Adding upstream version 7.0.14-dfsg.upstream/7.0.14-dfsg

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

26 files changed, 7179 insertions, 0 deletions

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..1ac8ed3d
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/RTLogWriteDebugger-r0drv-solaris.c
@@ -0,0 +1,76 @@
+/* $Id: RTLogWriteDebugger-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Log To Debugger, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   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..713c9c63
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/RTMpPokeCpu-r0drv-solaris.c
@@ -0,0 +1,60 @@
+/* $Id: RTMpPokeCpu-r0drv-solaris.c $ */
+/** @file
+ * IPRT - RTMpPokeCpu, Solaris Implementation.
+ */
+
+/*
+ * Copyright (C) 2009-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   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..9c0e9765
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/alloc-r0drv-solaris.c
@@ -0,0 +1,198 @@
+/* $Id: alloc-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Memory Allocation, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   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;
+    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;
+    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..a1b9dc56
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/assert-r0drv-solaris.c
@@ -0,0 +1,87 @@
+/* $Id: assert-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Assertion Workers, Ring-0 Drivers, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   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..bc617428
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/dbgkrnlinfo-r0drv-solaris.c
@@ -0,0 +1,349 @@
+/* $Id: dbgkrnlinfo-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Kernel debug information, Ring-0 Driver, Solaris Code.
+ */
+
+/*
+ * Copyright (C) 2012-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   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..4320a775
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/initterm-r0drv-solaris.c
@@ -0,0 +1,310 @@
+/* $Id: initterm-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Initialization & Termination, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   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..2308eff8
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/memobj-r0drv-solaris.c
@@ -0,0 +1,1213 @@
+/* $Id: memobj-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Ring-0 Memory Objects, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   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;
+    /** Set if executable allocation - only RTR0MEMOBJTYPE_PHYS. */
+    bool                fExecutable;
+} 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:
+            if (!pMemSolaris->fExecutable)
+                ddi_umem_free(pMemSolaris->Cookie);
+            else
+                segkmem_free(heaptext_arena, pMemSolaris->Core.pv, pMemSolaris->Core.cb);
+            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, const char *pszTag)
+{
+    /* Create the object. */
+    PRTR0MEMOBJSOL pMemSolaris = (PRTR0MEMOBJSOL)rtR0MemObjNew(sizeof(*pMemSolaris), RTR0MEMOBJTYPE_PAGE, NULL, cb, pszTag);
+    if (pMemSolaris)
+    {
+        void *pvMem;
+        if (!fExecutable)
+        {
+            pMemSolaris->Core.fFlags |= RTR0MEMOBJ_FLAGS_ZERO_AT_ALLOC;
+            pvMem = ddi_umem_alloc(cb, DDI_UMEM_SLEEP, &pMemSolaris->Cookie);
+        }
+        else
+        {
+            pMemSolaris->Core.fFlags |= RTR0MEMOBJ_FLAGS_UNINITIALIZED_AT_ALLOC; /** @todo does segkmem_alloc zero the memory? */
+            pvMem = segkmem_alloc(heaptext_arena, cb, KM_SLEEP);
+        }
+        if (pvMem)
+        {
+            pMemSolaris->Core.pv  = pvMem;
+            pMemSolaris->pvHandle = NULL;
+            pMemSolaris->fExecutable = fExecutable;
+            *ppMem = &pMemSolaris->Core;
+            return VINF_SUCCESS;
+        }
+        rtR0MemObjDelete(&pMemSolaris->Core);
+        return VERR_NO_PAGE_MEMORY;
+    }
+    return VERR_NO_MEMORY;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocLarge(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, size_t cbLargePage, uint32_t fFlags,
+                                           const char *pszTag)
+{
+    return rtR0MemObjFallbackAllocLarge(ppMem, cb, cbLargePage, fFlags, pszTag);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocLow(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable, const char *pszTag)
+{
+    AssertReturn(!fExecutable, VERR_NOT_SUPPORTED);
+
+    /* Create the object */
+    PRTR0MEMOBJSOL pMemSolaris = (PRTR0MEMOBJSOL)rtR0MemObjNew(sizeof(*pMemSolaris), RTR0MEMOBJTYPE_LOW, NULL, cb, pszTag);
+    if (pMemSolaris)
+    {
+        /* Allocate physically low page-aligned memory. */
+        uint64_t uPhysHi = _4G - 1;
+        void *pvMem = rtR0SolMemAlloc(uPhysHi, NULL /* puPhys */, cb, PAGE_SIZE, false /* fContig */);
+        if (pvMem)
+        {
+            pMemSolaris->Core.fFlags |= RTR0MEMOBJ_FLAGS_UNINITIALIZED_AT_ALLOC;
+            pMemSolaris->Core.pv = pvMem;
+            pMemSolaris->pvHandle = NULL;
+            *ppMem = &pMemSolaris->Core;
+            return VINF_SUCCESS;
+        }
+        rtR0MemObjDelete(&pMemSolaris->Core);
+        return VERR_NO_LOW_MEMORY;
+    }
+    return VERR_NO_MEMORY;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocCont(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, bool fExecutable, const char *pszTag)
+{
+    AssertReturn(!fExecutable, VERR_NOT_SUPPORTED);
+    return rtR0MemObjNativeAllocPhys(ppMem, cb, _4G - 1, PAGE_SIZE /* alignment */, pszTag);
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeAllocPhysNC(PPRTR0MEMOBJINTERNAL ppMem, size_t cb, RTHCPHYS PhysHighest, const char *pszTag)
+{
+#if HC_ARCH_BITS == 64
+    PRTR0MEMOBJSOL pMemSolaris = (PRTR0MEMOBJSOL)rtR0MemObjNew(sizeof(*pMemSolaris), RTR0MEMOBJTYPE_PHYS_NC, NULL, cb, pszTag);
+    if (pMemSolaris)
+    {
+        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;
+        }
+        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;
+        }
+        pMemSolaris->Core.fFlags |= RTR0MEMOBJ_FLAGS_UNINITIALIZED_AT_ALLOC;
+        *ppMem = &pMemSolaris->Core;
+        return VINF_SUCCESS;
+    }
+    return VERR_NO_MEMORY;
+
+#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,
+                                          const char *pszTag)
+{
+    AssertMsgReturn(PhysHighest >= 16 *_1M, ("PhysHigest=%RHp\n", PhysHighest), VERR_NOT_SUPPORTED);
+
+    PRTR0MEMOBJSOL pMemSolaris = (PRTR0MEMOBJSOL)rtR0MemObjNew(sizeof(*pMemSolaris), RTR0MEMOBJTYPE_PHYS, NULL, cb, pszTag);
+    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.fFlags           |= RTR0MEMOBJ_FLAGS_UNINITIALIZED_AT_ALLOC; /*?*/
+            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.fFlags           |= RTR0MEMOBJ_FLAGS_UNINITIALIZED_AT_ALLOC;
+            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,
+                                          const char *pszTag)
+{
+    AssertReturn(uCachePolicy == RTMEM_CACHE_POLICY_DONT_CARE, VERR_NOT_SUPPORTED);
+
+    /* Create the object. */
+    PRTR0MEMOBJSOL pMemSolaris = (PRTR0MEMOBJSOL)rtR0MemObjNew(sizeof(*pMemSolaris), RTR0MEMOBJTYPE_PHYS, NULL, cb, pszTag);
+    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, const char *pszTag)
+{
+    AssertReturn(R0Process == RTR0ProcHandleSelf(), VERR_INVALID_PARAMETER);
+    NOREF(fAccess);
+
+    /* Create the locking object */
+    PRTR0MEMOBJSOL pMemSolaris = (PRTR0MEMOBJSOL)rtR0MemObjNew(sizeof(*pMemSolaris), RTR0MEMOBJTYPE_LOCK,
+                                                               (void *)R3Ptr, cb, pszTag);
+    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, const char *pszTag)
+{
+    NOREF(fAccess);
+
+    PRTR0MEMOBJSOL pMemSolaris = (PRTR0MEMOBJSOL)rtR0MemObjNew(sizeof(*pMemSolaris), RTR0MEMOBJTYPE_LOCK, pv, cb, pszTag);
+    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,
+                                              const char *pszTag)
+{
+    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, pszTag);
+    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, const char *pszTag)
+{
+    RT_NOREF(ppMem, R3PtrFixed, cb, uAlignment, R0Process, pszTag);
+    return VERR_NOT_SUPPORTED;
+}
+
+
+DECLHIDDEN(int) rtR0MemObjNativeMapKernel(PPRTR0MEMOBJINTERNAL ppMem, RTR0MEMOBJ pMemToMap, void *pvFixed, size_t uAlignment,
+                                          unsigned fProt, size_t offSub, size_t cbSub, const char *pszTag)
+{
+    /* 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, pszTag);
+        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,
+                                        const char *pszTag)
+{
+    /*
+     * 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, pszTag);
+    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..8dbb6e5e
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/memobj-r0drv-solaris.h
@@ -0,0 +1,336 @@
+/* $Id: memobj-r0drv-solaris.h $ */
+/** @file
+ * IPRT - Ring-0 Memory Objects - Segment driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2012-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+#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;
+}
+
+
+#ifdef SEGOP_CAPABLE
+static int rtR0SegVBoxSolCapable(seg_t *pSeg, segcapability_t Capab)
+{
+    return 0;
+}
+#endif
+
+
+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() */
+#ifdef SEGOP_CAPABLE
+    rtR0SegVBoxSolCapable
+#endif
+};
+
+#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..81278fd7
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/memuserkernel-r0drv-solaris.c
@@ -0,0 +1,110 @@
+/* $Id: memuserkernel-r0drv-solaris.c $ */
+/** @file
+ * IPRT - User & Kernel Memory, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2009-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   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..0e053c47
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/modulestub-r0drv-solaris.c
@@ -0,0 +1,89 @@
+/* $Id: modulestub-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Ring-0 Solaris stubs
+ */
+
+/*
+ * Copyright (C) 2011-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   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..0f4f63e5
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/mp-r0drv-solaris.c
@@ -0,0 +1,460 @@
+/* $Id: mp-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Multiprocessor, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2008-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   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..983b5790
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/mpnotification-r0drv-solaris.c
@@ -0,0 +1,149 @@
+/* $Id: mpnotification-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Multiprocessor Event Notifications, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2008-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   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..0d9be4d9
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/process-r0drv-solaris.c
@@ -0,0 +1,59 @@
+/* $Id: process-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Process Management, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   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..0fab932b
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/semevent-r0drv-solaris.c
@@ -0,0 +1,364 @@
+/* $Id: semevent-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Single Release Event Semaphores, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   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();
+}
+
+
+RTR0DECL(bool) RTSemEventIsSignalSafe(void)
+{
+    /* I don't trust Solaris not to preempt us. */
+    return false;
+}
+
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..04692b61
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/semeventmulti-r0drv-solaris.c
@@ -0,0 +1,372 @@
+/* $Id: semeventmulti-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Multiple Release Event Semaphores, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   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();
+}
+
+
+RTR0DECL(bool) RTSemEventMultiIsSignalSafe(void)
+{
+    /* Don't trust solaris not to preempt us. */
+    return false;
+}
+
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..2494d6f5
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/semeventwait-r0drv-solaris.h
@@ -0,0 +1,508 @@
+/* $Id: semeventwait-r0drv-solaris.h $ */
+/** @file
+ * IPRT - Solaris Ring-0 Driver Helpers for Event Semaphore Waits.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+#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 (RT_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 (RT_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;
+
+    u.idCo = 0; /* Silence a spurious gcc [-Wmaybe-uninitialized] warning. */
+
+    /*
+     * 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..22a15aef
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/semfastmutex-r0drv-solaris.c
@@ -0,0 +1,130 @@
+/* $Id: semfastmutex-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Fast Mutex Semaphores, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   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..e8081482
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/semmutex-r0drv-solaris.c
@@ -0,0 +1,397 @@
+/* $Id: semmutex-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Mutex Semaphores, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   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..9032d810
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/spinlock-r0drv-solaris.c
@@ -0,0 +1,214 @@
+/* $Id: spinlock-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Spinlocks, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   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..3cadd282
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/the-solaris-kernel.h
@@ -0,0 +1,244 @@
+/* $Id: the-solaris-kernel.h $ */
+/** @file
+ * IPRT - Include all necessary headers for the Solaris kernel.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+#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..0fefabe9
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/thread-r0drv-solaris.c
@@ -0,0 +1,195 @@
+/* $Id: thread-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Threads, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   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..8ff450a5
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/thread2-r0drv-solaris.c
@@ -0,0 +1,160 @@
+/* $Id: thread2-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Threads (Part 2), Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   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..387e9356
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/threadctxhooks-r0drv-solaris.c
@@ -0,0 +1,359 @@
+/* $Id: threadctxhooks-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Thread Context Switching Hook, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2013-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   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..81001b97
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/time-r0drv-solaris.c
@@ -0,0 +1,80 @@
+/* $Id: time-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Time, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   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..b415201d
--- /dev/null
+++ b/src/VBox/Runtime/r0drv/solaris/timer-r0drv-solaris.c
@@ -0,0 +1,660 @@
+/* $Id: timer-r0drv-solaris.c $ */
+/** @file
+ * IPRT - Timer, Ring-0 Driver, Solaris.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox 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.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   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;
+}
+