es, ax
+    movzx   edx, word [es:ebx]
+    shl     edx, 16
+    jmp StoreIt
+
+    ; Load 16:16 ptr at ax:ebx.
+Load1616:
+    mov     es, ax
+    mov     edx, dword [es:ebx]
+    jmp StoreIt
+
+    ; Move ax:bx into edx.
+AsIs:
+    mov     dx, ax
+    shl     edx, 16
+    mov     dx, bx
+    jmp StoreIt
+
+Error2:
+    mov     eax, VERR_INVALID_PARAMETER
+    jmp     Done
+
+Error1:
+    mov     eax, VERR_GENERAL_FAILURE
+    jmp     Done
+
+StoreIt:
+    mov     ecx, [ebp + 10h]
+    mov     [ecx], edx
+    xor     eax, eax                    ; return success (VINF_SUCCESS == 0)
+
+Done:
+    pop     es
+    pop     ebx
+    leave
+
+    ; switch stack back and return.
+    push    eax
+    call    KernThunkStackTo32
+    pop     eax
+    ret
+ENDPROC RTR0Os2DHQueryDOSVar
+
diff --git a/src/VBox/Runtime/r0drv/os2/RTR0Os2DHVMGlobalToProcess.asm b/src/VBox/Runtime/r0drv/os2/RTR0Os2DHVMGlobalToProcess.asm
new file mode 100644
index 00000000..8c2b1087
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/os2/RTR0Os2DHVMGlobalToProcess.asm
@@ -0,0 +1,138 @@
+; $Id: RTR0Os2DHVMGlobalToProcess.asm $
+;; @file
+; IPRT - DevHelp_VMGlobalToProcess, Ring-0 Driver, OS/2.
+;
+
+;
+; Contributed by knut st. osmundsen.
+;
+; Copyright (C) 2007-2020 Oracle Corporation
+;
+; This file is part of VirtualBox Open Source Edition (OSE), as
+; available from http://www.virtualbox.org. This file is free software;
+; you can redistribute it and/or modify it under the terms of the GNU
+; General Public License (GPL) as published by the Free Software
+; Foundation, in version 2 as it comes in the "COPYING" file of the
+; VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+; hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+;
+; The contents of this file may alternatively be used under the terms
+; of the Common Development and Distribution License Version 1.0
+; (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+; VirtualBox OSE distribution, in which case the provisions of the
+; CDDL are applicable instead of those of the GPL.
+;
+; You may elect to license modified versions of this file under the
+; terms and conditions of either the GPL or the CDDL or both.
+; --------------------------------------------------------------------
+;
+; This code is based on:
+;
+; Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+;
+; Permission is hereby granted, free of charge, to any person
+; obtaining a copy of this software and associated documentation
+; files (the "Software"), to deal in the Software without
+; restriction, including without limitation the rights to use,
+; copy, modify, merge, publish, distribute, sublicense, and/or sell
+; copies of the Software, and to permit persons to whom the
+; Software is furnished to do so, subject to the following
+; conditions:
+;
+; The above copyright notice and this permission notice shall be
+; included in all copies or substantial portions of the Software.
+;
+; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+; EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+; OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+; NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+; HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+; WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+; FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+; OTHER DEALINGS IN THE SOFTWARE.
+;
+
+
+;*******************************************************************************
+;* Header Files                                                                *
+;*******************************************************************************
+%define RT_INCL_16BIT_SEGMENTS
+%include "iprt/asmdefs.mac"
+%include "iprt/err.mac"
+
+
+;*******************************************************************************
+;* External Symbols                                                            *
+;*******************************************************************************
+extern KernThunkStackTo32
+extern KernThunkStackTo16
+extern NAME(g_fpfnDevHlp)
+
+
+;*******************************************************************************
+;* Defined Constants And Macros                                                *
+;*******************************************************************************
+%define DevHlp_VMGlobalToProcess  05ah
+
+
+BEGINCODE
+
+;;
+; VMGlobalToProcess wrapper.
+;
+; @param    fFlags  [ebp + 08h]     Flags
+; @param    pvR0    [ebp + 0ch]     Ring-0 memory.
+; @param    cb      [ebp + 10h]     Size of memory object to map.
+; @param    ppR3    [ebp + 14h]     Where to store the address of the ring-3 mapping.
+;
+BEGINPROC_EXPORTED RTR0Os2DHVMGlobalToProcess
+    ; switch stack first.
+    call    KernThunkStackTo16
+
+    ; normal prolog.
+    push    ebp
+    mov     ebp, esp
+    push    dword [NAME(g_fpfnDevHlp)]  ; ebp - 4
+    push    ebx                         ; save ebx
+
+    ; setup the devhelp call
+    mov     eax, [ebp + 08h]            ; fFlags
+    mov     ebx, [ebp + 0ch]            ; pvR0
+    mov     ecx, [ebp + 10h]            ; cb
+    mov     dl, DevHlp_VMGlobalToProcess
+
+    ; jump to the 16-bit code.
+    ;jmp far dword NAME(RTR0Os2DHQueryDOSVar_16) wrt CODE16
+    db      066h
+    db      0eah
+    dw      NAME(RTR0Os2DHVMGlobalToProcess_16) wrt CODE16
+    dw      CODE16
+BEGINCODE16
+GLOBALNAME RTR0Os2DHVMGlobalToProcess_16
+    call far [ss:ebp - 4]
+
+    ;jmp far dword NAME(RTR0Os2DHVMGlobalToProcess_32) wrt FLAT
+    db      066h
+    db      0eah
+    dd      NAME(RTR0Os2DHVMGlobalToProcess_32) ;wrt FLAT
+    dw      TEXT32 wrt FLAT
+BEGINCODE
+GLOBALNAME RTR0Os2DHVMGlobalToProcess_32
+    jc      .done
+
+    ; save the result.
+    mov     edx, [ebp + 14h]            ; ppvR3
+    mov     [edx], eax
+    xor     eax, eax
+
+.done:
+    pop     ebx
+    leave
+
+    ; switch stack back and return.
+    push    eax
+    call    KernThunkStackTo32
+    pop     eax
+    ret
+ENDPROC RTR0Os2DHVMGlobalToProcess
+
diff --git a/src/VBox/Runtime/r0drv/os2/alloc-r0drv-os2.cpp b/src/VBox/Runtime/r0drv/os2/alloc-r0drv-os2.cpp
new file mode 100644
index 00000000..91bbe5d0
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/os2/alloc-r0drv-os2.cpp
@@ -0,0 +1,131 @@
+/* $Id: alloc-r0drv-os2.cpp $ */
+/** @file
+ * IPRT - Memory Allocation, Ring-0 Driver, OS/2.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-os2-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/mem.h>
+
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+#include <iprt/param.h>
+#include "r0drv/alloc-r0drv.h" /** @todo drop the r0drv/alloc-r0drv.cpp stuff on OS/2? */
+
+
+DECLHIDDEN(int) rtR0MemAllocEx(size_t cb, uint32_t fFlags, PRTMEMHDR *ppHdr)
+{
+    if (fFlags & RTMEMHDR_FLAG_ANY_CTX)
+        return VERR_NOT_SUPPORTED;
+
+    void *pv = NULL;
+    APIRET rc = KernVMAlloc(cb + sizeof(RTMEMHDR), VMDHA_FIXED, &pv, (void **)-1, NULL);
+    if (RT_UNLIKELY(rc != NO_ERROR))
+        return RTErrConvertFromOS2(rc);
+
+    PRTMEMHDR   pHdr = (PRTMEMHDR)pv;
+    pHdr->u32Magic   = RTMEMHDR_MAGIC;
+    pHdr->fFlags     = fFlags;
+    pHdr->cb         = cb;
+    pHdr->cbReq      = cb;
+    *ppHdr = pHdr;
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(void) rtR0MemFree(PRTMEMHDR pHdr)
+{
+    pHdr->u32Magic += 1;
+    APIRET rc = KernVMFree(pHdr);
+    Assert(!rc); NOREF(rc);
+}
+
+
+RTR0DECL(void *) RTMemContAlloc(PRTCCPHYS pPhys, size_t cb)
+{
+    /*
+     * Validate input.
+     */
+    AssertPtr(pPhys);
+    Assert(cb > 0);
+
+    /*
+     * All physical memory in OS/2 is below 4GB, so this should be kind of easy.
+     */
+    cb = RT_ALIGN_Z(cb, PAGE_SIZE); /* -> page aligned result. */
+    PVOID pv = NULL;
+    PVOID PhysAddr = (PVOID)~0UL;
+    APIRET rc = KernVMAlloc(cb, VMDHA_FIXED | VMDHA_CONTIG, &pv, &PhysAddr, NULL);
+    if (!rc)
+    {
+        Assert(PhysAddr != (PVOID)~0UL);
+        Assert(!((uintptr_t)pv & PAGE_OFFSET_MASK));
+        *pPhys = (uintptr_t)PhysAddr;
+        return pv;
+    }
+    return NULL;
+}
+
+
+RTR0DECL(void) RTMemContFree(void *pv, size_t cb)
+{
+    if (pv)
+    {
+        AssertMsg(!((uintptr_t)pv & PAGE_OFFSET_MASK), ("pv=%p\n", pv));
+        KernVMFree(pv);
+    }
+}
+
diff --git a/src/VBox/Runtime/r0drv/os2/assert-r0drv-os2.cpp b/src/VBox/Runtime/r0drv/os2/assert-r0drv-os2.cpp
new file mode 100644
index 00000000..8e18e300
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/os2/assert-r0drv-os2.cpp
@@ -0,0 +1,158 @@
+/* $Id: assert-r0drv-os2.cpp $ */
+/** @file
+ * IPRT - Assertion Workers, Ring-0 Drivers, OS/2.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/assert.h>
+#include <iprt/log.h>
+#include <iprt/string.h>
+#include <iprt/stdarg.h>
+
+#include <VBox/log.h>
+
+#include "internal/assert.h"
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+RT_C_DECLS_BEGIN /* for watcom */
+/** The last assert message. (in DATA16) */
+extern char g_szRTAssertMsg[2048];
+/** The length of the last assert message. (in DATA16) */
+extern size_t g_cchRTAssertMsg;
+RT_C_DECLS_END
+
+
+/*********************************************************************************************************************************
+*   Internal Functions                                                                                                           *
+*********************************************************************************************************************************/
+static DECLCALLBACK(size_t) rtR0Os2AssertOutputCB(void *pvArg, const char *pachChars, size_t cbChars);
+
+
+DECLHIDDEN(void) rtR0AssertNativeMsg1(const char *pszExpr, unsigned uLine, const char *pszFile, const char *pszFunction)
+{
+#if defined(DEBUG_bird)
+    RTLogComPrintf("\n!!Assertion Failed!!\n"
+                   "Expression: %s\n"
+                   "Location  : %s(%d) %s\n",
+                   pszExpr, pszFile, uLine, pszFunction);
+#endif
+
+    g_cchRTAssertMsg = RTStrPrintf(g_szRTAssertMsg, sizeof(g_szRTAssertMsg),
+                                   "\r\n!!Assertion Failed!!\r\n"
+                                   "Expression: %s\r\n"
+                                   "Location  : %s(%d) %s\r\n",
+                                   pszExpr, pszFile, uLine, pszFunction);
+}
+
+
+DECLHIDDEN(void) rtR0AssertNativeMsg2V(bool fInitial, const char *pszFormat, va_list va)
+{
+#if defined(DEBUG_bird)
+    va_list vaCopy;
+    va_copy(vaCopy, va);
+    RTLogComPrintfV(pszFormat, vaCopy);
+    va_end(vaCopy);
+#endif
+
+    size_t cch = g_cchRTAssertMsg;
+    char *pch = &g_szRTAssertMsg[cch];
+    cch += RTStrFormatV(rtR0Os2AssertOutputCB, &pch, NULL, NULL, pszFormat, va);
+    g_cchRTAssertMsg = cch;
+
+    NOREF(fInitial);
+}
+
+
+/**
+ * Output callback.
+ *
+ * @returns number of bytes written.
+ * @param   pvArg       Pointer to a char pointer with the current output position.
+ * @param   pachChars   Pointer to an array of utf-8 characters.
+ * @param   cbChars     Number of bytes in the character array pointed to by pachChars.
+ */
+static DECLCALLBACK(size_t) rtR0Os2AssertOutputCB(void *pvArg, const char *pachChars, size_t cbChars)
+{
+    char **ppch = (char **)pvArg;
+    char *pch = *ppch;
+
+    while (cbChars-- > 0)
+    {
+        const char ch = *pachChars++;
+        if (ch == '\r')
+            continue;
+        if (ch == '\n')
+        {
+            if (pch + 1 >= &g_szRTAssertMsg[sizeof(g_szRTAssertMsg)])
+                break;
+            *pch++ = '\r';
+        }
+        if (pch + 1 >= &g_szRTAssertMsg[sizeof(g_szRTAssertMsg)])
+            break;
+        *pch++ = ch;
+    }
+    *pch = '\0';
+
+    size_t cbWritten = pch - *ppch;
+    *ppch = pch;
+    return cbWritten;
+}
+
+
+/* RTR0AssertPanicSystem is implemented in RTR0AssertPanicSystem-r0drv-os2.asm */
+
diff --git a/src/VBox/Runtime/r0drv/os2/assertA-r0drv-os2.asm b/src/VBox/Runtime/r0drv/os2/assertA-r0drv-os2.asm
new file mode 100644
index 00000000..92700b0b
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/os2/assertA-r0drv-os2.asm
@@ -0,0 +1,71 @@
+; $Id: assertA-r0drv-os2.asm $
+;; @file
+; IPRT - DevHelp_GetDOSVar, Ring-0 Driver, OS/2.
+;
+
+;
+; Contributed by knut st. osmundsen.
+;
+; Copyright (C) 2007-2020 Oracle Corporation
+;
+; This file is part of VirtualBox Open Source Edition (OSE), as
+; available from http://www.virtualbox.org. This file is free software;
+; you can redistribute it and/or modify it under the terms of the GNU
+; General Public License (GPL) as published by the Free Software
+; Foundation, in version 2 as it comes in the "COPYING" file of the
+; VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+; hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+;
+; The contents of this file may alternatively be used under the terms
+; of the Common Development and Distribution License Version 1.0
+; (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+; VirtualBox OSE distribution, in which case the provisions of the
+; CDDL are applicable instead of those of the GPL.
+;
+; You may elect to license modified versions of this file under the
+; terms and conditions of either the GPL or the CDDL or both.
+; --------------------------------------------------------------------
+;
+; This code is based on:
+;
+; Copyright (c) 1999-2007 knut st. osmundsen <bird-src-spam@anduin.net>
+;
+; Permission is hereby granted, free of charge, to any person
+; obtaining a copy of this software and associated documentation
+; files (the "Software"), to deal in the Software without
+; restriction, including without limitation the rights to use,
+; copy, modify, merge, publish, distribute, sublicense, and/or sell
+; copies of the Software, and to permit persons to whom the
+; Software is furnished to do so, subject to the following
+; conditions:
+;
+; The above copyright notice and this permission notice shall be
+; included in all copies or substantial portions of the Software.
+;
+; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+; EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+; OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+; NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+; HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+; WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+; FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+; OTHER DEALINGS IN THE SOFTWARE.
+;
+
+
+;*******************************************************************************
+;* Header Files                                                                *
+;*******************************************************************************
+%define RT_INCL_16BIT_SEGMENTS
+%include "iprt/asmdefs.mac"
+
+BEGINDATA16
+
+;; The last assert message. (see assert-r0drv-os2.cpp)
+EXPORTEDNAME g_szRTAssertMsg
+times 2048 db 0
+
+;; The length of the last assert message.
+EXPORTEDNAME g_cchRTAssertMsg
+    dd 0
+
diff --git a/src/VBox/Runtime/r0drv/os2/initterm-r0drv-os2.cpp b/src/VBox/Runtime/r0drv/os2/initterm-r0drv-os2.cpp
new file mode 100644
index 00000000..24d45498
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/os2/initterm-r0drv-os2.cpp
@@ -0,0 +1,122 @@
+/* $Id: initterm-r0drv-os2.cpp $ */
+/** @file
+ * IPRT - Initialization & Termination, Ring-0 Driver, OS/2.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-os2-kernel.h"
+
+#include "internal/initterm.h"
+#include <iprt/errcore.h>
+#include <iprt/assert.h>
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/** Pointer to the 1st DOS variable table. */
+PCDOSTABLE  g_pDosTable = NULL;
+/** Pointer to the 2nd DOS variable table. */
+PCDOSTABLE2 g_pDosTable2 = NULL;
+/** Pointer to the global info segment. */
+PGINFOSEG   g_pGIS = NULL;
+/** Far 16:16 pointer to the local info segment.
+ * IIRC this must be converted to a flat pointer when accessed to work correctly on SMP systems. */
+RTFAR16     g_fpLIS = {0, 0};
+
+
+DECLHIDDEN(int) rtR0InitNative(void)
+{
+    /*
+     * Get the DOS Tables.
+     */
+    RTFAR16 fp;
+    int rc = RTR0Os2DHQueryDOSVar(DHGETDOSV_DOSTABLES, 0, &fp);
+    AssertMsgReturn(!rc, ("rc=%d\n", rc), VERR_INTERNAL_ERROR);
+    g_pDosTable = (PCDOSTABLE)RTR0Os2Virt2Flat(fp);
+    AssertReturn(g_pDosTable, VERR_INTERNAL_ERROR);
+    g_pDosTable2 = (PCDOSTABLE2)((const uint8_t *)g_pDosTable + g_pDosTable->cul * sizeof(ULONG) + 1);
+
+    /*
+     * Get the addresses of the two info segments.
+     */
+    rc = RTR0Os2DHQueryDOSVar(DHGETDOSV_SYSINFOSEG, 0, &fp);
+    AssertMsgReturn(!rc, ("rc=%d\n", rc), VERR_INTERNAL_ERROR);
+    g_pGIS = (PGINFOSEG)RTR0Os2Virt2Flat(fp);
+    rc = RTR0Os2DHQueryDOSVar(DHGETDOSV_LOCINFOSEG, 0, &fp);
+    AssertMsgReturn(!rc, ("rc=%d\n", rc), VERR_INTERNAL_ERROR);
+    g_fpLIS = fp;
+
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(void) rtR0TermNative(void)
+{
+    /* nothing to do here yet. */
+}
+
+
+/**
+ * Converts a 16:16 pointer to a flat pointer.
+ *
+ * @returns Flat pointer (NULL if fp is NULL).
+ * @param   fp      Far pointer to convert.
+ */
+RTR0DECL(void *) RTR0Os2Virt2Flat(RTFAR16 fp)
+{
+    return (void *)KernSelToFlat(((uint32_t)fp.sel << 16) | fp.off);
+}
+
diff --git a/src/VBox/Runtime/r0drv/os2/memobj-r0drv-os2.cpp b/src/VBox/Runtime/r0drv/os2/memobj-r0drv-os2.cpp
new file mode 100644
index 00000000..dfbe1078
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/os2/memobj-r0drv-os2.cpp
@@ -0,0 +1,598 @@
+/* $Id: memobj-r0drv-os2.cpp $ */
+/** @file
+ * IPRT - Ring-0 Memory Objects, OS/2.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-os2-kernel.h"
+
+#include <iprt/memobj.h>
+#include <iprt/mem.h>
+#include <iprt/err.h>
+#include <iprt/assert.h>
+#include <iprt/log.h>
+#include <iprt/param.h>
+#include <iprt/process.h>
+#include "internal/memobj.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * The OS/2 version of the memory object structure.
+ */
+typedef struct RTR0MEMOBJDARWIN
+{
+    /** The core structure. */
+    RTR0MEMOBJINTERNAL  Core;
+    /** Lock for the ring-3 / ring-0 pinned objectes.
+     * This member might not be allocated for some object types. */
+    KernVMLock_t        Lock;
+    /** Array of physical pages.
+     * This array can be 0 in length for some object types. */
+    KernPageList_t      aPages[1];
+} RTR0MEMOBJOS2, *PRTR0MEMOBJOS2;
+
+
+/*********************************************************************************************************************************
+*   Internal Functions                                                                                                           *
+*********************************************************************************************************************************/
+static void rtR0MemObjFixPageList(KernPageList_t *paPages, ULONG cPages, ULONG cPagesRet);
+
+
+DECLHIDDEN(int) rtR0MemObjNativeFree(RTR0MEMOBJ pMem)
+{
+    PRTR0MEMOBJOS2 pMemOs2 = (PRTR0MEMOBJOS2)pMem;
+    int rc;
+
+    switch (pMemOs2->Core.enmType)
+    {
+        case RTR0MEMOBJTYPE_PHYS_NC:
+            AssertMsgFailed(("RTR0MEMOBJTYPE_PHYS_NC\n"));
+            return VERR_INTERNAL_ERROR;
+
+        case RTR0MEMOBJTYPE_PHYS:
+            if (!pMemOs2->Core.pv)
+                break;
+
+        case RTR0MEMOBJTYPE_MAPPING:
+            if (pMemOs2->Core.u.Mapping.R0Process == NIL_RTR0PROCESS)
+                break;
+
+            RT_FALL_THRU();
+        case RTR0MEMOBJTYPE_PAGE:
+        case RTR0MEMOBJTYPE_LOW:
+        case RTR0MEMOBJTYPE_CONT:
+            rc = KernVMFree(pMemOs2->Core.pv);
+            AssertMsg(!rc, ("rc=%d type=%d pv=%p cb=%#zx\n", rc, pMemOs2->Core.enmType, pMemOs2->Core.pv, pMemOs2->Core.cb));
+            break;
+
+        case RTR0MEMOBJTYPE_LOCK:
+            rc = KernVMUnlock(&pMemOs2->Lock);
+            AssertMsg(!rc, ("rc=%d\n", rc));
+            break;
+
+        case RTR0MEMOBJTYPE_RES_VIRT:
+        default:
+            AssertMsgFailed(("enmType=%d\n", pMemOs2->Core.enmType));
+            return VERR_INTERNAL_ERROR;
+    }
+
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocPage(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    NOREF(fExecutable);
+
+    /* create the object. */
+    const ULONG cPages = cb >> PAGE_SHIFT;
+    PRTR0MEMOBJOS2 pMemOs2 = (PRTR0MEMOBJOS2)rtR0MemObjNew(RT_UOFFSETOF_DYN(RTR0MEMOBJOS2, aPages[cPages]),
+                                                           RTR0MEMOBJTYPE_PAGE, NULL, cb);
+    if (!pMemOs2)
+        return VERR_NO_MEMORY;
+
+    /* do the allocation. */
+    int rc = KernVMAlloc(cb, VMDHA_FIXED, &pMemOs2->Core.pv, (PPVOID)-1, NULL);
+    if (!rc)
+    {
+        ULONG cPagesRet = cPages;
+        rc = KernLinToPageList(pMemOs2->Core.pv, cb, &pMemOs2->aPages[0], &cPagesRet);
+        if (!rc)
+        {
+            rtR0MemObjFixPageList(&pMemOs2->aPages[0], cPages, cPagesRet);
+            *ppMem = &pMemOs2->Core;
+            return VINF_SUCCESS;
+        }
+        KernVMFree(pMemOs2->Core.pv);
+    }
+    rtR0MemObjDelete(&pMemOs2->Core);
+    return RTErrConvertFromOS2(rc);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocLow(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    NOREF(fExecutable);
+
+    /* create the object. */
+    const ULONG cPages = cb >> PAGE_SHIFT;
+    PRTR0MEMOBJOS2 pMemOs2 = (PRTR0MEMOBJOS2)rtR0MemObjNew(RT_UOFFSETOF_DYN(RTR0MEMOBJOS2, aPages[cPages]),
+                                                           RTR0MEMOBJTYPE_LOW, NULL, cb);
+    if (!pMemOs2)
+        return VERR_NO_MEMORY;
+
+    /* do the allocation. */
+    int rc = KernVMAlloc(cb, VMDHA_FIXED, &pMemOs2->Core.pv, (PPVOID)-1, NULL);
+    if (!rc)
+    {
+        ULONG cPagesRet = cPages;
+        rc = KernLinToPageList(pMemOs2->Core.pv, cb, &pMemOs2->aPages[0], &cPagesRet);
+        if (!rc)
+        {
+            rtR0MemObjFixPageList(&pMemOs2->aPages[0], cPages, cPagesRet);
+            *ppMem = &pMemOs2->Core;
+            return VINF_SUCCESS;
+        }
+        KernVMFree(pMemOs2->Core.pv);
+    }
+    rtR0MemObjDelete(&pMemOs2->Core);
+    rc = RTErrConvertFromOS2(rc);
+    return rc == VERR_NO_MEMORY ? VERR_NO_LOW_MEMORY : rc;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocCont(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    NOREF(fExecutable);
+
+    /* create the object. */
+    PRTR0MEMOBJOS2 pMemOs2 = (PRTR0MEMOBJOS2)rtR0MemObjNew(RT_UOFFSETOF(RTR0MEMOBJOS2, Lock), RTR0MEMOBJTYPE_CONT, NULL, cb);
+    if (!pMemOs2)
+        return VERR_NO_MEMORY;
+
+    /* do the allocation. */
+    ULONG ulPhys = ~0UL;
+    int rc = KernVMAlloc(cb, VMDHA_FIXED | VMDHA_CONTIG, &pMemOs2->Core.pv, (PPVOID)&ulPhys, NULL);
+    if (!rc)
+    {
+        Assert(ulPhys != ~0UL);
+        pMemOs2->Core.u.Cont.Phys = ulPhys;
+        *ppMem = &pMemOs2->Core;
+        return VINF_SUCCESS;
+    }
+    rtR0MemObjDelete(&pMemOs2->Core);
+    return RTErrConvertFromOS2(rc);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocPhys(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, RTHCPHYS PhysHighest, size_t uAlignment)
+{
+    AssertMsgReturn(PhysHighest >= 16 *_1M, ("PhysHigest=%RHp\n", PhysHighest), VERR_NOT_SUPPORTED);
+
+    /** @todo alignment  */
+    if (uAlignment != PAGE_SIZE)
+        return VERR_NOT_SUPPORTED;
+
+    /* create the object. */
+    PRTR0MEMOBJOS2 pMemOs2 = (PRTR0MEMOBJOS2)rtR0MemObjNew(RT_UOFFSETOF(RTR0MEMOBJOS2, Lock), RTR0MEMOBJTYPE_PHYS, NULL, cb);
+    if (!pMemOs2)
+        return VERR_NO_MEMORY;
+
+    /* do the allocation. */
+    ULONG ulPhys = ~0UL;
+    int rc = KernVMAlloc(cb, VMDHA_FIXED | VMDHA_CONTIG | (PhysHighest < _4G ? VMDHA_16M : 0), &pMemOs2->Core.pv, (PPVOID)&ulPhys, NULL);
+    if (!rc)
+    {
+        Assert(ulPhys != ~0UL);
+        pMemOs2->Core.u.Phys.fAllocated = true;
+        pMemOs2->Core.u.Phys.PhysBase = ulPhys;
+        *ppMem = &pMemOs2->Core;
+        return VINF_SUCCESS;
+    }
+    rtR0MemObjDelete(&pMemOs2->Core);
+    return RTErrConvertFromOS2(rc);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocPhysNC(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, RTHCPHYS PhysHighest)
+{
+    /** @todo rtR0MemObjNativeAllocPhys / darwin. */
+    return rtR0MemObjNativeAllocPhys(ppMem, cb, PhysHighest, PAGE_SIZE);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeEnterPhys(PPRTR0MEMOBJINTERNAL ppMem, RTHCPHYS Phys, size_t cb, uint32_t uCachePolicy)
+{
+    AssertReturn(uCachePolicy == RTMEM_CACHE_POLICY_DONT_CARE, VERR_NOT_SUPPORTED);
+
+    /* create the object. */
+    PRTR0MEMOBJOS2 pMemOs2 = (PRTR0MEMOBJOS2)rtR0MemObjNew(RT_UOFFSETOF(RTR0MEMOBJOS2, Lock), RTR0MEMOBJTYPE_PHYS, NULL, cb);
+    if (!pMemOs2)
+        return VERR_NO_MEMORY;
+
+    /* there is no allocation here, right? it needs to be mapped somewhere first. */
+    pMemOs2->Core.u.Phys.fAllocated = false;
+    pMemOs2->Core.u.Phys.PhysBase = Phys;
+    pMemOs2->Core.u.Phys.uCachePolicy = uCachePolicy;
+    *ppMem = &pMemOs2->Core;
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeLockUser(PPRTR0MEMOBJINTERNAL ppMem, RTR3PTR R3Ptr, size_t cb, uint32_t fAccess,
+                                         RTR0PROCESS R0Process)
+{
+    AssertMsgReturn(R0Process == RTR0ProcHandleSelf(), ("%p != %p\n", R0Process, RTR0ProcHandleSelf()), VERR_NOT_SUPPORTED);
+
+    /* create the object. */
+    const ULONG cPages = cb >> PAGE_SHIFT;
+    PRTR0MEMOBJOS2 pMemOs2 = (PRTR0MEMOBJOS2)rtR0MemObjNew(RT_UOFFSETOF_DYN(RTR0MEMOBJOS2, aPages[cPages]),
+                                                           RTR0MEMOBJTYPE_LOCK, (void *)R3Ptr, cb);
+    if (!pMemOs2)
+        return VERR_NO_MEMORY;
+
+    /* lock it. */
+    ULONG cPagesRet = cPages;
+    int rc = KernVMLock(VMDHL_LONG | (fAccess & RTMEM_PROT_WRITE ? VMDHL_WRITE : 0),
+                        (void *)R3Ptr, cb, &pMemOs2->Lock, &pMemOs2->aPages[0], &cPagesRet);
+    if (!rc)
+    {
+        rtR0MemObjFixPageList(&pMemOs2->aPages[0], cPages, cPagesRet);
+        Assert(cb == pMemOs2->Core.cb);
+        Assert(R3Ptr == (RTR3PTR)pMemOs2->Core.pv);
+        pMemOs2->Core.u.Lock.R0Process = R0Process;
+        *ppMem = &pMemOs2->Core;
+        return VINF_SUCCESS;
+    }
+    rtR0MemObjDelete(&pMemOs2->Core);
+    return RTErrConvertFromOS2(rc);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeLockKernel(PPRTR0MEMOBJINTERNAL ppMem, void *pv, size_t cb, uint32_t fAccess)
+{
+    /* create the object. */
+    const ULONG cPages = cb >> PAGE_SHIFT;
+    PRTR0MEMOBJOS2 pMemOs2 = (PRTR0MEMOBJOS2)rtR0MemObjNew(RT_UOFFSETOF_DYN(RTR0MEMOBJOS2, aPages[cPages]),
+                                                           RTR0MEMOBJTYPE_LOCK, pv, cb);
+    if (!pMemOs2)
+        return VERR_NO_MEMORY;
+
+    /* lock it. */
+    ULONG cPagesRet = cPages;
+    int rc = KernVMLock(VMDHL_LONG | (fAccess & RTMEM_PROT_WRITE ? VMDHL_WRITE : 0),
+                        pv, cb, &pMemOs2->Lock, &pMemOs2->aPages[0], &cPagesRet);
+    if (!rc)
+    {
+        rtR0MemObjFixPageList(&pMemOs2->aPages[0], cPages, cPagesRet);
+        pMemOs2->Core.u.Lock.R0Process = NIL_RTR0PROCESS;
+        *ppMem = &pMemOs2->Core;
+        return VINF_SUCCESS;
+    }
+    rtR0MemObjDelete(&pMemOs2->Core);
+    return RTErrConvertFromOS2(rc);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeReserveKernel(PPRTR0MEMOBJINTERNAL ppMem, void *pvFixed, size_t cb, size_t uAlignment)
+{
+    RT_NOREF(ppMem, pvFixed, cb, uAlignment);
+    return VERR_NOT_SUPPORTED;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeReserveUser(PPRTR0MEMOBJINTERNAL ppMem, RTR3PTR R3PtrFixed, size_t cb, size_t uAlignment,
+                                            RTR0PROCESS R0Process)
+{
+    RT_NOREF(ppMem, R3PtrFixed, cb, uAlignment, R0Process);
+    return VERR_NOT_SUPPORTED;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeMapKernel(PPRTR0MEMOBJINTERNAL ppMem, RTR0MEMOBJ pMemToMap, void *pvFixed, size_t uAlignment,
+                                          unsigned fProt, size_t offSub, size_t cbSub)
+{
+    AssertMsgReturn(pvFixed == (void *)-1, ("%p\n", pvFixed), VERR_NOT_SUPPORTED);
+
+    /*
+     * Check that the specified alignment is supported.
+     */
+    if (uAlignment > PAGE_SIZE)
+        return VERR_NOT_SUPPORTED;
+
+/** @todo finish the implementation. */
+
+    int rc;
+    void *pvR0 = NULL;
+    PRTR0MEMOBJOS2 pMemToMapOs2 = (PRTR0MEMOBJOS2)pMemToMap;
+    switch (pMemToMapOs2->Core.enmType)
+    {
+        /*
+         * These has kernel mappings.
+         */
+        case RTR0MEMOBJTYPE_PAGE:
+        case RTR0MEMOBJTYPE_LOW:
+        case RTR0MEMOBJTYPE_CONT:
+            pvR0 = pMemToMapOs2->Core.pv;
+            break;
+
+        case RTR0MEMOBJTYPE_PHYS:
+            pvR0 = pMemToMapOs2->Core.pv;
+            if (!pvR0)
+            {
+                /* no ring-0 mapping, so allocate a mapping in the process. */
+                AssertMsgReturn(fProt & RTMEM_PROT_WRITE, ("%#x\n", fProt), VERR_NOT_SUPPORTED);
+                Assert(!pMemToMapOs2->Core.u.Phys.fAllocated);
+                ULONG ulPhys = (ULONG)pMemToMapOs2->Core.u.Phys.PhysBase;
+                AssertReturn(ulPhys == pMemToMapOs2->Core.u.Phys.PhysBase, VERR_OUT_OF_RANGE);
+                rc = KernVMAlloc(pMemToMapOs2->Core.cb, VMDHA_PHYS, &pvR0, (PPVOID)&ulPhys, NULL);
+                if (rc)
+                    return RTErrConvertFromOS2(rc);
+                pMemToMapOs2->Core.pv = pvR0;
+            }
+            break;
+
+        case RTR0MEMOBJTYPE_PHYS_NC:
+            AssertMsgFailed(("RTR0MEMOBJTYPE_PHYS_NC\n"));
+            return VERR_INTERNAL_ERROR_3;
+
+        case RTR0MEMOBJTYPE_LOCK:
+            if (pMemToMapOs2->Core.u.Lock.R0Process != NIL_RTR0PROCESS)
+                return VERR_NOT_SUPPORTED; /** @todo implement this... */
+            pvR0 = pMemToMapOs2->Core.pv;
+            break;
+
+        case RTR0MEMOBJTYPE_RES_VIRT:
+        case RTR0MEMOBJTYPE_MAPPING:
+        default:
+            AssertMsgFailed(("enmType=%d\n", pMemToMapOs2->Core.enmType));
+            return VERR_INTERNAL_ERROR;
+    }
+
+    /*
+     * Create a dummy mapping object for it.
+     *
+     * All mappings are read/write/execute in OS/2 and there isn't
+     * any cache options, so sharing is ok. And the main memory object
+     * isn't actually freed until all the mappings have been freed up
+     * (reference counting).
+     */
+    if (!cbSub)
+        cbSub = pMemToMapOs2->Core.cb - offSub;
+    PRTR0MEMOBJOS2 pMemOs2 = (PRTR0MEMOBJOS2)rtR0MemObjNew(RT_UOFFSETOF(RTR0MEMOBJOS2, Lock), RTR0MEMOBJTYPE_MAPPING,
+                                                           (uint8_t *)pvR0 + offSub, cbSub);
+    if (pMemOs2)
+    {
+        pMemOs2->Core.u.Mapping.R0Process = NIL_RTR0PROCESS;
+        *ppMem = &pMemOs2->Core;
+        return VINF_SUCCESS;
+    }
+    return VERR_NO_MEMORY;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeMapUser(PPRTR0MEMOBJINTERNAL ppMem, RTR0MEMOBJ pMemToMap, RTR3PTR R3PtrFixed, size_t uAlignment,
+                                        unsigned fProt, RTR0PROCESS R0Process, size_t offSub, size_t cbSub)
+{
+    AssertMsgReturn(R0Process == RTR0ProcHandleSelf(), ("%p != %p\n", R0Process, RTR0ProcHandleSelf()), VERR_NOT_SUPPORTED);
+    AssertMsgReturn(R3PtrFixed == (RTR3PTR)-1, ("%p\n", R3PtrFixed), VERR_NOT_SUPPORTED);
+    if (uAlignment > PAGE_SIZE)
+        return VERR_NOT_SUPPORTED;
+    AssertMsgReturn(!offSub && !cbSub, ("%#zx %#zx\n", offSub, cbSub), VERR_NOT_SUPPORTED); /** @todo implement sub maps */
+
+    int rc;
+    void *pvR0;
+    void *pvR3 = NULL;
+    PRTR0MEMOBJOS2 pMemToMapOs2 = (PRTR0MEMOBJOS2)pMemToMap;
+    switch (pMemToMapOs2->Core.enmType)
+    {
+        /*
+         * These has kernel mappings.
+         */
+        case RTR0MEMOBJTYPE_PAGE:
+        case RTR0MEMOBJTYPE_LOW:
+        case RTR0MEMOBJTYPE_CONT:
+            pvR0 = pMemToMapOs2->Core.pv;
+            break;
+
+        case RTR0MEMOBJTYPE_PHYS:
+            pvR0 = pMemToMapOs2->Core.pv;
+#if 0/* this is wrong. */
+            if (!pvR0)
+            {
+                /* no ring-0 mapping, so allocate a mapping in the process. */
+                AssertMsgReturn(fProt & RTMEM_PROT_WRITE, ("%#x\n", fProt), VERR_NOT_SUPPORTED);
+                Assert(!pMemToMapOs2->Core.u.Phys.fAllocated);
+                ULONG ulPhys = pMemToMapOs2->Core.u.Phys.PhysBase;
+                rc = KernVMAlloc(pMemToMapOs2->Core.cb, VMDHA_PHYS | VMDHA_PROCESS, &pvR3, (PPVOID)&ulPhys, NULL);
+                if (rc)
+                    return RTErrConvertFromOS2(rc);
+            }
+            break;
+#endif
+            return VERR_NOT_SUPPORTED;
+
+        case RTR0MEMOBJTYPE_PHYS_NC:
+            AssertMsgFailed(("RTR0MEMOBJTYPE_PHYS_NC\n"));
+            return VERR_INTERNAL_ERROR_5;
+
+        case RTR0MEMOBJTYPE_LOCK:
+            if (pMemToMapOs2->Core.u.Lock.R0Process != NIL_RTR0PROCESS)
+                return VERR_NOT_SUPPORTED; /** @todo implement this... */
+            pvR0 = pMemToMapOs2->Core.pv;
+            break;
+
+        case RTR0MEMOBJTYPE_RES_VIRT:
+        case RTR0MEMOBJTYPE_MAPPING:
+        default:
+            AssertMsgFailed(("enmType=%d\n", pMemToMapOs2->Core.enmType));
+            return VERR_INTERNAL_ERROR;
+    }
+
+    /*
+     * Map the ring-0 memory into the current process.
+     */
+    if (!pvR3)
+    {
+        Assert(pvR0);
+        ULONG flFlags = 0;
+        if (uAlignment == PAGE_SIZE)
+            flFlags |= VMDHGP_4MB;
+        if (fProt & RTMEM_PROT_WRITE)
+            flFlags |= VMDHGP_WRITE;
+        rc = RTR0Os2DHVMGlobalToProcess(flFlags, pvR0, pMemToMapOs2->Core.cb, &pvR3);
+        if (rc)
+            return RTErrConvertFromOS2(rc);
+    }
+    Assert(pvR3);
+
+    /*
+     * Create a mapping object for it.
+     */
+    PRTR0MEMOBJOS2 pMemOs2 = (PRTR0MEMOBJOS2)rtR0MemObjNew(RT_UOFFSETOF(RTR0MEMOBJOS2, Lock), RTR0MEMOBJTYPE_MAPPING,
+                                                           pvR3, pMemToMapOs2->Core.cb);
+    if (pMemOs2)
+    {
+        Assert(pMemOs2->Core.pv == pvR3);
+        pMemOs2->Core.u.Mapping.R0Process = R0Process;
+        *ppMem = &pMemOs2->Core;
+        return VINF_SUCCESS;
+    }
+    KernVMFree(pvR3);
+    return VERR_NO_MEMORY;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeProtect(PRTR0MEMOBJINTERNAL pMem, size_t offSub, size_t cbSub, uint32_t fProt)
+{
+    NOREF(pMem);
+    NOREF(offSub);
+    NOREF(cbSub);
+    NOREF(fProt);
+    return VERR_NOT_SUPPORTED;
+}
+
+
+DECLHIDDEN(RTHCPHYS) rtR0MemObjNativeGetPagePhysAddr(PRTR0MEMOBJINTERNAL pMem, size_t iPage)
+{
+    PRTR0MEMOBJOS2 pMemOs2 = (PRTR0MEMOBJOS2)pMem;
+
+    switch (pMemOs2->Core.enmType)
+    {
+        case RTR0MEMOBJTYPE_PAGE:
+        case RTR0MEMOBJTYPE_LOW:
+        case RTR0MEMOBJTYPE_LOCK:
+        case RTR0MEMOBJTYPE_PHYS_NC:
+            return pMemOs2->aPages[iPage].Addr;
+
+        case RTR0MEMOBJTYPE_CONT:
+            return pMemOs2->Core.u.Cont.Phys + (iPage << PAGE_SHIFT);
+
+        case RTR0MEMOBJTYPE_PHYS:
+            return pMemOs2->Core.u.Phys.PhysBase + (iPage << PAGE_SHIFT);
+
+        case RTR0MEMOBJTYPE_RES_VIRT:
+        case RTR0MEMOBJTYPE_MAPPING:
+        default:
+            return NIL_RTHCPHYS;
+    }
+}
+
+
+/**
+ * Expands the page list so we can index pages directly.
+ *
+ * @param   paPages         The page list array to fix.
+ * @param   cPages          The number of pages that's supposed to go into the list.
+ * @param   cPagesRet       The actual number of pages in the list.
+ */
+static void rtR0MemObjFixPageList(KernPageList_t *paPages, ULONG cPages, ULONG cPagesRet)
+{
+    Assert(cPages >= cPagesRet);
+    if (cPages != cPagesRet)
+    {
+        ULONG iIn = cPagesRet;
+        ULONG iOut = cPages;
+        do
+        {
+            iIn--;
+            iOut--;
+            Assert(iIn <= iOut);
+
+            KernPageList_t Page = paPages[iIn];
+            Assert(!(Page.Addr & PAGE_OFFSET_MASK));
+            Assert(Page.Size == RT_ALIGN_Z(Page.Size, PAGE_SIZE));
+
+            if (Page.Size > PAGE_SIZE)
+            {
+                do
+                {
+                    Page.Size -= PAGE_SIZE;
+                    paPages[iOut].Addr = Page.Addr + Page.Size;
+                    paPages[iOut].Size = PAGE_SIZE;
+                    iOut--;
+                } while (Page.Size > PAGE_SIZE);
+            }
+
+            paPages[iOut].Addr = Page.Addr;
+            paPages[iOut].Size = PAGE_SIZE;
+        } while (   iIn != iOut
+                 && iIn > 0);
+    }
+}
+
diff --git a/src/VBox/Runtime/r0drv/os2/memuserkernel-r0drv-os2.cpp b/src/VBox/Runtime/r0drv/os2/memuserkernel-r0drv-os2.cpp
new file mode 100644
index 00000000..67350ae3
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/os2/memuserkernel-r0drv-os2.cpp
@@ -0,0 +1,91 @@
+/* $Id: memuserkernel-r0drv-os2.cpp $ */
+/** @file
+ * IPRT - User & Kernel Memory, Ring-0 Driver, OS/2.
+ */
+
+/*
+ * Copyright (C) 2009-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-os2-kernel.h"
+
+#include <iprt/mem.h>
+#include <iprt/errcore.h>
+
+
+RTR0DECL(int) RTR0MemUserCopyFrom(void *pvDst, RTR3PTR R3PtrSrc, size_t cb)
+{
+    int rc = KernCopyIn(pvDst, (void *)R3PtrSrc, cb);
+    if (RT_LIKELY(rc == 0))
+        return VINF_SUCCESS;
+    return VERR_ACCESS_DENIED;
+}
+
+
+RTR0DECL(int) RTR0MemUserCopyTo(RTR3PTR R3PtrDst, void const *pvSrc, size_t cb)
+{
+    int rc = KernCopyOut((void *)R3PtrDst, (void *)pvSrc, cb);
+    if (RT_LIKELY(rc == 0))
+        return VINF_SUCCESS;
+    return VERR_ACCESS_DENIED;
+}
+
+
+RTR0DECL(bool) RTR0MemUserIsValidAddr(RTR3PTR R3Ptr)
+{
+    /** @todo this is all wrong, but I'm too lazy to figure out how to make it
+     *        correct. Checking the user DS limit would work if it wasn't maxed
+     *        out by SDD, VPC or someone. The version (+SMP) would help on older
+     *        OS/2 versions where the limit is 512MB. */
+    return R3Ptr < UINT32_C(0xc0000000); /* 3GB */
+}
+
+
+RTR0DECL(bool) RTR0MemKernelIsValidAddr(void *pv)
+{
+    /** @todo this is all wrong, see RTR0MemUserIsValidAddr. */
+    return (uintptr_t)pv >= UINT32_C(0x20000000); /* 512MB */
+}
+
+
+RTR0DECL(bool) RTR0MemAreKrnlAndUsrDifferent(void)
+{
+    /** @todo this is all wrong, see RTR0MemUserIsValidAddr. */
+    return false;
+}
+
+
+RTR0DECL(int) RTR0MemKernelCopyFrom(void *pvDst, void const *pvSrc, size_t cb)
+{
+    RT_NOREF(pvDst, pvSrc, cb);
+    return VERR_NOT_SUPPORTED;
+}
+
+
+RTR0DECL(int) RTR0MemKernelCopyTo(void *pvDst, void const *pvSrc, size_t cb)
+{
+    RT_NOREF(pvDst, pvSrc, cb);
+    return VERR_NOT_SUPPORTED;
+}
+
diff --git a/src/VBox/Runtime/r0drv/os2/os2imports.imp b/src/VBox/Runtime/r0drv/os2/os2imports.imp
new file mode 100644
index 00000000..26feb406
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/os2/os2imports.imp
@@ -0,0 +1,121 @@
+;
+; DOSCALLS
+;
+DOS16OPEN DOSCALLS 70 ?
+DOS16CLOSE DOSCALLS 59 ?
+DOS16READ DOSCALLS 137 ?
+DOS16WRITE DOSCALL1 138 ?
+DOS16IREAD DOSCALL1 79 ?
+DOS16IWRITE DOSCALL1 87 ?
+DOS16DEVIOCTL DOSCALL1 53 ?
+DOS16DEVIOCTL2 DOSCALL1 99 ?
+DOS16FSATTACH DOSCALL1 181 ?
+DOS16FSCTL DOSCALL1 183 ?
+
+;
+; KEE
+;
+KernAllocSpinLock       KEE       10 ?
+KernFreeSpinLock        KEE       11 ?
+KernAcquireSpinLock     KEE       12 ?
+KernReleaseSpinLock     KEE       13 ?
+KernAllocMutexLock      KEE       20 ?
+KernFreeMutexLock       KEE       21 ?
+KernRequestSharedMutex  KEE       22 ?
+KernReleaseSharedMutex  KEE       23 ?
+KernTryRequestSharedMutex KEE       24 ?
+KernRequestExclusiveMutex KEE       25 ?
+KernReleaseExclusiveMutex KEE       26 ?
+KernTryRequestExclusiveMutex KEE       27 ?
+KernBlock               KEE       30 ?
+KernWakeup              KEE       31 ?
+KernThunkStackTo16      KEE       40 ?
+KernThunkStackTo32      KEE       41 ?
+KernSerialize16BitDD    KEE       42 ?
+KernUnserialize16BitDD  KEE       43 ?
+KernArmHook             KEE       44 ?
+KernAllocateContextHook KEE       45 ?
+KernCopyIn              KEE       50 ?
+KernCopyOut             KEE       51 ?
+KernVMAlloc             KEE       60 ?
+KernVMFree              KEE       61 ?
+KernVMLock              KEE       62 ?
+KernVMUnlock            KEE       63 ?
+KernLinToPageList       KEE       64 ?
+KernVMSetMem            KEE       65 ?
+KernSelToFlat           KEE       66 ?
+KernDynamicAPI          KEE       70 ?
+KernRASSysTrace         KEE       80 ?
+KernPerfSysTrace        KEE       81 ?
+_KernSISData            KEE       90 ?
+_KernLISData            KEE       91 ?
+_KernInterruptLevel     KEE       92 ?
+_KernTKSSBase           KEE       93 ?
+_KernKEEVersion         KEE       94 ?
+KernLockFile            KEE      100 ?
+KernUnLockFile          KEE      101 ?
+KernGetFileSize         KEE      102 ?
+KernTestFileCache       KEE      103 ?
+KernReadFileAt          KEE      104 ?
+KernReadFileAtCache     KEE      105 ?
+KernReturnFileCache     KEE      106 ?
+KernCreateUconvObject   KEE      120 ?
+KernStrFromUcs          KEE      121 ?
+KernStrToUcs            KEE      122 ?
+
+FSH_SEGALLOC            FSHELPER   1 ?
+FSH_SEGFREE             FSHELPER   2 ?
+FSH_SEGREALLOC          FSHELPER   3 ?
+FSH_FORCENOSWAP         FSHELPER   4 ?
+FSH_INTERR              FSHELPER   5 ?
+FSH_SEMREQUEST          FSHELPER   6 ?
+FSH_SEMCLEAR            FSHELPER   7 ?
+FSH_PROBEBUF            FSHELPER   8 ?
+FSH_GETPRIORITY         FSHELPER   9 ?
+FSH_IOSEMCLEAR          FSHELPER  10 ?
+FSH_FLUSHBUF            FSHELPER  11 ?
+FSH_CRITERROR           FSHELPER  12 ?
+FSH_DEVIOCTL            FSHELPER  13 ?
+FSH_GETVOLPARM          FSHELPER  14 ?
+FSH_FINDDUPHVPB         FSHELPER  15 ?
+FSH_DOVOLIO             FSHELPER  16 ?
+FSH_ADDSHARE            FSHELPER  17 ?
+FSH_REMOVESHARE         FSHELPER  18 ?
+FSH_GETOVERLAPBUF       FSHELPER  19 ?
+FSH_ISCURDIRPREFIX      FSHELPER  20 ?
+FSH_LOADCHAR            FSHELPER  21 ?
+FSH_PREVCHAR            FSHELPER  22 ?
+FSH_STORECHAR           FSHELPER  23 ?
+FSH_SEMSET              FSHELPER  24 ?
+FSH_SEMSETWAIT          FSHELPER  25 ?
+FSH_SEMWAIT             FSHELPER  26 ?
+FSH_WILDMATCH           FSHELPER  27 ?
+FSH_YIELD               FSHELPER  28 ?
+FSH_DOVOLIO2            FSHELPER  29 ?
+FSH_FINDCHAR            FSHELPER  30 ?
+MFSH_SETBOOTDRIVE       FSHELPER  31 ?
+FSH_CANONICALIZE        FSHELPER  32 ?
+MFSH_DOVOLIO            FSHELPER  33 ?
+MFSH_INTERR             FSHELPER  34 ?
+MFSH_SEGALLOC           FSHELPER  35 ?
+MFSH_SEGFREE            FSHELPER  36 ?
+MFSH_SEGREALLOC         FSHELPER  37 ?
+MFSH_CALLRM             FSHELPER  38 ?
+MFSH_LOCK               FSHELPER  39 ?
+MFSH_PHYSTOVIRT         FSHELPER  40 ?
+MFSH_UNLOCK             FSHELPER  41 ?
+MFSH_UNPHYSTOVIRT       FSHELPER  42 ?
+MFSH_VIRT2PHYS          FSHELPER  43 ?
+FSH_QSYSINFO            FSHELPER  44 ?
+FSH_NAMEFROMSFN         FSHELPER  45 ?
+FSH_UPPERCASE           FSHELPER  46 ?
+FSH_CHECKEANAME         FSHELPER  47 ?
+FSH_CALLDRIVER          FSHELPER  48 ?
+FSH_SETVOLUME           FSHELPER  49 ?
+FSH_STACKSPACE          FSHELPER  50 ?
+FSH_REGISTERPERFCTRS    FSHELPER  51 ?
+FSH_IOBOOST             FSHELPER  52 ?
+FSH_QUERYSERVERTHREAD   FSHELPER  53 ?
+FSH_QUERYOPLOCK         FSHELPER  54 ?
+FSH_EXTENDTIMESLICE     FSHELPER  55 ?
+
diff --git a/src/VBox/Runtime/r0drv/os2/process-r0drv-os2.cpp b/src/VBox/Runtime/r0drv/os2/process-r0drv-os2.cpp
new file mode 100644
index 00000000..5e3a64f3
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/os2/process-r0drv-os2.cpp
@@ -0,0 +1,78 @@
+/* $Id: process-r0drv-os2.cpp $ */
+/** @file
+ * IPRT - Process Management, Ring-0 Driver, OS/2.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-os2-kernel.h"
+
+#include <iprt/process.h>
+#include <iprt/assert.h>
+
+
+RTDECL(RTPROCESS) RTProcSelf(void)
+{
+    PLINFOSEG pLIS = (PLINFOSEG)RTR0Os2Virt2Flat(g_fpLIS);
+    AssertReturn(pLIS, NIL_RTPROCESS);
+    return pLIS->pidCurrent;
+}
+
+
+RTR0DECL(RTR0PROCESS) RTR0ProcHandleSelf(void)
+{
+    /* make this ptda later...  */
+    return (RTR0PROCESS)RTProcSelf();
+}
+
diff --git a/src/VBox/Runtime/r0drv/os2/semevent-r0drv-os2.cpp b/src/VBox/Runtime/r0drv/os2/semevent-r0drv-os2.cpp
new file mode 100644
index 00000000..b2592946
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/os2/semevent-r0drv-os2.cpp
@@ -0,0 +1,295 @@
+/* $Id: semevent-r0drv-os2.cpp $ */
+/** @file
+ * IPRT - Single Release Event Semaphores, Ring-0 Driver, OS/2.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-os2-kernel.h"
+#include "internal/iprt.h"
+
+#include <iprt/semaphore.h>
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/mem.h>
+#include <iprt/lockvalidator.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * OS/2 event semaphore.
+ */
+typedef struct RTSEMEVENTINTERNAL
+{
+    /** Magic value (RTSEMEVENT_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** The number of waiting threads. */
+    uint32_t volatile   cWaiters;
+    /** Set if the event object is signaled. */
+    uint8_t volatile    fSignaled;
+    /** The number of threads in the process of waking up. */
+    uint32_t volatile   cWaking;
+    /** The OS/2 spinlock protecting this structure. */
+    SpinLock_t          Spinlock;
+} RTSEMEVENTINTERNAL, *PRTSEMEVENTINTERNAL;
+
+
+RTDECL(int)  RTSemEventCreate(PRTSEMEVENT phEventSem)
+{
+    return RTSemEventCreateEx(phEventSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, NULL);
+}
+
+
+RTDECL(int)  RTSemEventCreateEx(PRTSEMEVENT phEventSem, uint32_t fFlags, RTLOCKVALCLASS hClass, const char *pszNameFmt, ...)
+{
+    AssertReturn(!(fFlags & ~(RTSEMEVENT_FLAGS_NO_LOCK_VAL | RTSEMEVENT_FLAGS_BOOTSTRAP_HACK)), VERR_INVALID_PARAMETER);
+    Assert(!(fFlags & RTSEMEVENT_FLAGS_BOOTSTRAP_HACK) || (fFlags & RTSEMEVENT_FLAGS_NO_LOCK_VAL));
+    AssertCompile(sizeof(RTSEMEVENTINTERNAL) > sizeof(void *));
+    AssertPtrReturn(phEventSem, VERR_INVALID_POINTER);
+    RT_NOREF(hClass, pszNameFmt);
+
+    PRTSEMEVENTINTERNAL pThis = (PRTSEMEVENTINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (!pThis)
+        return VERR_NO_MEMORY;
+
+    pThis->u32Magic = RTSEMEVENT_MAGIC;
+    pThis->cWaiters = 0;
+    pThis->cWaking = 0;
+    pThis->fSignaled = 0;
+    KernAllocSpinLock(&pThis->Spinlock);
+
+    *phEventSem = pThis;
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemEventDestroy(RTSEMEVENT hEventSem)
+{
+    PRTSEMEVENTINTERNAL pThis = hEventSem;
+    if (pThis == NIL_RTSEMEVENT)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+
+    KernAcquireSpinLock(&pThis->Spinlock);
+    ASMAtomicIncU32(&pThis->u32Magic); /* make the handle invalid */
+    if (pThis->cWaiters > 0)
+    {
+        /* abort waiting thread, last man cleans up. */
+        ASMAtomicXchgU32(&pThis->cWaking, pThis->cWaking + pThis->cWaiters);
+        ULONG cThreads;
+        KernWakeup((ULONG)pThis, WAKEUP_DATA | WAKEUP_BOOST, &cThreads, (ULONG)VERR_SEM_DESTROYED);
+        KernReleaseSpinLock(&pThis->Spinlock);
+    }
+    else if (pThis->cWaking)
+        /* the last waking thread is gonna do the cleanup */
+        KernReleaseSpinLock(&pThis->Spinlock);
+    else
+    {
+        KernReleaseSpinLock(&pThis->Spinlock);
+        KernFreeSpinLock(&pThis->Spinlock);
+        RTMemFree(pThis);
+    }
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemEventSignal(RTSEMEVENT hEventSem)
+{
+    PRTSEMEVENTINTERNAL pThis = (PRTSEMEVENTINTERNAL)hEventSem;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+
+    KernAcquireSpinLock(&pThis->Spinlock);
+
+    if (pThis->cWaiters > 0)
+    {
+        ASMAtomicDecU32(&pThis->cWaiters);
+        ASMAtomicIncU32(&pThis->cWaking);
+        ULONG cThreads;
+        KernWakeup((ULONG)pThis, WAKEUP_DATA | WAKEUP_ONE, &cThreads, VINF_SUCCESS);
+        if (RT_UNLIKELY(!cThreads))
+        {
+            /* shouldn't ever happen on OS/2 */
+            ASMAtomicXchgU8(&pThis->fSignaled, true);
+            ASMAtomicDecU32(&pThis->cWaking);
+            ASMAtomicIncU32(&pThis->cWaiters);
+        }
+    }
+    else
+        ASMAtomicXchgU8(&pThis->fSignaled, true);
+
+    KernReleaseSpinLock(&pThis->Spinlock);
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Worker for RTSemEventWaitEx and RTSemEventWaitExDebug.
+ *
+ * @returns VBox status code.
+ * @param   pThis           The event semaphore.
+ * @param   fFlags          See RTSemEventWaitEx.
+ * @param   uTimeout        See RTSemEventWaitEx.
+ * @param   pSrcPos         The source code position of the wait.
+ */
+static int rtR0SemEventOs2Wait(PRTSEMEVENTINTERNAL pThis, uint32_t fFlags, uint64_t uTimeout,
+                               PCRTLOCKVALSRCPOS pSrcPos)
+{
+    /*
+     * Validate and convert input.
+     */
+    if (!pThis)
+        return VERR_INVALID_HANDLE;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+    AssertReturn(RTSEMWAIT_FLAGS_ARE_VALID(fFlags), VERR_INVALID_PARAMETER);
+
+    ULONG cMsTimeout = rtR0SemWaitOs2ConvertTimeout(fFlags, uTimeout);
+    ULONG fBlock     = BLOCK_SPINLOCK;
+    if (!(fFlags & RTSEMWAIT_FLAGS_INTERRUPTIBLE))
+        fBlock |= BLOCK_UNINTERRUPTABLE;
+
+    /*
+     * Do the job.
+     */
+    KernAcquireSpinLock(&pThis->Spinlock);
+
+    int rc;
+    if (pThis->fSignaled)
+    {
+        Assert(!pThis->cWaiters);
+        ASMAtomicXchgU8(&pThis->fSignaled, false);
+        rc = VINF_SUCCESS;
+    }
+    else
+    {
+        ASMAtomicIncU32(&pThis->cWaiters);
+
+        ULONG ulData = (ULONG)VERR_INTERNAL_ERROR;
+        rc = KernBlock((ULONG)pThis, cMsTimeout, fBlock,
+                       &pThis->Spinlock,
+                       &ulData);
+        switch (rc)
+        {
+            case NO_ERROR:
+                rc = (int)ulData;
+                Assert(rc == VINF_SUCCESS || rc == VERR_SEM_DESTROYED);
+                Assert(pThis->cWaking > 0);
+                if (    !ASMAtomicDecU32(&pThis->cWaking)
+                    &&  pThis->u32Magic != RTSEMEVENT_MAGIC)
+                {
+                    /* The event was destroyed (ulData == VINF_SUCCESS if it was after we awoke), as
+                       the last thread do the cleanup. */
+                    KernReleaseSpinLock(&pThis->Spinlock);
+                    KernFreeSpinLock(&pThis->Spinlock);
+                    RTMemFree(pThis);
+                    return rc;
+                }
+                break;
+
+            case ERROR_TIMEOUT:
+                Assert(cMsTimeout != SEM_INDEFINITE_WAIT);
+                ASMAtomicDecU32(&pThis->cWaiters);
+                rc = VERR_TIMEOUT;
+                break;
+
+            case ERROR_INTERRUPT:
+                Assert(fFlags & RTSEMWAIT_FLAGS_INTERRUPTIBLE);
+                ASMAtomicDecU32(&pThis->cWaiters);
+                rc = VERR_INTERRUPTED;
+                break;
+
+            default:
+                AssertMsgFailed(("rc=%d\n", rc));
+                rc = VERR_GENERAL_FAILURE;
+                break;
+        }
+    }
+
+    KernReleaseSpinLock(&pThis->Spinlock);
+    return rc;
+}
+
+
+RTDECL(int)  RTSemEventWaitEx(RTSEMEVENT hEventSem, uint32_t fFlags, uint64_t uTimeout)
+{
+#ifndef RTSEMEVENT_STRICT
+    return rtR0SemEventOs2Wait(hEventSem, fFlags, uTimeout, NULL);
+#else
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
+    return rtR0SemEventOs2Wait(hEventSem, fFlags, uTimeout, &SrcPos);
+#endif
+}
+
+
+RTDECL(int)  RTSemEventWaitExDebug(RTSEMEVENT hEventSem, uint32_t fFlags, uint64_t uTimeout,
+                                   RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
+    return rtR0SemEventOs2Wait(hEventSem, fFlags, uTimeout, &SrcPos);
+}
+
+
+RTDECL(uint32_t) RTSemEventGetResolution(void)
+{
+    return 32000000; /* 32ms */
+}
+
diff --git a/src/VBox/Runtime/r0drv/os2/semeventmulti-r0drv-os2.cpp b/src/VBox/Runtime/r0drv/os2/semeventmulti-r0drv-os2.cpp
new file mode 100644
index 00000000..5af415ea
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/os2/semeventmulti-r0drv-os2.cpp
@@ -0,0 +1,305 @@
+/* $Id: semeventmulti-r0drv-os2.cpp $ */
+/** @file
+ * IPRT - Multiple Release Event Semaphores, Ring-0 Driver, OS/2.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-os2-kernel.h"
+#include "internal/iprt.h"
+
+#include <iprt/semaphore.h>
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/lockvalidator.h>
+#include <iprt/mem.h>
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * OS/2 multiple release event semaphore.
+ */
+typedef struct RTSEMEVENTMULTIINTERNAL
+{
+    /** Magic value (RTSEMEVENTMULTI_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** The number of waiting threads. */
+    uint32_t volatile   cWaiters;
+    /** Set if the event object is signaled. */
+    uint8_t volatile    fSignaled;
+    /** The number of threads in the process of waking up. */
+    uint32_t volatile   cWaking;
+    /** The OS/2 spinlock protecting this structure. */
+    SpinLock_t          Spinlock;
+} RTSEMEVENTMULTIINTERNAL, *PRTSEMEVENTMULTIINTERNAL;
+
+
+RTDECL(int)  RTSemEventMultiCreate(PRTSEMEVENTMULTI phEventMultiSem)
+{
+    return RTSemEventMultiCreateEx(phEventMultiSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, NULL);
+}
+
+
+RTDECL(int)  RTSemEventMultiCreateEx(PRTSEMEVENTMULTI phEventMultiSem, uint32_t fFlags, RTLOCKVALCLASS hClass,
+                                     const char *pszNameFmt, ...)
+{
+    AssertReturn(!(fFlags & ~RTSEMEVENTMULTI_FLAGS_NO_LOCK_VAL), VERR_INVALID_PARAMETER);
+    AssertPtrReturn(phEventMultiSem, VERR_INVALID_POINTER);
+
+    AssertCompile(sizeof(RTSEMEVENTMULTIINTERNAL) > sizeof(void *));
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (pThis)
+    {
+        pThis->u32Magic = RTSEMEVENTMULTI_MAGIC;
+        pThis->cWaiters = 0;
+        pThis->cWaking = 0;
+        pThis->fSignaled = 0;
+        KernAllocSpinLock(&pThis->Spinlock);
+
+        *phEventMultiSem = pThis;
+        return VINF_SUCCESS;
+    }
+    RT_NOREF(hClass, pszNameFmt);
+    return VERR_NO_MEMORY;
+}
+
+
+RTDECL(int)  RTSemEventMultiDestroy(RTSEMEVENTMULTI hEventMultiSem)
+{
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    if (pThis == NIL_RTSEMEVENTMULTI)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    KernAcquireSpinLock(&pThis->Spinlock);
+    ASMAtomicIncU32(&pThis->u32Magic); /* make the handle invalid */
+    if (pThis->cWaiters > 0)
+    {
+        /* abort waiting thread, last man cleans up. */
+        ASMAtomicXchgU32(&pThis->cWaking, pThis->cWaking + pThis->cWaiters);
+        ULONG cThreads;
+        KernWakeup((ULONG)pThis, WAKEUP_DATA | WAKEUP_BOOST, &cThreads, (ULONG)VERR_SEM_DESTROYED);
+        KernReleaseSpinLock(&pThis->Spinlock);
+    }
+    else if (pThis->cWaking)
+        /* the last waking thread is gonna do the cleanup */
+        KernReleaseSpinLock(&pThis->Spinlock);
+    else
+    {
+        KernReleaseSpinLock(&pThis->Spinlock);
+        KernFreeSpinLock(&pThis->Spinlock);
+        RTMemFree(pThis);
+    }
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemEventMultiSignal(RTSEMEVENTMULTI hEventMultiSem)
+{
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC,
+                    ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic),
+                    VERR_INVALID_HANDLE);
+
+    KernAcquireSpinLock(&pThis->Spinlock);
+
+    ASMAtomicXchgU8(&pThis->fSignaled, true);
+    if (pThis->cWaiters > 0)
+    {
+        ASMAtomicXchgU32(&pThis->cWaking, pThis->cWaking + pThis->cWaiters);
+        ASMAtomicXchgU32(&pThis->cWaiters, 0);
+        ULONG cThreads;
+        KernWakeup((ULONG)pThis, WAKEUP_DATA, &cThreads, VINF_SUCCESS);
+    }
+
+    KernReleaseSpinLock(&pThis->Spinlock);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemEventMultiReset(RTSEMEVENTMULTI hEventMultiSem)
+{
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC,
+                    ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic),
+                    VERR_INVALID_HANDLE);
+
+    KernAcquireSpinLock(&pThis->Spinlock);
+    ASMAtomicXchgU8(&pThis->fSignaled, false);
+    KernReleaseSpinLock(&pThis->Spinlock);
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Worker for RTSemEventWaitEx and RTSemEventWaitExDebug.
+ *
+ * @returns VBox status code.
+ * @param   pThis           The event semaphore.
+ * @param   fFlags          See RTSemEventWaitEx.
+ * @param   uTimeout        See RTSemEventWaitEx.
+ * @param   pSrcPos         The source code position of the wait.
+ */
+static int rtR0SemEventMultiOs2Wait(PRTSEMEVENTMULTIINTERNAL pThis, uint32_t fFlags, uint64_t uTimeout,
+                                    PCRTLOCKVALSRCPOS pSrcPos)
+{
+    RT_NOREF(pSrcPos);
+
+    /*
+     * Validate and convert the input.
+     */
+    if (!pThis)
+        return VERR_INVALID_HANDLE;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC,
+                    ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic),
+                    VERR_INVALID_HANDLE);
+    AssertReturn(RTSEMWAIT_FLAGS_ARE_VALID(fFlags), VERR_INVALID_PARAMETER);
+
+    ULONG cMsTimeout = rtR0SemWaitOs2ConvertTimeout(fFlags, uTimeout);
+    ULONG fBlock     = BLOCK_SPINLOCK;
+    if (!(fFlags & RTSEMWAIT_FLAGS_INTERRUPTIBLE))
+        fBlock |= BLOCK_UNINTERRUPTABLE;
+
+    /*
+     * Do the job.
+     */
+    KernAcquireSpinLock(&pThis->Spinlock);
+
+    int rc;
+    if (pThis->fSignaled)
+        rc = VINF_SUCCESS;
+    else
+    {
+        ASMAtomicIncU32(&pThis->cWaiters);
+
+        ULONG ulData = (ULONG)VERR_INTERNAL_ERROR;
+        rc = KernBlock((ULONG)pThis, cMsTimeout, fBlock,
+                       &pThis->Spinlock,
+                       &ulData);
+        switch (rc)
+        {
+            case NO_ERROR:
+                rc = (int)ulData;
+                Assert(rc == VINF_SUCCESS || rc == VERR_SEM_DESTROYED);
+                Assert(pThis->cWaking > 0);
+                if (    !ASMAtomicDecU32(&pThis->cWaking)
+                    &&  pThis->u32Magic != RTSEMEVENTMULTI_MAGIC)
+                {
+                    /* The event was destroyed (ulData == VINF_SUCCESS if it was after we awoke), as
+                       the last thread do the cleanup. */
+                    KernReleaseSpinLock(&pThis->Spinlock);
+                    KernFreeSpinLock(&pThis->Spinlock);
+                    RTMemFree(pThis);
+                    return VINF_SUCCESS;
+                }
+                rc = VINF_SUCCESS;
+                break;
+
+            case ERROR_TIMEOUT:
+                Assert(cMsTimeout != SEM_INDEFINITE_WAIT);
+                ASMAtomicDecU32(&pThis->cWaiters);
+                rc = VERR_TIMEOUT;
+                break;
+
+            case ERROR_INTERRUPT:
+                Assert(fFlags & RTSEMWAIT_FLAGS_INTERRUPTIBLE);
+                ASMAtomicDecU32(&pThis->cWaiters);
+                rc = VERR_INTERRUPTED;
+                break;
+
+            default:
+                AssertMsgFailed(("rc=%d\n", rc));
+                rc = VERR_GENERAL_FAILURE;
+                break;
+        }
+    }
+
+    KernReleaseSpinLock(&pThis->Spinlock);
+    return rc;
+}
+
+
+RTDECL(int)  RTSemEventMultiWaitEx(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout)
+{
+#ifndef RTSEMEVENT_STRICT
+    return rtR0SemEventMultiOs2Wait(hEventMultiSem, fFlags, uTimeout, NULL);
+#else
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
+    return rtR0SemEventMultiOs2Wait(hEventMultiSem, fFlags, uTimeout, &SrcPos);
+#endif
+}
+
+
+RTDECL(int)  RTSemEventMultiWaitExDebug(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout,
+                                        RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
+    return rtR0SemEventMultiOs2Wait(hEventMultiSem, fFlags, uTimeout, &SrcPos);
+}
+
+
+RTDECL(uint32_t) RTSemEventMultiGetResolution(void)
+{
+    return 32000000; /* 32ms */
+}
+
diff --git a/src/VBox/Runtime/r0drv/os2/semfastmutex-r0drv-os2.cpp b/src/VBox/Runtime/r0drv/os2/semfastmutex-r0drv-os2.cpp
new file mode 100644
index 00000000..f6f7c74c
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/os2/semfastmutex-r0drv-os2.cpp
@@ -0,0 +1,139 @@
+/* $Id: semfastmutex-r0drv-os2.cpp $ */
+/** @file
+ * IPRT - Fast Mutex Semaphores, Ring-0 Driver, OS/2.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-os2-kernel.h"
+
+#include <iprt/semaphore.h>
+#include <iprt/errcore.h>
+#include <iprt/alloc.h>
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Wrapper for the OS/2 KEE mutex semaphore.
+ */
+typedef struct RTSEMFASTMUTEXINTERNAL
+{
+    /** Magic value (RTSEMFASTMUTEX_MAGIC). */
+    uint32_t            u32Magic;
+    /** The KEE mutex. */
+    MutexLock_t         Mtx;
+} RTSEMFASTMUTEXINTERNAL, *PRTSEMFASTMUTEXINTERNAL;
+
+
+RTDECL(int)  RTSemFastMutexCreate(PRTSEMFASTMUTEX phFastMtx)
+{
+    AssertCompile(sizeof(RTSEMFASTMUTEXINTERNAL) > sizeof(void *));
+    AssertPtrReturn(phFastMtx, VERR_INVALID_POINTER);
+
+    PRTSEMFASTMUTEXINTERNAL pThis = (PRTSEMFASTMUTEXINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (pThis)
+    {
+        pThis->u32Magic = RTSEMFASTMUTEX_MAGIC;
+        KernAllocMutexLock(&pThis->Mtx);
+
+        *phFastMtx = pThis;
+        return VINF_SUCCESS;
+    }
+    return VERR_NO_MEMORY;
+}
+
+
+RTDECL(int)  RTSemFastMutexDestroy(RTSEMFASTMUTEX hFastMtx)
+{
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    if (pThis == NIL_RTSEMFASTMUTEX)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    ASMAtomicWriteU32(&pThis->u32Magic, RTSEMFASTMUTEX_MAGIC_DEAD);
+    KernFreeMutexLock(&pThis->Mtx);
+    RTMemFree(pThis);
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemFastMutexRequest(RTSEMFASTMUTEX hFastMtx)
+{
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    KernRequestExclusiveMutex(&pThis->Mtx);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemFastMutexRelease(RTSEMFASTMUTEX hFastMtx)
+{
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+
+    KernReleaseExclusiveMutex(&pThis->Mtx);
+    return VINF_SUCCESS;
+}
+
diff --git a/src/VBox/Runtime/r0drv/os2/spinlock-r0drv-os2.cpp b/src/VBox/Runtime/r0drv/os2/spinlock-r0drv-os2.cpp
new file mode 100644
index 00000000..b746bd59
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/os2/spinlock-r0drv-os2.cpp
@@ -0,0 +1,155 @@
+/* $Id: spinlock-r0drv-os2.cpp $ */
+/** @file
+ * IPRT - Spinlocks, Ring-0 Driver, OS/2.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-os2-kernel.h"
+
+#include <iprt/spinlock.h>
+#include <iprt/errcore.h>
+#include <iprt/alloc.h>
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+#ifdef RT_STRICT
+# include <iprt/asm-amd64-x86.h>
+#endif
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Wrapper for the SpinLock_t type.
+ */
+typedef struct RTSPINLOCKINTERNAL
+{
+    /** Spinlock magic value (RTSPINLOCK_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** Spinlock creation flags.  */
+    uint32_t            fFlags;
+    /** The OS/2 spinlock structure. */
+    SpinLock_t          Spinlock;
+} RTSPINLOCKINTERNAL, *PRTSPINLOCKINTERNAL;
+
+
+RTDECL(int)  RTSpinlockCreate(PRTSPINLOCK pSpinlock, uint32_t fFlags, const char *pszName)
+{
+    AssertReturn(fFlags == RTSPINLOCK_FLAGS_INTERRUPT_SAFE || fFlags == RTSPINLOCK_FLAGS_INTERRUPT_UNSAFE, VERR_INVALID_PARAMETER);
+    RT_NOREF(pszName);
+
+    /*
+     * Allocate.
+     */
+    AssertCompile(sizeof(RTSPINLOCKINTERNAL) > sizeof(void *));
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (!pThis)
+        return VERR_NO_MEMORY;
+
+    /*
+     * Initialize & return.
+     */
+    pThis->u32Magic     = RTSPINLOCK_MAGIC;
+    pThis->fFlags       = fFlags;
+    KernAllocSpinLock(&pThis->Spinlock);
+    *pSpinlock = pThis;
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSpinlockDestroy(RTSPINLOCK Spinlock)
+{
+    /*
+     * Validate input.
+     */
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
+    if (!pThis)
+        return VERR_INVALID_PARAMETER;
+    AssertMsgReturn(pThis->u32Magic == RTSPINLOCK_MAGIC,
+                    ("Invalid spinlock %p magic=%#x\n", pThis, pThis->u32Magic),
+                    VERR_INVALID_PARAMETER);
+
+    /*
+     * Make the lock invalid and release the memory.
+     */
+    ASMAtomicIncU32(&pThis->u32Magic);
+    KernFreeSpinLock(&pThis->Spinlock);
+    RTMemFree(pThis);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(void) RTSpinlockAcquire(RTSPINLOCK Spinlock)
+{
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
+    AssertPtr(pThis);
+    Assert(pThis->u32Magic == RTSPINLOCK_MAGIC);
+
+    KernAcquireSpinLock(&pThis->Spinlock);
+    Assert(!ASMIntAreEnabled()); /** @todo verify that interrupts are disabled. */
+}
+
+
+RTDECL(void) RTSpinlockRelease(RTSPINLOCK Spinlock)
+{
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
+    AssertPtr(pThis);
+    Assert(pThis->u32Magic == RTSPINLOCK_MAGIC);
+
+    KernReleaseSpinLock(&pThis->Spinlock);
+}
+
diff --git a/src/VBox/Runtime/r0drv/os2/the-os2-kernel.h b/src/VBox/Runtime/r0drv/os2/the-os2-kernel.h
new file mode 100644
index 00000000..7a972a67
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/os2/the-os2-kernel.h
@@ -0,0 +1,83 @@
+/* $Id: the-os2-kernel.h $ */
+/** @file
+ * IPRT - Ring-0 Driver, The OS/2 Kernel Headers.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef IPRT_INCLUDED_SRC_r0drv_os2_the_os2_kernel_h
+#define IPRT_INCLUDED_SRC_r0drv_os2_the_os2_kernel_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <iprt/types.h>
+
+#define INCL_ERRORS
+#define INCL_DOSSEMAPHORES /* for SEM_INDEFINITE_WAIT */
+#undef RT_MAX
+#include <os2ddk/bsekee.h>
+#include <os2ddk/devhlp.h>
+#undef RT_MAX
+
+RT_C_DECLS_BEGIN
+
+extern PCDOSTABLE   g_pDosTable;
+extern PCDOSTABLE2  g_pDosTable2;
+extern PGINFOSEG    g_pGIS;
+extern RTFAR16      g_fpLIS;
+
+RTR0DECL(void *) RTR0Os2Virt2Flat(RTFAR16 fp);
+DECLASM(int) RTR0Os2DHQueryDOSVar(uint8_t iVar, uint16_t iSub, PRTFAR16 pfp);
+DECLASM(int) RTR0Os2DHVMGlobalToProcess(ULONG fFlags, PVOID pvR0, ULONG cb, PPVOID ppvR3);
+
+RT_C_DECLS_END
+
+#endif /* !IPRT_INCLUDED_SRC_r0drv_os2_the_os2_kernel_h */
diff --git a/src/VBox/Runtime/r0drv/os2/thread-r0drv-os2.cpp b/src/VBox/Runtime/r0drv/os2/thread-r0drv-os2.cpp
new file mode 100644
index 00000000..4b107be2
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/os2/thread-r0drv-os2.cpp
@@ -0,0 +1,215 @@
+/* $Id: thread-r0drv-os2.cpp $ */
+/** @file
+ * IPRT - Threads (Part 1), Ring-0 Driver, OS/2.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-os2-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/thread.h>
+
+#include <iprt/asm.h>
+#include <iprt/asm-amd64-x86.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/mp.h>
+#include "internal/thread.h"
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/** Per-cpu preemption counters. */
+static int32_t volatile g_acPreemptDisabled[256];
+
+
+
+RTDECL(RTNATIVETHREAD) RTThreadNativeSelf(void)
+{
+    PLINFOSEG pLIS = (PLINFOSEG)RTR0Os2Virt2Flat(g_fpLIS);
+    AssertMsgReturn(pLIS, ("g_fpLIS=%04x:%04x - logging too early again?\n", g_fpLIS.sel, g_fpLIS.off), NIL_RTNATIVETHREAD);
+    return pLIS->tidCurrent | (pLIS->pidCurrent << 16);
+}
+
+
+static int rtR0ThreadOs2SleepCommon(RTMSINTERVAL cMillies)
+{
+    int rc = KernBlock((ULONG)RTThreadSleep,
+                       cMillies == RT_INDEFINITE_WAIT ? SEM_INDEFINITE_WAIT : cMillies,
+                       0, NULL, NULL);
+    switch (rc)
+    {
+        case NO_ERROR:
+            return VINF_SUCCESS;
+        case ERROR_TIMEOUT:
+            return VERR_TIMEOUT;
+        case ERROR_INTERRUPT:
+            return VERR_INTERRUPTED;
+        default:
+            AssertMsgFailed(("%d\n", rc));
+            return VERR_NO_TRANSLATION;
+    }
+}
+
+
+RTDECL(int) RTThreadSleep(RTMSINTERVAL cMillies)
+{
+    return rtR0ThreadOs2SleepCommon(cMillies);
+}
+
+
+RTDECL(int) RTThreadSleepNoBlock(RTMSINTERVAL cMillies)
+{
+    return rtR0ThreadOs2SleepCommon(cMillies);
+}
+
+
+RTDECL(bool) RTThreadYield(void)
+{
+    /** @todo implement me (requires a devhelp) */
+    return false;
+}
+
+
+RTDECL(bool) RTThreadPreemptIsEnabled(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD);
+    int32_t c = g_acPreemptDisabled[ASMGetApicId()];
+    AssertMsg(c >= 0 && c < 32, ("%d\n", c));
+    return c == 0
+        && ASMIntAreEnabled();
+}
+
+
+RTDECL(bool) RTThreadPreemptIsPending(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD);
+
+    union
+    {
+        RTFAR16 fp;
+        uint8_t fResched;
+    } u;
+    int rc = RTR0Os2DHQueryDOSVar(DHGETDOSV_YIELDFLAG, 0, &u.fp);
+    AssertReturn(rc == 0, false);
+    if (u.fResched)
+        return true;
+
+    /** @todo Check if DHGETDOSV_YIELDFLAG includes TCYIELDFLAG. */
+    rc = RTR0Os2DHQueryDOSVar(DHGETDOSV_TCYIELDFLAG, 0, &u.fp);
+    AssertReturn(rc == 0, false);
+    if (u.fResched)
+        return true;
+    return false;
+}
+
+
+RTDECL(bool) RTThreadPreemptIsPendingTrusty(void)
+{
+    /* yes, RTThreadPreemptIsPending is reliable. */
+    return true;
+}
+
+
+RTDECL(bool) RTThreadPreemptIsPossible(void)
+{
+    /* no kernel preemption on OS/2. */
+    return false;
+}
+
+
+RTDECL(void) RTThreadPreemptDisable(PRTTHREADPREEMPTSTATE pState)
+{
+    AssertPtr(pState);
+    Assert(pState->u32Reserved == 0);
+
+    /* No preemption on OS/2, so do our own accounting. */
+    int32_t c = ASMAtomicIncS32(&g_acPreemptDisabled[ASMGetApicId()]);
+    AssertMsg(c > 0 && c < 32, ("%d\n", c));
+    pState->u32Reserved = c;
+    RT_ASSERT_PREEMPT_CPUID_DISABLE(pState);
+}
+
+
+RTDECL(void) RTThreadPreemptRestore(PRTTHREADPREEMPTSTATE pState)
+{
+    AssertPtr(pState);
+    AssertMsg(pState->u32Reserved > 0 && pState->u32Reserved < 32, ("%d\n", pState->u32Reserved));
+    RT_ASSERT_PREEMPT_CPUID_RESTORE(pState);
+
+    /* No preemption on OS/2, so do our own accounting. */
+    int32_t volatile *pc = &g_acPreemptDisabled[ASMGetApicId()];
+    AssertMsg(pState->u32Reserved == (uint32_t)*pc, ("uchDummy=%d *pc=%d \n", pState->u32Reserved, *pc));
+    ASMAtomicUoWriteS32(pc, pState->u32Reserved - 1);
+    pState->u32Reserved = 0;
+}
+
+
+RTDECL(bool) RTThreadIsInInterrupt(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD); NOREF(hThread);
+
+    union
+    {
+        RTFAR16 fp;
+        uint8_t cInterruptLevel;
+    } u;
+    /** @todo OS/2: verify the usage of DHGETDOSV_INTERRUPTLEV. */
+    int rc = RTR0Os2DHQueryDOSVar(DHGETDOSV_INTERRUPTLEV, 0, &u.fp);
+    AssertReturn(rc == 0, true);
+
+    return u.cInterruptLevel > 0;
+}
+
diff --git a/src/VBox/Runtime/r0drv/os2/thread2-r0drv-os2.cpp b/src/VBox/Runtime/r0drv/os2/thread2-r0drv-os2.cpp
new file mode 100644
index 00000000..dadde061
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/os2/thread2-r0drv-os2.cpp
@@ -0,0 +1,110 @@
+/* $Id: thread2-r0drv-os2.cpp $ */
+/** @file
+ * IPRT - Threads (Part 2), Ring-0 Driver, Generic Stubs.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-os2-kernel.h"
+
+#include <iprt/thread.h>
+#include <iprt/errcore.h>
+#include "internal/thread.h"
+
+
+DECLHIDDEN(int) rtThreadNativeInit(void)
+{
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(RTTHREAD) RTThreadSelf(void)
+{
+    return rtThreadGetByNative(RTThreadNativeSelf());
+}
+
+
+DECLHIDDEN(int) rtThreadNativeSetPriority(PRTTHREADINT pThread, RTTHREADTYPE enmType)
+{
+    NOREF(pThread);
+    NOREF(enmType);
+    return VERR_NOT_IMPLEMENTED;
+}
+
+
+DECLHIDDEN(int) rtThreadNativeAdopt(PRTTHREADINT pThread)
+{
+    NOREF(pThread);
+    return VERR_NOT_IMPLEMENTED;
+}
+
+DECLHIDDEN(void) rtThreadNativeWaitKludge(PRTTHREADINT pThread)
+{
+    NOREF(pThread);
+}
+
+
+DECLHIDDEN(void) rtThreadNativeDestroy(PRTTHREADINT pThread)
+{
+    NOREF(pThread);
+}
+
+
+DECLHIDDEN(int) rtThreadNativeCreate(PRTTHREADINT pThreadInt, PRTNATIVETHREAD pNativeThread)
+{
+    NOREF(pNativeThread);
+    NOREF(pThreadInt);
+    return VERR_NOT_IMPLEMENTED;
+}
+
diff --git a/src/VBox/Runtime/r0drv/os2/time-r0drv-os2.cpp b/src/VBox/Runtime/r0drv/os2/time-r0drv-os2.cpp
new file mode 100644
index 00000000..4d98071f
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/os2/time-r0drv-os2.cpp
@@ -0,0 +1,116 @@
+/* $Id: time-r0drv-os2.cpp $ */
+/** @file
+ * IPRT - Time, Ring-0 Driver, OS/2.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-os2-kernel.h"
+
+#include <iprt/time.h>
+
+
+RTDECL(uint64_t) RTTimeNanoTS(void)
+{
+    /** @remark OS/2 Ring-0: will wrap after 48 days. */
+    return g_pGIS->msecs * UINT64_C(1000000);
+}
+
+
+RTDECL(uint64_t) RTTimeMilliTS(void)
+{
+    /** @remark OS/2 Ring-0: will wrap after 48 days. */
+    return g_pGIS->msecs;
+}
+
+
+RTDECL(uint64_t) RTTimeSystemNanoTS(void)
+{
+    /** @remark OS/2 Ring-0: will wrap after 48 days. */
+    return g_pGIS->msecs * UINT64_C(1000000);
+}
+
+
+RTDECL(uint64_t) RTTimeSystemMilliTS(void)
+{
+    /** @remark OS/2 Ring-0: will wrap after 48 days. */
+    return g_pGIS->msecs;
+}
+
+
+RTDECL(PRTTIMESPEC) RTTimeNow(PRTTIMESPEC pTime)
+{
+    /*
+     * Get the seconds since the unix epoch (local time) and current hundredths.
+     */
+    GINFOSEG volatile *pGIS = (GINFOSEG volatile *)g_pGIS;
+    UCHAR uchHundredths;
+    ULONG ulSeconds;
+    do
+    {
+        uchHundredths = pGIS->hundredths;
+        ulSeconds = pGIS->time;
+    } while (   uchHundredths  == pGIS->hundredths
+             && ulSeconds      == pGIS->time);
+
+    /*
+     * Combine the two and convert to UCT (later).
+     */
+    uint64_t u64 = ulSeconds * UINT64_C(1000000000) + (uint32_t)uchHundredths * 10000000;
+    /** @todo convert from local to UCT. */
+
+    /** @remark OS/2 Ring-0: Currently returns local time instead of UCT. */
+    return RTTimeSpecSetNano(pTime, u64);
+}
+
diff --git a/src/VBox/Runtime/r0drv/os2/timer-r0drv-os2.cpp b/src/VBox/Runtime/r0drv/os2/timer-r0drv-os2.cpp
new file mode 100644
index 00000000..5cb67133
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/os2/timer-r0drv-os2.cpp
@@ -0,0 +1,409 @@
+/* $Id: timer-r0drv-os2.cpp $ */
+/** @file
+ * IPRT - Memory Allocation, Ring-0 Driver, OS/2.
+ */
+
+/*
+ * Contributed by knut st. osmundsen.
+ *
+ * Copyright (C) 2007-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ * --------------------------------------------------------------------
+ *
+ * This code is based on:
+ *
+ * Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-os2-kernel.h"
+
+#include <iprt/timer.h>
+#include <iprt/time.h>
+#include <iprt/spinlock.h>
+#include <iprt/err.h>
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/alloc.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * The internal representation of an OS/2 timer handle.
+ */
+typedef struct RTTIMER
+{
+    /** Magic.
+     * This is RTTIMER_MAGIC, but changes to something else before the timer
+     * is destroyed to indicate clearly that thread should exit. */
+    uint32_t volatile       u32Magic;
+    /** The next timer in the timer list. */
+    PRTTIMER                pNext;
+    /** Flag indicating the timer is suspended. */
+    uint8_t volatile        fSuspended;
+    /** Cleared at the start of timer processing, set when calling pfnTimer.
+     * If any timer changes occurs while doing the callback this will be used to resume the cycle. */
+    bool                    fDone;
+    /** Callback. */
+    PFNRTTIMER              pfnTimer;
+    /** User argument. */
+    void                   *pvUser;
+    /** The timer interval. 0 if one-shot. */
+    uint64_t                u64NanoInterval;
+    /** The start of the current run.
+     * This is used to calculate when the timer ought to fire the next time. */
+    uint64_t volatile       u64StartTS;
+    /** The start of the current run.
+     * This is used to calculate when the timer ought to fire the next time. */
+    uint64_t volatile       u64NextTS;
+    /** The current tick number (since u64StartTS). */
+    uint64_t volatile       iTick;
+} RTTIMER;
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/** Spinlock protecting the timers. */
+static RTSPINLOCK           g_Spinlock = NIL_RTSPINLOCK;
+/** The timer head. */
+static PRTTIMER volatile    g_pTimerHead = NULL;
+/** The number of active timers. */
+static uint32_t volatile    g_cActiveTimers = 0;
+/** The number of active timers. */
+static uint32_t volatile    g_cTimers = 0;
+/** The change number.
+ * This is used to detect list changes during the timer callback loop. */
+static uint32_t volatile    g_u32ChangeNo;
+
+
+/*********************************************************************************************************************************
+*   Internal Functions                                                                                                           *
+*********************************************************************************************************************************/
+RT_C_DECLS_BEGIN
+DECLASM(void) rtTimerOs2Tick(void);
+DECLASM(int) rtTimerOs2Arm(void);
+DECLASM(int) rtTimerOs2Dearm(void);
+RT_C_DECLS_END
+
+
+
+RTDECL(int) RTTimerCreateEx(PRTTIMER *ppTimer, uint64_t u64NanoInterval, uint32_t fFlags, PFNRTTIMER pfnTimer, void *pvUser)
+{
+    *ppTimer = NULL;
+
+    /*
+     * We don't support the fancy MP features.
+     */
+    if (fFlags & RTTIMER_FLAGS_CPU_SPECIFIC)
+        return VERR_NOT_SUPPORTED;
+
+    /*
+     * Lazy initialize the spinlock.
+     */
+    if (g_Spinlock == NIL_RTSPINLOCK)
+    {
+        RTSPINLOCK Spinlock;
+        int rc = RTSpinlockCreate(&Spinlock, RTSPINLOCK_FLAGS_INTERRUPT_SAFE, "RTTimerOS2");
+        AssertRCReturn(rc, rc);
+        //bool fRc;
+        //ASMAtomicCmpXchgSize(&g_Spinlock, Spinlock, NIL_RTSPINLOCK, fRc);
+        //if (!fRc)
+        if (!ASMAtomicCmpXchgPtr((void * volatile *)&g_Spinlock, Spinlock, NIL_RTSPINLOCK))
+            RTSpinlockDestroy(Spinlock);
+    }
+
+    /*
+     * Allocate and initialize the timer handle.
+     */
+    PRTTIMER pTimer = (PRTTIMER)RTMemAlloc(sizeof(*pTimer));
+    if (!pTimer)
+        return VERR_NO_MEMORY;
+
+    pTimer->u32Magic = RTTIMER_MAGIC;
+    pTimer->pNext = NULL;
+    pTimer->fSuspended = true;
+    pTimer->pfnTimer = pfnTimer;
+    pTimer->pvUser = pvUser;
+    pTimer->u64NanoInterval = u64NanoInterval;
+    pTimer->u64StartTS = 0;
+
+    /*
+     * Insert the timer into the list (LIFO atm).
+     */
+    RTSpinlockAcquire(g_Spinlock);
+    g_u32ChangeNo++;
+    pTimer->pNext = g_pTimerHead;
+    g_pTimerHead = pTimer;
+    g_cTimers++;
+    RTSpinlockRelease(g_Spinlock);
+
+    *ppTimer = pTimer;
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Validates the timer handle.
+ *
+ * @returns true if valid, false if invalid.
+ * @param   pTimer  The handle.
+ */
+DECLINLINE(bool) rtTimerIsValid(PRTTIMER pTimer)
+{
+    AssertReturn(VALID_PTR(pTimer), false);
+    AssertReturn(pTimer->u32Magic == RTTIMER_MAGIC, false);
+    return true;
+}
+
+
+RTDECL(int) RTTimerDestroy(PRTTIMER pTimer)
+{
+    /* It's ok to pass NULL pointer. */
+    if (pTimer == /*NIL_RTTIMER*/ NULL)
+        return VINF_SUCCESS;
+    if (!rtTimerIsValid(pTimer))
+        return VERR_INVALID_HANDLE;
+
+    /*
+     * Remove it from the list.
+     */
+    RTSpinlockAcquire(g_Spinlock);
+    g_u32ChangeNo++;
+    if (g_pTimerHead == pTimer)
+        g_pTimerHead = pTimer->pNext;
+    else
+    {
+        PRTTIMER pPrev = g_pTimerHead;
+        while (pPrev->pNext != pTimer)
+        {
+            pPrev = pPrev->pNext;
+            if (RT_UNLIKELY(!pPrev))
+            {
+                RTSpinlockRelease(g_Spinlock);
+                return VERR_INVALID_HANDLE;
+            }
+        }
+        pPrev->pNext = pTimer->pNext;
+    }
+    Assert(g_cTimers > 0);
+    g_cTimers--;
+    if (!pTimer->fSuspended)
+    {
+        Assert(g_cActiveTimers > 0);
+        g_cActiveTimers--;
+        if (!g_cActiveTimers)
+            rtTimerOs2Dearm();
+    }
+    RTSpinlockRelease(g_Spinlock);
+
+    /*
+     * Free the associated resources.
+     */
+    pTimer->u32Magic++;
+    RTMemFree(pTimer);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTTimerStart(PRTTIMER pTimer, uint64_t u64First)
+{
+    if (!rtTimerIsValid(pTimer))
+        return VERR_INVALID_HANDLE;
+    if (!pTimer->fSuspended)
+        return VERR_TIMER_ACTIVE;
+
+    /*
+     * Calc when it should start firing and give the thread a kick so it get going.
+     */
+    u64First += RTTimeNanoTS();
+
+    RTSpinlockAcquire(g_Spinlock);
+    g_u32ChangeNo++;
+    if (!g_cActiveTimers)
+    {
+        int rc = rtTimerOs2Arm();
+        if (RT_FAILURE(rc))
+        {
+            RTSpinlockRelease(g_Spinlock);
+            return rc;
+        }
+    }
+    g_cActiveTimers++;
+    pTimer->fSuspended = false;
+    pTimer->fDone = true;               /* next tick, not current! */
+    pTimer->iTick = 0;
+    pTimer->u64StartTS = u64First;
+    pTimer->u64NextTS = u64First;
+    RTSpinlockRelease(g_Spinlock);
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTTimerStop(PRTTIMER pTimer)
+{
+    if (!rtTimerIsValid(pTimer))
+        return VERR_INVALID_HANDLE;
+    if (pTimer->fSuspended)
+        return VERR_TIMER_SUSPENDED;
+
+    /*
+     * Suspend the timer.
+     */
+    RTSpinlockAcquire(g_Spinlock);
+    g_u32ChangeNo++;
+    pTimer->fSuspended = true;
+    Assert(g_cActiveTimers > 0);
+    g_cActiveTimers--;
+    if (!g_cActiveTimers)
+        rtTimerOs2Dearm();
+    RTSpinlockRelease(g_Spinlock);
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTTimerChangeInterval(PRTTIMER pTimer, uint64_t u64NanoInterval)
+{
+    if (!rtTimerIsValid(pTimer))
+        return VERR_INVALID_HANDLE;
+    RT_NOREF(u64NanoInterval);
+    return VERR_NOT_SUPPORTED;
+}
+
+
+DECLASM(void) rtTimerOs2Tick(void)
+{
+    /*
+     * Query the current time and then take the lock.
+     */
+    const uint64_t u64NanoTS = RTTimeNanoTS();
+
+    RTSpinlockAcquire(g_Spinlock);
+
+    /*
+     * Clear the fDone flag.
+     */
+    PRTTIMER pTimer;
+    for (pTimer = g_pTimerHead; pTimer; pTimer = pTimer->pNext)
+        pTimer->fDone = false;
+
+    /*
+     * Walk the timer list and do the callbacks for any active timer.
+     */
+    uint32_t u32CurChangeNo = g_u32ChangeNo;
+    pTimer = g_pTimerHead;
+    while (pTimer)
+    {
+        PRTTIMER pNext = pTimer->pNext;
+        if (    !pTimer->fSuspended
+            &&  !pTimer->fDone
+            &&  pTimer->u64NextTS <= u64NanoTS)
+        {
+            pTimer->fDone = true;
+            pTimer->iTick++;
+
+            /* calculate the next timeout */
+            if (!pTimer->u64NanoInterval)
+                pTimer->fSuspended = true;
+            else
+            {
+                pTimer->u64NextTS = pTimer->u64StartTS + pTimer->iTick * pTimer->u64NanoInterval;
+                if (pTimer->u64NextTS < u64NanoTS)
+                    pTimer->u64NextTS = u64NanoTS + RTTimerGetSystemGranularity() / 2;
+            }
+
+            /* do the callout */
+            PFNRTTIMER  pfnTimer = pTimer->pfnTimer;
+            void       *pvUser   = pTimer->pvUser;
+            RTSpinlockRelease(g_Spinlock);
+            pfnTimer(pTimer, pvUser, pTimer->iTick);
+
+            RTSpinlockAcquire(g_Spinlock);
+
+            /* check if anything changed. */
+            if (u32CurChangeNo != g_u32ChangeNo)
+            {
+                u32CurChangeNo = g_u32ChangeNo;
+                pNext = g_pTimerHead;
+            }
+        }
+
+        /* next */
+        pTimer = pNext;
+    }
+
+    RTSpinlockRelease(g_Spinlock);
+}
+
+
+RTDECL(uint32_t) RTTimerGetSystemGranularity(void)
+{
+    return 32000000; /* 32ms */
+}
+
+
+RTDECL(int) RTTimerRequestSystemGranularity(uint32_t u32Request, uint32_t *pu32Granted)
+{
+    RT_NOREF(u32Request, pu32Granted);
+    return VERR_NOT_SUPPORTED;
+}
+
+
+RTDECL(int) RTTimerReleaseSystemGranularity(uint32_t u32Granted)
+{
+    RT_NOREF(u32Granted);
+    return VERR_NOT_SUPPORTED;
+}
+
+
+RTDECL(bool) RTTimerCanDoHighResolution(void)
+{
+    return false;
+}
+
diff --git a/src/VBox/Runtime/r0drv/os2/timerA-r0drv-os2.asm b/src/VBox/Runtime/r0drv/os2/timerA-r0drv-os2.asm
new file mode 100644
index 00000000..299a741f
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/os2/timerA-r0drv-os2.asm
@@ -0,0 +1,242 @@
+; $Id: timerA-r0drv-os2.asm $
+;; @file
+; IPRT - DevHelp_VMGlobalToProcess, Ring-0 Driver, OS/2.
+;
+
+;
+; Contributed by knut st. osmundsen.
+;
+; Copyright (C) 2007-2020 Oracle Corporation
+;
+; This file is part of VirtualBox Open Source Edition (OSE), as
+; available from http://www.virtualbox.org. This file is free software;
+; you can redistribute it and/or modify it under the terms of the GNU
+; General Public License (GPL) as published by the Free Software
+; Foundation, in version 2 as it comes in the "COPYING" file of the
+; VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+; hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+;
+; The contents of this file may alternatively be used under the terms
+; of the Common Development and Distribution License Version 1.0
+; (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+; VirtualBox OSE distribution, in which case the provisions of the
+; CDDL are applicable instead of those of the GPL.
+;
+; You may elect to license modified versions of this file under the
+; terms and conditions of either the GPL or the CDDL or both.
+; --------------------------------------------------------------------
+;
+; This code is based on:
+;
+; Copyright (c) 2007 knut st. osmundsen <bird-src-spam@anduin.net>
+;
+; Permission is hereby granted, free of charge, to any person
+; obtaining a copy of this software and associated documentation
+; files (the "Software"), to deal in the Software without
+; restriction, including without limitation the rights to use,
+; copy, modify, merge, publish, distribute, sublicense, and/or sell
+; copies of the Software, and to permit persons to whom the
+; Software is furnished to do so, subject to the following
+; conditions:
+;
+; The above copyright notice and this permission notice shall be
+; included in all copies or substantial portions of the Software.
+;
+; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+; EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+; OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+; NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+; HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+; WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+; FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+; OTHER DEALINGS IN THE SOFTWARE.
+;
+
+
+;*******************************************************************************
+;* Header Files                                                                *
+;*******************************************************************************
+%define RT_INCL_16BIT_SEGMENTS
+%include "iprt/asmdefs.mac"
+%include "iprt/err.mac"
+
+
+;*******************************************************************************
+;* External Symbols                                                            *
+;*******************************************************************************
+extern KernThunkStackTo32
+extern KernThunkStackTo16
+extern NAME(rtTimerOs2Tick)
+extern NAME(RTErrConvertFromOS2)
+BEGINDATA16
+extern NAME(g_fpfnDevHlp)
+
+
+;*******************************************************************************
+;* Defined Constants And Macros                                                *
+;*******************************************************************************
+%define DevHlp_SetTimer     01dh
+%define DevHlp_ResetTimer   01eh
+
+
+BEGINCODE
+
+;;
+; Arms the our OS/2 timer.
+;
+; @returns IPRT status code.
+;
+BEGINPROC_EXPORTED rtTimerOs2Arm
+    call    KernThunkStackTo16
+    push    ebp
+    mov     ebp, esp
+
+    ; jump to the 16-bit code.
+    ;jmp far dword NAME(rtTimerOs2Arm_16) wrt CODE16
+    db      066h
+    db      0eah
+    dw      NAME(rtTimerOs2Arm_16) wrt CODE16
+    dw      CODE16
+BEGINCODE16
+GLOBALNAME rtTimerOs2Arm_16
+
+    ; setup and do the call
+    push    ds
+    push    es
+    mov     dx, DATA16
+    mov     ds, dx
+    mov     es, dx
+
+    mov     ax, NAME(rtTimerOs2TickAsm) wrt CODE16
+    mov     dl, DevHlp_SetTimer
+    call far [NAME(g_fpfnDevHlp)]
+
+    pop     es
+    pop     ds
+
+    ;jmp far dword NAME(rtTimerOs2Arm_32) wrt FLAT
+    db      066h
+    db      0eah
+    dd      NAME(rtTimerOs2Arm_32) ;wrt FLAT
+    dw      TEXT32 wrt FLAT
+BEGINCODE
+GLOBALNAME rtTimerOs2Arm_32
+    jc      .error
+    xor     eax, eax
+.done:
+
+    leave
+    push    eax
+    call    KernThunkStackTo32
+    pop     eax
+    ret
+
+    ; convert the error code.
+.error:
+    and     eax, 0ffffh
+    call    NAME(RTErrConvertFromOS2)
+    jmp     .done
+ENDPROC rtTimerOs2Arm
+
+
+;;
+; Dearms the our OS/2 timer.
+;
+; @returns IPRT status code.
+;
+BEGINPROC_EXPORTED rtTimerOs2Dearm
+    call    KernThunkStackTo16
+    push    ebp
+    mov     ebp, esp
+
+    ; jump to the 16-bit code.
+    ;jmp far dword NAME(rtTimerOs2Dearm_16) wrt CODE16
+    db      066h
+    db      0eah
+    dw      NAME(rtTimerOs2Dearm_16) wrt CODE16
+    dw      CODE16
+BEGINCODE16
+GLOBALNAME rtTimerOs2Dearm_16
+
+    ; setup and do the call
+    push    ds
+    push    es
+    mov     dx, DATA16
+    mov     ds, dx
+    mov     es, dx
+
+    mov     ax, NAME(rtTimerOs2TickAsm) wrt CODE16
+    mov     dl, DevHlp_ResetTimer
+    call far [NAME(g_fpfnDevHlp)]
+
+    pop     es
+    pop     ds
+
+    ;jmp far dword NAME(rtTimerOs2Dearm_32) wrt FLAT
+    db      066h
+    db      0eah
+    dd      NAME(rtTimerOs2Dearm_32) ;wrt FLAT
+    dw      TEXT32 wrt FLAT
+BEGINCODE
+GLOBALNAME rtTimerOs2Dearm_32
+    jc      .error
+    xor     eax, eax
+.done:
+
+    ; epilogue
+    leave
+    push    eax
+    call    KernThunkStackTo32
+    pop     eax
+    ret
+
+    ; convert the error code.
+.error:
+    and     eax, 0ffffh
+    call    NAME(RTErrConvertFromOS2)
+    jmp     .done
+ENDPROC rtTimerOs2Dearm
+
+
+BEGINCODE16
+
+;;
+; OS/2 timer tick callback.
+;
+BEGINPROC rtTimerOs2TickAsm
+    push    ds
+    push    es
+    push    ecx
+    push    edx
+    push    eax
+
+    mov     ax, DATA32 wrt FLAT
+    mov     ds, ax
+    mov     es, ax
+
+    ;jmp far dword NAME(rtTimerOs2TickAsm_32) wrt FLAT
+    db      066h
+    db      0eah
+    dd      NAME(rtTimerOs2TickAsm_32) ;wrt FLAT
+    dw      TEXT32 wrt FLAT
+BEGINCODE
+GLOBALNAME rtTimerOs2TickAsm_32
+    call    KernThunkStackTo32
+    call    NAME(rtTimerOs2Tick)
+    call    KernThunkStackTo16
+
+    ;jmp far dword NAME(rtTimerOs2TickAsm_16) wrt CODE16
+    db      066h
+    db      0eah
+    dw      NAME(rtTimerOs2TickAsm_16) wrt CODE16
+    dw      CODE16
+BEGINCODE16
+GLOBALNAME rtTimerOs2TickAsm_16
+
+    pop     eax
+    pop     edx
+    pop     ecx
+    pop     es
+    pop     ds
+    retf
+ENDPROC rtTimerOs2TickAsm
diff --git a/src/VBox/Runtime/r0drv/power-r0drv.h b/src/VBox/Runtime/r0drv/power-r0drv.h
new file mode 100644
index 00000000..59d7cfe3
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/power-r0drv.h
@@ -0,0 +1,44 @@
+/* $Id: power-r0drv.h $ */
+/** @file
+ * IPRT - Power Management, Ring-0 Driver, Internal Header.
+ */
+
+/*
+ * Copyright (C) 2008-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+#ifndef IPRT_INCLUDED_SRC_r0drv_power_r0drv_h
+#define IPRT_INCLUDED_SRC_r0drv_power_r0drv_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <iprt/power.h>
+
+RT_C_DECLS_BEGIN
+
+/* Called from initterm-r0drv.cpp: */
+DECLHIDDEN(int)  rtR0PowerNotificationInit(void);
+DECLHIDDEN(void) rtR0PowerNotificationTerm(void);
+
+RT_C_DECLS_END
+
+#endif /* !IPRT_INCLUDED_SRC_r0drv_power_r0drv_h */
+
diff --git a/src/VBox/Runtime/r0drv/powernotification-r0drv.c b/src/VBox/Runtime/r0drv/powernotification-r0drv.c
new file mode 100644
index 00000000..c92e9133
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/powernotification-r0drv.c
@@ -0,0 +1,318 @@
+/* $Id: powernotification-r0drv.c $ */
+/** @file
+ * IPRT - Power Management, Ring-0 Driver, Event Notifications.
+ */
+
+/*
+ * Copyright (C) 2008-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/power.h>
+#include "internal/iprt.h"
+
+#include <iprt/asm.h>
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/mem.h>
+#include <iprt/spinlock.h>
+#include <iprt/string.h>
+#include <iprt/thread.h>
+#include "r0drv/mp-r0drv.h"
+#include "r0drv/power-r0drv.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Notification registration record tracking
+ * RTPowerRegisterNotification() calls.
+ */
+typedef struct RTPOWERNOTIFYREG
+{
+    /** Pointer to the next record. */
+    struct RTPOWERNOTIFYREG * volatile pNext;
+    /** The callback. */
+    PFNRTPOWERNOTIFICATION pfnCallback;
+    /** The user argument. */
+    void *pvUser;
+    /** Bit mask indicating whether we've done this callback or not. */
+    uint8_t bmDone[sizeof(void *)];
+} RTPOWERNOTIFYREG;
+/** Pointer to a registration record. */
+typedef RTPOWERNOTIFYREG *PRTPOWERNOTIFYREG;
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/** The spinlock protecting the list. */
+static RTSPINLOCK volatile g_hRTPowerNotifySpinLock = NIL_RTSPINLOCK;
+/** List of callbacks, in registration order. */
+static PRTPOWERNOTIFYREG volatile g_pRTPowerCallbackHead = NULL;
+/** The current done bit. */
+static uint32_t volatile g_iRTPowerDoneBit;
+/** The list generation.
+ * This is increased whenever the list has been modified. The callback routine
+ * make use of this to avoid having restart at the list head after each callback. */
+static uint32_t volatile g_iRTPowerGeneration;
+
+
+
+
+RTDECL(int) RTPowerSignalEvent(RTPOWEREVENT enmEvent)
+{
+    PRTPOWERNOTIFYREG pCur;
+    RTSPINLOCK        hSpinlock;
+
+    /*
+     * This is a little bit tricky as we cannot be holding the spinlock
+     * while calling the callback. This means that the list might change
+     * while we're walking it, and that multiple events might be running
+     * concurrently (depending on the OS).
+     *
+     * So, the first measure is to employ a 32-bitmask for each
+     * record where we'll use a bit that rotates for each call to
+     * this function to indicate which records that has been
+     * processed. This will take care of both changes to the list
+     * and a reasonable amount of concurrent events.
+     *
+     * In order to avoid having to restart the list walks for every
+     * callback we make, we'll make use a list generation number that is
+     * incremented everytime the list is changed. So, if it remains
+     * unchanged over a callback we can safely continue the iteration.
+     */
+    uint32_t iDone = ASMAtomicIncU32(&g_iRTPowerDoneBit);
+    iDone %= RT_SIZEOFMEMB(RTPOWERNOTIFYREG, bmDone) * 8;
+
+    hSpinlock = g_hRTPowerNotifySpinLock;
+    if (hSpinlock == NIL_RTSPINLOCK)
+        return VERR_ACCESS_DENIED;
+    RTSpinlockAcquire(hSpinlock);
+
+    /* Clear the bit. */
+    for (pCur = g_pRTPowerCallbackHead; pCur; pCur = pCur->pNext)
+        ASMAtomicBitClear(&pCur->bmDone[0], iDone);
+
+    /* Iterate the records and perform the callbacks. */
+    do
+    {
+        uint32_t const iGeneration = ASMAtomicUoReadU32(&g_iRTPowerGeneration);
+
+        pCur = g_pRTPowerCallbackHead;
+        while (pCur)
+        {
+            if (!ASMAtomicBitTestAndSet(&pCur->bmDone[0], iDone))
+            {
+                PFNRTPOWERNOTIFICATION pfnCallback = pCur->pfnCallback;
+                void *pvUser = pCur->pvUser;
+                pCur = pCur->pNext;
+                RTSpinlockRelease(g_hRTPowerNotifySpinLock);
+
+                pfnCallback(enmEvent, pvUser);
+
+                /* carefully require the lock here, see RTR0MpNotificationTerm(). */
+                hSpinlock = g_hRTPowerNotifySpinLock;
+                if (hSpinlock == NIL_RTSPINLOCK)
+                    return VERR_ACCESS_DENIED;
+                RTSpinlockAcquire(hSpinlock);
+                if (ASMAtomicUoReadU32(&g_iRTPowerGeneration) != iGeneration)
+                    break;
+            }
+            else
+                pCur = pCur->pNext;
+        }
+    } while (pCur);
+
+    RTSpinlockRelease(hSpinlock);
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTPowerSignalEvent);
+
+
+RTDECL(int) RTPowerNotificationRegister(PFNRTPOWERNOTIFICATION pfnCallback, void *pvUser)
+{
+    PRTPOWERNOTIFYREG   pCur;
+    PRTPOWERNOTIFYREG   pNew;
+
+    /*
+     * Validation.
+     */
+    AssertPtrReturn(pfnCallback, VERR_INVALID_POINTER);
+    AssertReturn(g_hRTPowerNotifySpinLock != NIL_RTSPINLOCK, VERR_WRONG_ORDER);
+    RT_ASSERT_PREEMPTIBLE();
+
+    RTSpinlockAcquire(g_hRTPowerNotifySpinLock);
+    for (pCur = g_pRTPowerCallbackHead; pCur; pCur = pCur->pNext)
+        if (    pCur->pvUser == pvUser
+            &&  pCur->pfnCallback == pfnCallback)
+            break;
+    RTSpinlockRelease(g_hRTPowerNotifySpinLock);
+    AssertMsgReturn(!pCur, ("pCur=%p pfnCallback=%p pvUser=%p\n", pCur, pfnCallback, pvUser), VERR_ALREADY_EXISTS);
+
+    /*
+     * Allocate a new record and attempt to insert it.
+     */
+    pNew = (PRTPOWERNOTIFYREG)RTMemAlloc(sizeof(*pNew));
+    if (!pNew)
+        return VERR_NO_MEMORY;
+
+    pNew->pNext = NULL;
+    pNew->pfnCallback = pfnCallback;
+    pNew->pvUser = pvUser;
+    memset(&pNew->bmDone[0], 0xff, sizeof(pNew->bmDone));
+
+    RTSpinlockAcquire(g_hRTPowerNotifySpinLock);
+
+    pCur = g_pRTPowerCallbackHead;
+    if (!pCur)
+        g_pRTPowerCallbackHead = pNew;
+    else
+    {
+        for (pCur = g_pRTPowerCallbackHead; ; pCur = pCur->pNext)
+            if (    pCur->pvUser == pvUser
+                &&  pCur->pfnCallback == pfnCallback)
+                break;
+            else if (!pCur->pNext)
+            {
+                pCur->pNext = pNew;
+                pCur = NULL;
+                break;
+            }
+    }
+
+    ASMAtomicIncU32(&g_iRTPowerGeneration);
+
+    RTSpinlockRelease(g_hRTPowerNotifySpinLock);
+
+    /* duplicate? */
+    if (pCur)
+    {
+        RTMemFree(pCur);
+        AssertMsgFailedReturn(("pCur=%p pfnCallback=%p pvUser=%p\n", pCur, pfnCallback, pvUser), VERR_ALREADY_EXISTS);
+    }
+
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTPowerNotificationRegister);
+
+
+RTDECL(int) RTPowerNotificationDeregister(PFNRTPOWERNOTIFICATION pfnCallback, void *pvUser)
+{
+    PRTPOWERNOTIFYREG   pPrev;
+    PRTPOWERNOTIFYREG   pCur;
+
+    /*
+     * Validation.
+     */
+    AssertPtrReturn(pfnCallback, VERR_INVALID_POINTER);
+    AssertReturn(g_hRTPowerNotifySpinLock != NIL_RTSPINLOCK, VERR_WRONG_ORDER);
+    RT_ASSERT_INTS_ON();
+
+    /*
+     * Find and unlink the record from the list.
+     */
+    RTSpinlockAcquire(g_hRTPowerNotifySpinLock);
+    pPrev = NULL;
+    for (pCur = g_pRTPowerCallbackHead; pCur; pCur = pCur->pNext)
+    {
+        if (    pCur->pvUser == pvUser
+            &&  pCur->pfnCallback == pfnCallback)
+            break;
+        pPrev = pCur;
+    }
+    if (pCur)
+    {
+        if (pPrev)
+            pPrev->pNext = pCur->pNext;
+        else
+            g_pRTPowerCallbackHead = pCur->pNext;
+        ASMAtomicIncU32(&g_iRTPowerGeneration);
+    }
+    RTSpinlockRelease(g_hRTPowerNotifySpinLock);
+
+    if (!pCur)
+        return VERR_NOT_FOUND;
+
+    /*
+     * Invalidate and free the record.
+     */
+    pCur->pNext = NULL;
+    pCur->pfnCallback = NULL;
+    RTMemFree(pCur);
+
+    return VINF_SUCCESS;
+}
+RT_EXPORT_SYMBOL(RTPowerNotificationDeregister);
+
+
+DECLHIDDEN(int) rtR0PowerNotificationInit(void)
+{
+    int rc = RTSpinlockCreate((PRTSPINLOCK)&g_hRTPowerNotifySpinLock, RTSPINLOCK_FLAGS_INTERRUPT_SAFE, "RTR0Power");
+    if (RT_SUCCESS(rc))
+    {
+        /** @todo OS specific init here */
+        return rc;
+#if 0
+        RTSpinlockDestroy(g_hRTPowerNotifySpinLock);
+        g_hRTPowerNotifySpinLock = NIL_RTSPINLOCK;
+#endif
+    }
+    return rc;
+}
+
+
+DECLHIDDEN(void) rtR0PowerNotificationTerm(void)
+{
+    PRTPOWERNOTIFYREG   pHead;
+    RTSPINLOCK          hSpinlock = g_hRTPowerNotifySpinLock;
+    AssertReturnVoid(hSpinlock != NIL_RTSPINLOCK);
+
+    /** @todo OS specific term here */
+
+    /* pick up the list and the spinlock. */
+    RTSpinlockAcquire(hSpinlock);
+    ASMAtomicWriteHandle(&g_hRTPowerNotifySpinLock, NIL_RTSPINLOCK);
+    pHead = g_pRTPowerCallbackHead;
+    g_pRTPowerCallbackHead = NULL;
+    ASMAtomicIncU32(&g_iRTPowerGeneration);
+    RTSpinlockRelease(hSpinlock);
+
+    /* free the list. */
+    while (pHead)
+    {
+        PRTPOWERNOTIFYREG pFree = pHead;
+        pHead = pHead->pNext;
+
+        pFree->pNext = NULL;
+        pFree->pfnCallback = NULL;
+        RTMemFree(pFree);
+    }
+
+    RTSpinlockDestroy(hSpinlock);
+}
+
diff --git a/src/VBox/Runtime/r0drv/solaris/Makefile.kup b/src/VBox/Runtime/r0drv/solaris/Makefile.kup
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/Makefile.kup
diff --git a/src/VBox/Runtime/r0drv/solaris/RTLogWriteDebugger-r0drv-solaris.c b/src/VBox/Runtime/r0drv/solaris/RTLogWriteDebugger-r0drv-solaris.c
new file mode 100644
index 00000000..46aa8aed
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/RTLogWriteDebugger-r0drv-solaris.c
@@ -0,0 +1,66 @@
+/* $Id: RTLogWriteDebugger-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Log To Debugger, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-solaris-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/log.h>
+
+#include <iprt/asm.h>
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/assert.h>
+#include <iprt/thread.h>
+
+
+
+RTDECL(void) RTLogWriteDebugger(const char *pch, size_t cb)
+{
+    if (pch[cb] != '\0')
+        AssertBreakpoint();
+
+    /* cmn_err() acquires adaptive mutexes. Not preemption safe, see @bugref{6657}. */
+    if (!RTThreadPreemptIsEnabled(NIL_RTTHREAD))
+        return;
+
+    if (    !g_frtSolSplSetsEIF
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+        ||  ASMIntAreEnabled()
+#else
+/* PORTME: Check if interrupts are enabled, if applicable. */
+#endif
+        )
+    {
+        cmn_err(CE_CONT, pch);
+    }
+
+    return;
+}
+
diff --git a/src/VBox/Runtime/r0drv/solaris/RTMpPokeCpu-r0drv-solaris.c b/src/VBox/Runtime/r0drv/solaris/RTMpPokeCpu-r0drv-solaris.c
new file mode 100644
index 00000000..8c16b1f6
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/RTMpPokeCpu-r0drv-solaris.c
@@ -0,0 +1,50 @@
+/* $Id: RTMpPokeCpu-r0drv-solaris.c $ */
+/** @file
+ * IPRT - RTMpPokeCpu, Solaris Implementation.
+ */
+
+/*
+ * Copyright (C) 2009-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-solaris-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/mp.h>
+
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+
+
+
+RTDECL(int) RTMpPokeCpu(RTCPUID idCpu)
+{
+    RT_ASSERT_INTS_ON();
+    if (idCpu < ncpus)
+        poke_cpu(idCpu);
+    return VINF_SUCCESS;
+}
+
diff --git a/src/VBox/Runtime/r0drv/solaris/alloc-r0drv-solaris.c b/src/VBox/Runtime/r0drv/solaris/alloc-r0drv-solaris.c
new file mode 100644
index 00000000..0cfb60c8
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/alloc-r0drv-solaris.c
@@ -0,0 +1,206 @@
+/* $Id: alloc-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Memory Allocation, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-solaris-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/mem.h>
+
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+#include <iprt/log.h>
+#include <iprt/param.h>
+#include <iprt/thread.h>
+#include "r0drv/alloc-r0drv.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+static ddi_dma_attr_t s_rtR0SolDmaAttr =
+{
+    DMA_ATTR_V0,                /* Version Number */
+    (uint64_t)0,                /* Lower limit */
+    (uint64_t)0,                /* High limit */
+    (uint64_t)0xffffffff,       /* Counter limit */
+    (uint64_t)PAGESIZE,         /* Alignment */
+    (uint64_t)PAGESIZE,         /* Burst size */
+    (uint64_t)PAGESIZE,         /* Effective DMA size */
+    (uint64_t)0xffffffff,       /* Max DMA xfer size */
+    (uint64_t)0xffffffff,       /* Segment boundary */
+    1,                          /* Scatter-gather list length (1 for contiguous) */
+    1,                          /* Device granularity */
+    0                           /* Bus-specific flags */
+};
+
+extern void *contig_alloc(size_t cb, ddi_dma_attr_t *pDmaAttr, size_t uAlign, int fCanSleep);
+
+
+/**
+ * OS specific allocation function.
+ */
+DECLHIDDEN(int) rtR0MemAllocEx(size_t cb, uint32_t fFlags, PRTMEMHDR *ppHdr)
+{
+    size_t      cbAllocated = cb;
+    PRTMEMHDR   pHdr;
+
+#ifdef RT_ARCH_AMD64
+    if (fFlags & RTMEMHDR_FLAG_EXEC)
+    {
+        AssertReturn(!(fFlags & RTMEMHDR_FLAG_ANY_CTX), VERR_NOT_SUPPORTED);
+        cbAllocated = RT_ALIGN_Z(cb + sizeof(*pHdr), PAGE_SIZE) - sizeof(*pHdr);
+        pHdr = (PRTMEMHDR)segkmem_alloc(heaptext_arena, cbAllocated + sizeof(*pHdr), KM_SLEEP);
+    }
+    else
+#endif
+    {
+        unsigned fKmFlags = fFlags & RTMEMHDR_FLAG_ANY_CTX_ALLOC ? KM_NOSLEEP : KM_SLEEP;
+        if (fFlags & RTMEMHDR_FLAG_ZEROED)
+            pHdr = (PRTMEMHDR)kmem_zalloc(cb + sizeof(*pHdr), fKmFlags);
+        else
+            pHdr = (PRTMEMHDR)kmem_alloc(cb + sizeof(*pHdr), fKmFlags);
+    }
+    if (RT_UNLIKELY(!pHdr))
+    {
+        LogRel(("rtMemAllocEx(%u, %#x) failed\n", (unsigned)cb + sizeof(*pHdr), fFlags));
+        return VERR_NO_MEMORY;
+    }
+
+    pHdr->u32Magic  = RTMEMHDR_MAGIC;
+    pHdr->fFlags    = fFlags;
+    pHdr->cb        = cbAllocated;
+    pHdr->cbReq     = cb;
+
+    *ppHdr = pHdr;
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * OS specific free function.
+ */
+DECLHIDDEN(void) rtR0MemFree(PRTMEMHDR pHdr)
+{
+    pHdr->u32Magic += 1;
+#ifdef RT_ARCH_AMD64
+    if (pHdr->fFlags & RTMEMHDR_FLAG_EXEC)
+        segkmem_free(heaptext_arena, pHdr, pHdr->cb + sizeof(*pHdr));
+    else
+#endif
+        kmem_free(pHdr, pHdr->cb + sizeof(*pHdr));
+}
+
+
+/**
+ * Allocates physical memory which satisfy the given constraints.
+ *
+ * @param   uPhysHi        The upper physical address limit (inclusive).
+ * @param   puPhys         Where to store the physical address of the allocated
+ *                         memory. Optional, can be NULL.
+ * @param   cb             Size of allocation.
+ * @param   uAlignment     Alignment.
+ * @param   fContig        Whether the memory must be physically contiguous or
+ *                         not.
+ *
+ * @returns Virtual address of allocated memory block or NULL if allocation
+ *        failed.
+ */
+DECLHIDDEN(void *) rtR0SolMemAlloc(uint64_t uPhysHi, uint64_t *puPhys, size_t cb, uint64_t uAlignment, bool fContig)
+{
+    if ((cb & PAGEOFFSET) != 0)
+        return NULL;
+
+    size_t cPages = (cb + PAGESIZE - 1) >> PAGESHIFT;
+    if (!cPages)
+        return NULL;
+
+    ddi_dma_attr_t DmaAttr = s_rtR0SolDmaAttr;
+    DmaAttr.dma_attr_addr_hi    = uPhysHi;
+    DmaAttr.dma_attr_align      = uAlignment;
+    if (!fContig)
+        DmaAttr.dma_attr_sgllen = cPages > INT_MAX ? INT_MAX - 1 : cPages;
+    else
+        AssertRelease(DmaAttr.dma_attr_sgllen == 1);
+
+    void *pvMem = contig_alloc(cb, &DmaAttr, PAGESIZE, 1 /* can sleep */);
+    if (!pvMem)
+    {
+        LogRel(("rtR0SolMemAlloc failed. cb=%u Align=%u fContig=%d\n", (unsigned)cb, (unsigned)uAlignment, fContig));
+        return NULL;
+    }
+
+    pfn_t PageFrameNum = hat_getpfnum(kas.a_hat, (caddr_t)pvMem);
+    AssertRelease(PageFrameNum != PFN_INVALID);
+    if (puPhys)
+        *puPhys = (uint64_t)PageFrameNum << PAGESHIFT;
+
+    return pvMem;
+}
+
+
+/**
+ * Frees memory allocated using rtR0SolMemAlloc().
+ *
+ * @param   pv         The memory to free.
+ * @param   cb         Size of the memory block
+ */
+DECLHIDDEN(void) rtR0SolMemFree(void *pv, size_t cb)
+{
+    if (RT_LIKELY(pv))
+        g_pfnrtR0Sol_contig_free(pv, cb);
+}
+
+
+RTR0DECL(void *) RTMemContAlloc(PRTCCPHYS pPhys, size_t cb)
+{
+    AssertPtrReturn(pPhys, NULL);
+    AssertReturn(cb > 0, NULL);
+    RT_ASSERT_PREEMPTIBLE();
+
+    /* Allocate physically contiguous (< 4GB) page-aligned memory. */
+    uint64_t uPhys;
+    void *pvMem = rtR0SolMemAlloc((uint64_t)_4G - 1, &uPhys, cb, PAGESIZE, true /* fContig */);
+    if (RT_UNLIKELY(!pvMem))
+    {
+        LogRel(("RTMemContAlloc failed to allocate %u bytes\n", cb));
+        return NULL;
+    }
+
+    Assert(uPhys < _4G);
+    *pPhys = uPhys;
+    return pvMem;
+}
+
+
+RTR0DECL(void) RTMemContFree(void *pv, size_t cb)
+{
+    RT_ASSERT_PREEMPTIBLE();
+    rtR0SolMemFree(pv, cb);
+}
+
diff --git a/src/VBox/Runtime/r0drv/solaris/assert-r0drv-solaris.c b/src/VBox/Runtime/r0drv/solaris/assert-r0drv-solaris.c
new file mode 100644
index 00000000..0bab01c2
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/assert-r0drv-solaris.c
@@ -0,0 +1,77 @@
+/* $Id: assert-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Assertion Workers, Ring-0 Drivers, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-solaris-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/assert.h>
+
+#include <iprt/asm.h>
+#include <iprt/log.h>
+#include <iprt/stdarg.h>
+#include <iprt/string.h>
+
+#include "internal/assert.h"
+
+
+DECLHIDDEN(void) rtR0AssertNativeMsg1(const char *pszExpr, unsigned uLine, const char *pszFile, const char *pszFunction)
+{
+    uprintf("\r\n!!Assertion Failed!!\r\n"
+            "Expression: %s\r\n"
+            "Location  : %s(%d) %s\r\n",
+            pszExpr, pszFile, uLine, pszFunction);
+}
+
+
+DECLHIDDEN(void) rtR0AssertNativeMsg2V(bool fInitial, const char *pszFormat, va_list va)
+{
+    char szMsg[256];
+
+    RTStrPrintfV(szMsg, sizeof(szMsg) - 1, pszFormat, va);
+    szMsg[sizeof(szMsg) - 1] = '\0';
+    uprintf("%s", szMsg);
+
+    NOREF(fInitial);
+}
+
+
+RTR0DECL(void) RTR0AssertPanicSystem(void)
+{
+    const char *psz    = &g_szRTAssertMsg2[0];
+    const char *pszEnd = &g_szRTAssertMsg2[sizeof(g_szRTAssertMsg2)];
+    while (psz < pszEnd && (*psz == ' ' || *psz == '\t' || *psz == '\n' || *psz == '\r'))
+        psz++;
+
+    if (psz < pszEnd && *psz)
+        assfail(psz, g_pszRTAssertFile, g_u32RTAssertLine);
+    else
+        assfail(g_szRTAssertMsg1, g_pszRTAssertFile, g_u32RTAssertLine);
+    g_szRTAssertMsg2[0] = '\0';
+}
+
diff --git a/src/VBox/Runtime/r0drv/solaris/dbgkrnlinfo-r0drv-solaris.c b/src/VBox/Runtime/r0drv/solaris/dbgkrnlinfo-r0drv-solaris.c
new file mode 100644
index 00000000..896d22d6
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/dbgkrnlinfo-r0drv-solaris.c
@@ -0,0 +1,339 @@
+/* $Id: dbgkrnlinfo-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Kernel debug information, Ring-0 Driver, Solaris Code.
+ */
+
+/*
+ * Copyright (C) 2012-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-solaris-kernel.h"
+#include "internal/iprt.h"
+
+#include <iprt/dbg.h>
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/log.h>
+#include <iprt/mem.h>
+#include <iprt/string.h>
+#include <iprt/thread.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Solaris kernel debug info instance data.
+ */
+typedef struct RTDBGKRNLINFOINT
+{
+    /** Magic value (RTDBGKRNLINFO_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** The number of threads referencing this object. */
+    uint32_t volatile   cRefs;
+    /** Pointer to the genunix CTF handle. */
+    ctf_file_t         *pGenUnixCTF;
+    /** Pointer to the genunix module handle. */
+    modctl_t           *pGenUnixMod;
+} RTDBGKRNLINFOINT;
+/** Pointer to the solaris kernel debug info instance data. */
+typedef struct RTDBGKRNLINFOINT *PRTDBGKRNLINFOINT;
+
+
+/**
+ * Retains a kernel module and opens the CTF data associated with it.
+ *
+ * @param pszModule     The name of the module to open.
+ * @param ppMod         Where to store the module handle.
+ * @param ppCTF         Where to store the module's CTF handle.
+ *
+ * @return IPRT status code.
+ */
+static int rtR0DbgKrnlInfoModRetain(char *pszModule, modctl_t **ppMod, ctf_file_t **ppCTF)
+{
+    AssertPtrReturn(pszModule, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(ppMod, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(ppCTF, VERR_INVALID_PARAMETER);
+
+    int rc = VINF_SUCCESS;
+    modid_t ModId = mod_name_to_modid(pszModule);
+    if (ModId != -1)
+    {
+        *ppMod = mod_hold_by_id(ModId);
+        if (*ppMod)
+        {
+            /*
+             * Hold mod_lock as ctf_modopen may update the module with uncompressed CTF data.
+             */
+            int err;
+            mutex_enter(&mod_lock);
+            *ppCTF = ctf_modopen(((modctl_t *)*ppMod)->mod_mp, &err);
+            mutex_exit(&mod_lock);
+            mod_release_mod(*ppMod);
+
+            if (*ppCTF)
+                return VINF_SUCCESS;
+            else
+            {
+                LogRel(("rtR0DbgKrnlInfoModRetain: ctf_modopen failed for '%s' err=%d\n", pszModule, err));
+                rc = VERR_INTERNAL_ERROR_3;
+            }
+        }
+        else
+        {
+            LogRel(("rtR0DbgKrnlInfoModRetain: mod_hold_by_id failed for '%s'\n", pszModule));
+            rc = VERR_INTERNAL_ERROR_2;
+        }
+    }
+    else
+    {
+        LogRel(("rtR0DbgKrnlInfoModRetain: mod_name_to_modid failed for '%s'\n", pszModule));
+        rc = VERR_INTERNAL_ERROR;
+    }
+
+    return rc;
+}
+
+
+/**
+ * Releases the kernel module and closes its CTF data.
+ *
+ * @param pMod          Pointer to the module handle.
+ * @param pCTF          Pointer to the module's CTF handle.
+ */
+static void rtR0DbgKrnlInfoModRelease(modctl_t *pMod, ctf_file_t *pCTF)
+{
+    AssertPtrReturnVoid(pMod);
+    AssertPtrReturnVoid(pCTF);
+
+    ctf_close(pCTF);
+}
+
+
+/**
+ * Helper for opening the specified kernel module.
+ *
+ * @param pszModule         The name of the module.
+ * @param ppMod             Where to store the module handle.
+ * @param ppCtf             Where to store the module's CTF handle.
+ *
+ * @returns Pointer to the CTF structure for the module.
+ */
+static int rtR0DbgKrnlInfoModRetainEx(const char *pszModule, modctl_t **ppMod, ctf_file_t **ppCtf)
+{
+    char *pszMod = RTStrDup(pszModule);
+    if (RT_LIKELY(pszMod))
+    {
+        int rc = rtR0DbgKrnlInfoModRetain(pszMod, ppMod, ppCtf);
+        RTStrFree(pszMod);
+        if (RT_SUCCESS(rc))
+        {
+            AssertPtrReturn(*ppMod, VERR_INTERNAL_ERROR_2);
+            AssertPtrReturn(*ppCtf, VERR_INTERNAL_ERROR_3);
+        }
+        return rc;
+    }
+    return VERR_NO_MEMORY;
+}
+
+
+RTR0DECL(int) RTR0DbgKrnlInfoOpen(PRTDBGKRNLINFO phKrnlInfo, uint32_t fFlags)
+{
+    AssertReturn(fFlags == 0, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(phKrnlInfo, VERR_INVALID_POINTER);
+    /* This can be called as part of IPRT init, in which case we have no thread preempt information yet. */
+    if (g_frtSolInitDone)
+        RT_ASSERT_PREEMPTIBLE();
+
+    *phKrnlInfo = NIL_RTDBGKRNLINFO;
+    PRTDBGKRNLINFOINT pThis = (PRTDBGKRNLINFOINT)RTMemAllocZ(sizeof(*pThis));
+    if (!pThis)
+        return VERR_NO_MEMORY;
+
+    char szGenUnixModName[] = "genunix";
+    int rc = rtR0DbgKrnlInfoModRetain(szGenUnixModName, &pThis->pGenUnixMod, &pThis->pGenUnixCTF);
+    if (RT_SUCCESS(rc))
+    {
+        pThis->u32Magic       = RTDBGKRNLINFO_MAGIC;
+        pThis->cRefs          = 1;
+
+        *phKrnlInfo = pThis;
+        return VINF_SUCCESS;
+    }
+
+    LogRel(("RTR0DbgKrnlInfoOpen: rtR0DbgKrnlInfoModRetain failed rc=%d.\n", rc));
+    RTMemFree(pThis);
+    return rc;
+}
+
+
+RTR0DECL(uint32_t) RTR0DbgKrnlInfoRetain(RTDBGKRNLINFO hKrnlInfo)
+{
+    PRTDBGKRNLINFOINT pThis = hKrnlInfo;
+    AssertPtrReturn(pThis, UINT32_MAX);
+    AssertMsgReturn(pThis->u32Magic == RTDBGKRNLINFO_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), UINT32_MAX);
+
+    uint32_t cRefs = ASMAtomicIncU32(&pThis->cRefs);
+    Assert(cRefs && cRefs < 100000);
+    return cRefs;
+}
+
+
+RTR0DECL(uint32_t) RTR0DbgKrnlInfoRelease(RTDBGKRNLINFO hKrnlInfo)
+{
+    PRTDBGKRNLINFOINT pThis = hKrnlInfo;
+    if (pThis == NIL_RTDBGKRNLINFO)
+        return 0;
+    AssertPtrReturn(pThis, UINT32_MAX);
+    AssertMsgReturn(pThis->u32Magic == RTDBGKRNLINFO_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), UINT32_MAX);
+    if (g_frtSolInitDone)
+        RT_ASSERT_PREEMPTIBLE();
+
+    uint32_t cRefs = ASMAtomicDecU32(&pThis->cRefs);
+    if (cRefs == 0)
+    {
+        pThis->u32Magic = ~RTDBGKRNLINFO_MAGIC;
+        rtR0DbgKrnlInfoModRelease(pThis->pGenUnixMod, pThis->pGenUnixCTF);
+        RTMemFree(pThis);
+    }
+    return cRefs;
+}
+
+
+RTR0DECL(int) RTR0DbgKrnlInfoQueryMember(RTDBGKRNLINFO hKrnlInfo, const char *pszModule, const char *pszStructure,
+                                         const char *pszMember, size_t *poffMember)
+{
+    PRTDBGKRNLINFOINT pThis = hKrnlInfo;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTDBGKRNLINFO_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+    AssertPtrReturn(pszMember, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(pszStructure, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(poffMember, VERR_INVALID_PARAMETER);
+    if (g_frtSolInitDone)
+        RT_ASSERT_PREEMPTIBLE();
+
+    ctf_file_t *pCtf = NULL;
+    modctl_t   *pMod = NULL;
+    if (!pszModule)
+    {
+        pCtf = pThis->pGenUnixCTF;
+        pMod = pThis->pGenUnixMod;
+    }
+    else
+    {
+        int rc2 = rtR0DbgKrnlInfoModRetainEx(pszModule, &pMod, &pCtf);
+        if (RT_FAILURE(rc2))
+            return rc2;
+        Assert(pMod);
+        Assert(pCtf);
+    }
+
+    int rc = VERR_NOT_FOUND;
+    ctf_id_t TypeIdent = ctf_lookup_by_name(pCtf, pszStructure);
+    if (TypeIdent != CTF_ERR)
+    {
+        ctf_membinfo_t MemberInfo;
+        RT_ZERO(MemberInfo);
+        if (ctf_member_info(pCtf, TypeIdent, pszMember, &MemberInfo) != CTF_ERR)
+        {
+            *poffMember = (MemberInfo.ctm_offset >> 3);
+            rc = VINF_SUCCESS;
+        }
+    }
+
+    if (pszModule)
+        rtR0DbgKrnlInfoModRelease(pMod, pCtf);
+    return rc;
+}
+
+
+RTR0DECL(int) RTR0DbgKrnlInfoQuerySymbol(RTDBGKRNLINFO hKrnlInfo, const char *pszModule,
+                                               const char *pszSymbol, void **ppvSymbol)
+{
+    PRTDBGKRNLINFOINT pThis = hKrnlInfo;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTDBGKRNLINFO_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+    AssertPtrReturn(pszSymbol, VERR_INVALID_PARAMETER);
+    AssertPtrNullReturn(ppvSymbol, VERR_INVALID_PARAMETER);
+    AssertReturn(!pszModule, VERR_MODULE_NOT_FOUND);
+    if (g_frtSolInitDone)
+        RT_ASSERT_PREEMPTIBLE();
+
+    uintptr_t uValue = kobj_getsymvalue((char *)pszSymbol, 1 /* only kernel */);
+    if (ppvSymbol)
+        *ppvSymbol = (void *)uValue;
+    if (uValue)
+        return VINF_SUCCESS;
+    return VERR_SYMBOL_NOT_FOUND;
+}
+
+
+RTR0DECL(int) RTR0DbgKrnlInfoQuerySize(RTDBGKRNLINFO hKrnlInfo, const char *pszModule, const char *pszType, size_t *pcbType)
+{
+    PRTDBGKRNLINFOINT pThis = hKrnlInfo;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTDBGKRNLINFO_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+    AssertPtrReturn(pszType, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(pcbType, VERR_INVALID_PARAMETER);
+    if (g_frtSolInitDone)
+        RT_ASSERT_PREEMPTIBLE();
+
+    modctl_t   *pMod = NULL;
+    ctf_file_t *pCtf = NULL;
+    if (!pszModule)
+    {
+        pCtf = pThis->pGenUnixCTF;
+        pMod = pThis->pGenUnixMod;
+    }
+    else
+    {
+        int rc2 = rtR0DbgKrnlInfoModRetainEx(pszModule, &pMod, &pCtf);
+        if (RT_FAILURE(rc2))
+            return rc2;
+        Assert(pMod);
+        Assert(pCtf);
+    }
+
+    int rc = VERR_NOT_FOUND;
+    ctf_id_t TypeIdent = ctf_lookup_by_name(pCtf, pszType);
+    if (TypeIdent != CTF_ERR)
+    {
+        ssize_t cbType = ctf_type_size(pCtf, TypeIdent);
+        if (cbType > 0)
+        {
+            *pcbType = cbType;
+            rc = VINF_SUCCESS;
+        }
+        else
+            rc = VERR_WRONG_TYPE;
+    }
+
+    if (pszModule)
+        rtR0DbgKrnlInfoModRelease(pMod, pCtf);
+    return rc;
+}
+
diff --git a/src/VBox/Runtime/r0drv/solaris/initterm-r0drv-solaris.c b/src/VBox/Runtime/r0drv/solaris/initterm-r0drv-solaris.c
new file mode 100644
index 00000000..e8dd270c
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/initterm-r0drv-solaris.c
@@ -0,0 +1,300 @@
+/* $Id: initterm-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Initialization & Termination, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-solaris-kernel.h"
+#include "internal/iprt.h"
+
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include "internal/initterm.h"
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/** Kernel debug info handle. */
+RTDBGKRNLINFO                   g_hKrnlDbgInfo;
+/** Indicates that the spl routines (and therefore a bunch of other ones too)
+ * will set EFLAGS::IF and break code that disables interrupts.  */
+bool g_frtSolSplSetsEIF = false;
+/** timeout_generic address. */
+PFNSOL_timeout_generic          g_pfnrtR0Sol_timeout_generic = NULL;
+/** untimeout_generic address. */
+PFNSOL_untimeout_generic        g_pfnrtR0Sol_untimeout_generic = NULL;
+/** cyclic_reprogram address. */
+PFNSOL_cyclic_reprogram         g_pfnrtR0Sol_cyclic_reprogram = NULL;
+/** page_noreloc_supported address. */
+PFNSOL_page_noreloc_supported   g_pfnrtR0Sol_page_noreloc_supported = NULL;
+/** Whether to use the kernel page freelist. */
+bool                            g_frtSolUseKflt = false;
+/** Whether we've completed R0 initialization. */
+bool                            g_frtSolInitDone = false;
+/** Whether to use old-style xc_call interface. */
+bool                            g_frtSolOldIPI = false;
+/** Whether to use old-style xc_call interface using one ulong_t as the CPU set
+ *  representation. */
+bool                            g_frtSolOldIPIUlong = false;
+/** The xc_call callout table structure. */
+RTR0FNSOLXCCALL                 g_rtSolXcCall;
+/** Whether to use the old-style installctx()/removectx() routines. */
+bool                            g_frtSolOldThreadCtx = false;
+/** The thread-context hooks callout table structure. */
+RTR0FNSOLTHREADCTX              g_rtSolThreadCtx;
+/** Thread preemption offset in the thread structure. */
+size_t                          g_offrtSolThreadPreempt;
+/** Thread ID offset in the thread structure. */
+size_t                          g_offrtSolThreadId;
+/** The interrupt (pinned) thread pointer offset in the thread structure.  */
+size_t                          g_offrtSolThreadIntrThread;
+/** The dispatcher lock pointer offset in the thread structure. */
+size_t                          g_offrtSolThreadLock;
+/** The process pointer offset in the thread structure. */
+size_t                          g_offrtSolThreadProc;
+/** Host scheduler preemption offset. */
+size_t                          g_offrtSolCpuPreempt;
+/** Host scheduler force preemption offset. */
+size_t                          g_offrtSolCpuForceKernelPreempt;
+/** Whether to use the old-style map_addr() routine. */
+bool                            g_frtSolOldMapAddr = false;
+/** The map_addr() hooks callout table structure. */
+RTR0FNSOLMAPADDR                g_rtSolMapAddr;
+/* Resolve using dl_lookup (remove if no longer relevant for supported S10 versions) */
+extern void contig_free(void *addr, size_t size);
+#pragma weak contig_free
+/** contig_free address. */
+PFNSOL_contig_free              g_pfnrtR0Sol_contig_free = contig_free;
+
+DECLHIDDEN(int) rtR0InitNative(void)
+{
+    /*
+     * IPRT has not yet been initialized at this point, so use Solaris' native cmn_err() for logging.
+     */
+    int rc = RTR0DbgKrnlInfoOpen(&g_hKrnlDbgInfo, 0 /* fFlags */);
+    if (RT_SUCCESS(rc))
+    {
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+        /*
+         * Detect whether spl*() is preserving the interrupt flag or not.
+         * This is a problem on S10.
+         */
+        RTCCUINTREG uOldFlags = ASMIntDisableFlags();
+        int iOld = splr(DISP_LEVEL);
+        if (ASMIntAreEnabled())
+            g_frtSolSplSetsEIF = true;
+        splx(iOld);
+        if (ASMIntAreEnabled())
+            g_frtSolSplSetsEIF = true;
+        ASMSetFlags(uOldFlags);
+#else
+        /* PORTME: See if the amd64/x86 problem applies to this architecture. */
+#endif
+        /*
+         * Mandatory: Preemption offsets.
+         */
+        rc = RTR0DbgKrnlInfoQueryMember(g_hKrnlDbgInfo, NULL, "cpu_t", "cpu_runrun", &g_offrtSolCpuPreempt);
+        if (RT_FAILURE(rc))
+        {
+            cmn_err(CE_NOTE, "Failed to find cpu_t::cpu_runrun!\n");
+            goto errorbail;
+        }
+
+        rc = RTR0DbgKrnlInfoQueryMember(g_hKrnlDbgInfo, NULL, "cpu_t", "cpu_kprunrun", &g_offrtSolCpuForceKernelPreempt);
+        if (RT_FAILURE(rc))
+        {
+            cmn_err(CE_NOTE, "Failed to find cpu_t::cpu_kprunrun!\n");
+            goto errorbail;
+        }
+
+        rc = RTR0DbgKrnlInfoQueryMember(g_hKrnlDbgInfo, NULL, "kthread_t", "t_preempt", &g_offrtSolThreadPreempt);
+        if (RT_FAILURE(rc))
+        {
+            cmn_err(CE_NOTE, "Failed to find kthread_t::t_preempt!\n");
+            goto errorbail;
+        }
+
+        rc = RTR0DbgKrnlInfoQueryMember(g_hKrnlDbgInfo, NULL, "kthread_t", "t_did", &g_offrtSolThreadId);
+        if (RT_FAILURE(rc))
+        {
+            cmn_err(CE_NOTE, "Failed to find kthread_t::t_did!\n");
+            goto errorbail;
+        }
+
+        rc = RTR0DbgKrnlInfoQueryMember(g_hKrnlDbgInfo, NULL, "kthread_t", "t_intr", &g_offrtSolThreadIntrThread);
+        if (RT_FAILURE(rc))
+        {
+            cmn_err(CE_NOTE, "Failed to find kthread_t::t_intr!\n");
+            goto errorbail;
+        }
+
+        rc = RTR0DbgKrnlInfoQueryMember(g_hKrnlDbgInfo, NULL, "kthread_t", "t_lockp", &g_offrtSolThreadLock);
+        if (RT_FAILURE(rc))
+        {
+            cmn_err(CE_NOTE, "Failed to find kthread_t::t_lockp!\n");
+            goto errorbail;
+        }
+
+        rc = RTR0DbgKrnlInfoQueryMember(g_hKrnlDbgInfo, NULL, "kthread_t", "t_procp", &g_offrtSolThreadProc);
+        if (RT_FAILURE(rc))
+        {
+            cmn_err(CE_NOTE, "Failed to find kthread_t::t_procp!\n");
+            goto errorbail;
+        }
+        cmn_err(CE_CONT, "!cpu_t::cpu_runrun @ 0x%lx (%ld)\n",    g_offrtSolCpuPreempt, g_offrtSolCpuPreempt);
+        cmn_err(CE_CONT, "!cpu_t::cpu_kprunrun @ 0x%lx (%ld)\n",  g_offrtSolCpuForceKernelPreempt, g_offrtSolCpuForceKernelPreempt);
+        cmn_err(CE_CONT, "!kthread_t::t_preempt @ 0x%lx (%ld)\n", g_offrtSolThreadPreempt, g_offrtSolThreadPreempt);
+        cmn_err(CE_CONT, "!kthread_t::t_did @ 0x%lx (%ld)\n",     g_offrtSolThreadId, g_offrtSolThreadId);
+        cmn_err(CE_CONT, "!kthread_t::t_intr @ 0x%lx (%ld)\n",    g_offrtSolThreadIntrThread, g_offrtSolThreadIntrThread);
+        cmn_err(CE_CONT, "!kthread_t::t_lockp @ 0x%lx (%ld)\n",   g_offrtSolThreadLock, g_offrtSolThreadLock);
+        cmn_err(CE_CONT, "!kthread_t::t_procp @ 0x%lx (%ld)\n",   g_offrtSolThreadProc, g_offrtSolThreadProc);
+
+        /*
+         * Mandatory: CPU cross call infrastructure. Refer the-solaris-kernel.h for details.
+         */
+        rc = RTR0DbgKrnlInfoQuerySymbol(g_hKrnlDbgInfo, NULL /* pszModule */, "xc_init_cpu", NULL /* ppvSymbol */);
+        if (RT_SUCCESS(rc))
+        {
+            if (ncpus > IPRT_SOL_NCPUS)
+            {
+                cmn_err(CE_NOTE, "rtR0InitNative: CPU count mismatch! ncpus=%d IPRT_SOL_NCPUS=%d\n", ncpus, IPRT_SOL_NCPUS);
+                rc = VERR_NOT_SUPPORTED;
+                goto errorbail;
+            }
+            g_rtSolXcCall.u.pfnSol_xc_call = (void *)xc_call;
+        }
+        else
+        {
+            g_frtSolOldIPI = true;
+            g_rtSolXcCall.u.pfnSol_xc_call_old = (void *)xc_call;
+            if (max_cpuid + 1 == sizeof(ulong_t) * 8)
+            {
+                g_frtSolOldIPIUlong = true;
+                g_rtSolXcCall.u.pfnSol_xc_call_old_ulong = (void *)xc_call;
+            }
+            else if (max_cpuid + 1 != IPRT_SOL_NCPUS)
+            {
+                cmn_err(CE_NOTE, "rtR0InitNative: cpuset_t size mismatch! max_cpuid=%d IPRT_SOL_NCPUS=%d\n", max_cpuid,
+                        IPRT_SOL_NCPUS);
+                rc = VERR_NOT_SUPPORTED;
+                goto errorbail;
+            }
+        }
+
+        /*
+         * Mandatory: Thread-context hooks.
+         */
+        rc = RTR0DbgKrnlInfoQuerySymbol(g_hKrnlDbgInfo, NULL /* pszModule */, "exitctx",  NULL /* ppvSymbol */);
+        if (RT_SUCCESS(rc))
+        {
+            g_rtSolThreadCtx.Install.pfnSol_installctx = (void *)installctx;
+            g_rtSolThreadCtx.Remove.pfnSol_removectx   = (void *)removectx;
+        }
+        else
+        {
+            g_frtSolOldThreadCtx = true;
+            g_rtSolThreadCtx.Install.pfnSol_installctx_old = (void *)installctx;
+            g_rtSolThreadCtx.Remove.pfnSol_removectx_old   = (void *)removectx;
+        }
+
+        /*
+         * Mandatory: map_addr() hooks.
+         */
+        rc = RTR0DbgKrnlInfoQuerySymbol(g_hKrnlDbgInfo, NULL /* pszModule */, "plat_map_align_amount",  NULL /* ppvSymbol */);
+        if (RT_SUCCESS(rc))
+        {
+            g_rtSolMapAddr.u.pfnSol_map_addr    = (void *)map_addr;
+        }
+        else
+        {
+            g_frtSolOldMapAddr = true;
+            g_rtSolMapAddr.u.pfnSol_map_addr_old    = (void *)map_addr;
+        }
+
+        /*
+         * Optional: Timeout hooks.
+         */
+        RTR0DbgKrnlInfoQuerySymbol(g_hKrnlDbgInfo, NULL /* pszModule */, "timeout_generic",
+                                   (void **)&g_pfnrtR0Sol_timeout_generic);
+        RTR0DbgKrnlInfoQuerySymbol(g_hKrnlDbgInfo, NULL /* pszModule */, "untimeout_generic",
+                                   (void **)&g_pfnrtR0Sol_untimeout_generic);
+        if ((g_pfnrtR0Sol_timeout_generic == NULL) != (g_pfnrtR0Sol_untimeout_generic == NULL))
+        {
+            static const char *s_apszFn[2] = { "timeout_generic", "untimeout_generic" };
+            bool iMissingFn = g_pfnrtR0Sol_timeout_generic == NULL;
+            cmn_err(CE_NOTE, "rtR0InitNative: Weird! Found %s but not %s!\n", s_apszFn[!iMissingFn], s_apszFn[iMissingFn]);
+            g_pfnrtR0Sol_timeout_generic   = NULL;
+            g_pfnrtR0Sol_untimeout_generic = NULL;
+        }
+        RTR0DbgKrnlInfoQuerySymbol(g_hKrnlDbgInfo, NULL /* pszModule */, "cyclic_reprogram",
+                                   (void **)&g_pfnrtR0Sol_cyclic_reprogram);
+
+        /*
+         * Optional: Querying page no-relocation support.
+         */
+        RTR0DbgKrnlInfoQuerySymbol(g_hKrnlDbgInfo, NULL /*pszModule */, "page_noreloc_supported",
+                                   (void **)&g_pfnrtR0Sol_page_noreloc_supported);
+
+        /*
+         * Weak binding failures: contig_free
+         */
+        if (g_pfnrtR0Sol_contig_free == NULL)
+        {
+            rc = RTR0DbgKrnlInfoQuerySymbol(g_hKrnlDbgInfo, NULL /* pszModule */, "contig_free",
+                                            (void **)&g_pfnrtR0Sol_contig_free);
+            if (RT_FAILURE(rc))
+            {
+                cmn_err(CE_NOTE, "rtR0InitNative: failed to find contig_free!\n");
+                goto errorbail;
+            }
+        }
+
+        g_frtSolInitDone = true;
+        return VINF_SUCCESS;
+    }
+    else
+    {
+        cmn_err(CE_NOTE, "RTR0DbgKrnlInfoOpen failed. rc=%d\n", rc);
+        return rc;
+    }
+
+errorbail:
+    RTR0DbgKrnlInfoRelease(g_hKrnlDbgInfo);
+    return rc;
+}
+
+
+DECLHIDDEN(void) rtR0TermNative(void)
+{
+    RTR0DbgKrnlInfoRelease(g_hKrnlDbgInfo);
+    g_frtSolInitDone = false;
+}
+
diff --git a/src/VBox/Runtime/r0drv/solaris/memobj-r0drv-solaris.c b/src/VBox/Runtime/r0drv/solaris/memobj-r0drv-solaris.c
new file mode 100644
index 00000000..ebf2eae2
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/memobj-r0drv-solaris.c
@@ -0,0 +1,1172 @@
+/* $Id: memobj-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Ring-0 Memory Objects, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-solaris-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/memobj.h>
+
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/log.h>
+#include <iprt/mem.h>
+#include <iprt/param.h>
+#include <iprt/process.h>
+#include "internal/memobj.h"
+#include "memobj-r0drv-solaris.h"
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+#define SOL_IS_KRNL_ADDR(vx)    ((uintptr_t)(vx) >= kernelbase)
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * The Solaris version of the memory object structure.
+ */
+typedef struct RTR0MEMOBJSOL
+{
+    /** The core structure. */
+    RTR0MEMOBJINTERNAL  Core;
+    /** Pointer to kernel memory cookie. */
+    ddi_umem_cookie_t   Cookie;
+    /** Shadow locked pages. */
+    void               *pvHandle;
+    /** Access during locking. */
+    int                 fAccess;
+    /** Set if large pages are involved in an RTR0MEMOBJTYPE_PHYS
+     *  allocation. */
+    bool                fLargePage;
+    /** Whether we have individual pages or a kernel-mapped virtual memory block in
+     *  an RTR0MEMOBJTYPE_PHYS_NC allocation. */
+    bool                fIndivPages;
+} RTR0MEMOBJSOL, *PRTR0MEMOBJSOL;
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+static vnode_t                  g_PageVnode;
+static kmutex_t                 g_OffsetMtx;
+static u_offset_t               g_offPage;
+
+static vnode_t                  g_LargePageVnode;
+static kmutex_t                 g_LargePageOffsetMtx;
+static u_offset_t               g_offLargePage;
+static bool                     g_fLargePageNoReloc;
+
+
+/**
+ * Returns the physical address for a virtual address.
+ *
+ * @param pv        The virtual address.
+ *
+ * @returns The physical address corresponding to @a pv.
+ */
+static uint64_t rtR0MemObjSolVirtToPhys(void *pv)
+{
+    struct hat *pHat         = NULL;
+    pfn_t       PageFrameNum = 0;
+    uintptr_t   uVirtAddr    = (uintptr_t)pv;
+
+    if (SOL_IS_KRNL_ADDR(pv))
+        pHat = kas.a_hat;
+    else
+    {
+        proc_t *pProcess = (proc_t *)RTR0ProcHandleSelf();
+        AssertRelease(pProcess);
+        pHat = pProcess->p_as->a_hat;
+    }
+
+    PageFrameNum = hat_getpfnum(pHat, (caddr_t)(uVirtAddr & PAGEMASK));
+    AssertReleaseMsg(PageFrameNum != PFN_INVALID, ("rtR0MemObjSolVirtToPhys failed. pv=%p\n", pv));
+    return (((uint64_t)PageFrameNum << PAGE_SHIFT) | (uVirtAddr & PAGE_OFFSET_MASK));
+}
+
+
+/**
+ * Returns the physical address for a page.
+ *
+ * @param    pPage      Pointer to the page.
+ *
+ * @returns The physical address for a page.
+ */
+static inline uint64_t rtR0MemObjSolPagePhys(page_t *pPage)
+{
+    AssertPtr(pPage);
+    pfn_t PageFrameNum = page_pptonum(pPage);
+    AssertReleaseMsg(PageFrameNum != PFN_INVALID, ("rtR0MemObjSolPagePhys failed pPage=%p\n"));
+    return (uint64_t)PageFrameNum << PAGE_SHIFT;
+}
+
+
+/**
+ * Allocates one page.
+ *
+ * @param virtAddr       The virtual address to which this page maybe mapped in
+ *                       the future.
+ *
+ * @returns Pointer to the allocated page, NULL on failure.
+ */
+static page_t *rtR0MemObjSolPageAlloc(caddr_t virtAddr)
+{
+    u_offset_t      offPage;
+    seg_t           KernelSeg;
+
+    /*
+     * 16777215 terabytes of total memory for all VMs or
+     * restart 8000 1GB VMs 2147483 times until wraparound!
+     */
+    mutex_enter(&g_OffsetMtx);
+    AssertCompileSize(u_offset_t, sizeof(uint64_t)); NOREF(RTASSERTVAR);
+    g_offPage = RT_ALIGN_64(g_offPage, PAGE_SIZE) + PAGE_SIZE;
+    offPage   = g_offPage;
+    mutex_exit(&g_OffsetMtx);
+
+    KernelSeg.s_as = &kas;
+    page_t *pPage = page_create_va(&g_PageVnode, offPage, PAGE_SIZE, PG_WAIT | PG_NORELOC, &KernelSeg, virtAddr);
+    if (RT_LIKELY(pPage))
+    {
+        /*
+         * Lock this page into memory "long term" to prevent this page from being paged out
+         * when we drop the page lock temporarily (during free). Downgrade to a shared lock
+         * to prevent page relocation.
+         */
+        page_pp_lock(pPage, 0 /* COW */, 1 /* Kernel */);
+        page_io_unlock(pPage);
+        page_downgrade(pPage);
+        Assert(PAGE_LOCKED_SE(pPage, SE_SHARED));
+    }
+
+    return pPage;
+}
+
+
+/**
+ * Destroys an allocated page.
+ *
+ * @param pPage         Pointer to the page to be destroyed.
+ * @remarks This function expects page in @c pPage to be shared locked.
+ */
+static void rtR0MemObjSolPageDestroy(page_t *pPage)
+{
+    /*
+     * We need to exclusive lock the pages before freeing them, if upgrading the shared lock to exclusive fails,
+     * drop the page lock and look it up from the hash. Record the page offset before we drop the page lock as
+     * we cannot touch any page_t members once the lock is dropped.
+     */
+    AssertPtr(pPage);
+    Assert(PAGE_LOCKED_SE(pPage, SE_SHARED));
+
+    u_offset_t offPage = pPage->p_offset;
+    int rc = page_tryupgrade(pPage);
+    if (!rc)
+    {
+        page_unlock(pPage);
+        page_t *pFoundPage = page_lookup(&g_PageVnode, offPage, SE_EXCL);
+
+        /*
+         * Since we allocated the pages as PG_NORELOC we should only get back the exact page always.
+         */
+        AssertReleaseMsg(pFoundPage == pPage, ("Page lookup failed %p:%llx returned %p, expected %p\n",
+                                               &g_PageVnode, offPage, pFoundPage, pPage));
+    }
+    Assert(PAGE_LOCKED_SE(pPage, SE_EXCL));
+    page_pp_unlock(pPage, 0 /* COW */, 1 /* Kernel */);
+    page_destroy(pPage, 0 /* move it to the free list */);
+}
+
+
+/* Currently not used on 32-bits, define it to shut up gcc. */
+#if HC_ARCH_BITS == 64
+/**
+ * Allocates physical, non-contiguous memory of pages.
+ *
+ * @param puPhys    Where to store the physical address of first page. Optional,
+ *                  can be NULL.
+ * @param cb        The size of the allocation.
+ *
+ * @return Array of allocated pages, NULL on failure.
+ */
+static page_t **rtR0MemObjSolPagesAlloc(uint64_t *puPhys, size_t cb)
+{
+    /*
+     * VM1:
+     * The page freelist and cachelist both hold pages that are not mapped into any address space.
+     * The cachelist is not really free pages but when memory is exhausted they'll be moved to the
+     * free lists, it's the total of the free+cache list that we see on the 'free' column in vmstat.
+     *
+     * VM2:
+     * @todo Document what happens behind the scenes in VM2 regarding the free and cachelist.
+     */
+
+    /*
+     * Non-pageable memory reservation request for _4K pages, don't sleep.
+     */
+    size_t cPages = (cb + PAGE_SIZE - 1) >> PAGE_SHIFT;
+    int rc = page_resv(cPages, KM_NOSLEEP);
+    if (rc)
+    {
+        size_t   cbPages = cPages * sizeof(page_t *);
+        page_t **ppPages = kmem_zalloc(cbPages, KM_SLEEP);
+        if (RT_LIKELY(ppPages))
+        {
+            /*
+             * Get pages from kseg, the 'virtAddr' here is only for colouring but unfortunately
+             * we don't yet have the 'virtAddr' to which this memory may be mapped.
+             */
+            caddr_t virtAddr = 0;
+            for (size_t i = 0; i < cPages; i++, virtAddr += PAGE_SIZE)
+            {
+                /*
+                 * Get a page from the free list locked exclusively. The page will be named (hashed in)
+                 * and we rely on it during free. The page we get will be shared locked to prevent the page
+                 * from being relocated.
+                 */
+                page_t *pPage = rtR0MemObjSolPageAlloc(virtAddr);
+                if (RT_UNLIKELY(!pPage))
+                {
+                    /*
+                     * No page found, release whatever pages we grabbed so far.
+                     */
+                    for (size_t k = 0; k < i; k++)
+                        rtR0MemObjSolPageDestroy(ppPages[k]);
+                    kmem_free(ppPages, cbPages);
+                    page_unresv(cPages);
+                    return NULL;
+                }
+
+                ppPages[i] = pPage;
+            }
+
+            if (puPhys)
+                *puPhys = rtR0MemObjSolPagePhys(ppPages[0]);
+            return ppPages;
+        }
+
+        page_unresv(cPages);
+    }
+
+    return NULL;
+}
+#endif  /* HC_ARCH_BITS == 64 */
+
+
+/**
+ * Frees the allocates pages.
+ *
+ * @param ppPages       Pointer to the page list.
+ * @param cbPages       Size of the allocation.
+ */
+static void rtR0MemObjSolPagesFree(page_t **ppPages, size_t cb)
+{
+    size_t cPages  = (cb + PAGE_SIZE - 1) >> PAGE_SHIFT;
+    size_t cbPages = cPages * sizeof(page_t *);
+    for (size_t iPage = 0; iPage < cPages; iPage++)
+        rtR0MemObjSolPageDestroy(ppPages[iPage]);
+
+    kmem_free(ppPages, cbPages);
+    page_unresv(cPages);
+}
+
+
+/**
+ * Allocates one large page.
+ *
+ * @param puPhys        Where to store the physical address of the allocated
+ *                      page. Optional, can be NULL.
+ * @param cbLargePage   Size of the large page.
+ *
+ * @returns Pointer to a list of pages that cover the large page, NULL on
+ *        failure.
+ */
+static page_t **rtR0MemObjSolLargePageAlloc(uint64_t *puPhys, size_t cbLargePage)
+{
+    /*
+     * Check PG_NORELOC support for large pages. Using this helps prevent _1G page
+     * fragementation on systems that support it.
+     */
+    static bool fPageNoRelocChecked = false;
+    if (fPageNoRelocChecked == false)
+    {
+        fPageNoRelocChecked = true;
+        g_fLargePageNoReloc = false;
+        if (   g_pfnrtR0Sol_page_noreloc_supported
+            && g_pfnrtR0Sol_page_noreloc_supported(cbLargePage))
+        {
+            g_fLargePageNoReloc = true;
+        }
+    }
+
+    /*
+     * Non-pageable memory reservation request for _4K pages, don't sleep.
+     */
+    size_t cPages       = (cbLargePage + PAGE_SIZE - 1) >> PAGE_SHIFT;
+    size_t cbPages      = cPages * sizeof(page_t *);
+    u_offset_t offPage  = 0;
+    int rc = page_resv(cPages, KM_NOSLEEP);
+    if (rc)
+    {
+        page_t **ppPages = kmem_zalloc(cbPages, KM_SLEEP);
+        if (RT_LIKELY(ppPages))
+        {
+            mutex_enter(&g_LargePageOffsetMtx);
+            AssertCompileSize(u_offset_t, sizeof(uint64_t)); NOREF(RTASSERTVAR);
+            g_offLargePage = RT_ALIGN_64(g_offLargePage, cbLargePage) + cbLargePage;
+            offPage        = g_offLargePage;
+            mutex_exit(&g_LargePageOffsetMtx);
+
+            seg_t KernelSeg;
+            KernelSeg.s_as = &kas;
+            page_t *pRootPage = page_create_va_large(&g_LargePageVnode, offPage, cbLargePage,
+                                                     PG_EXCL | (g_fLargePageNoReloc ? PG_NORELOC : 0), &KernelSeg,
+                                                     0 /* vaddr */,NULL /* locality group */);
+            if (pRootPage)
+            {
+                /*
+                 * Split it into sub-pages, downgrade each page to a shared lock to prevent page relocation.
+                 */
+                page_t *pPageList = pRootPage;
+                for (size_t iPage = 0; iPage < cPages; iPage++)
+                {
+                    page_t *pPage = pPageList;
+                    AssertPtr(pPage);
+                    AssertMsg(page_pptonum(pPage) == iPage + page_pptonum(pRootPage),
+                        ("%p:%lx %lx+%lx\n", pPage, page_pptonum(pPage), iPage, page_pptonum(pRootPage)));
+                    AssertMsg(pPage->p_szc == pRootPage->p_szc, ("Size code mismatch %p %d %d\n", pPage,
+                                                                 (int)pPage->p_szc, (int)pRootPage->p_szc));
+
+                    /*
+                     * Lock the page into memory "long term". This prevents callers of page_try_demote_pages() (such as the
+                     * pageout scanner) from demoting the large page into smaller pages while we temporarily release the
+                     * exclusive lock (during free). We pass "0, 1" since we've already accounted for availrmem during
+                     * page_resv().
+                     */
+                    page_pp_lock(pPage, 0 /* COW */, 1 /* Kernel */);
+
+                    page_sub(&pPageList, pPage);
+                    page_io_unlock(pPage);
+                    page_downgrade(pPage);
+                    Assert(PAGE_LOCKED_SE(pPage, SE_SHARED));
+
+                    ppPages[iPage] = pPage;
+                }
+                Assert(pPageList == NULL);
+                Assert(ppPages[0] == pRootPage);
+
+                uint64_t uPhys = rtR0MemObjSolPagePhys(pRootPage);
+                AssertMsg(!(uPhys & (cbLargePage - 1)), ("%llx %zx\n", uPhys, cbLargePage));
+                if (puPhys)
+                    *puPhys = uPhys;
+                return ppPages;
+            }
+
+            /*
+             * Don't restore offPrev in case of failure (race condition), we have plenty of offset space.
+             * The offset must be unique (for the same vnode) or we'll encounter panics on page_create_va_large().
+             */
+            kmem_free(ppPages, cbPages);
+        }
+
+        page_unresv(cPages);
+    }
+    return NULL;
+}
+
+
+/**
+ * Frees the large page.
+ *
+ * @param    ppPages        Pointer to the list of small pages that cover the
+ *                          large page.
+ * @param    cbLargePage    Size of the allocation (i.e. size of the large
+ *                          page).
+ */
+static void rtR0MemObjSolLargePageFree(page_t **ppPages, size_t cbLargePage)
+{
+    Assert(ppPages);
+    Assert(cbLargePage > PAGE_SIZE);
+
+    bool   fDemoted   = false;
+    size_t cPages     = (cbLargePage + PAGE_SIZE - 1) >> PAGE_SHIFT;
+    size_t cbPages    = cPages * sizeof(page_t *);
+    page_t *pPageList = ppPages[0];
+
+    for (size_t iPage = 0; iPage < cPages; iPage++)
+    {
+        /*
+         * We need the pages exclusively locked, try upgrading the shared lock.
+         * If it fails, drop the shared page lock (cannot access any page_t members once this is done)
+         * and lookup the page from the page hash locking it exclusively.
+         */
+        page_t    *pPage    = ppPages[iPage];
+        u_offset_t offPage  = pPage->p_offset;
+        int rc = page_tryupgrade(pPage);
+        if (!rc)
+        {
+            page_unlock(pPage);
+            page_t *pFoundPage = page_lookup(&g_LargePageVnode, offPage, SE_EXCL);
+            AssertRelease(pFoundPage);
+
+            if (g_fLargePageNoReloc)
+            {
+                /*
+                 * This can only be guaranteed if PG_NORELOC is used while allocating the pages.
+                 */
+                AssertReleaseMsg(pFoundPage == pPage,
+                             ("lookup failed %p:%llu returned %p, expected %p\n", &g_LargePageVnode, offPage,
+                              pFoundPage, pPage));
+            }
+
+            /*
+             * Check for page demotion (regardless of relocation). Some places in Solaris (e.g. VM1 page_retire())
+             * could possibly demote the large page to _4K pages between our call to page_unlock() and page_lookup().
+             */
+            if (page_get_pagecnt(pFoundPage->p_szc) == 1)   /* Base size of only _4K associated with this page. */
+                fDemoted = true;
+            pPage          = pFoundPage;
+            ppPages[iPage] = pFoundPage;
+        }
+        Assert(PAGE_LOCKED_SE(pPage, SE_EXCL));
+        page_pp_unlock(pPage, 0 /* COW */, 1 /* Kernel */);
+    }
+
+    if (fDemoted)
+    {
+        for (size_t iPage = 0; iPage < cPages; iPage++)
+        {
+            Assert(page_get_pagecnt(ppPages[iPage]->p_szc) == 1);
+            page_destroy(ppPages[iPage], 0 /* move it to the free list */);
+        }
+    }
+    else
+    {
+        /*
+         * Although we shred the adjacent pages in the linked list, page_destroy_pages works on
+         * adjacent pages via array increments. So this does indeed free all the pages.
+         */
+        AssertPtr(pPageList);
+        page_destroy_pages(pPageList);
+    }
+    kmem_free(ppPages, cbPages);
+    page_unresv(cPages);
+}
+
+
+/**
+ * Unmaps kernel/user-space mapped memory.
+ *
+ * @param    pv         Pointer to the mapped memory block.
+ * @param    cb         Size of the memory block.
+ */
+static void rtR0MemObjSolUnmap(void *pv, size_t cb)
+{
+    if (SOL_IS_KRNL_ADDR(pv))
+    {
+        hat_unload(kas.a_hat, pv, cb, HAT_UNLOAD | HAT_UNLOAD_UNLOCK);
+        vmem_free(heap_arena, pv, cb);
+    }
+    else
+    {
+        struct as *pAddrSpace = ((proc_t *)RTR0ProcHandleSelf())->p_as;
+        AssertPtr(pAddrSpace);
+        as_rangelock(pAddrSpace);
+        as_unmap(pAddrSpace, pv, cb);
+        as_rangeunlock(pAddrSpace);
+    }
+}
+
+
+/**
+ * Lock down memory mappings for a virtual address.
+ *
+ * @param    pv             Pointer to the memory to lock down.
+ * @param    cb             Size of the memory block.
+ * @param    fAccess        Page access rights (S_READ, S_WRITE, S_EXEC)
+ *
+ * @returns IPRT status code.
+ */
+static int rtR0MemObjSolLock(void *pv, size_t cb, int fPageAccess)
+{
+    /*
+     * Kernel memory mappings on x86/amd64 are always locked, only handle user-space memory.
+     */
+    if (!SOL_IS_KRNL_ADDR(pv))
+    {
+        proc_t *pProc = (proc_t *)RTR0ProcHandleSelf();
+        AssertPtr(pProc);
+        faultcode_t rc = as_fault(pProc->p_as->a_hat, pProc->p_as, (caddr_t)pv, cb, F_SOFTLOCK, fPageAccess);
+        if (rc)
+        {
+            LogRel(("rtR0MemObjSolLock failed for pv=%pv cb=%lx fPageAccess=%d rc=%d\n", pv, cb, fPageAccess, rc));
+            return VERR_LOCK_FAILED;
+        }
+    }
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Unlock memory mappings for a virtual address.
+ *
+ * @param    pv             Pointer to the locked memory.
+ * @param    cb             Size of the memory block.
+ * @param    fPageAccess    Page access rights (S_READ, S_WRITE, S_EXEC).
+ */
+static void rtR0MemObjSolUnlock(void *pv, size_t cb, int fPageAccess)
+{
+    if (!SOL_IS_KRNL_ADDR(pv))
+    {
+        proc_t *pProcess = (proc_t *)RTR0ProcHandleSelf();
+        AssertPtr(pProcess);
+        as_fault(pProcess->p_as->a_hat, pProcess->p_as, (caddr_t)pv, cb, F_SOFTUNLOCK, fPageAccess);
+    }
+}
+
+
+/**
+ * Maps a list of physical pages into user address space.
+ *
+ * @param    pVirtAddr      Where to store the virtual address of the mapping.
+ * @param    fPageAccess    Page access rights (PROT_READ, PROT_WRITE,
+ *                          PROT_EXEC)
+ * @param    paPhysAddrs    Array of physical addresses to pages.
+ * @param    cb             Size of memory being mapped.
+ *
+ * @returns IPRT status code.
+ */
+static int rtR0MemObjSolUserMap(caddr_t *pVirtAddr, unsigned fPageAccess, uint64_t *paPhysAddrs, size_t cb, size_t cbPageSize)
+{
+    struct as *pAddrSpace = ((proc_t *)RTR0ProcHandleSelf())->p_as;
+    int rc;
+    SEGVBOX_CRARGS Args;
+
+    Args.paPhysAddrs = paPhysAddrs;
+    Args.fPageAccess = fPageAccess;
+    Args.cbPageSize  = cbPageSize;
+
+    as_rangelock(pAddrSpace);
+    if (g_frtSolOldMapAddr)
+        g_rtSolMapAddr.u.pfnSol_map_addr_old(pVirtAddr, cb, 0 /* offset */, 0 /* vacalign */, MAP_SHARED);
+    else
+        g_rtSolMapAddr.u.pfnSol_map_addr(pVirtAddr, cb, 0 /* offset */, MAP_SHARED);
+    if (*pVirtAddr != NULL)
+        rc = as_map(pAddrSpace, *pVirtAddr, cb, rtR0SegVBoxSolCreate, &Args);
+    else
+        rc = ENOMEM;
+    as_rangeunlock(pAddrSpace);
+
+    return RTErrConvertFromErrno(rc);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeFree(RTR0MEMOBJ pMem)
+{
+    PRTR0MEMOBJSOL pMemSolaris = (PRTR0MEMOBJSOL)pMem;
+
+    switch (pMemSolaris->Core.enmType)
+    {
+        case RTR0MEMOBJTYPE_LOW:
+            rtR0SolMemFree(pMemSolaris->Core.pv, pMemSolaris->Core.cb);
+            break;
+
+        case RTR0MEMOBJTYPE_PHYS:
+            if (pMemSolaris->Core.u.Phys.fAllocated)
+            {
+                if (pMemSolaris->fLargePage)
+                    rtR0MemObjSolLargePageFree(pMemSolaris->pvHandle, pMemSolaris->Core.cb);
+                else
+                    rtR0SolMemFree(pMemSolaris->Core.pv, pMemSolaris->Core.cb);
+            }
+            break;
+
+        case RTR0MEMOBJTYPE_PHYS_NC:
+            if (pMemSolaris->fIndivPages)
+                rtR0MemObjSolPagesFree(pMemSolaris->pvHandle, pMemSolaris->Core.cb);
+            else
+                rtR0SolMemFree(pMemSolaris->Core.pv, pMemSolaris->Core.cb);
+            break;
+
+        case RTR0MEMOBJTYPE_PAGE:
+            ddi_umem_free(pMemSolaris->Cookie);
+            break;
+
+        case RTR0MEMOBJTYPE_LOCK:
+            rtR0MemObjSolUnlock(pMemSolaris->Core.pv, pMemSolaris->Core.cb, pMemSolaris->fAccess);
+            break;
+
+        case RTR0MEMOBJTYPE_MAPPING:
+            rtR0MemObjSolUnmap(pMemSolaris->Core.pv, pMemSolaris->Core.cb);
+            break;
+
+        case RTR0MEMOBJTYPE_RES_VIRT:
+        {
+            if (pMemSolaris->Core.u.ResVirt.R0Process == NIL_RTR0PROCESS)
+                vmem_xfree(heap_arena, pMemSolaris->Core.pv, pMemSolaris->Core.cb);
+            else
+                AssertFailed();
+            break;
+        }
+
+        case RTR0MEMOBJTYPE_CONT: /* we don't use this type here. */
+        default:
+            AssertMsgFailed(("enmType=%d\n", pMemSolaris->Core.enmType));
+            return VERR_INTERNAL_ERROR;
+    }
+
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocPage(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    /* Create the object. */
+    PRTR0MEMOBJSOL pMemSolaris = (PRTR0MEMOBJSOL)rtR0MemObjNew(sizeof(*pMemSolaris), RTR0MEMOBJTYPE_PAGE, NULL, cb);
+    if (RT_UNLIKELY(!pMemSolaris))
+        return VERR_NO_MEMORY;
+
+    void *pvMem = ddi_umem_alloc(cb, DDI_UMEM_SLEEP, &pMemSolaris->Cookie);
+    if (RT_UNLIKELY(!pvMem))
+    {
+        rtR0MemObjDelete(&pMemSolaris->Core);
+        return VERR_NO_PAGE_MEMORY;
+    }
+
+    pMemSolaris->Core.pv  = pvMem;
+    pMemSolaris->pvHandle = NULL;
+    *ppMem = &pMemSolaris->Core;
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocLow(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    NOREF(fExecutable);
+
+    /* Create the object */
+    PRTR0MEMOBJSOL pMemSolaris = (PRTR0MEMOBJSOL)rtR0MemObjNew(sizeof(*pMemSolaris), RTR0MEMOBJTYPE_LOW, NULL, cb);
+    if (!pMemSolaris)
+        return VERR_NO_MEMORY;
+
+    /* Allocate physically low page-aligned memory. */
+    uint64_t uPhysHi = _4G - 1;
+    void *pvMem = rtR0SolMemAlloc(uPhysHi, NULL /* puPhys */, cb, PAGE_SIZE, false /* fContig */);
+    if (RT_UNLIKELY(!pvMem))
+    {
+        rtR0MemObjDelete(&pMemSolaris->Core);
+        return VERR_NO_LOW_MEMORY;
+    }
+    pMemSolaris->Core.pv = pvMem;
+    pMemSolaris->pvHandle = NULL;
+    *ppMem = &pMemSolaris->Core;
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocCont(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable)
+{
+    NOREF(fExecutable);
+    return rtR0MemObjNativeAllocPhys(ppMem, cb, _4G - 1, PAGE_SIZE /* alignment */);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocPhysNC(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, RTHCPHYS PhysHighest)
+{
+#if HC_ARCH_BITS == 64
+    PRTR0MEMOBJSOL pMemSolaris = (PRTR0MEMOBJSOL)rtR0MemObjNew(sizeof(*pMemSolaris), RTR0MEMOBJTYPE_PHYS_NC, NULL, cb);
+    if (RT_UNLIKELY(!pMemSolaris))
+        return VERR_NO_MEMORY;
+
+    if (PhysHighest == NIL_RTHCPHYS)
+    {
+        uint64_t PhysAddr = UINT64_MAX;
+        void *pvPages = rtR0MemObjSolPagesAlloc(&PhysAddr, cb);
+        if (!pvPages)
+        {
+            LogRel(("rtR0MemObjNativeAllocPhysNC: rtR0MemObjSolPagesAlloc failed for cb=%u.\n", cb));
+            rtR0MemObjDelete(&pMemSolaris->Core);
+            return VERR_NO_MEMORY;
+        }
+        Assert(PhysAddr != UINT64_MAX);
+        Assert(!(PhysAddr & PAGE_OFFSET_MASK));
+
+        pMemSolaris->Core.pv     = NULL;
+        pMemSolaris->pvHandle    = pvPages;
+        pMemSolaris->fIndivPages = true;
+        *ppMem = &pMemSolaris->Core;
+        return VINF_SUCCESS;
+    }
+    else
+    {
+        /*
+         * If we must satisfy an upper limit constraint, it isn't feasible to grab individual pages.
+         * We fall back to using contig_alloc().
+         */
+        uint64_t PhysAddr = UINT64_MAX;
+        void *pvMem = rtR0SolMemAlloc(PhysHighest, &PhysAddr, cb, PAGE_SIZE, false /* fContig */);
+        if (!pvMem)
+        {
+            LogRel(("rtR0MemObjNativeAllocPhysNC: rtR0SolMemAlloc failed for cb=%u PhysHighest=%RHp.\n", cb, PhysHighest));
+            rtR0MemObjDelete(&pMemSolaris->Core);
+            return VERR_NO_MEMORY;
+        }
+        Assert(PhysAddr != UINT64_MAX);
+        Assert(!(PhysAddr & PAGE_OFFSET_MASK));
+
+        pMemSolaris->Core.pv     = pvMem;
+        pMemSolaris->pvHandle    = NULL;
+        pMemSolaris->fIndivPages = false;
+        *ppMem = &pMemSolaris->Core;
+        return VINF_SUCCESS;
+    }
+
+#else /* 32 bit: */
+    return VERR_NOT_SUPPORTED; /* see the RTR0MemObjAllocPhysNC specs */
+#endif
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocPhys(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, RTHCPHYS PhysHighest, size_t uAlignment)
+{
+    AssertMsgReturn(PhysHighest >= 16 *_1M, ("PhysHigest=%RHp\n", PhysHighest), VERR_NOT_SUPPORTED);
+
+    PRTR0MEMOBJSOL pMemSolaris = (PRTR0MEMOBJSOL)rtR0MemObjNew(sizeof(*pMemSolaris), RTR0MEMOBJTYPE_PHYS, NULL, cb);
+    if (RT_UNLIKELY(!pMemSolaris))
+        return VERR_NO_MEMORY;
+
+    /*
+     * Allocating one large page gets special treatment.
+     */
+    static uint32_t s_cbLargePage = UINT32_MAX;
+    if (s_cbLargePage == UINT32_MAX)
+    {
+        if (page_num_pagesizes() > 1)
+            ASMAtomicWriteU32(&s_cbLargePage, page_get_pagesize(1)); /* Page-size code 1 maps to _2M on Solaris x86/amd64. */
+        else
+            ASMAtomicWriteU32(&s_cbLargePage, 0);
+    }
+
+    uint64_t PhysAddr;
+    if (   cb == s_cbLargePage
+        && cb == uAlignment
+        && PhysHighest == NIL_RTHCPHYS)
+    {
+        /*
+         * Allocate one large page (backed by physically contiguous memory).
+         */
+        void *pvPages = rtR0MemObjSolLargePageAlloc(&PhysAddr, cb);
+        if (RT_LIKELY(pvPages))
+        {
+            AssertMsg(!(PhysAddr & (cb - 1)), ("%RHp\n", PhysAddr));
+            pMemSolaris->Core.pv                = NULL;
+            pMemSolaris->Core.u.Phys.PhysBase   = PhysAddr;
+            pMemSolaris->Core.u.Phys.fAllocated = true;
+            pMemSolaris->pvHandle               = pvPages;
+            pMemSolaris->fLargePage             = true;
+
+            *ppMem = &pMemSolaris->Core;
+            return VINF_SUCCESS;
+        }
+    }
+    else
+    {
+        /*
+         * Allocate physically contiguous memory aligned as specified.
+         */
+        AssertCompile(NIL_RTHCPHYS == UINT64_MAX); NOREF(RTASSERTVAR);
+        PhysAddr = PhysHighest;
+        void *pvMem = rtR0SolMemAlloc(PhysHighest, &PhysAddr, cb, uAlignment, true /* fContig */);
+        if (RT_LIKELY(pvMem))
+        {
+            Assert(!(PhysAddr & PAGE_OFFSET_MASK));
+            Assert(PhysAddr < PhysHighest);
+            Assert(PhysAddr + cb <= PhysHighest);
+
+            pMemSolaris->Core.pv                = pvMem;
+            pMemSolaris->Core.u.Phys.PhysBase   = PhysAddr;
+            pMemSolaris->Core.u.Phys.fAllocated = true;
+            pMemSolaris->pvHandle               = NULL;
+            pMemSolaris->fLargePage             = false;
+
+            *ppMem = &pMemSolaris->Core;
+            return VINF_SUCCESS;
+        }
+    }
+    rtR0MemObjDelete(&pMemSolaris->Core);
+    return VERR_NO_CONT_MEMORY;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeEnterPhys(PPRTR0MEMOBJINTERNAL ppMem, RTHCPHYS Phys, size_t cb, uint32_t uCachePolicy)
+{
+    AssertReturn(uCachePolicy == RTMEM_CACHE_POLICY_DONT_CARE, VERR_NOT_SUPPORTED);
+
+    /* Create the object. */
+    PRTR0MEMOBJSOL pMemSolaris = (PRTR0MEMOBJSOL)rtR0MemObjNew(sizeof(*pMemSolaris), RTR0MEMOBJTYPE_PHYS, NULL, cb);
+    if (!pMemSolaris)
+        return VERR_NO_MEMORY;
+
+    /* There is no allocation here, it needs to be mapped somewhere first. */
+    pMemSolaris->Core.u.Phys.fAllocated   = false;
+    pMemSolaris->Core.u.Phys.PhysBase     = Phys;
+    pMemSolaris->Core.u.Phys.uCachePolicy = uCachePolicy;
+    *ppMem = &pMemSolaris->Core;
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeLockUser(PPRTR0MEMOBJINTERNAL ppMem, RTR3PTR R3Ptr, size_t cb, uint32_t fAccess,
+                                         RTR0PROCESS R0Process)
+{
+    AssertReturn(R0Process == RTR0ProcHandleSelf(), VERR_INVALID_PARAMETER);
+    NOREF(fAccess);
+
+    /* Create the locking object */
+    PRTR0MEMOBJSOL pMemSolaris = (PRTR0MEMOBJSOL)rtR0MemObjNew(sizeof(*pMemSolaris), RTR0MEMOBJTYPE_LOCK, (void *)R3Ptr, cb);
+    if (!pMemSolaris)
+        return VERR_NO_MEMORY;
+
+    /* Lock down user pages. */
+    int fPageAccess = S_READ;
+    if (fAccess & RTMEM_PROT_WRITE)
+        fPageAccess = S_WRITE;
+    if (fAccess & RTMEM_PROT_EXEC)
+        fPageAccess = S_EXEC;
+    int rc = rtR0MemObjSolLock((void *)R3Ptr, cb, fPageAccess);
+    if (RT_FAILURE(rc))
+    {
+        LogRel(("rtR0MemObjNativeLockUser: rtR0MemObjSolLock failed rc=%d\n", rc));
+        rtR0MemObjDelete(&pMemSolaris->Core);
+        return rc;
+    }
+
+    /* Fill in the object attributes and return successfully. */
+    pMemSolaris->Core.u.Lock.R0Process  = R0Process;
+    pMemSolaris->pvHandle               = NULL;
+    pMemSolaris->fAccess                = fPageAccess;
+    *ppMem = &pMemSolaris->Core;
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeLockKernel(PPRTR0MEMOBJINTERNAL ppMem, void *pv, size_t cb, uint32_t fAccess)
+{
+    NOREF(fAccess);
+
+    PRTR0MEMOBJSOL pMemSolaris = (PRTR0MEMOBJSOL)rtR0MemObjNew(sizeof(*pMemSolaris), RTR0MEMOBJTYPE_LOCK, pv, cb);
+    if (!pMemSolaris)
+        return VERR_NO_MEMORY;
+
+    /* Lock down kernel pages. */
+    int fPageAccess = S_READ;
+    if (fAccess & RTMEM_PROT_WRITE)
+        fPageAccess = S_WRITE;
+    if (fAccess & RTMEM_PROT_EXEC)
+        fPageAccess = S_EXEC;
+    int rc = rtR0MemObjSolLock(pv, cb, fPageAccess);
+    if (RT_FAILURE(rc))
+    {
+        LogRel(("rtR0MemObjNativeLockKernel: rtR0MemObjSolLock failed rc=%d\n", rc));
+        rtR0MemObjDelete(&pMemSolaris->Core);
+        return rc;
+    }
+
+    /* Fill in the object attributes and return successfully. */
+    pMemSolaris->Core.u.Lock.R0Process = NIL_RTR0PROCESS;
+    pMemSolaris->pvHandle              = NULL;
+    pMemSolaris->fAccess               = fPageAccess;
+    *ppMem = &pMemSolaris->Core;
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeReserveKernel(PPRTR0MEMOBJINTERNAL ppMem, void *pvFixed, size_t cb, size_t uAlignment)
+{
+    PRTR0MEMOBJSOL  pMemSolaris;
+
+    /*
+     * Use xalloc.
+     */
+    void *pv = vmem_xalloc(heap_arena, cb, uAlignment, 0 /* phase */, 0 /* nocross */,
+                           NULL /* minaddr */, NULL /* maxaddr */, VM_SLEEP);
+    if (RT_UNLIKELY(!pv))
+        return VERR_NO_MEMORY;
+
+    /* Create the object. */
+    pMemSolaris = (PRTR0MEMOBJSOL)rtR0MemObjNew(sizeof(*pMemSolaris), RTR0MEMOBJTYPE_RES_VIRT, pv, cb);
+    if (!pMemSolaris)
+    {
+        LogRel(("rtR0MemObjNativeReserveKernel failed to alloc memory object.\n"));
+        vmem_xfree(heap_arena, pv, cb);
+        return VERR_NO_MEMORY;
+    }
+
+    pMemSolaris->Core.u.ResVirt.R0Process = NIL_RTR0PROCESS;
+    *ppMem = &pMemSolaris->Core;
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeReserveUser(PPRTR0MEMOBJINTERNAL ppMem, RTR3PTR R3PtrFixed, size_t cb, size_t uAlignment,
+                                            RTR0PROCESS R0Process)
+{
+    return VERR_NOT_SUPPORTED;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeMapKernel(PPRTR0MEMOBJINTERNAL ppMem, RTR0MEMOBJ pMemToMap, void *pvFixed, size_t uAlignment,
+                                          unsigned fProt, size_t offSub, size_t cbSub)
+{
+    /* Fail if requested to do something we can't. */
+    AssertMsgReturn(pvFixed == (void *)-1, ("%p\n", pvFixed), VERR_NOT_SUPPORTED);
+    if (uAlignment > PAGE_SIZE)
+        return VERR_NOT_SUPPORTED;
+
+    /*
+     * Use xalloc to get address space.
+     */
+    if (!cbSub)
+        cbSub = pMemToMap->cb;
+    void *pv = vmem_xalloc(heap_arena, cbSub, uAlignment, 0 /* phase */, 0 /* nocross */,
+                           NULL /* minaddr */, NULL /* maxaddr */, VM_SLEEP);
+    if (RT_UNLIKELY(!pv))
+        return VERR_MAP_FAILED;
+
+    /*
+     * Load the pages from the other object into it.
+     */
+    uint32_t fAttr  = HAT_UNORDERED_OK | HAT_MERGING_OK | HAT_LOADCACHING_OK | HAT_STORECACHING_OK;
+    if (fProt & RTMEM_PROT_READ)
+        fAttr |= PROT_READ;
+    if (fProt & RTMEM_PROT_EXEC)
+        fAttr |= PROT_EXEC;
+    if (fProt & RTMEM_PROT_WRITE)
+        fAttr |= PROT_WRITE;
+    fAttr |= HAT_NOSYNC;
+
+    int    rc  = VINF_SUCCESS;
+    size_t off = 0;
+    while (off < cbSub)
+    {
+        RTHCPHYS HCPhys = RTR0MemObjGetPagePhysAddr(pMemToMap, (offSub + off) >> PAGE_SHIFT);
+        AssertBreakStmt(HCPhys != NIL_RTHCPHYS, rc = VERR_INTERNAL_ERROR_2);
+        pfn_t pfn = HCPhys >> PAGE_SHIFT;
+        AssertBreakStmt(((RTHCPHYS)pfn << PAGE_SHIFT) == HCPhys, rc = VERR_INTERNAL_ERROR_3);
+
+        hat_devload(kas.a_hat, (uint8_t *)pv + off, PAGE_SIZE, pfn, fAttr, HAT_LOAD_LOCK);
+
+        /* Advance. */
+        off += PAGE_SIZE;
+    }
+    if (RT_SUCCESS(rc))
+    {
+        /*
+         * Create a memory object for the mapping.
+         */
+        PRTR0MEMOBJSOL pMemSolaris = (PRTR0MEMOBJSOL)rtR0MemObjNew(sizeof(*pMemSolaris), RTR0MEMOBJTYPE_MAPPING, pv, cbSub);
+        if (pMemSolaris)
+        {
+            pMemSolaris->Core.u.Mapping.R0Process = NIL_RTR0PROCESS;
+            *ppMem = &pMemSolaris->Core;
+            return VINF_SUCCESS;
+        }
+
+        LogRel(("rtR0MemObjNativeMapKernel failed to alloc memory object.\n"));
+        rc = VERR_NO_MEMORY;
+    }
+
+    if (off)
+        hat_unload(kas.a_hat, pv, off, HAT_UNLOAD | HAT_UNLOAD_UNLOCK);
+    vmem_xfree(heap_arena, pv, cbSub);
+    return rc;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeMapUser(PPRTR0MEMOBJINTERNAL ppMem, PRTR0MEMOBJINTERNAL pMemToMap, RTR3PTR R3PtrFixed,
+                                        size_t uAlignment, unsigned fProt, RTR0PROCESS R0Process, size_t offSub, size_t cbSub)
+{
+    /*
+     * Fend off things we cannot do.
+     */
+    AssertMsgReturn(R3PtrFixed == (RTR3PTR)-1, ("%p\n", R3PtrFixed), VERR_NOT_SUPPORTED);
+    AssertMsgReturn(R0Process == RTR0ProcHandleSelf(), ("%p != %p\n", R0Process, RTR0ProcHandleSelf()), VERR_NOT_SUPPORTED);
+    if (uAlignment != PAGE_SIZE)
+        return VERR_NOT_SUPPORTED;
+
+    /*
+     * Get parameters from the source object and offSub/cbSub.
+     */
+    PRTR0MEMOBJSOL  pMemToMapSolaris    = (PRTR0MEMOBJSOL)pMemToMap;
+    uint8_t        *pb                  = pMemToMapSolaris->Core.pv ? (uint8_t *)pMemToMapSolaris->Core.pv + offSub : NULL;
+    size_t const    cb                  = cbSub ? cbSub : pMemToMapSolaris->Core.cb;
+    size_t const    cPages              = cb >> PAGE_SHIFT;
+    Assert(!offSub || cbSub);
+    Assert(!(cb & PAGE_OFFSET_MASK));
+
+    /*
+     * Create the mapping object
+     */
+    PRTR0MEMOBJSOL pMemSolaris;
+    pMemSolaris = (PRTR0MEMOBJSOL)rtR0MemObjNew(sizeof(*pMemSolaris), RTR0MEMOBJTYPE_MAPPING, pb, cb);
+    if (RT_UNLIKELY(!pMemSolaris))
+        return VERR_NO_MEMORY;
+
+    /*
+     * Gather the physical page address of the pages to be mapped.
+     */
+    int rc = VINF_SUCCESS;
+    uint64_t *paPhysAddrs = kmem_zalloc(sizeof(uint64_t) * cPages, KM_SLEEP);
+    if (RT_LIKELY(paPhysAddrs))
+    {
+        if (   pMemToMapSolaris->Core.enmType == RTR0MEMOBJTYPE_PHYS_NC
+            && pMemToMapSolaris->fIndivPages)
+        {
+            /* Translate individual page_t to physical addresses. */
+            page_t **papPages = pMemToMapSolaris->pvHandle;
+            AssertPtr(papPages);
+            papPages += offSub >> PAGE_SHIFT;
+            for (size_t iPage = 0; iPage < cPages; iPage++)
+                paPhysAddrs[iPage] = rtR0MemObjSolPagePhys(papPages[iPage]);
+        }
+        else if (   pMemToMapSolaris->Core.enmType == RTR0MEMOBJTYPE_PHYS
+                 && pMemToMapSolaris->fLargePage)
+        {
+            /* Split up the large page into page-sized chunks. */
+            RTHCPHYS Phys = pMemToMapSolaris->Core.u.Phys.PhysBase;
+            Phys += offSub;
+            for (size_t iPage = 0; iPage < cPages; iPage++, Phys += PAGE_SIZE)
+                paPhysAddrs[iPage] = Phys;
+        }
+        else
+        {
+            /* Have kernel mapping, just translate virtual to physical. */
+            AssertPtr(pb);
+            for (size_t iPage = 0; iPage < cPages; iPage++)
+            {
+                paPhysAddrs[iPage] = rtR0MemObjSolVirtToPhys(pb);
+                if (RT_UNLIKELY(paPhysAddrs[iPage] == -(uint64_t)1))
+                {
+                    LogRel(("rtR0MemObjNativeMapUser: no page to map.\n"));
+                    rc = VERR_MAP_FAILED;
+                    break;
+                }
+                pb += PAGE_SIZE;
+            }
+        }
+        if (RT_SUCCESS(rc))
+        {
+            /*
+             * Perform the actual mapping.
+             */
+            unsigned fPageAccess = PROT_READ;
+            if (fProt & RTMEM_PROT_WRITE)
+                fPageAccess |= PROT_WRITE;
+            if (fProt & RTMEM_PROT_EXEC)
+                fPageAccess |= PROT_EXEC;
+
+            caddr_t UserAddr = NULL;
+            rc = rtR0MemObjSolUserMap(&UserAddr, fPageAccess, paPhysAddrs, cb, PAGE_SIZE);
+            if (RT_SUCCESS(rc))
+            {
+                pMemSolaris->Core.u.Mapping.R0Process = R0Process;
+                pMemSolaris->Core.pv                  = UserAddr;
+
+                *ppMem = &pMemSolaris->Core;
+                kmem_free(paPhysAddrs, sizeof(uint64_t) * cPages);
+                return VINF_SUCCESS;
+            }
+
+            LogRel(("rtR0MemObjNativeMapUser: rtR0MemObjSolUserMap failed rc=%d.\n", rc));
+        }
+
+        rc = VERR_MAP_FAILED;
+        kmem_free(paPhysAddrs, sizeof(uint64_t) * cPages);
+    }
+    else
+        rc = VERR_NO_MEMORY;
+    rtR0MemObjDelete(&pMemSolaris->Core);
+    return rc;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeProtect(PRTR0MEMOBJINTERNAL pMem, size_t offSub, size_t cbSub, uint32_t fProt)
+{
+    NOREF(pMem);
+    NOREF(offSub);
+    NOREF(cbSub);
+    NOREF(fProt);
+    return VERR_NOT_SUPPORTED;
+}
+
+
+DECLHIDDEN(RTHCPHYS) rtR0MemObjNativeGetPagePhysAddr(PRTR0MEMOBJINTERNAL pMem, size_t iPage)
+{
+    PRTR0MEMOBJSOL pMemSolaris = (PRTR0MEMOBJSOL)pMem;
+
+    switch (pMemSolaris->Core.enmType)
+    {
+        case RTR0MEMOBJTYPE_PHYS_NC:
+            if (   pMemSolaris->Core.u.Phys.fAllocated
+                || !pMemSolaris->fIndivPages)
+            {
+                uint8_t *pb = (uint8_t *)pMemSolaris->Core.pv + ((size_t)iPage << PAGE_SHIFT);
+                return rtR0MemObjSolVirtToPhys(pb);
+            }
+            page_t **ppPages = pMemSolaris->pvHandle;
+            return rtR0MemObjSolPagePhys(ppPages[iPage]);
+
+        case RTR0MEMOBJTYPE_PAGE:
+        case RTR0MEMOBJTYPE_LOW:
+        case RTR0MEMOBJTYPE_LOCK:
+        {
+            uint8_t *pb = (uint8_t *)pMemSolaris->Core.pv + ((size_t)iPage << PAGE_SHIFT);
+            return rtR0MemObjSolVirtToPhys(pb);
+        }
+
+        /*
+         * Although mapping can be handled by rtR0MemObjSolVirtToPhys(offset) like the above case,
+         * request it from the parent so that we have a clear distinction between CONT/PHYS_NC.
+         */
+        case RTR0MEMOBJTYPE_MAPPING:
+            return rtR0MemObjNativeGetPagePhysAddr(pMemSolaris->Core.uRel.Child.pParent, iPage);
+
+        case RTR0MEMOBJTYPE_CONT:
+        case RTR0MEMOBJTYPE_PHYS:
+            AssertFailed(); /* handled by the caller */
+        case RTR0MEMOBJTYPE_RES_VIRT:
+        default:
+            return NIL_RTHCPHYS;
+    }
+}
+
diff --git a/src/VBox/Runtime/r0drv/solaris/memobj-r0drv-solaris.h b/src/VBox/Runtime/r0drv/solaris/memobj-r0drv-solaris.h
new file mode 100644
index 00000000..5e8116cf
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/memobj-r0drv-solaris.h
@@ -0,0 +1,322 @@
+/* $Id: memobj-r0drv-solaris.h $ */
+/** @file
+ * IPRT - Ring-0 Memory Objects - Segment driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2012-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+#ifndef IPRT_INCLUDED_SRC_r0drv_solaris_memobj_r0drv_solaris_h
+#define IPRT_INCLUDED_SRC_r0drv_solaris_memobj_r0drv_solaris_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+/*******************************************************************************
+*   Header Files                                                               *
+*******************************************************************************/
+#include "the-solaris-kernel.h"
+
+
+/*******************************************************************************
+*   Structures and Typedefs                                                    *
+*******************************************************************************/
+typedef struct SEGVBOX_CRARGS
+{
+    uint64_t *paPhysAddrs;
+    size_t    cbPageSize;
+    uint_t    fPageAccess;
+} SEGVBOX_CRARGS;
+typedef SEGVBOX_CRARGS *PSEGVBOX_CRARGS;
+
+typedef struct SEGVBOX_DATA
+{
+    uint_t    fPageAccess;
+    size_t    cbPageSize;
+} SEGVBOX_DATA;
+typedef SEGVBOX_DATA *PSEGVBOX_DATA;
+
+static struct seg_ops s_SegVBoxOps;
+static vnode_t s_segVBoxVnode;
+
+
+DECLINLINE(int) rtR0SegVBoxSolCreate(seg_t *pSeg, void *pvArgs)
+{
+    struct as      *pAddrSpace = pSeg->s_as;
+    PSEGVBOX_CRARGS pArgs      = pvArgs;
+    PSEGVBOX_DATA   pData      = kmem_zalloc(sizeof(*pData), KM_SLEEP);
+
+    AssertPtr(pAddrSpace);
+    AssertPtr(pArgs);
+    AssertPtr(pData);
+
+    /*
+     * Currently we only map _4K pages but this segment driver can handle any size
+     * supported by the Solaris HAT layer.
+     */
+    size_t cbPageSize  = pArgs->cbPageSize;
+    size_t uPageShift  = 0;
+    switch (cbPageSize)
+    {
+        case _4K: uPageShift = 12; break;
+        case _2M: uPageShift = 21; break;
+        default:  AssertReleaseMsgFailed(("Unsupported page size for mapping cbPageSize=%llx\n", cbPageSize)); break;
+    }
+
+    hat_map(pAddrSpace->a_hat, pSeg->s_base, pSeg->s_size, HAT_MAP);
+    pData->fPageAccess = pArgs->fPageAccess | PROT_USER;
+    pData->cbPageSize  = cbPageSize;
+
+    pSeg->s_ops  = &s_SegVBoxOps;
+    pSeg->s_data = pData;
+
+    /*
+     * Now load and lock down the mappings to the physical addresses.
+     */
+    caddr_t virtAddr = pSeg->s_base;
+    pgcnt_t cPages   = (pSeg->s_size + cbPageSize - 1) >> uPageShift;
+    for (pgcnt_t iPage = 0; iPage < cPages; ++iPage, virtAddr += cbPageSize)
+    {
+        hat_devload(pAddrSpace->a_hat, virtAddr, cbPageSize, pArgs->paPhysAddrs[iPage] >> uPageShift,
+                    pData->fPageAccess | HAT_UNORDERED_OK, HAT_LOAD_LOCK);
+    }
+
+    return 0;
+}
+
+
+static int rtR0SegVBoxSolDup(seg_t *pSrcSeg, seg_t *pDstSeg)
+{
+    /*
+     * Duplicate a segment and return the new segment in 'pDstSeg'.
+     */
+    PSEGVBOX_DATA pSrcData = pSrcSeg->s_data;
+    PSEGVBOX_DATA pDstData = kmem_zalloc(sizeof(*pDstData), KM_SLEEP);
+
+    AssertPtr(pDstData);
+    AssertPtr(pSrcData);
+
+    pDstData->fPageAccess  = pSrcData->fPageAccess;
+    pDstData->cbPageSize   = pSrcData->cbPageSize;
+    pDstSeg->s_ops         = &s_SegVBoxOps;
+    pDstSeg->s_data        = pDstData;
+
+    return 0;
+}
+
+
+static int rtR0SegVBoxSolUnmap(seg_t *pSeg, caddr_t virtAddr, size_t cb)
+{
+    PSEGVBOX_DATA pData = pSeg->s_data;
+
+    AssertRelease(pData);
+    AssertReleaseMsg(virtAddr >= pSeg->s_base, ("virtAddr=%p s_base=%p\n", virtAddr, pSeg->s_base));
+    AssertReleaseMsg(virtAddr + cb <= pSeg->s_base + pSeg->s_size, ("virtAddr=%p cb=%llu s_base=%p s_size=%llu\n", virtAddr,
+                                                                    cb, pSeg->s_base, pSeg->s_size));
+    size_t cbPageOffset = pData->cbPageSize - 1;
+    AssertRelease(!(cb & cbPageOffset));
+    AssertRelease(!((uintptr_t)virtAddr & cbPageOffset));
+
+    if (   virtAddr != pSeg->s_base
+        || cb       != pSeg->s_size)
+    {
+        return ENOTSUP;
+    }
+
+    hat_unload(pSeg->s_as->a_hat, virtAddr, cb, HAT_UNLOAD_UNMAP | HAT_UNLOAD_UNLOCK);
+
+    seg_free(pSeg);
+    return 0;
+}
+
+
+static void rtR0SegVBoxSolFree(seg_t *pSeg)
+{
+    PSEGVBOX_DATA pData = pSeg->s_data;
+    kmem_free(pData, sizeof(*pData));
+}
+
+
+static int rtR0SegVBoxSolFault(struct hat *pHat, seg_t *pSeg, caddr_t virtAddr, size_t cb, enum fault_type FaultType,
+                               enum seg_rw ReadWrite)
+{
+    /*
+     * We would demand fault if the (u)read() path would SEGOP_FAULT() on buffers mapped in via our
+     * segment driver i.e. prefaults before DMA. Don't fail in such case where we're called directly,
+     * see @bugref{5047}.
+     */
+    return 0;
+}
+
+
+static int rtR0SegVBoxSolFaultA(seg_t *pSeg, caddr_t virtAddr)
+{
+    return 0;
+}
+
+
+static int rtR0SegVBoxSolSetProt(seg_t *pSeg, caddr_t virtAddr, size_t cb, uint_t fPageAccess)
+{
+    return EACCES;
+}
+
+
+static int rtR0SegVBoxSolCheckProt(seg_t *pSeg, caddr_t virtAddr, size_t cb, uint_t fPageAccess)
+{
+    return EINVAL;
+}
+
+
+static int rtR0SegVBoxSolKluster(seg_t *pSeg, caddr_t virtAddr, ssize_t Delta)
+{
+    return -1;
+}
+
+
+static int rtR0SegVBoxSolSync(seg_t *pSeg, caddr_t virtAddr, size_t cb, int Attr, uint_t fFlags)
+{
+    return 0;
+}
+
+
+static size_t rtR0SegVBoxSolInCore(seg_t *pSeg, caddr_t virtAddr, size_t cb, char *pVec)
+{
+    PSEGVBOX_DATA pData = pSeg->s_data;
+    AssertRelease(pData);
+    size_t uPageOffset  = pData->cbPageSize - 1;
+    size_t uPageMask    = ~uPageOffset;
+    size_t cbLen        = (cb + uPageOffset) & uPageMask;
+    for (virtAddr = 0; cbLen != 0; cbLen -= pData->cbPageSize, virtAddr += pData->cbPageSize)
+        *pVec++ = 1;
+    return cbLen;
+}
+
+
+static int rtR0SegVBoxSolLockOp(seg_t *pSeg, caddr_t virtAddr, size_t cb, int Attr, int Op, ulong_t *pLockMap, size_t off)
+{
+    return 0;
+}
+
+
+static int rtR0SegVBoxSolGetProt(seg_t *pSeg, caddr_t virtAddr, size_t cb, uint_t *pafPageAccess)
+{
+    PSEGVBOX_DATA pData = pSeg->s_data;
+    size_t iPage = seg_page(pSeg, virtAddr + cb) - seg_page(pSeg, virtAddr) + 1;
+    if (iPage)
+    {
+        do
+        {
+            iPage--;
+            pafPageAccess[iPage] = pData->fPageAccess;
+        } while (iPage);
+    }
+    return 0;
+}
+
+
+static u_offset_t rtR0SegVBoxSolGetOffset(seg_t *pSeg, caddr_t virtAddr)
+{
+    return ((uintptr_t)virtAddr - (uintptr_t)pSeg->s_base);
+}
+
+
+static int rtR0SegVBoxSolGetType(seg_t *pSeg, caddr_t virtAddr)
+{
+    return MAP_SHARED;
+}
+
+
+static int rtR0SegVBoxSolGetVp(seg_t *pSeg, caddr_t virtAddr, vnode_t **ppVnode)
+{
+    *ppVnode = &s_segVBoxVnode;
+    return 0;
+}
+
+
+static int rtR0SegVBoxSolAdvise(seg_t *pSeg, caddr_t virtAddr, size_t cb, uint_t Behav /* wut? */)
+{
+    return 0;
+}
+
+
+#if defined(VBOX_NEW_CRASH_DUMP_FORMAT)
+static void rtR0SegVBoxSolDump(seg_t *pSeg, dump_addpage_f Func)
+#else
+static void rtR0SegVBoxSolDump(seg_t *pSeg)
+#endif
+{
+    /* Nothing to do. */
+}
+
+
+static int rtR0SegVBoxSolPageLock(seg_t *pSeg, caddr_t virtAddr, size_t cb, page_t ***pppPage, enum lock_type LockType, enum seg_rw ReadWrite)
+{
+    return ENOTSUP;
+}
+
+
+static int rtR0SegVBoxSolSetPageSize(seg_t *pSeg, caddr_t virtAddr, size_t cb, uint_t SizeCode)
+{
+    return ENOTSUP;
+}
+
+
+static int rtR0SegVBoxSolGetMemId(seg_t *pSeg, caddr_t virtAddr, memid_t *pMemId)
+{
+    return ENODEV;
+}
+
+
+static int rtR0SegVBoxSolCapable(seg_t *pSeg, segcapability_t Capab)
+{
+    return 0;
+}
+
+
+static struct seg_ops s_SegVBoxOps =
+{
+    rtR0SegVBoxSolDup,
+    rtR0SegVBoxSolUnmap,
+    rtR0SegVBoxSolFree,
+    rtR0SegVBoxSolFault,
+    rtR0SegVBoxSolFaultA,
+    rtR0SegVBoxSolSetProt,
+    rtR0SegVBoxSolCheckProt,
+    rtR0SegVBoxSolKluster,
+    NULL,                       /* swapout */
+    rtR0SegVBoxSolSync,
+    rtR0SegVBoxSolInCore,
+    rtR0SegVBoxSolLockOp,
+    rtR0SegVBoxSolGetProt,
+    rtR0SegVBoxSolGetOffset,
+    rtR0SegVBoxSolGetType,
+    rtR0SegVBoxSolGetVp,
+    rtR0SegVBoxSolAdvise,
+    rtR0SegVBoxSolDump,
+    rtR0SegVBoxSolPageLock,
+    rtR0SegVBoxSolSetPageSize,
+    rtR0SegVBoxSolGetMemId,
+    NULL,                       /* getpolicy() */
+    rtR0SegVBoxSolCapable
+};
+
+#endif /* !IPRT_INCLUDED_SRC_r0drv_solaris_memobj_r0drv_solaris_h */
+
diff --git a/src/VBox/Runtime/r0drv/solaris/memuserkernel-r0drv-solaris.c b/src/VBox/Runtime/r0drv/solaris/memuserkernel-r0drv-solaris.c
new file mode 100644
index 00000000..9d6ff068
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/memuserkernel-r0drv-solaris.c
@@ -0,0 +1,100 @@
+/* $Id: memuserkernel-r0drv-solaris.c $ */
+/** @file
+ * IPRT - User & Kernel Memory, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2009-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-solaris-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/mem.h>
+
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+
+
+RTR0DECL(int) RTR0MemUserCopyFrom(void *pvDst, RTR3PTR R3PtrSrc, size_t cb)
+{
+    int rc;
+    RT_ASSERT_INTS_ON();
+
+    rc = ddi_copyin((const char *)R3PtrSrc, pvDst, cb, 0 /*flags*/);
+    if (RT_LIKELY(rc == 0))
+        return VINF_SUCCESS;
+    return VERR_ACCESS_DENIED;
+}
+
+
+RTR0DECL(int) RTR0MemUserCopyTo(RTR3PTR R3PtrDst, void const *pvSrc, size_t cb)
+{
+    int rc;
+    RT_ASSERT_INTS_ON();
+
+    rc = ddi_copyout(pvSrc, (void *)R3PtrDst, cb, 0 /*flags*/);
+    if (RT_LIKELY(rc == 0))
+        return VINF_SUCCESS;
+    return VERR_ACCESS_DENIED;
+}
+
+
+RTR0DECL(bool) RTR0MemUserIsValidAddr(RTR3PTR R3Ptr)
+{
+    return R3Ptr < kernelbase;
+}
+
+
+RTR0DECL(bool) RTR0MemKernelIsValidAddr(void *pv)
+{
+    return (uintptr_t)pv >= kernelbase;
+}
+
+
+RTR0DECL(bool) RTR0MemAreKrnlAndUsrDifferent(void)
+{
+    return true;
+}
+
+
+RTR0DECL(int) RTR0MemKernelCopyFrom(void *pvDst, void const *pvSrc, size_t cb)
+{
+    int rc = kcopy(pvSrc, pvDst, cb);
+    if (RT_LIKELY(rc == 0))
+        return VINF_SUCCESS;
+    return VERR_ACCESS_DENIED;
+}
+
+
+RTR0DECL(int) RTR0MemKernelCopyTo(void *pvDst, void const *pvSrc, size_t cb)
+{
+    int rc = kcopy(pvSrc, pvDst, cb);
+    if (RT_LIKELY(rc == 0))
+        return VINF_SUCCESS;
+    return VERR_ACCESS_DENIED;
+}
+
diff --git a/src/VBox/Runtime/r0drv/solaris/modulestub-r0drv-solaris.c b/src/VBox/Runtime/r0drv/solaris/modulestub-r0drv-solaris.c
new file mode 100644
index 00000000..5b5792c8
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/modulestub-r0drv-solaris.c
@@ -0,0 +1,79 @@
+/* $Id: modulestub-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Ring-0 Solaris stubs
+ */
+
+/*
+ * Copyright (C) 2011-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <sys/modctl.h>
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+static struct modlmisc g_rtModuleStubMisc =
+{
+    &mod_miscops,           /* extern from kernel */
+    "platform agnostic module"
+};
+
+
+static struct modlinkage g_rtModuleStubModLinkage =
+{
+    MODREV_1,   /* loadable module system revision */
+    {
+        &g_rtModuleStubMisc,
+        NULL    /* terminate array of linkage structures */
+    }
+};
+
+
+
+int _init(void);
+int _init(void)
+{
+    /* Disable auto unloading. */
+    modctl_t *pModCtl = mod_getctl(&g_rtModuleStubModLinkage);
+    if (pModCtl)
+        pModCtl->mod_loadflags |= MOD_NOAUTOUNLOAD;
+
+    return mod_install(&g_rtModuleStubModLinkage);
+}
+
+
+int _fini(void);
+int _fini(void)
+{
+    return mod_remove(&g_rtModuleStubModLinkage);
+}
+
+
+int _info(struct modinfo *pModInfo);
+int _info(struct modinfo *pModInfo)
+{
+    return mod_info(&g_rtModuleStubModLinkage, pModInfo);
+}
+
diff --git a/src/VBox/Runtime/r0drv/solaris/mp-r0drv-solaris.c b/src/VBox/Runtime/r0drv/solaris/mp-r0drv-solaris.c
new file mode 100644
index 00000000..f0485ec7
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/mp-r0drv-solaris.c
@@ -0,0 +1,450 @@
+/* $Id: mp-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Multiprocessor, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2008-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-solaris-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/mp.h>
+#include <iprt/cpuset.h>
+#include <iprt/thread.h>
+
+#include <iprt/asm.h>
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/err.h>
+#include "r0drv/mp-r0drv.h"
+
+typedef int FNRTMPSOLWORKER(void *pvUser1, void *pvUser2, void *pvUser3);
+typedef FNRTMPSOLWORKER *PFNRTMPSOLWORKER;
+
+
+RTDECL(bool) RTMpIsCpuWorkPending(void)
+{
+    return false;
+}
+
+
+RTDECL(RTCPUID) RTMpCpuId(void)
+{
+    return CPU->cpu_id;
+}
+
+
+RTDECL(int) RTMpCurSetIndex(void)
+{
+    return CPU->cpu_id;
+}
+
+
+RTDECL(int) RTMpCurSetIndexAndId(PRTCPUID pidCpu)
+{
+    return *pidCpu = CPU->cpu_id;
+}
+
+
+RTDECL(int) RTMpCpuIdToSetIndex(RTCPUID idCpu)
+{
+    return idCpu < RTCPUSET_MAX_CPUS && idCpu <= max_cpuid ? idCpu : -1;
+}
+
+
+RTDECL(RTCPUID) RTMpCpuIdFromSetIndex(int iCpu)
+{
+    return (unsigned)iCpu <= max_cpuid ? iCpu : NIL_RTCPUID;
+}
+
+
+RTDECL(RTCPUID) RTMpGetMaxCpuId(void)
+{
+    return max_cpuid;
+}
+
+
+RTDECL(bool) RTMpIsCpuOnline(RTCPUID idCpu)
+{
+    /*
+     * We cannot query CPU status recursively, check cpu member from cached set.
+     */
+    if (idCpu >= ncpus)
+        return false;
+
+    return RTCpuSetIsMember(&g_rtMpSolCpuSet, idCpu);
+}
+
+
+RTDECL(bool) RTMpIsCpuPossible(RTCPUID idCpu)
+{
+    return idCpu < ncpus;
+}
+
+
+RTDECL(PRTCPUSET) RTMpGetSet(PRTCPUSET pSet)
+{
+    RTCPUID idCpu;
+
+    RTCpuSetEmpty(pSet);
+    idCpu = RTMpGetMaxCpuId(); /* it's inclusive */
+    do
+    {
+        if (RTMpIsCpuPossible(idCpu))
+            RTCpuSetAdd(pSet, idCpu);
+    } while (idCpu-- > 0);
+
+    return pSet;
+}
+
+
+RTDECL(RTCPUID) RTMpGetCount(void)
+{
+    return ncpus;
+}
+
+
+RTDECL(PRTCPUSET) RTMpGetOnlineSet(PRTCPUSET pSet)
+{
+    /*
+     * We cannot query CPU status recursively, return the cached set.
+     */
+    *pSet = g_rtMpSolCpuSet;
+    return pSet;
+}
+
+
+RTDECL(RTCPUID) RTMpGetOnlineCount(void)
+{
+    RTCPUSET Set;
+    RTMpGetOnlineSet(&Set);
+    return RTCpuSetCount(&Set);
+}
+
+
+/**
+ * Wrapper to Solaris IPI infrastructure.
+ *
+ * @returns Solaris error code.
+ * @param   pCpuSet        Pointer to Solaris CPU set.
+ * @param   pfnSolWorker   Function to execute on target CPU(s).
+ * @param   pArgs          Pointer to RTMPARGS to pass to @a pfnSolWorker.
+ */
+static void rtMpSolCrossCall(PRTSOLCPUSET pCpuSet, PFNRTMPSOLWORKER pfnSolWorker, PRTMPARGS pArgs)
+{
+    AssertPtrReturnVoid(pCpuSet);
+    AssertPtrReturnVoid(pfnSolWorker);
+    AssertPtrReturnVoid(pCpuSet);
+
+    if (g_frtSolOldIPI)
+    {
+        if (g_frtSolOldIPIUlong)
+        {
+            g_rtSolXcCall.u.pfnSol_xc_call_old_ulong((xc_arg_t)pArgs,          /* Arg to IPI function */
+                                                     0,                        /* Arg2, ignored */
+                                                     0,                        /* Arg3, ignored */
+                                                     IPRT_SOL_X_CALL_HIPRI,    /* IPI priority */
+                                                     pCpuSet->auCpus[0],       /* Target CPU(s) */
+                                                     (xc_func_t)pfnSolWorker); /* Function to execute on target(s) */
+        }
+        else
+        {
+            g_rtSolXcCall.u.pfnSol_xc_call_old((xc_arg_t)pArgs,          /* Arg to IPI function */
+                                               0,                        /* Arg2, ignored */
+                                               0,                        /* Arg3, ignored */
+                                               IPRT_SOL_X_CALL_HIPRI,    /* IPI priority */
+                                               *pCpuSet,                 /* Target CPU set */
+                                               (xc_func_t)pfnSolWorker); /* Function to execute on target(s) */
+        }
+    }
+    else
+    {
+        g_rtSolXcCall.u.pfnSol_xc_call((xc_arg_t)pArgs,          /* Arg to IPI function */
+                                       0,                        /* Arg2 */
+                                       0,                        /* Arg3 */
+                                       &pCpuSet->auCpus[0],      /* Target CPU set */
+                                       (xc_func_t)pfnSolWorker); /* Function to execute on target(s) */
+    }
+}
+
+
+/**
+ * Wrapper between the native solaris per-cpu callback and PFNRTWORKER
+ * for the RTMpOnAll API.
+ *
+ * @returns Solaris error code.
+ * @param   uArgs       Pointer to the RTMPARGS package.
+ * @param   pvIgnored1  Ignored.
+ * @param   pvIgnored2  Ignored.
+ */
+static int rtMpSolOnAllCpuWrapper(void *uArg, void *pvIgnored1, void *pvIgnored2)
+{
+    PRTMPARGS pArgs = (PRTMPARGS)(uArg);
+
+    /*
+     * Solaris CPU cross calls execute on offline CPUs too. Check our CPU cache
+     * set and ignore if it's offline.
+     */
+    if (!RTMpIsCpuOnline(RTMpCpuId()))
+        return 0;
+
+    pArgs->pfnWorker(RTMpCpuId(), pArgs->pvUser1, pArgs->pvUser2);
+
+    NOREF(pvIgnored1);
+    NOREF(pvIgnored2);
+    return 0;
+}
+
+
+RTDECL(int) RTMpOnAll(PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    RTMPARGS Args;
+    RTSOLCPUSET CpuSet;
+    RTTHREADPREEMPTSTATE PreemptState = RTTHREADPREEMPTSTATE_INITIALIZER;
+    RT_ASSERT_INTS_ON();
+
+    Args.pfnWorker = pfnWorker;
+    Args.pvUser1 = pvUser1;
+    Args.pvUser2 = pvUser2;
+    Args.idCpu = NIL_RTCPUID;
+    Args.cHits = 0;
+
+    for (int i = 0; i < IPRT_SOL_SET_WORDS; i++)
+        CpuSet.auCpus[i] = (ulong_t)-1L;
+
+    RTThreadPreemptDisable(&PreemptState);
+
+    rtMpSolCrossCall(&CpuSet, rtMpSolOnAllCpuWrapper, &Args);
+
+    RTThreadPreemptRestore(&PreemptState);
+
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Wrapper between the native solaris per-cpu callback and PFNRTWORKER
+ * for the RTMpOnOthers API.
+ *
+ * @returns Solaris error code.
+ * @param   uArgs       Pointer to the RTMPARGS package.
+ * @param   pvIgnored1  Ignored.
+ * @param   pvIgnored2  Ignored.
+ */
+static int rtMpSolOnOtherCpusWrapper(void *uArg, void *pvIgnored1, void *pvIgnored2)
+{
+    PRTMPARGS pArgs = (PRTMPARGS)(uArg);
+    RTCPUID idCpu = RTMpCpuId();
+
+    Assert(idCpu != pArgs->idCpu);
+    pArgs->pfnWorker(idCpu, pArgs->pvUser1, pArgs->pvUser2);
+
+    NOREF(pvIgnored1);
+    NOREF(pvIgnored2);
+    return 0;
+}
+
+
+RTDECL(int) RTMpOnOthers(PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    RTMPARGS Args;
+    RTSOLCPUSET CpuSet;
+    RTTHREADPREEMPTSTATE PreemptState = RTTHREADPREEMPTSTATE_INITIALIZER;
+    RT_ASSERT_INTS_ON();
+
+    Args.pfnWorker = pfnWorker;
+    Args.pvUser1 = pvUser1;
+    Args.pvUser2 = pvUser2;
+    Args.idCpu = RTMpCpuId();
+    Args.cHits = 0;
+
+    /* The caller is supposed to have disabled preemption, but take no chances. */
+    RTThreadPreemptDisable(&PreemptState);
+
+    for (int i = 0; i < IPRT_SOL_SET_WORDS; i++)
+        CpuSet.auCpus[0] = (ulong_t)-1L;
+    BT_CLEAR(CpuSet.auCpus, RTMpCpuId());
+
+    rtMpSolCrossCall(&CpuSet, rtMpSolOnOtherCpusWrapper, &Args);
+
+    RTThreadPreemptRestore(&PreemptState);
+
+    return VINF_SUCCESS;
+}
+
+
+
+/**
+ * Wrapper between the native solaris per-cpu callback and PFNRTWORKER
+ * for the RTMpOnPair API.
+ *
+ * @returns Solaris error code.
+ * @param   uArgs       Pointer to the RTMPARGS package.
+ * @param   pvIgnored1  Ignored.
+ * @param   pvIgnored2  Ignored.
+ */
+static int rtMpSolOnPairCpuWrapper(void *uArg, void *pvIgnored1, void *pvIgnored2)
+{
+    PRTMPARGS pArgs = (PRTMPARGS)(uArg);
+    RTCPUID idCpu = RTMpCpuId();
+
+    Assert(idCpu == pArgs->idCpu || idCpu == pArgs->idCpu2);
+    pArgs->pfnWorker(idCpu, pArgs->pvUser1, pArgs->pvUser2);
+    ASMAtomicIncU32(&pArgs->cHits);
+
+    NOREF(pvIgnored1);
+    NOREF(pvIgnored2);
+    return 0;
+}
+
+
+RTDECL(int) RTMpOnPair(RTCPUID idCpu1, RTCPUID idCpu2, uint32_t fFlags, PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    int rc;
+    RTMPARGS Args;
+    RTSOLCPUSET CpuSet;
+    RTTHREADPREEMPTSTATE PreemptState = RTTHREADPREEMPTSTATE_INITIALIZER;
+
+    AssertReturn(idCpu1 != idCpu2, VERR_INVALID_PARAMETER);
+    AssertReturn(!(fFlags & RTMPON_F_VALID_MASK), VERR_INVALID_FLAGS);
+
+    Args.pfnWorker = pfnWorker;
+    Args.pvUser1   = pvUser1;
+    Args.pvUser2   = pvUser2;
+    Args.idCpu     = idCpu1;
+    Args.idCpu2    = idCpu2;
+    Args.cHits     = 0;
+
+    for (int i = 0; i < IPRT_SOL_SET_WORDS; i++)
+        CpuSet.auCpus[i] = 0;
+    BT_SET(CpuSet.auCpus, idCpu1);
+    BT_SET(CpuSet.auCpus, idCpu2);
+
+    /*
+     * Check that both CPUs are online before doing the broadcast call.
+     */
+    RTThreadPreemptDisable(&PreemptState);
+    if (   RTMpIsCpuOnline(idCpu1)
+        && RTMpIsCpuOnline(idCpu2))
+    {
+        rtMpSolCrossCall(&CpuSet, rtMpSolOnPairCpuWrapper, &Args);
+
+        Assert(Args.cHits <= 2);
+        if (Args.cHits == 2)
+            rc = VINF_SUCCESS;
+        else if (Args.cHits == 1)
+            rc = VERR_NOT_ALL_CPUS_SHOWED;
+        else if (Args.cHits == 0)
+            rc = VERR_CPU_OFFLINE;
+        else
+            rc = VERR_CPU_IPE_1;
+    }
+    /*
+     * A CPU must be present to be considered just offline.
+     */
+    else if (   RTMpIsCpuPresent(idCpu1)
+             && RTMpIsCpuPresent(idCpu2))
+        rc = VERR_CPU_OFFLINE;
+    else
+        rc = VERR_CPU_NOT_FOUND;
+
+    RTThreadPreemptRestore(&PreemptState);
+    return rc;
+}
+
+
+RTDECL(bool) RTMpOnPairIsConcurrentExecSupported(void)
+{
+    return true;
+}
+
+
+/**
+ * Wrapper between the native solaris per-cpu callback and PFNRTWORKER
+ * for the RTMpOnSpecific API.
+ *
+ * @returns Solaris error code.
+ * @param   uArgs       Pointer to the RTMPARGS package.
+ * @param   pvIgnored1  Ignored.
+ * @param   pvIgnored2  Ignored.
+ */
+static int rtMpSolOnSpecificCpuWrapper(void *uArg, void *pvIgnored1, void *pvIgnored2)
+{
+    PRTMPARGS pArgs = (PRTMPARGS)(uArg);
+    RTCPUID idCpu = RTMpCpuId();
+
+    Assert(idCpu == pArgs->idCpu);
+    pArgs->pfnWorker(idCpu, pArgs->pvUser1, pArgs->pvUser2);
+    ASMAtomicIncU32(&pArgs->cHits);
+
+    NOREF(pvIgnored1);
+    NOREF(pvIgnored2);
+    return 0;
+}
+
+
+RTDECL(int) RTMpOnSpecific(RTCPUID idCpu, PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    RTMPARGS Args;
+    RTSOLCPUSET CpuSet;
+    RTTHREADPREEMPTSTATE PreemptState = RTTHREADPREEMPTSTATE_INITIALIZER;
+    RT_ASSERT_INTS_ON();
+
+    if (idCpu >= ncpus)
+        return VERR_CPU_NOT_FOUND;
+
+    if (RT_UNLIKELY(!RTMpIsCpuOnline(idCpu)))
+        return RTMpIsCpuPresent(idCpu) ? VERR_CPU_OFFLINE : VERR_CPU_NOT_FOUND;
+
+    Args.pfnWorker = pfnWorker;
+    Args.pvUser1 = pvUser1;
+    Args.pvUser2 = pvUser2;
+    Args.idCpu = idCpu;
+    Args.cHits = 0;
+
+    for (int i = 0; i < IPRT_SOL_SET_WORDS; i++)
+        CpuSet.auCpus[i] = 0;
+    BT_SET(CpuSet.auCpus, idCpu);
+
+    RTThreadPreemptDisable(&PreemptState);
+
+    rtMpSolCrossCall(&CpuSet, rtMpSolOnSpecificCpuWrapper, &Args);
+
+    RTThreadPreemptRestore(&PreemptState);
+
+    Assert(ASMAtomicUoReadU32(&Args.cHits) <= 1);
+
+    return ASMAtomicUoReadU32(&Args.cHits) == 1
+         ? VINF_SUCCESS
+         : VERR_CPU_NOT_FOUND;
+}
+
+
+RTDECL(bool) RTMpOnAllIsConcurrentSafe(void)
+{
+    return true;
+}
+
diff --git a/src/VBox/Runtime/r0drv/solaris/mpnotification-r0drv-solaris.c b/src/VBox/Runtime/r0drv/solaris/mpnotification-r0drv-solaris.c
new file mode 100644
index 00000000..1ba45d86
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/mpnotification-r0drv-solaris.c
@@ -0,0 +1,139 @@
+/* $Id: mpnotification-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Multiprocessor Event Notifications, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2008-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-solaris-kernel.h"
+#include "internal/iprt.h"
+
+#include <iprt/errcore.h>
+#include <iprt/mp.h>
+#include <iprt/cpuset.h>
+#include <iprt/string.h>
+#include <iprt/thread.h>
+#include "r0drv/mp-r0drv.h"
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/** Whether CPUs are being watched or not. */
+static volatile bool g_fSolCpuWatch = false;
+/** Set of online cpus that is maintained by the MP callback.
+ * This avoids locking issues querying the set from the kernel as well as
+ * eliminating any uncertainty regarding the online status during the
+ * callback. */
+RTCPUSET g_rtMpSolCpuSet;
+
+/**
+ * Internal solaris representation for watching CPUs.
+ */
+typedef struct RTMPSOLWATCHCPUS
+{
+    /** Function pointer to Mp worker. */
+    PFNRTMPWORKER   pfnWorker;
+    /** Argument to pass to the Mp worker. */
+    void           *pvArg;
+} RTMPSOLWATCHCPUS;
+typedef RTMPSOLWATCHCPUS *PRTMPSOLWATCHCPUS;
+
+
+/**
+ * Solaris callback function for Mp event notification.
+ *
+ * @returns Solaris error code.
+ * @param    CpuState   The current event/state of the CPU.
+ * @param    iCpu       Which CPU is this event for.
+ * @param    pvArg      Ignored.
+ *
+ * @remarks This function assumes index == RTCPUID.
+ *          We may -not- be firing on the CPU going online/offline and called
+ *          with preemption enabled.
+ */
+static int rtMpNotificationCpuEvent(cpu_setup_t CpuState, int iCpu, void *pvArg)
+{
+    RTMPEVENT enmMpEvent;
+
+    /*
+     * Update our CPU set structures first regardless of whether we've been
+     * scheduled on the right CPU or not, this is just atomic accounting.
+     */
+    if (CpuState == CPU_ON)
+    {
+        enmMpEvent = RTMPEVENT_ONLINE;
+        RTCpuSetAdd(&g_rtMpSolCpuSet, iCpu);
+    }
+    else if (CpuState == CPU_OFF)
+    {
+        enmMpEvent = RTMPEVENT_OFFLINE;
+        RTCpuSetDel(&g_rtMpSolCpuSet, iCpu);
+    }
+    else
+        return 0;
+
+    rtMpNotificationDoCallbacks(enmMpEvent, iCpu);
+    NOREF(pvArg);
+    return 0;
+}
+
+
+DECLHIDDEN(int) rtR0MpNotificationNativeInit(void)
+{
+    if (ASMAtomicReadBool(&g_fSolCpuWatch) == true)
+        return VERR_WRONG_ORDER;
+
+    /*
+     * Register the callback building the online cpu set as we do so.
+     */
+    RTCpuSetEmpty(&g_rtMpSolCpuSet);
+
+    mutex_enter(&cpu_lock);
+    register_cpu_setup_func(rtMpNotificationCpuEvent, NULL /* pvArg */);
+
+    for (int i = 0; i < (int)RTMpGetCount(); ++i)
+        if (cpu_is_online(cpu[i]))
+            rtMpNotificationCpuEvent(CPU_ON, i, NULL /* pvArg */);
+
+    ASMAtomicWriteBool(&g_fSolCpuWatch, true);
+    mutex_exit(&cpu_lock);
+
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(void) rtR0MpNotificationNativeTerm(void)
+{
+    if (ASMAtomicReadBool(&g_fSolCpuWatch) == true)
+    {
+        mutex_enter(&cpu_lock);
+        unregister_cpu_setup_func(rtMpNotificationCpuEvent, NULL /* pvArg */);
+        ASMAtomicWriteBool(&g_fSolCpuWatch, false);
+        mutex_exit(&cpu_lock);
+    }
+}
+
diff --git a/src/VBox/Runtime/r0drv/solaris/process-r0drv-solaris.c b/src/VBox/Runtime/r0drv/solaris/process-r0drv-solaris.c
new file mode 100644
index 00000000..ecf66f78
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/process-r0drv-solaris.c
@@ -0,0 +1,49 @@
+/* $Id: process-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Process Management, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-solaris-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/process.h>
+
+
+
+RTDECL(RTPROCESS) RTProcSelf(void)
+{
+    return ddi_get_pid();
+}
+
+
+RTR0DECL(RTR0PROCESS) RTR0ProcHandleSelf(void)
+{
+    proc_t *pProcess = NULL;
+    drv_getparm(UPROCP, &pProcess);
+    return (RTR0PROCESS)pProcess;
+}
+
diff --git a/src/VBox/Runtime/r0drv/solaris/semevent-r0drv-solaris.c b/src/VBox/Runtime/r0drv/solaris/semevent-r0drv-solaris.c
new file mode 100644
index 00000000..47ef7df1
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/semevent-r0drv-solaris.c
@@ -0,0 +1,347 @@
+/* $Id: semevent-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Single Release Event Semaphores, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTSEMEVENT_WITHOUT_REMAPPING
+#include "the-solaris-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/semaphore.h>
+
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/err.h>
+#include <iprt/list.h>
+#include <iprt/lockvalidator.h>
+#include <iprt/mem.h>
+#include <iprt/mp.h>
+#include <iprt/thread.h>
+#include "internal/magics.h"
+#include "semeventwait-r0drv-solaris.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Waiter entry.  Lives on the stack.
+ *
+ * @remarks Unfortunately, we cannot easily use cv_signal because we cannot
+ *          distinguish between it and the spurious wakeups we get after fork.
+ *          So, we keep an unprioritized FIFO with the sleeping threads.
+ */
+typedef struct RTSEMEVENTSOLENTRY
+{
+    /** The list node. */
+    RTLISTNODE          Node;
+    /** The thread. */
+    kthread_t          *pThread;
+    /** Set to @c true when waking up the thread by signal or destroy. */
+    uint32_t volatile  fWokenUp;
+} RTSEMEVENTSOLENTRY;
+/** Pointer to waiter entry. */
+typedef RTSEMEVENTSOLENTRY *PRTSEMEVENTSOLENTRY;
+
+
+/**
+ * Solaris event semaphore.
+ */
+typedef struct RTSEMEVENTINTERNAL
+{
+    /** Magic value (RTSEMEVENT_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** The number of threads referencing this object. */
+    uint32_t volatile   cRefs;
+    /** Set if the object is signalled when there are no waiters. */
+    bool                fSignaled;
+    /** List of waiting and woken up threads. */
+    RTLISTANCHOR        WaitList;
+    /** The Solaris mutex protecting this structure and pairing up the with the cv. */
+    kmutex_t            Mtx;
+    /** The Solaris condition variable. */
+    kcondvar_t          Cnd;
+} RTSEMEVENTINTERNAL, *PRTSEMEVENTINTERNAL;
+
+
+
+RTDECL(int)  RTSemEventCreate(PRTSEMEVENT phEventSem)
+{
+    return RTSemEventCreateEx(phEventSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, NULL);
+}
+
+
+RTDECL(int)  RTSemEventCreateEx(PRTSEMEVENT phEventSem, uint32_t fFlags, RTLOCKVALCLASS hClass, const char *pszNameFmt, ...)
+{
+    AssertCompile(sizeof(RTSEMEVENTINTERNAL) > sizeof(void *));
+    AssertReturn(!(fFlags & ~(RTSEMEVENT_FLAGS_NO_LOCK_VAL | RTSEMEVENT_FLAGS_BOOTSTRAP_HACK)), VERR_INVALID_PARAMETER);
+    Assert(!(fFlags & RTSEMEVENT_FLAGS_BOOTSTRAP_HACK) || (fFlags & RTSEMEVENT_FLAGS_NO_LOCK_VAL));
+    AssertPtrReturn(phEventSem, VERR_INVALID_POINTER);
+    RT_ASSERT_PREEMPTIBLE();
+
+    PRTSEMEVENTINTERNAL pThis = (PRTSEMEVENTINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (!pThis)
+        return VERR_NO_MEMORY;
+
+    pThis->u32Magic       = RTSEMEVENT_MAGIC;
+    pThis->cRefs          = 1;
+    pThis->fSignaled      = false;
+    RTListInit(&pThis->WaitList);
+    mutex_init(&pThis->Mtx, "IPRT Event Semaphore", MUTEX_DRIVER, (void *)ipltospl(DISP_LEVEL));
+    cv_init(&pThis->Cnd, "IPRT CV", CV_DRIVER, NULL);
+
+    *phEventSem = pThis;
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Retain a reference to the semaphore.
+ *
+ * @param   pThis       The semaphore.
+ */
+DECLINLINE(void) rtR0SemEventSolRetain(PRTSEMEVENTINTERNAL pThis)
+{
+    uint32_t cRefs = ASMAtomicIncU32(&pThis->cRefs);
+    Assert(cRefs && cRefs < 100000);
+    NOREF(cRefs);
+}
+
+
+/**
+ * The destruct.
+ *
+ * @param   pThis       The semaphore.
+ */
+static void rtR0SemEventSolDtor(PRTSEMEVENTINTERNAL pThis)
+{
+    Assert(pThis->u32Magic != RTSEMEVENT_MAGIC);
+    cv_destroy(&pThis->Cnd);
+    mutex_destroy(&pThis->Mtx);
+    RTMemFree(pThis);
+}
+
+
+/**
+ * Release a reference, destroy the thing if necessary.
+ *
+ * @param   pThis       The semaphore.
+ */
+DECLINLINE(void) rtR0SemEventSolRelease(PRTSEMEVENTINTERNAL pThis)
+{
+    if (RT_UNLIKELY(ASMAtomicDecU32(&pThis->cRefs) == 0))
+        rtR0SemEventSolDtor(pThis);
+}
+
+
+RTDECL(int)  RTSemEventDestroy(RTSEMEVENT hEventSem)
+{
+    /*
+     * Validate input.
+     */
+    PRTSEMEVENTINTERNAL pThis = hEventSem;
+    if (pThis == NIL_RTSEMEVENT)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+    Assert(pThis->cRefs > 0);
+    RT_ASSERT_INTS_ON();
+
+    mutex_enter(&pThis->Mtx);
+
+    /*
+     * Invalidate the semaphore.
+     */
+    ASMAtomicWriteU32(&pThis->u32Magic, ~RTSEMEVENT_MAGIC);
+    ASMAtomicWriteBool(&pThis->fSignaled, false);
+
+    /*
+     * Abort and wake up all threads.
+     */
+    PRTSEMEVENTSOLENTRY pWaiter;
+    RTListForEach(&pThis->WaitList, pWaiter, RTSEMEVENTSOLENTRY, Node)
+    {
+        pWaiter->fWokenUp = true;
+    }
+    cv_broadcast(&pThis->Cnd);
+
+    /*
+     * Release the reference from RTSemEventCreateEx.
+     */
+    mutex_exit(&pThis->Mtx);
+    rtR0SemEventSolRelease(pThis);
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTSemEventSignal(RTSEMEVENT hEventSem)
+{
+    PRTSEMEVENTINTERNAL pThis = (PRTSEMEVENTINTERNAL)hEventSem;
+    RT_ASSERT_PREEMPT_CPUID_VAR();
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+    RT_ASSERT_INTS_ON();
+
+    rtR0SemEventSolRetain(pThis);
+    rtR0SemSolWaitEnterMutexWithUnpinningHack(&pThis->Mtx);
+
+    /*
+     * Wake up one thread.
+     */
+    ASMAtomicWriteBool(&pThis->fSignaled, true);
+
+    PRTSEMEVENTSOLENTRY pWaiter;
+    RTListForEach(&pThis->WaitList, pWaiter, RTSEMEVENTSOLENTRY, Node)
+    {
+        if (!pWaiter->fWokenUp)
+        {
+            pWaiter->fWokenUp = true;
+            setrun(pWaiter->pThread);
+            ASMAtomicWriteBool(&pThis->fSignaled, false);
+            break;
+        }
+    }
+
+    mutex_exit(&pThis->Mtx);
+    rtR0SemEventSolRelease(pThis);
+
+#ifdef DEBUG_ramshankar
+    /** See @bugref{6318} comment#11 */
+    return VINF_SUCCESS;
+#endif
+    RT_ASSERT_PREEMPT_CPUID();
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Worker for RTSemEventWaitEx and RTSemEventWaitExDebug.
+ *
+ * @returns VBox status code.
+ * @param   pThis           The event semaphore.
+ * @param   fFlags          See RTSemEventWaitEx.
+ * @param   uTimeout        See RTSemEventWaitEx.
+ * @param   pSrcPos         The source code position of the wait.
+ */
+static int rtR0SemEventSolWait(PRTSEMEVENTINTERNAL pThis, uint32_t fFlags, uint64_t uTimeout,
+                               PCRTLOCKVALSRCPOS pSrcPos)
+{
+    /*
+     * Validate the input.
+     */
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENT_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    AssertReturn(RTSEMWAIT_FLAGS_ARE_VALID(fFlags), VERR_INVALID_PARAMETER);
+
+    rtR0SemEventSolRetain(pThis);
+    mutex_enter(&pThis->Mtx);
+
+    /*
+     * In the signaled state?
+     */
+    int rc;
+    if (ASMAtomicCmpXchgBool(&pThis->fSignaled, false, true))
+        rc = VINF_SUCCESS;
+    else
+    {
+        /*
+         * We have to wait.
+         */
+        RTR0SEMSOLWAIT Wait;
+        rc = rtR0SemSolWaitInit(&Wait, fFlags, uTimeout);
+        if (RT_SUCCESS(rc))
+        {
+            RTSEMEVENTSOLENTRY Waiter;  /* ASSUMES we won't get swapped out while waiting (TS_DONT_SWAP). */
+            Waiter.pThread  = curthread;
+            Waiter.fWokenUp = false;
+            RTListAppend(&pThis->WaitList, &Waiter.Node);
+
+            for (;;)
+            {
+                /* The destruction test. */
+                if (RT_UNLIKELY(pThis->u32Magic != RTSEMEVENT_MAGIC))
+                    rc = VERR_SEM_DESTROYED;
+                else
+                {
+                    /* Check the exit conditions. */
+                    if (RT_UNLIKELY(pThis->u32Magic != RTSEMEVENT_MAGIC))
+                        rc = VERR_SEM_DESTROYED;
+                    else if (Waiter.fWokenUp)
+                        rc = VINF_SUCCESS;
+                    else if (rtR0SemSolWaitHasTimedOut(&Wait))
+                        rc = VERR_TIMEOUT;
+                    else if (rtR0SemSolWaitWasInterrupted(&Wait))
+                        rc = VERR_INTERRUPTED;
+                    else
+                    {
+                        /* Do the wait and then recheck the conditions. */
+                        rtR0SemSolWaitDoIt(&Wait, &pThis->Cnd, &pThis->Mtx, &Waiter.fWokenUp, false);
+                        continue;
+                    }
+                }
+                break;
+            }
+
+            rtR0SemSolWaitDelete(&Wait);
+            RTListNodeRemove(&Waiter.Node);
+        }
+    }
+
+    mutex_exit(&pThis->Mtx);
+    rtR0SemEventSolRelease(pThis);
+    return rc;
+}
+
+
+RTDECL(int)  RTSemEventWaitEx(RTSEMEVENT hEventSem, uint32_t fFlags, uint64_t uTimeout)
+{
+#ifndef RTSEMEVENT_STRICT
+    return rtR0SemEventSolWait(hEventSem, fFlags, uTimeout, NULL);
+#else
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
+    return rtR0SemEventSolWait(hEventSem, fFlags, uTimeout, &SrcPos);
+#endif
+}
+
+
+RTDECL(int)  RTSemEventWaitExDebug(RTSEMEVENT hEventSem, uint32_t fFlags, uint64_t uTimeout,
+                                   RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
+    return rtR0SemEventSolWait(hEventSem, fFlags, uTimeout, &SrcPos);
+}
+
+
+RTDECL(uint32_t) RTSemEventGetResolution(void)
+{
+    return rtR0SemSolWaitGetResolution();
+}
+
diff --git a/src/VBox/Runtime/r0drv/solaris/semeventmulti-r0drv-solaris.c b/src/VBox/Runtime/r0drv/solaris/semeventmulti-r0drv-solaris.c
new file mode 100644
index 00000000..7b10b610
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/semeventmulti-r0drv-solaris.c
@@ -0,0 +1,355 @@
+/* $Id: semeventmulti-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Multiple Release Event Semaphores, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTSEMEVENTMULTI_WITHOUT_REMAPPING
+#include "the-solaris-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/semaphore.h>
+
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/err.h>
+#include <iprt/lockvalidator.h>
+#include <iprt/mem.h>
+#include <iprt/mp.h>
+#include <iprt/thread.h>
+#include <iprt/time.h>
+#include "internal/magics.h"
+#include "semeventwait-r0drv-solaris.h"
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+/** @name fStateAndGen values
+ * @{ */
+/** The state bit number. */
+#define RTSEMEVENTMULTISOL_STATE_BIT        0
+/** The state mask. */
+#define RTSEMEVENTMULTISOL_STATE_MASK       RT_BIT_32(RTSEMEVENTMULTISOL_STATE_BIT)
+/** The generation mask. */
+#define RTSEMEVENTMULTISOL_GEN_MASK         ~RTSEMEVENTMULTISOL_STATE_MASK
+/** The generation shift. */
+#define RTSEMEVENTMULTISOL_GEN_SHIFT        1
+/** The initial variable value. */
+#define RTSEMEVENTMULTISOL_STATE_GEN_INIT   UINT32_C(0xfffffffc)
+/** @}  */
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Solaris multiple release event semaphore.
+ */
+typedef struct RTSEMEVENTMULTIINTERNAL
+{
+    /** Magic value (RTSEMEVENTMULTI_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** The number of references. */
+    uint32_t volatile   cRefs;
+    /** The object state bit and generation counter.
+     * The generation counter is incremented every time the object is
+     * signalled. */
+    uint32_t volatile   fStateAndGen;
+    /** The Solaris mutex protecting this structure and pairing up the with the cv. */
+    kmutex_t            Mtx;
+    /** The Solaris condition variable. */
+    kcondvar_t          Cnd;
+} RTSEMEVENTMULTIINTERNAL, *PRTSEMEVENTMULTIINTERNAL;
+
+
+
+RTDECL(int)  RTSemEventMultiCreate(PRTSEMEVENTMULTI phEventMultiSem)
+{
+    return RTSemEventMultiCreateEx(phEventMultiSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, NULL);
+}
+
+
+RTDECL(int)  RTSemEventMultiCreateEx(PRTSEMEVENTMULTI phEventMultiSem, uint32_t fFlags, RTLOCKVALCLASS hClass,
+                                     const char *pszNameFmt, ...)
+{
+    AssertReturn(!(fFlags & ~RTSEMEVENTMULTI_FLAGS_NO_LOCK_VAL), VERR_INVALID_PARAMETER);
+    AssertPtrReturn(phEventMultiSem, VERR_INVALID_POINTER);
+    RT_ASSERT_PREEMPTIBLE();
+
+    AssertCompile(sizeof(RTSEMEVENTMULTIINTERNAL) > sizeof(void *));
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (pThis)
+    {
+        pThis->u32Magic     = RTSEMEVENTMULTI_MAGIC;
+        pThis->cRefs        = 1;
+        pThis->fStateAndGen = RTSEMEVENTMULTISOL_STATE_GEN_INIT;
+        mutex_init(&pThis->Mtx, "IPRT Multiple Release Event Semaphore", MUTEX_DRIVER, (void *)ipltospl(DISP_LEVEL));
+        cv_init(&pThis->Cnd, "IPRT CV", CV_DRIVER, NULL);
+
+        *phEventMultiSem = pThis;
+        return VINF_SUCCESS;
+    }
+    return VERR_NO_MEMORY;
+}
+
+
+/**
+ * Retain a reference to the semaphore.
+ *
+ * @param   pThis       The semaphore.
+ */
+DECLINLINE(void) rtR0SemEventMultiSolRetain(PRTSEMEVENTMULTIINTERNAL pThis)
+{
+    uint32_t cRefs = ASMAtomicIncU32(&pThis->cRefs);
+    Assert(cRefs && cRefs < 100000);
+    NOREF(cRefs);
+}
+
+
+/**
+ * Destructor that is called when cRefs == 0.
+ *
+ * @param   pThis       The instance to destroy.
+ */
+static void rtSemEventMultiDtor(PRTSEMEVENTMULTIINTERNAL pThis)
+{
+    Assert(pThis->u32Magic != RTSEMEVENTMULTI_MAGIC);
+    cv_destroy(&pThis->Cnd);
+    mutex_destroy(&pThis->Mtx);
+    RTMemFree(pThis);
+}
+
+
+/**
+ * Release a reference, destroy the thing if necessary.
+ *
+ * @param   pThis       The semaphore.
+ */
+DECLINLINE(void) rtR0SemEventMultiSolRelease(PRTSEMEVENTMULTIINTERNAL pThis)
+{
+    if (RT_UNLIKELY(ASMAtomicDecU32(&pThis->cRefs) == 0))
+        rtSemEventMultiDtor(pThis);
+}
+
+
+
+RTDECL(int)  RTSemEventMultiDestroy(RTSEMEVENTMULTI hEventMultiSem)
+{
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    if (pThis == NIL_RTSEMEVENTMULTI)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->cRefs > 0, ("pThis=%p cRefs=%d\n", pThis, pThis->cRefs), VERR_INVALID_HANDLE);
+    RT_ASSERT_INTS_ON();
+
+    mutex_enter(&pThis->Mtx);
+
+    /* Invalidate the handle and wake up all threads that might be waiting on the semaphore. */
+    Assert(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC);
+    ASMAtomicWriteU32(&pThis->u32Magic, RTSEMEVENTMULTI_MAGIC_DEAD);
+    ASMAtomicAndU32(&pThis->fStateAndGen, RTSEMEVENTMULTISOL_GEN_MASK);
+    cv_broadcast(&pThis->Cnd);
+
+    /* Drop the reference from RTSemEventMultiCreateEx. */
+    mutex_exit(&pThis->Mtx);
+    rtR0SemEventMultiSolRelease(pThis);
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTSemEventMultiSignal(RTSEMEVENTMULTI hEventMultiSem)
+{
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    RT_ASSERT_PREEMPT_CPUID_VAR();
+
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC,
+                    ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic),
+                    VERR_INVALID_HANDLE);
+    RT_ASSERT_INTS_ON();
+    rtR0SemEventMultiSolRetain(pThis);
+    rtR0SemSolWaitEnterMutexWithUnpinningHack(&pThis->Mtx);
+    Assert(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC);
+
+    /*
+     * Do the job.
+     */
+    uint32_t fNew = ASMAtomicUoReadU32(&pThis->fStateAndGen);
+    fNew += 1 << RTSEMEVENTMULTISOL_GEN_SHIFT;
+    fNew |= RTSEMEVENTMULTISOL_STATE_MASK;
+    ASMAtomicWriteU32(&pThis->fStateAndGen, fNew);
+
+    cv_broadcast(&pThis->Cnd);
+
+    mutex_exit(&pThis->Mtx);
+
+    rtR0SemEventMultiSolRelease(pThis);
+#ifdef DEBUG_ramshankar
+    /** See @bugref{6318#c11}. */
+    return VINF_SUCCESS;
+#endif
+    RT_ASSERT_PREEMPT_CPUID();
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTSemEventMultiReset(RTSEMEVENTMULTI hEventMultiSem)
+{
+    PRTSEMEVENTMULTIINTERNAL pThis = (PRTSEMEVENTMULTIINTERNAL)hEventMultiSem;
+    RT_ASSERT_PREEMPT_CPUID_VAR();
+
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC,
+                    ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic),
+                    VERR_INVALID_HANDLE);
+    RT_ASSERT_INTS_ON();
+
+    rtR0SemEventMultiSolRetain(pThis);
+    rtR0SemSolWaitEnterMutexWithUnpinningHack(&pThis->Mtx);
+    Assert(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC);
+
+    /*
+     * Do the job (could be done without the lock, but play safe).
+     */
+    ASMAtomicAndU32(&pThis->fStateAndGen, ~RTSEMEVENTMULTISOL_STATE_MASK);
+
+    mutex_exit(&pThis->Mtx);
+    rtR0SemEventMultiSolRelease(pThis);
+
+#ifdef DEBUG_ramshankar
+    /** See @bugref{6318#c11}. */
+    return VINF_SUCCESS;
+#endif
+    RT_ASSERT_PREEMPT_CPUID();
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Worker for RTSemEventMultiWaitEx and RTSemEventMultiWaitExDebug.
+ *
+ * @returns VBox status code.
+ * @param   pThis           The event semaphore.
+ * @param   fFlags          See RTSemEventMultiWaitEx.
+ * @param   uTimeout        See RTSemEventMultiWaitEx.
+ * @param   pSrcPos         The source code position of the wait.
+ */
+static int rtR0SemEventMultiSolWait(PRTSEMEVENTMULTIINTERNAL pThis, uint32_t fFlags, uint64_t uTimeout,
+                                    PCRTLOCKVALSRCPOS pSrcPos)
+{
+    uint32_t    fOrgStateAndGen;
+    int         rc;
+
+    /*
+     * Validate the input.
+     */
+    AssertPtrReturn(pThis, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(pThis->u32Magic == RTSEMEVENTMULTI_MAGIC, ("%p u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_PARAMETER);
+    AssertReturn(RTSEMWAIT_FLAGS_ARE_VALID(fFlags), VERR_INVALID_PARAMETER);
+    rtR0SemEventMultiSolRetain(pThis);
+    mutex_enter(&pThis->Mtx); /* this could be moved down to the else, but play safe for now. */
+
+    /*
+     * Is the event already signalled or do we have to wait?
+     */
+    fOrgStateAndGen = ASMAtomicUoReadU32(&pThis->fStateAndGen);
+    if (fOrgStateAndGen & RTSEMEVENTMULTISOL_STATE_MASK)
+        rc = VINF_SUCCESS;
+    else
+    {
+        /*
+         * We have to wait.
+         */
+        RTR0SEMSOLWAIT Wait;
+        rc = rtR0SemSolWaitInit(&Wait, fFlags, uTimeout);
+        if (RT_SUCCESS(rc))
+        {
+            for (;;)
+            {
+                /* The destruction test. */
+                if (RT_UNLIKELY(pThis->u32Magic != RTSEMEVENTMULTI_MAGIC))
+                    rc = VERR_SEM_DESTROYED;
+                else
+                {
+                    /* Check the exit conditions. */
+                    if (RT_UNLIKELY(pThis->u32Magic != RTSEMEVENTMULTI_MAGIC))
+                        rc = VERR_SEM_DESTROYED;
+                    else if (ASMAtomicUoReadU32(&pThis->fStateAndGen) != fOrgStateAndGen)
+                        rc = VINF_SUCCESS;
+                    else if (rtR0SemSolWaitHasTimedOut(&Wait))
+                        rc = VERR_TIMEOUT;
+                    else if (rtR0SemSolWaitWasInterrupted(&Wait))
+                        rc = VERR_INTERRUPTED;
+                    else
+                    {
+                        /* Do the wait and then recheck the conditions. */
+                        rtR0SemSolWaitDoIt(&Wait, &pThis->Cnd, &pThis->Mtx, &pThis->fStateAndGen, fOrgStateAndGen);
+                        continue;
+                    }
+                }
+                break;
+            }
+            rtR0SemSolWaitDelete(&Wait);
+        }
+    }
+
+    mutex_exit(&pThis->Mtx);
+    rtR0SemEventMultiSolRelease(pThis);
+    return rc;
+}
+
+
+
+RTDECL(int)  RTSemEventMultiWaitEx(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout)
+{
+#ifndef RTSEMEVENT_STRICT
+    return rtR0SemEventMultiSolWait(hEventMultiSem, fFlags, uTimeout, NULL);
+#else
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
+    return rtR0SemEventMultiSolWait(hEventMultiSem, fFlags, uTimeout, &SrcPos);
+#endif
+}
+
+
+RTDECL(int)  RTSemEventMultiWaitExDebug(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout,
+                                        RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
+    return rtR0SemEventMultiSolWait(hEventMultiSem, fFlags, uTimeout, &SrcPos);
+}
+
+
+RTDECL(uint32_t) RTSemEventMultiGetResolution(void)
+{
+    return rtR0SemSolWaitGetResolution();
+}
+
diff --git a/src/VBox/Runtime/r0drv/solaris/semeventwait-r0drv-solaris.h b/src/VBox/Runtime/r0drv/solaris/semeventwait-r0drv-solaris.h
new file mode 100644
index 00000000..6ce0ad21
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/semeventwait-r0drv-solaris.h
@@ -0,0 +1,496 @@
+/* $Id: semeventwait-r0drv-solaris.h $ */
+/** @file
+ * IPRT - Solaris Ring-0 Driver Helpers for Event Semaphore Waits.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+#ifndef IPRT_INCLUDED_SRC_r0drv_solaris_semeventwait_r0drv_solaris_h
+#define IPRT_INCLUDED_SRC_r0drv_solaris_semeventwait_r0drv_solaris_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include "the-solaris-kernel.h"
+
+#include <iprt/err.h>
+#include <iprt/string.h>
+#include <iprt/time.h>
+
+
+/** The resolution (nanoseconds) specified when using timeout_generic. */
+#define RTR0SEMSOLWAIT_RESOLUTION   50000
+
+/** Disables the cyclic fallback code for old S10 installs - see @bugref{5342}.
+ * @todo Fixed by @bugref{5595}, can be reenabled after checking out
+ *       CY_HIGH_LEVEL. */
+#define RTR0SEMSOLWAIT_NO_OLD_S10_FALLBACK
+
+#define SOL_THREAD_TINTR_PTR        ((kthread_t **)((char *)curthread + g_offrtSolThreadIntrThread))
+
+
+/**
+ * Solaris semaphore wait structure.
+ */
+typedef struct RTR0SEMSOLWAIT
+{
+    /** The absolute timeout given as nanoseconds since the start of the
+     *  monotonic clock. */
+    uint64_t        uNsAbsTimeout;
+    /** The timeout in nanoseconds relative to the start of the wait. */
+    uint64_t        cNsRelTimeout;
+    /** The native timeout value. */
+    union
+    {
+        /** The timeout (in ticks) when fHighRes is false.  */
+        clock_t     lTimeout;
+    } u;
+    /** Set if we use high resolution timeouts. */
+    bool            fHighRes;
+    /** Set if it's an indefinite wait. */
+    bool            fIndefinite;
+    /** Set if the waiting thread is ready to be woken up.
+     * Avoids false setrun() calls due to temporary mutex exits. */
+    bool volatile   fWantWakeup;
+    /** Set if we've already timed out.
+     * Set by rtR0SemSolWaitDoIt or rtR0SemSolWaitHighResTimeout, read by
+     * rtR0SemSolWaitHasTimedOut. */
+    bool volatile   fTimedOut;
+    /** Whether the wait was interrupted. */
+    bool            fInterrupted;
+    /** Interruptible or uninterruptible wait. */
+    bool            fInterruptible;
+    /** The thread to wake up. */
+    kthread_t      *pThread;
+#ifndef RTR0SEMSOLWAIT_NO_OLD_S10_FALLBACK
+    /** Cylic timer ID (used by the timeout callback). */
+    cyclic_id_t     idCy;
+#endif
+    /** The mutex associated with the condition variable wait. */
+    void volatile  *pvMtx;
+} RTR0SEMSOLWAIT;
+/** Pointer to a solaris semaphore wait structure.  */
+typedef RTR0SEMSOLWAIT *PRTR0SEMSOLWAIT;
+
+
+/**
+ * Initializes a wait.
+ *
+ * The caller MUST check the wait condition BEFORE calling this function or the
+ * timeout logic will be flawed.
+ *
+ * @returns VINF_SUCCESS or VERR_TIMEOUT.
+ * @param   pWait               The wait structure.
+ * @param   fFlags              The wait flags.
+ * @param   uTimeout            The timeout.
+ */
+DECLINLINE(int) rtR0SemSolWaitInit(PRTR0SEMSOLWAIT pWait, uint32_t fFlags, uint64_t uTimeout)
+{
+    /*
+     * Process the flags and timeout.
+     */
+    if (!(fFlags & RTSEMWAIT_FLAGS_INDEFINITE))
+    {
+        if (fFlags & RTSEMWAIT_FLAGS_MILLISECS)
+            uTimeout = uTimeout < UINT64_MAX / RT_NS_1MS
+                     ? uTimeout * RT_NS_1MS
+                     : UINT64_MAX;
+        if (uTimeout == UINT64_MAX)
+            fFlags |= RTSEMWAIT_FLAGS_INDEFINITE;
+        else
+        {
+            uint64_t u64Now;
+            if (fFlags & RTSEMWAIT_FLAGS_RELATIVE)
+            {
+                if (uTimeout == 0)
+                    return VERR_TIMEOUT;
+
+                u64Now = RTTimeSystemNanoTS();
+                pWait->cNsRelTimeout = uTimeout;
+                pWait->uNsAbsTimeout = u64Now + uTimeout;
+                if (pWait->uNsAbsTimeout < u64Now) /* overflow */
+                    fFlags |= RTSEMWAIT_FLAGS_INDEFINITE;
+            }
+            else
+            {
+                u64Now = RTTimeSystemNanoTS();
+                if (u64Now >= uTimeout)
+                    return VERR_TIMEOUT;
+
+                pWait->cNsRelTimeout = uTimeout - u64Now;
+                pWait->uNsAbsTimeout = uTimeout;
+            }
+        }
+    }
+
+    if (!(fFlags & RTSEMWAIT_FLAGS_INDEFINITE))
+    {
+        pWait->fIndefinite      = false;
+        if (  (   (fFlags & (RTSEMWAIT_FLAGS_NANOSECS | RTSEMWAIT_FLAGS_ABSOLUTE))
+               || pWait->cNsRelTimeout < UINT32_C(1000000000) / 100 /*Hz*/ * 4)
+#ifdef RTR0SEMSOLWAIT_NO_OLD_S10_FALLBACK
+            && g_pfnrtR0Sol_timeout_generic != NULL
+#endif
+           )
+            pWait->fHighRes     = true;
+        else
+        {
+            uint64_t cTicks     = NSEC_TO_TICK_ROUNDUP(uTimeout);
+            if (cTicks >= LONG_MAX)
+                fFlags |= RTSEMWAIT_FLAGS_INDEFINITE;
+            else
+            {
+                pWait->u.lTimeout = cTicks;
+                pWait->fHighRes = false;
+            }
+        }
+    }
+
+    if (fFlags & RTSEMWAIT_FLAGS_INDEFINITE)
+    {
+        pWait->fIndefinite      = true;
+        pWait->fHighRes         = false;
+        pWait->uNsAbsTimeout    = UINT64_MAX;
+        pWait->cNsRelTimeout    = UINT64_MAX;
+        pWait->u.lTimeout       = LONG_MAX;
+    }
+
+    pWait->fWantWakeup      = false;
+    pWait->fTimedOut        = false;
+    pWait->fInterrupted     = false;
+    pWait->fInterruptible   = !!(fFlags & RTSEMWAIT_FLAGS_INTERRUPTIBLE);
+    pWait->pThread          = curthread;
+    pWait->pvMtx            = NULL;
+#ifndef RTR0SEMSOLWAIT_NO_OLD_S10_FALLBACK
+    pWait->idCy             = CYCLIC_NONE;
+#endif
+
+    return VINF_SUCCESS;
+}
+
+
+#ifndef RTR0SEMSOLWAIT_NO_OLD_S10_FALLBACK
+/**
+ * Cyclic timeout callback that sets the timeout indicator and wakes up the
+ * waiting thread.
+ *
+ * @param   pvUser              The wait structure.
+ */
+static void rtR0SemSolWaitHighResTimeout(void *pvUser)
+{
+    PRTR0SEMSOLWAIT pWait   = (PRTR0SEMSOLWAIT)pvUser;
+    kthread_t      *pThread = pWait->pThread;
+    kmutex_t       *pMtx    = (kmutex_t *)ASMAtomicReadPtr(&pWait->pvMtx);
+    if (VALID_PTR(pMtx))
+    {
+        /* Enter the mutex here to make sure the thread has gone to sleep
+           before we wake it up.
+           Note: Trying to take the cpu_lock here doesn't work. */
+        mutex_enter(pMtx);
+        if (mutex_owner(&cpu_lock) == curthread)
+        {
+            cyclic_remove(pWait->idCy);
+            pWait->idCy = CYCLIC_NONE;
+        }
+        bool const fWantWakeup = pWait->fWantWakeup;
+        ASMAtomicWriteBool(&pWait->fTimedOut, true);
+        mutex_exit(pMtx);
+
+        if (fWantWakeup)
+            setrun(pThread);
+    }
+}
+#endif
+
+
+/**
+ * Timeout callback that sets the timeout indicator and wakes up the waiting
+ * thread.
+ *
+ * @param   pvUser              The wait structure.
+ */
+static void rtR0SemSolWaitTimeout(void *pvUser)
+{
+    PRTR0SEMSOLWAIT pWait   = (PRTR0SEMSOLWAIT)pvUser;
+    kthread_t      *pThread = pWait->pThread;
+    kmutex_t       *pMtx    = (kmutex_t *)ASMAtomicReadPtr((void * volatile *)&pWait->pvMtx);
+    if (VALID_PTR(pMtx))
+    {
+        /* Enter the mutex here to make sure the thread has gone to sleep
+           before we wake it up. */
+        mutex_enter(pMtx);
+        bool const fWantWakeup = pWait->fWantWakeup;
+        ASMAtomicWriteBool(&pWait->fTimedOut, true);
+        mutex_exit(pMtx);
+
+        if (fWantWakeup)
+            setrun(pThread);
+    }
+}
+
+
+/**
+ * Do the actual wait.
+ *
+ * @param   pWait               The wait structure.
+ * @param   pCnd                The condition variable to wait on.
+ * @param   pMtx                The mutex related to the condition variable.
+ *                              The caller has entered this.
+ * @param   pfState             The state variable to check if have changed
+ *                              after leaving the mutex (spinlock).
+ * @param   fCurState           The current value of @a pfState.  We'll return
+ *                              without sleeping if @a pfState doesn't hold
+ *                              this value after reacquiring the mutex.
+ *
+ * @remarks This must be call with the object mutex (spinlock) held.
+ */
+DECLINLINE(void) rtR0SemSolWaitDoIt(PRTR0SEMSOLWAIT pWait, kcondvar_t *pCnd, kmutex_t *pMtx,
+                                    uint32_t volatile *pfState, uint32_t const fCurState)
+{
+    union
+    {
+        callout_id_t    idCo;
+        timeout_id_t    idTom;
+    } u;
+
+    /*
+     * Arm the timeout callback.
+     *
+     * We will have to leave the mutex (spinlock) when doing this because S10
+     * (didn't check S11) will not correctly preserve PIL across calls to
+     * timeout_generic() - @bugref{5595}.  We do it for all timeout methods to
+     * be on the safe side, the nice sideeffect of which is that it solves the
+     * lock inversion problem found in @bugref{5342}.
+     */
+    bool const  fHasTimeout = !pWait->fIndefinite;
+    bool        fGoToSleep  = !fHasTimeout;
+    if (fHasTimeout)
+    {
+        pWait->fWantWakeup = false;             /* only want fTimedOut */
+        ASMAtomicWritePtr(&pWait->pvMtx, pMtx); /* atomic is paranoia */
+        mutex_exit(pMtx);
+
+        if (pWait->fHighRes)
+        {
+#ifndef RTR0SEMSOLWAIT_NO_OLD_S10_FALLBACK
+            if (g_pfnrtR0Sol_timeout_generic != NULL)
+#endif
+            {
+                /*
+                 * High resolution timeout - arm a high resolution timeout callback
+                 * for waking up the thread at the desired time.
+                 */
+                u.idCo = g_pfnrtR0Sol_timeout_generic(CALLOUT_REALTIME, rtR0SemSolWaitTimeout, pWait,
+                                                      pWait->uNsAbsTimeout, RTR0SEMSOLWAIT_RESOLUTION,
+                                                      CALLOUT_FLAG_ABSOLUTE);
+            }
+#ifndef RTR0SEMSOLWAIT_NO_OLD_S10_FALLBACK
+            else
+            {
+                /*
+                 * High resolution timeout - arm a one-shot cyclic for waking up
+                 * the thread at the desired time.
+                 */
+                cyc_handler_t   Cyh;
+                Cyh.cyh_arg      = pWait;
+                Cyh.cyh_func     = rtR0SemSolWaitHighResTimeout;
+                Cyh.cyh_level    = CY_LOW_LEVEL; /// @todo try CY_LOCK_LEVEL and CY_HIGH_LEVEL?
+
+                cyc_time_t      Cyt;
+                Cyt.cyt_when     = pWait->uNsAbsTimeout;
+                Cyt.cyt_interval = UINT64_C(1000000000) * 60;
+
+                mutex_enter(&cpu_lock);
+                pWait->idCy = cyclic_add(&Cyh, &Cyt);
+                mutex_exit(&cpu_lock);
+            }
+#endif
+        }
+        else
+        {
+            /*
+             * Normal timeout.
+             * We're better off with our own callback like on the timeout man page,
+             * than calling cv_timedwait[_sig]().
+             */
+            u.idTom = realtime_timeout(rtR0SemSolWaitTimeout, pWait, pWait->u.lTimeout);
+        }
+
+        /*
+         * Reacquire the mutex and check if the sleep condition still holds and
+         * that we didn't already time out.
+         */
+        mutex_enter(pMtx);
+        pWait->fWantWakeup = true;
+        fGoToSleep = !ASMAtomicUoReadBool(&pWait->fTimedOut)
+                  && ASMAtomicReadU32(pfState) == fCurState;
+    }
+
+    /*
+     * Do the waiting if that's still desirable.
+     * (rc > 0 - normal wake-up; rc == 0 - interruption; rc == -1 - timeout)
+     */
+    if (fGoToSleep)
+    {
+        if (pWait->fInterruptible)
+        {
+            int rc = cv_wait_sig(pCnd, pMtx);
+            if (RT_UNLIKELY(rc <= 0))
+            {
+                if (RT_LIKELY(rc == 0))
+                    pWait->fInterrupted = true;
+                else
+                    AssertMsgFailed(("rc=%d\n", rc)); /* no timeouts, see above! */
+            }
+        }
+        else
+            cv_wait(pCnd, pMtx);
+    }
+
+    /*
+     * Remove the timeout callback.  Drop the lock while we're doing that
+     * to reduce lock contention / deadlocks.  Before dropping the lock,
+     * indicate that the callback shouldn't do anything.
+     *
+     * (Too bad we are stuck with the cv_* API here, it's doing a little
+     * bit too much.)
+     */
+    if (fHasTimeout)
+    {
+        pWait->fWantWakeup = false;
+        ASMAtomicWritePtr(&pWait->pvMtx, NULL);
+        mutex_exit(pMtx);
+
+        if (pWait->fHighRes)
+        {
+#ifndef RTR0SEMSOLWAIT_NO_OLD_S10_FALLBACK
+            if (g_pfnrtR0Sol_timeout_generic != NULL)
+#endif
+                g_pfnrtR0Sol_untimeout_generic(u.idCo, 0 /*nowait*/);
+#ifndef RTR0SEMSOLWAIT_NO_OLD_S10_FALLBACK
+            else
+            {
+                mutex_enter(&cpu_lock);
+                if (pWait->idCy != CYCLIC_NONE)
+                {
+                    cyclic_remove(pWait->idCy);
+                    pWait->idCy = CYCLIC_NONE;
+                }
+                mutex_exit(&cpu_lock);
+            }
+#endif
+        }
+        else
+            untimeout(u.idTom);
+
+        mutex_enter(pMtx);
+    }
+}
+
+
+/**
+ * Checks if a solaris wait was interrupted.
+ *
+ * @returns true / false
+ * @param   pWait               The wait structure.
+ * @remarks This shall be called before the first rtR0SemSolWaitDoIt().
+ */
+DECLINLINE(bool) rtR0SemSolWaitWasInterrupted(PRTR0SEMSOLWAIT pWait)
+{
+    return pWait->fInterrupted;
+}
+
+
+/**
+ * Checks if a solaris wait has timed out.
+ *
+ * @returns true / false
+ * @param   pWait               The wait structure.
+ */
+DECLINLINE(bool) rtR0SemSolWaitHasTimedOut(PRTR0SEMSOLWAIT pWait)
+{
+    return pWait->fTimedOut;
+}
+
+
+/**
+ * Deletes a solaris wait.
+ *
+ * @param   pWait               The wait structure.
+ */
+DECLINLINE(void) rtR0SemSolWaitDelete(PRTR0SEMSOLWAIT pWait)
+{
+    pWait->pThread = NULL;
+}
+
+
+/**
+ * Enters the mutex, unpinning the underlying current thread if contended and
+ * we're on an interrupt thread.
+ *
+ * The unpinning is done to prevent a deadlock, see s this could lead to a
+ * deadlock (see @bugref{4259} for the full explanation)
+ *
+ * @param   pMtx            The mutex to enter.
+ */
+DECLINLINE(void) rtR0SemSolWaitEnterMutexWithUnpinningHack(kmutex_t *pMtx)
+{
+    int fAcquired = mutex_tryenter(pMtx);
+    if (!fAcquired)
+    {
+        /*
+         * Note! This assumes nobody is using the RTThreadPreemptDisable() in an
+         *       interrupt context and expects it to work right.  The swtch will
+         *       result in a voluntary preemption.  To fix this, we would have to
+         *       do our own counting in RTThreadPreemptDisable/Restore() like we do
+         *       on systems which doesn't do preemption (OS/2, linux, ...) and
+         *       check whether preemption was disabled via RTThreadPreemptDisable()
+         *       or not and only call swtch if RTThreadPreemptDisable() wasn't called.
+         */
+        kthread_t **ppIntrThread = SOL_THREAD_TINTR_PTR;
+        if (   *ppIntrThread
+            && getpil() < DISP_LEVEL)
+        {
+            RTTHREADPREEMPTSTATE PreemptState = RTTHREADPREEMPTSTATE_INITIALIZER;
+            RTThreadPreemptDisable(&PreemptState);
+            preempt();
+            RTThreadPreemptRestore(&PreemptState);
+        }
+        mutex_enter(pMtx);
+    }
+}
+
+
+/**
+ * Gets the max resolution of the timeout machinery.
+ *
+ * @returns Resolution specified in nanoseconds.
+ */
+DECLINLINE(uint32_t) rtR0SemSolWaitGetResolution(void)
+{
+    return g_pfnrtR0Sol_timeout_generic != NULL
+         ? RTR0SEMSOLWAIT_RESOLUTION
+         : cyclic_getres();
+}
+
+#endif /* !IPRT_INCLUDED_SRC_r0drv_solaris_semeventwait_r0drv_solaris_h */
+
diff --git a/src/VBox/Runtime/r0drv/solaris/semfastmutex-r0drv-solaris.c b/src/VBox/Runtime/r0drv/solaris/semfastmutex-r0drv-solaris.c
new file mode 100644
index 00000000..d2fa43d3
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/semfastmutex-r0drv-solaris.c
@@ -0,0 +1,120 @@
+/* $Id: semfastmutex-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Fast Mutex Semaphores, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-solaris-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/semaphore.h>
+
+#include <iprt/asm.h>
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+#include <iprt/mem.h>
+#include <iprt/thread.h>
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Wrapper for the Solaris mutex.
+ */
+typedef struct RTSEMFASTMUTEXINTERNAL
+{
+    /** Magic value (RTSEMFASTMUTEX_MAGIC). */
+    uint32_t            u32Magic;
+    /** The Solaris mutex. */
+    krwlock_t           Mtx;
+} RTSEMFASTMUTEXINTERNAL, *PRTSEMFASTMUTEXINTERNAL;
+
+
+
+RTDECL(int)  RTSemFastMutexCreate(PRTSEMFASTMUTEX phFastMtx)
+{
+    AssertCompile(sizeof(RTSEMFASTMUTEXINTERNAL) > sizeof(void *));
+    AssertPtrReturn(phFastMtx, VERR_INVALID_POINTER);
+    RT_ASSERT_PREEMPTIBLE();
+
+    PRTSEMFASTMUTEXINTERNAL pThis = (PRTSEMFASTMUTEXINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (pThis)
+    {
+        pThis->u32Magic = RTSEMFASTMUTEX_MAGIC;
+        rw_init (&pThis->Mtx, "RWLOCK", RW_DRIVER, NULL);
+
+        *phFastMtx = pThis;
+        return VINF_SUCCESS;
+    }
+    return VERR_NO_MEMORY;
+}
+
+
+RTDECL(int)  RTSemFastMutexDestroy(RTSEMFASTMUTEX hFastMtx)
+{
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    if (pThis == NIL_RTSEMFASTMUTEX)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+    RT_ASSERT_INTS_ON();
+
+    ASMAtomicXchgU32(&pThis->u32Magic, RTSEMFASTMUTEX_MAGIC_DEAD);
+    rw_destroy(&pThis->Mtx);
+    RTMemFree(pThis);
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemFastMutexRequest(RTSEMFASTMUTEX hFastMtx)
+{
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+    RT_ASSERT_PREEMPTIBLE();
+
+    rw_enter(&pThis->Mtx, RW_WRITER);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSemFastMutexRelease(RTSEMFASTMUTEX hFastMtx)
+{
+    PRTSEMFASTMUTEXINTERNAL pThis = hFastMtx;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMFASTMUTEX_MAGIC, ("%p: u32Magic=%RX32\n", pThis, pThis->u32Magic), VERR_INVALID_HANDLE);
+    RT_ASSERT_INTS_ON();
+
+    rw_exit(&pThis->Mtx);
+    return VINF_SUCCESS;
+}
+
diff --git a/src/VBox/Runtime/r0drv/solaris/semmutex-r0drv-solaris.c b/src/VBox/Runtime/r0drv/solaris/semmutex-r0drv-solaris.c
new file mode 100644
index 00000000..6a3b4576
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/semmutex-r0drv-solaris.c
@@ -0,0 +1,387 @@
+/* $Id: semmutex-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Mutex Semaphores, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTSEMMUTEX_WITHOUT_REMAPPING
+#include "the-solaris-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/semaphore.h>
+
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/mem.h>
+#include <iprt/err.h>
+#include <iprt/list.h>
+#include <iprt/thread.h>
+
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Wrapper for the solaris semaphore structure.
+ */
+typedef struct RTSEMMUTEXINTERNAL
+{
+    /** Magic value (RTSEMMUTEX_MAGIC). */
+    uint32_t                    u32Magic;
+    /** The number of recursions. */
+    uint32_t                    cRecursions;
+    /** The number of threads waiting for the mutex. */
+    uint32_t volatile           cWaiters;
+    /** The number of threads referencing us. */
+    uint32_t volatile           cRefs;
+    /** The owner thread, NIL_RTNATIVETHREAD if none. */
+    RTNATIVETHREAD              hOwnerThread;
+    /** The mutex object for synchronization. */
+    kmutex_t                    Mtx;
+    /** The condition variable for synchronization. */
+    kcondvar_t                  Cnd;
+} RTSEMMUTEXINTERNAL, *PRTSEMMUTEXINTERNAL;
+
+
+RTDECL(int) RTSemMutexCreate(PRTSEMMUTEX phMtx)
+{
+    /*
+     * Allocate.
+     */
+    PRTSEMMUTEXINTERNAL pThis = (PRTSEMMUTEXINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (RT_UNLIKELY(!pThis))
+        return VERR_NO_MEMORY;
+
+    /*
+     * Initialize.
+     */
+    pThis->u32Magic     = RTSEMMUTEX_MAGIC;
+    pThis->cRecursions  = 0;
+    pThis->cWaiters     = 0;
+    pThis->cRefs        = 1;
+    pThis->hOwnerThread = NIL_RTNATIVETHREAD;
+    mutex_init(&pThis->Mtx, "IPRT Mutex", MUTEX_DRIVER, (void *)ipltospl(DISP_LEVEL));
+    cv_init(&pThis->Cnd, "IPRT CVM", CV_DRIVER, NULL);
+    *phMtx = pThis;
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTSemMutexDestroy(RTSEMMUTEX hMtx)
+{
+    PRTSEMMUTEXINTERNAL     pThis = hMtx;
+
+    /*
+     * Validate.
+     */
+    if (pThis == NIL_RTSEMMUTEX)
+        return VINF_SUCCESS;
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+
+    mutex_enter(&pThis->Mtx);
+
+    ASMAtomicDecU32(&pThis->cRefs);
+
+    /*
+     * Invalidate the magic to indicate the mutex is being destroyed.
+     */
+    ASMAtomicIncU32(&pThis->u32Magic);
+    if (pThis->cWaiters > 0)
+    {
+        /*
+         * Wake up all waiters, last waiter thread cleans up.
+         */
+        cv_broadcast(&pThis->Cnd);
+        mutex_exit(&pThis->Mtx);
+    }
+    else if (pThis->cRefs == 0)
+    {
+        /*
+         * We're the last waiter, destroy.
+         */
+        mutex_exit(&pThis->Mtx);
+        cv_destroy(&pThis->Cnd);
+        mutex_destroy(&pThis->Mtx);
+        RTMemFree(pThis);
+    }
+    else
+    {
+        /*
+         * We're not the last waiting thread to be woken up. Just relinquish & bail.
+         */
+        mutex_exit(&pThis->Mtx);
+    }
+
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Worker for rtSemMutexSolRequest that handles the case where we go to sleep.
+ *
+ * @returns VINF_SUCCESS, VERR_INTERRUPTED, or VERR_SEM_DESTROYED.
+ *          Returns without owning the mutex.
+ * @param   pThis           The mutex instance.
+ * @param   cMillies        The timeout, must be > 0 or RT_INDEFINITE_WAIT.
+ * @param   fInterruptible  The wait type.
+ *
+ * @remarks This needs to be called with the mutex object held!
+ */
+static int rtSemMutexSolRequestSleep(PRTSEMMUTEXINTERNAL pThis, RTMSINTERVAL cMillies,
+                                       bool fInterruptible)
+{
+    int rc = VERR_GENERAL_FAILURE;
+    Assert(cMillies > 0);
+
+    /*
+     * Now we wait (sleep; although might spin and then sleep) & reference the mutex.
+     */
+    ASMAtomicIncU32(&pThis->cWaiters);
+    ASMAtomicIncU32(&pThis->cRefs);
+
+    if (cMillies != RT_INDEFINITE_WAIT)
+    {
+        clock_t cTicks   = drv_usectohz((clock_t)(cMillies * 1000L));
+        clock_t cTimeout = ddi_get_lbolt();
+        cTimeout        += cTicks;
+        if (fInterruptible)
+            rc = cv_timedwait_sig(&pThis->Cnd, &pThis->Mtx, cTimeout);
+        else
+            rc = cv_timedwait(&pThis->Cnd, &pThis->Mtx, cTimeout);
+    }
+    else
+    {
+        if (fInterruptible)
+            rc = cv_wait_sig(&pThis->Cnd, &pThis->Mtx);
+        else
+        {
+            cv_wait(&pThis->Cnd, &pThis->Mtx);
+            rc = 1;
+        }
+    }
+
+    ASMAtomicDecU32(&pThis->cWaiters);
+    if (rc > 0)
+    {
+        if (pThis->u32Magic == RTSEMMUTEX_MAGIC)
+        {
+            if (pThis->hOwnerThread == NIL_RTNATIVETHREAD)
+            {
+                /*
+                 * Woken up by a release from another thread.
+                 */
+                Assert(pThis->cRecursions == 0);
+                pThis->cRecursions = 1;
+                pThis->hOwnerThread = RTThreadNativeSelf();
+                rc = VINF_SUCCESS;
+            }
+            else
+            {
+                /*
+                 * Interrupted by some signal.
+                 */
+                rc = VERR_INTERRUPTED;
+            }
+        }
+        else
+        {
+            /*
+             * Awakened due to the destruction-in-progress broadcast.
+             * We will cleanup if we're the last waiter.
+             */
+            rc = VERR_SEM_DESTROYED;
+        }
+    }
+    else if (rc == -1)
+    {
+        /*
+         * Timed out.
+         */
+        rc = VERR_TIMEOUT;
+    }
+    else
+    {
+        /*
+         * Condition may not have been met, returned due to pending signal.
+         */
+        rc = VERR_INTERRUPTED;
+    }
+
+    if (!ASMAtomicDecU32(&pThis->cRefs))
+    {
+        Assert(RT_FAILURE_NP(rc));
+        mutex_exit(&pThis->Mtx);
+        cv_destroy(&pThis->Cnd);
+        mutex_destroy(&pThis->Mtx);
+        RTMemFree(pThis);
+        return rc;
+    }
+
+    return rc;
+}
+
+
+/**
+ * Internal worker.
+ */
+DECLINLINE(int) rtSemMutexSolRequest(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, bool fInterruptible)
+{
+    PRTSEMMUTEXINTERNAL pThis = hMutexSem;
+    int rc = VERR_GENERAL_FAILURE;
+
+    /*
+     * Validate.
+     */
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+    Assert(pThis->cRefs >= 1);
+
+    /*
+     * Lock it and check if it's a recursion.
+     */
+    mutex_enter(&pThis->Mtx);
+    if (pThis->hOwnerThread == RTThreadNativeSelf())
+    {
+        pThis->cRecursions++;
+        Assert(pThis->cRecursions > 1);
+        Assert(pThis->cRecursions < 256);
+        rc = VINF_SUCCESS;
+    }
+    /*
+     * Not a recursion, claim the unowned mutex if we're there are no waiters.
+     */
+    else if (   pThis->hOwnerThread == NIL_RTNATIVETHREAD
+             && pThis->cWaiters == 0)
+    {
+        pThis->cRecursions  = 1;
+        pThis->hOwnerThread = RTThreadNativeSelf();
+        rc = VINF_SUCCESS;
+    }
+    /*
+     * A polling call?
+     */
+    else if (cMillies == 0)
+        rc = VERR_TIMEOUT;
+    /*
+     * No, we really need to get to sleep.
+     */
+    else
+        rc = rtSemMutexSolRequestSleep(pThis, cMillies, fInterruptible);
+
+    mutex_exit(&pThis->Mtx);
+    return rc;
+}
+
+
+RTDECL(int) RTSemMutexRequest(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies)
+{
+    return rtSemMutexSolRequest(hMutexSem, cMillies, false /*fInterruptible*/);
+}
+
+
+RTDECL(int) RTSemMutexRequestDebug(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    return RTSemMutexRequest(hMutexSem, cMillies);
+}
+
+
+RTDECL(int) RTSemMutexRequestNoResume(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies)
+{
+    return rtSemMutexSolRequest(hMutexSem, cMillies, true /*fInterruptible*/);
+}
+
+
+RTDECL(int) RTSemMutexRequestNoResumeDebug(RTSEMMUTEX hMutexSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    return RTSemMutexRequestNoResume(hMutexSem, cMillies);
+}
+
+
+RTDECL(int) RTSemMutexRelease(RTSEMMUTEX hMtx)
+{
+    PRTSEMMUTEXINTERNAL pThis = hMtx;
+    int                 rc;
+
+    /*
+     * Validate.
+     */
+    AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), VERR_INVALID_HANDLE);
+
+    /*
+     * Take the lock and release one recursion.
+     */
+    mutex_enter(&pThis->Mtx);
+    if (pThis->hOwnerThread == RTThreadNativeSelf())
+    {
+        Assert(pThis->cRecursions > 0);
+        if (--pThis->cRecursions == 0)
+        {
+            pThis->hOwnerThread = NIL_RTNATIVETHREAD;
+
+            /*
+             * If there are any waiters, signal one of them.
+             */
+            if (pThis->cWaiters > 0)
+                cv_signal(&pThis->Cnd);
+        }
+        rc = VINF_SUCCESS;
+    }
+    else
+        rc = VERR_NOT_OWNER;
+
+    mutex_exit(&pThis->Mtx);
+    return rc;
+}
+
+
+RTDECL(bool) RTSemMutexIsOwned(RTSEMMUTEX hMutexSem)
+{
+    PRTSEMMUTEXINTERNAL pThis = hMutexSem;
+    bool fOwned = false;
+
+    /*
+     * Validate.
+     */
+    AssertPtrReturn(pThis, false);
+    AssertMsgReturn(pThis->u32Magic == RTSEMMUTEX_MAGIC, ("u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis), false);
+
+    /*
+     * Check if this is the owner.
+     */
+    mutex_enter(&pThis->Mtx);
+    fOwned = pThis->hOwnerThread != NIL_RTNATIVETHREAD;
+    mutex_exit(&pThis->Mtx);
+
+    return fOwned;
+}
+
diff --git a/src/VBox/Runtime/r0drv/solaris/spinlock-r0drv-solaris.c b/src/VBox/Runtime/r0drv/solaris/spinlock-r0drv-solaris.c
new file mode 100644
index 00000000..4e0f2d1b
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/spinlock-r0drv-solaris.c
@@ -0,0 +1,204 @@
+/* $Id: spinlock-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Spinlocks, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-solaris-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/spinlock.h>
+
+#include <iprt/asm.h>
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+#include <iprt/mem.h>
+#include <iprt/mp.h>
+#include <iprt/thread.h>
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Wrapper for the struct mutex type.
+ */
+typedef struct RTSPINLOCKINTERNAL
+{
+    /** Spinlock magic value (RTSPINLOCK_MAGIC). */
+    uint32_t volatile   u32Magic;
+    /** Spinlock creation flags.  */
+    uint32_t            fFlags;
+    /** Saved interrupt flag. */
+    uint32_t volatile   fIntSaved;
+    /** A Solaris spinlock. */
+    kmutex_t            Mtx;
+#ifdef RT_MORE_STRICT
+    /** The idAssertCpu variable before acquring the lock for asserting after
+     *  releasing the spinlock. */
+    RTCPUID volatile    idAssertCpu;
+    /** The CPU that owns the lock. */
+    RTCPUID volatile    idCpuOwner;
+#endif
+} RTSPINLOCKINTERNAL, *PRTSPINLOCKINTERNAL;
+
+
+
+RTDECL(int)  RTSpinlockCreate(PRTSPINLOCK pSpinlock, uint32_t fFlags, const char *pszName)
+{
+    RT_ASSERT_PREEMPTIBLE();
+    AssertReturn(fFlags == RTSPINLOCK_FLAGS_INTERRUPT_SAFE || fFlags == RTSPINLOCK_FLAGS_INTERRUPT_UNSAFE, VERR_INVALID_PARAMETER);
+
+    /*
+     * Allocate.
+     */
+    AssertCompile(sizeof(RTSPINLOCKINTERNAL) > sizeof(void *));
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)RTMemAlloc(sizeof(*pThis));
+    if (!pThis)
+        return VERR_NO_MEMORY;
+
+    /*
+     * Initialize & return.
+     */
+    pThis->u32Magic  = RTSPINLOCK_MAGIC;
+    pThis->fFlags    = fFlags;
+    pThis->fIntSaved = 0;
+    /** @todo Consider different PIL when not interrupt safe requirement. */
+    mutex_init(&pThis->Mtx, "IPRT Spinlock", MUTEX_SPIN, (void *)ipltospl(PIL_MAX));
+    *pSpinlock = pThis;
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int)  RTSpinlockDestroy(RTSPINLOCK Spinlock)
+{
+    /*
+     * Validate input.
+     */
+    RT_ASSERT_INTS_ON();
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
+    if (!pThis)
+        return VERR_INVALID_PARAMETER;
+    AssertMsgReturn(pThis->u32Magic == RTSPINLOCK_MAGIC,
+                    ("Invalid spinlock %p magic=%#x\n", pThis, pThis->u32Magic),
+                    VERR_INVALID_PARAMETER);
+
+    /*
+     * Make the lock invalid and release the memory.
+     */
+    ASMAtomicIncU32(&pThis->u32Magic);
+    mutex_destroy(&pThis->Mtx);
+    RTMemFree(pThis);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(void) RTSpinlockAcquire(RTSPINLOCK Spinlock)
+{
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
+    RT_ASSERT_PREEMPT_CPUID_VAR();
+    AssertPtr(pThis);
+    Assert(pThis->u32Magic == RTSPINLOCK_MAGIC);
+
+    if (pThis->fFlags & RTSPINLOCK_FLAGS_INTERRUPT_SAFE)
+    {
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+        uint32_t fIntSaved = ASMIntDisableFlags();
+#endif
+        mutex_enter(&pThis->Mtx);
+
+        /*
+         * Solaris 10 doesn't preserve the interrupt flag, but since we're at PIL_MAX we should be
+         * fine and not get interrupts while lock is held. Re-disable interrupts to not upset
+         * assertions & assumptions callers might have.
+         */
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+        ASMIntDisable();
+#endif
+
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+        Assert(!ASMIntAreEnabled());
+#endif
+        pThis->fIntSaved = fIntSaved;
+    }
+    else
+    {
+#if defined(RT_STRICT) && (defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86))
+        bool fIntsOn = ASMIntAreEnabled();
+#endif
+
+        mutex_enter(&pThis->Mtx);
+
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+        AssertMsg(fIntsOn == ASMIntAreEnabled(), ("fIntsOn=%RTbool\n", fIntsOn));
+#endif
+    }
+
+    RT_ASSERT_PREEMPT_CPUID_SPIN_ACQUIRED(pThis);
+}
+
+
+RTDECL(void) RTSpinlockRelease(RTSPINLOCK Spinlock)
+{
+    PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
+    RT_ASSERT_PREEMPT_CPUID_SPIN_RELEASE_VARS();
+
+    AssertPtr(pThis);
+    Assert(pThis->u32Magic == RTSPINLOCK_MAGIC);
+    RT_ASSERT_PREEMPT_CPUID_SPIN_RELEASE(pThis);
+
+    if (pThis->fFlags & RTSPINLOCK_FLAGS_INTERRUPT_SAFE)
+    {
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+        uint32_t fIntSaved = pThis->fIntSaved;
+        pThis->fIntSaved = 0;
+#endif
+        mutex_exit(&pThis->Mtx);
+
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+        ASMSetFlags(fIntSaved);
+#endif
+    }
+    else
+    {
+#if defined(RT_STRICT) && (defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86))
+        bool fIntsOn = ASMIntAreEnabled();
+#endif
+
+        mutex_exit(&pThis->Mtx);
+
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+        AssertMsg(fIntsOn == ASMIntAreEnabled(), ("fIntsOn=%RTbool\n", fIntsOn));
+#endif
+    }
+
+    RT_ASSERT_PREEMPT_CPUID();
+}
+
diff --git a/src/VBox/Runtime/r0drv/solaris/the-solaris-kernel.h b/src/VBox/Runtime/r0drv/solaris/the-solaris-kernel.h
new file mode 100644
index 00000000..4a69c979
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/the-solaris-kernel.h
@@ -0,0 +1,234 @@
+/* $Id: the-solaris-kernel.h $ */
+/** @file
+ * IPRT - Include all necessary headers for the Solaris kernel.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+#ifndef IPRT_INCLUDED_SRC_r0drv_solaris_the_solaris_kernel_h
+#define IPRT_INCLUDED_SRC_r0drv_solaris_the_solaris_kernel_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <sys/kmem.h>
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <sys/thread.h>
+#include <sys/mutex.h>
+#include <sys/condvar.h>
+#include <sys/sdt.h>
+#include <sys/schedctl.h>
+#include <sys/time.h>
+#include <sys/sysmacros.h>
+#include <sys/cmn_err.h>
+#include <sys/vmsystm.h>
+#include <sys/cyclic.h>
+#include <sys/class.h>
+#include <sys/cpuvar.h>
+#include <sys/archsystm.h>
+#include <sys/x_call.h> /* in platform dir */
+#include <sys/x86_archext.h>
+#include <vm/hat.h>
+#include <vm/seg_vn.h>
+#include <vm/seg_kmem.h>
+#include <vm/page.h>
+#include <sys/ddi.h>
+#include <sys/sunddi.h>
+#include <sys/spl.h>
+#include <sys/archsystm.h>
+#include <sys/callo.h>
+#include <sys/kobj.h>
+#include <sys/ctf_api.h>
+#include <sys/modctl.h>
+#include <sys/proc.h>
+#include <sys/t_lock.h>
+
+#undef u /* /usr/include/sys/user.h:249:1 is where this is defined to (curproc->p_user). very cool. */
+
+#include <iprt/cdefs.h>
+#include <iprt/types.h>
+#include <iprt/dbg.h>
+
+RT_C_DECLS_BEGIN
+
+/* IPRT functions. */
+DECLHIDDEN(void *)   rtR0SolMemAlloc(uint64_t cbPhysHi, uint64_t *puPhys, size_t cb, uint64_t cbAlign, bool fContig);
+DECLHIDDEN(void)     rtR0SolMemFree(void *pv, size_t cb);
+
+
+/* Solaris functions. */
+typedef callout_id_t (*PFNSOL_timeout_generic)(int type, void (*func)(void *),
+                                               void *arg, hrtime_t expiration,
+                                               hrtime_t resultion, int flags);
+typedef hrtime_t     (*PFNSOL_untimeout_generic)(callout_id_t id, int nowait);
+typedef int          (*PFNSOL_cyclic_reprogram)(cyclic_id_t id, hrtime_t expiration);
+typedef void         (*PFNSOL_contig_free)(void *addr, size_t size);
+typedef int          (*PFNSOL_page_noreloc_supported)(size_t cbPageSize);
+
+/* IPRT globals. */
+extern bool                            g_frtSolSplSetsEIF;
+extern RTCPUSET                        g_rtMpSolCpuSet;
+extern PFNSOL_timeout_generic          g_pfnrtR0Sol_timeout_generic;
+extern PFNSOL_untimeout_generic        g_pfnrtR0Sol_untimeout_generic;
+extern PFNSOL_cyclic_reprogram         g_pfnrtR0Sol_cyclic_reprogram;
+extern PFNSOL_contig_free              g_pfnrtR0Sol_contig_free;
+extern PFNSOL_page_noreloc_supported   g_pfnrtR0Sol_page_noreloc_supported;
+extern size_t                          g_offrtSolThreadPreempt;
+extern size_t                          g_offrtSolThreadIntrThread;
+extern size_t                          g_offrtSolThreadLock;
+extern size_t                          g_offrtSolThreadProc;
+extern size_t                          g_offrtSolThreadId;
+extern size_t                          g_offrtSolCpuPreempt;
+extern size_t                          g_offrtSolCpuForceKernelPreempt;
+extern bool                            g_frtSolInitDone;
+extern RTDBGKRNLINFO                   g_hKrnlDbgInfo;
+
+/*
+ * Workarounds for running on old versions of solaris with different cross call
+ * interfaces. If we find xc_init_cpu() in the kernel, then just use the
+ * defined interfaces for xc_call() from the include file where the xc_call()
+ * interfaces just takes a pointer to a ulong_t array. The array must be long
+ * enough to hold "ncpus" bits at runtime.
+
+ * The reason for the hacks is that using the type "cpuset_t" is pretty much
+ * impossible from code built outside the Solaris source repository that wants
+ * to run on multiple releases of Solaris.
+ *
+ * For old style xc_call()s, 32 bit solaris and older 64 bit versions use
+ * "ulong_t" as cpuset_t.
+ *
+ * Later versions of 64 bit Solaris used: struct {ulong_t words[x];}
+ * where "x" depends on NCPU.
+ *
+ * We detect the difference in 64 bit support by checking the kernel value of
+ * max_cpuid, which always holds the compiled value of NCPU - 1.
+ *
+ * If Solaris increases NCPU to more than 256, VBox will continue to work on
+ * all versions of Solaris as long as the number of installed CPUs in the
+ * machine is <= IPRT_SOLARIS_NCPUS. If IPRT_SOLARIS_NCPUS is increased, this
+ * code has to be re-written some to provide compatibility with older Solaris
+ * which expects cpuset_t to be based on NCPU==256 -- or we discontinue
+ * support of old Nevada/S10.
+ */
+#define IPRT_SOL_NCPUS          256
+#define IPRT_SOL_SET_WORDS      (IPRT_SOL_NCPUS / (sizeof(ulong_t) * 8))
+#define IPRT_SOL_X_CALL_HIPRI   (2) /* for Old Solaris interface */
+typedef struct RTSOLCPUSET
+{
+    ulong_t                     auCpus[IPRT_SOL_SET_WORDS];
+} RTSOLCPUSET;
+typedef RTSOLCPUSET *PRTSOLCPUSET;
+
+/* Avoid warnings even if it means more typing... */
+typedef struct RTR0FNSOLXCCALL
+{
+    union
+    {
+        void *(*pfnSol_xc_call)          (xc_arg_t, xc_arg_t, xc_arg_t, ulong_t *, xc_func_t);
+        void *(*pfnSol_xc_call_old)      (xc_arg_t, xc_arg_t, xc_arg_t, int, RTSOLCPUSET, xc_func_t);
+        void *(*pfnSol_xc_call_old_ulong)(xc_arg_t, xc_arg_t, xc_arg_t, int, ulong_t, xc_func_t);
+    } u;
+} RTR0FNSOLXCCALL;
+typedef RTR0FNSOLXCCALL *PRTR0FNSOLXCCALL;
+
+extern RTR0FNSOLXCCALL          g_rtSolXcCall;
+extern bool                     g_frtSolOldIPI;
+extern bool                     g_frtSolOldIPIUlong;
+
+/*
+ * Thread-context hooks.
+ * Workarounds for older Solaris versions that did not have the exitctx() callback.
+ */
+typedef struct RTR0FNSOLTHREADCTX
+{
+    union
+    {
+        void *(*pfnSol_installctx)        (kthread_t *pThread, void *pvArg,
+                                           void (*pfnSave)(void *pvArg),
+                                           void (*pfnRestore)(void *pvArg),
+                                           void (*pfnFork)(void *pvThread, void *pvThreadFork),
+                                           void (*pfnLwpCreate)(void *pvThread, void *pvThreadCreate),
+                                           void (*pfnExit)(void *pvThread),
+                                           void (*pfnFree)(void *pvArg, int fIsExec));
+
+        void *(*pfnSol_installctx_old)    (kthread_t *pThread, void *pvArg,
+                                           void (*pfnSave)(void *pvArg),
+                                           void (*pfnRestore)(void *pvArg),
+                                           void (*pfnFork)(void *pvThread, void *pvThreadFork),
+                                           void (*pfnLwpCreate)(void *pvThread, void *pvThreadCreate),
+                                           void (*pfnFree)(void *pvArg, int fIsExec));
+    } Install;
+
+    union
+    {
+        int (*pfnSol_removectx)           (kthread_t *pThread, void *pvArg,
+                                           void (*pfnSave)(void *pvArg),
+                                           void (*pfnRestore)(void *pvArg),
+                                           void (*pfnFork)(void *pvThread, void *pvThreadFork),
+                                           void (*pfnLwpCreate)(void *pvThread, void *pvThreadCreate),
+                                           void (*pfnExit)(void *pvThread),
+                                           void (*pfnFree)(void *pvArg, int fIsExec));
+
+        int (*pfnSol_removectx_old)       (kthread_t *pThread, void *pvArg,
+                                           void (*pfnSave)(void *pvArg),
+                                           void (*pfnRestore)(void *pvArg),
+                                           void (*pfnFork)(void *pvThread, void *pvThreadFork),
+                                           void (*pfnLwpCreate)(void *pvThread, void *pvThreadCreate),
+                                           void (*pfnFree)(void *pvArg, int fIsExec));
+    } Remove;
+} RTR0FNSOLTHREADCTX;
+typedef RTR0FNSOLTHREADCTX *PRTR0FNSOLTHREADCTX;
+
+extern RTR0FNSOLTHREADCTX       g_rtSolThreadCtx;
+extern bool                     g_frtSolOldThreadCtx;
+
+/*
+ * Workaround for older Solaris versions which called map_addr()/choose_addr()/
+ * map_addr_proc() with an 'alignment' argument that was removed in Solaris
+ * 11.4.
+ */
+typedef struct RTR0FNSOLMAPADDR
+{
+    union
+    {
+        void *(*pfnSol_map_addr)          (caddr_t *, size_t, offset_t, uint_t);
+        void *(*pfnSol_map_addr_old)      (caddr_t *, size_t, offset_t, int, uint_t);
+    } u;
+} RTR0FNSOLMAPADDR;
+typedef RTR0FNSOLMAPADDR *PRTR0FNSOLMAPADDR;
+
+extern RTR0FNSOLMAPADDR         g_rtSolMapAddr;
+extern bool                     g_frtSolOldMapAddr;
+
+/* Solaris globals. */
+extern uintptr_t                kernelbase;
+
+/* Misc stuff from newer kernels. */
+#ifndef CALLOUT_FLAG_ABSOLUTE
+# define CALLOUT_FLAG_ABSOLUTE 2
+#endif
+
+RT_C_DECLS_END
+
+#endif /* !IPRT_INCLUDED_SRC_r0drv_solaris_the_solaris_kernel_h */
+
diff --git a/src/VBox/Runtime/r0drv/solaris/thread-r0drv-solaris.c b/src/VBox/Runtime/r0drv/solaris/thread-r0drv-solaris.c
new file mode 100644
index 00000000..a7782046
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/thread-r0drv-solaris.c
@@ -0,0 +1,185 @@
+/* $Id: thread-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Threads, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-solaris-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/thread.h>
+
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+#include <iprt/mp.h>
+
+#define SOL_THREAD_PREEMPT       (*((char *)curthread + g_offrtSolThreadPreempt))
+#define SOL_CPU_RUNRUN           (*((char *)CPU + g_offrtSolCpuPreempt))
+#define SOL_CPU_KPRUNRUN         (*((char *)CPU + g_offrtSolCpuForceKernelPreempt))
+
+RTDECL(RTNATIVETHREAD) RTThreadNativeSelf(void)
+{
+    return (RTNATIVETHREAD)curthread;
+}
+
+
+static int rtR0ThreadSolSleepCommon(RTMSINTERVAL cMillies)
+{
+    clock_t cTicks;
+    RT_ASSERT_PREEMPTIBLE();
+
+    if (!cMillies)
+    {
+        RTThreadYield();
+        return VINF_SUCCESS;
+    }
+
+    if (cMillies != RT_INDEFINITE_WAIT)
+        cTicks = drv_usectohz((clock_t)(cMillies * 1000L));
+    else
+        cTicks = 0;
+
+    delay(cTicks);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTThreadSleep(RTMSINTERVAL cMillies)
+{
+    return rtR0ThreadSolSleepCommon(cMillies);
+}
+
+
+RTDECL(int) RTThreadSleepNoLog(RTMSINTERVAL cMillies)
+{
+    return rtR0ThreadSolSleepCommon(cMillies);
+}
+
+
+RTDECL(bool) RTThreadYield(void)
+{
+    RT_ASSERT_PREEMPTIBLE();
+
+    RTTHREADPREEMPTSTATE PreemptState = RTTHREADPREEMPTSTATE_INITIALIZER;
+    RTThreadPreemptDisable(&PreemptState);
+
+    char const bThreadPreempt = SOL_THREAD_PREEMPT;
+    char const bForcePreempt  = SOL_CPU_KPRUNRUN;
+    bool fWillYield = false;
+    Assert(bThreadPreempt >= 1);
+
+    /*
+     * If we are the last preemption enabler for this thread and if force
+     * preemption is set on the CPU, only then we are guaranteed to be preempted.
+     */
+    if (bThreadPreempt == 1 && bForcePreempt != 0)
+        fWillYield = true;
+
+    RTThreadPreemptRestore(&PreemptState);
+    return fWillYield;
+}
+
+
+RTDECL(bool) RTThreadPreemptIsEnabled(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD);
+    if (RT_UNLIKELY(g_frtSolInitDone == false))
+    {
+        cmn_err(CE_CONT, "!RTThreadPreemptIsEnabled called before RTR0Init!\n");
+        return true;
+    }
+
+    bool fThreadPreempt = false;
+    if (SOL_THREAD_PREEMPT == 0)
+        fThreadPreempt = true;
+
+    if (!fThreadPreempt)
+        return false;
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+    if (!ASMIntAreEnabled())
+        return false;
+#endif
+    if (getpil() >= DISP_LEVEL)
+        return false;
+    return true;
+}
+
+
+RTDECL(bool) RTThreadPreemptIsPending(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD);
+
+    char const bPreempt      = SOL_CPU_RUNRUN;
+    char const bForcePreempt = SOL_CPU_KPRUNRUN;
+    return (bPreempt != 0 || bForcePreempt != 0);
+}
+
+
+RTDECL(bool) RTThreadPreemptIsPendingTrusty(void)
+{
+    /* yes, RTThreadPreemptIsPending is reliable. */
+    return true;
+}
+
+
+RTDECL(bool) RTThreadPreemptIsPossible(void)
+{
+    /* yes, kernel preemption is possible. */
+    return true;
+}
+
+
+RTDECL(void) RTThreadPreemptDisable(PRTTHREADPREEMPTSTATE pState)
+{
+    AssertPtr(pState);
+
+    SOL_THREAD_PREEMPT++;
+    Assert(SOL_THREAD_PREEMPT >= 1);
+
+    RT_ASSERT_PREEMPT_CPUID_DISABLE(pState);
+}
+
+
+RTDECL(void) RTThreadPreemptRestore(PRTTHREADPREEMPTSTATE pState)
+{
+    AssertPtr(pState);
+    RT_ASSERT_PREEMPT_CPUID_RESTORE(pState);
+
+    Assert(SOL_THREAD_PREEMPT >= 1);
+    if (--SOL_THREAD_PREEMPT == 0 && SOL_CPU_RUNRUN != 0)
+        kpreempt(KPREEMPT_SYNC);
+}
+
+
+RTDECL(bool) RTThreadIsInInterrupt(RTTHREAD hThread)
+{
+    Assert(hThread == NIL_RTTHREAD);
+    return servicing_interrupt() ? true : false;
+}
+
diff --git a/src/VBox/Runtime/r0drv/solaris/thread2-r0drv-solaris.c b/src/VBox/Runtime/r0drv/solaris/thread2-r0drv-solaris.c
new file mode 100644
index 00000000..c70b7c3f
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/thread2-r0drv-solaris.c
@@ -0,0 +1,150 @@
+/* $Id: thread2-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Threads (Part 2), Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-solaris-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/thread.h>
+#include <iprt/process.h>
+
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+#include "internal/thread.h"
+
+#define SOL_THREAD_ID_PTR           ((uint64_t *)((char *)curthread + g_offrtSolThreadId))
+#define SOL_THREAD_LOCKP_PTR        ((disp_lock_t **)((char *)curthread + g_offrtSolThreadLock))
+
+DECLHIDDEN(int) rtThreadNativeInit(void)
+{
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(RTTHREAD) RTThreadSelf(void)
+{
+    return rtThreadGetByNative(RTThreadNativeSelf());
+}
+
+
+DECLHIDDEN(int) rtThreadNativeSetPriority(PRTTHREADINT pThread, RTTHREADTYPE enmType)
+{
+    int iPriority;
+    disp_lock_t **ppDispLock;
+    switch (enmType)
+    {
+        case RTTHREADTYPE_INFREQUENT_POLLER:    iPriority = 60;             break;
+        case RTTHREADTYPE_EMULATION:            iPriority = 66;             break;
+        case RTTHREADTYPE_DEFAULT:              iPriority = 72;             break;
+        case RTTHREADTYPE_MSG_PUMP:             iPriority = 78;             break;
+        case RTTHREADTYPE_IO:                   iPriority = 84;             break;
+        case RTTHREADTYPE_TIMER:                iPriority = 99;             break;
+        default:
+            AssertMsgFailed(("enmType=%d\n", enmType));
+            return VERR_INVALID_PARAMETER;
+    }
+
+    Assert(curthread);
+    thread_lock(curthread);
+    thread_change_pri(curthread, iPriority, 0);
+
+    /*
+     * thread_unlock() is a macro calling disp_lock_exit() with the thread's dispatcher lock.
+     * We need to dereference the offset manually here (for S10, S11 compatibility) rather than
+     * using the macro.
+     */
+    ppDispLock = SOL_THREAD_LOCKP_PTR;
+    disp_lock_exit(*ppDispLock);
+
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(int) rtThreadNativeAdopt(PRTTHREADINT pThread)
+{
+    NOREF(pThread);
+    /* There is nothing special that needs doing here, but the
+       user really better know what he's cooking. */
+    return VINF_SUCCESS;
+}
+
+
+DECLHIDDEN(void) rtThreadNativeWaitKludge(PRTTHREADINT pThread)
+{
+    thread_join(pThread->tid);
+}
+
+
+DECLHIDDEN(void) rtThreadNativeDestroy(PRTTHREADINT pThread)
+{
+    NOREF(pThread);
+}
+
+
+/**
+ * Native thread main function.
+ *
+ * @param   pvThreadInt     The thread structure.
+ */
+static void rtThreadNativeMain(void *pvThreadInt)
+{
+    PRTTHREADINT pThreadInt = (PRTTHREADINT)pvThreadInt;
+
+    AssertCompile(sizeof(kt_did_t) == sizeof(pThreadInt->tid));
+    uint64_t *pu64ThrId = SOL_THREAD_ID_PTR;
+    pThreadInt->tid = *pu64ThrId;
+    rtThreadMain(pThreadInt, RTThreadNativeSelf(), &pThreadInt->szName[0]);
+    thread_exit();
+}
+
+
+DECLHIDDEN(int) rtThreadNativeCreate(PRTTHREADINT pThreadInt, PRTNATIVETHREAD pNativeThread)
+{
+    kthread_t *pThread;
+    RT_ASSERT_PREEMPTIBLE();
+
+    pThreadInt->tid = UINT64_MAX;
+
+    pThread = thread_create(NULL,                            /* Stack, use base */
+                            0,                               /* Stack size */
+                            rtThreadNativeMain,              /* Thread function */
+                            pThreadInt,                      /* Function data */
+                            0,                               /* Data size */
+                            &p0,                             /* Process 0 handle */
+                            TS_RUN,                          /* Ready to run */
+                            minclsyspri                      /* Priority */
+                            );
+    if (RT_LIKELY(pThread))
+    {
+        *pNativeThread = (RTNATIVETHREAD)pThread;
+        return VINF_SUCCESS;
+    }
+
+    return VERR_OUT_OF_RESOURCES;
+}
+
diff --git a/src/VBox/Runtime/r0drv/solaris/threadctxhooks-r0drv-solaris.c b/src/VBox/Runtime/r0drv/solaris/threadctxhooks-r0drv-solaris.c
new file mode 100644
index 00000000..665549f0
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/threadctxhooks-r0drv-solaris.c
@@ -0,0 +1,349 @@
+/* $Id: threadctxhooks-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Thread Context Switching Hook, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2013-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-solaris-kernel.h"
+#include "internal/iprt.h"
+
+#include <iprt/mem.h>
+#include <iprt/assert.h>
+#include <iprt/thread.h>
+#include <iprt/errcore.h>
+#include <iprt/asm.h>
+#include <iprt/log.h>
+#include "internal/thread.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * The internal hook object for solaris.
+ */
+typedef struct RTTHREADCTXHOOKINT
+{
+    /** Magic value (RTTHREADCTXHOOKINT_MAGIC). */
+    uint32_t volatile           u32Magic;
+    /** The thread handle (owner) for which the context-hooks are registered. */
+    RTNATIVETHREAD              hOwner;
+    /** Pointer to the registered callback function. */
+    PFNRTTHREADCTXHOOK          pfnCallback;
+    /** User argument passed to the callback function. */
+    void                       *pvUser;
+    /** Whether the hook is enabled or not. */
+    bool volatile               fEnabled;
+    /** Number of references to this object. */
+    uint32_t volatile           cRefs;
+} RTTHREADCTXHOOKINT;
+typedef RTTHREADCTXHOOKINT *PRTTHREADCTXHOOKINT;
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+/** Validates a hook handle and returns rc if not valid. */
+#define RTTHREADCTX_VALID_RETURN_RC(pThis, rc) \
+    do { \
+        AssertPtrReturn((pThis), (rc)); \
+        AssertReturn((pThis)->u32Magic == RTTHREADCTXHOOKINT_MAGIC, (rc)); \
+        AssertReturn((pThis)->cRefs > 0, (rc)); \
+    } while (0)
+
+
+/**
+ * Hook function for the thread-save event.
+ *
+ * @param   pvThreadCtxInt  Opaque pointer to the internal hook object.
+ *
+ * @remarks Called with the with preemption disabled!
+ */
+static void rtThreadCtxHookSolOut(void *pvThreadCtxInt)
+{
+    PRTTHREADCTXHOOKINT pThis = (PRTTHREADCTXHOOKINT)pvThreadCtxInt;
+    AssertPtr(pThis);
+    Assert(!RTThreadPreemptIsEnabled(NIL_RTTHREAD));
+    Assert(pThis->cRefs > 0);
+
+    if (pThis->fEnabled)
+    {
+        Assert(pThis->pfnCallback);
+        pThis->pfnCallback(RTTHREADCTXEVENT_OUT, pThis->pvUser);
+    }
+}
+
+
+/**
+ * Hook function for the thread-restore event.
+ *
+ * @param   pvThreadCtxInt  Opaque pointer to the internal hook object.
+ *
+ * @remarks Called with preemption disabled!
+ */
+static void rtThreadCtxHookSolIn(void *pvThreadCtxInt)
+{
+    PRTTHREADCTXHOOKINT pThis = (PRTTHREADCTXHOOKINT)pvThreadCtxInt;
+    AssertPtr(pThis);
+    Assert(!RTThreadPreemptIsEnabled(NIL_RTTHREAD));
+    Assert(pThis->cRefs > 0);
+
+    if (pThis->fEnabled)
+    {
+        Assert(pThis->pfnCallback);
+        pThis->pfnCallback(RTTHREADCTXEVENT_IN, pThis->pvUser);
+    }
+}
+
+
+/**
+ * Hook function for the thread-free event.
+ *
+ * This is used for making sure the hook object is safely released - see
+ * RTThreadCtxHookRelease for details.
+ *
+ * @param   pvThreadCtxInt      Opaque pointer to the internal hook object.
+ * @param   fIsExec             Whether this event is triggered due to exec().
+ */
+static void rtThreadCtxHookSolFree(void *pvThreadCtxInt, int fIsExec)
+{
+    PRTTHREADCTXHOOKINT pThis = (PRTTHREADCTXHOOKINT)pvThreadCtxInt;
+    AssertPtrReturnVoid(pThis);
+    AssertMsgReturnVoid(pThis->u32Magic == RTTHREADCTXHOOKINT_MAGIC, ("pThis->u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis));
+
+    uint32_t cRefs = ASMAtomicReadU32(&pThis->cRefs);
+    if (cRefs > 0)
+    {
+        cRefs = ASMAtomicDecU32(&pThis->cRefs);
+        if (!cRefs)
+        {
+            Assert(!pThis->fEnabled);
+            ASMAtomicWriteU32(&pThis->u32Magic, ~RTTHREADCTXHOOKINT_MAGIC);
+            RTMemFree(pThis);
+        }
+    }
+    else
+    {
+        /* Should never happen. */
+        AssertMsgFailed(("rtThreadCtxHookSolFree with cRefs=0 pThis=%p\n", pThis));
+    }
+}
+
+
+RTDECL(int) RTThreadCtxHookCreate(PRTTHREADCTXHOOK phCtxHook, uint32_t fFlags, PFNRTTHREADCTXHOOK pfnCallback, void *pvUser)
+{
+    /*
+     * Validate input.
+     */
+    PRTTHREADCTXHOOKINT pThis;
+    Assert(RTThreadPreemptIsEnabled(NIL_RTTHREAD));
+    AssertPtrReturn(pfnCallback, VERR_INVALID_POINTER);
+    AssertReturn(fFlags == 0, VERR_INVALID_FLAGS);
+
+    /*
+     * Allocate and initialize a new hook.
+     */
+    pThis = (PRTTHREADCTXHOOKINT)RTMemAllocZ(sizeof(*pThis));
+    if (RT_UNLIKELY(!pThis))
+        return VERR_NO_MEMORY;
+    pThis->u32Magic     = RTTHREADCTXHOOKINT_MAGIC;
+    pThis->hOwner       = RTThreadNativeSelf();
+    pThis->pfnCallback  = pfnCallback;
+    pThis->pvUser       = pvUser;
+    pThis->fEnabled     = false;
+    pThis->cRefs        = 2;        /* One reference for the thread, one for the caller. */
+
+    /*
+     * installctx() allocates memory and thus cannot be used in RTThreadCtxHookRegister() which can be used
+     * with preemption disabled. We allocate the context-hooks here and use 'fEnabled' to determine if we can
+     * invoke the consumer's hook or not.
+     */
+    if (g_frtSolOldThreadCtx)
+    {
+        g_rtSolThreadCtx.Install.pfnSol_installctx_old(curthread,
+                                                       pThis,
+                                                       rtThreadCtxHookSolOut,   /* save */
+                                                       rtThreadCtxHookSolIn,    /* restore */
+                                                       NULL,                    /* fork */
+                                                       NULL,                    /* lwp_create */
+                                                       rtThreadCtxHookSolFree);
+    }
+    else
+    {
+        g_rtSolThreadCtx.Install.pfnSol_installctx(curthread,
+                                                   pThis,
+                                                   rtThreadCtxHookSolOut,       /* save */
+                                                   rtThreadCtxHookSolIn,        /* restore */
+                                                   NULL,                        /* fork */
+                                                   NULL,                        /* lwp_create */
+                                                   NULL,                        /* exit */
+                                                   rtThreadCtxHookSolFree);
+    }
+
+    *phCtxHook = pThis;
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTThreadCtxHookDestroy(RTTHREADCTXHOOK hCtxHook)
+{
+    /*
+     * Validate input, ignoring NIL.
+     */
+    PRTTHREADCTXHOOKINT pThis = hCtxHook;
+    if (pThis == NIL_RTTHREADCTXHOOK)
+        return VINF_SUCCESS;
+    RTTHREADCTX_VALID_RETURN_RC(hCtxHook, VERR_INVALID_HANDLE);
+    Assert(RTThreadPreemptIsEnabled(NIL_RTTHREAD));
+    Assert(!pThis->fEnabled || pThis->hOwner == RTThreadNativeSelf());
+
+    /*
+     * Make sure it's disabled.
+     */
+    ASMAtomicWriteBool(&pThis->fEnabled, false);
+
+    /*
+     * Decrement.
+     */
+    uint32_t cRefs = ASMAtomicDecU32(&pThis->cRefs);
+    if (   cRefs == 1
+        && pThis->hOwner == RTThreadNativeSelf())
+    {
+        /*
+         * removectx() will invoke rtThreadCtxHookSolFree() and there is no way to bypass it and still use
+         * rtThreadCtxHookSolFree() at the same time.  Hence the convulated reference counting.
+         *
+         * When this function is called from the owner thread and is the last reference, we call removectx() which
+         * will invoke rtThreadCtxHookSolFree() with cRefs = 1 and that will then free the hook object.
+         *
+         * When the function is called from a different thread, we simply decrement the reference. Whenever the
+         * ring-0 thread dies, Solaris will call rtThreadCtxHookSolFree() which will free the hook object.
+         */
+        int rc;
+        if (g_frtSolOldThreadCtx)
+        {
+            rc = g_rtSolThreadCtx.Remove.pfnSol_removectx_old(curthread,
+                                                              pThis,
+                                                              rtThreadCtxHookSolOut,    /* save */
+                                                              rtThreadCtxHookSolIn,     /* restore */
+                                                              NULL,                     /* fork */
+                                                              NULL,                     /* lwp_create */
+                                                              rtThreadCtxHookSolFree);
+        }
+        else
+        {
+            rc = g_rtSolThreadCtx.Remove.pfnSol_removectx(curthread,
+                                                          pThis,
+                                                          rtThreadCtxHookSolOut,        /* save */
+                                                          rtThreadCtxHookSolIn,         /* restore */
+                                                          NULL,                         /* fork */
+                                                          NULL,                         /* lwp_create */
+                                                          NULL,                         /* exit */
+                                                          rtThreadCtxHookSolFree);
+        }
+        AssertMsg(rc, ("removectx() failed. rc=%d\n", rc));
+        NOREF(rc);
+
+#if 0 /*def RT_STRICT - access after free */
+        cRefs = ASMAtomicReadU32(&pThis->cRefs);
+        Assert(!cRefs);
+#endif
+        cRefs = 0;
+    }
+    else if (!cRefs)
+    {
+        /*
+         * The ring-0 thread for this hook object has already died. Free up the object as we have no more references.
+         */
+        Assert(pThis->hOwner != RTThreadNativeSelf());
+        ASMAtomicWriteU32(&pThis->u32Magic, ~RTTHREADCTXHOOKINT_MAGIC);
+        RTMemFree(pThis);
+    }
+
+    return cRefs;
+}
+
+
+RTDECL(int) RTThreadCtxHookEnable(RTTHREADCTXHOOK hCtxHook)
+{
+    /*
+     * Validate input.
+     */
+    PRTTHREADCTXHOOKINT pThis = hCtxHook;
+    AssertPtr(pThis);
+    AssertMsgReturn(pThis->u32Magic == RTTHREADCTXHOOKINT_MAGIC, ("pThis->u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis),
+                    VERR_INVALID_HANDLE);
+    Assert(pThis->hOwner == RTThreadNativeSelf());
+    Assert(!pThis->fEnabled);
+
+    /*
+     * Mark it as enabled.
+     */
+    pThis->fEnabled = true;
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTThreadCtxHookDisable(RTTHREADCTXHOOK hCtxHook)
+{
+    /*
+     * Validate input.
+     */
+    PRTTHREADCTXHOOKINT pThis = hCtxHook;
+    if (pThis != NIL_RTTHREADCTXHOOK)
+    {
+        AssertPtr(pThis);
+        AssertMsgReturn(pThis->u32Magic == RTTHREADCTXHOOKINT_MAGIC, ("pThis->u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis),
+                        VERR_INVALID_HANDLE);
+        Assert(pThis->hOwner == RTThreadNativeSelf());
+
+        /*
+         * Mark it as disabled.
+         */
+        pThis->fEnabled = false;
+    }
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(bool) RTThreadCtxHookIsEnabled(RTTHREADCTXHOOK hCtxHook)
+{
+    /*
+     * Validate input.
+     */
+    PRTTHREADCTXHOOKINT pThis = hCtxHook;
+    if (pThis == NIL_RTTHREADCTXHOOK)
+        return false;
+    AssertPtr(pThis);
+    AssertMsgReturn(pThis->u32Magic == RTTHREADCTXHOOKINT_MAGIC, ("pThis->u32Magic=%RX32 pThis=%p\n", pThis->u32Magic, pThis),
+                    false);
+
+    return pThis->fEnabled;
+}
+
diff --git a/src/VBox/Runtime/r0drv/solaris/time-r0drv-solaris.c b/src/VBox/Runtime/r0drv/solaris/time-r0drv-solaris.c
new file mode 100644
index 00000000..b5514b47
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/time-r0drv-solaris.c
@@ -0,0 +1,70 @@
+/* $Id: time-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Time, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define RTTIME_INCL_TIMESPEC
+#include "the-solaris-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/time.h>
+
+
+RTDECL(uint64_t) RTTimeNanoTS(void)
+{
+    return (uint64_t)gethrtime();
+}
+
+
+RTDECL(uint64_t) RTTimeMilliTS(void)
+{
+    return RTTimeNanoTS() / RT_NS_1MS;
+}
+
+
+RTDECL(uint64_t) RTTimeSystemNanoTS(void)
+{
+    return RTTimeNanoTS();
+}
+
+
+RTDECL(uint64_t) RTTimeSystemMilliTS(void)
+{
+    return RTTimeNanoTS() / RT_NS_1MS;
+}
+
+
+RTDECL(PRTTIMESPEC) RTTimeNow(PRTTIMESPEC pTime)
+{
+    timestruc_t TimeSpec;
+
+    mutex_enter(&tod_lock);
+    TimeSpec = tod_get();
+    mutex_exit(&tod_lock);
+    return RTTimeSpecSetNano(pTime, (uint64_t)TimeSpec.tv_sec * RT_NS_1SEC + TimeSpec.tv_nsec);
+}
+
diff --git a/src/VBox/Runtime/r0drv/solaris/timer-r0drv-solaris.c b/src/VBox/Runtime/r0drv/solaris/timer-r0drv-solaris.c
new file mode 100644
index 00000000..8cb91cc6
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/timer-r0drv-solaris.c
@@ -0,0 +1,650 @@
+/* $Id: timer-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Timer, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2020 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "the-solaris-kernel.h"
+#include "internal/iprt.h"
+#include <iprt/timer.h>
+
+#include <iprt/asm.h>
+#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
+# include <iprt/asm-amd64-x86.h>
+#endif
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/mem.h>
+#include <iprt/mp.h>
+#include <iprt/spinlock.h>
+#include <iprt/time.h>
+#include <iprt/thread.h>
+#include "internal/magics.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * The internal representation of a Solaris timer handle.
+ */
+typedef struct RTTIMER
+{
+    /** Magic.
+     * This is RTTIMER_MAGIC, but changes to something else before the timer
+     * is destroyed to indicate clearly that thread should exit. */
+    uint32_t volatile       u32Magic;
+    /** Reference counter. */
+    uint32_t volatile       cRefs;
+    /** Flag indicating that the timer is suspended (hCyclicId should be
+     *  CYCLIC_NONE). */
+    bool volatile           fSuspended;
+    /** Flag indicating that the timer was suspended from the timer callback and
+     * therefore the hCyclicId may still be valid. */
+    bool volatile           fSuspendedFromTimer;
+    /** Flag indicating that the timer interval was changed and that it requires
+     * manual expiration time programming for each callout. */
+    bool volatile           fIntervalChanged;
+    /** Whether the timer must run on all CPUs or not. */
+    uint8_t                 fAllCpus;
+    /** Whether the timer must run on a specific CPU or not. */
+    uint8_t                 fSpecificCpu;
+    /** The CPU it must run on if fSpecificCpu is set. */
+    uint32_t                iCpu;
+    /** The nano second interval for repeating timers. */
+    uint64_t volatile       cNsInterval;
+    /** Cyclic timer Id.  This is CYCLIC_NONE if no active timer.
+     * @remarks Please keep in mind that cyclic may call us back before the
+     *          cyclic_add/cyclic_add_omni functions returns, so don't use this
+     *          unguarded with cyclic_reprogram. */
+    cyclic_id_t             hCyclicId;
+    /** The user callback. */
+    PFNRTTIMER              pfnTimer;
+    /** The argument for the user callback. */
+    void                   *pvUser;
+    /** Union with timer type specific data. */
+    union
+    {
+        /** Single timer (fAllCpus == false). */
+        struct
+        {
+            /** Timer ticks. */
+            uint64_t        u64Tick;
+            /** The next tick when fIntervalChanged is true, otherwise 0. */
+            uint64_t        nsNextTick;
+            /** The (interrupt) thread currently active in the callback. */
+            kthread_t * volatile pActiveThread;
+        } Single;
+
+        /** Omni timer (fAllCpus == true). */
+        struct
+        {
+            /** Absolute timestamp of when the timer should fire first when starting up. */
+            uint64_t        u64When;
+            /** Array of per CPU data (variable size). */
+            struct
+            {
+                /** Timer ticks (reinitialized when online'd). */
+                uint64_t    u64Tick;
+                /** The (interrupt) thread currently active in the callback. */
+                kthread_t * volatile pActiveThread;
+                /** The next tick when fIntervalChanged is true, otherwise 0. */
+                uint64_t    nsNextTick;
+            } aPerCpu[1];
+        } Omni;
+    } u;
+} RTTIMER;
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+/** Validates that the timer is valid. */
+#define RTTIMER_ASSERT_VALID_RET(pTimer) \
+    do \
+    { \
+        AssertPtrReturn(pTimer, VERR_INVALID_HANDLE); \
+        AssertMsgReturn((pTimer)->u32Magic == RTTIMER_MAGIC, ("pTimer=%p u32Magic=%x expected %x\n", (pTimer), (pTimer)->u32Magic, RTTIMER_MAGIC), \
+            VERR_INVALID_HANDLE); \
+    } while (0)
+
+
+/*********************************************************************************************************************************
+*   Internal Functions                                                                                                           *
+*********************************************************************************************************************************/
+static void rtTimerSolSingleCallbackWrapper(void *pvArg);
+static void rtTimerSolStopIt(PRTTIMER pTimer);
+
+
+/**
+ * Retains a reference to the timer.
+ *
+ * @returns New reference counter value.
+ * @param   pTimer              The timer.
+ */
+DECLINLINE(uint32_t) rtTimerSolRetain(PRTTIMER pTimer)
+{
+    return ASMAtomicIncU32(&pTimer->cRefs);
+}
+
+
+/**
+ * Destroys the timer when the reference counter has reached zero.
+ *
+ * @returns 0 (new references counter value).
+ * @param   pTimer              The timer.
+ */
+static uint32_t rtTimeSolReleaseCleanup(PRTTIMER pTimer)
+{
+    Assert(pTimer->hCyclicId == CYCLIC_NONE);
+    ASMAtomicWriteU32(&pTimer->u32Magic, ~RTTIMER_MAGIC);
+    RTMemFree(pTimer);
+    return 0;
+}
+
+
+/**
+ * Releases a reference to the timer.
+ *
+ * @returns New reference counter value.
+ * @param   pTimer              The timer.
+ */
+DECLINLINE(uint32_t) rtTimerSolRelease(PRTTIMER pTimer)
+{
+    uint32_t cRefs = ASMAtomicDecU32(&pTimer->cRefs);
+    if (!cRefs)
+        return rtTimeSolReleaseCleanup(pTimer);
+    return cRefs;
+}
+
+
+/**
+ * Callback wrapper for single-CPU timers.
+ *
+ * @param    pvArg              Opaque pointer to the timer.
+ *
+ * @remarks This will be executed in interrupt context but only at the specified
+ *          level i.e. CY_LOCK_LEVEL in our case. We -CANNOT- call into the
+ *          cyclic subsystem here, neither should pfnTimer().
+ */
+static void rtTimerSolSingleCallbackWrapper(void *pvArg)
+{
+    PRTTIMER pTimer = (PRTTIMER)pvArg;
+    AssertPtrReturnVoid(pTimer);
+    Assert(!RTThreadPreemptIsEnabled(NIL_RTTHREAD));
+    Assert(!pTimer->fAllCpus);
+
+    /* Make sure one-shots do not fire another time. */
+    Assert(   !pTimer->fSuspended
+           || pTimer->cNsInterval != 0);
+
+    if (!pTimer->fSuspendedFromTimer)
+    {
+        /* Make sure we are firing on the right CPU. */
+        Assert(   !pTimer->fSpecificCpu
+               || pTimer->iCpu == RTMpCpuId());
+
+        /* For one-shot, we may allow the callback to restart them. */
+        if (pTimer->cNsInterval == 0)
+            pTimer->fSuspendedFromTimer = true;
+
+        /*
+         * Perform the callout.
+         */
+        pTimer->u.Single.pActiveThread = curthread;
+
+        uint64_t u64Tick = ++pTimer->u.Single.u64Tick;
+        pTimer->pfnTimer(pTimer, pTimer->pvUser, u64Tick);
+
+        pTimer->u.Single.pActiveThread = NULL;
+
+        if (RT_LIKELY(!pTimer->fSuspendedFromTimer))
+        {
+            if (   !pTimer->fIntervalChanged
+                || RT_UNLIKELY(pTimer->hCyclicId == CYCLIC_NONE))
+                return;
+
+            /*
+             * The interval was changed, we need to set the expiration time
+             * ourselves before returning.  This comes at a slight cost,
+             * which is why we don't do it all the time.
+             */
+            if (pTimer->u.Single.nsNextTick)
+                pTimer->u.Single.nsNextTick += ASMAtomicUoReadU64(&pTimer->cNsInterval);
+            else
+                pTimer->u.Single.nsNextTick = RTTimeSystemNanoTS() + ASMAtomicUoReadU64(&pTimer->cNsInterval);
+            cyclic_reprogram(pTimer->hCyclicId, pTimer->u.Single.nsNextTick);
+            return;
+        }
+
+        /*
+         * The timer has been suspended, set expiration time to infinitiy.
+         */
+    }
+    if (RT_LIKELY(pTimer->hCyclicId != CYCLIC_NONE))
+        cyclic_reprogram(pTimer->hCyclicId, CY_INFINITY);
+}
+
+
+/**
+ * Callback wrapper for Omni-CPU timers.
+ *
+ * @param    pvArg              Opaque pointer to the timer.
+ *
+ * @remarks This will be executed in interrupt context but only at the specified
+ *          level i.e. CY_LOCK_LEVEL in our case. We -CANNOT- call into the
+ *          cyclic subsystem here, neither should pfnTimer().
+ */
+static void rtTimerSolOmniCallbackWrapper(void *pvArg)
+{
+    PRTTIMER pTimer = (PRTTIMER)pvArg;
+    AssertPtrReturnVoid(pTimer);
+    Assert(!RTThreadPreemptIsEnabled(NIL_RTTHREAD));
+    Assert(pTimer->fAllCpus);
+
+    if (!pTimer->fSuspendedFromTimer)
+    {
+        /*
+         * Perform the callout.
+         */
+        uint32_t const iCpu = CPU->cpu_id;
+
+        pTimer->u.Omni.aPerCpu[iCpu].pActiveThread = curthread;
+        uint64_t u64Tick = ++pTimer->u.Omni.aPerCpu[iCpu].u64Tick;
+
+        pTimer->pfnTimer(pTimer, pTimer->pvUser, u64Tick);
+
+        pTimer->u.Omni.aPerCpu[iCpu].pActiveThread = NULL;
+
+        if (RT_LIKELY(!pTimer->fSuspendedFromTimer))
+        {
+            if (   !pTimer->fIntervalChanged
+                || RT_UNLIKELY(pTimer->hCyclicId == CYCLIC_NONE))
+                return;
+
+            /*
+             * The interval was changed, we need to set the expiration time
+             * ourselves before returning.  This comes at a slight cost,
+             * which is why we don't do it all the time.
+             *
+             * Note! The cyclic_reprogram call only affects the omni cyclic
+             *       component for this CPU.
+             */
+            if (pTimer->u.Omni.aPerCpu[iCpu].nsNextTick)
+                pTimer->u.Omni.aPerCpu[iCpu].nsNextTick += ASMAtomicUoReadU64(&pTimer->cNsInterval);
+            else
+                pTimer->u.Omni.aPerCpu[iCpu].nsNextTick = RTTimeSystemNanoTS() + ASMAtomicUoReadU64(&pTimer->cNsInterval);
+            cyclic_reprogram(pTimer->hCyclicId, pTimer->u.Omni.aPerCpu[iCpu].nsNextTick);
+            return;
+        }
+
+        /*
+         * The timer has been suspended, set expiration time to infinitiy.
+         */
+    }
+    if (RT_LIKELY(pTimer->hCyclicId != CYCLIC_NONE))
+        cyclic_reprogram(pTimer->hCyclicId, CY_INFINITY);
+}
+
+
+/**
+ * Omni-CPU cyclic online event. This is called before the omni cycle begins to
+ * fire on the specified CPU.
+ *
+ * @param    pvArg              Opaque pointer to the timer.
+ * @param    pCpu               Pointer to the CPU on which it will fire.
+ * @param    pCyclicHandler     Pointer to a cyclic handler to add to the CPU
+ *                              specified in @a pCpu.
+ * @param    pCyclicTime        Pointer to the cyclic time and interval object.
+ *
+ * @remarks We -CANNOT- call back into the cyclic subsystem here, we can however
+ *          block (sleep).
+ */
+static void rtTimerSolOmniCpuOnline(void *pvArg, cpu_t *pCpu, cyc_handler_t *pCyclicHandler, cyc_time_t *pCyclicTime)
+{
+    PRTTIMER pTimer = (PRTTIMER)pvArg;
+    AssertPtrReturnVoid(pTimer);
+    AssertPtrReturnVoid(pCpu);
+    AssertPtrReturnVoid(pCyclicHandler);
+    AssertPtrReturnVoid(pCyclicTime);
+    uint32_t const iCpu = pCpu->cpu_id; /* Note! CPU is not necessarily the same as pCpu. */
+
+    pTimer->u.Omni.aPerCpu[iCpu].u64Tick = 0;
+    pTimer->u.Omni.aPerCpu[iCpu].nsNextTick = 0;
+
+    pCyclicHandler->cyh_func  = (cyc_func_t)rtTimerSolOmniCallbackWrapper;
+    pCyclicHandler->cyh_arg   = pTimer;
+    pCyclicHandler->cyh_level = CY_LOCK_LEVEL;
+
+    uint64_t u64Now = RTTimeSystemNanoTS();
+    if (pTimer->u.Omni.u64When < u64Now)
+        pCyclicTime->cyt_when = u64Now + pTimer->cNsInterval / 2;
+    else
+        pCyclicTime->cyt_when = pTimer->u.Omni.u64When;
+
+    pCyclicTime->cyt_interval = pTimer->cNsInterval;
+}
+
+
+RTDECL(int) RTTimerCreateEx(PRTTIMER *ppTimer, uint64_t u64NanoInterval, uint32_t fFlags, PFNRTTIMER pfnTimer, void *pvUser)
+{
+    RT_ASSERT_PREEMPTIBLE();
+    *ppTimer = NULL;
+
+    /*
+     * Validate flags.
+     */
+    if (!RTTIMER_FLAGS_ARE_VALID(fFlags))
+        return VERR_INVALID_PARAMETER;
+
+    if (    (fFlags & RTTIMER_FLAGS_CPU_SPECIFIC)
+        &&  (fFlags & RTTIMER_FLAGS_CPU_ALL) != RTTIMER_FLAGS_CPU_ALL
+        &&  !RTMpIsCpuPossible(RTMpCpuIdFromSetIndex(fFlags & RTTIMER_FLAGS_CPU_MASK)))
+        return VERR_CPU_NOT_FOUND;
+
+    /* One-shot omni timers are not supported by the cyclic system. */
+    if (   (fFlags & RTTIMER_FLAGS_CPU_ALL) == RTTIMER_FLAGS_CPU_ALL
+        && u64NanoInterval == 0)
+        return VERR_NOT_SUPPORTED;
+
+    /*
+     * Allocate and initialize the timer handle.  The omni variant has a
+     * variable sized array of ticks counts, thus the size calculation.
+     */
+    PRTTIMER pTimer = (PRTTIMER)RTMemAllocZ(  (fFlags & RTTIMER_FLAGS_CPU_ALL) == RTTIMER_FLAGS_CPU_ALL
+                                            ? RT_UOFFSETOF_DYN(RTTIMER, u.Omni.aPerCpu[RTMpGetCount()])
+                                            : sizeof(RTTIMER));
+    if (!pTimer)
+        return VERR_NO_MEMORY;
+
+    pTimer->u32Magic = RTTIMER_MAGIC;
+    pTimer->cRefs = 1;
+    pTimer->fSuspended = true;
+    pTimer->fSuspendedFromTimer = false;
+    pTimer->fIntervalChanged = false;
+    if ((fFlags & RTTIMER_FLAGS_CPU_ALL) == RTTIMER_FLAGS_CPU_ALL)
+    {
+        pTimer->fAllCpus = true;
+        pTimer->fSpecificCpu = false;
+        pTimer->iCpu = UINT32_MAX;
+    }
+    else if (fFlags & RTTIMER_FLAGS_CPU_SPECIFIC)
+    {
+        pTimer->fAllCpus = false;
+        pTimer->fSpecificCpu = true;
+        pTimer->iCpu = fFlags & RTTIMER_FLAGS_CPU_MASK; /* ASSUMES: index == cpuid */
+    }
+    else
+    {
+        pTimer->fAllCpus = false;
+        pTimer->fSpecificCpu = false;
+        pTimer->iCpu = UINT32_MAX;
+    }
+    pTimer->cNsInterval = u64NanoInterval;
+    pTimer->pfnTimer = pfnTimer;
+    pTimer->pvUser = pvUser;
+    pTimer->hCyclicId = CYCLIC_NONE;
+
+    *ppTimer = pTimer;
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Checks if the calling thread is currently executing the timer proceduce for
+ * the given timer.
+ *
+ * @returns true if it is, false if it isn't.
+ * @param   pTimer              The timer in question.
+ */
+DECLINLINE(bool) rtTimerSolIsCallingFromTimerProc(PRTTIMER pTimer)
+{
+    kthread_t *pCurThread = curthread;
+    AssertReturn(pCurThread, false); /* serious paranoia */
+
+    if (!pTimer->fAllCpus)
+        return pTimer->u.Single.pActiveThread == pCurThread;
+    return pTimer->u.Omni.aPerCpu[CPU->cpu_id].pActiveThread == pCurThread;
+}
+
+
+RTDECL(int) RTTimerDestroy(PRTTIMER pTimer)
+{
+    if (pTimer == NULL)
+        return VINF_SUCCESS;
+    RTTIMER_ASSERT_VALID_RET(pTimer);
+    RT_ASSERT_INTS_ON();
+
+    /*
+     * It is not possible to destroy a timer from it's callback function.
+     * Cyclic makes that impossible (or at least extremely risky).
+     */
+    AssertReturn(!rtTimerSolIsCallingFromTimerProc(pTimer), VERR_INVALID_CONTEXT);
+
+    /*
+     * Invalidate the handle, make sure it's stopped and free the associated resources.
+     */
+    ASMAtomicWriteU32(&pTimer->u32Magic, ~RTTIMER_MAGIC);
+
+    if (   !pTimer->fSuspended
+        || pTimer->hCyclicId != CYCLIC_NONE) /* 2nd check shouldn't happen */
+        rtTimerSolStopIt(pTimer);
+
+    rtTimerSolRelease(pTimer);
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTTimerStart(PRTTIMER pTimer, uint64_t u64First)
+{
+    RTTIMER_ASSERT_VALID_RET(pTimer);
+    RT_ASSERT_INTS_ON();
+
+    /*
+     * It's not possible to restart a one-shot time from it's callback function,
+     * at least not at the moment.
+     */
+    AssertReturn(!rtTimerSolIsCallingFromTimerProc(pTimer), VERR_INVALID_CONTEXT);
+
+    mutex_enter(&cpu_lock);
+
+    /*
+     * Make sure it's not active already.  If it was suspended from a timer
+     * callback function, we need to do some cleanup work here before we can
+     * restart the timer.
+     */
+    if (!pTimer->fSuspended)
+    {
+        if (!pTimer->fSuspendedFromTimer)
+        {
+            mutex_exit(&cpu_lock);
+            return VERR_TIMER_ACTIVE;
+        }
+        cyclic_remove(pTimer->hCyclicId);
+        pTimer->hCyclicId = CYCLIC_NONE;
+    }
+
+    pTimer->fSuspended = false;
+    pTimer->fSuspendedFromTimer = false;
+    pTimer->fIntervalChanged = false;
+    if (pTimer->fAllCpus)
+    {
+        /*
+         * Setup omni (all CPU) timer. The Omni-CPU online event will fire
+         * and from there we setup periodic timers per CPU.
+         */
+        pTimer->u.Omni.u64When  = RTTimeSystemNanoTS() + (u64First ? u64First : pTimer->cNsInterval);
+
+        cyc_omni_handler_t HandlerOmni;
+        HandlerOmni.cyo_online  = rtTimerSolOmniCpuOnline;
+        HandlerOmni.cyo_offline = NULL;
+        HandlerOmni.cyo_arg     = pTimer;
+
+        pTimer->hCyclicId = cyclic_add_omni(&HandlerOmni);
+    }
+    else
+    {
+        cyc_handler_t Handler;
+        cyc_time_t    FireTime;
+
+        /*
+         * Setup a single CPU timer.   If a specific CPU was requested, it
+         * must be online or the timer cannot start.
+         */
+        if (   pTimer->fSpecificCpu
+            && !RTMpIsCpuOnline(pTimer->iCpu)) /* ASSUMES: index == cpuid */
+        {
+            pTimer->fSuspended = true;
+
+            mutex_exit(&cpu_lock);
+            return VERR_CPU_OFFLINE;
+        }
+
+        Handler.cyh_func  = (cyc_func_t)rtTimerSolSingleCallbackWrapper;
+        Handler.cyh_arg   = pTimer;
+        Handler.cyh_level = CY_LOCK_LEVEL;
+
+        /*
+         * Use a large interval (1 hour) so that we don't get a timer-callback between
+         * cyclic_add() and cyclic_bind(). Program the correct interval once cyclic_bind() is done.
+         * See @bugref{7691#c20}.
+         */
+        if (!pTimer->fSpecificCpu)
+            FireTime.cyt_when = RTTimeSystemNanoTS() + u64First;
+        else
+            FireTime.cyt_when = RTTimeSystemNanoTS() + u64First + RT_NS_1HOUR;
+        FireTime.cyt_interval = pTimer->cNsInterval != 0
+                              ? pTimer->cNsInterval
+                              : CY_INFINITY /* Special value, see cyclic_fire(). */;
+        pTimer->u.Single.u64Tick = 0;
+        pTimer->u.Single.nsNextTick = 0;
+
+        pTimer->hCyclicId = cyclic_add(&Handler, &FireTime);
+        if (pTimer->fSpecificCpu)
+        {
+            cyclic_bind(pTimer->hCyclicId, cpu[pTimer->iCpu], NULL /* cpupart */);
+            cyclic_reprogram(pTimer->hCyclicId, RTTimeSystemNanoTS() + u64First);
+        }
+    }
+
+    mutex_exit(&cpu_lock);
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Worker common for RTTimerStop and RTTimerDestroy.
+ *
+ * @param   pTimer      The timer to stop.
+ */
+static void rtTimerSolStopIt(PRTTIMER pTimer)
+{
+    mutex_enter(&cpu_lock);
+
+    pTimer->fSuspended = true;
+    if (pTimer->hCyclicId != CYCLIC_NONE)
+    {
+        cyclic_remove(pTimer->hCyclicId);
+        pTimer->hCyclicId = CYCLIC_NONE;
+    }
+    pTimer->fSuspendedFromTimer = false;
+
+    mutex_exit(&cpu_lock);
+}
+
+
+RTDECL(int) RTTimerStop(PRTTIMER pTimer)
+{
+    RTTIMER_ASSERT_VALID_RET(pTimer);
+    RT_ASSERT_INTS_ON();
+
+    if (pTimer->fSuspended)
+        return VERR_TIMER_SUSPENDED;
+
+    /* Trying the cpu_lock stuff and calling cyclic_remove may deadlock
+       the system, so just mark the timer as suspened and deal with it in
+       the callback wrapper function above. */
+    if (rtTimerSolIsCallingFromTimerProc(pTimer))
+        pTimer->fSuspendedFromTimer = true;
+    else
+        rtTimerSolStopIt(pTimer);
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(int) RTTimerChangeInterval(PRTTIMER pTimer, uint64_t u64NanoInterval)
+{
+    /*
+     * Validate.
+     */
+    RTTIMER_ASSERT_VALID_RET(pTimer);
+    AssertReturn(u64NanoInterval > 0, VERR_INVALID_PARAMETER);
+    AssertReturn(u64NanoInterval < UINT64_MAX / 8, VERR_INVALID_PARAMETER);
+    AssertReturn(pTimer->cNsInterval, VERR_INVALID_STATE);
+
+    if (pTimer->fSuspended || pTimer->fSuspendedFromTimer)
+        pTimer->cNsInterval = u64NanoInterval;
+    else
+    {
+        ASMAtomicWriteU64(&pTimer->cNsInterval, u64NanoInterval);
+        ASMAtomicWriteBool(&pTimer->fIntervalChanged, true);
+
+        if (   !pTimer->fAllCpus
+            && !pTimer->u.Single.nsNextTick
+            && pTimer->hCyclicId != CYCLIC_NONE
+            && rtTimerSolIsCallingFromTimerProc(pTimer))
+            pTimer->u.Single.nsNextTick = RTTimeSystemNanoTS();
+    }
+
+    return VINF_SUCCESS;
+}
+
+
+RTDECL(uint32_t) RTTimerGetSystemGranularity(void)
+{
+    return nsec_per_tick;
+}
+
+
+RTDECL(int) RTTimerRequestSystemGranularity(uint32_t u32Request, uint32_t *pu32Granted)
+{
+    return VERR_NOT_SUPPORTED;
+}
+
+
+RTDECL(int) RTTimerReleaseSystemGranularity(uint32_t u32Granted)
+{
+    return VERR_NOT_SUPPORTED;
+}
+
+
+RTDECL(bool) RTTimerCanDoHighResolution(void)
+{
+    return true;
+}
+