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

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

87 files changed, 39656 insertions, 0 deletions

diff --git a/src/VBox/Additions/common/VBoxGuest/.scm-settings b/src/VBox/Additions/common/VBoxGuest/.scm-settings
new file mode 100644
index 00000000..70bef493
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/.scm-settings
@@ -0,0 +1,65 @@
+# $Id: .scm-settings $
+## @file
+# Source code massager settings for VBoxGuest
+#
+
+#
+# Copyright (C) 2010-2023 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
+#
+
+# Like the host drivers, this is dual licensed.
+--license-ose-dual
+
+/VBoxGuest-solaris.conf: --treat-as .sh
+
+/netbsd/vboxguest.ioconf: --treat-as .sh --no-convert-tabs --no-convert-eol
+
+# a stub for a file that is normally autogenerated
+/netbsd/locators.h: --external-copyright --no-fix-header-guards
+
+# And the R0 library is MIT to make two-way code exchange with the Linux kernel
+# easier.
+/lib/VBoxGuestR0LibCrOgl.cpp:            --license-mit
+/lib/VBoxGuestR0LibGenericRequest.cpp:   --license-mit
+/lib/VBoxGuestR0LibHGCM.cpp:             --license-mit
+/lib/VBoxGuestR0LibHGCMInternal.cpp:     --license-mit
+/lib/VBoxGuestR0LibIdc-os2.cpp:          --license-mit
+/lib/VBoxGuestR0LibIdc-solaris.cpp:      --license-mit
+/lib/VBoxGuestR0LibIdc-unix.cpp:         --license-mit
+/lib/VBoxGuestR0LibIdc-win.cpp:          --license-mit
+/lib/VBoxGuestR0LibIdc.cpp:              --license-mit
+/lib/VBoxGuestR0LibInit.cpp:             --license-mit
+/lib/VBoxGuestR0LibInternal.h:           --license-mit
+/lib/VBoxGuestR0LibMouse.cpp:            --license-mit
+/lib/VBoxGuestR0LibPhysHeap.cpp:         --license-mit
+/lib/VBoxGuestR0LibSharedFolders.c:      --license-mit
+/lib/VBoxGuestR0LibVMMDev.cpp:           --license-mit
+/lib/VbglR0CanUsePhysPageList.cpp:       --license-mit
+
diff --git a/src/VBox/Additions/common/VBoxGuest/Makefile.kmk b/src/VBox/Additions/common/VBoxGuest/Makefile.kmk
new file mode 100644
index 00000000..f619d04a
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/Makefile.kmk
@@ -0,0 +1,287 @@
+# $Id: Makefile.kmk $
+## @file
+# Makefile for the Cross Platform Guest Additions Driver.
+#
+
+#
+# Copyright (C) 2007-2023 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
+#
+
+SUB_DEPTH = ../../../../..
+include $(KBUILD_PATH)/subheader.kmk
+
+# Include sub-makefile.
+include $(PATH_SUB_CURRENT)/lib/Makefile.kmk
+
+
+if defined(VBOX_WITH_ADDITION_DRIVERS) && "$(intersects $(KBUILD_TARGET), darwin freebsd haiku netbsd os2 solaris win)" != ""
+ #
+ # VBoxGuest - The Guest Additions Driver.
+ #
+ SYSMODS += VBoxGuest
+ VBoxGuest_TEMPLATE      = VBoxGuestR0Drv
+ VBoxGuest_NAME.freebsd  = vboxguest
+ VBoxGuest_NAME.haiku    = vboxguest
+ VBoxGuest_NAME.netbsd   = vboxguest
+ VBoxGuest_NAME.solaris  = vboxguest
+ VBoxGuest_INST.darwin   = $(INST_ADDITIONS)VBoxGuest.kext/Contents/MacOS/
+ if defined(VBOX_SIGNING_MODE) && defined(VBOX_SIGN_ADDITIONS) # See Additions/WINNT/Makefile.kmk?
+  VBoxGuest_INSTTYPE.win = none
+  VBoxGuest_DEBUG_INSTTYPE.win = both
+ endif
+ VBoxGuest_DEFS.haiku    = VBOX_SVN_REV=$(VBOX_SVN_REV) _KERNEL_MODE=1
+ VBoxGuest_DEFS.solaris  = VBOX_SVN_REV=$(VBOX_SVN_REV)
+ VBoxGuest_DEFS.win      = VBOX_GUESTDRV_WITH_RELEASE_LOGGER
+ VBoxGuest_DEFS.win.x86  = TARGET_NT4 TARGET_NT3 RT_WITHOUT_NOCRT_WRAPPERS
+ VBoxGuest_DEFS.darwin   = VBOX_GUESTDRV_WITH_RELEASE_LOGGER
+ ifeq ($(KBUILD_TYPE),release)
+  # Allow stopping/removing the driver without a reboot
+  # in debug mode; this is very useful for testing the shutdown stuff!
+  VBoxGuest_DEFS.win    += VBOX_REBOOT_ON_UNINSTALL
+ endif
+ ifdef VBOX_WITH_GUEST_BUGCHECK_DETECTION
+  VBoxGuest_DEFS.win    += VBOX_WITH_GUEST_BUGCHECK_DETECTION
+ endif
+ #VBoxGuest_DEFS.win     += LOG_ENABLED LOG_TO_BACKDOOR
+ VBoxGuest_DEFS.win += \
+ 	$(if $(VBOX_WITH_DPC_LATENCY_CHECKER),VBOX_WITH_DPC_LATENCY_CHECKER,)
+ VBoxGuest_DEPS.solaris += $(VBOX_SVN_REV_KMK)
+ VBoxGuest_DEPS.haiku   += $(VBOX_SVN_REV_HEADER)
+ VBoxGuest_DEPS.freebsd += $(VBOX_SVN_REV_HEADER)
+ VBoxGuest_DEPS.netbsd  += $(VBOX_SVN_REV_HEADER)
+ VBoxGuest_DEPS.darwin  += $(VBOX_SVN_REV_HEADER)
+ VBoxGuest_DEFS          = VBGL_VBOXGUEST VBOX_WITH_HGCM
+ VBoxGuest_INCS          = .
+ VBoxGuest_INCS.freebsd  = $(VBoxGuest_0_OUTDIR) $(PATH_STAGE)/gen-sys-hdrs
+ VBoxGuest_INCS.netbsd   = $(VBoxGuest_0_OUTDIR) netbsd
+ ifeq ($(KBUILD_HOST),solaris)
+  VBoxGuest_LDFLAGS.solaris         += -N misc/ctf
+ else
+  VBoxGuest_SOURCES.solaris          = solaris/deps.asm
+  VBoxGuest_solaris/deps.asm_ASFLAGS = -f bin -g null
+ endif
+ ifneq ($(KBUILD_TARGET),os2)
+  ifeq ($(KBUILD_TARGET),win)
+   VBoxGuest_LDFLAGS.x86 = -Entry:DriverEntry@8
+   VBoxGuest_LDFLAGS.amd64 = -Entry:DriverEntry
+   ifeq ($(KBUILD_TARGET_ARCH),x86)
+    VBoxGuest_SDKS       = ReorderCompilerIncs $(VBOX_WINDDK_GST_NT4)
+    VBoxGuest_LIBS       = \
+    	$(VBOX_LIB_VBGL_R0BASE) \
+    	$(VBOX_LIB_IPRT_GUEST_R0) \
+    	$(PATH_SDK_$(VBOX_WINDDK_GST_NT4)_LIB)/exsup.lib \
+    	$(PATH_SDK_$(VBOX_WINDDK_GST_NT4)_LIB)/int64.lib \
+    	$(PATH_SDK_$(VBOX_WINDDK_GST)_LIB)/ntoskrnl.lib \
+    	$(PATH_SDK_$(VBOX_WINDDK_GST)_LIB)/hal.lib
+    ifneq ($(VBOX_VCC_CC_GUARD_CF),)
+     VBoxGuest_LIBS     += \
+     	$(PATH_SDK_$(VBOX_WINDDK_GST)_LIB)/BufferOverflowK.lib
+    endif
+   else
+    VBoxGuest_LIBS       = \
+    	$(PATH_SDK_$(VBOX_WINDDK_GST)_LIB)/ntoskrnl.lib \
+    	$(PATH_SDK_$(VBOX_WINDDK_GST)_LIB)/hal.lib
+   endif
+   VBoxGuest_USES.win += vboximportchecker
+   VBoxGuest_VBOX_IMPORT_CHECKER.win.x86 = nt31/r0
+   VBoxGuest_VBOX_IMPORT_CHECKER.win.amd64 = xp64/r0
+  endif # win
+  ifn1of ($(KBUILD_TARGET), linux freebsd netbsd solaris haiku)
+   VBoxGuest_SOURCES    = VBoxGuest-$(KBUILD_TARGET).cpp
+  else
+   VBoxGuest_SOURCES    = VBoxGuest-$(KBUILD_TARGET).c
+   VBoxGuest_$(KBUILD_TARGET).c_DEPS = $(VBOX_SVN_REV_HEADER)
+   ifeq ($(KBUILD_TARGET),freebsd)
+    VBoxGuest-$(KBUILD_TARGET).c_CFLAGS = -Wno-sign-compare # /usr/src/sys/sys/vmmeter.h: In function 'vm_paging_needed'
+   endif
+  endif
+  VBoxGuest_SOURCES     += \
+  	VBoxGuest.cpp
+  VBoxGuest_SOURCES.win += \
+  	win/VBoxGuest.rc
+  VBoxGuest_SOURCES.win.x86 += \
+  	../../../Runtime/common/string/strcmp.asm \
+  	../../../Runtime/common/string/strchr.asm \
+  	../../../Runtime/r0drv/nt/nt3fakes-r0drv-nt.cpp \
+  	../../../Runtime/r0drv/nt/nt3fakesA-r0drv-nt.asm
+  VBoxGuest_LIBS        += \
+  	$(VBOX_LIB_VBGL_R0BASE) \
+  	$(VBOX_LIB_IPRT_GUEST_R0)
+  VBoxGuest_ORDERDEPS.freebsd = \
+  	$(PATH_STAGE)/gen-sys-hdrs/pci_if.h \
+  	$(PATH_STAGE)/gen-sys-hdrs/bus_if.h \
+  	$(PATH_STAGE)/gen-sys-hdrs/device_if.h
+  ifeq ($(KBUILD_TARGET),haiku)
+   # Haiku drivers cannot export symbols for other drivers, but modules can.
+   # Therefore vboxguest is a module containing the ring-0 guest lib, and vboxdev/vboxsf
+   # use this module to access the guest lib
+   SYSMODS += VBoxDev
+   VBoxDev_TEMPLATE      = VBoxGuestR0Drv
+   VBoxDev_NAME          = vboxdev
+   VBoxDev_DEFS          = VBOX_SVN_REV=$(VBOX_SVN_REV) _KERNEL_MODE=1 VBGL_VBOXGUEST VBOX_WITH_HGCM IN_RING0
+   VBoxDev_SOURCES       = VBoxDev-haiku.c VBoxGuest-haiku-stubs.c
+  endif
+ else # OS/2:
+  # The library order is crucial, so a bit of trickery is necessary.
+  # A library is used to make sure that VBoxGuestA-os2.asm is first in the link. (temporary hack?)
+  VBoxGuest_SOURCES      = \
+  	VBoxGuestA-os2.asm
+  ifdef VBOX_USE_WATCOM_FOR_OS2
+   VBoxGuest_LIBS        = \
+   	$(VBoxGuestLibOs2Hack_1_TARGET) \
+   	$(VBOX_LIB_VBGL_R0BASE) \
+   	$(VBOX_LIB_IPRT_GUEST_R0) \
+   	$(PATH_IGCC)/lib/libend.lib
+  else
+   VBoxGuest_SOURCES    += \
+   	VBoxGuest-os2.def
+   #VBoxGuest_LDFLAGS        = -s -t -v
+   VBoxGuest_LIBS        = \
+   	$(VBoxGuestLibOs2Hack_1_TARGET) \
+   	$(VBOX_LIB_VBGL_R0BASE) \
+   	$(VBOX_LIB_IPRT_GUEST_R0) \
+   	$(VBOX_GCC_LIBGCC) \
+   	end
+  endif
+  ## When debugging init with kDrvTest:
+  #VBoxGuest_NAME          = VBoxGst
+
+  # See above.
+  LIBRARIES += VBoxGuestLibOs2Hack
+  VBoxGuestLibOs2Hack_TEMPLATE = VBoxGuestR0DrvLib
+  VBoxGuestLibOs2Hack_INSTTYPE = none
+  VBoxGuestLibOs2Hack_DEFS = $(VBoxGuest_DEFS)
+  VBoxGuestLibOs2Hack_INCS = \
+  	. \
+  	$(PATH_ROOT)/src/VBox/Runtime/include # for the os2ddk
+  VBoxGuestLibOs2Hack_SOURCES = \
+  	VBoxGuest-os2.cpp \
+  	VBoxGuest.cpp
+ endif # OS/2
+
+ VBoxGuest.cpp_DEFS     = VBOX_SVN_REV=$(VBOX_SVN_REV)
+endif # enabled
+
+
+if defined(VBOX_WITH_ADDITION_DRIVERS) && "$(KBUILD_TARGET)" == "darwin"
+ # Files necessary to make a darwin kernel extension bundle.
+ INSTALLS += VBoxGuest.kext
+ VBoxGuest.kext_INST     = $(INST_ADDITIONS)/VBoxGuest.kext/Contents/
+ VBoxGuest.kext_SOURCES  = $(VBoxGuest.kext_0_OUTDIR)/Contents/Info.plist
+ VBoxGuest.kext_CLEAN    = $(VBoxGuest.kext_0_OUTDIR)/Contents/Info.plist
+ VBoxGuest.kext_BLDDIRS  = $(VBoxGuest.kext_0_OUTDIR)/Contents/
+
+ $$(VBoxGuest.kext_0_OUTDIR)/Contents/Info.plist: \
+ 		$(PATH_SUB_CURRENT)/darwin/Info.plist \
+ 		$(VBOX_VERSION_MK) | $$(dir $$@)
+	$(call MSG_GENERATE,VBoxGuest,$@,$<)
+	$(QUIET)$(RM) -f $@
+	$(QUIET)$(SED) \
+		-e 's+@VBOX_VERSION_STRING@+$(VBOX_VERSION_STRING)+g' \
+		-e 's+@VBOX_VERSION_MAJOR@+$(VBOX_VERSION_MAJOR)+g' \
+		-e 's+@VBOX_VERSION_MINOR@+$(VBOX_VERSION_MINOR)+g' \
+		-e 's+@VBOX_VERSION_BUILD@+$(VBOX_VERSION_BUILD)+g' \
+		-e 's+@VBOX_VENDOR@+$(VBOX_VENDOR)+g' \
+		-e 's+@VBOX_PRODUCT@+$(VBOX_PRODUCT)+g' \
+		-e 's+@VBOX_C_YEAR@+$(VBOX_C_YEAR)+g' \
+		--output $@ \
+		$<
+
+ $(evalcall2 VBOX_TEST_SIGN_KEXT,VBoxGuest)
+endif # darwin
+
+
+ifeq ($(KBUILD_TARGET),linux)
+ #
+ # Install the source files and script(s).
+ #
+ include $(PATH_SUB_CURRENT)/linux/files_vboxguest
+ # sources and stuff.
+ INSTALLS += vboxguest-src
+ vboxguest-src_INST     = $(INST_ADDITIONS)src/vboxguest/
+ vboxguest-src_MODE     = a+r,u+w
+ vboxguest-src_SOURCES  = $(subst ",,$(FILES_VBOXGUEST_NOBIN))
+
+ INSTALLS += vboxguest-scripts
+ vboxguest-scripts_INST    = $(INST_ADDITIONS)src/
+ vboxguest-scripts_MODE    = a+rx,u+w
+ vboxguest-scripts_SOURCES = ../../../HostDrivers/linux/build_in_tmp
+
+ # scripts.
+ INSTALLS += vboxguest-sh
+ vboxguest-sh_INST      = $(INST_ADDITIONS)src/vboxguest/
+ vboxguest-sh_MODE      = a+rx,u+w
+ vboxguest-sh_SOURCES   = $(subst ",,$(FILES_VBOXGUEST_BIN))
+
+ #
+ # Build test for the Guest Additions kernel module (kmk check).
+ #
+ $(evalcall2 VBOX_LINUX_KMOD_TEST_BUILD_RULE_FN,vboxguest-src,,save_symvers)
+endif # Linux
+
+ifeq ($(KBUILD_TARGET),freebsd)
+ #
+ # Install the source files and script(s).
+ #
+ include $(PATH_SUB_CURRENT)/freebsd/files_vboxguest
+ # sources and stuff.
+ INSTALLS += vboxguest-src
+ vboxguest-src_INST     = $(INST_ADDITIONS)src/vboxguest/
+ vboxguest-src_MODE     = a+r,u+w
+ vboxguest-src_SOURCES  = $(subst ",,$(FILES_VBOXGUEST_NOBIN))
+
+endif # FreeBSD
+
+ifeq ($(KBUILD_TARGET),win)
+ #
+ # VBoxGuestInst - The installer.
+ #
+ PROGRAMS.win.x86 += VBoxGuestInstNT
+ VBoxGuestInstNT_TEMPLATE = VBoxGuestR3Exe
+ ifndef VBOX_WITH_NOCRT_STATIC
+  VBoxGuestInstNT_LDFLAGS := -Include:_vcc100_kernel32_fakes_asm # Temporary kludge to deal with some link order issue.
+ endif
+ VBoxGuestInstNT_INCS     = ../../WINNT/include
+ VBoxGuestInstNT_SOURCES  = win/VBoxGuestInst.cpp
+ VBoxGuestInstNT_USES     = vboximportchecker
+ VBoxGuestInstNT_VBOX_IMPORT_CHECKER.win.x86 = nt31
+endif
+
+
+#
+# Helper script.
+#
+INSTALLS.solaris += VBoxGuestLoad
+VBoxGuestLoad_TEMPLATE = VBoxGuestR0Drv
+VBoxGuestLoad_EXEC_SOURCES = solaris/load.sh
+
+
+include $(FILE_KBUILD_SUB_FOOTER)
+
diff --git a/src/VBox/Additions/common/VBoxGuest/VBoxDev-haiku.c b/src/VBox/Additions/common/VBoxGuest/VBoxDev-haiku.c
new file mode 100644
index 00000000..1fb8d1f0
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/VBoxDev-haiku.c
@@ -0,0 +1,446 @@
+/* $Id: VBoxDev-haiku.c $ */
+/** @file
+ * VBoxGuest kernel driver, Haiku Guest Additions, implementation.
+ */
+
+/*
+ * 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
+ */
+
+/*
+ * This code is based on:
+ *
+ * VirtualBox Guest Additions for Haiku.
+ * Copyright (c) 2011 Mike Smith <mike@scgtrp.net>
+ *                    François Revol <revol@free.fr>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <sys/param.h>
+#include <sys/types.h>
+#include <sys/uio.h>
+#include <OS.h>
+#include <Drivers.h>
+#include <KernelExport.h>
+#include <PCI.h>
+
+#include "VBoxGuest-haiku.h"
+#include "VBoxGuestInternal.h"
+#include <VBox/log.h>
+#include <iprt/assert.h>
+#include <iprt/initterm.h>
+#include <iprt/process.h>
+#include <iprt/mem.h>
+#include <iprt/asm.h>
+
+#define DRIVER_NAME "vboxdev"
+#define DEVICE_NAME "misc/vboxguest"
+#define MODULE_NAME "generic/vboxguest"
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+int32 api_version = B_CUR_DRIVER_API_VERSION;
+
+
+/**
+ * Driver open hook.
+ *
+ * @param name          The name of the device as returned by publish_devices.
+ * @param flags         Open flags.
+ * @param cookie        Where to store the session pointer.
+ *
+ * @return Haiku status code.
+ */
+static status_t vgdrvHaikuOpen(const char *name, uint32 flags, void **cookie)
+{
+    int rc;
+    PVBOXGUESTSESSION pSession;
+
+    LogFlow((DRIVER_NAME ":vgdrvHaikuOpen\n"));
+
+    /*
+     * Create a new session.
+     */
+    rc = VGDrvCommonCreateUserSession(&g_DevExt, VMMDEV_REQUESTOR_USERMODE, &pSession);
+    if (RT_SUCCESS(rc))
+    {
+        Log((DRIVER_NAME ":vgdrvHaikuOpen success: g_DevExt=%p pSession=%p rc=%d pid=%d\n",&g_DevExt, pSession, rc,(int)RTProcSelf()));
+        ASMAtomicIncU32(&cUsers);
+        *cookie = pSession;
+        return B_OK;
+    }
+
+    LogRel((DRIVER_NAME ":vgdrvHaikuOpen: failed. rc=%d\n", rc));
+    return RTErrConvertToErrno(rc);
+}
+
+
+/**
+ * Driver close hook.
+ * @param cookie        The session.
+ *
+ * @return Haiku status code.
+ */
+static status_t vgdrvHaikuClose(void *cookie)
+{
+    PVBOXGUESTSESSION pSession = (PVBOXGUESTSESSION)cookie;
+    Log(("vgdrvHaikuClose: pSession=%p\n", pSession));
+
+    /** @todo r=ramshankar: should we really be using the session spinlock here? */
+    RTSpinlockAcquire(g_DevExt.SessionSpinlock);
+
+    /** @todo we don't know if it belongs to this session!! */
+    if (sState.selectSync)
+    {
+        //dprintf(DRIVER_NAME "close: unblocking select %p %x\n", sState.selectSync, sState.selectEvent);
+        notify_select_event(sState.selectSync, sState.selectEvent);
+        sState.selectEvent = (uint8_t)0;
+        sState.selectRef = (uint32_t)0;
+        sState.selectSync = (void *)NULL;
+    }
+
+    RTSpinlockRelease(g_DevExt.SessionSpinlock);
+    return B_OK;
+}
+
+
+/**
+ * Driver free hook.
+ * @param cookie        The session.
+ *
+ * @return Haiku status code.
+ */
+static status_t vgdrvHaikuFree(void *cookie)
+{
+    PVBOXGUESTSESSION pSession = (PVBOXGUESTSESSION)cookie;
+    Log(("vgdrvHaikuFree: pSession=%p\n", pSession));
+
+    /*
+     * Close the session if it's still hanging on to the device...
+     */
+    if (RT_VALID_PTR(pSession))
+    {
+        VGDrvCommonCloseSession(&g_DevExt, pSession);
+        ASMAtomicDecU32(&cUsers);
+    }
+    else
+        Log(("vgdrvHaikuFree: si_drv1=%p!\n", pSession));
+    return B_OK;
+}
+
+
+/**
+ * Driver IOCtl entry.
+ * @param cookie        The session.
+ * @param op            The operation to perform.
+ * @param data          The data associated with the operation.
+ * @param len           Size of the data in bytes.
+ *
+ * @return Haiku status code.
+ */
+static status_t vgdrvHaikuIOCtl(void *cookie, uint32 op, void *data, size_t len)
+{
+    PVBOXGUESTSESSION pSession = (PVBOXGUESTSESSION)cookie;
+    int rc;
+    Log(("vgdrvHaikuIOCtl: cookie=%p op=0x%08x data=%p len=%lu)\n", cookie, op, data, len));
+
+    /*
+     * Validate the input.
+     */
+    if (RT_UNLIKELY(!RT_VALID_PTR(pSession)))
+        return EINVAL;
+
+    /*
+     * Validate the request wrapper.
+     */
+#if 0
+    if (IOCPARM_LEN(ulCmd) != sizeof(VBGLBIGREQ))
+    {
+        Log((DRIVER_NAME ": vgdrvHaikuIOCtl: bad request %lu size=%lu expected=%d\n", ulCmd, IOCPARM_LEN(ulCmd),
+                                                                                        sizeof(VBGLBIGREQ)));
+        return ENOTTY;
+    }
+#endif
+
+    if (RT_UNLIKELY(len > _1M * 16))
+    {
+        dprintf(DRIVER_NAME ": vgdrvHaikuIOCtl: bad size %#x; pArg=%p Cmd=%lu.\n", (unsigned)len, data, op);
+        return EINVAL;
+    }
+
+    /*
+     * Read the request.
+     */
+    void *pvBuf = NULL;
+    if (RT_LIKELY(len > 0))
+    {
+        pvBuf = RTMemTmpAlloc(len);
+        if (RT_UNLIKELY(!pvBuf))
+        {
+            LogRel((DRIVER_NAME ":vgdrvHaikuIOCtl: RTMemTmpAlloc failed to alloc %d bytes.\n", len));
+            return ENOMEM;
+        }
+
+        /** @todo r=ramshankar: replace with RTR0MemUserCopyFrom() */
+        rc = user_memcpy(pvBuf, data, len);
+        if (RT_UNLIKELY(rc < 0))
+        {
+            RTMemTmpFree(pvBuf);
+            LogRel((DRIVER_NAME ":vgdrvHaikuIOCtl: user_memcpy failed; pvBuf=%p data=%p op=%d. rc=%d\n", pvBuf, data, op, rc));
+            return EFAULT;
+        }
+        if (RT_UNLIKELY(!RT_VALID_PTR(pvBuf)))
+        {
+            RTMemTmpFree(pvBuf);
+            LogRel((DRIVER_NAME ":vgdrvHaikuIOCtl: pvBuf invalid pointer %p\n", pvBuf));
+            return EINVAL;
+        }
+    }
+    Log(("vgdrvHaikuIOCtl: pSession=%p pid=%d.\n", pSession,(int)RTProcSelf()));
+
+    /*
+     * Process the IOCtl.
+     */
+    size_t cbDataReturned;
+    rc = VGDrvCommonIoCtl(op, &g_DevExt, pSession, pvBuf, len, &cbDataReturned);
+    if (RT_SUCCESS(rc))
+    {
+        rc = 0;
+        if (RT_UNLIKELY(cbDataReturned > len))
+        {
+            Log(("vgdrvHaikuIOCtl: too much output data %d expected %d\n", cbDataReturned, len));
+            cbDataReturned = len;
+        }
+        if (cbDataReturned > 0)
+        {
+            rc = user_memcpy(data, pvBuf, cbDataReturned);
+            if (RT_UNLIKELY(rc < 0))
+            {
+                Log(("vgdrvHaikuIOCtl: user_memcpy failed; pvBuf=%p pArg=%p Cmd=%lu. rc=%d\n", pvBuf, data, op, rc));
+                rc = EFAULT;
+            }
+        }
+    }
+    else
+    {
+        Log(("vgdrvHaikuIOCtl: VGDrvCommonIoCtl failed. rc=%d\n", rc));
+        rc = EFAULT;
+    }
+    RTMemTmpFree(pvBuf);
+    return rc;
+}
+
+
+/**
+ * Driver select hook.
+ *
+ * @param cookie        The session.
+ * @param event         The event.
+ * @param ref           ???
+ * @param sync          ???
+ *
+ * @return Haiku status code.
+ */
+static status_t vgdrvHaikuSelect(void *cookie, uint8 event, uint32 ref, selectsync *sync)
+{
+    PVBOXGUESTSESSION pSession = (PVBOXGUESTSESSION)cookie;
+    status_t err = B_OK;
+
+    switch (event)
+    {
+        case B_SELECT_READ:
+            break;
+        default:
+            return EINVAL;
+    }
+
+    RTSpinlockAcquire(g_DevExt.SessionSpinlock);
+
+    uint32_t u32CurSeq = ASMAtomicUoReadU32(&g_DevExt.u32MousePosChangedSeq);
+    if (pSession->u32MousePosChangedSeq != u32CurSeq)
+    {
+        pSession->u32MousePosChangedSeq = u32CurSeq;
+        notify_select_event(sync, event);
+    }
+    else if (sState.selectSync == NULL)
+    {
+        sState.selectEvent = (uint8_t)event;
+        sState.selectRef = (uint32_t)ref;
+        sState.selectSync = (void *)sync;
+    }
+    else
+        err = B_WOULD_BLOCK;
+
+    RTSpinlockRelease(g_DevExt.SessionSpinlock);
+
+    return err;
+}
+
+
+/**
+ * Driver deselect hook.
+ * @param cookie        The session.
+ * @param event         The event.
+ * @param sync          ???
+ *
+ * @return Haiku status code.
+ */
+static status_t vgdrvHaikuDeselect(void *cookie, uint8 event, selectsync *sync)
+{
+    PVBOXGUESTSESSION pSession = (PVBOXGUESTSESSION)cookie;
+    status_t err = B_OK;
+    //dprintf(DRIVER_NAME "deselect(,%d,%p)\n", event, sync);
+
+    RTSpinlockAcquire(g_DevExt.SessionSpinlock);
+
+    if (sState.selectSync == sync)
+    {
+        //dprintf(DRIVER_NAME "deselect: dropping: %p %x\n", sState.selectSync, sState.selectEvent);
+        sState.selectEvent = (uint8_t)0;
+        sState.selectRef = (uint32_t)0;
+        sState.selectSync = NULL;
+    }
+    else
+        err = B_OK;
+
+    RTSpinlockRelease(g_DevExt.SessionSpinlock);
+    return err;
+}
+
+
+/**
+ * Driver write hook.
+ * @param cookie            The session.
+ * @param position          The offset.
+ * @param data              Pointer to the data.
+ * @param numBytes          Where to store the number of bytes written.
+ *
+ * @return Haiku status code.
+ */
+static status_t vgdrvHaikuWrite(void *cookie, off_t position, const void *data, size_t *numBytes)
+{
+    *numBytes = 0;
+    return B_OK;
+}
+
+
+/**
+ * Driver read hook.
+ * @param cookie            The session.
+ * @param position          The offset.
+ * @param data              Pointer to the data.
+ * @param numBytes          Where to store the number of bytes read.
+ *
+ * @return Haiku status code.
+ */
+static status_t vgdrvHaikuRead(void *cookie, off_t position, void *data, size_t *numBytes)
+{
+    PVBOXGUESTSESSION pSession = (PVBOXGUESTSESSION)cookie;
+
+    if (*numBytes == 0)
+        return B_OK;
+
+    uint32_t u32CurSeq = ASMAtomicUoReadU32(&g_DevExt.u32MousePosChangedSeq);
+    if (pSession->u32MousePosChangedSeq != u32CurSeq)
+    {
+        pSession->u32MousePosChangedSeq = u32CurSeq;
+        *numBytes = 1;
+        return B_OK;
+    }
+
+    *numBytes = 0;
+    return B_OK;
+}
+
+
+
+status_t init_hardware()
+{
+    return get_module(MODULE_NAME, (module_info **)&g_VBoxGuest);
+}
+
+status_t init_driver()
+{
+    return B_OK;
+}
+
+device_hooks *find_device(const char *name)
+{
+    static device_hooks s_vgdrvHaikuDeviceHooks =
+    {
+        vgdrvHaikuOpen,
+        vgdrvHaikuClose,
+        vgdrvHaikuFree,
+        vgdrvHaikuIOCtl,
+        vgdrvHaikuRead,
+        vgdrvHaikuWrite,
+        vgdrvHaikuSelect,
+        vgdrvHaikuDeselect,
+    };
+    return &s_vgdrvHaikuDeviceHooks;
+}
+
+const char **publish_devices()
+{
+    static const char *s_papszDevices[] = { DEVICE_NAME, NULL };
+    return s_papszDevices;
+}
+
+void uninit_driver()
+{
+    put_module(MODULE_NAME);
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/VBoxGuest-darwin.cpp b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-darwin.cpp
new file mode 100644
index 00000000..1ee85362
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-darwin.cpp
@@ -0,0 +1,1393 @@
+/* $Id: VBoxGuest-darwin.cpp $ */
+/** @file
+ * VBoxGuest - Darwin Specifics.
+ */
+
+/*
+ * 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 LOG_GROUP LOG_GROUP_VGDRV
+/*
+ * Deal with conflicts first.
+ * PVM - BSD mess, that FreeBSD has correct a long time ago.
+ * iprt/types.h before sys/param.h - prevents UINT32_C and friends.
+ */
+#include <iprt/types.h>
+#include <sys/param.h>
+#undef PVM
+
+#include <IOKit/IOLib.h> /* Assert as function */
+
+#include <VBox/version.h>
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/initterm.h>
+#include <iprt/mem.h>
+#include <iprt/power.h>
+#include <iprt/process.h>
+#include <iprt/semaphore.h>
+#include <iprt/spinlock.h>
+#include <iprt/string.h>
+#include <VBox/err.h>
+#include <VBox/log.h>
+
+#include <mach/kmod.h>
+#include <miscfs/devfs/devfs.h>
+#include <sys/conf.h>
+#include <sys/errno.h>
+#include <sys/ioccom.h>
+#include <sys/malloc.h>
+#include <sys/proc.h>
+#include <sys/kauth.h>
+#define _OS_OSUNSERIALIZE_H /* HACK ALERT! Block importing OSUnserialized.h as it causes compilation trouble with
+                               newer clang versions and the 10.15 SDK, and we really don't need it. Sample error:
+                               libkern/c++/OSUnserialize.h:72:2: error: use of OSPtr outside of a return type [-Werror,-Wossharedptr-misuse] */
+#include <IOKit/IOService.h>
+#include <IOKit/IOUserClient.h>
+#include <IOKit/pwr_mgt/RootDomain.h>
+#include <IOKit/pci/IOPCIDevice.h>
+#include <IOKit/IOBufferMemoryDescriptor.h>
+#include <IOKit/IOFilterInterruptEventSource.h>
+#include "VBoxGuestInternal.h"
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+/** The system device node name. */
+#define DEVICE_NAME_SYS     "vboxguest"
+/** The user device node name. */
+#define DEVICE_NAME_USR     "vboxguestu"
+
+
+/** @name For debugging/whatever, now permanent.
+ * @{  */
+#define VBOX_PROC_SELFNAME_LEN              31
+#define VBOX_RETRIEVE_CUR_PROC_NAME(a_Name) char a_Name[VBOX_PROC_SELFNAME_LEN + 1]; \
+                                            proc_selfname(a_Name, VBOX_PROC_SELFNAME_LEN)
+/** @} */
+
+#ifndef minor
+/* The inlined C++ function version minor() takes the wrong parameter
+   type, uint32_t instead of dev_t.  This kludge works around that. */
+# define minor(x) minor((uint32_t)(x))
+#endif
+
+
+/*********************************************************************************************************************************
+*   Internal Functions                                                                                                           *
+*********************************************************************************************************************************/
+RT_C_DECLS_BEGIN
+static kern_return_t    vgdrvDarwinStart(struct kmod_info *pKModInfo, void *pvData);
+static kern_return_t    vgdrvDarwinStop(struct kmod_info *pKModInfo, void *pvData);
+static int              vgdrvDarwinCharDevRemove(void);
+
+static int              vgdrvDarwinOpen(dev_t Dev, int fFlags, int fDevType, struct proc *pProcess);
+static int              vgdrvDarwinClose(dev_t Dev, int fFlags, int fDevType, struct proc *pProcess);
+static int              vgdrvDarwinIOCtlSlow(PVBOXGUESTSESSION pSession, u_long iCmd, caddr_t pData, struct proc *pProcess);
+static int              vgdrvDarwinIOCtl(dev_t Dev, u_long iCmd, caddr_t pData, int fFlags, struct proc *pProcess);
+
+static int              vgdrvDarwinErr2DarwinErr(int rc);
+
+static IOReturn         vgdrvDarwinSleepHandler(void *pvTarget, void *pvRefCon, UInt32 uMessageType, IOService *pProvider, void *pvMessageArgument, vm_size_t argSize);
+RT_C_DECLS_END
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * The service class for handling the VMMDev PCI device.
+ *
+ * Instantiated when the module is loaded (and on PCI hotplugging?).
+ */
+class org_virtualbox_VBoxGuest : public IOService
+{
+    OSDeclareDefaultStructors(org_virtualbox_VBoxGuest);
+
+private:
+    IOPCIDevice                *m_pIOPCIDevice;
+    IOMemoryMap                *m_pMap;
+    IOFilterInterruptEventSource *m_pInterruptSrc;
+
+    bool setupVmmDevInterrupts(IOService *pProvider);
+    bool disableVmmDevInterrupts(void);
+    bool isVmmDev(IOPCIDevice *pIOPCIDevice);
+
+protected:
+    /** Non-NULL if interrupts are registered.  Probably same as getProvider(). */
+    IOService                 *m_pInterruptProvider;
+
+public:
+    virtual bool init(OSDictionary *pDictionary = 0);
+    virtual void free(void);
+    virtual IOService *probe(IOService *pProvider, SInt32 *pi32Score);
+    virtual bool start(IOService *pProvider);
+    virtual void stop(IOService *pProvider);
+    virtual bool terminate(IOOptionBits fOptions);
+    static void  vgdrvDarwinIrqHandler(OSObject *pTarget, void *pvRefCon, IOService *pNub, int iSrc);
+};
+
+OSDefineMetaClassAndStructors(org_virtualbox_VBoxGuest, IOService);
+
+
+/**
+ * An attempt at getting that clientDied() notification.
+ * I don't think it'll work as I cannot figure out where/what creates the correct
+ * port right.
+ *
+ * Instantiated when userland does IOServiceOpen().
+ */
+class org_virtualbox_VBoxGuestClient : public IOUserClient
+{
+    OSDeclareDefaultStructors(org_virtualbox_VBoxGuestClient);
+
+private:
+    /** Guard against the parent class growing and us using outdated headers. */
+    uint8_t m_abSafetyPadding[256];
+
+    PVBOXGUESTSESSION           m_pSession;     /**< The session. */
+    task_t                      m_Task;         /**< The client task. */
+    org_virtualbox_VBoxGuest   *m_pProvider;    /**< The service provider. */
+
+public:
+    virtual bool initWithTask(task_t OwningTask, void *pvSecurityId, UInt32 u32Type);
+    virtual bool start(IOService *pProvider);
+    static  void sessionClose(RTPROCESS Process);
+    virtual IOReturn clientClose(void);
+    virtual IOReturn clientDied(void);
+    virtual bool terminate(IOOptionBits fOptions = 0);
+    virtual bool finalize(IOOptionBits fOptions);
+    virtual void stop(IOService *pProvider);
+
+    RTR0MEMEF_NEW_AND_DELETE_OPERATORS_IOKIT();
+};
+
+OSDefineMetaClassAndStructors(org_virtualbox_VBoxGuestClient, IOUserClient);
+
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/**
+ * Declare the module stuff.
+ */
+RT_C_DECLS_BEGIN
+extern kern_return_t _start(struct kmod_info *pKModInfo, void *pvData);
+extern kern_return_t _stop(struct kmod_info *pKModInfo, void *pvData);
+
+KMOD_EXPLICIT_DECL(VBoxGuest, VBOX_VERSION_STRING, _start, _stop)
+DECL_HIDDEN_DATA(kmod_start_func_t *) _realmain = vgdrvDarwinStart;
+DECL_HIDDEN_DATA(kmod_stop_func_t *)  _antimain = vgdrvDarwinStop;
+DECL_HIDDEN_DATA(int)                 _kext_apple_cc = __APPLE_CC__;
+RT_C_DECLS_END
+
+
+/**
+ * Device extention & session data association structure.
+ */
+static VBOXGUESTDEVEXT  g_DevExt;
+
+/**
+ * The character device switch table for the driver.
+ */
+static struct cdevsw    g_DevCW =
+{
+    /*.d_open     = */ vgdrvDarwinOpen,
+    /*.d_close    = */ vgdrvDarwinClose,
+    /*.d_read     = */ eno_rdwrt,
+    /*.d_write    = */ eno_rdwrt,
+    /*.d_ioctl    = */ vgdrvDarwinIOCtl,
+    /*.d_stop     = */ eno_stop,
+    /*.d_reset    = */ eno_reset,
+    /*.d_ttys     = */ NULL,
+    /*.d_select   = */ eno_select,
+    /*.d_mmap     = */ eno_mmap,
+    /*.d_strategy = */ eno_strat,
+    /*.d_getc     = */ (void *)(uintptr_t)&enodev, //eno_getc,
+    /*.d_putc     = */ (void *)(uintptr_t)&enodev, //eno_putc,
+    /*.d_type     = */ 0
+};
+
+/** Major device number. */
+static int                  g_iMajorDeviceNo = -1;
+/** Registered devfs device handle. */
+static void                *g_hDevFsDeviceSys = NULL;
+/** Registered devfs device handle for the user device. */
+static void                *g_hDevFsDeviceUsr = NULL; /**< @todo 4 later */
+
+/** Spinlock protecting g_apSessionHashTab. */
+static RTSPINLOCK           g_Spinlock = NIL_RTSPINLOCK;
+/** Hash table */
+static PVBOXGUESTSESSION    g_apSessionHashTab[19];
+/** Calculates the index into g_apSessionHashTab.*/
+#define SESSION_HASH(pid)   ((pid) % RT_ELEMENTS(g_apSessionHashTab))
+/** The number of open sessions. */
+static int32_t volatile     g_cSessions = 0;
+/** Makes sure there is only one org_virtualbox_VBoxGuest instance. */
+static bool volatile        g_fInstantiated = 0;
+/** The notifier handle for the sleep callback handler. */
+static IONotifier          *g_pSleepNotifier = NULL;
+
+
+/**
+ * Start the kernel module.
+ */
+static kern_return_t    vgdrvDarwinStart(struct kmod_info *pKModInfo, void *pvData)
+{
+    RT_NOREF(pKModInfo, pvData);
+#ifdef DEBUG
+    printf("vgdrvDarwinStart\n");
+#endif
+#if 0
+    gIOKitDebug |= 0x001 //kIOLogAttach
+                |  0x002 //kIOLogProbe
+                |  0x004 //kIOLogStart
+                |  0x008 //kIOLogRegister
+                |  0x010 //kIOLogMatch
+                |  0x020 //kIOLogConfig
+                ;
+#endif
+
+    /*
+     * Initialize IPRT.
+     */
+    int rc = RTR0Init(0);
+    if (RT_SUCCESS(rc))
+    {
+        Log(("VBoxGuest: driver loaded\n"));
+        return KMOD_RETURN_SUCCESS;
+    }
+
+    RTLogBackdoorPrintf("VBoxGuest: RTR0Init failed with rc=%Rrc\n", rc);
+    printf("VBoxGuest: RTR0Init failed with rc=%d\n", rc);
+    return KMOD_RETURN_FAILURE;
+}
+
+
+/**
+ * Stop the kernel module.
+ */
+static kern_return_t vgdrvDarwinStop(struct kmod_info *pKModInfo, void *pvData)
+{
+    RT_NOREF(pKModInfo, pvData);
+
+    /** @todo we need to check for VBoxSF clients? */
+
+    RTLogBackdoorPrintf("VBoxGuest: calling RTR0TermForced ...\n");
+    RTR0TermForced();
+
+    RTLogBackdoorPrintf("VBoxGuest: vgdrvDarwinStop returns.\n");
+    printf("VBoxGuest: driver unloaded\n");
+    return KMOD_RETURN_SUCCESS;
+}
+
+
+/**
+ * Register VBoxGuest char device
+ */
+static int vgdrvDarwinCharDevInit(void)
+{
+    int rc = RTSpinlockCreate(&g_Spinlock, RTSPINLOCK_FLAGS_INTERRUPT_SAFE, "VBoxGuestDarwin");
+    if (RT_SUCCESS(rc))
+    {
+        /*
+         * Registering ourselves as a character device.
+         */
+        g_iMajorDeviceNo = cdevsw_add(-1, &g_DevCW);
+        if (g_iMajorDeviceNo >= 0)
+        {
+            /** @todo limit /dev/vboxguest access. */
+            g_hDevFsDeviceSys = devfs_make_node(makedev((uint32_t)g_iMajorDeviceNo, 0), DEVFS_CHAR,
+                                                UID_ROOT, GID_WHEEL, 0666, DEVICE_NAME_SYS);
+            if (g_hDevFsDeviceSys != NULL)
+            {
+                /*
+                 * And a all-user device.
+                 */
+                g_hDevFsDeviceUsr = devfs_make_node(makedev((uint32_t)g_iMajorDeviceNo, 1), DEVFS_CHAR,
+                                                    UID_ROOT, GID_WHEEL, 0666, DEVICE_NAME_USR);
+                if (g_hDevFsDeviceUsr != NULL)
+                {
+                    /*
+                     * Register a sleep/wakeup notification callback.
+                     */
+                    g_pSleepNotifier = registerPrioritySleepWakeInterest(&vgdrvDarwinSleepHandler, &g_DevExt, NULL);
+                    if (g_pSleepNotifier != NULL)
+                        return KMOD_RETURN_SUCCESS;
+                }
+            }
+        }
+        vgdrvDarwinCharDevRemove();
+    }
+    return KMOD_RETURN_FAILURE;
+}
+
+
+/**
+ * Unregister VBoxGuest char devices and associated session spinlock.
+ */
+static int vgdrvDarwinCharDevRemove(void)
+{
+    if (g_pSleepNotifier)
+    {
+        g_pSleepNotifier->remove();
+        g_pSleepNotifier = NULL;
+    }
+
+    if (g_hDevFsDeviceSys)
+    {
+        devfs_remove(g_hDevFsDeviceSys);
+        g_hDevFsDeviceSys = NULL;
+    }
+
+    if (g_hDevFsDeviceUsr)
+    {
+        devfs_remove(g_hDevFsDeviceUsr);
+        g_hDevFsDeviceUsr = NULL;
+    }
+
+    if (g_iMajorDeviceNo != -1)
+    {
+        int rc2 = cdevsw_remove(g_iMajorDeviceNo, &g_DevCW);
+        Assert(rc2 == g_iMajorDeviceNo); NOREF(rc2);
+        g_iMajorDeviceNo = -1;
+    }
+
+    if (g_Spinlock != NIL_RTSPINLOCK)
+    {
+        int rc2 = RTSpinlockDestroy(g_Spinlock); AssertRC(rc2);
+        g_Spinlock = NIL_RTSPINLOCK;
+    }
+
+    return KMOD_RETURN_SUCCESS;
+}
+
+
+/**
+ * Device open. Called on open /dev/vboxguest and (later) /dev/vboxguestu.
+ *
+ * @param   Dev         The device number.
+ * @param   fFlags      ???.
+ * @param   fDevType    ???.
+ * @param   pProcess    The process issuing this request.
+ */
+static int vgdrvDarwinOpen(dev_t Dev, int fFlags, int fDevType, struct proc *pProcess)
+{
+    RT_NOREF(fFlags,  fDevType);
+
+    /*
+     * Only two minor devices numbers are allowed.
+     */
+    if (minor(Dev) != 0 && minor(Dev) != 1)
+        return EACCES;
+
+    /*
+     * The process issuing the request must be the current process.
+     */
+    RTPROCESS Process = RTProcSelf();
+    if ((int)Process != proc_pid(pProcess))
+        return EIO;
+
+    /*
+     * Find the session created by org_virtualbox_VBoxGuestClient, fail
+     * if no such session, and mark it as opened. We set the uid & gid
+     * here too, since that is more straight forward at this point.
+     */
+    const bool          fUnrestricted = minor(Dev) == 0;
+    int                 rc = VINF_SUCCESS;
+    PVBOXGUESTSESSION   pSession = NULL;
+    kauth_cred_t        pCred = kauth_cred_proc_ref(pProcess);
+    if (pCred)
+    {
+#if MAC_OS_X_VERSION_MIN_REQUIRED >= 1070
+        RTUID           Uid = kauth_cred_getruid(pCred);
+        RTGID           Gid = kauth_cred_getrgid(pCred);
+#else
+        RTUID           Uid = pCred->cr_ruid;
+        RTGID           Gid = pCred->cr_rgid;
+#endif
+        unsigned        iHash = SESSION_HASH(Process);
+        RTSpinlockAcquire(g_Spinlock);
+
+        pSession = g_apSessionHashTab[iHash];
+        while (pSession && pSession->Process != Process)
+            pSession = pSession->pNextHash;
+        if (pSession)
+        {
+            if (!pSession->fOpened)
+            {
+                pSession->fOpened = true;
+                pSession->fUserSession = !fUnrestricted;
+                pSession->fRequestor = VMMDEV_REQUESTOR_USERMODE | VMMDEV_REQUESTOR_TRUST_NOT_GIVEN;
+                if (Uid == 0)
+                    pSession->fRequestor |= VMMDEV_REQUESTOR_USR_ROOT;
+                else
+                    pSession->fRequestor |= VMMDEV_REQUESTOR_USR_USER;
+                if (Gid == 0)
+                    pSession->fRequestor |= VMMDEV_REQUESTOR_GRP_WHEEL;
+                if (!fUnrestricted)
+                    pSession->fRequestor |= VMMDEV_REQUESTOR_USER_DEVICE;
+                pSession->fRequestor |= VMMDEV_REQUESTOR_CON_DONT_KNOW; /** @todo see if we can figure out console relationship of pProc. */
+            }
+            else
+                rc = VERR_ALREADY_LOADED;
+        }
+        else
+            rc = VERR_GENERAL_FAILURE;
+
+        RTSpinlockRelease(g_Spinlock);
+#if MAC_OS_X_VERSION_MIN_REQUIRED >= 1050
+        kauth_cred_unref(&pCred);
+#else  /* 10.4 */
+        /* The 10.4u SDK headers and 10.4.11 kernel source have inconsistent definitions
+           of kauth_cred_unref(), so use the other (now deprecated) API for releasing it. */
+        kauth_cred_rele(pCred);
+#endif /* 10.4 */
+    }
+    else
+        rc = VERR_INVALID_PARAMETER;
+
+    Log(("vgdrvDarwinOpen: g_DevExt=%p pSession=%p rc=%d pid=%d\n", &g_DevExt, pSession, rc, proc_pid(pProcess)));
+    return vgdrvDarwinErr2DarwinErr(rc);
+}
+
+
+/**
+ * Close device.
+ */
+static int vgdrvDarwinClose(dev_t Dev, int fFlags, int fDevType, struct proc *pProcess)
+{
+    RT_NOREF(Dev, fFlags, fDevType, pProcess);
+    Log(("vgdrvDarwinClose: pid=%d\n", (int)RTProcSelf()));
+    Assert(proc_pid(pProcess) == (int)RTProcSelf());
+
+    /*
+     * Hand the session closing to org_virtualbox_VBoxGuestClient.
+     */
+    org_virtualbox_VBoxGuestClient::sessionClose(RTProcSelf());
+    return 0;
+}
+
+
+/**
+ * Device I/O Control entry point.
+ *
+ * @returns Darwin for slow IOCtls and VBox status code for the fast ones.
+ * @param   Dev         The device number (major+minor).
+ * @param   iCmd        The IOCtl command.
+ * @param   pData       Pointer to the request data.
+ * @param   fFlags      Flag saying we're a character device (like we didn't know already).
+ * @param   pProcess    The process issuing this request.
+ */
+static int vgdrvDarwinIOCtl(dev_t Dev, u_long iCmd, caddr_t pData, int fFlags, struct proc *pProcess)
+{
+    RT_NOREF(Dev, fFlags);
+    const bool          fUnrestricted = minor(Dev) == 0;
+    const RTPROCESS     Process = (RTPROCESS)proc_pid(pProcess);
+    const unsigned      iHash = SESSION_HASH(Process);
+    PVBOXGUESTSESSION   pSession;
+
+    /*
+     * Find the session.
+     */
+    RTSpinlockAcquire(g_Spinlock);
+    pSession = g_apSessionHashTab[iHash];
+    while (pSession && (pSession->Process != Process || pSession->fUserSession == fUnrestricted || !pSession->fOpened))
+        pSession = pSession->pNextHash;
+
+    //if (RT_LIKELY(pSession))
+    //    supdrvSessionRetain(pSession);
+
+    RTSpinlockRelease(g_Spinlock);
+    if (!pSession)
+    {
+        Log(("VBoxDrvDarwinIOCtl: WHAT?!? pSession == NULL! This must be a mistake... pid=%d iCmd=%#lx\n",
+             (int)Process, iCmd));
+        return EINVAL;
+    }
+
+    /*
+     * Deal with the high-speed IOCtl.
+     */
+    int rc;
+    if (VBGL_IOCTL_IS_FAST(iCmd))
+        rc = VGDrvCommonIoCtlFast(iCmd, &g_DevExt, pSession);
+    else
+        rc = vgdrvDarwinIOCtlSlow(pSession, iCmd, pData, pProcess);
+
+    //supdrvSessionRelease(pSession);
+    return rc;
+}
+
+
+/**
+ * Worker for VBoxDrvDarwinIOCtl that takes the slow IOCtl functions.
+ *
+ * @returns Darwin errno.
+ *
+ * @param pSession  The session.
+ * @param iCmd      The IOCtl command.
+ * @param pData     Pointer to the request data.
+ * @param pProcess  The calling process.
+ */
+static int vgdrvDarwinIOCtlSlow(PVBOXGUESTSESSION pSession, u_long iCmd, caddr_t pData, struct proc *pProcess)
+{
+    RT_NOREF(pProcess);
+    LogFlow(("vgdrvDarwinIOCtlSlow: pSession=%p iCmd=%p pData=%p pProcess=%p\n", pSession, iCmd, pData, pProcess));
+
+
+    /*
+     * Buffered or unbuffered?
+     */
+    PVBGLREQHDR pHdr;
+    user_addr_t pUser = 0;
+    void *pvPageBuf = NULL;
+    uint32_t cbReq = IOCPARM_LEN(iCmd);
+    if ((IOC_DIRMASK & iCmd) == IOC_INOUT)
+    {
+        pHdr = (PVBGLREQHDR)pData;
+        if (RT_UNLIKELY(cbReq < sizeof(*pHdr)))
+        {
+            LogRel(("vgdrvDarwinIOCtlSlow: cbReq=%#x < %#x; iCmd=%#lx\n", cbReq, (int)sizeof(*pHdr), iCmd));
+            return EINVAL;
+        }
+        if (RT_UNLIKELY(pHdr->uVersion != VBGLREQHDR_VERSION))
+        {
+            LogRel(("vgdrvDarwinIOCtlSlow: bad uVersion=%#x; iCmd=%#lx\n", pHdr->uVersion, iCmd));
+            return EINVAL;
+        }
+        if (RT_UNLIKELY(   RT_MAX(pHdr->cbIn, pHdr->cbOut) != cbReq
+                        || pHdr->cbIn < sizeof(*pHdr)
+                        || (pHdr->cbOut < sizeof(*pHdr) && pHdr->cbOut != 0)))
+        {
+            LogRel(("vgdrvDarwinIOCtlSlow: max(%#x,%#x) != %#x; iCmd=%#lx\n", pHdr->cbIn, pHdr->cbOut, cbReq, iCmd));
+            return EINVAL;
+        }
+    }
+    else if ((IOC_DIRMASK & iCmd) == IOC_VOID && !cbReq)
+    {
+        /*
+         * Get the header and figure out how much we're gonna have to read.
+         */
+        VBGLREQHDR Hdr;
+        pUser = (user_addr_t)*(void **)pData;
+        int rc = copyin(pUser, &Hdr, sizeof(Hdr));
+        if (RT_UNLIKELY(rc))
+        {
+            LogRel(("vgdrvDarwinIOCtlSlow: copyin(%llx,Hdr,) -> %#x; iCmd=%#lx\n", (unsigned long long)pUser, rc, iCmd));
+            return rc;
+        }
+        if (RT_UNLIKELY(Hdr.uVersion != VBGLREQHDR_VERSION))
+        {
+            LogRel(("vgdrvDarwinIOCtlSlow: bad uVersion=%#x; iCmd=%#lx\n", Hdr.uVersion, iCmd));
+            return EINVAL;
+        }
+        cbReq = RT_MAX(Hdr.cbIn, Hdr.cbOut);
+        if (RT_UNLIKELY(   Hdr.cbIn < sizeof(Hdr)
+                        || (Hdr.cbOut < sizeof(Hdr) && Hdr.cbOut != 0)
+                        || cbReq > _1M*16))
+        {
+            LogRel(("vgdrvDarwinIOCtlSlow: max(%#x,%#x); iCmd=%#lx\n", Hdr.cbIn, Hdr.cbOut, iCmd));
+            return EINVAL;
+        }
+
+        /*
+         * Allocate buffer and copy in the data.
+         */
+        pHdr = (PVBGLREQHDR)RTMemTmpAlloc(cbReq);
+        if (!pHdr)
+            pvPageBuf = pHdr = (PVBGLREQHDR)IOMallocAligned(RT_ALIGN_Z(cbReq, PAGE_SIZE), 8);
+        if (RT_UNLIKELY(!pHdr))
+        {
+            LogRel(("vgdrvDarwinIOCtlSlow: failed to allocate buffer of %d bytes; iCmd=%#lx\n", cbReq, iCmd));
+            return ENOMEM;
+        }
+        rc = copyin(pUser, pHdr, Hdr.cbIn);
+        if (RT_UNLIKELY(rc))
+        {
+            LogRel(("vgdrvDarwinIOCtlSlow: copyin(%llx,%p,%#x) -> %#x; iCmd=%#lx\n",
+                    (unsigned long long)pUser, pHdr, Hdr.cbIn, rc, iCmd));
+            if (pvPageBuf)
+                IOFreeAligned(pvPageBuf, RT_ALIGN_Z(cbReq, PAGE_SIZE));
+            else
+                RTMemTmpFree(pHdr);
+            return rc;
+        }
+        if (Hdr.cbIn < cbReq)
+            RT_BZERO((uint8_t *)pHdr + Hdr.cbIn, cbReq - Hdr.cbIn);
+    }
+    else
+    {
+        Log(("vgdrvDarwinIOCtlSlow: huh? cbReq=%#x iCmd=%#lx\n", cbReq, iCmd));
+        return EINVAL;
+    }
+
+    /*
+     * Process the IOCtl.
+     */
+    int rc = VGDrvCommonIoCtl(iCmd, &g_DevExt, pSession, pHdr, cbReq);
+    if (RT_LIKELY(!rc))
+    {
+        /*
+         * If not buffered, copy back the buffer before returning.
+         */
+        if (pUser)
+        {
+            uint32_t cbOut = pHdr->cbOut;
+            if (cbOut > cbReq)
+            {
+                LogRel(("vgdrvDarwinIOCtlSlow: too much output! %#x > %#x; uCmd=%#lx!\n", cbOut, cbReq, iCmd));
+                cbOut = cbReq;
+            }
+            rc = copyout(pHdr, pUser, cbOut);
+            if (RT_UNLIKELY(rc))
+                LogRel(("vgdrvDarwinIOCtlSlow: copyout(%p,%llx,%#x) -> %d; uCmd=%#lx!\n",
+                        pHdr, (unsigned long long)pUser, cbOut, rc, iCmd));
+
+            /* cleanup */
+            if (pvPageBuf)
+                IOFreeAligned(pvPageBuf, RT_ALIGN_Z(cbReq, PAGE_SIZE));
+            else
+                RTMemTmpFree(pHdr);
+        }
+    }
+    else
+    {
+        /*
+         * The request failed, just clean up.
+         */
+        if (pUser)
+        {
+            if (pvPageBuf)
+                IOFreeAligned(pvPageBuf, RT_ALIGN_Z(cbReq, PAGE_SIZE));
+            else
+                RTMemTmpFree(pHdr);
+        }
+
+        Log(("vgdrvDarwinIOCtlSlow: pid=%d iCmd=%lx pData=%p failed, rc=%d\n", proc_pid(pProcess), iCmd, (void *)pData, rc));
+        rc = EINVAL;
+    }
+
+    Log2(("vgdrvDarwinIOCtlSlow: returns %d\n", rc));
+    return rc;
+}
+
+
+/**
+ * @note This code is duplicated on other platforms with variations, so please
+ *       keep them all up to date when making changes!
+ */
+int VBOXCALL VBoxGuestIDC(void *pvSession, uintptr_t uReq, PVBGLREQHDR pReqHdr, size_t cbReq)
+{
+    /*
+     * Simple request validation (common code does the rest).
+     */
+    int rc;
+    if (   RT_VALID_PTR(pReqHdr)
+        && cbReq >= sizeof(*pReqHdr))
+    {
+        /*
+         * All requests except the connect one requires a valid session.
+         */
+        PVBOXGUESTSESSION pSession = (PVBOXGUESTSESSION)pvSession;
+        if (pSession)
+        {
+            if (   RT_VALID_PTR(pSession)
+                && pSession->pDevExt == &g_DevExt)
+                rc = VGDrvCommonIoCtl(uReq, &g_DevExt, pSession, pReqHdr, cbReq);
+            else
+                rc = VERR_INVALID_HANDLE;
+        }
+        else if (uReq == VBGL_IOCTL_IDC_CONNECT)
+        {
+            rc = VGDrvCommonCreateKernelSession(&g_DevExt, &pSession);
+            if (RT_SUCCESS(rc))
+            {
+                rc = VGDrvCommonIoCtl(uReq, &g_DevExt, pSession, pReqHdr, cbReq);
+                if (RT_FAILURE(rc))
+                    VGDrvCommonCloseSession(&g_DevExt, pSession);
+            }
+        }
+        else
+            rc = VERR_INVALID_HANDLE;
+    }
+    else
+        rc = VERR_INVALID_POINTER;
+    return rc;
+}
+
+
+void VGDrvNativeISRMousePollEvent(PVBOXGUESTDEVEXT pDevExt)
+{
+    NOREF(pDevExt);
+}
+
+
+bool VGDrvNativeProcessOption(PVBOXGUESTDEVEXT pDevExt, const char *pszName, const char *pszValue)
+{
+    RT_NOREF(pDevExt); RT_NOREF(pszName); RT_NOREF(pszValue);
+    return false;
+}
+
+
+/**
+ * Callback for blah blah blah.
+ *
+ * @todo move to IPRT.
+ */
+static IOReturn vgdrvDarwinSleepHandler(void *pvTarget, void *pvRefCon, UInt32 uMessageType,
+                                        IOService *pProvider, void *pvMsgArg, vm_size_t cbMsgArg)
+{
+    RT_NOREF(pvTarget, pProvider, pvMsgArg, cbMsgArg);
+    LogFlow(("VBoxGuest: Got sleep/wake notice. Message type was %x\n", uMessageType));
+
+    if (uMessageType == kIOMessageSystemWillSleep)
+        RTPowerSignalEvent(RTPOWEREVENT_SUSPEND);
+    else if (uMessageType == kIOMessageSystemHasPoweredOn)
+        RTPowerSignalEvent(RTPOWEREVENT_RESUME);
+
+    acknowledgeSleepWakeNotification(pvRefCon);
+
+    return 0;
+}
+
+
+/**
+ * Converts an IPRT error code to a darwin error code.
+ *
+ * @returns corresponding darwin error code.
+ * @param   rc      IPRT status code.
+ */
+static int vgdrvDarwinErr2DarwinErr(int rc)
+{
+    switch (rc)
+    {
+        case VINF_SUCCESS:              return 0;
+        case VERR_GENERAL_FAILURE:      return EACCES;
+        case VERR_INVALID_PARAMETER:    return EINVAL;
+        case VERR_INVALID_MAGIC:        return EILSEQ;
+        case VERR_INVALID_HANDLE:       return ENXIO;
+        case VERR_INVALID_POINTER:      return EFAULT;
+        case VERR_LOCK_FAILED:          return ENOLCK;
+        case VERR_ALREADY_LOADED:       return EEXIST;
+        case VERR_PERMISSION_DENIED:    return EPERM;
+        case VERR_VERSION_MISMATCH:     return ENOSYS;
+    }
+
+    return EPERM;
+}
+
+
+/*
+ *
+ * org_virtualbox_VBoxGuest
+ *
+ * - IOService diff resync -
+ * - IOService diff resync -
+ * - IOService diff resync -
+ *
+ */
+
+
+/**
+ * Initialize the object.
+ */
+bool org_virtualbox_VBoxGuest::init(OSDictionary *pDictionary)
+{
+    LogFlow(("IOService::init([%p], %p)\n", this, pDictionary));
+    if (IOService::init(pDictionary))
+    {
+        /* init members. */
+        return true;
+    }
+    return false;
+}
+
+
+/**
+ * Free the object.
+ */
+void org_virtualbox_VBoxGuest::free(void)
+{
+    RTLogBackdoorPrintf("IOService::free([%p])\n", this); /* might go sideways if we use LogFlow() here. weird. */
+    IOService::free();
+}
+
+
+/**
+ * Check if it's ok to start this service.
+ * It's always ok by us, so it's up to IOService to decide really.
+ */
+IOService *org_virtualbox_VBoxGuest::probe(IOService *pProvider, SInt32 *pi32Score)
+{
+    LogFlow(("IOService::probe([%p])\n", this));
+    IOService *pRet = IOService::probe(pProvider, pi32Score);
+    LogFlow(("IOService::probe([%p]) returns %p *pi32Score=%d\n", this, pRet, pi32Score ? *pi32Score : -1));
+    return pRet;
+}
+
+
+/**
+ * Start this service.
+ */
+bool org_virtualbox_VBoxGuest::start(IOService *pProvider)
+{
+    LogFlow(("IOService::start([%p])\n", this));
+
+    /*
+     * Low level initialization / device initialization should be performed only once.
+     */
+    if (ASMAtomicCmpXchgBool(&g_fInstantiated, true, false))
+    {
+        /*
+         * Make sure it's a PCI device.
+         */
+        m_pIOPCIDevice = OSDynamicCast(IOPCIDevice, pProvider);
+        if (m_pIOPCIDevice)
+        {
+            /*
+             * Call parent.
+             */
+            if (IOService::start(pProvider))
+            {
+                /*
+                 * Is it the VMM device?
+                 */
+                if (isVmmDev(m_pIOPCIDevice))
+                {
+                    /*
+                     * Enable I/O port and memory regions on the device.
+                     */
+                    m_pIOPCIDevice->setMemoryEnable(true);
+                    m_pIOPCIDevice->setIOEnable(true);
+
+                    /*
+                     * Region #0: I/O ports. Mandatory.
+                     */
+                    IOMemoryDescriptor *pMem = m_pIOPCIDevice->getDeviceMemoryWithIndex(0);
+                    if (pMem)
+                    {
+                        IOPhysicalAddress IOPortBasePhys = pMem->getPhysicalAddress();
+                        if ((IOPortBasePhys >> 16) == 0)
+                        {
+                            RTIOPORT IOPortBase = (RTIOPORT)IOPortBasePhys;
+                            void    *pvMMIOBase = NULL;
+                            uint32_t cbMMIO     = 0;
+
+                            /*
+                             * Region #1: Shared Memory.  Technically optional.
+                             */
+                            m_pMap = m_pIOPCIDevice->mapDeviceMemoryWithIndex(1);
+                            if (m_pMap)
+                            {
+                                pvMMIOBase = (void *)m_pMap->getVirtualAddress();
+                                cbMMIO     = (uint32_t)m_pMap->getLength();
+                            }
+
+                            /*
+                             * Initialize the device extension.
+                             */
+                            int rc = VGDrvCommonInitDevExt(&g_DevExt, IOPortBase, pvMMIOBase, cbMMIO,
+                                                           ARCH_BITS == 64 ? VBOXOSTYPE_MacOS_x64 : VBOXOSTYPE_MacOS, 0);
+                            if (RT_SUCCESS(rc))
+                            {
+                                /*
+                                 * Register the device nodes and enable interrupts.
+                                 */
+                                rc = vgdrvDarwinCharDevInit();
+                                if (rc == KMOD_RETURN_SUCCESS)
+                                {
+                                    if (setupVmmDevInterrupts(pProvider))
+                                    {
+                                        /*
+                                         * Read host configuration.
+                                         */
+                                        VGDrvCommonProcessOptionsFromHost(&g_DevExt);
+
+                                        /*
+                                         * Just register the service and we're done!
+                                         */
+                                        registerService();
+
+                                        LogRel(("VBoxGuest: IOService started\n"));
+                                        return true;
+                                    }
+
+                                    LogRel(("VBoxGuest: Failed to set up interrupts\n"));
+                                    vgdrvDarwinCharDevRemove();
+                                }
+                                else
+                                    LogRel(("VBoxGuest: Failed to initialize character devices (rc=%#x).\n", rc));
+
+                                VGDrvCommonDeleteDevExt(&g_DevExt);
+                            }
+                            else
+                                LogRel(("VBoxGuest: Failed to initialize common code (rc=%Rrc).\n", rc));
+
+                            if (m_pMap)
+                            {
+                                m_pMap->release();
+                                m_pMap = NULL;
+                            }
+                        }
+                        else
+                            LogRel(("VBoxGuest: Bad I/O port address: %#RX64\n", (uint64_t)IOPortBasePhys));
+                    }
+                    else
+                        LogRel(("VBoxGuest: The device missing is the I/O port range (#0).\n"));
+                }
+                else
+                    LogRel(("VBoxGuest: Not the VMMDev (%#x:%#x).\n",
+                           m_pIOPCIDevice->configRead16(kIOPCIConfigVendorID), m_pIOPCIDevice->configRead16(kIOPCIConfigDeviceID)));
+
+                IOService::stop(pProvider);
+            }
+        }
+        else
+            LogRel(("VBoxGuest: Provider is not an instance of IOPCIDevice.\n"));
+
+        ASMAtomicXchgBool(&g_fInstantiated, false);
+    }
+    return false;
+}
+
+
+/**
+ * Stop this service.
+ */
+void org_virtualbox_VBoxGuest::stop(IOService *pProvider)
+{
+#ifdef LOG_ENABLED
+    RTLogBackdoorPrintf("org_virtualbox_VBoxGuest::stop([%p], %p)\n", this, pProvider); /* Being cautious here, no Log(). */
+#endif
+    AssertReturnVoid(ASMAtomicReadBool(&g_fInstantiated));
+
+    /* Low level termination should be performed only once */
+    if (!disableVmmDevInterrupts())
+        printf("VBoxGuest: unable to unregister interrupt handler\n");
+
+    vgdrvDarwinCharDevRemove();
+    VGDrvCommonDeleteDevExt(&g_DevExt);
+
+    if (m_pMap)
+    {
+        m_pMap->release();
+        m_pMap = NULL;
+    }
+
+    IOService::stop(pProvider);
+
+    ASMAtomicWriteBool(&g_fInstantiated, false);
+
+    printf("VBoxGuest: IOService stopped\n");
+    RTLogBackdoorPrintf("org_virtualbox_VBoxGuest::stop: returning\n"); /* Being cautious here, no Log(). */
+}
+
+
+/**
+ * Termination request.
+ *
+ * @return  true if we're ok with shutting down now, false if we're not.
+ * @param   fOptions        Flags.
+ */
+bool org_virtualbox_VBoxGuest::terminate(IOOptionBits fOptions)
+{
+#ifdef LOG_ENABLED
+    RTLogBackdoorPrintf("org_virtualbox_VBoxGuest::terminate: reference_count=%d g_cSessions=%d (fOptions=%#x)\n",
+                        KMOD_INFO_NAME.reference_count, ASMAtomicUoReadS32(&g_cSessions), fOptions); /* Being cautious here, no Log(). */
+#endif
+
+    bool fRc;
+    if (   KMOD_INFO_NAME.reference_count != 0
+        || ASMAtomicUoReadS32(&g_cSessions))
+        fRc = false;
+    else
+        fRc = IOService::terminate(fOptions);
+
+#ifdef LOG_ENABLED
+    RTLogBackdoorPrintf("org_virtualbox_SupDrv::terminate: returns %d\n", fRc); /* Being cautious here, no Log(). */
+#endif
+    return fRc;
+}
+
+
+/**
+ * Implementes a IOInterruptHandler, called by provider when an interrupt occurs.
+ */
+/*static*/ void org_virtualbox_VBoxGuest::vgdrvDarwinIrqHandler(OSObject *pTarget, void *pvRefCon, IOService *pNub, int iSrc)
+{
+#ifdef LOG_ENABLED
+    RTLogBackdoorPrintf("vgdrvDarwinIrqHandler: %p %p %p %d\n", pTarget, pvRefCon, pNub, iSrc);
+#endif
+    RT_NOREF(pTarget, pvRefCon, pNub, iSrc);
+
+    VGDrvCommonISR(&g_DevExt);
+    /* There is in fact no way of indicating that this is our interrupt, other
+       than making the device lower it.  So, the return code is ignored. */
+}
+
+
+/**
+ * Sets up and enables interrupts on the device.
+ *
+ * Interrupts are handled directly, no messing around with workloops.  The
+ * rational here is is that the main job of our interrupt handler is waking up
+ * other threads currently sitting in HGCM calls, i.e. little more effort than
+ * waking up the workloop thread.
+ *
+ * @returns success indicator.  Failures are fully logged.
+ */
+bool org_virtualbox_VBoxGuest::setupVmmDevInterrupts(IOService *pProvider)
+{
+    AssertReturn(pProvider, false);
+
+    if (m_pInterruptProvider != pProvider)
+    {
+        pProvider->retain();
+        if (m_pInterruptProvider)
+            m_pInterruptProvider->release();
+        m_pInterruptProvider = pProvider;
+    }
+
+    IOReturn rc = pProvider->registerInterrupt(0 /*intIndex*/, this, vgdrvDarwinIrqHandler, this);
+    if (rc == kIOReturnSuccess)
+    {
+        rc = pProvider->enableInterrupt(0 /*intIndex*/);
+        if (rc == kIOReturnSuccess)
+            return true;
+
+        LogRel(("VBoxGuest: Failed to enable interrupt: %#x\n", rc));
+        m_pInterruptProvider->unregisterInterrupt(0 /*intIndex*/);
+    }
+    else
+        LogRel(("VBoxGuest: Failed to register interrupt: %#x\n", rc));
+    return false;
+}
+
+
+/**
+ * Counterpart to setupVmmDevInterrupts().
+ */
+bool org_virtualbox_VBoxGuest::disableVmmDevInterrupts(void)
+{
+    if (m_pInterruptProvider)
+    {
+        IOReturn rc = m_pInterruptProvider->disableInterrupt(0 /*intIndex*/);
+        AssertMsg(rc == kIOReturnSuccess, ("%#x\n", rc));
+        rc = m_pInterruptProvider->unregisterInterrupt(0 /*intIndex*/);
+        AssertMsg(rc == kIOReturnSuccess, ("%#x\n", rc));
+        RT_NOREF_PV(rc);
+
+        m_pInterruptProvider->release();
+        m_pInterruptProvider = NULL;
+    }
+
+    return true;
+}
+
+
+/**
+ * Checks if it's the VMM device.
+ *
+ * @returns true if it is, false if it isn't.
+ * @param   pIOPCIDevice    The PCI device we think might be the VMM device.
+ */
+bool org_virtualbox_VBoxGuest::isVmmDev(IOPCIDevice *pIOPCIDevice)
+{
+    if (pIOPCIDevice)
+    {
+        uint16_t idVendor = m_pIOPCIDevice->configRead16(kIOPCIConfigVendorID);
+        if (idVendor == VMMDEV_VENDORID)
+        {
+            uint16_t idDevice = m_pIOPCIDevice->configRead16(kIOPCIConfigDeviceID);
+            if (idDevice == VMMDEV_DEVICEID)
+                return true;
+        }
+    }
+    return false;
+}
+
+
+
+/*
+ *
+ * org_virtualbox_VBoxGuestClient
+ *
+ */
+
+
+/**
+ * Initializer called when the client opens the service.
+ */
+bool org_virtualbox_VBoxGuestClient::initWithTask(task_t OwningTask, void *pvSecurityId, UInt32 u32Type)
+{
+    LogFlow(("org_virtualbox_VBoxGuestClient::initWithTask([%p], %#x, %p, %#x) (cur pid=%d proc=%p)\n",
+             this, OwningTask, pvSecurityId, u32Type, RTProcSelf(), RTR0ProcHandleSelf()));
+    AssertMsg((RTR0PROCESS)OwningTask == RTR0ProcHandleSelf(), ("%p %p\n", OwningTask, RTR0ProcHandleSelf()));
+
+    if (!OwningTask)
+        return false;
+
+    if (u32Type != VBOXGUEST_DARWIN_IOSERVICE_COOKIE)
+    {
+        VBOX_RETRIEVE_CUR_PROC_NAME(szProcName);
+        LogRelMax(10, ("org_virtualbox_VBoxGuestClient::initWithTask: Bad cookie %#x (%s)\n", u32Type, szProcName));
+        return false;
+    }
+
+    if (IOUserClient::initWithTask(OwningTask, pvSecurityId , u32Type))
+    {
+        /*
+         * In theory we have to call task_reference() to make sure that the task is
+         * valid during the lifetime of this object. The pointer is only used to check
+         * for the context this object is called in though and never dereferenced
+         * or passed to anything which might, so we just skip this step.
+         */
+        m_Task = OwningTask;
+        m_pSession = NULL;
+        m_pProvider = NULL;
+        return true;
+    }
+    return false;
+}
+
+
+/**
+ * Start the client service.
+ */
+bool org_virtualbox_VBoxGuestClient::start(IOService *pProvider)
+{
+    LogFlow(("org_virtualbox_VBoxGuestClient::start([%p], %p) (cur pid=%d proc=%p)\n",
+             this, pProvider, RTProcSelf(), RTR0ProcHandleSelf() ));
+    AssertMsgReturn((RTR0PROCESS)m_Task == RTR0ProcHandleSelf(),
+                    ("%p %p\n", m_Task, RTR0ProcHandleSelf()),
+                    false);
+
+    if (IOUserClient::start(pProvider))
+    {
+        m_pProvider = OSDynamicCast(org_virtualbox_VBoxGuest, pProvider);
+        if (m_pProvider)
+        {
+            Assert(!m_pSession);
+
+            /*
+             * Create a new session.
+             * Note! We complete the requestor stuff in the open method.
+             */
+            int rc = VGDrvCommonCreateUserSession(&g_DevExt, VMMDEV_REQUESTOR_USERMODE, &m_pSession);
+            if (RT_SUCCESS(rc))
+            {
+                m_pSession->fOpened = false;
+                /* The Uid, Gid and fUnrestricted fields are set on open. */
+
+                /*
+                 * Insert it into the hash table, checking that there isn't
+                 * already one for this process first. (One session per proc!)
+                 */
+                unsigned iHash = SESSION_HASH(m_pSession->Process);
+                RTSpinlockAcquire(g_Spinlock);
+
+                PVBOXGUESTSESSION pCur = g_apSessionHashTab[iHash];
+                while (pCur && pCur->Process != m_pSession->Process)
+                    pCur = pCur->pNextHash;
+                if (!pCur)
+                {
+                    m_pSession->pNextHash = g_apSessionHashTab[iHash];
+                    g_apSessionHashTab[iHash] = m_pSession;
+                    m_pSession->pvVBoxGuestClient = this;
+                    ASMAtomicIncS32(&g_cSessions);
+                    rc = VINF_SUCCESS;
+                }
+                else
+                    rc = VERR_ALREADY_LOADED;
+
+                RTSpinlockRelease(g_Spinlock);
+                if (RT_SUCCESS(rc))
+                {
+                    Log(("org_virtualbox_VBoxGuestClient::start: created session %p for pid %d\n", m_pSession, (int)RTProcSelf()));
+                    return true;
+                }
+
+                LogFlow(("org_virtualbox_VBoxGuestClient::start: already got a session for this process (%p)\n", pCur));
+                VGDrvCommonCloseSession(&g_DevExt, m_pSession);  //supdrvSessionRelease(m_pSession);
+            }
+
+            m_pSession = NULL;
+            LogFlow(("org_virtualbox_VBoxGuestClient::start: rc=%Rrc from supdrvCreateSession\n", rc));
+        }
+        else
+            LogFlow(("org_virtualbox_VBoxGuestClient::start: %p isn't org_virtualbox_VBoxGuest\n", pProvider));
+    }
+    return false;
+}
+
+
+/**
+ * Common worker for clientClose and VBoxDrvDarwinClose.
+ */
+/* static */ void org_virtualbox_VBoxGuestClient::sessionClose(RTPROCESS Process)
+{
+    /*
+     * Find the session and remove it from the hash table.
+     *
+     * Note! Only one session per process. (Both start() and
+     * vgdrvDarwinOpen makes sure this is so.)
+     */
+    const unsigned  iHash = SESSION_HASH(Process);
+    RTSpinlockAcquire(g_Spinlock);
+    PVBOXGUESTSESSION  pSession = g_apSessionHashTab[iHash];
+    if (pSession)
+    {
+        if (pSession->Process == Process)
+        {
+            g_apSessionHashTab[iHash] = pSession->pNextHash;
+            pSession->pNextHash = NULL;
+            ASMAtomicDecS32(&g_cSessions);
+        }
+        else
+        {
+            PVBOXGUESTSESSION pPrev = pSession;
+            pSession = pSession->pNextHash;
+            while (pSession)
+            {
+                if (pSession->Process == Process)
+                {
+                    pPrev->pNextHash = pSession->pNextHash;
+                    pSession->pNextHash = NULL;
+                    ASMAtomicDecS32(&g_cSessions);
+                    break;
+                }
+
+                /* next */
+                pPrev = pSession;
+                pSession = pSession->pNextHash;
+            }
+        }
+    }
+    RTSpinlockRelease(g_Spinlock);
+    if (!pSession)
+    {
+        Log(("VBoxGuestClient::sessionClose: pSession == NULL, pid=%d; freed already?\n", (int)Process));
+        return;
+    }
+
+    /*
+     * Remove it from the client object.
+     */
+    org_virtualbox_VBoxGuestClient *pThis = (org_virtualbox_VBoxGuestClient *)pSession->pvVBoxGuestClient;
+    pSession->pvVBoxGuestClient = NULL;
+    if (pThis)
+    {
+        Assert(pThis->m_pSession == pSession);
+        pThis->m_pSession = NULL;
+    }
+
+    /*
+     * Close the session.
+     */
+    VGDrvCommonCloseSession(&g_DevExt, pSession); // supdrvSessionRelease(m_pSession);
+}
+
+
+/**
+ * Client exits normally.
+ */
+IOReturn org_virtualbox_VBoxGuestClient::clientClose(void)
+{
+    LogFlow(("org_virtualbox_VBoxGuestClient::clientClose([%p]) (cur pid=%d proc=%p)\n", this, RTProcSelf(), RTR0ProcHandleSelf()));
+    AssertMsg((RTR0PROCESS)m_Task == RTR0ProcHandleSelf(), ("%p %p\n", m_Task, RTR0ProcHandleSelf()));
+
+    /*
+     * Clean up the session if it's still around.
+     *
+     * We cannot rely 100% on close, and in the case of a dead client
+     * we'll end up hanging inside vm_map_remove() if we postpone it.
+     */
+    if (m_pSession)
+    {
+        sessionClose(RTProcSelf());
+        Assert(!m_pSession);
+    }
+
+    m_pProvider = NULL;
+    terminate();
+
+    return kIOReturnSuccess;
+}
+
+
+/**
+ * The client exits abnormally / forgets to do cleanups. (logging)
+ */
+IOReturn org_virtualbox_VBoxGuestClient::clientDied(void)
+{
+    LogFlow(("IOService::clientDied([%p]) m_Task=%p R0Process=%p Process=%d\n", this, m_Task, RTR0ProcHandleSelf(), RTProcSelf()));
+
+    /* IOUserClient::clientDied() calls clientClose, so we'll just do the work there. */
+    return IOUserClient::clientDied();
+}
+
+
+/**
+ * Terminate the service (initiate the destruction). (logging)
+ */
+bool org_virtualbox_VBoxGuestClient::terminate(IOOptionBits fOptions)
+{
+    LogFlow(("IOService::terminate([%p], %#x)\n", this, fOptions));
+    return IOUserClient::terminate(fOptions);
+}
+
+
+/**
+ * The final stage of the client service destruction. (logging)
+ */
+bool org_virtualbox_VBoxGuestClient::finalize(IOOptionBits fOptions)
+{
+    LogFlow(("IOService::finalize([%p], %#x)\n", this, fOptions));
+    return IOUserClient::finalize(fOptions);
+}
+
+
+/**
+ * Stop the client service. (logging)
+ */
+void org_virtualbox_VBoxGuestClient::stop(IOService *pProvider)
+{
+    LogFlow(("IOService::stop([%p])\n", this));
+    IOUserClient::stop(pProvider);
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/VBoxGuest-freebsd.c b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-freebsd.c
new file mode 100644
index 00000000..99228388
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-freebsd.c
@@ -0,0 +1,799 @@
+/* $Id: VBoxGuest-freebsd.c $ */
+/** @file
+ * VirtualBox Guest Additions Driver for FreeBSD.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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
+ */
+
+/** @todo r=bird: This must merge with SUPDrv-freebsd.c before long. The two
+ * source files should only differ on prefixes and the extra bits wrt to the
+ * pci device. I.e. it should be diffable so that fixes to one can easily be
+ * applied to the other. */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <sys/param.h>
+#undef PVM
+#include <sys/types.h>
+#include <sys/module.h>
+#include <sys/systm.h>
+#include <sys/errno.h>
+#include <sys/kernel.h>
+#include <sys/fcntl.h>
+#include <sys/conf.h>
+#include <sys/uio.h>
+#include <sys/bus.h>
+#include <sys/poll.h>
+#include <sys/selinfo.h>
+#include <sys/queue.h>
+#include <sys/lock.h>
+#include <sys/lockmgr.h>
+#include <sys/malloc.h>
+#include <sys/file.h>
+#include <sys/rman.h>
+#include <machine/bus.h>
+#include <machine/resource.h>
+#include <dev/pci/pcivar.h>
+#include <dev/pci/pcireg.h>
+
+#include "VBoxGuestInternal.h"
+#include <VBox/version.h>
+#include <VBox/log.h>
+#include <iprt/assert.h>
+#include <iprt/initterm.h>
+#include <iprt/process.h>
+#include <iprt/string.h>
+#include <iprt/mem.h>
+#include <iprt/asm.h>
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+/** The module name. */
+#define DEVICE_NAME  "vboxguest"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+struct VBoxGuestDeviceState
+{
+    /** Resource ID of the I/O port */
+    int                iIOPortResId;
+    /** Pointer to the I/O port resource. */
+    struct resource   *pIOPortRes;
+    /** Start address of the IO Port. */
+    uint16_t           uIOPortBase;
+    /** Resource ID of the MMIO area */
+    int                iVMMDevMemResId;
+    /** Pointer to the MMIO resource. */
+    struct resource   *pVMMDevMemRes;
+    /** Handle of the MMIO resource. */
+    bus_space_handle_t VMMDevMemHandle;
+    /** Size of the memory area. */
+    bus_size_t         VMMDevMemSize;
+    /** Mapping of the register space */
+    void              *pMMIOBase;
+    /** IRQ number */
+    int                iIrqResId;
+    /** IRQ resource handle. */
+    struct resource   *pIrqRes;
+    /** Pointer to the IRQ handler. */
+    void              *pfnIrqHandler;
+    /** VMMDev version */
+    uint32_t           u32Version;
+};
+
+
+/*********************************************************************************************************************************
+*   Internal Functions                                                                                                           *
+*********************************************************************************************************************************/
+/*
+ * Character device file handlers.
+ */
+static d_fdopen_t vgdrvFreeBSDOpen;
+static d_close_t  vgdrvFreeBSDClose;
+static d_ioctl_t  vgdrvFreeBSDIOCtl;
+static int        vgdrvFreeBSDIOCtlSlow(PVBOXGUESTSESSION pSession, u_long ulCmd, caddr_t pvData, struct thread *pTd);
+static d_write_t  vgdrvFreeBSDWrite;
+static d_read_t   vgdrvFreeBSDRead;
+static d_poll_t   vgdrvFreeBSDPoll;
+
+/*
+ * IRQ related functions.
+ */
+static void vgdrvFreeBSDRemoveIRQ(device_t pDevice, void *pvState);
+static int  vgdrvFreeBSDAddIRQ(device_t pDevice, void *pvState);
+static int  vgdrvFreeBSDISR(void *pvState);
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+static MALLOC_DEFINE(M_VBOXGUEST, "vboxguest", "VirtualBox Guest Device Driver");
+
+#ifndef D_NEEDMINOR
+# define D_NEEDMINOR 0
+#endif
+
+/*
+ * The /dev/vboxguest character device entry points.
+ */
+static struct cdevsw    g_vgdrvFreeBSDChrDevSW =
+{
+    .d_version =        D_VERSION,
+    .d_flags =          D_TRACKCLOSE | D_NEEDMINOR,
+    .d_fdopen =         vgdrvFreeBSDOpen,
+    .d_close =          vgdrvFreeBSDClose,
+    .d_ioctl =          vgdrvFreeBSDIOCtl,
+    .d_read =           vgdrvFreeBSDRead,
+    .d_write =          vgdrvFreeBSDWrite,
+    .d_poll =           vgdrvFreeBSDPoll,
+    .d_name =           "vboxguest"
+};
+
+/** Device extention & session data association structure. */
+static VBOXGUESTDEVEXT      g_DevExt;
+
+/** List of cloned device. Managed by the kernel. */
+static struct clonedevs    *g_pvgdrvFreeBSDClones;
+/** The dev_clone event handler tag. */
+static eventhandler_tag     g_vgdrvFreeBSDEHTag;
+/** Reference counter */
+static volatile uint32_t    cUsers;
+/** selinfo structure used for polling. */
+static struct selinfo       g_SelInfo;
+
+/**
+ * DEVFS event handler.
+ */
+static void vgdrvFreeBSDClone(void *pvArg, struct ucred *pCred, char *pszName, int cchName, struct cdev **ppDev)
+{
+    int iUnit;
+    int rc;
+
+    Log(("vgdrvFreeBSDClone: pszName=%s ppDev=%p\n", pszName, ppDev));
+
+    /*
+     * One device node per user, si_drv1 points to the session.
+     * /dev/vboxguest<N> where N = {0...255}.
+     */
+    if (!ppDev)
+        return;
+    if (strcmp(pszName, "vboxguest") == 0)
+        iUnit =  -1;
+    else if (dev_stdclone(pszName, NULL, "vboxguest", &iUnit) != 1)
+        return;
+    if (iUnit >= 256)
+    {
+        Log(("vgdrvFreeBSDClone: iUnit=%d >= 256 - rejected\n", iUnit));
+        return;
+    }
+
+    Log(("vgdrvFreeBSDClone: pszName=%s iUnit=%d\n", pszName, iUnit));
+
+    rc = clone_create(&g_pvgdrvFreeBSDClones, &g_vgdrvFreeBSDChrDevSW, &iUnit, ppDev, 0);
+    Log(("vgdrvFreeBSDClone: clone_create -> %d; iUnit=%d\n", rc, iUnit));
+    if (rc)
+    {
+        *ppDev = make_dev(&g_vgdrvFreeBSDChrDevSW,
+                          iUnit,
+                          UID_ROOT,
+                          GID_WHEEL,
+                          0664,
+                          "vboxguest%d", iUnit);
+        if (*ppDev)
+        {
+            dev_ref(*ppDev);
+            (*ppDev)->si_flags |= SI_CHEAPCLONE;
+            Log(("vgdrvFreeBSDClone: Created *ppDev=%p iUnit=%d si_drv1=%p si_drv2=%p\n",
+                     *ppDev, iUnit, (*ppDev)->si_drv1, (*ppDev)->si_drv2));
+            (*ppDev)->si_drv1 = (*ppDev)->si_drv2 = NULL;
+        }
+        else
+            Log(("vgdrvFreeBSDClone: make_dev iUnit=%d failed\n", iUnit));
+    }
+    else
+        Log(("vgdrvFreeBSDClone: Existing *ppDev=%p iUnit=%d si_drv1=%p si_drv2=%p\n",
+             *ppDev, iUnit, (*ppDev)->si_drv1, (*ppDev)->si_drv2));
+}
+
+/**
+ * File open handler
+ *
+ */
+#if __FreeBSD_version >= 700000
+static int vgdrvFreeBSDOpen(struct cdev *pDev, int fOpen, struct thread *pTd, struct file *pFd)
+#else
+static int vgdrvFreeBSDOpen(struct cdev *pDev, int fOpen, struct thread *pTd)
+#endif
+{
+    int                 rc;
+    PVBOXGUESTSESSION   pSession;
+    uint32_t            fRequestor;
+    struct ucred       *pCred = curthread->td_ucred;
+    if (!pCred)
+        pCred = curproc->p_ucred;
+
+    LogFlow(("vgdrvFreeBSDOpen:\n"));
+
+    /*
+     * Try grab it (we don't grab the giant, remember).
+     */
+    if (!ASMAtomicCmpXchgPtr(&pDev->si_drv1, (void *)0x42, NULL))
+        return EBUSY;
+
+    /*
+     * Create a new session.
+     */
+    fRequestor = VMMDEV_REQUESTOR_USERMODE | VMMDEV_REQUESTOR_TRUST_NOT_GIVEN;
+    if (pCred && pCred->cr_uid == 0)
+        fRequestor |= VMMDEV_REQUESTOR_USR_ROOT;
+    else
+        fRequestor |= VMMDEV_REQUESTOR_USR_USER;
+    if (pCred && groupmember(0, pCred))
+        fRequestor |= VMMDEV_REQUESTOR_GRP_WHEEL;
+    fRequestor |= VMMDEV_REQUESTOR_NO_USER_DEVICE; /** @todo implement /dev/vboxuser
+    if (!fUnrestricted)
+        fRequestor |= VMMDEV_REQUESTOR_USER_DEVICE; */
+    fRequestor |= VMMDEV_REQUESTOR_CON_DONT_KNOW; /** @todo see if we can figure out console relationship of pProc. */
+    rc = VGDrvCommonCreateUserSession(&g_DevExt, fRequestor, &pSession);
+    if (RT_SUCCESS(rc))
+    {
+        if (ASMAtomicCmpXchgPtr(&pDev->si_drv1, pSession, (void *)0x42))
+        {
+            Log(("vgdrvFreeBSDOpen: success - g_DevExt=%p pSession=%p rc=%d pid=%d\n", &g_DevExt, pSession, rc, (int)RTProcSelf()));
+            ASMAtomicIncU32(&cUsers);
+            return 0;
+        }
+
+        VGDrvCommonCloseSession(&g_DevExt, pSession);
+    }
+
+    LogRel(("vgdrvFreeBSDOpen: failed. rc=%d\n", rc));
+    return RTErrConvertToErrno(rc);
+}
+
+/**
+ * File close handler
+ *
+ */
+static int vgdrvFreeBSDClose(struct cdev *pDev, int fFile, int DevType, struct thread *pTd)
+{
+    PVBOXGUESTSESSION pSession = (PVBOXGUESTSESSION)pDev->si_drv1;
+    Log(("vgdrvFreeBSDClose: fFile=%#x pSession=%p\n", fFile, pSession));
+
+    /*
+     * Close the session if it's still hanging on to the device...
+     */
+    if (RT_VALID_PTR(pSession))
+    {
+        VGDrvCommonCloseSession(&g_DevExt, pSession);
+        if (!ASMAtomicCmpXchgPtr(&pDev->si_drv1, NULL, pSession))
+            Log(("vgdrvFreeBSDClose: si_drv1=%p expected %p!\n", pDev->si_drv1, pSession));
+        ASMAtomicDecU32(&cUsers);
+        /* Don't use destroy_dev here because it may sleep resulting in a hanging user process. */
+        destroy_dev_sched(pDev);
+    }
+    else
+        Log(("vgdrvFreeBSDClose: si_drv1=%p!\n", pSession));
+    return 0;
+}
+
+
+/**
+ * I/O control request.
+ *
+ * @returns depends...
+ * @param   pDev        The device.
+ * @param   ulCmd       The command.
+ * @param   pvData      Pointer to the data.
+ * @param   fFile       The file descriptor flags.
+ * @param   pTd         The calling thread.
+ */
+static int vgdrvFreeBSDIOCtl(struct cdev *pDev, u_long ulCmd, caddr_t pvData, int fFile, struct thread *pTd)
+{
+    PVBOXGUESTSESSION pSession;
+    devfs_get_cdevpriv((void **)&pSession);
+
+    /*
+     * Deal with the fast ioctl path first.
+     */
+    if (VBGL_IOCTL_IS_FAST(ulCmd))
+        return VGDrvCommonIoCtlFast(ulCmd, &g_DevExt, pSession);
+
+    return vgdrvFreeBSDIOCtlSlow(pSession, ulCmd, pvData, pTd);
+}
+
+
+/**
+ * Deal with the 'slow' I/O control requests.
+ *
+ * @returns 0 on success, appropriate errno on failure.
+ * @param   pSession    The session.
+ * @param   ulCmd       The command.
+ * @param   pvData      The request data.
+ * @param   pTd         The calling thread.
+ */
+static int vgdrvFreeBSDIOCtlSlow(PVBOXGUESTSESSION pSession, u_long ulCmd, caddr_t pvData, struct thread *pTd)
+{
+    PVBGLREQHDR pHdr;
+    uint32_t    cbReq = IOCPARM_LEN(ulCmd);
+    void       *pvUser = NULL;
+
+    /*
+     * Buffered request?
+     */
+    if ((IOC_DIRMASK & ulCmd) == IOC_INOUT)
+    {
+        pHdr = (PVBGLREQHDR)pvData;
+        if (RT_UNLIKELY(cbReq < sizeof(*pHdr)))
+        {
+            LogRel(("vgdrvFreeBSDIOCtlSlow: cbReq=%#x < %#x; ulCmd=%#lx\n", cbReq, (int)sizeof(*pHdr), ulCmd));
+            return EINVAL;
+        }
+        if (RT_UNLIKELY(pHdr->uVersion != VBGLREQHDR_VERSION))
+        {
+            LogRel(("vgdrvFreeBSDIOCtlSlow: bad uVersion=%#x; ulCmd=%#lx\n", pHdr->uVersion, ulCmd));
+            return EINVAL;
+        }
+        if (RT_UNLIKELY(   RT_MAX(pHdr->cbIn, pHdr->cbOut) != cbReq
+                        || pHdr->cbIn < sizeof(*pHdr)
+                        || (pHdr->cbOut < sizeof(*pHdr) && pHdr->cbOut != 0)))
+        {
+            LogRel(("vgdrvFreeBSDIOCtlSlow: max(%#x,%#x) != %#x; ulCmd=%#lx\n", pHdr->cbIn, pHdr->cbOut, cbReq, ulCmd));
+            return EINVAL;
+        }
+    }
+    /*
+     * Big unbuffered request?
+     */
+    else if ((IOC_DIRMASK & ulCmd) == IOC_VOID && !cbReq)
+    {
+        /*
+         * Read the header, validate it and figure out how much that needs to be buffered.
+         */
+        VBGLREQHDR Hdr;
+        pvUser = *(void **)pvData;
+        int rc = copyin(pvUser, &Hdr, sizeof(Hdr));
+        if (RT_UNLIKELY(rc))
+        {
+            LogRel(("vgdrvFreeBSDIOCtlSlow: copyin(%p,Hdr,) -> %#x; ulCmd=%#lx\n", pvUser, rc, ulCmd));
+            return rc;
+        }
+        if (RT_UNLIKELY(Hdr.uVersion != VBGLREQHDR_VERSION))
+        {
+            LogRel(("vgdrvFreeBSDIOCtlSlow: bad uVersion=%#x; ulCmd=%#lx\n", Hdr.uVersion, ulCmd));
+            return EINVAL;
+        }
+        cbReq = RT_MAX(Hdr.cbIn, Hdr.cbOut);
+        if (RT_UNLIKELY(   Hdr.cbIn < sizeof(Hdr)
+                        || (Hdr.cbOut < sizeof(Hdr) && Hdr.cbOut != 0)
+                        || cbReq > _1M*16))
+        {
+            LogRel(("vgdrvFreeBSDIOCtlSlow: max(%#x,%#x); ulCmd=%#lx\n", Hdr.cbIn, Hdr.cbOut, ulCmd));
+            return EINVAL;
+        }
+
+        /*
+         * Allocate buffer and copy in the data.
+         */
+        pHdr = (PVBGLREQHDR)RTMemTmpAlloc(cbReq);
+        if (RT_UNLIKELY(!pHdr))
+        {
+            LogRel(("vgdrvFreeBSDIOCtlSlow: failed to allocate buffer of %d bytes; ulCmd=%#lx\n", cbReq, ulCmd));
+            return ENOMEM;
+        }
+        rc = copyin(pvUser, pHdr, Hdr.cbIn);
+        if (RT_UNLIKELY(rc))
+        {
+            LogRel(("vgdrvFreeBSDIOCtlSlow: copyin(%p,%p,%#x) -> %#x; ulCmd=%#lx\n",
+                        pvUser, pHdr, Hdr.cbIn, rc, ulCmd));
+            RTMemTmpFree(pHdr);
+            return rc;
+        }
+        if (Hdr.cbIn < cbReq)
+            RT_BZERO((uint8_t *)pHdr + Hdr.cbIn, cbReq - Hdr.cbIn);
+    }
+    else
+    {
+        Log(("vgdrvFreeBSDIOCtlSlow: huh? cbReq=%#x ulCmd=%#lx\n", cbReq, ulCmd));
+        return EINVAL;
+    }
+
+    /*
+     * Process the IOCtl.
+     */
+    int rc = VGDrvCommonIoCtl(ulCmd, &g_DevExt, pSession, pHdr, cbReq);
+    if (RT_LIKELY(!rc))
+    {
+        /*
+         * If unbuffered, copy back the result before returning.
+         */
+        if (pvUser)
+        {
+            uint32_t cbOut = pHdr->cbOut;
+            if (cbOut > cbReq)
+            {
+                LogRel(("vgdrvFreeBSDIOCtlSlow: too much output! %#x > %#x; uCmd=%#lx!\n", cbOut, cbReq, ulCmd));
+                cbOut = cbReq;
+            }
+            rc = copyout(pHdr, pvUser, cbOut);
+            if (RT_UNLIKELY(rc))
+                LogRel(("vgdrvFreeBSDIOCtlSlow: copyout(%p,%p,%#x) -> %d; uCmd=%#lx!\n", pHdr, pvUser, cbOut, rc, ulCmd));
+
+            Log(("vgdrvFreeBSDIOCtlSlow: returns %d / %d ulCmd=%lx\n", 0, pHdr->rc, ulCmd));
+
+            /* cleanup */
+            RTMemTmpFree(pHdr);
+        }
+    }
+    else
+    {
+        /*
+         * The request failed, just clean up.
+         */
+        if (pvUser)
+            RTMemTmpFree(pHdr);
+
+        Log(("vgdrvFreeBSDIOCtlSlow: ulCmd=%lx pData=%p failed, rc=%d\n", ulCmd, pvData, rc));
+        rc = EINVAL;
+    }
+
+    return rc;
+}
+
+
+/**
+ * @note This code is duplicated on other platforms with variations, so please
+ *       keep them all up to date when making changes!
+ */
+int VBOXCALL VBoxGuestIDC(void *pvSession, uintptr_t uReq, PVBGLREQHDR pReqHdr, size_t cbReq)
+{
+    /*
+     * Simple request validation (common code does the rest).
+     */
+    int rc;
+    if (   RT_VALID_PTR(pReqHdr)
+        && cbReq >= sizeof(*pReqHdr))
+    {
+        /*
+         * All requests except the connect one requires a valid session.
+         */
+        PVBOXGUESTSESSION pSession = (PVBOXGUESTSESSION)pvSession;
+        if (pSession)
+        {
+            if (   RT_VALID_PTR(pSession)
+                && pSession->pDevExt == &g_DevExt)
+                rc = VGDrvCommonIoCtl(uReq, &g_DevExt, pSession, pReqHdr, cbReq);
+            else
+                rc = VERR_INVALID_HANDLE;
+        }
+        else if (uReq == VBGL_IOCTL_IDC_CONNECT)
+        {
+            rc = VGDrvCommonCreateKernelSession(&g_DevExt, &pSession);
+            if (RT_SUCCESS(rc))
+            {
+                rc = VGDrvCommonIoCtl(uReq, &g_DevExt, pSession, pReqHdr, cbReq);
+                if (RT_FAILURE(rc))
+                    VGDrvCommonCloseSession(&g_DevExt, pSession);
+            }
+        }
+        else
+            rc = VERR_INVALID_HANDLE;
+    }
+    else
+        rc = VERR_INVALID_POINTER;
+    return rc;
+}
+
+
+static int vgdrvFreeBSDPoll(struct cdev *pDev, int fEvents, struct thread *td)
+{
+    int fEventsProcessed;
+
+    LogFlow(("vgdrvFreeBSDPoll: fEvents=%d\n", fEvents));
+
+    PVBOXGUESTSESSION pSession = (PVBOXGUESTSESSION)pDev->si_drv1;
+    if (RT_UNLIKELY(!RT_VALID_PTR(pSession))) {
+        Log(("vgdrvFreeBSDPoll: no state data for %s\n", devtoname(pDev)));
+        return (fEvents & (POLLHUP|POLLIN|POLLRDNORM|POLLOUT|POLLWRNORM));
+    }
+
+    uint32_t u32CurSeq = ASMAtomicUoReadU32(&g_DevExt.u32MousePosChangedSeq);
+    if (pSession->u32MousePosChangedSeq != u32CurSeq)
+    {
+        fEventsProcessed = fEvents & (POLLIN | POLLRDNORM);
+        pSession->u32MousePosChangedSeq = u32CurSeq;
+    }
+    else
+    {
+        fEventsProcessed = 0;
+
+        selrecord(td, &g_SelInfo);
+    }
+
+    return fEventsProcessed;
+}
+
+static int vgdrvFreeBSDWrite(struct cdev *pDev, struct uio *pUio, int fIo)
+{
+    return 0;
+}
+
+static int vgdrvFreeBSDRead(struct cdev *pDev, struct uio *pUio, int fIo)
+{
+    return 0;
+}
+
+static int vgdrvFreeBSDDetach(device_t pDevice)
+{
+    struct VBoxGuestDeviceState *pState = device_get_softc(pDevice);
+
+    if (cUsers > 0)
+        return EBUSY;
+
+    /*
+     * Reverse what we did in vgdrvFreeBSDAttach.
+     */
+    if (g_vgdrvFreeBSDEHTag != NULL)
+        EVENTHANDLER_DEREGISTER(dev_clone, g_vgdrvFreeBSDEHTag);
+
+    clone_cleanup(&g_pvgdrvFreeBSDClones);
+
+    vgdrvFreeBSDRemoveIRQ(pDevice, pState);
+
+    if (pState->pVMMDevMemRes)
+        bus_release_resource(pDevice, SYS_RES_MEMORY, pState->iVMMDevMemResId, pState->pVMMDevMemRes);
+    if (pState->pIOPortRes)
+        bus_release_resource(pDevice, SYS_RES_IOPORT, pState->iIOPortResId, pState->pIOPortRes);
+
+    VGDrvCommonDeleteDevExt(&g_DevExt);
+
+    RTR0Term();
+
+    return 0;
+}
+
+
+/**
+ * Interrupt service routine.
+ *
+ * @returns Whether the interrupt was from VMMDev.
+ * @param   pvState Opaque pointer to the device state.
+ */
+static int vgdrvFreeBSDISR(void *pvState)
+{
+    LogFlow(("vgdrvFreeBSDISR: pvState=%p\n", pvState));
+
+    bool fOurIRQ = VGDrvCommonISR(&g_DevExt);
+
+    return fOurIRQ ? 0 : 1;
+}
+
+void VGDrvNativeISRMousePollEvent(PVBOXGUESTDEVEXT pDevExt)
+{
+    LogFlow(("VGDrvNativeISRMousePollEvent:\n"));
+
+    /*
+     * Wake up poll waiters.
+     */
+    selwakeup(&g_SelInfo);
+}
+
+
+bool VGDrvNativeProcessOption(PVBOXGUESTDEVEXT pDevExt, const char *pszName, const char *pszValue)
+{
+    RT_NOREF(pDevExt); RT_NOREF(pszName); RT_NOREF(pszValue);
+    return false;
+}
+
+
+/**
+ * Sets IRQ for VMMDev.
+ *
+ * @returns FreeBSD error code.
+ * @param   pDevice  Pointer to the device info structure.
+ * @param   pvState  Pointer to the state info structure.
+ */
+static int vgdrvFreeBSDAddIRQ(device_t pDevice, void *pvState)
+{
+    int iResId = 0;
+    int rc = 0;
+    struct VBoxGuestDeviceState *pState = (struct VBoxGuestDeviceState *)pvState;
+
+    pState->pIrqRes = bus_alloc_resource_any(pDevice, SYS_RES_IRQ, &iResId, RF_SHAREABLE | RF_ACTIVE);
+
+#if __FreeBSD_version >= 700000
+    rc = bus_setup_intr(pDevice, pState->pIrqRes, INTR_TYPE_BIO | INTR_MPSAFE, NULL, (driver_intr_t *)vgdrvFreeBSDISR, pState,
+                        &pState->pfnIrqHandler);
+#else
+    rc = bus_setup_intr(pDevice, pState->pIrqRes, INTR_TYPE_BIO, (driver_intr_t *)vgdrvFreeBSDISR, pState, &pState->pfnIrqHandler);
+#endif
+
+    if (rc)
+    {
+        pState->pfnIrqHandler = NULL;
+        return VERR_DEV_IO_ERROR;
+    }
+
+    pState->iIrqResId = iResId;
+
+    return VINF_SUCCESS;
+}
+
+/**
+ * Removes IRQ for VMMDev.
+ *
+ * @param   pDevice  Pointer to the device info structure.
+ * @param   pvState  Opaque pointer to the state info structure.
+ */
+static void vgdrvFreeBSDRemoveIRQ(device_t pDevice, void *pvState)
+{
+    struct VBoxGuestDeviceState *pState = (struct VBoxGuestDeviceState *)pvState;
+
+    if (pState->pIrqRes)
+    {
+        bus_teardown_intr(pDevice, pState->pIrqRes, pState->pfnIrqHandler);
+        bus_release_resource(pDevice, SYS_RES_IRQ, 0, pState->pIrqRes);
+    }
+}
+
+static int vgdrvFreeBSDAttach(device_t pDevice)
+{
+    int rc;
+    int iResId;
+    struct VBoxGuestDeviceState *pState;
+
+    cUsers = 0;
+
+    /*
+     * Initialize IPRT R0 driver, which internally calls OS-specific r0 init.
+     */
+    rc = RTR0Init(0);
+    if (RT_FAILURE(rc))
+    {
+        LogFunc(("RTR0Init failed.\n"));
+        return ENXIO;
+    }
+
+    pState = device_get_softc(pDevice);
+
+    /*
+     * Allocate I/O port resource.
+     */
+    iResId                 = PCIR_BAR(0);
+    pState->pIOPortRes     = bus_alloc_resource_any(pDevice, SYS_RES_IOPORT, &iResId, RF_ACTIVE);
+    pState->uIOPortBase    = rman_get_start(pState->pIOPortRes);
+    pState->iIOPortResId   = iResId;
+    if (pState->uIOPortBase)
+    {
+        /*
+         * Map the MMIO region.
+         */
+        iResId                   = PCIR_BAR(1);
+        pState->pVMMDevMemRes    = bus_alloc_resource_any(pDevice, SYS_RES_MEMORY, &iResId, RF_ACTIVE);
+        pState->VMMDevMemHandle  = rman_get_bushandle(pState->pVMMDevMemRes);
+        pState->VMMDevMemSize    = rman_get_size(pState->pVMMDevMemRes);
+
+        pState->pMMIOBase        = rman_get_virtual(pState->pVMMDevMemRes);
+        pState->iVMMDevMemResId  = iResId;
+        if (pState->pMMIOBase)
+        {
+            /*
+             * Call the common device extension initializer.
+             */
+            rc = VGDrvCommonInitDevExt(&g_DevExt, pState->uIOPortBase,
+                                       pState->pMMIOBase, pState->VMMDevMemSize,
+#if ARCH_BITS == 64
+                                       VBOXOSTYPE_FreeBSD_x64,
+#else
+                                       VBOXOSTYPE_FreeBSD,
+#endif
+                                       VMMDEV_EVENT_MOUSE_POSITION_CHANGED);
+            if (RT_SUCCESS(rc))
+            {
+                /*
+                 * Add IRQ of VMMDev.
+                 */
+                rc = vgdrvFreeBSDAddIRQ(pDevice, pState);
+                if (RT_SUCCESS(rc))
+                {
+                    /*
+                     * Read host configuration.
+                     */
+                    VGDrvCommonProcessOptionsFromHost(&g_DevExt);
+
+                    /*
+                     * Configure device cloning.
+                     */
+                    clone_setup(&g_pvgdrvFreeBSDClones);
+                    g_vgdrvFreeBSDEHTag = EVENTHANDLER_REGISTER(dev_clone, vgdrvFreeBSDClone, 0, 1000);
+                    if (g_vgdrvFreeBSDEHTag)
+                    {
+                        printf(DEVICE_NAME ": loaded successfully\n");
+                        return 0;
+                    }
+
+                    printf(DEVICE_NAME ": EVENTHANDLER_REGISTER(dev_clone,,,) failed\n");
+                    clone_cleanup(&g_pvgdrvFreeBSDClones);
+                    vgdrvFreeBSDRemoveIRQ(pDevice, pState);
+                }
+                else
+                    printf((DEVICE_NAME ": VGDrvCommonInitDevExt failed.\n"));
+                VGDrvCommonDeleteDevExt(&g_DevExt);
+            }
+            else
+                printf((DEVICE_NAME ": vgdrvFreeBSDAddIRQ failed.\n"));
+        }
+        else
+            printf((DEVICE_NAME ": MMIO region setup failed.\n"));
+    }
+    else
+        printf((DEVICE_NAME ": IOport setup failed.\n"));
+
+    RTR0Term();
+    return ENXIO;
+}
+
+static int vgdrvFreeBSDProbe(device_t pDevice)
+{
+    if ((pci_get_vendor(pDevice) == VMMDEV_VENDORID) && (pci_get_device(pDevice) == VMMDEV_DEVICEID))
+        return 0;
+
+    return ENXIO;
+}
+
+static device_method_t vgdrvFreeBSDMethods[] =
+{
+    /* Device interface. */
+    DEVMETHOD(device_probe,  vgdrvFreeBSDProbe),
+    DEVMETHOD(device_attach, vgdrvFreeBSDAttach),
+    DEVMETHOD(device_detach, vgdrvFreeBSDDetach),
+    {0,0}
+};
+
+static driver_t vgdrvFreeBSDDriver =
+{
+    DEVICE_NAME,
+    vgdrvFreeBSDMethods,
+    sizeof(struct VBoxGuestDeviceState),
+};
+
+static devclass_t vgdrvFreeBSDClass;
+
+DRIVER_MODULE(vboxguest, pci, vgdrvFreeBSDDriver, vgdrvFreeBSDClass, 0, 0);
+MODULE_VERSION(vboxguest, 1);
+
diff --git a/src/VBox/Additions/common/VBoxGuest/VBoxGuest-haiku-stubs.c b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-haiku-stubs.c
new file mode 100644
index 00000000..8981a5e9
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-haiku-stubs.c
@@ -0,0 +1,471 @@
+/* $Id: VBoxGuest-haiku-stubs.c $ */
+/** @file
+ * VBoxGuest kernel module, Haiku Guest Additions, stubs.
+ */
+
+/*
+ * 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
+ */
+
+/*
+ * This code is based on:
+ *
+ * VirtualBox Guest Additions for Haiku.
+ * Copyright (c) 2011 Mike Smith <mike@scgtrp.net>
+ *                    François Revol <revol@free.fr>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*
+ * This file provides stubs for calling VBox runtime functions through the vboxguest module.
+ * It should be linked into any driver or module that uses the VBox runtime, except vboxguest
+ * itself (which contains the actual library and therefore doesn't need stubs to call it).
+ */
+
+#include "VBoxGuest-haiku.h"
+#include "VBoxGuestInternal.h"
+#include <VBox/log.h>
+#include <iprt/assert.h>
+#include <iprt/initterm.h>
+#include <iprt/process.h>
+#include <iprt/mem.h>
+#include <iprt/asm.h>
+#include <iprt/mp.h>
+#include <iprt/power.h>
+#include <iprt/thread.h>
+
+// >>> file('/tmp/stubs.c', 'w').writelines([re.sub(r'^(?P<returntype>[^(]+) \(\*_(?P<functionname>[A-Za-z0-9_]+)\)\((?P<params>[^)]+)\);', lambda m: '%s %s(%s)\n{\n    %sg_VBoxGuest->_%s(%s);\n}\n' % (m.group(1), m.group(2), m.group(3), ('return ' if m.group(1) != 'void' else ''), m.group(2), (', '.join(a.split(' ')[-1].replace('*', '') for a in m.group(3).split(',')) if m.group(3) != 'void' else '')), f) for f in functions])
+
+struct vboxguest_module_info *g_VBoxGuest;
+
+RTDECL(size_t) RTLogBackdoorPrintf(const char *pszFormat, ...)
+{
+    va_list args;
+    size_t cb;
+
+    va_start(args, pszFormat);
+    cb = g_VBoxGuest->_RTLogBackdoorPrintf(pszFormat, args);
+    va_end(args);
+
+    return cb;
+}
+RTDECL(size_t) RTLogBackdoorPrintfV(const char *pszFormat, va_list args)
+{
+    return g_VBoxGuest->_RTLogBackdoorPrintfV(pszFormat, args);
+}
+RTDECL(int) RTLogSetDefaultInstanceThread(PRTLOGGER pLogger, uintptr_t uKey)
+{
+    return g_VBoxGuest->_RTLogSetDefaultInstanceThread(pLogger, uKey);
+}
+RTDECL(int) RTMemAllocExTag(size_t cb, size_t cbAlignment, uint32_t fFlags, const char *pszTag, void **ppv)
+{
+    return g_VBoxGuest->_RTMemAllocExTag(cb, cbAlignment, fFlags, pszTag, ppv);
+}
+RTR0DECL(void*) RTMemContAlloc(PRTCCPHYS pPhys, size_t cb)
+{
+    return g_VBoxGuest->_RTMemContAlloc(pPhys, cb);
+}
+RTR0DECL(void) RTMemContFree(void *pv, size_t cb)
+{
+    g_VBoxGuest->_RTMemContFree(pv, cb);
+}
+RTDECL(void) RTMemFreeEx(void *pv, size_t cb)
+{
+    g_VBoxGuest->_RTMemFreeEx(pv, cb);
+}
+RTDECL(bool) RTMpIsCpuPossible(RTCPUID idCpu)
+{
+    return g_VBoxGuest->_RTMpIsCpuPossible(idCpu);
+}
+RTDECL(int) RTMpNotificationDeregister(PFNRTMPNOTIFICATION pfnCallback, void *pvUser)
+{
+    return g_VBoxGuest->_RTMpNotificationDeregister(pfnCallback, pvUser);
+}
+RTDECL(int) RTMpNotificationRegister(PFNRTMPNOTIFICATION pfnCallback, void *pvUser)
+{
+    return g_VBoxGuest->_RTMpNotificationRegister(pfnCallback, pvUser);
+}
+RTDECL(int) RTMpOnAll(PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    return g_VBoxGuest->_RTMpOnAll(pfnWorker, pvUser1, pvUser2);
+}
+RTDECL(int) RTMpOnOthers(PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    return g_VBoxGuest->_RTMpOnOthers(pfnWorker, pvUser1, pvUser2);
+}
+RTDECL(int) RTMpOnSpecific(RTCPUID idCpu, PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
+{
+    return g_VBoxGuest->_RTMpOnSpecific(idCpu, pfnWorker, pvUser1, pvUser2);
+}
+RTDECL(int) RTPowerNotificationDeregister(PFNRTPOWERNOTIFICATION pfnCallback, void *pvUser)
+{
+    return g_VBoxGuest->_RTPowerNotificationDeregister(pfnCallback, pvUser);
+}
+RTDECL(int) RTPowerNotificationRegister(PFNRTPOWERNOTIFICATION pfnCallback, void *pvUser)
+{
+    return g_VBoxGuest->_RTPowerNotificationRegister(pfnCallback, pvUser);
+}
+RTDECL(int) RTPowerSignalEvent(RTPOWEREVENT enmEvent)
+{
+    return g_VBoxGuest->_RTPowerSignalEvent(enmEvent);
+}
+RTR0DECL(void) RTR0AssertPanicSystem(void)
+{
+    g_VBoxGuest->_RTR0AssertPanicSystem();
+}
+RTR0DECL(int) RTR0Init(unsigned fReserved)
+{
+    return g_VBoxGuest->_RTR0Init(fReserved);
+}
+RTR0DECL(void*) RTR0MemObjAddress(RTR0MEMOBJ MemObj)
+{
+    return g_VBoxGuest->_RTR0MemObjAddress(MemObj);
+}
+RTR0DECL(RTR3PTR) RTR0MemObjAddressR3(RTR0MEMOBJ MemObj)
+{
+    return g_VBoxGuest->_RTR0MemObjAddressR3(MemObj);
+}
+RTR0DECL(int) RTR0MemObjAllocContTag(PRTR0MEMOBJ pMemObj, size_t cb, bool fExecutable, const char *pszTag)
+{
+    return g_VBoxGuest->_RTR0MemObjAllocContTag(pMemObj, cb, fExecutable, pszTag);
+}
+RTR0DECL(int) RTR0MemObjAllocLowTag(PRTR0MEMOBJ pMemObj, size_t cb, bool fExecutable, const char *pszTag)
+{
+    return g_VBoxGuest->_RTR0MemObjAllocLowTag(pMemObj, cb, fExecutable, pszTag);
+}
+RTR0DECL(int) RTR0MemObjAllocPageTag(PRTR0MEMOBJ pMemObj, size_t cb, bool fExecutable, const char *pszTag)
+{
+    return g_VBoxGuest->_RTR0MemObjAllocPageTag(pMemObj, cb, fExecutable, pszTag);
+}
+RTR0DECL(int) RTR0MemObjAllocPhysExTag(PRTR0MEMOBJ pMemObj, size_t cb, RTHCPHYS PhysHighest, size_t uAlignment, const char *pszTag)
+{
+    return g_VBoxGuest->_RTR0MemObjAllocPhysExTag(pMemObj, cb, PhysHighest, uAlignment, pszTag);
+}
+RTR0DECL(int) RTR0MemObjAllocPhysNCTag(PRTR0MEMOBJ pMemObj, size_t cb, RTHCPHYS PhysHighest, const char *pszTag)
+{
+    return g_VBoxGuest->_RTR0MemObjAllocPhysNCTag(pMemObj, cb, PhysHighest, pszTag);
+}
+RTR0DECL(int) RTR0MemObjAllocPhysTag(PRTR0MEMOBJ pMemObj, size_t cb, RTHCPHYS PhysHighest, const char *pszTag)
+{
+    return g_VBoxGuest->_RTR0MemObjAllocPhysTag(pMemObj, cb, PhysHighest, pszTag);
+}
+RTR0DECL(int) RTR0MemObjEnterPhysTag(PRTR0MEMOBJ pMemObj, RTHCPHYS Phys, size_t cb, uint32_t uCachePolicy, const char *pszTag)
+{
+    return g_VBoxGuest->_RTR0MemObjEnterPhysTag(pMemObj, Phys, cb, uCachePolicy, pszTag);
+}
+RTR0DECL(int) RTR0MemObjFree(RTR0MEMOBJ MemObj, bool fFreeMappings)
+{
+    return g_VBoxGuest->_RTR0MemObjFree(MemObj, fFreeMappings);
+}
+RTR0DECL(RTHCPHYS) RTR0MemObjGetPagePhysAddr(RTR0MEMOBJ MemObj, size_t iPage)
+{
+    return g_VBoxGuest->_RTR0MemObjGetPagePhysAddr(MemObj, iPage);
+}
+RTR0DECL(bool) RTR0MemObjIsMapping(RTR0MEMOBJ MemObj)
+{
+    return g_VBoxGuest->_RTR0MemObjIsMapping(MemObj);
+}
+RTR0DECL(int) RTR0MemObjLockKernelTag(PRTR0MEMOBJ pMemObj, void *pv, size_t cb, uint32_t fAccess, const char *pszTag)
+{
+    return g_VBoxGuest->_RTR0MemObjLockKernelTag(pMemObj, pv, cb, fAccess, pszTag);
+}
+RTR0DECL(int) RTR0MemObjLockUserTag(PRTR0MEMOBJ pMemObj, RTR3PTR R3Ptr, size_t cb, uint32_t fAccess, RTR0PROCESS R0Process, const char *pszTag)
+{
+    return g_VBoxGuest->_RTR0MemObjLockUserTag(pMemObj, R3Ptr, cb, fAccess, R0Process, pszTag);
+}
+RTR0DECL(int) RTR0MemObjMapKernelExTag(PRTR0MEMOBJ pMemObj, RTR0MEMOBJ MemObjToMap, void *pvFixed, size_t uAlignment, unsigned fProt, size_t offSub, size_t cbSub, const char *pszTag)
+{
+    return g_VBoxGuest->_RTR0MemObjMapKernelExTag(pMemObj, MemObjToMap, pvFixed, uAlignment, fProt, offSub, cbSub, pszTag);
+}
+RTR0DECL(int) RTR0MemObjMapKernelTag(PRTR0MEMOBJ pMemObj, RTR0MEMOBJ MemObjToMap, void *pvFixed, size_t uAlignment, unsigned fProt, const char *pszTag)
+{
+    return g_VBoxGuest->_RTR0MemObjMapKernelTag(pMemObj, MemObjToMap, pvFixed, uAlignment, fProt, pszTag);
+}
+RTR0DECL(int) RTR0MemObjMapUserTag(PRTR0MEMOBJ pMemObj, RTR0MEMOBJ MemObjToMap, RTR3PTR R3PtrFixed, size_t uAlignment, unsigned fProt, RTR0PROCESS R0Process, const char *pszTag)
+{
+    return g_VBoxGuest->_RTR0MemObjMapUserTag(pMemObj, MemObjToMap, R3PtrFixed, uAlignment, fProt, R0Process, pszTag);
+}
+RTR0DECL(int) RTR0MemObjProtect(RTR0MEMOBJ hMemObj, size_t offSub, size_t cbSub, uint32_t fProt)
+{
+    return g_VBoxGuest->_RTR0MemObjProtect(hMemObj, offSub, cbSub, fProt);
+}
+RTR0DECL(int) RTR0MemObjReserveKernelTag(PRTR0MEMOBJ pMemObj, void *pvFixed, size_t cb, size_t uAlignment, const char *pszTag)
+{
+    return g_VBoxGuest->_RTR0MemObjReserveKernelTag(pMemObj, pvFixed, cb, uAlignment, pszTag);
+}
+RTR0DECL(int) RTR0MemObjReserveUserTag(PRTR0MEMOBJ pMemObj, RTR3PTR R3PtrFixed, size_t cb, size_t uAlignment, RTR0PROCESS R0Process, const char *pszTag)
+{
+    return g_VBoxGuest->_RTR0MemObjReserveUserTag(pMemObj, R3PtrFixed, cb, uAlignment, R0Process, pszTag);
+}
+RTR0DECL(size_t) RTR0MemObjSize(RTR0MEMOBJ MemObj)
+{
+    return g_VBoxGuest->_RTR0MemObjSize(MemObj);
+}
+RTR0DECL(RTR0PROCESS) RTR0ProcHandleSelf(void)
+{
+    return g_VBoxGuest->_RTR0ProcHandleSelf();
+}
+RTR0DECL(void) RTR0Term(void)
+{
+    g_VBoxGuest->_RTR0Term();
+}
+RTR0DECL(void) RTR0TermForced(void)
+{
+    g_VBoxGuest->_RTR0TermForced();
+}
+RTDECL(RTPROCESS) RTProcSelf(void)
+{
+    return g_VBoxGuest->_RTProcSelf();
+}
+RTDECL(uint32_t) RTSemEventGetResolution(void)
+{
+    return g_VBoxGuest->_RTSemEventGetResolution();
+}
+RTDECL(uint32_t) RTSemEventMultiGetResolution(void)
+{
+    return g_VBoxGuest->_RTSemEventMultiGetResolution();
+}
+RTDECL(int) RTSemEventMultiWaitEx(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout)
+{
+    return g_VBoxGuest->_RTSemEventMultiWaitEx(hEventMultiSem, fFlags, uTimeout);
+}
+RTDECL(int) RTSemEventMultiWaitExDebug(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout, RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    return g_VBoxGuest->_RTSemEventMultiWaitExDebug(hEventMultiSem, fFlags, uTimeout, uId, pszFile, iLine, pszFunction);
+}
+RTDECL(int) RTSemEventWaitEx(RTSEMEVENT hEventSem, uint32_t fFlags, uint64_t uTimeout)
+{
+    return g_VBoxGuest->_RTSemEventWaitEx(hEventSem, fFlags, uTimeout);
+}
+RTDECL(int) RTSemEventWaitExDebug(RTSEMEVENT hEventSem, uint32_t fFlags, uint64_t uTimeout, RTHCUINTPTR uId, RT_SRC_POS_DECL)
+{
+    return g_VBoxGuest->_RTSemEventWaitExDebug(hEventSem, fFlags, uTimeout, uId, pszFile, iLine, pszFunction);
+}
+RTDECL(bool) RTThreadIsInInterrupt(RTTHREAD hThread)
+{
+    return g_VBoxGuest->_RTThreadIsInInterrupt(hThread);
+}
+RTDECL(void) RTThreadPreemptDisable(PRTTHREADPREEMPTSTATE pState)
+{
+    g_VBoxGuest->_RTThreadPreemptDisable(pState);
+}
+RTDECL(bool) RTThreadPreemptIsEnabled(RTTHREAD hThread)
+{
+    return g_VBoxGuest->_RTThreadPreemptIsEnabled(hThread);
+}
+RTDECL(bool) RTThreadPreemptIsPending(RTTHREAD hThread)
+{
+    return g_VBoxGuest->_RTThreadPreemptIsPending(hThread);
+}
+RTDECL(bool) RTThreadPreemptIsPendingTrusty(void)
+{
+    return g_VBoxGuest->_RTThreadPreemptIsPendingTrusty();
+}
+RTDECL(bool) RTThreadPreemptIsPossible(void)
+{
+    return g_VBoxGuest->_RTThreadPreemptIsPossible();
+}
+RTDECL(void) RTThreadPreemptRestore(PRTTHREADPREEMPTSTATE pState)
+{
+    g_VBoxGuest->_RTThreadPreemptRestore(pState);
+}
+RTDECL(uint32_t) RTTimerGetSystemGranularity(void)
+{
+    return g_VBoxGuest->_RTTimerGetSystemGranularity();
+}
+RTDECL(int) RTTimerReleaseSystemGranularity(uint32_t u32Granted)
+{
+    return g_VBoxGuest->_RTTimerReleaseSystemGranularity(u32Granted);
+}
+RTDECL(int) RTTimerRequestSystemGranularity(uint32_t u32Request, uint32_t *pu32Granted)
+{
+    return g_VBoxGuest->_RTTimerRequestSystemGranularity(u32Request, pu32Granted);
+}
+RTDECL(void) RTSpinlockAcquire(RTSPINLOCK Spinlock)
+{
+    g_VBoxGuest->_RTSpinlockAcquire(Spinlock);
+}
+RTDECL(void) RTSpinlockRelease(RTSPINLOCK Spinlock)
+{
+    g_VBoxGuest->_RTSpinlockRelease(Spinlock);
+}
+RTDECL(void*) RTMemTmpAllocTag(size_t cb, const char *pszTag)
+{
+    return g_VBoxGuest->_RTMemTmpAllocTag(cb, pszTag);
+}
+RTDECL(void) RTMemTmpFree(void *pv)
+{
+    g_VBoxGuest->_RTMemTmpFree(pv);
+}
+RTDECL(PRTLOGGER) RTLogDefaultInstance(void)
+{
+    return g_VBoxGuest->_RTLogDefaultInstance();
+}
+RTDECL(PRTLOGGER) RTLogDefaultInstanceEx(uint32_t fFlagsAndGroup)
+{
+    return g_VBoxGuest->_RTLogDefaultInstanceEx(fFlagsAndGroup);
+}
+RTDECL(PRTLOGGER) RTLogRelGetDefaultInstance(void)
+{
+    return g_VBoxGuest->_RTLogRelGetDefaultInstance();
+}
+RTDECL(PRTLOGGER) RTLogRelGetDefaultInstance(uint32_t fFlags, uint32_t iGroup)
+{
+    return g_VBoxGuest->_RTLogRelGetDefaultInstanceEx(fFlags, iGroup);
+}
+RTDECL(int) RTErrConvertToErrno(int iErr)
+{
+    return g_VBoxGuest->_RTErrConvertToErrno(iErr);
+}
+int VGDrvCommonIoCtl(unsigned iFunction, PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession, void *pvData, size_t cbData, size_t *pcbDataReturned)
+{
+    return g_VBoxGuest->_VGDrvCommonIoCtl(iFunction, pDevExt, pSession, pvData, cbData, pcbDataReturned);
+}
+int VGDrvCommonCreateUserSession(PVBOXGUESTDEVEXT pDevExt, uint32_t fRequestor, PVBOXGUESTSESSION *ppSession)
+{
+    return g_VBoxGuest->_VGDrvCommonCreateUserSession(pDevExt, fRequestor, ppSession);
+}
+void VGDrvCommonCloseSession(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession)
+{
+    g_VBoxGuest->_VGDrvCommonCloseSession(pDevExt, pSession);
+}
+void* VBoxGuestIDCOpen(uint32_t *pu32Version)
+{
+    return g_VBoxGuest->_VBoxGuestIDCOpen(pu32Version);
+}
+int VBoxGuestIDCClose(void *pvSession)
+{
+    return g_VBoxGuest->_VBoxGuestIDCClose(pvSession);
+}
+int VBoxGuestIDCCall(void *pvSession, unsigned iCmd, void *pvData, size_t cbData, size_t *pcbDataReturned)
+{
+    return g_VBoxGuest->_VBoxGuestIDCCall(pvSession, iCmd, pvData, cbData, pcbDataReturned);
+}
+RTDECL(void) RTAssertMsg1Weak(const char *pszExpr, unsigned uLine, const char *pszFile, const char *pszFunction)
+{
+    g_VBoxGuest->_RTAssertMsg1Weak(pszExpr, uLine, pszFile, pszFunction);
+}
+RTDECL(void) RTAssertMsg2Weak(const char *pszFormat, ...)
+{
+    va_list va;
+    va_start(va, pszFormat);
+    RTAssertMsg2WeakV(pszFormat, va);
+    va_end(va);
+}
+RTDECL(void) RTAssertMsg2WeakV(const char *pszFormat, va_list va)
+{
+    g_VBoxGuest->_RTAssertMsg2WeakV(pszFormat, va);
+}
+RTDECL(bool) RTAssertShouldPanic(void)
+{
+    return g_VBoxGuest->_RTAssertShouldPanic();
+}
+RTDECL(int) RTSemFastMutexCreate(PRTSEMFASTMUTEX phFastMtx)
+{
+    return g_VBoxGuest->_RTSemFastMutexCreate(phFastMtx);
+}
+RTDECL(int) RTSemFastMutexDestroy(RTSEMFASTMUTEX hFastMtx)
+{
+    return g_VBoxGuest->_RTSemFastMutexDestroy(hFastMtx);
+}
+RTDECL(int) RTSemFastMutexRelease(RTSEMFASTMUTEX hFastMtx)
+{
+    return g_VBoxGuest->_RTSemFastMutexRelease(hFastMtx);
+}
+RTDECL(int) RTSemFastMutexRequest(RTSEMFASTMUTEX hFastMtx)
+{
+    return g_VBoxGuest->_RTSemFastMutexRequest(hFastMtx);
+}
+RTDECL(int) RTSemMutexCreate(PRTSEMMUTEX phFastMtx)
+{
+    return g_VBoxGuest->_RTSemMutexCreate(phFastMtx);
+}
+RTDECL(int) RTSemMutexDestroy(RTSEMMUTEX hFastMtx)
+{
+    return g_VBoxGuest->_RTSemMutexDestroy(hFastMtx);
+}
+RTDECL(int) RTSemMutexRelease(RTSEMMUTEX hFastMtx)
+{
+    return g_VBoxGuest->_RTSemMutexRelease(hFastMtx);
+}
+RTDECL(int) RTSemMutexRequest(RTSEMMUTEX hFastMtx, RTMSINTERVAL cMillies)
+{
+    return g_VBoxGuest->_RTSemMutexRequest(hFastMtx, cMillies);
+}
+int RTHeapSimpleRelocate(RTHEAPSIMPLE hHeap, uintptr_t offDelta)
+{
+    return g_VBoxGuest->_RTHeapSimpleRelocate(hHeap, offDelta);
+}
+int RTHeapOffsetInit(PRTHEAPOFFSET phHeap, void *pvMemory, size_t cbMemory)
+{
+    return g_VBoxGuest->_RTHeapOffsetInit(phHeap, pvMemory, cbMemory);
+}
+int RTHeapSimpleInit(PRTHEAPSIMPLE pHeap, void *pvMemory, size_t cbMemory)
+{
+    return g_VBoxGuest->_RTHeapSimpleInit(pHeap, pvMemory, cbMemory);
+}
+void* RTHeapOffsetAlloc(RTHEAPOFFSET hHeap, size_t cb, size_t cbAlignment)
+{
+    return g_VBoxGuest->_RTHeapOffsetAlloc(hHeap, cb, cbAlignment);
+}
+void* RTHeapSimpleAlloc(RTHEAPSIMPLE Heap, size_t cb, size_t cbAlignment)
+{
+    return g_VBoxGuest->_RTHeapSimpleAlloc(Heap, cb, cbAlignment);
+}
+void RTHeapOffsetFree(RTHEAPOFFSET hHeap, void *pv)
+{
+    g_VBoxGuest->_RTHeapOffsetFree(hHeap, pv);
+}
+void RTHeapSimpleFree(RTHEAPSIMPLE Heap, void *pv)
+{
+    g_VBoxGuest->_RTHeapSimpleFree(Heap, pv);
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/VBoxGuest-haiku.c b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-haiku.c
new file mode 100644
index 00000000..2a872032
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-haiku.c
@@ -0,0 +1,588 @@
+/* $Id: VBoxGuest-haiku.c $ */
+/** @file
+ * VBoxGuest kernel module, Haiku Guest Additions, implementation.
+ */
+
+/*
+ * 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
+ */
+
+/*
+ * This code is based on:
+ *
+ * VirtualBox Guest Additions for Haiku.
+ * Copyright (c) 2011 Mike Smith <mike@scgtrp.net>
+ *                    François Revol <revol@free.fr>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define IN_VBOXGUEST
+#include <sys/param.h>
+#include <sys/types.h>
+#include <sys/uio.h>
+#include <OS.h>
+#include <Drivers.h>
+#include <KernelExport.h>
+#include <PCI.h>
+
+#include "VBoxGuest-haiku.h"
+#include "VBoxGuestInternal.h"
+#include <VBox/log.h>
+#include <iprt/assert.h>
+#include <iprt/initterm.h>
+#include <iprt/process.h>
+#include <iprt/mem.h>
+#include <iprt/memobj.h>
+#include <iprt/asm.h>
+#include <iprt/timer.h>
+#include <iprt/heap.h>
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+#define MODULE_NAME VBOXGUEST_MODULE_NAME
+
+
+/*********************************************************************************************************************************
+*   Internal Functions                                                                                                           *
+*********************************************************************************************************************************/
+/*
+ * IRQ related functions.
+ */
+static void  vgdrvHaikuRemoveIRQ(void *pvState);
+static int   vgdrvHaikuAddIRQ(void *pvState);
+static int32 vgdrvHaikuISR(void *pvState);
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+static status_t std_ops(int32 op, ...);
+
+static RTSPINLOCK g_Spinlock = NIL_RTSPINLOCK;
+
+int32    api_version = B_CUR_DRIVER_API_VERSION;
+
+/** List of cloned device. Managed by the kernel. */
+//static struct clonedevs    *g_pvgdrvHaikuClones;
+/** The dev_clone event handler tag. */
+//static eventhandler_tag     g_vgdrvHaikuEHTag;
+/** selinfo structure used for polling. */
+//static struct selinfo       g_SelInfo;
+/** PCI Bus Manager Module */
+static pci_module_info *gPCI;
+
+static struct vboxguest_module_info g_VBoxGuest =
+{
+    {
+        MODULE_NAME,
+        0,
+        std_ops
+    },
+    { 0 },
+    { 0 },
+    0,
+    RTLogBackdoorPrintf,
+    RTLogBackdoorPrintfV,
+    RTLogSetDefaultInstanceThread,
+    RTMemAllocExTag,
+    RTMemContAlloc,
+    RTMemContFree,
+    RTMemFreeEx,
+    RTMpIsCpuPossible,
+    RTMpNotificationDeregister,
+    RTMpNotificationRegister,
+    RTMpOnAll,
+    RTMpOnOthers,
+    RTMpOnSpecific,
+    RTPowerNotificationDeregister,
+    RTPowerNotificationRegister,
+    RTPowerSignalEvent,
+    RTR0AssertPanicSystem,
+    RTR0Init,
+    RTR0MemObjAddress,
+    RTR0MemObjAddressR3,
+    RTR0MemObjAllocContTag,
+    RTR0MemObjAllocLowTag,
+    RTR0MemObjAllocPageTag,
+    RTR0MemObjAllocPhysExTag,
+    RTR0MemObjAllocPhysNCTag,
+    RTR0MemObjAllocPhysTag,
+    RTR0MemObjEnterPhysTag,
+    RTR0MemObjFree,
+    RTR0MemObjGetPagePhysAddr,
+    RTR0MemObjIsMapping,
+    RTR0MemObjLockKernelTag,
+    RTR0MemObjLockUserTag,
+    RTR0MemObjMapKernelExTag,
+    RTR0MemObjMapKernelTag,
+    RTR0MemObjMapUserTag,
+    RTR0MemObjProtect,
+    RTR0MemObjReserveKernelTag,
+    RTR0MemObjReserveUserTag,
+    RTR0MemObjSize,
+    RTR0ProcHandleSelf,
+    RTR0Term,
+    RTR0TermForced,
+    RTProcSelf,
+    RTSemEventGetResolution,
+    RTSemEventMultiGetResolution,
+    RTSemEventMultiWaitEx,
+    RTSemEventMultiWaitExDebug,
+    RTSemEventWaitEx,
+    RTSemEventWaitExDebug,
+    RTThreadIsInInterrupt,
+    RTThreadPreemptDisable,
+    RTThreadPreemptIsEnabled,
+    RTThreadPreemptIsPending,
+    RTThreadPreemptIsPendingTrusty,
+    RTThreadPreemptIsPossible,
+    RTThreadPreemptRestore,
+    RTTimerGetSystemGranularity,
+    RTTimerReleaseSystemGranularity,
+    RTTimerRequestSystemGranularity,
+    RTSpinlockAcquire,
+    RTSpinlockRelease,
+    RTMemTmpAllocTag,
+    RTMemTmpFree,
+    RTLogDefaultInstance,
+    RTLogDefaultInstanceEx,
+    RTLogRelGetDefaultInstance,
+    RTLogRelGetDefaultInstanceEx,
+    RTErrConvertToErrno,
+    VGDrvCommonIoCtl,
+    VGDrvCommonCreateUserSession,
+    VGDrvCommonCloseSession,
+    VBoxGuestIDCOpen,
+    VBoxGuestIDCClose,
+    VBoxGuestIDCCall,
+    RTAssertMsg1Weak,
+    RTAssertMsg2Weak,
+    RTAssertMsg2WeakV,
+    RTAssertShouldPanic,
+    RTSemFastMutexCreate,
+    RTSemFastMutexDestroy,
+    RTSemFastMutexRelease,
+    RTSemFastMutexRequest,
+    RTSemMutexCreate,
+    RTSemMutexDestroy,
+    RTSemMutexRelease,
+    RTSemMutexRequest,
+    RTHeapSimpleRelocate,
+    RTHeapOffsetInit,
+    RTHeapSimpleInit,
+    RTHeapOffsetAlloc,
+    RTHeapSimpleAlloc,
+    RTHeapOffsetFree,
+    RTHeapSimpleFree
+};
+
+#if 0
+/**
+ * DEVFS event handler.
+ */
+static void vgdrvHaikuClone(void *pvArg, struct ucred *pCred, char *pszName, int cchName, struct cdev **ppDev)
+{
+    int iUnit;
+    int rc;
+
+    Log(("vgdrvHaikuClone: pszName=%s ppDev=%p\n", pszName, ppDev));
+
+    /*
+     * One device node per user, si_drv1 points to the session.
+     * /dev/vboxguest<N> where N = {0...255}.
+     */
+    if (!ppDev)
+    return;
+    if (strcmp(pszName, "vboxguest") == 0)
+    iUnit =  -1;
+    else if (dev_stdclone(pszName, NULL, "vboxguest", &iUnit) != 1)
+    return;
+    if (iUnit >= 256)
+    {
+        Log(("vgdrvHaikuClone: iUnit=%d >= 256 - rejected\n", iUnit));
+        return;
+    }
+
+    Log(("vgdrvHaikuClone: pszName=%s iUnit=%d\n", pszName, iUnit));
+
+    rc = clone_create(&g_pvgdrvHaikuClones, &g_vgdrvHaikuDeviceHooks, &iUnit, ppDev, 0);
+    Log(("vgdrvHaikuClone: clone_create -> %d; iUnit=%d\n", rc, iUnit));
+    if (rc)
+    {
+        *ppDev = make_dev(&g_vgdrvHaikuDeviceHooks,
+                          iUnit,
+                          UID_ROOT,
+                          GID_WHEEL,
+                          0644,
+                          "vboxguest%d", iUnit);
+        if (*ppDev)
+        {
+            dev_ref(*ppDev);
+            (*ppDev)->si_flags |= SI_CHEAPCLONE;
+            Log(("vgdrvHaikuClone: Created *ppDev=%p iUnit=%d si_drv1=%p si_drv2=%p\n",
+                 *ppDev, iUnit, (*ppDev)->si_drv1, (*ppDev)->si_drv2));
+            (*ppDev)->si_drv1 = (*ppDev)->si_drv2 = NULL;
+        }
+        else
+        Log(("vgdrvHaikuClone: make_dev iUnit=%d failed\n", iUnit));
+    }
+    else
+    Log(("vgdrvHaikuClone: Existing *ppDev=%p iUnit=%d si_drv1=%p si_drv2=%p\n",
+         *ppDev, iUnit, (*ppDev)->si_drv1, (*ppDev)->si_drv2));
+}
+#endif
+
+
+static status_t vgdrvHaikuDetach(void)
+{
+    struct VBoxGuestDeviceState *pState = &sState;
+
+    if (cUsers > 0)
+        return EBUSY;
+
+    /*
+     * Reverse what we did in vgdrvHaikuAttach.
+     */
+    vgdrvHaikuRemoveIRQ(pState);
+
+    if (pState->iVMMDevMemAreaId)
+        delete_area(pState->iVMMDevMemAreaId);
+
+    VGDrvCommonDeleteDevExt(&g_DevExt);
+
+#ifdef DO_LOG
+    RTLogDestroy(RTLogRelSetDefaultInstance(NULL));
+    RTLogSetDefaultInstance(NULL);
+//    RTLogDestroy(RTLogSetDefaultInstance(NULL));
+#endif
+
+    RTSpinlockDestroy(g_Spinlock);
+    g_Spinlock = NIL_RTSPINLOCK;
+
+    RTR0Term();
+    return B_OK;
+}
+
+
+/**
+ * Interrupt service routine.
+ *
+ * @returns Whether the interrupt was from VMMDev.
+ * @param   pvState Opaque pointer to the device state.
+ */
+static int32 vgdrvHaikuISR(void *pvState)
+{
+    LogFlow((MODULE_NAME ":vgdrvHaikuISR pvState=%p\n", pvState));
+
+    bool fOurIRQ = VGDrvCommonISR(&g_DevExt);
+    if (fOurIRQ)
+        return B_HANDLED_INTERRUPT;
+    return B_UNHANDLED_INTERRUPT;
+}
+
+
+void VGDrvNativeISRMousePollEvent(PVBOXGUESTDEVEXT pDevExt)
+{
+    LogFlow(("VGDrvNativeISRMousePollEvent:\n"));
+
+    status_t err = B_OK;
+    //dprintf(MODULE_NAME ": isr mouse\n");
+
+    /*
+     * Wake up poll waiters.
+     */
+    //selwakeup(&g_SelInfo);
+    //XXX:notify_select_event();
+    RTSpinlockAcquire(g_Spinlock);
+
+    if (sState.selectSync)
+    {
+        //dprintf(MODULE_NAME ": isr mouse: notify\n");
+        notify_select_event(sState.selectSync, sState.selectEvent);
+        sState.selectEvent = (uint8_t)0;
+        sState.selectRef = (uint32_t)0;
+        sState.selectSync = NULL;
+    }
+    else
+        err = B_ERROR;
+
+    RTSpinlockRelease(g_Spinlock);
+}
+
+
+bool VGDrvNativeProcessOption(PVBOXGUESTDEVEXT pDevExt, const char *pszName, const char *pszValue)
+{
+    RT_NOREF(pDevExt); RT_NOREF(pszName); RT_NOREF(pszValue);
+    return false;
+}
+
+
+/**
+ * Sets IRQ for VMMDev.
+ *
+ * @returns Haiku error code.
+ * @param   pvState  Pointer to the state info structure.
+ */
+static int vgdrvHaikuAddIRQ(void *pvState)
+{
+    status_t err;
+    struct VBoxGuestDeviceState *pState = (struct VBoxGuestDeviceState *)pvState;
+
+    AssertReturn(pState, VERR_INVALID_PARAMETER);
+
+    err = install_io_interrupt_handler(pState->iIrqResId, vgdrvHaikuISR, pState,  0);
+    if (err == B_OK)
+        return VINF_SUCCESS;
+    return VERR_DEV_IO_ERROR;
+}
+
+
+/**
+ * Removes IRQ for VMMDev.
+ *
+ * @param   pvState  Opaque pointer to the state info structure.
+ */
+static void vgdrvHaikuRemoveIRQ(void *pvState)
+{
+    struct VBoxGuestDeviceState *pState = (struct VBoxGuestDeviceState *)pvState;
+    AssertPtr(pState);
+
+    remove_io_interrupt_handler(pState->iIrqResId, vgdrvHaikuISR, pState);
+}
+
+
+static status_t vgdrvHaikuAttach(const pci_info *pDevice)
+{
+    status_t status;
+    int rc;
+    int iResId;
+    struct VBoxGuestDeviceState *pState = &sState;
+    static const char *const     s_apszGroups[] = VBOX_LOGGROUP_NAMES;
+    PRTLOGGER                    pRelLogger;
+
+    AssertReturn(pDevice, B_BAD_VALUE);
+
+    cUsers = 0;
+
+    /*
+     * Initialize IPRT R0 driver, which internally calls OS-specific r0 init.
+     */
+    rc = RTR0Init(0);
+    if (RT_FAILURE(rc))
+    {
+        dprintf(MODULE_NAME ": RTR0Init failed: %d\n", rc);
+        return ENXIO;
+    }
+
+    rc = RTSpinlockCreate(&g_Spinlock, RTSPINLOCK_FLAGS_INTERRUPT_SAFE, "vgdrvHaiku");
+    if (RT_FAILURE(rc))
+    {
+        LogRel(("vgdrvHaikuAttach: RTSpinlock create failed. rc=%Rrc\n", rc));
+        return ENXIO;
+    }
+
+#ifdef DO_LOG
+    /*
+     * Create the release log.
+     * (We do that here instead of common code because we want to log
+     * early failures using the LogRel macro.)
+     */
+    rc = RTLogCreate(&pRelLogger, 0 | RTLOGFLAGS_PREFIX_THREAD /* fFlags */, "all",
+                     "VBOX_RELEASE_LOG", RT_ELEMENTS(s_apszGroups), s_apszGroups,
+                     RTLOGDEST_STDOUT | RTLOGDEST_DEBUGGER | RTLOGDEST_USER, NULL);
+    dprintf(MODULE_NAME ": RTLogCreate: %d\n", rc);
+    if (RT_SUCCESS(rc))
+    {
+        //RTLogGroupSettings(pRelLogger, g_szLogGrp);
+        //RTLogFlags(pRelLogger, g_szLogFlags);
+        //RTLogDestinations(pRelLogger, "/var/log/vboxguest.log");
+        RTLogRelSetDefaultInstance(pRelLogger);
+        RTLogSetDefaultInstance(pRelLogger); //XXX
+    }
+#endif
+
+    /*
+     * Allocate I/O port resource.
+     */
+    pState->uIOPortBase = pDevice->u.h0.base_registers[0];
+    /** @todo check flags for IO? */
+    if (pState->uIOPortBase)
+    {
+        /*
+         * Map the MMIO region.
+         */
+        uint32 phys = pDevice->u.h0.base_registers[1];
+        /** @todo Check flags for mem? */
+        pState->VMMDevMemSize    = pDevice->u.h0.base_register_sizes[1];
+        pState->iVMMDevMemAreaId = map_physical_memory("VirtualBox Guest MMIO", phys, pState->VMMDevMemSize,
+                                                       B_ANY_KERNEL_BLOCK_ADDRESS, B_KERNEL_READ_AREA | B_KERNEL_WRITE_AREA,
+                                                       &pState->pMMIOBase);
+        if (pState->iVMMDevMemAreaId > 0 && pState->pMMIOBase)
+        {
+            /*
+             * Call the common device extension initializer.
+             */
+            rc = VGDrvCommonInitDevExt(&g_DevExt, pState->uIOPortBase, pState->pMMIOBase, pState->VMMDevMemSize,
+#if ARCH_BITS == 64
+                                       VBOXOSTYPE_Haiku_x64,
+#else
+                                       VBOXOSTYPE_Haiku,
+#endif
+                                       VMMDEV_EVENT_MOUSE_POSITION_CHANGED);
+            if (RT_SUCCESS(rc))
+            {
+                /*
+                 * Add IRQ of VMMDev.
+                 */
+                pState->iIrqResId = pDevice->u.h0.interrupt_line;
+                rc = vgdrvHaikuAddIRQ(pState);
+                if (RT_SUCCESS(rc))
+                {
+                    /*
+                     * Read host configuration.
+                     */
+                    VGDrvCommonProcessOptionsFromHost(&g_DevExt);
+
+                    LogRel((MODULE_NAME ": loaded successfully\n"));
+                    return B_OK;
+                }
+
+                LogRel((MODULE_NAME ": VGDrvCommonInitDevExt failed.\n"));
+                VGDrvCommonDeleteDevExt(&g_DevExt);
+            }
+            else
+                LogRel((MODULE_NAME ": vgdrvHaikuAddIRQ failed.\n"));
+        }
+        else
+            LogRel((MODULE_NAME ": MMIO region setup failed.\n"));
+    }
+    else
+        LogRel((MODULE_NAME ": IOport setup failed.\n"));
+
+    RTR0Term();
+    return ENXIO;
+}
+
+
+static status_t vgdrvHaikuProbe(pci_info *pDevice)
+{
+    if (   pDevice->vendor_id == VMMDEV_VENDORID
+        && pDevice->device_id == VMMDEV_DEVICEID)
+        return B_OK;
+
+    return ENXIO;
+}
+
+
+status_t init_module(void)
+{
+    status_t err = B_ENTRY_NOT_FOUND;
+    pci_info info;
+    int ix = 0;
+
+    err = get_module(B_PCI_MODULE_NAME, (module_info **)&gPCI);
+    if (err != B_OK)
+        return err;
+
+    while ((*gPCI->get_nth_pci_info)(ix++, &info) == B_OK)
+    {
+        if (vgdrvHaikuProbe(&info) == 0)
+        {
+            /* We found it */
+            err = vgdrvHaikuAttach(&info);
+            return err;
+        }
+    }
+
+    return B_ENTRY_NOT_FOUND;
+}
+
+
+void uninit_module(void)
+{
+    vgdrvHaikuDetach();
+    put_module(B_PCI_MODULE_NAME);
+}
+
+
+static status_t std_ops(int32 op, ...)
+{
+    switch (op)
+    {
+        case B_MODULE_INIT:
+            return init_module();
+
+        case B_MODULE_UNINIT:
+        {
+            uninit_module();
+            return B_OK;
+        }
+
+        default:
+            return B_ERROR;
+    }
+}
+
+
+_EXPORT module_info *modules[] =
+{
+    (module_info *)&g_VBoxGuest,
+    NULL
+};
+
+/* Common code that depend on g_DevExt. */
+#include "VBoxGuestIDC-unix.c.h"
+
diff --git a/src/VBox/Additions/common/VBoxGuest/VBoxGuest-haiku.h b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-haiku.h
new file mode 100644
index 00000000..a5fa58d6
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-haiku.h
@@ -0,0 +1,248 @@
+/* $Id: VBoxGuest-haiku.h $ */
+/** @file
+ * VBoxGuest kernel module, Haiku Guest Additions, header.
+ */
+
+/*
+ * 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
+ */
+
+/*
+ * This code is based on:
+ *
+ * VirtualBox Guest Additions for Haiku.
+ * Copyright (c) 2011 Mike Smith <mike@scgtrp.net>
+ *                    François Revol <revol@free.fr>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef GA_INCLUDED_SRC_common_VBoxGuest_VBoxGuest_haiku_h
+#define GA_INCLUDED_SRC_common_VBoxGuest_VBoxGuest_haiku_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <OS.h>
+#include <Drivers.h>
+#include <drivers/module.h>
+
+#include "VBoxGuestInternal.h"
+#include <VBox/log.h>
+#include <iprt/assert.h>
+#include <iprt/initterm.h>
+#include <iprt/process.h>
+#include <iprt/mem.h>
+#include <iprt/asm.h>
+#include <iprt/mp.h>
+#include <iprt/power.h>
+#include <iprt/thread.h>
+
+/** The module name. */
+#define VBOXGUEST_MODULE_NAME "generic/vboxguest"
+
+struct VBoxGuestDeviceState
+{
+    /** Resource ID of the I/O port */
+    int                iIOPortResId;
+    /** Pointer to the I/O port resource. */
+//    struct resource   *pIOPortRes;
+    /** Start address of the IO Port. */
+    uint16_t           uIOPortBase;
+    /** Resource ID of the MMIO area */
+    area_id            iVMMDevMemAreaId;
+    /** Pointer to the MMIO resource. */
+//    struct resource   *pVMMDevMemRes;
+    /** Handle of the MMIO resource. */
+//    bus_space_handle_t VMMDevMemHandle;
+    /** Size of the memory area. */
+    size_t             VMMDevMemSize;
+    /** Mapping of the register space */
+    void              *pMMIOBase;
+    /** IRQ number */
+    int                iIrqResId;
+    /** IRQ resource handle. */
+//    struct resource   *pIrqRes;
+    /** Pointer to the IRQ handler. */
+//    void              *pfnIrqHandler;
+    /** VMMDev version */
+    uint32_t           u32Version;
+
+    /** The (only) select data we wait on. */
+    //XXX: should leave in pSession ?
+    uint8_t            selectEvent;
+    uint32_t           selectRef;
+    void              *selectSync;
+};
+
+struct vboxguest_module_info
+{
+    module_info module;
+
+    VBOXGUESTDEVEXT devExt;
+    struct VBoxGuestDeviceState _sState;
+    volatile uint32_t _cUsers;
+
+    size_t(*_RTLogBackdoorPrintf)(const char *pszFormat, ...);
+    size_t(*_RTLogBackdoorPrintfV)(const char *pszFormat, va_list args);
+    int (*_RTLogSetDefaultInstanceThread)(PRTLOGGER pLogger, uintptr_t uKey);
+    int (*_RTMemAllocExTag)(size_t cb, size_t cbAlignment, uint32_t fFlags, const char *pszTag, void **ppv);
+    void* (*_RTMemContAlloc)(PRTCCPHYS pPhys, size_t cb);
+    void (*_RTMemContFree)(void *pv, size_t cb);
+    void (*_RTMemFreeEx)(void *pv, size_t cb);
+    bool (*_RTMpIsCpuPossible)(RTCPUID idCpu);
+    int (*_RTMpNotificationDeregister)(PFNRTMPNOTIFICATION pfnCallback, void *pvUser);
+    int (*_RTMpNotificationRegister)(PFNRTMPNOTIFICATION pfnCallback, void *pvUser);
+    int (*_RTMpOnAll)(PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2);
+    int (*_RTMpOnOthers)(PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2);
+    int (*_RTMpOnSpecific)(RTCPUID idCpu, PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2);
+    int (*_RTPowerNotificationDeregister)(PFNRTPOWERNOTIFICATION pfnCallback, void *pvUser);
+    int (*_RTPowerNotificationRegister)(PFNRTPOWERNOTIFICATION pfnCallback, void *pvUser);
+    int (*_RTPowerSignalEvent)(RTPOWEREVENT enmEvent);
+    void (*_RTR0AssertPanicSystem)(void);
+    int (*_RTR0Init)(unsigned fReserved);
+    void* (*_RTR0MemObjAddress)(RTR0MEMOBJ MemObj);
+    RTR3PTR(*_RTR0MemObjAddressR3)(RTR0MEMOBJ MemObj);
+    int (*_RTR0MemObjAllocContTag)(PRTR0MEMOBJ pMemObj, size_t cb, bool fExecutable, const char *pszTag);
+    int (*_RTR0MemObjAllocLowTag)(PRTR0MEMOBJ pMemObj, size_t cb, bool fExecutable, const char *pszTag);
+    int (*_RTR0MemObjAllocPageTag)(PRTR0MEMOBJ pMemObj, size_t cb, bool fExecutable, const char *pszTag);
+    int (*_RTR0MemObjAllocPhysExTag)(PRTR0MEMOBJ pMemObj, size_t cb, RTHCPHYS PhysHighest, size_t uAlignment, const char *pszTag);
+    int (*_RTR0MemObjAllocPhysNCTag)(PRTR0MEMOBJ pMemObj, size_t cb, RTHCPHYS PhysHighest, const char *pszTag);
+    int (*_RTR0MemObjAllocPhysTag)(PRTR0MEMOBJ pMemObj, size_t cb, RTHCPHYS PhysHighest, const char *pszTag);
+    int (*_RTR0MemObjEnterPhysTag)(PRTR0MEMOBJ pMemObj, RTHCPHYS Phys, size_t cb, uint32_t uCachePolicy, const char *pszTag);
+    int (*_RTR0MemObjFree)(RTR0MEMOBJ MemObj, bool fFreeMappings);
+    RTHCPHYS(*_RTR0MemObjGetPagePhysAddr)(RTR0MEMOBJ MemObj, size_t iPage);
+    bool (*_RTR0MemObjIsMapping)(RTR0MEMOBJ MemObj);
+    int (*_RTR0MemObjLockKernelTag)(PRTR0MEMOBJ pMemObj, void *pv, size_t cb, uint32_t fAccess, const char *pszTag);
+    int (*_RTR0MemObjLockUserTag)(PRTR0MEMOBJ pMemObj, RTR3PTR R3Ptr, size_t cb, uint32_t fAccess,
+                                  RTR0PROCESS R0Process, const char *pszTag);
+    int (*_RTR0MemObjMapKernelExTag)(PRTR0MEMOBJ pMemObj, RTR0MEMOBJ MemObjToMap, void *pvFixed, size_t uAlignment,
+                                     unsigned fProt, size_t offSub, size_t cbSub, const char *pszTag);
+    int (*_RTR0MemObjMapKernelTag)(PRTR0MEMOBJ pMemObj, RTR0MEMOBJ MemObjToMap, void *pvFixed,
+                                   size_t uAlignment, unsigned fProt, const char *pszTag);
+    int (*_RTR0MemObjMapUserTag)(PRTR0MEMOBJ pMemObj, RTR0MEMOBJ MemObjToMap, RTR3PTR R3PtrFixed,
+                                 size_t uAlignment, unsigned fProt, RTR0PROCESS R0Process, const char *pszTag);
+    int (*_RTR0MemObjProtect)(RTR0MEMOBJ hMemObj, size_t offSub, size_t cbSub, uint32_t fProt);
+    int (*_RTR0MemObjReserveKernelTag)(PRTR0MEMOBJ pMemObj, void *pvFixed, size_t cb, size_t uAlignment, const char *pszTag);
+    int (*_RTR0MemObjReserveUserTag)(PRTR0MEMOBJ pMemObj, RTR3PTR R3PtrFixed, size_t cb, size_t uAlignment,
+                                     RTR0PROCESS R0Process, const char *pszTag);
+    size_t(*_RTR0MemObjSize)(RTR0MEMOBJ MemObj);
+    RTR0PROCESS(*_RTR0ProcHandleSelf)(void);
+    void (*_RTR0Term)(void);
+    void (*_RTR0TermForced)(void);
+    RTPROCESS(*_RTProcSelf)(void);
+    uint32_t(*_RTSemEventGetResolution)(void);
+    uint32_t(*_RTSemEventMultiGetResolution)(void);
+    int (*_RTSemEventMultiWaitEx)(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout);
+    int (*_RTSemEventMultiWaitExDebug)(RTSEMEVENTMULTI hEventMultiSem, uint32_t fFlags, uint64_t uTimeout,
+                                       RTHCUINTPTR uId, RT_SRC_POS_DECL);
+    int (*_RTSemEventWaitEx)(RTSEMEVENT hEventSem, uint32_t fFlags, uint64_t uTimeout);
+    int (*_RTSemEventWaitExDebug)(RTSEMEVENT hEventSem, uint32_t fFlags, uint64_t uTimeout,
+                                  RTHCUINTPTR uId, RT_SRC_POS_DECL);
+    bool (*_RTThreadIsInInterrupt)(RTTHREAD hThread);
+    void (*_RTThreadPreemptDisable)(PRTTHREADPREEMPTSTATE pState);
+    bool (*_RTThreadPreemptIsEnabled)(RTTHREAD hThread);
+    bool (*_RTThreadPreemptIsPending)(RTTHREAD hThread);
+    bool (*_RTThreadPreemptIsPendingTrusty)(void);
+    bool (*_RTThreadPreemptIsPossible)(void);
+    void (*_RTThreadPreemptRestore)(PRTTHREADPREEMPTSTATE pState);
+    uint32_t(*_RTTimerGetSystemGranularity)(void);
+    int (*_RTTimerReleaseSystemGranularity)(uint32_t u32Granted);
+    int (*_RTTimerRequestSystemGranularity)(uint32_t u32Request, uint32_t *pu32Granted);
+    void (*_RTSpinlockAcquire)(RTSPINLOCK Spinlock);
+    void (*_RTSpinlockRelease)(RTSPINLOCK Spinlock);
+    void* (*_RTMemTmpAllocTag)(size_t cb, const char *pszTag);
+    void (*_RTMemTmpFree)(void *pv);
+    PRTLOGGER(*_RTLogDefaultInstance)(void);
+    PRTLOGGER(*_RTLogDefaultInstanceEx)(uint32_t fFlagsAndGroup);
+    PRTLOGGER(*_RTLogRelGetDefaultInstance)(void);
+    PRTLOGGER(*_RTLogRelGetDefaultInstanceEx)(uint32_t fFlagsAndGroup);
+    int (*_RTErrConvertToErrno)(int iErr);
+    int (*_VGDrvCommonIoCtl)(unsigned iFunction, PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession,
+                             void *pvData, size_t cbData, size_t *pcbDataReturned);
+    int (*_VGDrvCommonCreateUserSession)(PVBOXGUESTDEVEXT pDevExt, uint32_t fRequestor, PVBOXGUESTSESSION *ppSession);
+    void (*_VGDrvCommonCloseSession)(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession);
+    void* (*_VBoxGuestIDCOpen)(uint32_t *pu32Version);
+    int (*_VBoxGuestIDCClose)(void *pvSession);
+    int (*_VBoxGuestIDCCall)(void *pvSession, unsigned iCmd, void *pvData, size_t cbData, size_t *pcbDataReturned);
+    void (*_RTAssertMsg1Weak)(const char *pszExpr, unsigned uLine, const char *pszFile, const char *pszFunction);
+    void (*_RTAssertMsg2Weak)(const char *pszFormat, ...);
+    void (*_RTAssertMsg2WeakV)(const char *pszFormat, va_list va);
+    bool (*_RTAssertShouldPanic)(void);
+    int (*_RTSemFastMutexCreate)(PRTSEMFASTMUTEX phFastMtx);
+    int (*_RTSemFastMutexDestroy)(RTSEMFASTMUTEX hFastMtx);
+    int (*_RTSemFastMutexRelease)(RTSEMFASTMUTEX hFastMtx);
+    int (*_RTSemFastMutexRequest)(RTSEMFASTMUTEX hFastMtx);
+    int (*_RTSemMutexCreate)(PRTSEMMUTEX phFastMtx);
+    int (*_RTSemMutexDestroy)(RTSEMMUTEX hFastMtx);
+    int (*_RTSemMutexRelease)(RTSEMMUTEX hFastMtx);
+    int (*_RTSemMutexRequest)(RTSEMMUTEX hFastMtx, RTMSINTERVAL cMillies);
+    int (*_RTHeapSimpleRelocate)(RTHEAPSIMPLE hHeap, uintptr_t offDelta);
+    int (*_RTHeapOffsetInit)(PRTHEAPOFFSET phHeap, void *pvMemory, size_t cbMemory);
+    int (*_RTHeapSimpleInit)(PRTHEAPSIMPLE pHeap, void *pvMemory, size_t cbMemory);
+    void* (*_RTHeapOffsetAlloc)(RTHEAPOFFSET hHeap, size_t cb, size_t cbAlignment);
+    void* (*_RTHeapSimpleAlloc)(RTHEAPSIMPLE Heap, size_t cb, size_t cbAlignment);
+    void (*_RTHeapOffsetFree)(RTHEAPOFFSET hHeap, void *pv);
+    void (*_RTHeapSimpleFree)(RTHEAPSIMPLE Heap, void *pv);
+};
+
+
+#ifdef IN_VBOXGUEST
+#define g_DevExt (g_VBoxGuest.devExt)
+#define cUsers (g_VBoxGuest._cUsers)
+#define sState (g_VBoxGuest._sState)
+#else
+#define g_DevExt (g_VBoxGuest->devExt)
+#define cUsers (g_VBoxGuest->_cUsers)
+#define sState (g_VBoxGuest->_sState)
+extern struct vboxguest_module_info *g_VBoxGuest;
+#endif
+
+#endif /* !GA_INCLUDED_SRC_common_VBoxGuest_VBoxGuest_haiku_h */
+
diff --git a/src/VBox/Additions/common/VBoxGuest/VBoxGuest-linux.c b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-linux.c
new file mode 100644
index 00000000..538a0bc4
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-linux.c
@@ -0,0 +1,1470 @@
+/* $Id: VBoxGuest-linux.c $ */
+/** @file
+ * VBoxGuest - Linux specifics.
+ *
+ * Note. Unfortunately, the difference between this and SUPDrv-linux.c is
+ *       a little bit too big to be helpful.
+ */
+
+/*
+ * 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 LOG_GROUP LOG_GROUP_SUP_DRV
+
+#include "the-linux-kernel.h"
+
+#if RTLNX_VER_MIN(2,6,15)
+# define VBOXGUEST_WITH_INPUT_DRIVER
+#endif
+
+#if RTLNX_VER_MIN(4,15,0)
+# define CONST_4_15 const
+#else
+# define CONST_4_15
+#endif
+
+#include "VBoxGuestInternal.h"
+#ifdef VBOXGUEST_WITH_INPUT_DRIVER
+# include <linux/input.h>
+#endif
+#include <linux/miscdevice.h>
+#include <linux/poll.h>
+#if RTLNX_VER_MIN(2,6,28)
+# include <linux/tty.h>
+#endif
+#include <VBox/version.h>
+#include "revision-generated.h"
+
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+#include <iprt/ctype.h>
+#include <iprt/initterm.h>
+#include <iprt/mem.h>
+#include <iprt/mp.h>
+#include <iprt/process.h>
+#include <iprt/spinlock.h>
+#include <iprt/semaphore.h>
+#include <iprt/string.h>
+#include <VBox/err.h>
+#include <VBox/log.h>
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+/** The device name. */
+#define DEVICE_NAME             "vboxguest"
+/** The device name for the device node open to everyone. */
+#define DEVICE_NAME_USER        "vboxuser"
+/** The name of the PCI driver */
+#define DRIVER_NAME             DEVICE_NAME
+
+
+/* 2.4.x compatibility macros that may or may not be defined. */
+#ifndef IRQ_RETVAL
+# define irqreturn_t            void
+# define IRQ_RETVAL(n)
+#endif
+
+/* uidgid.h was introduced in 3.5.0. */
+#if RTLNX_VER_MAX(3,5,0)
+# define kgid_t gid_t
+# define kuid_t uid_t
+#endif
+
+#ifdef VBOXGUEST_WITH_INPUT_DRIVER
+/** The name of input pointing device for mouse integration. */
+# define VBOX_INPUT_DEVICE_NAME  "VirtualBox mouse integration"
+#endif
+
+
+/*********************************************************************************************************************************
+*   Internal Functions                                                                                                           *
+*********************************************************************************************************************************/
+static void vgdrvLinuxTermPci(struct pci_dev *pPciDev);
+static int  vgdrvLinuxProbePci(struct pci_dev *pPciDev, const struct pci_device_id *id);
+static int  __init vgdrvLinuxModInit(void);
+static void __exit vgdrvLinuxModExit(void);
+static int  vgdrvLinuxOpen(struct inode *pInode, struct file *pFilp);
+static int  vgdrvLinuxRelease(struct inode *pInode, struct file *pFilp);
+#ifdef HAVE_UNLOCKED_IOCTL
+static long vgdrvLinuxIOCtl(struct file *pFilp, unsigned int uCmd, unsigned long ulArg);
+#else
+static int  vgdrvLinuxIOCtl(struct inode *pInode, struct file *pFilp, unsigned int uCmd, unsigned long ulArg);
+#endif
+static int  vgdrvLinuxIOCtlSlow(struct file *pFilp, unsigned int uCmd, unsigned long ulArg, PVBOXGUESTSESSION pSession);
+static int  vgdrvLinuxFAsync(int fd, struct file *pFile, int fOn);
+static unsigned int vgdrvLinuxPoll(struct file *pFile, poll_table *pPt);
+static ssize_t vgdrvLinuxRead(struct file *pFile, char *pbBuf, size_t cbRead, loff_t *poff);
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/**
+ * Device extention & session data association structure.
+ */
+static VBOXGUESTDEVEXT          g_DevExt;
+/** The PCI device. */
+static struct pci_dev          *g_pPciDev = NULL;
+/** The base of the I/O port range. */
+static RTIOPORT                 g_IOPortBase;
+/** The base of the MMIO range. */
+static RTHCPHYS                 g_MMIOPhysAddr = NIL_RTHCPHYS;
+/** The size of the MMIO range as seen by PCI. */
+static uint32_t                 g_cbMMIO;
+/** The pointer to the mapping of the MMIO range. */
+static void                    *g_pvMMIOBase;
+/** Wait queue used by polling. */
+static wait_queue_head_t        g_PollEventQueue;
+/** Asynchronous notification stuff.  */
+static struct fasync_struct    *g_pFAsyncQueue;
+#ifdef VBOXGUEST_WITH_INPUT_DRIVER
+/** Pre-allocated mouse status VMMDev requests for use in the IRQ handler. */
+static VMMDevReqMouseStatusEx  *g_pMouseStatusReqEx;
+#endif
+#if RTLNX_VER_MIN(2,6,0)
+/** Whether we've create the logger or not. */
+static volatile bool            g_fLoggerCreated;
+/** Release logger group settings. */
+static char                     g_szLogGrp[128];
+/** Release logger flags settings. */
+static char                     g_szLogFlags[128];
+/** Release logger destination settings. */
+static char                     g_szLogDst[128];
+# if 0
+/** Debug logger group settings. */
+static char                     g_szDbgLogGrp[128];
+/** Debug logger flags settings. */
+static char                     g_szDbgLogFlags[128];
+/** Debug logger destination settings. */
+static char                     g_szDbgLogDst[128];
+# endif
+#endif
+
+/** The input device handle */
+#ifdef VBOXGUEST_WITH_INPUT_DRIVER
+static struct input_dev        *g_pInputDevice = NULL;
+#endif
+
+/** The file_operations structure. */
+static struct file_operations   g_FileOps =
+{
+    owner:          THIS_MODULE,
+    open:           vgdrvLinuxOpen,
+    release:        vgdrvLinuxRelease,
+#ifdef HAVE_UNLOCKED_IOCTL
+    unlocked_ioctl: vgdrvLinuxIOCtl,
+#else
+    ioctl:          vgdrvLinuxIOCtl,
+#endif
+    fasync:         vgdrvLinuxFAsync,
+    read:           vgdrvLinuxRead,
+    poll:           vgdrvLinuxPoll,
+    llseek:         no_llseek,
+};
+
+/** The miscdevice structure. */
+static struct miscdevice        g_MiscDevice =
+{
+    minor:          MISC_DYNAMIC_MINOR,
+    name:           DEVICE_NAME,
+    fops:           &g_FileOps,
+};
+
+/** The file_operations structure for the user device.
+ * @remarks For the time being we'll be using the same implementation as
+ *          /dev/vboxguest here. */
+static struct file_operations   g_FileOpsUser =
+{
+    owner:          THIS_MODULE,
+    open:           vgdrvLinuxOpen,
+    release:        vgdrvLinuxRelease,
+#ifdef HAVE_UNLOCKED_IOCTL
+    unlocked_ioctl: vgdrvLinuxIOCtl,
+#else
+    ioctl:          vgdrvLinuxIOCtl,
+#endif
+};
+
+/** The miscdevice structure for the user device. */
+static struct miscdevice        g_MiscDeviceUser =
+{
+    minor:          MISC_DYNAMIC_MINOR,
+    name:           DEVICE_NAME_USER,
+    fops:           &g_FileOpsUser,
+};
+
+
+/** PCI hotplug structure. */
+static const struct pci_device_id g_VBoxGuestPciId[] =
+{
+    {
+        vendor:     VMMDEV_VENDORID,
+        device:     VMMDEV_DEVICEID
+    },
+    {
+        /* empty entry */
+    }
+};
+
+MODULE_DEVICE_TABLE(pci, g_VBoxGuestPciId);
+
+/** Structure for registering the PCI driver. */
+static struct pci_driver  g_PciDriver =
+{
+    name:           DRIVER_NAME,
+    id_table:       g_VBoxGuestPciId,
+    probe:          vgdrvLinuxProbePci,
+    remove:         vgdrvLinuxTermPci
+};
+
+#ifdef VBOXGUEST_WITH_INPUT_DRIVER
+/** Kernel IDC session to ourselves for use with the mouse events. */
+static PVBOXGUESTSESSION        g_pKernelSession = NULL;
+#endif
+
+
+
+/**
+ * Converts a VBox status code to a linux error code.
+ *
+ * @returns corresponding negative linux error code.
+ * @param   rc  supdrv error code (SUPDRV_ERR_* defines).
+ */
+static int vgdrvLinuxConvertToNegErrno(int rc)
+{
+    if (   rc > -1000
+        && rc < 1000)
+        return -RTErrConvertToErrno(rc);
+    switch (rc)
+    {
+        case VERR_HGCM_SERVICE_NOT_FOUND:      return -ESRCH;
+        case VINF_HGCM_CLIENT_REJECTED:        return 0;
+        case VERR_HGCM_INVALID_CMD_ADDRESS:    return -EFAULT;
+        case VINF_HGCM_ASYNC_EXECUTE:          return 0;
+        case VERR_HGCM_INTERNAL:               return -EPROTO;
+        case VERR_HGCM_INVALID_CLIENT_ID:      return -EINVAL;
+        case VINF_HGCM_SAVE_STATE:             return 0;
+        /* No reason to return this to a guest */
+        // case VERR_HGCM_SERVICE_EXISTS:         return -EEXIST;
+        default:
+            AssertMsgFailed(("Unhandled error code %Rrc\n", rc));
+            return -EPROTO;
+    }
+}
+
+
+/**
+ * Does the PCI detection and init of the device.
+ *
+ * @returns 0 on success, negated errno on failure.
+ */
+static int vgdrvLinuxProbePci(struct pci_dev *pPciDev, const struct pci_device_id *id)
+{
+    int rc;
+
+    NOREF(id);
+    AssertReturn(!g_pPciDev, -EINVAL);
+    rc = pci_enable_device(pPciDev);
+    if (rc >= 0)
+    {
+        /* I/O Ports are mandatory, the MMIO bit is not. */
+        g_IOPortBase = pci_resource_start(pPciDev, 0);
+        if (g_IOPortBase != 0)
+        {
+            /*
+             * Map the register address space.
+             */
+            g_MMIOPhysAddr = pci_resource_start(pPciDev, 1);
+            g_cbMMIO       = pci_resource_len(pPciDev, 1);
+            if (request_mem_region(g_MMIOPhysAddr, g_cbMMIO, DEVICE_NAME) != NULL)
+            {
+                g_pvMMIOBase = ioremap(g_MMIOPhysAddr, g_cbMMIO);
+                if (g_pvMMIOBase)
+                {
+                    /** @todo why aren't we requesting ownership of the I/O ports as well? */
+                    g_pPciDev = pPciDev;
+                    return 0;
+                }
+
+                /* failure cleanup path */
+                LogRel((DEVICE_NAME ": ioremap failed; MMIO Addr=%RHp cb=%#x\n", g_MMIOPhysAddr, g_cbMMIO));
+                rc = -ENOMEM;
+                release_mem_region(g_MMIOPhysAddr, g_cbMMIO);
+            }
+            else
+            {
+                LogRel((DEVICE_NAME ": failed to obtain adapter memory\n"));
+                rc = -EBUSY;
+            }
+            g_MMIOPhysAddr = NIL_RTHCPHYS;
+            g_cbMMIO       = 0;
+            g_IOPortBase   = 0;
+        }
+        else
+        {
+            LogRel((DEVICE_NAME ": did not find expected hardware resources\n"));
+            rc = -ENXIO;
+        }
+        pci_disable_device(pPciDev);
+    }
+    else
+        LogRel((DEVICE_NAME ": could not enable device: %d\n", rc));
+    return rc;
+}
+
+
+/**
+ * Clean up the usage of the PCI device.
+ */
+static void vgdrvLinuxTermPci(struct pci_dev *pPciDev)
+{
+    g_pPciDev = NULL;
+    if (pPciDev)
+    {
+        iounmap(g_pvMMIOBase);
+        g_pvMMIOBase = NULL;
+
+        release_mem_region(g_MMIOPhysAddr, g_cbMMIO);
+        g_MMIOPhysAddr = NIL_RTHCPHYS;
+        g_cbMMIO = 0;
+
+        pci_disable_device(pPciDev);
+    }
+}
+
+
+/**
+ * Interrupt service routine.
+ *
+ * @returns In 2.4 it returns void.
+ *          In 2.6 we indicate whether we've handled the IRQ or not.
+ *
+ * @param   iIrq            The IRQ number.
+ * @param   pvDevId         The device ID, a pointer to g_DevExt.
+ * @param   pRegs           Register set. Removed in 2.6.19.
+ */
+#if RTLNX_VER_MIN(2,6,19) && !defined(DOXYGEN_RUNNING)
+static irqreturn_t vgdrvLinuxISR(int iIrq, void *pvDevId)
+#else
+static irqreturn_t vgdrvLinuxISR(int iIrq, void *pvDevId, struct pt_regs *pRegs)
+#endif
+{
+    bool fTaken = VGDrvCommonISR(&g_DevExt);
+    return IRQ_RETVAL(fTaken);
+}
+
+
+/**
+ * Registers the ISR and initializes the poll wait queue.
+ */
+static int __init vgdrvLinuxInitISR(void)
+{
+    int rc;
+
+    init_waitqueue_head(&g_PollEventQueue);
+    rc = request_irq(g_pPciDev->irq,
+                     vgdrvLinuxISR,
+#if RTLNX_VER_MIN(2,6,20)
+                     IRQF_SHARED,
+#else
+                     SA_SHIRQ,
+#endif
+                     DEVICE_NAME,
+                     &g_DevExt);
+    if (rc)
+    {
+        LogRel((DEVICE_NAME ": could not request IRQ %d: err=%d\n", g_pPciDev->irq, rc));
+        return rc;
+    }
+    return 0;
+}
+
+
+/**
+ * Deregisters the ISR.
+ */
+static void vgdrvLinuxTermISR(void)
+{
+    free_irq(g_pPciDev->irq, &g_DevExt);
+}
+
+
+#ifdef VBOXGUEST_WITH_INPUT_DRIVER
+/**
+ * Check if extended mouse pointer state request protocol is currently used by driver.
+ *
+ * @returns True if extended protocol is used, False otherwise.
+ */
+static bool vgdrvLinuxUsesMouseStatusEx(void)
+{
+    return g_pMouseStatusReqEx->Core.header.requestType == VMMDevReq_GetMouseStatusEx;
+}
+
+/**
+ * Reports the mouse integration status to the host.
+ *
+ * Calls the kernel IOCtl to report mouse status to the host on behalf of
+ * our kernel session.
+ *
+ * @param   fStatus     The mouse status to report.
+ */
+static int vgdrvLinuxSetMouseStatus(uint32_t fStatus)
+{
+    int rc;
+    VBGLIOCSETMOUSESTATUS Req;
+    VBGLREQHDR_INIT(&Req.Hdr, SET_MOUSE_STATUS);
+    Req.u.In.fStatus = fStatus;
+    rc = VGDrvCommonIoCtl(VBGL_IOCTL_SET_MOUSE_STATUS, &g_DevExt, g_pKernelSession, &Req.Hdr, sizeof(Req));
+    if (RT_SUCCESS(rc))
+        rc = Req.Hdr.rc;
+    return rc;
+}
+
+
+/**
+ * Called when the input device is first opened.
+ *
+ * Sets up absolute mouse reporting.
+ */
+static int vboxguestOpenInputDevice(struct input_dev *pDev)
+{
+    int rc = vgdrvLinuxSetMouseStatus(  VMMDEV_MOUSE_GUEST_CAN_ABSOLUTE
+                                      | VMMDEV_MOUSE_NEW_PROTOCOL
+                                      | (vgdrvLinuxUsesMouseStatusEx() ? VMMDEV_MOUSE_GUEST_USES_FULL_STATE_PROTOCOL : 0));
+    if (RT_FAILURE(rc))
+        return ENODEV;
+    NOREF(pDev);
+    return 0;
+}
+
+
+/**
+ * Called if all open handles to the input device are closed.
+ *
+ * Disables absolute reporting.
+ */
+static void vboxguestCloseInputDevice(struct input_dev *pDev)
+{
+    NOREF(pDev);
+    vgdrvLinuxSetMouseStatus(0);
+}
+
+
+/**
+ * Free corresponding mouse status request structure.
+ */
+static void vgdrvLinuxFreeMouseStatusReq(void)
+{
+    VbglR0GRFree(&g_pMouseStatusReqEx->Core.header);
+    g_pMouseStatusReqEx = NULL;
+}
+
+/**
+ * Creates the kernel input device.
+ */
+static int __init vgdrvLinuxCreateInputDevice(void)
+{
+    /* Try to allocate legacy request data first, and check if host supports extended protocol. */
+    int rc = VbglR0GRAlloc((VMMDevRequestHeader **)&g_pMouseStatusReqEx, sizeof(VMMDevReqMouseStatus), VMMDevReq_GetMouseStatus);
+    if (RT_SUCCESS(rc))
+    {
+        /* Check if host supports extended mouse state reporting. */
+        g_pMouseStatusReqEx->Core.mouseFeatures = 0;
+        rc = VbglR0GRPerform(&g_pMouseStatusReqEx->Core.header);
+        if (RT_SUCCESS(rc))
+        {
+            if (g_pMouseStatusReqEx->Core.mouseFeatures & VMMDEV_MOUSE_HOST_USES_FULL_STATE_PROTOCOL)
+            {
+                VMMDevReqMouseStatusEx *pReqEx = NULL;
+                rc = VbglR0GRAlloc((VMMDevRequestHeader **)&pReqEx, sizeof(*pReqEx), VMMDevReq_GetMouseStatusEx);
+                if (RT_SUCCESS(rc))
+                {
+                    /* De-allocate legacy request data, */
+                    VbglR0GRFree(&g_pMouseStatusReqEx->Core.header);
+                    /* ..and switch to extended requests. */
+                    g_pMouseStatusReqEx = pReqEx;
+                    LogRel(("Host supports full mouse state reporting, switching to extended mouse integration protocol\n"));
+                }
+                else
+                    LogRel(("Host supports full mouse state reporting, but feature cannot be initialized, switching to legacy mouse integration protocol\n"));
+            }
+            else
+                LogRel(("Host does not support full mouse state reporting, switching to legacy mouse integration protocol\n"));
+        }
+        else
+            LogRel(("Unable to get host mouse capabilities, switching to legacy mouse integration protocol\n"));
+    }
+    else
+        rc = -ENOMEM;
+
+    if (RT_SUCCESS(rc))
+    {
+        g_pInputDevice = input_allocate_device();
+        if (g_pInputDevice)
+        {
+            g_pInputDevice->name       = VBOX_INPUT_DEVICE_NAME;
+            g_pInputDevice->id.bustype = BUS_PCI;
+            g_pInputDevice->id.vendor  = VMMDEV_VENDORID;
+            g_pInputDevice->id.product = VMMDEV_DEVICEID;
+            g_pInputDevice->id.version = VBOX_SHORT_VERSION;
+            g_pInputDevice->open       = vboxguestOpenInputDevice;
+            g_pInputDevice->close      = vboxguestCloseInputDevice;
+# if RTLNX_VER_MAX(2,6,22)
+            g_pInputDevice->cdev.dev   = &g_pPciDev->dev;
+# else
+            g_pInputDevice->dev.parent = &g_pPciDev->dev;
+# endif
+            /* Set up input device capabilities. */
+            ASMBitSet(g_pInputDevice->evbit, EV_ABS);
+            ASMBitSet(g_pInputDevice->evbit, EV_KEY);
+# ifdef EV_SYN
+            ASMBitSet(g_pInputDevice->evbit, EV_SYN);
+# endif
+            ASMBitSet(g_pInputDevice->absbit, ABS_X);
+            ASMBitSet(g_pInputDevice->absbit, ABS_Y);
+
+            input_set_abs_params(g_pInputDevice, ABS_X, VMMDEV_MOUSE_RANGE_MIN, VMMDEV_MOUSE_RANGE_MAX, 0, 0);
+            input_set_abs_params(g_pInputDevice, ABS_Y, VMMDEV_MOUSE_RANGE_MIN, VMMDEV_MOUSE_RANGE_MAX, 0, 0);
+
+            ASMBitSet(g_pInputDevice->keybit, BTN_MOUSE);
+
+            /* Report extra capabilities to input layer if extended mouse state protocol
+             * will be used in communication with host. */
+            if (vgdrvLinuxUsesMouseStatusEx())
+            {
+                ASMBitSet(g_pInputDevice->evbit, EV_REL);
+                ASMBitSet(g_pInputDevice->evbit, EV_KEY);
+
+                ASMBitSet(g_pInputDevice->relbit, REL_WHEEL);
+                ASMBitSet(g_pInputDevice->relbit, REL_HWHEEL);
+
+                ASMBitSet(g_pInputDevice->keybit, BTN_LEFT);
+                ASMBitSet(g_pInputDevice->keybit, BTN_RIGHT);
+                ASMBitSet(g_pInputDevice->keybit, BTN_MIDDLE);
+                ASMBitSet(g_pInputDevice->keybit, BTN_SIDE);
+                ASMBitSet(g_pInputDevice->keybit, BTN_EXTRA);
+            }
+
+            rc = input_register_device(g_pInputDevice);
+            if (rc == 0)
+                return 0;
+
+            input_free_device(g_pInputDevice);
+        }
+        else
+            rc = -ENOMEM;
+
+        vgdrvLinuxFreeMouseStatusReq();
+    }
+
+    return rc;
+}
+
+
+/**
+ * Terminates the kernel input device.
+ */
+static void vgdrvLinuxTermInputDevice(void)
+{
+    /* Notify host that mouse integration is no longer available. */
+    vgdrvLinuxSetMouseStatus(0);
+
+    vgdrvLinuxFreeMouseStatusReq();
+
+    /* See documentation of input_register_device(): input_free_device()
+     * should not be called after a device has been registered. */
+    input_unregister_device(g_pInputDevice);
+}
+
+#endif /* VBOXGUEST_WITH_INPUT_DRIVER */
+
+/**
+ * Creates the device nodes.
+ *
+ * @returns 0 on success, negated errno on failure.
+ */
+static int __init vgdrvLinuxInitDeviceNodes(void)
+{
+    /*
+     * The full feature device node.
+     */
+    int rc = misc_register(&g_MiscDevice);
+    if (!rc)
+    {
+        /*
+         * The device node intended to be accessible by all users.
+         */
+        rc = misc_register(&g_MiscDeviceUser);
+        if (!rc)
+            return 0;
+        LogRel((DEVICE_NAME ": misc_register failed for %s (rc=%d)\n", DEVICE_NAME_USER, rc));
+        misc_deregister(&g_MiscDevice);
+    }
+    else
+        LogRel((DEVICE_NAME ": misc_register failed for %s (rc=%d)\n", DEVICE_NAME, rc));
+    return rc;
+}
+
+
+/**
+ * Deregisters the device nodes.
+ */
+static void vgdrvLinuxTermDeviceNodes(void)
+{
+    misc_deregister(&g_MiscDevice);
+    misc_deregister(&g_MiscDeviceUser);
+}
+
+
+/**
+ * Initialize module.
+ *
+ * @returns appropriate status code.
+ */
+static int __init vgdrvLinuxModInit(void)
+{
+    static const char * const   s_apszGroups[] = VBOX_LOGGROUP_NAMES;
+    PRTLOGGER                   pRelLogger;
+    int                         rc;
+
+    /*
+     * Initialize IPRT first.
+     */
+    rc = RTR0Init(0);
+    if (RT_FAILURE(rc))
+    {
+        printk(KERN_ERR DEVICE_NAME ": RTR0Init failed, rc=%d.\n", rc);
+        return -EINVAL;
+    }
+
+    /*
+     * Create the release log.
+     * (We do that here instead of common code because we want to log
+     * early failures using the LogRel macro.)
+     */
+    rc = RTLogCreate(&pRelLogger, 0 /* fFlags */, "all",
+                     "VBOX_RELEASE_LOG", RT_ELEMENTS(s_apszGroups), s_apszGroups,
+                     RTLOGDEST_STDOUT | RTLOGDEST_DEBUGGER | RTLOGDEST_USER, NULL);
+    if (RT_SUCCESS(rc))
+    {
+#if RTLNX_VER_MIN(2,6,0)
+        RTLogGroupSettings(pRelLogger, g_szLogGrp);
+        RTLogFlags(pRelLogger, g_szLogFlags);
+        RTLogDestinations(pRelLogger, g_szLogDst);
+#endif
+        RTLogRelSetDefaultInstance(pRelLogger);
+    }
+#if RTLNX_VER_MIN(2,6,0)
+    g_fLoggerCreated = true;
+#endif
+
+    /*
+     * Locate and initialize the PCI device.
+     */
+    rc = pci_register_driver(&g_PciDriver);
+    if (rc >= 0 && g_pPciDev)
+    {
+        /*
+         * Call the common device extension initializer.
+         */
+#if RTLNX_VER_MIN(2,6,0) && defined(RT_ARCH_X86)
+        VBOXOSTYPE enmOSType = VBOXOSTYPE_Linux26;
+#elif RTLNX_VER_MIN(2,6,0) && defined(RT_ARCH_AMD64)
+        VBOXOSTYPE enmOSType = VBOXOSTYPE_Linux26_x64;
+#elif RTLNX_VER_MIN(2,4,0) && defined(RT_ARCH_X86)
+        VBOXOSTYPE enmOSType = VBOXOSTYPE_Linux24;
+#elif RTLNX_VER_MIN(2,4,0) && defined(RT_ARCH_AMD64)
+        VBOXOSTYPE enmOSType = VBOXOSTYPE_Linux24_x64;
+#else
+# warning "huh? which arch + version is this?"
+        VBOXOSTYPE enmOsType = VBOXOSTYPE_Linux;
+#endif
+        rc = VGDrvCommonInitDevExt(&g_DevExt,
+                                   g_IOPortBase,
+                                   g_pvMMIOBase,
+                                   g_cbMMIO,
+                                   enmOSType,
+                                   VMMDEV_EVENT_MOUSE_POSITION_CHANGED);
+        if (RT_SUCCESS(rc))
+        {
+            /*
+             * Register the interrupt service routine for it now that g_DevExt can handle IRQs.
+             */
+            rc = vgdrvLinuxInitISR();
+            if (rc >= 0) /** @todo r=bird: status check differs from that inside vgdrvLinuxInitISR. */
+            {
+#ifdef VBOXGUEST_WITH_INPUT_DRIVER
+                /*
+                 * Create the kernel session for this driver.
+                 */
+                rc = VGDrvCommonCreateKernelSession(&g_DevExt, &g_pKernelSession);
+                if (RT_SUCCESS(rc))
+                {
+                    /*
+                     * Create the kernel input device.
+                     */
+                    rc = vgdrvLinuxCreateInputDevice();
+                    if (rc >= 0)
+                    {
+#endif
+                        /*
+                         * Read host configuration.
+                         */
+                        VGDrvCommonProcessOptionsFromHost(&g_DevExt);
+
+                        /*
+                         * Finally, create the device nodes.
+                         */
+                        rc = vgdrvLinuxInitDeviceNodes();
+                        if (rc >= 0)
+                        {
+                            /* some useful information for the user but don't show this on the console */
+                            LogRel((DEVICE_NAME ": Successfully loaded version " VBOX_VERSION_STRING " r" __stringify(VBOX_SVN_REV) "\n"));
+                            LogRel((DEVICE_NAME ": misc device minor %d, IRQ %d, I/O port %RTiop, MMIO at %RHp (size 0x%x)\n",
+                                    g_MiscDevice.minor, g_pPciDev->irq, g_IOPortBase, g_MMIOPhysAddr, g_cbMMIO));
+                            printk(KERN_DEBUG DEVICE_NAME ": Successfully loaded version "
+                                   VBOX_VERSION_STRING " r" __stringify(VBOX_SVN_REV) " (interface " RT_XSTR(VMMDEV_VERSION) ")\n");
+                            return rc;
+                        }
+
+                        /* bail out */
+#ifdef VBOXGUEST_WITH_INPUT_DRIVER
+                        vgdrvLinuxTermInputDevice();
+                    }
+                    else
+                    {
+                        LogRel((DEVICE_NAME ": vboxguestCreateInputDevice failed with rc=%Rrc\n", rc));
+                        rc = RTErrConvertFromErrno(rc);
+                    }
+                    VGDrvCommonCloseSession(&g_DevExt, g_pKernelSession);
+                }
+#endif
+                vgdrvLinuxTermISR();
+            }
+            VGDrvCommonDeleteDevExt(&g_DevExt);
+        }
+        else
+        {
+            LogRel((DEVICE_NAME ": VGDrvCommonInitDevExt failed with rc=%Rrc\n", rc));
+            rc = RTErrConvertFromErrno(rc);
+        }
+    }
+    else
+    {
+        LogRel((DEVICE_NAME ": PCI device not found, probably running on physical hardware.\n"));
+        rc = -ENODEV;
+    }
+    pci_unregister_driver(&g_PciDriver);
+    RTLogDestroy(RTLogRelSetDefaultInstance(NULL));
+    RTLogDestroy(RTLogSetDefaultInstance(NULL));
+    RTR0Term();
+    return rc;
+}
+
+
+/**
+ * Unload the module.
+ */
+static void __exit vgdrvLinuxModExit(void)
+{
+    /*
+     * Inverse order of init.
+     */
+    vgdrvLinuxTermDeviceNodes();
+#ifdef VBOXGUEST_WITH_INPUT_DRIVER
+    vgdrvLinuxTermInputDevice();
+    VGDrvCommonCloseSession(&g_DevExt, g_pKernelSession);
+#endif
+    vgdrvLinuxTermISR();
+    VGDrvCommonDeleteDevExt(&g_DevExt);
+    pci_unregister_driver(&g_PciDriver);
+    RTLogDestroy(RTLogRelSetDefaultInstance(NULL));
+    RTLogDestroy(RTLogSetDefaultInstance(NULL));
+    RTR0Term();
+}
+
+
+/**
+ * Get the process user ID.
+ *
+ * @returns UID.
+ */
+DECLINLINE(RTUID) vgdrvLinuxGetUid(void)
+{
+#if RTLNX_VER_MIN(2,6,29)
+# if RTLNX_VER_MIN(3,5,0)
+    return from_kuid(current_user_ns(), current->cred->uid);
+# else
+    return current->cred->uid;
+# endif
+#else
+    return current->uid;
+#endif
+}
+
+
+/**
+ * Checks if the given group number is zero or not.
+ *
+ * @returns true / false.
+ * @param   gid                 The group to check for.
+ */
+DECLINLINE(bool) vgdrvLinuxIsGroupZero(kgid_t gid)
+{
+#if RTLNX_VER_MIN(3,5,0)
+    return from_kgid(current_user_ns(), gid);
+#else
+    return gid == 0;
+#endif
+}
+
+
+/**
+ * Searches the effective group and supplementary groups for @a gid.
+ *
+ * @returns true if member, false if not.
+ * @param   gid                 The group to check for.
+ */
+DECLINLINE(RTGID) vgdrvLinuxIsInGroupEff(kgid_t gid)
+{
+    return in_egroup_p(gid) != 0;
+}
+
+
+/**
+ * Check if we can positively or negatively determine that the process is
+ * running under a login on the physical machine console.
+ *
+ * Havne't found a good way to figure this out for graphical sessions, so this
+ * is mostly pointless.  But let us try do what we can do.
+ *
+ * @returns VMMDEV_REQUESTOR_CON_XXX.
+ */
+static uint32_t vgdrvLinuxRequestorOnConsole(void)
+{
+    uint32_t           fRet = VMMDEV_REQUESTOR_CON_DONT_KNOW;
+
+#if RTLNX_VER_MIN(2,6,28) /* First with tty_kref_put(). */
+    /*
+     * Check for tty0..63, ASSUMING that these are only used for the physical console.
+     */
+    struct tty_struct *pTty = get_current_tty();
+    if (pTty)
+    {
+# if RTLNX_VER_MIN(4,2,0)
+        const char *pszName = tty_name(pTty);
+# else
+        char szBuf[64];
+        const char *pszName = tty_name(pTty, szBuf);
+# endif
+        if (   pszName
+            && pszName[0] == 't'
+            && pszName[1] == 't'
+            && pszName[2] == 'y'
+            && RT_C_IS_DIGIT(pszName[3])
+            && (   pszName[4] == '\0'
+                || (   RT_C_IS_DIGIT(pszName[4])
+                    && pszName[5] == '\0'
+                    && (pszName[3] - '0') * 10 + (pszName[4] - '0') <= 63)) )
+               fRet = VMMDEV_REQUESTOR_CON_YES;
+        tty_kref_put(pTty);
+    }
+#endif
+
+    return fRet;
+}
+
+
+/**
+ * Device open. Called on open /dev/vboxdrv
+ *
+ * @param   pInode      Pointer to inode info structure.
+ * @param   pFilp       Associated file pointer.
+ */
+static int vgdrvLinuxOpen(struct inode *pInode, struct file *pFilp)
+{
+    int                 rc;
+    PVBOXGUESTSESSION   pSession;
+    uint32_t            fRequestor;
+    Log((DEVICE_NAME ": pFilp=%p pid=%d/%d %s\n", pFilp, RTProcSelf(), current->pid, current->comm));
+
+    /*
+     * Figure out the requestor flags.
+     * ASSUMES that the gid of /dev/vboxuser is what we should consider the special vbox group.
+     */
+    fRequestor = VMMDEV_REQUESTOR_USERMODE | VMMDEV_REQUESTOR_TRUST_NOT_GIVEN;
+    if (vgdrvLinuxGetUid() == 0)
+        fRequestor |= VMMDEV_REQUESTOR_USR_ROOT;
+    else
+        fRequestor |= VMMDEV_REQUESTOR_USR_USER;
+    if (MINOR(pInode->i_rdev) == g_MiscDeviceUser.minor)
+    {
+        fRequestor |= VMMDEV_REQUESTOR_USER_DEVICE;
+        if (!vgdrvLinuxIsGroupZero(pInode->i_gid) && vgdrvLinuxIsInGroupEff(pInode->i_gid))
+            fRequestor |= VMMDEV_REQUESTOR_GRP_VBOX;
+    }
+    fRequestor |= vgdrvLinuxRequestorOnConsole();
+
+    /*
+     * Call common code to create the user session. Associate it with
+     * the file so we can access it in the other methods.
+     */
+    rc = VGDrvCommonCreateUserSession(&g_DevExt, fRequestor, &pSession);
+    if (RT_SUCCESS(rc))
+        pFilp->private_data = pSession;
+
+    Log(("vgdrvLinuxOpen: g_DevExt=%p pSession=%p rc=%d/%d (pid=%d/%d %s)\n",
+         &g_DevExt, pSession, rc, vgdrvLinuxConvertToNegErrno(rc), RTProcSelf(), current->pid, current->comm));
+    return vgdrvLinuxConvertToNegErrno(rc);
+}
+
+
+/**
+ * Close device.
+ *
+ * @param   pInode      Pointer to inode info structure.
+ * @param   pFilp       Associated file pointer.
+ */
+static int vgdrvLinuxRelease(struct inode *pInode, struct file *pFilp)
+{
+    Log(("vgdrvLinuxRelease: pFilp=%p pSession=%p pid=%d/%d %s\n",
+         pFilp, pFilp->private_data, RTProcSelf(), current->pid, current->comm));
+
+#if RTLNX_VER_MAX(2,6,28)
+    /* This housekeeping was needed in older kernel versions to ensure that
+     * the file pointer didn't get left on the polling queue. */
+    vgdrvLinuxFAsync(-1, pFilp, 0);
+#endif
+    VGDrvCommonCloseSession(&g_DevExt, (PVBOXGUESTSESSION)pFilp->private_data);
+    pFilp->private_data = NULL;
+    return 0;
+}
+
+
+/**
+ * Device I/O Control entry point.
+ *
+ * @param   pFilp       Associated file pointer.
+ * @param   uCmd        The function specified to ioctl().
+ * @param   ulArg       The argument specified to ioctl().
+ */
+#if defined(HAVE_UNLOCKED_IOCTL) || defined(DOXYGEN_RUNNING)
+static long vgdrvLinuxIOCtl(struct file *pFilp, unsigned int uCmd, unsigned long ulArg)
+#else
+static int vgdrvLinuxIOCtl(struct inode *pInode, struct file *pFilp, unsigned int uCmd, unsigned long ulArg)
+#endif
+{
+    PVBOXGUESTSESSION pSession = (PVBOXGUESTSESSION)pFilp->private_data;
+    int rc;
+#ifndef HAVE_UNLOCKED_IOCTL
+    unlock_kernel();
+#endif
+
+#if 0 /* no fast I/O controls defined atm. */
+    if (RT_LIKELY(   (   uCmd == SUP_IOCTL_FAST_DO_RAW_RUN
+                      || uCmd == SUP_IOCTL_FAST_DO_HM_RUN
+                      || uCmd == SUP_IOCTL_FAST_DO_NOP)
+                  && pSession->fUnrestricted == true))
+        rc = VGDrvCommonIoCtlFast(uCmd, ulArg, &g_DevExt, pSession);
+    else
+#endif
+        rc = vgdrvLinuxIOCtlSlow(pFilp, uCmd, ulArg, pSession);
+
+#ifndef HAVE_UNLOCKED_IOCTL
+    lock_kernel();
+#endif
+    return rc;
+}
+
+
+/**
+ * Device I/O Control entry point, slow variant.
+ *
+ * @param   pFilp       Associated file pointer.
+ * @param   uCmd        The function specified to ioctl().
+ * @param   ulArg       The argument specified to ioctl().
+ * @param   pSession    The session instance.
+ */
+static int vgdrvLinuxIOCtlSlow(struct file *pFilp, unsigned int uCmd, unsigned long ulArg, PVBOXGUESTSESSION pSession)
+{
+    int                 rc;
+    VBGLREQHDR          Hdr;
+    PVBGLREQHDR         pHdr;
+    uint32_t            cbBuf;
+
+    Log6(("vgdrvLinuxIOCtlSlow: pFilp=%p uCmd=%#x ulArg=%p pid=%d/%d\n", pFilp, uCmd, (void *)ulArg, RTProcSelf(), current->pid));
+
+    /*
+     * Read the header.
+     */
+    if (RT_FAILURE(RTR0MemUserCopyFrom(&Hdr, ulArg, sizeof(Hdr))))
+    {
+        Log(("vgdrvLinuxIOCtlSlow: copy_from_user(,%#lx,) failed; uCmd=%#x\n", ulArg, uCmd));
+        return -EFAULT;
+    }
+    if (RT_UNLIKELY(Hdr.uVersion != VBGLREQHDR_VERSION))
+    {
+        Log(("vgdrvLinuxIOCtlSlow: bad header version %#x; uCmd=%#x\n", Hdr.uVersion, uCmd));
+        return -EINVAL;
+    }
+
+    /*
+     * Buffer the request.
+     * Note! The header is revalidated by the common code.
+     */
+    cbBuf = RT_MAX(Hdr.cbIn, Hdr.cbOut);
+    if (RT_UNLIKELY(cbBuf > _1M*16))
+    {
+        Log(("vgdrvLinuxIOCtlSlow: too big cbBuf=%#x; uCmd=%#x\n", cbBuf, uCmd));
+        return -E2BIG;
+    }
+    if (RT_UNLIKELY(   Hdr.cbIn < sizeof(Hdr)
+                    || (cbBuf != _IOC_SIZE(uCmd) && _IOC_SIZE(uCmd) != 0)))
+    {
+        Log(("vgdrvLinuxIOCtlSlow: bad ioctl cbBuf=%#x _IOC_SIZE=%#x; uCmd=%#x\n", cbBuf, _IOC_SIZE(uCmd), uCmd));
+        return -EINVAL;
+    }
+    pHdr = RTMemAlloc(cbBuf);
+    if (RT_UNLIKELY(!pHdr))
+    {
+        LogRel(("vgdrvLinuxIOCtlSlow: failed to allocate buffer of %d bytes for uCmd=%#x\n", cbBuf, uCmd));
+        return -ENOMEM;
+    }
+    if (RT_FAILURE(RTR0MemUserCopyFrom(pHdr, ulArg, Hdr.cbIn)))
+    {
+        Log(("vgdrvLinuxIOCtlSlow: copy_from_user(,%#lx, %#x) failed; uCmd=%#x\n", ulArg, Hdr.cbIn, uCmd));
+        RTMemFree(pHdr);
+        return -EFAULT;
+    }
+    if (Hdr.cbIn < cbBuf)
+        RT_BZERO((uint8_t *)pHdr + Hdr.cbIn, cbBuf - Hdr.cbIn);
+
+    /*
+     * Process the IOCtl.
+     */
+    rc = VGDrvCommonIoCtl(uCmd, &g_DevExt, pSession, pHdr, cbBuf);
+
+    /*
+     * Copy ioctl data and output buffer back to user space.
+     */
+    if (RT_SUCCESS(rc))
+    {
+        uint32_t cbOut = pHdr->cbOut;
+        if (RT_UNLIKELY(cbOut > cbBuf))
+        {
+            LogRel(("vgdrvLinuxIOCtlSlow: too much output! %#x > %#x; uCmd=%#x!\n", cbOut, cbBuf, uCmd));
+            cbOut = cbBuf;
+        }
+        if (RT_FAILURE(RTR0MemUserCopyTo(ulArg, pHdr, cbOut)))
+        {
+            /* this is really bad! */
+            LogRel(("vgdrvLinuxIOCtlSlow: copy_to_user(%#lx,,%#x); uCmd=%#x!\n", ulArg, cbOut, uCmd));
+            rc = -EFAULT;
+        }
+    }
+    else
+    {
+        Log(("vgdrvLinuxIOCtlSlow: pFilp=%p uCmd=%#x ulArg=%p failed, rc=%d\n", pFilp, uCmd, (void *)ulArg, rc));
+        rc = -EINVAL;
+    }
+    RTMemFree(pHdr);
+
+    Log6(("vgdrvLinuxIOCtlSlow: returns %d (pid=%d/%d)\n", rc, RTProcSelf(), current->pid));
+    return rc;
+}
+
+
+/**
+ * @note This code is duplicated on other platforms with variations, so please
+ *       keep them all up to date when making changes!
+ */
+int VBOXCALL VBoxGuestIDC(void *pvSession, uintptr_t uReq, PVBGLREQHDR pReqHdr, size_t cbReq)
+{
+    /*
+     * Simple request validation (common code does the rest).
+     */
+    int rc;
+    if (   RT_VALID_PTR(pReqHdr)
+        && cbReq >= sizeof(*pReqHdr))
+    {
+        /*
+         * All requests except the connect one requires a valid session.
+         */
+        PVBOXGUESTSESSION pSession = (PVBOXGUESTSESSION)pvSession;
+        if (pSession)
+        {
+            if (   RT_VALID_PTR(pSession)
+                && pSession->pDevExt == &g_DevExt)
+                rc = VGDrvCommonIoCtl(uReq, &g_DevExt, pSession, pReqHdr, cbReq);
+            else
+                rc = VERR_INVALID_HANDLE;
+        }
+        else if (uReq == VBGL_IOCTL_IDC_CONNECT)
+        {
+            rc = VGDrvCommonCreateKernelSession(&g_DevExt, &pSession);
+            if (RT_SUCCESS(rc))
+            {
+                rc = VGDrvCommonIoCtl(uReq, &g_DevExt, pSession, pReqHdr, cbReq);
+                if (RT_FAILURE(rc))
+                    VGDrvCommonCloseSession(&g_DevExt, pSession);
+            }
+        }
+        else
+            rc = VERR_INVALID_HANDLE;
+    }
+    else
+        rc = VERR_INVALID_POINTER;
+    return rc;
+}
+EXPORT_SYMBOL(VBoxGuestIDC);
+
+
+/**
+ * Asynchronous notification activation method.
+ *
+ * @returns 0 on success, negative errno on failure.
+ *
+ * @param   fd          The file descriptor.
+ * @param   pFile       The file structure.
+ * @param   fOn         On/off indicator.
+ */
+static int vgdrvLinuxFAsync(int fd, struct file *pFile, int fOn)
+{
+    return fasync_helper(fd, pFile, fOn, &g_pFAsyncQueue);
+}
+
+
+/**
+ * Poll function.
+ *
+ * This returns ready to read if the mouse pointer mode or the pointer position
+ * has changed since last call to read.
+ *
+ * @returns 0 if no changes, POLLIN | POLLRDNORM if there are unseen changes.
+ *
+ * @param   pFile       The file structure.
+ * @param   pPt         The poll table.
+ *
+ * @remarks This is probably not really used, X11 is said to use the fasync
+ *          interface instead.
+ */
+static unsigned int vgdrvLinuxPoll(struct file *pFile, poll_table *pPt)
+{
+    PVBOXGUESTSESSION   pSession  = (PVBOXGUESTSESSION)pFile->private_data;
+    uint32_t            u32CurSeq = ASMAtomicUoReadU32(&g_DevExt.u32MousePosChangedSeq);
+    unsigned int        fMask     = pSession->u32MousePosChangedSeq != u32CurSeq
+                                  ? POLLIN | POLLRDNORM
+                                  : 0;
+    poll_wait(pFile, &g_PollEventQueue, pPt);
+    return fMask;
+}
+
+
+/**
+ * Read to go with our poll/fasync response.
+ *
+ * @returns 1 or -EINVAL.
+ *
+ * @param   pFile       The file structure.
+ * @param   pbBuf       The buffer to read into.
+ * @param   cbRead      The max number of bytes to read.
+ * @param   poff        The current file position.
+ *
+ * @remarks This is probably not really used as X11 lets the driver do its own
+ *          event reading. The poll condition is therefore also cleared when we
+ *          see VMMDevReq_GetMouseStatus in vgdrvIoCtl_VMMRequest.
+ */
+static ssize_t vgdrvLinuxRead(struct file *pFile, char *pbBuf, size_t cbRead, loff_t *poff)
+{
+    PVBOXGUESTSESSION   pSession  = (PVBOXGUESTSESSION)pFile->private_data;
+    uint32_t            u32CurSeq = ASMAtomicUoReadU32(&g_DevExt.u32MousePosChangedSeq);
+
+    if (*poff != 0)
+        return -EINVAL;
+
+    /*
+     * Fake a single byte read if we're not up to date with the current mouse position.
+     */
+    if (    pSession->u32MousePosChangedSeq != u32CurSeq
+        &&  cbRead > 0)
+    {
+        pSession->u32MousePosChangedSeq = u32CurSeq;
+        pbBuf[0] = 0;
+        return 1;
+    }
+    return 0;
+}
+
+
+#ifdef VBOXGUEST_WITH_INPUT_DRIVER
+/**
+ * Get host mouse state.
+ *
+ * @returns                 IPRT status code.
+ * @param pfMouseFeatures   Where to store host mouse capabilities.
+ * @param pX                Where to store X axis coordinate.
+ * @param pY                Where to store Y axis coordinate.
+ * @param pDz               Where to store vertical wheel movement offset (only set if in case of VMMDevReq_GetMouseStatusEx request).
+ * @param pDw               Where to store horizontal wheel movement offset (only set if in case of VMMDevReq_GetMouseStatusEx request).
+ * @param pfButtons         Where to store mouse buttons state (only set if in case of VMMDevReq_GetMouseStatusEx request).
+ */
+static int vgdrvLinuxGetHostMouseState(uint32_t *pfMouseFeatures, int32_t *pX, int32_t *pY, int32_t *pDz, int32_t *pDw, uint32_t *pfButtons)
+{
+    int rc = VERR_INVALID_PARAMETER;
+
+    Assert(pfMouseFeatures);
+    Assert(pX);
+    Assert(pY);
+    Assert(pDz);
+    Assert(pDw);
+    Assert(pfButtons);
+
+    /* Initialize legacy request data. */
+    g_pMouseStatusReqEx->Core.mouseFeatures = 0;
+    g_pMouseStatusReqEx->Core.pointerXPos = 0;
+    g_pMouseStatusReqEx->Core.pointerYPos = 0;
+
+    /* Initialize extended request data if VMMDevReq_GetMouseStatusEx is used. */
+    if (vgdrvLinuxUsesMouseStatusEx())
+    {
+        g_pMouseStatusReqEx->dz = 0;
+        g_pMouseStatusReqEx->dw = 0;
+        g_pMouseStatusReqEx->fButtons = 0;
+    }
+
+    /* Get host mouse state - either lagacy or extended version. */
+    rc = VbglR0GRPerform(&g_pMouseStatusReqEx->Core.header);
+    if (RT_SUCCESS(rc))
+    {
+        *pfMouseFeatures = g_pMouseStatusReqEx->Core.mouseFeatures;
+        *pX = g_pMouseStatusReqEx->Core.pointerXPos;
+        *pY = g_pMouseStatusReqEx->Core.pointerYPos;
+
+        /* Get extended mouse state data in case of VMMDevReq_GetMouseStatusEx. */
+        if (vgdrvLinuxUsesMouseStatusEx())
+        {
+            *pDz = g_pMouseStatusReqEx->dz;
+            *pDw = g_pMouseStatusReqEx->dw;
+            *pfButtons = g_pMouseStatusReqEx->fButtons;
+        }
+    }
+
+    return rc;
+}
+#endif /* VBOXGUEST_WITH_INPUT_DRIVER */
+
+
+void VGDrvNativeISRMousePollEvent(PVBOXGUESTDEVEXT pDevExt)
+{
+#ifdef VBOXGUEST_WITH_INPUT_DRIVER
+    int rc;
+    uint32_t fMouseFeatures = 0;
+    int32_t x = 0;
+    int32_t y = 0;
+    int32_t dz = 0;
+    int32_t dw = 0;
+    uint32_t fButtons = 0;
+#endif
+    NOREF(pDevExt);
+
+    /*
+     * Wake up everyone that's in a poll() and post anyone that has
+     * subscribed to async notifications.
+     */
+    Log3(("VGDrvNativeISRMousePollEvent: wake_up_all\n"));
+    wake_up_all(&g_PollEventQueue);
+    Log3(("VGDrvNativeISRMousePollEvent: kill_fasync\n"));
+    kill_fasync(&g_pFAsyncQueue, SIGIO, POLL_IN);
+#ifdef VBOXGUEST_WITH_INPUT_DRIVER
+    rc = vgdrvLinuxGetHostMouseState(&fMouseFeatures, &x, &y, &dz, &dw, &fButtons);
+    if (RT_SUCCESS(rc))
+    {
+        input_report_abs(g_pInputDevice, ABS_X, x);
+        input_report_abs(g_pInputDevice, ABS_Y, y);
+
+        if (   vgdrvLinuxUsesMouseStatusEx()
+            && fMouseFeatures & VMMDEV_MOUSE_HOST_USES_FULL_STATE_PROTOCOL
+            && fMouseFeatures & VMMDEV_MOUSE_GUEST_USES_FULL_STATE_PROTOCOL)
+        {
+            /* Vertical and horizontal scroll values come as-is from GUI.
+             * Invert values here as it is done in PS/2 mouse driver, so
+             * scrolling direction will be exectly the same. */
+            input_report_rel(g_pInputDevice, REL_WHEEL,  -dz);
+            input_report_rel(g_pInputDevice, REL_HWHEEL, -dw);
+
+            input_report_key(g_pInputDevice, BTN_LEFT,   RT_BOOL(fButtons & VMMDEV_MOUSE_BUTTON_LEFT));
+            input_report_key(g_pInputDevice, BTN_RIGHT,  RT_BOOL(fButtons & VMMDEV_MOUSE_BUTTON_RIGHT));
+            input_report_key(g_pInputDevice, BTN_MIDDLE, RT_BOOL(fButtons & VMMDEV_MOUSE_BUTTON_MIDDLE));
+            input_report_key(g_pInputDevice, BTN_SIDE,   RT_BOOL(fButtons & VMMDEV_MOUSE_BUTTON_X1));
+            input_report_key(g_pInputDevice, BTN_EXTRA,  RT_BOOL(fButtons & VMMDEV_MOUSE_BUTTON_X2));
+        }
+
+# ifdef EV_SYN
+        input_sync(g_pInputDevice);
+# endif
+    }
+#endif
+    Log3(("VGDrvNativeISRMousePollEvent: done\n"));
+}
+
+
+bool VGDrvNativeProcessOption(PVBOXGUESTDEVEXT pDevExt, const char *pszName, const char *pszValue)
+{
+    RT_NOREF(pDevExt); RT_NOREF(pszName); RT_NOREF(pszValue);
+    return false;
+}
+
+
+#if RTLNX_VER_MIN(2,6,0)
+
+/** log and dbg_log parameter setter. */
+static int vgdrvLinuxParamLogGrpSet(const char *pszValue, CONST_4_15 struct kernel_param *pParam)
+{
+    if (g_fLoggerCreated)
+    {
+        PRTLOGGER pLogger = pParam->name[0] == 'd' ? RTLogDefaultInstance() : RTLogRelGetDefaultInstance();
+        if (pLogger)
+            RTLogGroupSettings(pLogger, pszValue);
+    }
+    else if (pParam->name[0] != 'd')
+        strlcpy(&g_szLogGrp[0], pszValue, sizeof(g_szLogGrp));
+
+    return 0;
+}
+
+/** log and dbg_log parameter getter. */
+static int vgdrvLinuxParamLogGrpGet(char *pszBuf, CONST_4_15 struct kernel_param *pParam)
+{
+    PRTLOGGER pLogger = pParam->name[0] == 'd' ? RTLogDefaultInstance() : RTLogRelGetDefaultInstance();
+    *pszBuf = '\0';
+    if (pLogger)
+        RTLogQueryGroupSettings(pLogger, pszBuf, _4K);
+    return strlen(pszBuf);
+}
+
+
+/** log and dbg_log_flags parameter setter. */
+static int vgdrvLinuxParamLogFlagsSet(const char *pszValue, CONST_4_15 struct kernel_param *pParam)
+{
+    if (g_fLoggerCreated)
+    {
+        PRTLOGGER pLogger = pParam->name[0] == 'd' ? RTLogDefaultInstance() : RTLogRelGetDefaultInstance();
+        if (pLogger)
+            RTLogFlags(pLogger, pszValue);
+    }
+    else if (pParam->name[0] != 'd')
+        strlcpy(&g_szLogFlags[0], pszValue, sizeof(g_szLogFlags));
+    return 0;
+}
+
+/** log and dbg_log_flags parameter getter. */
+static int vgdrvLinuxParamLogFlagsGet(char *pszBuf, CONST_4_15 struct kernel_param *pParam)
+{
+    PRTLOGGER pLogger = pParam->name[0] == 'd' ? RTLogDefaultInstance() : RTLogRelGetDefaultInstance();
+    *pszBuf = '\0';
+    if (pLogger)
+        RTLogQueryFlags(pLogger, pszBuf, _4K);
+    return strlen(pszBuf);
+}
+
+
+/** log and dbg_log_dest parameter setter. */
+static int vgdrvLinuxParamLogDstSet(const char *pszValue, CONST_4_15 struct kernel_param *pParam)
+{
+    if (g_fLoggerCreated)
+    {
+        PRTLOGGER pLogger = pParam->name[0] == 'd' ? RTLogDefaultInstance() : RTLogRelGetDefaultInstance();
+        if (pLogger)
+            RTLogDestinations(pLogger, pszValue);
+    }
+    else if (pParam->name[0] != 'd')
+        strlcpy(&g_szLogDst[0], pszValue, sizeof(g_szLogDst));
+    return 0;
+}
+
+/** log and dbg_log_dest parameter getter. */
+static int vgdrvLinuxParamLogDstGet(char *pszBuf, CONST_4_15 struct kernel_param *pParam)
+{
+    PRTLOGGER pLogger = pParam->name[0] == 'd' ? RTLogDefaultInstance() : RTLogRelGetDefaultInstance();
+    *pszBuf = '\0';
+    if (pLogger)
+        RTLogQueryDestinations(pLogger, pszBuf, _4K);
+    return strlen(pszBuf);
+}
+
+
+/** r3_log_to_host parameter setter. */
+static int vgdrvLinuxParamR3LogToHostSet(const char *pszValue, CONST_4_15 struct kernel_param *pParam)
+{
+    g_DevExt.fLoggingEnabled = VBDrvCommonIsOptionValueTrue(pszValue);
+    return 0;
+}
+
+/** r3_log_to_host parameter getter. */
+static int vgdrvLinuxParamR3LogToHostGet(char *pszBuf, CONST_4_15 struct kernel_param *pParam)
+{
+    strcpy(pszBuf, g_DevExt.fLoggingEnabled ? "enabled" : "disabled");
+    return strlen(pszBuf);
+}
+
+
+/*
+ * Define module parameters.
+ */
+module_param_call(log,            vgdrvLinuxParamLogGrpSet,   vgdrvLinuxParamLogGrpGet,   NULL, 0664);
+module_param_call(log_flags,      vgdrvLinuxParamLogFlagsSet, vgdrvLinuxParamLogFlagsGet, NULL, 0664);
+module_param_call(log_dest,       vgdrvLinuxParamLogDstSet,   vgdrvLinuxParamLogDstGet,   NULL, 0664);
+# ifdef LOG_ENABLED
+module_param_call(dbg_log,        vgdrvLinuxParamLogGrpSet,   vgdrvLinuxParamLogGrpGet,   NULL, 0664);
+module_param_call(dbg_log_flags,  vgdrvLinuxParamLogFlagsSet, vgdrvLinuxParamLogFlagsGet, NULL, 0664);
+module_param_call(dbg_log_dest,   vgdrvLinuxParamLogDstSet,   vgdrvLinuxParamLogDstGet,   NULL, 0664);
+# endif
+module_param_call(r3_log_to_host, vgdrvLinuxParamR3LogToHostSet, vgdrvLinuxParamR3LogToHostGet, NULL, 0664);
+
+#endif /* 2.6.0 and later */
+
+
+module_init(vgdrvLinuxModInit);
+module_exit(vgdrvLinuxModExit);
+
+MODULE_AUTHOR(VBOX_VENDOR);
+MODULE_DESCRIPTION(VBOX_PRODUCT " Guest Additions for Linux Module");
+MODULE_LICENSE("GPL");
+#ifdef MODULE_VERSION
+MODULE_VERSION(VBOX_VERSION_STRING " r" RT_XSTR(VBOX_SVN_REV));
+#endif
+
diff --git a/src/VBox/Additions/common/VBoxGuest/VBoxGuest-netbsd.c b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-netbsd.c
new file mode 100644
index 00000000..a7c8c028
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-netbsd.c
@@ -0,0 +1,1094 @@
+/* $Id: VBoxGuest-netbsd.c $ */
+/** @file
+ * VirtualBox Guest Additions Driver for NetBSD.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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/param.h>
+#include <sys/systm.h>
+#include <sys/select.h>
+#include <sys/conf.h>
+#include <sys/kernel.h>
+#include <sys/kmem.h>
+#include <sys/module.h>
+#include <sys/device.h>
+#include <sys/bus.h>
+#include <sys/poll.h>
+#include <sys/proc.h>
+#include <sys/kauth.h>
+#include <sys/stat.h>
+#include <sys/selinfo.h>
+#include <sys/queue.h>
+#include <sys/lock.h>
+#include <sys/types.h>
+#include <sys/conf.h>
+#include <sys/malloc.h>
+#include <sys/uio.h>
+#include <sys/file.h>
+#include <sys/filedesc.h>
+#include <sys/vfs_syscalls.h>
+#include <dev/pci/pcivar.h>
+#include <dev/pci/pcireg.h>
+#include <dev/pci/pcidevs.h>
+
+#include <dev/wscons/wsconsio.h>
+#include <dev/wscons/wsmousevar.h>
+#include <dev/wscons/tpcalibvar.h>
+
+#ifdef PVM
+#  undef PVM
+#endif
+#include "VBoxGuestInternal.h"
+#include <VBox/log.h>
+#include <iprt/err.h>
+#include <iprt/assert.h>
+#include <iprt/initterm.h>
+#include <iprt/process.h>
+#include <iprt/mem.h>
+#include <iprt/asm.h>
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+/** The module name. */
+#define DEVICE_NAME  "vboxguest"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+typedef struct VBoxGuestDeviceState
+{
+    device_t sc_dev;
+    pci_chipset_tag_t sc_pc;
+
+    bus_space_tag_t sc_iot;
+    bus_space_handle_t sc_ioh;
+    bus_addr_t sc_iobase;
+    bus_size_t sc_iosize;
+
+    bus_space_tag_t sc_memt;
+    bus_space_handle_t sc_memh;
+
+    /** Size of the memory area. */
+    bus_size_t         sc_memsize;
+
+    /** IRQ resource handle. */
+    pci_intr_handle_t  ih;
+    /** Pointer to the IRQ handler. */
+    void              *pfnIrqHandler;
+
+    /** Controller features, limits and status. */
+    u_int              vboxguest_state;
+
+    device_t sc_wsmousedev;
+    VMMDevReqMouseStatus *sc_vmmmousereq;
+    PVBOXGUESTSESSION sc_session;
+    struct tpcalib_softc sc_tpcalib;
+} vboxguest_softc;
+
+
+struct vboxguest_fdata
+{
+    vboxguest_softc *sc;
+    PVBOXGUESTSESSION session;
+};
+
+#define VBOXGUEST_STATE_INITOK 1 << 0
+
+
+/*********************************************************************************************************************************
+*   Internal Functions                                                                                                           *
+*********************************************************************************************************************************/
+/*
+ * Driver(9) autoconf machinery.
+ */
+static int VBoxGuestNetBSDMatch(device_t parent, cfdata_t match, void *aux);
+static void VBoxGuestNetBSDAttach(device_t parent, device_t self, void *aux);
+static void VBoxGuestNetBSDWsmAttach(vboxguest_softc *sc);
+static int VBoxGuestNetBSDDetach(device_t self, int flags);
+
+/*
+ * IRQ related functions.
+ */
+static int  VBoxGuestNetBSDAddIRQ(vboxguest_softc *sc, struct pci_attach_args *pa);
+static void VBoxGuestNetBSDRemoveIRQ(vboxguest_softc *sc);
+static int  VBoxGuestNetBSDISR(void *pvState);
+
+/*
+ * Character device file handlers.
+ */
+static int VBoxGuestNetBSDOpen(dev_t device, int flags, int fmt, struct lwp *process);
+static int VBoxGuestNetBSDClose(struct file *fp);
+static int VBoxGuestNetBSDIOCtl(struct file *fp, u_long cmd, void *addr);
+static int VBoxGuestNetBSDIOCtlSlow(struct vboxguest_fdata *fdata, u_long command, void *data);
+static int VBoxGuestNetBSDPoll(struct file *fp, int events);
+
+/*
+ * wsmouse(4) accessops
+ */
+static int VBoxGuestNetBSDWsmEnable(void *cookie);
+static void VBoxGuestNetBSDWsmDisable(void *cookie);
+static int VBoxGuestNetBSDWsmIOCtl(void *cookie, u_long cmd, void *data, int flag, struct lwp *l);
+
+static int VBoxGuestNetBSDSetMouseStatus(vboxguest_softc *sc, uint32_t fStatus);
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+extern struct cfdriver vboxguest_cd; /* CFDRIVER_DECL */
+extern struct cfattach vboxguest_ca; /* CFATTACH_DECL */
+
+/*
+ * The /dev/vboxguest character device entry points.
+ */
+static struct cdevsw g_VBoxGuestNetBSDChrDevSW =
+{
+    .d_open = VBoxGuestNetBSDOpen,
+    .d_close = noclose,
+    .d_read = noread,
+    .d_write = nowrite,
+    .d_ioctl = noioctl,
+    .d_stop = nostop,
+    .d_tty = notty,
+    .d_poll = nopoll,
+    .d_mmap = nommap,
+    .d_kqfilter = nokqfilter,
+};
+
+static const struct fileops vboxguest_fileops = {
+    .fo_read = fbadop_read,
+    .fo_write = fbadop_write,
+    .fo_ioctl = VBoxGuestNetBSDIOCtl,
+    .fo_fcntl = fnullop_fcntl,
+    .fo_poll = VBoxGuestNetBSDPoll,
+    .fo_stat = fbadop_stat,
+    .fo_close = VBoxGuestNetBSDClose,
+    .fo_kqfilter = fnullop_kqfilter,
+    .fo_restart = fnullop_restart
+};
+
+
+const struct wsmouse_accessops vboxguest_wsm_accessops = {
+    VBoxGuestNetBSDWsmEnable,
+    VBoxGuestNetBSDWsmIOCtl,
+    VBoxGuestNetBSDWsmDisable,
+};
+
+
+/*
+ * XXX: wsmux(4) doesn't properly handle the case when two mice with
+ * absolute position events but different calibration data are being
+ * multiplexed.  Without GAs the absolute events will be reported
+ * through the tablet ums(4) device with the range of 32k, but with
+ * GAs the absolute events will be reported through the VMM device
+ * (wsmouse at vboxguest) and VMM uses the range of 64k.  Which one
+ * responds to the calibration ioctl depends on the order of
+ * attachment.  On boot kernel attaches ums first and GAs later, so
+ * it's VMM (this driver) that gets the ioctl.  After save/restore the
+ * ums will be detached and re-attached and after that it's ums that
+ * will get the ioctl, but the events (with a wider range) will still
+ * come via the VMM, confusing X, wsmoused, etc.  Hack around that by
+ * forcing the range here to match the tablet's range.
+ *
+ * We force VMM range into the ums range and rely on the fact that no
+ * actual calibration is done and both devices are used in the raw
+ * mode.  See tpcalib_trans call below.
+ *
+ * Cf. src/VBox/Devices/Input/UsbMouse.cpp
+ */
+#define USB_TABLET_RANGE_MIN 0
+#define USB_TABLET_RANGE_MAX 0x7fff
+
+static struct wsmouse_calibcoords vboxguest_wsm_default_calib = {
+    .minx = USB_TABLET_RANGE_MIN, // VMMDEV_MOUSE_RANGE_MIN,
+    .miny = USB_TABLET_RANGE_MIN, // VMMDEV_MOUSE_RANGE_MIN,
+    .maxx = USB_TABLET_RANGE_MAX, // VMMDEV_MOUSE_RANGE_MAX,
+    .maxy = USB_TABLET_RANGE_MAX, // VMMDEV_MOUSE_RANGE_MAX,
+    .samplelen = WSMOUSE_CALIBCOORDS_RESET,
+};
+
+/** Device extention & session data association structure. */
+static VBOXGUESTDEVEXT      g_DevExt;
+
+static vboxguest_softc     *g_SC;
+
+/** Reference counter */
+static volatile uint32_t    cUsers;
+/** selinfo structure used for polling. */
+static struct selinfo       g_SelInfo;
+
+
+CFATTACH_DECL_NEW(vboxguest, sizeof(vboxguest_softc),
+    VBoxGuestNetBSDMatch, VBoxGuestNetBSDAttach, VBoxGuestNetBSDDetach, NULL);
+
+
+static int VBoxGuestNetBSDMatch(device_t parent, cfdata_t match, void *aux)
+{
+    const struct pci_attach_args *pa = aux;
+
+    if (RT_UNLIKELY(g_SC != NULL)) /* should not happen */
+        return 0;
+
+    if (   PCI_VENDOR(pa->pa_id) == VMMDEV_VENDORID
+        && PCI_PRODUCT(pa->pa_id) == VMMDEV_DEVICEID)
+    {
+        return 1;
+    }
+
+    return 0;
+}
+
+
+static void VBoxGuestNetBSDAttach(device_t parent, device_t self, void *aux)
+{
+    int rc = VINF_SUCCESS;
+    int iResId = 0;
+    vboxguest_softc *sc;
+    struct pci_attach_args *pa = aux;
+    bus_space_tag_t iot, memt;
+    bus_space_handle_t ioh, memh;
+    bus_dma_segment_t seg;
+    int ioh_valid, memh_valid;
+
+    KASSERT(g_SC == NULL);
+
+    cUsers = 0;
+
+    aprint_normal(": VirtualBox Guest\n");
+
+    sc = device_private(self);
+    sc->sc_dev = self;
+
+    /*
+     * Initialize IPRT R0 driver, which internally calls OS-specific r0 init.
+     */
+    rc = RTR0Init(0);
+    if (RT_FAILURE(rc))
+    {
+        LogFunc(("RTR0Init failed.\n"));
+        aprint_error_dev(sc->sc_dev, "RTR0Init failed\n");
+        return;
+    }
+
+    sc->sc_pc = pa->pa_pc;
+
+    /*
+     * Allocate I/O port resource.
+     */
+    ioh_valid = (pci_mapreg_map(pa, PCI_BAR0,
+                                PCI_MAPREG_TYPE_IO, 0,
+                                &sc->sc_iot, &sc->sc_ioh,
+                                &sc->sc_iobase, &sc->sc_iosize) == 0);
+
+    if (ioh_valid)
+    {
+
+        /*
+         * Map the MMIO region.
+         */
+        memh_valid = (pci_mapreg_map(pa, PCI_BAR1,
+                                     PCI_MAPREG_TYPE_MEM, BUS_SPACE_MAP_LINEAR,
+                                     &sc->sc_memt, &sc->sc_memh,
+                                     NULL, &sc->sc_memsize) == 0);
+        if (memh_valid)
+        {
+            /*
+             * Call the common device extension initializer.
+             */
+            rc = VGDrvCommonInitDevExt(&g_DevExt, sc->sc_iobase,
+                                       bus_space_vaddr(sc->sc_memt, sc->sc_memh),
+                                       sc->sc_memsize,
+#if ARCH_BITS == 64
+                                       VBOXOSTYPE_NetBSD_x64,
+#else
+                                       VBOXOSTYPE_NetBSD,
+#endif
+                                       VMMDEV_EVENT_MOUSE_POSITION_CHANGED);
+            if (RT_SUCCESS(rc))
+            {
+                /*
+                 * Add IRQ of VMMDev.
+                 */
+                rc = VBoxGuestNetBSDAddIRQ(sc, pa);
+                if (RT_SUCCESS(rc))
+                {
+                    sc->vboxguest_state |= VBOXGUEST_STATE_INITOK;
+
+                    /*
+                     * Read host configuration.
+                     */
+                    VGDrvCommonProcessOptionsFromHost(&g_DevExt);
+
+                    /*
+                     * Attach wsmouse.
+                     */
+                    VBoxGuestNetBSDWsmAttach(sc);
+
+                    g_SC = sc;
+                    return;
+                }
+                VGDrvCommonDeleteDevExt(&g_DevExt);
+            }
+            else
+            {
+                aprint_error_dev(sc->sc_dev, "init failed\n");
+            }
+            bus_space_unmap(sc->sc_memt, sc->sc_memh, sc->sc_memsize);
+        }
+        else
+        {
+            aprint_error_dev(sc->sc_dev, "MMIO mapping failed\n");
+        }
+        bus_space_unmap(sc->sc_iot, sc->sc_ioh, sc->sc_iosize);
+    }
+    else
+    {
+        aprint_error_dev(sc->sc_dev, "IO mapping failed\n");
+    }
+
+    RTR0Term();
+    return;
+}
+
+
+/**
+ * Sets IRQ for VMMDev.
+ *
+ * @returns NetBSD error code.
+ * @param   sc  Pointer to the state info structure.
+ * @param   pa  Pointer to the PCI attach arguments.
+ */
+static int VBoxGuestNetBSDAddIRQ(vboxguest_softc *sc, struct pci_attach_args *pa)
+{
+    int iResId = 0;
+    int rc = 0;
+    const char *intrstr;
+#if __NetBSD_Prereq__(6, 99, 39)
+    char intstrbuf[100];
+#endif
+
+    LogFlow((DEVICE_NAME ": %s\n", __func__));
+
+    if (pci_intr_map(pa, &sc->ih))
+    {
+        aprint_error_dev(sc->sc_dev, "couldn't map interrupt.\n");
+        return VERR_DEV_IO_ERROR;
+    }
+
+    intrstr = pci_intr_string(sc->sc_pc, sc->ih
+#if __NetBSD_Prereq__(6, 99, 39)
+                              , intstrbuf, sizeof(intstrbuf)
+#endif
+                              );
+    aprint_normal_dev(sc->sc_dev, "interrupting at %s\n", intrstr);
+
+    sc->pfnIrqHandler = pci_intr_establish(sc->sc_pc, sc->ih, IPL_BIO, VBoxGuestNetBSDISR, sc);
+    if (sc->pfnIrqHandler == NULL)
+    {
+        aprint_error_dev(sc->sc_dev, "couldn't establish interrupt\n");
+        return VERR_DEV_IO_ERROR;
+    }
+
+    return VINF_SUCCESS;
+}
+
+
+/*
+ * Optionally attach wsmouse(4) device as a child.
+ */
+static void VBoxGuestNetBSDWsmAttach(vboxguest_softc *sc)
+{
+    struct wsmousedev_attach_args am = { &vboxguest_wsm_accessops, sc };
+
+    PVBOXGUESTSESSION session = NULL;
+    VMMDevReqMouseStatus *req = NULL;
+    int rc;
+
+    rc = VGDrvCommonCreateKernelSession(&g_DevExt, &session);
+    if (RT_FAILURE(rc))
+        goto fail;
+
+    rc = VbglR0GRAlloc((VMMDevRequestHeader **)&req, sizeof(*req),
+                       VMMDevReq_GetMouseStatus);
+    if (RT_FAILURE(rc))
+        goto fail;
+
+#if __NetBSD_Prereq__(9,99,88)
+    sc->sc_wsmousedev = config_found(sc->sc_dev, &am, wsmousedevprint,
+                            CFARGS(.iattr = "wsmousedev"));
+#elif __NetBSD_Prereq__(9,99,82)
+    sc->sc_wsmousedev = config_found(sc->sc_dev, &am, wsmousedevprint,
+                            CFARG_IATTR, "wsmousedev",
+                            CFARG_EOL);
+#else
+    sc->sc_wsmousedev = config_found_ia(sc->sc_dev, "wsmousedev",
+                            &am, wsmousedevprint);
+#endif
+
+    if (sc->sc_wsmousedev == NULL)
+        goto fail;
+
+    sc->sc_session = session;
+    sc->sc_vmmmousereq = req;
+
+    tpcalib_init(&sc->sc_tpcalib);
+    tpcalib_ioctl(&sc->sc_tpcalib, WSMOUSEIO_SCALIBCOORDS,
+                  &vboxguest_wsm_default_calib, 0, 0);
+    return;
+
+  fail:
+    if (session != NULL)
+        VGDrvCommonCloseSession(&g_DevExt, session);
+    if (req != NULL)
+        VbglR0GRFree((VMMDevRequestHeader *)req);
+}
+
+
+static int VBoxGuestNetBSDDetach(device_t self, int flags)
+{
+    vboxguest_softc *sc;
+    sc = device_private(self);
+
+    LogFlow((DEVICE_NAME ": %s\n", __func__));
+
+    if (cUsers > 0)
+        return EBUSY;
+
+    if ((sc->vboxguest_state & VBOXGUEST_STATE_INITOK) == 0)
+        return 0;
+
+    /*
+     * Reverse what we did in VBoxGuestNetBSDAttach.
+     */
+    if (sc->sc_vmmmousereq != NULL)
+        VbglR0GRFree((VMMDevRequestHeader *)sc->sc_vmmmousereq);
+
+    VBoxGuestNetBSDRemoveIRQ(sc);
+
+    VGDrvCommonDeleteDevExt(&g_DevExt);
+
+    bus_space_unmap(sc->sc_memt, sc->sc_memh, sc->sc_memsize);
+    bus_space_unmap(sc->sc_iot, sc->sc_ioh, sc->sc_iosize);
+
+    RTR0Term();
+
+    return config_detach_children(self, flags);
+}
+
+
+/**
+ * Removes IRQ for VMMDev.
+ *
+ * @param   sc      Opaque pointer to the state info structure.
+ */
+static void VBoxGuestNetBSDRemoveIRQ(vboxguest_softc *sc)
+{
+    LogFlow((DEVICE_NAME ": %s\n", __func__));
+
+    if (sc->pfnIrqHandler)
+    {
+        pci_intr_disestablish(sc->sc_pc, sc->pfnIrqHandler);
+    }
+}
+
+
+/**
+ * Interrupt service routine.
+ *
+ * @returns Whether the interrupt was from VMMDev.
+ * @param   pvState Opaque pointer to the device state.
+ */
+static int VBoxGuestNetBSDISR(void *pvState)
+{
+    LogFlow((DEVICE_NAME ": %s: pvState=%p\n", __func__, pvState));
+
+    bool fOurIRQ = VGDrvCommonISR(&g_DevExt);
+
+    return fOurIRQ ? 1 : 0;
+}
+
+
+/*
+ * Called by VGDrvCommonISR() if mouse position changed
+ */
+void VGDrvNativeISRMousePollEvent(PVBOXGUESTDEVEXT pDevExt)
+{
+    vboxguest_softc *sc = g_SC;
+
+    LogFlow((DEVICE_NAME ": %s\n", __func__));
+
+    /*
+     * Wake up poll waiters.
+     */
+    selnotify(&g_SelInfo, 0, 0);
+
+    if (sc->sc_vmmmousereq != NULL) {
+        int x, y;
+        int rc;
+
+        sc->sc_vmmmousereq->mouseFeatures = 0;
+        sc->sc_vmmmousereq->pointerXPos = 0;
+        sc->sc_vmmmousereq->pointerYPos = 0;
+
+        rc = VbglR0GRPerform(&sc->sc_vmmmousereq->header);
+        if (RT_FAILURE(rc))
+            return;
+
+        /* XXX: see the comment for vboxguest_wsm_default_calib */
+        int rawx = (unsigned)sc->sc_vmmmousereq->pointerXPos >> 1;
+        int rawy = (unsigned)sc->sc_vmmmousereq->pointerYPos >> 1;
+        tpcalib_trans(&sc->sc_tpcalib, rawx, rawy, &x, &y);
+
+        wsmouse_input(sc->sc_wsmousedev,
+                      0,    /* buttons */
+                      x, y,
+                      0, 0, /* z, w */
+                      WSMOUSE_INPUT_ABSOLUTE_X | WSMOUSE_INPUT_ABSOLUTE_Y);
+    }
+}
+
+
+bool VGDrvNativeProcessOption(PVBOXGUESTDEVEXT pDevExt, const char *pszName, const char *pszValue)
+{
+    RT_NOREF(pDevExt); RT_NOREF(pszName); RT_NOREF(pszValue);
+    return false;
+}
+
+
+static int VBoxGuestNetBSDSetMouseStatus(vboxguest_softc *sc, uint32_t fStatus)
+{
+    VBGLIOCSETMOUSESTATUS Req;
+    int rc;
+
+    VBGLREQHDR_INIT(&Req.Hdr, SET_MOUSE_STATUS);
+    Req.u.In.fStatus = fStatus;
+    rc = VGDrvCommonIoCtl(VBGL_IOCTL_SET_MOUSE_STATUS,
+                          &g_DevExt,
+                          sc->sc_session,
+                          &Req.Hdr, sizeof(Req));
+    if (RT_SUCCESS(rc))
+        rc = Req.Hdr.rc;
+
+    return rc;
+}
+
+
+static int
+VBoxGuestNetBSDWsmEnable(void *cookie)
+{
+    vboxguest_softc *sc = cookie;
+    int rc;
+
+    rc = VBoxGuestNetBSDSetMouseStatus(sc, VMMDEV_MOUSE_GUEST_CAN_ABSOLUTE
+                                         | VMMDEV_MOUSE_NEW_PROTOCOL);
+    if (RT_FAILURE(rc))
+        return RTErrConvertToErrno(rc);
+
+    return 0;
+}
+
+
+static void
+VBoxGuestNetBSDWsmDisable(void *cookie)
+{
+    vboxguest_softc *sc = cookie;
+    VBoxGuestNetBSDSetMouseStatus(sc, 0);
+}
+
+
+static int
+VBoxGuestNetBSDWsmIOCtl(void *cookie, u_long cmd, void *data, int flag, struct lwp *l)
+{
+    vboxguest_softc *sc = cookie;
+
+    switch (cmd) {
+    case WSMOUSEIO_GTYPE:
+        *(u_int *)data = WSMOUSE_TYPE_TPANEL;
+        break;
+
+    case WSMOUSEIO_SCALIBCOORDS:
+    case WSMOUSEIO_GCALIBCOORDS:
+        return tpcalib_ioctl(&sc->sc_tpcalib, cmd, data, flag, l);
+
+    default:
+        return EPASSTHROUGH;
+    }
+    return 0;
+}
+
+
+/**
+ * File open handler
+ *
+ */
+static int VBoxGuestNetBSDOpen(dev_t device, int flags, int fmt, struct lwp *pLwp)
+{
+    vboxguest_softc *sc;
+    struct vboxguest_fdata *fdata;
+    file_t *fp;
+    int fd, error;
+
+    LogFlow((DEVICE_NAME ": %s\n", __func__));
+
+    if ((sc = device_lookup_private(&vboxguest_cd, minor(device))) == NULL)
+    {
+        printf("device_lookup_private failed\n");
+        return (ENXIO);
+    }
+
+    if ((sc->vboxguest_state & VBOXGUEST_STATE_INITOK) == 0)
+    {
+        aprint_error_dev(sc->sc_dev, "device not configured\n");
+        return (ENXIO);
+    }
+
+    fdata = kmem_alloc(sizeof(*fdata), KM_SLEEP);
+    if (fdata != NULL)
+    {
+        fdata->sc = sc;
+
+        error = fd_allocfile(&fp, &fd);
+        if (error == 0)
+        {
+            /*
+             * Create a new session.
+             */
+            struct kauth_cred *pCred = pLwp->l_cred;
+            int fHaveCred = (pCred != NULL && pCred != NOCRED && pCred != FSCRED);
+            uint32_t fRequestor;
+            int fIsWheel;
+            int rc;
+
+            fRequestor = VMMDEV_REQUESTOR_USERMODE | VMMDEV_REQUESTOR_TRUST_NOT_GIVEN;
+
+            /* uid */
+            if (fHaveCred && kauth_cred_geteuid(pCred) == (uid_t)0)
+                fRequestor |= VMMDEV_REQUESTOR_USR_ROOT;
+            else
+                fRequestor |= VMMDEV_REQUESTOR_USR_USER;
+
+            /* gid */
+            if (fHaveCred
+                && (kauth_cred_getegid(pCred) == (gid_t)0
+                    || (kauth_cred_ismember_gid(pCred, 0, &fIsWheel) == 0
+                        && fIsWheel)))
+                fRequestor |= VMMDEV_REQUESTOR_GRP_WHEEL;
+
+#if 0       /** @todo implement /dev/vboxuser */
+            if (!fUnrestricted)
+                fRequestor |= VMMDEV_REQUESTOR_USER_DEVICE;
+#else
+            fRequestor |= VMMDEV_REQUESTOR_NO_USER_DEVICE;
+#endif
+
+            /** @todo can we find out if pLwp is on the console? */
+            fRequestor |= VMMDEV_REQUESTOR_CON_DONT_KNOW;
+
+            rc = VGDrvCommonCreateUserSession(&g_DevExt, fRequestor, &fdata->session);
+            if (RT_SUCCESS(rc))
+            {
+                ASMAtomicIncU32(&cUsers);
+                return fd_clone(fp, fd, flags, &vboxguest_fileops, fdata);
+            }
+
+            aprint_error_dev(sc->sc_dev, "VBox session creation failed\n");
+            closef(fp); /* ??? */
+            error = RTErrConvertToErrno(rc);
+        }
+        kmem_free(fdata, sizeof(*fdata));
+    }
+    else
+        error = ENOMEM;
+    return error;
+}
+
+/**
+ * File close handler
+ *
+ */
+static int VBoxGuestNetBSDClose(struct file *fp)
+{
+    struct vboxguest_fdata *fdata = fp->f_data;
+    vboxguest_softc *sc = fdata->sc;
+
+    LogFlow((DEVICE_NAME ": %s\n", __func__));
+
+    VGDrvCommonCloseSession(&g_DevExt, fdata->session);
+    ASMAtomicDecU32(&cUsers);
+
+    kmem_free(fdata, sizeof(*fdata));
+
+    return 0;
+}
+
+/**
+ * IOCTL handler
+ *
+ */
+static int VBoxGuestNetBSDIOCtl(struct file *fp, u_long command, void *data)
+{
+    struct vboxguest_fdata *fdata = fp->f_data;
+
+    if (VBGL_IOCTL_IS_FAST(command))
+        return VGDrvCommonIoCtlFast(command, &g_DevExt, fdata->session);
+
+    return VBoxGuestNetBSDIOCtlSlow(fdata, command, data);
+}
+
+static int VBoxGuestNetBSDIOCtlSlow(struct vboxguest_fdata *fdata, u_long command, void *data)
+{
+    vboxguest_softc *sc = fdata->sc;
+    size_t cbReq = IOCPARM_LEN(command);
+    PVBGLREQHDR pHdr = NULL;
+    void *pvUser = NULL;
+    int err, rc;
+
+    LogFlow(("%s: command=%#lx data=%p\n", __func__, command, data));
+
+    /*
+     * Buffered request?
+     */
+    if ((command & IOC_DIRMASK) == IOC_INOUT)
+    {
+        /* will be validated by VGDrvCommonIoCtl() */
+        pHdr = (PVBGLREQHDR)data;
+    }
+
+    /*
+     * Big unbuffered request?  "data" is the userland pointer.
+     */
+    else if ((command & IOC_DIRMASK) == IOC_VOID && cbReq != 0)
+    {
+        /*
+         * Read the header, validate it and figure out how much that
+         * needs to be buffered.
+         */
+        VBGLREQHDR Hdr;
+
+        if (RT_UNLIKELY(cbReq < sizeof(Hdr)))
+            return ENOTTY;
+
+        pvUser = data;
+        err = copyin(pvUser, &Hdr, sizeof(Hdr));
+        if (RT_UNLIKELY(err != 0))
+            return err;
+
+        if (RT_UNLIKELY(Hdr.uVersion != VBGLREQHDR_VERSION))
+            return ENOTTY;
+
+        if (cbReq > 16 * _1M)
+            return EINVAL;
+
+        if (Hdr.cbOut == 0)
+            Hdr.cbOut = Hdr.cbIn;
+
+        if (RT_UNLIKELY(   Hdr.cbIn  < sizeof(Hdr) || Hdr.cbIn  > cbReq
+                        || Hdr.cbOut < sizeof(Hdr) || Hdr.cbOut > cbReq))
+            return EINVAL;
+
+        /*
+         * Allocate buffer and copy in the data.
+         */
+        cbReq = RT_MAX(Hdr.cbIn, Hdr.cbOut);
+
+        pHdr = (PVBGLREQHDR)RTMemTmpAlloc(cbReq);
+        if (RT_UNLIKELY(pHdr == NULL))
+        {
+            LogRel(("%s: command=%#lx data=%p: unable to allocate %zu bytes\n",
+                    __func__, command, data, cbReq));
+            return ENOMEM;
+        }
+
+        err = copyin(pvUser, pHdr, Hdr.cbIn);
+        if (err != 0)
+        {
+            RTMemTmpFree(pHdr);
+            return err;
+        }
+
+        if (Hdr.cbIn < cbReq)
+            memset((uint8_t *)pHdr + Hdr.cbIn, '\0', cbReq - Hdr.cbIn);
+    }
+
+    /*
+     * Process the IOCtl.
+     */
+    rc = VGDrvCommonIoCtl(command, &g_DevExt, fdata->session, pHdr, cbReq);
+    if (RT_SUCCESS(rc))
+    {
+        err = 0;
+
+        /*
+         * If unbuffered, copy back the result before returning.
+         */
+        if (pvUser != NULL)
+        {
+            size_t cbOut = pHdr->cbOut;
+            if (cbOut > cbReq)
+            {
+                LogRel(("%s: command=%#lx data=%p: too much output: %zu > %zu\n",
+                        __func__, command, data, cbOut, cbReq));
+                cbOut = cbReq;
+            }
+
+            err = copyout(pHdr, pvUser, cbOut);
+            RTMemTmpFree(pHdr);
+        }
+    }
+    else
+    {
+        LogRel(("%s: command=%#lx data=%p: error %Rrc\n",
+                __func__, command, data, rc));
+
+        if (pvUser != NULL)
+            RTMemTmpFree(pHdr);
+
+        err = RTErrConvertToErrno(rc);
+    }
+
+    return err;
+}
+
+static int VBoxGuestNetBSDPoll(struct file *fp, int events)
+{
+    struct vboxguest_fdata *fdata = fp->f_data;
+    vboxguest_softc *sc = fdata->sc;
+
+    int rc = 0;
+    int events_processed;
+
+    uint32_t u32CurSeq;
+
+    LogFlow((DEVICE_NAME ": %s\n", __func__));
+
+    u32CurSeq = ASMAtomicUoReadU32(&g_DevExt.u32MousePosChangedSeq);
+    if (fdata->session->u32MousePosChangedSeq != u32CurSeq)
+    {
+        events_processed = events & (POLLIN | POLLRDNORM);
+        fdata->session->u32MousePosChangedSeq = u32CurSeq;
+    }
+    else
+    {
+        events_processed = 0;
+
+        selrecord(curlwp, &g_SelInfo);
+    }
+
+    return events_processed;
+}
+
+
+/**
+ * @note This code is duplicated on other platforms with variations, so please
+ *       keep them all up to date when making changes!
+ */
+int VBOXCALL VBoxGuestIDC(void *pvSession, uintptr_t uReq, PVBGLREQHDR pReqHdr, size_t cbReq)
+{
+    /*
+     * Simple request validation (common code does the rest).
+     */
+    int rc;
+    if (   RT_VALID_PTR(pReqHdr)
+        && cbReq >= sizeof(*pReqHdr))
+    {
+        /*
+         * All requests except the connect one requires a valid session.
+         */
+        PVBOXGUESTSESSION pSession = (PVBOXGUESTSESSION)pvSession;
+        if (pSession)
+        {
+            if (   RT_VALID_PTR(pSession)
+                && pSession->pDevExt == &g_DevExt)
+                rc = VGDrvCommonIoCtl(uReq, &g_DevExt, pSession, pReqHdr, cbReq);
+            else
+                rc = VERR_INVALID_HANDLE;
+        }
+        else if (uReq == VBGL_IOCTL_IDC_CONNECT)
+        {
+            rc = VGDrvCommonCreateKernelSession(&g_DevExt, &pSession);
+            if (RT_SUCCESS(rc))
+            {
+                rc = VGDrvCommonIoCtl(uReq, &g_DevExt, pSession, pReqHdr, cbReq);
+                if (RT_FAILURE(rc))
+                    VGDrvCommonCloseSession(&g_DevExt, pSession);
+            }
+        }
+        else
+            rc = VERR_INVALID_HANDLE;
+    }
+    else
+        rc = VERR_INVALID_POINTER;
+    return rc;
+}
+
+
+MODULE(MODULE_CLASS_DRIVER, vboxguest, "pci");
+
+/*
+ * XXX: See netbsd/vboxguest.ioconf for the details.
+*/
+#if 0
+#include "ioconf.c"
+#else
+
+static const struct cfiattrdata wsmousedevcf_iattrdata = {
+    "wsmousedev", 1, {
+        { "mux", "0", 0 },
+    }
+};
+
+/* device vboxguest: wsmousedev */
+static const struct cfiattrdata * const vboxguest_attrs[] = { &wsmousedevcf_iattrdata, NULL };
+CFDRIVER_DECL(vboxguest, DV_DULL, vboxguest_attrs);
+
+static struct cfdriver * const cfdriver_ioconf_vboxguest[] = {
+    &vboxguest_cd, NULL
+};
+
+
+static const struct cfparent vboxguest_pspec = {
+    "pci", "pci", DVUNIT_ANY
+};
+static int vboxguest_loc[] = { -1, -1 };
+
+
+static const struct cfparent wsmousedev_pspec = {
+    "wsmousedev", "vboxguest", DVUNIT_ANY
+};
+static int wsmousedev_loc[] = { 0 };
+
+
+static struct cfdata cfdata_ioconf_vboxguest[] = {
+    /*  vboxguest0 at pci? dev ? function ? */
+    {
+        .cf_name = "vboxguest",
+        .cf_atname = "vboxguest",
+        .cf_unit = 0,           /* Only unit 0 is ever used  */
+        .cf_fstate = FSTATE_NOTFOUND,
+        .cf_loc = vboxguest_loc,
+        .cf_flags = 0,
+        .cf_pspec = &vboxguest_pspec,
+    },
+
+    /* wsmouse* at vboxguest? */
+    { "wsmouse", "wsmouse", 0, FSTATE_STAR, wsmousedev_loc, 0, &wsmousedev_pspec },
+
+    { NULL, NULL, 0, 0, NULL, 0, NULL }
+};
+
+static struct cfattach * const vboxguest_cfattachinit[] = {
+    &vboxguest_ca, NULL
+};
+
+static const struct cfattachinit cfattach_ioconf_vboxguest[] = {
+    { "vboxguest", vboxguest_cfattachinit },
+    { NULL, NULL }
+};
+#endif
+
+
+static int
+vboxguest_modcmd(modcmd_t cmd, void *opaque)
+{
+    devmajor_t bmajor, cmajor;
+#if !__NetBSD_Prereq__(8,99,46)
+    register_t retval;
+#endif
+    int error;
+
+    LogFlow((DEVICE_NAME ": %s\n", __func__));
+
+    switch (cmd)
+    {
+        case MODULE_CMD_INIT:
+            error = config_init_component(cfdriver_ioconf_vboxguest,
+                                          cfattach_ioconf_vboxguest,
+                                          cfdata_ioconf_vboxguest);
+            if (error)
+                break;
+
+            bmajor = cmajor = NODEVMAJOR;
+            error = devsw_attach("vboxguest",
+                                 NULL, &bmajor,
+                                 &g_VBoxGuestNetBSDChrDevSW, &cmajor);
+            if (error)
+            {
+                if (error == EEXIST)
+                    error = 0; /* maybe built-in ... improve eventually */
+                else
+                    break;
+            }
+
+            error = do_sys_mknod(curlwp, "/dev/vboxguest",
+                                 0666|S_IFCHR, makedev(cmajor, 0),
+#if !__NetBSD_Prereq__(8,99,46)
+                                 &retval,
+#endif
+                                 UIO_SYSSPACE);
+            if (error == EEXIST) {
+                error = 0;
+
+                /*
+                 * Since NetBSD doesn't yet have a major reserved for
+                 * vboxguest, the (first free) major we get will
+                 * change when new devices are added, so an existing
+                 * /dev/vboxguest may now point to some other device,
+                 * creating confusion (tripped me up a few times).
+                 */
+                aprint_normal("vboxguest: major %d:"
+                              " check existing /dev/vboxguest\n", cmajor);
+            }
+            break;
+
+        case MODULE_CMD_FINI:
+            error = config_fini_component(cfdriver_ioconf_vboxguest,
+                                          cfattach_ioconf_vboxguest,
+                                          cfdata_ioconf_vboxguest);
+            if (error)
+                break;
+
+            devsw_detach(NULL, &g_VBoxGuestNetBSDChrDevSW);
+            break;
+
+        default:
+            return ENOTTY;
+    }
+    return error;
+}
diff --git a/src/VBox/Additions/common/VBoxGuest/VBoxGuest-os2.cpp b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-os2.cpp
new file mode 100644
index 00000000..10363a65
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-os2.cpp
@@ -0,0 +1,698 @@
+/* $Id: VBoxGuest-os2.cpp $ */
+/** @file
+ * VBoxGuest - OS/2 specifics.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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
+ * ---------------------------------------------------------------------------
+ * This code is based on:
+ *
+ * VBoxDrv - OS/2 specifics.
+ *
+ * Copyright (c) 2007-2012 knut st. osmundsen <bird-src-spam@anduin.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <os2ddk/bsekee.h>
+
+#include "VBoxGuestInternal.h"
+#include <VBox/version.h>
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/initterm.h>
+#include <iprt/log.h>
+#include <iprt/memobj.h>
+#include <iprt/mem.h>
+#include <iprt/param.h>
+#include <iprt/process.h>
+#include <iprt/spinlock.h>
+#include <iprt/string.h>
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/**
+ * Device extention & session data association structure.
+ */
+static VBOXGUESTDEVEXT      g_DevExt;
+/** The memory object for the MMIO memory.  */
+static RTR0MEMOBJ           g_MemObjMMIO = NIL_RTR0MEMOBJ;
+/** The memory mapping object the MMIO memory. */
+static RTR0MEMOBJ           g_MemMapMMIO = NIL_RTR0MEMOBJ;
+
+/** Spinlock protecting g_apSessionHashTab. */
+static RTSPINLOCK           g_Spinlock = NIL_RTSPINLOCK;
+/** Hash table */
+static PVBOXGUESTSESSION    g_apSessionHashTab[19];
+/** Calculates the index into g_apSessionHashTab.*/
+#define SESSION_HASH(sfn) ((sfn) % RT_ELEMENTS(g_apSessionHashTab))
+
+RT_C_DECLS_BEGIN
+/* Defined in VBoxGuestA-os2.asm */
+extern uint32_t             g_PhysMMIOBase;
+extern uint32_t             g_cbMMIO; /* 0 currently not set. */
+extern uint16_t             g_IOPortBase;
+extern uint8_t              g_bInterruptLine;
+extern uint8_t              g_bPciBusNo;
+extern uint8_t              g_bPciDevFunNo;
+extern RTFAR16              g_fpfnVBoxGuestOs2IDCService16;
+extern RTFAR16              g_fpfnVBoxGuestOs2IDCService16Asm;
+#ifdef DEBUG_READ
+/* (debugging) */
+extern uint16_t             g_offLogHead;
+extern uint16_t volatile    g_offLogTail;
+extern uint16_t const       g_cchLogMax;
+extern char                 g_szLog[];
+#endif
+/* (init only:) */
+extern char                 g_szInitText[];
+extern uint16_t             g_cchInitText;
+extern uint16_t             g_cchInitTextMax;
+RT_C_DECLS_END
+
+
+/*********************************************************************************************************************************
+*   Internal Functions                                                                                                           *
+*********************************************************************************************************************************/
+static int vgdrvOS2MapMemory(void);
+static VBOXOSTYPE vgdrvOS2DetectVersion(void);
+
+/* in VBoxGuestA-os2.asm */
+DECLASM(int) vgdrvOS2DevHlpSetIRQ(uint8_t bIRQ);
+
+
+/**
+ * 32-bit Ring-0 initialization.
+ *
+ * This is called from VBoxGuestA-os2.asm upon the first open call to the vboxgst$ device.
+ *
+ * @returns 0 on success, non-zero on failure.
+ * @param   pszArgs     Pointer to the device arguments.
+ */
+DECLASM(int) vgdrvOS2Init(const char *pszArgs)
+{
+    //Log(("vgdrvOS2Init: pszArgs='%s' MMIO=0x%RX32 IOPort=0x%RX16 Int=%#x Bus=%#x Dev=%#x Fun=%d\n",
+    //     pszArgs, g_PhysMMIOBase, g_IOPortBase, g_bInterruptLine, g_bPciBusNo, g_bPciDevFunNo >> 3, g_bPciDevFunNo & 7));
+
+    /*
+     * Initialize the runtime.
+     */
+    int rc = RTR0Init(0);
+    if (RT_SUCCESS(rc))
+    {
+        /*
+         * Process the command line.
+         */
+        bool fVerbose = true;
+        if (pszArgs)
+        {
+            char ch;
+            while ((ch = *pszArgs++) != '\0')
+                if (ch == '-' || ch == '/')
+                {
+                    ch = *pszArgs++;
+                    if (ch == 'Q' || ch == 'q')
+                        fVerbose = false;
+                    else if (ch == 'V' || ch == 'v')
+                        fVerbose = true;
+                    else if (ch == '\0')
+                        break;
+                    /*else: ignore stuff we don't know what is */
+                }
+                /* else: skip spaces and unknown stuff */
+        }
+
+        /*
+         * Map the MMIO memory if found.
+         */
+        rc = vgdrvOS2MapMemory();
+        if (RT_SUCCESS(rc))
+        {
+            /*
+             * Initialize the device extension.
+             */
+            if (g_MemMapMMIO != NIL_RTR0MEMOBJ)
+                rc = VGDrvCommonInitDevExt(&g_DevExt, g_IOPortBase,
+                                           RTR0MemObjAddress(g_MemMapMMIO),
+                                           RTR0MemObjSize(g_MemMapMMIO),
+                                           vgdrvOS2DetectVersion(),
+                                           0);
+            else
+                rc = VGDrvCommonInitDevExt(&g_DevExt, g_IOPortBase, NULL, 0, vgdrvOS2DetectVersion(), 0);
+            if (RT_SUCCESS(rc))
+            {
+                /*
+                 * Initialize the session hash table.
+                 */
+                rc = RTSpinlockCreate(&g_Spinlock, RTSPINLOCK_FLAGS_INTERRUPT_SAFE, "VBoxGuestOS2");
+                if (RT_SUCCESS(rc))
+                {
+                    /*
+                     * Configure the interrupt handler.
+                     */
+                    if (g_bInterruptLine)
+                    {
+                        rc = vgdrvOS2DevHlpSetIRQ(g_bInterruptLine);
+                        if (rc)
+                        {
+                            Log(("vgdrvOS2DevHlpSetIRQ(%d) -> %d\n", g_bInterruptLine, rc));
+                            rc = RTErrConvertFromOS2(rc);
+                        }
+                    }
+                    if (RT_SUCCESS(rc))
+                    {
+                        /*
+                         * Read host configuration.
+                         */
+                        VGDrvCommonProcessOptionsFromHost(&g_DevExt);
+
+                        /*
+                         * Success
+                         */
+                        if (fVerbose)
+                        {
+                            strcpy(&g_szInitText[0],
+                                   "\r\n"
+                                   "VirtualBox Guest Additions Driver for OS/2 version " VBOX_VERSION_STRING "\r\n"
+                                   "Copyright (C) 2008-" VBOX_C_YEAR " " VBOX_VENDOR "\r\n");
+                            g_cchInitText = strlen(&g_szInitText[0]);
+                        }
+                        Log(("vgdrvOS2Init: Successfully loaded\n%s", g_szInitText));
+                        return VINF_SUCCESS;
+                    }
+
+                    g_cchInitText = RTStrPrintf(&g_szInitText[0], g_cchInitTextMax, "VBoxGuest.sys: SetIrq failed for IRQ %#d, rc=%Rrc\n",
+                                                g_bInterruptLine, rc);
+                }
+                else
+                    g_cchInitText = RTStrPrintf(&g_szInitText[0], g_cchInitTextMax, "VBoxGuest.sys: RTSpinlockCreate failed, rc=%Rrc\n", rc);
+                VGDrvCommonDeleteDevExt(&g_DevExt);
+            }
+            else
+                g_cchInitText = RTStrPrintf(&g_szInitText[0], g_cchInitTextMax, "VBoxGuest.sys: vgdrvOS2InitDevExt failed, rc=%Rrc\n", rc);
+
+            int rc2 = RTR0MemObjFree(g_MemObjMMIO, true /* fFreeMappings */); AssertRC(rc2);
+            g_MemObjMMIO = g_MemMapMMIO = NIL_RTR0MEMOBJ;
+        }
+        else
+            g_cchInitText = RTStrPrintf(&g_szInitText[0], g_cchInitTextMax, "VBoxGuest.sys: VBoxGuestOS2MapMMIO failed, rc=%Rrc\n", rc);
+        RTR0Term();
+    }
+    else
+        g_cchInitText = RTStrPrintf(&g_szInitText[0], g_cchInitTextMax, "VBoxGuest.sys: RTR0Init failed, rc=%Rrc\n", rc);
+
+    RTLogBackdoorPrintf("vgdrvOS2Init: failed rc=%Rrc - %s", rc, &g_szInitText[0]);
+    return rc;
+}
+
+
+/**
+ * Maps the VMMDev memory.
+ *
+ * @returns VBox status code.
+ * @retval  VERR_VERSION_MISMATCH       The VMMDev memory didn't meet our expectations.
+ */
+static int vgdrvOS2MapMemory(void)
+{
+    const RTCCPHYS PhysMMIOBase = g_PhysMMIOBase;
+
+    /*
+     * Did we find any MMIO region (0 or NIL)?
+     */
+    if (    !PhysMMIOBase
+        ||  PhysMMIOBase == NIL_RTCCPHYS)
+    {
+        Assert(g_MemMapMMIO != NIL_RTR0MEMOBJ);
+        return VINF_SUCCESS;
+    }
+
+    /*
+     * Create a physical memory object for it.
+     *
+     * Since we don't know the actual size (OS/2 doesn't at least), we make
+     * a qualified guess using the VMMDEV_RAM_SIZE.
+     */
+    size_t cb = RT_ALIGN_Z(VMMDEV_RAM_SIZE, PAGE_SIZE);
+    int rc = RTR0MemObjEnterPhys(&g_MemObjMMIO, PhysMMIOBase, cb, RTMEM_CACHE_POLICY_DONT_CARE);
+    if (RT_FAILURE(rc))
+    {
+        cb = _4K;
+        rc = RTR0MemObjEnterPhys(&g_MemObjMMIO, PhysMMIOBase, cb, RTMEM_CACHE_POLICY_DONT_CARE);
+    }
+    if (RT_FAILURE(rc))
+    {
+        Log(("vgdrvOS2MapMemory: RTR0MemObjEnterPhys(,%RCp,%zx) -> %Rrc\n", PhysMMIOBase, cb, rc));
+        return rc;
+    }
+
+    /*
+     * Map the object into kernel space.
+     *
+     * We want a normal mapping with normal caching, which good in two ways. First
+     * since the API doesn't have any flags indicating how the mapping should be cached.
+     * And second, because PGM doesn't necessarily respect the cache/writethru bits
+     * anyway for normal RAM.
+     */
+    rc = RTR0MemObjMapKernel(&g_MemMapMMIO, g_MemObjMMIO, (void *)-1, 0, RTMEM_PROT_READ | RTMEM_PROT_WRITE);
+    if (RT_SUCCESS(rc))
+    {
+        /*
+         * Validate the VMM memory.
+         */
+        VMMDevMemory *pVMMDev = (VMMDevMemory *)RTR0MemObjAddress(g_MemMapMMIO);
+        Assert(pVMMDev);
+        if (    pVMMDev->u32Version == VMMDEV_MEMORY_VERSION
+            &&  pVMMDev->u32Size >= 32 /* just for checking sanity */)
+        {
+            /*
+             * Did we hit the correct size? If not we'll have to
+             * redo the mapping using the correct size.
+             */
+            if (RT_ALIGN_32(pVMMDev->u32Size, PAGE_SIZE) == cb)
+                return VINF_SUCCESS;
+
+            Log(("vgdrvOS2MapMemory: Actual size %#RX32 (tried %#zx)\n", pVMMDev->u32Size, cb));
+            cb = RT_ALIGN_32(pVMMDev->u32Size, PAGE_SIZE);
+
+            rc = RTR0MemObjFree(g_MemObjMMIO, true); AssertRC(rc);
+            g_MemObjMMIO = g_MemMapMMIO = NIL_RTR0MEMOBJ;
+
+            rc = RTR0MemObjEnterPhys(&g_MemObjMMIO, PhysMMIOBase, cb, RTMEM_CACHE_POLICY_DONT_CARE);
+            if (RT_SUCCESS(rc))
+            {
+                rc = RTR0MemObjMapKernel(&g_MemMapMMIO, g_MemObjMMIO, (void *)-1, 0, RTMEM_PROT_READ | RTMEM_PROT_WRITE);
+                if (RT_SUCCESS(rc))
+                    return VINF_SUCCESS;
+
+                Log(("vgdrvOS2MapMemory: RTR0MemObjMapKernel [%RCp,%zx] -> %Rrc (2nd)\n", PhysMMIOBase, cb, rc));
+            }
+            else
+                Log(("vgdrvOS2MapMemory: RTR0MemObjEnterPhys(,%RCp,%zx) -> %Rrc (2nd)\n", PhysMMIOBase, cb, rc));
+        }
+        else
+        {
+            rc = VERR_VERSION_MISMATCH;
+            LogRel(("vgdrvOS2MapMemory: Bogus VMMDev memory; u32Version=%RX32 (expected %RX32) u32Size=%RX32\n",
+                    pVMMDev->u32Version, VMMDEV_MEMORY_VERSION, pVMMDev->u32Size));
+        }
+    }
+    else
+        Log(("vgdrvOS2MapMemory: RTR0MemObjMapKernel [%RCp,%zx] -> %Rrc\n", PhysMMIOBase, cb, rc));
+
+    int rc2 = RTR0MemObjFree(g_MemObjMMIO, true /* fFreeMappings */); AssertRC(rc2);
+    g_MemObjMMIO = g_MemMapMMIO = NIL_RTR0MEMOBJ;
+    return rc;
+}
+
+
+/**
+ * Called fromn vgdrvOS2Init to determine which OS/2 version this is.
+ *
+ * @returns VBox OS/2 type.
+ */
+static VBOXOSTYPE vgdrvOS2DetectVersion(void)
+{
+    VBOXOSTYPE enmOSType = VBOXOSTYPE_OS2;
+
+#if 0 /** @todo dig up the version stuff from GIS later and verify that the numbers are actually decimal. */
+    unsigned uMajor, uMinor;
+    if (uMajor == 2)
+    {
+        if (uMinor >= 30 && uMinor < 40)
+            enmOSType = VBOXOSTYPE_OS2Warp3;
+        else if (uMinor >= 40 && uMinor < 45)
+            enmOSType = VBOXOSTYPE_OS2Warp4;
+        else if (uMinor >= 45 && uMinor < 50)
+            enmOSType = VBOXOSTYPE_OS2Warp45;
+    }
+#endif
+    return enmOSType;
+}
+
+
+DECLASM(int) vgdrvOS2Open(uint16_t sfn)
+{
+    int                 rc;
+    PVBOXGUESTSESSION   pSession;
+
+    /*
+     * Create a new session.
+     */
+    uint32_t fRequestor = VMMDEV_REQUESTOR_USERMODE
+                        | VMMDEV_REQUESTOR_TRUST_NOT_GIVEN
+                        | VMMDEV_REQUESTOR_USR_ROOT  /* everyone is root on OS/2 */
+                        | VMMDEV_REQUESTOR_GRP_WHEEL /* and their admins */
+                        | VMMDEV_REQUESTOR_NO_USER_DEVICE /** @todo implement /dev/vboxuser? */
+                        | VMMDEV_REQUESTOR_CON_DONT_KNOW; /** @todo check screen group/whatever of process to see if console */
+    rc = VGDrvCommonCreateUserSession(&g_DevExt, fRequestor, &pSession);
+    if (RT_SUCCESS(rc))
+    {
+        pSession->sfn = sfn;
+
+        /*
+         * Insert it into the hash table.
+         */
+        unsigned iHash = SESSION_HASH(sfn);
+        RTSpinlockAcquire(g_Spinlock);
+        pSession->pNextHash = g_apSessionHashTab[iHash];
+        g_apSessionHashTab[iHash] = pSession;
+        RTSpinlockRelease(g_Spinlock);
+    }
+
+    Log(("vgdrvOS2Open: g_DevExt=%p pSession=%p rc=%d pid=%d\n", &g_DevExt, pSession, rc, (int)RTProcSelf()));
+    return rc;
+}
+
+
+DECLASM(int) vgdrvOS2Close(uint16_t sfn)
+{
+    Log(("vgdrvOS2Close: pid=%d sfn=%d\n", (int)RTProcSelf(), sfn));
+
+    /*
+     * Remove from the hash table.
+     */
+    PVBOXGUESTSESSION   pSession;
+    const RTPROCESS     Process = RTProcSelf();
+    const unsigned      iHash = SESSION_HASH(sfn);
+    RTSpinlockAcquire(g_Spinlock);
+
+    pSession = g_apSessionHashTab[iHash];
+    if (pSession)
+    {
+        if (    pSession->sfn == sfn
+            &&  pSession->Process == Process)
+        {
+            g_apSessionHashTab[iHash] = pSession->pNextHash;
+            pSession->pNextHash = NULL;
+        }
+        else
+        {
+            PVBOXGUESTSESSION pPrev = pSession;
+            pSession = pSession->pNextHash;
+            while (pSession)
+            {
+                if (    pSession->sfn == sfn
+                    &&  pSession->Process == Process)
+                {
+                    pPrev->pNextHash = pSession->pNextHash;
+                    pSession->pNextHash = NULL;
+                    break;
+                }
+
+                /* next */
+                pPrev = pSession;
+                pSession = pSession->pNextHash;
+            }
+        }
+    }
+    RTSpinlockRelease(g_Spinlock);
+    if (!pSession)
+    {
+        Log(("VBoxGuestIoctl: WHUT?!? pSession == NULL! This must be a mistake... pid=%d sfn=%d\n", (int)Process, sfn));
+        return VERR_INVALID_PARAMETER;
+    }
+
+    /*
+     * Close the session.
+     */
+    VGDrvCommonCloseSession(&g_DevExt, pSession);
+    return 0;
+}
+
+
+DECLASM(int) vgdrvOS2IOCtlFast(uint16_t sfn, uint8_t iFunction, int32_t *prc)
+{
+    /*
+     * Find the session.
+     */
+    const RTPROCESS     Process = RTProcSelf();
+    const unsigned      iHash = SESSION_HASH(sfn);
+    PVBOXGUESTSESSION   pSession;
+
+    RTSpinlockAcquire(g_Spinlock);
+    pSession = g_apSessionHashTab[iHash];
+    if (pSession && pSession->Process != Process)
+    {
+        do pSession = pSession->pNextHash;
+        while (     pSession
+               &&   (   pSession->sfn != sfn
+                     || pSession->Process != Process));
+    }
+    RTSpinlockRelease(g_Spinlock);
+    if (RT_UNLIKELY(!pSession))
+    {
+        Log(("VBoxGuestIoctl: WHAT?!? pSession == NULL! This must be a mistake... pid=%d\n", (int)Process));
+        return VERR_INVALID_PARAMETER;
+    }
+
+    /*
+     * Dispatch the fast IOCtl.
+     */
+    *prc = VGDrvCommonIoCtlFast(iFunction, &g_DevExt, pSession);
+    return 0;
+}
+
+
+/**
+ * 32-bit IDC service routine.
+ *
+ * @returns VBox status code.
+ * @param   u32Session          The session handle (PVBOXGUESTSESSION).
+ * @param   iFunction           The requested function.
+ * @param   pReqHdr             The input/output data buffer.  The caller
+ *                              ensures that this cannot be swapped out, or that
+ *                              it's acceptable to take a page in fault in the
+ *                              current context.  If the request doesn't take
+ *                              input or produces output, apssing NULL is okay.
+ * @param   cbReq               The size of the data buffer.
+ *
+ * @remark  This is called from the 16-bit thunker as well as directly from the 32-bit clients.
+ */
+DECLASM(int) VGDrvOS2IDCService(uint32_t u32Session, unsigned iFunction, PVBGLREQHDR pReqHdr, size_t cbReq)
+{
+    PVBOXGUESTSESSION pSession = (PVBOXGUESTSESSION)u32Session;
+    AssertPtrReturn(pSession, VERR_INVALID_POINTER);
+    AssertMsgReturn(pSession->sfn == 0xffff, ("%RX16\n", pSession->sfn), VERR_INVALID_HANDLE);
+    AssertMsgReturn(pSession->pDevExt == &g_DevExt, ("%p != %p\n", pSession->pDevExt, &g_DevExt), VERR_INVALID_HANDLE);
+
+    return VGDrvCommonIoCtl(iFunction, &g_DevExt, pSession, pReqHdr, cbReq);
+}
+
+
+/**
+ * Worker for VBoxGuestOS2IDC, it creates the kernel session.
+ *
+ * @returns Pointer to the session.
+ */
+DECLASM(PVBOXGUESTSESSION) vgdrvOS2IDCConnect(void)
+{
+    PVBOXGUESTSESSION pSession;
+    int rc = VGDrvCommonCreateKernelSession(&g_DevExt, &pSession);
+    if (RT_SUCCESS(rc))
+    {
+        pSession->sfn = 0xffff;
+        return pSession;
+    }
+    return NULL;
+}
+
+
+DECLASM(int) vgdrvOS2IOCtl(uint16_t sfn, uint8_t iCat, uint8_t iFunction, void *pvParm, void *pvData,
+                           uint16_t *pcbParm, uint16_t *pcbData)
+{
+    /*
+     * Find the session.
+     */
+    const RTPROCESS     Process = RTProcSelf();
+    const unsigned      iHash = SESSION_HASH(sfn);
+    PVBOXGUESTSESSION   pSession;
+
+    RTSpinlockAcquire(g_Spinlock);
+    pSession = g_apSessionHashTab[iHash];
+    if (pSession && pSession->Process != Process)
+    {
+        do pSession = pSession->pNextHash;
+        while (     pSession
+               &&   (   pSession->sfn != sfn
+                     || pSession->Process != Process));
+    }
+    RTSpinlockRelease(g_Spinlock);
+    if (!pSession)
+    {
+        Log(("VBoxGuestIoctl: WHAT?!? pSession == NULL! This must be a mistake... pid=%d\n", (int)Process));
+        return VERR_INVALID_PARAMETER;
+    }
+
+    /*
+     * Verify the category and dispatch the IOCtl.
+     *
+     * The IOCtl call uses the parameter buffer as generic data input/output
+     * buffer similar to the one unix ioctl buffer argument.  While the data
+     * buffer is not used.
+     */
+    if (RT_LIKELY(iCat == VBGL_IOCTL_CATEGORY))
+    {
+        Log(("vgdrvOS2IOCtl: pSession=%p iFunction=%#x pvParm=%p pvData=%p *pcbParm=%d *pcbData=%d\n", pSession, iFunction, pvParm, pvData, *pcbParm, *pcbData));
+        if (   pvParm
+            && *pcbParm >= sizeof(VBGLREQHDR)
+            && *pcbData == 0)
+        {
+            /*
+             * Lock the buffer.
+             */
+            KernVMLock_t ParmLock;
+            int32_t rc = KernVMLock(VMDHL_WRITE, pvParm, *pcbParm, &ParmLock, (KernPageList_t *)-1, NULL);
+            if (rc == 0)
+            {
+                /*
+                 * Process the IOCtl.
+                 */
+                PVBGLREQHDR pReqHdr = (PVBGLREQHDR)pvParm;
+                rc = VGDrvCommonIoCtl(iFunction, &g_DevExt, pSession, pReqHdr, *pcbParm);
+
+                /*
+                 * Unlock the buffer.
+                 */
+                *pcbParm = RT_SUCCESS(rc) ? pReqHdr->cbOut : sizeof(*pReqHdr);
+                int rc2 = KernVMUnlock(&ParmLock);
+                AssertMsg(rc2 == 0, ("rc2=%d\n", rc2)); NOREF(rc2);
+
+                Log2(("vgdrvOS2IOCtl: returns %d\n", rc));
+                return rc;
+            }
+            AssertMsgFailed(("KernVMLock(VMDHL_WRITE, %p, %#x, &p, NULL, NULL) -> %d\n", pvParm, *pcbParm, &ParmLock, rc));
+            return VERR_LOCK_FAILED;
+        }
+        Log2(("vgdrvOS2IOCtl: returns VERR_INVALID_PARAMETER (iFunction=%#x)\n", iFunction));
+        return VERR_INVALID_PARAMETER;
+    }
+    return VERR_NOT_SUPPORTED;
+}
+
+
+/**
+ * 32-bit ISR, called by 16-bit assembly thunker in VBoxGuestA-os2.asm.
+ *
+ * @returns true if it's our interrupt, false it isn't.
+ */
+DECLASM(bool) vgdrvOS2ISR(void)
+{
+    Log(("vgdrvOS2ISR\n"));
+
+    return VGDrvCommonISR(&g_DevExt);
+}
+
+
+void VGDrvNativeISRMousePollEvent(PVBOXGUESTDEVEXT pDevExt)
+{
+    /* No polling on OS/2 */
+    NOREF(pDevExt);
+}
+
+
+bool VGDrvNativeProcessOption(PVBOXGUESTDEVEXT pDevExt, const char *pszName, const char *pszValue)
+{
+    RT_NOREF(pDevExt); RT_NOREF(pszName); RT_NOREF(pszValue);
+    return false;
+}
+
+
+#ifdef DEBUG_READ /** @todo figure out this one once and for all... */
+
+/**
+ * Callback for writing to the log buffer.
+ *
+ * @returns number of bytes written.
+ * @param   pvArg       Unused.
+ * @param   pachChars   Pointer to an array of utf-8 characters.
+ * @param   cbChars     Number of bytes in the character array pointed to by pachChars.
+ */
+static DECLCALLBACK(size_t) vgdrvOS2LogOutput(void *pvArg, const char *pachChars, size_t cbChars)
+{
+    size_t cchWritten = 0;
+    while (cbChars-- > 0)
+    {
+        const uint16_t offLogHead = g_offLogHead;
+        const uint16_t offLogHeadNext = (offLogHead + 1) & (g_cchLogMax - 1);
+        if (offLogHeadNext == g_offLogTail)
+            break; /* no */
+        g_szLog[offLogHead] = *pachChars++;
+        g_offLogHead = offLogHeadNext;
+        cchWritten++;
+    }
+    return cchWritten;
+}
+
+
+int SUPR0Printf(const char *pszFormat, ...)
+{
+    va_list va;
+
+#if 0 //def DEBUG_bird
+    va_start(va, pszFormat);
+    RTLogComPrintfV(pszFormat, va);
+    va_end(va);
+#endif
+
+    va_start(va, pszFormat);
+    int cch = RTLogFormatV(vgdrvOS2LogOutput, NULL, pszFormat, va);
+    va_end(va);
+
+    return cch;
+}
+
+#endif /* DEBUG_READ */
+
diff --git a/src/VBox/Additions/common/VBoxGuest/VBoxGuest-os2.def b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-os2.def
new file mode 100644
index 00000000..dde341fe
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-os2.def
@@ -0,0 +1,55 @@
+; $Id: VBoxGuest-os2.def $
+;; @file
+; VBoxGuest - OS/2 definition file.
+;
+
+;
+; Copyright (C) 2007-2023 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
+;
+
+
+PHYSICAL DEVICE VBoxGst
+DESCRIPTION 'VirtualBox Guest Additions Driver for OS/2.'
+CODE PRELOAD EXECUTEREAD
+DATA PRELOAD
+; We're using wlink.exe, so this doesn't work.
+;SEGMENTS
+;    DATA16              class 'FAR_DATA'
+;    DATA16_INIT         class 'FAR_DATA'
+;
+;    CODE16              class 'CODE'
+;    CODE16_INIT         class 'CODE'
+;
+;    CODE32              class 'CODE'
+;    TEXT32              class 'CODE'
+;
+;    DATA32              class 'DATA'
+;    BSS32               class 'BSS'
+
diff --git a/src/VBox/Additions/common/VBoxGuest/VBoxGuest-solaris.c b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-solaris.c
new file mode 100644
index 00000000..b28f9382
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-solaris.c
@@ -0,0 +1,1138 @@
+/* $Id: VBoxGuest-solaris.c $ */
+/** @file
+ * VirtualBox Guest Additions Driver for Solaris.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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/conf.h>
+#include <sys/modctl.h>
+#include <sys/mutex.h>
+#include <sys/pci.h>
+#include <sys/stat.h>
+#include <sys/ddi.h>
+#include <sys/ddi_intr.h>
+#include <sys/sunddi.h>
+#include <sys/open.h>
+#include <sys/sunldi.h>
+#include <sys/policy.h>
+#include <sys/file.h>
+#undef u /* /usr/include/sys/user.h:249:1 is where this is defined to (curproc->p_user). very cool. */
+
+#include "VBoxGuestInternal.h"
+#include <VBox/log.h>
+#include <VBox/version.h>
+#include <iprt/assert.h>
+#include <iprt/initterm.h>
+#include <iprt/process.h>
+#include <iprt/mem.h>
+#include <iprt/cdefs.h>
+#include <iprt/asm.h>
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+/** The module name. */
+#define DEVICE_NAME              "vboxguest"
+/** The module description as seen in 'modinfo'. */
+#define DEVICE_DESC              "VirtualBox GstDrv"
+
+
+/*********************************************************************************************************************************
+*   Internal Functions                                                                                                           *
+*********************************************************************************************************************************/
+static int vgdrvSolarisOpen(dev_t *pDev, int fFlag, int fType, cred_t *pCred);
+static int vgdrvSolarisClose(dev_t Dev, int fFlag, int fType, cred_t *pCred);
+static int vgdrvSolarisRead(dev_t Dev, struct uio *pUio, cred_t *pCred);
+static int vgdrvSolarisWrite(dev_t Dev, struct uio *pUio, cred_t *pCred);
+static int vgdrvSolarisIOCtl(dev_t Dev, int iCmd, intptr_t pArg, int Mode, cred_t *pCred, int *pVal);
+static int vgdrvSolarisIOCtlSlow(PVBOXGUESTSESSION pSession, int iCmd, int Mode, intptr_t iArgs);
+static int vgdrvSolarisPoll(dev_t Dev, short fEvents, int fAnyYet, short *pReqEvents, struct pollhead **ppPollHead);
+
+static int vgdrvSolarisGetInfo(dev_info_t *pDip, ddi_info_cmd_t enmCmd, void *pArg, void **ppResult);
+static int vgdrvSolarisAttach(dev_info_t *pDip, ddi_attach_cmd_t enmCmd);
+static int vgdrvSolarisDetach(dev_info_t *pDip, ddi_detach_cmd_t enmCmd);
+static int vgdrvSolarisQuiesce(dev_info_t *pDip);
+
+static int vgdrvSolarisAddIRQ(dev_info_t *pDip);
+static void vgdrvSolarisRemoveIRQ(dev_info_t *pDip);
+static uint_t vgdrvSolarisHighLevelISR(caddr_t Arg);
+static uint_t vgdrvSolarisISR(caddr_t Arg);
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * cb_ops: for drivers that support char/block entry points
+ */
+static struct cb_ops g_vgdrvSolarisCbOps =
+{
+    vgdrvSolarisOpen,
+    vgdrvSolarisClose,
+    nodev,                  /* b strategy */
+    nodev,                  /* b dump */
+    nodev,                  /* b print */
+    vgdrvSolarisRead,
+    vgdrvSolarisWrite,
+    vgdrvSolarisIOCtl,
+    nodev,                  /* c devmap */
+    nodev,                  /* c mmap */
+    nodev,                  /* c segmap */
+    vgdrvSolarisPoll,
+    ddi_prop_op,            /* property ops */
+    NULL,                   /* streamtab  */
+    D_NEW | D_MP,           /* compat. flag */
+    CB_REV                  /* revision */
+};
+
+/**
+ * dev_ops: for driver device operations
+ */
+static struct dev_ops g_vgdrvSolarisDevOps =
+{
+    DEVO_REV,               /* driver build revision */
+    0,                      /* ref count */
+    vgdrvSolarisGetInfo,
+    nulldev,                /* identify */
+    nulldev,                /* probe */
+    vgdrvSolarisAttach,
+    vgdrvSolarisDetach,
+    nodev,                  /* reset */
+    &g_vgdrvSolarisCbOps,
+    (struct bus_ops *)0,
+    nodev,                  /* power */
+    vgdrvSolarisQuiesce
+};
+
+/**
+ * modldrv: export driver specifics to the kernel
+ */
+static struct modldrv g_vgdrvSolarisModule =
+{
+    &mod_driverops,         /* extern from kernel */
+    DEVICE_DESC " " VBOX_VERSION_STRING "r" RT_XSTR(VBOX_SVN_REV),
+    &g_vgdrvSolarisDevOps
+};
+
+/**
+ * modlinkage: export install/remove/info to the kernel
+ */
+static struct modlinkage g_vgdrvSolarisModLinkage =
+{
+    MODREV_1,               /* loadable module system revision */
+    &g_vgdrvSolarisModule,
+    NULL                    /* terminate array of linkage structures */
+};
+
+/**
+ * State info for each open file handle.
+ */
+typedef struct
+{
+    /** Pointer to the session handle. */
+    PVBOXGUESTSESSION       pSession;
+    /** The process reference for posting signals */
+    void                   *pvProcRef;
+} vboxguest_state_t;
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/** Device handle (we support only one instance). */
+static dev_info_t          *g_pDip = NULL;
+/** Opaque pointer to file-descriptor states */
+static void                *g_pvgdrvSolarisState = NULL;
+/** Device extention & session data association structure. */
+static VBOXGUESTDEVEXT      g_DevExt;
+/** IO port handle. */
+static ddi_acc_handle_t     g_PciIOHandle;
+/** MMIO handle. */
+static ddi_acc_handle_t     g_PciMMIOHandle;
+/** IO Port. */
+static uint16_t             g_uIOPortBase;
+/** Address of the MMIO region.*/
+static caddr_t              g_pMMIOBase;
+/** Size of the MMIO region. */
+static off_t                g_cbMMIO;
+/** Pointer to an array of interrupt handles. */
+static ddi_intr_handle_t   *g_pahIntrs;
+/** Handle to the soft interrupt. */
+static ddi_softint_handle_t g_hSoftIntr;
+/** The pollhead structure */
+static pollhead_t           g_PollHead;
+/** The IRQ Mutex */
+static kmutex_t             g_IrqMtx;
+/** The IRQ high-level Mutex. */
+static kmutex_t             g_HighLevelIrqMtx;
+/** Whether soft-ints are setup. */
+static bool                 g_fSoftIntRegistered = false;
+
+/** Additional IPRT function we need to drag in for vboxfs. */
+PFNRT g_Deps[] =
+{
+    (PFNRT)RTErrConvertToErrno,
+};
+
+
+/**
+ * Kernel entry points
+ */
+int _init(void)
+{
+    /*
+     * Initialize IPRT R0 driver, which internally calls OS-specific r0 init.
+     */
+    int rc = RTR0Init(0);
+    if (RT_SUCCESS(rc))
+    {
+        PRTLOGGER pRelLogger;
+        static const char * const s_apszGroups[] = VBOX_LOGGROUP_NAMES;
+        rc = RTLogCreate(&pRelLogger, 0 /* fFlags */, "all",
+                         "VBOX_RELEASE_LOG", RT_ELEMENTS(s_apszGroups), s_apszGroups,
+                         RTLOGDEST_STDOUT | RTLOGDEST_DEBUGGER, NULL);
+        if (RT_SUCCESS(rc))
+            RTLogRelSetDefaultInstance(pRelLogger);
+        else
+            cmn_err(CE_NOTE, "failed to initialize driver logging rc=%d!\n", rc);
+
+        /*
+         * Prevent module autounloading.
+         */
+        modctl_t *pModCtl = mod_getctl(&g_vgdrvSolarisModLinkage);
+        if (pModCtl)
+            pModCtl->mod_loadflags |= MOD_NOAUTOUNLOAD;
+        else
+            LogRel((DEVICE_NAME ": failed to disable autounloading!\n"));
+
+        rc = ddi_soft_state_init(&g_pvgdrvSolarisState, sizeof(vboxguest_state_t), 1);
+        if (!rc)
+        {
+            rc = mod_install(&g_vgdrvSolarisModLinkage);
+            if (rc)
+                ddi_soft_state_fini(&g_pvgdrvSolarisState);
+        }
+    }
+    else
+    {
+        cmn_err(CE_NOTE, "_init: RTR0Init failed. rc=%d\n", rc);
+        return EINVAL;
+    }
+
+    return rc;
+}
+
+
+int _fini(void)
+{
+    LogFlow((DEVICE_NAME ":_fini\n"));
+    int rc = mod_remove(&g_vgdrvSolarisModLinkage);
+    if (!rc)
+        ddi_soft_state_fini(&g_pvgdrvSolarisState);
+
+    RTLogDestroy(RTLogRelSetDefaultInstance(NULL));
+    RTLogDestroy(RTLogSetDefaultInstance(NULL));
+
+    if (!rc)
+        RTR0Term();
+    return rc;
+}
+
+
+int _info(struct modinfo *pModInfo)
+{
+    /* LogFlow((DEVICE_NAME ":_info\n")); - Called too early, causing RTThreadPreemtIsEnabled warning. */
+    return mod_info(&g_vgdrvSolarisModLinkage, pModInfo);
+}
+
+
+/**
+ * Attach entry point, to attach a device to the system or resume it.
+ *
+ * @param   pDip            The module structure instance.
+ * @param   enmCmd          Attach type (ddi_attach_cmd_t)
+ *
+ * @return  corresponding solaris error code.
+ */
+static int vgdrvSolarisAttach(dev_info_t *pDip, ddi_attach_cmd_t enmCmd)
+{
+    LogFlow(("vgdrvSolarisAttach:\n"));
+    switch (enmCmd)
+    {
+        case DDI_ATTACH:
+        {
+            if (g_pDip)
+            {
+                LogRel(("vgdrvSolarisAttach: Only one instance supported.\n"));
+                return DDI_FAILURE;
+            }
+
+            /*
+             * Enable resources for PCI access.
+             */
+            ddi_acc_handle_t PciHandle;
+            int rc = pci_config_setup(pDip, &PciHandle);
+            if (rc == DDI_SUCCESS)
+            {
+                /*
+                 * Map the register address space.
+                 */
+                caddr_t baseAddr;
+                ddi_device_acc_attr_t deviceAttr;
+                deviceAttr.devacc_attr_version = DDI_DEVICE_ATTR_V0;
+                deviceAttr.devacc_attr_endian_flags = DDI_NEVERSWAP_ACC;
+                deviceAttr.devacc_attr_dataorder = DDI_STRICTORDER_ACC;
+                deviceAttr.devacc_attr_access = DDI_DEFAULT_ACC;
+                rc = ddi_regs_map_setup(pDip, 1, &baseAddr, 0, 0, &deviceAttr, &g_PciIOHandle);
+                if (rc == DDI_SUCCESS)
+                {
+                    /*
+                     * Read size of the MMIO region.
+                     */
+                    g_uIOPortBase = (uintptr_t)baseAddr;
+                    rc = ddi_dev_regsize(pDip, 2, &g_cbMMIO);
+                    if (rc == DDI_SUCCESS)
+                    {
+                        rc = ddi_regs_map_setup(pDip, 2, &g_pMMIOBase, 0, g_cbMMIO, &deviceAttr, &g_PciMMIOHandle);
+                        if (rc == DDI_SUCCESS)
+                        {
+                            /*
+                             * Call the common device extension initializer.
+                             */
+                            rc = VGDrvCommonInitDevExt(&g_DevExt, g_uIOPortBase, g_pMMIOBase, g_cbMMIO,
+#if ARCH_BITS == 64
+                                                       VBOXOSTYPE_Solaris_x64,
+#else
+                                                       VBOXOSTYPE_Solaris,
+#endif
+                                                       VMMDEV_EVENT_MOUSE_POSITION_CHANGED);
+                            if (RT_SUCCESS(rc))
+                            {
+                                /*
+                                 * Add IRQ of VMMDev.
+                                 */
+                                rc = vgdrvSolarisAddIRQ(pDip);
+                                if (rc == DDI_SUCCESS)
+                                {
+                                    /*
+                                     * Read host configuration.
+                                     */
+                                    VGDrvCommonProcessOptionsFromHost(&g_DevExt);
+
+                                    rc = ddi_create_minor_node(pDip, DEVICE_NAME, S_IFCHR, 0 /* instance */, DDI_PSEUDO,
+                                                               0 /* fFlags */);
+                                    if (rc == DDI_SUCCESS)
+                                    {
+                                        g_pDip = pDip;
+                                        pci_config_teardown(&PciHandle);
+                                        return DDI_SUCCESS;
+                                    }
+
+                                    LogRel((DEVICE_NAME "::Attach: ddi_create_minor_node failed.\n"));
+                                    vgdrvSolarisRemoveIRQ(pDip);
+                                }
+                                else
+                                    LogRel((DEVICE_NAME "::Attach: vgdrvSolarisAddIRQ failed.\n"));
+                                VGDrvCommonDeleteDevExt(&g_DevExt);
+                            }
+                            else
+                                LogRel((DEVICE_NAME "::Attach: VGDrvCommonInitDevExt failed.\n"));
+                            ddi_regs_map_free(&g_PciMMIOHandle);
+                        }
+                        else
+                            LogRel((DEVICE_NAME "::Attach: ddi_regs_map_setup for MMIO region failed.\n"));
+                    }
+                    else
+                        LogRel((DEVICE_NAME "::Attach: ddi_dev_regsize for MMIO region failed.\n"));
+                    ddi_regs_map_free(&g_PciIOHandle);
+                }
+                else
+                    LogRel((DEVICE_NAME "::Attach: ddi_regs_map_setup for IOport failed.\n"));
+                pci_config_teardown(&PciHandle);
+            }
+            else
+                LogRel((DEVICE_NAME "::Attach: pci_config_setup failed rc=%d.\n", rc));
+            return DDI_FAILURE;
+        }
+
+        case DDI_RESUME:
+        {
+            /** @todo implement resume for guest driver. */
+            return DDI_SUCCESS;
+        }
+
+        default:
+            return DDI_FAILURE;
+    }
+}
+
+
+/**
+ * Detach entry point, to detach a device to the system or suspend it.
+ *
+ * @param   pDip            The module structure instance.
+ * @param   enmCmd          Attach type (ddi_attach_cmd_t)
+ *
+ * @return  corresponding solaris error code.
+ */
+static int vgdrvSolarisDetach(dev_info_t *pDip, ddi_detach_cmd_t enmCmd)
+{
+    LogFlow(("vgdrvSolarisDetach:\n"));
+    switch (enmCmd)
+    {
+        case DDI_DETACH:
+        {
+            vgdrvSolarisRemoveIRQ(pDip);
+            ddi_regs_map_free(&g_PciIOHandle);
+            ddi_regs_map_free(&g_PciMMIOHandle);
+            ddi_remove_minor_node(pDip, NULL);
+            VGDrvCommonDeleteDevExt(&g_DevExt);
+            g_pDip = NULL;
+            return DDI_SUCCESS;
+        }
+
+        case DDI_SUSPEND:
+        {
+            /** @todo implement suspend for guest driver. */
+            return DDI_SUCCESS;
+        }
+
+        default:
+            return DDI_FAILURE;
+    }
+}
+
+
+/**
+ * Quiesce entry point, called by solaris kernel for disabling the device from
+ * generating any interrupts or doing in-bound DMA.
+ *
+ * @param   pDip            The module structure instance.
+ *
+ * @return  corresponding solaris error code.
+ */
+static int vgdrvSolarisQuiesce(dev_info_t *pDip)
+{
+    int rc = ddi_intr_disable(g_pahIntrs[0]);
+    if (rc != DDI_SUCCESS)
+        return DDI_FAILURE;
+
+    /** @todo What about HGCM/HGSMI touching guest-memory? */
+
+    return DDI_SUCCESS;
+}
+
+
+/**
+ * Info entry point, called by solaris kernel for obtaining driver info.
+ *
+ * @param   pDip            The module structure instance (do not use).
+ * @param   enmCmd          Information request type.
+ * @param   pvArg           Type specific argument.
+ * @param   ppvResult       Where to store the requested info.
+ *
+ * @return  corresponding solaris error code.
+ */
+static int vgdrvSolarisGetInfo(dev_info_t *pDip, ddi_info_cmd_t enmCmd, void *pvArg, void **ppvResult)
+{
+    LogFlow(("vgdrvSolarisGetInfo:\n"));
+
+    int rc = DDI_SUCCESS;
+    switch (enmCmd)
+    {
+        case DDI_INFO_DEVT2DEVINFO:
+        {
+            *ppvResult = (void *)g_pDip;
+            if (!*ppvResult)
+                rc = DDI_FAILURE;
+            break;
+        }
+
+        case DDI_INFO_DEVT2INSTANCE:
+        {
+            /* There can only be a single-instance of this driver and thus its instance number is 0. */
+            *ppvResult = (void *)0;
+            break;
+        }
+
+        default:
+            rc = DDI_FAILURE;
+            break;
+    }
+
+    NOREF(pvArg);
+    return rc;
+}
+
+
+/**
+ * User context entry points
+ *
+ * @remarks fFlags are the flags passed to open() or to ldi_open_by_name.  In
+ *          the latter case the FKLYR flag is added to indicate that the caller
+ *          is a kernel component rather than user land.
+ */
+static int vgdrvSolarisOpen(dev_t *pDev, int fFlags, int fType, cred_t *pCred)
+{
+    int                 rc;
+    PVBOXGUESTSESSION   pSession = NULL;
+
+    LogFlow(("vgdrvSolarisOpen:\n"));
+
+    /*
+     * Verify we are being opened as a character device.
+     */
+    if (fType != OTYP_CHR)
+        return EINVAL;
+
+    vboxguest_state_t *pState = NULL;
+    unsigned iOpenInstance;
+    for (iOpenInstance = 0; iOpenInstance < 4096; iOpenInstance++)
+    {
+        if (    !ddi_get_soft_state(g_pvgdrvSolarisState, iOpenInstance) /* faster */
+            &&  ddi_soft_state_zalloc(g_pvgdrvSolarisState, iOpenInstance) == DDI_SUCCESS)
+        {
+            pState = ddi_get_soft_state(g_pvgdrvSolarisState, iOpenInstance);
+            break;
+        }
+    }
+    if (!pState)
+    {
+        Log(("vgdrvSolarisOpen: too many open instances."));
+        return ENXIO;
+    }
+
+    /*
+     * Create a new session.
+     *
+     * Note! The devfs inode with the gid isn't readily available here, so we cannot easily
+     *       to the vbox group detection like on linux.  Read config instead?
+     */
+    if (!(fFlags & FKLYR))
+    {
+        uint32_t fRequestor = VMMDEV_REQUESTOR_USERMODE | VMMDEV_REQUESTOR_TRUST_NOT_GIVEN;
+        if (crgetruid(pCred) == 0)
+            fRequestor |= VMMDEV_REQUESTOR_USR_ROOT;
+        else
+            fRequestor |= VMMDEV_REQUESTOR_USR_USER;
+        if (secpolicy_coreadm(pCred) == 0)
+            fRequestor |= VMMDEV_REQUESTOR_GRP_WHEEL;
+        /** @todo is there any way of detecting that the process belongs to someone on the physical console?
+         * secpolicy_console() [== PRIV_SYS_DEVICES] doesn't look quite right, or does it? */
+        fRequestor |= VMMDEV_REQUESTOR_CON_DONT_KNOW;
+        fRequestor |= VMMDEV_REQUESTOR_NO_USER_DEVICE; /** @todo implement vboxuser device node. */
+
+        rc = VGDrvCommonCreateUserSession(&g_DevExt, fRequestor, &pSession);
+    }
+    else
+        rc = VGDrvCommonCreateKernelSession(&g_DevExt, &pSession);
+    if (RT_SUCCESS(rc))
+    {
+        if (!(fFlags & FKLYR))
+            pState->pvProcRef = proc_ref();
+        else
+            pState->pvProcRef = NULL;
+        pState->pSession = pSession;
+        *pDev = makedevice(getmajor(*pDev), iOpenInstance);
+        Log(("vgdrvSolarisOpen: pSession=%p pState=%p pid=%d\n", pSession, pState, (int)RTProcSelf()));
+        return 0;
+    }
+
+    /* Failed, clean up. */
+    ddi_soft_state_free(g_pvgdrvSolarisState, iOpenInstance);
+
+    LogRel((DEVICE_NAME "::Open: VGDrvCommonCreateUserSession failed. rc=%d\n", rc));
+    return EFAULT;
+}
+
+
+static int vgdrvSolarisClose(dev_t Dev, int flag, int fType, cred_t *pCred)
+{
+    LogFlow(("vgdrvSolarisClose: pid=%d\n", (int)RTProcSelf()));
+
+    PVBOXGUESTSESSION pSession = NULL;
+    vboxguest_state_t *pState = ddi_get_soft_state(g_pvgdrvSolarisState, getminor(Dev));
+    if (!pState)
+    {
+        Log(("vgdrvSolarisClose: failed to get pState.\n"));
+        return EFAULT;
+    }
+
+    if (pState->pvProcRef != NULL)
+    {
+        proc_unref(pState->pvProcRef);
+        pState->pvProcRef = NULL;
+    }
+    pSession = pState->pSession;
+    pState->pSession = NULL;
+    Log(("vgdrvSolarisClose: pSession=%p pState=%p\n", pSession, pState));
+    ddi_soft_state_free(g_pvgdrvSolarisState, getminor(Dev));
+    if (!pSession)
+    {
+        Log(("vgdrvSolarisClose: failed to get pSession.\n"));
+        return EFAULT;
+    }
+
+    /*
+     * Close the session.
+     */
+    if (pSession)
+        VGDrvCommonCloseSession(&g_DevExt, pSession);
+    return 0;
+}
+
+
+static int vgdrvSolarisRead(dev_t Dev, struct uio *pUio, cred_t *pCred)
+{
+    LogFlow((DEVICE_NAME "::Read\n"));
+
+    vboxguest_state_t *pState = ddi_get_soft_state(g_pvgdrvSolarisState, getminor(Dev));
+    if (!pState)
+    {
+        Log((DEVICE_NAME "::Close: failed to get pState.\n"));
+        return EFAULT;
+    }
+
+    PVBOXGUESTSESSION pSession = pState->pSession;
+    uint32_t u32CurSeq = ASMAtomicUoReadU32(&g_DevExt.u32MousePosChangedSeq);
+    if (pSession->u32MousePosChangedSeq != u32CurSeq)
+        pSession->u32MousePosChangedSeq = u32CurSeq;
+
+    return 0;
+}
+
+
+static int vgdrvSolarisWrite(dev_t Dev, struct uio *pUio, cred_t *pCred)
+{
+    LogFlow(("vgdrvSolarisWrite:\n"));
+    return 0;
+}
+
+
+/** @def IOCPARM_LEN
+ * Gets the length from the ioctl number.
+ * This is normally defined by sys/ioccom.h on BSD systems...
+ */
+#ifndef IOCPARM_LEN
+# define IOCPARM_LEN(x)     ( ((x) >> 16) & IOCPARM_MASK )
+#endif
+
+
+/**
+ * Driver ioctl, an alternate entry point for this character driver.
+ *
+ * @param   Dev             Device number
+ * @param   iCmd            Operation identifier
+ * @param   iArgs           Arguments from user to driver
+ * @param   Mode            Information bitfield (read/write, address space etc.)
+ * @param   pCred           User credentials
+ * @param   pVal            Return value for calling process.
+ *
+ * @return  corresponding solaris error code.
+ */
+static int vgdrvSolarisIOCtl(dev_t Dev, int iCmd, intptr_t iArgs, int Mode, cred_t *pCred, int *pVal)
+{
+    /*
+     * Get the session from the soft state item.
+     */
+    vboxguest_state_t *pState = ddi_get_soft_state(g_pvgdrvSolarisState, getminor(Dev));
+    if (!pState)
+    {
+        LogRel(("vgdrvSolarisIOCtl: no state data for %#x (%d)\n", Dev, getminor(Dev)));
+        return EINVAL;
+    }
+
+    PVBOXGUESTSESSION pSession = pState->pSession;
+    if (!pSession)
+    {
+        LogRel(("vgdrvSolarisIOCtl: no session in state data for %#x (%d)\n", Dev, getminor(Dev)));
+        return DDI_SUCCESS;
+    }
+
+    /*
+     * Deal with fast requests.
+     */
+    if (VBGL_IOCTL_IS_FAST(iCmd))
+    {
+        *pVal = VGDrvCommonIoCtlFast(iCmd, &g_DevExt, pSession);
+        return 0;
+    }
+
+    /*
+     * It's kind of simple if this is a kernel session, take slow path if user land.
+     */
+    if (pSession->R0Process == NIL_RTR0PROCESS)
+    {
+        if (IOCPARM_LEN(iCmd) == sizeof(VBGLREQHDR))
+        {
+            PVBGLREQHDR pHdr = (PVBGLREQHDR)iArgs;
+            int rc;
+            if (iCmd != VBGL_IOCTL_IDC_DISCONNECT)
+                rc =VGDrvCommonIoCtl(iCmd, &g_DevExt, pSession, pHdr, RT_MAX(pHdr->cbIn, pHdr->cbOut));
+            else
+            {
+                pState->pSession = NULL;
+                rc = VGDrvCommonIoCtl(iCmd, &g_DevExt, pSession, pHdr, RT_MAX(pHdr->cbIn, pHdr->cbOut));
+                if (RT_FAILURE(rc))
+                    pState->pSession = pSession;
+            }
+            return rc;
+        }
+    }
+
+    return vgdrvSolarisIOCtlSlow(pSession, iCmd, Mode, iArgs);
+}
+
+
+/**
+ * Worker for VBoxSupDrvIOCtl that takes the slow IOCtl functions.
+ *
+ * @returns Solaris errno.
+ *
+ * @param   pSession    The session.
+ * @param   iCmd        The IOCtl command.
+ * @param   Mode        Information bitfield (for specifying ownership of data)
+ * @param   iArg        User space address of the request buffer.
+ */
+static int vgdrvSolarisIOCtlSlow(PVBOXGUESTSESSION pSession, int iCmd, int Mode, intptr_t iArg)
+{
+    int         rc;
+    uint32_t    cbBuf = 0;
+    union
+    {
+        VBGLREQHDR  Hdr;
+        uint8_t     abBuf[64];
+    }           StackBuf;
+    PVBGLREQHDR  pHdr;
+
+
+    /*
+     * Read the header.
+     */
+    if (RT_UNLIKELY(IOCPARM_LEN(iCmd) != sizeof(StackBuf.Hdr)))
+    {
+        LogRel(("vgdrvSolarisIOCtlSlow: iCmd=%#x len %d expected %d\n", iCmd, IOCPARM_LEN(iCmd), sizeof(StackBuf.Hdr)));
+        return EINVAL;
+    }
+    rc = ddi_copyin((void *)iArg, &StackBuf.Hdr, sizeof(StackBuf.Hdr), Mode);
+    if (RT_UNLIKELY(rc))
+    {
+        LogRel(("vgdrvSolarisIOCtlSlow: ddi_copyin(,%#lx,) failed; iCmd=%#x. rc=%d\n", iArg, iCmd, rc));
+        return EFAULT;
+    }
+    if (RT_UNLIKELY(StackBuf.Hdr.uVersion != VBGLREQHDR_VERSION))
+    {
+        LogRel(("vgdrvSolarisIOCtlSlow: bad header version %#x; iCmd=%#x\n", StackBuf.Hdr.uVersion, iCmd));
+        return EINVAL;
+    }
+    cbBuf = RT_MAX(StackBuf.Hdr.cbIn, StackBuf.Hdr.cbOut);
+    if (RT_UNLIKELY(   StackBuf.Hdr.cbIn < sizeof(StackBuf.Hdr)
+                    || (StackBuf.Hdr.cbOut < sizeof(StackBuf.Hdr) && StackBuf.Hdr.cbOut != 0)
+                    || cbBuf > _1M*16))
+    {
+        LogRel(("vgdrvSolarisIOCtlSlow: max(%#x,%#x); iCmd=%#x\n", StackBuf.Hdr.cbIn, StackBuf.Hdr.cbOut, iCmd));
+        return EINVAL;
+    }
+
+    /*
+     * Buffer the request.
+     *
+     * Note! Common code revalidates the header sizes and version. So it's
+     *       fine to read it once more.
+     */
+    if (cbBuf <= sizeof(StackBuf))
+        pHdr = &StackBuf.Hdr;
+    else
+    {
+        pHdr = RTMemTmpAlloc(cbBuf);
+        if (RT_UNLIKELY(!pHdr))
+        {
+            LogRel(("vgdrvSolarisIOCtlSlow: failed to allocate buffer of %d bytes for iCmd=%#x.\n", cbBuf, iCmd));
+            return ENOMEM;
+        }
+    }
+    rc = ddi_copyin((void *)iArg, pHdr, cbBuf, Mode);
+    if (RT_UNLIKELY(rc))
+    {
+        LogRel(("vgdrvSolarisIOCtlSlow: copy_from_user(,%#lx, %#x) failed; iCmd=%#x. rc=%d\n", iArg, cbBuf, iCmd, rc));
+        if (pHdr != &StackBuf.Hdr)
+            RTMemFree(pHdr);
+        return EFAULT;
+    }
+
+    /*
+     * Process the IOCtl.
+     */
+    rc = VGDrvCommonIoCtl(iCmd, &g_DevExt, pSession, pHdr, cbBuf);
+
+    /*
+     * Copy ioctl data and output buffer back to user space.
+     */
+    if (RT_SUCCESS(rc))
+    {
+        uint32_t cbOut = pHdr->cbOut;
+        if (RT_UNLIKELY(cbOut > cbBuf))
+        {
+            LogRel(("vgdrvSolarisIOCtlSlow: too much output! %#x > %#x; iCmd=%#x!\n", cbOut, cbBuf, iCmd));
+            cbOut = cbBuf;
+        }
+        rc = ddi_copyout(pHdr, (void *)iArg, cbOut, Mode);
+        if (RT_UNLIKELY(rc != 0))
+        {
+            /* this is really bad */
+            LogRel(("vgdrvSolarisIOCtlSlow: ddi_copyout(,%p,%d) failed. rc=%d\n", (void *)iArg, cbBuf, rc));
+            rc = EFAULT;
+        }
+    }
+    else
+        rc = EINVAL;
+
+    if (pHdr != &StackBuf.Hdr)
+        RTMemTmpFree(pHdr);
+    return rc;
+}
+
+
+#if 0
+/**
+ * @note This code is duplicated on other platforms with variations, so please
+ *       keep them all up to date when making changes!
+ */
+int VBOXCALL VBoxGuestIDC(void *pvSession, uintptr_t uReq, PVBGLREQHDR pReqHdr, size_t cbReq)
+{
+    /*
+     * Simple request validation (common code does the rest).
+     */
+    int rc;
+    if (   RT_VALID_PTR(pReqHdr)
+        && cbReq >= sizeof(*pReqHdr))
+    {
+        /*
+         * All requests except the connect one requires a valid session.
+         */
+        PVBOXGUESTSESSION pSession = (PVBOXGUESTSESSION)pvSession;
+        if (pSession)
+        {
+            if (   RT_VALID_PTR(pSession)
+                && pSession->pDevExt == &g_DevExt)
+                rc = VGDrvCommonIoCtl(uReq, &g_DevExt, pSession, pReqHdr, cbReq);
+            else
+                rc = VERR_INVALID_HANDLE;
+        }
+        else if (uReq == VBGL_IOCTL_IDC_CONNECT)
+        {
+            rc = VGDrvCommonCreateKernelSession(&g_DevExt, &pSession);
+            if (RT_SUCCESS(rc))
+            {
+                rc = VGDrvCommonIoCtl(uReq, &g_DevExt, pSession, pReqHdr, cbReq);
+                if (RT_FAILURE(rc))
+                    VGDrvCommonCloseSession(&g_DevExt, pSession);
+            }
+        }
+        else
+            rc = VERR_INVALID_HANDLE;
+    }
+    else
+        rc = VERR_INVALID_POINTER;
+    return rc;
+}
+#endif
+
+
+static int vgdrvSolarisPoll(dev_t Dev, short fEvents, int fAnyYet, short *pReqEvents, struct pollhead **ppPollHead)
+{
+    LogFlow(("vgdrvSolarisPoll: fEvents=%d fAnyYet=%d\n", fEvents, fAnyYet));
+
+    vboxguest_state_t *pState = ddi_get_soft_state(g_pvgdrvSolarisState, getminor(Dev));
+    if (RT_LIKELY(pState))
+    {
+        PVBOXGUESTSESSION pSession  = (PVBOXGUESTSESSION)pState->pSession;
+        uint32_t u32CurSeq = ASMAtomicUoReadU32(&g_DevExt.u32MousePosChangedSeq);
+        if (pSession->u32MousePosChangedSeq != u32CurSeq)
+        {
+            *pReqEvents |= (POLLIN | POLLRDNORM);
+            pSession->u32MousePosChangedSeq = u32CurSeq;
+        }
+        else
+        {
+            *pReqEvents = 0;
+            if (!fAnyYet)
+                *ppPollHead = &g_PollHead;
+        }
+
+        return 0;
+    }
+
+    Log(("vgdrvSolarisPoll: no state data for %d\n", getminor(Dev)));
+    return EINVAL;
+}
+
+
+/**
+ * Sets IRQ for VMMDev.
+ *
+ * @returns Solaris error code.
+ * @param   pDip     Pointer to the device info structure.
+ */
+static int vgdrvSolarisAddIRQ(dev_info_t *pDip)
+{
+    LogFlow(("vgdrvSolarisAddIRQ: pDip=%p\n", pDip));
+
+    /* Get the types of interrupt supported for this hardware. */
+    int fIntrType = 0;
+    int rc = ddi_intr_get_supported_types(pDip, &fIntrType);
+    if (rc == DDI_SUCCESS)
+    {
+        /* We only support fixed interrupts at this point, not MSIs. */
+        if (fIntrType & DDI_INTR_TYPE_FIXED)
+        {
+            /* Verify the number of interrupts supported by this device. There can only be one fixed interrupt. */
+            int cIntrCount = 0;
+            rc = ddi_intr_get_nintrs(pDip, fIntrType, &cIntrCount);
+            if (   rc == DDI_SUCCESS
+                && cIntrCount == 1)
+            {
+                /* Allocated kernel memory for the interrupt handle. The allocation size is stored internally. */
+                g_pahIntrs = RTMemAllocZ(cIntrCount * sizeof(ddi_intr_handle_t));
+                if (g_pahIntrs)
+                {
+                    /* Allocate the interrupt for this device and verify the allocation. */
+                    int cIntrAllocated;
+                    rc = ddi_intr_alloc(pDip, g_pahIntrs, fIntrType, 0 /* interrupt number */, cIntrCount, &cIntrAllocated,
+                                        DDI_INTR_ALLOC_NORMAL);
+                    if (   rc == DDI_SUCCESS
+                        && cIntrAllocated == 1)
+                    {
+                        /* Get the interrupt priority assigned by the system. */
+                        uint_t uIntrPriority;
+                        rc = ddi_intr_get_pri(g_pahIntrs[0], &uIntrPriority);
+                        if (rc == DDI_SUCCESS)
+                        {
+                            /* Check if the interrupt priority is scheduler level or above, if so we need to use a high-level
+                               and low-level interrupt handlers with corresponding mutexes. */
+                            cmn_err(CE_CONT, "!vboxguest: uIntrPriority=%d hilevel_pri=%d\n", uIntrPriority, ddi_intr_get_hilevel_pri());
+                            if (uIntrPriority >= ddi_intr_get_hilevel_pri())
+                            {
+                                /* Initialize the high-level mutex. */
+                                mutex_init(&g_HighLevelIrqMtx, NULL /* pszDesc */, MUTEX_DRIVER, DDI_INTR_PRI(uIntrPriority));
+
+                                /* Assign interrupt handler function to the interrupt handle. */
+                                rc = ddi_intr_add_handler(g_pahIntrs[0], (ddi_intr_handler_t *)&vgdrvSolarisHighLevelISR,
+                                                          NULL /* pvArg1 */, NULL /* pvArg2 */);
+
+                                if (rc == DDI_SUCCESS)
+                                {
+                                    /* Add the low-level interrupt handler. */
+                                    rc = ddi_intr_add_softint(pDip, &g_hSoftIntr, DDI_INTR_SOFTPRI_MAX,
+                                                              (ddi_intr_handler_t *)&vgdrvSolarisISR, NULL /* pvArg1 */);
+                                    if (rc == DDI_SUCCESS)
+                                    {
+                                        /* Initialize the low-level mutex at the corresponding level. */
+                                        mutex_init(&g_IrqMtx, NULL /* pszDesc */,  MUTEX_DRIVER,
+                                                   DDI_INTR_PRI(DDI_INTR_SOFTPRI_MAX));
+
+                                        g_fSoftIntRegistered = true;
+                                        /* Enable the high-level interrupt. */
+                                        rc = ddi_intr_enable(g_pahIntrs[0]);
+                                        if (rc == DDI_SUCCESS)
+                                            return rc;
+
+                                        LogRel((DEVICE_NAME "::AddIRQ: failed to enable interrupt. rc=%d\n", rc));
+                                        mutex_destroy(&g_IrqMtx);
+                                    }
+                                    else
+                                        LogRel((DEVICE_NAME "::AddIRQ: failed to add soft interrupt handler. rc=%d\n", rc));
+
+                                    ddi_intr_remove_handler(g_pahIntrs[0]);
+                                }
+                                else
+                                    LogRel((DEVICE_NAME "::AddIRQ: failed to add high-level interrupt handler. rc=%d\n", rc));
+
+                                mutex_destroy(&g_HighLevelIrqMtx);
+                            }
+                            else
+                            {
+                                /* Interrupt handler runs at reschedulable level, initialize the mutex at the given priority. */
+                                mutex_init(&g_IrqMtx, NULL /* pszDesc */, MUTEX_DRIVER, DDI_INTR_PRI(uIntrPriority));
+
+                                /* Assign interrupt handler function to the interrupt handle. */
+                                rc = ddi_intr_add_handler(g_pahIntrs[0], (ddi_intr_handler_t *)vgdrvSolarisISR,
+                                                          NULL /* pvArg1 */, NULL /* pvArg2 */);
+                                if (rc == DDI_SUCCESS)
+                                {
+                                    /* Enable the interrupt. */
+                                    rc = ddi_intr_enable(g_pahIntrs[0]);
+                                    if (rc == DDI_SUCCESS)
+                                        return rc;
+
+                                    LogRel((DEVICE_NAME "::AddIRQ: failed to enable interrupt. rc=%d\n", rc));
+                                    mutex_destroy(&g_IrqMtx);
+                                }
+                            }
+                        }
+                        else
+                            LogRel((DEVICE_NAME "::AddIRQ: failed to get priority of interrupt. rc=%d\n", rc));
+
+                        Assert(cIntrAllocated == 1);
+                        ddi_intr_free(g_pahIntrs[0]);
+                    }
+                    else
+                        LogRel((DEVICE_NAME "::AddIRQ: failed to allocated IRQs. count=%d\n", cIntrCount));
+                    RTMemFree(g_pahIntrs);
+                }
+                else
+                    LogRel((DEVICE_NAME "::AddIRQ: failed to allocated IRQs. count=%d\n", cIntrCount));
+            }
+            else
+                LogRel((DEVICE_NAME "::AddIRQ: failed to get or insufficient number of IRQs. rc=%d cIntrCount=%d\n", rc, cIntrCount));
+        }
+        else
+            LogRel((DEVICE_NAME "::AddIRQ: fixed-type interrupts not supported. IntrType=%#x\n", fIntrType));
+    }
+    else
+        LogRel((DEVICE_NAME "::AddIRQ: failed to get supported interrupt types. rc=%d\n", rc));
+    return rc;
+}
+
+
+/**
+ * Removes IRQ for VMMDev.
+ *
+ * @param   pDip     Pointer to the device info structure.
+ */
+static void vgdrvSolarisRemoveIRQ(dev_info_t *pDip)
+{
+    LogFlow(("vgdrvSolarisRemoveIRQ:\n"));
+
+    int rc = ddi_intr_disable(g_pahIntrs[0]);
+    if (rc == DDI_SUCCESS)
+    {
+        rc = ddi_intr_remove_handler(g_pahIntrs[0]);
+        if (rc == DDI_SUCCESS)
+            ddi_intr_free(g_pahIntrs[0]);
+    }
+
+    if (g_fSoftIntRegistered)
+    {
+        ddi_intr_remove_softint(g_hSoftIntr);
+        mutex_destroy(&g_HighLevelIrqMtx);
+        g_fSoftIntRegistered = false;
+    }
+
+    mutex_destroy(&g_IrqMtx);
+    RTMemFree(g_pahIntrs);
+}
+
+
+/**
+ * High-level Interrupt Service Routine for VMMDev.
+ *
+ * This routine simply dispatches a soft-interrupt at an acceptable IPL as
+ * VGDrvCommonISR() cannot be called at a high IPL (scheduler level or higher)
+ * due to pollwakeup() in VGDrvNativeISRMousePollEvent().
+ *
+ * @param   Arg     Private data (unused, will be NULL).
+ * @returns DDI_INTR_CLAIMED if it's our interrupt, DDI_INTR_UNCLAIMED if it isn't.
+ */
+static uint_t vgdrvSolarisHighLevelISR(caddr_t Arg)
+{
+    bool const fOurIrq = VGDrvCommonIsOurIRQ(&g_DevExt);
+    if (fOurIrq)
+    {
+        ddi_intr_trigger_softint(g_hSoftIntr, NULL /* Arg */);
+        return DDI_INTR_CLAIMED;
+    }
+    return DDI_INTR_UNCLAIMED;
+}
+
+
+/**
+ * Interrupt Service Routine for VMMDev.
+ *
+ * @param   Arg     Private data (unused, will be NULL).
+ * @returns DDI_INTR_CLAIMED if it's our interrupt, DDI_INTR_UNCLAIMED if it isn't.
+ */
+static uint_t vgdrvSolarisISR(caddr_t Arg)
+{
+    LogFlow(("vgdrvSolarisISR:\n"));
+
+    /* The mutex is required to protect against parallel executions (if possible?) and also the
+       mouse notify registeration race between VGDrvNativeSetMouseNotifyCallback() and VGDrvCommonISR(). */
+    mutex_enter(&g_IrqMtx);
+    bool fOurIRQ = VGDrvCommonISR(&g_DevExt);
+    mutex_exit(&g_IrqMtx);
+
+    return fOurIRQ ? DDI_INTR_CLAIMED : DDI_INTR_UNCLAIMED;
+}
+
+
+void VGDrvNativeISRMousePollEvent(PVBOXGUESTDEVEXT pDevExt)
+{
+    LogFlow(("VGDrvNativeISRMousePollEvent:\n"));
+
+    /*
+     * Wake up poll waiters.
+     */
+    pollwakeup(&g_PollHead, POLLIN | POLLRDNORM);
+}
+
+
+bool VGDrvNativeProcessOption(PVBOXGUESTDEVEXT pDevExt, const char *pszName, const char *pszValue)
+{
+    RT_NOREF(pDevExt); RT_NOREF(pszName); RT_NOREF(pszValue);
+    return false;
+}
+
+
+/**
+ * Sets the mouse notification callback.
+ *
+ * @returns VBox status code.
+ * @param   pDevExt   Pointer to the device extension.
+ * @param   pNotify   Pointer to the mouse notify struct.
+ */
+int VGDrvNativeSetMouseNotifyCallback(PVBOXGUESTDEVEXT pDevExt, PVBGLIOCSETMOUSENOTIFYCALLBACK pNotify)
+{
+    /* Take the mutex here so as to not race with VGDrvCommonISR() which invokes the mouse notify callback. */
+    mutex_enter(&g_IrqMtx);
+    pDevExt->pfnMouseNotifyCallback   = pNotify->u.In.pfnNotify;
+    pDevExt->pvMouseNotifyCallbackArg = pNotify->u.In.pvUser;
+    mutex_exit(&g_IrqMtx);
+    return VINF_SUCCESS;
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/VBoxGuest-solaris.conf b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-solaris.conf
new file mode 100644
index 00000000..91a245bf
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-solaris.conf
@@ -0,0 +1,41 @@
+# $Id: VBoxGuest-solaris.conf $
+## @file
+# OpenSolaris Guest Driver Configuration
+
+#
+# Copyright (C) 2007-2023 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
+#
+
+# This needs to go into /platform/i86pc/kernel/drv,
+# while the 64-bit driver object goes into the amd64
+# subdirectory (32-bit drivers goes into the same
+# directory).
+#
+name="vboxguest" parent="/pci@0,0/pci80ee,cafe" instance=0;
diff --git a/src/VBox/Additions/common/VBoxGuest/VBoxGuest-win.cpp b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-win.cpp
new file mode 100644
index 00000000..c9e180af
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/VBoxGuest-win.cpp
@@ -0,0 +1,3503 @@
+/* $Id: VBoxGuest-win.cpp $ */
+/** @file
+ * VBoxGuest - Windows specifics.
+ */
+
+/*
+ * Copyright (C) 2010-2023 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 LOG_GROUP LOG_GROUP_SUP_DRV
+#include <iprt/nt/nt.h>
+
+#include "VBoxGuestInternal.h"
+#include <VBox/VBoxGuestLib.h>
+#include <VBox/log.h>
+
+#include <iprt/asm.h>
+#include <iprt/asm-amd64-x86.h>
+#include <iprt/critsect.h>
+#include <iprt/dbg.h>
+#include <iprt/err.h>
+#include <iprt/initterm.h>
+#include <iprt/memobj.h>
+#include <iprt/mem.h>
+#include <iprt/mp.h>
+#include <iprt/spinlock.h>
+#include <iprt/string.h>
+#include <iprt/utf16.h>
+
+#ifdef TARGET_NT4
+# include <VBox/pci.h>
+# define PIMAGE_NT_HEADERS32 PIMAGE_NT_HEADERS32_IPRT
+# include <iprt/formats/mz.h>
+# include <iprt/formats/pecoff.h>
+extern "C" IMAGE_DOS_HEADER __ImageBase;
+#endif
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+#undef ExFreePool
+
+#ifndef PCI_MAX_BUSES
+# define PCI_MAX_BUSES 256
+#endif
+
+/** CM_RESOURCE_MEMORY_* flags which were used on XP or earlier. */
+#define VBOX_CM_PRE_VISTA_MASK (0x3f)
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Possible device states for our state machine.
+ */
+typedef enum VGDRVNTDEVSTATE
+{
+    /** @name Stable states
+     * @{ */
+    VGDRVNTDEVSTATE_REMOVED = 0,
+    VGDRVNTDEVSTATE_STOPPED,
+    VGDRVNTDEVSTATE_OPERATIONAL,
+    /** @} */
+
+    /** @name Transitional states
+     *  @{ */
+    VGDRVNTDEVSTATE_PENDINGSTOP,
+    VGDRVNTDEVSTATE_PENDINGREMOVE,
+    VGDRVNTDEVSTATE_SURPRISEREMOVED
+    /** @} */
+} VGDRVNTDEVSTATE;
+
+
+/**
+ * Subclassing the device extension for adding windows-specific bits.
+ */
+typedef struct VBOXGUESTDEVEXTWIN
+{
+    /** The common device extension core. */
+    VBOXGUESTDEVEXT         Core;
+
+    /** Our functional driver object. */
+    PDEVICE_OBJECT          pDeviceObject;
+    /** Top of the stack. */
+    PDEVICE_OBJECT          pNextLowerDriver;
+
+    /** @name PCI bus and slot (device+function) set by for legacy NT only.
+     * @{ */
+    /** Bus number where the device is located. */
+    ULONG                   uBus;
+    /** Slot number where the device is located (PCI_SLOT_NUMBER). */
+    ULONG                   uSlot;
+    /** @} */
+
+    /** @name Interrupt stuff.
+     * @{  */
+    /** Interrupt object pointer. */
+    PKINTERRUPT             pInterruptObject;
+    /** Device interrupt level. */
+    ULONG                   uInterruptLevel;
+    /** Device interrupt vector. */
+    ULONG                   uInterruptVector;
+    /** Affinity mask. */
+    KAFFINITY               fInterruptAffinity;
+    /** LevelSensitive or Latched. */
+    KINTERRUPT_MODE         enmInterruptMode;
+    /** @} */
+
+    /** Physical address and length of VMMDev memory. */
+    PHYSICAL_ADDRESS        uVmmDevMemoryPhysAddr;
+    /** Length of VMMDev memory.   */
+    ULONG                   cbVmmDevMemory;
+
+    /** Device state. */
+    VGDRVNTDEVSTATE volatile enmDevState;
+    /** The previous stable device state. */
+    VGDRVNTDEVSTATE         enmPrevDevState;
+
+    /** Last system power action set (see VBoxGuestPower). */
+    POWER_ACTION            enmLastSystemPowerAction;
+    /** Preallocated generic request for shutdown. */
+    VMMDevPowerStateRequest *pPowerStateRequest;
+
+    /** Spinlock protecting MouseNotifyCallback. Required since the consumer is
+     *  in a DPC callback and not the ISR. */
+    KSPIN_LOCK              MouseEventAccessSpinLock;
+
+    /** Read/write critical section for handling race between checking for idle
+     * driver (in IRP_MN_QUERY_REMOVE_DEVICE & IRP_MN_QUERY_STOP_DEVICE) and
+     * creating new sessions.  The session creation code enteres the critical
+     * section in  read (shared) access mode, whereas the idle checking code
+     * enteres is in write (exclusive) access mode.  */
+    RTCRITSECTRW            SessionCreateCritSect;
+} VBOXGUESTDEVEXTWIN;
+typedef VBOXGUESTDEVEXTWIN *PVBOXGUESTDEVEXTWIN;
+
+
+/** NT (windows) version identifier. */
+typedef enum VGDRVNTVER
+{
+    VGDRVNTVER_INVALID = 0,
+    VGDRVNTVER_WINNT310,
+    VGDRVNTVER_WINNT350,
+    VGDRVNTVER_WINNT351,
+    VGDRVNTVER_WINNT4,
+    VGDRVNTVER_WIN2K,
+    VGDRVNTVER_WINXP,
+    VGDRVNTVER_WIN2K3,
+    VGDRVNTVER_WINVISTA,
+    VGDRVNTVER_WIN7,
+    VGDRVNTVER_WIN8,
+    VGDRVNTVER_WIN81,
+    VGDRVNTVER_WIN10,
+    VGDRVNTVER_WIN11
+} VGDRVNTVER;
+
+
+/*********************************************************************************************************************************
+*   Internal Functions                                                                                                           *
+*********************************************************************************************************************************/
+RT_C_DECLS_BEGIN
+static NTSTATUS NTAPI vgdrvNtNt5PlusAddDevice(PDRIVER_OBJECT pDrvObj, PDEVICE_OBJECT pDevObj);
+static NTSTATUS NTAPI vgdrvNtNt5PlusPnP(PDEVICE_OBJECT pDevObj, PIRP pIrp);
+static NTSTATUS NTAPI vgdrvNtNt5PlusPower(PDEVICE_OBJECT pDevObj, PIRP pIrp);
+static NTSTATUS NTAPI vgdrvNtNt5PlusSystemControl(PDEVICE_OBJECT pDevObj, PIRP pIrp);
+static void     NTAPI vgdrvNtUnload(PDRIVER_OBJECT pDrvObj);
+static NTSTATUS NTAPI vgdrvNtCreate(PDEVICE_OBJECT pDevObj, PIRP pIrp);
+static NTSTATUS NTAPI vgdrvNtClose(PDEVICE_OBJECT pDevObj, PIRP pIrp);
+static NTSTATUS NTAPI vgdrvNtDeviceControl(PDEVICE_OBJECT pDevObj, PIRP pIrp);
+static NTSTATUS       vgdrvNtDeviceControlSlow(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession,
+                                               PIRP pIrp, PIO_STACK_LOCATION pStack);
+static NTSTATUS NTAPI vgdrvNtInternalIOCtl(PDEVICE_OBJECT pDevObj, PIRP pIrp);
+static void           vgdrvNtReadConfiguration(PVBOXGUESTDEVEXTWIN pDevExt);
+static NTSTATUS NTAPI vgdrvNtShutdown(PDEVICE_OBJECT pDevObj, PIRP pIrp);
+static NTSTATUS NTAPI vgdrvNtNotSupportedStub(PDEVICE_OBJECT pDevObj, PIRP pIrp);
+static VOID     NTAPI vgdrvNtBugCheckCallback(PVOID pvBuffer, ULONG cbBuffer);
+static VOID     NTAPI vgdrvNtDpcHandler(PKDPC pDPC, PDEVICE_OBJECT pDevObj, PIRP pIrp, PVOID pContext);
+static BOOLEAN  NTAPI vgdrvNtIsrHandler(PKINTERRUPT interrupt, PVOID serviceContext);
+#ifdef VBOX_STRICT
+static void           vgdrvNtDoTests(void);
+#endif
+#ifdef TARGET_NT4
+static ULONG NTAPI    vgdrvNt31GetBusDataByOffset(BUS_DATA_TYPE enmBusDataType, ULONG idxBus, ULONG uSlot,
+                                                  void *pvData, ULONG offData, ULONG cbData);
+static ULONG NTAPI    vgdrvNt31SetBusDataByOffset(BUS_DATA_TYPE enmBusDataType, ULONG idxBus, ULONG uSlot,
+                                                  void *pvData, ULONG offData, ULONG cbData);
+#endif
+
+/*
+ * We only do INIT allocations.  PAGE is too much work and risk for little gain.
+ */
+#ifdef ALLOC_PRAGMA
+NTSTATUS DriverEntry(PDRIVER_OBJECT pDrvObj, PUNICODE_STRING pRegPath);
+# pragma alloc_text(INIT, DriverEntry)
+# ifdef TARGET_NT4
+static NTSTATUS       vgdrvNt4CreateDevice(PDRIVER_OBJECT pDrvObj, PUNICODE_STRING pRegPath);
+#  pragma alloc_text(INIT, vgdrvNt4CreateDevice)
+static NTSTATUS       vgdrvNt4FindPciDevice(PULONG puluBusNumber, PPCI_SLOT_NUMBER puSlotNumber);
+#  pragma alloc_text(INIT, vgdrvNt4FindPciDevice)
+# endif
+#endif
+RT_C_DECLS_END
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/** The detected NT (windows) version. */
+static VGDRVNTVER                               g_enmVGDrvNtVer = VGDRVNTVER_INVALID;
+/** Pointer to the PoStartNextPowerIrp routine (in the NT kernel).
+ * Introduced in Windows 2000. */
+static decltype(PoStartNextPowerIrp)           *g_pfnPoStartNextPowerIrp = NULL;
+/** Pointer to the PoCallDriver routine (in the NT kernel).
+ * Introduced in Windows 2000. */
+static decltype(PoCallDriver)                  *g_pfnPoCallDriver = NULL;
+#ifdef TARGET_NT4
+/** Pointer to the HalAssignSlotResources routine (in the HAL).
+ * Introduced in NT 3.50.  */
+static decltype(HalAssignSlotResources)        *g_pfnHalAssignSlotResources= NULL;
+/** Pointer to the HalGetBusDataByOffset routine (in the HAL).
+ * Introduced in NT 3.50.  */
+static decltype(HalGetBusDataByOffset)         *g_pfnHalGetBusDataByOffset = NULL;
+/** Pointer to the HalSetBusDataByOffset routine (in the HAL).
+ * Introduced in NT 3.50 (we provide fallback and use it only for NT 3.1).  */
+static decltype(HalSetBusDataByOffset)         *g_pfnHalSetBusDataByOffset = NULL;
+#endif
+/** Pointer to the KeRegisterBugCheckCallback routine (in the NT kernel).
+ * Introduced in Windows 3.50. */
+static decltype(KeRegisterBugCheckCallback)    *g_pfnKeRegisterBugCheckCallback = NULL;
+/** Pointer to the KeRegisterBugCheckCallback routine (in the NT kernel).
+ * Introduced in Windows 3.50. */
+static decltype(KeDeregisterBugCheckCallback)  *g_pfnKeDeregisterBugCheckCallback = NULL;
+/** Pointer to the KiBugCheckData array (in the NT kernel).
+ * Introduced in Windows 4. */
+static uintptr_t const                         *g_pauKiBugCheckData = NULL;
+/** Set if the callback was successfully registered and needs deregistering.  */
+static bool                                     g_fBugCheckCallbackRegistered = false;
+/** The bugcheck callback record. */
+static KBUGCHECK_CALLBACK_RECORD                g_BugCheckCallbackRec;
+
+
+
+/**
+ * Driver entry point.
+ *
+ * @returns appropriate status code.
+ * @param   pDrvObj     Pointer to driver object.
+ * @param   pRegPath    Registry base path.
+ */
+NTSTATUS DriverEntry(PDRIVER_OBJECT pDrvObj, PUNICODE_STRING pRegPath)
+{
+    RT_NOREF1(pRegPath);
+#ifdef TARGET_NT4
+    /*
+     * Looks like NT 3.1 doesn't necessarily zero our uninitialized data segments
+     * (like ".bss"), at least not when loading at runtime, so do that.
+     */
+    PIMAGE_DOS_HEADER   pMzHdr  = &__ImageBase;
+    PIMAGE_NT_HEADERS32 pNtHdrs = (PIMAGE_NT_HEADERS32)((uint8_t *)pMzHdr + pMzHdr->e_lfanew);
+    if (   pNtHdrs->Signature == IMAGE_NT_SIGNATURE
+        && pNtHdrs->FileHeader.NumberOfSections > 2
+        && pNtHdrs->FileHeader.NumberOfSections < 64)
+    {
+        uint32_t                iShdr   = pNtHdrs->FileHeader.NumberOfSections;
+        uint32_t                uRvaEnd = pNtHdrs->OptionalHeader.SizeOfImage; /* (may be changed to exclude tail sections) */
+        PIMAGE_SECTION_HEADER   paShdrs;
+        paShdrs = (PIMAGE_SECTION_HEADER)&pNtHdrs->OptionalHeader.DataDirectory[pNtHdrs->OptionalHeader.NumberOfRvaAndSizes];
+        while (iShdr-- > 0)
+        {
+            if (   !(paShdrs[iShdr].Characteristics & IMAGE_SCN_TYPE_NOLOAD)
+                && paShdrs[iShdr].VirtualAddress < uRvaEnd)
+            {
+                uint32_t const cbSection        = uRvaEnd - paShdrs[iShdr].VirtualAddress;
+                uint32_t const offUninitialized = paShdrs[iShdr].SizeOfRawData;
+                //RTLogBackdoorPrintf("section #%u: rva=%#x  size=%#x calcsize=%#x) rawsize=%#x\n", iShdr,
+                //                    paShdrs[iShdr].VirtualAddress, paShdrs[iShdr].Misc.VirtualSize, cbSection, offUninitialized);
+                if (   offUninitialized < cbSection
+                    && (paShdrs[iShdr].Characteristics & IMAGE_SCN_MEM_WRITE))
+                    memset((uint8_t *)pMzHdr + paShdrs[iShdr].VirtualAddress + offUninitialized, 0, cbSection - offUninitialized);
+                uRvaEnd = paShdrs[iShdr].VirtualAddress;
+            }
+        }
+    }
+    else
+        RTLogBackdoorPrintf("VBoxGuest: Bad pNtHdrs=%p: %#x\n", pNtHdrs, pNtHdrs->Signature);
+#endif
+
+    /*
+     * Start by initializing IPRT.
+     */
+    int rc = RTR0Init(0);
+    if (RT_FAILURE(rc))
+    {
+        RTLogBackdoorPrintf("VBoxGuest: RTR0Init failed: %Rrc!\n", rc);
+        return STATUS_UNSUCCESSFUL;
+    }
+    VGDrvCommonInitLoggers();
+
+    LogFunc(("Driver built: %s %s\n", __DATE__, __TIME__));
+
+    /*
+     * Check if the NT version is supported and initialize g_enmVGDrvNtVer.
+     */
+    ULONG ulMajorVer;
+    ULONG ulMinorVer;
+    ULONG ulBuildNo;
+    BOOLEAN fCheckedBuild = PsGetVersion(&ulMajorVer, &ulMinorVer, &ulBuildNo, NULL);
+
+    /* Use RTLogBackdoorPrintf to make sure that this goes to VBox.log on the host. */
+    RTLogBackdoorPrintf("VBoxGuest: Windows version %u.%u, build %u\n", ulMajorVer, ulMinorVer, ulBuildNo);
+    if (fCheckedBuild)
+        RTLogBackdoorPrintf("VBoxGuest: Windows checked build\n");
+
+#ifdef VBOX_STRICT
+    vgdrvNtDoTests();
+#endif
+    NTSTATUS rcNt = STATUS_SUCCESS;
+    switch (ulMajorVer)
+    {
+        case 10:
+            /* Windows 10 Preview builds starting with 9926. */
+            g_enmVGDrvNtVer = VGDRVNTVER_WIN10;
+            /* Windows 11 Preview builds starting with 22000. */
+            if (ulBuildNo >= 22000)
+                g_enmVGDrvNtVer = VGDRVNTVER_WIN11;
+            break;
+        case 6: /* Windows Vista or Windows 7 (based on minor ver) */
+            switch (ulMinorVer)
+            {
+                case 0: /* Note: Also could be Windows 2008 Server! */
+                    g_enmVGDrvNtVer = VGDRVNTVER_WINVISTA;
+                    break;
+                case 1: /* Note: Also could be Windows 2008 Server R2! */
+                    g_enmVGDrvNtVer = VGDRVNTVER_WIN7;
+                    break;
+                case 2:
+                    g_enmVGDrvNtVer = VGDRVNTVER_WIN8;
+                    break;
+                case 3:
+                    g_enmVGDrvNtVer = VGDRVNTVER_WIN81;
+                    break;
+                case 4: /* Windows 10 Preview builds. */
+                default:
+                    g_enmVGDrvNtVer = VGDRVNTVER_WIN10;
+                    break;
+            }
+            break;
+        case 5:
+            switch (ulMinorVer)
+            {
+                default:
+                case 2:
+                    g_enmVGDrvNtVer = VGDRVNTVER_WIN2K3;
+                    break;
+                case 1:
+                    g_enmVGDrvNtVer = VGDRVNTVER_WINXP;
+                    break;
+                case 0:
+                    g_enmVGDrvNtVer = VGDRVNTVER_WIN2K;
+                    break;
+            }
+            break;
+        case 4:
+            g_enmVGDrvNtVer = VGDRVNTVER_WINNT4;
+            break;
+        case 3:
+            if (ulMinorVer > 50)
+                g_enmVGDrvNtVer = VGDRVNTVER_WINNT351;
+            else if (ulMinorVer >= 50)
+                g_enmVGDrvNtVer = VGDRVNTVER_WINNT350;
+            else
+                g_enmVGDrvNtVer = VGDRVNTVER_WINNT310;
+            break;
+        default:
+            /* Major versions above 6 gets classified as windows 10. */
+            if (ulMajorVer > 6)
+                g_enmVGDrvNtVer = VGDRVNTVER_WIN10;
+            else
+            {
+                RTLogBackdoorPrintf("At least Windows NT 3.10 required! Found %u.%u!\n", ulMajorVer, ulMinorVer);
+                rcNt = STATUS_DRIVER_UNABLE_TO_LOAD;
+            }
+            break;
+    }
+    if (NT_SUCCESS(rcNt))
+    {
+        /*
+         * Dynamically resolve symbols not present in NT4.
+         */
+        RTDBGKRNLINFO hKrnlInfo;
+        rc = RTR0DbgKrnlInfoOpen(&hKrnlInfo, 0 /*fFlags*/);
+        if (RT_SUCCESS(rc))
+        {
+            g_pfnKeRegisterBugCheckCallback   = (decltype(KeRegisterBugCheckCallback) *)  RTR0DbgKrnlInfoGetSymbol(hKrnlInfo, NULL, "KeRegisterBugCheckCallback");
+            g_pfnKeDeregisterBugCheckCallback = (decltype(KeDeregisterBugCheckCallback) *)RTR0DbgKrnlInfoGetSymbol(hKrnlInfo, NULL, "KeDeregisterBugCheckCallback");
+            g_pauKiBugCheckData               = (uintptr_t const *)                       RTR0DbgKrnlInfoGetSymbol(hKrnlInfo, NULL, "KiBugCheckData");
+            g_pfnPoCallDriver                 = (decltype(PoCallDriver) *)                RTR0DbgKrnlInfoGetSymbol(hKrnlInfo, NULL, "PoCallDriver");
+            g_pfnPoStartNextPowerIrp          = (decltype(PoStartNextPowerIrp) *)         RTR0DbgKrnlInfoGetSymbol(hKrnlInfo, NULL, "PoStartNextPowerIrp");
+#ifdef TARGET_NT4
+            if (g_enmVGDrvNtVer > VGDRVNTVER_WINNT4)
+#endif
+            {
+                if (!g_pfnPoCallDriver)        { LogRelFunc(("Missing PoCallDriver!\n"));        rc = VERR_SYMBOL_NOT_FOUND; }
+                if (!g_pfnPoStartNextPowerIrp) { LogRelFunc(("Missing PoStartNextPowerIrp!\n")); rc = VERR_SYMBOL_NOT_FOUND; }
+            }
+
+#ifdef TARGET_NT4
+            g_pfnHalAssignSlotResources       = (decltype(HalAssignSlotResources) *)RTR0DbgKrnlInfoGetSymbol(hKrnlInfo, NULL, "HalAssignSlotResources");
+            if (!g_pfnHalAssignSlotResources && g_enmVGDrvNtVer >= VGDRVNTVER_WINNT350 && g_enmVGDrvNtVer < VGDRVNTVER_WIN2K)
+            {
+                RTLogBackdoorPrintf("VBoxGuest: Missing HalAssignSlotResources!\n");
+                rc = VERR_SYMBOL_NOT_FOUND;
+            }
+
+            g_pfnHalGetBusDataByOffset        = (decltype(HalGetBusDataByOffset) *)RTR0DbgKrnlInfoGetSymbol(hKrnlInfo, NULL, "HalGetBusDataByOffset");
+            if (!g_pfnHalGetBusDataByOffset && g_enmVGDrvNtVer >= VGDRVNTVER_WINNT350 && g_enmVGDrvNtVer < VGDRVNTVER_WIN2K)
+            {
+                RTLogBackdoorPrintf("VBoxGuest: Missing HalGetBusDataByOffset!\n");
+                rc = VERR_SYMBOL_NOT_FOUND;
+            }
+            if (!g_pfnHalGetBusDataByOffset)
+                g_pfnHalGetBusDataByOffset = vgdrvNt31GetBusDataByOffset;
+
+            g_pfnHalSetBusDataByOffset        = (decltype(HalSetBusDataByOffset) *)RTR0DbgKrnlInfoGetSymbol(hKrnlInfo, NULL, "HalSetBusDataByOffset");
+            if (!g_pfnHalSetBusDataByOffset && g_enmVGDrvNtVer >= VGDRVNTVER_WINNT350 && g_enmVGDrvNtVer < VGDRVNTVER_WIN2K)
+            {
+                RTLogBackdoorPrintf("VBoxGuest: Missing HalSetBusDataByOffset!\n");
+                rc = VERR_SYMBOL_NOT_FOUND;
+            }
+            if (!g_pfnHalSetBusDataByOffset)
+                g_pfnHalSetBusDataByOffset = vgdrvNt31SetBusDataByOffset;
+#endif
+            RTR0DbgKrnlInfoRelease(hKrnlInfo);
+        }
+        if (RT_SUCCESS(rc))
+        {
+            /*
+             * Setup the driver entry points in pDrvObj.
+             */
+            pDrvObj->DriverUnload                                  = vgdrvNtUnload;
+            pDrvObj->MajorFunction[IRP_MJ_CREATE]                  = vgdrvNtCreate;
+            pDrvObj->MajorFunction[IRP_MJ_CLOSE]                   = vgdrvNtClose;
+            pDrvObj->MajorFunction[IRP_MJ_DEVICE_CONTROL]          = vgdrvNtDeviceControl;
+            pDrvObj->MajorFunction[IRP_MJ_INTERNAL_DEVICE_CONTROL] = vgdrvNtInternalIOCtl;
+            /** @todo Need to call IoRegisterShutdownNotification or
+             *        IoRegisterLastChanceShutdownNotification, possibly hooking the
+             *        HalReturnToFirmware import in NTOSKRNL on older systems (<= ~NT4) and
+             *        check for power off requests. */
+            pDrvObj->MajorFunction[IRP_MJ_SHUTDOWN]                = vgdrvNtShutdown;
+            pDrvObj->MajorFunction[IRP_MJ_READ]                    = vgdrvNtNotSupportedStub;
+            pDrvObj->MajorFunction[IRP_MJ_WRITE]                   = vgdrvNtNotSupportedStub;
+#ifdef TARGET_NT4
+            if (g_enmVGDrvNtVer <= VGDRVNTVER_WINNT4)
+                rcNt = vgdrvNt4CreateDevice(pDrvObj, pRegPath);
+            else
+#endif
+            {
+                pDrvObj->MajorFunction[IRP_MJ_PNP]                     = vgdrvNtNt5PlusPnP;
+                pDrvObj->MajorFunction[IRP_MJ_POWER]                   = vgdrvNtNt5PlusPower;
+                pDrvObj->MajorFunction[IRP_MJ_SYSTEM_CONTROL]          = vgdrvNtNt5PlusSystemControl;
+                pDrvObj->DriverExtension->AddDevice                    = vgdrvNtNt5PlusAddDevice;
+            }
+            if (NT_SUCCESS(rcNt))
+            {
+                /*
+                 * Try register the bugcheck callback (non-fatal).
+                 */
+                if (   g_pfnKeRegisterBugCheckCallback
+                    && g_pfnKeDeregisterBugCheckCallback)
+                {
+                    AssertCompile(BufferEmpty == 0);
+                    KeInitializeCallbackRecord(&g_BugCheckCallbackRec);
+                    if (g_pfnKeRegisterBugCheckCallback(&g_BugCheckCallbackRec, vgdrvNtBugCheckCallback,
+                                                        NULL, 0, (PUCHAR)"VBoxGuest"))
+                        g_fBugCheckCallbackRegistered = true;
+                    else
+                        g_fBugCheckCallbackRegistered = false;
+                }
+                else
+                    Assert(g_pfnKeRegisterBugCheckCallback == NULL && g_pfnKeDeregisterBugCheckCallback == NULL);
+
+                LogFlowFunc(("Returning %#x\n", rcNt));
+                return rcNt;
+            }
+        }
+        else
+            rcNt = STATUS_PROCEDURE_NOT_FOUND;
+    }
+
+    /*
+     * Failed.
+     */
+    LogRelFunc(("Failed! rcNt=%#x\n", rcNt));
+    VGDrvCommonDestroyLoggers();
+    RTR0Term();
+    return rcNt;
+}
+
+
+/**
+ * Translates our internal NT version enum to VBox OS.
+ *
+ * @returns VBox OS type.
+ * @param   enmNtVer            The NT version.
+ */
+static VBOXOSTYPE vgdrvNtVersionToOSType(VGDRVNTVER enmNtVer)
+{
+    VBOXOSTYPE enmOsType;
+    switch (enmNtVer)
+    {
+        case VGDRVNTVER_WINNT310:   enmOsType = VBOXOSTYPE_WinNT3x; break;
+        case VGDRVNTVER_WINNT350:   enmOsType = VBOXOSTYPE_WinNT3x; break;
+        case VGDRVNTVER_WINNT351:   enmOsType = VBOXOSTYPE_WinNT3x; break;
+        case VGDRVNTVER_WINNT4:     enmOsType = VBOXOSTYPE_WinNT4; break;
+        case VGDRVNTVER_WIN2K:      enmOsType = VBOXOSTYPE_Win2k; break;
+        case VGDRVNTVER_WINXP:      enmOsType = VBOXOSTYPE_WinXP; break;
+        case VGDRVNTVER_WIN2K3:     enmOsType = VBOXOSTYPE_Win2k3; break;
+        case VGDRVNTVER_WINVISTA:   enmOsType = VBOXOSTYPE_WinVista; break;
+        case VGDRVNTVER_WIN7:       enmOsType = VBOXOSTYPE_Win7; break;
+        case VGDRVNTVER_WIN8:       enmOsType = VBOXOSTYPE_Win8; break;
+        case VGDRVNTVER_WIN81:      enmOsType = VBOXOSTYPE_Win81; break;
+        case VGDRVNTVER_WIN10:      enmOsType = VBOXOSTYPE_Win10; break;
+        case VGDRVNTVER_WIN11:      enmOsType = VBOXOSTYPE_Win11_x64; break;
+
+        default:
+            /* We don't know, therefore NT family. */
+            enmOsType = VBOXOSTYPE_WinNT;
+            break;
+    }
+#if ARCH_BITS == 64
+    enmOsType = (VBOXOSTYPE)((int)enmOsType | VBOXOSTYPE_x64);
+#endif
+    return enmOsType;
+}
+
+
+/**
+ * Does the fundamental device extension initialization.
+ *
+ * @returns NT status.
+ * @param   pDevExt             The device extension.
+ * @param   pDevObj             The device object.
+ */
+static NTSTATUS vgdrvNtInitDevExtFundament(PVBOXGUESTDEVEXTWIN pDevExt, PDEVICE_OBJECT pDevObj)
+{
+    RT_ZERO(*pDevExt);
+
+    KeInitializeSpinLock(&pDevExt->MouseEventAccessSpinLock);
+    pDevExt->pDeviceObject   = pDevObj;
+    pDevExt->enmPrevDevState = VGDRVNTDEVSTATE_STOPPED;
+    pDevExt->enmDevState     = VGDRVNTDEVSTATE_STOPPED;
+
+    int rc = RTCritSectRwInit(&pDevExt->SessionCreateCritSect);
+    if (RT_SUCCESS(rc))
+    {
+        rc = VGDrvCommonInitDevExtFundament(&pDevExt->Core);
+        if (RT_SUCCESS(rc))
+        {
+            LogFlow(("vgdrvNtInitDevExtFundament: returning success\n"));
+            return STATUS_SUCCESS;
+        }
+
+        RTCritSectRwDelete(&pDevExt->SessionCreateCritSect);
+    }
+    Log(("vgdrvNtInitDevExtFundament: failed: rc=%Rrc\n", rc));
+    return STATUS_UNSUCCESSFUL;
+}
+
+
+/**
+ * Counter part to vgdrvNtInitDevExtFundament.
+ *
+ * @param   pDevExt             The device extension.
+ */
+static void vgdrvNtDeleteDevExtFundament(PVBOXGUESTDEVEXTWIN pDevExt)
+{
+    LogFlow(("vgdrvNtDeleteDevExtFundament:\n"));
+    VGDrvCommonDeleteDevExtFundament(&pDevExt->Core);
+    RTCritSectRwDelete(&pDevExt->SessionCreateCritSect);
+}
+
+
+#ifdef LOG_ENABLED
+/**
+ * Debug helper to dump a device resource list.
+ *
+ * @param pResourceList  list of device resources.
+ */
+static void vgdrvNtShowDeviceResources(PCM_RESOURCE_LIST pRsrcList)
+{
+    for (uint32_t iList = 0; iList < pRsrcList->Count; iList++)
+    {
+        PCM_FULL_RESOURCE_DESCRIPTOR pList = &pRsrcList->List[iList];
+        LogFunc(("List #%u: InterfaceType=%#x BusNumber=%#x ListCount=%u ListRev=%#x ListVer=%#x\n",
+                 iList, pList->InterfaceType, pList->BusNumber, pList->PartialResourceList.Count,
+                 pList->PartialResourceList.Revision, pList->PartialResourceList.Version ));
+
+        PCM_PARTIAL_RESOURCE_DESCRIPTOR pResource = pList->PartialResourceList.PartialDescriptors;
+        for (ULONG i = 0; i < pList->PartialResourceList.Count; ++i, ++pResource)
+        {
+            ULONG uType = pResource->Type;
+            static char const * const s_apszName[] =
+            {
+                "CmResourceTypeNull",
+                "CmResourceTypePort",
+                "CmResourceTypeInterrupt",
+                "CmResourceTypeMemory",
+                "CmResourceTypeDma",
+                "CmResourceTypeDeviceSpecific",
+                "CmResourceTypeuBusNumber",
+                "CmResourceTypeDevicePrivate",
+                "CmResourceTypeAssignedResource",
+                "CmResourceTypeSubAllocateFrom",
+            };
+
+            if (uType < RT_ELEMENTS(s_apszName))
+                LogFunc(("  %.30s Flags=%#x Share=%#x", s_apszName[uType], pResource->Flags, pResource->ShareDisposition));
+            else
+                LogFunc(("  Type=%#x Flags=%#x Share=%#x", uType, pResource->Flags, pResource->ShareDisposition));
+            switch (uType)
+            {
+                case CmResourceTypePort:
+                case CmResourceTypeMemory:
+                    Log(("  Start %#RX64, length=%#x\n", pResource->u.Port.Start.QuadPart, pResource->u.Port.Length));
+                    break;
+
+                case CmResourceTypeInterrupt:
+                    Log(("  Level=%X, vector=%#x, affinity=%#x\n",
+                             pResource->u.Interrupt.Level, pResource->u.Interrupt.Vector, pResource->u.Interrupt.Affinity));
+                    break;
+
+                case CmResourceTypeDma:
+                    Log(("  Channel %d, Port %#x\n", pResource->u.Dma.Channel, pResource->u.Dma.Port));
+                    break;
+
+                default:
+                    Log(("\n"));
+                    break;
+            }
+        }
+    }
+}
+#endif /* LOG_ENABLED */
+
+
+/**
+ * Helper to scan the PCI resource list and remember stuff.
+ *
+ * @param   pDevExt         The device extension.
+ * @param   pResList        Resource list
+ * @param   fTranslated     Whether the addresses are translated or not.
+ */
+static NTSTATUS vgdrvNtScanPCIResourceList(PVBOXGUESTDEVEXTWIN pDevExt, PCM_RESOURCE_LIST pResList, bool fTranslated)
+{
+    LogFlowFunc(("Found %d resources\n", pResList->List->PartialResourceList.Count));
+    PCM_PARTIAL_RESOURCE_DESCRIPTOR pPartialData = NULL;
+    bool                            fGotIrq      = false;
+    bool                            fGotMmio     = false;
+    bool                            fGotIoPorts  = false;
+    NTSTATUS                        rc           = STATUS_SUCCESS;
+    for (ULONG i = 0; i < pResList->List->PartialResourceList.Count; i++)
+    {
+        pPartialData = &pResList->List->PartialResourceList.PartialDescriptors[i];
+        switch (pPartialData->Type)
+        {
+            case CmResourceTypePort:
+                LogFlowFunc(("I/O range: Base=%#RX64, length=%08x\n",
+                             pPartialData->u.Port.Start.QuadPart, pPartialData->u.Port.Length));
+                /* Save the first I/O port base. */
+                if (!fGotIoPorts)
+                {
+                    pDevExt->Core.IOPortBase = (RTIOPORT)pPartialData->u.Port.Start.LowPart;
+                    fGotIoPorts = true;
+                    LogFunc(("I/O range for VMMDev found! Base=%#RX64, length=%08x\n",
+                             pPartialData->u.Port.Start.QuadPart, pPartialData->u.Port.Length));
+                }
+                else
+                    LogRelFunc(("More than one I/O port range?!?\n"));
+                break;
+
+            case CmResourceTypeInterrupt:
+                LogFunc(("Interrupt: Level=%x, vector=%x, mode=%x\n",
+                         pPartialData->u.Interrupt.Level, pPartialData->u.Interrupt.Vector, pPartialData->Flags));
+                if (!fGotIrq)
+                {
+                    /* Save information. */
+                    pDevExt->uInterruptLevel    = pPartialData->u.Interrupt.Level;
+                    pDevExt->uInterruptVector   = pPartialData->u.Interrupt.Vector;
+                    pDevExt->fInterruptAffinity = pPartialData->u.Interrupt.Affinity;
+
+                    /* Check interrupt mode. */
+                    if (pPartialData->Flags & CM_RESOURCE_INTERRUPT_LATCHED)
+                        pDevExt->enmInterruptMode = Latched;
+                    else
+                        pDevExt->enmInterruptMode = LevelSensitive;
+                    fGotIrq = true;
+                    LogFunc(("Interrupt for VMMDev found! Vector=%#x Level=%#x Affinity=%zx Mode=%d\n", pDevExt->uInterruptVector,
+                             pDevExt->uInterruptLevel, pDevExt->fInterruptAffinity, pDevExt->enmInterruptMode));
+                }
+                else
+                    LogFunc(("More than one IRQ resource!\n"));
+                break;
+
+            case CmResourceTypeMemory:
+                LogFlowFunc(("Memory range: Base=%#RX64, length=%08x\n",
+                             pPartialData->u.Memory.Start.QuadPart, pPartialData->u.Memory.Length));
+                /* We only care about the first read/write memory range. */
+                if (   !fGotMmio
+                    && (pPartialData->Flags & CM_RESOURCE_MEMORY_WRITEABILITY_MASK) == CM_RESOURCE_MEMORY_READ_WRITE)
+                {
+                    /* Save physical MMIO base + length for VMMDev. */
+                    pDevExt->uVmmDevMemoryPhysAddr = pPartialData->u.Memory.Start;
+                    pDevExt->cbVmmDevMemory = (ULONG)pPartialData->u.Memory.Length;
+
+                    if (!fTranslated)
+                    {
+                        /* Technically we need to make the HAL translate the address.  since we
+                           didn't used to do this and it probably just returns the input address,
+                           we allow ourselves to ignore failures. */
+                        ULONG               uAddressSpace = 0;
+                        PHYSICAL_ADDRESS    PhysAddr = pPartialData->u.Memory.Start;
+                        if (HalTranslateBusAddress(pResList->List->InterfaceType, pResList->List->BusNumber, PhysAddr,
+                                                   &uAddressSpace, &PhysAddr))
+                        {
+                            Log(("HalTranslateBusAddress(%#RX64) -> %RX64, type %#x\n",
+                                 pPartialData->u.Memory.Start.QuadPart, PhysAddr.QuadPart, uAddressSpace));
+                            if (pPartialData->u.Memory.Start.QuadPart != PhysAddr.QuadPart)
+                                pDevExt->uVmmDevMemoryPhysAddr = PhysAddr;
+                        }
+                        else
+                            Log(("HalTranslateBusAddress(%#RX64) -> failed!\n", pPartialData->u.Memory.Start.QuadPart));
+                    }
+
+                    fGotMmio = true;
+                    LogFunc(("Found memory range for VMMDev! Base = %#RX64, Length = %08x\n",
+                             pPartialData->u.Memory.Start.QuadPart, pPartialData->u.Memory.Length));
+                }
+                else
+                    LogFunc(("Ignoring memory: Flags=%08x Base=%#RX64\n",
+                             pPartialData->Flags, pPartialData->u.Memory.Start.QuadPart));
+                break;
+
+            default:
+                LogFunc(("Unhandled resource found, type=%d\n", pPartialData->Type));
+                break;
+        }
+    }
+    return rc;
+}
+
+
+#ifdef TARGET_NT4
+
+/**
+ * Scans the PCI resources on NT 3.1.
+ *
+ * @returns STATUS_SUCCESS or STATUS_DEVICE_CONFIGURATION_ERROR.
+ * @param   pDevExt     The device extension.
+ * @param   uBus        The bus number.
+ * @param   uSlot       The PCI slot to scan.
+ */
+static NTSTATUS vgdrvNt31ScanSlotResources(PVBOXGUESTDEVEXTWIN pDevExt, ULONG uBus, ULONG uSlot)
+{
+    /*
+     * Disable memory mappings so we can determin the BAR lengths
+     * without upsetting other mappings.
+     */
+    uint16_t fCmd = 0;
+    g_pfnHalGetBusDataByOffset(PCIConfiguration, uBus, uSlot, &fCmd, VBOX_PCI_COMMAND, sizeof(fCmd));
+    if (fCmd & VBOX_PCI_COMMAND_MEMORY)
+    {
+        uint16_t fCmdTmp = fCmd & ~VBOX_PCI_COMMAND_MEMORY;
+        g_pfnHalSetBusDataByOffset(PCIConfiguration, uBus, uSlot, &fCmdTmp, VBOX_PCI_COMMAND, sizeof(fCmdTmp));
+    }
+
+    /*
+     * Scan the address resources first.
+     */
+    uint32_t aBars[6] = { UINT32_MAX, UINT32_MAX, UINT32_MAX, UINT32_MAX, UINT32_MAX, UINT32_MAX };
+    g_pfnHalGetBusDataByOffset(PCIConfiguration, uBus, uSlot, &aBars, VBOX_PCI_BASE_ADDRESS_0, sizeof(aBars));
+
+    bool fGotMmio    = false;
+    bool fGotIoPorts = false;
+    for (uint32_t i = 0; i < RT_ELEMENTS(aBars); i++)
+    {
+        uint32_t uBar = aBars[i];
+        if (uBar == UINT32_MAX)
+            continue;
+        if ((uBar & 1) == PCI_ADDRESS_SPACE_IO)
+        {
+            uint32_t uAddr = uBar & UINT32_C(0xfffffffc);
+            if (!uAddr)
+                continue;
+            if (!fGotIoPorts)
+            {
+                pDevExt->Core.IOPortBase = (uint16_t)uAddr & UINT16_C(0xfffc);
+                fGotIoPorts = true;
+                LogFunc(("I/O range for VMMDev found in BAR%u! %#x\n", i, pDevExt->Core.IOPortBase));
+            }
+            else
+                LogRelFunc(("More than one I/O port range?!? BAR%u=%#x\n", i, uBar));
+        }
+        else
+        {
+            uint32_t uAddr = uBar & UINT32_C(0xfffffff0);
+            if (!uAddr)
+                continue;
+
+            if (!fGotMmio)
+            {
+                /* Figure the length by trying to set all address bits and seeing
+                   how many we're allowed to set. */
+                uint32_t iBit = 4;
+                while (!(uAddr & RT_BIT_32(iBit)))
+                    iBit++;
+
+                uint32_t const offPciBar = VBOX_PCI_BASE_ADDRESS_0 + i * 4;
+                uint32_t       uTmpBar   = uBar | ((RT_BIT_32(iBit) - 1) & UINT32_C(0xfffffff0));
+                g_pfnHalSetBusDataByOffset(PCIConfiguration, uBus, uSlot, &uTmpBar, offPciBar, sizeof(uTmpBar));
+                uTmpBar = uBar;
+                g_pfnHalGetBusDataByOffset(PCIConfiguration, uBus, uSlot, &uTmpBar, offPciBar, sizeof(uTmpBar));
+                g_pfnHalSetBusDataByOffset(PCIConfiguration, uBus, uSlot, &uBar,    offPciBar, sizeof(uBar));
+
+                while (iBit > 4 && (uTmpBar & RT_BIT_32(iBit - 1)))
+                    iBit--;
+
+                /* got it */
+                pDevExt->cbVmmDevMemory = RT_BIT_32(iBit);
+                pDevExt->uVmmDevMemoryPhysAddr.QuadPart = uAddr;
+                fGotMmio = true;
+                LogFunc(("Found memory range for VMMDev in BAR%u! %#RX64 LB %#x (raw %#x)\n",
+                         i, pDevExt->uVmmDevMemoryPhysAddr.QuadPart, pDevExt->cbVmmDevMemory, uBar));
+            }
+            else
+                LogFunc(("Ignoring memory: BAR%u=%#x\n", i, uBar));
+        }
+    }
+
+    /*
+     * Get the IRQ
+     */
+    struct
+    {
+        uint8_t bInterruptLine;
+        uint8_t bInterruptPin;
+    } Buf = { 0, 0 };
+    g_pfnHalGetBusDataByOffset(PCIConfiguration, uBus, uSlot, &Buf, VBOX_PCI_INTERRUPT_LINE, sizeof(Buf));
+    if (Buf.bInterruptPin != 0)
+    {
+        pDevExt->uInterruptVector   = Buf.bInterruptLine;
+        pDevExt->uInterruptLevel    = Buf.bInterruptLine;
+        pDevExt->enmInterruptMode   = LevelSensitive;
+        pDevExt->fInterruptAffinity = RT_BIT_32(RTMpGetCount()) - 1;
+        LogFunc(("Interrupt for VMMDev found! Vector=%#x Level=%#x Affinity=%zx Mode=%d\n",
+                 pDevExt->uInterruptVector, pDevExt->uInterruptLevel, pDevExt->fInterruptAffinity, pDevExt->enmInterruptMode));
+    }
+
+    /*
+     * Got what we need?
+     */
+    if (fGotIoPorts && (!fGotMmio || Buf.bInterruptPin != 0))
+    {
+        /*
+         * Enable both MMIO, I/O space and busmastering so we can use the device.
+         */
+        uint16_t fCmdNew = fCmd | VBOX_PCI_COMMAND_IO | VBOX_PCI_COMMAND_MEMORY | VBOX_PCI_COMMAND_MASTER;
+        g_pfnHalSetBusDataByOffset(PCIConfiguration, uBus, uSlot, &fCmdNew, VBOX_PCI_COMMAND, sizeof(fCmdNew));
+
+        return STATUS_SUCCESS;
+    }
+
+    /* No. Complain, restore device command value and return failure. */
+    if (!fGotIoPorts)
+        LogRel(("VBoxGuest: Did not find I/O port range: %#x %#x %#x %#x %#x %#x\n",
+                aBars[0], aBars[1], aBars[2], aBars[3], aBars[4], aBars[5]));
+    if (!fGotMmio || Buf.bInterruptPin != 0)
+        LogRel(("VBoxGuest: Got MMIO but no interrupts!\n"));
+
+    g_pfnHalSetBusDataByOffset(PCIConfiguration, uBus, uSlot, &fCmd, VBOX_PCI_COMMAND, sizeof(fCmd));
+    return STATUS_DEVICE_CONFIGURATION_ERROR;
+}
+
+#endif /* TARGET_NT4 */
+
+/**
+ * Unmaps the VMMDev I/O range from kernel space.
+ *
+ * @param   pDevExt     The device extension.
+ */
+static void vgdrvNtUnmapVMMDevMemory(PVBOXGUESTDEVEXTWIN pDevExt)
+{
+    LogFlowFunc(("pVMMDevMemory = %#x\n", pDevExt->Core.pVMMDevMemory));
+    if (pDevExt->Core.pVMMDevMemory)
+    {
+        MmUnmapIoSpace((void*)pDevExt->Core.pVMMDevMemory, pDevExt->cbVmmDevMemory);
+        pDevExt->Core.pVMMDevMemory = NULL;
+    }
+
+    pDevExt->uVmmDevMemoryPhysAddr.QuadPart = 0;
+    pDevExt->cbVmmDevMemory = 0;
+}
+
+
+/**
+ * Maps the I/O space from VMMDev to virtual kernel address space.
+ *
+ * @return NTSTATUS
+ *
+ * @param pDevExt           The device extension.
+ * @param PhysAddr          Physical address to map.
+ * @param cbToMap           Number of bytes to map.
+ * @param ppvMMIOBase       Pointer of mapped I/O base.
+ * @param pcbMMIO           Length of mapped I/O base.
+ */
+static NTSTATUS vgdrvNtMapVMMDevMemory(PVBOXGUESTDEVEXTWIN pDevExt, PHYSICAL_ADDRESS PhysAddr, ULONG cbToMap,
+                                       void **ppvMMIOBase, uint32_t *pcbMMIO)
+{
+    AssertPtrReturn(pDevExt, VERR_INVALID_POINTER);
+    AssertPtrReturn(ppvMMIOBase, VERR_INVALID_POINTER);
+    /* pcbMMIO is optional. */
+
+    NTSTATUS rc = STATUS_SUCCESS;
+    if (PhysAddr.LowPart > 0) /* We're mapping below 4GB. */
+    {
+         VMMDevMemory *pVMMDevMemory = (VMMDevMemory *)MmMapIoSpace(PhysAddr, cbToMap, MmNonCached);
+         LogFlowFunc(("pVMMDevMemory = %#x\n", pVMMDevMemory));
+         if (pVMMDevMemory)
+         {
+             LogFunc(("VMMDevMemory: Version = %#x, Size = %d\n", pVMMDevMemory->u32Version, pVMMDevMemory->u32Size));
+
+             /* Check version of the structure; do we have the right memory version? */
+             if (pVMMDevMemory->u32Version == VMMDEV_MEMORY_VERSION)
+             {
+                 /* Save results. */
+                 *ppvMMIOBase = pVMMDevMemory;
+                 if (pcbMMIO) /* Optional. */
+                     *pcbMMIO = pVMMDevMemory->u32Size;
+
+                 LogFlowFunc(("VMMDevMemory found and mapped! pvMMIOBase = 0x%p\n", *ppvMMIOBase));
+             }
+             else
+             {
+                 /* Not our version, refuse operation and unmap the memory. */
+                 LogFunc(("Wrong version (%u), refusing operation!\n", pVMMDevMemory->u32Version));
+
+                 vgdrvNtUnmapVMMDevMemory(pDevExt);
+                 rc = STATUS_UNSUCCESSFUL;
+             }
+         }
+         else
+             rc = STATUS_UNSUCCESSFUL;
+    }
+    return rc;
+}
+
+
+/**
+ * Sets up the device and its resources.
+ *
+ * @param   pDevExt     Our device extension data.
+ * @param   pDevObj     The device object.
+ * @param   pIrp        The request packet if NT5+, NULL for NT4 and earlier.
+ * @param   pDrvObj     The driver object for NT4, NULL for NT5+.
+ * @param   pRegPath    The registry path for NT4, NULL for NT5+.
+ */
+static NTSTATUS vgdrvNtSetupDevice(PVBOXGUESTDEVEXTWIN pDevExt, PDEVICE_OBJECT pDevObj,
+                                   PIRP pIrp, PDRIVER_OBJECT pDrvObj, PUNICODE_STRING pRegPath)
+{
+    LogFlowFunc(("ENTER: pDevExt=%p pDevObj=%p pIrq=%p pDrvObj=%p pRegPath=%p\n", pDevExt, pDevObj, pIrp, pDrvObj, pRegPath));
+
+    NTSTATUS rcNt;
+    if (!pIrp)
+    {
+#ifdef TARGET_NT4
+        /*
+         * NT4, NT3.x: Let's have a look at what our PCI adapter offers.
+         */
+        LogFlowFunc(("Starting to scan PCI resources of VBoxGuest ...\n"));
+
+        /* Assign the PCI resources. */
+        UNICODE_STRING      ClassName;
+        RtlInitUnicodeString(&ClassName, L"VBoxGuestAdapter");
+        PCM_RESOURCE_LIST   pResourceList = NULL;
+        if (g_pfnHalAssignSlotResources)
+        {
+            rcNt = g_pfnHalAssignSlotResources(pRegPath, &ClassName, pDrvObj, pDevObj, PCIBus, pDevExt->uBus, pDevExt->uSlot,
+                                               &pResourceList);
+# ifdef LOG_ENABLED
+            if (pResourceList)
+                vgdrvNtShowDeviceResources(pResourceList);
+# endif
+            if (NT_SUCCESS(rcNt))
+            {
+                rcNt = vgdrvNtScanPCIResourceList(pDevExt, pResourceList, false /*fTranslated*/);
+                ExFreePool(pResourceList);
+            }
+        }
+        else
+            rcNt = vgdrvNt31ScanSlotResources(pDevExt, pDevExt->uBus, pDevExt->uSlot);
+
+# else  /* !TARGET_NT4 */
+        AssertFailed();
+        RT_NOREF(pDevObj, pDrvObj, pRegPath);
+        rcNt = STATUS_INTERNAL_ERROR;
+# endif /* !TARGET_NT4 */
+    }
+    else
+    {
+        /*
+         * NT5+: Scan the PCI resource list from the IRP.
+         */
+        PIO_STACK_LOCATION pStack = IoGetCurrentIrpStackLocation(pIrp);
+# ifdef LOG_ENABLED
+        vgdrvNtShowDeviceResources(pStack->Parameters.StartDevice.AllocatedResourcesTranslated);
+# endif
+        rcNt = vgdrvNtScanPCIResourceList(pDevExt, pStack->Parameters.StartDevice.AllocatedResourcesTranslated,
+                                          true /*fTranslated*/);
+    }
+    if (NT_SUCCESS(rcNt))
+    {
+        /*
+         * Map physical address of VMMDev memory into MMIO region
+         * and init the common device extension bits.
+         */
+        void    *pvMMIOBase = NULL;
+        uint32_t cbMMIO     = 0;
+        rcNt = vgdrvNtMapVMMDevMemory(pDevExt,
+                                      pDevExt->uVmmDevMemoryPhysAddr,
+                                      pDevExt->cbVmmDevMemory,
+                                      &pvMMIOBase,
+                                      &cbMMIO);
+        if (NT_SUCCESS(rcNt))
+        {
+            pDevExt->Core.pVMMDevMemory = (VMMDevMemory *)pvMMIOBase;
+
+            LogFunc(("pvMMIOBase=0x%p, pDevExt=0x%p, pDevExt->Core.pVMMDevMemory=0x%p\n",
+                     pvMMIOBase, pDevExt, pDevExt ? pDevExt->Core.pVMMDevMemory : NULL));
+
+            int vrc = VGDrvCommonInitDevExtResources(&pDevExt->Core,
+                                                     pDevExt->Core.IOPortBase,
+                                                     pvMMIOBase, cbMMIO,
+                                                     vgdrvNtVersionToOSType(g_enmVGDrvNtVer),
+                                                     VMMDEV_EVENT_MOUSE_POSITION_CHANGED);
+            if (RT_SUCCESS(vrc))
+            {
+
+                vrc = VbglR0GRAlloc((VMMDevRequestHeader **)&pDevExt->pPowerStateRequest,
+                                    sizeof(VMMDevPowerStateRequest), VMMDevReq_SetPowerStatus);
+                if (RT_SUCCESS(vrc))
+                {
+                    /*
+                     * Register DPC and ISR.
+                     */
+                    LogFlowFunc(("Initializing DPC/ISR (pDevObj=%p)...\n", pDevExt->pDeviceObject));
+                    IoInitializeDpcRequest(pDevExt->pDeviceObject, vgdrvNtDpcHandler);
+
+                    ULONG uInterruptVector = pDevExt->uInterruptVector;
+                    KIRQL uHandlerIrql     = (KIRQL)pDevExt->uInterruptLevel;
+#ifdef TARGET_NT4
+                    if (!pIrp)
+                    {
+                        /* NT4: Get an interrupt vector.  Only proceed if the device provides an interrupt. */
+                        if (   uInterruptVector
+                            || pDevExt->uInterruptLevel)
+                        {
+                            LogFlowFunc(("Getting interrupt vector (HAL): Bus=%u, IRQL=%u, Vector=%u\n",
+                                         pDevExt->uBus, pDevExt->uInterruptLevel, pDevExt->uInterruptVector));
+                            uInterruptVector = HalGetInterruptVector(g_enmVGDrvNtVer == VGDRVNTVER_WINNT310 ? Isa : PCIBus,
+                                                                     pDevExt->uBus,
+                                                                     pDevExt->uInterruptLevel,
+                                                                     pDevExt->uInterruptVector,
+                                                                     &uHandlerIrql,
+                                                                     &pDevExt->fInterruptAffinity);
+                            LogFlowFunc(("HalGetInterruptVector returns vector=%u\n", uInterruptVector));
+                        }
+                        else
+                            LogFunc(("Device does not provide an interrupt!\n"));
+                    }
+#endif
+                    if (uInterruptVector)
+                    {
+                        LogFlowFunc(("Connecting interrupt (IntVector=%#u), uHandlerIrql=%u) ...\n",
+                                     uInterruptVector, uHandlerIrql));
+
+                        rcNt = IoConnectInterrupt(&pDevExt->pInterruptObject,                 /* Out: interrupt object. */
+                                                  vgdrvNtIsrHandler,                          /* Our ISR handler. */
+                                                  pDevExt,                                    /* Device context. */
+                                                  NULL,                                       /* Optional spinlock. */
+                                                  uInterruptVector,                           /* Interrupt vector. */
+                                                  uHandlerIrql,                               /* Irql. */
+                                                  uHandlerIrql,                               /* SynchronizeIrql. */
+                                                  pDevExt->enmInterruptMode,                  /* LevelSensitive or Latched. */
+                                                  TRUE,                                       /* Shareable interrupt. */
+                                                  pDevExt->fInterruptAffinity,                /* CPU affinity. */
+                                                  FALSE);                                     /* Don't save FPU stack. */
+                        if (NT_ERROR(rcNt))
+                            LogFunc(("Could not connect interrupt: rcNt=%#x!\n", rcNt));
+                    }
+                    else
+                        LogFunc(("No interrupt vector found!\n"));
+                    if (NT_SUCCESS(rcNt))
+                    {
+                        /*
+                         * Once we've read configuration from register and host, we're finally read.
+                         */
+                        /** @todo clean up guest ring-3 logging, keeping it separate from the kernel to avoid sharing limits with it. */
+                        pDevExt->Core.fLoggingEnabled = true;
+                        vgdrvNtReadConfiguration(pDevExt);
+
+                        /* Ready to rumble! */
+                        LogRelFunc(("Device is ready!\n"));
+                        pDevExt->enmDevState     = VGDRVNTDEVSTATE_OPERATIONAL;
+                        pDevExt->enmPrevDevState = VGDRVNTDEVSTATE_OPERATIONAL;
+                        return STATUS_SUCCESS;
+                    }
+
+                    pDevExt->pInterruptObject = NULL;
+
+                    VbglR0GRFree(&pDevExt->pPowerStateRequest->header);
+                    pDevExt->pPowerStateRequest = NULL;
+                }
+                else
+                {
+                    LogFunc(("Alloc for pPowerStateRequest failed, vrc=%Rrc\n", vrc));
+                    rcNt = STATUS_UNSUCCESSFUL;
+                }
+
+                VGDrvCommonDeleteDevExtResources(&pDevExt->Core);
+            }
+            else
+            {
+                LogFunc(("Could not init device extension resources: vrc=%Rrc\n", vrc));
+                rcNt = STATUS_DEVICE_CONFIGURATION_ERROR;
+            }
+            vgdrvNtUnmapVMMDevMemory(pDevExt);
+        }
+        else
+            LogFunc(("Could not map physical address of VMMDev, rcNt=%#x\n", rcNt));
+    }
+
+    LogFunc(("Returned with rcNt=%#x\n", rcNt));
+    return rcNt;
+}
+
+
+
+
+#ifdef TARGET_NT4
+# define PCI_CFG_ADDR   0xcf8
+# define PCI_CFG_DATA   0xcfc
+
+/**
+ * NT 3.1 doesn't do PCI nor HalSetBusDataByOffset, this is our fallback.
+ */
+static ULONG NTAPI vgdrvNt31SetBusDataByOffset(BUS_DATA_TYPE enmBusDataType, ULONG idxBus, ULONG uSlot,
+                                               void *pvData, ULONG offData, ULONG cbData)
+{
+    /*
+     * Validate input a little bit.
+     */
+    RT_NOREF(enmBusDataType);
+    Assert(idxBus  <= 255);
+    Assert(uSlot   <= 255);
+    Assert(offData <= 255);
+    Assert(cbData > 0);
+
+    PCI_SLOT_NUMBER PciSlot;
+    PciSlot.u.AsULONG = uSlot;
+    uint32_t const idxAddrTop = UINT32_C(0x80000000)
+                              | (idxBus                        << 16)
+                              | (PciSlot.u.bits.DeviceNumber   << 11)
+                              | (PciSlot.u.bits.FunctionNumber << 8);
+
+    /*
+     * Write the given bytes.
+     */
+    uint8_t const *pbData = (uint8_t const *)pvData;
+    uint32_t       off    = offData;
+    uint32_t       cbRet  = 0;
+
+    /* Unaligned start. */
+    if (off & 3)
+    {
+        ASMOutU32(PCI_CFG_ADDR, idxAddrTop | (off & ~3));
+        switch (off & 3)
+        {
+            case 1:
+                ASMOutU8(PCI_CFG_DATA + 1, pbData[cbRet++]);
+                if (cbRet >= cbData)
+                    break;
+                RT_FALL_THRU();
+            case 2:
+                ASMOutU8(PCI_CFG_DATA + 2, pbData[cbRet++]);
+                if (cbRet >= cbData)
+                    break;
+                RT_FALL_THRU();
+            case 3:
+                ASMOutU8(PCI_CFG_DATA + 3, pbData[cbRet++]);
+                break;
+        }
+        off = (off | 3) + 1;
+    }
+
+    /* Bulk. */
+    while (off < 256 && cbRet < cbData)
+    {
+        ASMOutU32(PCI_CFG_ADDR, idxAddrTop | off);
+        switch (cbData - cbRet)
+        {
+            case 1:
+                ASMOutU8(PCI_CFG_DATA, pbData[cbRet]);
+                cbRet += 1;
+                break;
+            case 2:
+                ASMOutU16(PCI_CFG_DATA, RT_MAKE_U16(pbData[cbRet], pbData[cbRet + 1]));
+                cbRet += 2;
+                break;
+            case 3:
+                ASMOutU16(PCI_CFG_DATA, RT_MAKE_U16(pbData[cbRet], pbData[cbRet + 1]));
+                ASMOutU8(PCI_CFG_DATA + 2, pbData[cbRet + 2]);
+                cbRet += 3;
+                break;
+            default:
+                ASMOutU32(PCI_CFG_DATA, RT_MAKE_U32_FROM_U8(pbData[cbRet], pbData[cbRet + 1],
+                                                            pbData[cbRet + 2], pbData[cbRet + 3]));
+                cbRet += 4;
+                break;
+        }
+        off += 4;
+    }
+
+    return cbRet;
+}
+
+
+/**
+ * NT 3.1 doesn't do PCI nor HalGetBusDataByOffset, this is our fallback.
+ */
+static ULONG NTAPI vgdrvNt31GetBusDataByOffset(BUS_DATA_TYPE enmBusDataType, ULONG idxBus, ULONG uSlot,
+                                               void *pvData, ULONG offData, ULONG cbData)
+{
+    /*
+     * Validate input a little bit.
+     */
+    RT_NOREF(enmBusDataType);
+    Assert(idxBus  <= 255);
+    Assert(uSlot   <= 255);
+    Assert(offData <= 255);
+    Assert(cbData > 0);
+
+    PCI_SLOT_NUMBER PciSlot;
+    PciSlot.u.AsULONG = uSlot;
+    uint32_t const idxAddrTop = UINT32_C(0x80000000)
+                              | (idxBus                        << 16)
+                              | (PciSlot.u.bits.DeviceNumber   << 11)
+                              | (PciSlot.u.bits.FunctionNumber << 8);
+
+    /*
+     * Read the header type.
+     */
+    ASMOutU32(PCI_CFG_ADDR,  idxAddrTop | (VBOX_PCI_HEADER_TYPE & ~3));
+    uint8_t bHdrType = ASMInU8(PCI_CFG_DATA + (VBOX_PCI_HEADER_TYPE & 3));
+    if (bHdrType == 0xff)
+        return idxBus < 8 ? 2 : 0; /* No device here */
+    if (   offData == VBOX_PCI_HEADER_TYPE
+        && cbData == 1)
+    {
+        *(uint8_t *)pvData = bHdrType;
+        /*Log("vgdrvNt31GetBusDataByOffset: PCI %#x/%#x -> %02x\n", idxAddrTop, offData, bHdrType);*/
+        return 1;
+    }
+
+    /*
+     * Read the requested bytes.
+     */
+    uint8_t *pbData = (uint8_t *)pvData;
+    uint32_t off    = offData;
+    uint32_t cbRet  = 0;
+
+    /* Unaligned start. */
+    if (off & 3)
+    {
+        ASMOutU32(PCI_CFG_ADDR, idxAddrTop | (off & ~3));
+        uint32_t uValue = ASMInU32(PCI_CFG_DATA);
+        switch (off & 3)
+        {
+            case 1:
+                pbData[cbRet++] = (uint8_t)(uValue >> 8);
+                if (cbRet >= cbData)
+                    break;
+                RT_FALL_THRU();
+            case 2:
+                pbData[cbRet++] = (uint8_t)(uValue >> 16);
+                if (cbRet >= cbData)
+                    break;
+                RT_FALL_THRU();
+            case 3:
+                pbData[cbRet++] = (uint8_t)(uValue >> 24);
+                break;
+        }
+        off = (off | 3) + 1;
+    }
+
+    /* Bulk. */
+    while (off < 256 && cbRet < cbData)
+    {
+        ASMOutU32(PCI_CFG_ADDR, idxAddrTop | off);
+        uint32_t uValue = ASMInU32(PCI_CFG_DATA);
+        switch (cbData - cbRet)
+        {
+            case 1:
+                pbData[cbRet++] = (uint8_t)uValue;
+                break;
+            case 2:
+                pbData[cbRet++] = (uint8_t)uValue;
+                pbData[cbRet++] = (uint8_t)(uValue >> 8);
+                break;
+            case 3:
+                pbData[cbRet++] = (uint8_t)uValue;
+                pbData[cbRet++] = (uint8_t)(uValue >> 8);
+                pbData[cbRet++] = (uint8_t)(uValue >> 16);
+                break;
+            default:
+                pbData[cbRet++] = (uint8_t)uValue;
+                pbData[cbRet++] = (uint8_t)(uValue >> 8);
+                pbData[cbRet++] = (uint8_t)(uValue >> 16);
+                pbData[cbRet++] = (uint8_t)(uValue >> 24);
+                break;
+        }
+        off += 4;
+    }
+
+    Log(("vgdrvNt31GetBusDataByOffset: PCI %#x/%#x -> %.*Rhxs\n", idxAddrTop, offData, cbRet, pvData));
+    return cbRet;
+}
+
+
+/**
+ * Helper function to handle the PCI device lookup.
+ *
+ * @returns NT status code.
+ *
+ * @param   puBus           Where to return the bus number on success.
+ * @param   pSlot           Where to return the slot number on success.
+ */
+static NTSTATUS vgdrvNt4FindPciDevice(PULONG puBus, PPCI_SLOT_NUMBER pSlot)
+{
+    Log(("vgdrvNt4FindPciDevice\n"));
+
+    PCI_SLOT_NUMBER Slot;
+    Slot.u.AsULONG = 0;
+
+    /* Scan each bus. */
+    for (ULONG uBus = 0; uBus < PCI_MAX_BUSES; uBus++)
+    {
+        /* Scan each device. */
+        for (ULONG idxDevice = 0; idxDevice < PCI_MAX_DEVICES; idxDevice++)
+        {
+            Slot.u.bits.DeviceNumber   = idxDevice;
+            Slot.u.bits.FunctionNumber = 0;
+
+            /* Check the device header. */
+            uint8_t bHeaderType = 0xff;
+            ULONG cbRet = g_pfnHalGetBusDataByOffset(PCIConfiguration, uBus, Slot.u.AsULONG,
+                                                     &bHeaderType, VBOX_PCI_HEADER_TYPE, sizeof(bHeaderType));
+            if (cbRet == 0)
+                break;
+            if (cbRet == 2 || bHeaderType == 0xff)
+                continue;
+
+            /* Scan functions. */
+            uint32_t const cFunctionStep = bHeaderType & 0x80 ? 1 : 8;
+            Log(("vgdrvNt4FindPciDevice: %#x:%#x cFunctionStep=%d bHeaderType=%#x\n", uBus, idxDevice, cFunctionStep, bHeaderType));
+            for (ULONG idxFunction = 0; idxFunction < PCI_MAX_FUNCTION; idxFunction += cFunctionStep)
+            {
+                Slot.u.bits.FunctionNumber = idxFunction;
+
+                /* Read the vendor and device IDs of this device and compare with the VMMDev. */
+                struct
+                {
+                    uint16_t idVendor;
+                    uint16_t idDevice;
+                } Buf = { PCI_INVALID_VENDORID, PCI_INVALID_VENDORID };
+                cbRet = g_pfnHalGetBusDataByOffset(PCIConfiguration, uBus, Slot.u.AsULONG, &Buf, VBOX_PCI_VENDOR_ID, sizeof(Buf));
+                if (   cbRet == sizeof(Buf)
+                    && Buf.idVendor == VMMDEV_VENDORID
+                    && Buf.idDevice == VMMDEV_DEVICEID)
+                {
+                    /* Hooray, we've found it! */
+                    Log(("vgdrvNt4FindPciDevice: Device found! Bus=%#x Slot=%#u (dev %#x, fun %#x, rvd %#x)\n",
+                         uBus, Slot.u.AsULONG, Slot.u.bits.DeviceNumber, Slot.u.bits.FunctionNumber, Slot.u.bits.Reserved));
+
+                    *puBus  = uBus;
+                    *pSlot  = Slot;
+                    return STATUS_SUCCESS;
+                }
+            }
+        }
+    }
+
+    return STATUS_DEVICE_DOES_NOT_EXIST;
+}
+
+
+/**
+ * Legacy helper function to create the device object.
+ *
+ * @returns NT status code.
+ *
+ * @param   pDrvObj         The driver object.
+ * @param   pRegPath        The driver registry path.
+ */
+static NTSTATUS vgdrvNt4CreateDevice(PDRIVER_OBJECT pDrvObj, PUNICODE_STRING pRegPath)
+{
+    Log(("vgdrvNt4CreateDevice: pDrvObj=%p, pRegPath=%p\n", pDrvObj, pRegPath));
+
+    /*
+     * Find our virtual PCI device
+     */
+    ULONG           uBus;
+    PCI_SLOT_NUMBER uSlot;
+    NTSTATUS rc = vgdrvNt4FindPciDevice(&uBus, &uSlot);
+    if (NT_ERROR(rc))
+    {
+        Log(("vgdrvNt4CreateDevice: Device not found!\n"));
+        return rc;
+    }
+
+    /*
+     * Create device.
+     */
+    UNICODE_STRING DevName;
+    RtlInitUnicodeString(&DevName, VBOXGUEST_DEVICE_NAME_NT);
+    PDEVICE_OBJECT pDeviceObject = NULL;
+    rc = IoCreateDevice(pDrvObj, sizeof(VBOXGUESTDEVEXTWIN), &DevName, FILE_DEVICE_UNKNOWN, 0, FALSE, &pDeviceObject);
+    if (NT_SUCCESS(rc))
+    {
+        Log(("vgdrvNt4CreateDevice: Device created\n"));
+
+        UNICODE_STRING DosName;
+        RtlInitUnicodeString(&DosName, VBOXGUEST_DEVICE_NAME_DOS);
+        rc = IoCreateSymbolicLink(&DosName, &DevName);
+        if (NT_SUCCESS(rc))
+        {
+            Log(("vgdrvNt4CreateDevice: Symlink created\n"));
+
+            /*
+             * Setup the device extension.
+             */
+            Log(("vgdrvNt4CreateDevice: Setting up device extension ...\n"));
+            PVBOXGUESTDEVEXTWIN pDevExt = (PVBOXGUESTDEVEXTWIN)pDeviceObject->DeviceExtension;
+            int vrc = vgdrvNtInitDevExtFundament(pDevExt, pDeviceObject);
+            if (RT_SUCCESS(vrc))
+            {
+                /* Store bus and slot number we've queried before. */
+                pDevExt->uBus  = uBus;
+                pDevExt->uSlot = uSlot.u.AsULONG;
+
+                Log(("vgdrvNt4CreateDevice: Device extension created\n"));
+
+                /* Do the actual VBox init ... */
+                rc = vgdrvNtSetupDevice(pDevExt, pDeviceObject, NULL /*pIrp*/, pDrvObj, pRegPath);
+                if (NT_SUCCESS(rc))
+                {
+                    Log(("vgdrvNt4CreateDevice: Returning rc = 0x%x (success)\n", rc));
+                    return rc;
+                }
+
+                /* bail out */
+                vgdrvNtDeleteDevExtFundament(pDevExt);
+            }
+            IoDeleteSymbolicLink(&DosName);
+        }
+        else
+            Log(("vgdrvNt4CreateDevice: IoCreateSymbolicLink failed with rc = %#x\n", rc));
+        IoDeleteDevice(pDeviceObject);
+    }
+    else
+        Log(("vgdrvNt4CreateDevice: IoCreateDevice failed with rc = %#x\n", rc));
+    Log(("vgdrvNt4CreateDevice: Returning rc = 0x%x\n", rc));
+    return rc;
+}
+
+#endif /* TARGET_NT4 */
+
+/**
+ * Handle request from the Plug & Play subsystem.
+ *
+ * @returns NT status code
+ * @param   pDrvObj   Driver object
+ * @param   pDevObj   Device object
+ *
+ * @remarks Parts of this is duplicated in VBoxGuest-win-legacy.cpp.
+ */
+static NTSTATUS NTAPI vgdrvNtNt5PlusAddDevice(PDRIVER_OBJECT pDrvObj, PDEVICE_OBJECT pDevObj)
+{
+    LogFlowFuncEnter();
+
+    /*
+     * Create device.
+     */
+    UNICODE_STRING DevName;
+    RtlInitUnicodeString(&DevName, VBOXGUEST_DEVICE_NAME_NT);
+    PDEVICE_OBJECT pDeviceObject = NULL;
+    NTSTATUS rcNt = IoCreateDevice(pDrvObj, sizeof(VBOXGUESTDEVEXTWIN), &DevName, FILE_DEVICE_UNKNOWN, 0, FALSE, &pDeviceObject);
+    if (NT_SUCCESS(rcNt))
+    {
+        /*
+         * Create symbolic link (DOS devices).
+         */
+        UNICODE_STRING DosName;
+        RtlInitUnicodeString(&DosName, VBOXGUEST_DEVICE_NAME_DOS);
+        rcNt = IoCreateSymbolicLink(&DosName, &DevName);
+        if (NT_SUCCESS(rcNt))
+        {
+            /*
+             * Setup the device extension.
+             */
+            PVBOXGUESTDEVEXTWIN pDevExt = (PVBOXGUESTDEVEXTWIN)pDeviceObject->DeviceExtension;
+            rcNt = vgdrvNtInitDevExtFundament(pDevExt, pDeviceObject);
+            if (NT_SUCCESS(rcNt))
+            {
+                pDevExt->pNextLowerDriver = IoAttachDeviceToDeviceStack(pDeviceObject, pDevObj);
+                if (pDevExt->pNextLowerDriver != NULL)
+                {
+                    /* Ensure we are not called at elevated IRQL, even if our code isn't pagable any more. */
+                    pDeviceObject->Flags |= DO_POWER_PAGABLE;
+
+                    /* Driver is ready now. */
+                    pDeviceObject->Flags &= ~DO_DEVICE_INITIALIZING;
+                    LogFlowFunc(("Returning with rcNt=%#x (success)\n", rcNt));
+                    return rcNt;
+                }
+                LogFunc(("IoAttachDeviceToDeviceStack did not give a nextLowerDriver!\n"));
+                rcNt = STATUS_DEVICE_NOT_CONNECTED;
+                vgdrvNtDeleteDevExtFundament(pDevExt);
+            }
+
+            IoDeleteSymbolicLink(&DosName);
+        }
+        else
+            LogFunc(("IoCreateSymbolicLink failed with rcNt=%#x!\n", rcNt));
+        IoDeleteDevice(pDeviceObject);
+    }
+    else
+        LogFunc(("IoCreateDevice failed with rcNt=%#x!\n", rcNt));
+
+    LogFunc(("Returning with rcNt=%#x\n", rcNt));
+    return rcNt;
+}
+
+
+/**
+ * Irp completion routine for PnP Irps we send.
+ *
+ * @returns NT status code.
+ * @param   pDevObj   Device object.
+ * @param   pIrp      Request packet.
+ * @param   pEvent    Semaphore.
+ */
+static NTSTATUS vgdrvNt5PlusPnpIrpComplete(PDEVICE_OBJECT pDevObj, PIRP pIrp, PKEVENT pEvent)
+{
+    RT_NOREF2(pDevObj, pIrp);
+    KeSetEvent(pEvent, 0, FALSE);
+    return STATUS_MORE_PROCESSING_REQUIRED;
+}
+
+
+/**
+ * Helper to send a PnP IRP and wait until it's done.
+ *
+ * @returns NT status code.
+ * @param    pDevObj    Device object.
+ * @param    pIrp       Request packet.
+ * @param    fStrict    When set, returns an error if the IRP gives an error.
+ */
+static NTSTATUS vgdrvNt5PlusPnPSendIrpSynchronously(PDEVICE_OBJECT pDevObj, PIRP pIrp, BOOLEAN fStrict)
+{
+    KEVENT Event;
+
+    KeInitializeEvent(&Event, SynchronizationEvent, FALSE);
+
+    IoCopyCurrentIrpStackLocationToNext(pIrp);
+    IoSetCompletionRoutine(pIrp, (PIO_COMPLETION_ROUTINE)vgdrvNt5PlusPnpIrpComplete, &Event, TRUE, TRUE, TRUE);
+
+    NTSTATUS rcNt = IoCallDriver(pDevObj, pIrp);
+    if (rcNt == STATUS_PENDING)
+    {
+        KeWaitForSingleObject(&Event, Executive, KernelMode, FALSE, NULL);
+        rcNt = pIrp->IoStatus.Status;
+    }
+
+    if (   !fStrict
+        && (rcNt == STATUS_NOT_SUPPORTED || rcNt == STATUS_INVALID_DEVICE_REQUEST))
+    {
+        rcNt = STATUS_SUCCESS;
+    }
+
+    Log(("vgdrvNt5PlusPnPSendIrpSynchronously: Returning %#x\n", rcNt));
+    return rcNt;
+}
+
+
+/**
+ * Deletes the device hardware resources.
+ *
+ * Used during removal, stopping and legacy module unloading.
+ *
+ * @param   pDevExt         The device extension.
+ */
+static void vgdrvNtDeleteDeviceResources(PVBOXGUESTDEVEXTWIN pDevExt)
+{
+    if (pDevExt->pInterruptObject)
+    {
+        IoDisconnectInterrupt(pDevExt->pInterruptObject);
+        pDevExt->pInterruptObject = NULL;
+    }
+    pDevExt->pPowerStateRequest = NULL; /* Will be deleted by the following call. */
+    if (pDevExt->Core.uInitState == VBOXGUESTDEVEXT_INIT_STATE_RESOURCES)
+        VGDrvCommonDeleteDevExtResources(&pDevExt->Core);
+    vgdrvNtUnmapVMMDevMemory(pDevExt);
+}
+
+
+/**
+ * Deletes the device extension fundament and unlinks the device
+ *
+ * Used during removal and legacy module unloading.  Must have called
+ * vgdrvNtDeleteDeviceResources.
+ *
+ * @param   pDevObj         Device object.
+ * @param   pDevExt         The device extension.
+ */
+static void vgdrvNtDeleteDeviceFundamentAndUnlink(PDEVICE_OBJECT pDevObj, PVBOXGUESTDEVEXTWIN pDevExt)
+{
+    /*
+     * Delete the remainder of the device extension.
+     */
+    vgdrvNtDeleteDevExtFundament(pDevExt);
+
+    /*
+     * Delete the DOS symlink to the device and finally the device itself.
+     */
+    UNICODE_STRING DosName;
+    RtlInitUnicodeString(&DosName, VBOXGUEST_DEVICE_NAME_DOS);
+    IoDeleteSymbolicLink(&DosName);
+
+    Log(("vgdrvNtDeleteDeviceFundamentAndUnlink: Deleting device ...\n"));
+    IoDeleteDevice(pDevObj);
+}
+
+
+/**
+ * Checks if the device is idle.
+ * @returns STATUS_SUCCESS if idle, STATUS_UNSUCCESSFUL if busy.
+ * @param   pDevExt             The device extension.
+ * @param   pszQueryNm          The query name.
+ */
+static NTSTATUS vgdrvNtCheckIdle(PVBOXGUESTDEVEXTWIN pDevExt, const char *pszQueryNm)
+{
+    uint32_t cSessions = pDevExt->Core.cSessions;
+    if (cSessions == 0)
+        return STATUS_SUCCESS;
+    LogRel(("vgdrvNtCheckIdle/%s: cSessions=%d\n", pszQueryNm, cSessions));
+    return STATUS_UNSUCCESSFUL;
+}
+
+
+/**
+ * PnP Request handler.
+ *
+ * @param  pDevObj    Device object.
+ * @param  pIrp       Request packet.
+ */
+static NTSTATUS NTAPI vgdrvNtNt5PlusPnP(PDEVICE_OBJECT pDevObj, PIRP pIrp)
+{
+    PVBOXGUESTDEVEXTWIN pDevExt = (PVBOXGUESTDEVEXTWIN)pDevObj->DeviceExtension;
+    PIO_STACK_LOCATION  pStack  = IoGetCurrentIrpStackLocation(pIrp);
+
+#ifdef LOG_ENABLED
+    static char const * const s_apszFnctName[] =
+    {
+        "IRP_MN_START_DEVICE",
+        "IRP_MN_QUERY_REMOVE_DEVICE",
+        "IRP_MN_REMOVE_DEVICE",
+        "IRP_MN_CANCEL_REMOVE_DEVICE",
+        "IRP_MN_STOP_DEVICE",
+        "IRP_MN_QUERY_STOP_DEVICE",
+        "IRP_MN_CANCEL_STOP_DEVICE",
+        "IRP_MN_QUERY_DEVICE_RELATIONS",
+        "IRP_MN_QUERY_INTERFACE",
+        "IRP_MN_QUERY_CAPABILITIES",
+        "IRP_MN_QUERY_RESOURCES",
+        "IRP_MN_QUERY_RESOURCE_REQUIREMENTS",
+        "IRP_MN_QUERY_DEVICE_TEXT",
+        "IRP_MN_FILTER_RESOURCE_REQUIREMENTS",
+        "IRP_MN_0xE",
+        "IRP_MN_READ_CONFIG",
+        "IRP_MN_WRITE_CONFIG",
+        "IRP_MN_EJECT",
+        "IRP_MN_SET_LOCK",
+        "IRP_MN_QUERY_ID",
+        "IRP_MN_QUERY_PNP_DEVICE_STATE",
+        "IRP_MN_QUERY_BUS_INFORMATION",
+        "IRP_MN_DEVICE_USAGE_NOTIFICATION",
+        "IRP_MN_SURPRISE_REMOVAL",
+    };
+    Log(("vgdrvNtNt5PlusPnP: MinorFunction: %s\n",
+         pStack->MinorFunction < RT_ELEMENTS(s_apszFnctName) ? s_apszFnctName[pStack->MinorFunction] : "Unknown"));
+#endif
+
+    NTSTATUS rc = STATUS_SUCCESS;
+    uint8_t bMinorFunction = pStack->MinorFunction;
+    switch (bMinorFunction)
+    {
+        case IRP_MN_START_DEVICE:
+        {
+            Log(("vgdrvNtNt5PlusPnP: START_DEVICE\n"));
+
+            /* This must be handled first by the lower driver. */
+            rc = vgdrvNt5PlusPnPSendIrpSynchronously(pDevExt->pNextLowerDriver, pIrp, TRUE);
+            if (   NT_SUCCESS(rc)
+                && NT_SUCCESS(pIrp->IoStatus.Status))
+            {
+                Log(("vgdrvNtNt5PlusPnP: START_DEVICE: pStack->Parameters.StartDevice.AllocatedResources = %p\n",
+                     pStack->Parameters.StartDevice.AllocatedResources));
+                if (pStack->Parameters.StartDevice.AllocatedResources)
+                {
+                    rc = vgdrvNtSetupDevice(pDevExt, pDevObj, pIrp, NULL, NULL);
+                    if (NT_SUCCESS(rc))
+                        Log(("vgdrvNtNt5PlusPnP: START_DEVICE: success\n"));
+                    else
+                        Log(("vgdrvNtNt5PlusPnP: START_DEVICE: vgdrvNtSetupDevice failed: %#x\n", rc));
+                }
+                else
+                {
+                    Log(("vgdrvNtNt5PlusPnP: START_DEVICE: No resources, pDevExt = %p, nextLowerDriver = %p!\n",
+                         pDevExt, pDevExt ? pDevExt->pNextLowerDriver : NULL));
+                    rc = STATUS_UNSUCCESSFUL;
+                }
+            }
+            else
+                Log(("vgdrvNtNt5PlusPnP: START_DEVICE: vgdrvNt5PlusPnPSendIrpSynchronously failed: %#x + %#x\n",
+                     rc, pIrp->IoStatus.Status));
+
+            pIrp->IoStatus.Status = rc;
+            IoCompleteRequest(pIrp, IO_NO_INCREMENT);
+            return rc;
+        }
+
+
+        /*
+         * Sent before removing the device and/or driver.
+         */
+        case IRP_MN_QUERY_REMOVE_DEVICE:
+        {
+            Log(("vgdrvNtNt5PlusPnP: QUERY_REMOVE_DEVICE\n"));
+
+            RTCritSectRwEnterExcl(&pDevExt->SessionCreateCritSect);
+#ifdef VBOX_REBOOT_ON_UNINSTALL
+            Log(("vgdrvNtNt5PlusPnP: QUERY_REMOVE_DEVICE: Device cannot be removed without a reboot.\n"));
+            rc = STATUS_UNSUCCESSFUL;
+#endif
+            if (NT_SUCCESS(rc))
+                rc = vgdrvNtCheckIdle(pDevExt, "QUERY_REMOVE_DEVICE");
+            if (NT_SUCCESS(rc))
+            {
+                pDevExt->enmDevState = VGDRVNTDEVSTATE_PENDINGREMOVE;
+                RTCritSectRwLeaveExcl(&pDevExt->SessionCreateCritSect);
+
+                /* This IRP passed down to lower driver. */
+                pIrp->IoStatus.Status = STATUS_SUCCESS;
+
+                IoSkipCurrentIrpStackLocation(pIrp);
+                rc = IoCallDriver(pDevExt->pNextLowerDriver, pIrp);
+                Log(("vgdrvNtNt5PlusPnP: QUERY_REMOVE_DEVICE: Next lower driver replied rc = 0x%x\n", rc));
+
+                /* We must not do anything the IRP after doing IoSkip & CallDriver
+                   since the driver below us will complete (or already have completed) the IRP.
+                   I.e. just return the status we got from IoCallDriver */
+            }
+            else
+            {
+                RTCritSectRwLeaveExcl(&pDevExt->SessionCreateCritSect);
+                pIrp->IoStatus.Status = rc;
+                IoCompleteRequest(pIrp, IO_NO_INCREMENT);
+            }
+
+            Log(("vgdrvNtNt5PlusPnP: QUERY_REMOVE_DEVICE: Returning with rc = 0x%x\n", rc));
+            return rc;
+        }
+
+        /*
+         * Cancels a pending remove, IRP_MN_QUERY_REMOVE_DEVICE.
+         * We only have to revert the state.
+         */
+        case IRP_MN_CANCEL_REMOVE_DEVICE:
+        {
+            Log(("vgdrvNtNt5PlusPnP: CANCEL_REMOVE_DEVICE\n"));
+
+            /* This must be handled first by the lower driver. */
+            rc = vgdrvNt5PlusPnPSendIrpSynchronously(pDevExt->pNextLowerDriver, pIrp, TRUE);
+            if (   NT_SUCCESS(rc)
+                && pDevExt->enmDevState == VGDRVNTDEVSTATE_PENDINGREMOVE)
+            {
+                /* Return to the state prior to receiving the IRP_MN_QUERY_REMOVE_DEVICE request. */
+                pDevExt->enmDevState = pDevExt->enmPrevDevState;
+            }
+
+            /* Complete the IRP. */
+            pIrp->IoStatus.Status = rc;
+            IoCompleteRequest(pIrp, IO_NO_INCREMENT);
+            return rc;
+        }
+
+        /*
+         * We do nothing here actually, esp. since this request is not expected for VBoxGuest.
+         * The cleanup will be done in IRP_MN_REMOVE_DEVICE, which follows this call.
+         */
+        case IRP_MN_SURPRISE_REMOVAL:
+        {
+            Log(("vgdrvNtNt5PlusPnP: IRP_MN_SURPRISE_REMOVAL\n"));
+            pDevExt->enmDevState = VGDRVNTDEVSTATE_SURPRISEREMOVED;
+            LogRel(("VBoxGuest: unexpected device removal\n"));
+
+            /* Pass to the lower driver. */
+            pIrp->IoStatus.Status = STATUS_SUCCESS;
+
+            IoSkipCurrentIrpStackLocation(pIrp);
+            rc = IoCallDriver(pDevExt->pNextLowerDriver, pIrp);
+
+            /* Do not complete the IRP. */
+            return rc;
+        }
+
+        /*
+         * Device and/or driver removal.  Destroy everything.
+         */
+        case IRP_MN_REMOVE_DEVICE:
+        {
+            Log(("vgdrvNtNt5PlusPnP: REMOVE_DEVICE\n"));
+            pDevExt->enmDevState = VGDRVNTDEVSTATE_REMOVED;
+
+            /*
+             * Disconnect interrupts and delete all hardware resources.
+             * Note! This may already have been done if we're STOPPED already, if that's a possibility.
+             */
+            vgdrvNtDeleteDeviceResources(pDevExt);
+
+            /*
+             * We need to send the remove down the stack before we detach, but we don't need
+             * to wait for the completion of this operation (nor register a completion routine).
+             */
+            pIrp->IoStatus.Status = STATUS_SUCCESS;
+
+            IoSkipCurrentIrpStackLocation(pIrp);
+            rc = IoCallDriver(pDevExt->pNextLowerDriver, pIrp);
+            Log(("vgdrvNtNt5PlusPnP: REMOVE_DEVICE: Next lower driver replied rc = 0x%x\n", rc));
+
+            IoDetachDevice(pDevExt->pNextLowerDriver);
+            Log(("vgdrvNtNt5PlusPnP: REMOVE_DEVICE: Removing device ...\n"));
+
+            /*
+             * Delete the remainder of the device extension data, unlink it from the namespace and delete it.
+             */
+            vgdrvNtDeleteDeviceFundamentAndUnlink(pDevObj, pDevExt);
+
+            pDevObj = NULL; /* invalid */
+            pDevExt = NULL; /* invalid */
+
+            Log(("vgdrvNtNt5PlusPnP: REMOVE_DEVICE: Device removed!\n"));
+            return rc; /* Propagating rc from IoCallDriver. */
+        }
+
+
+        /*
+         * Sent before stopping the device/driver to check whether it is okay to do so.
+         */
+        case IRP_MN_QUERY_STOP_DEVICE:
+        {
+            Log(("vgdrvNtNt5PlusPnP: QUERY_STOP_DEVICE\n"));
+            RTCritSectRwEnterExcl(&pDevExt->SessionCreateCritSect);
+            rc = vgdrvNtCheckIdle(pDevExt, "QUERY_STOP_DEVICE");
+            if (NT_SUCCESS(rc))
+            {
+                pDevExt->enmPrevDevState = pDevExt->enmDevState;
+                pDevExt->enmDevState = VGDRVNTDEVSTATE_PENDINGSTOP;
+                RTCritSectRwLeaveExcl(&pDevExt->SessionCreateCritSect);
+
+                /* This IRP passed down to lower driver. */
+                pIrp->IoStatus.Status = STATUS_SUCCESS;
+
+                IoSkipCurrentIrpStackLocation(pIrp);
+
+                rc = IoCallDriver(pDevExt->pNextLowerDriver, pIrp);
+                Log(("vgdrvNtNt5PlusPnP: QUERY_STOP_DEVICE: Next lower driver replied rc = 0x%x\n", rc));
+
+                /* we must not do anything with the IRP after doing IoSkip & CallDriver since the
+                   driver below us will complete (or already have completed) the IRP.  I.e. just
+                   return the status we got from IoCallDriver. */
+            }
+            else
+            {
+                RTCritSectRwLeaveExcl(&pDevExt->SessionCreateCritSect);
+                pIrp->IoStatus.Status = rc;
+                IoCompleteRequest(pIrp, IO_NO_INCREMENT);
+            }
+
+            Log(("vgdrvNtNt5PlusPnP: QUERY_STOP_DEVICE: Returning with rc = 0x%x\n", rc));
+            return rc;
+        }
+
+        /*
+         * Cancels a pending remove, IRP_MN_QUERY_STOP_DEVICE.
+         * We only have to revert the state.
+         */
+        case IRP_MN_CANCEL_STOP_DEVICE:
+        {
+            Log(("vgdrvNtNt5PlusPnP: CANCEL_STOP_DEVICE\n"));
+
+            /* This must be handled first by the lower driver. */
+            rc = vgdrvNt5PlusPnPSendIrpSynchronously(pDevExt->pNextLowerDriver, pIrp, TRUE);
+            if (   NT_SUCCESS(rc)
+                && pDevExt->enmDevState == VGDRVNTDEVSTATE_PENDINGSTOP)
+            {
+                /* Return to the state prior to receiving the IRP_MN_QUERY_STOP_DEVICE request. */
+                pDevExt->enmDevState = pDevExt->enmPrevDevState;
+            }
+
+            /* Complete the IRP. */
+            pIrp->IoStatus.Status = rc;
+            IoCompleteRequest(pIrp, IO_NO_INCREMENT);
+            return rc;
+        }
+
+        /*
+         * Stop the device.
+         */
+        case IRP_MN_STOP_DEVICE:
+        {
+            Log(("vgdrvNtNt5PlusPnP: STOP_DEVICE\n"));
+            pDevExt->enmDevState = VGDRVNTDEVSTATE_STOPPED;
+
+            /*
+             * Release the hardware resources.
+             */
+            vgdrvNtDeleteDeviceResources(pDevExt);
+
+            /*
+             * Pass the request to the lower driver.
+             */
+            pIrp->IoStatus.Status = STATUS_SUCCESS;
+            IoSkipCurrentIrpStackLocation(pIrp);
+            rc = IoCallDriver(pDevExt->pNextLowerDriver, pIrp);
+            Log(("vgdrvNtNt5PlusPnP: STOP_DEVICE: Next lower driver replied rc = 0x%x\n", rc));
+            return rc;
+        }
+
+        default:
+        {
+            IoSkipCurrentIrpStackLocation(pIrp);
+            rc = IoCallDriver(pDevExt->pNextLowerDriver, pIrp);
+            Log(("vgdrvNtNt5PlusPnP: Unknown request %#x: Lower driver replied: %x\n", bMinorFunction, rc));
+            return rc;
+        }
+    }
+}
+
+
+/**
+ * Handle the power completion event.
+ *
+ * @returns NT status code.
+ * @param pDevObj   Targetted device object.
+ * @param pIrp      IO request packet.
+ * @param pContext  Context value passed to IoSetCompletionRoutine in VBoxGuestPower.
+ */
+static NTSTATUS vgdrvNtNt5PlusPowerComplete(IN PDEVICE_OBJECT pDevObj, IN PIRP pIrp, IN PVOID pContext)
+{
+#ifdef VBOX_STRICT
+    RT_NOREF1(pDevObj);
+    PVBOXGUESTDEVEXTWIN pDevExt = (PVBOXGUESTDEVEXTWIN)pContext;
+    PIO_STACK_LOCATION  pIrpSp  = IoGetCurrentIrpStackLocation(pIrp);
+
+    Assert(pDevExt);
+
+    if (pIrpSp)
+    {
+        Assert(pIrpSp->MajorFunction == IRP_MJ_POWER);
+        if (NT_SUCCESS(pIrp->IoStatus.Status))
+        {
+            switch (pIrpSp->MinorFunction)
+            {
+                case IRP_MN_SET_POWER:
+                    switch (pIrpSp->Parameters.Power.Type)
+                    {
+                        case DevicePowerState:
+                            switch (pIrpSp->Parameters.Power.State.DeviceState)
+                            {
+                                case PowerDeviceD0:
+                                    break;
+                                default:  /* Shut up MSC */
+                                    break;
+                            }
+                            break;
+                        default: /* Shut up MSC */
+                            break;
+                    }
+                    break;
+            }
+        }
+    }
+#else
+    RT_NOREF3(pDevObj, pIrp, pContext);
+#endif
+
+    return STATUS_SUCCESS;
+}
+
+
+/**
+ * Handle the Power requests.
+ *
+ * @returns   NT status code
+ * @param     pDevObj   device object
+ * @param     pIrp      IRP
+ */
+static NTSTATUS NTAPI vgdrvNtNt5PlusPower(PDEVICE_OBJECT pDevObj, PIRP pIrp)
+{
+    PIO_STACK_LOCATION  pStack   = IoGetCurrentIrpStackLocation(pIrp);
+    PVBOXGUESTDEVEXTWIN pDevExt  = (PVBOXGUESTDEVEXTWIN)pDevObj->DeviceExtension;
+    POWER_STATE_TYPE    enmPowerType   = pStack->Parameters.Power.Type;
+    POWER_STATE         PowerState     = pStack->Parameters.Power.State;
+    POWER_ACTION        enmPowerAction = pStack->Parameters.Power.ShutdownType;
+
+    Log(("vgdrvNtNt5PlusPower:\n"));
+
+    switch (pStack->MinorFunction)
+    {
+        case IRP_MN_SET_POWER:
+        {
+            Log(("vgdrvNtNt5PlusPower: IRP_MN_SET_POWER, type= %d\n", enmPowerType));
+            switch (enmPowerType)
+            {
+                case SystemPowerState:
+                {
+                    Log(("vgdrvNtNt5PlusPower: SystemPowerState, action = %d, state = %d/%d\n",
+                         enmPowerAction, PowerState.SystemState, PowerState.DeviceState));
+
+                    switch (enmPowerAction)
+                    {
+                        case PowerActionSleep:
+
+                            /* System now is in a working state. */
+                            if (PowerState.SystemState == PowerSystemWorking)
+                            {
+                                if (   pDevExt
+                                    && pDevExt->enmLastSystemPowerAction == PowerActionHibernate)
+                                {
+                                    Log(("vgdrvNtNt5PlusPower: Returning from hibernation!\n"));
+                                    int rc = VGDrvCommonReinitDevExtAfterHibernation(&pDevExt->Core,
+                                                                                     vgdrvNtVersionToOSType(g_enmVGDrvNtVer));
+                                    if (RT_FAILURE(rc))
+                                        Log(("vgdrvNtNt5PlusPower: Cannot re-init VMMDev chain, rc = %d!\n", rc));
+                                }
+                            }
+                            break;
+
+                        case PowerActionShutdownReset:
+                        {
+                            Log(("vgdrvNtNt5PlusPower: Power action reset!\n"));
+
+                            /* Tell the VMM that we no longer support mouse pointer integration. */
+                            VMMDevReqMouseStatus *pReq = NULL;
+                            int vrc = VbglR0GRAlloc((VMMDevRequestHeader **)&pReq, sizeof (VMMDevReqMouseStatus),
+                                                    VMMDevReq_SetMouseStatus);
+                            if (RT_SUCCESS(vrc))
+                            {
+                                pReq->mouseFeatures = 0;
+                                pReq->pointerXPos = 0;
+                                pReq->pointerYPos = 0;
+
+                                vrc = VbglR0GRPerform(&pReq->header);
+                                if (RT_FAILURE(vrc))
+                                {
+                                    Log(("vgdrvNtNt5PlusPower: error communicating new power status to VMMDev. vrc = %Rrc\n", vrc));
+                                }
+
+                                VbglR0GRFree(&pReq->header);
+                            }
+
+                            /* Don't do any cleanup here; there might be still coming in some IOCtls after we got this
+                             * power action and would assert/crash when we already cleaned up all the stuff! */
+                            break;
+                        }
+
+                        case PowerActionShutdown:
+                        case PowerActionShutdownOff:
+                        {
+                            Log(("vgdrvNtNt5PlusPower: Power action shutdown!\n"));
+                            if (PowerState.SystemState >= PowerSystemShutdown)
+                            {
+                                Log(("vgdrvNtNt5PlusPower: Telling the VMMDev to close the VM ...\n"));
+
+                                VMMDevPowerStateRequest *pReq = pDevExt->pPowerStateRequest;
+                                int vrc = VERR_NOT_IMPLEMENTED;
+                                if (pReq)
+                                {
+                                    pReq->header.requestType = VMMDevReq_SetPowerStatus;
+                                    pReq->powerState = VMMDevPowerState_PowerOff;
+
+                                    vrc = VbglR0GRPerform(&pReq->header);
+                                }
+                                if (RT_FAILURE(vrc))
+                                    Log(("vgdrvNtNt5PlusPower: Error communicating new power status to VMMDev. vrc = %Rrc\n", vrc));
+
+                                /* No need to do cleanup here; at this point we should've been
+                                 * turned off by VMMDev already! */
+                            }
+                            break;
+                        }
+
+                        case PowerActionHibernate:
+                            Log(("vgdrvNtNt5PlusPower: Power action hibernate!\n"));
+                            break;
+
+                        case PowerActionWarmEject:
+                            Log(("vgdrvNtNt5PlusPower: PowerActionWarmEject!\n"));
+                            break;
+
+                        default:
+                            Log(("vgdrvNtNt5PlusPower: %d\n", enmPowerAction));
+                            break;
+                    }
+
+                    /*
+                     * Save the current system power action for later use.
+                     * This becomes handy when we return from hibernation for example.
+                     */
+                    if (pDevExt)
+                        pDevExt->enmLastSystemPowerAction = enmPowerAction;
+
+                    break;
+                }
+                default:
+                    break;
+            }
+            break;
+        }
+        default:
+            break;
+    }
+
+    /*
+     * Whether we are completing or relaying this power IRP,
+     * we must call PoStartNextPowerIrp.
+     */
+    g_pfnPoStartNextPowerIrp(pIrp);
+
+    /*
+     * Send the IRP down the driver stack, using PoCallDriver
+     * (not IoCallDriver, as for non-power irps).
+     */
+    IoCopyCurrentIrpStackLocationToNext(pIrp);
+    IoSetCompletionRoutine(pIrp,
+                           vgdrvNtNt5PlusPowerComplete,
+                           (PVOID)pDevExt,
+                           TRUE,
+                           TRUE,
+                           TRUE);
+    return g_pfnPoCallDriver(pDevExt->pNextLowerDriver, pIrp);
+}
+
+
+/**
+ * IRP_MJ_SYSTEM_CONTROL handler.
+ *
+ * @returns NT status code
+ * @param   pDevObj     Device object.
+ * @param   pIrp        IRP.
+ */
+static NTSTATUS NTAPI vgdrvNtNt5PlusSystemControl(PDEVICE_OBJECT pDevObj, PIRP pIrp)
+{
+    PVBOXGUESTDEVEXTWIN pDevExt = (PVBOXGUESTDEVEXTWIN)pDevObj->DeviceExtension;
+
+    LogFlowFuncEnter();
+
+    /* Always pass it on to the next driver. */
+    IoSkipCurrentIrpStackLocation(pIrp);
+
+    return IoCallDriver(pDevExt->pNextLowerDriver, pIrp);
+}
+
+
+/**
+ * Unload the driver.
+ *
+ * @param   pDrvObj     Driver object.
+ */
+static void NTAPI vgdrvNtUnload(PDRIVER_OBJECT pDrvObj)
+{
+    LogFlowFuncEnter();
+
+#ifdef TARGET_NT4
+    /*
+     * We need to destroy the device object here on NT4 and earlier.
+     */
+    PDEVICE_OBJECT pDevObj = pDrvObj->DeviceObject;
+    if (pDevObj)
+    {
+        if (g_enmVGDrvNtVer <= VGDRVNTVER_WINNT4)
+        {
+            PVBOXGUESTDEVEXTWIN pDevExt = (PVBOXGUESTDEVEXTWIN)pDevObj->DeviceExtension;
+            AssertPtr(pDevExt);
+            AssertMsg(pDevExt->Core.uInitState == VBOXGUESTDEVEXT_INIT_STATE_RESOURCES,
+                      ("uInitState=%#x\n", pDevExt->Core.uInitState));
+
+            vgdrvNtDeleteDeviceResources(pDevExt);
+            vgdrvNtDeleteDeviceFundamentAndUnlink(pDevObj, pDevExt);
+        }
+    }
+#else  /* !TARGET_NT4 */
+    /*
+     * On a PnP driver this routine will be called after IRP_MN_REMOVE_DEVICE
+     * where we already did the cleanup, so don't do anything here (yet).
+     */
+    RT_NOREF1(pDrvObj);
+#endif /* !TARGET_NT4 */
+
+    VGDrvCommonDestroyLoggers();
+    RTR0Term();
+
+    /*
+     * Finally deregister the bugcheck callback.  Do it late to catch trouble in RTR0Term.
+     */
+    if (g_fBugCheckCallbackRegistered)
+    {
+        g_pfnKeDeregisterBugCheckCallback(&g_BugCheckCallbackRec);
+        g_fBugCheckCallbackRegistered = false;
+    }
+}
+
+
+/**
+ * For simplifying request completion into a simple return statement, extended
+ * version.
+ *
+ * @returns rcNt
+ * @param   rcNt                The status code.
+ * @param   uInfo               Extra info value.
+ * @param   pIrp                The IRP.
+ */
+DECLINLINE(NTSTATUS) vgdrvNtCompleteRequestEx(NTSTATUS rcNt, ULONG_PTR uInfo, PIRP pIrp)
+{
+    pIrp->IoStatus.Status       = rcNt;
+    pIrp->IoStatus.Information  = uInfo;
+    IoCompleteRequest(pIrp, IO_NO_INCREMENT);
+    return rcNt;
+}
+
+
+/**
+ * For simplifying request completion into a simple return statement.
+ *
+ * @returns rcNt
+ * @param   rcNt                The status code.
+ * @param   pIrp                The IRP.
+ */
+DECLINLINE(NTSTATUS) vgdrvNtCompleteRequest(NTSTATUS rcNt, PIRP pIrp)
+{
+    return vgdrvNtCompleteRequestEx(rcNt, 0 /*uInfo*/, pIrp);
+}
+
+
+/**
+ * Checks if NT authority rev 1 SID (SECURITY_NT_AUTHORITY).
+ *
+ * @returns true / false.
+ * @param   pSid                The SID to check.
+ */
+DECLINLINE(bool) vgdrvNtIsSidNtAuth(struct _SID const *pSid)
+{
+    return pSid != NULL
+        && pSid->Revision == 1
+        && pSid->IdentifierAuthority.Value[5] == 5
+        && pSid->IdentifierAuthority.Value[4] == 0
+        && pSid->IdentifierAuthority.Value[3] == 0
+        && pSid->IdentifierAuthority.Value[2] == 0
+        && pSid->IdentifierAuthority.Value[1] == 0
+        && pSid->IdentifierAuthority.Value[0] == 0;
+}
+
+
+/**
+ * Matches SID with local system user (S-1-5-18 / SECURITY_LOCAL_SYSTEM_RID).
+ */
+DECLINLINE(bool) vgdrvNtIsSidLocalSystemUser(SID const *pSid)
+{
+    return vgdrvNtIsSidNtAuth(pSid)
+        && pSid->SubAuthorityCount == 1
+        && pSid->SubAuthority[0]   == SECURITY_LOCAL_SYSTEM_RID;
+}
+
+
+/**
+ * Matches SID with NT system admin user (S-1-5-*-500 / DOMAIN_USER_RID_ADMIN).
+ */
+DECLINLINE(bool) vgdrvNtIsSidAdminUser(SID const *pSid)
+{
+    /** @todo restrict to SECURITY_NT_NON_UNIQUE? */
+    return vgdrvNtIsSidNtAuth(pSid)
+        && pSid->SubAuthorityCount >= 2
+        && pSid->SubAuthorityCount <= SID_MAX_SUB_AUTHORITIES
+        && pSid->SubAuthority[pSid->SubAuthorityCount - 1] == DOMAIN_USER_RID_ADMIN;
+}
+
+
+/**
+ * Matches SID with NT system guest user (S-1-5-*-501 / DOMAIN_USER_RID_GUEST).
+ */
+DECLINLINE(bool) vgdrvNtIsSidGuestUser(SID const *pSid)
+{
+    /** @todo restrict to SECURITY_NT_NON_UNIQUE? */
+    return vgdrvNtIsSidNtAuth(pSid)
+        && pSid->SubAuthorityCount >= 2
+        && pSid->SubAuthorityCount <= SID_MAX_SUB_AUTHORITIES
+        && pSid->SubAuthority[pSid->SubAuthorityCount - 1] == DOMAIN_USER_RID_GUEST;
+}
+
+
+/**
+ * Matches SID with NT system admins group (S-1-5-32-544, S-1-5-*-512).
+ */
+DECLINLINE(bool) vgdrvNtIsSidAdminsGroup(SID const *pSid)
+{
+    return vgdrvNtIsSidNtAuth(pSid)
+        && (   (   pSid->SubAuthorityCount == 2
+                && pSid->SubAuthority[0] == SECURITY_BUILTIN_DOMAIN_RID
+                && pSid->SubAuthority[1] == DOMAIN_ALIAS_RID_ADMINS)
+#if 0
+            /** @todo restrict to SECURITY_NT_NON_UNIQUE? */
+            || (   pSid->SubAuthorityCount >= 2
+                && pSid->SubAuthorityCount <= SID_MAX_SUB_AUTHORITIES
+                && pSid->SubAuthority[pSid->SubAuthorityCount - 1] == DOMAIN_GROUP_RID_ADMINS)
+#endif
+           );
+}
+
+
+/**
+ * Matches SID with NT system users group (S-1-5-32-545, S-1-5-32-547, S-1-5-*-512).
+ */
+DECLINLINE(bool) vgdrvNtIsSidUsersGroup(SID const *pSid)
+{
+    return vgdrvNtIsSidNtAuth(pSid)
+        && (   (   pSid->SubAuthorityCount == 2
+                && pSid->SubAuthority[0] == SECURITY_BUILTIN_DOMAIN_RID
+                && (   pSid->SubAuthority[1] == DOMAIN_ALIAS_RID_USERS
+                    || pSid->SubAuthority[1] == DOMAIN_ALIAS_RID_POWER_USERS) )
+#if 0
+           /** @todo restrict to SECURITY_NT_NON_UNIQUE? */
+           || (   pSid->SubAuthorityCount >= 2
+               && pSid->SubAuthorityCount <= SID_MAX_SUB_AUTHORITIES
+               && pSid->SubAuthority[pSid->SubAuthorityCount - 1] == DOMAIN_GROUP_RID_USERS)
+#endif
+           );
+}
+
+
+/**
+ * Matches SID with NT system guests group (S-1-5-32-546, S-1-5-*-512).
+ */
+DECLINLINE(bool) vgdrvNtIsSidGuestsGroup(SID const *pSid)
+{
+    return vgdrvNtIsSidNtAuth(pSid)
+        && (   (   pSid->SubAuthorityCount == 2
+                && pSid->SubAuthority[0] == SECURITY_BUILTIN_DOMAIN_RID
+                && pSid->SubAuthority[1] == DOMAIN_ALIAS_RID_GUESTS)
+#if 0
+           /** @todo restrict to SECURITY_NT_NON_UNIQUE? */
+           || (   pSid->SubAuthorityCount >= 2
+               && pSid->SubAuthorityCount <= SID_MAX_SUB_AUTHORITIES
+               && pSid->SubAuthority[pSid->SubAuthorityCount - 1] == DOMAIN_GROUP_RID_GUESTS)
+#endif
+           );
+}
+
+
+/**
+ * Checks if local authority rev 1 SID (SECURITY_LOCAL_SID_AUTHORITY).
+ *
+ * @returns true / false.
+ * @param   pSid                The SID to check.
+ */
+DECLINLINE(bool) vgdrvNtIsSidLocalAuth(struct _SID const *pSid)
+{
+    return pSid != NULL
+        && pSid->Revision == 1
+        && pSid->IdentifierAuthority.Value[5] == 2
+        && pSid->IdentifierAuthority.Value[4] == 0
+        && pSid->IdentifierAuthority.Value[3] == 0
+        && pSid->IdentifierAuthority.Value[2] == 0
+        && pSid->IdentifierAuthority.Value[1] == 0
+        && pSid->IdentifierAuthority.Value[0] == 0;
+}
+
+
+/**
+ * Matches SID with console logon group (S-1-2-1 / SECURITY_LOCAL_LOGON_RID).
+ */
+DECLINLINE(bool) vgdrvNtIsSidConsoleLogonGroup(SID const *pSid)
+{
+    return vgdrvNtIsSidLocalAuth(pSid)
+        && pSid->SubAuthorityCount == 1
+        && pSid->SubAuthority[0] == SECURITY_LOCAL_LOGON_RID;
+}
+
+
+/**
+ * Checks if mandatory label authority rev 1 SID (SECURITY_MANDATORY_LABEL_AUTHORITY).
+ *
+ * @returns true / false.
+ * @param   pSid                The SID to check.
+ */
+DECLINLINE(bool) vgdrvNtIsSidMandatoryLabelAuth(struct _SID const *pSid)
+{
+    return pSid != NULL
+        && pSid->Revision == 1
+        && pSid->IdentifierAuthority.Value[5] == 16
+        && pSid->IdentifierAuthority.Value[4] == 0
+        && pSid->IdentifierAuthority.Value[3] == 0
+        && pSid->IdentifierAuthority.Value[2] == 0
+        && pSid->IdentifierAuthority.Value[1] == 0
+        && pSid->IdentifierAuthority.Value[0] == 0;
+}
+
+
+#ifdef LOG_ENABLED
+/** Format an SID for logging.  */
+static const char *vgdrvNtFormatSid(char *pszBuf, size_t cbBuf, struct _SID const *pSid)
+{
+    uint64_t uAuth = RT_MAKE_U64_FROM_U8(pSid->IdentifierAuthority.Value[5], pSid->IdentifierAuthority.Value[4],
+                                         pSid->IdentifierAuthority.Value[3], pSid->IdentifierAuthority.Value[2],
+                                         pSid->IdentifierAuthority.Value[1], pSid->IdentifierAuthority.Value[0],
+                                         0,                                  0);
+    ssize_t offCur = RTStrPrintf2(pszBuf, cbBuf, "S-%u-%RU64", pSid->Revision, uAuth);
+    ULONG const *puSubAuth = &pSid->SubAuthority[0];
+    unsigned     cSubAuths = pSid->SubAuthorityCount;
+    while (cSubAuths > 0 && (size_t)offCur < cbBuf)
+    {
+        ssize_t cchThis = RTStrPrintf2(&pszBuf[offCur], cbBuf - (size_t)offCur, "-%u", *puSubAuth);
+        if (cchThis > 0)
+        {
+            offCur += cchThis;
+            puSubAuth++;
+            cSubAuths--;
+        }
+        else
+        {
+            Assert(cbBuf >= 5);
+            pszBuf[cbBuf - 4] = '.';
+            pszBuf[cbBuf - 3] = '.';
+            pszBuf[cbBuf - 2] = '.';
+            pszBuf[cbBuf - 1] = '\0';
+            break;
+        }
+    }
+    return pszBuf;
+}
+#endif
+
+
+/**
+ * Calculate requestor flags for the current process.
+ *
+ * ASSUMES vgdrvNtCreate is executed in the context of the process and thread
+ * doing the NtOpenFile call.
+ *
+ * @returns VMMDEV_REQUESTOR_XXX
+ */
+static uint32_t vgdrvNtCalcRequestorFlags(void)
+{
+    uint32_t fRequestor = VMMDEV_REQUESTOR_USERMODE
+                        | VMMDEV_REQUESTOR_USR_NOT_GIVEN
+                        | VMMDEV_REQUESTOR_CON_DONT_KNOW
+                        | VMMDEV_REQUESTOR_TRUST_NOT_GIVEN
+                        | VMMDEV_REQUESTOR_NO_USER_DEVICE;
+    HANDLE   hToken = NULL;
+    NTSTATUS rcNt = ZwOpenProcessToken(NtCurrentProcess(), TOKEN_QUERY, &hToken);
+    if (NT_SUCCESS(rcNt))
+    {
+        union
+        {
+            TOKEN_USER      CurUser;
+            TOKEN_GROUPS    CurGroups;
+            uint8_t         abPadding[256];
+        } Buf;
+#ifdef LOG_ENABLED
+        char szSid[200];
+#endif
+
+        /*
+         * Get the user SID and see if it's a standard one.
+         */
+        RT_ZERO(Buf.CurUser);
+        ULONG cbReturned = 0;
+        rcNt = ZwQueryInformationToken(hToken, TokenUser, &Buf.CurUser, sizeof(Buf), &cbReturned);
+        if (NT_SUCCESS(rcNt))
+        {
+            struct _SID const *pSid = (struct _SID const *)Buf.CurUser.User.Sid;
+            Log5(("vgdrvNtCalcRequestorFlags: TokenUser: %#010x %s\n",
+                  Buf.CurUser.User.Attributes, vgdrvNtFormatSid(szSid, sizeof(szSid), pSid)));
+
+            if (vgdrvNtIsSidLocalSystemUser(pSid))
+                fRequestor = (fRequestor & ~VMMDEV_REQUESTOR_USR_MASK) | VMMDEV_REQUESTOR_USR_SYSTEM;
+            else if (vgdrvNtIsSidAdminUser(pSid))
+                fRequestor = (fRequestor & ~VMMDEV_REQUESTOR_USR_MASK) | VMMDEV_REQUESTOR_USR_ROOT;
+            else if (vgdrvNtIsSidGuestUser(pSid))
+                fRequestor = (fRequestor & ~VMMDEV_REQUESTOR_USR_MASK) | VMMDEV_REQUESTOR_USR_GUEST;
+        }
+        else
+            LogRel(("vgdrvNtCalcRequestorFlags: TokenUser query failed: %#x\n", rcNt));
+
+        /*
+         * Get the groups.
+         */
+        TOKEN_GROUPS *pCurGroupsFree = NULL;
+        TOKEN_GROUPS *pCurGroups     = &Buf.CurGroups;
+        uint32_t      cbCurGroups    = sizeof(Buf);
+        cbReturned = 0;
+        RT_ZERO(Buf);
+        rcNt = ZwQueryInformationToken(hToken, TokenGroups, pCurGroups, cbCurGroups, &cbReturned);
+        if (rcNt == STATUS_BUFFER_TOO_SMALL)
+        {
+            uint32_t cTries = 8;
+            do
+            {
+                RTMemTmpFree(pCurGroupsFree);
+                if (cbCurGroups < cbReturned)
+                    cbCurGroups = RT_ALIGN_32(cbCurGroups + 32, 64);
+                else
+                    cbCurGroups += 64;
+                pCurGroupsFree = pCurGroups = (TOKEN_GROUPS *)RTMemTmpAllocZ(cbCurGroups);
+                if (pCurGroupsFree)
+                    rcNt = ZwQueryInformationToken(hToken, TokenGroups, pCurGroups, cbCurGroups, &cbReturned);
+                else
+                    rcNt = STATUS_NO_MEMORY;
+            } while (rcNt == STATUS_BUFFER_TOO_SMALL && cTries-- > 0);
+        }
+        if (NT_SUCCESS(rcNt))
+        {
+            bool fGuestsMember = false;
+            bool fUsersMember  = false;
+            if (g_enmVGDrvNtVer >= VGDRVNTVER_WIN7)
+                fRequestor = (fRequestor & ~VMMDEV_REQUESTOR_CON_MASK) | VMMDEV_REQUESTOR_CON_NO;
+
+            for (uint32_t iGrp = 0; iGrp < pCurGroups->GroupCount; iGrp++)
+            {
+                uint32_t const     fAttribs = pCurGroups->Groups[iGrp].Attributes;
+                struct _SID const *pSid     = (struct _SID const *)pCurGroups->Groups[iGrp].Sid;
+                Log5(("vgdrvNtCalcRequestorFlags: TokenGroups[%u]: %#10x %s\n",
+                      iGrp, fAttribs, vgdrvNtFormatSid(szSid, sizeof(szSid), pSid)));
+
+                if (   (fAttribs & SE_GROUP_INTEGRITY_ENABLED)
+                    && vgdrvNtIsSidMandatoryLabelAuth(pSid)
+                    && pSid->SubAuthorityCount == 1
+                    && (fRequestor & VMMDEV_REQUESTOR_TRUST_MASK) == VMMDEV_REQUESTOR_TRUST_NOT_GIVEN)
+                {
+                    fRequestor &= ~VMMDEV_REQUESTOR_TRUST_MASK;
+                    if (pSid->SubAuthority[0] < SECURITY_MANDATORY_LOW_RID)
+                        fRequestor |= VMMDEV_REQUESTOR_TRUST_UNTRUSTED;
+                    else if (pSid->SubAuthority[0] < SECURITY_MANDATORY_MEDIUM_RID)
+                        fRequestor |= VMMDEV_REQUESTOR_TRUST_LOW;
+                    else if (pSid->SubAuthority[0] < SECURITY_MANDATORY_MEDIUM_PLUS_RID)
+                        fRequestor |= VMMDEV_REQUESTOR_TRUST_MEDIUM;
+                    else if (pSid->SubAuthority[0] < SECURITY_MANDATORY_HIGH_RID)
+                        fRequestor |= VMMDEV_REQUESTOR_TRUST_MEDIUM_PLUS;
+                    else if (pSid->SubAuthority[0] < SECURITY_MANDATORY_SYSTEM_RID)
+                        fRequestor |= VMMDEV_REQUESTOR_TRUST_HIGH;
+                    else if (pSid->SubAuthority[0] < SECURITY_MANDATORY_PROTECTED_PROCESS_RID)
+                        fRequestor |= VMMDEV_REQUESTOR_TRUST_SYSTEM;
+                    else
+                        fRequestor |= VMMDEV_REQUESTOR_TRUST_PROTECTED;
+                    Log5(("vgdrvNtCalcRequestorFlags: mandatory label %u: => %#x\n", pSid->SubAuthority[0], fRequestor));
+                }
+                else if (      (fAttribs & (SE_GROUP_ENABLED | SE_GROUP_MANDATORY | SE_GROUP_USE_FOR_DENY_ONLY))
+                            ==             (SE_GROUP_ENABLED | SE_GROUP_MANDATORY)
+                         && vgdrvNtIsSidConsoleLogonGroup(pSid))
+                {
+                    fRequestor = (fRequestor & ~VMMDEV_REQUESTOR_CON_MASK) | VMMDEV_REQUESTOR_CON_YES;
+                    Log5(("vgdrvNtCalcRequestorFlags: console: => %#x\n", fRequestor));
+                }
+                else if (      (fAttribs & (SE_GROUP_ENABLED | SE_GROUP_MANDATORY | SE_GROUP_USE_FOR_DENY_ONLY))
+                            ==             (SE_GROUP_ENABLED | SE_GROUP_MANDATORY)
+                         && vgdrvNtIsSidNtAuth(pSid))
+                {
+                    if (vgdrvNtIsSidAdminsGroup(pSid))
+                    {
+                        fRequestor |= VMMDEV_REQUESTOR_GRP_WHEEL;
+                        Log5(("vgdrvNtCalcRequestorFlags: admins group: => %#x\n", fRequestor));
+                    }
+                    else if (vgdrvNtIsSidUsersGroup(pSid))
+                    {
+                        Log5(("vgdrvNtCalcRequestorFlags: users group\n"));
+                        fUsersMember = true;
+                    }
+                    else if (vgdrvNtIsSidGuestsGroup(pSid))
+                    {
+                        Log5(("vgdrvNtCalcRequestorFlags: guests group\n"));
+                        fGuestsMember = true;
+                    }
+                }
+            }
+            if ((fRequestor & VMMDEV_REQUESTOR_USR_MASK) == VMMDEV_REQUESTOR_USR_NOT_GIVEN)
+            {
+                if (fUsersMember)
+                    fRequestor = (fRequestor & ~VMMDEV_REQUESTOR_USR_MASK) | VMMDEV_REQUESTOR_USR_USER;
+                else if (fGuestsMember)
+                    fRequestor = (fRequestor & ~VMMDEV_REQUESTOR_USR_MASK) | VMMDEV_REQUESTOR_USR_GUEST;
+            }
+        }
+        else
+            LogRel(("vgdrvNtCalcRequestorFlags: TokenGroups query failed: %#x\n", rcNt));
+
+        RTMemTmpFree(pCurGroupsFree);
+        ZwClose(hToken);
+
+        /*
+         * Determine whether we should set VMMDEV_REQUESTOR_USER_DEVICE or not.
+         *
+         * The purpose here is to differentiate VBoxService accesses
+         * from VBoxTray and VBoxControl, as VBoxService should be allowed to
+         * do more than the latter two.  VBoxService normally runs under the
+         * system account which is easily detected, but for debugging and
+         * similar purposes we also allow an elevated admin to run it as well.
+         */
+        if (   (fRequestor & VMMDEV_REQUESTOR_TRUST_MASK) == VMMDEV_REQUESTOR_TRUST_UNTRUSTED /* general paranoia wrt system account */
+            || (fRequestor & VMMDEV_REQUESTOR_TRUST_MASK) == VMMDEV_REQUESTOR_TRUST_LOW       /* ditto */
+            || (fRequestor & VMMDEV_REQUESTOR_TRUST_MASK) == VMMDEV_REQUESTOR_TRUST_MEDIUM    /* ditto */
+            || !(   (fRequestor & VMMDEV_REQUESTOR_USR_MASK) == VMMDEV_REQUESTOR_USR_SYSTEM
+                 || (   (   (fRequestor & VMMDEV_REQUESTOR_GRP_WHEEL)
+                         || (fRequestor & VMMDEV_REQUESTOR_USR_MASK) == VMMDEV_REQUESTOR_USR_ROOT)
+                     && (   (fRequestor & VMMDEV_REQUESTOR_TRUST_MASK) >= VMMDEV_REQUESTOR_TRUST_HIGH
+                         || (fRequestor & VMMDEV_REQUESTOR_TRUST_MASK) == VMMDEV_REQUESTOR_TRUST_NOT_GIVEN)) ))
+            fRequestor |= VMMDEV_REQUESTOR_USER_DEVICE;
+    }
+    else
+    {
+        LogRel(("vgdrvNtCalcRequestorFlags: NtOpenProcessToken query failed: %#x\n", rcNt));
+        fRequestor |= VMMDEV_REQUESTOR_USER_DEVICE;
+    }
+
+    Log5(("vgdrvNtCalcRequestorFlags: returns %#x\n", fRequestor));
+    return fRequestor;
+}
+
+
+/**
+ * Create (i.e. Open) file entry point.
+ *
+ * @param   pDevObj     Device object.
+ * @param   pIrp        Request packet.
+ */
+static NTSTATUS NTAPI vgdrvNtCreate(PDEVICE_OBJECT pDevObj, PIRP pIrp)
+{
+    Log(("vgdrvNtCreate: RequestorMode=%d\n", pIrp->RequestorMode));
+    PIO_STACK_LOCATION  pStack   = IoGetCurrentIrpStackLocation(pIrp);
+    PFILE_OBJECT        pFileObj = pStack->FileObject;
+    PVBOXGUESTDEVEXTWIN pDevExt  = (PVBOXGUESTDEVEXTWIN)pDevObj->DeviceExtension;
+
+    Assert(pFileObj->FsContext == NULL);
+
+    /*
+     * We are not remotely similar to a directory...
+     */
+    NTSTATUS rcNt;
+    if (!(pStack->Parameters.Create.Options & FILE_DIRECTORY_FILE))
+    {
+        /*
+         * Check the device state.  We enter the critsect in shared mode to
+         * prevent race with PnP system requests checking whether we're idle.
+         */
+        RTCritSectRwEnterShared(&pDevExt->SessionCreateCritSect);
+        VGDRVNTDEVSTATE const enmDevState = pDevExt->enmDevState;
+        if (enmDevState == VGDRVNTDEVSTATE_OPERATIONAL)
+        {
+            /*
+             * Create a client session.
+             */
+            int                 rc;
+            PVBOXGUESTSESSION   pSession;
+            if (pIrp->RequestorMode == KernelMode)
+                rc = VGDrvCommonCreateKernelSession(&pDevExt->Core, &pSession);
+            else
+                rc = VGDrvCommonCreateUserSession(&pDevExt->Core, vgdrvNtCalcRequestorFlags(), &pSession);
+            RTCritSectRwLeaveShared(&pDevExt->SessionCreateCritSect);
+            if (RT_SUCCESS(rc))
+            {
+                pFileObj->FsContext = pSession;
+                Log(("vgdrvNtCreate: Successfully created %s session %p (fRequestor=%#x)\n",
+                     pIrp->RequestorMode == KernelMode ? "kernel" : "user", pSession, pSession->fRequestor));
+
+                return vgdrvNtCompleteRequestEx(STATUS_SUCCESS, FILE_OPENED, pIrp);
+            }
+
+            /* Note. the IoStatus is completely ignored on error. */
+            Log(("vgdrvNtCreate: Failed to create session: rc=%Rrc\n", rc));
+            if (rc == VERR_NO_MEMORY)
+                rcNt = STATUS_NO_MEMORY;
+            else
+                rcNt = STATUS_UNSUCCESSFUL;
+        }
+        else
+        {
+            RTCritSectRwLeaveShared(&pDevExt->SessionCreateCritSect);
+            LogFlow(("vgdrvNtCreate: Failed. Device is not in 'working' state: %d\n", enmDevState));
+            rcNt = STATUS_DEVICE_NOT_READY;
+        }
+    }
+    else
+    {
+        LogFlow(("vgdrvNtCreate: Failed. FILE_DIRECTORY_FILE set\n"));
+        rcNt = STATUS_NOT_A_DIRECTORY;
+    }
+    return vgdrvNtCompleteRequest(rcNt, pIrp);
+}
+
+
+/**
+ * Close file entry point.
+ *
+ * @param   pDevObj     Device object.
+ * @param   pIrp        Request packet.
+ */
+static NTSTATUS NTAPI vgdrvNtClose(PDEVICE_OBJECT pDevObj, PIRP pIrp)
+{
+    PVBOXGUESTDEVEXTWIN pDevExt  = (PVBOXGUESTDEVEXTWIN)pDevObj->DeviceExtension;
+    PIO_STACK_LOCATION  pStack   = IoGetCurrentIrpStackLocation(pIrp);
+    PFILE_OBJECT        pFileObj = pStack->FileObject;
+
+    LogFlowFunc(("pDevExt=0x%p, pFileObj=0x%p, FsContext=0x%p\n", pDevExt, pFileObj, pFileObj->FsContext));
+
+#ifdef VBOX_WITH_HGCM
+    /* Close both, R0 and R3 sessions. */
+    PVBOXGUESTSESSION pSession = (PVBOXGUESTSESSION)pFileObj->FsContext;
+    if (pSession)
+        VGDrvCommonCloseSession(&pDevExt->Core, pSession);
+#endif
+
+    pFileObj->FsContext = NULL;
+    pIrp->IoStatus.Information = 0;
+    pIrp->IoStatus.Status = STATUS_SUCCESS;
+    IoCompleteRequest(pIrp, IO_NO_INCREMENT);
+
+    return STATUS_SUCCESS;
+}
+
+
+/**
+ * Device I/O Control entry point.
+ *
+ * @param   pDevObj     Device object.
+ * @param   pIrp        Request packet.
+ */
+NTSTATUS NTAPI vgdrvNtDeviceControl(PDEVICE_OBJECT pDevObj, PIRP pIrp)
+{
+    PVBOXGUESTDEVEXTWIN pDevExt  = (PVBOXGUESTDEVEXTWIN)pDevObj->DeviceExtension;
+    PIO_STACK_LOCATION  pStack   = IoGetCurrentIrpStackLocation(pIrp);
+    PVBOXGUESTSESSION   pSession = pStack->FileObject ? (PVBOXGUESTSESSION)pStack->FileObject->FsContext : NULL;
+
+    if (!RT_VALID_PTR(pSession))
+        return vgdrvNtCompleteRequest(STATUS_TRUST_FAILURE, pIrp);
+
+#if 0 /* No fast I/O controls defined yet. */
+    /*
+     * Deal with the 2-3 high-speed IOCtl that takes their arguments from
+     * the session and iCmd, and does not return anything.
+     */
+    if (pSession->fUnrestricted)
+    {
+        ULONG ulCmd = pStack->Parameters.DeviceIoControl.IoControlCode;
+        if (   ulCmd == SUP_IOCTL_FAST_DO_RAW_RUN
+            || ulCmd == SUP_IOCTL_FAST_DO_HM_RUN
+            || ulCmd == SUP_IOCTL_FAST_DO_NOP)
+        {
+            int rc = supdrvIOCtlFast(ulCmd, (unsigned)(uintptr_t)pIrp->UserBuffer /* VMCPU id */, pDevExt, pSession);
+
+            /* Complete the I/O request. */
+            supdrvSessionRelease(pSession);
+            return vgdrvNtCompleteRequest(RT_SUCCESS(rc) ? STATUS_SUCCESS : STATUS_INVALID_PARAMETER, pIrp);
+        }
+    }
+#endif
+
+    return vgdrvNtDeviceControlSlow(&pDevExt->Core, pSession, pIrp, pStack);
+}
+
+
+/**
+ * Device I/O Control entry point.
+ *
+ * @param   pDevExt     The device extension.
+ * @param   pSession    The session.
+ * @param   pIrp        Request packet.
+ * @param   pStack      The request stack pointer.
+ */
+static NTSTATUS vgdrvNtDeviceControlSlow(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession,
+                                         PIRP pIrp, PIO_STACK_LOCATION pStack)
+{
+    NTSTATUS    rcNt;
+    uint32_t    cbOut = 0;
+    int         rc = 0;
+    Log2(("vgdrvNtDeviceControlSlow(%p,%p): ioctl=%#x pBuf=%p cbIn=%#x cbOut=%#x pSession=%p\n",
+          pDevExt, pIrp, pStack->Parameters.DeviceIoControl.IoControlCode,
+          pIrp->AssociatedIrp.SystemBuffer, pStack->Parameters.DeviceIoControl.InputBufferLength,
+          pStack->Parameters.DeviceIoControl.OutputBufferLength, pSession));
+
+#if 0 /*def RT_ARCH_AMD64*/
+    /* Don't allow 32-bit processes to do any I/O controls. */
+    if (!IoIs32bitProcess(pIrp))
+#endif
+    {
+        /* Verify that it's a buffered CTL. */
+        if ((pStack->Parameters.DeviceIoControl.IoControlCode & 0x3) == METHOD_BUFFERED)
+        {
+            /* Verify that the sizes in the request header are correct. */
+            PVBGLREQHDR pHdr = (PVBGLREQHDR)pIrp->AssociatedIrp.SystemBuffer;
+            if (   pStack->Parameters.DeviceIoControl.InputBufferLength  >= sizeof(*pHdr)
+                && pStack->Parameters.DeviceIoControl.InputBufferLength  == pHdr->cbIn
+                && pStack->Parameters.DeviceIoControl.OutputBufferLength == pHdr->cbOut)
+            {
+                /* Zero extra output bytes to make sure we don't leak anything. */
+                if (pHdr->cbIn < pHdr->cbOut)
+                    RtlZeroMemory((uint8_t *)pHdr + pHdr->cbIn, pHdr->cbOut - pHdr->cbIn);
+
+                /*
+                 * Do the job.
+                 */
+                rc = VGDrvCommonIoCtl(pStack->Parameters.DeviceIoControl.IoControlCode, pDevExt, pSession, pHdr,
+                                      RT_MAX(pHdr->cbIn, pHdr->cbOut));
+                if (RT_SUCCESS(rc))
+                {
+                    rcNt  = STATUS_SUCCESS;
+                    cbOut = pHdr->cbOut;
+                    if (cbOut > pStack->Parameters.DeviceIoControl.OutputBufferLength)
+                    {
+                        cbOut = pStack->Parameters.DeviceIoControl.OutputBufferLength;
+                        LogRel(("vgdrvNtDeviceControlSlow: too much output! %#x > %#x; uCmd=%#x!\n",
+                                pHdr->cbOut, cbOut, pStack->Parameters.DeviceIoControl.IoControlCode));
+                    }
+
+                    /* If IDC successful disconnect request, we must set the context pointer to NULL. */
+                    if (   pStack->Parameters.DeviceIoControl.IoControlCode == VBGL_IOCTL_IDC_DISCONNECT
+                        && RT_SUCCESS(pHdr->rc))
+                        pStack->FileObject->FsContext = NULL;
+                }
+                else if (rc == VERR_NOT_SUPPORTED)
+                    rcNt = STATUS_NOT_SUPPORTED;
+                else
+                    rcNt = STATUS_INVALID_PARAMETER;
+                Log2(("vgdrvNtDeviceControlSlow: returns %#x cbOut=%d rc=%#x\n", rcNt, cbOut, rc));
+            }
+            else
+            {
+                Log(("vgdrvNtDeviceControlSlow: Mismatching sizes (%#x) - Hdr=%#lx/%#lx Irp=%#lx/%#lx!\n",
+                     pStack->Parameters.DeviceIoControl.IoControlCode,
+                     pStack->Parameters.DeviceIoControl.InputBufferLength >= sizeof(*pHdr) ? pHdr->cbIn  : 0,
+                     pStack->Parameters.DeviceIoControl.InputBufferLength >= sizeof(*pHdr) ? pHdr->cbOut : 0,
+                     pStack->Parameters.DeviceIoControl.InputBufferLength,
+                     pStack->Parameters.DeviceIoControl.OutputBufferLength));
+                rcNt = STATUS_INVALID_PARAMETER;
+            }
+        }
+        else
+        {
+            Log(("vgdrvNtDeviceControlSlow: not buffered request (%#x) - not supported\n",
+                 pStack->Parameters.DeviceIoControl.IoControlCode));
+            rcNt = STATUS_NOT_SUPPORTED;
+        }
+    }
+#if 0 /*def RT_ARCH_AMD64*/
+    else
+    {
+        Log(("VBoxDrvNtDeviceControlSlow: WOW64 req - not supported\n"));
+        rcNt = STATUS_NOT_SUPPORTED;
+    }
+#endif
+
+    return vgdrvNtCompleteRequestEx(rcNt, cbOut, pIrp);
+}
+
+
+/**
+ * Internal Device I/O Control entry point (for IDC).
+ *
+ * @param   pDevObj     Device object.
+ * @param   pIrp        Request packet.
+ */
+static NTSTATUS NTAPI vgdrvNtInternalIOCtl(PDEVICE_OBJECT pDevObj, PIRP pIrp)
+{
+    /* Currently no special code here. */
+    return vgdrvNtDeviceControl(pDevObj, pIrp);
+}
+
+
+/**
+ * IRP_MJ_SHUTDOWN handler.
+ *
+ * @returns NT status code
+ * @param pDevObj    Device object.
+ * @param pIrp       IRP.
+ */
+static NTSTATUS NTAPI vgdrvNtShutdown(PDEVICE_OBJECT pDevObj, PIRP pIrp)
+{
+    PVBOXGUESTDEVEXTWIN pDevExt = (PVBOXGUESTDEVEXTWIN)pDevObj->DeviceExtension;
+    LogFlowFuncEnter();
+
+    VMMDevPowerStateRequest *pReq = pDevExt->pPowerStateRequest;
+    if (pReq)
+    {
+        pReq->header.requestType = VMMDevReq_SetPowerStatus;
+        pReq->powerState = VMMDevPowerState_PowerOff;
+
+        int rc = VbglR0GRPerform(&pReq->header);
+        if (RT_FAILURE(rc))
+            LogFunc(("Error performing request to VMMDev, rc=%Rrc\n", rc));
+    }
+
+    /* just in case, since we shouldn't normally get here. */
+    pIrp->IoStatus.Information = 0;
+    pIrp->IoStatus.Status = STATUS_SUCCESS;
+    IoCompleteRequest(pIrp, IO_NO_INCREMENT);
+    return STATUS_SUCCESS;
+}
+
+
+/**
+ * Stub function for functions we don't implemented.
+ *
+ * @returns STATUS_NOT_SUPPORTED
+ * @param   pDevObj     Device object.
+ * @param   pIrp        IRP.
+ */
+static NTSTATUS vgdrvNtNotSupportedStub(PDEVICE_OBJECT pDevObj, PIRP pIrp)
+{
+    RT_NOREF1(pDevObj);
+    LogFlowFuncEnter();
+
+    pIrp->IoStatus.Information = 0;
+    pIrp->IoStatus.Status = STATUS_NOT_SUPPORTED;
+    IoCompleteRequest(pIrp, IO_NO_INCREMENT);
+
+    return STATUS_NOT_SUPPORTED;
+}
+
+
+/**
+ * Bug check callback (KBUGCHECK_CALLBACK_ROUTINE).
+ *
+ * This adds a log entry on the host, in case Hyper-V isn't active or the guest
+ * is too old for reporting it itself via the crash MSRs.
+ *
+ * @param   pvBuffer            Not used.
+ * @param   cbBuffer            Not used.
+ */
+static VOID NTAPI vgdrvNtBugCheckCallback(PVOID pvBuffer, ULONG cbBuffer)
+{
+    if (g_pauKiBugCheckData)
+    {
+        RTLogBackdoorPrintf("VBoxGuest: BugCheck! P0=%#zx P1=%#zx P2=%#zx P3=%#zx P4=%#zx\n", g_pauKiBugCheckData[0],
+                            g_pauKiBugCheckData[1], g_pauKiBugCheckData[2], g_pauKiBugCheckData[3], g_pauKiBugCheckData[4]);
+
+        VMMDevReqNtBugCheck *pReq = NULL;
+        int rc = VbglR0GRAlloc((VMMDevRequestHeader **)&pReq, sizeof(*pReq), VMMDevReq_NtBugCheck);
+        if (RT_SUCCESS(rc))
+        {
+            pReq->uBugCheck       = g_pauKiBugCheckData[0];
+            pReq->auParameters[0] = g_pauKiBugCheckData[1];
+            pReq->auParameters[1] = g_pauKiBugCheckData[2];
+            pReq->auParameters[2] = g_pauKiBugCheckData[3];
+            pReq->auParameters[3] = g_pauKiBugCheckData[4];
+            VbglR0GRPerform(&pReq->header);
+            VbglR0GRFree(&pReq->header);
+        }
+    }
+    else
+    {
+        RTLogBackdoorPrintf("VBoxGuest: BugCheck!\n");
+
+        VMMDevRequestHeader *pReqHdr = NULL;
+        int rc = VbglR0GRAlloc(&pReqHdr, sizeof(*pReqHdr), VMMDevReq_NtBugCheck);
+        if (RT_SUCCESS(rc))
+        {
+            VbglR0GRPerform(pReqHdr);
+            VbglR0GRFree(pReqHdr);
+        }
+    }
+
+    RT_NOREF(pvBuffer, cbBuffer);
+}
+
+
+/**
+ * Sets the mouse notification callback.
+ *
+ * @returns VBox status code.
+ * @param   pDevExt   Pointer to the device extension.
+ * @param   pNotify   Pointer to the mouse notify struct.
+ */
+int VGDrvNativeSetMouseNotifyCallback(PVBOXGUESTDEVEXT pDevExt, PVBGLIOCSETMOUSENOTIFYCALLBACK pNotify)
+{
+    PVBOXGUESTDEVEXTWIN pDevExtWin = (PVBOXGUESTDEVEXTWIN)pDevExt;
+    /* we need a lock here to avoid concurrency with the set event functionality */
+    KIRQL OldIrql;
+    KeAcquireSpinLock(&pDevExtWin->MouseEventAccessSpinLock, &OldIrql);
+    pDevExtWin->Core.pfnMouseNotifyCallback   = pNotify->u.In.pfnNotify;
+    pDevExtWin->Core.pvMouseNotifyCallbackArg = pNotify->u.In.pvUser;
+    KeReleaseSpinLock(&pDevExtWin->MouseEventAccessSpinLock, OldIrql);
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * DPC handler.
+ *
+ * @param   pDPC        DPC descriptor.
+ * @param   pDevObj     Device object.
+ * @param   pIrp        Interrupt request packet.
+ * @param   pContext    Context specific pointer.
+ */
+static void NTAPI vgdrvNtDpcHandler(PKDPC pDPC, PDEVICE_OBJECT pDevObj, PIRP pIrp, PVOID pContext)
+{
+    RT_NOREF3(pDPC, pIrp, pContext);
+    PVBOXGUESTDEVEXTWIN pDevExt = (PVBOXGUESTDEVEXTWIN)pDevObj->DeviceExtension;
+    Log3Func(("pDevExt=0x%p\n", pDevExt));
+
+    /* Test & reset the counter. */
+    if (ASMAtomicXchgU32(&pDevExt->Core.u32MousePosChangedSeq, 0))
+    {
+        /* we need a lock here to avoid concurrency with the set event ioctl handler thread,
+         * i.e. to prevent the event from destroyed while we're using it */
+        Assert(KeGetCurrentIrql() == DISPATCH_LEVEL);
+        KeAcquireSpinLockAtDpcLevel(&pDevExt->MouseEventAccessSpinLock);
+
+        if (pDevExt->Core.pfnMouseNotifyCallback)
+            pDevExt->Core.pfnMouseNotifyCallback(pDevExt->Core.pvMouseNotifyCallbackArg);
+
+        KeReleaseSpinLockFromDpcLevel(&pDevExt->MouseEventAccessSpinLock);
+    }
+
+    /* Process the wake-up list we were asked by the scheduling a DPC
+     * in vgdrvNtIsrHandler(). */
+    VGDrvCommonWaitDoWakeUps(&pDevExt->Core);
+}
+
+
+/**
+ * ISR handler.
+ *
+ * @return  BOOLEAN         Indicates whether the IRQ came from us (TRUE) or not (FALSE).
+ * @param   pInterrupt      Interrupt that was triggered.
+ * @param   pServiceContext Context specific pointer.
+ */
+static BOOLEAN NTAPI vgdrvNtIsrHandler(PKINTERRUPT pInterrupt, PVOID pServiceContext)
+{
+    RT_NOREF1(pInterrupt);
+    PVBOXGUESTDEVEXTWIN pDevExt = (PVBOXGUESTDEVEXTWIN)pServiceContext;
+    if (pDevExt == NULL)
+        return FALSE;
+
+    /*Log3Func(("pDevExt=0x%p, pVMMDevMemory=0x%p\n", pDevExt, pDevExt ? pDevExt->pVMMDevMemory : NULL));*/
+
+    /* Enter the common ISR routine and do the actual work. */
+    BOOLEAN fIRQTaken = VGDrvCommonISR(&pDevExt->Core);
+
+    /* If we need to wake up some events we do that in a DPC to make
+     * sure we're called at the right IRQL. */
+    if (fIRQTaken)
+    {
+        Log3Func(("IRQ was taken! pInterrupt=0x%p, pDevExt=0x%p\n", pInterrupt, pDevExt));
+        if (ASMAtomicUoReadU32(   &pDevExt->Core.u32MousePosChangedSeq)
+                               || !RTListIsEmpty(&pDevExt->Core.WakeUpList))
+        {
+            Log3Func(("Requesting DPC...\n"));
+            IoRequestDpc(pDevExt->pDeviceObject, NULL /*pIrp*/, NULL /*pvContext*/);
+        }
+    }
+    return fIRQTaken;
+}
+
+
+void VGDrvNativeISRMousePollEvent(PVBOXGUESTDEVEXT pDevExt)
+{
+    NOREF(pDevExt);
+    /* nothing to do here - i.e. since we can not KeSetEvent from ISR level,
+     * we rely on the pDevExt->u32MousePosChangedSeq to be set to a non-zero value on a mouse event
+     * and queue the DPC in our ISR routine in that case doing KeSetEvent from the DPC routine */
+}
+
+
+/**
+ * Hook for handling OS specfic options from the host.
+ *
+ * @returns true if handled, false if not.
+ * @param   pDevExt         The device extension.
+ * @param   pszName         The option name.
+ * @param   pszValue        The option value.
+ */
+bool VGDrvNativeProcessOption(PVBOXGUESTDEVEXT pDevExt, const char *pszName, const char *pszValue)
+{
+    RT_NOREF(pDevExt); RT_NOREF(pszName); RT_NOREF(pszValue);
+    return false;
+}
+
+
+/**
+ * Implements RTL_QUERY_REGISTRY_ROUTINE for enumerating our registry key.
+ */
+static NTSTATUS NTAPI vgdrvNtRegistryEnumCallback(PWSTR pwszValueName, ULONG uValueType,
+                                                  PVOID pvValue, ULONG cbValue, PVOID pvUser, PVOID pvEntryCtx)
+{
+    Log4(("vgdrvNtRegistryEnumCallback: pwszValueName=%ls uValueType=%#x Value=%.*Rhxs\n", pwszValueName, uValueType, cbValue, pvValue));
+
+    /*
+     * Filter out general service config values.
+     */
+    if (   RTUtf16ICmpAscii(pwszValueName, "Type") == 0
+        || RTUtf16ICmpAscii(pwszValueName, "Start") == 0
+        || RTUtf16ICmpAscii(pwszValueName, "ErrorControl") == 0
+        || RTUtf16ICmpAscii(pwszValueName, "Tag") == 0
+        || RTUtf16ICmpAscii(pwszValueName, "ImagePath") == 0
+        || RTUtf16ICmpAscii(pwszValueName, "DisplayName") == 0
+        || RTUtf16ICmpAscii(pwszValueName, "Group") == 0
+        || RTUtf16ICmpAscii(pwszValueName, "DependOnGroup") == 0
+        || RTUtf16ICmpAscii(pwszValueName, "DependOnService") == 0
+       )
+    {
+        return STATUS_SUCCESS;
+    }
+
+    /*
+     * Convert the value name.
+     */
+    size_t cch = RTUtf16CalcUtf8Len(pwszValueName);
+    if (cch < 64 && cch > 0)
+    {
+        char szValueName[72];
+        char *pszTmp = szValueName;
+        int rc = RTUtf16ToUtf8Ex(pwszValueName, RTSTR_MAX, &pszTmp, sizeof(szValueName), NULL);
+        if (RT_SUCCESS(rc))
+        {
+            /*
+             * Convert the value.
+             */
+            char  szValue[72];
+            char *pszFree = NULL;
+            char *pszValue = NULL;
+            szValue[0] = '\0';
+            switch (uValueType)
+            {
+                case REG_SZ:
+                case REG_EXPAND_SZ:
+                    rc = RTUtf16CalcUtf8LenEx((PCRTUTF16)pvValue, cbValue / sizeof(RTUTF16), &cch);
+                    if (RT_SUCCESS(rc) && cch < _1K)
+                    {
+                        if (cch < sizeof(szValue))
+                        {
+                            pszValue = szValue;
+                            rc = RTUtf16ToUtf8Ex((PCRTUTF16)pvValue, cbValue / sizeof(RTUTF16), &pszValue, sizeof(szValue), NULL);
+                        }
+                        else
+                        {
+                            rc = RTUtf16ToUtf8Ex((PCRTUTF16)pvValue, cbValue / sizeof(RTUTF16), &pszValue, sizeof(szValue), NULL);
+                            if (RT_SUCCESS(rc))
+                                pszFree = pszValue;
+                        }
+                        if (RT_FAILURE(rc))
+                        {
+                            LogRel(("VBoxGuest: Failed to convert registry value '%ls' string data to UTF-8: %Rrc\n",
+                                    pwszValueName, rc));
+                            pszValue = NULL;
+                        }
+                    }
+                    else if (RT_SUCCESS(rc))
+                        LogRel(("VBoxGuest: Registry value '%ls' has a too long value: %#x (uvalueType=%#x)\n",
+                                pwszValueName, cbValue, uValueType));
+                    else
+                        LogRel(("VBoxGuest: Registry value '%ls' has an invalid string value (cbValue=%#x, uvalueType=%#x)\n",
+                                pwszValueName, cbValue, uValueType));
+                    break;
+
+                case REG_DWORD:
+                    if (cbValue == sizeof(uint32_t))
+                    {
+                        RTStrFormatU32(szValue, sizeof(szValue), *(uint32_t const *)pvValue, 10, 0, 0, 0);
+                        pszValue = szValue;
+                    }
+                    else
+                        LogRel(("VBoxGuest: Registry value '%ls' has wrong length for REG_DWORD: %#x\n", pwszValueName, cbValue));
+                    break;
+
+                case REG_QWORD:
+                    if (cbValue == sizeof(uint64_t))
+                    {
+                        RTStrFormatU32(szValue, sizeof(szValue), *(uint32_t const *)pvValue, 10, 0, 0, 0);
+                        pszValue = szValue;
+                    }
+                    else
+                        LogRel(("VBoxGuest: Registry value '%ls' has wrong length for REG_DWORD: %#x\n", pwszValueName, cbValue));
+                    break;
+
+                default:
+                    LogRel(("VBoxGuest: Ignoring registry value '%ls': Unsupported type %#x\n", pwszValueName, uValueType));
+                    break;
+            }
+            if (pszValue)
+            {
+                /*
+                 * Process it.
+                 */
+                PVBOXGUESTDEVEXT pDevExt = (PVBOXGUESTDEVEXT)pvUser;
+                VGDrvCommonProcessOption(pDevExt, szValueName, pszValue);
+                if (pszFree)
+                    RTStrFree(pszFree);
+            }
+        }
+    }
+    else if (cch > 0)
+        LogRel(("VBoxGuest: Ignoring registery value '%ls': name too long\n", pwszValueName));
+    else
+        LogRel(("VBoxGuest: Ignoring registery value with bad name\n", pwszValueName));
+    NOREF(pvEntryCtx);
+    return STATUS_SUCCESS;
+}
+
+
+/**
+ * Reads configuration from the registry and guest properties.
+ *
+ * We ignore failures and instead preserve existing configuration values.
+ *
+ * Thie routine will block.
+ *
+ * @param   pDevExt             The device extension.
+ */
+static void vgdrvNtReadConfiguration(PVBOXGUESTDEVEXTWIN pDevExt)
+{
+    /*
+     * First the registry.
+     *
+     * Note! RTL_QUERY_REGISTRY_NOEXPAND is sensible (no environment) and also necessary to
+     *       avoid crash on NT 3.1 because RtlExpandEnvironmentStrings_U thinks its in ring-3
+     *       and tries to get the default heap from the PEB via the TEB.  No TEB in ring-0.
+     */
+    RTL_QUERY_REGISTRY_TABLE aQuery[2];
+    RT_ZERO(aQuery);
+    aQuery[0].QueryRoutine = vgdrvNtRegistryEnumCallback;
+    aQuery[0].Flags        = RTL_QUERY_REGISTRY_NOEXPAND;
+    aQuery[0].Name         = NULL;
+    aQuery[0].EntryContext = NULL;
+    aQuery[0].DefaultType  = REG_NONE;
+    NTSTATUS rcNt = RtlQueryRegistryValues(RTL_REGISTRY_SERVICES, L"VBoxGuest", &aQuery[0], pDevExt, NULL /*pwszzEnv*/);
+    if (!NT_SUCCESS(rcNt))
+        LogRel(("VBoxGuest: RtlQueryRegistryValues failed: %#x\n", rcNt));
+
+    /*
+     * Read configuration from the host.
+     */
+    VGDrvCommonProcessOptionsFromHost(&pDevExt->Core);
+}
+
+#ifdef VBOX_STRICT
+
+/**
+ * A quick implementation of AtomicTestAndClear for uint32_t and multiple bits.
+ */
+static uint32_t vgdrvNtAtomicBitsTestAndClear(void *pu32Bits, uint32_t u32Mask)
+{
+    AssertPtrReturn(pu32Bits, 0);
+    LogFlowFunc(("*pu32Bits=%#x, u32Mask=%#x\n", *(uint32_t *)pu32Bits, u32Mask));
+    uint32_t u32Result = 0;
+    uint32_t u32WorkingMask = u32Mask;
+    int iBitOffset = ASMBitFirstSetU32 (u32WorkingMask);
+
+    while (iBitOffset > 0)
+    {
+        bool fSet = ASMAtomicBitTestAndClear(pu32Bits, iBitOffset - 1);
+        if (fSet)
+            u32Result |= 1 << (iBitOffset - 1);
+        u32WorkingMask &= ~(1 << (iBitOffset - 1));
+        iBitOffset = ASMBitFirstSetU32 (u32WorkingMask);
+    }
+    LogFlowFunc(("Returning %#x\n", u32Result));
+    return u32Result;
+}
+
+
+static void vgdrvNtTestAtomicTestAndClearBitsU32(uint32_t u32Mask, uint32_t u32Bits, uint32_t u32Exp)
+{
+    ULONG u32Bits2 = u32Bits;
+    uint32_t u32Result = vgdrvNtAtomicBitsTestAndClear(&u32Bits2, u32Mask);
+    if (   u32Result != u32Exp
+        || (u32Bits2 & u32Mask)
+        || (u32Bits2 & u32Result)
+        || ((u32Bits2 | u32Result) != u32Bits)
+       )
+        AssertLogRelMsgFailed(("TEST FAILED: u32Mask=%#x, u32Bits (before)=%#x, u32Bits (after)=%#x, u32Result=%#x, u32Exp=%#x\n",
+                               u32Mask, u32Bits, u32Bits2, u32Result));
+}
+
+
+static void vgdrvNtDoTests(void)
+{
+    vgdrvNtTestAtomicTestAndClearBitsU32(0x00, 0x23, 0);
+    vgdrvNtTestAtomicTestAndClearBitsU32(0x11, 0, 0);
+    vgdrvNtTestAtomicTestAndClearBitsU32(0x11, 0x22, 0);
+    vgdrvNtTestAtomicTestAndClearBitsU32(0x11, 0x23, 0x1);
+    vgdrvNtTestAtomicTestAndClearBitsU32(0x11, 0x32, 0x10);
+    vgdrvNtTestAtomicTestAndClearBitsU32(0x22, 0x23, 0x22);
+}
+
+#endif /* VBOX_STRICT */
+
+#ifdef VBOX_WITH_DPC_LATENCY_CHECKER
+
+/*
+ * DPC latency checker.
+ */
+
+/**
+ * One DPC latency sample.
+ */
+typedef struct DPCSAMPLE
+{
+    LARGE_INTEGER   PerfDelta;
+    LARGE_INTEGER   PerfCounter;
+    LARGE_INTEGER   PerfFrequency;
+    uint64_t        u64TSC;
+} DPCSAMPLE;
+AssertCompileSize(DPCSAMPLE, 4*8);
+
+/**
+ * The DPC latency measurement workset.
+ */
+typedef struct DPCDATA
+{
+    KDPC            Dpc;
+    KTIMER          Timer;
+    KSPIN_LOCK      SpinLock;
+
+    ULONG           ulTimerRes;
+
+    bool volatile   fFinished;
+
+    /** The timer interval (relative). */
+    LARGE_INTEGER   DueTime;
+
+    LARGE_INTEGER   PerfCounterPrev;
+
+    /** Align the sample array on a 64 byte boundrary just for the off chance
+     * that we'll get cache line aligned memory backing this structure. */
+    uint32_t        auPadding[ARCH_BITS == 32 ? 5 : 7];
+
+    int             cSamples;
+    DPCSAMPLE       aSamples[8192];
+} DPCDATA;
+
+AssertCompileMemberAlignment(DPCDATA, aSamples, 64);
+
+/**
+ * DPC callback routine for the DPC latency measurement code.
+ *
+ * @param   pDpc                The DPC, not used.
+ * @param   pvDeferredContext   Pointer to the DPCDATA.
+ * @param   SystemArgument1     System use, ignored.
+ * @param   SystemArgument2     System use, ignored.
+ */
+static VOID vgdrvNtDpcLatencyCallback(PKDPC pDpc, PVOID pvDeferredContext, PVOID SystemArgument1, PVOID SystemArgument2)
+{
+    DPCDATA *pData = (DPCDATA *)pvDeferredContext;
+    RT_NOREF(pDpc, SystemArgument1, SystemArgument2);
+
+    KeAcquireSpinLockAtDpcLevel(&pData->SpinLock);
+
+    if (pData->cSamples >= RT_ELEMENTS(pData->aSamples))
+        pData->fFinished = true;
+    else
+    {
+        DPCSAMPLE *pSample = &pData->aSamples[pData->cSamples++];
+
+        pSample->u64TSC = ASMReadTSC();
+        pSample->PerfCounter = KeQueryPerformanceCounter(&pSample->PerfFrequency);
+        pSample->PerfDelta.QuadPart = pSample->PerfCounter.QuadPart - pData->PerfCounterPrev.QuadPart;
+
+        pData->PerfCounterPrev.QuadPart = pSample->PerfCounter.QuadPart;
+
+        KeSetTimer(&pData->Timer, pData->DueTime, &pData->Dpc);
+    }
+
+    KeReleaseSpinLockFromDpcLevel(&pData->SpinLock);
+}
+
+
+/**
+ * Handles the DPC latency checker request.
+ *
+ * @returns VBox status code.
+ */
+int VGDrvNtIOCtl_DpcLatencyChecker(void)
+{
+    /*
+     * Allocate a block of non paged memory for samples and related data.
+     */
+    DPCDATA *pData = (DPCDATA *)RTMemAlloc(sizeof(DPCDATA));
+    if (!pData)
+    {
+        RTLogBackdoorPrintf("VBoxGuest: DPC: DPCDATA allocation failed.\n");
+        return VERR_NO_MEMORY;
+    }
+
+    /*
+     * Initialize the data.
+     */
+    KeInitializeDpc(&pData->Dpc, vgdrvNtDpcLatencyCallback, pData);
+    KeInitializeTimer(&pData->Timer);
+    KeInitializeSpinLock(&pData->SpinLock);
+
+    pData->fFinished = false;
+    pData->cSamples = 0;
+    pData->PerfCounterPrev.QuadPart = 0;
+
+    pData->ulTimerRes = ExSetTimerResolution(1000 * 10, 1);
+    pData->DueTime.QuadPart = -(int64_t)pData->ulTimerRes / 10;
+
+    /*
+     * Start the DPC measurements and wait for a full set.
+     */
+    KeSetTimer(&pData->Timer, pData->DueTime, &pData->Dpc);
+
+    while (!pData->fFinished)
+    {
+        LARGE_INTEGER Interval;
+        Interval.QuadPart = -100 * 1000 * 10;
+        KeDelayExecutionThread(KernelMode, TRUE, &Interval);
+    }
+
+    ExSetTimerResolution(0, 0);
+
+    /*
+     * Log everything to the host.
+     */
+    RTLogBackdoorPrintf("DPC: ulTimerRes = %d\n", pData->ulTimerRes);
+    for (int i = 0; i < pData->cSamples; i++)
+    {
+        DPCSAMPLE *pSample = &pData->aSamples[i];
+
+        RTLogBackdoorPrintf("[%d] pd %lld pc %lld pf %lld t %lld\n",
+                            i,
+                            pSample->PerfDelta.QuadPart,
+                            pSample->PerfCounter.QuadPart,
+                            pSample->PerfFrequency.QuadPart,
+                            pSample->u64TSC);
+    }
+
+    RTMemFree(pData);
+    return VINF_SUCCESS;
+}
+
+#endif /* VBOX_WITH_DPC_LATENCY_CHECKER */
+
diff --git a/src/VBox/Additions/common/VBoxGuest/VBoxGuest.cpp b/src/VBox/Additions/common/VBoxGuest/VBoxGuest.cpp
new file mode 100644
index 00000000..e6485c0b
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/VBoxGuest.cpp
@@ -0,0 +1,4516 @@
+/* $Id: VBoxGuest.cpp $ */
+/** @file
+ * VBoxGuest - Guest Additions Driver, Common Code.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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
+ */
+
+/** @page pg_vbdrv VBoxGuest
+ *
+ * VBoxGuest is the device driver for VMMDev.
+ *
+ * The device driver is shipped as part of the guest additions.  It has roots in
+ * the host VMM support driver (usually known as VBoxDrv), so fixes in platform
+ * specific code may apply to both drivers.
+ *
+ * The common code lives in VBoxGuest.cpp and is compiled both as C++ and C.
+ * The VBoxGuest.cpp source file shall not contain platform specific code,
+ * though it must occationally do a few \#ifdef RT_OS_XXX tests to cater for
+ * platform differences.  Though, in those cases, it is common that more than
+ * one platform needs special handling.
+ *
+ * On most platforms the device driver should create two device nodes, one for
+ * full (unrestricted) access to the feature set, and one which only provides a
+ * restrict set of functions.  These are generally referred to as 'vboxguest'
+ * and 'vboxuser' respectively.  Currently, this two device approach is only
+ * implemented on Linux!
+ *
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define LOG_GROUP   LOG_GROUP_DEFAULT
+#include "VBoxGuestInternal.h"
+#include <VBox/VMMDev.h> /* for VMMDEV_RAM_SIZE */
+#include <VBox/err.h>
+#include <VBox/log.h>
+#include <VBox/HostServices/GuestPropertySvc.h>
+#include <iprt/ctype.h>
+#include <iprt/mem.h>
+#include <iprt/time.h>
+#include <iprt/memobj.h>
+#include <iprt/asm.h>
+#include <iprt/asm-amd64-x86.h>
+#include <iprt/string.h>
+#include <iprt/process.h>
+#include <iprt/assert.h>
+#include <iprt/param.h>
+#include <iprt/timer.h>
+#ifdef VBOX_WITH_HGCM
+# include <iprt/thread.h>
+#endif
+#include "version-generated.h"
+#if defined(RT_OS_LINUX) || defined(RT_OS_FREEBSD)
+# include "revision-generated.h"
+#endif
+#if defined(RT_OS_SOLARIS) || defined(RT_OS_DARWIN)
+# include <iprt/rand.h>
+#endif
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+#define VBOXGUEST_ACQUIRE_STYLE_EVENTS (VMMDEV_EVENT_DISPLAY_CHANGE_REQUEST | VMMDEV_EVENT_SEAMLESS_MODE_CHANGE_REQUEST)
+
+
+/*********************************************************************************************************************************
+*   Internal Functions                                                                                                           *
+*********************************************************************************************************************************/
+#ifdef VBOX_WITH_HGCM
+static DECLCALLBACK(int) vgdrvHgcmAsyncWaitCallback(VMMDevHGCMRequestHeader *pHdrNonVolatile, void *pvUser, uint32_t u32User);
+#endif
+static int      vgdrvIoCtl_CancelAllWaitEvents(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession);
+static void     vgdrvBitUsageTrackerClear(PVBOXGUESTBITUSAGETRACER pTracker);
+static uint32_t vgdrvGetAllowedEventMaskForSession(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession);
+static int      vgdrvResetEventFilterOnHost(PVBOXGUESTDEVEXT pDevExt, uint32_t fFixedEvents);
+static int      vgdrvResetMouseStatusOnHost(PVBOXGUESTDEVEXT pDevExt);
+static int      vgdrvResetCapabilitiesOnHost(PVBOXGUESTDEVEXT pDevExt);
+static int      vgdrvSetSessionEventFilter(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession,
+                                           uint32_t fOrMask, uint32_t fNotMask, bool fSessionTermination);
+static int      vgdrvSetSessionMouseStatus(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession,
+                                           uint32_t fOrMask, uint32_t fNotMask, bool fSessionTermination);
+static int      vgdrvSetSessionCapabilities(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession,
+                                            uint32_t fOrMask, uint32_t fNoMask,
+                                            uint32_t *pfSessionCaps, uint32_t *pfGlobalCaps, bool fSessionTermination);
+static int      vgdrvAcquireSessionCapabilities(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession,
+                                                uint32_t fOrMask, uint32_t fNotMask, uint32_t fFlags, bool fSessionTermination);
+static int      vgdrvDispatchEventsLocked(PVBOXGUESTDEVEXT pDevExt, uint32_t fEvents);
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+static const uint32_t g_cbChangeMemBalloonReq = RT_UOFFSETOF(VMMDevChangeMemBalloon, aPhysPage[VMMDEV_MEMORY_BALLOON_CHUNK_PAGES]);
+
+#if defined(RT_OS_DARWIN) || defined(RT_OS_SOLARIS)
+/**
+ * Drag in the rest of IRPT since we share it with the
+ * rest of the kernel modules on Solaris.
+ */
+struct CLANG11WEIRDNESS { PFNRT pfn; } g_apfnVBoxGuestIPRTDeps[] =
+{
+    /* VirtioNet */
+    { (PFNRT)RTRandBytes },
+    /* RTSemMutex* */
+    { (PFNRT)RTSemMutexCreate },
+    { (PFNRT)RTSemMutexDestroy },
+    { (PFNRT)RTSemMutexRequest },
+    { (PFNRT)RTSemMutexRequestNoResume },
+    { (PFNRT)RTSemMutexRequestDebug },
+    { (PFNRT)RTSemMutexRequestNoResumeDebug },
+    { (PFNRT)RTSemMutexRelease },
+    { (PFNRT)RTSemMutexIsOwned },
+    { NULL }
+};
+#endif  /* RT_OS_DARWIN || RT_OS_SOLARIS  */
+
+
+/**
+ * Reserves memory in which the VMM can relocate any guest mappings
+ * that are floating around.
+ *
+ * This operation is a little bit tricky since the VMM might not accept
+ * just any address because of address clashes between the three contexts
+ * it operates in, so use a small stack to perform this operation.
+ *
+ * @returns VBox status code (ignored).
+ * @param   pDevExt     The device extension.
+ */
+static int vgdrvInitFixateGuestMappings(PVBOXGUESTDEVEXT pDevExt)
+{
+    /*
+     * Query the required space.
+     */
+    VMMDevReqHypervisorInfo *pReq;
+    int rc = VbglR0GRAlloc((VMMDevRequestHeader **)&pReq, sizeof(VMMDevReqHypervisorInfo), VMMDevReq_GetHypervisorInfo);
+    if (RT_FAILURE(rc))
+        return rc;
+    pReq->hypervisorStart = 0;
+    pReq->hypervisorSize  = 0;
+    rc = VbglR0GRPerform(&pReq->header);
+    if (RT_FAILURE(rc)) /* this shouldn't happen! */
+    {
+        VbglR0GRFree(&pReq->header);
+        return rc;
+    }
+
+    /*
+     * The VMM will report back if there is nothing it wants to map, like for
+     * instance in VT-x and AMD-V mode.
+     */
+    if (pReq->hypervisorSize == 0)
+        Log(("vgdrvInitFixateGuestMappings: nothing to do\n"));
+    else
+    {
+        /*
+         * We have to try several times since the host can be picky
+         * about certain addresses.
+         */
+        RTR0MEMOBJ  hFictive     = NIL_RTR0MEMOBJ;
+        uint32_t    cbHypervisor = pReq->hypervisorSize;
+        RTR0MEMOBJ  ahTries[5];
+        uint32_t    iTry;
+        bool        fBitched = false;
+        Log(("vgdrvInitFixateGuestMappings: cbHypervisor=%#x\n", cbHypervisor));
+        for (iTry = 0; iTry < RT_ELEMENTS(ahTries); iTry++)
+        {
+            /*
+             * Reserve space, or if that isn't supported, create a object for
+             * some fictive physical memory and map that in to kernel space.
+             *
+             * To make the code a bit uglier, most systems cannot help with
+             * 4MB alignment, so we have to deal with that in addition to
+             * having two ways of getting the memory.
+             */
+            uint32_t    uAlignment = _4M;
+            RTR0MEMOBJ  hObj;
+            rc = RTR0MemObjReserveKernel(&hObj, (void *)-1, RT_ALIGN_32(cbHypervisor, _4M), uAlignment);
+            if (rc == VERR_NOT_SUPPORTED)
+            {
+                uAlignment = PAGE_SIZE;
+                rc = RTR0MemObjReserveKernel(&hObj, (void *)-1, RT_ALIGN_32(cbHypervisor, _4M) + _4M, uAlignment);
+            }
+            /*
+             * If both RTR0MemObjReserveKernel calls above failed because either not supported or
+             * not implemented at all at the current platform, try to map the memory object into the
+             * virtual kernel space.
+             */
+            if (rc == VERR_NOT_SUPPORTED)
+            {
+                if (hFictive == NIL_RTR0MEMOBJ)
+                {
+                    rc = RTR0MemObjEnterPhys(&hObj, VBOXGUEST_HYPERVISOR_PHYSICAL_START, cbHypervisor + _4M, RTMEM_CACHE_POLICY_DONT_CARE);
+                    if (RT_FAILURE(rc))
+                        break;
+                    hFictive = hObj;
+                }
+                uAlignment = _4M;
+                rc = RTR0MemObjMapKernel(&hObj, hFictive, (void *)-1, uAlignment, RTMEM_PROT_READ | RTMEM_PROT_WRITE);
+                if (rc == VERR_NOT_SUPPORTED)
+                {
+                    uAlignment = PAGE_SIZE;
+                    rc = RTR0MemObjMapKernel(&hObj, hFictive, (void *)-1, uAlignment, RTMEM_PROT_READ | RTMEM_PROT_WRITE);
+                }
+            }
+            if (RT_FAILURE(rc))
+            {
+                LogRel(("VBoxGuest: Failed to reserve memory for the hypervisor: rc=%Rrc (cbHypervisor=%#x uAlignment=%#x iTry=%u)\n",
+                        rc, cbHypervisor, uAlignment, iTry));
+                fBitched = true;
+                break;
+            }
+
+            /*
+             * Try set it.
+             */
+            pReq->header.requestType = VMMDevReq_SetHypervisorInfo;
+            pReq->header.rc          = VERR_INTERNAL_ERROR;
+            pReq->hypervisorSize     = cbHypervisor;
+            pReq->hypervisorStart    = (RTGCPTR32)(uintptr_t)RTR0MemObjAddress(hObj);
+            if (    uAlignment == PAGE_SIZE
+                &&  pReq->hypervisorStart & (_4M - 1))
+                pReq->hypervisorStart = RT_ALIGN_32(pReq->hypervisorStart, _4M);
+            AssertMsg(RT_ALIGN_32(pReq->hypervisorStart, _4M) == pReq->hypervisorStart, ("%#x\n", pReq->hypervisorStart));
+
+            rc = VbglR0GRPerform(&pReq->header);
+            if (RT_SUCCESS(rc))
+            {
+                pDevExt->hGuestMappings = hFictive != NIL_RTR0MEMOBJ ? hFictive : hObj;
+                Log(("VBoxGuest: %p LB %#x; uAlignment=%#x iTry=%u hGuestMappings=%p (%s)\n",
+                     RTR0MemObjAddress(pDevExt->hGuestMappings),
+                     RTR0MemObjSize(pDevExt->hGuestMappings),
+                     uAlignment, iTry, pDevExt->hGuestMappings, hFictive != NIL_RTR0PTR ? "fictive" : "reservation"));
+                break;
+            }
+            ahTries[iTry] = hObj;
+        }
+
+        /*
+         * Cleanup failed attempts.
+         */
+        while (iTry-- > 0)
+            RTR0MemObjFree(ahTries[iTry], false /* fFreeMappings */);
+        if (    RT_FAILURE(rc)
+            &&  hFictive != NIL_RTR0PTR)
+            RTR0MemObjFree(hFictive, false /* fFreeMappings */);
+        if (RT_FAILURE(rc) && !fBitched)
+            LogRel(("VBoxGuest: Warning: failed to reserve %#d of memory for guest mappings.\n", cbHypervisor));
+    }
+    VbglR0GRFree(&pReq->header);
+
+    /*
+     * We ignore failed attempts for now.
+     */
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Undo what vgdrvInitFixateGuestMappings did.
+ *
+ * @param   pDevExt     The device extension.
+ */
+static void vgdrvTermUnfixGuestMappings(PVBOXGUESTDEVEXT pDevExt)
+{
+    if (pDevExt->hGuestMappings != NIL_RTR0PTR)
+    {
+        /*
+         * Tell the host that we're going to free the memory we reserved for
+         * it, the free it up. (Leak the memory if anything goes wrong here.)
+         */
+        VMMDevReqHypervisorInfo *pReq;
+        int rc = VbglR0GRAlloc((VMMDevRequestHeader **)&pReq, sizeof(VMMDevReqHypervisorInfo), VMMDevReq_SetHypervisorInfo);
+        if (RT_SUCCESS(rc))
+        {
+            pReq->hypervisorStart = 0;
+            pReq->hypervisorSize  = 0;
+            rc = VbglR0GRPerform(&pReq->header);
+            VbglR0GRFree(&pReq->header);
+        }
+        if (RT_SUCCESS(rc))
+        {
+            rc = RTR0MemObjFree(pDevExt->hGuestMappings, true /* fFreeMappings */);
+            AssertRC(rc);
+        }
+        else
+            LogRel(("vgdrvTermUnfixGuestMappings: Failed to unfix the guest mappings! rc=%Rrc\n", rc));
+
+        pDevExt->hGuestMappings = NIL_RTR0MEMOBJ;
+    }
+}
+
+
+
+/**
+ * Report the guest information to the host.
+ *
+ * @returns IPRT status code.
+ * @param   enmOSType       The OS type to report.
+ */
+static int vgdrvReportGuestInfo(VBOXOSTYPE enmOSType)
+{
+    /*
+     * Allocate and fill in the two guest info reports.
+     */
+    VMMDevReportGuestInfo2 *pReqInfo2 = NULL;
+    VMMDevReportGuestInfo  *pReqInfo1 = NULL;
+    int rc = VbglR0GRAlloc((VMMDevRequestHeader **)&pReqInfo2, sizeof (VMMDevReportGuestInfo2), VMMDevReq_ReportGuestInfo2);
+    Log(("vgdrvReportGuestInfo: VbglR0GRAlloc VMMDevReportGuestInfo2 completed with rc=%Rrc\n", rc));
+    if (RT_SUCCESS(rc))
+    {
+        pReqInfo2->guestInfo.additionsMajor    = VBOX_VERSION_MAJOR;
+        pReqInfo2->guestInfo.additionsMinor    = VBOX_VERSION_MINOR;
+        pReqInfo2->guestInfo.additionsBuild    = VBOX_VERSION_BUILD;
+        pReqInfo2->guestInfo.additionsRevision = VBOX_SVN_REV;
+        pReqInfo2->guestInfo.additionsFeatures = VBOXGSTINFO2_F_REQUESTOR_INFO;
+        RTStrCopy(pReqInfo2->guestInfo.szName, sizeof(pReqInfo2->guestInfo.szName), VBOX_VERSION_STRING);
+
+        rc = VbglR0GRAlloc((VMMDevRequestHeader **)&pReqInfo1, sizeof (VMMDevReportGuestInfo), VMMDevReq_ReportGuestInfo);
+        Log(("vgdrvReportGuestInfo: VbglR0GRAlloc VMMDevReportGuestInfo completed with rc=%Rrc\n", rc));
+        if (RT_SUCCESS(rc))
+        {
+            pReqInfo1->guestInfo.interfaceVersion = VMMDEV_VERSION;
+            pReqInfo1->guestInfo.osType           = enmOSType;
+
+            /*
+             * There are two protocols here:
+             *      1. Info2 + Info1. Supported by >=3.2.51.
+             *      2. Info1 and optionally Info2. The old protocol.
+             *
+             * We try protocol 1 first.  It will fail with VERR_NOT_SUPPORTED
+             * if not supported by the VMMDev (message ordering requirement).
+             */
+            rc = VbglR0GRPerform(&pReqInfo2->header);
+            Log(("vgdrvReportGuestInfo: VbglR0GRPerform VMMDevReportGuestInfo2 completed with rc=%Rrc\n", rc));
+            if (RT_SUCCESS(rc))
+            {
+                rc = VbglR0GRPerform(&pReqInfo1->header);
+                Log(("vgdrvReportGuestInfo: VbglR0GRPerform VMMDevReportGuestInfo completed with rc=%Rrc\n", rc));
+            }
+            else if (   rc == VERR_NOT_SUPPORTED
+                     || rc == VERR_NOT_IMPLEMENTED)
+            {
+                rc = VbglR0GRPerform(&pReqInfo1->header);
+                Log(("vgdrvReportGuestInfo: VbglR0GRPerform VMMDevReportGuestInfo completed with rc=%Rrc\n", rc));
+                if (RT_SUCCESS(rc))
+                {
+                    rc = VbglR0GRPerform(&pReqInfo2->header);
+                    Log(("vgdrvReportGuestInfo: VbglR0GRPerform VMMDevReportGuestInfo2 completed with rc=%Rrc\n", rc));
+                    if (rc == VERR_NOT_IMPLEMENTED)
+                        rc = VINF_SUCCESS;
+                }
+            }
+            VbglR0GRFree(&pReqInfo1->header);
+        }
+        VbglR0GRFree(&pReqInfo2->header);
+    }
+
+    return rc;
+}
+
+
+/**
+ * Report the guest driver status to the host.
+ *
+ * @returns IPRT status code.
+ * @param   fActive         Flag whether the driver is now active or not.
+ */
+static int vgdrvReportDriverStatus(bool fActive)
+{
+    /*
+     * Report guest status of the VBox driver to the host.
+     */
+    VMMDevReportGuestStatus *pReq2 = NULL;
+    int rc = VbglR0GRAlloc((VMMDevRequestHeader **)&pReq2, sizeof(*pReq2), VMMDevReq_ReportGuestStatus);
+    Log(("vgdrvReportDriverStatus: VbglR0GRAlloc VMMDevReportGuestStatus completed with rc=%Rrc\n", rc));
+    if (RT_SUCCESS(rc))
+    {
+        pReq2->guestStatus.facility = VBoxGuestFacilityType_VBoxGuestDriver;
+        pReq2->guestStatus.status = fActive ?
+                                    VBoxGuestFacilityStatus_Active
+                                  : VBoxGuestFacilityStatus_Inactive;
+        pReq2->guestStatus.flags = 0;
+        rc = VbglR0GRPerform(&pReq2->header);
+        Log(("vgdrvReportDriverStatus: VbglR0GRPerform VMMDevReportGuestStatus completed with fActive=%d, rc=%Rrc\n",
+             fActive ? 1 : 0, rc));
+        if (rc == VERR_NOT_IMPLEMENTED) /* Compatibility with older hosts. */
+            rc = VINF_SUCCESS;
+        VbglR0GRFree(&pReq2->header);
+    }
+
+    return rc;
+}
+
+
+/** @name Memory Ballooning
+ * @{
+ */
+
+/**
+ * Inflate the balloon by one chunk represented by an R0 memory object.
+ *
+ * The caller owns the balloon mutex.
+ *
+ * @returns IPRT status code.
+ * @param   pMemObj     Pointer to the R0 memory object.
+ * @param   pReq        The pre-allocated request for performing the VMMDev call.
+ */
+static int vgdrvBalloonInflate(PRTR0MEMOBJ pMemObj, VMMDevChangeMemBalloon *pReq)
+{
+    uint32_t iPage;
+    int rc;
+
+    for (iPage = 0; iPage < VMMDEV_MEMORY_BALLOON_CHUNK_PAGES; iPage++)
+    {
+        RTHCPHYS phys = RTR0MemObjGetPagePhysAddr(*pMemObj, iPage);
+        pReq->aPhysPage[iPage] = phys;
+    }
+
+    pReq->fInflate = true;
+    pReq->header.size = g_cbChangeMemBalloonReq;
+    pReq->cPages = VMMDEV_MEMORY_BALLOON_CHUNK_PAGES;
+
+    rc = VbglR0GRPerform(&pReq->header);
+    if (RT_FAILURE(rc))
+        LogRel(("vgdrvBalloonInflate: VbglR0GRPerform failed. rc=%Rrc\n", rc));
+    return rc;
+}
+
+
+/**
+ * Deflate the balloon by one chunk - info the host and free the memory object.
+ *
+ * The caller owns the balloon mutex.
+ *
+ * @returns IPRT status code.
+ * @param   pMemObj     Pointer to the R0 memory object.
+ *                      The memory object will be freed afterwards.
+ * @param   pReq        The pre-allocated request for performing the VMMDev call.
+ */
+static int vgdrvBalloonDeflate(PRTR0MEMOBJ pMemObj, VMMDevChangeMemBalloon *pReq)
+{
+    uint32_t iPage;
+    int rc;
+
+    for (iPage = 0; iPage < VMMDEV_MEMORY_BALLOON_CHUNK_PAGES; iPage++)
+    {
+        RTHCPHYS phys = RTR0MemObjGetPagePhysAddr(*pMemObj, iPage);
+        pReq->aPhysPage[iPage] = phys;
+    }
+
+    pReq->fInflate = false;
+    pReq->header.size = g_cbChangeMemBalloonReq;
+    pReq->cPages = VMMDEV_MEMORY_BALLOON_CHUNK_PAGES;
+
+    rc = VbglR0GRPerform(&pReq->header);
+    if (RT_FAILURE(rc))
+    {
+        LogRel(("vgdrvBalloonDeflate: VbglR0GRPerform failed. rc=%Rrc\n", rc));
+        return rc;
+    }
+
+    rc = RTR0MemObjFree(*pMemObj, true);
+    if (RT_FAILURE(rc))
+    {
+        LogRel(("vgdrvBalloonDeflate: RTR0MemObjFree(%p,true) -> %Rrc; this is *BAD*!\n", *pMemObj, rc));
+        return rc;
+    }
+
+    *pMemObj = NIL_RTR0MEMOBJ;
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Inflate/deflate the memory balloon and notify the host.
+ *
+ * This is a worker used by vgdrvIoCtl_CheckMemoryBalloon - it takes the mutex.
+ *
+ * @returns VBox status code.
+ * @param   pDevExt         The device extension.
+ * @param   cBalloonChunks  The new size of the balloon in chunks of 1MB.
+ * @param   pfHandleInR3    Where to return the handle-in-ring3 indicator
+ *                          (VINF_SUCCESS if set).
+ */
+static int vgdrvSetBalloonSizeKernel(PVBOXGUESTDEVEXT pDevExt, uint32_t cBalloonChunks, bool *pfHandleInR3)
+{
+    int rc = VINF_SUCCESS;
+
+    if (pDevExt->MemBalloon.fUseKernelAPI)
+    {
+        VMMDevChangeMemBalloon *pReq;
+        uint32_t i;
+
+        if (cBalloonChunks > pDevExt->MemBalloon.cMaxChunks)
+        {
+            LogRel(("vgdrvSetBalloonSizeKernel: illegal balloon size %u (max=%u)\n",
+                    cBalloonChunks, pDevExt->MemBalloon.cMaxChunks));
+            return VERR_INVALID_PARAMETER;
+        }
+
+        if (cBalloonChunks == pDevExt->MemBalloon.cMaxChunks)
+            return VINF_SUCCESS;   /* nothing to do */
+
+        if (   cBalloonChunks > pDevExt->MemBalloon.cChunks
+            && !pDevExt->MemBalloon.paMemObj)
+        {
+            pDevExt->MemBalloon.paMemObj = (PRTR0MEMOBJ)RTMemAllocZ(sizeof(RTR0MEMOBJ) * pDevExt->MemBalloon.cMaxChunks);
+            if (!pDevExt->MemBalloon.paMemObj)
+            {
+                LogRel(("vgdrvSetBalloonSizeKernel: no memory for paMemObj!\n"));
+                return VERR_NO_MEMORY;
+            }
+        }
+
+        rc = VbglR0GRAlloc((VMMDevRequestHeader **)&pReq, g_cbChangeMemBalloonReq, VMMDevReq_ChangeMemBalloon);
+        if (RT_FAILURE(rc))
+            return rc;
+
+        if (cBalloonChunks > pDevExt->MemBalloon.cChunks)
+        {
+            /* inflate */
+            for (i = pDevExt->MemBalloon.cChunks; i < cBalloonChunks; i++)
+            {
+                rc = RTR0MemObjAllocPhysNC(&pDevExt->MemBalloon.paMemObj[i],
+                                           VMMDEV_MEMORY_BALLOON_CHUNK_SIZE, NIL_RTHCPHYS);
+                if (RT_FAILURE(rc))
+                {
+                    if (rc == VERR_NOT_SUPPORTED)
+                    {
+                        /* not supported -- fall back to the R3-allocated memory. */
+                        rc = VINF_SUCCESS;
+                        pDevExt->MemBalloon.fUseKernelAPI = false;
+                        Assert(pDevExt->MemBalloon.cChunks == 0);
+                        Log(("VBoxGuestSetBalloonSizeKernel: PhysNC allocs not supported, falling back to R3 allocs.\n"));
+                    }
+                    /* else if (rc == VERR_NO_MEMORY || rc == VERR_NO_PHYS_MEMORY):
+                     *      cannot allocate more memory => don't try further, just stop here */
+                    /* else: XXX what else can fail?  VERR_MEMOBJ_INIT_FAILED for instance. just stop. */
+                    break;
+                }
+
+                rc = vgdrvBalloonInflate(&pDevExt->MemBalloon.paMemObj[i], pReq);
+                if (RT_FAILURE(rc))
+                {
+                    Log(("vboxGuestSetBalloonSize(inflate): failed, rc=%Rrc!\n", rc));
+                    RTR0MemObjFree(pDevExt->MemBalloon.paMemObj[i], true);
+                    pDevExt->MemBalloon.paMemObj[i] = NIL_RTR0MEMOBJ;
+                    break;
+                }
+                pDevExt->MemBalloon.cChunks++;
+            }
+        }
+        else
+        {
+            /* deflate */
+            for (i = pDevExt->MemBalloon.cChunks; i-- > cBalloonChunks;)
+            {
+                rc = vgdrvBalloonDeflate(&pDevExt->MemBalloon.paMemObj[i], pReq);
+                if (RT_FAILURE(rc))
+                {
+                    Log(("vboxGuestSetBalloonSize(deflate): failed, rc=%Rrc!\n", rc));
+                    break;
+                }
+                pDevExt->MemBalloon.cChunks--;
+            }
+        }
+
+        VbglR0GRFree(&pReq->header);
+    }
+
+    /*
+     * Set the handle-in-ring3 indicator.  When set Ring-3 will have to work
+     * the balloon changes via the other API.
+     */
+    *pfHandleInR3 = pDevExt->MemBalloon.fUseKernelAPI ? false : true;
+
+    return rc;
+}
+
+
+/**
+ * Inflate/deflate the balloon by one chunk.
+ *
+ * Worker for vgdrvIoCtl_ChangeMemoryBalloon - it takes the mutex.
+ *
+ * @returns VBox status code.
+ * @param   pDevExt         The device extension.
+ * @param   pSession        The session.
+ * @param   pvChunk         The address of the chunk to add to / remove from the
+ *                          balloon. (user space address)
+ * @param   fInflate        Inflate if true, deflate if false.
+ */
+static int vgdrvSetBalloonSizeFromUser(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession, RTR3PTR pvChunk, bool fInflate)
+{
+    VMMDevChangeMemBalloon *pReq;
+    PRTR0MEMOBJ pMemObj = NULL;
+    int rc = VINF_SUCCESS;
+    uint32_t i;
+    RT_NOREF1(pSession);
+
+    if (fInflate)
+    {
+        if (   pDevExt->MemBalloon.cChunks > pDevExt->MemBalloon.cMaxChunks - 1
+            || pDevExt->MemBalloon.cMaxChunks == 0 /* If called without first querying. */)
+        {
+            LogRel(("vgdrvSetBalloonSizeFromUser: cannot inflate balloon, already have %u chunks (max=%u)\n",
+                    pDevExt->MemBalloon.cChunks, pDevExt->MemBalloon.cMaxChunks));
+            return VERR_INVALID_PARAMETER;
+        }
+
+        if (!pDevExt->MemBalloon.paMemObj)
+        {
+            pDevExt->MemBalloon.paMemObj = (PRTR0MEMOBJ)RTMemAlloc(sizeof(RTR0MEMOBJ) * pDevExt->MemBalloon.cMaxChunks);
+            if (!pDevExt->MemBalloon.paMemObj)
+            {
+                LogRel(("vgdrvSetBalloonSizeFromUser: no memory for paMemObj!\n"));
+                return VERR_NO_MEMORY;
+            }
+            for (i = 0; i < pDevExt->MemBalloon.cMaxChunks; i++)
+                pDevExt->MemBalloon.paMemObj[i] = NIL_RTR0MEMOBJ;
+        }
+    }
+    else
+    {
+        if (pDevExt->MemBalloon.cChunks == 0)
+        {
+            AssertMsgFailed(("vgdrvSetBalloonSizeFromUser: cannot decrease balloon, already at size 0\n"));
+            return VERR_INVALID_PARAMETER;
+        }
+    }
+
+    /*
+     * Enumerate all memory objects and check if the object is already registered.
+     */
+    for (i = 0; i < pDevExt->MemBalloon.cMaxChunks; i++)
+    {
+        if (   fInflate
+            && !pMemObj
+            && pDevExt->MemBalloon.paMemObj[i] == NIL_RTR0MEMOBJ)
+            pMemObj = &pDevExt->MemBalloon.paMemObj[i]; /* found free object pointer */
+        if (RTR0MemObjAddressR3(pDevExt->MemBalloon.paMemObj[i]) == pvChunk)
+        {
+            if (fInflate)
+                return VERR_ALREADY_EXISTS; /* don't provide the same memory twice */
+            pMemObj = &pDevExt->MemBalloon.paMemObj[i];
+            break;
+        }
+    }
+    if (!pMemObj)
+    {
+        if (fInflate)
+        {
+            /* no free object pointer found -- should not happen */
+            return VERR_NO_MEMORY;
+        }
+
+        /* cannot free this memory as it wasn't provided before */
+        return VERR_NOT_FOUND;
+    }
+
+    /*
+     * Try inflate / default the balloon as requested.
+     */
+    rc = VbglR0GRAlloc((VMMDevRequestHeader **)&pReq, g_cbChangeMemBalloonReq, VMMDevReq_ChangeMemBalloon);
+    if (RT_FAILURE(rc))
+        return rc;
+    pReq->header.fRequestor = pSession->fRequestor;
+
+    if (fInflate)
+    {
+        rc = RTR0MemObjLockUser(pMemObj, pvChunk, VMMDEV_MEMORY_BALLOON_CHUNK_SIZE,
+                                RTMEM_PROT_READ | RTMEM_PROT_WRITE, NIL_RTR0PROCESS);
+        if (RT_SUCCESS(rc))
+        {
+            rc = vgdrvBalloonInflate(pMemObj, pReq);
+            if (RT_SUCCESS(rc))
+                pDevExt->MemBalloon.cChunks++;
+            else
+            {
+                Log(("vgdrvSetBalloonSizeFromUser(inflate): failed, rc=%Rrc!\n", rc));
+                RTR0MemObjFree(*pMemObj, true);
+                *pMemObj = NIL_RTR0MEMOBJ;
+            }
+        }
+    }
+    else
+    {
+        rc = vgdrvBalloonDeflate(pMemObj, pReq);
+        if (RT_SUCCESS(rc))
+            pDevExt->MemBalloon.cChunks--;
+        else
+            Log(("vgdrvSetBalloonSizeFromUser(deflate): failed, rc=%Rrc!\n", rc));
+    }
+
+    VbglR0GRFree(&pReq->header);
+    return rc;
+}
+
+
+/**
+ * Cleanup the memory balloon of a session.
+ *
+ * Will request the balloon mutex, so it must be valid and the caller must not
+ * own it already.
+ *
+ * @param   pDevExt     The device extension.
+ * @param   pSession    The session.  Can be NULL at unload.
+ */
+static void vgdrvCloseMemBalloon(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession)
+{
+    RTSemFastMutexRequest(pDevExt->MemBalloon.hMtx);
+    if (    pDevExt->MemBalloon.pOwner == pSession
+        ||  pSession == NULL /*unload*/)
+    {
+        if (pDevExt->MemBalloon.paMemObj)
+        {
+            VMMDevChangeMemBalloon *pReq;
+            int rc = VbglR0GRAlloc((VMMDevRequestHeader **)&pReq, g_cbChangeMemBalloonReq, VMMDevReq_ChangeMemBalloon);
+            if (RT_SUCCESS(rc))
+            {
+                /* fRequestor is kernel here, as we're cleaning up. */
+
+                uint32_t i;
+                for (i = pDevExt->MemBalloon.cChunks; i-- > 0;)
+                {
+                    rc = vgdrvBalloonDeflate(&pDevExt->MemBalloon.paMemObj[i], pReq);
+                    if (RT_FAILURE(rc))
+                    {
+                        LogRel(("vgdrvCloseMemBalloon: Deflate failed with rc=%Rrc.  Will leak %u chunks.\n",
+                                rc, pDevExt->MemBalloon.cChunks));
+                        break;
+                    }
+                    pDevExt->MemBalloon.paMemObj[i] = NIL_RTR0MEMOBJ;
+                    pDevExt->MemBalloon.cChunks--;
+                }
+                VbglR0GRFree(&pReq->header);
+            }
+            else
+                LogRel(("vgdrvCloseMemBalloon: Failed to allocate VMMDev request buffer (rc=%Rrc).  Will leak %u chunks.\n",
+                        rc, pDevExt->MemBalloon.cChunks));
+            RTMemFree(pDevExt->MemBalloon.paMemObj);
+            pDevExt->MemBalloon.paMemObj = NULL;
+        }
+
+        pDevExt->MemBalloon.pOwner = NULL;
+    }
+    RTSemFastMutexRelease(pDevExt->MemBalloon.hMtx);
+}
+
+/** @} */
+
+
+
+/** @name Heartbeat
+ * @{
+ */
+
+/**
+ * Sends heartbeat to host.
+ *
+ * @returns VBox status code.
+ */
+static int vgdrvHeartbeatSend(PVBOXGUESTDEVEXT pDevExt)
+{
+    int rc;
+    if (pDevExt->pReqGuestHeartbeat)
+    {
+        rc = VbglR0GRPerform(pDevExt->pReqGuestHeartbeat);
+        Log3(("vgdrvHeartbeatSend: VbglR0GRPerform vgdrvHeartbeatSend completed with rc=%Rrc\n", rc));
+    }
+    else
+        rc = VERR_INVALID_STATE;
+    return rc;
+}
+
+
+/**
+ * Callback for heartbeat timer.
+ */
+static DECLCALLBACK(void) vgdrvHeartbeatTimerHandler(PRTTIMER hTimer, void *pvUser, uint64_t iTick)
+{
+    PVBOXGUESTDEVEXT pDevExt = (PVBOXGUESTDEVEXT)pvUser;
+    int rc;
+    AssertReturnVoid(pDevExt);
+
+    rc = vgdrvHeartbeatSend(pDevExt);
+    if (RT_FAILURE(rc))
+        Log(("HB Timer: vgdrvHeartbeatSend failed: rc=%Rrc\n", rc));
+
+    NOREF(hTimer); NOREF(iTick);
+}
+
+
+/**
+ * Configure the host to check guest's heartbeat
+ * and get heartbeat interval from the host.
+ *
+ * @returns VBox status code.
+ * @param   pDevExt         The device extension.
+ * @param   fEnabled        Set true to enable guest heartbeat checks on host.
+ */
+static int vgdrvHeartbeatHostConfigure(PVBOXGUESTDEVEXT pDevExt, bool fEnabled)
+{
+    VMMDevReqHeartbeat *pReq;
+    int rc = VbglR0GRAlloc((VMMDevRequestHeader **)&pReq, sizeof(*pReq), VMMDevReq_HeartbeatConfigure);
+    Log(("vgdrvHeartbeatHostConfigure: VbglR0GRAlloc vgdrvHeartbeatHostConfigure completed with rc=%Rrc\n", rc));
+    if (RT_SUCCESS(rc))
+    {
+        pReq->fEnabled = fEnabled;
+        pReq->cNsInterval = 0;
+        rc = VbglR0GRPerform(&pReq->header);
+        Log(("vgdrvHeartbeatHostConfigure: VbglR0GRPerform vgdrvHeartbeatHostConfigure completed with rc=%Rrc\n", rc));
+        pDevExt->cNsHeartbeatInterval = pReq->cNsInterval;
+        VbglR0GRFree(&pReq->header);
+    }
+    return rc;
+}
+
+
+/**
+ * Initializes the heartbeat timer.
+ *
+ * This feature may be disabled by the host.
+ *
+ * @returns VBox status (ignored).
+ * @param   pDevExt             The device extension.
+ */
+static int vgdrvHeartbeatInit(PVBOXGUESTDEVEXT pDevExt)
+{
+    /*
+     * Make sure that heartbeat checking is disabled.
+     */
+    int rc = vgdrvHeartbeatHostConfigure(pDevExt, false);
+    if (RT_SUCCESS(rc))
+    {
+        rc = vgdrvHeartbeatHostConfigure(pDevExt, true);
+        if (RT_SUCCESS(rc))
+        {
+            /*
+             * Preallocate the request to use it from the timer callback because:
+             *    1) on Windows VbglR0GRAlloc must be called at IRQL <= APC_LEVEL
+             *       and the timer callback runs at DISPATCH_LEVEL;
+             *    2) avoid repeated allocations.
+             */
+            rc = VbglR0GRAlloc(&pDevExt->pReqGuestHeartbeat, sizeof(*pDevExt->pReqGuestHeartbeat), VMMDevReq_GuestHeartbeat);
+            if (RT_SUCCESS(rc))
+            {
+                LogRel(("vgdrvHeartbeatInit: Setting up heartbeat to trigger every %RU64 milliseconds\n",
+                        pDevExt->cNsHeartbeatInterval / RT_NS_1MS));
+                rc = RTTimerCreateEx(&pDevExt->pHeartbeatTimer, pDevExt->cNsHeartbeatInterval, 0 /*fFlags*/,
+                                     (PFNRTTIMER)vgdrvHeartbeatTimerHandler, pDevExt);
+                if (RT_SUCCESS(rc))
+                {
+                    rc = RTTimerStart(pDevExt->pHeartbeatTimer, 0);
+                    if (RT_SUCCESS(rc))
+                        return VINF_SUCCESS;
+
+                    LogRel(("vgdrvHeartbeatInit: Heartbeat timer failed to start, rc=%Rrc\n", rc));
+                }
+                else
+                    LogRel(("vgdrvHeartbeatInit: Failed to create heartbeat timer: %Rrc\n", rc));
+
+                VbglR0GRFree(pDevExt->pReqGuestHeartbeat);
+                pDevExt->pReqGuestHeartbeat = NULL;
+            }
+            else
+                LogRel(("vgdrvHeartbeatInit: VbglR0GRAlloc(VMMDevReq_GuestHeartbeat): %Rrc\n", rc));
+
+            LogRel(("vgdrvHeartbeatInit: Failed to set up the timer, guest heartbeat is disabled\n"));
+            vgdrvHeartbeatHostConfigure(pDevExt, false);
+        }
+        else
+            LogRel(("vgdrvHeartbeatInit: Failed to configure host for heartbeat checking: rc=%Rrc\n", rc));
+    }
+    return rc;
+}
+
+/** @} */
+
+
+/**
+ * Helper to reinit the VMMDev communication after hibernation.
+ *
+ * @returns VBox status code.
+ * @param   pDevExt         The device extension.
+ * @param   enmOSType       The OS type.
+ *
+ * @todo Call this on all platforms, not just windows.
+ */
+int VGDrvCommonReinitDevExtAfterHibernation(PVBOXGUESTDEVEXT pDevExt, VBOXOSTYPE enmOSType)
+{
+    int rc = vgdrvReportGuestInfo(enmOSType);
+    if (RT_SUCCESS(rc))
+    {
+        rc = vgdrvReportDriverStatus(true /* Driver is active */);
+        if (RT_FAILURE(rc))
+            Log(("VGDrvCommonReinitDevExtAfterHibernation: could not report guest driver status, rc=%Rrc\n", rc));
+    }
+    else
+        Log(("VGDrvCommonReinitDevExtAfterHibernation: could not report guest information to host, rc=%Rrc\n", rc));
+    LogFlow(("VGDrvCommonReinitDevExtAfterHibernation: returned with rc=%Rrc\n", rc));
+    RT_NOREF1(pDevExt);
+    return rc;
+}
+
+
+/**
+ * Initializes the release logger (debug is implicit), if configured.
+ *
+ * @returns IPRT status code.
+ */
+int VGDrvCommonInitLoggers(void)
+{
+#ifdef VBOX_GUESTDRV_WITH_RELEASE_LOGGER
+    /*
+     * Create the release log.
+     */
+    static const char * const s_apszGroups[] = VBOX_LOGGROUP_NAMES;
+    PRTLOGGER pRelLogger;
+    int rc = RTLogCreate(&pRelLogger, 0 /*fFlags*/, "all", "VBOXGUEST_RELEASE_LOG", RT_ELEMENTS(s_apszGroups), s_apszGroups,
+                         RTLOGDEST_STDOUT | RTLOGDEST_DEBUGGER, NULL);
+    if (RT_SUCCESS(rc))
+        RTLogRelSetDefaultInstance(pRelLogger);
+    /** @todo Add native hook for getting logger config parameters and setting
+     *        them.  On linux we should use the module parameter stuff... */
+    return rc;
+#else
+    return VINF_SUCCESS;
+#endif
+}
+
+
+/**
+ * Destroys the loggers.
+ */
+void VGDrvCommonDestroyLoggers(void)
+{
+#ifdef VBOX_GUESTDRV_WITH_RELEASE_LOGGER
+    RTLogDestroy(RTLogRelSetDefaultInstance(NULL));
+    RTLogDestroy(RTLogSetDefaultInstance(NULL));
+#endif
+}
+
+
+/**
+ * Initialize the device extension fundament.
+ *
+ * There are no device resources at this point, VGDrvCommonInitDevExtResources
+ * should be called when they are available.
+ *
+ * @returns VBox status code.
+ * @param   pDevExt         The device extension to init.
+ */
+int VGDrvCommonInitDevExtFundament(PVBOXGUESTDEVEXT pDevExt)
+{
+    int rc;
+    AssertMsg(   pDevExt->uInitState != VBOXGUESTDEVEXT_INIT_STATE_FUNDAMENT
+              && pDevExt->uInitState != VBOXGUESTDEVEXT_INIT_STATE_RESOURCES, ("uInitState=%#x\n", pDevExt->uInitState));
+
+    /*
+     * Initialize the data.
+     */
+    pDevExt->IOPortBase = UINT16_MAX;
+    pDevExt->pVMMDevMemory = NULL;
+    pDevExt->hGuestMappings = NIL_RTR0MEMOBJ;
+    pDevExt->EventSpinlock = NIL_RTSPINLOCK;
+    pDevExt->fHostFeatures = 0;
+    pDevExt->pIrqAckEvents = NULL;
+    pDevExt->PhysIrqAckEvents = NIL_RTCCPHYS;
+    RTListInit(&pDevExt->WaitList);
+#ifdef VBOX_WITH_HGCM
+    RTListInit(&pDevExt->HGCMWaitList);
+#endif
+#ifdef VBOXGUEST_USE_DEFERRED_WAKE_UP
+    RTListInit(&pDevExt->WakeUpList);
+#endif
+    RTListInit(&pDevExt->WokenUpList);
+    RTListInit(&pDevExt->FreeList);
+    RTListInit(&pDevExt->SessionList);
+    pDevExt->cSessions = 0;
+    pDevExt->fLoggingEnabled = false;
+    pDevExt->f32PendingEvents = 0;
+    pDevExt->u32MousePosChangedSeq = 0;
+    pDevExt->SessionSpinlock = NIL_RTSPINLOCK;
+    pDevExt->MemBalloon.hMtx = NIL_RTSEMFASTMUTEX;
+    pDevExt->MemBalloon.cChunks = 0;
+    pDevExt->MemBalloon.cMaxChunks = 0;
+    pDevExt->MemBalloon.fUseKernelAPI = true;
+    pDevExt->MemBalloon.paMemObj = NULL;
+    pDevExt->MemBalloon.pOwner = NULL;
+    pDevExt->pfnMouseNotifyCallback = NULL;
+    pDevExt->pvMouseNotifyCallbackArg = NULL;
+    pDevExt->pReqGuestHeartbeat = NULL;
+
+    pDevExt->fFixedEvents = 0;
+    vgdrvBitUsageTrackerClear(&pDevExt->EventFilterTracker);
+    pDevExt->fEventFilterHost = UINT32_MAX;  /* forces a report */
+
+    vgdrvBitUsageTrackerClear(&pDevExt->MouseStatusTracker);
+    pDevExt->fMouseStatusHost = UINT32_MAX;  /* forces a report */
+
+    pDevExt->fAcquireModeGuestCaps = 0;
+    pDevExt->fSetModeGuestCaps = 0;
+    pDevExt->fAcquiredGuestCaps = 0;
+    vgdrvBitUsageTrackerClear(&pDevExt->SetGuestCapsTracker);
+    pDevExt->fGuestCapsHost = UINT32_MAX; /* forces a report */
+
+    /*
+     * Create the wait and session spinlocks as well as the ballooning mutex.
+     */
+    rc = RTSpinlockCreate(&pDevExt->EventSpinlock, RTSPINLOCK_FLAGS_INTERRUPT_SAFE, "VBoxGuestEvent");
+    if (RT_SUCCESS(rc))
+    {
+        rc = RTSpinlockCreate(&pDevExt->SessionSpinlock, RTSPINLOCK_FLAGS_INTERRUPT_SAFE, "VBoxGuestSession");
+        if (RT_SUCCESS(rc))
+        {
+            rc = RTSemFastMutexCreate(&pDevExt->MemBalloon.hMtx);
+            if (RT_SUCCESS(rc))
+            {
+                pDevExt->uInitState = VBOXGUESTDEVEXT_INIT_STATE_FUNDAMENT;
+                return VINF_SUCCESS;
+            }
+
+            LogRel(("VGDrvCommonInitDevExt: failed to create mutex, rc=%Rrc!\n", rc));
+            RTSpinlockDestroy(pDevExt->SessionSpinlock);
+        }
+        else
+            LogRel(("VGDrvCommonInitDevExt: failed to create spinlock, rc=%Rrc!\n", rc));
+        RTSpinlockDestroy(pDevExt->EventSpinlock);
+    }
+    else
+        LogRel(("VGDrvCommonInitDevExt: failed to create spinlock, rc=%Rrc!\n", rc));
+
+    pDevExt->uInitState = 0;
+    return rc;
+}
+
+
+/**
+ * Counter to VGDrvCommonInitDevExtFundament.
+ *
+ * @param   pDevExt         The device extension.
+ */
+void VGDrvCommonDeleteDevExtFundament(PVBOXGUESTDEVEXT pDevExt)
+{
+    int rc2;
+    AssertMsgReturnVoid(pDevExt->uInitState == VBOXGUESTDEVEXT_INIT_STATE_FUNDAMENT, ("uInitState=%#x\n", pDevExt->uInitState));
+    pDevExt->uInitState = VBOXGUESTDEVEXT_INIT_STATE_DELETED;
+
+    rc2 = RTSemFastMutexDestroy(pDevExt->MemBalloon.hMtx); AssertRC(rc2);
+    rc2 = RTSpinlockDestroy(pDevExt->EventSpinlock); AssertRC(rc2);
+    rc2 = RTSpinlockDestroy(pDevExt->SessionSpinlock); AssertRC(rc2);
+}
+
+
+/**
+ * Initializes the VBoxGuest device extension resource parts.
+ *
+ * The native code locates the VMMDev on the PCI bus and retrieve the MMIO and
+ * I/O port ranges, this function will take care of mapping the MMIO memory (if
+ * present).  Upon successful return the native code should set up the interrupt
+ * handler.
+ *
+ * @returns VBox status code.
+ *
+ * @param   pDevExt         The device extension. Allocated by the native code.
+ * @param   IOPortBase      The base of the I/O port range.
+ * @param   pvMMIOBase      The base of the MMIO memory mapping.
+ *                          This is optional, pass NULL if not present.
+ * @param   cbMMIO          The size of the MMIO memory mapping.
+ *                          This is optional, pass 0 if not present.
+ * @param   enmOSType       The guest OS type to report to the VMMDev.
+ * @param   fFixedEvents    Events that will be enabled upon init and no client
+ *                          will ever be allowed to mask.
+ */
+int VGDrvCommonInitDevExtResources(PVBOXGUESTDEVEXT pDevExt, uint16_t IOPortBase,
+                                   void *pvMMIOBase, uint32_t cbMMIO, VBOXOSTYPE enmOSType, uint32_t fFixedEvents)
+{
+    int rc;
+    AssertMsgReturn(pDevExt->uInitState == VBOXGUESTDEVEXT_INIT_STATE_FUNDAMENT, ("uInitState=%#x\n", pDevExt->uInitState),
+                    VERR_INVALID_STATE);
+
+    /*
+     * If there is an MMIO region validate the version and size.
+     */
+    if (pvMMIOBase)
+    {
+        VMMDevMemory *pVMMDev = (VMMDevMemory *)pvMMIOBase;
+        Assert(cbMMIO);
+        if (    pVMMDev->u32Version == VMMDEV_MEMORY_VERSION
+            &&  pVMMDev->u32Size >= 32
+            &&  pVMMDev->u32Size <= cbMMIO)
+        {
+            pDevExt->pVMMDevMemory = pVMMDev;
+            Log(("VGDrvCommonInitDevExtResources: VMMDevMemory: mapping=%p size=%#RX32 (%#RX32) version=%#RX32\n",
+                 pVMMDev, pVMMDev->u32Size, cbMMIO, pVMMDev->u32Version));
+        }
+        else /* try live without it. */
+            LogRel(("VGDrvCommonInitDevExtResources: Bogus VMMDev memory; u32Version=%RX32 (expected %RX32) u32Size=%RX32 (expected <= %RX32)\n",
+                    pVMMDev->u32Version, VMMDEV_MEMORY_VERSION, pVMMDev->u32Size, cbMMIO));
+    }
+
+    /*
+     * Initialize the guest library and report the guest info back to VMMDev,
+     * set the interrupt control filter mask, and fixate the guest mappings
+     * made by the VMM.
+     */
+    pDevExt->IOPortBase = IOPortBase;
+    rc = VbglR0InitPrimary(pDevExt->IOPortBase, (VMMDevMemory *)pDevExt->pVMMDevMemory, &pDevExt->fHostFeatures);
+    if (RT_SUCCESS(rc))
+    {
+        VMMDevRequestHeader *pAckReq = NULL;
+        rc = VbglR0GRAlloc(&pAckReq, sizeof(VMMDevEvents), VMMDevReq_AcknowledgeEvents);
+        if (RT_SUCCESS(rc))
+        {
+            pDevExt->PhysIrqAckEvents = VbglR0PhysHeapGetPhysAddr(pAckReq);
+            Assert(pDevExt->PhysIrqAckEvents != 0);
+            ASMCompilerBarrier(); /* linux + solaris already have IRQs hooked up at this point, so take care. */
+            pDevExt->pIrqAckEvents = (VMMDevEvents *)pAckReq;
+
+            rc = vgdrvReportGuestInfo(enmOSType);
+            if (RT_SUCCESS(rc))
+            {
+                /*
+                 * Set the fixed event and make sure the host doesn't have any lingering
+                 * the guest capabilities or mouse status bits set.
+                 */
+#ifdef VBOX_WITH_HGCM
+                fFixedEvents |= VMMDEV_EVENT_HGCM;
+#endif
+                pDevExt->fFixedEvents = fFixedEvents;
+                rc = vgdrvResetEventFilterOnHost(pDevExt, fFixedEvents);
+                if (RT_SUCCESS(rc))
+                {
+                    rc = vgdrvResetCapabilitiesOnHost(pDevExt);
+                    if (RT_SUCCESS(rc))
+                    {
+                        rc = vgdrvResetMouseStatusOnHost(pDevExt);
+                        if (RT_SUCCESS(rc))
+                        {
+                            /*
+                             * Initialize stuff which may fail without requiring the driver init to fail.
+                             */
+                            vgdrvInitFixateGuestMappings(pDevExt);
+                            vgdrvHeartbeatInit(pDevExt);
+
+                            /*
+                             * Done!
+                             */
+                            rc = vgdrvReportDriverStatus(true /* Driver is active */);
+                            if (RT_FAILURE(rc))
+                                LogRel(("VGDrvCommonInitDevExtResources: VBoxReportGuestDriverStatus failed, rc=%Rrc\n", rc));
+
+                            pDevExt->uInitState = VBOXGUESTDEVEXT_INIT_STATE_RESOURCES;
+                            LogFlowFunc(("VGDrvCommonInitDevExtResources: returns success\n"));
+                            return VINF_SUCCESS;
+                        }
+                        LogRel(("VGDrvCommonInitDevExtResources: failed to clear mouse status: rc=%Rrc\n", rc));
+                    }
+                    else
+                        LogRel(("VGDrvCommonInitDevExtResources: failed to clear guest capabilities: rc=%Rrc\n", rc));
+                }
+                else
+                    LogRel(("VGDrvCommonInitDevExtResources: failed to set fixed event filter: rc=%Rrc\n", rc));
+                pDevExt->fFixedEvents = 0;
+            }
+            else
+                LogRel(("VGDrvCommonInitDevExtResources: vgdrvReportGuestInfo failed: rc=%Rrc\n", rc));
+            VbglR0GRFree((VMMDevRequestHeader *)pDevExt->pIrqAckEvents);
+        }
+        else
+            LogRel(("VGDrvCommonInitDevExtResources: VbglR0GRAlloc failed: rc=%Rrc\n", rc));
+
+        VbglR0TerminatePrimary();
+    }
+    else
+        LogRel(("VGDrvCommonInitDevExtResources: VbglR0InitPrimary failed: rc=%Rrc\n", rc));
+    pDevExt->IOPortBase = UINT16_MAX;
+    return rc;
+}
+
+
+/**
+ * Deletes all the items in a wait chain.
+ * @param   pList       The head of the chain.
+ */
+static void vgdrvDeleteWaitList(PRTLISTNODE pList)
+{
+    while (!RTListIsEmpty(pList))
+    {
+        int             rc2;
+        PVBOXGUESTWAIT  pWait = RTListGetFirst(pList, VBOXGUESTWAIT, ListNode);
+        RTListNodeRemove(&pWait->ListNode);
+
+        rc2 = RTSemEventMultiDestroy(pWait->Event); AssertRC(rc2);
+        pWait->Event = NIL_RTSEMEVENTMULTI;
+        pWait->pSession = NULL;
+        RTMemFree(pWait);
+    }
+}
+
+
+/**
+ * Counter to VGDrvCommonInitDevExtResources.
+ *
+ * @param   pDevExt         The device extension.
+ */
+void VGDrvCommonDeleteDevExtResources(PVBOXGUESTDEVEXT pDevExt)
+{
+    Log(("VGDrvCommonDeleteDevExtResources:\n"));
+    AssertMsgReturnVoid(pDevExt->uInitState == VBOXGUESTDEVEXT_INIT_STATE_RESOURCES, ("uInitState=%#x\n", pDevExt->uInitState));
+    pDevExt->uInitState = VBOXGUESTDEVEXT_INIT_STATE_FUNDAMENT;
+
+    /*
+     * Stop and destroy HB timer and disable host heartbeat checking.
+     */
+    if (pDevExt->pHeartbeatTimer)
+    {
+        RTTimerDestroy(pDevExt->pHeartbeatTimer);
+        vgdrvHeartbeatHostConfigure(pDevExt, false);
+    }
+
+    VbglR0GRFree(pDevExt->pReqGuestHeartbeat);
+    pDevExt->pReqGuestHeartbeat = NULL;
+
+    /*
+     * Clean up the bits that involves the host first.
+     */
+    vgdrvTermUnfixGuestMappings(pDevExt);
+    if (!RTListIsEmpty(&pDevExt->SessionList))
+    {
+        LogRelFunc(("session list not empty!\n"));
+        RTListInit(&pDevExt->SessionList);
+    }
+
+    /*
+     * Update the host flags (mouse status etc) not to reflect this session.
+     */
+    pDevExt->fFixedEvents = 0;
+    vgdrvResetEventFilterOnHost(pDevExt, 0 /*fFixedEvents*/);
+    vgdrvResetCapabilitiesOnHost(pDevExt);
+    vgdrvResetMouseStatusOnHost(pDevExt);
+
+    vgdrvCloseMemBalloon(pDevExt, (PVBOXGUESTSESSION)NULL);
+
+    /*
+     * No more IRQs.
+     */
+    pDevExt->pIrqAckEvents = NULL; /* Will be freed by VbglR0TerminatePrimary. */
+    ASMAtomicWriteU32(&pDevExt->fHostFeatures, 0);
+
+    /*
+     * Cleanup all the other resources.
+     */
+    vgdrvDeleteWaitList(&pDevExt->WaitList);
+#ifdef VBOX_WITH_HGCM
+    vgdrvDeleteWaitList(&pDevExt->HGCMWaitList);
+#endif
+#ifdef VBOXGUEST_USE_DEFERRED_WAKE_UP
+    vgdrvDeleteWaitList(&pDevExt->WakeUpList);
+#endif
+    vgdrvDeleteWaitList(&pDevExt->WokenUpList);
+    vgdrvDeleteWaitList(&pDevExt->FreeList);
+
+    VbglR0TerminatePrimary();
+
+
+    pDevExt->pVMMDevMemory = NULL;
+    pDevExt->IOPortBase = 0;
+}
+
+
+/**
+ * Initializes the VBoxGuest device extension when the device driver is loaded.
+ *
+ * The native code locates the VMMDev on the PCI bus and retrieve the MMIO and
+ * I/O port ranges, this function will take care of mapping the MMIO memory (if
+ * present). Upon successful return the native code should set up the interrupt
+ * handler.
+ *
+ * Instead of calling this method, the host specific code choose to perform a
+ * more granular initialization using:
+ *      1. VGDrvCommonInitLoggers
+ *      2. VGDrvCommonInitDevExtFundament
+ *      3. VGDrvCommonInitDevExtResources
+ *
+ * @returns VBox status code.
+ *
+ * @param   pDevExt         The device extension. Allocated by the native code.
+ * @param   IOPortBase      The base of the I/O port range.
+ * @param   pvMMIOBase      The base of the MMIO memory mapping.
+ *                          This is optional, pass NULL if not present.
+ * @param   cbMMIO          The size of the MMIO memory mapping.
+ *                          This is optional, pass 0 if not present.
+ * @param   enmOSType       The guest OS type to report to the VMMDev.
+ * @param   fFixedEvents    Events that will be enabled upon init and no client
+ *                          will ever be allowed to mask.
+ */
+int VGDrvCommonInitDevExt(PVBOXGUESTDEVEXT pDevExt, uint16_t IOPortBase,
+                          void *pvMMIOBase, uint32_t cbMMIO, VBOXOSTYPE enmOSType, uint32_t fFixedEvents)
+{
+    int rc;
+    VGDrvCommonInitLoggers();
+
+    rc = VGDrvCommonInitDevExtFundament(pDevExt);
+    if (RT_SUCCESS(rc))
+    {
+        rc = VGDrvCommonInitDevExtResources(pDevExt, IOPortBase, pvMMIOBase, cbMMIO, enmOSType, fFixedEvents);
+        if (RT_SUCCESS(rc))
+            return rc;
+
+        VGDrvCommonDeleteDevExtFundament(pDevExt);
+    }
+    VGDrvCommonDestroyLoggers();
+    return rc; /* (failed) */
+}
+
+
+/**
+ * Checks if the given option can be taken to not mean 'false'.
+ *
+ * @returns true or false accordingly.
+ * @param   pszValue            The value to consider.
+ */
+bool VBDrvCommonIsOptionValueTrue(const char *pszValue)
+{
+    if (pszValue)
+    {
+        char ch;
+        while (  (ch = *pszValue) != '\0'
+               && RT_C_IS_SPACE(ch))
+            pszValue++;
+
+        return ch != '\0'
+            && ch != 'n' /* no */
+            && ch != 'N' /* NO */
+            && ch != 'd' /* disabled */
+            && ch != 'f' /* false*/
+            && ch != 'F' /* FALSE */
+            && ch != 'D' /* DISABLED */
+            && (   (ch != 'o' && ch != 'O') /* off, OFF, Off */
+                || (pszValue[1] != 'f' && pszValue[1] != 'F') )
+            && (ch != '0' || pszValue[1] != '\0') /* '0' */
+            ;
+    }
+    return false;
+}
+
+
+/**
+ * Processes a option.
+ *
+ * This will let the OS specific code have a go at it too.
+ *
+ * @param   pDevExt         The device extension.
+ * @param   pszName         The option name, sans prefix.
+ * @param   pszValue        The option value.
+ */
+void VGDrvCommonProcessOption(PVBOXGUESTDEVEXT pDevExt, const char *pszName, const char *pszValue)
+{
+    Log(("VGDrvCommonProcessOption: pszName='%s' pszValue='%s'\n", pszName, pszValue));
+
+    if (   RTStrICmpAscii(pszName, "r3_log_to_host") == 0
+        || RTStrICmpAscii(pszName, "LoggingEnabled") == 0 /*legacy*/ )
+        pDevExt->fLoggingEnabled = VBDrvCommonIsOptionValueTrue(pszValue);
+    else if (   RTStrNICmpAscii(pszName, RT_STR_TUPLE("log")) == 0
+             || RTStrNICmpAscii(pszName, RT_STR_TUPLE("dbg_log")) == 0)
+    {
+        bool const  fDbgRel    = *pszName == 'd' || *pszName == 'D';
+        const char *pszSubName = &pszName[fDbgRel ? 4 + 3 : 3];
+        if (   !*pszSubName
+            || RTStrICmpAscii(pszSubName, "_flags") == 0
+            || RTStrICmpAscii(pszSubName, "_dest") == 0)
+        {
+            PRTLOGGER pLogger = !fDbgRel ? RTLogRelGetDefaultInstance() : RTLogDefaultInstance();
+            if (pLogger)
+            {
+                if (!*pszSubName)
+                    RTLogGroupSettings(pLogger, pszValue);
+                else if (RTStrICmpAscii(pszSubName, "_flags"))
+                    RTLogFlags(pLogger, pszValue);
+                else
+                    RTLogDestinations(pLogger, pszValue);
+            }
+        }
+        else if (!VGDrvNativeProcessOption(pDevExt, pszName, pszValue))
+            LogRel(("VBoxGuest: Ignoring unknown option '%s' (value '%s')\n", pszName, pszValue));
+    }
+    else if (!VGDrvNativeProcessOption(pDevExt, pszName, pszValue))
+        LogRel(("VBoxGuest: Ignoring unknown option '%s' (value '%s')\n", pszName, pszValue));
+}
+
+
+/**
+ * Read driver configuration from the host.
+ *
+ * This involves connecting to the guest properties service, which means that
+ * interrupts needs to work and that the calling thread must be able to block.
+ *
+ * @param   pDevExt     The device extension.
+ */
+void VGDrvCommonProcessOptionsFromHost(PVBOXGUESTDEVEXT pDevExt)
+{
+    /*
+     * Create a kernel session without our selves, then connect to the HGCM service.
+     */
+    PVBOXGUESTSESSION pSession;
+    int rc = VGDrvCommonCreateKernelSession(pDevExt, &pSession);
+    if (RT_SUCCESS(rc))
+    {
+        union
+        {
+            VBGLIOCHGCMCONNECT          Connect;
+            VBGLIOCHGCMDISCONNECT       Disconnect;
+            GuestPropMsgEnumProperties  EnumMsg;
+        } uBuf;
+
+        RT_ZERO(uBuf.Connect);
+        VBGLREQHDR_INIT(&uBuf.Connect.Hdr, HGCM_CONNECT);
+        uBuf.Connect.u.In.Loc.type = VMMDevHGCMLoc_LocalHost_Existing;
+        RTStrCopy(uBuf.Connect.u.In.Loc.u.host.achName, sizeof(uBuf.Connect.u.In.Loc.u.host.achName),
+                  "VBoxGuestPropSvc"); /** @todo Add a define to the header for the name. */
+        rc = VGDrvCommonIoCtl(VBGL_IOCTL_HGCM_CONNECT, pDevExt, pSession, &uBuf.Connect.Hdr, sizeof(uBuf.Connect));
+        if (RT_SUCCESS(rc))
+        {
+            static const char   g_szzPattern[] = "/VirtualBox/GuestAdd/VBoxGuest/*\0";
+            uint32_t const      idClient       = uBuf.Connect.u.Out.idClient;
+            char               *pszzStrings    = NULL;
+            uint32_t            cbStrings;
+
+            /*
+             * Enumerate all the relevant properties.  We try with a 1KB buffer, but
+             * will double it until we get what we want or go beyond 16KB.
+             */
+            for (cbStrings = _1K; cbStrings <= _16K; cbStrings *= 2)
+            {
+                pszzStrings = (char *)RTMemAllocZ(cbStrings);
+                if (pszzStrings)
+                {
+                    VBGL_HGCM_HDR_INIT(&uBuf.EnumMsg.hdr, idClient, GUEST_PROP_FN_ENUM_PROPS, 3);
+
+                    uBuf.EnumMsg.patterns.type                    = VMMDevHGCMParmType_LinAddr;
+                    uBuf.EnumMsg.patterns.u.Pointer.size          = sizeof(g_szzPattern);
+                    uBuf.EnumMsg.patterns.u.Pointer.u.linearAddr  = (uintptr_t)g_szzPattern;
+
+                    uBuf.EnumMsg.strings.type                     = VMMDevHGCMParmType_LinAddr;
+                    uBuf.EnumMsg.strings.u.Pointer.size           = cbStrings;
+                    uBuf.EnumMsg.strings.u.Pointer.u.linearAddr   = (uintptr_t)pszzStrings;
+
+                    uBuf.EnumMsg.size.type                        = VMMDevHGCMParmType_32bit;
+                    uBuf.EnumMsg.size.u.value32                   = 0;
+
+                    rc = VGDrvCommonIoCtl(VBGL_IOCTL_HGCM_CALL(sizeof(uBuf.EnumMsg)), pDevExt, pSession,
+                                          &uBuf.EnumMsg.hdr.Hdr, sizeof(uBuf.EnumMsg));
+                    if (RT_SUCCESS(rc))
+                    {
+                        if (   uBuf.EnumMsg.size.type == VMMDevHGCMParmType_32bit
+                            && uBuf.EnumMsg.size.u.value32 <= cbStrings
+                            && uBuf.EnumMsg.size.u.value32 > 0)
+                            cbStrings = uBuf.EnumMsg.size.u.value32;
+                        Log(("VGDrvCommonReadConfigurationFromHost: GUEST_PROP_FN_ENUM_PROPS -> %#x bytes (cbStrings=%#x)\n",
+                             uBuf.EnumMsg.size.u.value32, cbStrings));
+                        break;
+                    }
+
+                    RTMemFree(pszzStrings);
+                    pszzStrings = NULL;
+                }
+                else
+                {
+                    LogRel(("VGDrvCommonReadConfigurationFromHost: failed to allocate %#x bytes\n", cbStrings));
+                    break;
+                }
+            }
+
+            /*
+             * Disconnect and destroy the session.
+             */
+            VBGLREQHDR_INIT(&uBuf.Disconnect.Hdr, HGCM_DISCONNECT);
+            uBuf.Disconnect.u.In.idClient = idClient;
+            VGDrvCommonIoCtl(VBGL_IOCTL_HGCM_DISCONNECT, pDevExt, pSession, &uBuf.Disconnect.Hdr, sizeof(uBuf.Disconnect));
+
+            VGDrvCommonCloseSession(pDevExt, pSession);
+
+            /*
+             * Process the properties if we got any.
+             *
+             * The string buffer contains packed strings in groups of four - name, value,
+             * timestamp (as a decimal string) and flags.  It is terminated by four empty
+             * strings.  Layout:
+             *   Name\0Value\0Timestamp\0Flags\0
+             */
+            if (pszzStrings)
+            {
+                uint32_t off;
+                for (off = 0; off < cbStrings; off++)
+                {
+                    /*
+                     * Parse the four fields, checking that it's all plain ASCII w/o any control characters.
+                     */
+                    const char *apszFields[4] = { NULL, NULL, NULL, NULL };
+                    bool        fValidFields  = true;
+                    unsigned    iField;
+                    for (iField = 0; iField < RT_ELEMENTS(apszFields); iField++)
+                    {
+                        apszFields[0] = &pszzStrings[off];
+                        while (off < cbStrings)
+                        {
+                            char ch = pszzStrings[off++];
+                            if ((unsigned)ch < 0x20U || (unsigned)ch > 0x7fU)
+                            {
+                                if (!ch)
+                                    break;
+                                if (fValidFields)
+                                    Log(("VGDrvCommonReadConfigurationFromHost: Invalid char %#x at %#x (field %u)\n",
+                                         ch, off - 1, iField));
+                                fValidFields = false;
+                            }
+                        }
+                    }
+                    if (   off <= cbStrings
+                        && fValidFields
+                        && *apszFields[0] != '\0')
+                    {
+                        /*
+                         * Validate and convert the flags to integer, then process the option.
+                         */
+                        uint32_t fFlags = 0;
+                        rc = GuestPropValidateFlags(apszFields[3], &fFlags);
+                        if (RT_SUCCESS(rc))
+                        {
+                            if (fFlags & GUEST_PROP_F_RDONLYGUEST)
+                            {
+                                apszFields[0] += sizeof(g_szzPattern) - 2;
+                                VGDrvCommonProcessOption(pDevExt, apszFields[0], apszFields[1]);
+                            }
+                            else
+                                LogRel(("VBoxGuest: Ignoring '%s' as it does not have RDONLYGUEST set\n", apszFields[0]));
+                        }
+                        else
+                            LogRel(("VBoxGuest: Invalid flags '%s' for '%s': %Rrc\n", apszFields[2], apszFields[0], rc));
+                    }
+                    else if (off < cbStrings)
+                    {
+                        LogRel(("VBoxGuest: Malformed guest properties enum result!\n"));
+                        Log(("VBoxGuest: off=%#x cbStrings=%#x\n%.*Rhxd\n", off, cbStrings, cbStrings, pszzStrings));
+                        break;
+                    }
+                    else if (!fValidFields)
+                        LogRel(("VBoxGuest: Ignoring %.*Rhxs as it has invalid characters in one or more fields\n",
+                                (int)strlen(apszFields[0]), apszFields[0]));
+                    else
+                        break;
+                }
+
+                RTMemFree(pszzStrings);
+            }
+            else
+                LogRel(("VGDrvCommonReadConfigurationFromHost: failed to enumerate '%s': %Rrc\n", g_szzPattern, rc));
+
+        }
+        else
+            LogRel(("VGDrvCommonReadConfigurationFromHost: failed to connect: %Rrc\n", rc));
+    }
+    else
+        LogRel(("VGDrvCommonReadConfigurationFromHost: failed to connect: %Rrc\n", rc));
+}
+
+
+/**
+ * Destroys the VBoxGuest device extension.
+ *
+ * The native code should call this before the driver is unloaded,
+ * but don't call this on shutdown.
+ *
+ * @param   pDevExt         The device extension.
+ */
+void VGDrvCommonDeleteDevExt(PVBOXGUESTDEVEXT pDevExt)
+{
+    Log(("VGDrvCommonDeleteDevExt:\n"));
+    Log(("VBoxGuest: The additions driver is terminating.\n"));
+    VGDrvCommonDeleteDevExtResources(pDevExt);
+    VGDrvCommonDeleteDevExtFundament(pDevExt);
+    VGDrvCommonDestroyLoggers();
+}
+
+
+/**
+ * Creates a VBoxGuest user session.
+ *
+ * The native code calls this when a ring-3 client opens the device.
+ * Use VGDrvCommonCreateKernelSession when a ring-0 client connects.
+ *
+ * @returns VBox status code.
+ * @param   pDevExt         The device extension.
+ * @param   fRequestor      VMMDEV_REQUESTOR_XXX.
+ * @param   ppSession       Where to store the session on success.
+ */
+int VGDrvCommonCreateUserSession(PVBOXGUESTDEVEXT pDevExt, uint32_t fRequestor, PVBOXGUESTSESSION *ppSession)
+{
+    PVBOXGUESTSESSION pSession = (PVBOXGUESTSESSION)RTMemAllocZ(sizeof(*pSession));
+    if (RT_UNLIKELY(!pSession))
+    {
+        LogRel(("VGDrvCommonCreateUserSession: no memory!\n"));
+        return VERR_NO_MEMORY;
+    }
+
+    pSession->Process = RTProcSelf();
+    pSession->R0Process = RTR0ProcHandleSelf();
+    pSession->pDevExt = pDevExt;
+    pSession->fRequestor = fRequestor;
+    pSession->fUserSession = RT_BOOL(fRequestor & VMMDEV_REQUESTOR_USER_DEVICE);
+    RTSpinlockAcquire(pDevExt->SessionSpinlock);
+    RTListAppend(&pDevExt->SessionList, &pSession->ListNode);
+    pDevExt->cSessions++;
+    RTSpinlockRelease(pDevExt->SessionSpinlock);
+
+    *ppSession = pSession;
+    LogFlow(("VGDrvCommonCreateUserSession: pSession=%p proc=%RTproc (%d) r0proc=%p\n",
+             pSession, pSession->Process, (int)pSession->Process, (uintptr_t)pSession->R0Process)); /** @todo %RTr0proc */
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Creates a VBoxGuest kernel session.
+ *
+ * The native code calls this when a ring-0 client connects to the device.
+ * Use VGDrvCommonCreateUserSession when a ring-3 client opens the device.
+ *
+ * @returns VBox status code.
+ * @param   pDevExt         The device extension.
+ * @param   ppSession       Where to store the session on success.
+ */
+int VGDrvCommonCreateKernelSession(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION *ppSession)
+{
+    PVBOXGUESTSESSION pSession = (PVBOXGUESTSESSION)RTMemAllocZ(sizeof(*pSession));
+    if (RT_UNLIKELY(!pSession))
+    {
+        LogRel(("VGDrvCommonCreateKernelSession: no memory!\n"));
+        return VERR_NO_MEMORY;
+    }
+
+    pSession->Process = NIL_RTPROCESS;
+    pSession->R0Process = NIL_RTR0PROCESS;
+    pSession->pDevExt = pDevExt;
+    pSession->fRequestor = VMMDEV_REQUESTOR_KERNEL        | VMMDEV_REQUESTOR_USR_DRV_OTHER
+                         | VMMDEV_REQUESTOR_CON_DONT_KNOW | VMMDEV_REQUESTOR_TRUST_NOT_GIVEN;
+    RTSpinlockAcquire(pDevExt->SessionSpinlock);
+    RTListAppend(&pDevExt->SessionList, &pSession->ListNode);
+    pDevExt->cSessions++;
+    RTSpinlockRelease(pDevExt->SessionSpinlock);
+
+    *ppSession = pSession;
+    LogFlow(("VGDrvCommonCreateKernelSession: pSession=%p proc=%RTproc (%d) r0proc=%p\n",
+             pSession, pSession->Process, (int)pSession->Process, (uintptr_t)pSession->R0Process)); /** @todo %RTr0proc */
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Closes a VBoxGuest session.
+ *
+ * @param   pDevExt         The device extension.
+ * @param   pSession        The session to close (and free).
+ */
+void VGDrvCommonCloseSession(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession)
+{
+#ifdef VBOX_WITH_HGCM
+    unsigned i;
+#endif
+    LogFlow(("VGDrvCommonCloseSession: pSession=%p proc=%RTproc (%d) r0proc=%p\n",
+             pSession, pSession->Process, (int)pSession->Process, (uintptr_t)pSession->R0Process)); /** @todo %RTr0proc */
+
+    RTSpinlockAcquire(pDevExt->SessionSpinlock);
+    RTListNodeRemove(&pSession->ListNode);
+    pDevExt->cSessions--;
+    RTSpinlockRelease(pDevExt->SessionSpinlock);
+    vgdrvAcquireSessionCapabilities(pDevExt, pSession, 0, UINT32_MAX, VBGL_IOC_AGC_FLAGS_DEFAULT, true /*fSessionTermination*/);
+    vgdrvSetSessionCapabilities(pDevExt, pSession, 0 /*fOrMask*/, UINT32_MAX /*fNotMask*/,
+                                NULL /*pfSessionCaps*/, NULL /*pfGlobalCaps*/, true /*fSessionTermination*/);
+    vgdrvSetSessionEventFilter(pDevExt, pSession, 0 /*fOrMask*/, UINT32_MAX /*fNotMask*/, true /*fSessionTermination*/);
+    vgdrvSetSessionMouseStatus(pDevExt, pSession, 0 /*fOrMask*/, UINT32_MAX /*fNotMask*/, true /*fSessionTermination*/);
+
+    vgdrvIoCtl_CancelAllWaitEvents(pDevExt, pSession);
+
+#ifdef VBOX_WITH_HGCM
+    for (i = 0; i < RT_ELEMENTS(pSession->aHGCMClientIds); i++)
+        if (pSession->aHGCMClientIds[i])
+        {
+            uint32_t idClient = pSession->aHGCMClientIds[i];
+            pSession->aHGCMClientIds[i] = 0;
+            Log(("VGDrvCommonCloseSession: disconnecting client id %#RX32\n", idClient));
+            VbglR0HGCMInternalDisconnect(idClient, VMMDEV_REQUESTOR_KERNEL | VMMDEV_REQUESTOR_USR_DRV,
+                                         vgdrvHgcmAsyncWaitCallback, pDevExt, RT_INDEFINITE_WAIT);
+        }
+#endif
+
+    pSession->pDevExt = NULL;
+    pSession->Process = NIL_RTPROCESS;
+    pSession->R0Process = NIL_RTR0PROCESS;
+    vgdrvCloseMemBalloon(pDevExt, pSession);
+    RTMemFree(pSession);
+}
+
+
+/**
+ * Allocates a wait-for-event entry.
+ *
+ * @returns The wait-for-event entry.
+ * @param   pDevExt         The device extension.
+ * @param   pSession        The session that's allocating this. Can be NULL.
+ */
+static PVBOXGUESTWAIT vgdrvWaitAlloc(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession)
+{
+    /*
+     * Allocate it one way or the other.
+     */
+    PVBOXGUESTWAIT pWait = RTListGetFirst(&pDevExt->FreeList, VBOXGUESTWAIT, ListNode);
+    if (pWait)
+    {
+        RTSpinlockAcquire(pDevExt->EventSpinlock);
+
+        pWait = RTListGetFirst(&pDevExt->FreeList, VBOXGUESTWAIT, ListNode);
+        if (pWait)
+            RTListNodeRemove(&pWait->ListNode);
+
+        RTSpinlockRelease(pDevExt->EventSpinlock);
+    }
+    if (!pWait)
+    {
+        int rc;
+
+        pWait = (PVBOXGUESTWAIT)RTMemAlloc(sizeof(*pWait));
+        if (!pWait)
+        {
+            LogRelMax(32, ("vgdrvWaitAlloc: out-of-memory!\n"));
+            return NULL;
+        }
+
+        rc = RTSemEventMultiCreate(&pWait->Event);
+        if (RT_FAILURE(rc))
+        {
+            LogRelMax(32, ("vgdrvWaitAlloc: RTSemEventMultiCreate failed with rc=%Rrc!\n", rc));
+            RTMemFree(pWait);
+            return NULL;
+        }
+
+        pWait->ListNode.pNext = NULL;
+        pWait->ListNode.pPrev = NULL;
+    }
+
+    /*
+     * Zero members just as an precaution.
+     */
+    pWait->fReqEvents = 0;
+    pWait->fResEvents = 0;
+#ifdef VBOXGUEST_USE_DEFERRED_WAKE_UP
+    pWait->fPendingWakeUp = false;
+    pWait->fFreeMe = false;
+#endif
+    pWait->pSession = pSession;
+#ifdef VBOX_WITH_HGCM
+    pWait->pHGCMReq = NULL;
+#endif
+    RTSemEventMultiReset(pWait->Event);
+    return pWait;
+}
+
+
+/**
+ * Frees the wait-for-event entry.
+ *
+ * The caller must own the wait spinlock !
+ * The entry must be in a list!
+ *
+ * @param   pDevExt         The device extension.
+ * @param   pWait           The wait-for-event entry to free.
+ */
+static void vgdrvWaitFreeLocked(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTWAIT pWait)
+{
+    pWait->fReqEvents = 0;
+    pWait->fResEvents = 0;
+#ifdef VBOX_WITH_HGCM
+    pWait->pHGCMReq = NULL;
+#endif
+#ifdef VBOXGUEST_USE_DEFERRED_WAKE_UP
+    Assert(!pWait->fFreeMe);
+    if (pWait->fPendingWakeUp)
+        pWait->fFreeMe = true;
+    else
+#endif
+    {
+        RTListNodeRemove(&pWait->ListNode);
+        RTListAppend(&pDevExt->FreeList, &pWait->ListNode);
+    }
+}
+
+
+/**
+ * Frees the wait-for-event entry.
+ *
+ * @param   pDevExt         The device extension.
+ * @param   pWait           The wait-for-event entry to free.
+ */
+static void vgdrvWaitFreeUnlocked(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTWAIT pWait)
+{
+    RTSpinlockAcquire(pDevExt->EventSpinlock);
+    vgdrvWaitFreeLocked(pDevExt, pWait);
+    RTSpinlockRelease(pDevExt->EventSpinlock);
+}
+
+
+#ifdef VBOXGUEST_USE_DEFERRED_WAKE_UP
+/**
+ * Processes the wake-up list.
+ *
+ * All entries in the wake-up list gets signalled and moved to the woken-up
+ * list.
+ * At least on Windows this function can be invoked concurrently from
+ * different VCPUs. So, be thread-safe.
+ *
+ * @param   pDevExt         The device extension.
+ */
+void VGDrvCommonWaitDoWakeUps(PVBOXGUESTDEVEXT pDevExt)
+{
+    if (!RTListIsEmpty(&pDevExt->WakeUpList))
+    {
+        RTSpinlockAcquire(pDevExt->EventSpinlock);
+        for (;;)
+        {
+            int            rc;
+            PVBOXGUESTWAIT pWait = RTListGetFirst(&pDevExt->WakeUpList, VBOXGUESTWAIT, ListNode);
+            if (!pWait)
+                break;
+            /* Prevent other threads from accessing pWait when spinlock is released. */
+            RTListNodeRemove(&pWait->ListNode);
+
+            pWait->fPendingWakeUp = true;
+            RTSpinlockRelease(pDevExt->EventSpinlock);
+
+            rc = RTSemEventMultiSignal(pWait->Event);
+            AssertRC(rc);
+
+            RTSpinlockAcquire(pDevExt->EventSpinlock);
+            Assert(pWait->ListNode.pNext == NULL && pWait->ListNode.pPrev == NULL);
+            RTListAppend(&pDevExt->WokenUpList, &pWait->ListNode);
+            pWait->fPendingWakeUp = false;
+            if (RT_LIKELY(!pWait->fFreeMe))
+            { /* likely */ }
+            else
+            {
+                pWait->fFreeMe = false;
+                vgdrvWaitFreeLocked(pDevExt, pWait);
+            }
+        }
+        RTSpinlockRelease(pDevExt->EventSpinlock);
+    }
+}
+#endif /* VBOXGUEST_USE_DEFERRED_WAKE_UP */
+
+
+/**
+ * Implements the fast (no input or output) type of IOCtls.
+ *
+ * This is currently just a placeholder stub inherited from the support driver code.
+ *
+ * @returns VBox status code.
+ * @param   iFunction   The IOCtl function number.
+ * @param   pDevExt     The device extension.
+ * @param   pSession    The session.
+ */
+int VGDrvCommonIoCtlFast(uintptr_t iFunction, PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession)
+{
+    LogFlow(("VGDrvCommonIoCtlFast: iFunction=%#x pDevExt=%p pSession=%p\n", iFunction, pDevExt, pSession));
+
+    NOREF(iFunction);
+    NOREF(pDevExt);
+    NOREF(pSession);
+    return VERR_NOT_SUPPORTED;
+}
+
+
+/**
+ * Gets the driver I/O control interface version, maybe adjusting it for
+ * backwards compatibility.
+ *
+ * The adjusting is currently not implemented as we only have one major I/O
+ * control interface version out there to support.  This is something we will
+ * implement as needed.
+ *
+ * returns IPRT status code.
+ * @param   pDevExt         The device extension.
+ * @param   pSession        The session.
+ * @param   pReq            The request info.
+ */
+static int vgdrvIoCtl_DriverVersionInfo(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession, PVBGLIOCDRIVERVERSIONINFO pReq)
+{
+    int rc;
+    LogFlow(("VBGL_IOCTL_DRIVER_VERSION_INFO: uReqVersion=%#x uMinVersion=%#x uReserved1=%#x uReserved2=%#x\n",
+             pReq->u.In.uReqVersion, pReq->u.In.uMinVersion, pReq->u.In.uReserved1, pReq->u.In.uReserved2));
+    RT_NOREF2(pDevExt, pSession);
+
+    /*
+     * Input validation.
+     */
+    if (   pReq->u.In.uMinVersion <= pReq->u.In.uReqVersion
+        && RT_HI_U16(pReq->u.In.uMinVersion) == RT_HI_U16(pReq->u.In.uReqVersion))
+    {
+        /*
+         * Match the version.
+         * The current logic is very simple, match the major interface version.
+         */
+        if (   pReq->u.In.uMinVersion <= VBGL_IOC_VERSION
+            && RT_HI_U16(pReq->u.In.uMinVersion) == RT_HI_U16(VBGL_IOC_VERSION))
+            rc = VINF_SUCCESS;
+        else
+        {
+            LogRel(("VBGL_IOCTL_DRIVER_VERSION_INFO: Version mismatch. Requested: %#x  Min: %#x  Current: %#x\n",
+                    pReq->u.In.uReqVersion, pReq->u.In.uMinVersion, VBGL_IOC_VERSION));
+            rc = VERR_VERSION_MISMATCH;
+        }
+    }
+    else
+    {
+        LogRel(("VBGL_IOCTL_DRIVER_VERSION_INFO: uMinVersion=%#x uMaxVersion=%#x doesn't match!\n",
+                pReq->u.In.uMinVersion, pReq->u.In.uReqVersion));
+        rc = VERR_INVALID_PARAMETER;
+    }
+
+    pReq->u.Out.uSessionVersion = RT_SUCCESS(rc) ? VBGL_IOC_VERSION : UINT32_MAX;
+    pReq->u.Out.uDriverVersion  = VBGL_IOC_VERSION;
+    pReq->u.Out.uDriverRevision = VBOX_SVN_REV;
+    pReq->u.Out.uReserved1      = 0;
+    pReq->u.Out.uReserved2      = 0;
+    return rc;
+}
+
+
+/**
+ * Similar to vgdrvIoCtl_DriverVersionInfo, except its for IDC.
+ *
+ * returns IPRT status code.
+ * @param   pDevExt         The device extension.
+ * @param   pSession        The session.
+ * @param   pReq            The request info.
+ */
+static int vgdrvIoCtl_IdcConnect(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession, PVBGLIOCIDCCONNECT pReq)
+{
+    int rc;
+    LogFlow(("VBGL_IOCTL_IDC_CONNECT: u32MagicCookie=%#x uReqVersion=%#x uMinVersion=%#x uReserved=%#x\n",
+             pReq->u.In.u32MagicCookie, pReq->u.In.uReqVersion, pReq->u.In.uMinVersion, pReq->u.In.uReserved));
+    Assert(pSession != NULL);
+    RT_NOREF(pDevExt);
+
+    /*
+     * Input validation.
+     */
+    if (pReq->u.In.u32MagicCookie == VBGL_IOCTL_IDC_CONNECT_MAGIC_COOKIE)
+    {
+        if (   pReq->u.In.uMinVersion <= pReq->u.In.uReqVersion
+            && RT_HI_U16(pReq->u.In.uMinVersion) == RT_HI_U16(pReq->u.In.uReqVersion))
+        {
+            /*
+             * Match the version.
+             * The current logic is very simple, match the major interface version.
+             */
+            if (   pReq->u.In.uMinVersion <= VBGL_IOC_VERSION
+                && RT_HI_U16(pReq->u.In.uMinVersion) == RT_HI_U16(VBGL_IOC_VERSION))
+            {
+                pReq->u.Out.pvSession       = pSession;
+                pReq->u.Out.uSessionVersion = VBGL_IOC_VERSION;
+                pReq->u.Out.uDriverVersion  = VBGL_IOC_VERSION;
+                pReq->u.Out.uDriverRevision = VBOX_SVN_REV;
+                pReq->u.Out.uReserved1      = 0;
+                pReq->u.Out.pvReserved2     = NULL;
+                return VINF_SUCCESS;
+
+            }
+            LogRel(("VBGL_IOCTL_IDC_CONNECT: Version mismatch. Requested: %#x  Min: %#x  Current: %#x\n",
+                    pReq->u.In.uReqVersion, pReq->u.In.uMinVersion, VBGL_IOC_VERSION));
+            rc = VERR_VERSION_MISMATCH;
+        }
+        else
+        {
+            LogRel(("VBGL_IOCTL_IDC_CONNECT: uMinVersion=%#x uMaxVersion=%#x doesn't match!\n",
+                    pReq->u.In.uMinVersion, pReq->u.In.uReqVersion));
+            rc = VERR_INVALID_PARAMETER;
+        }
+
+        pReq->u.Out.pvSession       = NULL;
+        pReq->u.Out.uSessionVersion = UINT32_MAX;
+        pReq->u.Out.uDriverVersion  = VBGL_IOC_VERSION;
+        pReq->u.Out.uDriverRevision = VBOX_SVN_REV;
+        pReq->u.Out.uReserved1      = 0;
+        pReq->u.Out.pvReserved2     = NULL;
+    }
+    else
+    {
+        LogRel(("VBGL_IOCTL_IDC_CONNECT: u32MagicCookie=%#x expected %#x!\n",
+                pReq->u.In.u32MagicCookie, VBGL_IOCTL_IDC_CONNECT_MAGIC_COOKIE));
+        rc = VERR_INVALID_PARAMETER;
+    }
+    return rc;
+}
+
+
+/**
+ * Counterpart to vgdrvIoCtl_IdcConnect, destroys the session.
+ *
+ * returns IPRT status code.
+ * @param   pDevExt         The device extension.
+ * @param   pSession        The session.
+ * @param   pReq            The request info.
+ */
+static int vgdrvIoCtl_IdcDisconnect(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession, PVBGLIOCIDCDISCONNECT pReq)
+{
+    LogFlow(("VBGL_IOCTL_IDC_DISCONNECT: pvSession=%p vs pSession=%p\n", pReq->u.In.pvSession, pSession));
+    RT_NOREF(pDevExt);
+    Assert(pSession != NULL);
+
+    if (pReq->u.In.pvSession == pSession)
+    {
+        VGDrvCommonCloseSession(pDevExt, pSession);
+        return VINF_SUCCESS;
+    }
+    LogRel(("VBGL_IOCTL_IDC_DISCONNECT: In.pvSession=%p is not equal to pSession=%p!\n", pReq->u.In.pvSession, pSession));
+    return VERR_INVALID_PARAMETER;
+}
+
+
+/**
+ * Return the VMM device I/O info.
+ *
+ * returns IPRT status code.
+ * @param   pDevExt         The device extension.
+ * @param   pInfo           The request info.
+ * @note    Ring-0 only, caller checked.
+ */
+static int vgdrvIoCtl_GetVMMDevIoInfo(PVBOXGUESTDEVEXT pDevExt, PVBGLIOCGETVMMDEVIOINFO pInfo)
+{
+    LogFlow(("VBGL_IOCTL_GET_VMMDEV_IO_INFO\n"));
+
+    pInfo->u.Out.IoPort          = pDevExt->IOPortBase;
+    pInfo->u.Out.pvVmmDevMapping = pDevExt->pVMMDevMemory;
+    pInfo->u.Out.auPadding[0]    = 0;
+#if HC_ARCH_BITS != 32
+    pInfo->u.Out.auPadding[1]    = 0;
+    pInfo->u.Out.auPadding[2]    = 0;
+#endif
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Set the callback for the kernel mouse handler.
+ *
+ * returns IPRT status code.
+ * @param   pDevExt         The device extension.
+ * @param   pNotify         The new callback information.
+ */
+static int vgdrvIoCtl_SetMouseNotifyCallback(PVBOXGUESTDEVEXT pDevExt, PVBGLIOCSETMOUSENOTIFYCALLBACK pNotify)
+{
+    LogFlow(("VBOXGUEST_IOCTL_SET_MOUSE_NOTIFY_CALLBACK: pfnNotify=%p pvUser=%p\n", pNotify->u.In.pfnNotify, pNotify->u.In.pvUser));
+
+#ifdef VBOXGUEST_MOUSE_NOTIFY_CAN_PREEMPT
+    VGDrvNativeSetMouseNotifyCallback(pDevExt, pNotify);
+#else
+    RTSpinlockAcquire(pDevExt->EventSpinlock);
+    pDevExt->pfnMouseNotifyCallback   = pNotify->u.In.pfnNotify;
+    pDevExt->pvMouseNotifyCallbackArg = pNotify->u.In.pvUser;
+    RTSpinlockRelease(pDevExt->EventSpinlock);
+#endif
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Worker vgdrvIoCtl_WaitEvent.
+ *
+ * The caller enters the spinlock, we leave it.
+ *
+ * @returns VINF_SUCCESS if we've left the spinlock and can return immediately.
+ */
+DECLINLINE(int) vbdgCheckWaitEventCondition(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession,
+                                            PVBGLIOCWAITFOREVENTS pInfo, int iEvent, const uint32_t fReqEvents)
+{
+    uint32_t fMatches = pDevExt->f32PendingEvents & fReqEvents;
+    if (fMatches & VBOXGUEST_ACQUIRE_STYLE_EVENTS)
+        fMatches &= vgdrvGetAllowedEventMaskForSession(pDevExt, pSession);
+    if (fMatches || pSession->fPendingCancelWaitEvents)
+    {
+        ASMAtomicAndU32(&pDevExt->f32PendingEvents, ~fMatches);
+        RTSpinlockRelease(pDevExt->EventSpinlock);
+
+        pInfo->u.Out.fEvents = fMatches;
+        if (fReqEvents & ~((uint32_t)1 << iEvent))
+            LogFlow(("VBOXGUEST_IOCTL_WAITEVENT: returns %#x\n", pInfo->u.Out.fEvents));
+        else
+            LogFlow(("VBOXGUEST_IOCTL_WAITEVENT: returns %#x/%d\n", pInfo->u.Out.fEvents, iEvent));
+        pSession->fPendingCancelWaitEvents = false;
+        return VINF_SUCCESS;
+    }
+
+    RTSpinlockRelease(pDevExt->EventSpinlock);
+    return VERR_TIMEOUT;
+}
+
+
+static int vgdrvIoCtl_WaitForEvents(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession,
+                                    PVBGLIOCWAITFOREVENTS pInfo, bool fInterruptible)
+{
+    uint32_t const  cMsTimeout = pInfo->u.In.cMsTimeOut;
+    const uint32_t  fReqEvents = pInfo->u.In.fEvents;
+    uint32_t        fResEvents;
+    int             iEvent;
+    PVBOXGUESTWAIT  pWait;
+    int             rc;
+
+    pInfo->u.Out.fEvents = 0;           /* Note! This overwrites pInfo->u.In.* fields!  */
+
+    /*
+     * Copy and verify the input mask.
+     */
+    iEvent = ASMBitFirstSetU32(fReqEvents) - 1;
+    if (RT_UNLIKELY(iEvent < 0))
+    {
+        LogRel(("VBOXGUEST_IOCTL_WAITEVENT: Invalid input mask %#x!!\n", fReqEvents));
+        return VERR_INVALID_PARAMETER;
+    }
+
+    /*
+     * Check the condition up front, before doing the wait-for-event allocations.
+     */
+    RTSpinlockAcquire(pDevExt->EventSpinlock);
+    rc = vbdgCheckWaitEventCondition(pDevExt, pSession, pInfo, iEvent, fReqEvents);
+    if (rc == VINF_SUCCESS)
+        return rc;
+
+    if (!cMsTimeout)
+    {
+        LogFlow(("VBOXGUEST_IOCTL_WAITEVENT: returns VERR_TIMEOUT\n"));
+        return VERR_TIMEOUT;
+    }
+
+    pWait = vgdrvWaitAlloc(pDevExt, pSession);
+    if (!pWait)
+        return VERR_NO_MEMORY;
+    pWait->fReqEvents = fReqEvents;
+
+    /*
+     * We've got the wait entry now, re-enter the spinlock and check for the condition.
+     * If the wait condition is met, return.
+     * Otherwise enter into the list and go to sleep waiting for the ISR to signal us.
+     */
+    RTSpinlockAcquire(pDevExt->EventSpinlock);
+    RTListAppend(&pDevExt->WaitList, &pWait->ListNode);
+    rc = vbdgCheckWaitEventCondition(pDevExt, pSession, pInfo, iEvent, fReqEvents);
+    if (rc == VINF_SUCCESS)
+    {
+        vgdrvWaitFreeUnlocked(pDevExt, pWait);
+        return rc;
+    }
+
+    if (fInterruptible)
+        rc = RTSemEventMultiWaitNoResume(pWait->Event, cMsTimeout == UINT32_MAX ? RT_INDEFINITE_WAIT : cMsTimeout);
+    else
+        rc = RTSemEventMultiWait(pWait->Event, cMsTimeout == UINT32_MAX ? RT_INDEFINITE_WAIT : cMsTimeout);
+
+    /*
+     * There is one special case here and that's when the semaphore is
+     * destroyed upon device driver unload. This shouldn't happen of course,
+     * but in case it does, just get out of here ASAP.
+     */
+    if (rc == VERR_SEM_DESTROYED)
+        return rc;
+
+    /*
+     * Unlink the wait item and dispose of it.
+     */
+    RTSpinlockAcquire(pDevExt->EventSpinlock);
+    fResEvents = pWait->fResEvents;
+    vgdrvWaitFreeLocked(pDevExt, pWait);
+    RTSpinlockRelease(pDevExt->EventSpinlock);
+
+    /*
+     * Now deal with the return code.
+     */
+    if (   fResEvents
+        && fResEvents != UINT32_MAX)
+    {
+        pInfo->u.Out.fEvents = fResEvents;
+        if (fReqEvents & ~((uint32_t)1 << iEvent))
+            LogFlow(("VBOXGUEST_IOCTL_WAITEVENT: returns %#x\n", pInfo->u.Out.fEvents));
+        else
+            LogFlow(("VBOXGUEST_IOCTL_WAITEVENT: returns %#x/%d\n", pInfo->u.Out.fEvents, iEvent));
+        rc = VINF_SUCCESS;
+    }
+    else if (   fResEvents == UINT32_MAX
+             || rc == VERR_INTERRUPTED)
+    {
+        rc = VERR_INTERRUPTED;
+        LogFlow(("VBOXGUEST_IOCTL_WAITEVENT: returns VERR_INTERRUPTED\n"));
+    }
+    else if (rc == VERR_TIMEOUT)
+        LogFlow(("VBOXGUEST_IOCTL_WAITEVENT: returns VERR_TIMEOUT (2)\n"));
+    else
+    {
+        if (RT_SUCCESS(rc))
+        {
+            LogRelMax(32, ("VBOXGUEST_IOCTL_WAITEVENT: returns %Rrc but no events!\n", rc));
+            rc = VERR_INTERNAL_ERROR;
+        }
+        LogFlow(("VBOXGUEST_IOCTL_WAITEVENT: returns %Rrc\n", rc));
+    }
+
+    return rc;
+}
+
+
+/** @todo the semantics of this IoCtl have been tightened, so that no calls to
+ *  VBOXGUEST_IOCTL_WAITEVENT are allowed in a session after it has been
+ *  called.  Change the code to make calls to VBOXGUEST_IOCTL_WAITEVENT made
+ *  after that to return VERR_INTERRUPTED or something appropriate. */
+static int vgdrvIoCtl_CancelAllWaitEvents(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession)
+{
+    PVBOXGUESTWAIT          pWait;
+    PVBOXGUESTWAIT          pSafe;
+    int                     rc = 0;
+    /* Was as least one WAITEVENT in process for this session?  If not we
+     * set a flag that the next call should be interrupted immediately.  This
+     * is needed so that a user thread can reliably interrupt another one in a
+     * WAITEVENT loop. */
+    bool                    fCancelledOne = false;
+
+    LogFlow(("VBOXGUEST_IOCTL_CANCEL_ALL_WAITEVENTS\n"));
+
+    /*
+     * Walk the event list and wake up anyone with a matching session.
+     */
+    RTSpinlockAcquire(pDevExt->EventSpinlock);
+    RTListForEachSafe(&pDevExt->WaitList, pWait, pSafe, VBOXGUESTWAIT, ListNode)
+    {
+        if (pWait->pSession == pSession)
+        {
+            fCancelledOne = true;
+            pWait->fResEvents = UINT32_MAX;
+            RTListNodeRemove(&pWait->ListNode);
+#ifdef VBOXGUEST_USE_DEFERRED_WAKE_UP
+            RTListAppend(&pDevExt->WakeUpList, &pWait->ListNode);
+#else
+            rc |= RTSemEventMultiSignal(pWait->Event);
+            RTListAppend(&pDevExt->WokenUpList, &pWait->ListNode);
+#endif
+        }
+    }
+    if (!fCancelledOne)
+        pSession->fPendingCancelWaitEvents = true;
+    RTSpinlockRelease(pDevExt->EventSpinlock);
+    Assert(rc == 0);
+    NOREF(rc);
+
+#ifdef VBOXGUEST_USE_DEFERRED_WAKE_UP
+    VGDrvCommonWaitDoWakeUps(pDevExt);
+#endif
+
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Checks if the VMM request is allowed in the context of the given session.
+ *
+ * @returns VINF_SUCCESS or VERR_PERMISSION_DENIED.
+ * @param   pDevExt             The device extension.
+ * @param   pSession            The calling session.
+ * @param   enmType             The request type.
+ * @param   pReqHdr             The request.
+ */
+static int vgdrvCheckIfVmmReqIsAllowed(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession, VMMDevRequestType enmType,
+                                       VMMDevRequestHeader const *pReqHdr)
+{
+    /*
+     * Categorize the request being made.
+     */
+    /** @todo This need quite some more work! */
+    enum
+    {
+        kLevel_Invalid, kLevel_NoOne, kLevel_OnlyVBoxGuest, kLevel_OnlyKernel, kLevel_TrustedUsers, kLevel_AllUsers
+    } enmRequired;
+    RT_NOREF1(pDevExt);
+
+    switch (enmType)
+    {
+        /*
+         * Deny access to anything we don't know or provide specialized I/O controls for.
+         */
+#ifdef VBOX_WITH_HGCM
+        case VMMDevReq_HGCMConnect:
+        case VMMDevReq_HGCMDisconnect:
+# ifdef VBOX_WITH_64_BITS_GUESTS
+        case VMMDevReq_HGCMCall64:
+# endif
+        case VMMDevReq_HGCMCall32:
+        case VMMDevReq_HGCMCancel:
+        case VMMDevReq_HGCMCancel2:
+#endif /* VBOX_WITH_HGCM */
+        case VMMDevReq_SetGuestCapabilities:
+        default:
+            enmRequired = kLevel_NoOne;
+            break;
+
+        /*
+         * There are a few things only this driver can do (and it doesn't use
+         * the VMMRequst I/O control route anyway, but whatever).
+         */
+        case VMMDevReq_ReportGuestInfo:
+        case VMMDevReq_ReportGuestInfo2:
+        case VMMDevReq_GetHypervisorInfo:
+        case VMMDevReq_SetHypervisorInfo:
+        case VMMDevReq_RegisterPatchMemory:
+        case VMMDevReq_DeregisterPatchMemory:
+        case VMMDevReq_GetMemBalloonChangeRequest:
+        case VMMDevReq_ChangeMemBalloon:
+            enmRequired = kLevel_OnlyVBoxGuest;
+            break;
+
+        /*
+         * Trusted users apps only.
+         */
+        case VMMDevReq_QueryCredentials:
+        case VMMDevReq_ReportCredentialsJudgement:
+        case VMMDevReq_RegisterSharedModule:
+        case VMMDevReq_UnregisterSharedModule:
+        case VMMDevReq_WriteCoreDump:
+        case VMMDevReq_GetCpuHotPlugRequest:
+        case VMMDevReq_SetCpuHotPlugStatus:
+        case VMMDevReq_CheckSharedModules:
+        case VMMDevReq_GetPageSharingStatus:
+        case VMMDevReq_DebugIsPageShared:
+        case VMMDevReq_ReportGuestStats:
+        case VMMDevReq_ReportGuestUserState:
+        case VMMDevReq_GetStatisticsChangeRequest:
+            enmRequired = kLevel_TrustedUsers;
+            break;
+
+        /*
+         * Anyone.
+         */
+        case VMMDevReq_GetMouseStatus:
+        case VMMDevReq_SetMouseStatus:
+        case VMMDevReq_SetPointerShape:
+        case VMMDevReq_GetHostVersion:
+        case VMMDevReq_Idle:
+        case VMMDevReq_GetHostTime:
+        case VMMDevReq_SetPowerStatus:
+        case VMMDevReq_AcknowledgeEvents:
+        case VMMDevReq_CtlGuestFilterMask:
+        case VMMDevReq_ReportGuestStatus:
+        case VMMDevReq_GetDisplayChangeRequest:
+        case VMMDevReq_VideoModeSupported:
+        case VMMDevReq_GetHeightReduction:
+        case VMMDevReq_GetDisplayChangeRequest2:
+        case VMMDevReq_VideoModeSupported2:
+        case VMMDevReq_VideoAccelEnable:
+        case VMMDevReq_VideoAccelFlush:
+        case VMMDevReq_VideoSetVisibleRegion:
+        case VMMDevReq_VideoUpdateMonitorPositions:
+        case VMMDevReq_GetDisplayChangeRequestEx:
+        case VMMDevReq_GetDisplayChangeRequestMulti:
+        case VMMDevReq_GetSeamlessChangeRequest:
+        case VMMDevReq_GetVRDPChangeRequest:
+        case VMMDevReq_LogString:
+        case VMMDevReq_GetSessionId:
+            enmRequired = kLevel_AllUsers;
+            break;
+
+        /*
+         * Depends on the request parameters...
+         */
+        /** @todo this have to be changed into an I/O control and the facilities
+         *        tracked in the session so they can automatically be failed when the
+         *        session terminates without reporting the new status.
+         *
+         *  The information presented by IGuest is not reliable without this! */
+        case VMMDevReq_ReportGuestCapabilities:
+            switch (((VMMDevReportGuestStatus const *)pReqHdr)->guestStatus.facility)
+            {
+                case VBoxGuestFacilityType_All:
+                case VBoxGuestFacilityType_VBoxGuestDriver:
+                    enmRequired = kLevel_OnlyVBoxGuest;
+                    break;
+                case VBoxGuestFacilityType_VBoxService:
+                    enmRequired = kLevel_TrustedUsers;
+                    break;
+                case VBoxGuestFacilityType_VBoxTrayClient:
+                case VBoxGuestFacilityType_Seamless:
+                case VBoxGuestFacilityType_Graphics:
+                default:
+                    enmRequired = kLevel_AllUsers;
+                    break;
+            }
+            break;
+    }
+
+    /*
+     * Check against the session.
+     */
+    switch (enmRequired)
+    {
+        default:
+        case kLevel_NoOne:
+            break;
+        case kLevel_OnlyVBoxGuest:
+        case kLevel_OnlyKernel:
+            if (pSession->R0Process == NIL_RTR0PROCESS)
+                return VINF_SUCCESS;
+            break;
+        case kLevel_TrustedUsers:
+            if (pSession->fUserSession)
+                break;
+            RT_FALL_THRU();
+        case kLevel_AllUsers:
+            return VINF_SUCCESS;
+    }
+
+    return VERR_PERMISSION_DENIED;
+}
+
+static int vgdrvIoCtl_VMMDevRequest(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession,
+                                    VMMDevRequestHeader *pReqHdr, size_t cbData)
+{
+    int                     rc;
+    VMMDevRequestHeader    *pReqCopy;
+
+    /*
+     * Validate the header and request size.
+     */
+    const VMMDevRequestType enmType   = pReqHdr->requestType;
+    const uint32_t          cbReq     = pReqHdr->size;
+    const uint32_t          cbMinSize = (uint32_t)vmmdevGetRequestSize(enmType);
+
+    LogFlow(("VBOXGUEST_IOCTL_VMMREQUEST: type %d\n", pReqHdr->requestType));
+
+    if (cbReq < cbMinSize)
+    {
+        LogRel(("VBOXGUEST_IOCTL_VMMREQUEST: invalid hdr size %#x, expected >= %#x; type=%#x!!\n",
+                cbReq, cbMinSize, enmType));
+        return VERR_INVALID_PARAMETER;
+    }
+    if (cbReq > cbData)
+    {
+        LogRel(("VBOXGUEST_IOCTL_VMMREQUEST: invalid size %#x, expected >= %#x (hdr); type=%#x!!\n",
+                cbData, cbReq, enmType));
+        return VERR_INVALID_PARAMETER;
+    }
+    rc = VbglGR0Verify(pReqHdr, cbData);
+    if (RT_FAILURE(rc))
+    {
+        Log(("VBOXGUEST_IOCTL_VMMREQUEST: invalid header: size %#x, expected >= %#x (hdr); type=%#x; rc=%Rrc!!\n",
+             cbData, cbReq, enmType, rc));
+        return rc;
+    }
+
+    rc = vgdrvCheckIfVmmReqIsAllowed(pDevExt, pSession, enmType, pReqHdr);
+    if (RT_FAILURE(rc))
+    {
+        Log(("VBOXGUEST_IOCTL_VMMREQUEST: Operation not allowed! type=%#x rc=%Rrc\n", enmType, rc));
+        return rc;
+    }
+
+    /*
+     * Make a copy of the request in the physical memory heap so
+     * the VBoxGuestLibrary can more easily deal with the request.
+     * (This is really a waste of time since the OS or the OS specific
+     * code has already buffered or locked the input/output buffer, but
+     * it does makes things a bit simpler wrt to phys address.)
+     */
+    rc = VbglR0GRAlloc(&pReqCopy, cbReq, enmType);
+    if (RT_FAILURE(rc))
+    {
+        Log(("VBOXGUEST_IOCTL_VMMREQUEST: failed to allocate %u (%#x) bytes to cache the request. rc=%Rrc!!\n",
+             cbReq, cbReq, rc));
+        return rc;
+    }
+    memcpy(pReqCopy, pReqHdr, cbReq);
+    Assert(pReqCopy->reserved1 == cbReq);
+    pReqCopy->reserved1 = 0;            /* VGDrvCommonIoCtl or caller sets cbOut, so clear it. */
+    pReqCopy->fRequestor = pSession->fRequestor;
+
+    if (enmType == VMMDevReq_GetMouseStatus) /* clear poll condition. */
+        pSession->u32MousePosChangedSeq = ASMAtomicUoReadU32(&pDevExt->u32MousePosChangedSeq);
+
+    rc = VbglR0GRPerform(pReqCopy);
+    if (   RT_SUCCESS(rc)
+        && RT_SUCCESS(pReqCopy->rc))
+    {
+        Assert(rc != VINF_HGCM_ASYNC_EXECUTE);
+        Assert(pReqCopy->rc != VINF_HGCM_ASYNC_EXECUTE);
+
+        memcpy(pReqHdr, pReqCopy, cbReq);
+        pReqHdr->reserved1 = cbReq; /* preserve cbOut */
+    }
+    else if (RT_FAILURE(rc))
+        Log(("VBOXGUEST_IOCTL_VMMREQUEST: VbglR0GRPerform - rc=%Rrc!\n", rc));
+    else
+    {
+        Log(("VBOXGUEST_IOCTL_VMMREQUEST: request execution failed; VMMDev rc=%Rrc!\n", pReqCopy->rc));
+        rc = pReqCopy->rc;
+    }
+
+    VbglR0GRFree(pReqCopy);
+    return rc;
+}
+
+
+#ifdef VBOX_WITH_HGCM
+
+AssertCompile(RT_INDEFINITE_WAIT == (uint32_t)RT_INDEFINITE_WAIT); /* assumed by code below */
+
+/** Worker for vgdrvHgcmAsyncWaitCallback*. */
+static int vgdrvHgcmAsyncWaitCallbackWorker(VMMDevHGCMRequestHeader volatile *pHdr, PVBOXGUESTDEVEXT pDevExt,
+                                            bool fInterruptible, uint32_t cMillies)
+{
+    int rc;
+
+    /*
+     * Check to see if the condition was met by the time we got here.
+     *
+     * We create a simple poll loop here for dealing with out-of-memory
+     * conditions since the caller isn't necessarily able to deal with
+     * us returning too early.
+     */
+    PVBOXGUESTWAIT pWait;
+    for (;;)
+    {
+        RTSpinlockAcquire(pDevExt->EventSpinlock);
+        if ((pHdr->fu32Flags & VBOX_HGCM_REQ_DONE) != 0)
+        {
+            RTSpinlockRelease(pDevExt->EventSpinlock);
+            return VINF_SUCCESS;
+        }
+        RTSpinlockRelease(pDevExt->EventSpinlock);
+
+        pWait = vgdrvWaitAlloc(pDevExt, NULL);
+        if (pWait)
+            break;
+        if (fInterruptible)
+            return VERR_INTERRUPTED;
+        RTThreadSleep(1);
+    }
+    pWait->fReqEvents = VMMDEV_EVENT_HGCM;
+    pWait->pHGCMReq = pHdr;
+
+    /*
+     * Re-enter the spinlock and re-check for the condition.
+     * If the condition is met, return.
+     * Otherwise link us into the HGCM wait list and go to sleep.
+     */
+    RTSpinlockAcquire(pDevExt->EventSpinlock);
+    RTListAppend(&pDevExt->HGCMWaitList, &pWait->ListNode);
+    if ((pHdr->fu32Flags & VBOX_HGCM_REQ_DONE) != 0)
+    {
+        vgdrvWaitFreeLocked(pDevExt, pWait);
+        RTSpinlockRelease(pDevExt->EventSpinlock);
+        return VINF_SUCCESS;
+    }
+    RTSpinlockRelease(pDevExt->EventSpinlock);
+
+    if (fInterruptible)
+        rc = RTSemEventMultiWaitNoResume(pWait->Event, cMillies);
+    else
+        rc = RTSemEventMultiWait(pWait->Event, cMillies);
+    if (rc == VERR_SEM_DESTROYED)
+        return rc;
+
+    /*
+     * Unlink, free and return.
+     */
+    if (   RT_FAILURE(rc)
+        && rc != VERR_TIMEOUT
+        && (   !fInterruptible
+            || rc != VERR_INTERRUPTED))
+        LogRel(("vgdrvHgcmAsyncWaitCallback: wait failed! %Rrc\n", rc));
+
+    vgdrvWaitFreeUnlocked(pDevExt, pWait);
+    return rc;
+}
+
+
+/**
+ * This is a callback for dealing with async waits.
+ *
+ * It operates in a manner similar to vgdrvIoCtl_WaitEvent.
+ */
+static DECLCALLBACK(int) vgdrvHgcmAsyncWaitCallback(VMMDevHGCMRequestHeader *pHdr, void *pvUser, uint32_t u32User)
+{
+    PVBOXGUESTDEVEXT pDevExt = (PVBOXGUESTDEVEXT)pvUser;
+    LogFlow(("vgdrvHgcmAsyncWaitCallback: requestType=%d\n", pHdr->header.requestType));
+    return vgdrvHgcmAsyncWaitCallbackWorker((VMMDevHGCMRequestHeader volatile *)pHdr, pDevExt,
+                                            false /* fInterruptible */, u32User  /* cMillies */);
+}
+
+
+/**
+ * This is a callback for dealing with async waits with a timeout.
+ *
+ * It operates in a manner similar to vgdrvIoCtl_WaitEvent.
+ */
+static DECLCALLBACK(int) vgdrvHgcmAsyncWaitCallbackInterruptible(VMMDevHGCMRequestHeader *pHdr, void *pvUser, uint32_t u32User)
+{
+    PVBOXGUESTDEVEXT pDevExt = (PVBOXGUESTDEVEXT)pvUser;
+    LogFlow(("vgdrvHgcmAsyncWaitCallbackInterruptible: requestType=%d\n", pHdr->header.requestType));
+    return vgdrvHgcmAsyncWaitCallbackWorker((VMMDevHGCMRequestHeader volatile *)pHdr, pDevExt,
+                                            true /* fInterruptible */, u32User /* cMillies */);
+}
+
+
+static int vgdrvIoCtl_HGCMConnect(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession, PVBGLIOCHGCMCONNECT pInfo)
+{
+    int rc;
+    HGCMCLIENTID idClient = 0;
+
+    /*
+     * The VbglHGCMConnect call will invoke the callback if the HGCM
+     * call is performed in an ASYNC fashion. The function is not able
+     * to deal with cancelled requests.
+     */
+    Log(("VBOXGUEST_IOCTL_HGCM_CONNECT: %.128s\n",
+         pInfo->u.In.Loc.type == VMMDevHGCMLoc_LocalHost || pInfo->u.In.Loc.type == VMMDevHGCMLoc_LocalHost_Existing
+         ? pInfo->u.In.Loc.u.host.achName : "<not local host>"));
+
+    rc = VbglR0HGCMInternalConnect(&pInfo->u.In.Loc, pSession->fRequestor, &idClient,
+                                   vgdrvHgcmAsyncWaitCallback, pDevExt, RT_INDEFINITE_WAIT);
+    Log(("VBOXGUEST_IOCTL_HGCM_CONNECT: idClient=%RX32 (rc=%Rrc)\n", idClient, rc));
+    if (RT_SUCCESS(rc))
+    {
+        /*
+         * Append the client id to the client id table.
+         * If the table has somehow become filled up, we'll disconnect the session.
+         */
+        unsigned i;
+        RTSpinlockAcquire(pDevExt->SessionSpinlock);
+        for (i = 0; i < RT_ELEMENTS(pSession->aHGCMClientIds); i++)
+            if (!pSession->aHGCMClientIds[i])
+            {
+                pSession->aHGCMClientIds[i] = idClient;
+                break;
+            }
+        RTSpinlockRelease(pDevExt->SessionSpinlock);
+        if (i >= RT_ELEMENTS(pSession->aHGCMClientIds))
+        {
+            LogRelMax(32, ("VBOXGUEST_IOCTL_HGCM_CONNECT: too many HGCMConnect calls for one session!\n"));
+            VbglR0HGCMInternalDisconnect(idClient, pSession->fRequestor, vgdrvHgcmAsyncWaitCallback, pDevExt, RT_INDEFINITE_WAIT);
+
+            pInfo->u.Out.idClient = 0;
+            return VERR_TOO_MANY_OPEN_FILES;
+        }
+    }
+    pInfo->u.Out.idClient = idClient;
+    return rc;
+}
+
+
+static int vgdrvIoCtl_HGCMDisconnect(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession, PVBGLIOCHGCMDISCONNECT pInfo)
+{
+    /*
+     * Validate the client id and invalidate its entry while we're in the call.
+     */
+    int             rc;
+    const uint32_t  idClient = pInfo->u.In.idClient;
+    unsigned        i;
+    RTSpinlockAcquire(pDevExt->SessionSpinlock);
+    for (i = 0; i < RT_ELEMENTS(pSession->aHGCMClientIds); i++)
+        if (pSession->aHGCMClientIds[i] == idClient)
+        {
+            pSession->aHGCMClientIds[i] = UINT32_MAX;
+            break;
+        }
+    RTSpinlockRelease(pDevExt->SessionSpinlock);
+    if (i >= RT_ELEMENTS(pSession->aHGCMClientIds))
+    {
+        LogRelMax(32, ("VBOXGUEST_IOCTL_HGCM_DISCONNECT: idClient=%RX32\n", idClient));
+        return VERR_INVALID_HANDLE;
+    }
+
+    /*
+     * The VbglHGCMConnect call will invoke the callback if the HGCM
+     * call is performed in an ASYNC fashion. The function is not able
+     * to deal with cancelled requests.
+     */
+    Log(("VBOXGUEST_IOCTL_HGCM_DISCONNECT: idClient=%RX32\n", idClient));
+    rc = VbglR0HGCMInternalDisconnect(idClient, pSession->fRequestor, vgdrvHgcmAsyncWaitCallback, pDevExt, RT_INDEFINITE_WAIT);
+    LogFlow(("VBOXGUEST_IOCTL_HGCM_DISCONNECT: rc=%Rrc\n", rc));
+
+    /* Update the client id array according to the result. */
+    RTSpinlockAcquire(pDevExt->SessionSpinlock);
+    if (pSession->aHGCMClientIds[i] == UINT32_MAX)
+        pSession->aHGCMClientIds[i] = RT_SUCCESS(rc) ? 0 : idClient;
+    RTSpinlockRelease(pDevExt->SessionSpinlock);
+
+    return rc;
+}
+
+
+static int vgdrvIoCtl_HGCMCallInner(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession, PVBGLIOCHGCMCALL pInfo,
+                                    uint32_t cMillies, bool fInterruptible, bool f32bit, bool fUserData,
+                                    size_t cbExtra, size_t cbData)
+{
+    const uint32_t  u32ClientId = pInfo->u32ClientID;
+    uint32_t        fFlags;
+    size_t          cbActual;
+    unsigned        i;
+    int             rc;
+
+    /*
+     * Some more validations.
+     */
+    if (RT_LIKELY(pInfo->cParms <= VMMDEV_MAX_HGCM_PARMS)) /* (Just make sure it doesn't overflow the next check.) */
+    { /* likely */}
+    else
+    {
+        LogRel(("VBOXGUEST_IOCTL_HGCM_CALL: cParm=%RX32 is not sane\n", pInfo->cParms));
+        return VERR_INVALID_PARAMETER;
+    }
+
+    cbActual = cbExtra + sizeof(*pInfo);
+#ifdef RT_ARCH_AMD64
+    if (f32bit)
+        cbActual += pInfo->cParms * sizeof(HGCMFunctionParameter32);
+    else
+#endif
+        cbActual += pInfo->cParms * sizeof(HGCMFunctionParameter);
+    if (RT_LIKELY(cbData >= cbActual))
+    { /* likely */}
+    else
+    {
+        LogRel(("VBOXGUEST_IOCTL_HGCM_CALL: cbData=%#zx (%zu) required size is %#zx (%zu)\n",
+               cbData, cbData, cbActual, cbActual));
+        return VERR_INVALID_PARAMETER;
+    }
+    pInfo->Hdr.cbOut = (uint32_t)cbActual;
+
+    /*
+     * Validate the client id.
+     */
+    RTSpinlockAcquire(pDevExt->SessionSpinlock);
+    for (i = 0; i < RT_ELEMENTS(pSession->aHGCMClientIds); i++)
+        if (pSession->aHGCMClientIds[i] == u32ClientId)
+            break;
+    RTSpinlockRelease(pDevExt->SessionSpinlock);
+    if (RT_LIKELY(i < RT_ELEMENTS(pSession->aHGCMClientIds)))
+    { /* likely */}
+    else
+    {
+        LogRelMax(32, ("VBOXGUEST_IOCTL_HGCM_CALL: Invalid handle. u32Client=%RX32\n", u32ClientId));
+        return VERR_INVALID_HANDLE;
+    }
+
+    /*
+     * The VbglHGCMCall call will invoke the callback if the HGCM
+     * call is performed in an ASYNC fashion. This function can
+     * deal with cancelled requests, so we let user more requests
+     * be interruptible (should add a flag for this later I guess).
+     */
+    LogFlow(("VBOXGUEST_IOCTL_HGCM_CALL: u32Client=%RX32\n", pInfo->u32ClientID));
+    fFlags = !fUserData && pSession->R0Process == NIL_RTR0PROCESS ? VBGLR0_HGCMCALL_F_KERNEL : VBGLR0_HGCMCALL_F_USER;
+    uint32_t cbInfo = (uint32_t)(cbData - cbExtra);
+#ifdef RT_ARCH_AMD64
+    if (f32bit)
+    {
+        if (fInterruptible)
+            rc = VbglR0HGCMInternalCall32(pInfo, cbInfo, fFlags, pSession->fRequestor,
+                                          vgdrvHgcmAsyncWaitCallbackInterruptible, pDevExt, cMillies);
+        else
+            rc = VbglR0HGCMInternalCall32(pInfo, cbInfo, fFlags, pSession->fRequestor,
+                                          vgdrvHgcmAsyncWaitCallback, pDevExt, cMillies);
+    }
+    else
+#endif
+    {
+        if (fInterruptible)
+            rc = VbglR0HGCMInternalCall(pInfo, cbInfo, fFlags, pSession->fRequestor,
+                                        vgdrvHgcmAsyncWaitCallbackInterruptible, pDevExt, cMillies);
+        else
+            rc = VbglR0HGCMInternalCall(pInfo, cbInfo, fFlags, pSession->fRequestor,
+                                        vgdrvHgcmAsyncWaitCallback, pDevExt, cMillies);
+    }
+    if (RT_SUCCESS(rc))
+    {
+        rc = pInfo->Hdr.rc;
+        LogFlow(("VBOXGUEST_IOCTL_HGCM_CALL: result=%Rrc\n", rc));
+    }
+    else
+    {
+        if (   rc != VERR_INTERRUPTED
+            && rc != VERR_TIMEOUT)
+            LogRelMax(32, ("VBOXGUEST_IOCTL_HGCM_CALL: %s Failed. rc=%Rrc (Hdr.rc=%Rrc).\n", f32bit ? "32" : "64", rc, pInfo->Hdr.rc));
+        else
+            Log(("VBOXGUEST_IOCTL_HGCM_CALL: %s Failed. rc=%Rrc (Hdr.rc=%Rrc).\n", f32bit ? "32" : "64", rc, pInfo->Hdr.rc));
+    }
+    return rc;
+}
+
+
+static int vgdrvIoCtl_HGCMCallWrapper(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession, PVBGLIOCHGCMCALL pInfo,
+                                      bool f32bit, bool fUserData, size_t cbData)
+{
+    return vgdrvIoCtl_HGCMCallInner(pDevExt, pSession, pInfo, pInfo->cMsTimeout,
+                                    pInfo->fInterruptible || pSession->R0Process != NIL_RTR0PROCESS,
+                                    f32bit, fUserData, 0 /*cbExtra*/, cbData);
+}
+
+
+/**
+ * Handles a fast HGCM call from another driver.
+ *
+ * The driver has provided a fully assembled HGCM call request and all we need
+ * to do is send it to the host and do the wait processing.
+ *
+ * @returns VBox status code of the request submission part.
+ * @param   pDevExt     The device extension.
+ * @param   pCallReq    The call request.
+ */
+static int vgdrvIoCtl_HGCMFastCall(PVBOXGUESTDEVEXT pDevExt, VBGLIOCIDCHGCMFASTCALL volatile *pCallReq)
+{
+    VMMDevHGCMCall volatile *pHgcmCall = (VMMDevHGCMCall volatile *)(pCallReq + 1);
+    int rc;
+
+    /*
+     * Check out the physical address.
+     */
+    Assert((pCallReq->GCPhysReq & PAGE_OFFSET_MASK) == ((uintptr_t)pHgcmCall & PAGE_OFFSET_MASK));
+
+    AssertReturn(!pCallReq->fInterruptible, VERR_NOT_IMPLEMENTED);
+
+    /*
+     * Submit the request.
+     */
+    Log(("vgdrvIoCtl_HGCMFastCall -> host\n"));
+    ASMOutU32(pDevExt->IOPortBase + VMMDEV_PORT_OFF_REQUEST, (uint32_t)pCallReq->GCPhysReq);
+
+    /* Make the compiler aware that the host has changed memory. */
+    ASMCompilerBarrier();
+
+    rc = pHgcmCall->header.header.rc;
+    Log(("vgdrvIoCtl_HGCMFastCall -> %Rrc (header rc=%Rrc)\n", rc, pHgcmCall->header.result));
+
+    /*
+     * The host is likely to engage in asynchronous execution of HGCM, unless it fails.
+     */
+    if (rc == VINF_HGCM_ASYNC_EXECUTE)
+    {
+        rc = vgdrvHgcmAsyncWaitCallbackWorker(&pHgcmCall->header, pDevExt, false /* fInterruptible */, RT_INDEFINITE_WAIT);
+        if (pHgcmCall->header.fu32Flags & VBOX_HGCM_REQ_DONE)
+        {
+            Assert(!(pHgcmCall->header.fu32Flags & VBOX_HGCM_REQ_CANCELLED));
+            rc = VINF_SUCCESS;
+        }
+        else
+        {
+            /*
+             * Timeout and interrupt scenarios are messy and requires
+             * cancelation, so implement later.
+             */
+            AssertReleaseMsgFailed(("rc=%Rrc\n", rc));
+        }
+    }
+    else
+        Assert((pHgcmCall->header.fu32Flags & VBOX_HGCM_REQ_DONE) || RT_FAILURE_NP(rc));
+
+    Log(("vgdrvIoCtl_HGCMFastCall: rc=%Rrc result=%Rrc fu32Flags=%#x\n", rc, pHgcmCall->header.result, pHgcmCall->header.fu32Flags));
+    return rc;
+
+}
+
+#endif /* VBOX_WITH_HGCM */
+
+/**
+ * Handle VBGL_IOCTL_CHECK_BALLOON from R3.
+ *
+ * Ask the host for the size of the balloon and try to set it accordingly.  If
+ * this approach fails because it's not supported, return with fHandleInR3 set
+ * and let the user land supply memory we can lock via the other ioctl.
+ *
+ * @returns VBox status code.
+ *
+ * @param   pDevExt             The device extension.
+ * @param   pSession            The session.
+ * @param   pInfo               The output buffer.
+ */
+static int vgdrvIoCtl_CheckMemoryBalloon(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession, PVBGLIOCCHECKBALLOON pInfo)
+{
+    VMMDevGetMemBalloonChangeRequest *pReq;
+    int rc;
+
+    LogFlow(("VBGL_IOCTL_CHECK_BALLOON:\n"));
+    rc = RTSemFastMutexRequest(pDevExt->MemBalloon.hMtx);
+    AssertRCReturn(rc, rc);
+
+    /*
+     * The first user trying to query/change the balloon becomes the
+     * owner and owns it until the session is closed (vgdrvCloseMemBalloon).
+     */
+    if (   pDevExt->MemBalloon.pOwner != pSession
+        && pDevExt->MemBalloon.pOwner == NULL)
+        pDevExt->MemBalloon.pOwner = pSession;
+
+    if (pDevExt->MemBalloon.pOwner == pSession)
+    {
+        /*
+         * This is a response to that event. Setting this bit means that
+         * we request the value from the host and change the guest memory
+         * balloon according to this value.
+         */
+        rc = VbglR0GRAlloc((VMMDevRequestHeader **)&pReq, sizeof(VMMDevGetMemBalloonChangeRequest), VMMDevReq_GetMemBalloonChangeRequest);
+        if (RT_SUCCESS(rc))
+        {
+            pReq->header.fRequestor = pSession->fRequestor;
+            pReq->eventAck = VMMDEV_EVENT_BALLOON_CHANGE_REQUEST;
+            rc = VbglR0GRPerform(&pReq->header);
+            if (RT_SUCCESS(rc))
+            {
+                Assert(pDevExt->MemBalloon.cMaxChunks == pReq->cPhysMemChunks || pDevExt->MemBalloon.cMaxChunks == 0);
+                pDevExt->MemBalloon.cMaxChunks = pReq->cPhysMemChunks;
+
+                pInfo->u.Out.cBalloonChunks = pReq->cBalloonChunks;
+                pInfo->u.Out.fHandleInR3    = false;
+                pInfo->u.Out.afPadding[0]   = false;
+                pInfo->u.Out.afPadding[1]   = false;
+                pInfo->u.Out.afPadding[2]   = false;
+
+                rc = vgdrvSetBalloonSizeKernel(pDevExt, pReq->cBalloonChunks, &pInfo->u.Out.fHandleInR3);
+                /* Ignore various out of memory failures. */
+                if (   rc == VERR_NO_MEMORY
+                    || rc == VERR_NO_PHYS_MEMORY
+                    || rc == VERR_NO_CONT_MEMORY)
+                    rc = VINF_SUCCESS;
+            }
+            else
+                LogRel(("VBGL_IOCTL_CHECK_BALLOON: VbglR0GRPerform failed. rc=%Rrc\n", rc));
+            VbglR0GRFree(&pReq->header);
+        }
+    }
+    else
+        rc = VERR_PERMISSION_DENIED;
+
+    RTSemFastMutexRelease(pDevExt->MemBalloon.hMtx);
+    LogFlow(("VBGL_IOCTL_CHECK_BALLOON returns %Rrc\n", rc));
+    return rc;
+}
+
+
+/**
+ * Handle a request for changing the memory balloon.
+ *
+ * @returns VBox status code.
+ *
+ * @param   pDevExt             The device extention.
+ * @param   pSession            The session.
+ * @param   pInfo               The change request structure (input).
+ */
+static int vgdrvIoCtl_ChangeMemoryBalloon(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession, PVBGLIOCCHANGEBALLOON pInfo)
+{
+    int rc;
+    LogFlow(("VBGL_IOCTL_CHANGE_BALLOON: fInflate=%RTbool u64ChunkAddr=%p\n", pInfo->u.In.fInflate, pInfo->u.In.pvChunk));
+    if (   pInfo->u.In.abPadding[0]
+        || pInfo->u.In.abPadding[1]
+        || pInfo->u.In.abPadding[2]
+        || pInfo->u.In.abPadding[3]
+        || pInfo->u.In.abPadding[4]
+        || pInfo->u.In.abPadding[5]
+        || pInfo->u.In.abPadding[6]
+#if ARCH_BITS == 32
+        || pInfo->u.In.abPadding[7]
+        || pInfo->u.In.abPadding[8]
+        || pInfo->u.In.abPadding[9]
+#endif
+       )
+    {
+        Log(("VBGL_IOCTL_CHANGE_BALLOON: Padding isn't all zero: %.*Rhxs\n", sizeof(pInfo->u.In.abPadding), pInfo->u.In.abPadding));
+        return VERR_INVALID_PARAMETER;
+    }
+
+    rc = RTSemFastMutexRequest(pDevExt->MemBalloon.hMtx);
+    AssertRCReturn(rc, rc);
+
+    if (!pDevExt->MemBalloon.fUseKernelAPI)
+    {
+        /*
+         * The first user trying to query/change the balloon becomes the
+         * owner and owns it until the session is closed (vgdrvCloseMemBalloon).
+         */
+        if (   pDevExt->MemBalloon.pOwner != pSession
+            && pDevExt->MemBalloon.pOwner == NULL)
+            pDevExt->MemBalloon.pOwner = pSession;
+
+        if (pDevExt->MemBalloon.pOwner == pSession)
+            rc = vgdrvSetBalloonSizeFromUser(pDevExt, pSession, pInfo->u.In.pvChunk, pInfo->u.In.fInflate != false);
+        else
+            rc = VERR_PERMISSION_DENIED;
+    }
+    else
+        rc = VERR_PERMISSION_DENIED;
+
+    RTSemFastMutexRelease(pDevExt->MemBalloon.hMtx);
+    return rc;
+}
+
+
+/**
+ * Handle a request for writing a core dump of the guest on the host.
+ *
+ * @returns VBox status code.
+ *
+ * @param   pDevExt             The device extension.
+ * @param   pSession            The session.
+ * @param   pInfo               The output buffer.
+ */
+static int vgdrvIoCtl_WriteCoreDump(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession, PVBGLIOCWRITECOREDUMP pInfo)
+{
+    VMMDevReqWriteCoreDump *pReq = NULL;
+    int rc;
+    LogFlow(("VBOXGUEST_IOCTL_WRITE_CORE_DUMP\n"));
+    RT_NOREF1(pDevExt);
+
+    rc = VbglR0GRAlloc((VMMDevRequestHeader **)&pReq, sizeof(*pReq), VMMDevReq_WriteCoreDump);
+    if (RT_SUCCESS(rc))
+    {
+        pReq->header.fRequestor = pSession->fRequestor;
+        pReq->fFlags = pInfo->u.In.fFlags;
+        rc = VbglR0GRPerform(&pReq->header);
+        if (RT_FAILURE(rc))
+            Log(("VBOXGUEST_IOCTL_WRITE_CORE_DUMP: VbglR0GRPerform failed, rc=%Rrc!\n", rc));
+
+        VbglR0GRFree(&pReq->header);
+    }
+    else
+        Log(("VBOXGUEST_IOCTL_WRITE_CORE_DUMP: failed to allocate %u (%#x) bytes to cache the request. rc=%Rrc!!\n",
+             sizeof(*pReq), sizeof(*pReq), rc));
+    return rc;
+}
+
+
+/**
+ * Guest backdoor logging.
+ *
+ * @returns VBox status code.
+ *
+ * @param   pDevExt             The device extension.
+ * @param   pch                 The log message (need not be NULL terminated).
+ * @param   cbData              Size of the buffer.
+ * @param   fUserSession        Copy of VBOXGUESTSESSION::fUserSession for the
+ *                              call.  True normal user, false root user.
+ */
+static int vgdrvIoCtl_Log(PVBOXGUESTDEVEXT pDevExt, const char *pch, size_t cbData, bool fUserSession)
+{
+    if (pDevExt->fLoggingEnabled)
+        RTLogBackdoorPrintf("%.*s", cbData, pch);
+    else if (!fUserSession)
+        LogRel(("%.*s", cbData, pch));
+    else
+        Log(("%.*s", cbData, pch));
+    return VINF_SUCCESS;
+}
+
+
+/** @name Guest Capabilities, Mouse Status and Event Filter
+ * @{
+ */
+
+/**
+ * Clears a bit usage tracker (init time).
+ *
+ * @param   pTracker            The tracker to clear.
+ */
+static void vgdrvBitUsageTrackerClear(PVBOXGUESTBITUSAGETRACER pTracker)
+{
+    uint32_t iBit;
+    AssertCompile(sizeof(pTracker->acPerBitUsage) == 32 * sizeof(uint32_t));
+
+    for (iBit = 0; iBit < 32; iBit++)
+        pTracker->acPerBitUsage[iBit] = 0;
+    pTracker->fMask = 0;
+}
+
+
+#ifdef VBOX_STRICT
+/**
+ * Checks that pTracker->fMask is correct and that the usage values are within
+ * the valid range.
+ *
+ * @param   pTracker            The tracker.
+ * @param   cMax                Max valid usage value.
+ * @param   pszWhat             Identifies the tracker in assertions.
+ */
+static void vgdrvBitUsageTrackerCheckMask(PCVBOXGUESTBITUSAGETRACER pTracker, uint32_t cMax, const char *pszWhat)
+{
+    uint32_t fMask = 0;
+    uint32_t iBit;
+    AssertCompile(sizeof(pTracker->acPerBitUsage) == 32 * sizeof(uint32_t));
+
+    for (iBit = 0; iBit < 32; iBit++)
+        if (pTracker->acPerBitUsage[iBit])
+        {
+            fMask |= RT_BIT_32(iBit);
+            AssertMsg(pTracker->acPerBitUsage[iBit] <= cMax,
+                      ("%s: acPerBitUsage[%u]=%#x cMax=%#x\n", pszWhat, iBit, pTracker->acPerBitUsage[iBit], cMax));
+        }
+
+    AssertMsg(fMask == pTracker->fMask, ("%s: %#x vs %#x\n", pszWhat, fMask, pTracker->fMask));
+}
+#endif
+
+
+/**
+ * Applies a change to the bit usage tracker.
+ *
+ *
+ * @returns true if the mask changed, false if not.
+ * @param   pTracker            The bit usage tracker.
+ * @param   fChanged            The bits to change.
+ * @param   fPrevious           The previous value of the bits.
+ * @param   cMax                The max valid usage value for assertions.
+ * @param   pszWhat             Identifies the tracker in assertions.
+ */
+static bool vgdrvBitUsageTrackerChange(PVBOXGUESTBITUSAGETRACER pTracker, uint32_t fChanged, uint32_t fPrevious,
+                                       uint32_t cMax, const char *pszWhat)
+{
+    bool fGlobalChange = false;
+    AssertCompile(sizeof(pTracker->acPerBitUsage) == 32 * sizeof(uint32_t));
+
+    while (fChanged)
+    {
+        uint32_t const iBit     = ASMBitFirstSetU32(fChanged) - 1;
+        uint32_t const fBitMask = RT_BIT_32(iBit);
+        Assert(iBit < 32); Assert(fBitMask & fChanged);
+
+        if (fBitMask & fPrevious)
+        {
+            pTracker->acPerBitUsage[iBit] -= 1;
+            AssertMsg(pTracker->acPerBitUsage[iBit] <= cMax,
+                      ("%s: acPerBitUsage[%u]=%#x cMax=%#x\n", pszWhat, iBit, pTracker->acPerBitUsage[iBit], cMax));
+            if (pTracker->acPerBitUsage[iBit] == 0)
+            {
+                fGlobalChange = true;
+                pTracker->fMask &= ~fBitMask;
+            }
+        }
+        else
+        {
+            pTracker->acPerBitUsage[iBit] += 1;
+            AssertMsg(pTracker->acPerBitUsage[iBit] > 0 && pTracker->acPerBitUsage[iBit] <= cMax,
+                      ("pTracker->acPerBitUsage[%u]=%#x cMax=%#x\n", pszWhat, iBit, pTracker->acPerBitUsage[iBit], cMax));
+            if (pTracker->acPerBitUsage[iBit] == 1)
+            {
+                fGlobalChange = true;
+                pTracker->fMask |= fBitMask;
+            }
+        }
+
+        fChanged &= ~fBitMask;
+    }
+
+#ifdef VBOX_STRICT
+    vgdrvBitUsageTrackerCheckMask(pTracker, cMax, pszWhat);
+#endif
+    NOREF(pszWhat); NOREF(cMax);
+    return fGlobalChange;
+}
+
+
+/**
+ * Init and termination worker for resetting the (host) event filter on the host
+ *
+ * @returns VBox status code.
+ * @param   pDevExt         The device extension.
+ * @param   fFixedEvents    Fixed events (init time).
+ */
+static int vgdrvResetEventFilterOnHost(PVBOXGUESTDEVEXT pDevExt, uint32_t fFixedEvents)
+{
+    VMMDevCtlGuestFilterMask *pReq;
+    int rc = VbglR0GRAlloc((VMMDevRequestHeader **)&pReq, sizeof(*pReq), VMMDevReq_CtlGuestFilterMask);
+    if (RT_SUCCESS(rc))
+    {
+        pReq->u32NotMask = UINT32_MAX & ~fFixedEvents;
+        pReq->u32OrMask  = fFixedEvents;
+        rc = VbglR0GRPerform(&pReq->header);
+        if (RT_FAILURE(rc))
+            LogRelFunc(("failed with rc=%Rrc\n", rc));
+        VbglR0GRFree(&pReq->header);
+    }
+    RT_NOREF1(pDevExt);
+    return rc;
+}
+
+
+/**
+ * Changes the event filter mask for the given session.
+ *
+ * This is called in response to VBGL_IOCTL_CHANGE_FILTER_MASK as well as to do
+ * session cleanup.
+ *
+ * @returns VBox status code.
+ * @param   pDevExt             The device extension.
+ * @param   pSession            The session.
+ * @param   fOrMask             The events to add.
+ * @param   fNotMask            The events to remove.
+ * @param   fSessionTermination Set if we're called by the session cleanup code.
+ *                              This tweaks the error handling so we perform
+ *                              proper session cleanup even if the host
+ *                              misbehaves.
+ *
+ * @remarks Takes the session spinlock.
+ */
+static int vgdrvSetSessionEventFilter(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession,
+                                      uint32_t fOrMask, uint32_t fNotMask, bool fSessionTermination)
+{
+    VMMDevCtlGuestFilterMask   *pReq;
+    uint32_t                    fChanged;
+    uint32_t                    fPrevious;
+    int                         rc;
+
+    /*
+     * Preallocate a request buffer so we can do all in one go without leaving the spinlock.
+     */
+    rc = VbglR0GRAlloc((VMMDevRequestHeader **)&pReq, sizeof(*pReq), VMMDevReq_CtlGuestFilterMask);
+    if (RT_SUCCESS(rc))
+    { /* nothing */ }
+    else if (!fSessionTermination)
+    {
+        LogRel(("vgdrvSetSessionFilterMask: VbglR0GRAlloc failure: %Rrc\n", rc));
+        return rc;
+    }
+    else
+        pReq = NULL; /* Ignore failure, we must do session cleanup. */
+
+
+    RTSpinlockAcquire(pDevExt->SessionSpinlock);
+
+    /*
+     * Apply the changes to the session mask.
+     */
+    fPrevious = pSession->fEventFilter;
+    pSession->fEventFilter |= fOrMask;
+    pSession->fEventFilter &= ~fNotMask;
+
+    /*
+     * If anything actually changed, update the global usage counters.
+     */
+    fChanged = fPrevious ^ pSession->fEventFilter;
+    LogFlow(("vgdrvSetSessionEventFilter: Session->fEventFilter: %#x -> %#x (changed %#x)\n",
+             fPrevious, pSession->fEventFilter, fChanged));
+    if (fChanged)
+    {
+        bool fGlobalChange = vgdrvBitUsageTrackerChange(&pDevExt->EventFilterTracker, fChanged, fPrevious,
+                                                        pDevExt->cSessions, "EventFilterTracker");
+
+        /*
+         * If there are global changes, update the event filter on the host.
+         */
+        if (fGlobalChange || pDevExt->fEventFilterHost == UINT32_MAX)
+        {
+            Assert(pReq || fSessionTermination);
+            if (pReq)
+            {
+                pReq->u32OrMask = pDevExt->fFixedEvents | pDevExt->EventFilterTracker.fMask;
+                if (pReq->u32OrMask == pDevExt->fEventFilterHost)
+                    rc = VINF_SUCCESS;
+                else
+                {
+                    pDevExt->fEventFilterHost = pReq->u32OrMask;
+                    pReq->u32NotMask = ~pReq->u32OrMask;
+                    rc = VbglR0GRPerform(&pReq->header);
+                    if (RT_FAILURE(rc))
+                    {
+                        /*
+                         * Failed, roll back (unless it's session termination time).
+                         */
+                        pDevExt->fEventFilterHost = UINT32_MAX;
+                        if (!fSessionTermination)
+                        {
+                            vgdrvBitUsageTrackerChange(&pDevExt->EventFilterTracker, fChanged, pSession->fEventFilter,
+                                                       pDevExt->cSessions, "EventFilterTracker");
+                            pSession->fEventFilter = fPrevious;
+                        }
+                    }
+                }
+            }
+            else
+                rc = VINF_SUCCESS;
+        }
+    }
+
+    RTSpinlockRelease(pDevExt->SessionSpinlock);
+    if (pReq)
+        VbglR0GRFree(&pReq->header);
+    return rc;
+}
+
+
+/**
+ * Handle VBGL_IOCTL_CHANGE_FILTER_MASK.
+ *
+ * @returns VBox status code.
+ *
+ * @param   pDevExt             The device extension.
+ * @param   pSession            The session.
+ * @param   pInfo               The request.
+ */
+static int vgdrvIoCtl_ChangeFilterMask(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession, PVBGLIOCCHANGEFILTERMASK pInfo)
+{
+    LogFlow(("VBGL_IOCTL_CHANGE_FILTER_MASK: or=%#x not=%#x\n", pInfo->u.In.fOrMask, pInfo->u.In.fNotMask));
+
+    if ((pInfo->u.In.fOrMask | pInfo->u.In.fNotMask) & ~VMMDEV_EVENT_VALID_EVENT_MASK)
+    {
+        Log(("VBGL_IOCTL_CHANGE_FILTER_MASK: or=%#x not=%#x: Invalid masks!\n", pInfo->u.In.fOrMask, pInfo->u.In.fNotMask));
+        return VERR_INVALID_PARAMETER;
+    }
+
+    return vgdrvSetSessionEventFilter(pDevExt, pSession, pInfo->u.In.fOrMask, pInfo->u.In.fNotMask, false /*fSessionTermination*/);
+}
+
+
+/**
+ * Init and termination worker for set mouse feature status to zero on the host.
+ *
+ * @returns VBox status code.
+ * @param   pDevExt         The device extension.
+ */
+static int vgdrvResetMouseStatusOnHost(PVBOXGUESTDEVEXT pDevExt)
+{
+    VMMDevReqMouseStatus *pReq;
+    int rc = VbglR0GRAlloc((VMMDevRequestHeader **)&pReq, sizeof(*pReq), VMMDevReq_SetMouseStatus);
+    if (RT_SUCCESS(rc))
+    {
+        pReq->mouseFeatures = 0;
+        pReq->pointerXPos   = 0;
+        pReq->pointerYPos   = 0;
+        rc = VbglR0GRPerform(&pReq->header);
+        if (RT_FAILURE(rc))
+            LogRelFunc(("failed with rc=%Rrc\n", rc));
+        VbglR0GRFree(&pReq->header);
+    }
+    RT_NOREF1(pDevExt);
+    return rc;
+}
+
+
+/**
+ * Changes the mouse status mask for the given session.
+ *
+ * This is called in response to VBOXGUEST_IOCTL_SET_MOUSE_STATUS as well as to
+ * do session cleanup.
+ *
+ * @returns VBox status code.
+ * @param   pDevExt             The device extension.
+ * @param   pSession            The session.
+ * @param   fOrMask             The status flags to add.
+ * @param   fNotMask            The status flags to remove.
+ * @param   fSessionTermination Set if we're called by the session cleanup code.
+ *                              This tweaks the error handling so we perform
+ *                              proper session cleanup even if the host
+ *                              misbehaves.
+ *
+ * @remarks Takes the session spinlock.
+ */
+static int vgdrvSetSessionMouseStatus(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession,
+                                      uint32_t fOrMask, uint32_t fNotMask, bool fSessionTermination)
+{
+    VMMDevReqMouseStatus   *pReq;
+    uint32_t                fChanged;
+    uint32_t                fPrevious;
+    int                     rc;
+
+    /*
+     * Preallocate a request buffer so we can do all in one go without leaving the spinlock.
+     */
+    rc = VbglR0GRAlloc((VMMDevRequestHeader **)&pReq, sizeof(*pReq), VMMDevReq_SetMouseStatus);
+    if (RT_SUCCESS(rc))
+    {
+        if (!fSessionTermination)
+            pReq->header.fRequestor = pSession->fRequestor;
+    }
+    else if (!fSessionTermination)
+    {
+        LogRel(("vgdrvSetSessionMouseStatus: VbglR0GRAlloc failure: %Rrc\n", rc));
+        return rc;
+    }
+    else
+        pReq = NULL; /* Ignore failure, we must do session cleanup. */
+
+
+    RTSpinlockAcquire(pDevExt->SessionSpinlock);
+
+    /*
+     * Apply the changes to the session mask.
+     */
+    fPrevious = pSession->fMouseStatus;
+    pSession->fMouseStatus |= fOrMask;
+    pSession->fMouseStatus &= ~fNotMask;
+
+    /*
+     * If anything actually changed, update the global usage counters.
+     */
+    fChanged = fPrevious ^ pSession->fMouseStatus;
+    if (fChanged)
+    {
+        bool fGlobalChange = vgdrvBitUsageTrackerChange(&pDevExt->MouseStatusTracker, fChanged, fPrevious,
+                                                        pDevExt->cSessions, "MouseStatusTracker");
+
+        /*
+         * If there are global changes, update the event filter on the host.
+         */
+        if (fGlobalChange || pDevExt->fMouseStatusHost == UINT32_MAX)
+        {
+            Assert(pReq || fSessionTermination);
+            if (pReq)
+            {
+                pReq->mouseFeatures = pDevExt->MouseStatusTracker.fMask;
+                if (pReq->mouseFeatures == pDevExt->fMouseStatusHost)
+                    rc = VINF_SUCCESS;
+                else
+                {
+                    pDevExt->fMouseStatusHost = pReq->mouseFeatures;
+                    pReq->pointerXPos = 0;
+                    pReq->pointerYPos = 0;
+                    rc = VbglR0GRPerform(&pReq->header);
+                    if (RT_FAILURE(rc))
+                    {
+                        /*
+                         * Failed, roll back (unless it's session termination time).
+                         */
+                        pDevExt->fMouseStatusHost = UINT32_MAX;
+                        if (!fSessionTermination)
+                        {
+                            vgdrvBitUsageTrackerChange(&pDevExt->MouseStatusTracker, fChanged, pSession->fMouseStatus,
+                                                       pDevExt->cSessions, "MouseStatusTracker");
+                            pSession->fMouseStatus = fPrevious;
+                        }
+                    }
+                }
+            }
+            else
+                rc = VINF_SUCCESS;
+        }
+    }
+
+    RTSpinlockRelease(pDevExt->SessionSpinlock);
+    if (pReq)
+        VbglR0GRFree(&pReq->header);
+    return rc;
+}
+
+
+/**
+ * Sets the mouse status features for this session and updates them globally.
+ *
+ * @returns VBox status code.
+ *
+ * @param   pDevExt             The device extention.
+ * @param   pSession            The session.
+ * @param   fFeatures           New bitmap of enabled features.
+ */
+static int vgdrvIoCtl_SetMouseStatus(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession, uint32_t fFeatures)
+{
+    LogFlow(("VBGL_IOCTL_SET_MOUSE_STATUS: features=%#x\n", fFeatures));
+
+    if (fFeatures & ~VMMDEV_MOUSE_GUEST_MASK)
+        return VERR_INVALID_PARAMETER;
+
+    return vgdrvSetSessionMouseStatus(pDevExt, pSession, fFeatures, ~fFeatures, false /*fSessionTermination*/);
+}
+
+
+/**
+ * Return the mask of VMM device events that this session is allowed to see (wrt
+ * to "acquire" mode guest capabilities).
+ *
+ * The events associated with guest capabilities in "acquire" mode will be
+ * restricted to sessions which has acquired the respective capabilities.
+ * If someone else tries to wait for acquired events, they won't be woken up
+ * when the event becomes pending.  Should some other thread in the session
+ * acquire the capability while the corresponding event is pending, the waiting
+ * thread will woken up.
+ *
+ * @returns Mask of events valid for the given session.
+ * @param   pDevExt             The device extension.
+ * @param   pSession            The session.
+ *
+ * @remarks Needs only be called when dispatching events in the
+ *          VBOXGUEST_ACQUIRE_STYLE_EVENTS mask.
+ */
+static uint32_t vgdrvGetAllowedEventMaskForSession(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession)
+{
+    uint32_t fAcquireModeGuestCaps;
+    uint32_t fAcquiredGuestCaps;
+    uint32_t fAllowedEvents;
+
+    /*
+     * Note! Reads pSession->fAcquiredGuestCaps and pDevExt->fAcquireModeGuestCaps
+     *       WITHOUT holding VBOXGUESTDEVEXT::SessionSpinlock.
+     */
+    fAcquireModeGuestCaps = ASMAtomicUoReadU32(&pDevExt->fAcquireModeGuestCaps);
+    if (fAcquireModeGuestCaps == 0)
+        return VMMDEV_EVENT_VALID_EVENT_MASK;
+    fAcquiredGuestCaps = ASMAtomicUoReadU32(&pSession->fAcquiredGuestCaps);
+
+    /*
+     * Calculate which events to allow according to the cap config and caps
+     * acquired by the session.
+     */
+    fAllowedEvents = VMMDEV_EVENT_VALID_EVENT_MASK;
+    if (   !(fAcquiredGuestCaps   & VMMDEV_GUEST_SUPPORTS_GRAPHICS)
+        && (fAcquireModeGuestCaps & VMMDEV_GUEST_SUPPORTS_GRAPHICS))
+        fAllowedEvents &= ~VMMDEV_EVENT_DISPLAY_CHANGE_REQUEST;
+
+    if (   !(fAcquiredGuestCaps   & VMMDEV_GUEST_SUPPORTS_SEAMLESS)
+        && (fAcquireModeGuestCaps & VMMDEV_GUEST_SUPPORTS_SEAMLESS))
+        fAllowedEvents &= ~VMMDEV_EVENT_SEAMLESS_MODE_CHANGE_REQUEST;
+
+    return fAllowedEvents;
+}
+
+
+/**
+ * Init and termination worker for set guest capabilities to zero on the host.
+ *
+ * @returns VBox status code.
+ * @param   pDevExt         The device extension.
+ */
+static int vgdrvResetCapabilitiesOnHost(PVBOXGUESTDEVEXT pDevExt)
+{
+    VMMDevReqGuestCapabilities2 *pReq;
+    int rc = VbglR0GRAlloc((VMMDevRequestHeader **)&pReq, sizeof(*pReq), VMMDevReq_SetGuestCapabilities);
+    if (RT_SUCCESS(rc))
+    {
+        pReq->u32NotMask = UINT32_MAX;
+        pReq->u32OrMask  = 0;
+        rc = VbglR0GRPerform(&pReq->header);
+
+        if (RT_FAILURE(rc))
+            LogRelFunc(("failed with rc=%Rrc\n", rc));
+        VbglR0GRFree(&pReq->header);
+    }
+    RT_NOREF1(pDevExt);
+    return rc;
+}
+
+
+/**
+ * Sets the guest capabilities to the host while holding the lock.
+ *
+ * This will ASSUME that we're the ones in charge of the mask, so
+ * we'll simply clear all bits we don't set.
+ *
+ * @returns VBox status code.
+ * @param   pDevExt             The device extension.
+ * @param   pReq                The request.
+ */
+static int vgdrvUpdateCapabilitiesOnHostWithReqAndLock(PVBOXGUESTDEVEXT pDevExt, VMMDevReqGuestCapabilities2 *pReq)
+{
+    int rc;
+
+    pReq->u32OrMask = pDevExt->fAcquiredGuestCaps | pDevExt->SetGuestCapsTracker.fMask;
+    if (pReq->u32OrMask == pDevExt->fGuestCapsHost)
+        rc = VINF_SUCCESS;
+    else
+    {
+        pDevExt->fGuestCapsHost = pReq->u32OrMask;
+        pReq->u32NotMask = ~pReq->u32OrMask;
+        rc = VbglR0GRPerform(&pReq->header);
+        if (RT_FAILURE(rc))
+            pDevExt->fGuestCapsHost = UINT32_MAX;
+    }
+
+    return rc;
+}
+
+
+/**
+ * Switch a set of capabilities into "acquire" mode and (maybe) acquire them for
+ * the given session.
+ *
+ * This is called in response to VBOXGUEST_IOCTL_GUEST_CAPS_ACQUIRE as well as
+ * to do session cleanup.
+ *
+ * @returns VBox status code.
+ * @param   pDevExt             The device extension.
+ * @param   pSession            The session.
+ * @param   fOrMask             The capabilities to add .
+ * @param   fNotMask            The capabilities to remove.  Ignored in
+ *                              VBOXGUESTCAPSACQUIRE_FLAGS_CONFIG_ACQUIRE_MODE.
+ * @param   fFlags              Confusing operation modifier.
+ *                              VBOXGUESTCAPSACQUIRE_FLAGS_NONE means to both
+ *                              configure and acquire/release the capabilities.
+ *                              VBOXGUESTCAPSACQUIRE_FLAGS_CONFIG_ACQUIRE_MODE
+ *                              means only configure capabilities in the
+ *                              @a fOrMask capabilities for "acquire" mode.
+ * @param   fSessionTermination Set if we're called by the session cleanup code.
+ *                              This tweaks the error handling so we perform
+ *                              proper session cleanup even if the host
+ *                              misbehaves.
+ *
+ * @remarks Takes both the session and event spinlocks.
+ */
+static int vgdrvAcquireSessionCapabilities(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession,
+                                           uint32_t fOrMask, uint32_t fNotMask, uint32_t fFlags,
+                                           bool fSessionTermination)
+{
+    uint32_t fCurrentOwnedCaps;
+    uint32_t fSessionRemovedCaps;
+    uint32_t fSessionAddedCaps;
+    uint32_t fOtherConflictingCaps;
+    VMMDevReqGuestCapabilities2 *pReq = NULL;
+    int rc;
+
+
+    /*
+     * Validate and adjust input.
+     */
+    if (fOrMask & ~(  VMMDEV_GUEST_SUPPORTS_SEAMLESS
+                    | VMMDEV_GUEST_SUPPORTS_GUEST_HOST_WINDOW_MAPPING
+                    | VMMDEV_GUEST_SUPPORTS_GRAPHICS ) )
+    {
+        LogRel(("vgdrvAcquireSessionCapabilities: invalid fOrMask=%#x (pSession=%p fNotMask=%#x fFlags=%#x)\n",
+                fOrMask, pSession, fNotMask, fFlags));
+        return VERR_INVALID_PARAMETER;
+    }
+
+    if ((fFlags & ~VBGL_IOC_AGC_FLAGS_VALID_MASK) != 0)
+    {
+        LogRel(("vgdrvAcquireSessionCapabilities: invalid fFlags=%#x (pSession=%p fOrMask=%#x fNotMask=%#x)\n",
+                fFlags, pSession, fOrMask, fNotMask));
+        return VERR_INVALID_PARAMETER;
+    }
+    Assert(!fOrMask || !fSessionTermination);
+
+    /* The fNotMask no need to have all values valid, invalid ones will simply be ignored. */
+    fNotMask &= ~fOrMask;
+
+    /*
+     * Preallocate a update request if we're about to do more than just configure
+     * the capability mode.
+     */
+    if (!(fFlags & VBGL_IOC_AGC_FLAGS_CONFIG_ACQUIRE_MODE))
+    {
+        rc = VbglR0GRAlloc((VMMDevRequestHeader **)&pReq, sizeof(*pReq), VMMDevReq_SetGuestCapabilities);
+        if (RT_SUCCESS(rc))
+        {
+            if (!fSessionTermination)
+                pReq->header.fRequestor = pSession->fRequestor;
+        }
+        else if (!fSessionTermination)
+        {
+            LogRel(("vgdrvAcquireSessionCapabilities: pSession=%p fOrMask=%#x fNotMask=%#x fFlags=%#x: VbglR0GRAlloc failure: %Rrc\n",
+                    pSession, fOrMask, fNotMask, fFlags, rc));
+            return rc;
+        }
+        else
+            pReq = NULL; /* Ignore failure, we must do session cleanup. */
+    }
+
+    /*
+     * Try switch the capabilities in the OR mask into "acquire" mode.
+     *
+     * Note! We currently ignore anyone which may already have "set" the capabilities
+     *       in fOrMask.  Perhaps not the best way to handle it, but it's simple...
+     */
+    RTSpinlockAcquire(pDevExt->EventSpinlock);
+
+    if (!(pDevExt->fSetModeGuestCaps & fOrMask))
+        pDevExt->fAcquireModeGuestCaps |= fOrMask;
+    else
+    {
+        RTSpinlockRelease(pDevExt->EventSpinlock);
+
+        if (pReq)
+            VbglR0GRFree(&pReq->header);
+        AssertMsgFailed(("Trying to change caps mode: %#x\n", fOrMask));
+        LogRel(("vgdrvAcquireSessionCapabilities: pSession=%p fOrMask=%#x fNotMask=%#x fFlags=%#x: calling caps acquire for set caps\n",
+                pSession, fOrMask, fNotMask, fFlags));
+        return VERR_INVALID_STATE;
+    }
+
+    /*
+     * If we only wanted to switch the capabilities into "acquire" mode, we're done now.
+     */
+    if (fFlags & VBGL_IOC_AGC_FLAGS_CONFIG_ACQUIRE_MODE)
+    {
+        RTSpinlockRelease(pDevExt->EventSpinlock);
+
+        Assert(!pReq);
+        Log(("vgdrvAcquireSessionCapabilities: pSession=%p fOrMask=%#x fNotMask=%#x fFlags=%#x: configured acquire caps: 0x%x\n",
+             pSession, fOrMask, fNotMask, fFlags));
+        return VINF_SUCCESS;
+    }
+    Assert(pReq || fSessionTermination);
+
+    /*
+     * Caller wants to acquire/release the capabilities too.
+     *
+     * Note! The mode change of the capabilities above won't be reverted on
+     *       failure, this is intentional.
+     */
+    fCurrentOwnedCaps      = pSession->fAcquiredGuestCaps;
+    fSessionRemovedCaps    = fCurrentOwnedCaps & fNotMask;
+    fSessionAddedCaps      = fOrMask & ~fCurrentOwnedCaps;
+    fOtherConflictingCaps  = pDevExt->fAcquiredGuestCaps & ~fCurrentOwnedCaps;
+    fOtherConflictingCaps &= fSessionAddedCaps;
+
+    if (!fOtherConflictingCaps)
+    {
+        if (fSessionAddedCaps)
+        {
+            pSession->fAcquiredGuestCaps |= fSessionAddedCaps;
+            pDevExt->fAcquiredGuestCaps  |= fSessionAddedCaps;
+        }
+
+        if (fSessionRemovedCaps)
+        {
+            pSession->fAcquiredGuestCaps &= ~fSessionRemovedCaps;
+            pDevExt->fAcquiredGuestCaps  &= ~fSessionRemovedCaps;
+        }
+
+        /*
+         * If something changes (which is very likely), tell the host.
+         */
+        if (fSessionAddedCaps || fSessionRemovedCaps || pDevExt->fGuestCapsHost == UINT32_MAX)
+        {
+            Assert(pReq || fSessionTermination);
+            if (pReq)
+            {
+                rc = vgdrvUpdateCapabilitiesOnHostWithReqAndLock(pDevExt, pReq);
+                if (RT_FAILURE(rc) && !fSessionTermination)
+                {
+                    /* Failed, roll back. */
+                    if (fSessionAddedCaps)
+                    {
+                        pSession->fAcquiredGuestCaps &= ~fSessionAddedCaps;
+                        pDevExt->fAcquiredGuestCaps  &= ~fSessionAddedCaps;
+                    }
+                    if (fSessionRemovedCaps)
+                    {
+                        pSession->fAcquiredGuestCaps |= fSessionRemovedCaps;
+                        pDevExt->fAcquiredGuestCaps  |= fSessionRemovedCaps;
+                    }
+
+                    RTSpinlockRelease(pDevExt->EventSpinlock);
+                    LogRel(("vgdrvAcquireSessionCapabilities: vgdrvUpdateCapabilitiesOnHostWithReqAndLock failed: rc=%Rrc\n", rc));
+                    VbglR0GRFree(&pReq->header);
+                    return rc;
+                }
+            }
+        }
+    }
+    else
+    {
+        RTSpinlockRelease(pDevExt->EventSpinlock);
+
+        Log(("vgdrvAcquireSessionCapabilities: Caps %#x were busy\n", fOtherConflictingCaps));
+        VbglR0GRFree(&pReq->header);
+        return VERR_RESOURCE_BUSY;
+    }
+
+    RTSpinlockRelease(pDevExt->EventSpinlock);
+    if (pReq)
+        VbglR0GRFree(&pReq->header);
+
+    /*
+     * If we added a capability, check if that means some other thread in our
+     * session should be unblocked because there are events pending.
+     *
+     * HACK ALERT! When the seamless support capability is added we generate a
+     *             seamless change event so that the ring-3 client can sync with
+     *             the seamless state. Although this introduces a spurious
+     *             wakeups of the ring-3 client, it solves the problem of client
+     *             state inconsistency in multiuser environment (on Windows).
+     */
+    if (fSessionAddedCaps)
+    {
+        uint32_t fGenFakeEvents = 0;
+        if (fSessionAddedCaps & VMMDEV_GUEST_SUPPORTS_SEAMLESS)
+            fGenFakeEvents |= VMMDEV_EVENT_SEAMLESS_MODE_CHANGE_REQUEST;
+
+        RTSpinlockAcquire(pDevExt->EventSpinlock);
+        if (fGenFakeEvents || pDevExt->f32PendingEvents)
+            vgdrvDispatchEventsLocked(pDevExt, fGenFakeEvents);
+        RTSpinlockRelease(pDevExt->EventSpinlock);
+
+#ifdef VBOXGUEST_USE_DEFERRED_WAKE_UP
+        VGDrvCommonWaitDoWakeUps(pDevExt);
+#endif
+    }
+
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Handle VBGL_IOCTL_ACQUIRE_GUEST_CAPABILITIES.
+ *
+ * @returns VBox status code.
+ *
+ * @param   pDevExt             The device extension.
+ * @param   pSession            The session.
+ * @param   pAcquire            The request.
+ */
+static int vgdrvIoCtl_GuestCapsAcquire(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession, PVBGLIOCACQUIREGUESTCAPS pAcquire)
+{
+    int rc;
+    LogFlow(("VBGL_IOCTL_ACQUIRE_GUEST_CAPABILITIES: or=%#x not=%#x flags=%#x\n",
+             pAcquire->u.In.fOrMask, pAcquire->u.In.fNotMask, pAcquire->u.In.fFlags));
+
+    rc = vgdrvAcquireSessionCapabilities(pDevExt, pSession, pAcquire->u.In.fOrMask, pAcquire->u.In.fNotMask,
+                                         pAcquire->u.In.fFlags, false /*fSessionTermination*/);
+    if (RT_FAILURE(rc))
+        LogRel(("VBGL_IOCTL_ACQUIRE_GUEST_CAPABILITIES failed rc=%Rrc\n", rc));
+    return rc;
+}
+
+
+/**
+ * Sets the guest capabilities for a session.
+ *
+ * @returns VBox status code.
+ * @param   pDevExt             The device extension.
+ * @param   pSession            The session.
+ * @param   fOrMask             The capabilities to add.
+ * @param   fNotMask            The capabilities to remove.
+ * @param   pfSessionCaps       Where to return the guest capabilities reported
+ *                              for this session.  Optional.
+ * @param   pfGlobalCaps        Where to return the guest capabilities reported
+ *                              for all the sessions.  Optional.
+ *
+ * @param   fSessionTermination Set if we're called by the session cleanup code.
+ *                              This tweaks the error handling so we perform
+ *                              proper session cleanup even if the host
+ *                              misbehaves.
+ *
+ * @remarks Takes the session spinlock.
+ */
+static int vgdrvSetSessionCapabilities(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession,
+                                       uint32_t fOrMask, uint32_t fNotMask, uint32_t *pfSessionCaps, uint32_t *pfGlobalCaps,
+                                       bool fSessionTermination)
+{
+    /*
+     * Preallocate a request buffer so we can do all in one go without leaving the spinlock.
+     */
+    VMMDevReqGuestCapabilities2 *pReq;
+    int rc = VbglR0GRAlloc((VMMDevRequestHeader **)&pReq, sizeof(*pReq), VMMDevReq_SetGuestCapabilities);
+    if (RT_SUCCESS(rc))
+    {
+        if (!fSessionTermination)
+            pReq->header.fRequestor = pSession->fRequestor;
+    }
+    else if (!fSessionTermination)
+    {
+        if (pfSessionCaps)
+            *pfSessionCaps = UINT32_MAX;
+        if (pfGlobalCaps)
+            *pfGlobalCaps  = UINT32_MAX;
+        LogRel(("vgdrvSetSessionCapabilities: VbglR0GRAlloc failure: %Rrc\n", rc));
+        return rc;
+    }
+    else
+        pReq = NULL; /* Ignore failure, we must do session cleanup. */
+
+
+    RTSpinlockAcquire(pDevExt->SessionSpinlock);
+
+#ifndef VBOXGUEST_DISREGARD_ACQUIRE_MODE_GUEST_CAPS
+    /*
+     * Capabilities in "acquire" mode cannot be set via this API.
+     * (Acquire mode is only used on windows at the time of writing.)
+     */
+    if (!(fOrMask & pDevExt->fAcquireModeGuestCaps))
+#endif
+    {
+        /*
+         * Apply the changes to the session mask.
+         */
+        uint32_t fChanged;
+        uint32_t fPrevious = pSession->fCapabilities;
+        pSession->fCapabilities |= fOrMask;
+        pSession->fCapabilities &= ~fNotMask;
+
+        /*
+         * If anything actually changed, update the global usage counters.
+         */
+        fChanged = fPrevious ^ pSession->fCapabilities;
+        if (fChanged)
+        {
+            bool fGlobalChange = vgdrvBitUsageTrackerChange(&pDevExt->SetGuestCapsTracker, fChanged, fPrevious,
+                                                            pDevExt->cSessions, "SetGuestCapsTracker");
+
+            /*
+             * If there are global changes, update the capabilities on the host.
+             */
+            if (fGlobalChange || pDevExt->fGuestCapsHost == UINT32_MAX)
+            {
+                Assert(pReq || fSessionTermination);
+                if (pReq)
+                {
+                    rc = vgdrvUpdateCapabilitiesOnHostWithReqAndLock(pDevExt, pReq);
+
+                    /* On failure, roll back (unless it's session termination time). */
+                    if (RT_FAILURE(rc) && !fSessionTermination)
+                    {
+                        vgdrvBitUsageTrackerChange(&pDevExt->SetGuestCapsTracker, fChanged, pSession->fCapabilities,
+                                                   pDevExt->cSessions, "SetGuestCapsTracker");
+                        pSession->fCapabilities = fPrevious;
+                    }
+                }
+            }
+        }
+    }
+#ifndef VBOXGUEST_DISREGARD_ACQUIRE_MODE_GUEST_CAPS
+    else
+        rc = VERR_RESOURCE_BUSY;
+#endif
+
+    if (pfSessionCaps)
+        *pfSessionCaps = pSession->fCapabilities;
+    if (pfGlobalCaps)
+        *pfGlobalCaps  = pDevExt->fAcquiredGuestCaps | pDevExt->SetGuestCapsTracker.fMask;
+
+    RTSpinlockRelease(pDevExt->SessionSpinlock);
+    if (pReq)
+        VbglR0GRFree(&pReq->header);
+    return rc;
+}
+
+
+/**
+ * Handle VBGL_IOCTL_CHANGE_GUEST_CAPABILITIES.
+ *
+ * @returns VBox status code.
+ *
+ * @param   pDevExt             The device extension.
+ * @param   pSession            The session.
+ * @param   pInfo               The request.
+ */
+static int vgdrvIoCtl_SetCapabilities(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession, PVBGLIOCSETGUESTCAPS pInfo)
+{
+    int rc;
+    LogFlow(("VBGL_IOCTL_CHANGE_GUEST_CAPABILITIES: or=%#x not=%#x\n", pInfo->u.In.fOrMask, pInfo->u.In.fNotMask));
+
+    if (!((pInfo->u.In.fOrMask | pInfo->u.In.fNotMask) & ~VMMDEV_GUEST_CAPABILITIES_MASK))
+        rc = vgdrvSetSessionCapabilities(pDevExt, pSession, pInfo->u.In.fOrMask, pInfo->u.In.fNotMask,
+                                         &pInfo->u.Out.fSessionCaps, &pInfo->u.Out.fGlobalCaps, false /*fSessionTermination*/);
+    else
+        rc = VERR_INVALID_PARAMETER;
+
+    return rc;
+}
+
+/** @} */
+
+
+/**
+ * Common IOCtl for user to kernel and kernel to kernel communication.
+ *
+ * This function only does the basic validation and then invokes
+ * worker functions that takes care of each specific function.
+ *
+ * @returns VBox status code.
+ *
+ * @param   iFunction           The requested function.
+ * @param   pDevExt             The device extension.
+ * @param   pSession            The client session.
+ * @param   pReqHdr             Pointer to the request.  This always starts with
+ *                              a request common header.
+ * @param   cbReq               The max size of the request buffer.
+ */
+int VGDrvCommonIoCtl(uintptr_t iFunction, PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession, PVBGLREQHDR pReqHdr, size_t cbReq)
+{
+    uintptr_t const iFunctionStripped = VBGL_IOCTL_CODE_STRIPPED(iFunction);
+    int rc;
+
+    LogFlow(("VGDrvCommonIoCtl: iFunction=%#x pDevExt=%p pSession=%p pReqHdr=%p cbReq=%zu\n",
+             iFunction, pDevExt, pSession, pReqHdr, cbReq));
+
+    /*
+     * Define some helper macros to simplify validation.
+     */
+#define REQ_CHECK_SIZES_EX(Name, cbInExpect, cbOutExpect) \
+    do { \
+        if (RT_LIKELY(   pReqHdr->cbIn == (cbInExpect) \
+                      && (   pReqHdr->cbOut == (cbOutExpect) \
+                          || ((cbInExpect) == (cbOutExpect) && pReqHdr->cbOut == 0) ) )) \
+        { /* likely */ } \
+        else \
+        { \
+            Log(( #Name ": Invalid input/output sizes. cbIn=%ld expected %ld. cbOut=%ld expected %ld.\n", \
+                 (long)pReqHdr->cbIn, (long)(cbInExpect), (long)pReqHdr->cbOut, (long)(cbOutExpect))); \
+            return pReqHdr->rc = VERR_INVALID_PARAMETER; \
+        } \
+    } while (0)
+
+#define REQ_CHECK_SIZES(Name) REQ_CHECK_SIZES_EX(Name, Name ## _SIZE_IN, Name ## _SIZE_OUT)
+
+#define REQ_CHECK_SIZE_IN(Name, cbInExpect) \
+    do { \
+        if (RT_LIKELY(pReqHdr->cbIn == (cbInExpect))) \
+        { /* likely */ } \
+        else \
+        { \
+            Log(( #Name ": Invalid input/output sizes. cbIn=%ld expected %ld.\n", \
+                 (long)pReqHdr->cbIn, (long)(cbInExpect))); \
+            return pReqHdr->rc = VERR_INVALID_PARAMETER; \
+        } \
+    } while (0)
+
+#define REQ_CHECK_SIZE_OUT(Name, cbOutExpect) \
+    do { \
+        if (RT_LIKELY(   pReqHdr->cbOut == (cbOutExpect) \
+                      || (pReqHdr->cbOut == 0 && pReqHdr->cbIn == (cbOutExpect)))) \
+        { /* likely */ } \
+        else \
+        { \
+            Log(( #Name ": Invalid input/output sizes. cbOut=%ld (%ld) expected %ld.\n", \
+                 (long)pReqHdr->cbOut, (long)pReqHdr->cbIn, (long)(cbOutExpect))); \
+            return pReqHdr->rc = VERR_INVALID_PARAMETER; \
+        } \
+    } while (0)
+
+#define REQ_CHECK_EXPR(Name, expr) \
+    do { \
+        if (RT_LIKELY(!!(expr))) \
+        { /* likely */ } \
+        else \
+        { \
+            Log(( #Name ": %s\n", #expr)); \
+            return pReqHdr->rc = VERR_INVALID_PARAMETER; \
+        } \
+    } while (0)
+
+#define REQ_CHECK_EXPR_FMT(expr, fmt) \
+    do { \
+        if (RT_LIKELY(!!(expr))) \
+        { /* likely */ } \
+        else \
+        { \
+            Log( fmt ); \
+            return pReqHdr->rc = VERR_INVALID_PARAMETER; \
+        } \
+    } while (0)
+
+#define REQ_CHECK_RING0(mnemonic) \
+    do { \
+        if (pSession->R0Process != NIL_RTR0PROCESS) \
+        { \
+            LogFunc((mnemonic ": Ring-0 only, caller is %RTproc/%p\n", \
+                     pSession->Process, (uintptr_t)pSession->R0Process)); \
+            return pReqHdr->rc = VERR_PERMISSION_DENIED; \
+        } \
+    } while (0)
+
+
+    /*
+     * Validate the request.
+     */
+    if (RT_LIKELY(cbReq >= sizeof(*pReqHdr)))
+    { /* likely */ }
+    else
+    {
+        Log(("VGDrvCommonIoCtl: Bad ioctl request size; cbReq=%#lx\n", (long)cbReq));
+        return VERR_INVALID_PARAMETER;
+    }
+
+    if (pReqHdr->cbOut == 0)
+        pReqHdr->cbOut = pReqHdr->cbIn;
+
+    if (RT_LIKELY(   pReqHdr->uVersion == VBGLREQHDR_VERSION
+                  && pReqHdr->cbIn  >= sizeof(*pReqHdr)
+                  && pReqHdr->cbIn  <= cbReq
+                  && pReqHdr->cbOut >= sizeof(*pReqHdr)
+                  && pReqHdr->cbOut <= cbReq))
+    { /* likely */ }
+    else
+    {
+        Log(("VGDrvCommonIoCtl: Bad ioctl request header; cbIn=%#lx cbOut=%#lx version=%#lx\n",
+             (long)pReqHdr->cbIn, (long)pReqHdr->cbOut, (long)pReqHdr->uVersion));
+        return VERR_INVALID_PARAMETER;
+    }
+
+    if (RT_LIKELY(RT_VALID_PTR(pSession)))
+    { /* likely */ }
+    else
+    {
+        Log(("VGDrvCommonIoCtl: Invalid pSession value %p (ioctl=%#x)\n", pSession, iFunction));
+        return VERR_INVALID_PARAMETER;
+    }
+
+
+    /*
+     * Deal with variably sized requests first.
+     */
+    rc = VINF_SUCCESS;
+    if (   iFunctionStripped == VBGL_IOCTL_CODE_STRIPPED(VBGL_IOCTL_VMMDEV_REQUEST(0))
+        || iFunctionStripped == VBGL_IOCTL_CODE_STRIPPED(VBGL_IOCTL_VMMDEV_REQUEST_BIG) )
+    {
+        REQ_CHECK_EXPR(VBGL_IOCTL_VMMDEV_REQUEST, pReqHdr->uType != VBGLREQHDR_TYPE_DEFAULT);
+        REQ_CHECK_EXPR_FMT(pReqHdr->cbIn == pReqHdr->cbOut,
+                           ("VBGL_IOCTL_VMMDEV_REQUEST: cbIn=%ld != cbOut=%ld\n", (long)pReqHdr->cbIn, (long)pReqHdr->cbOut));
+        pReqHdr->rc = vgdrvIoCtl_VMMDevRequest(pDevExt, pSession, (VMMDevRequestHeader *)pReqHdr, cbReq);
+    }
+    else if (RT_LIKELY(pReqHdr->uType == VBGLREQHDR_TYPE_DEFAULT))
+    {
+        if (iFunctionStripped == VBGL_IOCTL_CODE_STRIPPED(VBGL_IOCTL_LOG(0)))
+        {
+            REQ_CHECK_SIZE_OUT(VBGL_IOCTL_LOG, VBGL_IOCTL_LOG_SIZE_OUT);
+            pReqHdr->rc = vgdrvIoCtl_Log(pDevExt, &((PVBGLIOCLOG)pReqHdr)->u.In.szMsg[0], pReqHdr->cbIn - sizeof(VBGLREQHDR),
+                                         pSession->fUserSession);
+        }
+#ifdef VBOX_WITH_HGCM
+        else if (iFunction == VBGL_IOCTL_IDC_HGCM_FAST_CALL) /* (is variable size, but we don't bother encoding it) */
+        {
+            REQ_CHECK_RING0("VBGL_IOCTL_IDC_HGCM_FAST_CALL");
+            REQ_CHECK_EXPR(VBGL_IOCTL_IDC_HGCM_FAST_CALL, cbReq >= sizeof(VBGLIOCIDCHGCMFASTCALL) + sizeof(VMMDevHGCMCall));
+            pReqHdr->rc = vgdrvIoCtl_HGCMFastCall(pDevExt, (VBGLIOCIDCHGCMFASTCALL volatile *)pReqHdr);
+        }
+        else if (   iFunctionStripped == VBGL_IOCTL_CODE_STRIPPED(VBGL_IOCTL_HGCM_CALL(0))
+# if ARCH_BITS == 64
+                 || iFunctionStripped == VBGL_IOCTL_CODE_STRIPPED(VBGL_IOCTL_HGCM_CALL_32(0))
+# endif
+                )
+        {
+            REQ_CHECK_EXPR(VBGL_IOCTL_HGCM_CALL, pReqHdr->cbIn >= sizeof(VBGLIOCHGCMCALL));
+            REQ_CHECK_EXPR(VBGL_IOCTL_HGCM_CALL, pReqHdr->cbIn == pReqHdr->cbOut);
+            pReqHdr->rc = vgdrvIoCtl_HGCMCallWrapper(pDevExt, pSession, (PVBGLIOCHGCMCALL)pReqHdr,
+                                                     iFunctionStripped == VBGL_IOCTL_CODE_STRIPPED(VBGL_IOCTL_HGCM_CALL_32(0)),
+                                                     false /*fUserData*/, cbReq);
+        }
+        else if (iFunctionStripped == VBGL_IOCTL_CODE_STRIPPED(VBGL_IOCTL_HGCM_CALL_WITH_USER_DATA(0)))
+        {
+            REQ_CHECK_RING0("VBGL_IOCTL_HGCM_CALL_WITH_USER_DATA");
+            REQ_CHECK_EXPR(VBGL_IOCTL_HGCM_CALL, pReqHdr->cbIn >= sizeof(VBGLIOCHGCMCALL));
+            REQ_CHECK_EXPR(VBGL_IOCTL_HGCM_CALL, pReqHdr->cbIn == pReqHdr->cbOut);
+            pReqHdr->rc = vgdrvIoCtl_HGCMCallWrapper(pDevExt, pSession, (PVBGLIOCHGCMCALL)pReqHdr,
+                                                     ARCH_BITS == 32, true /*fUserData*/, cbReq);
+        }
+#endif /* VBOX_WITH_HGCM */
+        else
+        {
+            switch (iFunction)
+            {
+                /*
+                 * Ring-0 only:
+                 */
+                case VBGL_IOCTL_IDC_CONNECT:
+                    REQ_CHECK_RING0("VBGL_IOCL_IDC_CONNECT");
+                    REQ_CHECK_SIZES(VBGL_IOCTL_IDC_CONNECT);
+                    pReqHdr->rc = vgdrvIoCtl_IdcConnect(pDevExt, pSession, (PVBGLIOCIDCCONNECT)pReqHdr);
+                    break;
+
+                case VBGL_IOCTL_IDC_DISCONNECT:
+                    REQ_CHECK_RING0("VBGL_IOCTL_IDC_DISCONNECT");
+                    REQ_CHECK_SIZES(VBGL_IOCTL_IDC_DISCONNECT);
+                    pReqHdr->rc = vgdrvIoCtl_IdcDisconnect(pDevExt, pSession, (PVBGLIOCIDCDISCONNECT)pReqHdr);
+                    break;
+
+                case VBGL_IOCTL_GET_VMMDEV_IO_INFO:
+                    REQ_CHECK_RING0("GET_VMMDEV_IO_INFO");
+                    REQ_CHECK_SIZES(VBGL_IOCTL_GET_VMMDEV_IO_INFO);
+                    pReqHdr->rc = vgdrvIoCtl_GetVMMDevIoInfo(pDevExt, (PVBGLIOCGETVMMDEVIOINFO)pReqHdr);
+                    break;
+
+                case VBGL_IOCTL_SET_MOUSE_NOTIFY_CALLBACK:
+                    REQ_CHECK_RING0("SET_MOUSE_NOTIFY_CALLBACK");
+                    REQ_CHECK_SIZES(VBGL_IOCTL_SET_MOUSE_NOTIFY_CALLBACK);
+                    pReqHdr->rc = vgdrvIoCtl_SetMouseNotifyCallback(pDevExt, (PVBGLIOCSETMOUSENOTIFYCALLBACK)pReqHdr);
+                    break;
+
+                /*
+                 * Ring-3 only:
+                 */
+                case VBGL_IOCTL_DRIVER_VERSION_INFO:
+                    REQ_CHECK_SIZES(VBGL_IOCTL_DRIVER_VERSION_INFO);
+                    pReqHdr->rc = vgdrvIoCtl_DriverVersionInfo(pDevExt, pSession, (PVBGLIOCDRIVERVERSIONINFO)pReqHdr);
+                    break;
+
+                /*
+                 * Both ring-3 and ring-0:
+                 */
+                case VBGL_IOCTL_WAIT_FOR_EVENTS:
+                    REQ_CHECK_SIZES(VBGL_IOCTL_WAIT_FOR_EVENTS);
+                    pReqHdr->rc = vgdrvIoCtl_WaitForEvents(pDevExt, pSession, (VBGLIOCWAITFOREVENTS *)pReqHdr,
+                                                           pSession->R0Process != NIL_RTR0PROCESS);
+                    break;
+
+                case VBGL_IOCTL_INTERRUPT_ALL_WAIT_FOR_EVENTS:
+                    REQ_CHECK_SIZES(VBGL_IOCTL_INTERRUPT_ALL_WAIT_FOR_EVENTS);
+                    pReqHdr->rc = vgdrvIoCtl_CancelAllWaitEvents(pDevExt, pSession);
+                    break;
+
+                case VBGL_IOCTL_CHANGE_FILTER_MASK:
+                    REQ_CHECK_SIZES(VBGL_IOCTL_CHANGE_FILTER_MASK);
+                    pReqHdr->rc = vgdrvIoCtl_ChangeFilterMask(pDevExt, pSession, (PVBGLIOCCHANGEFILTERMASK)pReqHdr);
+                    break;
+
+#ifdef VBOX_WITH_HGCM
+                case VBGL_IOCTL_HGCM_CONNECT:
+                    REQ_CHECK_SIZES(VBGL_IOCTL_HGCM_CONNECT);
+                    pReqHdr->rc = vgdrvIoCtl_HGCMConnect(pDevExt, pSession, (PVBGLIOCHGCMCONNECT)pReqHdr);
+                    break;
+
+                case VBGL_IOCTL_HGCM_DISCONNECT:
+                    REQ_CHECK_SIZES(VBGL_IOCTL_HGCM_DISCONNECT);
+                    pReqHdr->rc = vgdrvIoCtl_HGCMDisconnect(pDevExt, pSession, (PVBGLIOCHGCMDISCONNECT)pReqHdr);
+                    break;
+#endif
+
+                case VBGL_IOCTL_CHECK_BALLOON:
+                    REQ_CHECK_SIZES(VBGL_IOCTL_CHECK_BALLOON);
+                    pReqHdr->rc = vgdrvIoCtl_CheckMemoryBalloon(pDevExt, pSession, (PVBGLIOCCHECKBALLOON)pReqHdr);
+                    break;
+
+                case VBGL_IOCTL_CHANGE_BALLOON:
+                    REQ_CHECK_SIZES(VBGL_IOCTL_CHANGE_BALLOON);
+                    pReqHdr->rc = vgdrvIoCtl_ChangeMemoryBalloon(pDevExt, pSession, (PVBGLIOCCHANGEBALLOON)pReqHdr);
+                    break;
+
+                case VBGL_IOCTL_WRITE_CORE_DUMP:
+                    REQ_CHECK_SIZES(VBGL_IOCTL_WRITE_CORE_DUMP);
+                    pReqHdr->rc = vgdrvIoCtl_WriteCoreDump(pDevExt, pSession, (PVBGLIOCWRITECOREDUMP)pReqHdr);
+                    break;
+
+                case VBGL_IOCTL_SET_MOUSE_STATUS:
+                    REQ_CHECK_SIZES(VBGL_IOCTL_SET_MOUSE_STATUS);
+                    pReqHdr->rc = vgdrvIoCtl_SetMouseStatus(pDevExt, pSession, ((PVBGLIOCSETMOUSESTATUS)pReqHdr)->u.In.fStatus);
+                    break;
+
+                case VBGL_IOCTL_ACQUIRE_GUEST_CAPABILITIES:
+                    REQ_CHECK_SIZES(VBGL_IOCTL_ACQUIRE_GUEST_CAPABILITIES);
+                    pReqHdr->rc = vgdrvIoCtl_GuestCapsAcquire(pDevExt, pSession, (PVBGLIOCACQUIREGUESTCAPS)pReqHdr);
+                    break;
+
+                case VBGL_IOCTL_CHANGE_GUEST_CAPABILITIES:
+                    REQ_CHECK_SIZES(VBGL_IOCTL_CHANGE_GUEST_CAPABILITIES);
+                    pReqHdr->rc = vgdrvIoCtl_SetCapabilities(pDevExt, pSession, (PVBGLIOCSETGUESTCAPS)pReqHdr);
+                    break;
+
+#ifdef VBOX_WITH_DPC_LATENCY_CHECKER
+                case VBGL_IOCTL_DPC_LATENCY_CHECKER:
+                    REQ_CHECK_SIZES(VBGL_IOCTL_DPC_LATENCY_CHECKER);
+                    pReqHdr->rc = VGDrvNtIOCtl_DpcLatencyChecker();
+                    break;
+#endif
+
+                default:
+                {
+                    LogRel(("VGDrvCommonIoCtl: Unknown request iFunction=%#x (stripped %#x) cbReq=%#x\n",
+                            iFunction, iFunctionStripped, cbReq));
+                    pReqHdr->rc = rc = VERR_NOT_SUPPORTED;
+                    break;
+                }
+            }
+        }
+    }
+    else
+    {
+        Log(("VGDrvCommonIoCtl: uType=%#x, expected default (ioctl=%#x)\n", pReqHdr->uType, iFunction));
+        return VERR_INVALID_PARAMETER;
+    }
+
+    LogFlow(("VGDrvCommonIoCtl: returns %Rrc (req: rc=%Rrc cbOut=%#x)\n", rc, pReqHdr->rc, pReqHdr->cbOut));
+    return rc;
+}
+
+
+/**
+ * Used by VGDrvCommonISR as well as the acquire guest capability code.
+ *
+ * @returns VINF_SUCCESS on success. On failure, ORed together
+ *          RTSemEventMultiSignal errors (completes processing despite errors).
+ * @param   pDevExt             The VBoxGuest device extension.
+ * @param   fEvents             The events to dispatch.
+ */
+static int vgdrvDispatchEventsLocked(PVBOXGUESTDEVEXT pDevExt, uint32_t fEvents)
+{
+    PVBOXGUESTWAIT  pWait;
+    PVBOXGUESTWAIT  pSafe;
+    int             rc = VINF_SUCCESS;
+
+    fEvents |= pDevExt->f32PendingEvents;
+
+    RTListForEachSafe(&pDevExt->WaitList, pWait, pSafe, VBOXGUESTWAIT, ListNode)
+    {
+        uint32_t fHandledEvents = pWait->fReqEvents & fEvents;
+        if (    fHandledEvents != 0
+            &&  !pWait->fResEvents)
+        {
+            /* Does this one wait on any of the events we're dispatching?  We do a quick
+               check first, then deal with VBOXGUEST_ACQUIRE_STYLE_EVENTS as applicable. */
+            if (fHandledEvents & VBOXGUEST_ACQUIRE_STYLE_EVENTS)
+                fHandledEvents &= vgdrvGetAllowedEventMaskForSession(pDevExt, pWait->pSession);
+            if (fHandledEvents)
+            {
+                pWait->fResEvents = pWait->fReqEvents & fEvents & fHandledEvents;
+                fEvents &= ~pWait->fResEvents;
+                RTListNodeRemove(&pWait->ListNode);
+#ifdef VBOXGUEST_USE_DEFERRED_WAKE_UP
+                RTListAppend(&pDevExt->WakeUpList, &pWait->ListNode);
+#else
+                RTListAppend(&pDevExt->WokenUpList, &pWait->ListNode);
+                rc |= RTSemEventMultiSignal(pWait->Event);
+#endif
+                if (!fEvents)
+                    break;
+            }
+        }
+    }
+
+    ASMAtomicWriteU32(&pDevExt->f32PendingEvents, fEvents);
+    return rc;
+}
+
+
+/**
+ * Simply checks whether the IRQ is ours or not, does not do any interrupt
+ * procesing.
+ *
+ * @returns true if it was our interrupt, false if it wasn't.
+ * @param   pDevExt     The VBoxGuest device extension.
+ */
+bool VGDrvCommonIsOurIRQ(PVBOXGUESTDEVEXT pDevExt)
+{
+    VMMDevMemory volatile *pVMMDevMemory;
+    bool fOurIrq;
+
+    RTSpinlockAcquire(pDevExt->EventSpinlock);
+    pVMMDevMemory = pDevExt->pVMMDevMemory;
+    fOurIrq = pVMMDevMemory ? pVMMDevMemory->V.V1_04.fHaveEvents : false;
+    RTSpinlockRelease(pDevExt->EventSpinlock);
+
+    return fOurIrq;
+}
+
+
+/**
+ * Common interrupt service routine.
+ *
+ * This deals with events and with waking up thread waiting for those events.
+ *
+ * @returns true if it was our interrupt, false if it wasn't.
+ * @param   pDevExt     The VBoxGuest device extension.
+ */
+bool VGDrvCommonISR(PVBOXGUESTDEVEXT pDevExt)
+{
+    VMMDevEvents volatile  *pReq;
+    bool                    fMousePositionChanged = false;
+    int                     rc                    = 0;
+    VMMDevMemory volatile  *pVMMDevMemory;
+    bool                    fOurIrq;
+
+    /*
+     * Make sure we've initialized the device extension.
+     */
+    if (RT_LIKELY(pDevExt->fHostFeatures & VMMDEV_HVF_FAST_IRQ_ACK))
+        pReq = NULL;
+    else if (RT_LIKELY((pReq = pDevExt->pIrqAckEvents) != NULL))
+    { /* likely */ }
+    else
+        return false;
+
+    /*
+     * Enter the spinlock and check if it's our IRQ or not.
+     */
+    RTSpinlockAcquire(pDevExt->EventSpinlock);
+    pVMMDevMemory = pDevExt->pVMMDevMemory;
+    fOurIrq = pVMMDevMemory ? pVMMDevMemory->V.V1_04.fHaveEvents : false;
+    if (fOurIrq)
+    {
+        /*
+         * Acknowledge events.
+         * We don't use VbglR0GRPerform here as it may take another spinlocks.
+         */
+        uint32_t fEvents;
+        if (!pReq)
+        {
+            fEvents = ASMInU32(pDevExt->IOPortBase + VMMDEV_PORT_OFF_REQUEST_FAST);
+            ASMCompilerBarrier();   /* paranoia */
+            rc = fEvents != UINT32_MAX ? VINF_SUCCESS : VERR_INTERNAL_ERROR;
+        }
+        else
+        {
+            pReq->header.rc = VERR_INTERNAL_ERROR;
+            pReq->events    = 0;
+            ASMCompilerBarrier();
+            ASMOutU32(pDevExt->IOPortBase + VMMDEV_PORT_OFF_REQUEST, (uint32_t)pDevExt->PhysIrqAckEvents);
+            ASMCompilerBarrier();   /* paranoia */
+            fEvents = pReq->events;
+            rc = pReq->header.rc;
+        }
+        if (RT_SUCCESS(rc))
+        {
+            Log3(("VGDrvCommonISR: acknowledge events succeeded %#RX32\n", fEvents));
+
+            /*
+             * VMMDEV_EVENT_MOUSE_POSITION_CHANGED can only be polled for.
+             */
+            if (fEvents & VMMDEV_EVENT_MOUSE_POSITION_CHANGED)
+            {
+                fMousePositionChanged = true;
+                fEvents &= ~VMMDEV_EVENT_MOUSE_POSITION_CHANGED;
+#if !defined(VBOXGUEST_MOUSE_NOTIFY_CAN_PREEMPT)
+                if (pDevExt->pfnMouseNotifyCallback)
+                    pDevExt->pfnMouseNotifyCallback(pDevExt->pvMouseNotifyCallbackArg);
+#endif
+            }
+
+#ifdef VBOX_WITH_HGCM
+            /*
+             * The HGCM event/list is kind of different in that we evaluate all entries.
+             */
+            if (fEvents & VMMDEV_EVENT_HGCM)
+            {
+                PVBOXGUESTWAIT pWait;
+                PVBOXGUESTWAIT pSafe;
+                RTListForEachSafe(&pDevExt->HGCMWaitList, pWait, pSafe, VBOXGUESTWAIT, ListNode)
+                {
+                    if (pWait->pHGCMReq->fu32Flags & VBOX_HGCM_REQ_DONE)
+                    {
+                        pWait->fResEvents = VMMDEV_EVENT_HGCM;
+                        RTListNodeRemove(&pWait->ListNode);
+# ifdef VBOXGUEST_USE_DEFERRED_WAKE_UP
+                        RTListAppend(&pDevExt->WakeUpList, &pWait->ListNode);
+# else
+                        RTListAppend(&pDevExt->WokenUpList, &pWait->ListNode);
+                        rc |= RTSemEventMultiSignal(pWait->Event);
+# endif
+                    }
+                }
+                fEvents &= ~VMMDEV_EVENT_HGCM;
+            }
+#endif
+
+            /*
+             * Normal FIFO waiter evaluation.
+             */
+            rc |= vgdrvDispatchEventsLocked(pDevExt, fEvents);
+        }
+        else /* something is serious wrong... */
+            Log(("VGDrvCommonISR: acknowledge events failed rc=%Rrc (events=%#x)!!\n", rc, fEvents));
+    }
+    else
+        Log3(("VGDrvCommonISR: not ours\n"));
+
+    RTSpinlockRelease(pDevExt->EventSpinlock);
+
+    /*
+     * Execute the mouse notification callback here if it cannot be executed while
+     * holding the interrupt safe spinlock, see @bugref{8639}.
+     */
+#if defined(VBOXGUEST_MOUSE_NOTIFY_CAN_PREEMPT) && !defined(RT_OS_WINDOWS) /* (Windows does this in the Dpc callback) */
+    if (   fMousePositionChanged
+        && pDevExt->pfnMouseNotifyCallback)
+        pDevExt->pfnMouseNotifyCallback(pDevExt->pvMouseNotifyCallbackArg);
+#endif
+
+#if defined(VBOXGUEST_USE_DEFERRED_WAKE_UP) && !defined(RT_OS_WINDOWS)
+    /*
+     * Do wake-ups.
+     * Note. On Windows this isn't possible at this IRQL, so a DPC will take
+     *       care of it.  Same on darwin, doing it in the work loop callback.
+     */
+    VGDrvCommonWaitDoWakeUps(pDevExt);
+#endif
+
+    /*
+     * Work the poll and async notification queues on OSes that implements that.
+     * (Do this outside the spinlock to prevent some recursive spinlocking.)
+     */
+    if (fMousePositionChanged)
+    {
+        ASMAtomicIncU32(&pDevExt->u32MousePosChangedSeq);
+        VGDrvNativeISRMousePollEvent(pDevExt);
+    }
+
+    AssertMsg(rc == 0, ("rc=%#x (%d)\n", rc, rc));
+    return fOurIrq;
+}
diff --git a/src/VBox/Additions/common/VBoxGuest/VBoxGuestA-os2.asm b/src/VBox/Additions/common/VBoxGuest/VBoxGuestA-os2.asm
new file mode 100644
index 00000000..12df6b42
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/VBoxGuestA-os2.asm
@@ -0,0 +1,1679 @@
+; $Id: VBoxGuestA-os2.asm $
+;; @file
+; VBoxGuest - OS/2 assembly file, the first file in the link.
+;
+
+;
+; Copyright (C) 2007-2023 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
+;-----------------------------------------------------------------------------
+; This code is based on:
+;
+; VBoxDrv - OS/2 assembly file, the first file in the link.
+;
+; Copyright (c) 2007-2010 knut st. osmundsen <bird-src-spam@anduin.net>
+;
+; Permission is hereby granted, free of charge, to any person
+; obtaining a copy of this software and associated documentation
+; files (the "Software"), to deal in the Software without
+; restriction, including without limitation the rights to use,
+; copy, modify, merge, publish, distribute, sublicense, and/or sell
+; copies of the Software, and to permit persons to whom the
+; Software is furnished to do so, subject to the following
+; conditions:
+;
+; The above copyright notice and this permission notice shall be
+; included in all copies or substantial portions of the Software.
+;
+; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+; EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+; OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+; NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+; HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+; WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+; FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+; OTHER DEALINGS IN THE SOFTWARE.
+;
+
+
+;*******************************************************************************
+;* Header Files                                                                *
+;*******************************************************************************
+%define RT_INCL_16BIT_SEGMENTS
+%include "iprt/asmdefs.mac"
+%include "iprt/err.mac"
+%include "VBox/VBoxGuest.mac"
+
+
+;*******************************************************************************
+;* Structures and Typedefs                                                     *
+;*******************************************************************************
+;;
+; Request packet header.
+struc PKTHDR
+    .cb     resb 1
+    .unit   resb 1
+    .cmd    resb 1
+    .status resw 1
+    .res1   resd 1
+    .link   resd 1
+endstruc
+
+
+;;
+; Init request packet - input.
+struc PKTINITIN
+    .cb     resb 1
+    .unit   resb 1
+    .cmd    resb 1
+    .status resw 1
+    .res1   resd 1
+    .link   resd 1
+
+    .data_1 resb 1
+    .fpfnDevHlp resd 1
+    .fpszArgs   resd 1
+    .data_2 resb 1
+endstruc
+
+;;
+; Init request packet - output.
+struc PKTINITOUT
+    .cb     resb 1
+    .unit   resb 1
+    .cmd    resb 1
+    .status resw 1
+    .res1   resd 1
+    .link   resd 1
+
+    .cUnits resb 1                      ; block devs only.
+    .cbCode16 resw 1
+    .cbData16 resw 1
+    .fpaBPBs  resd 1                    ; block devs only.
+    .data_2 resb 1
+endstruc
+
+;;
+; Open request packet.
+struc PKTOPEN
+    .cb     resb 1
+    .unit   resb 1
+    .cmd    resb 1
+    .status resw 1
+    .res1   resd 1
+    .link   resd 1
+    .sfn    resw 1
+endstruc
+
+;;
+; Close request packet.
+struc PKTCLOSE
+    .cb     resb 1
+    .unit   resb 1
+    .cmd    resb 1
+    .status resw 1
+    .res1   resd 1
+    .link   resd 1
+    .sfn    resw 1
+endstruc
+
+;;
+; IOCtl request packet.
+struc PKTIOCTL
+    .cb     resb 1
+    .unit   resb 1
+    .cmd    resb 1
+    .status resw 1
+    .res1   resd 1
+    .link   resd 1
+
+    .cat    resb 1
+    .fun    resb 1
+    .pParm  resd 1
+    .pData  resd 1
+    .sfn    resw 1
+    .cbParm resw 1
+    .cbData resw 1
+endstruc
+
+;;
+; Read/Write request packet
+struc PKTRW
+    .cb     resb 1
+    .unit   resb 1
+    .cmd    resb 1
+    .status resw 1
+    .res1   resd 1
+    .link   resd 1
+
+    .media  resb 1
+    .PhysTrans resd 1
+    .cbTrans resw 1
+    .start  resd 1
+    .sfn    resw 1
+endstruc
+
+
+;*******************************************************************************
+;*  Defined Constants And Macros                                               *
+;*******************************************************************************
+; Some devhdr.inc stuff.
+%define DEVLEV_3                0180h
+%define DEV_30                  0800h
+%define DEV_IOCTL               4000h
+%define DEV_CHAR_DEV            8000h
+
+%define DEV_16MB                0002h
+%define DEV_IOCTL2              0001h
+
+; Some dhcalls.h stuff.
+%define DevHlp_VirtToLin        05bh
+%define DevHlp_SAVE_MESSAGE     03dh
+%define DevHlp_EOI              031h
+%define DevHlp_SetIRQ           01bh
+%define DevHlp_PhysToVirt       015h
+
+; Fast IOCtl category, also defined in VBoxGuest.h
+%define VBGL_IOCTL_CATEGORY_FAST    0c3h
+
+;;
+; Got some nasm/link trouble, so emit the stuff ourselves.
+; @param    %1      Must be a GLOBALNAME.
+%macro JMP32TO16 1
+    ;jmp far dword NAME(%1) wrt CODE16
+    db      066h
+    db      0eah
+    dw      NAME(%1) wrt CODE16
+    dw      CODE16
+%endmacro
+
+;;
+; Got some nasm/link trouble, so emit the stuff ourselves.
+; @param    %1      Must be a GLOBALNAME.
+%macro JMP16TO32 1
+    ;jmp far dword NAME(%1) wrt FLAT
+    db      066h
+    db      0eah
+    dd      NAME(%1) ;wrt FLAT
+    dw      TEXT32 wrt FLAT
+%endmacro
+
+
+;*******************************************************************************
+;* External Symbols                                                            *
+;*******************************************************************************
+segment CODE16
+extern DOS16OPEN
+extern DOS16CLOSE
+extern DOS16WRITE
+extern DOS16DEVIOCTL2
+segment TEXT32
+extern KernThunkStackTo32
+extern KernThunkStackTo16
+
+extern NAME(vgdrvOS2Init)
+extern NAME(vgdrvOS2Open)
+extern NAME(vgdrvOS2Close)
+extern NAME(vgdrvOS2IOCtl)
+extern NAME(vgdrvOS2IOCtlFast)
+extern NAME(vgdrvOS2IDCConnect)
+extern NAME(VGDrvOS2IDCService)
+extern NAME(vgdrvOS2ISR)
+
+
+segment DATA16
+
+;;
+; Device headers. The first one is the one we'll be opening and the
+; latter is only used for 32-bit initialization.
+GLOBALNAME g_VBoxGuestHdr1
+    dw  NAME(g_VBoxGuestHdr2) wrt DATA16            ; NextHeader.off
+    dw  DATA16                                      ; NextHeader.sel
+    dw  DEVLEV_3 | DEV_30 | DEV_CHAR_DEV | DEV_IOCTL; SDevAtt
+    dw  NAME(VGDrvOS2Entrypoint) wrt CODE16         ; StrategyEP
+    dw  NAME(VGDrvOS2IDC) wrt CODE16                ; IDCEP
+    db  'vboxgst$'                                  ; DevName
+    dw  0                                           ; SDevProtCS
+    dw  0                                           ; SDevProtDS
+    dw  0                                           ; SDevRealCS
+    dw  0                                           ; SDevRealDS
+    dd  DEV_16MB | DEV_IOCTL2                       ; SDevCaps
+
+align 4
+GLOBALNAME g_VBoxGuestHdr2
+    dd  0ffffffffh                                  ; NextHeader (NIL)
+    dw  DEVLEV_3 | DEV_30 | DEV_CHAR_DEV            ; SDevAtt
+    dw  NAME(vgdrvOS2InitEntrypoint) wrt CODE16     ; StrategyEP
+    dw  0                                           ; IDCEP
+    db  'vboxgs1$'                                  ; DevName
+    dw  0                                           ; SDevProtCS
+    dw  0                                           ; SDevProtDS
+    dw  0                                           ; SDevRealCS
+    dw  0                                           ; SDevRealDS
+    dd  DEV_16MB | DEV_IOCTL2                       ; SDevCaps
+
+
+;; Tristate 32-bit initialization indicator [0 = need init, -1 = init failed, 1 init succeeded].
+; Check in the open path of the primary driver. The secondary driver will
+; open the primary one during it's init and thereby trigger the 32-bit init.
+GLOBALNAME g_fInitialized
+    db 0
+
+align 4
+;; Pointer to the device helper service routine
+; This is set during the initialization of the 2nd device driver.
+GLOBALNAME g_fpfnDevHlp
+    dd 0
+
+
+;; vgdrvFindAdapter Output
+; @{
+
+;; The MMIO base of the VMMDev.
+GLOBALNAME g_PhysMMIOBase
+    dd 0
+;; The size of the MMIO memory of the VMMDev.
+GLOBALNAME g_cbMMIO
+    dd 0
+;; The I/O port base of the VMMDev.
+GLOBALNAME g_IOPortBase
+    dw 0
+;; The VMMDev Interrupt Line.
+GLOBALNAME g_bInterruptLine
+    db 0
+;; The PCI bus number returned by Find PCI Device.
+GLOBALNAME g_bPciBusNo
+    db 0
+;; The PCI Device No / Function Number returned by Find PCI Device.
+; (The upper 5 bits is the number, and the lower 3 the function.)
+GLOBALNAME g_bPciDevFunNo
+    db 0
+;; Flag that is set by the vboxgst$ init routine if VMMDev was found.
+; Both init routines must refuse loading the driver if the
+; device cannot be located.
+GLOBALNAME g_fFoundAdapter
+    db 0
+;; @}
+
+
+%ifdef DEBUG_READ
+;; Where we write to the log.
+GLOBALNAME g_offLogHead
+    dw 0
+;; Where we read from the log.
+GLOBALNAME g_offLogTail
+    dw 0
+;; The size of the log. (power of two!)
+%define LOG_SIZE 16384
+GLOBALNAME g_cchLogMax
+    dw LOG_SIZE
+;; The log buffer.
+GLOBALNAME g_szLog
+    times LOG_SIZE db 0
+%endif ; DEBUG_READ
+
+
+;
+; The init data.
+;
+segment DATA16_INIT
+GLOBALNAME g_InitDataStart
+
+;; Far pointer to the device argument.
+g_fpszArgs:
+    dd      0
+
+%if 0
+;; Message table for the Save_Message device helper.
+GLOBALNAME g_MsgTab
+    dw  1178                                        ; MsgId - 'MSG_REPLACEMENT_STRING'.
+    dw  1                                           ; cMsgStrings
+    dw  NAME(g_szInitText)                          ; MsgStrings[0]
+    dw  seg NAME(g_szInitText)
+%else
+;; Far pointer to DOS16WRITE (corrected set before called).
+; Just a temporary hack to work around a wlink issue.
+GLOBALNAME g_fpfnDos16Write
+    dw  DOS16WRITE
+    dw  seg DOS16WRITE
+%endif
+
+;; Size of the text currently in the g_szInitText buffer.
+GLOBALNAME g_cchInitText
+    dw      0
+;; The max size of text that can fit into the g_szInitText buffer.
+GLOBALNAME g_cchInitTextMax
+    dw      512
+;; The init text buffer.
+GLOBALNAME g_szInitText
+    times 512 db 0
+
+;; Message string that's written on failure.
+g_achLoadFailureMsg1:
+    db      0dh,0ah,'VBoxGuest: load failure no. '
+g_cchLoadFailureMsg1 EQU $ - g_achLoadFailureMsg1
+g_achLoadFailureMsg2:
+    db      '!',0dh,0ah
+g_cchLoadFailureMsg2 EQU $ - g_achLoadFailureMsg2
+
+
+;
+; The 16-bit code segment.
+;
+segment CODE16
+
+
+;;
+; The strategy entry point (vboxdrv$).
+;
+; ss:bx -> request packet
+; ds:si -> device header
+;
+; Can clobber any registers it likes except SP.
+;
+BEGINPROC VGDrvOS2Entrypoint
+    push    ebp
+    mov     ebp, esp
+    push    es                                      ; bp - 2
+    push    bx                                      ; bp - 4
+    and     sp, 0fffch
+
+    ;
+    ; Check for the most frequent first.
+    ;
+    cmp     byte [es:bx + PKTHDR.cmd], 10h          ; Generic IOCtl
+    jne near vgdrvOS2EP_NotGenIOCtl
+
+
+    ;
+    ; Generic I/O Control Request.
+    ;
+vgdrvOS2EP_GenIOCtl:
+
+    ; Fast IOCtl?
+    cmp     byte [es:bx + PKTIOCTL.cat], VBGL_IOCTL_CATEGORY_FAST
+    jne     vgdrvOS2EP_GenIOCtl_Other
+
+    ;
+    ; Fast IOCtl.
+    ;   DECLASM(int) vgdrvOS2IOCtlFast(uint16_t sfn, uint8_t iFunction, uint16_t *pcbParm)
+    ;
+vgdrvOS2EP_GenIOCtl_Fast:
+    mov     ax, [es:bx + PKTIOCTL.pData + 2]        ; LDT selector to flat address.
+    shr     ax, 3
+    shl     eax, 16
+    mov     ax, [es:bx + PKTIOCTL.pData]
+    push    eax                                     ; 08h - pointer to the rc buffer.
+
+    ; function.
+    movzx   edx, byte [es:bx + PKTIOCTL.fun]
+    push    edx                                     ; 04h
+
+    ; system file number.
+    movzx   eax, word [es:bx + PKTIOCTL.sfn]
+    push    eax                                     ; 00h
+
+    JMP16TO32 vgdrvOS2EP_GenIOCtl_Fast_32
+segment TEXT32
+GLOBALNAME vgdrvOS2EP_GenIOCtl_Fast_32
+
+    ; switch stack to 32-bit.
+    mov     ax, DATA32 wrt FLAT
+    mov     ds, ax
+    mov     es, ax
+    call    KernThunkStackTo32
+
+    ; call the C code (don't cleanup the stack).
+    call    NAME(vgdrvOS2IOCtlFast)
+
+    ; switch back the stack.
+    push    eax
+    call    KernThunkStackTo16
+    pop     eax
+
+    JMP32TO16 vgdrvOS2EP_GenIOCtl_Fast_32
+segment CODE16
+GLOBALNAME vgdrvOS2EP_GenIOCtl_Fast_16
+
+    les     bx, [bp - 4]                            ; Reload the packet pointer.
+    or      eax, eax
+    jnz near vgdrvOS2EP_GeneralFailure
+
+    ; setup output stuff.
+    mov     edx, esp
+    mov     eax, [ss:edx + 0ch]                     ; output sizes.
+    mov     [es:bx + PKTIOCTL.cbParm], eax          ; update cbParm and cbData.
+    mov     word [es:bx + PKTHDR.status], 00100h    ; done, ok.
+
+    mov     sp, bp
+    pop     ebp
+    retf
+
+    ;
+    ; Other IOCtl (slow)
+    ;
+vgdrvOS2EP_GenIOCtl_Other:
+    mov     eax, [es:bx +  PKTIOCTL.cbParm]         ; Load cbParm and cbData
+    push    eax                                     ; 1eh - in/out data size.
+                                                    ; 1ch - in/out parameter size.
+    push    edx                                     ; 18h - pointer to data size (filled in later).
+    push    ecx                                     ; 14h - pointer to param size (filled in later).
+
+    ; pData (convert to flat 32-bit)
+    mov     ax,  word [es:bx + PKTIOCTL.pData + 2]  ; selector
+    cmp     ax, 3                                   ; <= 3 -> nil selector...
+    jbe     .no_data
+    movzx   esi, word [es:bx + PKTIOCTL.pData]      ; offset
+    mov     dl, DevHlp_VirtToLin
+    call far [NAME(g_fpfnDevHlp)]
+    jc near vgdrvOS2EP_GeneralFailure
+    jmp     .finish_data
+.no_data:
+    xor     eax, eax
+.finish_data:
+    push    eax                                     ; 10h
+
+    ; pParm (convert to flat 32-bit)
+    mov     ax,  word [es:bx + PKTIOCTL.pParm + 2]  ; selector
+    cmp     ax, 3                                   ; <= 3 -> nil selector...
+    jbe     .no_parm
+    movzx   esi, word [es:bx + PKTIOCTL.pParm]      ; offset
+    mov     dl, DevHlp_VirtToLin
+    call far [NAME(g_fpfnDevHlp)]
+    jc near vgdrvOS2EP_GeneralFailure
+    jmp     .finish_parm
+.no_parm:
+    xor     eax, eax
+.finish_parm:
+    push    eax                                     ; 0ch
+
+    ; function.
+    movzx   edx, byte [es:bx + PKTIOCTL.fun]
+    push    edx                                     ; 08h
+
+    ; category.
+    movzx   ecx, byte [es:bx + PKTIOCTL.cat]
+    push    ecx                                     ; 04h
+
+    ; system file number.
+    movzx   eax, word [es:bx + PKTIOCTL.sfn]
+    push    eax                                     ; 00h
+
+    JMP16TO32 vgdrvOS2EP_GenIOCtl_Other_32
+segment TEXT32
+GLOBALNAME vgdrvOS2EP_GenIOCtl_Other_32
+
+    ; switch stack to 32-bit.
+    mov     ax, DATA32 wrt FLAT
+    mov     ds, ax
+    mov     es, ax
+    call    KernThunkStackTo32
+
+    ; update in/out parameter pointers
+    lea     eax, [esp + 1ch]
+    mov     [esp + 14h], eax
+    lea     edx, [esp + 1eh]
+    mov     [esp + 18h], edx
+
+    ; call the C code (don't cleanup the stack).
+    call    NAME(vgdrvOS2IOCtl)
+
+    ; switch back the stack.
+    push    eax
+    call    KernThunkStackTo16
+    pop     eax
+
+    JMP32TO16 vgdrvOS2EP_GenIOCtl_Other_16
+segment CODE16
+GLOBALNAME vgdrvOS2EP_GenIOCtl_Other_16
+
+    les     bx, [bp - 4]                            ; Reload the packet pointer.
+    or      eax, eax
+    jnz near vgdrvOS2EP_GeneralFailure
+
+    ; setup output stuff.
+    mov     edx, esp
+    mov     eax, [ss:edx + 1ch]                     ; output sizes.
+    mov     [es:bx + PKTIOCTL.cbParm], eax          ; update cbParm and cbData.
+    mov     word [es:bx + PKTHDR.status], 00100h    ; done, ok.
+
+    mov     sp, bp
+    pop     ebp
+    retf
+
+
+    ;
+    ; Less Performance Critical Requests.
+    ;
+vgdrvOS2EP_NotGenIOCtl:
+    cmp     byte [es:bx + PKTHDR.cmd], 0dh          ; Open
+    je      vgdrvOS2EP_Open
+    cmp     byte [es:bx + PKTHDR.cmd], 0eh          ; Close
+    je      vgdrvOS2EP_Close
+    cmp     byte [es:bx + PKTHDR.cmd], 00h          ; Init
+    je      vgdrvOS2EP_Init
+%ifdef DEBUG_READ
+    cmp     byte [es:bx + PKTHDR.cmd], 04h          ; Read
+    je near vgdrvOS2EP_Read
+%endif
+    jmp near vgdrvOS2EP_NotSupported
+
+
+    ;
+    ; Open Request. w/ ring-0 init.
+    ;
+vgdrvOS2EP_Open:
+    cmp     byte [NAME(g_fInitialized)], 1
+    jne     vgdrvOS2EP_OpenOther
+
+    ; First argument, the system file number.
+    movzx   eax, word [es:bx + PKTOPEN.sfn]
+    push    eax
+
+    JMP16TO32 vgdrvOS2EP_Open_32
+segment TEXT32
+GLOBALNAME vgdrvOS2EP_Open_32
+
+    ; switch stack to 32-bit.
+    mov     ax, DATA32 wrt FLAT
+    mov     ds, ax
+    mov     es, ax
+    call    KernThunkStackTo32
+
+    ; call the C code.
+    call    NAME(vgdrvOS2Open)
+
+    ; switch back the stack.
+    push    eax
+    call    KernThunkStackTo16
+    pop     eax
+
+    JMP32TO16 vgdrvOS2EP_Open_16
+segment CODE16
+GLOBALNAME vgdrvOS2EP_Open_16
+
+    les     bx, [bp - 4]                            ; Reload the packet pointer.
+    or      eax, eax
+    jnz near vgdrvOS2EP_GeneralFailure
+    mov     word [es:bx + PKTHDR.status], 00100h    ; done, ok.
+    jmp near vgdrvOS2EP_Done
+
+    ; Initializing or failed init?
+vgdrvOS2EP_OpenOther:
+    cmp     byte [NAME(g_fInitialized)], 0
+    jne     vgdrvOS2EP_OpenFailed
+
+    mov     byte [NAME(g_fInitialized)], -1
+    call    NAME(vgdrvRing0Init)
+    cmp     byte [NAME(g_fInitialized)], 1
+    je      vgdrvOS2EP_Open
+
+vgdrvOS2EP_OpenFailed:
+    mov     word [es:bx + PKTHDR.status], 0810fh    ; error, done, init failed.
+    jmp near vgdrvOS2EP_Done
+
+
+    ;
+    ; Close Request.
+    ;
+vgdrvOS2EP_Close:
+    ; First argument, the system file number.
+    movzx   eax, word [es:bx + PKTOPEN.sfn]
+    push    eax
+
+    JMP16TO32 vgdrvOS2EP_Close_32
+segment TEXT32
+GLOBALNAME vgdrvOS2EP_Close_32
+
+    ; switch stack to 32-bit.
+    mov     ax, DATA32 wrt FLAT
+    mov     ds, ax
+    mov     es, ax
+    call    KernThunkStackTo32
+
+    ; call the C code.
+    call    NAME(vgdrvOS2Close)
+
+    ; switch back the stack.
+    push    eax
+    call    KernThunkStackTo16
+    pop     eax
+
+    JMP32TO16 vgdrvOS2EP_Close_16
+segment CODE16
+GLOBALNAME vgdrvOS2EP_Close_16
+
+    les     bx, [bp - 4]                            ; Reload the packet pointer.
+    or      eax, eax
+    jnz near vgdrvOS2EP_GeneralFailure
+    mov     word [es:bx + PKTHDR.status], 00100h    ; done, ok.
+    jmp near vgdrvOS2EP_Done
+
+
+    ;
+    ; Init Request.
+    ; Find the VMMDev adapter so we can unload the driver (and avoid trouble) if not found.
+    ;
+vgdrvOS2EP_Init:
+    call    NAME(vgdrvFindAdapter)
+    test    ax, ax
+    jz      .ok
+    mov     word [es:bx + PKTHDR.status], 0810fh    ; error, done, init failed.
+    call    NAME(vgdrvOS2InitFlushText)
+    jmp     .next
+.ok:
+    mov     word [es:bx + PKTHDR.status], 00100h    ; done, ok.
+.next:
+    mov     byte [es:bx + PKTINITOUT.cUnits], 0
+    mov     word [es:bx + PKTINITOUT.cbCode16], NAME(g_InitCodeStart) wrt CODE16
+    mov     word [es:bx + PKTINITOUT.cbData16], NAME(g_InitDataStart) wrt DATA16
+    mov     dword [es:bx + PKTINITOUT.fpaBPBs], 0
+    jmp near vgdrvOS2EP_Done
+
+
+%ifdef DEBUG_READ
+    ;
+    ; Read Request.
+    ; Return log data.
+    ;
+vgdrvOS2EP_Read:
+    ; Any log data available?
+    xor     dx, dx
+    mov     ax, [NAME(g_offLogTail)]
+    cmp     ax, [NAME(g_offLogHead)]
+    jz near .log_done
+
+    ; create a temporary mapping of the physical buffer. Docs claims it trashes nearly everything...
+    push    ebp
+    mov     cx, [es:bx + PKTRW.cbTrans]
+    push    cx
+    mov     ax, [es:bx + PKTRW.PhysTrans + 2]
+    mov     bx, [es:bx + PKTRW.PhysTrans]
+    mov     dh, 1
+    mov     dl, DevHlp_PhysToVirt
+    call far [NAME(g_fpfnDevHlp)]
+    pop     bx                                      ; bx = cbTrans
+    pop     ebp
+    jc near .log_phystovirt_failed
+                                                    ; es:di -> the output buffer.
+
+    ; setup the copy operation.
+    mov     ax, [NAME(g_offLogTail)]
+    xor     dx, dx                                  ; dx tracks the number of bytes copied.
+.log_loop:
+    mov     cx, [NAME(g_offLogHead)]
+    cmp     ax, cx
+    je      .log_done
+    jb      .log_loop_before
+    mov     cx, LOG_SIZE
+.log_loop_before:                                   ; cx = end offset
+    sub     cx, ax                                  ; cx = sequential bytes to copy.
+    cmp     cx, bx
+    jbe     .log_loop_min
+    mov     cx, bx                                  ; output buffer is smaller than available data.
+.log_loop_min:
+    mov     si, NAME(g_szLog)
+    add     si, ax                                  ; ds:si -> the log buffer.
+    add     dx, cx                                  ; update output counter
+    add     ax, cx                                  ; calc new offLogTail
+    and     ax, LOG_SIZE - 1
+    rep movsb                                       ; do the copy
+    mov     [NAME(g_offLogTail)], ax                ; commit the read.
+    jmp     .log_loop
+
+.log_done:
+    les     bx, [bp - 4]                            ; Reload the packet pointer.
+    mov     word [es:bx + PKTRW.cbTrans], dx
+    mov     word [es:bx + PKTHDR.status], 00100h    ; done, ok.
+    jmp near vgdrvOS2EP_Done
+
+.log_phystovirt_failed:
+    les     bx, [bp - 4]                            ; Reload the packet pointer.
+    jmp     vgdrvOS2EP_GeneralFailure
+%endif ; DEBUG_READ
+
+
+    ;
+    ; Return 'unknown command' error.
+    ;
+vgdrvOS2EP_NotSupported:
+    mov     word [es:bx + PKTHDR.status], 08103h    ; error, done, unknown command.
+    jmp     vgdrvOS2EP_Done
+
+    ;
+    ; Return 'general failure' error.
+    ;
+vgdrvOS2EP_GeneralFailure:
+    mov     word [es:bx + PKTHDR.status], 0810ch    ; error, done, general failure.
+    jmp     vgdrvOS2EP_Done
+
+    ;
+    ; Non-optimized return path.
+    ;
+vgdrvOS2EP_Done:
+    mov     sp, bp
+    pop     ebp
+    retf
+ENDPROC VGDrvOS2Entrypoint
+
+
+;;
+; The helper device entry point.
+;
+; This is only used to do the DosOpen on the main driver so we can
+; do ring-3 init and report failures.
+;
+GLOBALNAME vgdrvOS2InitEntrypoint
+    ; The only request we're servicing is the 'init' one.
+    cmp     word [es:bx + PKTHDR.cmd], 0
+    je near NAME(vgdrvOS2InitEntrypointServiceInitReq)
+
+    ; Ok, it's not the init request, just fail it.
+    mov     word [es:bx + PKTHDR.status], 08103h    ; error, done, unknown command.
+    retf
+
+
+;;
+; The OS/2 IDC entry point.
+;
+; This is only used to setup connection, the returned structure
+; will provide the entry points that we'll be using.
+;
+; @cproto  void far __cdecl VGDrvOS2IDC(VBOXGUESTOS2IDCCONNECT far *fpConnectInfo);
+;
+; @param   fpConnectInfo   [bp + 8]     Pointer to an VBOXGUESTOS2IDCCONNECT structure.
+;
+GLOBALNAME VGDrvOS2IDC
+    push    ebp                         ; bp -  0h
+    mov     ebp, esp
+    ; save everything we might touch.
+    push    es                          ; bp -  2h
+    push    ds                          ; bp -  4h
+    push    eax                         ; bp -  8h
+    push    ebx                         ; bp - 0ch
+    push    ecx                         ; bp - 10h
+    push    edx                         ; bp - 14h
+    and     sp, 0fffch
+
+    JMP16TO32 VGDrvOS2IDC_32
+segment TEXT32
+GLOBALNAME VGDrvOS2IDC_32
+
+    ; switch stack to 32-bit.
+    mov     ax, DATA32 wrt FLAT
+    mov     ds, ax
+    mov     es, ax
+    call    KernThunkStackTo32
+
+    ; call the C code.
+    call    NAME(vgdrvOS2IDCConnect)
+
+    ;
+    ; Load the return buffer address into ds:ebx and setup the buffer.
+    ; (eax == u32Session)
+    ;
+    mov     cx, [ebp + 08h + 2]
+    mov     ds, cx
+    movzx   ebx, word [ebp + 08h]
+
+    mov     dword [ebx + VBGLOS2ATTACHDD.u32Version       ], VBGL_IOC_VERSION
+    mov     dword [ebx + VBGLOS2ATTACHDD.u32Session       ], eax
+    mov     dword [ebx + VBGLOS2ATTACHDD.pfnServiceEP     ], NAME(VGDrvOS2IDCService)
+    mov     word  [ebx + VBGLOS2ATTACHDD.fpfnServiceEP    ], NAME(VGDrvOS2IDCService16) wrt CODE16
+    mov     word  [ebx + VBGLOS2ATTACHDD.fpfnServiceEP + 2], CODE16
+    mov     word  [ebx + VBGLOS2ATTACHDD.fpfnServiceAsmEP ], NAME(VGDrvOS2IDCService16Asm) wrt CODE16
+    mov     word  [ebx + VBGLOS2ATTACHDD.fpfnServiceAsmEP+2],CODE16
+
+    mov     ax, DATA32 wrt FLAT
+    mov     ds, ax
+
+    ; switch back the stack.
+    call    KernThunkStackTo16
+
+    JMP32TO16 VGDrvOS2IDC_16
+segment CODE16
+GLOBALNAME VGDrvOS2IDC_16
+
+    ; restore.
+    lea     sp, [bp - 14h]
+    pop     edx
+    pop     ecx
+    pop     ebx
+    pop     eax
+    pop     ds
+    pop     es
+    pop     ebp
+    retf
+ENDPROC VGDrvOS2IDC
+
+
+;;
+; The 16-bit IDC entry point, cdecl.
+;
+; All this does is thunking the request into something that fits
+; the 32-bit IDC service routine.
+;
+;
+; @returns VBox status code.
+; @param   u32Session          bp +  8h - The above session handle.
+; @param   iFunction           bp + 0ch - The requested function.
+; @param   fpReqHdr            bp + 0eh - The input/output data buffer. The caller ensures that this
+;                                         cannot be swapped out, or that it's acceptable to take a
+;                                         page in fault in the current context. If the request doesn't
+;                                         take input or produces output, passing NULL is okay.
+; @param   cbReq               bp + 12h - The size of the data buffer.
+;
+; @cproto long far __cdecl VGDrvOS2IDCService16(uint32_t u32Session, uint16_t iFunction, void far *fpReqHdr, uint16_t cbReq);
+;
+GLOBALNAME VGDrvOS2IDCService16
+    push    ebp                         ; bp -  0h
+    mov     ebp, esp
+    push    es                          ; bp -  2h
+    push    ds                          ; bp -  4h
+    push    ecx                         ; bp -  8h
+    push    edx                         ; bp - 0ch
+    push    esi                         ; bp - 10h
+    and     sp, 0fffch                  ; align the stack.
+
+    ; locals
+    push    dword 0                     ; esp + 18h (dd): cbDataReturned
+
+    ; load our ds (for g_fpfnDevHlp).
+    mov     ax, DATA16
+    mov     ds, ax
+
+    ;
+    ; Create the call frame before switching.
+    ;
+    movzx   ecx, word [bp + 12h]
+    push    ecx                         ; esp + 10h:    cbData
+
+    ; thunk data argument if present.
+    mov     ax,  [bp + 0eh + 2]         ; selector
+    cmp     ax, 3                       ; <= 3 -> nil selector...
+    jbe     .no_data
+    movzx   esi, word [bp + 0eh]        ; offset
+    mov     dl, DevHlp_VirtToLin
+    call far [NAME(g_fpfnDevHlp)]
+    jc near VGDrvOS2IDCService16_InvalidPointer
+    jmp     .finish_data
+.no_data:
+    xor     eax, eax
+.finish_data:
+    push    eax                         ; esp + 08h:    pvData
+    movzx   edx, word [bp + 0ch]
+    push    edx                         ; esp + 04h:    iFunction
+    mov     ecx, [bp + 08h]
+    push    ecx                         ; esp + 00h:    u32Session
+
+    JMP16TO32 VGDrvOS2IDCService16_32
+segment TEXT32
+GLOBALNAME VGDrvOS2IDCService16_32
+
+    ; switch stack to 32-bit.
+    mov     ax, DATA32 wrt FLAT
+    mov     ds, ax
+    mov     es, ax
+    call    KernThunkStackTo32
+
+    ; call the C code (don't cleanup the stack).
+    call    NAME(VGDrvOS2IDCService)
+
+    ; switch back the stack.
+    push    eax
+    call    KernThunkStackTo16
+    pop     eax
+
+    JMP32TO16 VGDrvOS2IDCService16_16
+segment CODE16
+GLOBALNAME VGDrvOS2IDCService16_16
+
+VGDrvOS2IDCService16_Done:
+    lea     sp, [bp - 10h]
+    pop     esi
+    pop     edx
+    pop     ecx
+    pop     ds
+    pop     es
+    pop     ebp
+    retf
+
+VGDrvOS2IDCService16_InvalidPointer:
+    mov     ax, VERR_INVALID_POINTER
+    jmp     VGDrvOS2IDCService16_Done
+ENDPROC VGDrvOS2IDCService16
+
+
+;;
+; The 16-bit IDC entry point, register based.
+;
+; This is just a wrapper around VGDrvOS2IDCService16 to simplify
+; calls from 16-bit assembly code.
+;
+; @returns ax: VBox status code; cx: The amount of data returned.
+;
+; @param   u32Session          eax   - The above session handle.
+; @param   iFunction           dl    - The requested function.
+; @param   pvData              es:bx - The input/output data buffer.
+; @param   cbData              cx    - The size of the data buffer.
+;
+GLOBALNAME VGDrvOS2IDCService16Asm
+    push    ebp                         ; bp - 0h
+    mov     ebp, esp
+    push    edx                         ; bp - 4h
+
+    push    cx                          ; cbData
+    push    es
+    xor     dh, dh
+    push    dx
+    push    eax
+    call    NAME(VGDrvOS2IDCService16)
+
+    mov     cx, [es:bx + VBGLREQHDR.cbOut]
+
+    mov     edx, [bp - 4]
+    mov     esp, ebp
+    pop     ebp
+    retf
+ENDPROC VGDrvOS2IDCService16Asm
+
+
+
+;;
+; The 16-bit interrupt service routine.
+;
+; OS/2 saves all registers according to the docs, although it doesn't say whether
+; this includes the 32-bit parts. Since it doesn't cost much to be careful, save
+; everything.
+;
+; @returns  CF=0 if it's our interrupt, CF=1 it it isn't.
+;
+;
+GLOBALNAME vgdrvOS2ISR16
+    push    ebp
+    mov     ebp, esp
+    pushf                               ; bp - 02h
+    cli
+    push    eax                         ; bp - 06h
+    push    edx                         ; bp - 0ah
+    push    ebx                         ; bp - 0eh
+    push    ds                          ; bp - 10h
+    push    es                          ; bp - 12h
+    push    ecx                         ; bp - 16h
+    push    esi                         ; bp - 1ah
+    push    edi                         ; bp - 1eh
+
+    and     sp, 0fff0h                  ; align the stack (16-bytes make GCC extremely happy).
+
+    JMP16TO32 vgdrvOS2ISR16_32
+segment TEXT32
+GLOBALNAME vgdrvOS2ISR16_32
+
+    mov     ax, DATA32 wrt FLAT
+    mov     ds, ax
+    mov     es, ax
+
+    call    KernThunkStackTo32
+
+    call    NAME(vgdrvOS2ISR)
+    mov     ebx, eax
+
+    call    KernThunkStackTo16
+
+    JMP32TO16 vgdrvOS2ISR16_16
+segment CODE16
+GLOBALNAME vgdrvOS2ISR16_16
+
+    lea     sp, [bp - 1eh]
+    pop     edi
+    pop     esi
+    pop     ecx
+    pop     es
+    pop     ds
+    test    bl, 0ffh
+    jnz     .our
+    pop     ebx
+    pop     edx
+    pop     eax
+    popf
+    pop     ebp
+    stc
+    retf
+
+    ;
+    ; Do EIO.
+    ;
+.our:
+    mov     al, [NAME(g_bInterruptLine)]
+    mov     dl, DevHlp_EOI
+    call far [NAME(g_fpfnDevHlp)]
+
+    pop     ebx
+    pop     edx
+    pop     eax
+    popf
+    pop     ebp
+    clc
+    retf
+ENDPROC vgdrvOS2ISR16
+
+
+
+
+
+
+;
+; The 32-bit text segment.
+;
+segment TEXT32
+;;
+; 32-bit worker for registering the ISR.
+;
+; @returns  0 on success, some non-zero OS/2 error code on failure.
+; @param    bIrq        [ebp + 8]       The IRQ number. (uint8_t)
+;
+GLOBALNAME vgdrvOS2DevHlpSetIRQ
+    push    ebp
+    mov     ebp, esp
+    push    ebx
+    push    ds
+
+    call    KernThunkStackTo16
+
+    movzx   ebx, byte [ebp + 8]         ; load bIrq into BX.
+
+    JMP32TO16 vgdrvOS2DevHlpSetIRQ_16
+segment CODE16
+GLOBALNAME vgdrvOS2DevHlpSetIRQ_16
+
+    mov     ax, DATA16                  ; for g_fpfnDevHlp.
+    mov     ds, ax
+    mov     ax, NAME(vgdrvOS2ISR16)     ; The devhlp assume it's relative to DS.
+    mov     dh, 1                       ; 1 = shared
+    mov     dl, DevHlp_SetIRQ
+    call far [NAME(g_fpfnDevHlp)]
+    jnc     .ok
+    movzx   eax, ax
+    or      eax, eax
+    jnz     .go_back
+    or      eax, 6
+    jmp     .go_back
+.ok:
+    xor     eax, eax
+
+.go_back:
+    JMP16TO32 vgdrvOS2DevHlpSetIRQ_32
+segment TEXT32
+GLOBALNAME vgdrvOS2DevHlpSetIRQ_32
+
+    pop     ds                          ; KernThunkStackTo32 ASSUMES flat DS and ES.
+
+    mov     ebx, eax
+    call    KernThunkStackTo32
+    mov     eax, ebx
+
+    pop     ebx
+    pop     ebp
+    ret
+ENDPROC vgdrvOS2DevHlpSetIRQ
+
+
+
+
+;
+; The 16-bit init code.
+;
+segment CODE16_INIT
+GLOBALNAME g_InitCodeStart
+
+;; The device name for DosOpen.
+g_szDeviceName:
+    db  '\DEV\vboxgst$', 0
+
+; icsdebug can't see where stuff starts otherwise. (kDevTest)
+int3
+int3
+int3
+int3
+int3
+int3
+
+;;
+; The Ring-3 init code.
+;
+BEGINPROC vgdrvOS2InitEntrypointServiceInitReq
+    push    ebp
+    mov     ebp, esp
+    push    es                                      ; bp - 2
+    push    sp                                      ; bp - 4
+    push    -1                                      ; bp - 6: hfOpen
+    push    0                                       ; bp - 8: usAction
+    and     sp, 0fffch
+
+    ; check for the init package.
+    cmp     word [es:bx + PKTHDR.cmd], 0
+    jne near .not_init
+
+    ; check that we found the VMMDev.
+    test    byte [NAME(g_fFoundAdapter)], 1
+    jz near .done_err
+
+    ;
+    ; Copy the data out of the init packet.
+    ;
+    mov     eax, [es:bx + PKTINITIN.fpfnDevHlp]
+    mov     [NAME(g_fpfnDevHlp)], eax
+    mov     edx, [es:bx + PKTINITIN.fpszArgs]
+    mov     [g_fpszArgs], edx
+
+    ;
+    ; Open the first driver, close it, and check status.
+    ;
+
+    ; APIRET _Pascal DosOpen(PSZ pszFname, PHFILE phfOpen, PUSHORT pusAction,
+    ;                        ULONG ulFSize, USHORT usAttr, USHORT fsOpenFlags,
+    ;                        USHORT fsOpenMode, ULONG ulReserved);
+    push    seg g_szDeviceName                      ; pszFname
+    push    g_szDeviceName
+    push    ss                                      ; phfOpen
+    lea     dx, [bp - 6]
+    push    dx
+    push    ss                                      ; pusAction
+    lea     dx, [bp - 8]
+    push    dx
+    push    dword 0                                 ; ulFSize
+    push    0                                       ; usAttr = FILE_NORMAL
+    push    1                                       ; fsOpenFlags = FILE_OPEN
+    push    00040h                                  ; fsOpenMode = OPEN_SHARE_DENYNONE | OPEN_ACCESS_READONLY
+    push    dword 0                                 ; ulReserved
+    call far DOS16OPEN
+
+    push    ax                                      ; Quickly flush any text.
+    call    NAME(vgdrvOS2InitFlushText)
+    pop     ax
+
+    or      ax, ax
+    jnz     .done_err
+
+    ; APIRET  APIENTRY DosClose(HFILE hf);
+    mov     cx, [bp - 6]
+    push    cx
+    call far DOS16CLOSE
+    or      ax, ax
+    jnz     .done_err                               ; This can't happen (I hope).
+
+    ;
+    ; Ok, we're good.
+    ;
+    mov     word [es:bx + PKTHDR.status], 00100h    ; done, ok.
+    mov     byte [es:bx + PKTINITOUT.cUnits], 0
+    mov     word [es:bx + PKTINITOUT.cbCode16], NAME(g_InitCodeStart) wrt CODE16
+    mov     word [es:bx + PKTINITOUT.cbData16], NAME(g_InitDataStart) wrt DATA16
+    mov     dword [es:bx + PKTINITOUT.fpaBPBs], 0
+    jmp     .done
+
+    ;
+    ; Init failure.
+    ;
+.done_err:
+    mov     word [es:bx + PKTHDR.status], 0810fh    ; error, done, init failed.
+    mov     byte [es:bx + PKTINITOUT.cUnits], 0
+    mov     word [es:bx + PKTINITOUT.cbCode16], 0
+    mov     word [es:bx + PKTINITOUT.cbData16], 0
+    mov     dword [es:bx + PKTINITOUT.fpaBPBs], 0
+    jmp     .done
+
+    ;
+    ; Not init, return 'unknown command'.
+    ;
+.not_init:
+    mov     word [es:bx + PKTHDR.status], 08103h    ; error, done, unknown command.
+    jmp     .done
+
+    ;
+    ; Request done.
+    ;
+.done:
+    mov     sp, bp
+    pop     ebp
+    retf
+ENDPROC vgdrvOS2InitEntrypointServiceInitReq
+
+
+;;
+; The Ring-0 init code.
+;
+BEGINPROC vgdrvRing0Init
+    push    es
+    push    esi
+    push    ebp
+    mov     ebp, esp
+    and     sp, 0fffch
+
+    ;
+    ; Thunk the argument string pointer first.
+    ;
+    movzx   esi, word [g_fpszArgs]                  ; offset
+    mov     ax, [g_fpszArgs + 2]                    ; selector
+    mov     dl, DevHlp_VirtToLin
+    call far [NAME(g_fpfnDevHlp)]
+    jc near vgdrvRing0Init_done                     ; eax is non-zero on failure (can't happen)
+    push    eax                                     ; 00h - pszArgs (for vgdrvOS2Init).
+
+    ;
+    ; Do 16-bit init?
+    ;
+
+
+    ;
+    ; Do 32-bit init
+    ;
+    JMP16TO32 vgdrvRing0Init_32
+segment TEXT32
+GLOBALNAME vgdrvRing0Init_32
+
+    ; switch stack to 32-bit.
+    mov     ax, DATA32 wrt FLAT
+    mov     ds, ax
+    mov     es, ax
+    call    KernThunkStackTo32
+
+    ; call the C code.
+    call    NAME(vgdrvOS2Init)
+
+    ; switch back the stack and reload ds.
+    push    eax
+    call    KernThunkStackTo16
+    pop     eax
+
+    mov     dx, seg NAME(g_fInitialized)
+    mov     ds, dx
+
+    JMP32TO16 vgdrvRing0Init_16
+segment CODE16_INIT
+GLOBALNAME vgdrvRing0Init_16
+
+    ; check the result and set g_fInitialized on success.
+    or      eax, eax
+    jnz     vgdrvRing0Init_done
+    mov     byte [NAME(g_fInitialized)], 1
+
+vgdrvRing0Init_done:
+    mov     sp, bp
+    pop     ebp
+    pop     esi
+    pop     es
+    ret
+ENDPROC vgdrvRing0Init
+
+
+;;
+; Flush any text in the text buffer.
+;
+BEGINPROC vgdrvOS2InitFlushText
+    push    bp
+    mov     bp, sp
+
+    ; Anything in the buffer?
+    mov     ax, [NAME(g_cchInitText)]
+    or      ax, ax
+    jz      .done
+
+%if 1
+    ; Write it to STDOUT.
+    ; APIRET  _Pascal DosWrite(HFILE hf, PVOID pvBuf, USHORT cbBuf, PUSHORT pcbBytesWritten);
+    push    ax                                      ; bp - 2 : cbBytesWritten
+    mov     cx, sp
+    push    1                                       ; STDOUT
+    push    seg NAME(g_szInitText)                  ; pvBuf
+    push    NAME(g_szInitText)
+    push    ax                                      ; cbBuf
+    push    ss                                      ; pcbBytesWritten
+    push    cx
+%if 0 ; wlink generates a non-aliased fixup here which results in 16-bit offset with the flat 32-bit selector.
+    call far DOS16WRITE
+%else
+    ; convert flat pointer to a far pointer using the tiled algorithm.
+    push    ds
+    mov     ax, DATA32 wrt FLAT
+    mov     ds, ax
+    mov     eax, g_pfnDos16Write wrt FLAT
+    movzx   eax, word [eax + 2]                     ; High word of the flat address (in DATA32).
+    shl     ax, 3
+    or      ax, 0007h
+    pop     ds
+    mov     [NAME(g_fpfnDos16Write) + 2], ax        ; Update the selector (in DATA16_INIT).
+    ; do the call
+    call far [NAME(g_fpfnDos16Write)]
+%endif
+
+%else ; alternative workaround for the wlink issue.
+    ; Use the save message devhlp.
+    push    esi
+    push    ebx
+    xor     bx, bx
+    mov     si, NAME(g_MsgTab)
+    mov     dx, seg NAME(g_MsgTab)
+    mov     ds, dx
+    mov     dl, DevHlp_SAVE_MESSAGE
+    call far [NAME(g_fpfnDevHlp)]
+    pop     ebx
+    pop     esi
+%endif
+
+    ; Empty the buffer.
+    mov     word [NAME(g_cchInitText)], 0
+    mov     byte [NAME(g_szInitText)], 0
+
+.done:
+    mov     sp, bp
+    pop     bp
+    ret
+ENDPROC vgdrvOS2InitFlushText
+
+
+;; The device name for DosOpen.
+g_szOemHlpDevName:
+    db  '\DEV\OEMHLP$', 0
+
+
+;;
+; Talks to OEMHLP$ about finding the VMMDev PCI adapter.
+;
+; On success g_fFoundAdapter is set to 1, and g_cbMMIO,
+; g_PhysMMIOBase and g_IOPortBase are initialized with
+; the PCI data.
+;
+; @returns  0 on success, non-zero on failure. (eax)
+;
+; @remark   ASSUMES DS:DATA16.
+; @uses     nothing.
+;
+BEGINPROC vgdrvFindAdapter
+    push    ebx
+    push    ecx
+    push    edx
+    push    esi
+    push    edi
+    push    ebp
+    mov     ebp, esp
+    push    -1                                      ; bp - 2: hfOpen
+%define hfOpen      bp - 2
+    push    0                                       ; bp - 4: usAction
+%define usAction    bp - 4
+    sub     sp, 20h                                 ; bp - 44: 32 byte parameter buffer.
+%define abParm      bp - 24h
+    sub     sp, 40h                                 ; bp - c4: 32 byte data buffer.
+%define abData      bp - 44h
+
+;; VBox stuff
+%define VBOX_PCI_VENDORID       080eeh
+%define VMMDEV_DEVICEID         0cafeh
+
+;; OEMHLP$ stuff.
+%define IOCTL_OEMHLP            80h
+%define OEMHLP_PCI              0bh
+%define PCI_FIND_DEVICE         1
+%define PCI_READ_CONFIG         3
+
+;; PCI stuff
+%define PCI_INTERRUPT_LINE      03ch                ;;< 8-bit RW - Interrupt line.
+%define PCI_BASE_ADDRESS_0      010h                ;;< 32-bit RW */
+%define PCI_BASE_ADDRESS_1      014h                ;;< 32-bit RW */
+
+
+%macro CallIOCtl 2
+    ; APIRET _Pascal DosDevIOCtl2(PVOID pData, USHORT cbData, PVOID pParm,
+    ;                             USHORT cbParm, USHORT usFun, USHORT usCategory,
+    ;                             HFILE hDev);
+    push    ss                                      ; pData
+    lea     dx, [abData]
+    push    dx
+    push    %2                                      ; cbData
+
+    push    ss                                      ; pParm
+    lea     dx, [abParm]
+    push    dx
+    push    %1                                      ; cbParm
+    push    OEMHLP_PCI                              ; usFun
+    push    IOCTL_OEMHLP                            ; usCategory
+
+    mov     ax, [hfOpen]                            ; hDev
+    push    ax
+    call far DOS16DEVIOCTL2
+
+    ; check for error.
+    test    ax, ax
+    jnz near .done_err_close
+    cmp     [abData + 0], byte 0
+    jne near .done_err_close
+%endmacro
+
+
+    ;
+    ; Open the OEMHLP$ driver.
+    ;
+
+    ; APIRET _Pascal DosOpen(PSZ pszFname, PHFILE phfOpen, PUSHORT pusAction,
+    ;                        ULONG ulFSize, USHORT usAttr, USHORT fsOpenFlags,
+    ;                        USHORT fsOpenMode, ULONG ulReserved);
+    mov     di, '0'
+    push    seg g_szOemHlpDevName                   ; pszFname
+    push    g_szOemHlpDevName
+    push    ss                                      ; phfOpen
+    lea     dx, [hfOpen]
+    push    dx
+    push    ss                                      ; pusAction
+    lea     dx, [usAction]
+    push    dx
+    push    dword 0                                 ; ulFSize
+    push    0                                       ; usAttr = FILE_NORMAL
+    push    1                                       ; fsOpenFlags = FILE_OPEN
+    push    00040h                                  ; fsOpenMode = OPEN_SHARE_DENYNONE | OPEN_ACCESS_READONLY
+    push    dword 0                                 ; ulReserved
+    call far DOS16OPEN
+    or      ax, ax
+    jnz near .done
+
+
+    ;
+    ; Send a PCI_FIND_DEVICE request.
+    ;
+
+    ; Initialize the parameter packet.
+    mov     [abParm + 0], byte PCI_FIND_DEVICE      ; 0 - db - SubFunction Number
+    mov     [abParm + 1], word VMMDEV_DEVICEID      ; 1 - dw - Device ID
+    mov     [abParm + 3], word VBOX_PCI_VENDORID    ; 3 - dw - Vendor ID
+    mov     [abParm + 5], byte 0                    ; 5 - db - (Device) Index
+
+    ; Zero padd the data packet.
+    mov     [abData + 0], dword 0
+
+    mov     di, '1'
+    CallIOCtl 6, 3
+
+    mov     al, [abData + 1]                        ; 1 - db - Bus Number.
+    mov     [NAME(g_bPciBusNo)], al
+    mov     al, [abData + 2]                        ; 2 - db - DevFunc Number.
+    mov     [NAME(g_bPciDevFunNo)], al
+
+    ;
+    ; Read the interrupt register (byte).
+    ;
+    mov     di, '2'
+    mov     ax, PCI_INTERRUPT_LINE | 0100h
+    call .NestedReadReg
+    mov     [NAME(g_bInterruptLine)], al
+
+    ;
+    ; Read the first base address (dword), this shall must be in I/O space.
+    ;
+    mov     di, '3'
+    mov     ax, PCI_BASE_ADDRESS_0 | 0400h
+    call .NestedReadReg
+    mov     di, '4'
+    test    al, 1h                                  ; Test that it's an I/O space address.
+    jz      .done_err_close
+    mov     di, '5'
+    test    eax, 0ffff0002h                         ; These shall all be 0 according to the specs.
+    jnz     .done_err_close
+    and     ax, 0fffeh
+    mov     [NAME(g_IOPortBase)], ax
+
+    ;
+    ; Read the second base address (dword), this shall be in memory space if present.
+    ;
+    mov     di, '6'
+    mov     ax, PCI_BASE_ADDRESS_1 | 0400h
+    call .NestedReadReg
+    mov     di, '7'
+    test    al, 1h                                  ; Test that it's a memory space address.
+    jnz     .done_err_close
+    and     eax, 0fffffff0h
+    mov     [NAME(g_PhysMMIOBase)], eax
+
+    ;or      eax, eax
+    ;jz      .done_success                             ; No memory region.
+    ;; @todo If there is a simple way of determining the size do that, if
+    ;        not we can easily handle it the code that does the actual mapping.
+
+
+    ;
+    ; Ok, we're good!
+    ;
+.done_success:
+    or      [NAME(g_fFoundAdapter)], byte 1
+    jmp     .done_close
+
+    ;
+    ; Close the OEMHLP$ driver.
+    ;
+.done_err_close:
+    or      ax, 80h
+.done_close:
+    ; APIRET  APIENTRY DosClose(HFILE hf);
+    push    ax                                      ; Save result
+    mov     cx, [hfOpen]
+    push    cx
+    call far DOS16CLOSE
+    or      ax, ax
+    jnz     .bitch                                  ; This can't happen (I hope).
+    pop     ax
+    or      ax, ax
+    jnz     .bitch
+
+    ;
+    ; Return to vgdrvOS2EP_Init.
+    ;
+.done:
+    mov     esp, ebp
+    pop     ebp
+    pop     edi
+    pop     esi
+    pop     edx
+    pop     ecx
+    pop     ebx
+    ret
+
+
+    ;
+    ; Puts the reason for failure in message buffer.
+    ; The caller will flush this.
+    ;
+.bitch:
+    push    es
+
+    mov     ax, ds
+    mov     es, ax
+    mov     ax, di                                  ; save the reason.
+    mov     di, NAME(g_szInitText)
+    add     di, [NAME(g_cchInitText)]
+
+    mov     si, g_achLoadFailureMsg1
+    mov     cx, g_cchLoadFailureMsg1
+    rep movsb
+
+    stosb
+
+    mov     si, g_achLoadFailureMsg2
+    mov     cx, g_cchLoadFailureMsg2
+    rep movsb
+
+    mov     [di], byte 0
+    sub     di, NAME(g_szInitText)
+    mov     [NAME(g_cchInitText)], di
+
+    pop     es
+    jmp     .done
+
+
+    ;
+    ; Nested function which reads a PCI config register.
+    ; (This operates on the vgdrvFindAdapter stack frame.)
+    ;
+    ; Input:
+    ;   al - register to read
+    ;   ah - register size.
+    ;
+    ; Output:
+    ;   eax - the value.
+    ;
+    ; Uses:
+    ;   dx
+    ;
+.NestedReadReg:
+    ; Fill in the request packet.
+    mov     [abParm + 0], byte PCI_READ_CONFIG      ; 0 - db - SubFunction Number
+    mov     dl, [NAME(g_bPciBusNo)]
+    mov     [abParm + 1], dl                        ; 1 - db - Bus Number
+    mov     dl, [NAME(g_bPciDevFunNo)]
+    mov     [abParm + 2], dl                        ; 2 - db - DevFunc Number
+    mov     [abParm + 3], al                        ; 3 - db - Configuration Register
+    mov     [abParm + 4], ah                        ; 4 - db - (Register) Size
+
+    ; Pad the data packet.
+    mov     [abData + 0], dword 0
+    mov     [abData + 4], dword 0
+
+    CallIOCtl 5, 5
+
+    mov     eax, [abData + 1]                       ; 1 - dd - Data
+
+    ret
+
+ENDPROC vgdrvFindAdapter
+
+
+
+;;
+; This must be present
+segment DATA32
+g_pfnDos16Write:
+    dd  DOS16WRITE  ; flat
+
diff --git a/src/VBox/Additions/common/VBoxGuest/VBoxGuestInternal.h b/src/VBox/Additions/common/VBoxGuest/VBoxGuestInternal.h
new file mode 100644
index 00000000..282c835f
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/VBoxGuestInternal.h
@@ -0,0 +1,415 @@
+/* $Id: VBoxGuestInternal.h $ */
+/** @file
+ * VBoxGuest - Guest Additions Driver, Internal Header.
+ */
+
+/*
+ * Copyright (C) 2010-2023 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 GA_INCLUDED_SRC_common_VBoxGuest_VBoxGuestInternal_h
+#define GA_INCLUDED_SRC_common_VBoxGuest_VBoxGuestInternal_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <iprt/types.h>
+#include <iprt/list.h>
+#include <iprt/semaphore.h>
+#include <iprt/spinlock.h>
+#include <iprt/timer.h>
+#include <VBox/VMMDev.h>
+#include <VBox/VBoxGuest.h>
+#include <VBox/VBoxGuestLib.h>
+
+/** @def VBOXGUEST_USE_DEFERRED_WAKE_UP
+ * Defer wake-up of waiting thread when defined. */
+#if defined(RT_OS_SOLARIS) || defined(RT_OS_WINDOWS) || defined(DOXYGEN_RUNNING)
+# define VBOXGUEST_USE_DEFERRED_WAKE_UP
+#endif
+
+/** @def VBOXGUEST_MOUSE_NOTIFY_CAN_PREEMPT
+ * The mouse notification callback can cause preemption and must not be invoked
+ * while holding a high-level spinlock.
+ */
+#if defined(RT_OS_SOLARIS) || defined(RT_OS_WINDOWS) || defined(DOXYGEN_RUNNING)
+# define VBOXGUEST_MOUSE_NOTIFY_CAN_PREEMPT
+#endif
+
+/** Pointer to the VBoxGuest per session data. */
+typedef struct VBOXGUESTSESSION *PVBOXGUESTSESSION;
+
+/** Pointer to a wait-for-event entry. */
+typedef struct VBOXGUESTWAIT *PVBOXGUESTWAIT;
+
+/**
+ * VBox guest wait for event entry.
+ *
+ * Each waiting thread allocates one of these items and adds
+ * it to the wait list before going to sleep on the event sem.
+ */
+typedef struct VBOXGUESTWAIT
+{
+    /** The list node. */
+    RTLISTNODE                  ListNode;
+    /** The events we are waiting on. */
+    uint32_t                    fReqEvents;
+    /** The events we received. */
+    uint32_t volatile           fResEvents;
+#ifdef VBOXGUEST_USE_DEFERRED_WAKE_UP
+    /** Set by VGDrvCommonWaitDoWakeUps before leaving the spinlock to call
+     *  RTSemEventMultiSignal. */
+    bool volatile               fPendingWakeUp;
+    /** Set by the requestor thread if it got the spinlock before the
+     * signaller.  Deals with the race in VGDrvCommonWaitDoWakeUps. */
+    bool volatile               fFreeMe;
+#endif
+    /** The event semaphore. */
+    RTSEMEVENTMULTI             Event;
+    /** The session that's waiting. */
+    PVBOXGUESTSESSION           pSession;
+#ifdef VBOX_WITH_HGCM
+    /** The HGCM request we're waiting for to complete. */
+    VMMDevHGCMRequestHeader volatile *pHGCMReq;
+#endif
+} VBOXGUESTWAIT;
+
+
+/**
+ * VBox guest memory balloon.
+ */
+typedef struct VBOXGUESTMEMBALLOON
+{
+    /** Mutex protecting the members below from concurrent access. */
+    RTSEMFASTMUTEX              hMtx;
+    /** The current number of chunks in the balloon. */
+    uint32_t                    cChunks;
+    /** The maximum number of chunks in the balloon (typically the amount of guest
+     * memory / chunksize). */
+    uint32_t                    cMaxChunks;
+    /** This is true if we are using RTR0MemObjAllocPhysNC() / RTR0MemObjGetPagePhysAddr()
+     * and false otherwise. */
+    bool                        fUseKernelAPI;
+    /** The current owner of the balloon.
+     * This is automatically assigned to the first session using the ballooning
+     * API and first released when the session closes. */
+    PVBOXGUESTSESSION           pOwner;
+    /** The pointer to the array of memory objects holding the chunks of the
+     *  balloon.  This array is cMaxChunks in size when present. */
+    PRTR0MEMOBJ                 paMemObj;
+} VBOXGUESTMEMBALLOON;
+/** Pointer to a memory balloon. */
+typedef VBOXGUESTMEMBALLOON *PVBOXGUESTMEMBALLOON;
+
+
+/**
+ * Per bit usage tracker for a uint32_t mask.
+ *
+ * Used for optimal handling of guest properties, mouse status and event filter.
+ */
+typedef struct VBOXGUESTBITUSAGETRACER
+{
+    /** Per bit usage counters. */
+    uint32_t        acPerBitUsage[32];
+    /** The current mask according to acPerBitUsage. */
+    uint32_t        fMask;
+} VBOXGUESTBITUSAGETRACER;
+/** Pointer to a per bit usage tracker.  */
+typedef VBOXGUESTBITUSAGETRACER *PVBOXGUESTBITUSAGETRACER;
+/** Pointer to a const per bit usage tracker.  */
+typedef VBOXGUESTBITUSAGETRACER const *PCVBOXGUESTBITUSAGETRACER;
+
+
+/**
+ * VBox guest device (data) extension.
+ */
+typedef struct VBOXGUESTDEVEXT
+{
+    /** VBOXGUESTDEVEXT_INIT_STATE_XXX.   */
+    uint32_t                    uInitState;
+    /** The base of the adapter I/O ports. */
+    RTIOPORT                    IOPortBase;
+    /** Pointer to the mapping of the VMMDev adapter memory. */
+    VMMDevMemory volatile      *pVMMDevMemory;
+    /** The memory object reserving space for the guest mappings. */
+    RTR0MEMOBJ                  hGuestMappings;
+    /** Spinlock protecting the signaling and resetting of the wait-for-event
+     * semaphores as well as the event acking in the ISR. */
+    RTSPINLOCK                  EventSpinlock;
+    /** Host feature flags (VMMDEV_HVF_XXX).   */
+    uint32_t                    fHostFeatures;
+    /** Preallocated VMMDevEvents for the IRQ handler. */
+    VMMDevEvents               *pIrqAckEvents;
+    /** The physical address of pIrqAckEvents. */
+    RTCCPHYS                    PhysIrqAckEvents;
+    /** Wait-for-event list for threads waiting for multiple events
+     * (VBOXGUESTWAIT). */
+    RTLISTANCHOR                WaitList;
+#ifdef VBOX_WITH_HGCM
+    /** Wait-for-event list for threads waiting on HGCM async completion
+     * (VBOXGUESTWAIT).
+     *
+     * The entire list is evaluated upon the arrival of an HGCM event, unlike
+     * the other lists which are only evaluated till the first thread has
+     * been woken up. */
+    RTLISTANCHOR                HGCMWaitList;
+#endif
+#ifdef VBOXGUEST_USE_DEFERRED_WAKE_UP
+    /** List of wait-for-event entries that needs waking up
+     * (VBOXGUESTWAIT). */
+    RTLISTANCHOR                WakeUpList;
+#endif
+    /** List of wait-for-event entries that has been woken up
+     * (VBOXGUESTWAIT). */
+    RTLISTANCHOR                WokenUpList;
+    /** List of free wait-for-event entries (VBOXGUESTWAIT). */
+    RTLISTANCHOR                FreeList;
+    /** Mask of pending events. */
+    uint32_t volatile           f32PendingEvents;
+    /** Current VMMDEV_EVENT_MOUSE_POSITION_CHANGED sequence number.
+     * Used to implement polling.  */
+    uint32_t volatile           u32MousePosChangedSeq;
+
+    /** Spinlock various items in the VBOXGUESTSESSION. */
+    RTSPINLOCK                  SessionSpinlock;
+    /** List of guest sessions (VBOXGUESTSESSION).  We currently traverse this
+     * but do not search it, so a list data type should be fine.  Use under the
+     * #SessionSpinlock lock. */
+    RTLISTANCHOR                SessionList;
+    /** Number of session. */
+    uint32_t                    cSessions;
+    /** Flag indicating whether logging to the release log
+     *  is enabled. */
+    bool                        fLoggingEnabled;
+    /** Memory balloon information for RTR0MemObjAllocPhysNC(). */
+    VBOXGUESTMEMBALLOON         MemBalloon;
+    /** Mouse notification callback function. */
+    PFNVBOXGUESTMOUSENOTIFY     pfnMouseNotifyCallback;
+    /** The callback argument for the mouse ntofication callback. */
+    void                       *pvMouseNotifyCallbackArg;
+
+    /** @name Host Event Filtering
+     * @{ */
+    /** Events we won't permit anyone to filter out. */
+    uint32_t                    fFixedEvents;
+    /** Usage counters for the host events. (Fixed events are not included.) */
+    VBOXGUESTBITUSAGETRACER     EventFilterTracker;
+    /** The event filter last reported to the host (UINT32_MAX on failure). */
+    uint32_t                    fEventFilterHost;
+    /** @} */
+
+    /** @name Mouse Status
+     * @{ */
+    /** Usage counters for the mouse statuses (VMMDEV_MOUSE_XXX). */
+    VBOXGUESTBITUSAGETRACER     MouseStatusTracker;
+    /** The mouse status last reported to the host (UINT32_MAX on failure). */
+    uint32_t                    fMouseStatusHost;
+    /** @} */
+
+    /** @name Guest Capabilities
+     * @{ */
+    /** Guest capabilities which have been set to "acquire" mode.  This means
+     * that only one session can use them at a time, and that they will be
+     * automatically cleaned up if that session exits without doing so.
+     *
+     * Protected by VBOXGUESTDEVEXT::SessionSpinlock, but is unfortunately read
+     * without holding the lock in a couple of places. */
+    uint32_t volatile           fAcquireModeGuestCaps;
+    /** Guest capabilities which have been set to "set" mode.  This just means
+     * that they have been blocked from ever being set to "acquire" mode. */
+    uint32_t                    fSetModeGuestCaps;
+    /** Mask of all capabilities which are currently acquired by some session
+     * and as such reported to the host. */
+    uint32_t                    fAcquiredGuestCaps;
+    /** Usage counters for guest capabilities in "set" mode. Indexed by
+     *  capability bit number, one count per session using a capability. */
+    VBOXGUESTBITUSAGETRACER     SetGuestCapsTracker;
+    /** The guest capabilities last reported to the host (UINT32_MAX on failure). */
+    uint32_t                    fGuestCapsHost;
+    /** @} */
+
+    /** Heartbeat timer which fires with interval
+      * cNsHearbeatInterval and its handler sends
+      * VMMDevReq_GuestHeartbeat to VMMDev. */
+    PRTTIMER                    pHeartbeatTimer;
+    /** Heartbeat timer interval in nanoseconds. */
+    uint64_t                    cNsHeartbeatInterval;
+    /** Preallocated VMMDevReq_GuestHeartbeat request. */
+    VMMDevRequestHeader         *pReqGuestHeartbeat;
+} VBOXGUESTDEVEXT;
+/** Pointer to the VBoxGuest driver data. */
+typedef VBOXGUESTDEVEXT *PVBOXGUESTDEVEXT;
+
+/** @name VBOXGUESTDEVEXT_INIT_STATE_XXX - magic values for validating init
+ *        state of the device extension structur.
+ * @{ */
+#define VBOXGUESTDEVEXT_INIT_STATE_FUNDAMENT        UINT32_C(0x0badcafe)
+#define VBOXGUESTDEVEXT_INIT_STATE_RESOURCES        UINT32_C(0xcafebabe)
+#define VBOXGUESTDEVEXT_INIT_STATE_DELETED          UINT32_C(0xdeadd0d0)
+/** @} */
+
+/**
+ * The VBoxGuest per session data.
+ */
+typedef struct VBOXGUESTSESSION
+{
+    /** The list node. */
+    RTLISTNODE                  ListNode;
+#if defined(RT_OS_DARWIN) || defined(RT_OS_FREEBSD) || defined(RT_OS_OS2) || defined(RT_OS_SOLARIS)
+    /** Pointer to the next session with the same hash. */
+    PVBOXGUESTSESSION           pNextHash;
+#endif
+#if defined(RT_OS_OS2)
+    /** The system file number of this session. */
+    uint16_t                    sfn;
+    uint16_t                    Alignment; /**< Alignment */
+#endif
+    /** The requestor information to pass to the host for this session.
+     * @sa VMMDevRequestHeader::fRequestor */
+    uint32_t                    fRequestor;
+    /** The process (id) of the session.
+     * This is NIL if it's a kernel session. */
+    RTPROCESS                   Process;
+    /** Which process this session is associated with.
+     * This is NIL if it's a kernel session. */
+    RTR0PROCESS                 R0Process;
+    /** Pointer to the device extension. */
+    PVBOXGUESTDEVEXT            pDevExt;
+
+#ifdef VBOX_WITH_HGCM
+    /** Array containing HGCM client IDs associated with this session.
+     * This will be automatically disconnected when the session is closed. */
+    uint32_t volatile           aHGCMClientIds[64];
+#endif
+    /** The last consumed VMMDEV_EVENT_MOUSE_POSITION_CHANGED sequence number.
+     * Used to implement polling.  */
+    uint32_t volatile           u32MousePosChangedSeq;
+    /** Host events requested by the session.
+     * An event type requested in any guest session will be added to the host
+     * filter.  Protected by VBOXGUESTDEVEXT::SessionSpinlock. */
+    uint32_t                    fEventFilter;
+    /** Guest capabilities held in "acquired" by this session.
+     * Protected by VBOXGUESTDEVEXT::SessionSpinlock, but is unfortunately read
+     * without holding the lock in a couple of places. */
+    uint32_t volatile           fAcquiredGuestCaps;
+    /** Guest capabilities in "set" mode for this session.
+     * These accumulated for sessions via VBOXGUESTDEVEXT::acGuestCapsSet and
+     * reported to the host.  Protected by VBOXGUESTDEVEXT::SessionSpinlock.  */
+    uint32_t                    fCapabilities;
+    /** Mouse features supported.  A feature enabled in any guest session will
+     * be enabled for the host.
+     * @note We invert the VMMDEV_MOUSE_GUEST_NEEDS_HOST_CURSOR feature in this
+     * bitmap.  The logic of this is that the real feature is when the host
+     * cursor is not needed, and we tell the host it is not needed if any
+     * session explicitly fails to assert it.  Storing it inverted simplifies
+     * the checks.
+     * Use under the VBOXGUESTDEVEXT#SessionSpinlock lock. */
+    uint32_t                    fMouseStatus;
+#ifdef RT_OS_DARWIN
+    /** Pointer to the associated org_virtualbox_VBoxGuestClient object. */
+    void                       *pvVBoxGuestClient;
+    /** Whether this session has been opened or not. */
+    bool                        fOpened;
+#endif
+    /** Whether a CANCEL_ALL_WAITEVENTS is pending.  This happens when
+     * CANCEL_ALL_WAITEVENTS is called, but no call to WAITEVENT is in process
+     * in the current session.  In that case the next call will be interrupted
+     * at once. */
+    bool volatile               fPendingCancelWaitEvents;
+    /** Does this session belong to a root process or a user one? */
+    bool                        fUserSession;
+} VBOXGUESTSESSION;
+
+RT_C_DECLS_BEGIN
+
+int  VGDrvCommonInitDevExt(PVBOXGUESTDEVEXT pDevExt, uint16_t IOPortBase, void *pvMMIOBase, uint32_t cbMMIO,
+                           VBOXOSTYPE enmOSType, uint32_t fEvents);
+void VGDrvCommonDeleteDevExt(PVBOXGUESTDEVEXT pDevExt);
+
+int  VGDrvCommonInitLoggers(void);
+void VGDrvCommonDestroyLoggers(void);
+int  VGDrvCommonInitDevExtFundament(PVBOXGUESTDEVEXT pDevExt);
+void VGDrvCommonDeleteDevExtFundament(PVBOXGUESTDEVEXT pDevExt);
+int  VGDrvCommonInitDevExtResources(PVBOXGUESTDEVEXT pDevExt, uint16_t IOPortBase,
+                                    void *pvMMIOBase, uint32_t cbMMIO, VBOXOSTYPE enmOSType, uint32_t fFixedEvents);
+void VGDrvCommonDeleteDevExtResources(PVBOXGUESTDEVEXT pDevExt);
+int  VGDrvCommonReinitDevExtAfterHibernation(PVBOXGUESTDEVEXT pDevExt, VBOXOSTYPE enmOSType);
+
+bool VBDrvCommonIsOptionValueTrue(const char *pszValue);
+void VGDrvCommonProcessOption(PVBOXGUESTDEVEXT pDevExt, const char *pszName, const char *pszValue);
+void VGDrvCommonProcessOptionsFromHost(PVBOXGUESTDEVEXT pDevExt);
+bool VGDrvCommonIsOurIRQ(PVBOXGUESTDEVEXT pDevExt);
+bool VGDrvCommonISR(PVBOXGUESTDEVEXT pDevExt);
+
+#ifdef VBOXGUEST_USE_DEFERRED_WAKE_UP
+void VGDrvCommonWaitDoWakeUps(PVBOXGUESTDEVEXT pDevExt);
+#endif
+
+int  VGDrvCommonCreateUserSession(PVBOXGUESTDEVEXT pDevExt, uint32_t fRequestor, PVBOXGUESTSESSION *ppSession);
+int  VGDrvCommonCreateKernelSession(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION *ppSession);
+void VGDrvCommonCloseSession(PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession);
+
+int  VGDrvCommonIoCtlFast(uintptr_t iFunction, PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession);
+int  VGDrvCommonIoCtl(uintptr_t iFunction, PVBOXGUESTDEVEXT pDevExt, PVBOXGUESTSESSION pSession,
+                      PVBGLREQHDR pReqHdr, size_t cbReq);
+
+/**
+ * ISR callback for notifying threads polling for mouse events.
+ *
+ * This is called at the end of the ISR, after leaving the event spinlock, if
+ * VMMDEV_EVENT_MOUSE_POSITION_CHANGED was raised by the host.
+ *
+ * @param   pDevExt     The device extension.
+ */
+void VGDrvNativeISRMousePollEvent(PVBOXGUESTDEVEXT pDevExt);
+
+/**
+ * Hook for handling OS specfic options from the host.
+ *
+ * @returns true if handled, false if not.
+ * @param   pDevExt         The device extension.
+ * @param   pszName         The option name.
+ * @param   pszValue        The option value.
+ */
+bool VGDrvNativeProcessOption(PVBOXGUESTDEVEXT pDevExt, const char *pszName, const char *pszValue);
+
+
+#ifdef VBOX_WITH_DPC_LATENCY_CHECKER
+int VGDrvNtIOCtl_DpcLatencyChecker(void);
+#endif
+
+#ifdef VBOXGUEST_MOUSE_NOTIFY_CAN_PREEMPT
+int VGDrvNativeSetMouseNotifyCallback(PVBOXGUESTDEVEXT pDevExt, PVBGLIOCSETMOUSENOTIFYCALLBACK pNotify);
+#endif
+
+RT_C_DECLS_END
+
+#endif /* !GA_INCLUDED_SRC_common_VBoxGuest_VBoxGuestInternal_h */
+
diff --git a/src/VBox/Additions/common/VBoxGuest/darwin/Info.plist b/src/VBox/Additions/common/VBoxGuest/darwin/Info.plist
new file mode 100644
index 00000000..f4384535
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/darwin/Info.plist
@@ -0,0 +1,51 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+    <key>CFBundleDevelopmentRegion</key>        <string>English</string>
+    <key>CFBundleExecutable</key>               <string>VBoxGuest</string>
+    <key>CFBundleIdentifier</key>               <string>org.virtualbox.kext.VBoxGuest</string>
+    <key>CFBundleInfoDictionaryVersion</key>    <string>6.0</string>
+    <key>CFBundleName</key>                     <string>VBoxGuest</string>
+    <key>CFBundlePackageType</key>              <string>KEXT</string>
+    <key>CFBundleSignature</key>                <string>????</string>
+    <key>NSHumanReadableCopyright</key>         <string>Copyright © 2007-@VBOX_C_YEAR@ @VBOX_VENDOR@</string>
+    <key>CFBundleGetInfoString</key>            <string>@VBOX_PRODUCT@ @VBOX_VERSION_STRING@, © 2007-@VBOX_C_YEAR@ @VBOX_VENDOR@</string>
+    <key>CFBundleVersion</key>                  <string>@VBOX_VERSION_MAJOR@.@VBOX_VERSION_MINOR@.@VBOX_VERSION_BUILD@</string>
+    <key>CFBundleShortVersionString</key>       <string>@VBOX_VERSION_MAJOR@.@VBOX_VERSION_MINOR@.@VBOX_VERSION_BUILD@</string>
+    <key>OSBundleCompatibleVersion</key>        <string>@VBOX_VERSION_MAJOR@.@VBOX_VERSION_MINOR@.@VBOX_VERSION_BUILD@</string>
+    <key>IOKitPersonalities</key>
+    <dict>
+        <key>VBoxGuest</key>
+        <dict>
+            <key>CFBundleIdentifier</key>       <string>org.virtualbox.kext.VBoxGuest</string>
+            <key>IOClass</key>                  <string>org_virtualbox_VBoxGuest</string>
+            <key>IOMatchCategory</key>          <string>org_virtualbox_VBoxGuest</string>
+            <key>IOUserClientClass</key>        <string>org_virtualbox_VBoxGuestClient</string>
+            <key>IOKitDebug</key>               <integer>65535</integer>
+            <key>IOProviderClass</key>          <string>IOPCIDevice</string>
+            <key>IOPCIPrimaryMatch</key>        <string>0xcafe80ee</string>
+            <!-- <key>IONameMatch</key>              <string>pci80ee,cafe</string> -->
+        </dict>
+    </dict>
+    <key>OSBundleLibraries</key>
+    <dict>
+        <key>com.apple.iokit.IOPCIFamily</key>  <string>2.5</string> <!-- TODO: Figure the version in mac os x 10.4. -->
+        <key>com.apple.kpi.bsd</key>            <string>8.0.0</string>
+        <key>com.apple.kpi.mach</key>           <string>8.0.0</string>
+        <key>com.apple.kpi.libkern</key>        <string>8.0.0</string>
+        <key>com.apple.kpi.unsupported</key>    <string>8.0.0</string>
+        <key>com.apple.kpi.iokit</key>          <string>8.0.0</string>
+    </dict>
+    <key>OSBundleLibraries_x86_64</key>
+    <dict>
+        <key>com.apple.iokit.IOPCIFamily</key>  <string>2.6</string>
+        <key>com.apple.kpi.bsd</key>            <string>10.0.0d4</string>
+        <key>com.apple.kpi.mach</key>           <string>10.0.0d3</string>
+        <key>com.apple.kpi.libkern</key>        <string>10.0.0d3</string>
+        <key>com.apple.kpi.iokit</key>          <string>10.0.0d3</string>
+        <key>com.apple.kpi.unsupported</key>    <string>10.0.0d3</string>
+    </dict>
+</dict>
+</plist>
+
diff --git a/src/VBox/Additions/common/VBoxGuest/freebsd/Makefile b/src/VBox/Additions/common/VBoxGuest/freebsd/Makefile
new file mode 100644
index 00000000..5344dbc0
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/freebsd/Makefile
@@ -0,0 +1,202 @@
+# $Id: Makefile $
+## @file
+# VirtualBox Guest Additions Module Makefile.
+#
+
+#
+# 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
+#
+KMOD = vboxguest
+
+CFLAGS += -DRT_OS_FREEBSD -DIN_RING0 -DIN_RT_R0 -DIN_SUP_R0 -DVBOX -DRT_WITH_VBOX -Iinclude -I. -Ir0drv -w -DVBGL_VBOXGUEST -DVBOX_WITH_HGCM -DVBOX_WITH_64_BITS_GUESTS
+
+.if (${MACHINE_ARCH} == "i386")
+ CFLAGS += -DRT_ARCH_X86
+.elif (${MACHINE_ARCH} == "amd64")
+ CFLAGS += -DRT_ARCH_AMD64
+.endif
+
+SRCS = \
+	VBoxGuest.c \
+	VBoxGuest-freebsd.c \
+	VBoxGuestR0LibGenericRequest.c \
+	VBoxGuestR0LibHGCMInternal.c \
+	VBoxGuestR0LibInit.c \
+	VBoxGuestR0LibPhysHeap.c \
+	VBoxGuestR0LibVMMDev.c
+
+# Include needed interface headers so they are created during build
+SRCS += \
+	device_if.h \
+	bus_if.h \
+	pci_if.h \
+
+.PATH:	${.CURDIR}/alloc
+SRCS += \
+	heapsimple.c
+
+.PATH:	${.CURDIR}/common/err
+SRCS += \
+	RTErrConvertFromErrno.c \
+	RTErrConvertToErrno.c \
+	errinfo.c
+
+.PATH:	${.CURDIR}/common/log
+SRCS += \
+	log.c \
+	logellipsis.c \
+	logrel.c \
+	logrelellipsis.c \
+	logcom.c \
+	logformat.c \
+	RTLogCreateEx.c
+
+.PATH:	${.CURDIR}/common/misc
+SRCS += \
+	RTAssertMsg1Weak.c \
+	RTAssertMsg2.c \
+	RTAssertMsg2Add.c \
+	RTAssertMsg2AddWeak.c \
+	RTAssertMsg2AddWeakV.c \
+	RTAssertMsg2Weak.c \
+	RTAssertMsg2WeakV.c \
+	assert.c \
+	handletable.c \
+	handletablectx.c \
+	once.c \
+	thread.c
+
+.PATH:	${.CURDIR}/common/string
+SRCS += \
+	RTStrCat.c \
+	RTStrCmp.c \
+	RTStrCopy.c \
+	RTStrCopyEx.c \
+	RTStrCopyP.c \
+	RTStrEnd.c \
+	RTStrICmpAscii.c \
+	RTStrNICmpAscii.c \
+	RTStrNCmp.c \
+	RTStrNLen.c \
+	stringalloc.c \
+	strformat.c \
+	RTStrFormat.c \
+	strformatnum.c \
+	strformatrt.c \
+	strformattype.c \
+	strprintf.c \
+	strprintf-ellipsis.c \
+	strprintf2.c \
+	strprintf2-ellipsis.c \
+	strtonum.c \
+	memchr.c \
+	utf-8.c
+
+.PATH:	${.CURDIR}/common/rand
+SRCS += \
+	rand.c \
+	randadv.c \
+	randparkmiller.c
+
+.PATH:	${.CURDIR}/common/path
+SRCS += \
+	RTPathStripFilename.c
+
+.PATH:	${.CURDIR}/common/checksum
+SRCS += \
+	crc32.c \
+	ipv4.c
+
+.PATH:	${.CURDIR}/common/table
+SRCS += \
+	avlpv.c
+
+.PATH:	${.CURDIR}/common/time
+SRCS += \
+	time.c
+
+.PATH:	${.CURDIR}/generic
+SRCS += \
+	uuid-generic.c \
+	RTAssertShouldPanic-generic.c \
+	RTLogWriteDebugger-generic.c \
+	RTLogWriteStdOut-stub-generic.c \
+	RTLogWriteStdErr-stub-generic.c \
+	RTRandAdvCreateSystemFaster-generic.c \
+	RTRandAdvCreateSystemTruer-generic.c \
+	RTSemEventWait-2-ex-generic.c \
+	RTSemEventWaitNoResume-2-ex-generic.c \
+	RTSemEventMultiWait-2-ex-generic.c \
+	RTSemEventMultiWaitNoResume-2-ex-generic.c \
+	RTTimerCreate-generic.c \
+	rtStrFormatKernelAddress-generic.c \
+	timer-generic.c \
+	errvars-generic.c \
+	mppresent-generic.c
+
+.PATH:	${.CURDIR}/r0drv
+SRCS += \
+	alloc-r0drv.c \
+	initterm-r0drv.c \
+	memobj-r0drv.c \
+	powernotification-r0drv.c
+
+.PATH:	${.CURDIR}/r0drv/freebsd
+SRCS += \
+	assert-r0drv-freebsd.c \
+	alloc-r0drv-freebsd.c \
+	initterm-r0drv-freebsd.c \
+	memobj-r0drv-freebsd.c \
+	memuserkernel-r0drv-freebsd.c \
+	mp-r0drv-freebsd.c \
+	process-r0drv-freebsd.c \
+	semevent-r0drv-freebsd.c \
+	semeventmulti-r0drv-freebsd.c \
+	semfastmutex-r0drv-freebsd.c \
+	semmutex-r0drv-freebsd.c \
+	spinlock-r0drv-freebsd.c \
+	thread-r0drv-freebsd.c \
+	thread2-r0drv-freebsd.c \
+	time-r0drv-freebsd.c
+
+.PATH:	${.CURDIR}/r0drv/generic
+SRCS += \
+	semspinmutex-r0drv-generic.c \
+	mpnotification-r0drv-generic.c \
+	RTMpIsCpuWorkPending-r0drv-generic.c
+
+.PATH:	${.CURDIR}/VBox
+SRCS += \
+	log-vbox.c \
+	logbackdoor.c \
+	RTLogWriteVmm-amd64-x86.
+
+.include <bsd.kmod.mk>
+
diff --git a/src/VBox/Additions/common/VBoxGuest/freebsd/Makefile.kup b/src/VBox/Additions/common/VBoxGuest/freebsd/Makefile.kup
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/freebsd/Makefile.kup
diff --git a/src/VBox/Additions/common/VBoxGuest/freebsd/files_vboxguest b/src/VBox/Additions/common/VBoxGuest/freebsd/files_vboxguest
new file mode 100755
index 00000000..3f8e8f94
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/freebsd/files_vboxguest
@@ -0,0 +1,240 @@
+#!/bin/sh
+# $Id: files_vboxguest $
+## @file
+# Shared file between Makefile.kmk and export_modules.sh.
+#
+
+#
+# Copyright (C) 2007-2023 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
+#
+
+FILES_VBOXGUEST_NOBIN=" \
+    ${PATH_ROOT}/include/iprt/alloca.h=>include/iprt/alloca.h \
+    ${PATH_ROOT}/include/iprt/alloc.h=>include/iprt/alloc.h \
+    ${PATH_ROOT}/include/iprt/asm.h=>include/iprt/asm.h \
+    ${PATH_ROOT}/include/iprt/asm-amd64-x86.h=>include/iprt/asm-amd64-x86.h \
+    ${PATH_ROOT}/include/iprt/asm-math.h=>include/iprt/asm-math.h \
+    ${PATH_ROOT}/include/iprt/assert.h=>include/iprt/assert.h \
+    ${PATH_ROOT}/include/iprt/assertcompile.h=>include/iprt/assertcompile.h \
+    ${PATH_ROOT}/include/iprt/avl.h=>include/iprt/avl.h \
+    ${PATH_ROOT}/include/iprt/cdefs.h=>include/iprt/cdefs.h \
+    ${PATH_ROOT}/include/iprt/cpuset.h=>include/iprt/cpuset.h \
+    ${PATH_ROOT}/include/iprt/ctype.h=>include/iprt/ctype.h \
+    ${PATH_ROOT}/include/iprt/err.h=>include/iprt/err.h \
+    ${PATH_ROOT}/include/iprt/errcore.h=>include/iprt/errcore.h \
+    ${PATH_ROOT}/include/iprt/errno.h=>include/iprt/errno.h \
+    ${PATH_ROOT}/include/iprt/heap.h=>include/iprt/heap.h \
+    ${PATH_ROOT}/include/iprt/handletable.h=>include/iprt/handletable.h \
+    ${PATH_ROOT}/include/iprt/initterm.h=>include/iprt/initterm.h \
+    ${PATH_ROOT}/include/iprt/latin1.h=>include/iprt/latin1.h \
+    ${PATH_ROOT}/include/iprt/list.h=>include/iprt/list.h \
+    ${PATH_ROOT}/include/iprt/lockvalidator.h=>include/iprt/lockvalidator.h \
+    ${PATH_ROOT}/include/iprt/log.h=>include/iprt/log.h \
+    ${PATH_ROOT}/include/iprt/mangling.h=>include/iprt/mangling.h \
+    ${PATH_ROOT}/include/iprt/mem.h=>include/iprt/mem.h \
+    ${PATH_ROOT}/include/iprt/memobj.h=>include/iprt/memobj.h \
+    ${PATH_ROOT}/include/iprt/mp.h=>include/iprt/mp.h \
+    ${PATH_ROOT}/include/iprt/param.h=>include/iprt/param.h \
+    ${PATH_ROOT}/include/iprt/power.h=>include/iprt/power.h \
+    ${PATH_ROOT}/include/iprt/process.h=>include/iprt/process.h \
+    ${PATH_ROOT}/include/iprt/semaphore.h=>include/iprt/semaphore.h \
+    ${PATH_ROOT}/include/iprt/spinlock.h=>include/iprt/spinlock.h \
+    ${PATH_ROOT}/include/iprt/stdarg.h=>include/iprt/stdarg.h \
+    ${PATH_ROOT}/include/iprt/stdint.h=>include/iprt/stdint.h \
+    ${PATH_ROOT}/include/iprt/string.h=>include/iprt/string.h \
+    ${PATH_ROOT}/include/iprt/thread.h=>include/iprt/thread.h \
+    ${PATH_ROOT}/include/iprt/time.h=>include/iprt/time.h \
+    ${PATH_ROOT}/include/iprt/timer.h=>include/iprt/timer.h \
+    ${PATH_ROOT}/include/iprt/types.h=>include/iprt/types.h \
+    ${PATH_ROOT}/include/iprt/utf16.h=>include/iprt/utf16.h \
+    ${PATH_ROOT}/include/iprt/uuid.h=>include/iprt/uuid.h \
+    ${PATH_ROOT}/include/iprt/crc.h=>include/iprt/crc.h \
+    ${PATH_ROOT}/include/iprt/net.h=>include/iprt/net.h \
+    ${PATH_ROOT}/include/iprt/rand.h=>include/iprt/rand.h \
+    ${PATH_ROOT}/include/iprt/path.h=>include/iprt/path.h \
+    ${PATH_ROOT}/include/iprt/once.h=>include/iprt/once.h \
+    ${PATH_ROOT}/include/iprt/critsect.h=>include/iprt/critsect.h \
+    ${PATH_ROOT}/include/iprt/x86.h=>include/iprt/x86.h \
+    ${PATH_ROOT}/include/iprt/x86-helpers.h=>include/iprt/x86-helpers.h \
+    ${PATH_ROOT}/include/iprt/nocrt/limits.h=>include/iprt/nocrt/limits.h \
+    ${PATH_ROOT}/include/VBox/cdefs.h=>include/VBox/cdefs.h \
+    ${PATH_ROOT}/include/VBox/err.h=>include/VBox/err.h \
+    ${PATH_ROOT}/include/VBox/log.h=>include/VBox/log.h \
+    ${PATH_ROOT}/include/VBox/param.h=>include/VBox/param.h \
+    ${PATH_ROOT}/include/VBox/types.h=>include/VBox/types.h \
+    ${PATH_ROOT}/include/VBox/ostypes.h=>include/VBox/ostypes.h \
+    ${PATH_ROOT}/include/VBox/VMMDev.h=>include/VBox/VMMDev.h \
+    ${PATH_ROOT}/include/VBox/VMMDevCoreTypes.h=>include/VBox/VMMDevCoreTypes.h \
+    ${PATH_ROOT}/include/VBox/VBoxGuest.h=>include/VBox/VBoxGuest.h \
+    ${PATH_ROOT}/include/VBox/VBoxGuestCoreTypes.h=>include/VBox/VBoxGuestCoreTypes.h \
+    ${PATH_ROOT}/include/VBox/VBoxGuestLib.h=>include/VBox/VBoxGuestLib.h \
+    ${PATH_ROOT}/include/VBox/VBoxGuestMangling.h=>include/VBox/VBoxGuestMangling.h \
+    ${PATH_ROOT}/include/VBox/version.h=>include/VBox/version.h \
+    ${PATH_ROOT}/include/VBox/HostServices/GuestPropertySvc.h=>include/VBox/HostServices/GuestPropertySvc.h \
+    ${PATH_ROOT}/include/VBox/vmm/cpuidcall.h=>include/VBox/vmm/cpuidcall.h \
+    ${PATH_ROOT}/src/VBox/Additions/common/VBoxGuest/VBoxGuest.cpp=>VBoxGuest.c \
+    ${PATH_ROOT}/src/VBox/Additions/common/VBoxGuest/VBoxGuest-freebsd.c=>VBoxGuest-freebsd.c \
+    ${PATH_ROOT}/src/VBox/Additions/common/VBoxGuest/VBoxGuestInternal.h=>VBoxGuestInternal.h \
+    ${PATH_ROOT}/src/VBox/Additions/common/VBoxGuest/freebsd/Makefile=>Makefile \
+    ${PATH_ROOT}/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibInternal.h=>VBoxGuestR0LibInternal.h \
+    ${PATH_ROOT}/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibGenericRequest.cpp=>VBoxGuestR0LibGenericRequest.c \
+    ${PATH_ROOT}/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibHGCMInternal.cpp=>VBoxGuestR0LibHGCMInternal.c \
+    ${PATH_ROOT}/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibInit.cpp=>VBoxGuestR0LibInit.c \
+    ${PATH_ROOT}/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibPhysHeap.cpp=>VBoxGuestR0LibPhysHeap.c \
+    ${PATH_ROOT}/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibVMMDev.cpp=>VBoxGuestR0LibVMMDev.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/alloc/heapsimple.cpp=>alloc/heapsimple.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/err/RTErrConvertFromErrno.cpp=>common/err/RTErrConvertFromErrno.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/err/RTErrConvertToErrno.cpp=>common/err/RTErrConvertToErrno.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/err/errinfo.cpp=>common/err/errinfo.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/log/log.cpp=>common/log/log.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/log/logellipsis.cpp=>common/log/logellipsis.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/log/logrel.cpp=>common/log/logrel.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/log/logrelellipsis.cpp=>common/log/logrelellipsis.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/log/logcom.cpp=>common/log/logcom.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/log/logformat.cpp=>common/log/logformat.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/log/RTLogCreateEx.cpp=>common/log/RTLogCreateEx.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/misc/handletable.cpp=>common/misc/handletable.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/misc/handletable.h=>common/misc/handletable.h \
+    ${PATH_ROOT}/src/VBox/Runtime/common/misc/handletablectx.cpp=>common/misc/handletablectx.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/misc/once.cpp=>common/misc/once.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/misc/thread.cpp=>common/misc/thread.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/misc/RTAssertMsg1Weak.cpp=>common/misc/RTAssertMsg1Weak.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/misc/RTAssertMsg2.cpp=>common/misc/RTAssertMsg2.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/misc/RTAssertMsg2Add.cpp=>common/misc/RTAssertMsg2Add.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/misc/RTAssertMsg2AddWeak.cpp=>common/misc/RTAssertMsg2AddWeak.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/misc/RTAssertMsg2AddWeakV.cpp=>common/misc/RTAssertMsg2AddWeakV.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/misc/RTAssertMsg2Weak.cpp=>common/misc/RTAssertMsg2Weak.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/misc/RTAssertMsg2WeakV.cpp=>common/misc/RTAssertMsg2WeakV.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/misc/assert.cpp=>common/misc/assert.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/RTStrCat.cpp=>common/string/RTStrCat.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/RTStrCmp.cpp=>common/string/RTStrCmp.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/RTStrCopy.cpp=>common/string/RTStrCopy.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/RTStrCopyEx.cpp=>common/string/RTStrCopyEx.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/RTStrCopyP.cpp=>common/string/RTStrCopyP.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/RTStrEnd.cpp=>common/string/RTStrEnd.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/RTStrICmpAscii.cpp=>common/string/RTStrICmpAscii.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/RTStrNICmpAscii.cpp=>common/string/RTStrNICmpAscii.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/RTStrNCmp.cpp=>common/string/RTStrNCmp.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/RTStrNLen.cpp=>common/string/RTStrNLen.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/stringalloc.cpp=>common/string/stringalloc.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/strformat.cpp=>common/string/strformat.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/RTStrFormat.cpp=>common/string/RTStrFormat.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/strformatnum.cpp=>common/string/strformatnum.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/strformatrt.cpp=>common/string/strformatrt.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/strformattype.cpp=>common/string/strformattype.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/strprintf.cpp=>common/string/strprintf.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/strprintf-ellipsis.cpp=>common/string/strprintf-ellipsis.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/strprintf2.cpp=>common/string/strprintf2.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/strprintf2-ellipsis.cpp=>common/string/strprintf2-ellipsis.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/strtonum.cpp=>common/string/strtonum.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/memchr.cpp=>common/string/memchr.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/utf-8.cpp=>common/string/utf-8.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/rand/rand.cpp=>common/rand/rand.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/rand/randadv.cpp=>common/rand/randadv.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/rand/randparkmiller.cpp=>common/rand/randparkmiller.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/path/RTPathStripFilename.cpp=>common/path/RTPathStripFilename.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/checksum/crc32.cpp=>common/checksum/crc32.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/checksum/ipv4.cpp=>common/checksum/ipv4.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/table/avlpv.cpp=>common/table/avlpv.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/table/avl_Base.cpp.h=>common/table/avl_Base.cpp.h \
+    ${PATH_ROOT}/src/VBox/Runtime/common/table/avl_Get.cpp.h=>common/table/avl_Get.cpp.h \
+    ${PATH_ROOT}/src/VBox/Runtime/common/table/avl_GetBestFit.cpp.h=>common/table/avl_GetBestFit.cpp.h \
+    ${PATH_ROOT}/src/VBox/Runtime/common/table/avl_RemoveBestFit.cpp.h=>common/table/avl_RemoveBestFit.cpp.h \
+    ${PATH_ROOT}/src/VBox/Runtime/common/table/avl_DoWithAll.cpp.h=>common/table/avl_DoWithAll.cpp.h \
+    ${PATH_ROOT}/src/VBox/Runtime/common/table/avl_Destroy.cpp.h=>common/table/avl_Destroy.cpp.h \
+    ${PATH_ROOT}/src/VBox/Runtime/common/time/time.cpp=>common/time/time.c \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/assert.h=>include/internal/assert.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/initterm.h=>include/internal/initterm.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/iprt.h=>include/internal/iprt.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/lockvalidator.h=>include/internal/lockvalidator.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/magics.h=>include/internal/magics.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/mem.h=>include/internal/mem.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/memobj.h=>include/internal/memobj.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/string.h=>include/internal/string.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/thread.h=>include/internal/thread.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/time.h=>include/internal/time.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/rand.h=>include/internal/rand.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/sched.h=>include/internal/sched.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/process.h=>include/internal/process.h \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/RTAssertShouldPanic-generic.cpp=>generic/RTAssertShouldPanic-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/RTLogWriteStdErr-stub-generic.cpp=>generic/RTLogWriteStdErr-stub-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/RTLogWriteStdOut-stub-generic.cpp=>generic/RTLogWriteStdOut-stub-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/RTLogWriteDebugger-generic.cpp=>generic/RTLogWriteDebugger-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/RTRandAdvCreateSystemFaster-generic.cpp=>generic/RTRandAdvCreateSystemFaster-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/RTRandAdvCreateSystemTruer-generic.cpp=>generic/RTRandAdvCreateSystemTruer-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/uuid-generic.cpp=>generic/uuid-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/RTSemEventWait-2-ex-generic.cpp=>generic/RTSemEventWait-2-ex-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/RTSemEventWaitNoResume-2-ex-generic.cpp=>generic/RTSemEventWaitNoResume-2-ex-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/RTSemEventMultiWait-2-ex-generic.cpp=>generic/RTSemEventMultiWait-2-ex-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/RTSemEventMultiWaitNoResume-2-ex-generic.cpp=>generic/RTSemEventMultiWaitNoResume-2-ex-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/RTTimerCreate-generic.cpp=>generic/RTTimerCreate-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/rtStrFormatKernelAddress-generic.cpp=>generic/rtStrFormatKernelAddress-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/errvars-generic.cpp=>generic/errvars-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/timer-generic.cpp=>generic/timer-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/mppresent-generic.cpp=>generic/mppresent-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/alloc-r0drv.cpp=>r0drv/alloc-r0drv.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/alloc-r0drv.h=>r0drv/alloc-r0drv.h \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/initterm-r0drv.cpp=>r0drv/initterm-r0drv.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/mp-r0drv.h=>r0drv/mp-r0drv.h \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/power-r0drv.h=>r0drv/power-r0drv.h \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/powernotification-r0drv.c=>r0drv/powernotification-r0drv.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/freebsd/assert-r0drv-freebsd.c=>r0drv/freebsd/assert-r0drv-freebsd.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/freebsd/alloc-r0drv-freebsd.c=>r0drv/freebsd/alloc-r0drv-freebsd.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/freebsd/initterm-r0drv-freebsd.c=>r0drv/freebsd/initterm-r0drv-freebsd.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/freebsd/memobj-r0drv-freebsd.c=>r0drv/freebsd/memobj-r0drv-freebsd.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/freebsd/memuserkernel-r0drv-freebsd.c=>r0drv/freebsd/memuserkernel-r0drv-freebsd.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/freebsd/mp-r0drv-freebsd.c=>r0drv/freebsd/mp-r0drv-freebsd.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/freebsd/process-r0drv-freebsd.c=>r0drv/freebsd/process-r0drv-freebsd.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/freebsd/semevent-r0drv-freebsd.c=>r0drv/freebsd/semevent-r0drv-freebsd.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/freebsd/semeventmulti-r0drv-freebsd.c=>r0drv/freebsd/semeventmulti-r0drv-freebsd.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/freebsd/semfastmutex-r0drv-freebsd.c=>r0drv/freebsd/semfastmutex-r0drv-freebsd.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/freebsd/semmutex-r0drv-freebsd.c=>r0drv/freebsd/semmutex-r0drv-freebsd.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/freebsd/spinlock-r0drv-freebsd.c=>r0drv/freebsd/spinlock-r0drv-freebsd.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/freebsd/the-freebsd-kernel.h=>r0drv/freebsd/the-freebsd-kernel.h \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/freebsd/thread-r0drv-freebsd.c=>r0drv/freebsd/thread-r0drv-freebsd.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/freebsd/thread2-r0drv-freebsd.c=>r0drv/freebsd/thread2-r0drv-freebsd.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/freebsd/time-r0drv-freebsd.c=>r0drv/freebsd/time-r0drv-freebsd.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/freebsd/timer-r0drv-freebsd.c=>r0drv/freebsd/timer-r0drv-freebsd.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/freebsd/sleepqueue-r0drv-freebsd.h=>r0drv/freebsd/sleepqueue-r0drv-freebsd.h \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/generic/semspinmutex-r0drv-generic.c=>r0drv/generic/semspinmutex-r0drv-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/generic/mpnotification-r0drv-generic.cpp=>r0drv/generic/mpnotification-r0drv-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/generic/RTMpIsCpuWorkPending-r0drv-generic.cpp=>r0drv/generic/RTMpIsCpuWorkPending-r0drv-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/memobj-r0drv.cpp=>r0drv/memobj-r0drv.c \
+    ${PATH_ROOT}/src/VBox/Runtime/VBox/log-vbox.cpp=>VBox/log-vbox.c \
+    ${PATH_ROOT}/src/VBox/Runtime/VBox/logbackdoor.cpp=>VBox/logbackdoor.c \
+    ${PATH_ROOT}/src/VBox/Runtime/VBox/RTLogWriteVmm-amd64-x86.cpp=>VBox/RTLogWriteVmm-amd64-x86.c \
+    ${PATH_OUT}/version-generated.h=>version-generated.h \
+    ${PATH_OUT}/product-generated.h=>product-generated.h \
+    ${PATH_OUT}/revision-generated.h=>revision-generated.h \
+"
+
+FILES_VBOXGUEST_BIN=" \
+"
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/Makefile.kmk b/src/VBox/Additions/common/VBoxGuest/lib/Makefile.kmk
new file mode 100644
index 00000000..eead95e5
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/Makefile.kmk
@@ -0,0 +1,254 @@
+# $Id: Makefile.kmk $
+## @file
+# Sub-Makefile for the common guest addition code library.
+#
+
+#
+# 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
+#
+
+SUB_DEPTH = ../../../../../..
+include $(KBUILD_PATH)/subheader.kmk
+
+include $(PATH_SUB_CURRENT)/testcase/Makefile.kmk
+
+#
+# Target config.
+#
+if defined(VBOX_WITH_ADDITION_DRIVERS) && !defined(VBOX_ONLY_VALIDATIONKIT)
+ LIBRARIES += \
+ 	VBoxGuestR0Lib \
+ 	VBoxGuestR0LibBase
+endif
+LIBRARIES += \
+	VBoxGuestR3Lib \
+	VBoxGuestR3LibShared
+ifndef VBOX_ONLY_VALIDATIONKIT
+ if1of ($(KBUILD_TARGET), freebsd linux netbsd openbsd)
+  ifndef VBOX_USE_SYSTEM_XORG_HEADERS
+   LIBRARIES += \
+   	VBoxGuestR3LibXFree86
+  endif
+ endif
+ if1of ($(KBUILD_TARGET), freebsd linux netbsd openbsd solaris)
+  LIBRARIES += \
+  	VBoxGuestR3LibXOrg
+ endif
+endif
+LIBRARIES.win.amd64 += VBoxGuestR3Lib-x86 VBoxGuestR3LibShared-x86
+
+
+#
+# VBoxGuestR0Lib
+#
+VBoxGuestR0Lib_TEMPLATE     = VBoxGuestR0DrvLib
+VBoxGuestR0Lib_DEFS         = VBOX_WITH_HGCM \
+	$(if $(VBOX_WITH_DRAG_AND_DROP),VBOX_WITH_DRAG_AND_DROP,) \
+	$(if $(VBOX_WITH_DRAG_AND_DROP_GH),VBOX_WITH_DRAG_AND_DROP_GH,)
+VBoxGuestR0Lib_INCS         = \
+	$(VBoxGuestR0Lib_0_OUTDIR)
+VBoxGuestR0Lib_SOURCES      = \
+	VBoxGuestR0LibInit.cpp \
+	VBoxGuestR0LibPhysHeap.cpp \
+	VBoxGuestR0LibGenericRequest.cpp \
+	VBoxGuestR0LibVMMDev.cpp \
+	VBoxGuestR0LibHGCM.cpp \
+	VbglR0CanUsePhysPageList.cpp \
+	\
+	VBoxGuestR0LibIdc.cpp \
+	VBoxGuestR0LibSharedFolders.c \
+	VBoxGuestR0LibCrOgl.cpp \
+	VBoxGuestR0LibMouse.cpp
+VBoxGuestR0Lib_SOURCES.os2     = VBoxGuestR0LibIdc-os2.cpp
+VBoxGuestR0Lib_SOURCES.solaris = VBoxGuestR0LibIdc-solaris.cpp
+VBoxGuestR0Lib_SOURCES.win     = VBoxGuestR0LibIdc-win.cpp
+ifn1of ($(KBUILD_TARGET), os2 solaris win)
+ VBoxGuestR0Lib_SOURCES       += VBoxGuestR0LibIdc-unix.cpp
+endif
+
+#
+# VBoxGuestR0LibBase
+#
+VBoxGuestR0LibBase_TEMPLATE = VBoxGuestR0DrvLib
+VBoxGuestR0LibBase_DEFS     = VBOX_WITH_HGCM VBGL_VBOXGUEST \
+	$(if $(VBOX_WITH_DRAG_AND_DROP),VBOX_WITH_DRAG_AND_DROP,) \
+	$(if $(VBOX_WITH_DRAG_AND_DROP_GH),VBOX_WITH_DRAG_AND_DROP_GH,)
+VBoxGuestR0LibBase_INCS     = $(VBoxGuestR0Lib_INCS)
+VBoxGuestR0LibBase_INCS.win = $(VBoxGuestR0Lib_INCS.win)
+VBoxGuestR0LibBase_SOURCES  = \
+	VBoxGuestR0LibInit.cpp \
+	VBoxGuestR0LibPhysHeap.cpp \
+	VBoxGuestR0LibGenericRequest.cpp \
+	VBoxGuestR0LibVMMDev.cpp \
+	VBoxGuestR0LibHGCMInternal.cpp \
+	VbglR0CanUsePhysPageList.cpp
+
+#
+# VBoxGuestR3Lib
+#
+VBoxGuestR3Lib_TEMPLATE   := VBoxGuestR3Lib
+VBoxGuestR3Lib_DEFS        = \
+	VBOX_WITH_HGCM \
+	$(if $(VBOX_WITH_GUEST_PROPS),VBOX_WITH_GUEST_PROPS,) \
+	$(if $(VBOX_WITH_SHARED_CLIPBOARD),VBOX_WITH_SHARED_CLIPBOARD,) \
+	$(if $(VBOX_WITH_SHARED_CLIPBOARD_TRANSFERS),VBOX_WITH_SHARED_CLIPBOARD_TRANSFERS,) \
+	$(if $(VBOX_WITH_SHARED_FOLDERS),VBOX_WITH_SHARED_FOLDERS,) \
+	$(if $(VBOX_WITH_GUEST_CONTROL),VBOX_WITH_GUEST_CONTROL,)
+VBoxGuestR3Lib_SOURCES     = \
+	VBoxGuestR3Lib.cpp \
+	VBoxGuestR3LibAdditions.cpp \
+	VBoxGuestR3LibAutoLogon.cpp \
+	VBoxGuestR3LibBalloon.cpp \
+	VBoxGuestR3LibCoreDump.cpp \
+	VBoxGuestR3LibCpuHotPlug.cpp \
+	VBoxGuestR3LibCredentials.cpp \
+	VBoxGuestR3LibDrmClient.cpp \
+	VBoxGuestR3LibEvent.cpp \
+	VBoxGuestR3LibGuestUser.cpp \
+	VBoxGuestR3LibGR.cpp \
+	VBoxGuestR3LibHGCM.cpp \
+	VBoxGuestR3LibHostChannel.cpp \
+	VBoxGuestR3LibLog.cpp \
+	VBoxGuestR3LibMisc.cpp \
+	VBoxGuestR3LibStat.cpp \
+	VBoxGuestR3LibTime.cpp \
+	VBoxGuestR3LibModule.cpp \
+	VBoxGuestR3LibPidFile.cpp \
+	VBoxGuestR3LibVrdp.cpp \
+	VBoxGuestR3LibMouse.cpp \
+	VBoxGuestR3LibSeamless.cpp \
+	VBoxGuestR3LibVideo.cpp
+ifneq ($(KBUILD_TARGET),win)
+ VBoxGuestR3Lib_SOURCES   += \
+ 	VBoxGuestR3LibDaemonize.cpp
+endif
+ifdef VBOX_WITH_GUEST_PROPS
+ VBoxGuestR3Lib_SOURCES   += \
+ 	VBoxGuestR3LibGuestProp.cpp \
+ 	VBoxGuestR3LibHostVersion.cpp
+endif
+ifdef VBOX_WITH_SHARED_CLIPBOARD
+ VBoxGuestR3Lib_DEFS      += VBOX_WITH_SHARED_CLIPBOARD_GUEST
+ VBoxGuestR3Lib_SOURCES   += \
+ 	VBoxGuestR3LibClipboard.cpp
+ ifdef VBOX_WITH_SHARED_CLIPBOARD_TRANSFERS
+  VBoxGuestR3Lib_SOURCES  += \
+  	$(PATH_ROOT)/src/VBox/GuestHost/SharedClipboard/ClipboardMIME.cpp
+ endif
+endif
+ifdef VBOX_WITH_SHARED_FOLDERS
+ VBoxGuestR3Lib_SOURCES   += \
+ 	VBoxGuestR3LibSharedFolders.cpp
+endif
+ifdef VBOX_WITH_GUEST_CONTROL
+ VBoxGuestR3Lib_SOURCES   += \
+ 	VBoxGuestR3LibGuestCtrl.cpp
+endif
+ifdef VBOX_WITH_DRAG_AND_DROP
+ VBoxGuestR3Lib_DEFS      += \
+ 	VBOX_WITH_DRAG_AND_DROP \
+ 	$(if $(VBOX_WITH_DRAG_AND_DROP_GH),VBOX_WITH_DRAG_AND_DROP_GH,)
+ VBoxGuestR3Lib_SOURCES   += \
+ 	VBoxGuestR3LibDragAndDrop.cpp
+endif
+
+VBoxGuestR3LibAdditions.cpp_DEFS = VBOX_SVN_REV=$(VBOX_SVN_REV)
+
+#
+# VBoxGuestR3LibShared - a PIC variant of VBoxGuestR3Lib for linking into .so/.dll/.dylib.
+#
+VBoxGuestR3LibShared_TEMPLATE := VBoxGuestR3Dll
+VBoxGuestR3LibShared_DEFS     := $(VBoxGuestR3Lib_DEFS)
+VBoxGuestR3LibShared_SOURCES  := $(VBoxGuestR3Lib_SOURCES)
+VBoxGuestR3LibShared_INST     := $(INST_ADDITIONS_LIB)
+
+
+#
+# VBoxGuestR3Lib-x86 - an x86 (32-bit) variant of VBoxGuestR3Lib for 64-bit Windows.
+#
+VBoxGuestR3Lib-x86_EXTENDS      := VBoxGuestR3Lib
+VBoxGuestR3Lib-x86_BLD_TRG_ARCH := x86
+
+
+#
+# VBoxGuestR3LibShared-x86 - an x86 (32-bit) variant of VBoxGuestR3LibShared for 64-bit Windows.
+#
+VBoxGuestR3LibShared-x86_EXTENDS      := VBoxGuestR3LibShared
+VBoxGuestR3LibShared-x86_BLD_TRG_ARCH := x86
+
+
+#
+# VBoxGuestR3LibXFree86 - a reduced version of the guest library which uses
+# the X server runtime instead of IPRT, for use with old servers where the
+# C library is not available.
+#
+VBoxGuestR3LibXFree86_TEMPLATE = VBoxGuestR3XFree86Lib
+VBoxGuestR3LibXFree86_DEFS     = \
+	VBOX_WITH_HGCM \
+	VBOX_VBGLR3_XFREE86 \
+	RTMEM_NO_WRAP_TO_EF_APIS \
+	$(if $(VBOX_WITH_GUEST_PROPS),VBOX_WITH_GUEST_PROPS,) \
+	$(if $(VBOX_WITH_DRAG_AND_DROP),VBOX_WITH_DRAG_AND_DROP,) \
+	$(if $(VBOX_WITH_DRAG_AND_DROP_GH),VBOX_WITH_DRAG_AND_DROP_GH,) \
+	$(if $(VBOX_WITH_SHARED_CLIPBOARD_TRANSFERS),VBOX_WITH_SHARED_CLIPBOARD_TRANSFERS,)
+VBoxGuestR3LibXFree86_SOURCES  = \
+	VBoxGuestR3Lib.cpp \
+	VBoxGuestR3LibGR.cpp \
+	$(if $(VBOX_WITH_GUEST_PROPS),VBoxGuestR3LibGuestProp.cpp,) \
+	VBoxGuestR3LibMouse.cpp \
+	VBoxGuestR3LibMisc.cpp \
+	VBoxGuestR3LibSeamless.cpp \
+	VBoxGuestR3LibVideo.cpp \
+	VBoxGuestR3LibRuntimeXF86.cpp
+VBoxGuestR3LibXFree86_INCS     = \
+	$(VBOX_PATH_X11_ROOT)/XFree86-4.3/Xserver \
+	$(VBOX_PATH_X11_ROOT)/XFree86-4.3 \
+	$(VBOX_PATH_X11_ROOT)/XFree86-4.3/X11
+
+#
+# VBoxGuestR3LibXOrg - a reduced version of the guest library which uses
+# the C server runtime instead of IPRT.
+#
+VBoxGuestR3LibXOrg_TEMPLATE = VBoxGuestR3XOrgLib
+VBoxGuestR3LibXOrg_DEFS     = \
+	VBOX_WITH_HGCM \
+	VBOX_VBGLR3_XORG \
+	RTMEM_NO_WRAP_TO_EF_APIS \
+	IN_RT_STATIC \
+	$(if $(VBOX_WITH_GUEST_PROPS),VBOX_WITH_GUEST_PROPS,) \
+	$(if $(VBOX_WITH_DRAG_AND_DROP),VBOX_WITH_DRAG_AND_DROP,) \
+	$(if $(VBOX_WITH_DRAG_AND_DROP_GH),VBOX_WITH_DRAG_AND_DROP_GH,) \
+	$(if $(VBOX_WITH_SHARED_CLIPBOARD_TRANSFERS),VBOX_WITH_SHARED_CLIPBOARD_TRANSFERS,)
+VBoxGuestR3LibXOrg_SOURCES  = $(VBoxGuestR3LibXFree86_SOURCES)
+
+VBoxGuestR3LibRuntimeXF86.cpp_CXXFLAGS = -Wno-shadow
+
+include $(FILE_KBUILD_SUB_FOOTER)
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibCrOgl.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibCrOgl.cpp
new file mode 100644
index 00000000..a6638dc0
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibCrOgl.cpp
@@ -0,0 +1,134 @@
+/* $Id: VBoxGuestR0LibCrOgl.cpp $ */
+/** @file
+ * VBoxGuestLib - Ring-3 Support Library for VirtualBox guest additions, Chromium OpenGL Service.
+ */
+
+/*
+ * Copyright (C) 2012-2023 Oracle and/or its affiliates.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/string.h>
+#include "VBoxGuestR0LibInternal.h"
+
+#ifdef VBGL_VBOXGUEST
+# error "This file shouldn't be part of the VBoxGuestR0LibBase library that is linked into VBoxGuest.  It's client code."
+#endif
+
+
+DECLR0VBGL(int) VbglR0CrCtlCreate(VBGLCRCTLHANDLE *phCtl)
+{
+    int rc;
+
+    if (phCtl)
+    {
+        struct VBGLHGCMHANDLEDATA *pHandleData = vbglR0HGCMHandleAlloc();
+        if (pHandleData)
+        {
+            rc = VbglR0IdcOpen(&pHandleData->IdcHandle,
+                               VBGL_IOC_VERSION /*uReqVersion*/,
+                               VBGL_IOC_VERSION & UINT32_C(0xffff0000) /*uMinVersion*/,
+                               NULL /*puSessionVersion*/, NULL /*puDriverVersion*/, NULL /*uDriverRevision*/);
+            if (RT_SUCCESS(rc))
+            {
+                *phCtl = pHandleData;
+                return VINF_SUCCESS;
+            }
+
+            vbglR0HGCMHandleFree(pHandleData);
+        }
+        else
+            rc = VERR_NO_MEMORY;
+
+        *phCtl = NULL;
+    }
+    else
+        rc = VERR_INVALID_PARAMETER;
+
+    return rc;
+}
+
+DECLR0VBGL(int) VbglR0CrCtlDestroy(VBGLCRCTLHANDLE hCtl)
+{
+    VbglR0IdcClose(&hCtl->IdcHandle);
+
+    vbglR0HGCMHandleFree(hCtl);
+
+    return VINF_SUCCESS;
+}
+
+DECLR0VBGL(int) VbglR0CrCtlConConnect(VBGLCRCTLHANDLE hCtl, HGCMCLIENTID *pidClient)
+{
+    VBGLIOCHGCMCONNECT info;
+    int rc;
+
+    if (!hCtl || !pidClient)
+        return VERR_INVALID_PARAMETER;
+
+    RT_ZERO(info);
+    VBGLREQHDR_INIT(&info.Hdr, HGCM_CONNECT);
+    info.u.In.Loc.type = VMMDevHGCMLoc_LocalHost_Existing;
+    RTStrCopy(info.u.In.Loc.u.host.achName, sizeof(info.u.In.Loc.u.host.achName), "VBoxSharedCrOpenGL");
+    rc = VbglR0IdcCall(&hCtl->IdcHandle, VBGL_IOCTL_HGCM_CONNECT, &info.Hdr, sizeof(info));
+    if (RT_SUCCESS(rc))
+    {
+        Assert(info.u.Out.idClient);
+        *pidClient = info.u.Out.idClient;
+        return rc;
+    }
+
+    AssertRC(rc);
+    *pidClient = 0;
+    return rc;
+}
+
+DECLR0VBGL(int) VbglR0CrCtlConDisconnect(VBGLCRCTLHANDLE hCtl, HGCMCLIENTID idClient)
+{
+    VBGLIOCHGCMDISCONNECT info;
+    VBGLREQHDR_INIT(&info.Hdr, HGCM_DISCONNECT);
+    info.u.In.idClient = idClient;
+    return VbglR0IdcCall(&hCtl->IdcHandle, VBGL_IOCTL_HGCM_DISCONNECT, &info.Hdr, sizeof(info));
+}
+
+DECLR0VBGL(int) VbglR0CrCtlConCallRaw(VBGLCRCTLHANDLE hCtl, PVBGLIOCHGCMCALL pCallInfo, int cbCallInfo)
+{
+    return VbglR0IdcCallRaw(&hCtl->IdcHandle, VBGL_IOCTL_HGCM_CALL(cbCallInfo), &pCallInfo->Hdr, cbCallInfo);
+}
+
+DECLR0VBGL(int) VbglR0CrCtlConCall(VBGLCRCTLHANDLE hCtl, PVBGLIOCHGCMCALL pCallInfo, int cbCallInfo)
+{
+    int rc = VbglR0IdcCallRaw(&hCtl->IdcHandle, VBGL_IOCTL_HGCM_CALL(cbCallInfo), &pCallInfo->Hdr, cbCallInfo);
+    if (RT_SUCCESS(rc))
+        rc = pCallInfo->Hdr.rc;
+    return rc;
+}
+
+DECLR0VBGL(int) VbglR0CrCtlConCallUserDataRaw(VBGLCRCTLHANDLE hCtl, PVBGLIOCHGCMCALL pCallInfo, int cbCallInfo)
+{
+    return VbglR0IdcCallRaw(&hCtl->IdcHandle, VBGL_IOCTL_HGCM_CALL_WITH_USER_DATA(cbCallInfo), &pCallInfo->Hdr, cbCallInfo);
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibGenericRequest.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibGenericRequest.cpp
new file mode 100644
index 00000000..72518a3e
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibGenericRequest.cpp
@@ -0,0 +1,183 @@
+/* $Id: VBoxGuestR0LibGenericRequest.cpp $ */
+/** @file
+ * VBoxGuestLibR0 - Generic VMMDev request management.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "VBoxGuestR0LibInternal.h"
+#include <iprt/asm.h>
+#include <iprt/asm-amd64-x86.h>
+#include <iprt/assert.h>
+#include <iprt/string.h>
+#include <VBox/err.h>
+
+
+DECLR0VBGL(int) VbglGR0Verify(const VMMDevRequestHeader *pReq, size_t cbReq)
+{
+    size_t cbReqExpected;
+
+    if (RT_UNLIKELY(!pReq || cbReq < sizeof(VMMDevRequestHeader)))
+    {
+        dprintf(("VbglGR0Verify: Invalid parameter: pReq = %p, cbReq = %zu\n", pReq, cbReq));
+        return VERR_INVALID_PARAMETER;
+    }
+
+    if (RT_UNLIKELY(pReq->size > cbReq))
+    {
+        dprintf(("VbglGR0Verify: request size %u > buffer size %zu\n", pReq->size, cbReq));
+        return VERR_INVALID_PARAMETER;
+    }
+
+    /* The request size must correspond to the request type. */
+    cbReqExpected = vmmdevGetRequestSize(pReq->requestType);
+    if (RT_UNLIKELY(cbReq < cbReqExpected))
+    {
+        dprintf(("VbglGR0Verify: buffer size %zu < expected size %zu\n", cbReq, cbReqExpected));
+        return VERR_INVALID_PARAMETER;
+    }
+
+    if (cbReqExpected == cbReq)
+    {
+        /*
+         * This is most likely a fixed size request, and in this case the
+         * request size must be also equal to the expected size.
+         */
+        if (RT_UNLIKELY(pReq->size != cbReqExpected))
+        {
+            dprintf(("VbglGR0Verify: request size %u != expected size %zu\n", pReq->size, cbReqExpected));
+            return VERR_INVALID_PARAMETER;
+        }
+
+        return VINF_SUCCESS;
+    }
+
+    /*
+     * This can be a variable size request. Check the request type and limit the size
+     * to VMMDEV_MAX_VMMDEVREQ_SIZE, which is max size supported by the host.
+     *
+     * Note: Keep this list sorted for easier human lookup!
+     */
+    if (   pReq->requestType == VMMDevReq_ChangeMemBalloon
+        || pReq->requestType == VMMDevReq_GetDisplayChangeRequestMulti
+#ifdef VBOX_WITH_64_BITS_GUESTS
+        || pReq->requestType == VMMDevReq_HGCMCall64
+#endif
+        || pReq->requestType == VMMDevReq_HGCMCall32
+        || pReq->requestType == VMMDevReq_RegisterSharedModule
+        || pReq->requestType == VMMDevReq_ReportGuestUserState
+        || pReq->requestType == VMMDevReq_LogString
+        || pReq->requestType == VMMDevReq_SetPointerShape
+        || pReq->requestType == VMMDevReq_VideoSetVisibleRegion
+        || pReq->requestType == VMMDevReq_VideoUpdateMonitorPositions)
+    {
+        if (RT_UNLIKELY(cbReq > VMMDEV_MAX_VMMDEVREQ_SIZE))
+        {
+            dprintf(("VbglGR0Verify: VMMDevReq_LogString: buffer size %zu too big\n", cbReq));
+            return VERR_BUFFER_OVERFLOW; /** @todo is this error code ok? */
+        }
+    }
+    else
+    {
+        dprintf(("VbglGR0Verify: request size %u > buffer size %zu\n", pReq->size, cbReq));
+        return VERR_IO_BAD_LENGTH; /** @todo is this error code ok? */
+    }
+
+    return VINF_SUCCESS;
+}
+
+DECLR0VBGL(int) VbglR0GRAlloc(VMMDevRequestHeader **ppReq, size_t cbReq, VMMDevRequestType enmReqType)
+{
+    int rc = vbglR0Enter();
+    if (RT_SUCCESS(rc))
+    {
+        if (   ppReq
+            && cbReq >= sizeof(VMMDevRequestHeader)
+            && cbReq == (uint32_t)cbReq)
+        {
+            VMMDevRequestHeader *pReq = (VMMDevRequestHeader *)VbglR0PhysHeapAlloc((uint32_t)cbReq);
+            AssertMsgReturn(pReq, ("VbglR0GRAlloc: no memory (cbReq=%u)\n", cbReq), VERR_NO_MEMORY);
+            memset(pReq, 0xAA, cbReq);
+
+            pReq->size        = (uint32_t)cbReq;
+            pReq->version     = VMMDEV_REQUEST_HEADER_VERSION;
+            pReq->requestType = enmReqType;
+            pReq->rc          = VERR_GENERAL_FAILURE;
+            pReq->reserved1   = 0;
+#ifdef VBGL_VBOXGUEST
+            pReq->fRequestor  = VMMDEV_REQUESTOR_KERNEL        | VMMDEV_REQUESTOR_USR_DRV
+#else
+            pReq->fRequestor  = VMMDEV_REQUESTOR_KERNEL        | VMMDEV_REQUESTOR_USR_DRV_OTHER
+#endif
+
+                              | VMMDEV_REQUESTOR_CON_DONT_KNOW | VMMDEV_REQUESTOR_TRUST_NOT_GIVEN;
+            *ppReq = pReq;
+            rc = VINF_SUCCESS;
+        }
+        else
+        {
+            dprintf(("VbglR0GRAlloc: Invalid parameter: ppReq=%p cbReq=%u\n", ppReq, cbReq));
+            rc = VERR_INVALID_PARAMETER;
+        }
+    }
+    return rc;
+}
+
+DECLR0VBGL(int) VbglR0GRPerform(VMMDevRequestHeader *pReq)
+{
+    int rc = vbglR0Enter();
+    if (RT_SUCCESS(rc))
+    {
+        if (pReq)
+        {
+            RTCCPHYS PhysAddr = VbglR0PhysHeapGetPhysAddr(pReq);
+            if (   PhysAddr != 0
+                && PhysAddr < _4G) /* Port IO is 32 bit. */
+            {
+                ASMOutU32(g_vbgldata.portVMMDev + VMMDEV_PORT_OFF_REQUEST, (uint32_t)PhysAddr);
+                /* Make the compiler aware that the host has changed memory. */
+                ASMCompilerBarrier();
+                rc = pReq->rc;
+            }
+            else
+                rc = VERR_VBGL_INVALID_ADDR;
+        }
+        else
+            rc = VERR_INVALID_PARAMETER;
+    }
+    return rc;
+}
+
+DECLR0VBGL(void) VbglR0GRFree(VMMDevRequestHeader *pReq)
+{
+    int rc = vbglR0Enter();
+    if (RT_SUCCESS(rc))
+        VbglR0PhysHeapFree(pReq);
+}
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibHGCM.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibHGCM.cpp
new file mode 100644
index 00000000..e2e28ebb
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibHGCM.cpp
@@ -0,0 +1,240 @@
+/* $Id: VBoxGuestR0LibHGCM.cpp $ */
+/** @file
+ * VBoxGuestLib - Host-Guest Communication Manager, ring-0 client drivers.
+ *
+ * These public functions can be only used by other drivers. They all
+ * do an IOCTL to VBoxGuest via IDC.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "VBoxGuestR0LibInternal.h"
+
+#include <iprt/assert.h>
+#include <iprt/semaphore.h>
+#include <iprt/string.h>
+#include <VBox/err.h>
+
+#ifdef VBGL_VBOXGUEST
+# error "This file shouldn't be part of the VBoxGuestR0LibBase library that is linked into VBoxGuest.  It's client code."
+#endif
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+#define VBGL_HGCM_ASSERT_MSG AssertReleaseMsg
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/**
+ * Fast heap for HGCM handles data.
+ * @{
+ */
+static RTSEMFASTMUTEX            g_hMtxHGCMHandleData;
+static struct VBGLHGCMHANDLEDATA g_aHGCMHandleData[64];
+/** @} */
+
+
+/**
+ * Initializes the HGCM VBGL bits.
+ *
+ * @return VBox status code.
+ */
+DECLR0VBGL(int) VbglR0HGCMInit(void)
+{
+    AssertReturn(g_hMtxHGCMHandleData == NIL_RTSEMFASTMUTEX, VINF_ALREADY_INITIALIZED);
+    return RTSemFastMutexCreate(&g_hMtxHGCMHandleData);
+}
+
+/**
+ * Initializes the HGCM VBGL bits.
+ *
+ * @return VBox status code.
+ */
+DECLR0VBGL(int) VbglR0HGCMTerminate(void)
+{
+    RTSemFastMutexDestroy(g_hMtxHGCMHandleData);
+    g_hMtxHGCMHandleData = NIL_RTSEMFASTMUTEX;
+
+    return VINF_SUCCESS;
+}
+
+DECLINLINE(int) vbglR0HandleHeapEnter(void)
+{
+    int rc = RTSemFastMutexRequest(g_hMtxHGCMHandleData);
+
+    VBGL_HGCM_ASSERT_MSG(RT_SUCCESS(rc), ("Failed to request handle heap mutex, rc = %Rrc\n", rc));
+
+    return rc;
+}
+
+DECLINLINE(void) vbglR0HandleHeapLeave(void)
+{
+    RTSemFastMutexRelease(g_hMtxHGCMHandleData);
+}
+
+struct VBGLHGCMHANDLEDATA *vbglR0HGCMHandleAlloc(void)
+{
+    struct VBGLHGCMHANDLEDATA *p = NULL;
+    int rc = vbglR0HandleHeapEnter();
+    if (RT_SUCCESS(rc))
+    {
+        uint32_t i;
+
+        /* Simple linear search in array. This will be called not so often, only connect/disconnect. */
+        /** @todo bitmap for faster search and other obvious optimizations. */
+        for (i = 0; i < RT_ELEMENTS(g_aHGCMHandleData); i++)
+        {
+            if (!g_aHGCMHandleData[i].fAllocated)
+            {
+                p = &g_aHGCMHandleData[i];
+                p->fAllocated = 1;
+                break;
+            }
+        }
+
+        vbglR0HandleHeapLeave();
+
+        VBGL_HGCM_ASSERT_MSG(p != NULL, ("Not enough HGCM handles.\n"));
+    }
+    return p;
+}
+
+void vbglR0HGCMHandleFree(struct VBGLHGCMHANDLEDATA *pHandle)
+{
+    if (pHandle)
+    {
+        int rc = vbglR0HandleHeapEnter();
+        if (RT_SUCCESS(rc))
+        {
+            VBGL_HGCM_ASSERT_MSG(pHandle->fAllocated, ("Freeing not allocated handle.\n"));
+
+            RT_ZERO(*pHandle);
+            vbglR0HandleHeapLeave();
+        }
+    }
+}
+
+DECLR0VBGL(int) VbglR0HGCMConnect(VBGLHGCMHANDLE *pHandle, const char *pszServiceName, HGCMCLIENTID *pidClient)
+{
+    int rc;
+    if (pHandle && pszServiceName && pidClient)
+    {
+        struct VBGLHGCMHANDLEDATA *pHandleData = vbglR0HGCMHandleAlloc();
+        if (pHandleData)
+        {
+            rc = VbglR0IdcOpen(&pHandleData->IdcHandle,
+                               VBGL_IOC_VERSION /*uReqVersion*/,
+                               VBGL_IOC_VERSION & UINT32_C(0xffff0000) /*uMinVersion*/,
+                               NULL /*puSessionVersion*/, NULL /*puDriverVersion*/, NULL /*uDriverRevision*/);
+            if (RT_SUCCESS(rc))
+            {
+                VBGLIOCHGCMCONNECT Info;
+                RT_ZERO(Info);
+                VBGLREQHDR_INIT(&Info.Hdr, HGCM_CONNECT);
+                Info.u.In.Loc.type     = VMMDevHGCMLoc_LocalHost_Existing;
+                rc = RTStrCopy(Info.u.In.Loc.u.host.achName, sizeof(Info.u.In.Loc.u.host.achName), pszServiceName);
+                if (RT_SUCCESS(rc))
+                {
+                    rc = VbglR0IdcCall(&pHandleData->IdcHandle, VBGL_IOCTL_HGCM_CONNECT, &Info.Hdr, sizeof(Info));
+                    if (RT_SUCCESS(rc))
+                    {
+                        *pidClient = Info.u.Out.idClient;
+                        *pHandle   = pHandleData;
+                        return rc;
+                    }
+                }
+
+                VbglR0IdcClose(&pHandleData->IdcHandle);
+            }
+
+            vbglR0HGCMHandleFree(pHandleData);
+        }
+        else
+            rc = VERR_NO_MEMORY;
+    }
+    else
+        rc = VERR_INVALID_PARAMETER;
+    return rc;
+}
+
+DECLR0VBGL(int) VbglR0HGCMDisconnect(VBGLHGCMHANDLE handle, HGCMCLIENTID idClient)
+{
+    int rc;
+    VBGLIOCHGCMDISCONNECT Info;
+
+    RT_ZERO(Info);
+    VBGLREQHDR_INIT(&Info.Hdr, HGCM_DISCONNECT);
+    Info.u.In.idClient = idClient;
+    rc = VbglR0IdcCall(&handle->IdcHandle, VBGL_IOCTL_HGCM_DISCONNECT, &Info.Hdr, sizeof(Info));
+
+    VbglR0IdcClose(&handle->IdcHandle);
+
+    vbglR0HGCMHandleFree(handle);
+
+    return rc;
+}
+
+DECLR0VBGL(int) VbglR0HGCMCallRaw(VBGLHGCMHANDLE handle, PVBGLIOCHGCMCALL pData, uint32_t cbData)
+{
+    VBGL_HGCM_ASSERT_MSG(cbData >= sizeof(VBGLIOCHGCMCALL) + pData->cParms * sizeof(HGCMFunctionParameter),
+                         ("cbData = %d, cParms = %d (calculated size %d)\n", cbData, pData->cParms,
+                          sizeof(VBGLIOCHGCMCALL) + pData->cParms * sizeof(VBGLIOCHGCMCALL)));
+
+    return VbglR0IdcCallRaw(&handle->IdcHandle, VBGL_IOCTL_HGCM_CALL(cbData), &pData->Hdr, cbData);
+}
+
+DECLR0VBGL(int) VbglR0HGCMCall(VBGLHGCMHANDLE handle, PVBGLIOCHGCMCALL pData, uint32_t cbData)
+{
+    int rc = VbglR0HGCMCallRaw(handle, pData, cbData);
+    if (RT_SUCCESS(rc))
+        rc = pData->Hdr.rc;
+    return rc;
+}
+
+DECLR0VBGL(int) VbglR0HGCMCallUserDataRaw(VBGLHGCMHANDLE handle, PVBGLIOCHGCMCALL pData, uint32_t cbData)
+{
+    VBGL_HGCM_ASSERT_MSG(cbData >= sizeof(VBGLIOCHGCMCALL) + pData->cParms * sizeof(HGCMFunctionParameter),
+                         ("cbData = %d, cParms = %d (calculated size %d)\n", cbData, pData->cParms,
+                          sizeof(VBGLIOCHGCMCALL) + pData->cParms * sizeof(VBGLIOCHGCMCALL)));
+
+    return VbglR0IdcCallRaw(&handle->IdcHandle, VBGL_IOCTL_HGCM_CALL_WITH_USER_DATA(cbData), &pData->Hdr, cbData);
+}
+
+
+DECLR0VBGL(int) VbglR0HGCMFastCall(VBGLHGCMHANDLE hHandle, PVBGLIOCIDCHGCMFASTCALL pCallReq, uint32_t cbCallReq)
+{
+    /* pCallReq->Hdr.rc and pCallReq->HgcmCallReq.header.header.rc; are not used by this IDC. */
+    return VbglR0IdcCallRaw(&hHandle->IdcHandle, VBGL_IOCTL_IDC_HGCM_FAST_CALL, &pCallReq->Hdr, cbCallReq);
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibHGCMInternal.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibHGCMInternal.cpp
new file mode 100644
index 00000000..2a237db1
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibHGCMInternal.cpp
@@ -0,0 +1,1175 @@
+/* $Id: VBoxGuestR0LibHGCMInternal.cpp $ */
+/** @file
+ * VBoxGuestLib - Host-Guest Communication Manager internal functions, implemented by VBoxGuest
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define LOG_GROUP LOG_GROUP_HGCM
+
+#include "VBoxGuestR0LibInternal.h"
+#include <iprt/asm.h>
+#include <iprt/assert.h>
+#include <iprt/mem.h>
+#include <iprt/memobj.h>
+#include <iprt/string.h>
+#include <iprt/thread.h>
+#include <iprt/time.h>
+#include <VBox/err.h>
+
+#ifndef VBGL_VBOXGUEST
+# error "This file should only be part of the VBoxGuestR0LibBase library that is linked into VBoxGuest."
+#endif
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+/** The max parameter buffer size for a user request. */
+#define VBGLR0_MAX_HGCM_USER_PARM       (24*_1M)
+/** The max parameter buffer size for a kernel request. */
+#define VBGLR0_MAX_HGCM_KERNEL_PARM     (16*_1M)
+/** The max embedded buffer size. */
+#define VBGLR0_MAX_HGCM_EMBEDDED_BUFFER _64K
+
+#if defined(RT_OS_LINUX) || defined(RT_OS_DARWIN)
+/** Linux needs to use bounce buffers since RTR0MemObjLockUser has unwanted
+ * side effects.
+ * Darwin 32bit & 64bit also needs this because of 4GB/4GB user/kernel space. */
+# define USE_BOUNCE_BUFFERS
+#endif
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Lock info structure used by VbglR0HGCMInternalCall and its helpers.
+ */
+struct VbglR0ParmInfo
+{
+    uint32_t cLockBufs;
+    struct
+    {
+        uint32_t    iParm;
+        RTR0MEMOBJ  hObj;
+#ifdef USE_BOUNCE_BUFFERS
+        void       *pvSmallBuf;
+#endif
+    } aLockBufs[10];
+};
+
+
+
+/* These functions can be only used by VBoxGuest. */
+
+DECLR0VBGL(int) VbglR0HGCMInternalConnect(HGCMServiceLocation const *pLoc, uint32_t fRequestor, HGCMCLIENTID *pidClient,
+                                          PFNVBGLHGCMCALLBACK pfnAsyncCallback, void *pvAsyncData, uint32_t u32AsyncData)
+{
+    int rc;
+    if (   RT_VALID_PTR(pLoc)
+        && RT_VALID_PTR(pidClient)
+        && RT_VALID_PTR(pfnAsyncCallback))
+    {
+        /* Allocate request */
+        VMMDevHGCMConnect *pHGCMConnect = NULL;
+        rc = VbglR0GRAlloc((VMMDevRequestHeader **)&pHGCMConnect, sizeof(VMMDevHGCMConnect), VMMDevReq_HGCMConnect);
+        if (RT_SUCCESS(rc))
+        {
+            /* Initialize request memory */
+            pHGCMConnect->header.header.fRequestor = fRequestor;
+
+            pHGCMConnect->header.fu32Flags = 0;
+
+            memcpy(&pHGCMConnect->loc, pLoc, sizeof(pHGCMConnect->loc));
+            pHGCMConnect->u32ClientID = 0;
+
+            /* Issue request */
+            rc = VbglR0GRPerform (&pHGCMConnect->header.header);
+            if (RT_SUCCESS(rc))
+            {
+                /* Check if host decides to process the request asynchronously. */
+                if (rc == VINF_HGCM_ASYNC_EXECUTE)
+                {
+                    /* Wait for request completion interrupt notification from host */
+                    pfnAsyncCallback(&pHGCMConnect->header, pvAsyncData, u32AsyncData);
+                }
+
+                rc = pHGCMConnect->header.result;
+                if (RT_SUCCESS(rc))
+                    *pidClient = pHGCMConnect->u32ClientID;
+            }
+            VbglR0GRFree(&pHGCMConnect->header.header);
+        }
+    }
+    else
+        rc = VERR_INVALID_PARAMETER;
+    return rc;
+}
+
+
+DECLR0VBGL(int) VbglR0HGCMInternalDisconnect(HGCMCLIENTID idClient, uint32_t fRequestor,
+                                             PFNVBGLHGCMCALLBACK pfnAsyncCallback, void *pvAsyncData, uint32_t u32AsyncData)
+{
+    int rc;
+    if (   idClient != 0
+        && pfnAsyncCallback)
+    {
+        /* Allocate request */
+        VMMDevHGCMDisconnect *pHGCMDisconnect = NULL;
+        rc = VbglR0GRAlloc ((VMMDevRequestHeader **)&pHGCMDisconnect, sizeof (VMMDevHGCMDisconnect), VMMDevReq_HGCMDisconnect);
+        if (RT_SUCCESS(rc))
+        {
+            /* Initialize request memory */
+            pHGCMDisconnect->header.header.fRequestor = fRequestor;
+
+            pHGCMDisconnect->header.fu32Flags = 0;
+
+            pHGCMDisconnect->u32ClientID = idClient;
+
+            /* Issue request */
+            rc = VbglR0GRPerform(&pHGCMDisconnect->header.header);
+            if (RT_SUCCESS(rc))
+            {
+                /* Check if host decides to process the request asynchronously. */
+                if (rc == VINF_HGCM_ASYNC_EXECUTE)
+                {
+                    /* Wait for request completion interrupt notification from host */
+                    pfnAsyncCallback(&pHGCMDisconnect->header, pvAsyncData, u32AsyncData);
+                }
+
+                rc = pHGCMDisconnect->header.result;
+            }
+
+            VbglR0GRFree(&pHGCMDisconnect->header.header);
+        }
+    }
+    else
+        rc = VERR_INVALID_PARAMETER;
+    return rc;
+}
+
+
+/**
+ * Preprocesses the HGCM call, validating and locking/buffering parameters.
+ *
+ * @returns VBox status code.
+ *
+ * @param   pCallInfo       The call info.
+ * @param   cbCallInfo      The size of the call info structure.
+ * @param   fIsUser         Is it a user request or kernel request.
+ * @param   pcbExtra        Where to return the extra request space needed for
+ *                          physical page lists.
+ */
+static int vbglR0HGCMInternalPreprocessCall(PCVBGLIOCHGCMCALL pCallInfo, uint32_t cbCallInfo,
+                                            bool fIsUser, struct VbglR0ParmInfo *pParmInfo,  size_t *pcbExtra)
+{
+    HGCMFunctionParameter const *pSrcParm = VBGL_HGCM_GET_CALL_PARMS(pCallInfo);
+    uint32_t const               cParms   = pCallInfo->cParms;
+    uint32_t                     iParm;
+    uint32_t                     cb;
+
+    /*
+     * Lock down the any linear buffers so we can get their addresses
+     * and figure out how much extra storage we need for page lists.
+     *
+     * Note! With kernel mode users we can be assertive. For user mode users
+     *       we should just (debug) log it and fail without any fanfare.
+     */
+    *pcbExtra = 0;
+    pParmInfo->cLockBufs = 0;
+    for (iParm = 0; iParm < cParms; iParm++, pSrcParm++)
+    {
+        switch (pSrcParm->type)
+        {
+            case VMMDevHGCMParmType_32bit:
+                Log4(("GstHGCMCall: parm=%u type=32bit: %#010x\n", iParm, pSrcParm->u.value32));
+                break;
+
+            case VMMDevHGCMParmType_64bit:
+                Log4(("GstHGCMCall: parm=%u type=64bit: %#018RX64\n", iParm, pSrcParm->u.value64));
+                break;
+
+            case VMMDevHGCMParmType_PageList:
+            case VMMDevHGCMParmType_ContiguousPageList:
+                if (fIsUser)
+                    return VERR_INVALID_PARAMETER;
+                cb = pSrcParm->u.PageList.size;
+                if (cb)
+                {
+                    uint32_t            off = pSrcParm->u.PageList.offset;
+                    HGCMPageListInfo   *pPgLst;
+                    uint32_t            cPages;
+                    uint32_t            u32;
+
+                    AssertMsgReturn(cb <= VBGLR0_MAX_HGCM_KERNEL_PARM, ("%#x > %#x\n", cb, VBGLR0_MAX_HGCM_KERNEL_PARM),
+                                    VERR_OUT_OF_RANGE);
+                    AssertMsgReturn(   off >= cParms * sizeof(HGCMFunctionParameter)
+                                    && off <= cbCallInfo - sizeof(HGCMPageListInfo),
+                                    ("offset=%#x cParms=%#x cbCallInfo=%#x\n", off, cParms, cbCallInfo),
+                                    VERR_INVALID_PARAMETER);
+
+                    pPgLst = (HGCMPageListInfo *)((uint8_t *)pCallInfo + off);
+                    cPages = pPgLst->cPages;
+                    u32    = RT_UOFFSETOF_DYN(HGCMPageListInfo, aPages[cPages]) + off;
+                    AssertMsgReturn(u32 <= cbCallInfo,
+                                    ("u32=%#x (cPages=%#x offset=%#x) cbCallInfo=%#x\n", u32, cPages, off, cbCallInfo),
+                                    VERR_INVALID_PARAMETER);
+                    AssertMsgReturn(pPgLst->offFirstPage < PAGE_SIZE, ("#x\n", pPgLst->offFirstPage), VERR_INVALID_PARAMETER);
+                    u32 = RT_ALIGN_32(pPgLst->offFirstPage + cb, PAGE_SIZE) >> PAGE_SHIFT;
+                    AssertMsgReturn(cPages == u32, ("cPages=%#x u32=%#x\n", cPages, u32), VERR_INVALID_PARAMETER);
+                    AssertMsgReturn(VBOX_HGCM_F_PARM_ARE_VALID(pPgLst->flags), ("%#x\n", pPgLst->flags), VERR_INVALID_PARAMETER);
+                    Log4(("GstHGCMCall: parm=%u type=pglst: cb=%#010x cPgs=%u offPg0=%#x flags=%#x\n",
+                          iParm, cb, cPages, pPgLst->offFirstPage, pPgLst->flags));
+                    u32 = cPages;
+                    while (u32-- > 0)
+                    {
+                        Log4(("GstHGCMCall:   pg#%u=%RHp\n", u32, pPgLst->aPages[u32]));
+                        AssertMsgReturn(!(pPgLst->aPages[u32] & (PAGE_OFFSET_MASK | UINT64_C(0xfff0000000000000))),
+                                        ("pg#%u=%RHp\n", u32, pPgLst->aPages[u32]),
+                                        VERR_INVALID_PARAMETER);
+                    }
+
+                    *pcbExtra += RT_UOFFSETOF_DYN(HGCMPageListInfo, aPages[pPgLst->cPages]);
+                }
+                else
+                    Log4(("GstHGCMCall: parm=%u type=pglst: cb=0\n", iParm));
+                break;
+
+            case VMMDevHGCMParmType_Embedded:
+                if (fIsUser) /// @todo relax this.
+                    return VERR_INVALID_PARAMETER;
+                cb = pSrcParm->u.Embedded.cbData;
+                if (cb)
+                {
+                    uint32_t off = pSrcParm->u.Embedded.offData;
+                    AssertMsgReturn(cb <= VBGLR0_MAX_HGCM_EMBEDDED_BUFFER, ("%#x > %#x\n", cb, VBGLR0_MAX_HGCM_EMBEDDED_BUFFER),
+                                    VERR_INVALID_PARAMETER);
+                    AssertMsgReturn(cb <= cbCallInfo - cParms * sizeof(HGCMFunctionParameter),
+                                    ("cb=%#x cParms=%#x cbCallInfo=%3x\n", cb, cParms, cbCallInfo),
+                                    VERR_INVALID_PARAMETER);
+                    AssertMsgReturn(   off >= cParms * sizeof(HGCMFunctionParameter)
+                                    && off <= cbCallInfo - cb,
+                                    ("offData=%#x cParms=%#x cbCallInfo=%#x\n", off, cParms, cbCallInfo),
+                                    VERR_INVALID_PARAMETER);
+                    AssertMsgReturn(VBOX_HGCM_F_PARM_ARE_VALID(pSrcParm->u.Embedded.fFlags),
+                                    ("%#x\n", pSrcParm->u.Embedded.fFlags), VERR_INVALID_PARAMETER);
+
+                    *pcbExtra += RT_ALIGN_32(cb, 8);
+                }
+                else
+                    Log4(("GstHGCMCall: parm=%u type=embed: cb=0\n", iParm));
+                break;
+
+
+            case VMMDevHGCMParmType_LinAddr_Locked_In:
+            case VMMDevHGCMParmType_LinAddr_Locked_Out:
+            case VMMDevHGCMParmType_LinAddr_Locked:
+                if (fIsUser)
+                    return VERR_INVALID_PARAMETER;
+                if (!VBGLR0_CAN_USE_PHYS_PAGE_LIST(/*a_fLocked =*/ true))
+                {
+                    cb = pSrcParm->u.Pointer.size;
+                    AssertMsgReturn(cb <= VBGLR0_MAX_HGCM_KERNEL_PARM, ("%#x > %#x\n", cb, VBGLR0_MAX_HGCM_KERNEL_PARM),
+                                    VERR_OUT_OF_RANGE);
+                    if (cb != 0)
+                        Log4(("GstHGCMCall: parm=%u type=%#x: cb=%#010x pv=%p\n",
+                              iParm, pSrcParm->type, cb, pSrcParm->u.Pointer.u.linearAddr));
+                    else
+                        Log4(("GstHGCMCall: parm=%u type=%#x: cb=0\n", iParm, pSrcParm->type));
+                    break;
+                }
+                RT_FALL_THRU();
+
+            case VMMDevHGCMParmType_LinAddr_In:
+            case VMMDevHGCMParmType_LinAddr_Out:
+            case VMMDevHGCMParmType_LinAddr:
+                cb = pSrcParm->u.Pointer.size;
+                if (cb != 0)
+                {
+#ifdef USE_BOUNCE_BUFFERS
+                    void       *pvSmallBuf = NULL;
+#endif
+                    uint32_t    iLockBuf   = pParmInfo->cLockBufs;
+                    RTR0MEMOBJ  hObj;
+                    int         rc;
+                    uint32_t    fAccess =    pSrcParm->type == VMMDevHGCMParmType_LinAddr_In
+                                          || pSrcParm->type == VMMDevHGCMParmType_LinAddr_Locked_In
+                                        ? RTMEM_PROT_READ
+                                        : RTMEM_PROT_READ | RTMEM_PROT_WRITE;
+
+                    AssertReturn(iLockBuf < RT_ELEMENTS(pParmInfo->aLockBufs), VERR_INVALID_PARAMETER);
+                    if (!fIsUser)
+                    {
+                        AssertMsgReturn(cb <= VBGLR0_MAX_HGCM_KERNEL_PARM, ("%#x > %#x\n", cb, VBGLR0_MAX_HGCM_KERNEL_PARM),
+                                        VERR_OUT_OF_RANGE);
+                        rc = RTR0MemObjLockKernel(&hObj, (void *)pSrcParm->u.Pointer.u.linearAddr, cb, fAccess);
+                        if (RT_FAILURE(rc))
+                        {
+                            Log(("GstHGCMCall: id=%#x fn=%u parm=%u RTR0MemObjLockKernel(,%p,%#x) -> %Rrc\n",
+                                 pCallInfo->u32ClientID, pCallInfo->u32Function, iParm, pSrcParm->u.Pointer.u.linearAddr, cb, rc));
+                            return rc;
+                        }
+                        Log3(("GstHGCMCall: parm=%u type=%#x: cb=%#010x pv=%p locked kernel -> %p\n",
+                              iParm, pSrcParm->type, cb, pSrcParm->u.Pointer.u.linearAddr, hObj));
+                    }
+                    else if (cb > VBGLR0_MAX_HGCM_USER_PARM)
+                    {
+                        Log(("GstHGCMCall: id=%#x fn=%u parm=%u pv=%p cb=%#x > %#x -> out of range\n",
+                             pCallInfo->u32ClientID, pCallInfo->u32Function, iParm, pSrcParm->u.Pointer.u.linearAddr,
+                             cb, VBGLR0_MAX_HGCM_USER_PARM));
+                        return VERR_OUT_OF_RANGE;
+                    }
+                    else
+                    {
+#ifndef USE_BOUNCE_BUFFERS
+                        rc = RTR0MemObjLockUser(&hObj, (RTR3PTR)pSrcParm->u.Pointer.u.linearAddr, cb, fAccess, NIL_RTR0PROCESS);
+                        if (RT_FAILURE(rc))
+                        {
+                            Log(("GstHGCMCall: id=%#x fn=%u parm=%u RTR0MemObjLockUser(,%p,%#x,nil) -> %Rrc\n",
+                                 pCallInfo->u32ClientID, pCallInfo->u32Function, iParm, pSrcParm->u.Pointer.u.linearAddr, cb, rc));
+                            return rc;
+                        }
+                        Log3(("GstHGCMCall: parm=%u type=%#x: cb=%#010x pv=%p locked user -> %p\n",
+                              iParm, pSrcParm->type, cb, pSrcParm->u.Pointer.u.linearAddr, hObj));
+
+#else  /* USE_BOUNCE_BUFFERS */
+                        /*
+                         * This is a bit massive, but we don't want to waste a
+                         * whole page for a 3 byte string buffer (guest props).
+                         *
+                         * The threshold is ASSUMING sizeof(RTMEMHDR) == 16 and
+                         * the system is using some power of two allocator.
+                         */
+                        /** @todo A more efficient strategy would be to combine buffers. However it
+                         *        is probably going to be more massive than the current code, so
+                         *        it can wait till later. */
+                        bool fCopyIn = pSrcParm->type != VMMDevHGCMParmType_LinAddr_Out
+                                    && pSrcParm->type != VMMDevHGCMParmType_LinAddr_Locked_Out;
+                        if (cb <= PAGE_SIZE / 2 - 16)
+                        {
+                            pvSmallBuf = fCopyIn ? RTMemTmpAlloc(cb) : RTMemTmpAllocZ(cb);
+                            if (RT_UNLIKELY(!pvSmallBuf))
+                                return VERR_NO_MEMORY;
+                            if (fCopyIn)
+                            {
+                                rc = RTR0MemUserCopyFrom(pvSmallBuf, pSrcParm->u.Pointer.u.linearAddr, cb);
+                                if (RT_FAILURE(rc))
+                                {
+                                    RTMemTmpFree(pvSmallBuf);
+                                    Log(("GstHGCMCall: id=%#x fn=%u parm=%u RTR0MemUserCopyFrom(,%p,%#x) -> %Rrc\n",
+                                         pCallInfo->u32ClientID, pCallInfo->u32Function, iParm,
+                                         pSrcParm->u.Pointer.u.linearAddr, cb, rc));
+                                    return rc;
+                                }
+                            }
+                            rc = RTR0MemObjLockKernel(&hObj, pvSmallBuf, cb, fAccess);
+                            if (RT_FAILURE(rc))
+                            {
+                                RTMemTmpFree(pvSmallBuf);
+                                Log(("GstHGCMCall: RTR0MemObjLockKernel failed for small buffer: rc=%Rrc pvSmallBuf=%p cb=%#x\n",
+                                     rc, pvSmallBuf, cb));
+                                return rc;
+                            }
+                            Log3(("GstHGCMCall: parm=%u type=%#x: cb=%#010x pv=%p small buffer %p -> %p\n",
+                                  iParm, pSrcParm->type, cb, pSrcParm->u.Pointer.u.linearAddr, pvSmallBuf, hObj));
+                        }
+                        else
+                        {
+                            rc = RTR0MemObjAllocPage(&hObj, cb, false /*fExecutable*/);
+                            if (RT_FAILURE(rc))
+                                return rc;
+                            if (!fCopyIn)
+                                memset(RTR0MemObjAddress(hObj), '\0', cb);
+                            else
+                            {
+                                rc = RTR0MemUserCopyFrom(RTR0MemObjAddress(hObj), pSrcParm->u.Pointer.u.linearAddr, cb);
+                                if (RT_FAILURE(rc))
+                                {
+                                    RTR0MemObjFree(hObj, false /*fFreeMappings*/);
+                                    Log(("GstHGCMCall: id=%#x fn=%u parm=%u RTR0MemUserCopyFrom(,%p,%#x) -> %Rrc\n",
+                                         pCallInfo->u32ClientID, pCallInfo->u32Function, iParm,
+                                         pSrcParm->u.Pointer.u.linearAddr, cb, rc));
+                                    return rc;
+                                }
+                            }
+                            Log3(("GstHGCMCall: parm=%u type=%#x: cb=%#010x pv=%p big buffer -> %p\n",
+                                  iParm, pSrcParm->type, cb, pSrcParm->u.Pointer.u.linearAddr, hObj));
+                        }
+#endif /* USE_BOUNCE_BUFFERS */
+                    }
+
+                    pParmInfo->aLockBufs[iLockBuf].iParm      = iParm;
+                    pParmInfo->aLockBufs[iLockBuf].hObj       = hObj;
+#ifdef USE_BOUNCE_BUFFERS
+                    pParmInfo->aLockBufs[iLockBuf].pvSmallBuf = pvSmallBuf;
+#endif
+                    pParmInfo->cLockBufs = iLockBuf + 1;
+
+                    if (VBGLR0_CAN_USE_PHYS_PAGE_LIST(/*a_fLocked =*/ false))
+                    {
+                        size_t const cPages = RTR0MemObjSize(hObj) >> PAGE_SHIFT;
+                        *pcbExtra += RT_UOFFSETOF_DYN(HGCMPageListInfo, aPages[cPages]);
+                    }
+                }
+                else
+                    Log4(("GstHGCMCall: parm=%u type=%#x: cb=0\n", iParm, pSrcParm->type));
+                break;
+
+            default:
+                return VERR_INVALID_PARAMETER;
+        }
+    }
+
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Translates locked linear address to the normal type.
+ * The locked types are only for the guest side and not handled by the host.
+ *
+ * @returns normal linear address type.
+ * @param   enmType     The type.
+ */
+static HGCMFunctionParameterType vbglR0HGCMInternalConvertLinAddrType(HGCMFunctionParameterType enmType)
+{
+    switch (enmType)
+    {
+        case VMMDevHGCMParmType_LinAddr_Locked_In:
+            return VMMDevHGCMParmType_LinAddr_In;
+        case VMMDevHGCMParmType_LinAddr_Locked_Out:
+            return VMMDevHGCMParmType_LinAddr_Out;
+        case VMMDevHGCMParmType_LinAddr_Locked:
+            return VMMDevHGCMParmType_LinAddr;
+        default:
+            return enmType;
+    }
+}
+
+
+/**
+ * Translates linear address types to page list direction flags.
+ *
+ * @returns page list flags.
+ * @param   enmType     The type.
+ */
+static uint32_t vbglR0HGCMInternalLinAddrTypeToPageListFlags(HGCMFunctionParameterType enmType)
+{
+    switch (enmType)
+    {
+        case VMMDevHGCMParmType_LinAddr_In:
+        case VMMDevHGCMParmType_LinAddr_Locked_In:
+            return VBOX_HGCM_F_PARM_DIRECTION_TO_HOST;
+
+        case VMMDevHGCMParmType_LinAddr_Out:
+        case VMMDevHGCMParmType_LinAddr_Locked_Out:
+            return VBOX_HGCM_F_PARM_DIRECTION_FROM_HOST;
+
+        default: AssertFailed(); RT_FALL_THRU();
+        case VMMDevHGCMParmType_LinAddr:
+        case VMMDevHGCMParmType_LinAddr_Locked:
+            return VBOX_HGCM_F_PARM_DIRECTION_BOTH;
+    }
+}
+
+
+/**
+ * Initializes the call request that we're sending to the host.
+ *
+ * @returns VBox status code.
+ *
+ * @param   pCallInfo       The call info.
+ * @param   cbCallInfo      The size of the call info structure.
+ * @param   fRequestor      VMMDEV_REQUESTOR_XXX.
+ * @param   fIsUser         Is it a user request or kernel request.
+ * @param   pcbExtra        Where to return the extra request space needed for
+ *                          physical page lists.
+ */
+static void vbglR0HGCMInternalInitCall(VMMDevHGCMCall *pHGCMCall, PCVBGLIOCHGCMCALL pCallInfo,
+                                       uint32_t cbCallInfo, uint32_t fRequestor, bool fIsUser, struct VbglR0ParmInfo *pParmInfo)
+{
+    HGCMFunctionParameter const *pSrcParm = VBGL_HGCM_GET_CALL_PARMS(pCallInfo);
+    HGCMFunctionParameter       *pDstParm = VMMDEV_HGCM_CALL_PARMS(pHGCMCall);
+    uint32_t const               cParms   = pCallInfo->cParms;
+    uint32_t    offExtra = (uint32_t)((uintptr_t)(pDstParm + cParms) - (uintptr_t)pHGCMCall);
+    uint32_t    iLockBuf = 0;
+    uint32_t    iParm;
+    RT_NOREF1(cbCallInfo);
+#ifndef USE_BOUNCE_BUFFERS
+    RT_NOREF1(fIsUser);
+#endif
+
+    /*
+     * The call request headers.
+     */
+    pHGCMCall->header.header.fRequestor = !fIsUser || (fRequestor & VMMDEV_REQUESTOR_USERMODE) ? fRequestor
+                                        :   VMMDEV_REQUESTOR_USERMODE        | VMMDEV_REQUESTOR_USR_NOT_GIVEN
+                                          | VMMDEV_REQUESTOR_TRUST_NOT_GIVEN | VMMDEV_REQUESTOR_CON_DONT_KNOW;
+
+    pHGCMCall->header.fu32Flags = 0;
+    pHGCMCall->header.result    = VINF_SUCCESS;
+
+    pHGCMCall->u32ClientID = pCallInfo->u32ClientID;
+    pHGCMCall->u32Function = pCallInfo->u32Function;
+    pHGCMCall->cParms      = cParms;
+
+    /*
+     * The parameters.
+     */
+    for (iParm = 0; iParm < cParms; iParm++, pSrcParm++, pDstParm++)
+    {
+        switch (pSrcParm->type)
+        {
+            case VMMDevHGCMParmType_32bit:
+            case VMMDevHGCMParmType_64bit:
+                *pDstParm = *pSrcParm;
+                break;
+
+            case VMMDevHGCMParmType_PageList:
+            case VMMDevHGCMParmType_ContiguousPageList:
+                pDstParm->type = pSrcParm->type;
+                pDstParm->u.PageList.size = pSrcParm->u.PageList.size;
+                if (pSrcParm->u.PageList.size)
+                {
+                    HGCMPageListInfo const *pSrcPgLst = (HGCMPageListInfo *)((uint8_t *)pCallInfo + pSrcParm->u.PageList.offset);
+                    HGCMPageListInfo       *pDstPgLst = (HGCMPageListInfo *)((uint8_t *)pHGCMCall + offExtra);
+                    uint32_t const          cPages    = pSrcPgLst->cPages;
+                    uint32_t                iPage;
+
+                    pDstParm->u.PageList.offset = offExtra;
+                    pDstPgLst->flags            = pSrcPgLst->flags;
+                    pDstPgLst->offFirstPage     = pSrcPgLst->offFirstPage;
+                    pDstPgLst->cPages           = (uint16_t)cPages;
+                    for (iPage = 0; iPage < cPages; iPage++)
+                        pDstPgLst->aPages[iPage] = pSrcPgLst->aPages[iPage];
+
+                    offExtra += RT_UOFFSETOF_DYN(HGCMPageListInfo, aPages[cPages]);
+                }
+                else
+                    pDstParm->u.PageList.offset = 0; /** @todo will fail on the host side now */
+                break;
+
+            case VMMDevHGCMParmType_Embedded:
+            {
+                uint32_t const cb = pSrcParm->u.Embedded.cbData;
+                pDstParm->type = VMMDevHGCMParmType_Embedded;
+                pDstParm->u.Embedded.cbData  = cb;
+                pDstParm->u.Embedded.offData = offExtra;
+                if (cb > 0)
+                {
+                    uint8_t *pbDst = (uint8_t *)pHGCMCall + offExtra;
+                    if (pSrcParm->u.Embedded.fFlags & VBOX_HGCM_F_PARM_DIRECTION_TO_HOST)
+                    {
+                        memcpy(pbDst, (uint8_t const *)pCallInfo + pSrcParm->u.Embedded.offData, cb);
+                        if (RT_ALIGN(cb, 8) != cb)
+                            memset(pbDst + cb, 0, RT_ALIGN(cb, 8) - cb);
+                    }
+                    else
+                        RT_BZERO(pbDst, RT_ALIGN(cb, 8));
+                    offExtra += RT_ALIGN(cb, 8);
+                }
+                break;
+            }
+
+            case VMMDevHGCMParmType_LinAddr_Locked_In:
+            case VMMDevHGCMParmType_LinAddr_Locked_Out:
+            case VMMDevHGCMParmType_LinAddr_Locked:
+                if (!VBGLR0_CAN_USE_PHYS_PAGE_LIST(/*a_fLocked =*/ true))
+                {
+                    *pDstParm = *pSrcParm;
+                    pDstParm->type = vbglR0HGCMInternalConvertLinAddrType(pSrcParm->type);
+                    break;
+                }
+                RT_FALL_THRU();
+
+            case VMMDevHGCMParmType_LinAddr_In:
+            case VMMDevHGCMParmType_LinAddr_Out:
+            case VMMDevHGCMParmType_LinAddr:
+                if (pSrcParm->u.Pointer.size != 0)
+                {
+#ifdef USE_BOUNCE_BUFFERS
+                    void      *pvSmallBuf = pParmInfo->aLockBufs[iLockBuf].pvSmallBuf;
+#endif
+                    RTR0MEMOBJ hObj       = pParmInfo->aLockBufs[iLockBuf].hObj;
+                    Assert(iParm == pParmInfo->aLockBufs[iLockBuf].iParm);
+
+                    if (VBGLR0_CAN_USE_PHYS_PAGE_LIST(/*a_fLocked =*/ false))
+                    {
+                        HGCMPageListInfo   *pDstPgLst = (HGCMPageListInfo *)((uint8_t *)pHGCMCall + offExtra);
+                        size_t const        cPages    = RTR0MemObjSize(hObj) >> PAGE_SHIFT;
+                        size_t              iPage;
+
+                        pDstParm->type = VMMDevHGCMParmType_PageList;
+                        pDstParm->u.PageList.size   = pSrcParm->u.Pointer.size;
+                        pDstParm->u.PageList.offset = offExtra;
+                        pDstPgLst->flags            = vbglR0HGCMInternalLinAddrTypeToPageListFlags(pSrcParm->type);
+#ifdef USE_BOUNCE_BUFFERS
+                        if (fIsUser)
+                            pDstPgLst->offFirstPage = (uintptr_t)pvSmallBuf & PAGE_OFFSET_MASK;
+                        else
+#endif
+                            pDstPgLst->offFirstPage = (uint16_t)(pSrcParm->u.Pointer.u.linearAddr & PAGE_OFFSET_MASK);
+                        pDstPgLst->cPages           = (uint16_t)cPages; Assert(pDstPgLst->cPages == cPages);
+                        for (iPage = 0; iPage < cPages; iPage++)
+                        {
+                            pDstPgLst->aPages[iPage] = RTR0MemObjGetPagePhysAddr(hObj, iPage);
+                            Assert(pDstPgLst->aPages[iPage] != NIL_RTHCPHYS);
+                        }
+
+                        offExtra += RT_UOFFSETOF_DYN(HGCMPageListInfo, aPages[cPages]);
+                    }
+                    else
+                    {
+                        pDstParm->type = vbglR0HGCMInternalConvertLinAddrType(pSrcParm->type);
+                        pDstParm->u.Pointer.size = pSrcParm->u.Pointer.size;
+#ifdef USE_BOUNCE_BUFFERS
+                        if (fIsUser)
+                            pDstParm->u.Pointer.u.linearAddr = pvSmallBuf
+                                                             ? (uintptr_t)pvSmallBuf
+                                                             : (uintptr_t)RTR0MemObjAddress(hObj);
+                        else
+#endif
+                            pDstParm->u.Pointer.u.linearAddr = pSrcParm->u.Pointer.u.linearAddr;
+                    }
+                    iLockBuf++;
+                }
+                else
+                {
+                    pDstParm->type = vbglR0HGCMInternalConvertLinAddrType(pSrcParm->type);
+                    pDstParm->u.Pointer.size = 0;
+                    pDstParm->u.Pointer.u.linearAddr = 0;
+                }
+                break;
+
+            default:
+                AssertFailed();
+                pDstParm->type = VMMDevHGCMParmType_Invalid;
+                break;
+        }
+    }
+}
+
+
+/**
+ * Performs the call and completion wait.
+ *
+ * @returns VBox status code of this operation, not necessarily the call.
+ *
+ * @param   pHGCMCall           The HGCM call info.
+ * @param   pfnAsyncCallback    The async callback that will wait for the call
+ *                              to complete.
+ * @param   pvAsyncData         Argument for the callback.
+ * @param   u32AsyncData        Argument for the callback.
+ * @param   pfLeakIt            Where to return the leak it / free it,
+ *                              indicator. Cancellation fun.
+ */
+static int vbglR0HGCMInternalDoCall(VMMDevHGCMCall *pHGCMCall, PFNVBGLHGCMCALLBACK pfnAsyncCallback,
+                                    void *pvAsyncData, uint32_t u32AsyncData, bool *pfLeakIt)
+{
+    int rc;
+
+    Log(("calling VbglR0GRPerform\n"));
+    rc = VbglR0GRPerform(&pHGCMCall->header.header);
+    Log(("VbglR0GRPerform rc = %Rrc (header rc=%d)\n", rc, pHGCMCall->header.result));
+
+    /*
+     * If the call failed, but as a result of the request itself, then pretend
+     * success. Upper layers will interpret the result code in the packet.
+     */
+    if (    RT_FAILURE(rc)
+        &&  rc == pHGCMCall->header.result)
+    {
+        Assert(pHGCMCall->header.fu32Flags & VBOX_HGCM_REQ_DONE);
+        rc = VINF_SUCCESS;
+    }
+
+    /*
+     * Check if host decides to process the request asynchronously,
+     * if so, we wait for it to complete using the caller supplied callback.
+     */
+    *pfLeakIt = false;
+    if (rc == VINF_HGCM_ASYNC_EXECUTE)
+    {
+        Log(("Processing HGCM call asynchronously\n"));
+        rc = pfnAsyncCallback(&pHGCMCall->header, pvAsyncData, u32AsyncData);
+        if (pHGCMCall->header.fu32Flags & VBOX_HGCM_REQ_DONE)
+        {
+            Assert(!(pHGCMCall->header.fu32Flags & VBOX_HGCM_REQ_CANCELLED));
+            rc = VINF_SUCCESS;
+        }
+        else
+        {
+            /*
+             * The request didn't complete in time or the call was interrupted,
+             * the RC from the callback indicates which. Try cancel the request.
+             *
+             * This is a bit messy because we're racing request completion. Sorry.
+             */
+            /** @todo It would be nice if we could use the waiter callback to do further
+             *  waiting in case of a completion race. If it wasn't for WINNT having its own
+             *  version of all that stuff, I would've done it already. */
+            VMMDevHGCMCancel2 *pCancelReq;
+            int rc2 = VbglR0GRAlloc((VMMDevRequestHeader **)&pCancelReq, sizeof(*pCancelReq), VMMDevReq_HGCMCancel2);
+            if (RT_SUCCESS(rc2))
+            {
+                pCancelReq->physReqToCancel = VbglR0PhysHeapGetPhysAddr(pHGCMCall);
+                rc2 = VbglR0GRPerform(&pCancelReq->header);
+                VbglR0GRFree(&pCancelReq->header);
+            }
+#if 1 /** @todo ADDVER: Remove this on next minor version change. */
+            if (rc2 == VERR_NOT_IMPLEMENTED)
+            {
+                /* host is too old, or we're out of heap. */
+                pHGCMCall->header.fu32Flags |= VBOX_HGCM_REQ_CANCELLED;
+                pHGCMCall->header.header.requestType = VMMDevReq_HGCMCancel;
+                rc2 = VbglR0GRPerform(&pHGCMCall->header.header);
+                if (rc2 == VERR_INVALID_PARAMETER)
+                    rc2 = VERR_NOT_FOUND;
+                else if (RT_SUCCESS(rc))
+                    RTThreadSleep(1);
+            }
+#endif
+            if (RT_SUCCESS(rc)) rc = VERR_INTERRUPTED; /** @todo weed this out from the WINNT VBoxGuest code. */
+            if (RT_SUCCESS(rc2))
+            {
+                Log(("vbglR0HGCMInternalDoCall: successfully cancelled\n"));
+                pHGCMCall->header.fu32Flags |= VBOX_HGCM_REQ_CANCELLED;
+            }
+            else
+            {
+                /*
+                 * Wait for a bit while the host (hopefully) completes it.
+                 */
+                uint64_t u64Start       = RTTimeSystemMilliTS();
+                uint32_t cMilliesToWait = rc2 == VERR_NOT_FOUND || rc2 == VERR_SEM_DESTROYED ? 500 : 2000;
+                uint64_t cElapsed       = 0;
+                if (rc2 != VERR_NOT_FOUND)
+                {
+                    static unsigned s_cErrors = 0;
+                    if (s_cErrors++ < 32)
+                        LogRel(("vbglR0HGCMInternalDoCall: Failed to cancel the HGCM call on %Rrc: rc2=%Rrc\n", rc, rc2));
+                }
+                else
+                    Log(("vbglR0HGCMInternalDoCall: Cancel race rc=%Rrc rc2=%Rrc\n", rc, rc2));
+
+                do
+                {
+                    ASMCompilerBarrier();       /* paranoia */
+                    if (pHGCMCall->header.fu32Flags & VBOX_HGCM_REQ_DONE)
+                        break;
+                    RTThreadSleep(1);
+                    cElapsed = RTTimeSystemMilliTS() - u64Start;
+                } while (cElapsed < cMilliesToWait);
+
+                ASMCompilerBarrier();           /* paranoia^2 */
+                if (pHGCMCall->header.fu32Flags & VBOX_HGCM_REQ_DONE)
+                    rc = VINF_SUCCESS;
+                else
+                {
+                    LogRel(("vbglR0HGCMInternalDoCall: Leaking %u bytes. Pending call to %u with %u parms. (rc2=%Rrc)\n",
+                            pHGCMCall->header.header.size, pHGCMCall->u32Function, pHGCMCall->cParms, rc2));
+                    *pfLeakIt = true;
+                }
+                Log(("vbglR0HGCMInternalDoCall: Cancel race ended with rc=%Rrc (rc2=%Rrc) after %llu ms\n", rc, rc2, cElapsed));
+            }
+        }
+    }
+
+    Log(("GstHGCMCall: rc=%Rrc result=%Rrc fu32Flags=%#x fLeakIt=%d\n",
+         rc, pHGCMCall->header.result, pHGCMCall->header.fu32Flags, *pfLeakIt));
+    return rc;
+}
+
+
+/**
+ * Copies the result of the call back to the caller info structure and user
+ * buffers (if using bounce buffers).
+ *
+ * @returns rc, unless RTR0MemUserCopyTo fails.
+ * @param   pCallInfo           Call info structure to update.
+ * @param   cbCallInfo          The size of the client request.
+ * @param   pHGCMCall           HGCM call request.
+ * @param   cbHGCMCall          The size of the HGCM call request.
+ * @param   pParmInfo           Parameter locking/buffering info.
+ * @param   fIsUser             Is it a user (true) or kernel request.
+ * @param   rc                  The current result code. Passed along to
+ *                              preserve informational status codes.
+ */
+static int vbglR0HGCMInternalCopyBackResult(PVBGLIOCHGCMCALL pCallInfo, uint32_t cbCallInfo,
+                                            VMMDevHGCMCall const *pHGCMCall, uint32_t cbHGCMCall,
+                                            struct VbglR0ParmInfo *pParmInfo, bool fIsUser, int rc)
+{
+    HGCMFunctionParameter const *pSrcParm = VMMDEV_HGCM_CALL_PARMS(pHGCMCall);
+    HGCMFunctionParameter       *pDstParm = VBGL_HGCM_GET_CALL_PARMS(pCallInfo);
+    uint32_t const               cParms   = pCallInfo->cParms;
+#ifdef USE_BOUNCE_BUFFERS
+    uint32_t    iLockBuf = 0;
+#endif
+    uint32_t    iParm;
+    RT_NOREF1(pParmInfo);
+#ifndef USE_BOUNCE_BUFFERS
+    RT_NOREF1(fIsUser);
+#endif
+
+    /*
+     * The call result.
+     */
+    pCallInfo->Hdr.rc = pHGCMCall->header.result;
+
+    /*
+     * Copy back parameters.
+     */
+    /** @todo This is assuming user data (pDstParm) is buffered.  Not true
+     *        on OS/2, though I'm not sure we care... */
+    for (iParm = 0; iParm < cParms; iParm++, pSrcParm++, pDstParm++)
+    {
+        switch (pDstParm->type)
+        {
+            case VMMDevHGCMParmType_32bit:
+            case VMMDevHGCMParmType_64bit:
+                *pDstParm = *pSrcParm;
+                break;
+
+            case VMMDevHGCMParmType_PageList:
+            case VMMDevHGCMParmType_ContiguousPageList:
+                pDstParm->u.PageList.size = pSrcParm->u.PageList.size;
+                break;
+
+            case VMMDevHGCMParmType_Embedded:
+            {
+                uint32_t const cbDst = pDstParm->u.Embedded.cbData;
+                uint32_t       cbSrc;
+                pDstParm->u.Embedded.cbData = cbSrc = pSrcParm->u.Embedded.cbData;
+                if (    cbSrc > 0
+                    && (pDstParm->u.Embedded.fFlags & VBOX_HGCM_F_PARM_DIRECTION_FROM_HOST))
+                {
+                    uint32_t const offDst = pDstParm->u.Embedded.offData;
+                    uint32_t const offSrc = pSrcParm->u.Embedded.offData;
+
+                    AssertReturn(offDst < cbCallInfo, VERR_INTERNAL_ERROR_2);
+                    AssertReturn(offDst >= sizeof(*pCallInfo) + cParms * sizeof(*pDstParm), VERR_INTERNAL_ERROR_2);
+                    AssertReturn(cbDst  <= cbCallInfo - offDst , VERR_INTERNAL_ERROR_2);
+
+                    AssertReturn(offSrc < cbCallInfo, VERR_INTERNAL_ERROR_2);
+                    AssertReturn(offSrc >= sizeof(*pHGCMCall) + cParms * sizeof(*pSrcParm), VERR_INTERNAL_ERROR_2);
+                    if (cbSrc <= cbHGCMCall - offSrc)
+                    { /* likely */ }
+                    else
+                    {
+                        /* Special case: Buffer overflow w/ correct size given. */
+                        AssertReturn(RT_FAILURE_NP(rc), VERR_INTERNAL_ERROR_2);
+                        cbSrc = cbHGCMCall - offSrc;
+                    }
+                    memcpy((uint8_t *)pCallInfo + offDst, (uint8_t const *)pHGCMCall + offSrc, RT_MIN(cbSrc, cbDst));
+                }
+                break;
+            }
+
+            case VMMDevHGCMParmType_LinAddr_Locked_In:
+            case VMMDevHGCMParmType_LinAddr_In:
+#ifdef USE_BOUNCE_BUFFERS
+                if (    fIsUser
+                    &&  iLockBuf < pParmInfo->cLockBufs
+                    &&  iParm   == pParmInfo->aLockBufs[iLockBuf].iParm)
+                    iLockBuf++;
+#endif
+                pDstParm->u.Pointer.size = pSrcParm->u.Pointer.size;
+                break;
+
+            case VMMDevHGCMParmType_LinAddr_Locked_Out:
+            case VMMDevHGCMParmType_LinAddr_Locked:
+                if (!VBGLR0_CAN_USE_PHYS_PAGE_LIST(/*a_fLocked =*/ true))
+                {
+                    pDstParm->u.Pointer.size = pSrcParm->u.Pointer.size;
+                    break;
+                }
+                RT_FALL_THRU();
+
+            case VMMDevHGCMParmType_LinAddr_Out:
+            case VMMDevHGCMParmType_LinAddr:
+            {
+#ifdef USE_BOUNCE_BUFFERS
+                if (fIsUser)
+                {
+                    size_t cbOut = RT_MIN(pSrcParm->u.Pointer.size, pDstParm->u.Pointer.size);
+                    if (cbOut)
+                    {
+                        int rc2;
+                        Assert(pParmInfo->aLockBufs[iLockBuf].iParm == iParm);
+                        rc2 = RTR0MemUserCopyTo((RTR3PTR)pDstParm->u.Pointer.u.linearAddr,
+                                                pParmInfo->aLockBufs[iLockBuf].pvSmallBuf
+                                                ? pParmInfo->aLockBufs[iLockBuf].pvSmallBuf
+                                                : RTR0MemObjAddress(pParmInfo->aLockBufs[iLockBuf].hObj),
+                                                cbOut);
+                        if (RT_FAILURE(rc2))
+                            return rc2;
+                        iLockBuf++;
+                    }
+                    else if (   iLockBuf < pParmInfo->cLockBufs
+                             && iParm   == pParmInfo->aLockBufs[iLockBuf].iParm)
+                        iLockBuf++;
+                }
+#endif
+                pDstParm->u.Pointer.size = pSrcParm->u.Pointer.size;
+                break;
+            }
+
+            default:
+                AssertFailed();
+                rc = VERR_INTERNAL_ERROR_4;
+                break;
+        }
+    }
+
+#ifdef USE_BOUNCE_BUFFERS
+    Assert(!fIsUser || pParmInfo->cLockBufs == iLockBuf);
+#endif
+    return rc;
+}
+
+
+DECLR0VBGL(int) VbglR0HGCMInternalCall(PVBGLIOCHGCMCALL pCallInfo, uint32_t cbCallInfo, uint32_t fFlags, uint32_t fRequestor,
+                                       PFNVBGLHGCMCALLBACK pfnAsyncCallback, void *pvAsyncData, uint32_t u32AsyncData)
+{
+    bool                    fIsUser = (fFlags & VBGLR0_HGCMCALL_F_MODE_MASK) == VBGLR0_HGCMCALL_F_USER;
+    struct VbglR0ParmInfo   ParmInfo;
+    size_t                  cbExtra;
+    int                     rc;
+
+    /*
+     * Basic validation.
+     */
+    AssertMsgReturn(   !pCallInfo
+                    || !pfnAsyncCallback
+                    || pCallInfo->cParms > VBOX_HGCM_MAX_PARMS
+                    || !(fFlags & ~VBGLR0_HGCMCALL_F_MODE_MASK),
+                    ("pCallInfo=%p pfnAsyncCallback=%p fFlags=%#x\n", pCallInfo, pfnAsyncCallback, fFlags),
+                    VERR_INVALID_PARAMETER);
+    AssertReturn(   cbCallInfo >= sizeof(VBGLIOCHGCMCALL)
+                 || cbCallInfo >= pCallInfo->cParms * sizeof(HGCMFunctionParameter),
+                 VERR_INVALID_PARAMETER);
+
+    Log(("GstHGCMCall: u32ClientID=%#x u32Function=%u cParms=%u cbCallInfo=%#x fFlags=%#x\n",
+         pCallInfo->u32ClientID, pCallInfo->u32ClientID, pCallInfo->u32Function, pCallInfo->cParms, cbCallInfo, fFlags));
+
+    /*
+     * Validate, lock and buffer the parameters for the call.
+     * This will calculate the amount of extra space for physical page list.
+     */
+    rc = vbglR0HGCMInternalPreprocessCall(pCallInfo, cbCallInfo, fIsUser, &ParmInfo, &cbExtra);
+    if (RT_SUCCESS(rc))
+    {
+        /*
+         * Allocate the request buffer and recreate the call request.
+         */
+        VMMDevHGCMCall *pHGCMCall;
+        uint32_t const  cbHGCMCall = sizeof(VMMDevHGCMCall) + pCallInfo->cParms * sizeof(HGCMFunctionParameter) + (uint32_t)cbExtra;
+        rc = VbglR0GRAlloc((VMMDevRequestHeader **)&pHGCMCall, cbHGCMCall, VMMDevReq_HGCMCall);
+        if (RT_SUCCESS(rc))
+        {
+            bool fLeakIt;
+            vbglR0HGCMInternalInitCall(pHGCMCall, pCallInfo, cbCallInfo, fRequestor, fIsUser, &ParmInfo);
+
+            /*
+             * Perform the call.
+             */
+            rc = vbglR0HGCMInternalDoCall(pHGCMCall, pfnAsyncCallback, pvAsyncData, u32AsyncData, &fLeakIt);
+            if (RT_SUCCESS(rc))
+            {
+                /*
+                 * Copy back the result (parameters and buffers that changed).
+                 */
+                rc = vbglR0HGCMInternalCopyBackResult(pCallInfo, cbCallInfo, pHGCMCall, cbHGCMCall, &ParmInfo, fIsUser, rc);
+            }
+            else
+            {
+                if (   rc != VERR_INTERRUPTED
+                    && rc != VERR_TIMEOUT)
+                {
+                    static unsigned s_cErrors = 0;
+                    if (s_cErrors++ < 32)
+                        LogRel(("VbglR0HGCMInternalCall: vbglR0HGCMInternalDoCall failed. rc=%Rrc\n", rc));
+                }
+            }
+
+            if (!fLeakIt)
+                VbglR0GRFree(&pHGCMCall->header.header);
+        }
+    }
+    else
+        LogRel(("VbglR0HGCMInternalCall: vbglR0HGCMInternalPreprocessCall failed. rc=%Rrc\n", rc));
+
+    /*
+     * Release locks and free bounce buffers.
+     */
+    if (ParmInfo.cLockBufs)
+        while (ParmInfo.cLockBufs-- > 0)
+        {
+            RTR0MemObjFree(ParmInfo.aLockBufs[ParmInfo.cLockBufs].hObj, false /*fFreeMappings*/);
+#ifdef USE_BOUNCE_BUFFERS
+            RTMemTmpFree(ParmInfo.aLockBufs[ParmInfo.cLockBufs].pvSmallBuf);
+#endif
+        }
+
+    return rc;
+}
+
+
+#if ARCH_BITS == 64
+DECLR0VBGL(int) VbglR0HGCMInternalCall32(PVBGLIOCHGCMCALL pCallInfo, uint32_t cbCallInfo, uint32_t fFlags, uint32_t fRequestor,
+                                         PFNVBGLHGCMCALLBACK pfnAsyncCallback, void *pvAsyncData, uint32_t u32AsyncData)
+{
+    PVBGLIOCHGCMCALL         pCallInfo64 = NULL;
+    HGCMFunctionParameter   *pParm64 = NULL;
+    HGCMFunctionParameter32 *pParm32 = NULL;
+    uint32_t                 cParms = 0;
+    uint32_t                 iParm = 0;
+    int                      rc = VINF_SUCCESS;
+
+    /*
+     * Input validation.
+     */
+    AssertMsgReturn(    !pCallInfo
+                    ||  !pfnAsyncCallback
+                    ||  pCallInfo->cParms > VBOX_HGCM_MAX_PARMS
+                    || !(fFlags & ~VBGLR0_HGCMCALL_F_MODE_MASK),
+                    ("pCallInfo=%p pfnAsyncCallback=%p fFlags=%#x\n", pCallInfo, pfnAsyncCallback, fFlags),
+                    VERR_INVALID_PARAMETER);
+    AssertReturn(   cbCallInfo >= sizeof(VBGLIOCHGCMCALL)
+                 || cbCallInfo >= pCallInfo->cParms * sizeof(HGCMFunctionParameter32),
+                 VERR_INVALID_PARAMETER);
+
+    /* This Assert does not work on Solaris/Windows 64/32 mixed mode, not sure why, skipping for now */
+#if !defined(RT_OS_SOLARIS) && !defined(RT_OS_WINDOWS)
+    AssertReturn((fFlags & VBGLR0_HGCMCALL_F_MODE_MASK) == VBGLR0_HGCMCALL_F_KERNEL, VERR_WRONG_ORDER);
+#endif
+
+    cParms = pCallInfo->cParms;
+    Log(("VbglR0HGCMInternalCall32: cParms=%d, u32Function=%d, fFlags=%#x\n", cParms, pCallInfo->u32Function, fFlags));
+
+    /*
+     * The simple approach, allocate a temporary request and convert the parameters.
+     */
+    pCallInfo64 = (PVBGLIOCHGCMCALL)RTMemTmpAllocZ(sizeof(*pCallInfo64) + cParms * sizeof(HGCMFunctionParameter));
+    if (!pCallInfo64)
+        return VERR_NO_TMP_MEMORY;
+
+    *pCallInfo64 = *pCallInfo;
+    pParm32 = VBGL_HGCM_GET_CALL_PARMS32(pCallInfo);
+    pParm64 = VBGL_HGCM_GET_CALL_PARMS(pCallInfo64);
+    for (iParm = 0; iParm < cParms; iParm++, pParm32++, pParm64++)
+    {
+        switch (pParm32->type)
+        {
+            case VMMDevHGCMParmType_32bit:
+                pParm64->type      = VMMDevHGCMParmType_32bit;
+                pParm64->u.value32 = pParm32->u.value32;
+                break;
+
+            case VMMDevHGCMParmType_64bit:
+                pParm64->type      = VMMDevHGCMParmType_64bit;
+                pParm64->u.value64 = pParm32->u.value64;
+                break;
+
+            case VMMDevHGCMParmType_LinAddr_Out:
+            case VMMDevHGCMParmType_LinAddr:
+            case VMMDevHGCMParmType_LinAddr_In:
+                pParm64->type                   = pParm32->type;
+                pParm64->u.Pointer.size         = pParm32->u.Pointer.size;
+                pParm64->u.Pointer.u.linearAddr = pParm32->u.Pointer.u.linearAddr;
+                break;
+
+            default:
+                rc = VERR_INVALID_PARAMETER;
+                LogRel(("VbglR0HGCMInternalCall32: pParm32 type %#x invalid.\n", pParm32->type));
+                break;
+        }
+        if (RT_FAILURE(rc))
+            break;
+    }
+    if (RT_SUCCESS(rc))
+    {
+        rc = VbglR0HGCMInternalCall(pCallInfo64, sizeof(*pCallInfo64) + cParms * sizeof(HGCMFunctionParameter), fFlags,
+                                    fRequestor, pfnAsyncCallback, pvAsyncData, u32AsyncData);
+
+        if (RT_SUCCESS(rc))
+        {
+            *pCallInfo = *pCallInfo64;
+
+            /*
+             * Copy back.
+             */
+            pParm32 = VBGL_HGCM_GET_CALL_PARMS32(pCallInfo);
+            pParm64 = VBGL_HGCM_GET_CALL_PARMS(pCallInfo64);
+            for (iParm = 0; iParm < cParms; iParm++, pParm32++, pParm64++)
+            {
+                switch (pParm64->type)
+                {
+                    case VMMDevHGCMParmType_32bit:
+                        pParm32->u.value32 = pParm64->u.value32;
+                        break;
+
+                    case VMMDevHGCMParmType_64bit:
+                        pParm32->u.value64 = pParm64->u.value64;
+                        break;
+
+                    case VMMDevHGCMParmType_LinAddr_Out:
+                    case VMMDevHGCMParmType_LinAddr:
+                    case VMMDevHGCMParmType_LinAddr_In:
+                        pParm32->u.Pointer.size = pParm64->u.Pointer.size;
+                        break;
+
+                    default:
+                        LogRel(("VbglR0HGCMInternalCall32: failed invalid pParm32 type %d\n", pParm32->type));
+                        rc = VERR_INTERNAL_ERROR_3;
+                        break;
+                }
+            }
+        }
+        else
+        {
+            static unsigned s_cErrors = 0;
+            if (s_cErrors++ < 32)
+                LogRel(("VbglR0HGCMInternalCall32: VbglR0HGCMInternalCall failed. rc=%Rrc\n", rc));
+        }
+    }
+    else
+    {
+        static unsigned s_cErrors = 0;
+        if (s_cErrors++ < 32)
+            LogRel(("VbglR0HGCMInternalCall32: failed. rc=%Rrc\n", rc));
+    }
+
+    RTMemTmpFree(pCallInfo64);
+    return rc;
+}
+#endif /* ARCH_BITS == 64 */
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibIdc-os2.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibIdc-os2.cpp
new file mode 100644
index 00000000..828dea2e
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibIdc-os2.cpp
@@ -0,0 +1,85 @@
+/* $Id: VBoxGuestR0LibIdc-os2.cpp $ */
+/** @file
+ * VBoxGuestLib - Ring-0 Support Library for VBoxGuest, IDC, OS/2 specific.
+ */
+
+/*
+ * Copyright (C) 2008-2023 Oracle and/or its affiliates.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "VBoxGuestR0LibInternal.h"
+#include <VBox/err.h>
+#include <VBox/log.h>
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+RT_C_DECLS_BEGIN /* for watcom */
+/* This is defined in some assembly file.  The AttachDD operation
+   is done in the driver init code. */
+extern VBGLOS2ATTACHDD g_VBoxGuestIDC;
+RT_C_DECLS_END
+
+
+
+int VBOXCALL vbglR0IdcNativeOpen(PVBGLIDCHANDLE pHandle, PVBGLIOCIDCCONNECT pReq)
+{
+    /*
+     * Just check whether the connection was made or not.
+     */
+    if (   g_VBoxGuestIDC.u32Version == VBGL_IOC_VERSION
+        && RT_VALID_PTR(g_VBoxGuestIDC.u32Session)
+        && RT_VALID_PTR(g_VBoxGuestIDC.pfnServiceEP))
+        return g_VBoxGuestIDC.pfnServiceEP(g_VBoxGuestIDC.u32Session, VBGL_IOCTL_IDC_CONNECT, &pReq->Hdr, sizeof(*pReq));
+    Log(("vbglDriverOpen: failed\n"));
+    RT_NOREF(pHandle);
+    return VERR_FILE_NOT_FOUND;
+}
+
+
+int VBOXCALL vbglR0IdcNativeClose(PVBGLIDCHANDLE pHandle, PVBGLIOCIDCDISCONNECT pReq)
+{
+    return g_VBoxGuestIDC.pfnServiceEP((uintptr_t)pHandle->s.pvSession, VBGL_IOCTL_IDC_DISCONNECT, &pReq->Hdr, sizeof(*pReq));
+}
+
+
+/**
+ * Makes an IDC call, returning only the I/O control status code.
+ *
+ * @returns VBox status code (the I/O control failure status).
+ * @param   pHandle             The IDC handle.
+ * @param   uReq                The request number.
+ * @param   pReqHdr             The request header.
+ * @param   cbReq               The request size.
+ */
+DECLR0VBGL(int) VbglR0IdcCallRaw(PVBGLIDCHANDLE pHandle, uintptr_t uReq, PVBGLREQHDR pReqHdr, uint32_t cbReq)
+{
+    return g_VBoxGuestIDC.pfnServiceEP((uintptr_t)pHandle->s.pvSession, uReq, pReqHdr, cbReq);
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibIdc-solaris.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibIdc-solaris.cpp
new file mode 100644
index 00000000..760f060c
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibIdc-solaris.cpp
@@ -0,0 +1,97 @@
+/* $Id: VBoxGuestR0LibIdc-solaris.cpp $ */
+/** @file
+ * VBoxGuestLib - Ring-0 Support Library for VBoxGuest, IDC, Solaris specific.
+ */
+
+/*
+ * Copyright (C) 2008-2023 Oracle and/or its affiliates.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <sys/conf.h>
+#include <sys/sunldi.h>
+#include <sys/file.h>
+#undef u /* /usr/include/sys/user.h:249:1 is where this is defined to (curproc->p_user). very cool. */
+#include "VBoxGuestR0LibInternal.h"
+#include <VBox/err.h>
+
+
+int VBOXCALL vbglR0IdcNativeOpen(PVBGLIDCHANDLE pHandle, PVBGLIOCIDCCONNECT pReq)
+{
+    ldi_handle_t hDev   = NULL;
+    ldi_ident_t  hIdent = ldi_ident_from_anon();
+    int rc = ldi_open_by_name((char *)VBOXGUEST_DEVICE_NAME, FREAD, kcred, &hDev, hIdent);
+    ldi_ident_release(hIdent);
+    if (rc == 0)
+    {
+        pHandle->s.hDev = hDev;
+        rc = VbglR0IdcCallRaw(pHandle, VBGL_IOCTL_IDC_CONNECT, &pReq->Hdr, sizeof(*pReq));
+        if (RT_SUCCESS(rc) && RT_SUCCESS(pReq->Hdr.rc))
+            return VINF_SUCCESS;
+        ldi_close(hDev, FREAD, kcred);
+    }
+    else
+        rc = VERR_OPEN_FAILED;
+    pHandle->s.hDev = NULL;
+    return rc;
+}
+
+
+int VBOXCALL vbglR0IdcNativeClose(PVBGLIDCHANDLE pHandle, PVBGLIOCIDCDISCONNECT pReq)
+{
+    int rc = VbglR0IdcCallRaw(pHandle, VBGL_IOCTL_IDC_DISCONNECT, &pReq->Hdr, sizeof(*pReq));
+    if (RT_SUCCESS(rc) && RT_SUCCESS(pReq->Hdr.rc))
+    {
+        ldi_close(pHandle->s.hDev, FREAD, kcred);
+        pHandle->s.hDev = NULL;
+    }
+    return rc;
+}
+
+
+/**
+ * Makes an IDC call, returning only the I/O control status code.
+ *
+ * @returns VBox status code (the I/O control failure status).
+ * @param   pHandle             The IDC handle.
+ * @param   uReq                The request number.
+ * @param   pReqHdr             The request header.
+ * @param   cbReq               The request size.
+ */
+DECLR0VBGL(int) VbglR0IdcCallRaw(PVBGLIDCHANDLE pHandle, uintptr_t uReq, PVBGLREQHDR pReqHdr, uint32_t cbReq)
+{
+#if 0
+    return VBoxGuestIDC(pHandle->s.pvSession, uReq, pReqHdr, cbReq);
+#else
+    int iIgn;
+    int rc = ldi_ioctl(pHandle->s.hDev, uReq, (intptr_t)pReqHdr, FKIOCTL | FNATIVE, kcred, &iIgn);
+    if (rc == 0)
+        return VINF_SUCCESS;
+    return RTErrConvertFromErrno(rc);
+#endif
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibIdc-unix.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibIdc-unix.cpp
new file mode 100644
index 00000000..8aefb725
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibIdc-unix.cpp
@@ -0,0 +1,64 @@
+/* $Id: VBoxGuestR0LibIdc-unix.cpp $ */
+/** @file
+ * VBoxGuestLib - Ring-0 Support Library for VBoxGuest, IDC, UNIX-like OSes.
+ */
+
+/*
+ * Copyright (C) 2008-2023 Oracle and/or its affiliates.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "VBoxGuestR0LibInternal.h"
+
+
+int VBOXCALL vbglR0IdcNativeOpen(PVBGLIDCHANDLE pHandle, PVBGLIOCIDCCONNECT pReq)
+{
+    RT_NOREF(pHandle);
+    return VBoxGuestIDC(NULL /*pvSession*/, VBGL_IOCTL_IDC_CONNECT, &pReq->Hdr, sizeof(*pReq));
+}
+
+
+int VBOXCALL vbglR0IdcNativeClose(PVBGLIDCHANDLE pHandle, PVBGLIOCIDCDISCONNECT pReq)
+{
+    return VBoxGuestIDC(pHandle->s.pvSession, VBGL_IOCTL_IDC_DISCONNECT, &pReq->Hdr, sizeof(*pReq));
+}
+
+
+/**
+ * Makes an IDC call, returning only the I/O control status code.
+ *
+ * @returns VBox status code (the I/O control failure status).
+ * @param   pHandle             The IDC handle.
+ * @param   uReq                The request number.
+ * @param   pReqHdr             The request header.
+ * @param   cbReq               The request size.
+ */
+DECLR0VBGL(int) VbglR0IdcCallRaw(PVBGLIDCHANDLE pHandle, uintptr_t uReq, PVBGLREQHDR pReqHdr, uint32_t cbReq)
+{
+    return VBoxGuestIDC(pHandle->s.pvSession, uReq, pReqHdr, cbReq);
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibIdc-win.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibIdc-win.cpp
new file mode 100644
index 00000000..395667e0
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibIdc-win.cpp
@@ -0,0 +1,208 @@
+/* $Id: VBoxGuestR0LibIdc-win.cpp $ */
+/** @file
+ * VBoxGuestLib - Ring-0 Support Library for VBoxGuest, IDC, Windows specific.
+ */
+
+/*
+ * Copyright (C) 2008-2023 Oracle and/or its affiliates.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/nt/nt.h>
+#include "VBoxGuestR0LibInternal.h"
+#include <VBox/VBoxGuest.h>
+#include <iprt/errcore.h>
+#include <VBox/log.h>
+
+
+/**
+ * Internal I/O Control call worker.
+ *
+ * @returns VBox status code.
+ * @param   pDeviceObject   The device object to call.
+ * @param   pFileObject     The file object for the connection.
+ * @param   uReq            The request.
+ * @param   pReq            The request packet.
+ */
+static int vbglR0IdcNtCallInternal(PDEVICE_OBJECT pDeviceObject, PFILE_OBJECT pFileObject, uint32_t uReq, PVBGLREQHDR pReq)
+{
+    int      rc;
+    NTSTATUS rcNt;
+
+    /*
+     * Build the request.
+     *
+     * We want to avoid double buffering of the request, therefore we don't
+     * specify any request pointers or sizes when asking the kernel to build
+     * the IRP for us, but instead do that part our selves.
+     *
+     * See https://www.osr.com/blog/2018/02/14/beware-iobuilddeviceiocontrolrequest/
+     * for how fun this is when we're not at IRQL PASSIVE (HACK ALERT futher down).
+     * Ran into this little issue when LoadLibraryEx on a .NET DLL using the
+     * LOAD_LIBRARY_AS_DATAFILE and LOAD_LIBRARY_AS_IMAGE_RESOURCE flags.
+     */
+    KEVENT Event;
+    KeInitializeEvent(&Event, NotificationEvent, FALSE);
+
+    IO_STATUS_BLOCK IoStatusBlock = RTNT_IO_STATUS_BLOCK_INITIALIZER;
+#if 0
+    PIRP pIrp = IoBuildDeviceIoControlRequest(uReq,              /* IoControlCode */
+                                              pDeviceObject,
+                                              pReq,              /* InputBuffer */
+                                              pReq->cbIn,        /* InputBufferLength */
+                                              pReq,              /* OutputBuffer */
+                                              pReq->cbOut,       /* OutputBufferLength */
+                                              TRUE,              /* InternalDeviceIoControl (=> IRP_MJ_INTERNAL_DEVICE_CONTROL) */
+                                              &Event,            /* Event */
+                                              &IoStatusBlock);   /* IoStatusBlock */
+#else
+    PIRP pIrp = IoBuildDeviceIoControlRequest(uReq,              /* IoControlCode */
+                                              pDeviceObject,
+                                              NULL,              /* InputBuffer */
+                                              0,                 /* InputBufferLength */
+                                              NULL,              /* OutputBuffer */
+                                              0,                 /* OutputBufferLength */
+                                              TRUE,              /* InternalDeviceIoControl (=> IRP_MJ_INTERNAL_DEVICE_CONTROL) */
+                                              &Event,            /* Event */
+                                              &IoStatusBlock);   /* IoStatusBlock */
+#endif
+    if (pIrp)
+    {
+#if 0
+        IoGetNextIrpStackLocation(pIrp)->FileObject = pFileObject;
+#else
+        //w2k3sp1+: if (!KeAreAllApcsDisabled())
+        //w2k3sp1+:     pIrp->Flags                                      |= IRP_SYNCHRONOUS_API;
+        //w2k3sp1+: else
+        {
+            /* HACK ALERT! Causes IoCompleteRequest to update UserIosb and free the IRP w/o any APC happening. */
+            pIrp->Flags                                      |= IRP_SYNCHRONOUS_API | IRP_PAGING_IO | IRP_SYNCHRONOUS_PAGING_IO;
+            KIRQL bIrqlSaved;
+            KeRaiseIrql(APC_LEVEL, &bIrqlSaved);
+            RemoveEntryList(&pIrp->ThreadListEntry);
+            InitializeListHead(&pIrp->ThreadListEntry);
+            KeLowerIrql(bIrqlSaved);
+        }
+        pIrp->UserBuffer                                      = pReq;
+        pIrp->AssociatedIrp.SystemBuffer                      = pReq;
+        PIO_STACK_LOCATION pStack = IoGetNextIrpStackLocation(pIrp);
+        pStack->FileObject                                    = pFileObject;
+        pStack->Parameters.DeviceIoControl.OutputBufferLength = pReq->cbOut;
+        pStack->Parameters.DeviceIoControl.InputBufferLength  = pReq->cbIn;
+#endif
+
+        /*
+         * Call the driver, wait for an async request to complete (should never happen).
+         */
+        rcNt = IoCallDriver(pDeviceObject, pIrp);
+        if (rcNt == STATUS_PENDING)
+            rcNt = KeWaitForSingleObject(&Event,            /* Object */
+                                         Executive,         /* WaitReason */
+                                         KernelMode,        /* WaitMode */
+                                         FALSE,             /* Alertable */
+                                         NULL);             /* TimeOut */
+        if (NT_SUCCESS(rcNt))
+            rcNt = IoStatusBlock.Status;
+        if (NT_SUCCESS(rcNt))
+            rc = pReq->rc;
+        else
+            rc = RTErrConvertFromNtStatus(rcNt);
+    }
+    else
+        rc = VERR_NO_MEMORY;
+    return rc;
+}
+
+
+int VBOXCALL vbglR0IdcNativeOpen(PVBGLIDCHANDLE pHandle, PVBGLIOCIDCCONNECT pReq)
+{
+    PDEVICE_OBJECT  pDeviceObject = NULL;
+    PFILE_OBJECT    pFileObject = NULL;
+    UNICODE_STRING  wszDeviceName;
+    NTSTATUS        rcNt;
+    int             rc;
+
+    /*
+     * Get the device object pointer.
+     */
+    RtlInitUnicodeString(&wszDeviceName, VBOXGUEST_DEVICE_NAME_NT);
+    rcNt = IoGetDeviceObjectPointer(&wszDeviceName, FILE_ALL_ACCESS, &pFileObject, &pDeviceObject);
+    if (NT_SUCCESS(rcNt))
+    {
+        /*
+         * Make the connection call.
+         */
+        rc = vbglR0IdcNtCallInternal(pDeviceObject, pFileObject, VBGL_IOCTL_IDC_CONNECT, &pReq->Hdr);
+        if (RT_SUCCESS(rc) && RT_SUCCESS(pReq->Hdr.rc))
+        {
+            pHandle->s.pDeviceObject = pDeviceObject;
+            pHandle->s.pFileObject   = pFileObject;
+            return rc;
+        }
+
+        /* only the file object. */
+        ObDereferenceObject(pFileObject);
+    }
+    else
+        rc = RTErrConvertFromNtStatus(rcNt);
+
+    pHandle->s.pDeviceObject = NULL;
+    pHandle->s.pFileObject = NULL;
+    return rc;
+}
+
+
+int VBOXCALL vbglR0IdcNativeClose(PVBGLIDCHANDLE pHandle, PVBGLIOCIDCDISCONNECT pReq)
+{
+    PFILE_OBJECT pFileObject = pHandle->s.pFileObject;
+    int rc = vbglR0IdcNtCallInternal(pHandle->s.pDeviceObject, pFileObject, VBGL_IOCTL_IDC_DISCONNECT, &pReq->Hdr);
+    if (RT_SUCCESS(rc) && RT_SUCCESS(pReq->Hdr.rc))
+    {
+        pHandle->s.pDeviceObject = NULL;
+        pHandle->s.pFileObject   = NULL;
+        ObDereferenceObject(pFileObject);
+    }
+
+    return rc;
+}
+
+
+/**
+ * Makes an IDC call, returning only the I/O control status code.
+ *
+ * @returns VBox status code (the I/O control failure status).
+ * @param   pHandle             The IDC handle.
+ * @param   uReq                The request number.
+ * @param   pReqHdr             The request header.
+ * @param   cbReq               The request size.
+ */
+DECLR0VBGL(int) VbglR0IdcCallRaw(PVBGLIDCHANDLE pHandle, uintptr_t uReq, PVBGLREQHDR pReqHdr, uint32_t cbReq)
+{
+    NOREF(cbReq);
+    return vbglR0IdcNtCallInternal(pHandle->s.pDeviceObject, pHandle->s.pFileObject, (uint32_t)uReq, pReqHdr);
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibIdc.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibIdc.cpp
new file mode 100644
index 00000000..c0b0ac53
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibIdc.cpp
@@ -0,0 +1,205 @@
+/* $Id: VBoxGuestR0LibIdc.cpp $ */
+/** @file
+ * VBoxGuestLib - Ring-0 Support Library for VBoxGuest, IDC.
+ */
+
+/*
+ * Copyright (C) 2008-2023 Oracle and/or its affiliates.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "VBoxGuestR0LibInternal.h"
+#include <iprt/errcore.h>
+#include <VBox/VBoxGuest.h>
+/*#include <iprt/asm.h>*/
+
+#ifdef VBGL_VBOXGUEST
+# error "This file shouldn't be part of the VBoxGuestR0LibBase library that is linked into VBoxGuest.  It's client code."
+#endif
+
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/*static PVBGLIDCHANDLE volatile g_pMainHandle = NULL;*/
+
+
+/**
+ * Opens the IDC interface of the support driver.
+ *
+ * This will perform basic version negotiations and fail if the
+ * minimum requirements aren't met.
+ *
+ * @returns VBox status code.
+ * @param   pHandle             The handle structure (output).
+ * @param   uReqVersion         The requested version. Pass 0 for default.
+ * @param   uMinVersion         The minimum required version. Pass 0 for default.
+ * @param   puSessionVersion    Where to store the session version. Optional.
+ * @param   puDriverVersion     Where to store the session version. Optional.
+ * @param   puDriverRevision    Where to store the SVN revision of the driver. Optional.
+ */
+DECLR0VBGL(int) VbglR0IdcOpen(PVBGLIDCHANDLE pHandle, uint32_t uReqVersion, uint32_t uMinVersion,
+                              uint32_t *puSessionVersion, uint32_t *puDriverVersion, uint32_t *puDriverRevision)
+{
+    unsigned uDefaultMinVersion;
+    VBGLIOCIDCCONNECT Req;
+    int rc;
+
+    /*
+     * Validate and set failure return values.
+     */
+    AssertPtrReturn(pHandle, VERR_INVALID_POINTER);
+    pHandle->s.pvSession = NULL;
+
+    AssertPtrNullReturn(puSessionVersion, VERR_INVALID_POINTER);
+    if (puSessionVersion)
+        *puSessionVersion = 0;
+
+    AssertPtrNullReturn(puDriverVersion, VERR_INVALID_POINTER);
+    if (puDriverVersion)
+        *puDriverVersion = 0;
+
+    AssertPtrNullReturn(puDriverRevision, VERR_INVALID_POINTER);
+    if (puDriverRevision)
+        *puDriverRevision = 0;
+
+    AssertReturn(!uMinVersion || (uMinVersion & UINT32_C(0xffff0000)) == (VBGL_IOC_VERSION & UINT32_C(0xffff0000)), VERR_INVALID_PARAMETER);
+    AssertReturn(!uReqVersion || (uReqVersion & UINT32_C(0xffff0000)) == (VBGL_IOC_VERSION & UINT32_C(0xffff0000)), VERR_INVALID_PARAMETER);
+
+    /*
+     * Handle default version input and enforce minimum requirements made
+     * by this library.
+     *
+     * The clients will pass defaults (0), and only in the case that some
+     * special API feature was just added will they set an actual version.
+     * So, this is the place where can easily enforce a minimum IDC version
+     * on bugs and similar. It corresponds a bit to what SUPR3Init is
+     * responsible for.
+     */
+    uDefaultMinVersion = VBGL_IOC_VERSION & UINT32_C(0xffff0000);
+    if (!uMinVersion || uMinVersion < uDefaultMinVersion)
+        uMinVersion = uDefaultMinVersion;
+    if (!uReqVersion || uReqVersion < uDefaultMinVersion)
+        uReqVersion = uDefaultMinVersion;
+
+    /*
+     * Setup the connect request packet and call the OS specific function.
+     */
+    VBGLREQHDR_INIT(&Req.Hdr, IDC_CONNECT);
+    Req.u.In.u32MagicCookie = VBGL_IOCTL_IDC_CONNECT_MAGIC_COOKIE;
+    Req.u.In.uMinVersion = uMinVersion;
+    Req.u.In.uReqVersion = uReqVersion;
+    Req.u.In.uReserved = 0;
+    rc = vbglR0IdcNativeOpen(pHandle, &Req);
+    if (RT_SUCCESS(rc))
+        rc = Req.Hdr.rc;
+    if (RT_SUCCESS(rc))
+    {
+        pHandle->s.pvSession = Req.u.Out.pvSession;
+        if (puSessionVersion)
+            *puSessionVersion = Req.u.Out.uSessionVersion;
+        if (puDriverVersion)
+            *puDriverVersion = Req.u.Out.uDriverVersion;
+        if (puDriverRevision)
+            *puDriverRevision = Req.u.Out.uDriverRevision;
+
+        /*
+         * We don't really trust anyone, make sure the returned
+         * session and version values actually makes sense.
+         */
+        if (    RT_VALID_PTR(Req.u.Out.pvSession)
+            &&  Req.u.Out.uSessionVersion >= uMinVersion
+            &&  (Req.u.Out.uSessionVersion & UINT32_C(0xffff0000)) == (VBGL_IOC_VERSION & UINT32_C(0xffff0000)))
+        {
+            /*ASMAtomicCmpXchgPtr(&g_pMainHandle, pHandle, NULL);*/
+            return rc;
+        }
+
+        AssertMsgFailed(("pSession=%p uSessionVersion=0x%x (r%u)\n", Req.u.Out.pvSession, Req.u.Out.uSessionVersion, Req.u.Out.uDriverRevision));
+        rc = VERR_VERSION_MISMATCH;
+        VbglR0IdcClose(pHandle);
+    }
+
+    return rc;
+}
+
+
+/**
+ * Closes a IDC connection established by VbglR0IdcOpen.
+ *
+ * @returns VBox status code.
+ * @param   pHandle     The IDC handle.
+ */
+DECLR0VBGL(int) VbglR0IdcClose(PVBGLIDCHANDLE pHandle)
+{
+    VBGLIOCIDCDISCONNECT Req;
+    int rc;
+
+    /*
+     * Catch closed handles and check that the session is valid.
+     */
+    AssertPtrReturn(pHandle, VERR_INVALID_POINTER);
+    if (!pHandle->s.pvSession)
+        return VERR_INVALID_HANDLE;
+    AssertPtrReturn(pHandle->s.pvSession, VERR_INVALID_HANDLE);
+
+    /*
+     * Create the request and hand it to the OS specific code.
+     */
+    VBGLREQHDR_INIT(&Req.Hdr, IDC_DISCONNECT);
+    Req.u.In.pvSession = pHandle->s.pvSession;
+    rc = vbglR0IdcNativeClose(pHandle, &Req);
+    if (RT_SUCCESS(rc))
+        rc = Req.Hdr.rc;
+    if (RT_SUCCESS(rc))
+    {
+        pHandle->s.pvSession = NULL;
+        /*ASMAtomicCmpXchgPtr(&g_pMainHandle, NULL, pHandle);*/
+    }
+    return rc;
+}
+
+
+/**
+ * Makes an IDC call, returning the request status.
+ *
+ * @returns VBox status code.  Request status if the I/O control succeeds,
+ *          otherwise the I/O control failure status.
+ * @param   pHandle             The IDC handle.
+ * @param   uReq                The request number.
+ * @param   pReqHdr             The request header.
+ * @param   cbReq               The request size.
+ */
+DECLR0VBGL(int) VbglR0IdcCall(PVBGLIDCHANDLE pHandle, uintptr_t uReq, PVBGLREQHDR pReqHdr, uint32_t cbReq)
+{
+    int rc = VbglR0IdcCallRaw(pHandle, uReq, pReqHdr, cbReq);
+    if (RT_SUCCESS(rc))
+        rc = pReqHdr->rc;
+    return rc;
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibInit.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibInit.cpp
new file mode 100644
index 00000000..0ed6c35f
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibInit.cpp
@@ -0,0 +1,333 @@
+/* $Id: VBoxGuestR0LibInit.cpp $ */
+/** @file
+ * VBoxGuestLibR0 - Library initialization.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "VBoxGuestR0LibInternal.h"
+
+#include <iprt/string.h>
+#include <iprt/assert.h>
+#include <iprt/semaphore.h>
+#include <VBox/err.h>
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/** The global VBGL instance data.  */
+VBGLDATA g_vbgldata;
+
+
+/**
+ * Used by vbglR0QueryDriverInfo and VbglInit to try get the host feature mask
+ * and version information (g_vbgldata::hostVersion).
+ *
+ * This was first implemented by the host in 3.1 and we quietly ignore failures
+ * for that reason.
+ */
+static void vbglR0QueryHostVersion(void)
+{
+    VMMDevReqHostVersion *pReq;
+    int rc = VbglR0GRAlloc((VMMDevRequestHeader **) &pReq, sizeof (*pReq), VMMDevReq_GetHostVersion);
+    if (RT_SUCCESS(rc))
+    {
+        rc = VbglR0GRPerform(&pReq->header);
+        if (RT_SUCCESS(rc))
+        {
+            g_vbgldata.hostVersion = *pReq;
+            Log(("vbglR0QueryHostVersion: %u.%u.%ur%u %#x\n",
+                 pReq->major, pReq->minor, pReq->build, pReq->revision, pReq->features));
+        }
+
+        VbglR0GRFree(&pReq->header);
+    }
+}
+
+
+#ifndef VBGL_VBOXGUEST
+/**
+ * The guest library uses lazy initialization for VMMDev port and memory,
+ * because these values are provided by the VBoxGuest driver and it might
+ * be loaded later than other drivers.
+ *
+ * The VbglEnter checks the current library status, tries to retrieve these
+ * values and fails if they are unavailable.
+ */
+static int vbglR0QueryDriverInfo(void)
+{
+# ifdef VBGLDATA_USE_FAST_MUTEX
+    int rc = RTSemFastMutexRequest(g_vbgldata.hMtxIdcSetup);
+# else
+    int rc = RTSemMutexRequest(g_vbgldata.hMtxIdcSetup, RT_INDEFINITE_WAIT);
+# endif
+    if (RT_SUCCESS(rc))
+    {
+        if (g_vbgldata.status == VbglStatusReady)
+        { /* likely */ }
+        else
+        {
+            rc = VbglR0IdcOpen(&g_vbgldata.IdcHandle,
+                               VBGL_IOC_VERSION /*uReqVersion*/,
+                               VBGL_IOC_VERSION & UINT32_C(0xffff0000) /*uMinVersion*/,
+                               NULL /*puSessionVersion*/, NULL /*puDriverVersion*/, NULL /*puDriverRevision*/);
+            if (RT_SUCCESS(rc))
+            {
+                /*
+                 * Try query the port info.
+                 */
+                VBGLIOCGETVMMDEVIOINFO PortInfo;
+                RT_ZERO(PortInfo);
+                VBGLREQHDR_INIT(&PortInfo.Hdr, GET_VMMDEV_IO_INFO);
+                rc = VbglR0IdcCall(&g_vbgldata.IdcHandle, VBGL_IOCTL_GET_VMMDEV_IO_INFO, &PortInfo.Hdr, sizeof(PortInfo));
+                if (RT_SUCCESS(rc))
+                {
+                    dprintf(("Port I/O = 0x%04x, MMIO = %p\n", PortInfo.u.Out.IoPort, PortInfo.u.Out.pvVmmDevMapping));
+
+                    g_vbgldata.portVMMDev    = PortInfo.u.Out.IoPort;
+                    g_vbgldata.pVMMDevMemory = (VMMDevMemory *)PortInfo.u.Out.pvVmmDevMapping;
+                    g_vbgldata.status        = VbglStatusReady;
+
+                    vbglR0QueryHostVersion();
+                }
+            }
+
+            dprintf(("vbglQueryDriverInfo rc = %Rrc\n", rc));
+        }
+
+# ifdef VBGLDATA_USE_FAST_MUTEX
+        RTSemFastMutexRelease(g_vbgldata.hMtxIdcSetup);
+# else
+        RTSemMutexRelease(g_vbgldata.hMtxIdcSetup);
+# endif
+    }
+    return rc;
+}
+#endif /* !VBGL_VBOXGUEST */
+
+/**
+ * Checks if VBGL has been initialized.
+ *
+ * The client library, this will lazily complete the initialization.
+ *
+ * @return VINF_SUCCESS or VERR_VBGL_NOT_INITIALIZED.
+ */
+int vbglR0Enter(void)
+{
+    if (g_vbgldata.status == VbglStatusReady)
+        return VINF_SUCCESS;
+
+#ifndef VBGL_VBOXGUEST
+    if (g_vbgldata.status == VbglStatusInitializing)
+    {
+        vbglR0QueryDriverInfo();
+        if (g_vbgldata.status == VbglStatusReady)
+            return VINF_SUCCESS;
+    }
+#endif
+    return VERR_VBGL_NOT_INITIALIZED;
+}
+
+
+static int vbglR0InitCommon(void)
+{
+    int rc;
+
+    RT_ZERO(g_vbgldata);
+    g_vbgldata.status = VbglStatusInitializing;
+
+    rc = VbglR0PhysHeapInit();
+    if (RT_SUCCESS(rc))
+    {
+        dprintf(("vbglR0InitCommon: returns rc = %d\n", rc));
+        return rc;
+    }
+
+    LogRel(("vbglR0InitCommon: VbglR0PhysHeapInit failed: rc=%Rrc\n", rc));
+    g_vbgldata.status = VbglStatusNotInitialized;
+    return rc;
+}
+
+
+static void vbglR0TerminateCommon(void)
+{
+    VbglR0PhysHeapTerminate();
+    g_vbgldata.status = VbglStatusNotInitialized;
+}
+
+#ifdef VBGL_VBOXGUEST
+
+DECLR0VBGL(int) VbglR0InitPrimary(RTIOPORT portVMMDev, VMMDevMemory *pVMMDevMemory, uint32_t *pfFeatures)
+{
+    int rc;
+
+# ifdef RT_OS_WINDOWS /** @todo r=bird: this doesn't make sense. Is there something special going on on windows? */
+    dprintf(("vbglInit: starts g_vbgldata.status %d\n", g_vbgldata.status));
+
+    if (   g_vbgldata.status == VbglStatusInitializing
+        || g_vbgldata.status == VbglStatusReady)
+    {
+        /* Initialization is already in process. */
+        return VINF_SUCCESS;
+    }
+# else
+    dprintf(("vbglInit: starts\n"));
+# endif
+
+    rc = vbglR0InitCommon();
+    if (RT_SUCCESS(rc))
+    {
+        g_vbgldata.portVMMDev    = portVMMDev;
+        g_vbgldata.pVMMDevMemory = pVMMDevMemory;
+        g_vbgldata.status        = VbglStatusReady;
+
+        vbglR0QueryHostVersion();
+        *pfFeatures = g_vbgldata.hostVersion.features;
+        return VINF_SUCCESS;
+    }
+
+    g_vbgldata.status = VbglStatusNotInitialized;
+    return rc;
+}
+
+DECLR0VBGL(void) VbglR0TerminatePrimary(void)
+{
+    vbglR0TerminateCommon();
+}
+
+
+#else /* !VBGL_VBOXGUEST */
+
+DECLR0VBGL(int) VbglR0InitClient(void)
+{
+    int rc;
+
+    /** @todo r=bird: explain why we need to be doing this, please... */
+    if (   g_vbgldata.status == VbglStatusInitializing
+        || g_vbgldata.status == VbglStatusReady)
+    {
+        /* Initialization is already in process. */
+        return VINF_SUCCESS;
+    }
+
+    rc = vbglR0InitCommon();
+    if (RT_SUCCESS(rc))
+    {
+# ifdef VBGLDATA_USE_FAST_MUTEX
+        rc = RTSemFastMutexCreate(&g_vbgldata.hMtxIdcSetup);
+# else
+        rc = RTSemMutexCreate(&g_vbgldata.hMtxIdcSetup);
+# endif
+        if (RT_SUCCESS(rc))
+        {
+            /* Try to obtain VMMDev port via IOCTL to VBoxGuest main driver. */
+            vbglR0QueryDriverInfo();
+
+# ifdef VBOX_WITH_HGCM
+            rc = VbglR0HGCMInit();
+# endif
+            if (RT_SUCCESS(rc))
+                return VINF_SUCCESS;
+
+# ifdef VBGLDATA_USE_FAST_MUTEX
+            RTSemFastMutexDestroy(g_vbgldata.hMtxIdcSetup);
+            g_vbgldata.hMtxIdcSetup = NIL_RTSEMFASTMUTEX;
+# else
+            RTSemMutexDestroy(g_vbgldata.hMtxIdcSetup);
+            g_vbgldata.hMtxIdcSetup = NIL_RTSEMMUTEX;
+# endif
+        }
+        vbglR0TerminateCommon();
+    }
+
+    return rc;
+}
+
+DECLR0VBGL(void) VbglR0TerminateClient(void)
+{
+# ifdef VBOX_WITH_HGCM
+    VbglR0HGCMTerminate();
+# endif
+
+    /* driver open could fail, which does not prevent VbglInit from succeeding,
+     * close the driver only if it is opened */
+    VbglR0IdcClose(&g_vbgldata.IdcHandle);
+# ifdef VBGLDATA_USE_FAST_MUTEX
+    RTSemFastMutexDestroy(g_vbgldata.hMtxIdcSetup);
+    g_vbgldata.hMtxIdcSetup = NIL_RTSEMFASTMUTEX;
+# else
+    RTSemMutexDestroy(g_vbgldata.hMtxIdcSetup);
+    g_vbgldata.hMtxIdcSetup = NIL_RTSEMMUTEX;
+# endif
+
+    /* note: do vbglR0TerminateCommon as a last step since it zeroez up the g_vbgldata
+     * conceptually, doing vbglR0TerminateCommon last is correct
+     * since this is the reverse order to how init is done */
+    vbglR0TerminateCommon();
+}
+
+
+int VBOXCALL vbglR0QueryIdcHandle(PVBGLIDCHANDLE *ppIdcHandle)
+{
+    if (g_vbgldata.status == VbglStatusReady)
+    { /* likely */ }
+    else
+    {
+        vbglR0QueryDriverInfo();
+        if (g_vbgldata.status != VbglStatusReady)
+        {
+            *ppIdcHandle = NULL;
+            return VERR_TRY_AGAIN;
+        }
+    }
+
+    *ppIdcHandle = &g_vbgldata.IdcHandle;
+    return VINF_SUCCESS;
+}
+
+
+DECLR0VBGL(int) VbglR0QueryHostFeatures(uint32_t *pfHostFeatures)
+{
+    if (g_vbgldata.status == VbglStatusReady)
+        *pfHostFeatures = g_vbgldata.hostVersion.features;
+    else
+    {
+        int rc = vbglR0QueryDriverInfo();
+        if (g_vbgldata.status != VbglStatusReady)
+            return rc;
+        *pfHostFeatures = g_vbgldata.hostVersion.features;
+    }
+
+    return VINF_SUCCESS;
+}
+
+#endif /* !VBGL_VBOXGUEST */
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibInternal.h b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibInternal.h
new file mode 100644
index 00000000..81657a8e
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibInternal.h
@@ -0,0 +1,212 @@
+/* $Id: VBoxGuestR0LibInternal.h $ */
+/** @file
+ * VBoxGuestLibR0 - Internal header.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef GA_INCLUDED_SRC_common_VBoxGuest_lib_VBoxGuestR0LibInternal_h
+#define GA_INCLUDED_SRC_common_VBoxGuest_lib_VBoxGuestR0LibInternal_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+/*
+ * Define the private IDC handle structure before we include the VBoxGuestLib.h header.
+ */
+#include <iprt/types.h>
+#include <iprt/assert.h>
+RT_C_DECLS_BEGIN
+
+# ifndef VBGL_VBOXGUEST
+/**
+ * The hidden part of VBGLIDCHANDLE.
+ */
+struct VBGLIDCHANDLEPRIVATE
+{
+    /** Pointer to the session handle. */
+    void           *pvSession;
+# if defined(RT_OS_WINDOWS) && (defined(IPRT_INCLUDED_nt_ntddk_h) || defined(IPRT_INCLUDED_nt_nt_h))
+    /** Pointer to the NT device object. */
+    PDEVICE_OBJECT  pDeviceObject;
+    /** Pointer to the NT file object. */
+    PFILE_OBJECT    pFileObject;
+# elif defined(RT_OS_SOLARIS) && defined(_SYS_SUNLDI_H)
+    /** LDI device handle to keep the device attached. */
+    ldi_handle_t    hDev;
+# endif
+};
+/** Indicate that the VBGLIDCHANDLEPRIVATE structure is present. */
+# define VBGLIDCHANDLEPRIVATE_DECLARED 1
+#endif
+
+#include <VBox/VMMDev.h>
+#include <VBox/VBoxGuest.h>
+#include <VBox/VBoxGuestLib.h>
+
+#ifdef VBGLIDCHANDLEPRIVATE_DECLARED
+AssertCompile(RT_SIZEOFMEMB(VBGLIDCHANDLE, apvPadding) >= sizeof(struct VBGLIDCHANDLEPRIVATE));
+#endif
+
+
+/*
+ * Native IDC functions.
+ */
+int VBOXCALL vbglR0IdcNativeOpen(PVBGLIDCHANDLE pHandle, PVBGLIOCIDCCONNECT pReq);
+int VBOXCALL vbglR0IdcNativeClose(PVBGLIDCHANDLE pHandle, PVBGLIOCIDCDISCONNECT pReq);
+
+
+/*
+ * Deprecated logging macro
+ */
+#include <VBox/log.h>
+#ifdef RT_OS_WINDOWS /** @todo dprintf() -> Log() */
+# if (defined(DEBUG) && !defined(NO_LOGGING)) || defined(LOG_ENABLED)
+#  define dprintf(a) RTLogBackdoorPrintf a
+# else
+#  define dprintf(a) do {} while (0)
+# endif
+#else
+# define dprintf(a) Log(a)
+#endif
+
+/*
+ * Lazy bird: OS/2 doesn't currently implement the RTSemMutex API in ring-0, so
+ *  use a fast mutex instead.   Unlike Windows, the OS/2 implementation
+ *  doesn't have any nasty side effects on IRQL-like context properties, so the
+ *  fast mutexes on OS/2 are identical to normal mutexes except for the missing
+ *  timeout aspec.  Fortunately we don't need timeouts here.
+ */
+#ifdef RT_OS_OS2
+# define VBGLDATA_USE_FAST_MUTEX
+#endif
+
+struct VBGLPHYSHEAPBLOCK;
+typedef struct VBGLPHYSHEAPBLOCK VBGLPHYSHEAPBLOCK;
+struct VBGLPHYSHEAPFREEBLOCK;
+typedef struct VBGLPHYSHEAPFREEBLOCK VBGLPHYSHEAPFREEBLOCK;
+struct VBGLPHYSHEAPCHUNK;
+typedef struct VBGLPHYSHEAPCHUNK VBGLPHYSHEAPCHUNK;
+
+enum VbglLibStatus
+{
+    VbglStatusNotInitialized = 0,
+    VbglStatusInitializing,
+    VbglStatusReady
+};
+
+/**
+ * Global VBGL ring-0 data.
+ * Lives in VBoxGuestR0LibInit.cpp.
+ */
+typedef struct VBGLDATA
+{
+    enum VbglLibStatus status;
+
+    RTIOPORT portVMMDev;
+
+    VMMDevMemory *pVMMDevMemory;
+
+    /** Physical memory heap data.
+     * @{
+     */
+    RTSEMFASTMUTEX          hMtxHeap;
+    /** Head of the block list (both free and allocated blocks).
+     * This runs parallel to the chunk list and is sorted by address within each
+     * chunk.  This allows merging with blocks both after and before when
+     * freeing. */
+    VBGLPHYSHEAPBLOCK      *pBlockHead;
+    /** Head of the free list.
+     *  This is not sorted and more on the most recently freed approach. */
+    VBGLPHYSHEAPFREEBLOCK  *pFreeHead;
+    /** Number of block of any kind. */
+    int32_t                 cBlocks;
+    /** Number of free blocks. */
+    int32_t                 cFreeBlocks;
+    /** Head of the chunk list. */
+    VBGLPHYSHEAPCHUNK      *pChunkHead;
+    /** @} */
+
+    /**
+     * The host version data.
+     */
+    VMMDevReqHostVersion hostVersion;
+
+
+#ifndef VBGL_VBOXGUEST
+    /** The IDC handle.  This is used for talking to the main driver. */
+    VBGLIDCHANDLE IdcHandle;
+    /** Mutex used to serialize IDC setup.   */
+# ifdef VBGLDATA_USE_FAST_MUTEX
+    RTSEMFASTMUTEX hMtxIdcSetup;
+# else
+    RTSEMMUTEX hMtxIdcSetup;
+# endif
+#endif
+} VBGLDATA;
+
+
+extern VBGLDATA g_vbgldata;
+
+/**
+ * Internal macro for checking whether we can pass physical page lists to the
+ * host.
+ *
+ * ASSUMES that vbglR0Enter has been called already.
+ *
+ * @param   a_fLocked       For the windows shared folders workarounds.
+ *
+ * @remarks Disabled the PageList feature for locked memory on Windows,
+ *          because a new MDL is created by VBGL to get the page addresses
+ *          and the pages from the MDL are marked as dirty when they should not.
+ */
+#if defined(RT_OS_WINDOWS)
+# define VBGLR0_CAN_USE_PHYS_PAGE_LIST(a_fLocked) \
+    ( !(a_fLocked) && (g_vbgldata.hostVersion.features & VMMDEV_HVF_HGCM_PHYS_PAGE_LIST) )
+#else
+# define VBGLR0_CAN_USE_PHYS_PAGE_LIST(a_fLocked) \
+    ( !!(g_vbgldata.hostVersion.features & VMMDEV_HVF_HGCM_PHYS_PAGE_LIST) )
+#endif
+
+int vbglR0Enter (void);
+
+#ifdef VBOX_WITH_HGCM
+struct VBGLHGCMHANDLEDATA  *vbglR0HGCMHandleAlloc(void);
+void                        vbglR0HGCMHandleFree(struct VBGLHGCMHANDLEDATA *pHandle);
+#endif /* VBOX_WITH_HGCM */
+
+#ifndef VBGL_VBOXGUEST
+/**
+ * Get the IDC handle to the main VBoxGuest driver.
+ * @returns VERR_TRY_AGAIN if the main driver has not yet been loaded.
+ */
+int VBOXCALL vbglR0QueryIdcHandle(PVBGLIDCHANDLE *ppIdcHandle);
+#endif
+
+RT_C_DECLS_END
+
+#endif /* !GA_INCLUDED_SRC_common_VBoxGuest_lib_VBoxGuestR0LibInternal_h */
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibMouse.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibMouse.cpp
new file mode 100644
index 00000000..a0c9e1c5
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibMouse.cpp
@@ -0,0 +1,130 @@
+/* $Id: VBoxGuestR0LibMouse.cpp $ */
+/** @file
+ * VBoxGuestLibR0 - Mouse Integration.
+ */
+
+/*
+ * Copyright (C) 2012-2023 Oracle and/or its affiliates.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "VBoxGuestR0LibInternal.h"
+#ifdef VBGL_VBOXGUEST
+# error "This file shouldn't be part of the VBoxGuestR0LibBase library that is linked into VBoxGuest.  It's client code."
+#endif
+
+
+/**
+ * Sets the function which is called back on each mouse pointer event.  Only
+ * one callback can be active at once, so if you need several for any reason
+ * you must multiplex yourself.  Call backs can be disabled by passing NULL
+ * as the function pointer.
+ *
+ * @remarks Ring-0.
+ * @returns iprt status code.
+ * @returns VERR_TRY_AGAIN if the main guest driver hasn't finished
+ *          initialising.
+ *
+ * @param   pfnNotify  the function to call back.  NULL to disable call backs.
+ * @param   pvUser     user supplied data/cookie to be passed to the function.
+ */
+DECLR0VBGL(int) VbglR0SetMouseNotifyCallback(PFNVBOXGUESTMOUSENOTIFY pfnNotify, void *pvUser)
+{
+    PVBGLIDCHANDLE pIdcHandle;
+    int rc = vbglR0QueryIdcHandle(&pIdcHandle);
+    if (RT_SUCCESS(rc))
+    {
+        VBGLIOCSETMOUSENOTIFYCALLBACK NotifyCallback;
+        VBGLREQHDR_INIT(&NotifyCallback.Hdr, SET_MOUSE_NOTIFY_CALLBACK);
+        NotifyCallback.u.In.pfnNotify = pfnNotify;
+        NotifyCallback.u.In.pvUser    = pvUser;
+        rc = VbglR0IdcCall(pIdcHandle, VBGL_IOCTL_SET_MOUSE_NOTIFY_CALLBACK, &NotifyCallback.Hdr, sizeof(NotifyCallback));
+    }
+    return rc;
+}
+
+
+/**
+ * Retrieve mouse coordinates and features from the host.
+ *
+ * @remarks Ring-0.
+ * @returns VBox status code.
+ *
+ * @param   pfFeatures  Where to store the mouse features.
+ * @param   px          Where to store the X co-ordinate.
+ * @param   py          Where to store the Y co-ordinate.
+ */
+DECLR0VBGL(int) VbglR0GetMouseStatus(uint32_t *pfFeatures, uint32_t *px, uint32_t *py)
+{
+    PVBGLIDCHANDLE pIdcHandle;
+    int rc = vbglR0QueryIdcHandle(&pIdcHandle);
+    if (RT_SUCCESS(rc))
+    {
+        VMMDevReqMouseStatus Req;
+        VMMDEV_REQ_HDR_INIT(&Req.header, sizeof(Req), VMMDevReq_GetMouseStatus);
+        Req.mouseFeatures = 0;
+        Req.pointerXPos = 0;
+        Req.pointerYPos = 0;
+        rc = VbglR0IdcCall(pIdcHandle, VBGL_IOCTL_VMMDEV_REQUEST(sizeof(Req)), (PVBGLREQHDR)&Req.header, sizeof(Req));
+        if (RT_SUCCESS(rc))
+        {
+            if (pfFeatures)
+                *pfFeatures = Req.mouseFeatures;
+            if (px)
+                *px = Req.pointerXPos;
+            if (py)
+                *py = Req.pointerYPos;
+        }
+    }
+    return rc;
+}
+
+
+/**
+ * Send mouse features to the host.
+ *
+ * @remarks Ring-0.
+ * @returns VBox status code.
+ *
+ * @param   fFeatures  Supported mouse pointer features.  The main guest driver
+ *                     will mediate different callers and show the host any
+ *                     feature enabled by any guest caller.
+ */
+DECLR0VBGL(int) VbglR0SetMouseStatus(uint32_t fFeatures)
+{
+    PVBGLIDCHANDLE pIdcHandle;
+    int rc = vbglR0QueryIdcHandle(&pIdcHandle);
+    if (RT_SUCCESS(rc))
+    {
+        VBGLIOCSETMOUSESTATUS Req;
+        VBGLREQHDR_INIT(&Req.Hdr, SET_MOUSE_STATUS);
+        Req.u.In.fStatus = fFeatures;
+        rc = VbglR0IdcCall(pIdcHandle, VBGL_IOCTL_SET_MOUSE_STATUS, &Req.Hdr, sizeof(Req));
+    }
+    return rc;
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibPhysHeap.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibPhysHeap.cpp
new file mode 100644
index 00000000..b99f51ad
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibPhysHeap.cpp
@@ -0,0 +1,1197 @@
+/* $Id: VBoxGuestR0LibPhysHeap.cpp $ */
+/** @file
+ * VBoxGuestLibR0 - Physical memory heap.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+/** @page pg_vbglr0_phys_heap   VBoxGuestLibR0 - Physical memory heap.
+ *
+ * Traditional heap implementation keeping all blocks in a ordered list and
+ * keeping free blocks on additional list via pointers in the user area.  This
+ * is similar to @ref grp_rt_heap_simple "RTHeapSimple" and
+ * @ref grp_rt_heap_offset "RTHeapOffset" in IPRT, except that this code handles
+ * mutiple chunks and has a physical address associated with each chunk and
+ * block.  The alignment is fixed (VBGL_PH_ALLOC_ALIGN).
+ *
+ * When allocating memory, a free block is found that satisfies the request,
+ * extending the heap with another chunk if needed.  The block is split if it's
+ * too large, and the tail end is put on the free list.
+ *
+ * When freeing memory, the block being freed is put back on the free list and
+ * we use the block list to check whether it can be merged with adjacent blocks.
+ *
+ * @note The original code managed the blocks in two separate lists for free and
+ *       allocated blocks, which had the disadvantage only allowing merging with
+ *       the block after the block being freed.  On the plus side, it had the
+ *       potential for slightly better locality when examining the free list,
+ *       since the next pointer and block size members were closer to one
+ *       another.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "VBoxGuestR0LibInternal.h"
+
+#include <iprt/assert.h>
+#include <iprt/err.h>
+#include <iprt/mem.h>
+#include <iprt/memobj.h>
+#include <iprt/semaphore.h>
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+/** Enables heap dumping. */
+#if defined(DOXYGEN_RUNNING) || 0
+# define VBGL_PH_DUMPHEAP
+#endif
+
+#ifdef VBGL_PH_DUMPHEAP
+# define VBGL_PH_DPRINTF(a)             RTAssertMsg2Weak a
+#else
+# define VBGL_PH_DPRINTF(a)             do { } while (0)
+#endif
+
+/** Heap chunk signature */
+#define VBGL_PH_CHUNKSIGNATURE          UINT32_C(0xADDCCCCC)
+/** Heap chunk allocation unit */
+#define VBGL_PH_CHUNKSIZE               (0x10000)
+
+/** Heap block signature */
+#define VBGL_PH_BLOCKSIGNATURE          UINT32_C(0xADDBBBBB)
+
+/** The allocation block alignment.
+ *
+ * This cannot be larger than VBGLPHYSHEAPBLOCK.
+ */
+#define VBGL_PH_ALLOC_ALIGN             (sizeof(void *))
+
+/** Max number of free nodes to search before just using the best fit.
+ *
+ * This is used to limit the free list walking during allocation and just get
+ * on with the job.  A low number should reduce the cache trashing at the
+ * possible cost of heap fragmentation.
+ *
+ * Picked 16 after comparing the tstVbglR0PhysHeap-1 results w/ uRandSeed=42 for
+ * different max values.
+ */
+#define VBGL_PH_MAX_FREE_SEARCH         16
+
+/** Threshold to stop the block search if a free block is at least this much too big.
+ *
+ * May cause more fragmation (depending on usage pattern), but should speed up
+ * allocation and hopefully reduce cache trashing.
+ *
+ * Since we merge adjacent free blocks when we can, free blocks should typically
+ * be a lot larger that what's requested.  So, it is probably a good idea to
+ * just chop up a large block rather than keep searching for a perfect-ish
+ * match.
+ *
+ * Undefine this to disable this trick.
+ */
+#if defined(DOXYGEN_RUNNING) || 1
+# define VBGL_PH_STOP_SEARCH_AT_EXCESS   _4K
+#endif
+
+/** Threshold at which to split out a tail free block when allocating.
+ *
+ * The value gives the amount of user space, i.e. excluding the header.
+ *
+ * Using 32 bytes based on VMMDev.h request sizes.  The smallest requests are 24
+ * bytes, i.e. only the header, at least 4 of these.  There are at least 10 with
+ * size 28 bytes and at least 11 with size 32 bytes.  So, 32 bytes would fit
+ * some 25 requests out of about 60, which is reasonable.
+ */
+#define VBGL_PH_MIN_SPLIT_FREE_BLOCK    32
+
+
+/** The smallest amount of user data that can be allocated.
+ *
+ * This is to ensure that the block can be converted into a
+ * VBGLPHYSHEAPFREEBLOCK structure when freed.  This must be smaller or equal
+ * to VBGL_PH_MIN_SPLIT_FREE_BLOCK.
+ */
+#define VBGL_PH_SMALLEST_ALLOC_SIZE     16
+
+/** The maximum allocation request size. */
+#define VBGL_PH_LARGEST_ALLOC_SIZE      RT_ALIGN_32(  _128M  \
+                                                    - sizeof(VBGLPHYSHEAPBLOCK) \
+                                                    - sizeof(VBGLPHYSHEAPCHUNK) \
+                                                    - VBGL_PH_ALLOC_ALIGN, \
+                                                    VBGL_PH_ALLOC_ALIGN)
+
+/**
+ * Whether to use the RTR0MemObjAllocCont API or RTMemContAlloc for
+ * allocating chunks.
+ *
+ * This can be enabled on hosts where RTMemContAlloc is more complicated than
+ * RTR0MemObjAllocCont.  This can also be done if we wish to save code space, as
+ * the latter is typically always dragged into the link on guests where the
+ * linker cannot eliminiate functions within objects.  Only drawback is that
+ * RTR0MemObjAllocCont requires another heap allocation for the handle.
+ */
+#if defined(DOXYGEN_RUNNING) || (!defined(IN_TESTCASE) && 0)
+# define VBGL_PH_USE_MEMOBJ
+#endif
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * A heap block (within a chunk).
+ *
+ * This is used to track a part of a heap chunk that's either free or
+ * allocated.  The VBGLPHYSHEAPBLOCK::fAllocated member indicates which it is.
+ */
+struct VBGLPHYSHEAPBLOCK
+{
+    /** Magic value (VBGL_PH_BLOCKSIGNATURE). */
+    uint32_t u32Signature;
+
+    /** Size of user data in the block. Does not include this block header. */
+    uint32_t cbUser : 31;
+    /** The top bit indicates whether it's allocated or free. */
+    uint32_t fAllocated : 1;
+
+    /** Pointer to the next block on the list. */
+    VBGLPHYSHEAPBLOCK  *pNext;
+    /** Pointer to the previous block on the list. */
+    VBGLPHYSHEAPBLOCK  *pPrev;
+    /** Pointer back to the chunk. */
+    VBGLPHYSHEAPCHUNK  *pChunk;
+};
+
+/**
+ * A free block.
+ */
+struct VBGLPHYSHEAPFREEBLOCK
+{
+    /** Core block data. */
+    VBGLPHYSHEAPBLOCK       Core;
+    /** Pointer to the next free list entry. */
+    VBGLPHYSHEAPFREEBLOCK  *pNextFree;
+    /** Pointer to the previous free list entry. */
+    VBGLPHYSHEAPFREEBLOCK  *pPrevFree;
+};
+AssertCompile(VBGL_PH_SMALLEST_ALLOC_SIZE  >= sizeof(VBGLPHYSHEAPFREEBLOCK) - sizeof(VBGLPHYSHEAPBLOCK));
+AssertCompile(VBGL_PH_MIN_SPLIT_FREE_BLOCK >= sizeof(VBGLPHYSHEAPFREEBLOCK) - sizeof(VBGLPHYSHEAPBLOCK));
+AssertCompile(VBGL_PH_MIN_SPLIT_FREE_BLOCK >= VBGL_PH_SMALLEST_ALLOC_SIZE);
+
+/**
+ * A chunk of memory used by the heap for sub-allocations.
+ *
+ * There is a list of these.
+ */
+struct VBGLPHYSHEAPCHUNK
+{
+    /** Magic value (VBGL_PH_CHUNKSIGNATURE). */
+    uint32_t u32Signature;
+
+    /** Size of the chunk. Includes the chunk header. */
+    uint32_t cbChunk;
+
+    /** Physical address of the chunk (contiguous). */
+    uint32_t physAddr;
+
+#if !defined(VBGL_PH_USE_MEMOBJ) || ARCH_BITS != 32
+    uint32_t uPadding1;
+#endif
+
+    /** Number of block of any kind. */
+    int32_t  cBlocks;
+    /** Number of free blocks. */
+    int32_t  cFreeBlocks;
+
+    /** Pointer to the next chunk. */
+    VBGLPHYSHEAPCHUNK  *pNext;
+    /** Pointer to the previous chunk. */
+    VBGLPHYSHEAPCHUNK  *pPrev;
+
+#if defined(VBGL_PH_USE_MEMOBJ)
+    /** The allocation handle. */
+    RTR0MEMOBJ          hMemObj;
+#endif
+
+#if ARCH_BITS == 64
+    /** Pad the size up to 64 bytes. */
+# ifdef VBGL_PH_USE_MEMOBJ
+    uintptr_t           auPadding2[2];
+# else
+    uintptr_t           auPadding2[3];
+# endif
+#endif
+};
+#if ARCH_BITS == 64
+AssertCompileSize(VBGLPHYSHEAPCHUNK, 64);
+#endif
+
+
+/**
+ * Debug function that dumps the heap.
+ */
+#ifndef VBGL_PH_DUMPHEAP
+# define dumpheap(pszWhere) do { } while (0)
+#else
+static void dumpheap(const char *pszWhere)
+{
+   VBGL_PH_DPRINTF(("VBGL_PH dump at '%s'\n", pszWhere));
+
+   VBGL_PH_DPRINTF(("Chunks:\n"));
+   for (VBGLPHYSHEAPCHUNK *pChunk = g_vbgldata.pChunkHead; pChunk; pChunk = pChunk->pNext)
+       VBGL_PH_DPRINTF(("%p: pNext = %p, pPrev = %p, sign = %08X, size = %8d, cBlocks = %8d, cFreeBlocks=%8d, phys = %08X\n",
+                        pChunk, pChunk->pNext, pChunk->pPrev, pChunk->u32Signature, pChunk->cbChunk,
+                        pChunk->cBlocks, pChunk->cFreeBlocks, pChunk->physAddr));
+
+   VBGL_PH_DPRINTF(("Allocated blocks:\n"));
+   for (VBGLPHYSHEAPBLOCK *pBlock = g_vbgldata.pBlockHead; pBlock; pBlock = pBlock->pNext)
+       VBGL_PH_DPRINTF(("%p: pNext = %p, pPrev = %p, size = %05x, sign = %08X, %s, pChunk = %p\n",
+                        pBlock, pBlock->pNext, pBlock->pPrev, pBlock->cbUser,
+                        pBlock->u32Signature,  pBlock->fAllocated ? "allocated" : "     free", pBlock->pChunk));
+
+   VBGL_PH_DPRINTF(("Free blocks:\n"));
+   for (VBGLPHYSHEAPFREEBLOCK *pBlock = g_vbgldata.pFreeHead; pBlock; pBlock = pBlock->pNextFree)
+       VBGL_PH_DPRINTF(("%p: pNextFree = %p, pPrevFree = %p, size = %05x, sign = %08X, pChunk = %p%s\n",
+                        pBlock, pBlock->pNextFree, pBlock->pPrevFree, pBlock->Core.cbUser,
+                        pBlock->Core.u32Signature, pBlock->Core.pChunk,
+                        !pBlock->Core.fAllocated ? "" : " !!allocated-block-on-freelist!!"));
+
+   VBGL_PH_DPRINTF(("VBGL_PH dump at '%s' done\n", pszWhere));
+}
+#endif
+
+
+/**
+ * Initialize a free block
+ */
+static void vbglPhysHeapInitFreeBlock(VBGLPHYSHEAPFREEBLOCK *pBlock, VBGLPHYSHEAPCHUNK *pChunk, uint32_t cbUser)
+{
+    Assert(pBlock != NULL);
+    Assert(pChunk != NULL);
+
+    pBlock->Core.u32Signature = VBGL_PH_BLOCKSIGNATURE;
+    pBlock->Core.cbUser       = cbUser;
+    pBlock->Core.fAllocated   = false;
+    pBlock->Core.pNext        = NULL;
+    pBlock->Core.pPrev        = NULL;
+    pBlock->Core.pChunk       = pChunk;
+    pBlock->pNextFree         = NULL;
+    pBlock->pPrevFree         = NULL;
+}
+
+
+/**
+ * Updates block statistics when a block is added.
+ */
+DECLINLINE(void) vbglPhysHeapStatsBlockAdded(VBGLPHYSHEAPBLOCK *pBlock)
+{
+    g_vbgldata.cBlocks      += 1;
+    pBlock->pChunk->cBlocks += 1;
+    AssertMsg((uint32_t)pBlock->pChunk->cBlocks <= pBlock->pChunk->cbChunk / sizeof(VBGLPHYSHEAPFREEBLOCK),
+              ("pChunk=%p: cbChunk=%#x cBlocks=%d\n", pBlock->pChunk, pBlock->pChunk->cbChunk, pBlock->pChunk->cBlocks));
+}
+
+
+/**
+ * Links @a pBlock onto the head of block list.
+ *
+ * This also update the per-chunk block counts.
+ */
+static void vbglPhysHeapInsertBlock(VBGLPHYSHEAPBLOCK *pBlock)
+{
+    AssertMsg(pBlock->pNext == NULL, ("pBlock->pNext = %p\n", pBlock->pNext));
+    AssertMsg(pBlock->pPrev == NULL, ("pBlock->pPrev = %p\n", pBlock->pPrev));
+
+    /* inserting to head of list */
+    VBGLPHYSHEAPBLOCK *pOldHead = g_vbgldata.pBlockHead;
+
+    pBlock->pNext = pOldHead;
+    pBlock->pPrev = NULL;
+
+    if (pOldHead)
+        pOldHead->pPrev = pBlock;
+    g_vbgldata.pBlockHead = pBlock;
+
+    /* Update the stats: */
+    vbglPhysHeapStatsBlockAdded(pBlock);
+}
+
+
+/**
+ * Links @a pBlock onto the block list after @a pInsertAfter.
+ *
+ * This also update the per-chunk block counts.
+ */
+static void vbglPhysHeapInsertBlockAfter(VBGLPHYSHEAPBLOCK *pBlock, VBGLPHYSHEAPBLOCK *pInsertAfter)
+{
+    AssertMsg(pBlock->pNext == NULL, ("pBlock->pNext = %p\n", pBlock->pNext));
+    AssertMsg(pBlock->pPrev == NULL, ("pBlock->pPrev = %p\n", pBlock->pPrev));
+
+    pBlock->pNext = pInsertAfter->pNext;
+    pBlock->pPrev = pInsertAfter;
+
+    if (pInsertAfter->pNext)
+        pInsertAfter->pNext->pPrev = pBlock;
+
+    pInsertAfter->pNext = pBlock;
+
+    /* Update the stats: */
+    vbglPhysHeapStatsBlockAdded(pBlock);
+}
+
+
+/**
+ * Unlinks @a pBlock from the block list.
+ *
+ * This also update the per-chunk block counts.
+ */
+static void vbglPhysHeapUnlinkBlock(VBGLPHYSHEAPBLOCK *pBlock)
+{
+    VBGLPHYSHEAPBLOCK *pOtherBlock = pBlock->pNext;
+    if (pOtherBlock)
+        pOtherBlock->pPrev = pBlock->pPrev;
+    /* else: this is tail of list but we do not maintain tails of block lists. so nothing to do. */
+
+    pOtherBlock = pBlock->pPrev;
+    if (pOtherBlock)
+        pOtherBlock->pNext = pBlock->pNext;
+    else
+    {
+        Assert(g_vbgldata.pBlockHead == pBlock);
+        g_vbgldata.pBlockHead = pBlock->pNext;
+    }
+
+    pBlock->pNext = NULL;
+    pBlock->pPrev = NULL;
+
+    /* Update the stats: */
+    g_vbgldata.cBlocks      -= 1;
+    pBlock->pChunk->cBlocks -= 1;
+    AssertMsg(pBlock->pChunk->cBlocks >= 0,
+              ("pChunk=%p: cbChunk=%#x cBlocks=%d\n", pBlock->pChunk, pBlock->pChunk->cbChunk, pBlock->pChunk->cBlocks));
+    Assert(g_vbgldata.cBlocks >= 0);
+}
+
+
+
+/**
+ * Updates statistics after adding a free block.
+ */
+DECLINLINE(void) vbglPhysHeapStatsFreeBlockAdded(VBGLPHYSHEAPFREEBLOCK *pBlock)
+{
+    g_vbgldata.cFreeBlocks           += 1;
+    pBlock->Core.pChunk->cFreeBlocks += 1;
+}
+
+
+/**
+ * Links @a pBlock onto head of the free chain.
+ *
+ * This is used during block freeing and when adding a new chunk.
+ *
+ * This also update the per-chunk block counts.
+ */
+static void vbglPhysHeapInsertFreeBlock(VBGLPHYSHEAPFREEBLOCK *pBlock)
+{
+    Assert(!pBlock->Core.fAllocated);
+    AssertMsg(pBlock->pNextFree == NULL, ("pBlock->pNextFree = %p\n", pBlock->pNextFree));
+    AssertMsg(pBlock->pPrevFree == NULL, ("pBlock->pPrevFree = %p\n", pBlock->pPrevFree));
+
+    /* inserting to head of list */
+    VBGLPHYSHEAPFREEBLOCK *pOldHead = g_vbgldata.pFreeHead;
+
+    pBlock->pNextFree = pOldHead;
+    pBlock->pPrevFree = NULL;
+
+    if (pOldHead)
+        pOldHead->pPrevFree = pBlock;
+    g_vbgldata.pFreeHead = pBlock;
+
+    /* Update the stats: */
+    vbglPhysHeapStatsFreeBlockAdded(pBlock);
+}
+
+
+/**
+ * Links @a pBlock after @a pInsertAfter.
+ *
+ * This is used when splitting a free block during allocation to preserve the
+ * place in the free list.
+ *
+ * This also update the per-chunk block counts.
+ */
+static void vbglPhysHeapInsertFreeBlockAfter(VBGLPHYSHEAPFREEBLOCK *pBlock, VBGLPHYSHEAPFREEBLOCK *pInsertAfter)
+{
+    Assert(!pBlock->Core.fAllocated);
+    AssertMsg(pBlock->pNextFree == NULL, ("pBlock->pNextFree = %p\n", pBlock->pNextFree));
+    AssertMsg(pBlock->pPrevFree == NULL, ("pBlock->pPrevFree = %p\n", pBlock->pPrevFree));
+
+    /* inserting after the tiven node */
+    pBlock->pNextFree = pInsertAfter->pNextFree;
+    pBlock->pPrevFree = pInsertAfter;
+
+    if (pInsertAfter->pNextFree)
+        pInsertAfter->pNextFree->pPrevFree = pBlock;
+
+    pInsertAfter->pNextFree = pBlock;
+
+    /* Update the stats: */
+    vbglPhysHeapStatsFreeBlockAdded(pBlock);
+}
+
+
+/**
+ * Unlinks @a pBlock from the free list.
+ *
+ * This also update the per-chunk block counts.
+ */
+static void vbglPhysHeapUnlinkFreeBlock(VBGLPHYSHEAPFREEBLOCK *pBlock)
+{
+    Assert(!pBlock->Core.fAllocated);
+
+    VBGLPHYSHEAPFREEBLOCK *pOtherBlock = pBlock->pNextFree;
+    if (pOtherBlock)
+        pOtherBlock->pPrevFree = pBlock->pPrevFree;
+    /* else: this is tail of list but we do not maintain tails of block lists. so nothing to do. */
+
+    pOtherBlock = pBlock->pPrevFree;
+    if (pOtherBlock)
+        pOtherBlock->pNextFree = pBlock->pNextFree;
+    else
+    {
+        Assert(g_vbgldata.pFreeHead == pBlock);
+        g_vbgldata.pFreeHead = pBlock->pNextFree;
+    }
+
+    pBlock->pNextFree = NULL;
+    pBlock->pPrevFree = NULL;
+
+    /* Update the stats: */
+    g_vbgldata.cFreeBlocks      -= 1;
+    pBlock->Core.pChunk->cFreeBlocks -= 1;
+    AssertMsg(pBlock->Core.pChunk->cFreeBlocks >= 0,
+              ("pChunk=%p: cbChunk=%#x cFreeBlocks=%d\n",
+               pBlock->Core.pChunk, pBlock->Core.pChunk->cbChunk, pBlock->Core.pChunk->cFreeBlocks));
+    Assert(g_vbgldata.cFreeBlocks >= 0);
+}
+
+
+/**
+ * Allocate another chunk and add it to the heap.
+ *
+ * @returns Pointer to the free block in the new chunk on success, NULL on
+ *          allocation failure.
+ * @param   cbMinBlock  The size of the user block we need this chunk for.
+ */
+static VBGLPHYSHEAPFREEBLOCK *vbglPhysHeapChunkAlloc(uint32_t cbMinBlock)
+{
+    RTCCPHYS            PhysAddr = NIL_RTHCPHYS;
+    VBGLPHYSHEAPCHUNK  *pChunk;
+    uint32_t            cbChunk;
+#ifdef VBGL_PH_USE_MEMOBJ
+    RTR0MEMOBJ          hMemObj = NIL_RTR0MEMOBJ;
+    int                 rc;
+#endif
+
+    VBGL_PH_DPRINTF(("Allocating new chunk for %#x byte allocation\n", cbMinBlock));
+    AssertReturn(cbMinBlock <= VBGL_PH_LARGEST_ALLOC_SIZE, NULL); /* paranoia */
+
+    /*
+     * Compute the size of the new chunk, rounding up to next chunk size,
+     * which must be power of 2.
+     *
+     * Note! Using VBGLPHYSHEAPFREEBLOCK here means the minimum block size is
+     *       8 or 16 bytes too high, but safer this way since cbMinBlock is
+     *       zero during the init code call.
+     */
+    Assert(RT_IS_POWER_OF_TWO(VBGL_PH_CHUNKSIZE));
+    cbChunk = cbMinBlock + sizeof(VBGLPHYSHEAPCHUNK) + sizeof(VBGLPHYSHEAPFREEBLOCK);
+    cbChunk = RT_ALIGN_32(cbChunk, VBGL_PH_CHUNKSIZE);
+
+    /*
+     * This function allocates physical contiguous memory below 4 GB.  This 4GB
+     * limitation stems from using a 32-bit OUT instruction to pass a block
+     * physical address to the host.
+     */
+#ifdef VBGL_PH_USE_MEMOBJ
+    rc = RTR0MemObjAllocCont(&hMemObj, cbChunk, false /*fExecutable*/);
+    pChunk = (VBGLPHYSHEAPCHUNK *)(RT_SUCCESS(rc) ? RTR0MemObjAddress(hMemObj) : NULL);
+#else
+    pChunk = (VBGLPHYSHEAPCHUNK *)RTMemContAlloc(&PhysAddr, cbChunk);
+#endif
+    if (!pChunk)
+    {
+        /* If the allocation fail, halv the size till and try again. */
+        uint32_t cbMinChunk = RT_MAX(cbMinBlock, PAGE_SIZE / 2) + sizeof(VBGLPHYSHEAPCHUNK) + sizeof(VBGLPHYSHEAPFREEBLOCK);
+        cbMinChunk = RT_ALIGN_32(cbMinChunk, PAGE_SIZE);
+        if (cbChunk > cbMinChunk)
+            do
+            {
+                cbChunk >>= 2;
+                cbChunk = RT_ALIGN_32(cbChunk, PAGE_SIZE);
+#ifdef VBGL_PH_USE_MEMOBJ
+                rc = RTR0MemObjAllocCont(&hMemObj, cbChunk, false /*fExecutable*/);
+                pChunk = (VBGLPHYSHEAPCHUNK *)(RT_SUCCESS(rc) ? RTR0MemObjAddress(hMemObj) : NULL);
+#else
+                pChunk = (VBGLPHYSHEAPCHUNK *)RTMemContAlloc(&PhysAddr, cbChunk);
+#endif
+            } while (!pChunk && cbChunk > cbMinChunk);
+    }
+    if (pChunk)
+    {
+        VBGLPHYSHEAPCHUNK     *pOldHeadChunk;
+        VBGLPHYSHEAPFREEBLOCK *pBlock;
+        AssertRelease(PhysAddr < _4G && PhysAddr + cbChunk <= _4G);
+
+        /*
+         * Init the new chunk.
+         */
+        pChunk->u32Signature     = VBGL_PH_CHUNKSIGNATURE;
+        pChunk->cbChunk          = cbChunk;
+        pChunk->physAddr         = (uint32_t)PhysAddr;
+        pChunk->cBlocks          = 0;
+        pChunk->cFreeBlocks      = 0;
+        pChunk->pNext            = NULL;
+        pChunk->pPrev            = NULL;
+#ifdef VBGL_PH_USE_MEMOBJ
+        pChunk->hMemObj          = hMemObj;
+#endif
+
+        /* Initialize the padding too: */
+#if !defined(VBGL_PH_USE_MEMOBJ) || ARCH_BITS != 32
+        pChunk->uPadding1        = UINT32_C(0xADDCAAA1);
+#endif
+#if ARCH_BITS == 64
+        pChunk->auPadding2[0]    = UINT64_C(0xADDCAAA3ADDCAAA2);
+        pChunk->auPadding2[1]    = UINT64_C(0xADDCAAA5ADDCAAA4);
+# ifndef VBGL_PH_USE_MEMOBJ
+        pChunk->auPadding2[2]    = UINT64_C(0xADDCAAA7ADDCAAA6);
+# endif
+#endif
+
+        /*
+         * Initialize the free block, which now occupies entire chunk.
+         */
+        pBlock = (VBGLPHYSHEAPFREEBLOCK *)(pChunk + 1);
+        vbglPhysHeapInitFreeBlock(pBlock, pChunk, cbChunk - sizeof(VBGLPHYSHEAPCHUNK) - sizeof(VBGLPHYSHEAPBLOCK));
+        vbglPhysHeapInsertBlock(&pBlock->Core);
+        vbglPhysHeapInsertFreeBlock(pBlock);
+
+        /*
+         * Add the chunk to the list.
+         */
+        pOldHeadChunk = g_vbgldata.pChunkHead;
+        pChunk->pNext = pOldHeadChunk;
+        if (pOldHeadChunk)
+            pOldHeadChunk->pPrev = pChunk;
+        g_vbgldata.pChunkHead    = pChunk;
+
+        VBGL_PH_DPRINTF(("Allocated chunk %p LB %#x, block %p LB %#x\n", pChunk, cbChunk, pBlock, pBlock->Core.cbUser));
+        return pBlock;
+    }
+    LogRel(("vbglPhysHeapChunkAlloc: failed to alloc %u (%#x) contiguous bytes.\n", cbChunk, cbChunk));
+    return NULL;
+}
+
+
+/**
+ * Deletes a chunk: Unlinking all its blocks and freeing its memory.
+ */
+static void vbglPhysHeapChunkDelete(VBGLPHYSHEAPCHUNK *pChunk)
+{
+    uintptr_t uEnd, uCur;
+    Assert(pChunk != NULL);
+    AssertMsg(pChunk->u32Signature == VBGL_PH_CHUNKSIGNATURE, ("pChunk->u32Signature = %08X\n", pChunk->u32Signature));
+
+    VBGL_PH_DPRINTF(("Deleting chunk %p size %x\n", pChunk, pChunk->cbChunk));
+
+    /*
+     * First scan the chunk and unlink all blocks from the lists.
+     *
+     * Note! We could do this by finding the first and last block list entries
+     *       and just drop the whole chain relating to this chunk, rather than
+     *       doing it one by one.  But doing it one by one is simpler and will
+     *       continue to work if the block list ends in an unsorted state.
+     */
+    uEnd = (uintptr_t)pChunk + pChunk->cbChunk;
+    uCur = (uintptr_t)(pChunk + 1);
+
+    while (uCur < uEnd)
+    {
+        VBGLPHYSHEAPBLOCK *pBlock = (VBGLPHYSHEAPBLOCK *)uCur;
+        Assert(pBlock->u32Signature == VBGL_PH_BLOCKSIGNATURE);
+        Assert(pBlock->pChunk == pChunk);
+
+        uCur += pBlock->cbUser + sizeof(VBGLPHYSHEAPBLOCK);
+        Assert(uCur == (uintptr_t)pBlock->pNext || uCur >= uEnd);
+
+        if (!pBlock->fAllocated)
+            vbglPhysHeapUnlinkFreeBlock((VBGLPHYSHEAPFREEBLOCK *)pBlock);
+        vbglPhysHeapUnlinkBlock(pBlock);
+    }
+
+    AssertMsg(uCur == uEnd, ("uCur = %p, uEnd = %p, pChunk->cbChunk = %08X\n", uCur, uEnd, pChunk->cbChunk));
+
+    /*
+     * Unlink the chunk from the chunk list.
+     */
+    if (pChunk->pNext)
+        pChunk->pNext->pPrev = pChunk->pPrev;
+    /* else: we do not maintain tail pointer. */
+
+    if (pChunk->pPrev)
+        pChunk->pPrev->pNext = pChunk->pNext;
+    else
+    {
+        Assert(g_vbgldata.pChunkHead == pChunk);
+        g_vbgldata.pChunkHead = pChunk->pNext;
+    }
+
+    /*
+     * Finally, free the chunk memory.
+     */
+#ifdef VBGL_PH_USE_MEMOBJ
+    RTR0MemObjFree(pChunk->hMemObj, true /*fFreeMappings*/);
+#else
+    RTMemContFree(pChunk, pChunk->cbChunk);
+#endif
+}
+
+
+DECLR0VBGL(void *) VbglR0PhysHeapAlloc(uint32_t cb)
+{
+    VBGLPHYSHEAPFREEBLOCK  *pBlock;
+    VBGLPHYSHEAPFREEBLOCK  *pIter;
+    int32_t                 cLeft;
+#ifdef VBGL_PH_STOP_SEARCH_AT_EXCESS
+    uint32_t                cbAlwaysSplit;
+#endif
+    int                     rc;
+
+    /*
+     * Make sure we don't allocate anything too small to turn into a free node
+     * and align the size to prevent pointer misalignment and whatnot.
+     */
+    cb = RT_MAX(cb, VBGL_PH_SMALLEST_ALLOC_SIZE);
+    cb = RT_ALIGN_32(cb, VBGL_PH_ALLOC_ALIGN);
+    AssertCompile(VBGL_PH_ALLOC_ALIGN <= sizeof(pBlock->Core));
+
+    rc = RTSemFastMutexRequest(g_vbgldata.hMtxHeap);
+    AssertRCReturn(rc, NULL);
+
+    dumpheap("pre alloc");
+
+    /*
+     * Search the free list.  We do this in linear fashion as we don't expect
+     * there to be many blocks in the heap.
+     */
+#ifdef VBGL_PH_STOP_SEARCH_AT_EXCESS
+    cbAlwaysSplit = cb + VBGL_PH_STOP_SEARCH_AT_EXCESS;
+#endif
+    cLeft         = VBGL_PH_MAX_FREE_SEARCH;
+    pBlock        = NULL;
+    if (cb <= PAGE_SIZE / 4 * 3)
+    {
+        /* Smaller than 3/4 page:  Prefer a free block that can keep the request within a single page,
+           so HGCM processing in VMMDev can use page locks instead of several reads and writes. */
+        VBGLPHYSHEAPFREEBLOCK *pFallback = NULL;
+        for (pIter = g_vbgldata.pFreeHead; pIter != NULL; pIter = pIter->pNextFree, cLeft--)
+        {
+            AssertBreak(pIter->Core.u32Signature == VBGL_PH_BLOCKSIGNATURE);
+            if (pIter->Core.cbUser >= cb)
+            {
+                if (pIter->Core.cbUser == cb)
+                {
+                    if (PAGE_SIZE - ((uintptr_t)(pIter + 1) & PAGE_OFFSET_MASK) >= cb)
+                    {
+                        pBlock = pIter;
+                        break;
+                    }
+                    pFallback = pIter;
+                }
+                else
+                {
+                    if (!pFallback || pIter->Core.cbUser < pFallback->Core.cbUser)
+                        pFallback = pIter;
+                    if (PAGE_SIZE - ((uintptr_t)(pIter + 1) & PAGE_OFFSET_MASK) >= cb)
+                    {
+                        if (!pBlock || pIter->Core.cbUser < pBlock->Core.cbUser)
+                            pBlock = pIter;
+#ifdef VBGL_PH_STOP_SEARCH_AT_EXCESS
+                        else if (pIter->Core.cbUser >= cbAlwaysSplit)
+                        {
+                            pBlock = pIter;
+                            break;
+                        }
+#endif
+                    }
+                }
+
+                if (cLeft > 0)
+                { /* likely */ }
+                else
+                    break;
+            }
+        }
+
+        if (!pBlock)
+            pBlock = pFallback;
+    }
+    else
+    {
+        /* Large than 3/4 page:  Find closest free list match. */
+        for (pIter = g_vbgldata.pFreeHead; pIter != NULL; pIter = pIter->pNextFree, cLeft--)
+        {
+            AssertBreak(pIter->Core.u32Signature == VBGL_PH_BLOCKSIGNATURE);
+            if (pIter->Core.cbUser >= cb)
+            {
+                if (pIter->Core.cbUser == cb)
+                {
+                    /* Exact match - we're done! */
+                    pBlock = pIter;
+                    break;
+                }
+
+#ifdef VBGL_PH_STOP_SEARCH_AT_EXCESS
+                if (pIter->Core.cbUser >= cbAlwaysSplit)
+                {
+                    /* Really big block - no point continue searching! */
+                    pBlock = pIter;
+                    break;
+                }
+#endif
+                /* Looking for a free block with nearest size. */
+                if (!pBlock || pIter->Core.cbUser < pBlock->Core.cbUser)
+                    pBlock = pIter;
+
+                if (cLeft > 0)
+                { /* likely */ }
+                else
+                    break;
+            }
+        }
+    }
+
+    if (!pBlock)
+    {
+        /* No free blocks, allocate a new chunk, the only free block of the
+           chunk will be returned. */
+        pBlock = vbglPhysHeapChunkAlloc(cb);
+    }
+
+    if (pBlock)
+    {
+        /* We have a free block, either found or allocated. */
+        AssertMsg(pBlock->Core.u32Signature == VBGL_PH_BLOCKSIGNATURE,
+                  ("pBlock = %p, pBlock->u32Signature = %08X\n", pBlock, pBlock->Core.u32Signature));
+        AssertMsg(!pBlock->Core.fAllocated, ("pBlock = %p\n", pBlock));
+
+        /*
+         * If the block is too large, split off a free block with the unused space.
+         *
+         * We do this before unlinking the block so we can preserve the location
+         * in the free list.
+         *
+         * Note! We cannot split off and return the tail end here, because that may
+         *       violate the same page requirements for requests smaller than 3/4 page.
+         */
+        AssertCompile(VBGL_PH_MIN_SPLIT_FREE_BLOCK >= sizeof(*pBlock) - sizeof(pBlock->Core));
+        if (pBlock->Core.cbUser >= sizeof(VBGLPHYSHEAPBLOCK) * 2 + VBGL_PH_MIN_SPLIT_FREE_BLOCK + cb)
+        {
+            pIter = (VBGLPHYSHEAPFREEBLOCK *)((uintptr_t)(&pBlock->Core + 1) + cb);
+            vbglPhysHeapInitFreeBlock(pIter, pBlock->Core.pChunk, pBlock->Core.cbUser - cb - sizeof(VBGLPHYSHEAPBLOCK));
+
+            pBlock->Core.cbUser = cb;
+
+            /* Insert the new 'pIter' block after the 'pBlock' in the block list
+               and in the free list. */
+            vbglPhysHeapInsertBlockAfter(&pIter->Core, &pBlock->Core);
+            vbglPhysHeapInsertFreeBlockAfter(pIter, pBlock);
+        }
+
+        /*
+         * Unlink the block from the free list and mark it as allocated.
+         */
+        vbglPhysHeapUnlinkFreeBlock(pBlock);
+        pBlock->Core.fAllocated = true;
+
+        dumpheap("post alloc");
+
+        /*
+         * Return success.
+         */
+        rc = RTSemFastMutexRelease(g_vbgldata.hMtxHeap);
+
+        VBGL_PH_DPRINTF(("VbglR0PhysHeapAlloc: returns %p size %x\n", pBlock + 1, pBlock->Core.cbUser));
+        return &pBlock->Core + 1;
+    }
+
+    /*
+     * Return failure.
+     */
+    rc = RTSemFastMutexRelease(g_vbgldata.hMtxHeap);
+    AssertRC(rc);
+
+    VBGL_PH_DPRINTF(("VbglR0PhysHeapAlloc: returns NULL (requested %#x bytes)\n", cb));
+    return NULL;
+}
+
+
+DECLR0VBGL(uint32_t) VbglR0PhysHeapGetPhysAddr(void *pv)
+{
+    /*
+     * Validate the incoming pointer.
+     */
+    if (pv != NULL)
+    {
+        VBGLPHYSHEAPBLOCK *pBlock = (VBGLPHYSHEAPBLOCK *)pv - 1;
+        if (   pBlock->u32Signature == VBGL_PH_BLOCKSIGNATURE
+            && pBlock->fAllocated)
+        {
+            /*
+             * Calculate and return its physical address.
+             */
+            VBGLPHYSHEAPCHUNK  *pChunk = pBlock->pChunk;
+            return pChunk->physAddr + (uint32_t)((uintptr_t)pv - (uintptr_t)pChunk);
+        }
+
+        AssertMsgFailed(("Use after free or corrupt pointer variable: pv=%p pBlock=%p: u32Signature=%#x cb=%#x fAllocated=%d\n",
+                         pv, pBlock, pBlock->u32Signature, pBlock->cbUser, pBlock->fAllocated));
+    }
+    else
+        AssertMsgFailed(("Unexpected NULL pointer\n"));
+    return 0;
+}
+
+
+DECLR0VBGL(void) VbglR0PhysHeapFree(void *pv)
+{
+    if (pv != NULL)
+    {
+        VBGLPHYSHEAPFREEBLOCK *pBlock;
+
+        int rc = RTSemFastMutexRequest(g_vbgldata.hMtxHeap);
+        AssertRCReturnVoid(rc);
+
+        dumpheap("pre free");
+
+        /*
+         * Validate the block header.
+         */
+        pBlock = (VBGLPHYSHEAPFREEBLOCK *)((VBGLPHYSHEAPBLOCK *)pv - 1);
+        if (   pBlock->Core.u32Signature == VBGL_PH_BLOCKSIGNATURE
+            && pBlock->Core.fAllocated
+            && pBlock->Core.cbUser >= VBGL_PH_SMALLEST_ALLOC_SIZE)
+        {
+            VBGLPHYSHEAPCHUNK *pChunk;
+            VBGLPHYSHEAPBLOCK *pNeighbour;
+
+            /*
+             * Change the block status to freeed.
+             */
+            VBGL_PH_DPRINTF(("VbglR0PhysHeapFree: %p size %#x\n", pv, pBlock->Core.cbUser));
+
+            pBlock->Core.fAllocated = false;
+            pBlock->pNextFree = pBlock->pPrevFree = NULL;
+            vbglPhysHeapInsertFreeBlock(pBlock);
+
+            dumpheap("post insert");
+
+            /*
+             * Check if the block after this one is also free and we can merge it into this one.
+             */
+            pChunk = pBlock->Core.pChunk;
+
+            pNeighbour = pBlock->Core.pNext;
+            if (   pNeighbour
+                && !pNeighbour->fAllocated
+                && pNeighbour->pChunk == pChunk)
+            {
+                Assert((uintptr_t)pBlock + sizeof(pBlock->Core) + pBlock->Core.cbUser == (uintptr_t)pNeighbour);
+
+                /* Adjust size of current memory block */
+                pBlock->Core.cbUser += pNeighbour->cbUser + sizeof(VBGLPHYSHEAPBLOCK);
+
+                /* Unlink the following node and invalid it. */
+                vbglPhysHeapUnlinkFreeBlock((VBGLPHYSHEAPFREEBLOCK *)pNeighbour);
+                vbglPhysHeapUnlinkBlock(pNeighbour);
+
+                pNeighbour->u32Signature = ~VBGL_PH_BLOCKSIGNATURE;
+                pNeighbour->cbUser       = UINT32_MAX / 4;
+
+                dumpheap("post merge after");
+            }
+
+            /*
+             * Same check for the block before us.  This invalidates pBlock.
+             */
+            pNeighbour = pBlock->Core.pPrev;
+            if (   pNeighbour
+                && !pNeighbour->fAllocated
+                && pNeighbour->pChunk == pChunk)
+            {
+                Assert((uintptr_t)pNeighbour + sizeof(*pNeighbour) + pNeighbour->cbUser == (uintptr_t)pBlock);
+
+                /* Adjust size of the block before us */
+                pNeighbour->cbUser += pBlock->Core.cbUser + sizeof(VBGLPHYSHEAPBLOCK);
+
+                /* Unlink this node and invalid it. */
+                vbglPhysHeapUnlinkFreeBlock(pBlock);
+                vbglPhysHeapUnlinkBlock(&pBlock->Core);
+
+                pBlock->Core.u32Signature = ~VBGL_PH_BLOCKSIGNATURE;
+                pBlock->Core.cbUser       = UINT32_MAX / 8;
+
+                pBlock = NULL; /* invalid */
+
+                dumpheap("post merge before");
+            }
+
+            /*
+             * If this chunk is now completely unused, delete it if there are
+             * more completely free ones.
+             */
+            if (   pChunk->cFreeBlocks == pChunk->cBlocks
+                && (pChunk->pPrev || pChunk->pNext))
+            {
+                VBGLPHYSHEAPCHUNK *pCurChunk;
+                uint32_t           cUnusedChunks = 0;
+                for (pCurChunk = g_vbgldata.pChunkHead; pCurChunk; pCurChunk = pCurChunk->pNext)
+                {
+                    AssertBreak(pCurChunk->u32Signature == VBGL_PH_CHUNKSIGNATURE);
+                    if (pCurChunk->cFreeBlocks == pCurChunk->cBlocks)
+                    {
+                        cUnusedChunks++;
+                        if (cUnusedChunks > 1)
+                        {
+                            /* Delete current chunk, it will also unlink all free blocks
+                             * remaining in the chunk from the free list, so the pBlock
+                             * will also be invalid after this.
+                             */
+                            vbglPhysHeapChunkDelete(pChunk);
+                            pBlock = NULL;      /* invalid */
+                            pChunk = NULL;
+                            pNeighbour = NULL;
+                            break;
+                        }
+                    }
+                }
+            }
+
+            dumpheap("post free");
+        }
+        else
+            AssertMsgFailed(("pBlock: %p: u32Signature=%#x cb=%#x fAllocated=%d - double free?\n",
+                             pBlock, pBlock->Core.u32Signature, pBlock->Core.cbUser, pBlock->Core.fAllocated));
+
+        rc = RTSemFastMutexRelease(g_vbgldata.hMtxHeap);
+        AssertRC(rc);
+    }
+}
+
+#ifdef IN_TESTCASE /* For the testcase only */
+
+/**
+ * Returns the sum of all free heap blocks.
+ *
+ * This is the amount of memory you can theoretically allocate if you do
+ * allocations exactly matching the free blocks.
+ *
+ * @returns The size of the free blocks.
+ * @returns 0 if heap was safely detected as being bad.
+ */
+DECLVBGL(size_t) VbglR0PhysHeapGetFreeSize(void)
+{
+    int rc = RTSemFastMutexRequest(g_vbgldata.hMtxHeap);
+    AssertRCReturn(rc, 0);
+
+    size_t cbTotal = 0;
+    for (VBGLPHYSHEAPFREEBLOCK *pCurBlock = g_vbgldata.pFreeHead; pCurBlock; pCurBlock = pCurBlock->pNextFree)
+    {
+        Assert(pCurBlock->Core.u32Signature == VBGL_PH_BLOCKSIGNATURE);
+        Assert(!pCurBlock->Core.fAllocated);
+        cbTotal += pCurBlock->Core.cbUser;
+    }
+
+    RTSemFastMutexRelease(g_vbgldata.hMtxHeap);
+    return cbTotal;
+}
+
+
+/**
+ * Checks the heap, caller responsible for locking.
+ *
+ * @returns VINF_SUCCESS if okay, error status if not.
+ * @param   pErrInfo    Where to return more error details, optional.
+ */
+static int vbglR0PhysHeapCheckLocked(PRTERRINFO pErrInfo)
+{
+    /*
+     * Scan the blocks in each chunk, walking the block list in parallel.
+     */
+    const VBGLPHYSHEAPBLOCK *pPrevBlockListEntry = NULL;
+    const VBGLPHYSHEAPBLOCK *pCurBlockListEntry  = g_vbgldata.pBlockHead;
+    unsigned                 acTotalBlocks[2]    = { 0, 0 };
+    for (VBGLPHYSHEAPCHUNK *pCurChunk = g_vbgldata.pChunkHead, *pPrevChunk = NULL; pCurChunk; pCurChunk = pCurChunk->pNext)
+    {
+        AssertReturn(pCurChunk->u32Signature == VBGL_PH_CHUNKSIGNATURE,
+                     RTErrInfoSetF(pErrInfo, VERR_INVALID_MAGIC, "pCurChunk=%p: magic=%#x", pCurChunk, pCurChunk->u32Signature));
+        AssertReturn(pCurChunk->pPrev == pPrevChunk,
+                     RTErrInfoSetF(pErrInfo, VERR_INTERNAL_ERROR_2,
+                                   "pCurChunk=%p: pPrev=%p, expected %p", pCurChunk, pCurChunk->pPrev, pPrevChunk));
+
+        const VBGLPHYSHEAPBLOCK *pCurBlock   = (const VBGLPHYSHEAPBLOCK *)(pCurChunk + 1);
+        uintptr_t const          uEnd        = (uintptr_t)pCurChunk + pCurChunk->cbChunk;
+        unsigned                 acBlocks[2] = { 0, 0 };
+        while ((uintptr_t)pCurBlock < uEnd)
+        {
+            AssertReturn(pCurBlock->u32Signature == VBGL_PH_BLOCKSIGNATURE,
+                         RTErrInfoSetF(pErrInfo, VERR_INVALID_MAGIC,
+                                       "pCurBlock=%p: magic=%#x", pCurBlock, pCurBlock->u32Signature));
+            AssertReturn(pCurBlock->pChunk == pCurChunk,
+                         RTErrInfoSetF(pErrInfo, VERR_INTERNAL_ERROR_2,
+                                       "pCurBlock=%p: pChunk=%p, expected %p", pCurBlock, pCurBlock->pChunk, pCurChunk));
+            AssertReturn(   pCurBlock->cbUser >= VBGL_PH_SMALLEST_ALLOC_SIZE
+                         && pCurBlock->cbUser <= VBGL_PH_LARGEST_ALLOC_SIZE
+                         && RT_ALIGN_32(pCurBlock->cbUser, VBGL_PH_ALLOC_ALIGN) == pCurBlock->cbUser,
+                         RTErrInfoSetF(pErrInfo, VERR_INTERNAL_ERROR_3,
+                                       "pCurBlock=%p: cbUser=%#x", pCurBlock, pCurBlock->cbUser));
+            AssertReturn(pCurBlock == pCurBlockListEntry,
+                         RTErrInfoSetF(pErrInfo, VERR_INTERNAL_ERROR_4,
+                                       "pCurChunk=%p: pCurBlock=%p, pCurBlockListEntry=%p\n",
+                                       pCurChunk, pCurBlock, pCurBlockListEntry));
+            AssertReturn(pCurBlock->pPrev == pPrevBlockListEntry,
+                         RTErrInfoSetF(pErrInfo, VERR_INTERNAL_ERROR_5,
+                                       "pCurChunk=%p: pCurBlock->pPrev=%p, pPrevBlockListEntry=%p\n",
+                                       pCurChunk, pCurBlock->pPrev, pPrevBlockListEntry));
+
+            acBlocks[pCurBlock->fAllocated] += 1;
+
+            /* advance */
+            pPrevBlockListEntry = pCurBlock;
+            pCurBlockListEntry  = pCurBlock->pNext;
+            pCurBlock = (const VBGLPHYSHEAPBLOCK *)((uintptr_t)(pCurBlock + 1) + pCurBlock->cbUser);
+        }
+        AssertReturn((uintptr_t)pCurBlock == uEnd,
+                     RTErrInfoSetF(pErrInfo, VERR_INTERNAL_ERROR_4,
+                                   "pCurBlock=%p uEnd=%p", pCurBlock, uEnd));
+
+        acTotalBlocks[1] += acBlocks[1];
+        AssertReturn(acBlocks[0] + acBlocks[1] == (uint32_t)pCurChunk->cBlocks,
+                     RTErrInfoSetF(pErrInfo, VERR_INTERNAL_ERROR_4,
+                                   "pCurChunk=%p: cBlocks=%u, expected %u",
+                                   pCurChunk, pCurChunk->cBlocks, acBlocks[0] + acBlocks[1]));
+
+        acTotalBlocks[0] += acBlocks[0];
+        AssertReturn(acBlocks[0] == (uint32_t)pCurChunk->cFreeBlocks,
+                     RTErrInfoSetF(pErrInfo, VERR_INTERNAL_ERROR_5,
+                                   "pCurChunk=%p: cFreeBlocks=%u, expected %u",
+                                   pCurChunk, pCurChunk->cFreeBlocks, acBlocks[0]));
+
+        pPrevChunk = pCurChunk;
+    }
+
+    AssertReturn(acTotalBlocks[0] == (uint32_t)g_vbgldata.cFreeBlocks,
+                 RTErrInfoSetF(pErrInfo, VERR_INTERNAL_ERROR,
+                               "g_vbgldata.cFreeBlocks=%u, expected %u", g_vbgldata.cFreeBlocks, acTotalBlocks[0]));
+    AssertReturn(acTotalBlocks[0] + acTotalBlocks[1] == (uint32_t)g_vbgldata.cBlocks,
+                 RTErrInfoSetF(pErrInfo, VERR_INTERNAL_ERROR,
+                               "g_vbgldata.cBlocks=%u, expected %u", g_vbgldata.cBlocks, acTotalBlocks[0] + acTotalBlocks[1]));
+
+    /*
+     * Check that the free list contains the same number of blocks as we
+     * encountered during the above scan.
+     */
+    {
+        unsigned cFreeListBlocks = 0;
+        for (const VBGLPHYSHEAPFREEBLOCK *pCurBlock = g_vbgldata.pFreeHead, *pPrevBlock = NULL;
+             pCurBlock;
+             pCurBlock = pCurBlock->pNextFree)
+        {
+            AssertReturn(pCurBlock->Core.u32Signature == VBGL_PH_BLOCKSIGNATURE,
+                         RTErrInfoSetF(pErrInfo, VERR_INVALID_MAGIC,
+                                       "pCurBlock=%p/free: magic=%#x", pCurBlock, pCurBlock->Core.u32Signature));
+            AssertReturn(pCurBlock->pPrevFree == pPrevBlock,
+                         RTErrInfoSetF(pErrInfo, VERR_INTERNAL_ERROR_2,
+                                       "pCurBlock=%p/free: pPrev=%p, expected %p", pCurBlock, pCurBlock->pPrevFree, pPrevBlock));
+            AssertReturn(pCurBlock->Core.pChunk->u32Signature == VBGL_PH_CHUNKSIGNATURE,
+                         RTErrInfoSetF(pErrInfo, VERR_INVALID_MAGIC, "pCurBlock=%p/free: chunk (%p) magic=%#x",
+                                       pCurBlock, pCurBlock->Core.pChunk, pCurBlock->Core.pChunk->u32Signature));
+            cFreeListBlocks++;
+            pPrevBlock = pCurBlock;
+        }
+
+        AssertReturn(cFreeListBlocks == acTotalBlocks[0],
+                     RTErrInfoSetF(pErrInfo, VERR_INTERNAL_ERROR_3,
+                                   "Found %u in free list, expected %u", cFreeListBlocks, acTotalBlocks[0]));
+    }
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Performs a heap check.
+ *
+ * @returns Problem description on failure, NULL on success.
+ * @param   pErrInfo    Where to return more error details, optional.
+ */
+DECLVBGL(int) VbglR0PhysHeapCheck(PRTERRINFO pErrInfo)
+{
+    int rc = RTSemFastMutexRequest(g_vbgldata.hMtxHeap);
+    AssertRCReturn(rc, 0);
+
+    rc = vbglR0PhysHeapCheckLocked(pErrInfo);
+
+    RTSemFastMutexRelease(g_vbgldata.hMtxHeap);
+    return rc;
+}
+
+#endif /* IN_TESTCASE */
+
+DECLR0VBGL(int) VbglR0PhysHeapInit(void)
+{
+    g_vbgldata.hMtxHeap = NIL_RTSEMFASTMUTEX;
+
+    /* Allocate the first chunk of the heap. */
+    VBGLPHYSHEAPFREEBLOCK *pBlock = vbglPhysHeapChunkAlloc(0);
+    if (pBlock)
+        return RTSemFastMutexCreate(&g_vbgldata.hMtxHeap);
+    return VERR_NO_CONT_MEMORY;
+}
+
+DECLR0VBGL(void) VbglR0PhysHeapTerminate(void)
+{
+    while (g_vbgldata.pChunkHead)
+        vbglPhysHeapChunkDelete(g_vbgldata.pChunkHead);
+
+    RTSemFastMutexDestroy(g_vbgldata.hMtxHeap);
+    g_vbgldata.hMtxHeap = NIL_RTSEMFASTMUTEX;
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibSharedFolders.c b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibSharedFolders.c
new file mode 100644
index 00000000..02a5c470
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibSharedFolders.c
@@ -0,0 +1,716 @@
+/* $Id: VBoxGuestR0LibSharedFolders.c $ */
+/** @file
+ * VBoxGuestR0LibSharedFolders - Ring 0 Shared Folders calls.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#define LOG_GROUP LOG_GROUP_SHARED_FOLDERS
+#include "VBoxGuestR0LibInternal.h"
+#include <VBox/VBoxGuestLibSharedFolders.h>
+#include <VBox/log.h>
+#include <iprt/err.h>
+#include <iprt/time.h>
+#include <iprt/mem.h>
+#include <iprt/path.h>
+#include <iprt/string.h>
+
+#ifdef VBGL_VBOXGUEST
+# error "This file shouldn't be part of the VBoxGuestR0LibBase library that is linked into VBoxGuest.  It's client code."
+#endif
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+#define VBOX_INIT_CALL(a, b, c) \
+    LogFunc(("%s, idClient=%d\n", "SHFL_FN_" # b, (c)->idClient)); \
+    VBGL_HGCM_HDR_INIT(a, (c)->idClient, SHFL_FN_##b, SHFL_CPARMS_##b); \
+    (a)->fInterruptible = false /* Currently we do like nfs with -o hard (default). */
+
+#define VBOX_INIT_CALL_EX(a, b, c, a_cbReq) \
+    LogFunc(("%s, idClient=%d\n", "SHFL_FN_" # b, (c)->idClient)); \
+    VBGL_HGCM_HDR_INIT_EX(a, (c)->idClient, SHFL_FN_##b, SHFL_CPARMS_##b, a_cbReq); \
+    (a)->fInterruptible = false /* Currently we do like nfs with -o hard (default). */
+
+
+
+DECLVBGL(int) VbglR0SfInit(void)
+{
+    return VbglR0InitClient();
+}
+
+DECLVBGL(void) VbglR0SfTerm(void)
+{
+    VbglR0TerminateClient();
+}
+
+DECLVBGL(int) VbglR0SfConnect(PVBGLSFCLIENT pClient)
+{
+    int rc = VbglR0HGCMConnect(&pClient->handle, "VBoxSharedFolders", &pClient->idClient);
+    if (RT_SUCCESS(rc))
+        LogFunc(("idClient=%d\n", pClient->idClient));
+    else
+        LogFunc(("VbglR0HGCMConnect failed -> rc=%Rrc\n", rc));
+    return rc;
+}
+
+DECLVBGL(void) VbglR0SfDisconnect(PVBGLSFCLIENT pClient)
+{
+    int rc;
+    LogFunc(("u32ClientID=%d\n", pClient->idClient));
+    if (pClient->handle == NULL)
+        return;                 /* not connected */
+
+    rc = VbglR0HGCMDisconnect(pClient->handle, pClient->idClient);
+    NOREF(rc);
+/*    Log(("VBOXSF: VbglR0SfDisconnect: VbglR0HGCMDisconnect -> %#x\n", rc)); */
+    pClient->idClient = 0;
+    pClient->handle   = NULL;
+    return;
+}
+
+#if !defined(RT_OS_LINUX)
+
+# ifndef RT_OS_WINDOWS
+
+DECLVBGL(int) VbglR0SfSetUtf8(PVBGLSFCLIENT pClient)
+{
+    int rc;
+    VBGLIOCHGCMCALL callInfo;
+
+    VBOX_INIT_CALL(&callInfo, SET_UTF8, pClient);
+    rc = VbglR0HGCMCall(pClient->handle, &callInfo, sizeof(callInfo));
+/*    Log(("VBOXSF: VbglR0SfSetUtf8: VbglR0HGCMCall rc = %#x, result = %#x\n", rc, data.callInfo.Hdr.rc)); */
+    return rc;
+}
+
+# endif /* !RT_OS_WINDOWS */
+
+/** @name       Deprecated VBGL shared folder helpers.
+ *
+ * @deprecated  These are all use the slow VbglR0HGCMCall interface, that
+ *              basically treat ring-0 and user land callers much the same.
+ *              Since 6.0 there is VbglR0HGCMFastCall() that does not bother with
+ *              repacking the request and locking/duplicating parameter buffers,
+ *              but just passes it along to the host and handles the waiting.
+ *              Also new in 6.0 is embedded buffers which saves a bit time on
+ *              guest and host by embedding parameter buffers into the request.
+ *
+ * @{
+ */
+
+DECLVBGL(int) VbglR0SfQueryMappings(PVBGLSFCLIENT pClient, SHFLMAPPING paMappings[], uint32_t *pcMappings)
+{
+    int rc;
+    VBoxSFQueryMappings data;
+
+    VBOX_INIT_CALL(&data.callInfo, QUERY_MAPPINGS, pClient);
+
+    data.flags.type                      = VMMDevHGCMParmType_32bit;
+    data.flags.u.value32                 = SHFL_MF_UCS2;
+
+    data.numberOfMappings.type           = VMMDevHGCMParmType_32bit;
+    data.numberOfMappings.u.value32      = *pcMappings;
+
+    data.mappings.type                   = VMMDevHGCMParmType_LinAddr;
+    data.mappings.u.Pointer.size         = sizeof(SHFLMAPPING) * *pcMappings;
+    data.mappings.u.Pointer.u.linearAddr = (uintptr_t)&paMappings[0];
+
+/*    Log(("VBOXSF: in ifs difference %d\n", (char *)&data.flags.type - (char *)&data.callInfo.cParms)); */
+    rc = VbglR0HGCMCall(pClient->handle, &data.callInfo, sizeof(data));
+/*    Log(("VBOXSF: VbglR0SfQueryMappings: VbglR0HGCMCall rc = %#x, result = %#x\n", rc, data.callInfo.result)); */
+    if (RT_SUCCESS(rc))
+        *pcMappings = data.numberOfMappings.u.value32;
+
+    return rc;
+}
+
+DECLVBGL(int) VbglR0SfQueryMapName(PVBGLSFCLIENT pClient, SHFLROOT root, SHFLSTRING *pString, uint32_t size)
+{
+    int rc;
+    VBoxSFQueryMapName data;
+
+    VBOX_INIT_CALL(&data.callInfo, QUERY_MAP_NAME, pClient);
+
+    data.root.type                   = VMMDevHGCMParmType_32bit;
+    data.root.u.value32              = root;
+
+    data.name.type                   = VMMDevHGCMParmType_LinAddr;
+    data.name.u.Pointer.size         = size;
+    data.name.u.Pointer.u.linearAddr = (uintptr_t)pString;
+
+    rc = VbglR0HGCMCall(pClient->handle, &data.callInfo, sizeof(data));
+/*    Log(("VBOXSF: VbglR0SfQueryMapName: VbglR0HGCMCall rc = %#x, result = %#x\n", rc, data.callInfo.Hdr.rc)); */
+    return rc;
+}
+
+DECLVBGL(int) VbglR0SfMapFolder(PVBGLSFCLIENT pClient, PSHFLSTRING szFolderName, PVBGLSFMAP pMap)
+{
+    int rc;
+    VBoxSFMapFolder data;
+
+    VBOX_INIT_CALL(&data.callInfo, MAP_FOLDER, pClient);
+
+    data.path.type                    = VMMDevHGCMParmType_LinAddr;
+    data.path.u.Pointer.size          = ShflStringSizeOfBuffer(szFolderName);
+    data.path.u.Pointer.u.linearAddr  = (uintptr_t)szFolderName;
+
+    data.root.type                    = VMMDevHGCMParmType_32bit;
+    data.root.u.value32               = 0;
+
+    data.delimiter.type               = VMMDevHGCMParmType_32bit;
+    data.delimiter.u.value32          = RTPATH_DELIMITER;
+
+    data.fCaseSensitive.type          = VMMDevHGCMParmType_32bit;
+#if defined(RT_OS_WINDOWS) || defined(RT_OS_OS2)
+    data.fCaseSensitive.u.value32     = 0;
+#else
+    data.fCaseSensitive.u.value32     = 1;
+#endif
+
+    rc = VbglR0HGCMCallRaw(pClient->handle, &data.callInfo, sizeof(data));
+/*    Log(("VBOXSF: VbglR0SfMapFolder: VbglR0HGCMCall rc = %#x, result = %#x\n", rc, data.callInfo.Hdr.rc)); */
+    if (RT_SUCCESS(rc))
+    {
+        pMap->root = data.root.u.value32;
+        rc         = data.callInfo.Hdr.rc;
+    }
+    return rc;
+}
+
+DECLVBGL(int) VbglR0SfUnmapFolder(PVBGLSFCLIENT pClient, PVBGLSFMAP pMap)
+{
+    int rc;
+    VBoxSFUnmapFolder data;
+
+    VBOX_INIT_CALL(&data.callInfo, UNMAP_FOLDER, pClient);
+
+    data.root.type                      = VMMDevHGCMParmType_32bit;
+    data.root.u.value32                 = pMap->root;
+
+    rc = VbglR0HGCMCall(pClient->handle, &data.callInfo, sizeof(data));
+/*    Log(("VBOXSF: VbglR0SfUnmapFolder: VbglR0HGCMCall rc = %#x, result = %#x\n", rc, data.callInfo.Hdr.rc)); */
+    return rc;
+}
+
+# if !defined(RT_OS_WINDOWS)
+
+DECLVBGL(int) VbglR0SfCreate(PVBGLSFCLIENT pClient, PVBGLSFMAP pMap, PSHFLSTRING pParsedPath, PSHFLCREATEPARMS pCreateParms)
+{
+    /** @todo copy buffers to physical or mapped memory. */
+    int rc;
+    VBoxSFCreate data;
+
+    VBOX_INIT_CALL(&data.callInfo, CREATE, pClient);
+
+    data.root.type                    = VMMDevHGCMParmType_32bit;
+    data.root.u.value32               = pMap->root;
+
+    data.path.type                    = VMMDevHGCMParmType_LinAddr;
+    data.path.u.Pointer.size          = ShflStringSizeOfBuffer (pParsedPath);
+    data.path.u.Pointer.u.linearAddr  = (uintptr_t)pParsedPath;
+
+    data.parms.type                   = VMMDevHGCMParmType_LinAddr;
+    data.parms.u.Pointer.size         = sizeof(SHFLCREATEPARMS);
+    data.parms.u.Pointer.u.linearAddr = (uintptr_t)pCreateParms;
+
+    rc = VbglR0HGCMCall(pClient->handle, &data.callInfo, sizeof(data));
+/*    Log(("VBOXSF: VbglR0SfCreate: VbglR0HGCMCall rc = %#x, result = %#x\n", rc, data.callInfo.Hdr.rc)); */
+    return rc;
+}
+
+DECLVBGL(int) VbglR0SfClose(PVBGLSFCLIENT pClient, PVBGLSFMAP pMap, SHFLHANDLE Handle)
+{
+    int rc;
+    VBoxSFClose data;
+
+    VBOX_INIT_CALL(&data.callInfo, CLOSE, pClient);
+
+    data.root.type                      = VMMDevHGCMParmType_32bit;
+    data.root.u.value32                 = pMap->root;
+
+    data.handle.type                    = VMMDevHGCMParmType_64bit;
+    data.handle.u.value64               = Handle;
+
+    rc = VbglR0HGCMCall(pClient->handle, &data.callInfo, sizeof(data));
+/*    Log(("VBOXSF: VbglR0SfClose: VbglR0HGCMCall rc = %#x, result = %#x\n", rc, data.callInfo.Hdr.rc)); */
+    return rc;
+}
+
+
+DECLVBGL(int) VbglR0SfRemove(PVBGLSFCLIENT pClient, PVBGLSFMAP pMap, PSHFLSTRING pParsedPath, uint32_t flags)
+{
+    int rc = VINF_SUCCESS;
+
+    VBoxSFRemove data;
+
+    VBOX_INIT_CALL(&data.callInfo, REMOVE, pClient);
+
+    data.root.type                      = VMMDevHGCMParmType_32bit;
+    data.root.u.value32                 = pMap->root;
+
+    data.path.type                      = VMMDevHGCMParmType_LinAddr_In;
+    data.path.u.Pointer.size            = ShflStringSizeOfBuffer(pParsedPath);
+    data.path.u.Pointer.u.linearAddr    = (uintptr_t)pParsedPath;
+
+    data.flags.type                     = VMMDevHGCMParmType_32bit;
+    data.flags.u.value32                = flags;
+
+    rc = VbglR0HGCMCall(pClient->handle, &data.callInfo, sizeof(data));
+/*    Log(("VBOXSF: VbglR0SfRemove: VbglR0HGCMCall rc = %#x, result = %#x\n", rc, data.callInfo.Hdr.rc)); */
+    return rc;
+}
+
+DECLVBGL(int) VbglR0SfRename(PVBGLSFCLIENT pClient, PVBGLSFMAP pMap, PSHFLSTRING pSrcPath, PSHFLSTRING pDestPath, uint32_t flags)
+{
+    int rc;
+    VBoxSFRename data;
+
+    VBOX_INIT_CALL(&data.callInfo, RENAME, pClient);
+
+    data.root.type                      = VMMDevHGCMParmType_32bit;
+    data.root.u.value32                 = pMap->root;
+
+    data.src.type                       = VMMDevHGCMParmType_LinAddr_In;
+    data.src.u.Pointer.size             = ShflStringSizeOfBuffer(pSrcPath);
+    data.src.u.Pointer.u.linearAddr     = (uintptr_t)pSrcPath;
+
+    data.dest.type                      = VMMDevHGCMParmType_LinAddr_In;
+    data.dest.u.Pointer.size            = ShflStringSizeOfBuffer(pDestPath);
+    data.dest.u.Pointer.u.linearAddr    = (uintptr_t)pDestPath;
+
+    data.flags.type                     = VMMDevHGCMParmType_32bit;
+    data.flags.u.value32                = flags;
+
+    rc = VbglR0HGCMCall(pClient->handle, &data.callInfo, sizeof(data));
+/*    Log(("VBOXSF: VbglR0SfRename: VbglR0HGCMCall rc = %#x, result = %#x\n", rc, data.callInfo.Hdr.rc)); */
+    return rc;
+}
+
+DECLVBGL(int) VbglR0SfRead(PVBGLSFCLIENT pClient, PVBGLSFMAP pMap, SHFLHANDLE hFile,
+                           uint64_t offset, uint32_t *pcbBuffer, uint8_t *pBuffer, bool fLocked)
+{
+    int rc;
+    VBoxSFRead data;
+
+    VBOX_INIT_CALL(&data.callInfo, READ, pClient);
+
+    data.root.type                      = VMMDevHGCMParmType_32bit;
+    data.root.u.value32                 = pMap->root;
+
+    data.handle.type                    = VMMDevHGCMParmType_64bit;
+    data.handle.u.value64               = hFile;
+    data.offset.type                    = VMMDevHGCMParmType_64bit;
+    data.offset.u.value64               = offset;
+    data.cb.type                        = VMMDevHGCMParmType_32bit;
+    data.cb.u.value32                   = *pcbBuffer;
+    data.buffer.type                    = (fLocked) ? VMMDevHGCMParmType_LinAddr_Locked_Out : VMMDevHGCMParmType_LinAddr_Out;
+    data.buffer.u.Pointer.size          = *pcbBuffer;
+    data.buffer.u.Pointer.u.linearAddr  = (uintptr_t)pBuffer;
+
+    rc = VbglR0HGCMCallRaw(pClient->handle, &data.callInfo, sizeof(data));
+/*    Log(("VBOXSF: VbglR0SfRead: VbglR0HGCMCall rc = %#x, result = %#x\n", rc, data.callInfo.Hdr.rc)); */
+    if (RT_SUCCESS(rc))
+    {
+        rc = data.callInfo.Hdr.rc;
+        *pcbBuffer = data.cb.u.value32;
+    }
+    return rc;
+}
+
+DECLVBGL(int) VbglR0SfReadPageList(PVBGLSFCLIENT pClient, PVBGLSFMAP pMap, SHFLHANDLE hFile, uint64_t offset, uint32_t *pcbBuffer,
+                                   uint16_t offFirstPage, uint16_t cPages, RTGCPHYS64 *paPages)
+{
+    uint32_t            cbToRead  = *pcbBuffer;
+    uint32_t            cbData    = (uint32_t)(sizeof(VBoxSFRead) + RT_UOFFSETOF_DYN(HGCMPageListInfo, aPages[cPages]));
+    VBoxSFRead         *pData     = (VBoxSFRead *)RTMemTmpAlloc(cbData);
+    HGCMPageListInfo   *pPgLst    = (HGCMPageListInfo *)(pData + 1);
+    uint16_t            iPage;
+    int                 rc;
+
+    if (RT_UNLIKELY(!pData))
+        return VERR_NO_TMP_MEMORY;
+
+    VBOX_INIT_CALL_EX(&pData->callInfo, READ, pClient, cbData);
+
+    pData->root.type                      = VMMDevHGCMParmType_32bit;
+    pData->root.u.value32                 = pMap->root;
+
+    pData->handle.type                    = VMMDevHGCMParmType_64bit;
+    pData->handle.u.value64               = hFile;
+    pData->offset.type                    = VMMDevHGCMParmType_64bit;
+    pData->offset.u.value64               = offset;
+    pData->cb.type                        = VMMDevHGCMParmType_32bit;
+    pData->cb.u.value32                   = cbToRead;
+    pData->buffer.type                    = VMMDevHGCMParmType_PageList;
+    pData->buffer.u.PageList.size         = cbToRead;
+    pData->buffer.u.PageList.offset       = sizeof(VBoxSFRead);
+
+    pPgLst->flags = VBOX_HGCM_F_PARM_DIRECTION_FROM_HOST;
+    pPgLst->offFirstPage = offFirstPage;
+    pPgLst->cPages = cPages;
+    for (iPage = 0; iPage < cPages; iPage++)
+        pPgLst->aPages[iPage] = paPages[iPage];
+
+    rc = VbglR0HGCMCallRaw(pClient->handle, &pData->callInfo, cbData);
+/*    Log(("VBOXSF: VbglR0SfReadPageList: VbglR0HGCMCall rc = %#x, result = %#x\n", rc, data.callInfo.Hdr.rc)); */
+    if (RT_SUCCESS(rc))
+    {
+        rc = pData->callInfo.Hdr.rc;
+        *pcbBuffer = pData->cb.u.value32;
+    }
+
+    RTMemTmpFree(pData);
+    return rc;
+}
+
+DECLVBGL(int) VbglR0SfWrite(PVBGLSFCLIENT pClient, PVBGLSFMAP pMap, SHFLHANDLE hFile,
+                            uint64_t offset, uint32_t *pcbBuffer, uint8_t *pBuffer, bool fLocked)
+{
+    int rc;
+    VBoxSFWrite data;
+
+    VBOX_INIT_CALL(&data.callInfo, WRITE, pClient);
+
+    data.root.type                      = VMMDevHGCMParmType_32bit;
+    data.root.u.value32                 = pMap->root;
+
+    data.handle.type                    = VMMDevHGCMParmType_64bit;
+    data.handle.u.value64               = hFile;
+    data.offset.type                    = VMMDevHGCMParmType_64bit;
+    data.offset.u.value64               = offset;
+    data.cb.type                        = VMMDevHGCMParmType_32bit;
+    data.cb.u.value32                   = *pcbBuffer;
+    data.buffer.type                    = fLocked ? VMMDevHGCMParmType_LinAddr_Locked_In : VMMDevHGCMParmType_LinAddr_In;
+    data.buffer.u.Pointer.size          = *pcbBuffer;
+    data.buffer.u.Pointer.u.linearAddr  = (uintptr_t)pBuffer;
+
+    rc = VbglR0HGCMCallRaw(pClient->handle, &data.callInfo, sizeof(data));
+/*    Log(("VBOXSF: VbglR0SfWrite: VbglR0HGCMCall rc = %#x, result = %#x\n", rc, data.callInfo.Hdr.rc)); */
+    if (RT_SUCCESS(rc))
+    {
+        rc = data.callInfo.Hdr.rc;
+        *pcbBuffer = data.cb.u.value32;
+    }
+    return rc;
+}
+
+DECLVBGL(int) VbglR0SfWritePhysCont(PVBGLSFCLIENT pClient, PVBGLSFMAP pMap, SHFLHANDLE hFile, uint64_t offset,
+                                    uint32_t *pcbBuffer, RTCCPHYS PhysBuffer)
+{
+    uint32_t            cbToWrite = *pcbBuffer;
+    uint32_t            cPages    = RT_ALIGN_32((PhysBuffer & PAGE_OFFSET_MASK) + cbToWrite, PAGE_SIZE) >> PAGE_SHIFT;
+    uint32_t            cbData    = (uint32_t)(sizeof(VBoxSFWrite) + RT_UOFFSETOF_DYN(HGCMPageListInfo, aPages[cPages]));
+    VBoxSFWrite        *pData     = (VBoxSFWrite *)RTMemTmpAlloc(cbData);
+    HGCMPageListInfo   *pPgLst    = (HGCMPageListInfo *)(pData + 1);
+    uint32_t            iPage;
+    int                 rc;
+
+    if (RT_UNLIKELY(!pData))
+        return VERR_NO_TMP_MEMORY;
+
+    VBOX_INIT_CALL_EX(&pData->callInfo, WRITE, pClient, cbData);
+
+    pData->root.type                      = VMMDevHGCMParmType_32bit;
+    pData->root.u.value32                 = pMap->root;
+
+    pData->handle.type                    = VMMDevHGCMParmType_64bit;
+    pData->handle.u.value64               = hFile;
+    pData->offset.type                    = VMMDevHGCMParmType_64bit;
+    pData->offset.u.value64               = offset;
+    pData->cb.type                        = VMMDevHGCMParmType_32bit;
+    pData->cb.u.value32                   = cbToWrite;
+    pData->buffer.type                    = VMMDevHGCMParmType_PageList;
+    pData->buffer.u.PageList.size         = cbToWrite;
+    pData->buffer.u.PageList.offset       = sizeof(VBoxSFWrite);
+
+    pPgLst->flags = VBOX_HGCM_F_PARM_DIRECTION_TO_HOST;
+    pPgLst->offFirstPage = (uint16_t)(PhysBuffer & PAGE_OFFSET_MASK);
+    pPgLst->cPages = cPages;
+    PhysBuffer &= ~(RTCCPHYS)PAGE_OFFSET_MASK;
+    for (iPage = 0; iPage < cPages; iPage++, PhysBuffer += PAGE_SIZE)
+        pPgLst->aPages[iPage] = PhysBuffer;
+
+    rc = VbglR0HGCMCallRaw(pClient->handle, &pData->callInfo, cbData);
+/*    Log(("VBOXSF: VbglR0SfWritePhysCont: VbglR0HGCMCall rc = %#x, result = %#x\n", rc, data.callInfo.Hdr.rc)); */
+    if (RT_SUCCESS(rc))
+    {
+        rc = pData->callInfo.Hdr.rc;
+        *pcbBuffer = pData->cb.u.value32;
+    }
+
+    RTMemTmpFree(pData);
+    return rc;
+
+}
+
+DECLVBGL(int) VbglR0SfWritePageList(PVBGLSFCLIENT pClient, PVBGLSFMAP pMap, SHFLHANDLE hFile, uint64_t offset, uint32_t *pcbBuffer,
+                                    uint16_t offFirstPage, uint16_t cPages, RTGCPHYS64 *paPages)
+{
+    uint32_t            cbToWrite = *pcbBuffer;
+    uint32_t            cbData    = (uint32_t)(sizeof(VBoxSFWrite) + RT_UOFFSETOF_DYN(HGCMPageListInfo, aPages[cPages]));
+    VBoxSFWrite        *pData     = (VBoxSFWrite *)RTMemTmpAlloc(cbData);
+    HGCMPageListInfo   *pPgLst    = (HGCMPageListInfo *)(pData + 1);
+    uint16_t            iPage;
+    int                 rc;
+
+    if (RT_UNLIKELY(!pData))
+        return VERR_NO_TMP_MEMORY;
+
+    VBOX_INIT_CALL_EX(&pData->callInfo, WRITE, pClient, cbData);
+
+    pData->root.type                      = VMMDevHGCMParmType_32bit;
+    pData->root.u.value32                 = pMap->root;
+
+    pData->handle.type                    = VMMDevHGCMParmType_64bit;
+    pData->handle.u.value64               = hFile;
+    pData->offset.type                    = VMMDevHGCMParmType_64bit;
+    pData->offset.u.value64               = offset;
+    pData->cb.type                        = VMMDevHGCMParmType_32bit;
+    pData->cb.u.value32                   = cbToWrite;
+    pData->buffer.type                    = VMMDevHGCMParmType_PageList;
+    pData->buffer.u.PageList.size         = cbToWrite;
+    pData->buffer.u.PageList.offset       = sizeof(VBoxSFWrite);
+
+    pPgLst->flags = VBOX_HGCM_F_PARM_DIRECTION_TO_HOST;
+    pPgLst->offFirstPage = offFirstPage;
+    pPgLst->cPages = cPages;
+    for (iPage = 0; iPage < cPages; iPage++)
+        pPgLst->aPages[iPage] = paPages[iPage];
+
+    rc = VbglR0HGCMCallRaw(pClient->handle, &pData->callInfo, cbData);
+/*    Log(("VBOXSF: VbglR0SfWritePageList: VbglR0HGCMCall rc = %#x, result = %#x\n", rc, data.callInfo.Hdr.rc)); */
+    if (RT_SUCCESS(rc))
+    {
+        rc = pData->callInfo.Hdr.rc;
+        *pcbBuffer = pData->cb.u.value32;
+    }
+
+    RTMemTmpFree(pData);
+    return rc;
+}
+
+# endif /* !RT_OS_WINDOWS */
+
+DECLVBGL(int) VbglR0SfFlush(PVBGLSFCLIENT pClient, PVBGLSFMAP pMap, SHFLHANDLE hFile)
+{
+    int rc;
+    VBoxSFFlush data;
+
+    VBOX_INIT_CALL(&data.callInfo, FLUSH, pClient);
+
+    data.root.type                      = VMMDevHGCMParmType_32bit;
+    data.root.u.value32                 = pMap->root;
+
+    data.handle.type                    = VMMDevHGCMParmType_64bit;
+    data.handle.u.value64               = hFile;
+
+    rc = VbglR0HGCMCall(pClient->handle, &data.callInfo, sizeof(data));
+/*    Log(("VBOXSF: VbglR0SfFlush: VbglR0HGCMCall rc = %#x, result = %#x\n", rc, data.callInfo.Hdr.rc)); */
+    return rc;
+}
+
+DECLVBGL(int) VbglR0SfDirInfo(
+    PVBGLSFCLIENT pClient,
+    PVBGLSFMAP pMap,
+    SHFLHANDLE hFile,
+    PSHFLSTRING ParsedPath,
+    uint32_t flags,
+    uint32_t index,
+    uint32_t *pcbBuffer,
+    PSHFLDIRINFO pBuffer,
+    uint32_t *pcFiles)
+{
+    int rc;
+    VBoxSFList data;
+
+    VBOX_INIT_CALL(&data.callInfo, LIST, pClient);
+
+    data.root.type                      = VMMDevHGCMParmType_32bit;
+    data.root.u.value32                 = pMap->root;
+
+    data.handle.type                    = VMMDevHGCMParmType_64bit;
+    data.handle.u.value64               = hFile;
+    data.flags.type                     = VMMDevHGCMParmType_32bit;
+    data.flags.u.value32                = flags;
+    data.cb.type                        = VMMDevHGCMParmType_32bit;
+    data.cb.u.value32                   = *pcbBuffer;
+    data.path.type                      = VMMDevHGCMParmType_LinAddr_In;
+    data.path.u.Pointer.size            = ParsedPath ? ShflStringSizeOfBuffer(ParsedPath) : 0;
+    data.path.u.Pointer.u.linearAddr    = (uintptr_t) ParsedPath;
+
+    data.buffer.type                    = VMMDevHGCMParmType_LinAddr_Out;
+    data.buffer.u.Pointer.size          = *pcbBuffer;
+    data.buffer.u.Pointer.u.linearAddr  = (uintptr_t)pBuffer;
+
+    data.resumePoint.type               = VMMDevHGCMParmType_32bit;
+    data.resumePoint.u.value32          = index;
+    data.cFiles.type                    = VMMDevHGCMParmType_32bit;
+    data.cFiles.u.value32               = 0; /* out parameters only */
+
+    rc = VbglR0HGCMCall(pClient->handle, &data.callInfo, sizeof(data));
+/*    Log(("VBOXSF: VbglR0SfDirInfo: rc = %#x, result = %#x\n", rc, data.callInfo.Hdr.rc)); */
+    *pcbBuffer = data.cb.u.value32;
+    *pcFiles   = data.cFiles.u.value32;
+    return rc;
+}
+
+# ifndef RT_OS_WINDOWS
+
+DECLVBGL(int) VbglR0SfFsInfo(PVBGLSFCLIENT pClient, PVBGLSFMAP pMap, SHFLHANDLE hFile,
+                             uint32_t flags, uint32_t *pcbBuffer, PSHFLDIRINFO pBuffer)
+{
+    int rc;
+    VBoxSFInformation data;
+
+    VBOX_INIT_CALL(&data.callInfo, INFORMATION, pClient);
+
+    data.root.type                      = VMMDevHGCMParmType_32bit;
+    data.root.u.value32                 = pMap->root;
+
+    data.handle.type                    = VMMDevHGCMParmType_64bit;
+    data.handle.u.value64               = hFile;
+    data.flags.type                     = VMMDevHGCMParmType_32bit;
+    data.flags.u.value32                = flags;
+    data.cb.type                        = VMMDevHGCMParmType_32bit;
+    data.cb.u.value32                   = *pcbBuffer;
+    data.info.type                      = VMMDevHGCMParmType_LinAddr;
+    data.info.u.Pointer.size            = *pcbBuffer;
+    data.info.u.Pointer.u.linearAddr    = (uintptr_t)pBuffer;
+
+    rc = VbglR0HGCMCallRaw(pClient->handle, &data.callInfo, sizeof(data));
+/*    Log(("VBOXSF: VbglR0SfFsInfo: VbglR0HGCMCall rc = %#x, result = %#x\n", rc, data.callInfo.Hdr.rc)); */
+    if (RT_SUCCESS(rc))
+    {
+        rc = data.callInfo.Hdr.rc;
+        *pcbBuffer = data.cb.u.value32;
+    }
+    return rc;
+}
+
+# endif /* !RT_OS_WINDOWS */
+
+DECLVBGL(int) VbglR0SfLock(PVBGLSFCLIENT pClient, PVBGLSFMAP pMap, SHFLHANDLE hFile,
+                           uint64_t offset, uint64_t cbSize, uint32_t fLock)
+{
+    int rc;
+    VBoxSFLock data;
+
+    VBOX_INIT_CALL(&data.callInfo, LOCK, pClient);
+
+    data.root.type                      = VMMDevHGCMParmType_32bit;
+    data.root.u.value32                 = pMap->root;
+
+    data.handle.type                    = VMMDevHGCMParmType_64bit;
+    data.handle.u.value64               = hFile;
+    data.offset.type                    = VMMDevHGCMParmType_64bit;
+    data.offset.u.value64               = offset;
+    data.length.type                    = VMMDevHGCMParmType_64bit;
+    data.length.u.value64               = cbSize;
+
+    data.flags.type                     = VMMDevHGCMParmType_32bit;
+    data.flags.u.value32                = fLock;
+
+    rc = VbglR0HGCMCall(pClient->handle, &data.callInfo, sizeof(data));
+/*    Log(("VBOXSF: VbglR0SfLock: VbglR0HGCMCall rc = %#x, result = %#x\n", rc, data.callInfo.Hdr.rc)); */
+    return rc;
+}
+
+# ifndef RT_OS_WINDOWS
+
+DECLVBGL(int) VbglR0SfReadLink(PVBGLSFCLIENT pClient, PVBGLSFMAP pMap, PSHFLSTRING pParsedPath, uint32_t cbBuffer, uint8_t *pBuffer)
+{
+    int rc;
+    VBoxSFReadLink data;
+
+    VBOX_INIT_CALL(&data.callInfo, READLINK, pClient);
+
+    data.root.type                      = VMMDevHGCMParmType_32bit;
+    data.root.u.value32                 = pMap->root;
+
+    data.path.type                      = VMMDevHGCMParmType_LinAddr_In;
+    data.path.u.Pointer.size            = ShflStringSizeOfBuffer (pParsedPath);
+    data.path.u.Pointer.u.linearAddr    = (uintptr_t)pParsedPath;
+
+    data.buffer.type                    = VMMDevHGCMParmType_LinAddr_Out;
+    data.buffer.u.Pointer.size          = cbBuffer;
+    data.buffer.u.Pointer.u.linearAddr  = (uintptr_t)pBuffer;
+
+    rc = VbglR0HGCMCall(pClient->handle, &data.callInfo, sizeof(data));
+/*    Log(("VBOXSF: VbglR0SfReadLink: VbglR0HGCMCall rc = %#x, result = %#x\n", rc, data.callInfo.Hdr.rc)); */
+    return rc;
+}
+
+DECLVBGL(int) VbglR0SfSymlink(PVBGLSFCLIENT pClient, PVBGLSFMAP pMap, PSHFLSTRING pNewPath, PSHFLSTRING pOldPath,
+                              PSHFLFSOBJINFO pBuffer)
+{
+    int rc;
+    VBoxSFSymlink data;
+
+    VBOX_INIT_CALL(&data.callInfo, SYMLINK, pClient);
+
+    data.root.type                      = VMMDevHGCMParmType_32bit;
+    data.root.u.value32                 = pMap->root;
+
+    data.newPath.type                   = VMMDevHGCMParmType_LinAddr_In;
+    data.newPath.u.Pointer.size         = ShflStringSizeOfBuffer (pNewPath);
+    data.newPath.u.Pointer.u.linearAddr = (uintptr_t)pNewPath;
+
+    data.oldPath.type                   = VMMDevHGCMParmType_LinAddr_In;
+    data.oldPath.u.Pointer.size         = ShflStringSizeOfBuffer (pOldPath);
+    data.oldPath.u.Pointer.u.linearAddr = (uintptr_t)pOldPath;
+
+    data.info.type                      = VMMDevHGCMParmType_LinAddr_Out;
+    data.info.u.Pointer.size            = sizeof(SHFLFSOBJINFO);
+    data.info.u.Pointer.u.linearAddr    = (uintptr_t)pBuffer;
+
+    rc = VbglR0HGCMCall(pClient->handle, &data.callInfo, sizeof(data));
+/*    Log(("VBOXSF: VbglR0SfSymlink: VbglR0HGCMCall rc = %#x, result = %#x\n", rc, data.callInfo.Hdr.rc)); */
+    return rc;
+}
+
+DECLVBGL(int) VbglR0SfSetSymlinks(PVBGLSFCLIENT pClient)
+{
+    int rc;
+    VBGLIOCHGCMCALL callInfo;
+
+    VBOX_INIT_CALL(&callInfo, SET_SYMLINKS, pClient);
+    rc = VbglR0HGCMCall(pClient->handle, &callInfo, sizeof(callInfo));
+/*    Log(("VBOXSF: VbglR0SfSetSymlinks: VbglR0HGCMCall rc = %#x, result = %#x\n", rc, data.callInfo.Hdr.rc)); */
+    return rc;
+}
+
+# endif /* !RT_OS_WINDOWS */
+
+#endif /* !RT_OS_LINUX */
+
+/** @} */
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibVMMDev.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibVMMDev.cpp
new file mode 100644
index 00000000..5909fd2c
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibVMMDev.cpp
@@ -0,0 +1,51 @@
+/* $Id: VBoxGuestR0LibVMMDev.cpp $ */
+/** @file
+ * VBoxGuestLibR0 - VMMDev device related functions.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "VBoxGuestR0LibInternal.h"
+
+
+DECLVBGL(int) VbglR0QueryVMMDevMemory(VMMDevMemory **ppVMMDevMemory)
+{
+    int rc = vbglR0Enter();
+    if (RT_FAILURE(rc))
+        return rc;
+
+    /* If the memory was not found, return an error. */
+    if (!g_vbgldata.pVMMDevMemory)
+        return VERR_NOT_SUPPORTED;
+
+    *ppVMMDevMemory = g_vbgldata.pVMMDevMemory;
+    return rc;
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3Lib.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3Lib.cpp
new file mode 100644
index 00000000..4298b742
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3Lib.cpp
@@ -0,0 +1,485 @@
+/* $Id: VBoxGuestR3Lib.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, Core.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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                                                                                                                 *
+*********************************************************************************************************************************/
+#if defined(RT_OS_WINDOWS)
+# include <iprt/nt/nt-and-windows.h>
+
+#elif defined(RT_OS_OS2)
+# define INCL_BASE
+# define INCL_ERRORS
+# include <os2.h>
+
+#elif defined(RT_OS_DARWIN) \
+   || defined(RT_OS_FREEBSD) \
+   || defined(RT_OS_HAIKU) \
+   || defined(RT_OS_LINUX) \
+   || defined(RT_OS_NETBSD) \
+   || defined(RT_OS_SOLARIS)
+# include <sys/types.h>
+# include <sys/stat.h>
+# if defined(RT_OS_DARWIN) || defined(RT_OS_LINUX) || defined(RT_OS_NETBSD)
+   /** @todo check this on solaris+freebsd as well. */
+#  include <sys/ioctl.h>
+# endif
+# if defined(RT_OS_DARWIN)
+#  include <mach/mach_port.h>
+#  include <IOKit/IOKitLib.h>
+# endif
+# include <errno.h>
+# include <unistd.h>
+#endif
+
+#include <iprt/assert.h>
+#include <iprt/asm.h>
+#include <iprt/err.h>
+#include <iprt/file.h>
+#include <iprt/time.h>
+#include <iprt/string.h>
+#include <iprt/thread.h>
+#include <VBox/log.h>
+#include "VBoxGuestR3LibInternal.h"
+
+#ifdef VBOX_VBGLR3_XFREE86
+/* Rather than try to resolve all the header file conflicts, I will just
+   prototype what we need here. */
+# define XF86_O_RDWR  0x0002
+typedef void *pointer;
+extern "C" int xf86open(const char *, int, ...);
+extern "C" int xf86close(int);
+extern "C" int xf86ioctl(int, unsigned long, pointer);
+# define VBOX_VBGLR3_XSERVER
+#elif defined(VBOX_VBGLR3_XORG)
+# include <sys/stat.h>
+# include <fcntl.h>
+# include <unistd.h>
+# include <sys/ioctl.h>
+# define xf86open open
+# define xf86close close
+# define xf86ioctl ioctl
+# define XF86_O_RDWR O_RDWR
+# define VBOX_VBGLR3_XSERVER
+#endif
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/** The VBoxGuest device handle. */
+#ifdef VBOX_VBGLR3_XSERVER
+static int g_File = -1;
+#elif defined(RT_OS_WINDOWS)
+static HANDLE g_hFile = INVALID_HANDLE_VALUE;
+#else
+static RTFILE g_File = NIL_RTFILE;
+#endif
+/** User counter.
+ * A counter of the number of times the library has been initialised, for use with
+ * X.org drivers, where the library may be shared by multiple independent modules
+ * inside a single process space.
+ */
+static uint32_t volatile g_cInits = 0;
+#ifdef RT_OS_DARWIN
+/** I/O Kit connection handle. */
+static io_connect_t g_uConnection = 0;
+#endif
+
+
+
+/**
+ * Implementation of VbglR3Init and VbglR3InitUser
+ */
+static int vbglR3Init(const char *pszDeviceName)
+{
+    int      rc2;
+    uint32_t cInits = ASMAtomicIncU32(&g_cInits);
+    Assert(cInits > 0);
+    if (cInits > 1)
+    {
+        /*
+         * This will fail if two (or more) threads race each other calling VbglR3Init.
+         * However it will work fine for single threaded or otherwise serialized
+         * processed calling us more than once.
+         */
+#ifdef RT_OS_WINDOWS
+        if (g_hFile == INVALID_HANDLE_VALUE)
+#elif !defined (VBOX_VBGLR3_XSERVER)
+        if (g_File == NIL_RTFILE)
+#else
+        if (g_File == -1)
+#endif
+            return VERR_INTERNAL_ERROR;
+        return VINF_SUCCESS;
+    }
+#if defined(RT_OS_WINDOWS)
+    if (g_hFile != INVALID_HANDLE_VALUE)
+#elif !defined(VBOX_VBGLR3_XSERVER)
+    if (g_File != NIL_RTFILE)
+#else
+    if (g_File != -1)
+#endif
+        return VERR_INTERNAL_ERROR;
+
+#if defined(RT_OS_WINDOWS)
+    /*
+     * Have to use CreateFile here as we want to specify FILE_FLAG_OVERLAPPED
+     * and possible some other bits not available thru iprt/file.h.
+     */
+    HANDLE hFile = CreateFile(pszDeviceName,
+                              GENERIC_READ | GENERIC_WRITE,
+                              FILE_SHARE_READ | FILE_SHARE_WRITE,
+                              NULL,
+                              OPEN_EXISTING,
+                              FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED,
+                              NULL);
+
+    if (hFile == INVALID_HANDLE_VALUE)
+        return VERR_OPEN_FAILED;
+    g_hFile = hFile;
+
+#elif defined(RT_OS_OS2)
+    /*
+     * We might wish to compile this with Watcom, so stick to
+     * the OS/2 APIs all the way. And in any case we have to use
+     * DosDevIOCtl for the requests, why not use Dos* for everything.
+     */
+    HFILE hf = NULLHANDLE;
+    ULONG ulAction = 0;
+    APIRET rc = DosOpen((PCSZ)pszDeviceName, &hf, &ulAction, 0, FILE_NORMAL,
+                        OPEN_ACTION_OPEN_IF_EXISTS,
+                        OPEN_FLAGS_FAIL_ON_ERROR | OPEN_FLAGS_NOINHERIT | OPEN_SHARE_DENYNONE | OPEN_ACCESS_READWRITE,
+                        NULL);
+    if (rc)
+        return RTErrConvertFromOS2(rc);
+
+    if (hf < 16)
+    {
+        HFILE ahfs[16];
+        unsigned i;
+        for (i = 0; i < RT_ELEMENTS(ahfs); i++)
+        {
+            ahfs[i] = 0xffffffff;
+            rc = DosDupHandle(hf, &ahfs[i]);
+            if (rc)
+                break;
+        }
+
+        if (i-- > 1)
+        {
+            ULONG fulState = 0;
+            rc = DosQueryFHState(ahfs[i], &fulState);
+            if (!rc)
+            {
+                fulState |= OPEN_FLAGS_NOINHERIT;
+                fulState &= OPEN_FLAGS_WRITE_THROUGH | OPEN_FLAGS_FAIL_ON_ERROR | OPEN_FLAGS_NO_CACHE | OPEN_FLAGS_NOINHERIT; /* Turn off non-participating bits. */
+                rc = DosSetFHState(ahfs[i], fulState);
+            }
+            if (!rc)
+            {
+                rc = DosClose(hf);
+                AssertMsg(!rc, ("%ld\n", rc));
+                hf = ahfs[i];
+            }
+            else
+                i++;
+            while (i-- > 0)
+                DosClose(ahfs[i]);
+        }
+    }
+    g_File = (RTFILE)hf;
+
+#elif defined(RT_OS_DARWIN)
+    /*
+     * Darwin is kind of special we need to engage the device via I/O first
+     * before we open it via the BSD device node.
+     */
+   /* IOKit */
+    mach_port_t MasterPort;
+    kern_return_t kr = IOMasterPort(MACH_PORT_NULL, &MasterPort);
+    if (kr != kIOReturnSuccess)
+    {
+        LogRel(("IOMasterPort -> %d\n", kr));
+        return VERR_GENERAL_FAILURE;
+    }
+
+    CFDictionaryRef ClassToMatch = IOServiceMatching("org_virtualbox_VBoxGuest");
+    if (!ClassToMatch)
+    {
+        LogRel(("IOServiceMatching(\"org_virtualbox_VBoxGuest\") failed.\n"));
+        return VERR_GENERAL_FAILURE;
+    }
+
+    io_service_t ServiceObject = IOServiceGetMatchingService(kIOMasterPortDefault, ClassToMatch);
+    if (!ServiceObject)
+    {
+        LogRel(("IOServiceGetMatchingService returned NULL\n"));
+        return VERR_NOT_FOUND;
+    }
+
+    io_connect_t uConnection;
+    kr = IOServiceOpen(ServiceObject, mach_task_self(), VBOXGUEST_DARWIN_IOSERVICE_COOKIE, &uConnection);
+    IOObjectRelease(ServiceObject);
+    if (kr != kIOReturnSuccess)
+    {
+        LogRel(("IOServiceOpen returned %d. Driver open failed.\n", kr));
+        return VERR_OPEN_FAILED;
+    }
+
+    /* Regular unix FD. */
+    RTFILE hFile;
+    int rc = RTFileOpen(&hFile, pszDeviceName, RTFILE_O_READWRITE | RTFILE_O_OPEN | RTFILE_O_DENY_NONE);
+    if (RT_FAILURE(rc))
+    {
+        LogRel(("RTFileOpen(%s) returned %Rrc. Driver open failed.\n", pszDeviceName, rc));
+        IOServiceClose(uConnection);
+        return rc;
+    }
+    g_File = hFile;
+    g_uConnection = uConnection;
+
+#elif defined(VBOX_VBGLR3_XSERVER)
+    int File = xf86open(pszDeviceName, XF86_O_RDWR);
+    if (File == -1)
+        return VERR_OPEN_FAILED;
+    g_File = File;
+
+#else
+
+    /* The default implementation. (linux, solaris, freebsd, netbsd, haiku) */
+    RTFILE File;
+    int rc = RTFileOpen(&File, pszDeviceName, RTFILE_O_READWRITE | RTFILE_O_OPEN | RTFILE_O_DENY_NONE);
+    if (RT_FAILURE(rc))
+        return rc;
+    g_File = File;
+
+#endif
+
+    /*
+     * Adjust the I/O control interface version.
+     */
+    {
+        VBGLIOCDRIVERVERSIONINFO VerInfo;
+        VBGLREQHDR_INIT(&VerInfo.Hdr, DRIVER_VERSION_INFO);
+        VerInfo.u.In.uMinVersion    = VBGL_IOC_VERSION & UINT32_C(0xffff0000);
+        VerInfo.u.In.uReqVersion    = VBGL_IOC_VERSION;
+        VerInfo.u.In.uReserved1     = 0;
+        VerInfo.u.In.uReserved2     = 0;
+        rc2 = vbglR3DoIOCtl(VBGL_IOCTL_DRIVER_VERSION_INFO, &VerInfo.Hdr, sizeof(VerInfo));
+#ifndef VBOX_VBGLR3_XSERVER
+        AssertRC(rc2); /* otherwise ignored for now*/
+#endif
+    }
+
+
+#ifndef VBOX_VBGLR3_XSERVER
+    /*
+     * Create release logger
+     */
+    PRTLOGGER pReleaseLogger;
+    static const char * const s_apszGroups[] = VBOX_LOGGROUP_NAMES;
+    rc2 = RTLogCreate(&pReleaseLogger, 0, "all", "VBOX_RELEASE_LOG",
+                      RT_ELEMENTS(s_apszGroups), &s_apszGroups[0], RTLOGDEST_USER, NULL);
+    /* This may legitimately fail if we are using the mini-runtime. */
+    if (RT_SUCCESS(rc2))
+        RTLogRelSetDefaultInstance(pReleaseLogger);
+#endif
+
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Open the VBox R3 Guest Library.  This should be called by system daemons
+ * and processes.
+ */
+VBGLR3DECL(int) VbglR3Init(void)
+{
+    return vbglR3Init(VBOXGUEST_DEVICE_NAME);
+}
+
+
+/**
+ * Open the VBox R3 Guest Library.  Equivalent to VbglR3Init, but for user
+ * session processes.
+ */
+VBGLR3DECL(int) VbglR3InitUser(void)
+{
+    return vbglR3Init(VBOXGUEST_USER_DEVICE_NAME);
+}
+
+
+VBGLR3DECL(void) VbglR3Term(void)
+{
+    /*
+     * Decrement the reference count and see if we're the last one out.
+     */
+    uint32_t cInits = ASMAtomicDecU32(&g_cInits);
+    if (cInits > 0)
+        return;
+#if !defined(VBOX_VBGLR3_XSERVER)
+    AssertReturnVoid(!cInits);
+
+# if defined(RT_OS_WINDOWS)
+    HANDLE hFile = g_hFile;
+    g_hFile = INVALID_HANDLE_VALUE;
+    AssertReturnVoid(hFile != INVALID_HANDLE_VALUE);
+    BOOL fRc = CloseHandle(hFile);
+    Assert(fRc); NOREF(fRc);
+
+# elif defined(RT_OS_OS2)
+    RTFILE File = g_File;
+    g_File = NIL_RTFILE;
+    AssertReturnVoid(File != NIL_RTFILE);
+    APIRET rc = DosClose((uintptr_t)File);
+    AssertMsg(!rc, ("%ld\n", rc));
+
+#elif defined(RT_OS_DARWIN)
+    io_connect_t    uConnection = g_uConnection;
+    RTFILE          hFile       = g_File;
+    g_uConnection = 0;
+    g_File        = NIL_RTFILE;
+    kern_return_t kr = IOServiceClose(uConnection);
+    AssertMsg(kr == kIOReturnSuccess, ("%#x (%d)\n", kr, kr)); NOREF(kr);
+    int rc = RTFileClose(hFile);
+    AssertRC(rc);
+
+# else /* The IPRT case. */
+    RTFILE File = g_File;
+    g_File = NIL_RTFILE;
+    AssertReturnVoid(File != NIL_RTFILE);
+    int rc = RTFileClose(File);
+    AssertRC(rc);
+# endif
+
+#else  /* VBOX_VBGLR3_XSERVER */
+    int File = g_File;
+    g_File = -1;
+    if (File == -1)
+        return;
+    xf86close(File);
+#endif /* VBOX_VBGLR3_XSERVER */
+}
+
+
+/**
+ * Internal wrapper around various OS specific ioctl implementations.
+ *
+ * @returns VBox status code as returned by VBoxGuestCommonIOCtl, or
+ *          an failure returned by the OS specific ioctl APIs.
+ *
+ * @param   uFunction   The requested function.
+ * @param   pHdr        The input and output request buffer.
+ * @param   cbReq       The size of the request buffer.
+ */
+int vbglR3DoIOCtlRaw(uintptr_t uFunction, PVBGLREQHDR pHdr, size_t cbReq)
+{
+    Assert(cbReq == RT_MAX(pHdr->cbIn, pHdr->cbOut)); RT_NOREF1(cbReq);
+    Assert(pHdr->cbOut != 0);
+
+#if defined(RT_OS_WINDOWS)
+# if 0 /*def USE_NT_DEVICE_IO_CONTROL_FILE*/
+    IO_STATUS_BLOCK Ios;
+    Ios.Status      = -1;
+    Ios.Information = 0;
+    NTSTATUS rcNt = NtDeviceIoControlFile(g_hFile, NULL /*hEvent*/, NULL /*pfnApc*/, NULL /*pvApcCtx*/, &Ios,
+                                          (ULONG)uFunction,
+                                          pHdr /*pvInput */, pHdr->cbIn /* cbInput */,
+                                          pHdr /*pvOutput*/, pHdr->cbOut /* cbOutput */);
+    if (NT_SUCCESS(rcNt))
+    {
+        if (NT_SUCCESS(Ios.Status))
+            return VINF_SUCCESS;
+        rcNt = Ios.Status;
+    }
+    return RTErrConvertFromNtStatus(rcNt);
+
+# else
+    DWORD cbReturned = (ULONG)pHdr->cbOut;
+    if (DeviceIoControl(g_hFile, uFunction, pHdr, pHdr->cbIn, pHdr, cbReturned, &cbReturned, NULL))
+        return 0;
+    return RTErrConvertFromWin32(GetLastError());
+# endif
+
+#elif defined(RT_OS_OS2)
+    ULONG cbOS2Parm = cbReq;
+    APIRET rc = DosDevIOCtl((uintptr_t)g_File, VBGL_IOCTL_CATEGORY, uFunction, pHdr, cbReq, &cbOS2Parm, NULL, 0, NULL);
+    if (RT_LIKELY(rc == NO_ERROR))
+        return VINF_SUCCESS;
+    return RTErrConvertFromOS2(rc);
+
+#elif defined(VBOX_VBGLR3_XSERVER)
+    if (g_File != -1)
+    {
+        if (RT_LIKELY(xf86ioctl((int)g_File, uFunction, pHdr) >= 0))
+            return VINF_SUCCESS;
+        return VERR_FILE_IO_ERROR;
+    }
+    return VERR_INVALID_HANDLE;
+
+#else
+    if (g_File != NIL_RTFILE)
+    {
+        if (RT_LIKELY(ioctl((int)(intptr_t)g_File, uFunction, pHdr) >= 0))
+            return VINF_SUCCESS;
+        return RTErrConvertFromErrno(errno);
+    }
+    return VERR_INVALID_HANDLE;
+#endif
+}
+
+
+/**
+ * Internal wrapper around various OS specific ioctl implementations, that
+ * returns the status from the header.
+ *
+ * @returns VBox status code as returned by VBoxGuestCommonIOCtl, or
+ *          an failure returned by the OS specific ioctl APIs.
+ *
+ * @param   uFunction   The requested function.
+ * @param   pHdr        The input and output request buffer.
+ * @param   cbReq       The size of the request buffer.
+ */
+int vbglR3DoIOCtl(uintptr_t uFunction, PVBGLREQHDR pHdr, size_t cbReq)
+{
+    int rc = vbglR3DoIOCtlRaw(uFunction, pHdr, cbReq);
+    if (RT_SUCCESS(rc))
+        rc = pHdr->rc;
+    return rc;
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibAdditions.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibAdditions.cpp
new file mode 100644
index 00000000..2ee88509
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibAdditions.cpp
@@ -0,0 +1,363 @@
+/* $Id: VBoxGuestR3LibAdditions.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, Additions Info.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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 <iprt/err.h>
+#include <iprt/mem.h>
+#include <iprt/path.h>
+#include <iprt/string.h>
+#ifdef RT_OS_WINDOWS
+# include <iprt/utf16.h>
+#endif
+#include <VBox/log.h>
+#include <VBox/version.h>
+#include "VBoxGuestR3LibInternal.h"
+
+
+
+#ifdef RT_OS_WINDOWS
+
+/**
+ * Opens the "VirtualBox Guest Additions" registry key.
+ *
+ * @returns IPRT status code
+ * @param   phKey       Receives key handle on success. The returned handle must
+ *                      be closed by calling vbglR3WinCloseRegKey.
+ */
+static int vbglR3WinOpenAdditionRegisterKey(PHKEY phKey)
+{
+    /*
+     * Current vendor first.  We keep the older ones just for the case that
+     * the caller isn't actually installed yet (no real use case AFAIK).
+     */
+    static PCRTUTF16 s_apwszKeys[] =
+    {
+        L"SOFTWARE\\" RT_LSTR(VBOX_VENDOR_SHORT) L"\\VirtualBox Guest Additions",
+#ifdef RT_ARCH_AMD64
+        L"SOFTWARE\\Wow6432Node\\" RT_LSTR(VBOX_VENDOR_SHORT) L"\\VirtualBox Guest Additions",
+#endif
+        L"SOFTWARE\\Sun\\VirtualBox Guest Additions",
+#ifdef RT_ARCH_AMD64
+        L"SOFTWARE\\Wow6432Node\\Sun\\VirtualBox Guest Additions",
+#endif
+        L"SOFTWARE\\Sun\\xVM VirtualBox Guest Additions",
+#ifdef RT_ARCH_AMD64
+        L"SOFTWARE\\Wow6432Node\\Sun\\xVM VirtualBox Guest Additions",
+#endif
+    };
+    int rc = VERR_NOT_FOUND;
+    for (uint32_t i = 0; i < RT_ELEMENTS(s_apwszKeys); i++)
+    {
+        LSTATUS lrc = RegOpenKeyExW(HKEY_LOCAL_MACHINE, s_apwszKeys[i], 0 /* ulOptions*/, KEY_READ, phKey);
+        if (lrc == ERROR_SUCCESS)
+            return VINF_SUCCESS;
+        if (i == 0)
+            rc = RTErrConvertFromWin32(lrc);
+    }
+    return rc;
+}
+
+
+/**
+ * Closes the registry handle returned by vbglR3WinOpenAdditionRegisterKey().
+ *
+ * @returns @a rc or IPRT failure status.
+ * @param   hKey        Handle to close.
+ * @param   rc          The current IPRT status of the operation.  Error
+ *                      condition takes precedence over errors from this call.
+ */
+static int vbglR3WinCloseRegKey(HKEY hKey, int rc)
+{
+    LSTATUS lrc = RegCloseKey(hKey);
+    if (   lrc == ERROR_SUCCESS
+        || RT_FAILURE(rc))
+        return rc;
+    return RTErrConvertFromWin32(lrc);
+}
+
+
+/**
+ * Queries a string value from a specified registry key.
+ *
+ * @return  IPRT status code.
+ * @param   hKey                Handle of registry key to use.
+ * @param   pwszValueName       The name of the value to query.
+ * @param   cbHint              Size hint.
+ * @param   ppszValue           Where to return value string on success. Free
+ *                              with RTStrFree.
+ */
+static int vbglR3QueryRegistryString(HKEY hKey, PCRTUTF16 pwszValueName, uint32_t cbHint, char **ppszValue)
+{
+    AssertPtr(pwszValueName);
+    AssertPtrReturn(ppszValue, VERR_INVALID_POINTER);
+
+    /*
+     * First try.
+     */
+    int rc;
+    DWORD dwType;
+    DWORD cbTmp = cbHint;
+    PRTUTF16 pwszTmp = (PRTUTF16)RTMemTmpAllocZ(cbTmp + sizeof(RTUTF16));
+    if (pwszTmp)
+    {
+        LSTATUS lrc = RegQueryValueExW(hKey, pwszValueName, NULL, &dwType, (BYTE *)pwszTmp, &cbTmp);
+        if (lrc == ERROR_MORE_DATA)
+        {
+            /*
+             * Allocate larger buffer and try again.
+             */
+            RTMemTmpFree(pwszTmp);
+            cbTmp += 16;
+            pwszTmp = (PRTUTF16)RTMemTmpAllocZ(cbTmp + sizeof(RTUTF16));
+            if (!pwszTmp)
+            {
+                *ppszValue = NULL;
+                return VERR_NO_TMP_MEMORY;
+            }
+            lrc = RegQueryValueExW(hKey, pwszValueName, NULL, &dwType, (BYTE *)pwszTmp, &cbTmp);
+        }
+        if (lrc == ERROR_SUCCESS)
+        {
+            /*
+             * Check the type and convert to UTF-8.
+             */
+            if (dwType == REG_SZ)
+                rc = RTUtf16ToUtf8(pwszTmp, ppszValue);
+            else
+                rc = VERR_WRONG_TYPE;
+        }
+        else
+            rc = RTErrConvertFromWin32(lrc);
+        RTMemTmpFree(pwszTmp);
+    }
+    else
+        rc = VERR_NO_TMP_MEMORY;
+    if (RT_SUCCESS(rc))
+        return rc;
+    *ppszValue = NULL;
+    return rc;
+}
+
+#endif /* RT_OS_WINDOWS */
+
+
+/**
+ * Fallback for VbglR3GetAdditionsVersion.
+ *
+ * @copydoc VbglR3GetAdditionsVersion
+ */
+static int vbglR3GetAdditionsCompileTimeVersion(char **ppszVer, char **ppszVerExt, char **ppszRev)
+{
+    int rc = VINF_SUCCESS;
+    if (ppszVer)
+        rc = RTStrDupEx(ppszVer, VBOX_VERSION_STRING_RAW);
+    if (RT_SUCCESS(rc))
+    {
+        if (ppszVerExt)
+            rc = RTStrDupEx(ppszVerExt, VBOX_VERSION_STRING);
+        if (RT_SUCCESS(rc))
+        {
+            if (ppszRev)
+                rc = RTStrDupEx(ppszRev, RT_XSTR(VBOX_SVN_REV));
+            if (RT_SUCCESS(rc))
+                return VINF_SUCCESS;
+
+            /* bail out: */
+        }
+        if (ppszVerExt)
+        {
+            RTStrFree(*ppszVerExt);
+            *ppszVerExt = NULL;
+        }
+    }
+    if (ppszVer)
+    {
+        RTStrFree(*ppszVer);
+        *ppszVer = NULL;
+    }
+    return rc;
+}
+
+
+/**
+ * Retrieves the installed Guest Additions version and/or revision.
+ *
+ * @returns IPRT status code
+ * @param   ppszVer     Receives pointer of allocated raw version string
+ *                      (major.minor.build). NULL is accepted. The returned
+ *                      pointer must be freed using RTStrFree().
+ * @param   ppszVerExt  Receives pointer of allocated full version string
+ *                      (raw version + vendor suffix(es)). NULL is
+ *                      accepted. The returned pointer must be freed using
+ *                      RTStrFree().
+ * @param   ppszRev     Receives pointer of allocated revision string. NULL is
+ *                      accepted. The returned pointer must be freed using
+ *                      RTStrFree().
+ */
+VBGLR3DECL(int) VbglR3GetAdditionsVersion(char **ppszVer, char **ppszVerExt, char **ppszRev)
+{
+    /*
+     * Zap the return value up front.
+     */
+    if (ppszVer)
+        *ppszVer    = NULL;
+    if (ppszVerExt)
+        *ppszVerExt = NULL;
+    if (ppszRev)
+        *ppszRev    = NULL;
+
+#ifdef RT_OS_WINDOWS
+    HKEY hKey;
+    int rc = vbglR3WinOpenAdditionRegisterKey(&hKey);
+    if (RT_SUCCESS(rc))
+    {
+        /*
+         * Version.
+         */
+        if (ppszVer)
+            rc = vbglR3QueryRegistryString(hKey, L"Version", 64, ppszVer);
+
+        if (   RT_SUCCESS(rc)
+            && ppszVerExt)
+            rc = vbglR3QueryRegistryString(hKey, L"VersionExt", 128, ppszVerExt);
+
+        /*
+         * Revision.
+         */
+        if (   RT_SUCCESS(rc)
+            && ppszRev)
+            rc = vbglR3QueryRegistryString(hKey, L"Revision", 64, ppszRev);
+
+        rc = vbglR3WinCloseRegKey(hKey, rc);
+
+        /* Clean up allocated strings on error. */
+        if (RT_FAILURE(rc))
+        {
+            if (ppszVer)
+            {
+                RTStrFree(*ppszVer);
+                *ppszVer = NULL;
+            }
+            if (ppszVerExt)
+            {
+                RTStrFree(*ppszVerExt);
+                *ppszVerExt = NULL;
+            }
+            if (ppszRev)
+            {
+                RTStrFree(*ppszRev);
+                *ppszRev = NULL;
+            }
+        }
+    }
+    /*
+     * No registry entries found, return the version string compiled into this binary.
+     */
+    else
+        rc = vbglR3GetAdditionsCompileTimeVersion(ppszVer, ppszVerExt, ppszRev);
+    return rc;
+
+#else  /* !RT_OS_WINDOWS */
+    /*
+     * On non-Windows platforms just return the compile-time version string.
+     */
+    return vbglR3GetAdditionsCompileTimeVersion(ppszVer, ppszVerExt, ppszRev);
+#endif /* !RT_OS_WINDOWS */
+}
+
+
+/**
+ * Retrieves the installation path of Guest Additions.
+ *
+ * @returns IPRT status code
+ * @param   ppszPath    Receives pointer of allocated installation path string.
+ *                      The returned pointer must be freed using
+ *                      RTStrFree().
+ */
+VBGLR3DECL(int) VbglR3GetAdditionsInstallationPath(char **ppszPath)
+{
+    int rc;
+
+#ifdef RT_OS_WINDOWS
+    /*
+     * Get it from the registry.
+     */
+    HKEY hKey;
+    rc = vbglR3WinOpenAdditionRegisterKey(&hKey);
+    if (RT_SUCCESS(rc))
+    {
+        rc = vbglR3QueryRegistryString(hKey, L"InstallDir", MAX_PATH * sizeof(RTUTF16), ppszPath);
+        if (RT_SUCCESS(rc))
+            RTPathChangeToUnixSlashes(*ppszPath, true /*fForce*/);
+        rc = vbglR3WinCloseRegKey(hKey, rc);
+    }
+#else
+    /** @todo implement me */
+    rc = VERR_NOT_IMPLEMENTED;
+    RT_NOREF1(ppszPath);
+#endif
+    return rc;
+}
+
+
+/**
+ * Reports the Guest Additions status of a certain facility to the host.
+ *
+ * @returns IPRT status code
+ * @param   enmFacility     The facility to report the status on.
+ * @param   enmStatus       The new status of the facility.
+ * @param   fReserved       Flags reserved for future hacks.
+ */
+VBGLR3DECL(int) VbglR3ReportAdditionsStatus(VBoxGuestFacilityType enmFacility, VBoxGuestFacilityStatus enmStatus,
+                                            uint32_t fReserved)
+{
+    VMMDevReportGuestStatus Report;
+    RT_ZERO(Report);
+    int rc = vmmdevInitRequest(&Report.header, VMMDevReq_ReportGuestStatus);
+    if (RT_SUCCESS(rc))
+    {
+        Report.guestStatus.facility = enmFacility;
+        Report.guestStatus.status   = enmStatus;
+        Report.guestStatus.flags    = fReserved;
+
+        rc = vbglR3GRPerform(&Report.header);
+    }
+    return rc;
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibAutoLogon.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibAutoLogon.cpp
new file mode 100644
index 00000000..680e6a5c
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibAutoLogon.cpp
@@ -0,0 +1,130 @@
+/* $Id: VBoxGuestR3LibAutoLogon.cpp $ */
+/** @file
+ * VBoxGuestR3LibAutoLogon - Ring-3 utility functions for auto-logon modules
+ *                           (VBoxGINA / VBoxCredProv / pam_vbox).
+ */
+
+/*
+ * 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                                                                                                                 *
+*********************************************************************************************************************************/
+#ifdef RT_OS_WINDOWS
+# include <iprt/win/windows.h>
+#endif
+
+#include "VBoxGuestR3LibInternal.h"
+#include <iprt/errcore.h>
+
+
+/**
+ * Reports the current auto-logon status to the host.
+ *
+ * This makes sure that the Failed state is sticky.
+ *
+ * @return  IPRT status code.
+ * @param   enmStatus               Status to report to the host.
+ */
+VBGLR3DECL(int) VbglR3AutoLogonReportStatus(VBoxGuestFacilityStatus enmStatus)
+{
+    /*
+     * VBoxGuestFacilityStatus_Failed is sticky.
+     */
+    static VBoxGuestFacilityStatus s_enmLastStatus = VBoxGuestFacilityStatus_Inactive;
+    if (s_enmLastStatus != VBoxGuestFacilityStatus_Failed)
+    {
+        int rc = VbglR3ReportAdditionsStatus(VBoxGuestFacilityType_AutoLogon, enmStatus, 0 /* Flags */);
+        if (rc == VERR_NOT_SUPPORTED)
+        {
+            /*
+             * To maintain backwards compatibility to older hosts which don't have
+             * VMMDevReportGuestStatus implemented we set the appropriate status via
+             * guest property to have at least something.
+             */
+#ifdef VBOX_WITH_GUEST_PROPS
+            HGCMCLIENTID idClient = 0;
+            rc = VbglR3GuestPropConnect(&idClient);
+            if (RT_SUCCESS(rc))
+            {
+                const char *pszStatus;
+                switch (enmStatus)
+                {
+                    case VBoxGuestFacilityStatus_Inactive:      pszStatus = "Inactive"; break;
+                    case VBoxGuestFacilityStatus_Paused:        pszStatus = "Disabled"; break;
+                    case VBoxGuestFacilityStatus_PreInit:       pszStatus = "PreInit"; break;
+                    case VBoxGuestFacilityStatus_Init:          pszStatus = "Init"; break;
+                    case VBoxGuestFacilityStatus_Active:        pszStatus = "Active"; break;
+                    case VBoxGuestFacilityStatus_Terminating:   pszStatus = "Terminating"; break;
+                    case VBoxGuestFacilityStatus_Terminated:    pszStatus = "Terminated"; break;
+                    case VBoxGuestFacilityStatus_Failed:        pszStatus = "Failed"; break;
+                    default:                                    pszStatus = NULL;
+                }
+                if (pszStatus)
+                {
+                    /*
+                     * Use TRANSRESET when possible, fall back to TRANSIENT
+                     * (generally sufficient unless the guest misbehaves).
+                     */
+                    static const char s_szPath[] = "/VirtualBox/GuestInfo/OS/AutoLogonStatus";
+                    rc = VbglR3GuestPropWrite(idClient, s_szPath, pszStatus, "TRANSRESET");
+                    if (rc == VERR_PARSE_ERROR)
+                        rc = VbglR3GuestPropWrite(idClient, s_szPath, pszStatus, "TRANSIENT");
+                }
+                else
+                    rc = VERR_INVALID_PARAMETER;
+
+                VbglR3GuestPropDisconnect(idClient);
+            }
+#endif
+        }
+
+        s_enmLastStatus = enmStatus;
+    }
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Detects whether our process is running in a remote session or not.
+ *
+ * @return  bool        true if running in a remote session, false if not.
+ */
+VBGLR3DECL(bool) VbglR3AutoLogonIsRemoteSession(void)
+{
+#ifdef RT_OS_WINDOWS
+    return GetSystemMetrics(SM_REMOTESESSION) != 0 ? true : false;
+#else
+    return false; /* Not implemented. */
+#endif
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibBalloon.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibBalloon.cpp
new file mode 100644
index 00000000..b7b2a8f8
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibBalloon.cpp
@@ -0,0 +1,83 @@
+/* $Id: VBoxGuestR3LibBalloon.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, Ballooning.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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 "VBoxGuestR3LibInternal.h"
+#include <iprt/string.h>
+
+
+/**
+ * Refresh the memory balloon after a change.
+ *
+ * @returns IPRT status code.
+ * @param   pcChunks        The size of the balloon in chunks of 1MB (out).
+ * @param   pfHandleInR3    Allocating of memory in R3 required (out).
+ */
+VBGLR3DECL(int) VbglR3MemBalloonRefresh(uint32_t *pcChunks, bool *pfHandleInR3)
+{
+    VBGLIOCCHECKBALLOON Info;
+    VBGLREQHDR_INIT(&Info.Hdr, CHECK_BALLOON);
+    int rc = vbglR3DoIOCtl(VBGL_IOCTL_CHECK_BALLOON, &Info.Hdr, sizeof(Info));
+    if (RT_SUCCESS(rc))
+    {
+        *pcChunks = Info.u.Out.cBalloonChunks;
+        *pfHandleInR3 = Info.u.Out.fHandleInR3 != false;
+    }
+    return rc;
+}
+
+
+/**
+ * Change the memory by granting/reclaiming memory to/from R0.
+ *
+ * @returns IPRT status code.
+ * @param   pv          Memory chunk (1MB).
+ * @param   fInflate    true = inflate balloon (grant memory).
+ *                      false = deflate balloon (reclaim memory).
+ */
+VBGLR3DECL(int) VbglR3MemBalloonChange(void *pv, bool fInflate)
+{
+    VBGLIOCCHANGEBALLOON Info;
+    VBGLREQHDR_INIT(&Info.Hdr, CHANGE_BALLOON);
+    Info.u.In.pvChunk  = pv;
+    Info.u.In.fInflate = fInflate;
+    RT_ZERO(Info.u.In.abPadding);
+    return vbglR3DoIOCtl(VBGL_IOCTL_CHANGE_BALLOON, &Info.Hdr, sizeof(Info));
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibClipboard.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibClipboard.cpp
new file mode 100644
index 00000000..f44b923a
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibClipboard.cpp
@@ -0,0 +1,2609 @@
+/* $Id: VBoxGuestR3LibClipboard.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, Shared Clipboard.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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 <VBox/GuestHost/SharedClipboard.h>
+#include <VBox/GuestHost/clipboard-helper.h>
+#ifdef VBOX_WITH_SHARED_CLIPBOARD_TRANSFERS
+# include <VBox/GuestHost/SharedClipboard-transfers.h>
+#endif
+#include <VBox/HostServices/VBoxClipboardSvc.h>
+#include <VBox/err.h>
+#include <iprt/assert.h>
+#ifdef VBOX_WITH_SHARED_CLIPBOARD_TRANSFERS
+# include <iprt/dir.h>
+# include <iprt/file.h>
+# include <iprt/path.h>
+#endif
+#include <iprt/string.h>
+#include <iprt/cpp/ministring.h>
+
+#include "VBoxGuestR3LibInternal.h"
+
+
+/*
+ * Function naming convention:
+ *
+ * FunctionNameRecv  = Receives a host message (request).
+ * FunctionNameReply = Replies to a host message (request).
+ * FunctionNameSend  = Sends a guest message to the host.
+ */
+
+
+/*********************************************************************************************************************************
+*   Prototypes                                                                                                                   *
+*********************************************************************************************************************************/
+
+
+/**
+ * Connects to the Shared Clipboard service, legacy version, do not use anymore.
+ *
+ * @returns VBox status code
+ * @param   pidClient       Where to put the client id on success. The client id
+ *                          must be passed to all the other clipboard calls.
+ */
+VBGLR3DECL(int) VbglR3ClipboardConnect(HGCMCLIENTID *pidClient)
+{
+    int rc = VbglR3HGCMConnect("VBoxSharedClipboard", pidClient);
+    if (RT_FAILURE(rc))
+    {
+        if (rc == VERR_HGCM_SERVICE_NOT_FOUND)
+            LogRel(("Shared Clipboard: Unabled to connect, as host service was not found, skipping\n"));
+        else
+            LogRel(("Shared Clipboard: Unabled to connect to host service, rc=%Rrc\n", rc));
+    }
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+
+/**
+ * Connects to the Shared Clipboard service, extended version.
+ *
+ * @returns VBox status code.
+ * @param   pCtx            Command context.  This will be initialized by this
+ *                          call.
+ * @param   fGuestFeatures  The guest features supported by this client,
+ *                          VBOX_SHCL_GF_0_XXX.
+ */
+VBGLR3DECL(int) VbglR3ClipboardConnectEx(PVBGLR3SHCLCMDCTX pCtx, uint64_t fGuestFeatures)
+{
+    /*
+     * Intialize the context structure.
+     */
+    pCtx->idClient              = 0;
+    pCtx->fGuestFeatures        = fGuestFeatures;
+    pCtx->fHostFeatures         = 0;
+    pCtx->fUseLegacyProtocol    = true;
+    pCtx->cParmsRecived         = 0;
+    pCtx->idContext             = 0;
+
+#ifdef VBOX_WITH_SHARED_CLIPBOARD_TRANSFERS
+    /* Init callback table. */
+    RT_ZERO(pCtx->Transfers.Callbacks);
+    /* Indicate that this guest supports Shared Clipboard file transfers. */
+    pCtx->fGuestFeatures |= VBOX_SHCL_GF_0_TRANSFERS;
+# ifdef RT_OS_WINDOWS
+    /* Indicate that on Windows guest OSes we have our own IDataObject implementation which
+     * integrates nicely into the guest's Windows Explorer showing / handling the Shared Clipboard file transfers. */
+    pCtx->fGuestFeatures |= VBOX_SHCL_GF_0_TRANSFERS_FRONTEND;
+# endif
+    pCtx->Transfers.cbChunkSize    = VBOX_SHCL_DEFAULT_CHUNK_SIZE; /** @todo Make this configurable. */
+    pCtx->Transfers.cbMaxChunkSize = VBOX_SHCL_MAX_CHUNK_SIZE;     /** @todo Ditto. */
+#endif /* VBOX_WITH_SHARED_CLIPBOARD_TRANSFERS */
+
+    /*
+     * First step is connecting to the HGCM service.
+     */
+    int rc = VbglR3ClipboardConnect(&pCtx->idClient);
+    if (RT_SUCCESS(rc))
+    {
+        /*
+         * Next is reporting our features.  If this fails, assume older host.
+         */
+        rc = VbglR3ClipboardReportFeatures(pCtx->idClient, pCtx->fGuestFeatures, &pCtx->fHostFeatures);
+        if (RT_SUCCESS(rc))
+        {
+            LogRel2(("Shared Clipboard: Guest features: %#RX64 - Host features: %#RX64\n",
+                     pCtx->fGuestFeatures, pCtx->fHostFeatures));
+
+            if (   (pCtx->fHostFeatures & VBOX_SHCL_HF_0_CONTEXT_ID)
+                && (pCtx->fGuestFeatures & VBOX_SHCL_GF_0_CONTEXT_ID) )
+            {
+                pCtx->fUseLegacyProtocol = false;
+
+#ifdef VBOX_WITH_SHARED_CLIPBOARD_TRANSFERS
+                if (   (pCtx->fHostFeatures & VBOX_SHCL_HF_0_TRANSFERS)
+                    && (pCtx->fGuestFeatures & VBOX_SHCL_GF_0_TRANSFERS) )
+                {
+                    VBoxShClParmNegotiateChunkSize MsgChunkSize;
+                    do
+                    {
+                        VBGL_HGCM_HDR_INIT(&MsgChunkSize.hdr, pCtx->idClient, VBOX_SHCL_GUEST_FN_NEGOTIATE_CHUNK_SIZE,
+                                           VBOX_SHCL_CPARMS_NEGOTIATE_CHUNK_SIZE);
+                        MsgChunkSize.cb32MaxChunkSize.SetUInt32(pCtx->Transfers.cbMaxChunkSize);
+                        MsgChunkSize.cb32ChunkSize.SetUInt32(0); /* If set to 0, let the host choose. */
+                        rc = VbglR3HGCMCall(&MsgChunkSize.hdr, sizeof(MsgChunkSize));
+                    } while (rc == VERR_INTERRUPTED);
+                    if (RT_SUCCESS(rc))
+                    {
+                        Assert(MsgChunkSize.cb32ChunkSize.type == VMMDevHGCMParmType_32bit);
+                        pCtx->Transfers.cbChunkSize    = RT_MIN(MsgChunkSize.cb32ChunkSize.u.value32,    pCtx->Transfers.cbChunkSize);
+                        Assert(MsgChunkSize.cb32MaxChunkSize.type == VMMDevHGCMParmType_32bit);
+                        pCtx->Transfers.cbMaxChunkSize = RT_MIN(MsgChunkSize.cb32MaxChunkSize.u.value32, pCtx->Transfers.cbMaxChunkSize);
+
+                        LogRel2(("Shared Clipboard: Using chunk size %RU32 (maximum is %RU32)\n",
+                                 pCtx->Transfers.cbChunkSize, pCtx->Transfers.cbMaxChunkSize));
+                    }
+                }
+                else
+                {
+                    if (!(pCtx->fHostFeatures & VBOX_SHCL_HF_0_TRANSFERS))
+                        LogRel2(("Shared Clipboard: Host does not support transfers\n"));
+                }
+#endif /* VBOX_WITH_SHARED_CLIPBOARD_TRANSFERS */
+            }
+            else
+            {
+                if (!(pCtx->fHostFeatures & VBOX_SHCL_HF_0_CONTEXT_ID))
+                    LogRel(("Shared Clipboard: Host does not support context IDs, using legacy protocol\n"));
+
+                pCtx->fUseLegacyProtocol = true;
+            }
+        }
+        else
+        {
+            AssertLogRelMsg(rc == VERR_NOT_SUPPORTED || rc == VERR_NOT_IMPLEMENTED,
+                            ("Reporting features failed: %Rrc\n", rc));
+            pCtx->fUseLegacyProtocol = true;
+        }
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+
+/**
+ * Reports features to the host and retrieve host feature set.
+ *
+ * @returns VBox status code.
+ * @param   idClient        The client ID returned by VbglR3ClipboardConnect().
+ * @param   fGuestFeatures  Features to report, VBOX_SHCL_GF_XXX.
+ * @param   pfHostFeatures  Where to store the features VBOX_SHCL_HF_XXX.
+ */
+VBGLR3DECL(int) VbglR3ClipboardReportFeatures(uint32_t idClient, uint64_t fGuestFeatures, uint64_t *pfHostFeatures)
+{
+    int rc;
+    do
+    {
+        struct
+        {
+            VBGLIOCHGCMCALL         Hdr;
+            HGCMFunctionParameter   f64Features0;
+            HGCMFunctionParameter   f64Features1;
+        } Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.Hdr, idClient, VBOX_SHCL_GUEST_FN_REPORT_FEATURES, 2);
+        VbglHGCMParmUInt64Set(&Msg.f64Features0, fGuestFeatures);
+        VbglHGCMParmUInt64Set(&Msg.f64Features1, VBOX_SHCL_GF_1_MUST_BE_ONE);
+
+        rc = VbglR3HGCMCall(&Msg.Hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            Assert(Msg.f64Features0.type == VMMDevHGCMParmType_64bit);
+            Assert(Msg.f64Features1.type == VMMDevHGCMParmType_64bit);
+            if (Msg.f64Features1.u.value64 & VBOX_SHCL_GF_1_MUST_BE_ONE)
+                rc = VERR_NOT_SUPPORTED;
+            else if (pfHostFeatures)
+                *pfHostFeatures = Msg.f64Features0.u.value64;
+            break;
+        }
+    } while (rc == VERR_INTERRUPTED);
+    return rc;
+
+}
+
+
+/**
+ * Disconnects from the Shared Clipboard service, legacy version, do not use anymore.
+ *
+ * @returns VBox status code.
+ * @param   idClient        The client id returned by VbglR3ClipboardConnect().
+ */
+VBGLR3DECL(int) VbglR3ClipboardDisconnect(HGCMCLIENTID idClient)
+{
+    return VbglR3HGCMDisconnect(idClient);
+}
+
+
+/**
+ * Disconnects from the Shared Clipboard service, extended version.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ */
+VBGLR3DECL(int) VbglR3ClipboardDisconnectEx(PVBGLR3SHCLCMDCTX pCtx)
+{
+    int rc = VbglR3ClipboardDisconnect(pCtx->idClient);
+    if (RT_SUCCESS(rc))
+    {
+        pCtx->idClient = 0;
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+
+/**
+ * Receives reported formats from the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx        Shared Clipboard command context to use for the
+ *                      connection.
+ * @param   pfFormats   Where to store the received formats from the host.
+ */
+static int vbglR3ClipboardFormatsReportRecv(PVBGLR3SHCLCMDCTX pCtx, PSHCLFORMATS pfFormats)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+    AssertPtrReturn(pfFormats, VERR_INVALID_POINTER);
+
+    *pfFormats = 0;
+
+    struct
+    {
+        VBGLIOCHGCMCALL         Hdr;
+        HGCMFunctionParameter   id64Context;
+        HGCMFunctionParameter   f32Formats;
+    } Msg;
+
+    VBGL_HGCM_HDR_INIT(&Msg.Hdr, pCtx->idClient, VBOX_SHCL_GUEST_FN_MSG_GET, 2);
+    Msg.id64Context.SetUInt32(VBOX_SHCL_HOST_MSG_FORMATS_REPORT);
+    Msg.f32Formats.SetUInt32(0);
+
+    int rc = VbglR3HGCMCall(&Msg.Hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        rc = Msg.f32Formats.GetUInt32(pfFormats);
+        AssertRC(rc);
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+
+/**
+ * Fetches a VBOX_SHCL_HOST_MSG_READ_DATA_CID message.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   pfFormat            Where to return the requested format.
+ */
+static int vbglR3ClipboardFetchReadDataCid(PVBGLR3SHCLCMDCTX pCtx, PSHCLFORMAT pfFormat)
+{
+    AssertPtrReturn(pCtx,     VERR_INVALID_POINTER);
+    AssertPtrReturn(pfFormat, VERR_INVALID_POINTER);
+
+    struct
+    {
+        VBGLIOCHGCMCALL         Hdr;
+        HGCMFunctionParameter   id64Context;
+        HGCMFunctionParameter   f32Format;
+    } Msg;
+
+    VBGL_HGCM_HDR_INIT(&Msg.Hdr, pCtx->idClient, VBOX_SHCL_GUEST_FN_MSG_GET, 2);
+    Msg.id64Context.SetUInt64(VBOX_SHCL_HOST_MSG_READ_DATA_CID);
+    Msg.f32Format.SetUInt32(0);
+
+    int rc = VbglR3HGCMCall(&Msg.Hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        rc = Msg.id64Context.GetUInt64(&pCtx->idContext);
+        AssertRC(rc);
+        int rc2 = Msg.f32Format.GetUInt32(pfFormat);
+        AssertRCStmt(rc2, rc = rc2);
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+
+/**
+ * Fetches a VBOX_SHCL_HOST_MSG_READ_DATA message.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   pfFormat            Where to return the requested format.
+ */
+static int vbglR3ClipboardFetchReadData(PVBGLR3SHCLCMDCTX pCtx, PSHCLFORMAT pfFormat)
+{
+    AssertPtrReturn(pCtx,     VERR_INVALID_POINTER);
+    AssertPtrReturn(pfFormat, VERR_INVALID_POINTER);
+
+    struct
+    {
+        VBGLIOCHGCMCALL         Hdr;
+        HGCMFunctionParameter   id32Msg;
+        HGCMFunctionParameter   f32Format;
+    } Msg;
+
+    VBGL_HGCM_HDR_INIT(&Msg.Hdr, pCtx->idClient, VBOX_SHCL_GUEST_FN_MSG_GET, 2);
+    Msg.id32Msg.SetUInt32(VBOX_SHCL_HOST_MSG_READ_DATA);
+    Msg.f32Format.SetUInt32(0);
+
+    int rc = VbglR3HGCMCall(&Msg.Hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        rc = Msg.f32Format.GetUInt32(pfFormat);
+        AssertRC(rc);
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+
+/**
+ * Get a host message, legacy version (which does not have VBOX_SHCL_GUEST_FN_MSG_GET). Do not use anymore.
+ *
+ * Note: This is the old message which still is being used for the non-URI Shared Clipboard transfers,
+ *       to not break compatibility with older additions / VBox versions.
+ *
+ * This will block until a message becomes available.
+ *
+ * @returns VBox status code.
+ * @param   idClient        The client id returned by VbglR3ClipboardConnect().
+ * @param   pidMsg          Where to store the message id.
+ * @param   pfFormats       Where to store the format(s) the message applies to.
+ */
+VBGLR3DECL(int) VbglR3ClipboardGetHostMsgOld(HGCMCLIENTID idClient, uint32_t *pidMsg, uint32_t *pfFormats)
+{
+    VBoxShClGetHostMsgOld Msg;
+
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, idClient, VBOX_SHCL_GUEST_FN_MSG_OLD_GET_WAIT, VBOX_SHCL_CPARMS_GET_HOST_MSG_OLD);
+    VbglHGCMParmUInt32Set(&Msg.msg, 0);
+    VbglHGCMParmUInt32Set(&Msg.formats, 0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        int rc2 = VbglHGCMParmUInt32Get(&Msg.msg, pidMsg);
+        if (RT_SUCCESS(rc))
+        {
+            rc2 = VbglHGCMParmUInt32Get(&Msg.formats, pfFormats);
+            if (RT_SUCCESS(rc2))
+                return rc;
+        }
+        rc = rc2;
+    }
+    *pidMsg    = UINT32_MAX - 1;
+    *pfFormats = UINT32_MAX;
+    return rc;
+}
+
+
+/**
+ * Reads data from the host clipboard.
+ *
+ * Legacy function, do not use anymore.
+ *
+ * @returns VBox status code.
+ * @retval  VINF_BUFFER_OVERFLOW    If there is more data available than the caller provided buffer space for.
+ *
+ * @param   idClient        The client id returned by VbglR3ClipboardConnect().
+ * @param   fFormat         The format we're requesting the data in.
+ * @param   pvData          Where to store the data.
+ * @param   cbData          The size of the buffer pointed to by \a pvData.
+ * @param   pcbRead         The actual size of the host clipboard data. May be larger than \a cbData.
+ */
+VBGLR3DECL(int) VbglR3ClipboardReadData(HGCMCLIENTID idClient, uint32_t fFormat, void *pvData, uint32_t cbData,
+                                        uint32_t *pcbRead)
+{
+    LogFlowFuncEnter();
+
+    struct
+    {
+        VBGLIOCHGCMCALL      Hdr;
+        VBoxShClParmDataRead Parms;
+    } Msg;
+
+    VBGL_HGCM_HDR_INIT(&Msg.Hdr, idClient, VBOX_SHCL_GUEST_FN_DATA_READ, VBOX_SHCL_CPARMS_DATA_READ);
+    VbglHGCMParmUInt32Set(&Msg.Parms.f32Format,  fFormat);
+    VbglHGCMParmPtrSet(   &Msg.Parms.pData,      pvData, cbData);
+    VbglHGCMParmUInt32Set(&Msg.Parms.cb32Needed, 0);
+
+    int rc = VbglR3HGCMCall(&Msg.Hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        uint32_t cbRead;
+        rc = VbglHGCMParmUInt32Get(&Msg.Parms.cb32Needed, &cbRead);
+        if (RT_SUCCESS(rc))
+        {
+            LogFlowFunc(("cbRead=%RU32\n", cbRead));
+
+            if (cbRead > cbData)
+                rc = VINF_BUFFER_OVERFLOW;
+
+            *pcbRead = cbRead;
+        }
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+
+/**
+ * Reads clipboard data from the host clipboard.
+ *
+ * @returns VBox status code.
+ * @retval  VINF_BUFFER_OVERFLOW If there is more data available than the caller provided buffer space for.
+ *
+ * @param   pCtx                The command context returned by VbglR3ClipboardConnectEx().
+ * @param   uFormat             Clipboard format of clipboard data to be read.
+ * @param   pvData              Buffer where to store the read data.
+ * @param   cbData              Size (in bytes) of data buffer where to store the read data.
+ * @param   pcbRead             The actual size of the host clipboard data.
+ */
+VBGLR3DECL(int) VbglR3ClipboardReadDataEx(PVBGLR3SHCLCMDCTX pCtx,
+                                          SHCLFORMAT uFormat, void *pvData, uint32_t cbData, uint32_t *pcbRead)
+{
+    AssertPtrReturn(pCtx,   VERR_INVALID_POINTER);
+    AssertPtrReturn(pvData, VERR_INVALID_POINTER);
+    return VbglR3ClipboardReadData(pCtx->idClient, uFormat, pvData, cbData, pcbRead);
+}
+
+
+/**
+ * Query the host features.
+ *
+ * @returns VBox status code.
+ * @param   idClient        The client ID returned by VbglR3ClipboardConnect().
+ * @param   pfHostFeatures  Where to store the host feature, VBOX_SHCL_HF_XXX.
+ */
+VBGLR3DECL(int) VbglR3ClipboardQueryFeatures(uint32_t idClient, uint64_t *pfHostFeatures)
+{
+    int rc;
+    do
+    {
+        struct
+        {
+            VBGLIOCHGCMCALL         Hdr;
+            HGCMFunctionParameter   f64Features0;
+            HGCMFunctionParameter   f64Features1;
+        } Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.Hdr, idClient, VBOX_SHCL_GUEST_FN_QUERY_FEATURES, 2);
+        VbglHGCMParmUInt64Set(&Msg.f64Features0, 0);
+        VbglHGCMParmUInt64Set(&Msg.f64Features1, RT_BIT_64(63));
+
+        rc = VbglR3HGCMCall(&Msg.Hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            Assert(Msg.f64Features0.type == VMMDevHGCMParmType_64bit);
+            Assert(Msg.f64Features1.type == VMMDevHGCMParmType_64bit);
+            if (Msg.f64Features1.u.value64 & RT_BIT_64(63))
+                rc = VERR_NOT_SUPPORTED;
+            else if (pfHostFeatures)
+                *pfHostFeatures = Msg.f64Features0.u.value64;
+            break;
+        }
+    } while (rc == VERR_INTERRUPTED);
+    return rc;
+
+}
+
+/**
+ * Peeks at the next host message, waiting for one to turn up.
+ *
+ * This glosses over the difference between new (6.1) and old (1.3.2) host
+ * service versions, however it does so by abusing @a pcParameters, so don't use
+ * it directly when in legacy mode, always pass it on to
+ * VbglR3ClipboardEventGetNext() or VbglR3ClipboardEventGetNextEx().
+ *
+ * @returns VBox status code.
+ * @retval  VERR_INTERRUPTED if interrupted.  Does the necessary cleanup, so
+ *          caller just have to repeat this call.
+ * @retval  VERR_VM_RESTORED if the VM has been restored (idRestoreCheck).
+ *
+ * @param   pCtx            Shared Clipboard command context to use for the connection.
+ * @param   pidMsg          Where to store the message id.
+ * @param   pcParameters    Where to store the number  of parameters which will
+ *                          be received in a second call to the host.
+ * @param   pidRestoreCheck Pointer to the VbglR3GetSessionId() variable to use
+ *                          for the VM restore check.  Optional.
+ *
+ * @note    Restore check is only performed optimally with a 6.0 host.
+ */
+VBGLR3DECL(int) VbglR3ClipboardMsgPeekWait(PVBGLR3SHCLCMDCTX pCtx, uint32_t *pidMsg,
+                                           uint32_t *pcParameters, uint64_t *pidRestoreCheck)
+{
+    AssertPtrReturn(pidMsg, VERR_INVALID_POINTER);
+    AssertPtrReturn(pcParameters, VERR_INVALID_POINTER);
+
+    struct
+    {
+        VBGLIOCHGCMCALL Hdr;
+        HGCMFunctionParameter idMsg;       /* Doubles as restore check on input. */
+        HGCMFunctionParameter cParameters;
+    } Msg;
+    int rc;
+    if (!pCtx->fUseLegacyProtocol)
+    {
+        VBGL_HGCM_HDR_INIT(&Msg.Hdr, pCtx->idClient, VBOX_SHCL_GUEST_FN_MSG_PEEK_WAIT, 2);
+        VbglHGCMParmUInt64Set(&Msg.idMsg, pidRestoreCheck ? *pidRestoreCheck : 0);
+        VbglHGCMParmUInt32Set(&Msg.cParameters, 0);
+        rc = VbglR3HGCMCall(&Msg.Hdr, sizeof(Msg));
+        LogFlowFunc(("VbglR3HGCMCall -> %Rrc\n", rc));
+        if (RT_SUCCESS(rc))
+        {
+            AssertMsgReturn(   Msg.idMsg.type       == VMMDevHGCMParmType_64bit
+                            && Msg.cParameters.type == VMMDevHGCMParmType_32bit,
+                            ("msg.type=%d num_parms.type=%d\n", Msg.idMsg.type, Msg.cParameters.type),
+                            VERR_INTERNAL_ERROR_3);
+
+            *pidMsg       = (uint32_t)Msg.idMsg.u.value64;
+            *pcParameters = Msg.cParameters.u.value32;
+            return rc;
+        }
+
+        /*
+         * If restored, update pidRestoreCheck.
+         */
+        if (rc == VERR_VM_RESTORED && pidRestoreCheck)
+            *pidRestoreCheck = Msg.idMsg.u.value64;
+    }
+    else
+    {
+        /*
+         * We do some crude stuff here by putting the 2nd parameter (foramts) in the parameter count,
+         * however it's supposed to be passed directly to VbglR3ClipboardEventGetNext or
+         * VbglR3ClipboardEventGetNextEx, so that's fine...
+         */
+        rc = VbglR3ClipboardGetHostMsgOld(pCtx->idClient, pidMsg, pcParameters);
+        if (RT_SUCCESS(rc))
+            return rc;
+    }
+
+    /*
+     * If interrupted we must cancel the call so it doesn't prevent us from making another one.
+     */
+    if (rc == VERR_INTERRUPTED)
+    {
+        VBGL_HGCM_HDR_INIT(&Msg.Hdr, pCtx->idClient, VBOX_SHCL_GUEST_FN_MSG_CANCEL, 0);
+        int rc2 = VbglR3HGCMCall(&Msg.Hdr, sizeof(Msg.Hdr));
+        AssertRC(rc2);
+    }
+
+    *pidMsg       = UINT32_MAX - 1;
+    *pcParameters = UINT32_MAX - 2;
+    return rc;
+}
+
+#ifdef VBOX_WITH_SHARED_CLIPBOARD_TRANSFERS
+
+/**
+ * Reads a root list header from the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   pRootListHdr        Where to store the received root list header.
+ */
+static int vbglR3ClipboardRootListHdrRead(PVBGLR3SHCLCMDCTX pCtx, PSHCLROOTLISTHDR pRootListHdr)
+{
+    AssertPtrReturn(pCtx,         VERR_INVALID_POINTER);
+    AssertPtrReturn(pRootListHdr, VERR_INVALID_POINTER);
+
+    VBoxShClRootListHdrMsg Msg;
+
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_ROOT_LIST_HDR_READ, VBOX_SHCL_CPARMS_ROOT_LIST_HDR_READ);
+
+    Msg.ReqParms.uContext.SetUInt64(pCtx->idContext);
+    Msg.ReqParms.fRoots.SetUInt32(0);
+
+    Msg.cRoots.SetUInt32(0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        rc = Msg.ReqParms.fRoots.GetUInt32(&pRootListHdr->fRoots); AssertRC(rc);
+        if (RT_SUCCESS(rc))
+        {
+            rc = Msg.cRoots.GetUInt32(&pRootListHdr->cRoots);
+            AssertRC(rc);
+        }
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Reads a root list entry from the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   uIndex              Index of root list entry to read.
+ * @param   pRootListEntry      Where to store the root list entry read from the host.
+ */
+static int vbglR3ClipboardRootListEntryRead(PVBGLR3SHCLCMDCTX pCtx, uint32_t uIndex, PSHCLROOTLISTENTRY pRootListEntry)
+{
+    AssertPtrReturn(pCtx,           VERR_INVALID_POINTER);
+    AssertPtrReturn(pRootListEntry, VERR_INVALID_POINTER);
+
+    VBoxShClRootListEntryMsg Msg;
+
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_ROOT_LIST_ENTRY_READ, VBOX_SHCL_CPARMS_ROOT_LIST_ENTRY_READ);
+
+    Msg.Parms.uContext.SetUInt64(pCtx->idContext);
+    Msg.Parms.fInfo.SetUInt32(pRootListEntry->fInfo);
+    Msg.Parms.uIndex.SetUInt32(uIndex);
+
+    Msg.szName.SetPtr(pRootListEntry->pszName, pRootListEntry->cbName);
+    Msg.cbInfo.SetUInt32(pRootListEntry->cbInfo);
+    Msg.pvInfo.SetPtr(pRootListEntry->pvInfo, pRootListEntry->cbInfo);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        rc = Msg.Parms.fInfo.GetUInt32(&pRootListEntry->fInfo); AssertRC(rc);
+        if (RT_SUCCESS(rc))
+        {
+            uint32_t cbInfo = 0;
+            rc = Msg.cbInfo.GetUInt32(&cbInfo); AssertRC(rc);
+            if (pRootListEntry->cbInfo != cbInfo)
+                rc = VERR_INVALID_PARAMETER;
+        }
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Reads the root list from the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   ppRootList          Where to store the (allocated) root list. Must be free'd by the caller with
+ *                              SharedClipboardTransferRootListFree().
+ */
+VBGLR3DECL(int) VbglR3ClipboardRootListRead(PVBGLR3SHCLCMDCTX pCtx, PSHCLROOTLIST *ppRootList)
+{
+    AssertPtrReturn(pCtx,       VERR_INVALID_POINTER);
+    AssertPtrReturn(ppRootList, VERR_INVALID_POINTER);
+
+    int rc;
+
+    PSHCLROOTLIST pRootList = ShClTransferRootListAlloc();
+    if (pRootList)
+    {
+        SHCLROOTLISTHDR srcRootListHdr;
+        rc = vbglR3ClipboardRootListHdrRead(pCtx, &srcRootListHdr);
+        if (RT_SUCCESS(rc))
+        {
+            pRootList->Hdr.cRoots = srcRootListHdr.cRoots;
+            pRootList->Hdr.fRoots = 0; /** @todo Implement this. */
+
+            if (srcRootListHdr.cRoots)
+            {
+                pRootList->paEntries =
+                    (PSHCLROOTLISTENTRY)RTMemAllocZ(srcRootListHdr.cRoots * sizeof(SHCLROOTLISTENTRY));
+                if (pRootList->paEntries)
+                {
+                    for (uint32_t i = 0; i < srcRootListHdr.cRoots; i++)
+                    {
+                        SHCLROOTLISTENTRY *pEntry = &pRootList->paEntries[i];
+                        AssertPtr(pEntry);
+
+                        rc = ShClTransferRootListEntryInit(pEntry);
+                        if (RT_SUCCESS(rc))
+                            rc = vbglR3ClipboardRootListEntryRead(pCtx, i, pEntry);
+
+                        if (RT_FAILURE(rc))
+                            break;
+                    }
+                }
+                else
+                    rc = VERR_NO_MEMORY;
+            }
+        }
+
+        if (RT_SUCCESS(rc))
+        {
+            *ppRootList = pRootList;
+        }
+        else
+            ShClTransferRootListFree(pRootList);
+    }
+    else
+        rc = VERR_NO_MEMORY;
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Receives a transfer status from the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   pEnmDir             Where to store the transfer direction for the reported transfer.
+ * @param   pReport             Where to store the transfer (status) report.
+ */
+VBGLR3DECL(int) VbglR3ClipboarTransferStatusRecv(PVBGLR3SHCLCMDCTX pCtx,
+                                                 PSHCLTRANSFERDIR pEnmDir, PSHCLTRANSFERREPORT pReport)
+{
+    AssertPtrReturn(pCtx,    VERR_INVALID_POINTER);
+    AssertPtrReturn(pReport, VERR_INVALID_POINTER);
+    AssertPtrReturn(pEnmDir, VERR_INVALID_POINTER);
+
+    VBoxShClTransferStatusMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_MSG_GET, VBOX_SHCL_CPARMS_TRANSFER_STATUS);
+
+    Msg.uContext.SetUInt64(VBOX_SHCL_HOST_MSG_TRANSFER_STATUS);
+    Msg.enmDir.SetUInt32(0);
+    Msg.enmStatus.SetUInt32(0);
+    Msg.rc.SetUInt32(0);
+    Msg.fFlags.SetUInt32(0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        rc = Msg.uContext.GetUInt64(&pCtx->idContext); AssertRC(rc);
+        if (RT_SUCCESS(rc))
+        {
+            rc = Msg.enmDir.GetUInt32((uint32_t *)pEnmDir);
+            AssertRC(rc);
+        }
+        if (RT_SUCCESS(rc))
+        {
+            rc = Msg.enmStatus.GetUInt32(&pReport->uStatus);
+            AssertRC(rc);
+        }
+        if (RT_SUCCESS(rc))
+        {
+            rc = Msg.rc.GetUInt32((uint32_t *)&pReport->rc);
+            AssertRC(rc);
+        }
+        if (RT_SUCCESS(rc))
+        {
+            rc = Msg.fFlags.GetUInt32(&pReport->fFlags);
+            AssertRC(rc);
+        }
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Replies to a transfer report from the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   pTransfer           Transfer of report to reply to.
+ * @param   uStatus             Tranfer status to reply.
+ * @param   rcTransfer          Result code (rc) to reply.
+ */
+VBGLR3DECL(int) VbglR3ClipboardTransferStatusReply(PVBGLR3SHCLCMDCTX pCtx, PSHCLTRANSFER pTransfer,
+                                                   SHCLTRANSFERSTATUS uStatus, int rcTransfer)
+{
+    AssertPtrReturn(pCtx,      VERR_INVALID_POINTER);
+    AssertPtrReturn(pTransfer, VERR_INVALID_POINTER);
+
+    RT_NOREF(pTransfer);
+
+    VBoxShClReplyMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_REPLY, VBOX_SHCL_CPARMS_REPLY_MIN + 1);
+
+    Msg.uContext.SetUInt64(pCtx->idContext);
+    Msg.enmType.SetUInt32(VBOX_SHCL_REPLYMSGTYPE_TRANSFER_STATUS);
+    Msg.rc.SetUInt32((uint32_t )rcTransfer); /* int vs. uint32_t */
+    Msg.pvPayload.SetPtr(NULL, 0);
+
+    Msg.u.TransferStatus.enmStatus.SetUInt32((uint32_t)uStatus);
+
+    LogFlowFunc(("%s\n", ShClTransferStatusToStr(uStatus)));
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Receives a host request to read a root list header from the guest.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   pfRoots             Where to store the root list header flags to use, requested by the host.
+ */
+VBGLR3DECL(int) VbglR3ClipboardRootListHdrReadReq(PVBGLR3SHCLCMDCTX pCtx, uint32_t *pfRoots)
+{
+    AssertPtrReturn(pCtx,    VERR_INVALID_POINTER);
+    AssertPtrReturn(pfRoots, VERR_INVALID_POINTER);
+
+    VBoxShClRootListReadReqMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_MSG_GET, VBOX_SHCL_CPARMS_ROOT_LIST_HDR_READ_REQ);
+
+    Msg.ReqParms.uContext.SetUInt64(VBOX_SHCL_HOST_MSG_TRANSFER_ROOT_LIST_HDR_READ);
+    Msg.ReqParms.fRoots.SetUInt32(0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        rc = Msg.ReqParms.uContext.GetUInt64(&pCtx->idContext); AssertRC(rc);
+        if (RT_SUCCESS(rc))
+        {
+            rc = Msg.ReqParms.fRoots.GetUInt32(pfRoots);
+            AssertRC(rc);
+        }
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Replies to a root list header request.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   pRootListHdr        Root lsit header to reply to the host.
+ */
+VBGLR3DECL(int) VbglR3ClipboardRootListHdrReadReply(PVBGLR3SHCLCMDCTX pCtx, PSHCLROOTLISTHDR pRootListHdr)
+{
+    AssertPtrReturn(pCtx,         VERR_INVALID_POINTER);
+    AssertPtrReturn(pRootListHdr, VERR_INVALID_POINTER);
+
+    VBoxShClRootListHdrMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_ROOT_LIST_HDR_WRITE, VBOX_SHCL_CPARMS_ROOT_LIST_HDR_WRITE);
+
+    Msg.ReqParms.uContext.SetUInt64(pCtx->idContext);
+    Msg.ReqParms.fRoots.SetUInt32(pRootListHdr->fRoots);
+
+    Msg.cRoots.SetUInt32(pRootListHdr->cRoots);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Receives a host request to read a root list entry from the guest.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   puIndex             Where to return the index of the root list entry the host wants to read.
+ * @param   pfInfo              Where to return the read flags the host wants to use.
+ */
+VBGLR3DECL(int) VbglR3ClipboardRootListEntryReadReq(PVBGLR3SHCLCMDCTX pCtx, uint32_t *puIndex, uint32_t *pfInfo)
+{
+    AssertPtrReturn(pCtx,    VERR_INVALID_POINTER);
+    AssertPtrReturn(puIndex, VERR_INVALID_POINTER);
+    AssertPtrReturn(pfInfo,  VERR_INVALID_POINTER);
+
+    VBoxShClRootListEntryReadReqMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_MSG_GET, VBOX_SHCL_CPARMS_ROOT_LIST_ENTRY_READ_REQ);
+
+    Msg.Parms.uContext.SetUInt64(VBOX_SHCL_HOST_MSG_TRANSFER_ROOT_LIST_ENTRY_READ);
+    Msg.Parms.fInfo.SetUInt32(0);
+    Msg.Parms.uIndex.SetUInt32(0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        rc = Msg.Parms.uContext.GetUInt64(&pCtx->idContext); AssertRC(rc);
+        if (RT_SUCCESS(rc))
+        {
+            rc = Msg.Parms.fInfo.GetUInt32(pfInfo);
+            AssertRC(rc);
+        }
+        if (RT_SUCCESS(rc))
+        {
+            rc = Msg.Parms.uIndex.GetUInt32(puIndex);
+            AssertRC(rc);
+        }
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Replies to a root list entry read request from the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   uIndex              Index of root list entry to reply.
+ * @param   pEntry              Actual root list entry to reply.
+ */
+VBGLR3DECL(int) VbglR3ClipboardRootListEntryReadReply(PVBGLR3SHCLCMDCTX pCtx, uint32_t uIndex, PSHCLROOTLISTENTRY pEntry)
+{
+    AssertPtrReturn(pCtx,   VERR_INVALID_POINTER);
+    AssertPtrReturn(pEntry, VERR_INVALID_POINTER);
+
+    VBoxShClRootListEntryMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_ROOT_LIST_ENTRY_WRITE, VBOX_SHCL_CPARMS_ROOT_LIST_ENTRY_WRITE);
+
+    Msg.Parms.uContext.SetUInt64(pCtx->idContext);
+    Msg.Parms.fInfo.SetUInt32(0);
+    Msg.Parms.uIndex.SetUInt32(uIndex);
+
+    Msg.szName.SetPtr(pEntry->pszName, pEntry->cbName);
+    Msg.cbInfo.SetUInt32(pEntry->cbInfo);
+    Msg.pvInfo.SetPtr(pEntry->pvInfo, pEntry->cbInfo);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Sends a request to open a list handle to the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   pOpenParms          List open parameters to use for the open request.
+ * @param   phList              Where to return the list handle received from the host.
+ */
+VBGLR3DECL(int) VbglR3ClipboardListOpenSend(PVBGLR3SHCLCMDCTX pCtx, PSHCLLISTOPENPARMS pOpenParms,
+                                            PSHCLLISTHANDLE phList)
+{
+    AssertPtrReturn(pCtx,       VERR_INVALID_POINTER);
+    AssertPtrReturn(pOpenParms, VERR_INVALID_POINTER);
+    AssertPtrReturn(phList,     VERR_INVALID_POINTER);
+
+    VBoxShClListOpenMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_LIST_OPEN, VBOX_SHCL_CPARMS_LIST_OPEN);
+
+    Msg.uContext.SetUInt64(pCtx->idContext);
+    Msg.fList.SetUInt32(0);
+    Msg.pvFilter.SetPtr(pOpenParms->pszFilter, pOpenParms->cbFilter);
+    Msg.pvPath.SetPtr(pOpenParms->pszPath, pOpenParms->cbPath);
+    Msg.uHandle.SetUInt64(0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        rc = Msg.uHandle.GetUInt64(phList); AssertRC(rc);
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Receives a host request to open a list handle on the guest.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   pOpenParms          Where to store the open parameters the host wants to use for opening the list handle.
+ */
+VBGLR3DECL(int) VbglR3ClipboardListOpenRecv(PVBGLR3SHCLCMDCTX pCtx, PSHCLLISTOPENPARMS pOpenParms)
+{
+    AssertPtrReturn(pCtx,       VERR_INVALID_POINTER);
+    AssertPtrReturn(pOpenParms, VERR_INVALID_POINTER);
+
+    VBoxShClListOpenMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_MSG_GET, VBOX_SHCL_CPARMS_LIST_OPEN);
+
+    Msg.uContext.SetUInt64(VBOX_SHCL_HOST_MSG_TRANSFER_LIST_OPEN);
+    Msg.fList.SetUInt32(0);
+    Msg.pvPath.SetPtr(pOpenParms->pszPath, pOpenParms->cbPath);
+    Msg.pvFilter.SetPtr(pOpenParms->pszFilter, pOpenParms->cbFilter);
+    Msg.uHandle.SetUInt64(0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        rc = Msg.uContext.GetUInt64(&pCtx->idContext);
+        if (RT_SUCCESS(rc))
+            rc = Msg.fList.GetUInt32(&pOpenParms->fList);
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Replies to a list open request from the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   rcReply             Return code to reply to the host.
+ * @param   hList               List handle of (guest) list to reply to the host.
+ */
+VBGLR3DECL(int) VbglR3ClipboardListOpenReply(PVBGLR3SHCLCMDCTX pCtx, int rcReply, SHCLLISTHANDLE hList)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    VBoxShClReplyMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_REPLY, VBOX_SHCL_CPARMS_REPLY_MIN + 1);
+
+    Msg.uContext.SetUInt64(pCtx->idContext);
+    Msg.enmType.SetUInt32(VBOX_SHCL_REPLYMSGTYPE_LIST_OPEN);
+    Msg.rc.SetUInt32((uint32_t)rcReply); /** int vs. uint32_t */
+    Msg.pvPayload.SetPtr(NULL, 0);
+
+    Msg.u.ListOpen.uHandle.SetUInt64(hList);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Receives a host request to close a list handle on the guest.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   phList              Where to store the list handle to close, received from the host.
+ */
+VBGLR3DECL(int) VbglR3ClipboardListCloseRecv(PVBGLR3SHCLCMDCTX pCtx, PSHCLLISTHANDLE phList)
+{
+    AssertPtrReturn(pCtx,   VERR_INVALID_POINTER);
+    AssertPtrReturn(phList, VERR_INVALID_POINTER);
+
+    VBoxShClListCloseMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_MSG_GET, VBOX_SHCL_CPARMS_LIST_CLOSE);
+
+    Msg.uContext.SetUInt64(VBOX_SHCL_HOST_MSG_TRANSFER_LIST_CLOSE);
+    Msg.uHandle.SetUInt64(0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        rc = Msg.uContext.GetUInt64(&pCtx->idContext);
+        if (RT_SUCCESS(rc))
+        {
+            rc = Msg.uHandle.GetUInt64(phList);
+            AssertRC(rc);
+        }
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Replies to a list handle close request from the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   rcReply             Return code to reply to the host.
+ * @param   hList               List handle the send the close reply for.
+ */
+VBGLR3DECL(int) VbglR3ClipboardListCloseReply(PVBGLR3SHCLCMDCTX pCtx, int rcReply, SHCLLISTHANDLE hList)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    VBoxShClReplyMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_REPLY, VBOX_SHCL_CPARMS_REPLY_MIN + 1);
+
+    Msg.uContext.SetUInt64(pCtx->idContext);
+    Msg.enmType.SetUInt32(VBOX_SHCL_REPLYMSGTYPE_LIST_CLOSE);
+    Msg.rc.SetUInt32((uint32_t)rcReply); /** int vs. uint32_t */
+    Msg.pvPayload.SetPtr(NULL, 0);
+
+    Msg.u.ListOpen.uHandle.SetUInt64(hList);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Sends a request to close a list handle to the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   hList               List handle to request for closing on the host.
+ */
+VBGLR3DECL(int) VbglR3ClipboardListCloseSend(PVBGLR3SHCLCMDCTX pCtx, SHCLLISTHANDLE hList)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    VBoxShClListCloseMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_LIST_CLOSE, VBOX_SHCL_CPARMS_LIST_CLOSE);
+
+    Msg.uContext.SetUInt64(pCtx->idContext);
+    Msg.uHandle.SetUInt64(hList);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Sends a request to read a list header to the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   hList               List handle to read list header for.
+ * @param   fFlags              List header read flags to use.
+ * @param   pListHdr            Where to return the list header received from the host.
+ */
+VBGLR3DECL(int) VbglR3ClipboardListHdrRead(PVBGLR3SHCLCMDCTX pCtx, SHCLLISTHANDLE hList, uint32_t fFlags,
+                                           PSHCLLISTHDR pListHdr)
+{
+    AssertPtrReturn(pCtx,     VERR_INVALID_POINTER);
+    AssertPtrReturn(pListHdr, VERR_INVALID_POINTER);
+
+    VBoxShClListHdrMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_LIST_HDR_READ, VBOX_SHCL_CPARMS_LIST_HDR);
+
+    Msg.ReqParms.uContext.SetUInt64(pCtx->idContext);
+    Msg.ReqParms.uHandle.SetUInt64(hList);
+    Msg.ReqParms.fFlags.SetUInt32(fFlags);
+
+    Msg.fFeatures.SetUInt32(0);
+    Msg.cbTotalSize.SetUInt32(0);
+    Msg.cTotalObjects.SetUInt64(0);
+    Msg.cbTotalSize.SetUInt64(0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        rc = Msg.fFeatures.GetUInt32(&pListHdr->fFeatures);
+        if (RT_SUCCESS(rc))
+            rc = Msg.cTotalObjects.GetUInt64(&pListHdr->cTotalObjects);
+        if (RT_SUCCESS(rc))
+            rc = Msg.cbTotalSize.GetUInt64(&pListHdr->cbTotalSize);
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Receives a host request to read a list header on the guest.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   phList              Where to return the list handle to read list header for.
+ * @param   pfFlags             Where to return the List header read flags to use.
+ */
+VBGLR3DECL(int) VbglR3ClipboardListHdrReadRecvReq(PVBGLR3SHCLCMDCTX pCtx, PSHCLLISTHANDLE phList, uint32_t *pfFlags)
+{
+    AssertPtrReturn(pCtx,    VERR_INVALID_POINTER);
+    AssertPtrReturn(phList,  VERR_INVALID_POINTER);
+    AssertPtrReturn(pfFlags, VERR_INVALID_POINTER);
+
+    VBoxShClListHdrReadReqMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_MSG_GET, VBOX_SHCL_CPARMS_LIST_HDR_READ_REQ);
+
+    Msg.ReqParms.uContext.SetUInt64(VBOX_SHCL_HOST_MSG_TRANSFER_LIST_HDR_READ);
+    Msg.ReqParms.uHandle.SetUInt64(0);
+    Msg.ReqParms.fFlags.SetUInt32(0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        rc = Msg.ReqParms.uContext.GetUInt64(&pCtx->idContext);
+        if (RT_SUCCESS(rc))
+            rc = Msg.ReqParms.uHandle.GetUInt64(phList);
+        if (RT_SUCCESS(rc))
+            rc = Msg.ReqParms.fFlags.GetUInt32(pfFlags);
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Sends (writes) a list header to the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   hList               List handle to write list header for.
+ * @param   pListHdr            List header to write.
+ */
+VBGLR3DECL(int) VbglR3ClipboardListHdrWrite(PVBGLR3SHCLCMDCTX pCtx, SHCLLISTHANDLE hList,
+                                            PSHCLLISTHDR pListHdr)
+{
+    AssertPtrReturn(pCtx,     VERR_INVALID_POINTER);
+    AssertPtrReturn(pListHdr, VERR_INVALID_POINTER);
+
+    VBoxShClListHdrMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_LIST_HDR_WRITE, VBOX_SHCL_CPARMS_LIST_HDR);
+
+    Msg.ReqParms.uContext.SetUInt64(pCtx->idContext);
+    Msg.ReqParms.uHandle.SetUInt64(hList);
+    Msg.ReqParms.fFlags.SetUInt32(0);
+
+    Msg.fFeatures.SetUInt32(0);
+    Msg.cbTotalSize.SetUInt32(pListHdr->fFeatures);
+    Msg.cTotalObjects.SetUInt64(pListHdr->cTotalObjects);
+    Msg.cbTotalSize.SetUInt64(pListHdr->cbTotalSize);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Sends a request to read a list entry from the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   hList               List handle to request to read a list entry for.
+ * @param   pListEntry          Where to return the list entry read from the host.
+ */
+VBGLR3DECL(int) VbglR3ClipboardListEntryRead(PVBGLR3SHCLCMDCTX pCtx, SHCLLISTHANDLE hList,
+                                             PSHCLLISTENTRY pListEntry)
+{
+    AssertPtrReturn(pCtx,       VERR_INVALID_POINTER);
+    AssertPtrReturn(pListEntry, VERR_INVALID_POINTER);
+
+    VBoxShClListEntryMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_LIST_ENTRY_READ, VBOX_SHCL_CPARMS_LIST_ENTRY);
+
+    Msg.ReqParms.uContext.SetUInt64(pCtx->idContext);
+    Msg.ReqParms.uHandle.SetUInt64(hList);
+    Msg.ReqParms.fInfo.SetUInt32(0);
+
+    Msg.szName.SetPtr(pListEntry->pszName, pListEntry->cbName);
+    Msg.cbInfo.SetUInt32(pListEntry->cbInfo);
+    Msg.pvInfo.SetPtr(pListEntry->pvInfo, pListEntry->cbInfo);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        rc = Msg.cbInfo.GetUInt32(&pListEntry->cbInfo); AssertRC(rc);
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Receives a host request to read a list entry from the guest.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   phList              Where to return the list handle to read a list entry for.
+ * @param   pfInfo              Where to return the list read flags.
+ */
+VBGLR3DECL(int) VbglR3ClipboardListEntryReadRecvReq(PVBGLR3SHCLCMDCTX pCtx, PSHCLLISTHANDLE phList, uint32_t *pfInfo)
+{
+    AssertPtrReturn(pCtx,   VERR_INVALID_POINTER);
+    AssertPtrReturn(phList, VERR_INVALID_POINTER);
+    AssertPtrReturn(pfInfo, VERR_INVALID_POINTER);
+
+    VBoxShClListEntryReadReqMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_MSG_GET, VBOX_SHCL_CPARMS_LIST_ENTRY_READ);
+
+    Msg.ReqParms.uContext.SetUInt64(VBOX_SHCL_HOST_MSG_TRANSFER_LIST_ENTRY_READ);
+    Msg.ReqParms.uHandle.SetUInt64(0);
+    Msg.ReqParms.fInfo.SetUInt32(0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        rc = Msg.ReqParms.uContext.GetUInt64(&pCtx->idContext);
+        if (RT_SUCCESS(rc))
+        {
+            rc = Msg.ReqParms.uHandle.GetUInt64(phList);
+            AssertRC(rc);
+        }
+        if (RT_SUCCESS(rc))
+        {
+            rc = Msg.ReqParms.fInfo.GetUInt32(pfInfo);
+            AssertRC(rc);
+        }
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Sends (writes) a list entry to the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   hList               List handle to write a list etnry for.
+ * @param   pListEntry          List entry to write.
+ */
+VBGLR3DECL(int) VbglR3ClipboardListEntryWrite(PVBGLR3SHCLCMDCTX pCtx, SHCLLISTHANDLE hList,
+                                              PSHCLLISTENTRY pListEntry)
+{
+    AssertPtrReturn(pCtx,       VERR_INVALID_POINTER);
+    AssertPtrReturn(pListEntry, VERR_INVALID_POINTER);
+
+    VBoxShClListEntryMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_LIST_ENTRY_WRITE, VBOX_SHCL_CPARMS_LIST_ENTRY);
+
+    Msg.ReqParms.uContext.SetUInt64(pCtx->idContext);
+    Msg.ReqParms.uHandle.SetUInt64(hList);
+    Msg.ReqParms.fInfo.SetUInt32(pListEntry->fInfo);
+
+    Msg.szName.SetPtr(pListEntry->pszName, pListEntry->cbName);
+    Msg.cbInfo.SetUInt32(pListEntry->cbInfo);
+    Msg.pvInfo.SetPtr(pListEntry->pvInfo, pListEntry->cbInfo);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Receives a host request to open an object on the guest.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   pCreateParms        Where to store the object open/create parameters received from the host.
+ */
+VBGLR3DECL(int) VbglR3ClipboardObjOpenRecv(PVBGLR3SHCLCMDCTX pCtx, PSHCLOBJOPENCREATEPARMS pCreateParms)
+{
+    AssertPtrReturn(pCtx,         VERR_INVALID_POINTER);
+    AssertPtrReturn(pCreateParms, VERR_INVALID_POINTER);
+
+    VBoxShClObjOpenMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_MSG_GET, VBOX_SHCL_CPARMS_OBJ_OPEN);
+
+    Msg.uContext.SetUInt64(VBOX_SHCL_HOST_MSG_TRANSFER_OBJ_OPEN);
+    Msg.uHandle.SetUInt64(0);
+    Msg.szPath.SetPtr(pCreateParms->pszPath, pCreateParms->cbPath);
+    Msg.fCreate.SetUInt32(0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        rc = Msg.uContext.GetUInt64(&pCtx->idContext);
+        if (RT_SUCCESS(rc))
+            rc = Msg.fCreate.GetUInt32(&pCreateParms->fCreate);
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Replies a host request to open an object.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   rcReply             Return code to reply to the host.
+ * @param   hObj                Object handle of opened object to reply to the host.
+ */
+VBGLR3DECL(int) VbglR3ClipboardObjOpenReply(PVBGLR3SHCLCMDCTX pCtx, int rcReply, SHCLOBJHANDLE hObj)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    VBoxShClReplyMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_REPLY, VBOX_SHCL_CPARMS_REPLY_MIN + 1);
+
+    Msg.uContext.SetUInt64(pCtx->idContext);
+    Msg.enmType.SetUInt32(VBOX_SHCL_REPLYMSGTYPE_OBJ_OPEN);
+    Msg.rc.SetUInt32((uint32_t)rcReply); /** int vs. uint32_t */
+    Msg.pvPayload.SetPtr(NULL, 0);
+
+    Msg.u.ObjOpen.uHandle.SetUInt64(hObj);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Sends an object open request to the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   pCreateParms        Object open/create parameters to use for opening the object on the host.
+ * @param   phObj               Where to return the object handle from the host.
+ */
+VBGLR3DECL(int) VbglR3ClipboardObjOpenSend(PVBGLR3SHCLCMDCTX pCtx, PSHCLOBJOPENCREATEPARMS pCreateParms,
+                                           PSHCLOBJHANDLE phObj)
+{
+    AssertPtrReturn(pCtx,         VERR_INVALID_POINTER);
+    AssertPtrReturn(pCreateParms, VERR_INVALID_POINTER);
+    AssertPtrReturn(phObj,        VERR_INVALID_POINTER);
+
+    VBoxShClObjOpenMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_OBJ_OPEN, VBOX_SHCL_CPARMS_OBJ_OPEN);
+
+    Msg.uContext.SetUInt64(pCtx->idContext);
+    Msg.uHandle.SetUInt64(0);
+    Msg.szPath.SetPtr((void *)pCreateParms->pszPath, pCreateParms->cbPath);
+    Msg.fCreate.SetUInt32(pCreateParms->fCreate);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        Msg.uHandle.GetUInt64(phObj);
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Receives a host request to close an object on the guest.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   phObj               Where to return the object handle to close from the host.
+ */
+VBGLR3DECL(int) VbglR3ClipboardObjCloseRecv(PVBGLR3SHCLCMDCTX pCtx, PSHCLOBJHANDLE phObj)
+{
+    AssertPtrReturn(pCtx,  VERR_INVALID_POINTER);
+    AssertPtrReturn(phObj, VERR_INVALID_POINTER);
+
+    VBoxShClObjCloseMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_MSG_GET, VBOX_SHCL_CPARMS_OBJ_CLOSE);
+
+    Msg.uContext.SetUInt64(VBOX_SHCL_HOST_MSG_TRANSFER_OBJ_CLOSE);
+    Msg.uHandle.SetUInt64(0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        rc = Msg.uContext.GetUInt64(&pCtx->idContext);
+        if (RT_SUCCESS(rc))
+            rc = Msg.uHandle.GetUInt64(phObj);
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Replies to an object open request from the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   rcReply             Return code to reply to the host.
+ * @param   hObj                Object handle to reply to the host.
+ */
+VBGLR3DECL(int) VbglR3ClipboardObjCloseReply(PVBGLR3SHCLCMDCTX pCtx, int rcReply, SHCLOBJHANDLE hObj)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    VBoxShClReplyMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_REPLY, VBOX_SHCL_CPARMS_REPLY_MIN + 1);
+
+    Msg.uContext.SetUInt64(pCtx->idContext);
+    Msg.enmType.SetUInt32(VBOX_SHCL_REPLYMSGTYPE_OBJ_CLOSE);
+    Msg.rc.SetUInt32((uint32_t)rcReply); /** int vs. uint32_t */
+    Msg.pvPayload.SetPtr(NULL, 0);
+
+    Msg.u.ObjClose.uHandle.SetUInt64(hObj);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Sends a request to close an object to the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   hObj                Object handle to close on the host.
+ */
+VBGLR3DECL(int) VbglR3ClipboardObjCloseSend(PVBGLR3SHCLCMDCTX pCtx, SHCLOBJHANDLE hObj)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    VBoxShClObjCloseMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_OBJ_CLOSE, VBOX_SHCL_CPARMS_OBJ_CLOSE);
+
+    Msg.uContext.SetUInt64(pCtx->idContext);
+    Msg.uHandle.SetUInt64(hObj);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Receives a host request to read from an object on the guest.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   phObj               Where to return the object handle to read from.
+ * @param   pcbToRead           Where to return the amount (in bytes) to read.
+ * @param   pfFlags             Where to return the read flags.
+ */
+VBGLR3DECL(int) VbglR3ClipboardObjReadRecv(PVBGLR3SHCLCMDCTX pCtx, PSHCLOBJHANDLE phObj, uint32_t *pcbToRead,
+                                           uint32_t *pfFlags)
+{
+    AssertPtrReturn(pCtx,      VERR_INVALID_POINTER);
+    AssertPtrReturn(phObj,     VERR_INVALID_POINTER);
+    AssertPtrReturn(pcbToRead, VERR_INVALID_POINTER);
+    AssertPtrReturn(pfFlags,   VERR_INVALID_POINTER);
+
+    VBoxShClObjReadReqMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_MSG_GET, VBOX_SHCL_CPARMS_OBJ_READ_REQ);
+
+    Msg.ReqParms.uContext.SetUInt64(VBOX_SHCL_HOST_MSG_TRANSFER_OBJ_READ);
+    Msg.ReqParms.uHandle.SetUInt64(0);
+    Msg.ReqParms.cbToRead.SetUInt32(0);
+    Msg.ReqParms.fRead.SetUInt32(0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        rc = Msg.ReqParms.uContext.GetUInt64(&pCtx->idContext);
+        if (RT_SUCCESS(rc))
+            rc = Msg.ReqParms.uHandle.GetUInt64(phObj);
+        if (RT_SUCCESS(rc))
+            rc = Msg.ReqParms.cbToRead.GetUInt32(pcbToRead);
+        if (RT_SUCCESS(rc))
+            rc = Msg.ReqParms.fRead.GetUInt32(pfFlags);
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Sends a request to read from an object to the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   hObj                Object handle of object to read from.
+ * @param   pvData              Buffer where to store the read object data.
+ * @param   cbData              Size (in bytes) of buffer.
+ * @param   pcbRead             Where to store the amount (in bytes) read from the object.
+ */
+VBGLR3DECL(int) VbglR3ClipboardObjReadSend(PVBGLR3SHCLCMDCTX pCtx, SHCLOBJHANDLE hObj,
+                                           void *pvData, uint32_t cbData, uint32_t *pcbRead)
+{
+    AssertPtrReturn(pCtx,   VERR_INVALID_POINTER);
+    AssertPtrReturn(pvData, VERR_INVALID_POINTER);
+    AssertReturn(cbData,    VERR_INVALID_PARAMETER);
+    /* pcbRead is optional. */
+
+    VBoxShClObjReadWriteMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_OBJ_READ, VBOX_SHCL_CPARMS_OBJ_READ);
+
+    Msg.uContext.SetUInt64(pCtx->idContext);
+    Msg.uHandle.SetUInt64(hObj);
+    Msg.cbData.SetUInt32(cbData);
+    Msg.pvData.SetPtr(pvData, cbData);
+    Msg.cbChecksum.SetUInt32(0);
+    Msg.pvChecksum.SetPtr(NULL, 0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        /** @todo Add checksum support. */
+
+        if (pcbRead)
+        {
+            rc = Msg.cbData.GetUInt32(pcbRead); AssertRC(rc);
+            AssertReturn(cbData >= *pcbRead, VERR_TOO_MUCH_DATA);
+        }
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Sends a request to write to an object to the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Shared Clipboard command context to use for the connection.
+ * @param   hObj                Object handle of object to write to.
+ * @param   pvData              Buffer of data to write to object.
+ * @param   cbData              Size (in bytes) of buffer.
+ * @param   pcbWritten          Where to store the amount (in bytes) written to the object.
+ */
+VBGLR3DECL(int) VbglR3ClipboardObjWriteSend(PVBGLR3SHCLCMDCTX pCtx, SHCLOBJHANDLE hObj,
+                                            void *pvData, uint32_t cbData, uint32_t *pcbWritten)
+{
+    AssertPtrReturn(pCtx,   VERR_INVALID_POINTER);
+    AssertPtrReturn(pvData, VERR_INVALID_POINTER);
+    /* cbData can be 0. */
+    /* pcbWritten is optional. */
+
+    VBoxShClObjReadWriteMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->idClient,
+                       VBOX_SHCL_GUEST_FN_OBJ_WRITE, VBOX_SHCL_CPARMS_OBJ_WRITE);
+
+    Msg.uContext.SetUInt64(pCtx->idContext);
+    Msg.uHandle.SetUInt64(hObj);
+    Msg.pvData.SetPtr(pvData, cbData);
+    Msg.pvChecksum.SetPtr(NULL, 0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        /** @todo Add checksum support. */
+
+        if (pcbWritten)
+            *pcbWritten = cbData; /** @todo For now return all as being written. */
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+
+/*********************************************************************************************************************************
+*   Transfer interface implementations                                                                                           *
+*********************************************************************************************************************************/
+
+static DECLCALLBACK(int) vbglR3ClipboardTransferIfaceGetRoots(PSHCLTXPROVIDERCTX pCtx, PSHCLROOTLIST *ppRootList)
+{
+    LogFlowFuncEnter();
+
+    PVBGLR3SHCLCMDCTX pCmdCtx = (PVBGLR3SHCLCMDCTX)pCtx->pvUser;
+    AssertPtr(pCmdCtx);
+
+    int rc = VbglR3ClipboardRootListRead(pCmdCtx, ppRootList);
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+static DECLCALLBACK(int) vbglR3ClipboardTransferIfaceListOpen(PSHCLTXPROVIDERCTX pCtx, PSHCLLISTOPENPARMS pOpenParms,
+                                                              PSHCLLISTHANDLE phList)
+{
+    LogFlowFuncEnter();
+
+    PVBGLR3SHCLCMDCTX pCmdCtx = (PVBGLR3SHCLCMDCTX)pCtx->pvUser;
+    AssertPtr(pCmdCtx);
+
+    int rc = VbglR3ClipboardListOpenSend(pCmdCtx, pOpenParms, phList);
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+static DECLCALLBACK(int) vbglR3ClipboardTransferIfaceListClose(PSHCLTXPROVIDERCTX pCtx, SHCLLISTHANDLE hList)
+{
+    LogFlowFuncEnter();
+
+    PVBGLR3SHCLCMDCTX pCmdCtx = (PVBGLR3SHCLCMDCTX)pCtx->pvUser;
+    AssertPtr(pCmdCtx);
+
+    int rc = VbglR3ClipboardListCloseSend(pCmdCtx, hList);
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+static DECLCALLBACK(int) vbglR3ClipboardTransferIfaceListHdrRead(PSHCLTXPROVIDERCTX pCtx,
+                                                                 SHCLLISTHANDLE hList, PSHCLLISTHDR pListHdr)
+{
+    LogFlowFuncEnter();
+
+    PVBGLR3SHCLCMDCTX pCmdCtx = (PVBGLR3SHCLCMDCTX)pCtx->pvUser;
+    AssertPtr(pCmdCtx);
+
+    int rc = ShClTransferListHdrInit(pListHdr);
+    if (RT_SUCCESS(rc))
+    {
+        if (RT_SUCCESS(rc))
+        {
+            rc = VbglR3ClipboardListHdrRead(pCmdCtx, hList, 0 /* fFlags */, pListHdr);
+        }
+        else
+            ShClTransferListHdrDestroy(pListHdr);
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+static DECLCALLBACK(int) vbglR3ClipboardTransferIfaceListEntryRead(PSHCLTXPROVIDERCTX pCtx,
+                                                                   SHCLLISTHANDLE hList, PSHCLLISTENTRY pEntry)
+{
+    LogFlowFuncEnter();
+
+    PVBGLR3SHCLCMDCTX pCmdCtx = (PVBGLR3SHCLCMDCTX)pCtx->pvUser;
+    AssertPtr(pCmdCtx);
+
+    int rc = VbglR3ClipboardListEntryRead(pCmdCtx, hList, pEntry);
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+static DECLCALLBACK(int) vbglR3ClipboardTransferIfaceObjOpen(PSHCLTXPROVIDERCTX pCtx,
+                                                             PSHCLOBJOPENCREATEPARMS pCreateParms, PSHCLOBJHANDLE phObj)
+{
+    LogFlowFuncEnter();
+
+    PVBGLR3SHCLCMDCTX pCmdCtx = (PVBGLR3SHCLCMDCTX)pCtx->pvUser;
+    AssertPtr(pCmdCtx);
+
+    int rc = VbglR3ClipboardObjOpenSend(pCmdCtx, pCreateParms, phObj);
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+static DECLCALLBACK(int) vbglR3ClipboardTransferIfaceObjClose(PSHCLTXPROVIDERCTX pCtx, SHCLOBJHANDLE hObj)
+{
+    LogFlowFuncEnter();
+
+    PVBGLR3SHCLCMDCTX pCmdCtx = (PVBGLR3SHCLCMDCTX)pCtx->pvUser;
+    AssertPtr(pCmdCtx);
+
+    int rc = VbglR3ClipboardObjCloseSend(pCmdCtx, hObj);
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+static DECLCALLBACK(int) vbglR3ClipboardTransferIfaceObjRead(PSHCLTXPROVIDERCTX pCtx,
+                                                             SHCLOBJHANDLE hObj, void *pvData, uint32_t cbData,
+                                                             uint32_t fFlags, uint32_t *pcbRead)
+{
+    LogFlowFuncEnter();
+
+    PVBGLR3SHCLCMDCTX pCmdCtx = (PVBGLR3SHCLCMDCTX)pCtx->pvUser;
+    AssertPtr(pCmdCtx);
+
+    RT_NOREF(fFlags); /* Not used yet. */
+
+    int rc = VbglR3ClipboardObjReadSend(pCmdCtx, hObj, pvData, cbData, pcbRead);
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Starts a transfer on the guest side.
+ *
+ * @returns VBox status code.
+ * @param   pCmdCtx             Command context to use.
+ * @param   pTransferCtx        Transfer context to create transfer for.
+ * @param   uTransferID         ID to use for transfer to start.
+ * @param   enmDir              Direction of transfer to start.
+ * @param   enmSource           Source of transfer to start.
+ * @param   ppTransfer          Where to return the transfer object on success. Optional.
+ */
+static int vbglR3ClipboardTransferStart(PVBGLR3SHCLCMDCTX pCmdCtx, PSHCLTRANSFERCTX pTransferCtx,
+                                        SHCLTRANSFERID uTransferID, SHCLTRANSFERDIR enmDir, SHCLSOURCE enmSource,
+                                        PSHCLTRANSFER *ppTransfer)
+{
+    PSHCLTRANSFER pTransfer;
+    int rc = ShClTransferCreate(&pTransfer);
+    if (RT_SUCCESS(rc))
+    {
+        ShClTransferSetCallbacks(pTransfer, &pCmdCtx->Transfers.Callbacks);
+
+        rc = ShClTransferInit(pTransfer, enmDir, enmSource);
+        if (RT_SUCCESS(rc))
+        {
+            rc = ShClTransferCtxTransferRegisterById(pTransferCtx, pTransfer, uTransferID);
+            if (RT_SUCCESS(rc))
+            {
+                /* If this is a read transfer (reading data from host), set the interface to use
+                 * our VbglR3 routines here. */
+                if (enmDir == SHCLTRANSFERDIR_FROM_REMOTE)
+                {
+                    SHCLTXPROVIDERCREATIONCTX creationCtx;
+                    RT_ZERO(creationCtx);
+
+                    creationCtx.Interface.pfnRootsGet      = vbglR3ClipboardTransferIfaceGetRoots;
+
+                    creationCtx.Interface.pfnListOpen      = vbglR3ClipboardTransferIfaceListOpen;
+                    creationCtx.Interface.pfnListClose     = vbglR3ClipboardTransferIfaceListClose;
+                    creationCtx.Interface.pfnListHdrRead   = vbglR3ClipboardTransferIfaceListHdrRead;
+                    creationCtx.Interface.pfnListEntryRead = vbglR3ClipboardTransferIfaceListEntryRead;
+
+                    creationCtx.Interface.pfnObjOpen       = vbglR3ClipboardTransferIfaceObjOpen;
+                    creationCtx.Interface.pfnObjClose      = vbglR3ClipboardTransferIfaceObjClose;
+                    creationCtx.Interface.pfnObjRead       = vbglR3ClipboardTransferIfaceObjRead;
+
+                    creationCtx.pvUser = pCmdCtx;
+
+                    rc = ShClTransferSetProviderIface(pTransfer, &creationCtx);
+                }
+
+                if (RT_SUCCESS(rc))
+                    rc = ShClTransferStart(pTransfer);
+            }
+
+            if (RT_FAILURE(rc))
+                ShClTransferCtxTransferUnregister(pTransferCtx, uTransferID);
+        }
+    }
+
+    if (RT_SUCCESS(rc))
+    {
+        if (ppTransfer)
+            *ppTransfer = pTransfer;
+
+        LogRel2(("Shared Clipboard: Transfer ID=%RU32 (%s %s) successfully started\n",
+                 uTransferID,
+                 enmDir    == SHCLTRANSFERDIR_FROM_REMOTE ? "reading from" : "writing to",
+                 enmSource == SHCLSOURCE_LOCAL            ? "local"        : "remote"));
+    }
+    else
+        LogRel(("Shared Clipboard: Unable to start transfer ID=%RU32, rc=%Rrc\n", uTransferID, rc));
+
+    /* Send a reply in any case. */
+    int rc2 = VbglR3ClipboardTransferStatusReply(pCmdCtx, pTransfer,
+                                                   RT_SUCCESS(rc)
+                                                 ? SHCLTRANSFERSTATUS_STARTED : SHCLTRANSFERSTATUS_ERROR, rc);
+    if (RT_SUCCESS(rc))
+        rc = rc2;
+
+    if (RT_FAILURE(rc))
+    {
+        ShClTransferDestroy(pTransfer);
+        pTransfer = NULL;
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Stops a transfer on the guest side.
+ *
+ * @returns VBox status code, or VERR_NOT_FOUND if transfer has not been found.
+ * @param   pCmdCtx             Command context to use.
+ * @param   pTransferCtx        Transfer context to stop transfer for.
+ * @param   uTransferID         ID of transfer to stop.
+ */
+static int vbglR3ClipboardTransferStop(PVBGLR3SHCLCMDCTX pCmdCtx, PSHCLTRANSFERCTX pTransferCtx,
+                                       SHCLTRANSFERID uTransferID)
+{
+    int rc;
+
+    PSHCLTRANSFER pTransfer = ShClTransferCtxGetTransferById(pTransferCtx, uTransferID);
+    if (pTransfer)
+    {
+        rc = ShClTransferCtxTransferUnregister(pTransferCtx, uTransferID);
+        if (RT_SUCCESS(rc))
+        {
+            LogRel2(("Shared Clipboard: Transfer ID=%RU32 successfully stopped\n", uTransferID));
+        }
+        else
+            LogRel(("Shared Clipboard: Unable to stop transfer ID=%RU32, rc=%Rrc\n", uTransferID, rc));
+
+        /* Send a reply in any case. */
+        int rc2 = VbglR3ClipboardTransferStatusReply(pCmdCtx, pTransfer,
+                                                       RT_SUCCESS(rc)
+                                                     ? SHCLTRANSFERSTATUS_STOPPED : SHCLTRANSFERSTATUS_ERROR, rc);
+        AssertRC(rc2);
+    }
+    else
+        rc = VERR_NOT_FOUND;
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Sets transfer callbacks of a Shared Clipboard command context.
+ *
+ * @param   pCmdCtx             Command context to set callbacks for.
+ * @param   pCallbacks          Pointer to callback table to set.
+ */
+VBGLR3DECL(void) VbglR3ClipboardTransferSetCallbacks(PVBGLR3SHCLCMDCTX pCmdCtx,  PSHCLTRANSFERCALLBACKTABLE pCallbacks)
+{
+    AssertPtrReturnVoid(pCmdCtx);
+    AssertPtrReturnVoid(pCallbacks);
+
+    ShClTransferCopyCallbacks(&pCmdCtx->Transfers.Callbacks, pCallbacks);
+}
+
+VBGLR3DECL(int) VbglR3ClipboardEventGetNextEx(uint32_t idMsg, uint32_t cParms,
+                                              PVBGLR3SHCLCMDCTX pCmdCtx, PSHCLTRANSFERCTX pTransferCtx,
+                                              PVBGLR3CLIPBOARDEVENT pEvent)
+{
+    AssertPtrReturn(pCmdCtx,      VERR_INVALID_POINTER);
+    AssertPtrReturn(pTransferCtx, VERR_INVALID_POINTER);
+    AssertPtrReturn(pEvent,       VERR_INVALID_POINTER);
+
+    LogFunc(("Handling idMsg=%RU32 (%s), cParms=%RU32\n", idMsg, ShClHostMsgToStr(idMsg), cParms));
+
+    int rc;
+    if (!pCmdCtx->fUseLegacyProtocol)
+    {
+        bool fErrorSent = false; /* Whether an error has been reported back to the host already. */
+
+        switch (idMsg)
+        {
+            case VBOX_SHCL_HOST_MSG_TRANSFER_STATUS:
+            {
+                SHCLTRANSFERDIR    enmDir;
+                SHCLTRANSFERREPORT transferReport;
+                rc = VbglR3ClipboarTransferStatusRecv(pCmdCtx, &enmDir, &transferReport);
+                if (RT_SUCCESS(rc))
+                {
+                    const SHCLTRANSFERID uTransferID = VBOX_SHCL_CONTEXTID_GET_TRANSFER(pCmdCtx->idContext);
+
+                    LogFlowFunc(("[Transfer %RU32] enmDir=%RU32, status=%s\n",
+                                 uTransferID, enmDir, ShClTransferStatusToStr(transferReport.uStatus)));
+
+                    switch (transferReport.uStatus)
+                    {
+                        case SHCLTRANSFERSTATUS_INITIALIZED:
+                            RT_FALL_THROUGH();
+                        case SHCLTRANSFERSTATUS_STARTED:
+                        {
+                            SHCLSOURCE enmSource = SHCLSOURCE_INVALID;
+
+                            /* The host announces the transfer direction from its point of view, so inverse the direction here. */
+                            if (enmDir == SHCLTRANSFERDIR_TO_REMOTE)
+                            {
+                                enmDir = SHCLTRANSFERDIR_FROM_REMOTE;
+                                enmSource = SHCLSOURCE_REMOTE;
+                            }
+                            else if (enmDir == SHCLTRANSFERDIR_FROM_REMOTE)
+                            {
+                                enmDir = SHCLTRANSFERDIR_TO_REMOTE;
+                                enmSource = SHCLSOURCE_LOCAL;
+                            }
+                            else
+                                AssertFailedBreakStmt(rc = VERR_INVALID_PARAMETER);
+
+                            rc = vbglR3ClipboardTransferStart(pCmdCtx, pTransferCtx, uTransferID,
+                                                              enmDir, enmSource, NULL /* ppTransfer */);
+                            break;
+                        }
+
+                        case SHCLTRANSFERSTATUS_STOPPED:
+                            RT_FALL_THROUGH();
+                        case SHCLTRANSFERSTATUS_CANCELED:
+                            RT_FALL_THROUGH();
+                        case SHCLTRANSFERSTATUS_KILLED:
+                            RT_FALL_THROUGH();
+                        case SHCLTRANSFERSTATUS_ERROR:
+                        {
+                            rc = vbglR3ClipboardTransferStop(pCmdCtx, pTransferCtx,
+                                                             VBOX_SHCL_CONTEXTID_GET_TRANSFER(pCmdCtx->idContext));
+                            break;
+                        }
+
+                        default:
+                            rc = VERR_NOT_SUPPORTED;
+                            break;
+                    }
+
+                    if (RT_SUCCESS(rc))
+                    {
+                        pEvent->u.TransferStatus.enmDir = enmDir;
+                        pEvent->u.TransferStatus.Report = transferReport;
+                        pEvent->u.TransferStatus.uID    = VBOX_SHCL_CONTEXTID_GET_TRANSFER(pCmdCtx->idContext);
+
+                        pEvent->enmType = VBGLR3CLIPBOARDEVENTTYPE_TRANSFER_STATUS;
+
+                        LogRel2(("Shared Clipboard: Received status %s (rc=%Rrc) for transfer ID=%RU32\n",
+                                 ShClTransferStatusToStr(pEvent->u.TransferStatus.Report.uStatus), pEvent->u.TransferStatus.Report.rc,
+                                 pEvent->u.TransferStatus.uID));
+                    }
+                }
+                break;
+            }
+
+            case VBOX_SHCL_HOST_MSG_TRANSFER_ROOT_LIST_HDR_READ:
+            {
+                uint32_t fRoots;
+                rc = VbglR3ClipboardRootListHdrReadReq(pCmdCtx, &fRoots);
+
+                /** @todo Validate / handle fRoots. */
+
+                if (RT_SUCCESS(rc))
+                {
+                    PSHCLTRANSFER pTransfer = ShClTransferCtxGetTransferById(pTransferCtx,
+                                                                             VBOX_SHCL_CONTEXTID_GET_TRANSFER(pCmdCtx->idContext));
+                    AssertPtrBreakStmt(pTransfer, rc = VERR_NOT_FOUND);
+
+                    SHCLROOTLISTHDR rootListHdr;
+                    RT_ZERO(rootListHdr);
+
+                    rootListHdr.cRoots = ShClTransferRootsCount(pTransfer);
+
+                    LogFlowFunc(("cRoots=%RU32\n", rootListHdr.cRoots));
+
+                    rc = VbglR3ClipboardRootListHdrReadReply(pCmdCtx, &rootListHdr);
+                }
+                break;
+            }
+
+            case VBOX_SHCL_HOST_MSG_TRANSFER_ROOT_LIST_ENTRY_READ:
+            {
+                uint32_t uIndex;
+                uint32_t fInfo;
+                rc = VbglR3ClipboardRootListEntryReadReq(pCmdCtx, &uIndex, &fInfo);
+                if (RT_SUCCESS(rc))
+                {
+                    PSHCLTRANSFER pTransfer = ShClTransferCtxGetTransferById(pTransferCtx,
+                                                                             VBOX_SHCL_CONTEXTID_GET_TRANSFER(pCmdCtx->idContext));
+                    AssertPtrBreakStmt(pTransfer, rc = VERR_NOT_FOUND);
+
+                    SHCLROOTLISTENTRY rootListEntry;
+                    rc = ShClTransferRootsEntry(pTransfer, uIndex, &rootListEntry);
+                    if (RT_SUCCESS(rc))
+                        rc = VbglR3ClipboardRootListEntryReadReply(pCmdCtx, uIndex, &rootListEntry);
+                }
+                break;
+            }
+
+            case VBOX_SHCL_HOST_MSG_TRANSFER_LIST_OPEN:
+            {
+                SHCLLISTOPENPARMS openParmsList;
+                rc = ShClTransferListOpenParmsInit(&openParmsList);
+                if (RT_SUCCESS(rc))
+                {
+                    rc = VbglR3ClipboardListOpenRecv(pCmdCtx, &openParmsList);
+                    if (RT_SUCCESS(rc))
+                    {
+                        PSHCLTRANSFER pTransfer = ShClTransferCtxGetTransferById(pTransferCtx,
+                                                                                 VBOX_SHCL_CONTEXTID_GET_TRANSFER(pCmdCtx->idContext));
+                        AssertPtrBreakStmt(pTransfer, rc = VERR_NOT_FOUND);
+
+                        LogFlowFunc(("pszPath=%s\n", openParmsList.pszPath));
+
+                        SHCLLISTHANDLE hList = SHCLLISTHANDLE_INVALID;
+                        rc = ShClTransferListOpen(pTransfer, &openParmsList, &hList);
+
+                        /* Reply in any case. */
+                        int rc2 = VbglR3ClipboardListOpenReply(pCmdCtx, rc, hList);
+                        AssertRC(rc2);
+                    }
+
+                    ShClTransferListOpenParmsDestroy(&openParmsList);
+                }
+
+                break;
+            }
+
+            case VBOX_SHCL_HOST_MSG_TRANSFER_LIST_CLOSE:
+            {
+                SHCLLISTHANDLE hList;
+                rc = VbglR3ClipboardListCloseRecv(pCmdCtx, &hList);
+                if (RT_SUCCESS(rc))
+                {
+                    PSHCLTRANSFER pTransfer = ShClTransferCtxGetTransferById(pTransferCtx,
+                                                                             VBOX_SHCL_CONTEXTID_GET_TRANSFER(pCmdCtx->idContext));
+                    AssertPtrBreakStmt(pTransfer, rc = VERR_NOT_FOUND);
+
+                    rc = ShClTransferListClose(pTransfer, hList);
+
+                    /* Reply in any case. */
+                    int rc2 = VbglR3ClipboardListCloseReply(pCmdCtx, rc, hList);
+                    AssertRC(rc2);
+                }
+
+                break;
+            }
+
+            case VBOX_SHCL_HOST_MSG_TRANSFER_LIST_HDR_READ:
+            {
+                /** @todo Handle filter + list features. */
+
+                SHCLLISTHANDLE hList  = SHCLLISTHANDLE_INVALID;
+                uint32_t       fFlags = 0;
+                rc = VbglR3ClipboardListHdrReadRecvReq(pCmdCtx, &hList, &fFlags);
+                if (RT_SUCCESS(rc))
+                {
+                    PSHCLTRANSFER pTransfer = ShClTransferCtxGetTransferById(pTransferCtx,
+                                                                             VBOX_SHCL_CONTEXTID_GET_TRANSFER(pCmdCtx->idContext));
+                    AssertPtrBreakStmt(pTransfer, rc = VERR_NOT_FOUND);
+
+                    SHCLLISTHDR hdrList;
+                    rc = ShClTransferListGetHeader(pTransfer, hList, &hdrList);
+                    if (RT_SUCCESS(rc))
+                    {
+                        rc = VbglR3ClipboardListHdrWrite(pCmdCtx, hList, &hdrList);
+
+                        ShClTransferListHdrDestroy(&hdrList);
+                    }
+                }
+
+                break;
+            }
+
+            case VBOX_SHCL_HOST_MSG_TRANSFER_LIST_ENTRY_READ:
+            {
+                LogFlowFunc(("VBOX_SHCL_HOST_MSG_TRANSFER_LIST_ENTRY_READ\n"));
+
+                SHCLLISTENTRY entryList;
+                rc = ShClTransferListEntryInit(&entryList);
+                if (RT_SUCCESS(rc))
+                {
+                    SHCLLISTHANDLE hList;
+                    uint32_t       fInfo;
+                    rc = VbglR3ClipboardListEntryReadRecvReq(pCmdCtx, &hList, &fInfo);
+                    if (RT_SUCCESS(rc))
+                    {
+                        PSHCLTRANSFER pTransfer = ShClTransferCtxGetTransferById(pTransferCtx,
+                                                                                 VBOX_SHCL_CONTEXTID_GET_TRANSFER(pCmdCtx->idContext));
+                        AssertPtrBreakStmt(pTransfer, rc = VERR_NOT_FOUND);
+
+                        rc = ShClTransferListRead(pTransfer, hList, &entryList);
+                        if (RT_SUCCESS(rc))
+                        {
+                            PSHCLFSOBJINFO pObjInfo = (PSHCLFSOBJINFO)entryList.pvInfo;
+                            Assert(entryList.cbInfo == sizeof(SHCLFSOBJINFO));
+
+                            RT_NOREF(pObjInfo);
+
+                            LogFlowFunc(("\t%s (%RU64 bytes)\n", entryList.pszName, pObjInfo->cbObject));
+
+                            rc = VbglR3ClipboardListEntryWrite(pCmdCtx, hList, &entryList);
+                        }
+                    }
+
+                    ShClTransferListEntryDestroy(&entryList);
+                }
+
+                break;
+            }
+
+            case VBOX_SHCL_HOST_MSG_TRANSFER_OBJ_OPEN:
+            {
+                SHCLOBJOPENCREATEPARMS openParms;
+                rc = ShClTransferObjOpenParmsInit(&openParms);
+                if (RT_SUCCESS(rc))
+                {
+                    rc = VbglR3ClipboardObjOpenRecv(pCmdCtx, &openParms);
+                    if (RT_SUCCESS(rc))
+                    {
+                        PSHCLTRANSFER pTransfer = ShClTransferCtxGetTransferById(pTransferCtx,
+                                                                                 VBOX_SHCL_CONTEXTID_GET_TRANSFER(pCmdCtx->idContext));
+                        AssertPtrBreakStmt(pTransfer, rc = VERR_NOT_FOUND);
+
+                        SHCLOBJHANDLE hObj;
+                        rc = ShClTransferObjOpen(pTransfer, &openParms, &hObj);
+
+                        /* Reply in any case. */
+                        int rc2 = VbglR3ClipboardObjOpenReply(pCmdCtx, rc, hObj);
+                        AssertRC(rc2);
+                    }
+
+                    ShClTransferObjOpenParmsDestroy(&openParms);
+                }
+
+                break;
+            }
+
+            case VBOX_SHCL_HOST_MSG_TRANSFER_OBJ_CLOSE:
+            {
+                SHCLOBJHANDLE hObj;
+                rc = VbglR3ClipboardObjCloseRecv(pCmdCtx, &hObj);
+                if (RT_SUCCESS(rc))
+                {
+                    PSHCLTRANSFER pTransfer = ShClTransferCtxGetTransferById(pTransferCtx,
+                                                                             VBOX_SHCL_CONTEXTID_GET_TRANSFER(pCmdCtx->idContext));
+                    AssertPtrBreakStmt(pTransfer, rc = VERR_NOT_FOUND);
+
+                    rc = ShClTransferObjClose(pTransfer, hObj);
+
+                    /* Reply in any case. */
+                    int rc2 = VbglR3ClipboardObjCloseReply(pCmdCtx, rc, hObj);
+                    AssertRC(rc2);
+                }
+
+                break;
+            }
+
+            case VBOX_SHCL_HOST_MSG_TRANSFER_OBJ_READ:
+            {
+                SHCLOBJHANDLE hObj;
+                uint32_t      cbBuf;
+                uint32_t      fFlags;
+                rc = VbglR3ClipboardObjReadRecv(pCmdCtx, &hObj, &cbBuf, &fFlags);
+                if (RT_SUCCESS(rc))
+                {
+                    PSHCLTRANSFER pTransfer = ShClTransferCtxGetTransferById(pTransferCtx,
+                                                                         VBOX_SHCL_CONTEXTID_GET_TRANSFER(pCmdCtx->idContext));
+                    AssertPtrBreakStmt(pTransfer, rc = VERR_NOT_FOUND);
+
+                    AssertBreakStmt(pCmdCtx->Transfers.cbChunkSize, rc = VERR_INVALID_PARAMETER);
+
+                    const uint32_t cbToRead = RT_MIN(cbBuf, pCmdCtx->Transfers.cbChunkSize);
+
+                    LogFlowFunc(("hObj=%RU64, cbBuf=%RU32, fFlags=0x%x -> cbChunkSize=%RU32, cbToRead=%RU32\n",
+                                 hObj, cbBuf, fFlags, pCmdCtx->Transfers.cbChunkSize, cbToRead));
+
+                    void *pvBuf = RTMemAlloc(cbToRead);
+                    if (pvBuf)
+                    {
+                        uint32_t cbRead;
+                        rc = ShClTransferObjRead(pTransfer, hObj, pvBuf, cbToRead, fFlags, &cbRead);
+                        if (RT_SUCCESS(rc))
+                            rc = VbglR3ClipboardObjWriteSend(pCmdCtx, hObj, pvBuf, cbRead, NULL /* pcbWritten */);
+
+                        RTMemFree(pvBuf);
+                    }
+                    else
+                        rc = VERR_NO_MEMORY;
+                }
+
+                break;
+            }
+
+            default:
+            {
+                rc = VbglR3ClipboardEventGetNext(idMsg, cParms, pCmdCtx, pEvent);
+                if (RT_FAILURE(rc))
+                    fErrorSent = true;
+                break;
+            }
+        }
+
+        if (   !fErrorSent
+            && RT_FAILURE(rc))
+        {
+            /* Report error back to the host. */
+            int rc2 = VbglR3ClipboardWriteError(pCmdCtx->idClient, rc);
+            AssertRC(rc2);
+        }
+    }
+    else
+    {
+        /*
+         * This builds on what we did in VbglR3ClipboardMsgPeekWait, so
+         * !HACK ALERT! cParms is the format flag or flags.
+         */
+        rc = VINF_SUCCESS;
+        switch (idMsg)
+        {
+            case VBOX_SHCL_HOST_MSG_FORMATS_REPORT:
+                pEvent->enmType = VBGLR3CLIPBOARDEVENTTYPE_REPORT_FORMATS;
+                pEvent->u.fReportedFormats = cParms;
+                break;
+
+            case VBOX_SHCL_HOST_MSG_READ_DATA:
+                pEvent->enmType = VBGLR3CLIPBOARDEVENTTYPE_READ_DATA;
+                pEvent->u.fReadData = cParms;
+                break;
+
+            case VBOX_SHCL_HOST_MSG_QUIT:
+                pEvent->enmType = VBGLR3CLIPBOARDEVENTTYPE_QUIT;
+                break;
+
+            default:
+                AssertMsgFailed(("%u (%#x)\n", idMsg, idMsg));
+                rc = VERR_NOT_SUPPORTED;
+                break;
+        }
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+#endif /* VBOX_WITH_SHARED_CLIPBOARD_TRANSFERS */
+
+VBGLR3DECL(int) VbglR3ClipboardEventGetNext(uint32_t idMsg, uint32_t cParms, PVBGLR3SHCLCMDCTX pCtx, PVBGLR3CLIPBOARDEVENT pEvent)
+{
+    AssertPtrReturn(pCtx,   VERR_INVALID_POINTER);
+    AssertPtrReturn(pEvent, VERR_INVALID_POINTER);
+
+    RT_NOREF(cParms);
+
+    int rc;
+    if (!pCtx->fUseLegacyProtocol)
+    {
+        LogFunc(("Handling idMsg=%RU32 (%s)\n", idMsg, ShClHostMsgToStr(idMsg)));
+        switch (idMsg)
+        {
+            case VBOX_SHCL_HOST_MSG_FORMATS_REPORT:
+            {
+                rc = vbglR3ClipboardFormatsReportRecv(pCtx, &pEvent->u.fReportedFormats);
+                if (RT_SUCCESS(rc))
+                    pEvent->enmType = VBGLR3CLIPBOARDEVENTTYPE_REPORT_FORMATS;
+                break;
+            }
+
+            case VBOX_SHCL_HOST_MSG_READ_DATA_CID:
+            {
+                rc = vbglR3ClipboardFetchReadDataCid(pCtx, &pEvent->u.fReadData);
+                if (RT_SUCCESS(rc))
+                    pEvent->enmType = VBGLR3CLIPBOARDEVENTTYPE_READ_DATA;
+                break;
+            }
+
+            case VBOX_SHCL_HOST_MSG_READ_DATA:
+            {
+                rc = vbglR3ClipboardFetchReadData(pCtx, &pEvent->u.fReadData);
+                if (RT_SUCCESS(rc))
+                    pEvent->enmType = VBGLR3CLIPBOARDEVENTTYPE_READ_DATA;
+                break;
+            }
+
+            case VBOX_SHCL_HOST_MSG_QUIT:
+            {
+                pEvent->enmType = VBGLR3CLIPBOARDEVENTTYPE_QUIT;
+                rc = VINF_SUCCESS;
+                break;
+            }
+
+            default:
+            {
+                /** @todo r=bird: BUGBUG - need a skip command here! */
+                rc = VERR_NOT_SUPPORTED;
+                break;
+            }
+        }
+
+        if (RT_SUCCESS(rc))
+        {
+            /* Copy over our command context to the event. */
+            pEvent->cmdCtx = *pCtx;
+        }
+        else
+        {
+            /* Report error back to the host. */
+            int rc2 = VbglR3ClipboardWriteError(pCtx->idClient, rc);
+            AssertRC(rc2);
+        }
+    }
+    else
+    {
+        /*
+         * This builds on what we did in VbglR3ClipboardMsgPeekWait, so
+         * !HACK ALERT! cParms is the format flag or flags.
+         */
+        rc = VINF_SUCCESS;
+        switch (idMsg)
+        {
+            case VBOX_SHCL_HOST_MSG_FORMATS_REPORT:
+                pEvent->enmType = VBGLR3CLIPBOARDEVENTTYPE_REPORT_FORMATS;
+                pEvent->u.fReportedFormats = cParms;
+                break;
+
+            case VBOX_SHCL_HOST_MSG_READ_DATA:
+                pEvent->enmType = VBGLR3CLIPBOARDEVENTTYPE_READ_DATA;
+                pEvent->u.fReadData = cParms;
+                break;
+
+            case VBOX_SHCL_HOST_MSG_QUIT:
+                pEvent->enmType = VBGLR3CLIPBOARDEVENTTYPE_QUIT;
+                break;
+
+            default:
+                AssertMsgFailed(("%u (%#x)\n", idMsg, idMsg));
+                rc = VERR_NOT_SUPPORTED;
+                break;
+        }
+        pEvent->cmdCtx = *pCtx;
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Frees (destroys) a formerly allocated Shared Clipboard event.
+ *
+ * @returns IPRT status code.
+ * @param   pEvent              Event to free (destroy).
+ */
+VBGLR3DECL(void) VbglR3ClipboardEventFree(PVBGLR3CLIPBOARDEVENT pEvent)
+{
+    if (!pEvent)
+        return;
+
+    /* Some messages require additional cleanup. */
+    switch (pEvent->enmType)
+    {
+        default:
+            break;
+    }
+
+    RTMemFree(pEvent);
+    pEvent = NULL;
+}
+
+/**
+ * Reports (advertises) guest clipboard formats to the host.
+ *
+ * Legacy function, do not use anymore.
+ *
+ * @returns VBox status code.
+ * @param   idClient        The client id returned by VbglR3ClipboardConnect().
+ * @param   fFormats        The formats to report.
+ */
+VBGLR3DECL(int) VbglR3ClipboardReportFormats(HGCMCLIENTID idClient, uint32_t fFormats)
+{
+    struct
+    {
+        VBGLIOCHGCMCALL             Hdr;
+        VBoxShClParmReportFormats   Parms;
+    } Msg;
+
+    VBGL_HGCM_HDR_INIT(&Msg.Hdr, idClient, VBOX_SHCL_GUEST_FN_REPORT_FORMATS, VBOX_SHCL_CPARMS_REPORT_FORMATS);
+    VbglHGCMParmUInt32Set(&Msg.Parms.f32Formats, fFormats);
+
+    int rc = VbglR3HGCMCall(&Msg.Hdr, sizeof(Msg));
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Sends guest clipboard data to the host.
+ *
+ * Legacy function kept for compatibility, do not use anymore.
+ *
+ * This is usually called in reply to a VBOX_SHCL_HOST_MSG_READ_DATA message
+ * from the host.
+ *
+ * @returns VBox status code.
+ * @param   idClient    The client id returned by VbglR3ClipboardConnect().
+ * @param   fFormat     The format of the data.
+ * @param   pvData      Pointer to the data to send.  Can be NULL if @a cbData
+ *                      is zero.
+ * @param   cbData      Number of bytes of data to send.  Zero is valid.
+ */
+VBGLR3DECL(int) VbglR3ClipboardWriteData(HGCMCLIENTID idClient, uint32_t fFormat, void *pv, uint32_t cb)
+{
+    LogFlowFuncEnter();
+
+    struct
+    {
+        VBGLIOCHGCMCALL             Hdr;
+        VBoxShClParmDataWriteOld    Parms;
+    } Msg;
+
+    VBGL_HGCM_HDR_INIT(&Msg.Hdr, idClient, VBOX_SHCL_GUEST_FN_DATA_WRITE, VBOX_SHCL_CPARMS_DATA_WRITE_OLD);
+    VbglHGCMParmUInt32Set(&Msg.Parms.f32Format, fFormat);
+    VbglHGCMParmPtrSet(&Msg.Parms.pData, pv, cb);
+
+    int rc = VbglR3HGCMCall(&Msg.Hdr, sizeof(Msg));
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Sends guest clipboard data to the host.
+ *
+ * This is usually called in reply to a VBOX_SHCL_HOST_MSG_READ_DATA message
+ * from the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx        The command context returned by VbglR3ClipboardConnectEx().
+ * @param   fFormat     Clipboard format to send.
+ * @param   pvData      Pointer to the data to send.  Can be NULL if @a cbData
+ *                      is zero.
+ * @param   cbData      Number of bytes of data to send.  Zero is valid.
+ */
+VBGLR3DECL(int) VbglR3ClipboardWriteDataEx(PVBGLR3SHCLCMDCTX pCtx, SHCLFORMAT fFormat, void *pvData, uint32_t cbData)
+{
+    LogFlowFunc(("ENTER: fFormat=%#x pvData=%p cbData=%#x\n", fFormat, pvData, cbData));
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+    if (cbData > 0)
+        AssertPtrReturn(pvData, VERR_INVALID_POINTER);
+
+    int rc;
+    if (pCtx->fUseLegacyProtocol)
+        rc = VbglR3ClipboardWriteData(pCtx->idClient, fFormat, pvData, cbData);
+    else
+    {
+        struct
+        {
+            VBGLIOCHGCMCALL         Hdr;
+            VBoxShClParmDataWrite   Parms;
+        } Msg;
+
+        VBGL_HGCM_HDR_INIT(&Msg.Hdr, pCtx->idClient, VBOX_SHCL_GUEST_FN_DATA_WRITE, VBOX_SHCL_CPARMS_DATA_WRITE);
+        Msg.Parms.id64Context.SetUInt64(pCtx->idContext);
+        Msg.Parms.f32Format.SetUInt32(fFormat);
+        Msg.Parms.pData.SetPtr(pvData, cbData);
+
+        LogFlowFunc(("CID=%RU32\n", pCtx->idContext));
+
+        rc = VbglR3HGCMCall(&Msg.Hdr, sizeof(Msg));
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Writes an error to the host.
+ *
+ * @returns IPRT status code.
+ * @param   idClient            The client id returned by VbglR3ClipboardConnect().
+ * @param   rcErr               Error (IPRT-style) to send.
+ */
+VBGLR3DECL(int) VbglR3ClipboardWriteError(HGCMCLIENTID idClient, int rcErr)
+{
+    AssertReturn(idClient, VERR_INVALID_PARAMETER);
+
+    VBoxShClWriteErrorMsg Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, idClient, VBOX_SHCL_GUEST_FN_ERROR, VBOX_SHCL_CPARMS_ERROR);
+
+    /** @todo Context ID not used yet. */
+    Msg.uContext.SetUInt64(0);
+    Msg.rc.SetUInt32((uint32_t)rcErr); /* uint32_t vs. int. */
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+
+    if (RT_FAILURE(rc))
+        LogFlowFunc(("Sending error %Rrc failed with rc=%Rrc\n", rcErr, rc));
+    if (rc == VERR_NOT_SUPPORTED)
+        rc = VINF_SUCCESS;
+
+    if (RT_FAILURE(rc))
+        LogRel(("Shared Clipboard: Reporting error %Rrc to the host failed with %Rrc\n", rcErr, rc));
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibCoreDump.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibCoreDump.cpp
new file mode 100644
index 00000000..35971006
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibCoreDump.cpp
@@ -0,0 +1,56 @@
+/* $Id: VBoxGuestR3LibCoreDump.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, Core Dumps.
+ */
+
+/*
+ * Copyright (C) 2010-2023 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 "VBoxGuestR3LibInternal.h"
+
+
+/**
+ * Write guest core dump.
+ *
+ * @returns IPRT status code.
+ */
+VBGLR3DECL(int) VbglR3WriteCoreDump(void)
+{
+    VBGLIOCWRITECOREDUMP Req;
+    VBGLREQHDR_INIT(&Req.Hdr, WRITE_CORE_DUMP);
+    Req.u.In.fFlags = 0;
+    return vbglR3DoIOCtl(VBGL_IOCTL_WRITE_CORE_DUMP, &Req.Hdr, sizeof(Req));
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibCpuHotPlug.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibCpuHotPlug.cpp
new file mode 100644
index 00000000..00aa0257
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibCpuHotPlug.cpp
@@ -0,0 +1,133 @@
+/* $Id: VBoxGuestR3LibCpuHotPlug.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, CPU Hot Plugging.
+ */
+
+/*
+ * Copyright (C) 2010-2023 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 "VBoxGuestR3LibInternal.h"
+#include <iprt/assert.h>
+#include <iprt/errcore.h>
+
+
+/**
+ * Initialize CPU hot plugging.
+ *
+ * This will enable the CPU hot plugging events.
+ *
+ * @returns VBox status code.
+ */
+VBGLR3DECL(int) VbglR3CpuHotPlugInit(void)
+{
+    int rc = VbglR3CtlFilterMask(VMMDEV_EVENT_CPU_HOTPLUG, 0);
+    if (RT_FAILURE(rc))
+        return rc;
+
+    VMMDevCpuHotPlugStatusRequest Req;
+    vmmdevInitRequest(&Req.header, VMMDevReq_SetCpuHotPlugStatus);
+    Req.enmStatusType = VMMDevCpuStatusType_Enable;
+    rc = vbglR3GRPerform(&Req.header);
+    if (RT_FAILURE(rc))
+        VbglR3CtlFilterMask(0, VMMDEV_EVENT_CPU_HOTPLUG);
+
+    return rc;
+}
+
+
+/**
+ * Terminate CPU hot plugging.
+ *
+ * This will disable the CPU hot plugging events.
+ *
+ * @returns VBox status code.
+ */
+VBGLR3DECL(int) VbglR3CpuHotPlugTerm(void)
+{
+    /* Clear the events. */
+    VbglR3CtlFilterMask(0, VMMDEV_EVENT_CPU_HOTPLUG);
+
+    VMMDevCpuHotPlugStatusRequest Req;
+    vmmdevInitRequest(&Req.header, VMMDevReq_SetCpuHotPlugStatus);
+    Req.enmStatusType = VMMDevCpuStatusType_Disable;
+    return vbglR3GRPerform(&Req.header);
+}
+
+
+/**
+ * Waits for a CPU hot plugging event and retrieve the data associated with it.
+ *
+ * @returns VBox status code.
+ * @param   penmEventType   Where to store the event type on success.
+ * @param   pidCpuCore      Where to store the CPU core ID on success.
+ * @param   pidCpuPackage   Where to store the CPU package ID on success.
+ */
+VBGLR3DECL(int) VbglR3CpuHotPlugWaitForEvent(VMMDevCpuEventType *penmEventType, uint32_t *pidCpuCore, uint32_t *pidCpuPackage)
+{
+    AssertPtrReturn(penmEventType, VERR_INVALID_POINTER);
+    AssertPtrReturn(pidCpuCore, VERR_INVALID_POINTER);
+    AssertPtrReturn(pidCpuPackage, VERR_INVALID_POINTER);
+
+    uint32_t fEvents = 0;
+    int rc = VbglR3WaitEvent(VMMDEV_EVENT_CPU_HOTPLUG, RT_INDEFINITE_WAIT, &fEvents);
+    if (RT_SUCCESS(rc))
+    {
+        /* did we get the right event? */
+        if (fEvents & VMMDEV_EVENT_CPU_HOTPLUG)
+        {
+            VMMDevGetCpuHotPlugRequest Req;
+
+            /* get the CPU hot plugging request */
+            vmmdevInitRequest(&Req.header, VMMDevReq_GetCpuHotPlugRequest);
+            Req.idCpuCore    = UINT32_MAX;
+            Req.idCpuPackage = UINT32_MAX;
+            Req.enmEventType = VMMDevCpuEventType_None;
+            rc = vbglR3GRPerform(&Req.header);
+            if (RT_SUCCESS(rc))
+            {
+                *penmEventType = Req.enmEventType;
+                *pidCpuCore    = Req.idCpuCore;
+                *pidCpuPackage = Req.idCpuPackage;
+                return VINF_SUCCESS;
+            }
+        }
+        else
+            rc = VERR_TRY_AGAIN;
+    }
+    else if (rc == VERR_TIMEOUT) /* just in case */
+        rc = VERR_TRY_AGAIN;
+    return rc;
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibCredentials.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibCredentials.cpp
new file mode 100644
index 00000000..b4d795f7
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibCredentials.cpp
@@ -0,0 +1,222 @@
+/* $Id: VBoxGuestR3LibCredentials.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, user credentials.
+ */
+
+/*
+ * 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 <iprt/asm.h>
+#include <iprt/mem.h>
+#include <iprt/rand.h>
+#include <iprt/string.h>
+#include <iprt/utf16.h>
+#include <VBox/log.h>
+
+#include "VBoxGuestR3LibInternal.h"
+
+
+/**
+ * Checks whether user credentials are available to the guest or not.
+ *
+ * @returns IPRT status value; VINF_SUCCESS if credentials are available,
+ *          VERR_NOT_FOUND if not. Otherwise an error is occurred.
+ */
+VBGLR3DECL(int) VbglR3CredentialsQueryAvailability(void)
+{
+    VMMDevCredentials Req;
+    RT_ZERO(Req);
+    vmmdevInitRequest((VMMDevRequestHeader*)&Req, VMMDevReq_QueryCredentials);
+    Req.u32Flags |= VMMDEV_CREDENTIALS_QUERYPRESENCE;
+
+    int rc = vbglR3GRPerform(&Req.header);
+    if (RT_SUCCESS(rc))
+    {
+        if ((Req.u32Flags & VMMDEV_CREDENTIALS_PRESENT) == 0)
+            rc = VERR_NOT_FOUND;
+    }
+    return rc;
+}
+
+
+/**
+ * Retrieves and clears the user credentials for logging into the guest OS.
+ *
+ * @returns IPRT status value
+ * @param   ppszUser        Receives pointer of allocated user name string.
+ *                          The returned pointer must be freed using VbglR3CredentialsDestroy().
+ * @param   ppszPassword    Receives pointer of allocated user password string.
+ *                          The returned pointer must be freed using VbglR3CredentialsDestroy().
+ * @param   ppszDomain      Receives pointer of allocated domain name string.
+ *                          The returned pointer must be freed using VbglR3CredentialsDestroy().
+ */
+VBGLR3DECL(int) VbglR3CredentialsRetrieve(char **ppszUser, char **ppszPassword, char **ppszDomain)
+{
+    AssertPtrReturn(ppszUser, VERR_INVALID_POINTER);
+    AssertPtrReturn(ppszPassword, VERR_INVALID_POINTER);
+    AssertPtrReturn(ppszDomain, VERR_INVALID_POINTER);
+
+    VMMDevCredentials Req;
+    RT_ZERO(Req);
+    vmmdevInitRequest((VMMDevRequestHeader*)&Req, VMMDevReq_QueryCredentials);
+    Req.u32Flags |= VMMDEV_CREDENTIALS_READ | VMMDEV_CREDENTIALS_CLEAR;
+
+    int rc = vbglR3GRPerform(&Req.header);
+    if (RT_SUCCESS(rc))
+    {
+        rc = RTStrDupEx(ppszUser, Req.szUserName);
+        if (RT_SUCCESS(rc))
+        {
+            rc = RTStrDupEx(ppszPassword, Req.szPassword);
+            if (RT_SUCCESS(rc))
+            {
+                rc = RTStrDupEx(ppszDomain, Req.szDomain);
+                if (RT_SUCCESS(rc))
+                    return VINF_SUCCESS;
+
+                RTStrFree(*ppszPassword);
+            }
+            RTStrFree(*ppszUser);
+        }
+    }
+    return rc;
+}
+
+
+/**
+ * Retrieves and clears the user credentials for logging into the guest OS.
+ * UTF-16 version.
+ *
+ * @returns IPRT status value
+ * @param   ppwszUser       Receives pointer of allocated user name string.
+ *                          The returned pointer must be freed using VbglR3CredentialsDestroyUtf16().
+ * @param   ppwszPassword   Receives pointer of allocated user password string.
+ *                          The returned pointer must be freed using VbglR3CredentialsDestroyUtf16().
+ * @param   ppwszDomain     Receives pointer of allocated domain name string.
+ *                          The returned pointer must be freed using VbglR3CredentialsDestroyUtf16().
+ */
+VBGLR3DECL(int) VbglR3CredentialsRetrieveUtf16(PRTUTF16 *ppwszUser, PRTUTF16 *ppwszPassword, PRTUTF16 *ppwszDomain)
+{
+    AssertPtrReturn(ppwszUser, VERR_INVALID_POINTER);
+    AssertPtrReturn(ppwszPassword, VERR_INVALID_POINTER);
+    AssertPtrReturn(ppwszDomain, VERR_INVALID_POINTER);
+
+    char *pszUser, *pszPassword, *pszDomain;
+    int rc = VbglR3CredentialsRetrieve(&pszUser, &pszPassword, &pszDomain);
+    if (RT_SUCCESS(rc))
+    {
+        PRTUTF16 pwszUser = NULL;
+        PRTUTF16 pwszPassword = NULL;
+        PRTUTF16 pwszDomain = NULL;
+
+        rc = RTStrToUtf16(pszUser, &pwszUser);
+        if (RT_SUCCESS(rc))
+        {
+            rc = RTStrToUtf16(pszPassword, &pwszPassword);
+            if (RT_SUCCESS(rc))
+                rc = RTStrToUtf16(pszDomain, &pwszDomain);
+        }
+
+        if (RT_SUCCESS(rc))
+        {
+            *ppwszUser     = pwszUser;
+            *ppwszPassword = pwszPassword;
+            *ppwszDomain   = pwszDomain;
+        }
+        else
+            VbglR3CredentialsDestroyUtf16(pwszUser, pwszPassword, pwszDomain, 3 /* Passes */);
+        VbglR3CredentialsDestroy(pszUser, pszPassword, pszDomain, 3 /* Passes */);
+    }
+
+    return rc;
+}
+
+
+/**
+ * Clears and frees the three strings.
+ *
+ * @param   pszUser        Receives pointer of the user name string to destroy.
+ *                         Optional.
+ * @param   pszPassword    Receives pointer of the password string to destroy.
+ *                         Optional.
+ * @param   pszDomain      Receives pointer of allocated domain name string.
+ *                         Optional.
+ * @param   cPasses        Number of wipe passes.  The more the better + slower.
+ */
+VBGLR3DECL(void) VbglR3CredentialsDestroy(char *pszUser, char *pszPassword, char *pszDomain, uint32_t cPasses)
+{
+    /* wipe first */
+    if (pszUser)
+        RTMemWipeThoroughly(pszUser,     strlen(pszUser) + 1,     cPasses);
+    if (pszPassword)
+        RTMemWipeThoroughly(pszPassword, strlen(pszPassword) + 1, cPasses);
+    if (pszDomain)
+        RTMemWipeThoroughly(pszDomain,   strlen(pszDomain) + 1,   cPasses);
+
+    /* then free. */
+    RTStrFree(pszUser);
+    RTStrFree(pszPassword);
+    RTStrFree(pszDomain);
+}
+
+
+/**
+ * Clears and frees the three strings. UTF-16 version.
+ *
+ * @param   pwszUser       Receives pointer of the user name string to destroy.
+ *                         Optional.
+ * @param   pwszPassword   Receives pointer of the password string to destroy.
+ *                         Optional.
+ * @param   pwszDomain     Receives pointer of allocated domain name string.
+ *                         Optional.
+ * @param   cPasses        Number of wipe passes.  The more the better + slower.
+ */
+VBGLR3DECL(void) VbglR3CredentialsDestroyUtf16(PRTUTF16 pwszUser, PRTUTF16 pwszPassword, PRTUTF16 pwszDomain,
+                                               uint32_t cPasses)
+{
+    /* wipe first */
+    if (pwszUser)
+        RTMemWipeThoroughly(pwszUser,     (RTUtf16Len(pwszUser)     + 1) * sizeof(RTUTF16), cPasses);
+    if (pwszPassword)
+        RTMemWipeThoroughly(pwszPassword, (RTUtf16Len(pwszPassword) + 1) * sizeof(RTUTF16), cPasses);
+    if (pwszDomain)
+        RTMemWipeThoroughly(pwszDomain,   (RTUtf16Len(pwszDomain)   + 1) * sizeof(RTUTF16), cPasses);
+
+    /* then free. */
+    RTUtf16Free(pwszUser);
+    RTUtf16Free(pwszPassword);
+    RTUtf16Free(pwszDomain);
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibDaemonize.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibDaemonize.cpp
new file mode 100644
index 00000000..2aad8c5c
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibDaemonize.cpp
@@ -0,0 +1,326 @@
+/** $Id: VBoxGuestR3LibDaemonize.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, daemonize a process.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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                                                                                                                 *
+*********************************************************************************************************************************/
+#if defined(RT_OS_OS2)
+# define INCL_BASE
+# define INCL_ERRORS
+# include <os2.h>
+
+# include <iprt/alloca.h>
+# include <iprt/string.h>
+
+#elif defined(RT_OS_WINDOWS)
+# error "PORTME"
+
+#else /* the unices */
+# include <sys/types.h>
+# include <sys/stat.h>
+# include <sys/wait.h>
+# include <stdio.h>
+# include <fcntl.h>
+# include <stdlib.h>
+# include <unistd.h>
+# include <signal.h>
+# include <errno.h>
+#endif
+
+#include <iprt/process.h>
+#include <iprt/string.h>
+#include <VBox/err.h>
+#include <VBox/log.h>
+
+#include "VBoxGuestR3LibInternal.h"
+
+
+/**
+ * Daemonize the process for running in the background.
+ *
+ * This is supposed to do the same job as the BSD daemon() call.
+ *
+ * @returns 0 on success
+ *
+ * @param   fNoChDir        Pass false to change working directory to root.
+ * @param   fNoClose        Pass false to redirect standard file streams to /dev/null.
+ * @param   fRespawn        Restart the daemonised process after five seconds if it
+ *                          terminates abnormally.
+ * @param   pcRespawn       Where to store a count of how often we have respawned,
+ *                          intended for avoiding error spamming.  Optional.
+ * @param   fReturnOnUpdate If True, this function will return control to caller when
+ *                          child process will terminate with exit code of VBGLR3EXITCODERELOAD,
+ *                          indicating that Guest Additions update has been started and this running
+ *                          process will be asked to be restarted by arrival of the next SIGUSR1
+ *                          signal (caller should wait for SIGUSR1). If False, this functions will
+ *                          never return, but rather exit() when child process terminates with
+ *                          exit code 0.
+ * @param   pfUpdateStarted A flag which passed to caller if fReturnOnUpdate is True (can be NULL).
+ * @param   szPidfile       Optional path to parent process' pidfile (can be NULL).
+ * @param   phPidfile       Optional path to parent process' pidfile handle (can not be NULL if
+ *                          szPidfile was specified).
+ *
+ * @todo    Use RTProcDaemonize instead of this.
+ * @todo    Implement fRespawn on OS/2.
+ * @todo    Make the respawn interval configurable.  But not until someone
+ *          actually needs that.
+ */
+VBGLR3DECL(int) VbglR3DaemonizeEx(bool fNoChDir, bool fNoClose, bool fRespawn, unsigned *pcRespawn,
+                                  bool fReturnOnUpdate, bool *pfUpdateStarted, const char *szPidfile,
+                                  RTFILE *phPidfile)
+{
+#if defined(RT_OS_OS2)
+    PPIB pPib;
+    PTIB pTib;
+    DosGetInfoBlocks(&pTib, &pPib);
+
+    RT_NOREF(fReturnOnUpdate);
+    RT_NOREF(pfUpdateStarted);
+    RT_NOREF(szPidfile);
+    RT_NOREF(phPidfile);
+
+    AssertRelease(!fRespawn);
+    /* Get the full path to the executable. */
+    char szExe[CCHMAXPATH];
+    APIRET rc = DosQueryModuleName(pPib->pib_hmte, sizeof(szExe), szExe);
+    if (rc)
+        return RTErrConvertFromOS2(rc);
+
+    /* calc the length of the command line. */
+    char *pch = pPib->pib_pchcmd;
+    size_t cch0 = strlen(pch);
+    pch += cch0 + 1;
+    size_t cch1 = strlen(pch);
+    pch += cch1 + 1;
+    char *pchArgs;
+    if (cch1 && *pch)
+    {
+        do  pch = strchr(pch, '\0') + 1;
+        while (*pch);
+
+        size_t cchTotal = pch - pPib->pib_pchcmd;
+        pchArgs = (char *)alloca(cchTotal + sizeof("--daemonized\0\0"));
+        memcpy(pchArgs, pPib->pib_pchcmd, cchTotal - 1);
+        memcpy(pchArgs + cchTotal - 1, "--daemonized\0\0", sizeof("--daemonized\0\0"));
+    }
+    else
+    {
+        size_t cchTotal = pch - pPib->pib_pchcmd + 1;
+        pchArgs = (char *)alloca(cchTotal + sizeof(" --daemonized "));
+        memcpy(pchArgs, pPib->pib_pchcmd, cch0 + 1);
+        pch = pchArgs + cch0 + 1;
+        memcpy(pch, " --daemonized ", sizeof(" --daemonized ") - 1);
+        pch += sizeof(" --daemonized ") - 1;
+        if (cch1)
+            memcpy(pch, pPib->pib_pchcmd + cch0 + 1, cch1 + 2);
+        else
+            pch[0] = pch[1] = '\0';
+    }
+
+    /* spawn a detach process  */
+    char szObj[128];
+    RESULTCODES ResCodes = { 0, 0 };
+    szObj[0] = '\0';
+    rc = DosExecPgm(szObj, sizeof(szObj), EXEC_BACKGROUND, (PCSZ)pchArgs, NULL, &ResCodes, (PCSZ)szExe);
+    if (rc)
+    {
+        /** @todo Change this to some standard log/print error?? */
+        /* VBoxServiceError("DosExecPgm failed with rc=%d and szObj='%s'\n", rc, szObj); */
+        return RTErrConvertFromOS2(rc);
+    }
+    DosExit(EXIT_PROCESS, 0);
+    return VERR_GENERAL_FAILURE;
+
+#elif defined(RT_OS_WINDOWS)
+# error "PORTME"
+
+#else /* the unices */
+    /*
+     * Fork the child process in a new session and quit the parent.
+     *
+     * - fork once and create a new session (setsid). This will detach us
+     *   from the controlling tty meaning that we won't receive the SIGHUP
+     *   (or any other signal) sent to that session.
+     * - The SIGHUP signal is ignored because the session/parent may throw
+     *   us one before we get to the setsid.
+     * - When the parent exit(0) we will become an orphan and re-parented to
+     *   the init process.
+     * - Because of the Linux / System V semantics of assigning the controlling
+     *   tty automagically when a session leader first opens a tty, we will
+     *   fork() once more on Linux to get rid of the session leadership role.
+     */
+
+    struct sigaction OldSigAct;
+    struct sigaction SigAct;
+    RT_ZERO(SigAct);
+    SigAct.sa_handler = SIG_IGN;
+    int rcSigAct = sigaction(SIGHUP, &SigAct, &OldSigAct);
+
+    pid_t pid = fork();
+    if (pid == -1)
+        return RTErrConvertFromErrno(errno);
+    if (pid != 0)
+        exit(0);
+
+    /*
+     * The orphaned child becomes is reparented to the init process.
+     * We create a new session for it (setsid), point the standard
+     * file descriptors to /dev/null, and change to the root directory.
+     */
+    pid_t newpgid = setsid();
+    int SavedErrno = errno;
+    if (rcSigAct != -1)
+        sigaction(SIGHUP, &OldSigAct, NULL);
+    if (newpgid == -1)
+        return RTErrConvertFromErrno(SavedErrno);
+
+    if (!fNoClose)
+    {
+        /* Open stdin(0), stdout(1) and stderr(2) as /dev/null. */
+        int fd = open("/dev/null", O_RDWR);
+        if (fd == -1) /* paranoia */
+        {
+            close(STDIN_FILENO);
+            close(STDOUT_FILENO);
+            close(STDERR_FILENO);
+            fd = open("/dev/null", O_RDWR);
+        }
+        if (fd != -1)
+        {
+            dup2(fd, STDIN_FILENO);
+            dup2(fd, STDOUT_FILENO);
+            dup2(fd, STDERR_FILENO);
+            if (fd > 2)
+                close(fd);
+        }
+    }
+
+    if (!fNoChDir)
+    {
+        int rcShutUpGcc = chdir("/");
+        RT_NOREF_PV(rcShutUpGcc);
+    }
+
+    /*
+     * Change the umask - this is non-standard daemon() behavior.
+     */
+    umask(027);
+
+# ifdef RT_OS_LINUX
+    /*
+     * And fork again to lose session leader status (non-standard daemon()
+     * behaviour).
+     */
+    pid = fork();
+    if (pid == -1)
+        return RTErrConvertFromErrno(errno);
+    if (pid != 0)
+        exit(0);
+# endif /* RT_OS_LINUX */
+
+    /* Check if another instance is already running. */
+    if (szPidfile != NULL)
+    {
+        if (phPidfile != NULL)
+        {
+            int rc = VbglR3PidfileWait(szPidfile, phPidfile, 5000);
+
+             /* Another instance of process is already running. */
+            if (rc == VERR_FILE_LOCK_VIOLATION)
+            {
+                LogRel(("cannot aquire pidfile %s, exitting\n", szPidfile));
+                exit(1);
+            }
+
+            /* Unable to lock on pidfile. */
+            if (RT_FAILURE(rc))
+                exit(1);
+        }
+        else
+            return VERR_INVALID_PARAMETER;
+    }
+
+    if (fRespawn)
+    {
+        /* We implement re-spawning as a third fork(), with the parent process
+         * monitoring the child and re-starting it after a delay if it exits
+         * abnormally. */
+        unsigned cRespawn = 0;
+        for (;;)
+        {
+            int iStatus, rcWait;
+
+            if (pcRespawn != NULL)
+                *pcRespawn = cRespawn;
+            pid = fork();
+            if (pid == -1)
+                return RTErrConvertFromErrno(errno);
+            if (pid == 0)
+                return VINF_SUCCESS;
+            do
+                rcWait = waitpid(pid, &iStatus, 0);
+            while (rcWait == -1 && errno == EINTR);
+            if (rcWait == -1)
+                exit(1);
+            if (WIFEXITED(iStatus))
+            {
+                if (WEXITSTATUS(iStatus) == 0)
+                    exit(0);
+                else if (fReturnOnUpdate && WEXITSTATUS(iStatus) == VBGLR3EXITCODERELOAD)
+                {
+                    /* Tell caller that update has been started. */
+                    if (pfUpdateStarted != NULL)
+                        *pfUpdateStarted = true;
+
+                    return VINF_SUCCESS;
+                }
+            }
+            sleep(5);
+            ++cRespawn;
+        }
+    }
+    return VINF_SUCCESS;
+#endif
+}
+
+/**
+ * A wrapper function for VbglR3DaemonizeEx.
+ */
+VBGLR3DECL(int) VbglR3Daemonize(bool fNoChDir, bool fNoClose, bool fRespawn, unsigned *pcRespawn)
+{
+    return VbglR3DaemonizeEx(fNoChDir, fNoClose, fRespawn, pcRespawn, false, NULL, NULL, NULL);
+}
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibDragAndDrop.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibDragAndDrop.cpp
new file mode 100644
index 00000000..68ba038b
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibDragAndDrop.cpp
@@ -0,0 +1,1948 @@
+/* $Id: VBoxGuestR3LibDragAndDrop.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, Drag & Drop.
+ */
+
+/*
+ * 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 <iprt/path.h>
+#include <iprt/dir.h>
+#include <iprt/file.h>
+#include <iprt/uri.h>
+#include <iprt/thread.h>
+
+#include <iprt/cpp/list.h>
+#include <iprt/cpp/ministring.h>
+
+#ifdef LOG_GROUP
+ #undef LOG_GROUP
+#endif
+#define LOG_GROUP LOG_GROUP_GUEST_DND
+#include <VBox/log.h>
+
+#include <VBox/VBoxGuestLib.h>
+#include <VBox/GuestHost/DragAndDrop.h>
+#include <VBox/HostServices/DragAndDropSvc.h>
+
+using namespace DragAndDropSvc;
+
+#include "VBoxGuestR3LibInternal.h"
+
+
+/*********************************************************************************************************************************
+*   Private internal functions                                                                                                   *
+*********************************************************************************************************************************/
+
+/**
+ * Receives the next upcoming message for a given DnD context.
+ *
+ * @returns IPRT status code.
+ *          Will return VERR_CANCELLED (implemented by the host service) if we need to bail out.
+ * @param   pCtx                DnD context to use.
+ * @param   puMsg               Where to store the message type.
+ * @param   pcParms             Where to store the number of parameters required for receiving the message.
+ * @param   fWait               Whether to wait (block) for a new message to arrive or not.
+ */
+static int vbglR3DnDGetNextMsgType(PVBGLR3GUESTDNDCMDCTX pCtx, uint32_t *puMsg, uint32_t *pcParms, bool fWait)
+{
+    AssertPtrReturn(pCtx,    VERR_INVALID_POINTER);
+    AssertPtrReturn(puMsg,   VERR_INVALID_POINTER);
+    AssertPtrReturn(pcParms, VERR_INVALID_POINTER);
+
+    int rc;
+
+    do
+    {
+        HGCMMsgGetNext Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_DND_FN_GET_NEXT_HOST_MSG, 3);
+        Msg.uMsg.SetUInt32(0);
+        Msg.cParms.SetUInt32(0);
+        Msg.fBlock.SetUInt32(fWait ? 1 : 0);
+
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            rc = Msg.uMsg.GetUInt32(puMsg);     AssertRC(rc);
+            rc = Msg.cParms.GetUInt32(pcParms); AssertRC(rc);
+        }
+
+        LogRel(("DnD: Received message %s (%#x) from host\n", DnDHostMsgToStr(*puMsg), *puMsg));
+
+    } while (rc == VERR_INTERRUPTED);
+
+    return rc;
+}
+
+
+/**
+ * Sends a DnD error back to the host.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to use.
+ * @param   rcErr               Error (IPRT-style) to send.
+ */
+VBGLR3DECL(int) VbglR3DnDSendError(PVBGLR3GUESTDNDCMDCTX pCtx, int rcErr)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    HGCMMsgGHError Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_DND_FN_EVT_ERROR, 2);
+    /** @todo Context ID not used yet. */
+    Msg.u.v3.uContext.SetUInt32(0);
+    Msg.u.v3.rc.SetUInt32((uint32_t)rcErr); /* uint32_t vs. int. */
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+
+    /*
+     * Never return an error if the host did not accept the error at the current
+     * time.  This can be due to the host not having any appropriate callbacks
+     * set which would handle that error.
+     *
+     * bird: Looks like VERR_NOT_SUPPORTED is what the host will return if it
+     *       doesn't an appropriate callback.  The code used to ignore ALL errors
+     *       the host would return, also relevant ones.
+     */
+    if (RT_FAILURE(rc))
+        LogFlowFunc(("Sending error %Rrc failed with rc=%Rrc\n", rcErr, rc));
+    if (rc == VERR_NOT_SUPPORTED)
+        rc = VINF_SUCCESS;
+
+    return rc;
+}
+
+/**
+ * Host -> Guest
+ * Utility function to receive a so-called "action message" from the host.
+ * Certain DnD messages use the same amount / sort of parameters and grouped as "action messages".
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to use.
+ * @param   uMsg                Which kind of message to receive.
+ * @param   puScreenID          Where to store the host screen ID the message is bound to. Optional.
+ * @param   puX                 Where to store the absolute X coordinates. Optional.
+ * @param   puY                 Where to store the absolute Y coordinates. Optional.
+ * @param   puDefAction         Where to store the default action to perform. Optional.
+ * @param   puAllActions        Where to store the available actions. Optional.
+ * @param   ppszFormats         Where to store List of formats. Optional.
+ * @param   pcbFormats          Size (in bytes) of where to store the list of formats. Optional.
+ *
+ * @todo r=andy Get rid of this function as soon as we resolved the protocol TODO #1.
+ *              This was part of the initial protocol and needs to go.
+ */
+static int vbglR3DnDHGRecvAction(PVBGLR3GUESTDNDCMDCTX pCtx,
+                                 uint32_t   uMsg,
+                                 uint32_t  *puScreenID,
+                                 uint32_t  *puX,
+                                 uint32_t  *puY,
+                                 uint32_t  *puDefAction,
+                                 uint32_t  *puAllActions,
+                                 char     **ppszFormats,
+                                 uint32_t  *pcbFormats)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+    /* The rest is optional. */
+
+    const uint32_t cbFormatsTmp = pCtx->cbMaxChunkSize;
+
+    char *pszFormatsTmp = static_cast<char *>(RTMemAlloc(cbFormatsTmp));
+    if (!pszFormatsTmp)
+        return VERR_NO_MEMORY;
+
+    HGCMMsgHGAction Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, uMsg, 8);
+    Msg.u.v3.uContext.SetUInt32(0);
+    Msg.u.v3.uScreenId.SetUInt32(0);
+    Msg.u.v3.uX.SetUInt32(0);
+    Msg.u.v3.uY.SetUInt32(0);
+    Msg.u.v3.uDefAction.SetUInt32(0);
+    Msg.u.v3.uAllActions.SetUInt32(0);
+    Msg.u.v3.pvFormats.SetPtr(pszFormatsTmp, cbFormatsTmp);
+    Msg.u.v3.cbFormats.SetUInt32(0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        /** @todo Context ID not used yet. */
+        if (RT_SUCCESS(rc) && puScreenID)
+            rc = Msg.u.v3.uScreenId.GetUInt32(puScreenID);
+        if (RT_SUCCESS(rc) && puX)
+            rc = Msg.u.v3.uX.GetUInt32(puX);
+        if (RT_SUCCESS(rc) && puY)
+            rc = Msg.u.v3.uY.GetUInt32(puY);
+        if (RT_SUCCESS(rc) && puDefAction)
+            rc = Msg.u.v3.uDefAction.GetUInt32(puDefAction);
+        if (RT_SUCCESS(rc) && puAllActions)
+            rc = Msg.u.v3.uAllActions.GetUInt32(puAllActions);
+        if (RT_SUCCESS(rc) && pcbFormats)
+            rc = Msg.u.v3.cbFormats.GetUInt32(pcbFormats);
+
+        if (RT_SUCCESS(rc))
+        {
+            if (ppszFormats)
+            {
+                *ppszFormats = RTStrDup(pszFormatsTmp);
+                if (!*ppszFormats)
+                    rc = VERR_NO_MEMORY;
+            }
+        }
+    }
+
+    RTStrFree(pszFormatsTmp);
+
+    return rc;
+}
+
+/**
+ * Host -> Guest
+ * Utility function to receive a HOST_DND_FN_HG_EVT_LEAVE message from the host.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to use.
+ */
+static int vbglR3DnDHGRecvLeave(PVBGLR3GUESTDNDCMDCTX pCtx)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    HGCMMsgHGLeave Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, HOST_DND_FN_HG_EVT_LEAVE, 1);
+    /** @todo Context ID not used yet. */
+    Msg.u.v3.uContext.SetUInt32(0);
+
+    return VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+}
+
+/**
+ * Host -> Guest
+ * Utility function to receive a HOST_DND_FN_HG_EVT_CANCEL message from the host.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to use.
+ */
+static int vbglR3DnDHGRecvCancel(PVBGLR3GUESTDNDCMDCTX pCtx)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    HGCMMsgHGCancel Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, HOST_DND_FN_CANCEL, 1);
+    /** @todo Context ID not used yet. */
+    Msg.u.v3.uContext.SetUInt32(0);
+
+    return VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+}
+
+/**
+ * Host -> Guest
+ * Utility function to receive a HOST_DND_FN_HG_SND_DIR message from the host.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to use.
+ * @param   pszDirname          Where to store the directory name of the directory being created.
+ * @param   cbDirname           Size (in bytes) of where to store the directory name of the directory being created.
+ * @param   pcbDirnameRecv      Size (in bytes) of the actual directory name received.
+ * @param   pfMode              Where to store the directory creation mode.
+ */
+static int vbglR3DnDHGRecvDir(PVBGLR3GUESTDNDCMDCTX pCtx,
+                              char     *pszDirname,
+                              uint32_t  cbDirname,
+                              uint32_t *pcbDirnameRecv,
+                              uint32_t *pfMode)
+{
+    AssertPtrReturn(pCtx,           VERR_INVALID_POINTER);
+    AssertPtrReturn(pszDirname,     VERR_INVALID_POINTER);
+    AssertReturn(cbDirname,         VERR_INVALID_PARAMETER);
+    AssertPtrReturn(pcbDirnameRecv, VERR_INVALID_POINTER);
+    AssertPtrReturn(pfMode,         VERR_INVALID_POINTER);
+
+    HGCMMsgHGSendDir Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, HOST_DND_FN_HG_SND_DIR, 4);
+    /** @todo Context ID not used yet. */
+    Msg.u.v3.uContext.SetUInt32(0);
+    Msg.u.v3.pvName.SetPtr(pszDirname, cbDirname);
+    Msg.u.v3.cbName.SetUInt32(cbDirname);
+    Msg.u.v3.fMode.SetUInt32(0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        /** @todo Context ID not used yet. */
+        rc = Msg.u.v3.cbName.GetUInt32(pcbDirnameRecv); AssertRC(rc);
+        rc = Msg.u.v3.fMode.GetUInt32(pfMode);          AssertRC(rc);
+
+        AssertReturn(cbDirname >= *pcbDirnameRecv, VERR_TOO_MUCH_DATA);
+    }
+
+    return rc;
+}
+
+/**
+ * Host -> Guest
+ * Utility function to receive a HOST_DND_FN_HG_SND_FILE_DATA message from the host.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to use.
+ * @param   pvData              Where to store the file data chunk.
+ * @param   cbData              Size (in bytes) of where to store the data chunk.
+ * @param   pcbDataRecv         Size (in bytes) of the actual data chunk size received.
+ */
+static int vbglR3DnDHGRecvFileData(PVBGLR3GUESTDNDCMDCTX pCtx,
+                                   void                 *pvData,
+                                   uint32_t              cbData,
+                                   uint32_t             *pcbDataRecv)
+{
+    AssertPtrReturn(pCtx,            VERR_INVALID_POINTER);
+    AssertPtrReturn(pvData,          VERR_INVALID_POINTER);
+    AssertReturn(cbData,             VERR_INVALID_PARAMETER);
+    AssertPtrReturn(pcbDataRecv,     VERR_INVALID_POINTER);
+
+    HGCMMsgHGSendFileData Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, HOST_DND_FN_HG_SND_FILE_DATA, 5);
+    Msg.u.v3.uContext.SetUInt32(0);
+    Msg.u.v3.pvData.SetPtr(pvData, cbData);
+    Msg.u.v3.cbData.SetUInt32(0);
+    Msg.u.v3.pvChecksum.SetPtr(NULL, 0);
+    Msg.u.v3.cbChecksum.SetUInt32(0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        /** @todo Context ID not used yet. */
+        rc = Msg.u.v3.cbData.GetUInt32(pcbDataRecv); AssertRC(rc);
+        AssertReturn(cbData >= *pcbDataRecv, VERR_TOO_MUCH_DATA);
+        /** @todo Add checksum support. */
+    }
+
+    return rc;
+}
+
+/**
+ * Host -> Guest
+ * Utility function to receive the HOST_DND_FN_HG_SND_FILE_HDR message from the host.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to use.
+ * @param   pszFilename         Where to store the file name of the file being transferred.
+ * @param   cbFilename          Size (in bytes) of where to store the file name of the file being transferred.
+ * @param   puFlags             File transfer flags. Currently not being used.
+ * @param   pfMode              Where to store the file creation mode.
+ * @param   pcbTotal            Where to store the file size (in bytes).
+ */
+static int vbglR3DnDHGRecvFileHdr(PVBGLR3GUESTDNDCMDCTX  pCtx,
+                                  char                  *pszFilename,
+                                  uint32_t               cbFilename,
+                                  uint32_t              *puFlags,
+                                  uint32_t              *pfMode,
+                                  uint64_t              *pcbTotal)
+{
+    AssertPtrReturn(pCtx,        VERR_INVALID_POINTER);
+    AssertPtrReturn(pszFilename, VERR_INVALID_POINTER);
+    AssertReturn(cbFilename,     VERR_INVALID_PARAMETER);
+    AssertPtrReturn(puFlags,     VERR_INVALID_POINTER);
+    AssertPtrReturn(pfMode,      VERR_INVALID_POINTER);
+    AssertReturn(pcbTotal,       VERR_INVALID_POINTER);
+
+    HGCMMsgHGSendFileHdr Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, HOST_DND_FN_HG_SND_FILE_HDR, 6);
+    Msg.uContext.SetUInt32(0); /** @todo Not used yet. */
+    Msg.pvName.SetPtr(pszFilename, cbFilename);
+    Msg.cbName.SetUInt32(cbFilename);
+    Msg.uFlags.SetUInt32(0);
+    Msg.fMode.SetUInt32(0);
+    Msg.cbTotal.SetUInt64(0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        /** @todo Get context ID. */
+        rc = Msg.uFlags.GetUInt32(puFlags);   AssertRC(rc);
+        rc = Msg.fMode.GetUInt32(pfMode);     AssertRC(rc);
+        rc = Msg.cbTotal.GetUInt64(pcbTotal); AssertRC(rc);
+    }
+
+    return rc;
+}
+
+/**
+ * Host -> Guest
+ * Helper function for receiving URI data from the host. Do not call directly.
+ * This function also will take care of the file creation / locking on the guest.
+ *
+ * @returns IPRT status code.
+ * @retval  VERR_CANCELLED if the transfer was cancelled by the host.
+ * @param   pCtx                DnD context to use.
+ * @param   pDataHdr            DnD data header to use. Needed for accounting.
+ * @param   pDroppedFiles       Dropped files object to use for maintaining the file creation / locking.
+ */
+static int vbglR3DnDHGRecvURIData(PVBGLR3GUESTDNDCMDCTX pCtx, PVBOXDNDSNDDATAHDR pDataHdr, PDNDDROPPEDFILES pDroppedFiles)
+{
+    AssertPtrReturn(pCtx,          VERR_INVALID_POINTER);
+    AssertPtrReturn(pDataHdr,      VERR_INVALID_POINTER);
+    AssertPtrReturn(pDroppedFiles, VERR_INVALID_POINTER);
+
+    /* Only count the raw data minus the already received meta data. */
+    Assert(pDataHdr->cbTotal >= pDataHdr->cbMeta);
+    uint64_t cbToRecvBytes = pDataHdr->cbTotal - pDataHdr->cbMeta;
+    uint64_t cToRecvObjs   = pDataHdr->cObjects;
+
+    LogFlowFunc(("cbToRecvBytes=%RU64, cToRecvObjs=%RU64, (cbTotal=%RU64, cbMeta=%RU32)\n",
+                 cbToRecvBytes, cToRecvObjs, pDataHdr->cbTotal, pDataHdr->cbMeta));
+
+    /* Anything to do at all? */
+    /* Note: Do not check for cbToRecvBytes == 0 here, as this might be just
+     *       a bunch of 0-byte files to be transferred. */
+    if (!cToRecvObjs)
+        return VINF_SUCCESS;
+
+    LogRel2(("DnD: Receiving URI data started\n"));
+
+    /*
+     * Allocate temporary chunk buffer.
+     */
+    uint32_t cbChunkMax = pCtx->cbMaxChunkSize;
+    void *pvChunk = RTMemAlloc(cbChunkMax);
+    if (!pvChunk)
+        return VERR_NO_MEMORY;
+    uint32_t cbChunkRead   = 0;
+
+    uint64_t cbFileSize    = 0; /* Total file size (in bytes). */
+    uint64_t cbFileWritten = 0; /* Written bytes. */
+
+    const char *pszDropDir = DnDDroppedFilesGetDirAbs(pDroppedFiles);
+    AssertPtr(pszDropDir);
+
+    int rc;
+
+    /*
+     * Enter the main loop of retieving files + directories.
+     */
+    DNDTRANSFEROBJECT objCur;
+    RT_ZERO(objCur);
+
+    char szPathName[RTPATH_MAX] = { 0 };
+    uint32_t cbPathName = 0;
+    uint32_t fFlags     = 0;
+    uint32_t fMode      = 0;
+
+    do
+    {
+        LogFlowFunc(("Waiting for new message ...\n"));
+
+        uint32_t uNextMsg;
+        uint32_t cNextParms;
+        rc = vbglR3DnDGetNextMsgType(pCtx, &uNextMsg, &cNextParms, true /* fWait */);
+        if (RT_SUCCESS(rc))
+        {
+            LogFlowFunc(("uNextMsg=%RU32, cNextParms=%RU32\n", uNextMsg, cNextParms));
+
+            switch (uNextMsg)
+            {
+                case HOST_DND_FN_HG_SND_DIR:
+                {
+                    rc = vbglR3DnDHGRecvDir(pCtx,
+                                            szPathName,
+                                            sizeof(szPathName),
+                                            &cbPathName,
+                                            &fMode);
+                    LogFlowFunc(("HOST_DND_FN_HG_SND_DIR: "
+                                 "pszPathName=%s, cbPathName=%RU32, fMode=0x%x, rc=%Rrc\n",
+                                 szPathName, cbPathName, fMode, rc));
+
+                    char *pszPathAbs = RTPathJoinA(pszDropDir, szPathName);
+                    if (pszPathAbs)
+                    {
+#ifdef RT_OS_WINDOWS
+                        uint32_t fCreationMode = (fMode & RTFS_DOS_MASK) | RTFS_DOS_NT_NORMAL;
+#else
+                        uint32_t fCreationMode = (fMode & RTFS_UNIX_MASK) | RTFS_UNIX_IRWXU;
+#endif
+                        rc = RTDirCreate(pszPathAbs, fCreationMode, 0);
+                        if (RT_SUCCESS(rc))
+                            rc = DnDDroppedFilesAddDir(pDroppedFiles, pszPathAbs);
+
+                        if (RT_SUCCESS(rc))
+                        {
+                            Assert(cToRecvObjs);
+                            cToRecvObjs--;
+                        }
+
+                        RTStrFree(pszPathAbs);
+                    }
+                    else
+                        rc = VERR_NO_MEMORY;
+                    break;
+                }
+                case HOST_DND_FN_HG_SND_FILE_HDR:
+                    RT_FALL_THROUGH();
+                case HOST_DND_FN_HG_SND_FILE_DATA:
+                {
+                    if (uNextMsg == HOST_DND_FN_HG_SND_FILE_HDR)
+                    {
+                        rc = vbglR3DnDHGRecvFileHdr(pCtx,
+                                                    szPathName,
+                                                    sizeof(szPathName),
+                                                    &fFlags,
+                                                    &fMode,
+                                                    &cbFileSize);
+                        LogFlowFunc(("HOST_DND_FN_HG_SND_FILE_HDR: "
+                                     "szPathName=%s, fFlags=0x%x, fMode=0x%x, cbFileSize=%RU64, rc=%Rrc\n",
+                                     szPathName, fFlags, fMode, cbFileSize, rc));
+                    }
+                    else
+                    {
+                        rc = vbglR3DnDHGRecvFileData(pCtx,
+                                                     pvChunk,
+                                                     cbChunkMax,
+                                                     &cbChunkRead);
+                        LogFlowFunc(("HOST_DND_FN_HG_SND_FILE_DATA: "
+                                     "cbChunkRead=%RU32, rc=%Rrc\n", cbChunkRead, rc));
+                    }
+
+                    if (   RT_SUCCESS(rc)
+                        && uNextMsg == HOST_DND_FN_HG_SND_FILE_HDR)
+                    {
+                        char *pszPathAbs = RTPathJoinA(pszDropDir, szPathName);
+                        if (pszPathAbs)
+                        {
+                            LogFlowFunc(("Opening pszPathName=%s, cbPathName=%RU32, fMode=0x%x, cbFileSize=%zu\n",
+                                         szPathName, cbPathName, fMode, cbFileSize));
+
+                            uint64_t fOpen  =   RTFILE_O_WRITE | RTFILE_O_DENY_WRITE
+                                              | RTFILE_O_CREATE_REPLACE;
+
+                            /* Is there already a file open, e.g. in transfer? */
+                            if (!DnDTransferObjectIsOpen(&objCur))
+                            {
+#ifdef RT_OS_WINDOWS
+                                uint32_t fCreationMode = (fMode & RTFS_DOS_MASK) | RTFS_DOS_NT_NORMAL;
+#else
+                                uint32_t fCreationMode = (fMode & RTFS_UNIX_MASK) | RTFS_UNIX_IRUSR | RTFS_UNIX_IWUSR;
+#endif
+                                rc = DnDTransferObjectInitEx(&objCur, DNDTRANSFEROBJTYPE_FILE,
+                                                             pszDropDir /* Source (base) path */, szPathName /* Destination path */);
+                                if (RT_SUCCESS(rc))
+                                {
+                                    rc = DnDTransferObjectOpen(&objCur, fOpen, fCreationMode, DNDTRANSFEROBJECT_FLAGS_NONE);
+                                    if (RT_SUCCESS(rc))
+                                    {
+                                        rc = DnDDroppedFilesAddFile(pDroppedFiles, pszPathAbs);
+                                        if (RT_SUCCESS(rc))
+                                        {
+                                            cbFileWritten = 0;
+                                            DnDTransferObjectSetSize(&objCur, cbFileSize);
+                                        }
+                                    }
+                                }
+                            }
+                            else
+                            {
+                                AssertMsgFailed(("ObjType=%RU32\n", DnDTransferObjectGetType(&objCur)));
+                                rc = VERR_WRONG_ORDER;
+                            }
+
+                            RTStrFree(pszPathAbs);
+                        }
+                        else
+                            rc = VERR_NO_MEMORY;
+                    }
+
+                    if (   RT_SUCCESS(rc)
+                        && uNextMsg == HOST_DND_FN_HG_SND_FILE_DATA
+                        && cbChunkRead)
+                    {
+                        uint32_t cbChunkWritten;
+                        rc = DnDTransferObjectWrite(&objCur, pvChunk, cbChunkRead, &cbChunkWritten);
+                        if (RT_SUCCESS(rc))
+                        {
+                            LogFlowFunc(("HOST_DND_FN_HG_SND_FILE_DATA: "
+                                         "cbChunkRead=%RU32, cbChunkWritten=%RU32, cbFileWritten=%RU64 cbFileSize=%RU64\n",
+                                         cbChunkRead, cbChunkWritten, cbFileWritten + cbChunkWritten, cbFileSize));
+
+                            cbFileWritten += cbChunkWritten;
+
+                            Assert(cbChunkRead <= cbToRecvBytes);
+                            cbToRecvBytes -= cbChunkRead;
+                        }
+                    }
+
+                    /* Data transfer complete? Close the file. */
+                    bool fClose = DnDTransferObjectIsComplete(&objCur);
+                    if (fClose)
+                    {
+                        Assert(cToRecvObjs);
+                        cToRecvObjs--;
+                    }
+
+                    /* Only since protocol v2 we know the file size upfront. */
+                    Assert(cbFileWritten <= cbFileSize);
+
+                    if (fClose)
+                    {
+                        LogFlowFunc(("Closing file\n"));
+                        DnDTransferObjectDestroy(&objCur);
+                    }
+
+                    break;
+                }
+                case HOST_DND_FN_CANCEL:
+                {
+                    rc = vbglR3DnDHGRecvCancel(pCtx);
+                    if (RT_SUCCESS(rc))
+                        rc = VERR_CANCELLED;
+                    break;
+                }
+                default:
+                {
+                    LogRel(("DnD: Warning: Message %s (%#x) from host not supported or in wrong order\n", DnDHostMsgToStr(uNextMsg), uNextMsg));
+                    rc = VERR_NOT_SUPPORTED;
+                    break;
+                }
+            }
+        }
+
+        if (RT_FAILURE(rc))
+            break;
+
+        LogFlowFunc(("cbToRecvBytes=%RU64, cToRecvObjs=%RU64\n", cbToRecvBytes, cToRecvObjs));
+        if (   !cbToRecvBytes
+            && !cToRecvObjs)
+        {
+            break;
+        }
+
+    } while (RT_SUCCESS(rc));
+
+    LogFlowFunc(("Loop ended with %Rrc\n", rc));
+
+    /* All URI data processed? */
+    if (rc == VERR_NO_DATA)
+        rc = VINF_SUCCESS;
+
+    /* Delete temp buffer again. */
+    if (pvChunk)
+        RTMemFree(pvChunk);
+
+    /* Cleanup on failure or if the user has canceled the operation or
+     * something else went wrong. */
+    if (RT_FAILURE(rc))
+    {
+        if (rc == VERR_CANCELLED)
+            LogRel2(("DnD: Receiving URI data was cancelled by the host\n"));
+        else
+            LogRel(("DnD: Receiving URI data failed with %Rrc\n", rc));
+
+        DnDTransferObjectDestroy(&objCur);
+        DnDDroppedFilesRollback(pDroppedFiles);
+    }
+    else
+    {
+        LogRel2(("DnD: Receiving URI data finished\n"));
+
+        /** @todo Compare the transfer list with the dirs/files we really transferred. */
+        /** @todo Implement checksum verification, if any. */
+    }
+
+    /*
+     * Close the dropped files directory.
+     * Don't try to remove it here, however, as the files are being needed
+     * by the client's drag'n drop operation lateron.
+     */
+    int rc2 = DnDDroppedFilesReset(pDroppedFiles, false /* fRemoveDropDir */);
+    if (RT_FAILURE(rc2)) /* Not fatal, don't report back to host. */
+        LogFlowFunc(("Closing dropped files directory failed with %Rrc\n", rc2));
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Host -> Guest
+ * Utility function to receive the HOST_DND_FN_HG_SND_DATA message from the host.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to use.
+ * @param   pDataHdr            DnD data header to use. Need for accounting and stuff.
+ * @param   pvData              Where to store the received data from the host.
+ * @param   cbData              Size (in bytes) of where to store the received data.
+ * @param   pcbDataRecv         Where to store the received amount of data (in bytes).
+ */
+static int vbglR3DnDHGRecvDataRaw(PVBGLR3GUESTDNDCMDCTX pCtx, PVBOXDNDSNDDATAHDR pDataHdr,
+                                  void *pvData, uint32_t cbData, uint32_t *pcbDataRecv)
+{
+    AssertPtrReturn(pCtx,            VERR_INVALID_POINTER);
+    AssertPtrReturn(pDataHdr,        VERR_INVALID_POINTER);
+    AssertPtrReturn(pvData,          VERR_INVALID_POINTER);
+    AssertReturn(cbData,             VERR_INVALID_PARAMETER);
+    AssertPtrNullReturn(pcbDataRecv, VERR_INVALID_POINTER);
+
+    LogFlowFunc(("pvDate=%p, cbData=%RU32\n", pvData, cbData));
+
+    HGCMMsgHGSendData Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, HOST_DND_FN_HG_SND_DATA, 5);
+    Msg.u.v3.uContext.SetUInt32(0);
+    Msg.u.v3.pvData.SetPtr(pvData, cbData);
+    Msg.u.v3.cbData.SetUInt32(0);
+    Msg.u.v3.pvChecksum.SetPtr(NULL, 0);
+    Msg.u.v3.cbChecksum.SetUInt32(0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        uint32_t cbDataRecv;
+        rc = Msg.u.v3.cbData.GetUInt32(&cbDataRecv);
+        AssertRC(rc);
+        if (RT_SUCCESS(rc))
+        {
+            /** @todo Use checksum for validating the received data. */
+            if (pcbDataRecv)
+                *pcbDataRecv = cbDataRecv;
+            LogFlowFuncLeaveRC(rc);
+            return rc;
+        }
+    }
+
+    /* failure */
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Host -> Guest
+ * Utility function to receive the HOST_DND_FN_HG_SND_DATA_HDR message from the host.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to use.
+ * @param   pDataHdr            Where to store the receivd DnD data header.
+ */
+static int vbglR3DnDHGRecvDataHdr(PVBGLR3GUESTDNDCMDCTX pCtx, PVBOXDNDSNDDATAHDR pDataHdr)
+{
+    AssertPtrReturn(pCtx,     VERR_INVALID_POINTER);
+    AssertPtrReturn(pDataHdr, VERR_INVALID_POINTER);
+
+    Assert(pCtx->uProtocolDeprecated >= 3); /* Only for protocol v3 and up. */
+
+    HGCMMsgHGSendDataHdr Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, HOST_DND_FN_HG_SND_DATA_HDR, 12);
+    Msg.uContext.SetUInt32(0);
+    Msg.uFlags.SetUInt32(0);
+    Msg.uScreenId.SetUInt32(0);
+    Msg.cbTotal.SetUInt64(0);
+    Msg.cbMeta.SetUInt32(0);
+    Msg.pvMetaFmt.SetPtr(pDataHdr->pvMetaFmt, pDataHdr->cbMetaFmt);
+    Msg.cbMetaFmt.SetUInt32(0);
+    Msg.cObjects.SetUInt64(0);
+    Msg.enmCompression.SetUInt32(0);
+    Msg.enmChecksumType.SetUInt32(0);
+    Msg.pvChecksum.SetPtr(pDataHdr->pvChecksum, pDataHdr->cbChecksum);
+    Msg.cbChecksum.SetUInt32(0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        /* Msg.uContext not needed here. */
+        Msg.uFlags.GetUInt32(&pDataHdr->uFlags);
+        Msg.uScreenId.GetUInt32(&pDataHdr->uScreenId);
+        Msg.cbTotal.GetUInt64(&pDataHdr->cbTotal);
+        Msg.cbMeta.GetUInt32(&pDataHdr->cbMeta);
+        Msg.cbMetaFmt.GetUInt32(&pDataHdr->cbMetaFmt);
+        Msg.cObjects.GetUInt64(&pDataHdr->cObjects);
+        Msg.enmCompression.GetUInt32(&pDataHdr->enmCompression);
+        Msg.enmChecksumType.GetUInt32((uint32_t *)&pDataHdr->enmChecksumType);
+        Msg.cbChecksum.GetUInt32(&pDataHdr->cbChecksum);
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Host -> Guest
+ * Helper function for receiving the actual DnD data from the host. Do not call directly.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to use.
+ * @param   pDataHdr            Where to store the data header data.
+ * @param   ppvData             Returns the received meta data. Needs to be free'd by the caller.
+ * @param   pcbData             Where to store the size (in bytes) of the received meta data.
+ */
+static int vbglR3DnDHGRecvDataLoop(PVBGLR3GUESTDNDCMDCTX pCtx, PVBOXDNDSNDDATAHDR pDataHdr,
+                                   void **ppvData, uint64_t *pcbData)
+{
+    AssertPtrReturn(pCtx,     VERR_INVALID_POINTER);
+    AssertPtrReturn(pDataHdr, VERR_INVALID_POINTER);
+    AssertPtrReturn(ppvData,  VERR_INVALID_POINTER);
+    AssertPtrReturn(pcbData,  VERR_INVALID_POINTER);
+
+    int rc;
+    uint32_t cbDataRecv;
+
+    LogFlowFuncEnter();
+
+    rc = vbglR3DnDHGRecvDataHdr(pCtx, pDataHdr);
+    if (RT_FAILURE(rc))
+        return rc;
+
+    LogFlowFunc(("cbTotal=%RU64, cbMeta=%RU32, cObjects=%RU32\n", pDataHdr->cbTotal, pDataHdr->cbMeta, pDataHdr->cObjects));
+    if (pDataHdr->cbMeta)
+    {
+        uint64_t cbDataTmp = 0;
+        void    *pvDataTmp = RTMemAlloc(pDataHdr->cbMeta);
+        if (!pvDataTmp)
+            rc = VERR_NO_MEMORY;
+
+        if (RT_SUCCESS(rc))
+        {
+            uint8_t *pvDataOff = (uint8_t *)pvDataTmp;
+            while (cbDataTmp < pDataHdr->cbMeta)
+            {
+                rc = vbglR3DnDHGRecvDataRaw(pCtx, pDataHdr,
+                                            pvDataOff, RT_MIN(pDataHdr->cbMeta - cbDataTmp, pCtx->cbMaxChunkSize),
+                                            &cbDataRecv);
+                if (RT_SUCCESS(rc))
+                {
+                    LogFlowFunc(("cbDataRecv=%RU32, cbDataTmp=%RU64\n", cbDataRecv, cbDataTmp));
+                    Assert(cbDataTmp + cbDataRecv <= pDataHdr->cbMeta);
+                    cbDataTmp += cbDataRecv;
+                    pvDataOff += cbDataRecv;
+                }
+                else
+                    break;
+            }
+
+            if (RT_SUCCESS(rc))
+            {
+                Assert(cbDataTmp == pDataHdr->cbMeta);
+
+                LogFlowFunc(("Received %RU64 bytes of data\n", cbDataTmp));
+
+                *ppvData = pvDataTmp;
+                *pcbData = cbDataTmp;
+            }
+            else
+                RTMemFree(pvDataTmp);
+        }
+    }
+    else
+    {
+        *ppvData = NULL;
+        *pcbData = 0;
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Host -> Guest
+ * Main function for receiving the actual DnD data from the host.
+ *
+ * @returns VBox status code.
+ * @retval  VERR_CANCELLED if cancelled by the host.
+ * @param   pCtx                DnD context to use.
+ * @param   pMeta               Where to store the actual meta data received from the host.
+ */
+static int vbglR3DnDHGRecvDataMain(PVBGLR3GUESTDNDCMDCTX   pCtx,
+                                   PVBGLR3GUESTDNDMETADATA pMeta)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+    AssertPtrReturn(pMeta, VERR_INVALID_POINTER);
+
+    AssertMsgReturn(pCtx->cbMaxChunkSize, ("Maximum chunk size must not be 0\n"), VERR_INVALID_PARAMETER);
+
+    VBOXDNDDATAHDR dataHdr;
+    RT_ZERO(dataHdr);
+    dataHdr.cbMetaFmt = pCtx->cbMaxChunkSize;
+    dataHdr.pvMetaFmt = RTMemAlloc(dataHdr.cbMetaFmt);
+    if (!dataHdr.pvMetaFmt)
+        return VERR_NO_MEMORY;
+
+    void    *pvData = NULL;
+    uint64_t cbData = 0;
+    int rc = vbglR3DnDHGRecvDataLoop(pCtx, &dataHdr, &pvData, &cbData);
+    if (RT_SUCCESS(rc))
+    {
+        LogRel2(("DnD: Received %RU64 bytes meta data in format '%s'\n", cbData, (char *)dataHdr.pvMetaFmt));
+
+        /**
+         * Check if this is an URI event. If so, let VbglR3 do all the actual
+         * data transfer + file/directory creation internally without letting
+         * the caller know.
+         *
+         * This keeps the actual (guest OS-)dependent client (like VBoxClient /
+         * VBoxTray) small by not having too much redundant code.
+         */
+        Assert(dataHdr.cbMetaFmt);
+        AssertPtr(dataHdr.pvMetaFmt);
+        if (DnDMIMEHasFileURLs((char *)dataHdr.pvMetaFmt, dataHdr.cbMetaFmt)) /* URI data. */
+        {
+            DNDDROPPEDFILES droppedFiles;
+            RT_ZERO(droppedFiles);
+
+            rc = DnDDroppedFilesInit(&droppedFiles);
+            if (RT_SUCCESS(rc))
+                rc = DnDDroppedFilesOpenTemp(&droppedFiles, DNDURIDROPPEDFILE_FLAGS_NONE);
+
+            if (RT_FAILURE(rc))
+            {
+                LogRel(("DnD: Initializing dropped files directory failed with %Rrc\n", rc));
+            }
+            else
+            {
+                AssertPtr(pvData);
+                Assert(cbData);
+
+                /* Use the dropped files directory as the root directory for the current transfer. */
+                rc = DnDTransferListInitEx(&pMeta->u.URI.Transfer, DnDDroppedFilesGetDirAbs(&droppedFiles),
+                                           DNDTRANSFERLISTFMT_NATIVE);
+                if (RT_SUCCESS(rc))
+                {
+                    rc = DnDTransferListAppendRootsFromBuffer(&pMeta->u.URI.Transfer, DNDTRANSFERLISTFMT_URI, (const char *)pvData, cbData,
+                                                              DND_PATH_SEPARATOR_STR, 0 /* fFlags */);
+                    if (RT_SUCCESS(rc))
+                    {
+                        rc = vbglR3DnDHGRecvURIData(pCtx, &dataHdr, &droppedFiles);
+                        if (RT_SUCCESS(rc))
+                        {
+                            pMeta->enmType = VBGLR3GUESTDNDMETADATATYPE_URI_LIST;
+                        }
+                    }
+                }
+            }
+        }
+        else /* Raw data. */
+        {
+            pMeta->u.Raw.cbMeta = cbData;
+            pMeta->u.Raw.pvMeta = pvData;
+
+            pMeta->enmType = VBGLR3GUESTDNDMETADATATYPE_RAW;
+        }
+
+        if (pvData)
+            RTMemFree(pvData);
+    }
+
+    if (dataHdr.pvMetaFmt)
+        RTMemFree(dataHdr.pvMetaFmt);
+
+    if (RT_FAILURE(rc))
+    {
+        if (rc != VERR_CANCELLED)
+        {
+            LogRel(("DnD: Receiving data failed with %Rrc\n", rc));
+
+            int rc2 = VbglR3DnDHGSendProgress(pCtx, DND_PROGRESS_ERROR, 100 /* Percent */, rc);
+            if (RT_FAILURE(rc2))
+                LogRel(("DnD: Unable to send progress error %Rrc to host: %Rrc\n", rc, rc2));
+        }
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+#ifdef VBOX_WITH_DRAG_AND_DROP_GH
+/**
+ * Guest -> Host
+ * Utility function to receive the HOST_DND_FN_GH_REQ_PENDING message from the host.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to use.
+ * @param   puScreenID          For which screen on the host the request is for. Optional.
+ */
+static int vbglR3DnDGHRecvPending(PVBGLR3GUESTDNDCMDCTX pCtx, uint32_t *puScreenID)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+   /* pScreenID is optional. */
+
+    HGCMMsgGHReqPending Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, HOST_DND_FN_GH_REQ_PENDING, 2);
+    /** @todo Context ID not used yet. */
+    Msg.u.v3.uContext.SetUInt32(0);
+    Msg.u.v3.uScreenId.SetUInt32(0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        /** @todo Context ID not used yet. */
+        if (puScreenID)
+            rc = Msg.u.v3.uContext.GetUInt32(puScreenID);
+    }
+
+    return rc;
+}
+
+/**
+ * Guest -> Host
+ * Utility function to receive the HOST_DND_FN_GH_EVT_DROPPED message from the host.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to use.
+ * @param   ppszFormat          Requested data format from the host. Optional.
+ * @param   pcbFormat           Size of requested data format (in bytes). Optional.
+ * @param   puAction            Requested action from the host. Optional.
+ */
+static int vbglR3DnDGHRecvDropped(PVBGLR3GUESTDNDCMDCTX pCtx,
+                                  char     **ppszFormat,
+                                  uint32_t  *pcbFormat,
+                                  uint32_t  *puAction)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+    /* The rest is optional. */
+
+    const uint32_t cbFormatTmp = pCtx->cbMaxChunkSize;
+
+    char *pszFormatTmp = static_cast<char *>(RTMemAlloc(cbFormatTmp));
+    if (!pszFormatTmp)
+        return VERR_NO_MEMORY;
+
+    HGCMMsgGHDropped Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, HOST_DND_FN_GH_EVT_DROPPED, 4);
+    Msg.u.v3.uContext.SetUInt32(0);
+    Msg.u.v3.pvFormat.SetPtr(pszFormatTmp, cbFormatTmp);
+    Msg.u.v3.cbFormat.SetUInt32(0);
+    Msg.u.v3.uAction.SetUInt32(0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        /** @todo Context ID not used yet. */
+        if (pcbFormat)
+            rc = Msg.u.v3.cbFormat.GetUInt32(pcbFormat);
+        if (RT_SUCCESS(rc) && puAction)
+            rc = Msg.u.v3.uAction.GetUInt32(puAction);
+
+        if (RT_SUCCESS(rc))
+        {
+            *ppszFormat = RTStrDup(pszFormatTmp);
+            if (!*ppszFormat)
+                rc = VERR_NO_MEMORY;
+        }
+    }
+
+    RTMemFree(pszFormatTmp);
+
+    return rc;
+}
+#endif /* VBOX_WITH_DRAG_AND_DROP_GH */
+
+
+/*********************************************************************************************************************************
+*   Public functions                                                                                                             *
+*********************************************************************************************************************************/
+
+/**
+ * Connects a DnD context to the DnD host service.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to connect.
+ */
+VBGLR3DECL(int) VbglR3DnDConnect(PVBGLR3GUESTDNDCMDCTX pCtx)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    /* Initialize header */
+    int rc = VbglR3HGCMConnect("VBoxDragAndDropSvc", &pCtx->uClientID);
+    if (RT_FAILURE(rc))
+        return rc;
+    Assert(pCtx->uClientID);
+
+    /* Set the default protocol version we would like to use.
+     * Deprecated since VBox 6.1.x, but let this set to 3 to (hopefully) not break things. */
+    pCtx->uProtocolDeprecated = 3;
+
+    pCtx->fHostFeatures  = VBOX_DND_HF_NONE;
+    pCtx->fGuestFeatures = VBOX_DND_GF_NONE;
+
+    /*
+     * Get the VM's session ID.
+     * This is not fatal in case we're running with an ancient VBox version.
+     */
+    pCtx->uSessionID = 0;
+    int rc2 = VbglR3GetSessionId(&pCtx->uSessionID); RT_NOREF(rc2);
+    LogFlowFunc(("uSessionID=%RU64, rc=%Rrc\n", pCtx->uSessionID, rc2));
+
+    /*
+     * Try sending the connect message to tell the protocol version to use.
+     * Note: This might fail when the Guest Additions run on an older VBox host (< VBox 5.0) which
+     *       does not implement this command.
+     */
+    HGCMMsgConnect Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_DND_FN_CONNECT, 3);
+    Msg.u.v3.uContext.SetUInt32(0);                /** @todo Context ID not used yet. */
+    Msg.u.v3.uProtocol.SetUInt32(pCtx->uProtocolDeprecated); /* Deprecated since VBox 6.1.x. */
+    Msg.u.v3.uFlags.SetUInt32(0);                  /* Unused at the moment. */
+
+    rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (RT_SUCCESS(rc))
+    {
+        /* Set the protocol version we're going to use as told by the host. */
+        rc = Msg.u.v3.uProtocol.GetUInt32(&pCtx->uProtocolDeprecated); AssertRC(rc);
+
+        /*
+         * Next is reporting our features.  If this fails, assume older host.
+         */
+        rc2 = VbglR3DnDReportFeatures(pCtx->uClientID, pCtx->fGuestFeatures, &pCtx->fHostFeatures);
+        if (RT_SUCCESS(rc2))
+        {
+            LogRel2(("DnD: Guest features: %#RX64 - Host features: %#RX64\n",
+                     pCtx->fGuestFeatures, pCtx->fHostFeatures));
+        }
+        else /* Failing here is not fatal; might be running with an older host. */
+        {
+            AssertLogRelMsg(rc2 == VERR_NOT_SUPPORTED || rc2 == VERR_NOT_IMPLEMENTED,
+                            ("Reporting features failed: %Rrc\n", rc2));
+        }
+
+        pCtx->cbMaxChunkSize = DND_DEFAULT_CHUNK_SIZE; /** @todo Use a scratch buffer on the heap? */
+    }
+    else
+        pCtx->uProtocolDeprecated = 0; /*  We're using protocol v0 (initial draft) as a fallback. */
+
+    LogFlowFunc(("uClient=%RU32, uProtocol=%RU32, rc=%Rrc\n", pCtx->uClientID, pCtx->uProtocolDeprecated, rc));
+    return rc;
+}
+
+/**
+ * Disconnects a given DnD context from the DnD host service.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to disconnect.
+ *                              The context is invalid afterwards on successful disconnection.
+ */
+VBGLR3DECL(int) VbglR3DnDDisconnect(PVBGLR3GUESTDNDCMDCTX pCtx)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    if (!pCtx->uClientID) /* Already disconnected? Bail out early. */
+        return VINF_SUCCESS;
+
+    int rc = VbglR3HGCMDisconnect(pCtx->uClientID);
+    if (RT_SUCCESS(rc))
+        pCtx->uClientID = 0;
+
+    return rc;
+}
+
+/**
+ * Reports features to the host and retrieve host feature set.
+ *
+ * @returns VBox status code.
+ * @param   idClient        The client ID returned by VbglR3DnDConnect().
+ * @param   fGuestFeatures  Features to report, VBOX_DND_GF_XXX.
+ * @param   pfHostFeatures  Where to store the features VBOX_DND_HF_XXX.
+ */
+VBGLR3DECL(int) VbglR3DnDReportFeatures(uint32_t idClient, uint64_t fGuestFeatures, uint64_t *pfHostFeatures)
+{
+    int rc;
+    do
+    {
+        struct
+        {
+            VBGLIOCHGCMCALL         Hdr;
+            HGCMFunctionParameter   f64Features0;
+            HGCMFunctionParameter   f64Features1;
+        } Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.Hdr, idClient, GUEST_DND_FN_REPORT_FEATURES, 2);
+        VbglHGCMParmUInt64Set(&Msg.f64Features0, fGuestFeatures);
+        VbglHGCMParmUInt64Set(&Msg.f64Features1, VBOX_DND_GF_1_MUST_BE_ONE);
+
+        rc = VbglR3HGCMCall(&Msg.Hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            Assert(Msg.f64Features0.type == VMMDevHGCMParmType_64bit);
+            Assert(Msg.f64Features1.type == VMMDevHGCMParmType_64bit);
+            if (Msg.f64Features1.u.value64 & VBOX_DND_GF_1_MUST_BE_ONE)
+                rc = VERR_NOT_SUPPORTED;
+            else if (pfHostFeatures)
+                *pfHostFeatures = Msg.f64Features0.u.value64;
+            break;
+        }
+    } while (rc == VERR_INTERRUPTED);
+    return rc;
+
+}
+
+/**
+ * Receives the next upcoming DnD event.
+ *
+ * This is the main function DnD clients call in order to implement any DnD functionality.
+ * The purpose of it is to abstract the actual DnD protocol handling as much as possible from
+ * the clients -- those only need to react to certain events, regardless of how the underlying
+ * protocol actually is working.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                DnD context to work with.
+ * @param   ppEvent             Next DnD event received on success; needs to be free'd by the client calling
+ *                              VbglR3DnDEventFree() when done.
+ */
+VBGLR3DECL(int) VbglR3DnDEventGetNext(PVBGLR3GUESTDNDCMDCTX pCtx, PVBGLR3DNDEVENT *ppEvent)
+{
+    AssertPtrReturn(pCtx,    VERR_INVALID_POINTER);
+    AssertPtrReturn(ppEvent, VERR_INVALID_POINTER);
+
+    PVBGLR3DNDEVENT pEvent = (PVBGLR3DNDEVENT)RTMemAllocZ(sizeof(VBGLR3DNDEVENT));
+    if (!pEvent)
+        return VERR_NO_MEMORY;
+
+    uint32_t uMsg   = 0;
+    uint32_t cParms = 0;
+    int rc = vbglR3DnDGetNextMsgType(pCtx, &uMsg, &cParms, true /* fWait */);
+    if (RT_SUCCESS(rc))
+    {
+        /* Check for VM session change. */
+        uint64_t uSessionID;
+        int rc2 = VbglR3GetSessionId(&uSessionID);
+        if (   RT_SUCCESS(rc2)
+            && (uSessionID != pCtx->uSessionID))
+        {
+            LogRel2(("DnD: VM session ID changed to %RU64\n", uSessionID));
+            rc = VbglR3DnDDisconnect(pCtx);
+            if (RT_SUCCESS(rc))
+                rc = VbglR3DnDConnect(pCtx);
+        }
+    }
+
+    if (rc == VERR_CANCELLED) /* Host service told us that we have to bail out. */
+    {
+        LogRel2(("DnD: Host service requested termination\n"));
+
+        pEvent->enmType = VBGLR3DNDEVENTTYPE_QUIT;
+        *ppEvent = pEvent;
+
+        return VINF_SUCCESS;
+    }
+
+    if (RT_SUCCESS(rc))
+    {
+        LogFunc(("Handling uMsg=%RU32\n", uMsg));
+
+        switch(uMsg)
+        {
+            case HOST_DND_FN_HG_EVT_ENTER:
+            {
+                rc = vbglR3DnDHGRecvAction(pCtx,
+                                           uMsg,
+                                           &pEvent->u.HG_Enter.uScreenID,
+                                           NULL /* puXPos */,
+                                           NULL /* puYPos */,
+                                           NULL /* uDefAction */,
+                                           &pEvent->u.HG_Enter.dndLstActionsAllowed,
+                                           &pEvent->u.HG_Enter.pszFormats,
+                                           &pEvent->u.HG_Enter.cbFormats);
+                if (RT_SUCCESS(rc))
+                    pEvent->enmType = VBGLR3DNDEVENTTYPE_HG_ENTER;
+                break;
+            }
+            case HOST_DND_FN_HG_EVT_MOVE:
+            {
+                rc = vbglR3DnDHGRecvAction(pCtx,
+                                           uMsg,
+                                           NULL /* puScreenId */,
+                                           &pEvent->u.HG_Move.uXpos,
+                                           &pEvent->u.HG_Move.uYpos,
+                                           &pEvent->u.HG_Move.dndActionDefault,
+                                           NULL /* puAllActions */,
+                                           NULL /* pszFormats */,
+                                           NULL /* pcbFormats */);
+                if (RT_SUCCESS(rc))
+                    pEvent->enmType = VBGLR3DNDEVENTTYPE_HG_MOVE;
+                break;
+            }
+            case HOST_DND_FN_HG_EVT_DROPPED:
+            {
+                rc = vbglR3DnDHGRecvAction(pCtx,
+                                           uMsg,
+                                           NULL /* puScreenId */,
+                                           &pEvent->u.HG_Drop.uXpos,
+                                           &pEvent->u.HG_Drop.uYpos,
+                                           &pEvent->u.HG_Drop.dndActionDefault,
+                                           NULL /* puAllActions */,
+                                           NULL /* pszFormats */,
+                                           NULL /* pcbFormats */);
+                if (RT_SUCCESS(rc))
+                    pEvent->enmType = VBGLR3DNDEVENTTYPE_HG_DROP;
+                break;
+            }
+            case HOST_DND_FN_HG_EVT_LEAVE:
+            {
+                rc = vbglR3DnDHGRecvLeave(pCtx);
+                if (RT_SUCCESS(rc))
+                    pEvent->enmType = VBGLR3DNDEVENTTYPE_HG_LEAVE;
+                break;
+            }
+            case HOST_DND_FN_HG_SND_DATA_HDR:
+            {
+                rc = vbglR3DnDHGRecvDataMain(pCtx, &pEvent->u.HG_Received.Meta);
+                if (RT_SUCCESS(rc))
+                    pEvent->enmType = VBGLR3DNDEVENTTYPE_HG_RECEIVE;
+                break;
+            }
+            case HOST_DND_FN_HG_SND_DIR:
+                RT_FALL_THROUGH();
+            case HOST_DND_FN_HG_SND_FILE_HDR:
+                RT_FALL_THROUGH();
+            case HOST_DND_FN_HG_SND_FILE_DATA:
+            {
+                /*
+                 * All messages for this block are handled internally
+                 * by vbglR3DnDHGRecvDataMain(), see above.
+                 *
+                 * So if we land here our code is buggy.
+                 */
+                rc = VERR_WRONG_ORDER;
+                break;
+            }
+            case HOST_DND_FN_CANCEL:
+            {
+                rc = vbglR3DnDHGRecvCancel(pCtx);
+                if (RT_SUCCESS(rc))
+                    rc = VERR_CANCELLED; /* Will emit a cancel event below. */
+                break;
+            }
+#ifdef VBOX_WITH_DRAG_AND_DROP_GH
+            case HOST_DND_FN_GH_REQ_PENDING:
+            {
+                rc = vbglR3DnDGHRecvPending(pCtx, &pEvent->u.GH_IsPending.uScreenID);
+                if (RT_SUCCESS(rc))
+                    pEvent->enmType = VBGLR3DNDEVENTTYPE_GH_REQ_PENDING;
+                break;
+            }
+            case HOST_DND_FN_GH_EVT_DROPPED:
+            {
+                rc = vbglR3DnDGHRecvDropped(pCtx,
+                                            &pEvent->u.GH_Drop.pszFormat,
+                                            &pEvent->u.GH_Drop.cbFormat,
+                                            &pEvent->u.GH_Drop.dndActionRequested);
+                if (RT_SUCCESS(rc))
+                    pEvent->enmType = VBGLR3DNDEVENTTYPE_GH_DROP;
+                break;
+            }
+#endif
+            default:
+            {
+                rc = VERR_NOT_SUPPORTED;
+                break;
+            }
+        }
+    }
+
+    if (RT_FAILURE(rc))
+    {
+        /* Current operation cancelled? Set / overwrite event type and tell the caller. */
+        if (rc == VERR_CANCELLED)
+        {
+            pEvent->enmType = VBGLR3DNDEVENTTYPE_CANCEL;
+            rc              = VINF_SUCCESS; /* Deliver the event to the caller. */
+        }
+        else
+        {
+            VbglR3DnDEventFree(pEvent);
+            LogRel(("DnD: Handling message %s (%#x) failed with %Rrc\n", DnDHostMsgToStr(uMsg), uMsg, rc));
+        }
+    }
+
+    if (RT_SUCCESS(rc))
+        *ppEvent = pEvent;
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Frees (destroys) a formerly allocated DnD event.
+ *
+ * @returns IPRT status code.
+ * @param   pEvent              Event to free (destroy).
+ */
+VBGLR3DECL(void) VbglR3DnDEventFree(PVBGLR3DNDEVENT pEvent)
+{
+    if (!pEvent)
+        return;
+
+    /* Some messages require additional cleanup. */
+    switch (pEvent->enmType)
+    {
+        case VBGLR3DNDEVENTTYPE_HG_ENTER:
+        {
+            if (pEvent->u.HG_Enter.pszFormats)
+                RTStrFree(pEvent->u.HG_Enter.pszFormats);
+            break;
+        }
+
+#ifdef VBOX_WITH_DRAG_AND_DROP_GH
+        case VBGLR3DNDEVENTTYPE_GH_DROP:
+        {
+            if (pEvent->u.GH_Drop.pszFormat)
+                RTStrFree(pEvent->u.GH_Drop.pszFormat);
+            break;
+        }
+#endif
+        case VBGLR3DNDEVENTTYPE_HG_RECEIVE:
+        {
+            PVBGLR3GUESTDNDMETADATA pMeta = &pEvent->u.HG_Received.Meta;
+            switch (pMeta->enmType)
+            {
+                case VBGLR3GUESTDNDMETADATATYPE_RAW:
+                {
+                    if (pMeta->u.Raw.pvMeta)
+                    {
+                        Assert(pMeta->u.Raw.cbMeta);
+                        RTMemFree(pMeta->u.Raw.pvMeta);
+                        pMeta->u.Raw.cbMeta = 0;
+                    }
+                    break;
+                }
+
+                case VBGLR3GUESTDNDMETADATATYPE_URI_LIST:
+                {
+                    DnDTransferListDestroy(&pMeta->u.URI.Transfer);
+                    break;
+                }
+
+                default:
+                    break;
+            }
+            break;
+        }
+
+        default:
+            break;
+    }
+
+    RTMemFree(pEvent);
+    pEvent = NULL;
+}
+
+VBGLR3DECL(int) VbglR3DnDHGSendAckOp(PVBGLR3GUESTDNDCMDCTX pCtx, VBOXDNDACTION dndAction)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    HGCMMsgHGAck Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_DND_FN_HG_ACK_OP, 2);
+    /** @todo Context ID not used yet. */
+    Msg.u.v3.uContext.SetUInt32(0);
+    Msg.u.v3.uAction.SetUInt32(dndAction);
+
+    return VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+}
+
+/**
+ * Host -> Guest
+ * Requests the actual DnD data to be sent from the host.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to use.
+ * @param   pcszFormat          Format to request the data from the host in.
+ */
+VBGLR3DECL(int) VbglR3DnDHGSendReqData(PVBGLR3GUESTDNDCMDCTX pCtx, const char* pcszFormat)
+{
+    AssertPtrReturn(pCtx,       VERR_INVALID_POINTER);
+    AssertPtrReturn(pcszFormat, VERR_INVALID_POINTER);
+    if (!RTStrIsValidEncoding(pcszFormat))
+        return VERR_INVALID_PARAMETER;
+
+    const uint32_t cbFormat = (uint32_t)strlen(pcszFormat) + 1; /* Include termination */
+
+    HGCMMsgHGReqData Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_DND_FN_HG_REQ_DATA, 3);
+    /** @todo Context ID not used yet. */
+    Msg.u.v3.uContext.SetUInt32(0);
+    Msg.u.v3.pvFormat.SetPtr((void*)pcszFormat, cbFormat);
+    Msg.u.v3.cbFormat.SetUInt32(cbFormat);
+
+    return VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+}
+
+/**
+ * Host -> Guest
+ * Reports back its progress back to the host.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to use.
+ * @param   uStatus             DnD status to report.
+ * @param   uPercent            Overall progress (in percent) to report.
+ * @param   rcErr               Error code (IPRT-style) to report.
+ */
+VBGLR3DECL(int) VbglR3DnDHGSendProgress(PVBGLR3GUESTDNDCMDCTX pCtx, uint32_t uStatus, uint8_t uPercent, int rcErr)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+    AssertReturn(uStatus > DND_PROGRESS_UNKNOWN, VERR_INVALID_PARAMETER);
+
+    HGCMMsgHGProgress Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_DND_FN_HG_EVT_PROGRESS, 4);
+    /** @todo Context ID not used yet. */
+    Msg.u.v3.uContext.SetUInt32(0);
+    Msg.u.v3.uStatus.SetUInt32(uStatus);
+    Msg.u.v3.uPercent.SetUInt32(uPercent);
+    Msg.u.v3.rc.SetUInt32((uint32_t)rcErr); /* uint32_t vs. int. */
+
+    return VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+}
+
+#ifdef VBOX_WITH_DRAG_AND_DROP_GH
+/**
+ * Guest -> Host
+ * Acknowledges that there currently is a drag'n drop operation in progress on the guest,
+ * which eventually could be dragged over to the host.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                 DnD context to use.
+ * @param   dndActionDefault     Default action for the operation to report.
+ * @param   dndLstActionsAllowed All available actions for the operation to report.
+ * @param   pcszFormats          Available formats for the operation to report.
+ * @param   cbFormats            Size (in bytes) of formats to report.
+ */
+VBGLR3DECL(int) VbglR3DnDGHSendAckPending(PVBGLR3GUESTDNDCMDCTX pCtx,
+                                          VBOXDNDACTION dndActionDefault, VBOXDNDACTIONLIST dndLstActionsAllowed,
+                                          const char* pcszFormats, uint32_t cbFormats)
+{
+    AssertPtrReturn(pCtx,        VERR_INVALID_POINTER);
+    AssertPtrReturn(pcszFormats, VERR_INVALID_POINTER);
+    AssertReturn(cbFormats,      VERR_INVALID_PARAMETER);
+
+    if (!RTStrIsValidEncoding(pcszFormats))
+        return VERR_INVALID_UTF8_ENCODING;
+
+    HGCMMsgGHAckPending Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_DND_FN_GH_ACK_PENDING, 5);
+    /** @todo Context ID not used yet. */
+    Msg.u.v3.uContext.SetUInt32(0);
+    Msg.u.v3.uDefAction.SetUInt32(dndActionDefault);
+    Msg.u.v3.uAllActions.SetUInt32(dndLstActionsAllowed);
+    Msg.u.v3.pvFormats.SetPtr((void*)pcszFormats, cbFormats);
+    Msg.u.v3.cbFormats.SetUInt32(cbFormats);
+
+    return VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+}
+
+/**
+ * Guest -> Host
+ * Utility function to send DnD data from guest to the host.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to use.
+ * @param   pvData              Data block to send.
+ * @param   cbData              Size (in bytes) of data block to send.
+ * @param   pDataHdr            Data header to use -- needed for accounting.
+ */
+static int vbglR3DnDGHSendDataInternal(PVBGLR3GUESTDNDCMDCTX pCtx,
+                                       void *pvData, uint64_t cbData, PVBOXDNDSNDDATAHDR pDataHdr)
+{
+    AssertPtrReturn(pCtx,     VERR_INVALID_POINTER);
+    AssertPtrReturn(pvData,   VERR_INVALID_POINTER);
+    AssertReturn(cbData,      VERR_INVALID_PARAMETER);
+    AssertPtrReturn(pDataHdr, VERR_INVALID_POINTER);
+
+    HGCMMsgGHSendDataHdr MsgHdr;
+    VBGL_HGCM_HDR_INIT(&MsgHdr.hdr, pCtx->uClientID, GUEST_DND_FN_GH_SND_DATA_HDR, 12);
+    MsgHdr.uContext.SetUInt32(0);                           /** @todo Not used yet. */
+    MsgHdr.uFlags.SetUInt32(0);                             /** @todo Not used yet. */
+    MsgHdr.uScreenId.SetUInt32(0);                          /** @todo Not used for guest->host (yet). */
+    MsgHdr.cbTotal.SetUInt64(pDataHdr->cbTotal);
+    MsgHdr.cbMeta.SetUInt32(pDataHdr->cbMeta);
+    MsgHdr.pvMetaFmt.SetPtr(pDataHdr->pvMetaFmt, pDataHdr->cbMetaFmt);
+    MsgHdr.cbMetaFmt.SetUInt32(pDataHdr->cbMetaFmt);
+    MsgHdr.cObjects.SetUInt64(pDataHdr->cObjects);
+    MsgHdr.enmCompression.SetUInt32(0);                     /** @todo Not used yet. */
+    MsgHdr.enmChecksumType.SetUInt32(RTDIGESTTYPE_INVALID); /** @todo Not used yet. */
+    MsgHdr.pvChecksum.SetPtr(NULL, 0);                      /** @todo Not used yet. */
+    MsgHdr.cbChecksum.SetUInt32(0);                         /** @todo Not used yet. */
+
+    int rc = VbglR3HGCMCall(&MsgHdr.hdr, sizeof(MsgHdr));
+
+    LogFlowFunc(("cbTotal=%RU64, cbMeta=%RU32, cObjects=%RU64, rc=%Rrc\n",
+                 pDataHdr->cbTotal, pDataHdr->cbMeta, pDataHdr->cObjects, rc));
+
+    if (RT_SUCCESS(rc))
+    {
+        HGCMMsgGHSendData MsgData;
+        VBGL_HGCM_HDR_INIT(&MsgData.hdr, pCtx->uClientID, GUEST_DND_FN_GH_SND_DATA, 5);
+        MsgData.u.v3.uContext.SetUInt32(0);      /** @todo Not used yet. */
+        MsgData.u.v3.pvChecksum.SetPtr(NULL, 0); /** @todo Not used yet. */
+        MsgData.u.v3.cbChecksum.SetUInt32(0);    /** @todo Not used yet. */
+
+        uint32_t       cbCurChunk;
+        const uint32_t cbMaxChunk = pCtx->cbMaxChunkSize;
+        uint32_t       cbSent     = 0;
+
+        while (cbSent < cbData)
+        {
+            cbCurChunk = RT_MIN(cbData - cbSent, cbMaxChunk);
+            MsgData.u.v3.pvData.SetPtr(static_cast<uint8_t *>(pvData) + cbSent, cbCurChunk);
+            MsgData.u.v3.cbData.SetUInt32(cbCurChunk);
+
+            rc = VbglR3HGCMCall(&MsgData.hdr, sizeof(MsgData));
+            if (RT_FAILURE(rc))
+                break;
+
+            cbSent += cbCurChunk;
+        }
+
+        LogFlowFunc(("cbMaxChunk=%RU32, cbData=%RU64, cbSent=%RU32, rc=%Rrc\n",
+                     cbMaxChunk, cbData, cbSent, rc));
+
+        if (RT_SUCCESS(rc))
+            Assert(cbSent == cbData);
+    }
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Guest -> Host
+ * Utility function to send a guest directory to the host.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to use.
+ * @param   pObj                transfer object containing the directory to send.
+ */
+static int vbglR3DnDGHSendDir(PVBGLR3GUESTDNDCMDCTX pCtx, DNDTRANSFEROBJECT *pObj)
+{
+    AssertPtrReturn(pObj,                                         VERR_INVALID_POINTER);
+    AssertPtrReturn(pCtx,                                         VERR_INVALID_POINTER);
+    AssertReturn(DnDTransferObjectGetType(pObj) == DNDTRANSFEROBJTYPE_DIRECTORY, VERR_INVALID_PARAMETER);
+
+    const char *pcszPath = DnDTransferObjectGetDestPath(pObj);
+    const size_t cbPath  = RTStrNLen(pcszPath, RTPATH_MAX) + 1 /* Include termination. */;
+    const RTFMODE fMode  = DnDTransferObjectGetMode(pObj);
+
+    LogFlowFunc(("strDir=%s (%zu bytes), fMode=0x%x\n", pcszPath, cbPath, fMode));
+
+    if (cbPath > RTPATH_MAX + 1) /* Can't happen, but check anyway. */
+        return VERR_INVALID_PARAMETER;
+
+    HGCMMsgGHSendDir Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_DND_FN_GH_SND_DIR, 4);
+    /** @todo Context ID not used yet. */
+    Msg.u.v3.uContext.SetUInt32(0);
+    Msg.u.v3.pvName.SetPtr((void *)pcszPath, (uint32_t)cbPath);
+    Msg.u.v3.cbName.SetUInt32((uint32_t)cbPath);
+    Msg.u.v3.fMode.SetUInt32(fMode);
+
+    return VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+}
+
+/**
+ * Guest -> Host
+ * Utility function to send a file from the guest to the host.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to use.
+ * @param   pObj                Transfer object containing the file to send.
+ */
+static int vbglR3DnDGHSendFile(PVBGLR3GUESTDNDCMDCTX pCtx, PDNDTRANSFEROBJECT pObj)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+    AssertPtrReturn(pObj, VERR_INVALID_POINTER);
+    AssertReturn(DnDTransferObjectIsOpen(pObj) == false, VERR_INVALID_STATE);
+    AssertReturn(DnDTransferObjectGetType(pObj) == DNDTRANSFEROBJTYPE_FILE, VERR_INVALID_PARAMETER);
+
+    uint64_t fOpen = RTFILE_O_OPEN | RTFILE_O_READ | RTFILE_O_DENY_WRITE;
+
+    int rc = DnDTransferObjectOpen(pObj, fOpen, 0 /* fMode */, DNDTRANSFEROBJECT_FLAGS_NONE);
+    if (RT_FAILURE(rc))
+        return rc;
+
+    uint32_t cbBuf = pCtx->cbMaxChunkSize;
+    AssertReturn(cbBuf, VERR_INVALID_PARAMETER);
+    void *pvBuf = RTMemAlloc(cbBuf); /** @todo Make this buffer part of PVBGLR3GUESTDNDCMDCTX? */
+    if (!pvBuf)
+    {
+        int rc2 = DnDTransferObjectClose(pObj);
+        AssertRC(rc2);
+        return VERR_NO_MEMORY;
+    }
+
+    const char *pcszPath  = DnDTransferObjectGetDestPath(pObj);
+    const size_t cchPath  = RTStrNLen(pcszPath, RTPATH_MAX);
+    const uint64_t cbSize = DnDTransferObjectGetSize(pObj);
+    const RTFMODE fMode   = DnDTransferObjectGetMode(pObj);
+
+    LogFlowFunc(("strFile=%s (%zu), cbSize=%RU64, fMode=0x%x\n", pcszPath, cchPath, cbSize, fMode));
+
+    HGCMMsgGHSendFileHdr MsgHdr;
+    VBGL_HGCM_HDR_INIT(&MsgHdr.hdr, pCtx->uClientID, GUEST_DND_FN_GH_SND_FILE_HDR, 6);
+    MsgHdr.uContext.SetUInt32(0);                                                    /* Context ID; unused at the moment. */
+    MsgHdr.pvName.SetPtr((void *)pcszPath, (uint32_t)(cchPath + 1));                 /* Include termination. */
+    MsgHdr.cbName.SetUInt32((uint32_t)(cchPath + 1));                                /* Ditto. */
+    MsgHdr.uFlags.SetUInt32(0);                                                      /* Flags; unused at the moment. */
+    MsgHdr.fMode.SetUInt32(fMode);                                                   /* File mode */
+    MsgHdr.cbTotal.SetUInt64(cbSize);                                                /* File size (in bytes). */
+
+    rc = VbglR3HGCMCall(&MsgHdr.hdr, sizeof(MsgHdr));
+
+    LogFlowFunc(("Sending file header resulted in %Rrc\n", rc));
+
+    if (RT_SUCCESS(rc))
+    {
+        /*
+         * Send the actual file data, chunk by chunk.
+         */
+        HGCMMsgGHSendFileData Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_DND_FN_GH_SND_FILE_DATA, 5);
+        Msg.u.v3.uContext.SetUInt32(0);
+        Msg.u.v3.pvChecksum.SetPtr(NULL, 0);
+        Msg.u.v3.cbChecksum.SetUInt32(0);
+
+        uint64_t cbToReadTotal  = cbSize;
+        uint64_t cbWrittenTotal = 0;
+        while (cbToReadTotal)
+        {
+            uint32_t cbToRead = RT_MIN(cbToReadTotal, cbBuf);
+            uint32_t cbRead   = 0;
+            if (cbToRead)
+                rc = DnDTransferObjectRead(pObj, pvBuf, cbToRead, &cbRead);
+
+            LogFlowFunc(("cbToReadTotal=%RU64, cbToRead=%RU32, cbRead=%RU32, rc=%Rrc\n",
+                         cbToReadTotal, cbToRead, cbRead, rc));
+
+            if (   RT_SUCCESS(rc)
+                && cbRead)
+            {
+                Msg.u.v3.pvData.SetPtr(pvBuf, cbRead);
+                Msg.u.v3.cbData.SetUInt32(cbRead);
+                /** @todo Calculate + set checksums. */
+
+                rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+            }
+
+            if (RT_FAILURE(rc))
+            {
+                LogFlowFunc(("Reading failed with rc=%Rrc\n", rc));
+                break;
+            }
+
+            Assert(cbRead  <= cbToReadTotal);
+            cbToReadTotal  -= cbRead;
+            cbWrittenTotal += cbRead;
+
+            LogFlowFunc(("%RU64/%RU64 -- %RU8%%\n", cbWrittenTotal, cbSize, cbWrittenTotal * 100 / cbSize));
+        };
+    }
+
+    RTMemFree(pvBuf);
+    int rc2 = DnDTransferObjectClose(pObj);
+    if (RT_SUCCESS(rc))
+        rc = rc2;
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Guest -> Host
+ * Utility function to send a transfer object from guest to the host.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to use.
+ * @param   pObj                Transfer object to send from guest to the host.
+ */
+static int vbglR3DnDGHSendURIObject(PVBGLR3GUESTDNDCMDCTX pCtx, PDNDTRANSFEROBJECT pObj)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+    AssertPtrReturn(pObj, VERR_INVALID_POINTER);
+
+    int rc;
+
+    const DNDTRANSFEROBJTYPE enmType = DnDTransferObjectGetType(pObj);
+
+    switch (enmType)
+    {
+        case DNDTRANSFEROBJTYPE_DIRECTORY:
+            rc = vbglR3DnDGHSendDir(pCtx, pObj);
+            break;
+
+        case DNDTRANSFEROBJTYPE_FILE:
+            rc = vbglR3DnDGHSendFile(pCtx, pObj);
+            break;
+
+        default:
+            AssertMsgFailed(("Object type %ld not implemented\n", enmType));
+            rc = VERR_NOT_IMPLEMENTED;
+            break;
+    }
+
+    return rc;
+}
+
+/**
+ * Guest -> Host
+ * Utility function to send raw data from guest to the host.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to use.
+ * @param   pvData              Block to raw data to send.
+ * @param   cbData              Size (in bytes) of raw data to send.
+ */
+static int vbglR3DnDGHSendRawData(PVBGLR3GUESTDNDCMDCTX pCtx, void *pvData, size_t cbData)
+{
+    AssertPtrReturn(pCtx,   VERR_INVALID_POINTER);
+    AssertPtrReturn(pvData, VERR_INVALID_POINTER);
+    /* cbData can be 0. */
+
+    VBOXDNDDATAHDR dataHdr;
+    RT_ZERO(dataHdr);
+
+    dataHdr.cbMeta  = (uint32_t)cbData;
+    dataHdr.cbTotal = cbData;
+
+    return vbglR3DnDGHSendDataInternal(pCtx, pvData, cbData, &dataHdr);
+}
+
+/**
+ * Guest -> Host
+ * Utility function to send transfer data from guest to the host.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to use.
+ * @param   pTransferList       Dnd transfer list to send.
+ */
+static int vbglR3DnDGHSendTransferData(PVBGLR3GUESTDNDCMDCTX pCtx, PDNDTRANSFERLIST pTransferList)
+{
+    AssertPtrReturn(pCtx,VERR_INVALID_POINTER);
+    AssertPtrReturn(pTransferList, VERR_INVALID_POINTER);
+
+    /*
+     * Send the (meta) data; in case of URIs it's the root entries of a
+     * transfer list the host needs to know upfront to set up the drag'n drop operation.
+     */
+    char *pszList = NULL;
+    size_t cbList;
+    int rc = DnDTransferListGetRoots(pTransferList, DNDTRANSFERLISTFMT_URI, &pszList, &cbList);
+    if (RT_FAILURE(rc))
+        return rc;
+
+    void    *pvURIList = (void *)pszList;
+    uint32_t cbURLIist = (uint32_t)cbList;
+
+    /* The total size also contains the size of the meta data. */
+    uint64_t cbTotal  = cbURLIist;
+             cbTotal += DnDTransferListObjTotalBytes(pTransferList);
+
+    /* We're going to send a transfer list in text format. */
+    const char     szMetaFmt[] = "text/uri-list";
+    const uint32_t cbMetaFmt   = (uint32_t)strlen(szMetaFmt) + 1; /* Include termination. */
+
+    VBOXDNDDATAHDR dataHdr;
+    dataHdr.uFlags    = 0; /* Flags not used yet. */
+    dataHdr.cbTotal   = cbTotal;
+    dataHdr.cbMeta    = cbURLIist;
+    dataHdr.pvMetaFmt = (void *)szMetaFmt;
+    dataHdr.cbMetaFmt = cbMetaFmt;
+    dataHdr.cObjects  = DnDTransferListObjCount(pTransferList);
+
+    rc = vbglR3DnDGHSendDataInternal(pCtx, pvURIList, cbURLIist, &dataHdr);
+
+    if (RT_SUCCESS(rc))
+    {
+        while (DnDTransferListObjCount(pTransferList))
+        {
+            PDNDTRANSFEROBJECT pObj = DnDTransferListObjGetFirst(pTransferList);
+
+            rc = vbglR3DnDGHSendURIObject(pCtx, pObj);
+            if (RT_FAILURE(rc))
+                break;
+
+            DnDTransferListObjRemoveFirst(pTransferList);
+        }
+
+        Assert(DnDTransferListObjCount(pTransferList) == 0);
+    }
+
+    return rc;
+}
+
+/**
+ * Guest -> Host
+ * Sends data, which either can be raw or URI data, from guest to the host. This function
+ * initiates the actual data transfer from guest to the host.
+ *
+ * @returns IPRT status code.
+ * @param   pCtx                DnD context to use.
+ * @param   pszFormat           In which format the data will be sent.
+ * @param   pvData              Data block to send.
+ *                              For URI data this must contain the absolute local URI paths, separated by DND_PATH_SEPARATOR_STR.
+ * @param   cbData              Size (in bytes) of data block to send.
+ */
+VBGLR3DECL(int) VbglR3DnDGHSendData(PVBGLR3GUESTDNDCMDCTX pCtx, const char *pszFormat, void *pvData, uint32_t cbData)
+{
+    AssertPtrReturn(pCtx,      VERR_INVALID_POINTER);
+    AssertPtrReturn(pszFormat, VERR_INVALID_POINTER);
+    AssertPtrReturn(pvData,    VERR_INVALID_POINTER);
+    AssertReturn(cbData,       VERR_INVALID_PARAMETER);
+
+    LogFlowFunc(("pszFormat=%s, pvData=%p, cbData=%RU32\n", pszFormat, pvData, cbData));
+
+    LogRel2(("DnD: Sending %RU32 bytes meta data in format '%s'\n", cbData, pszFormat));
+
+    int rc;
+    if (DnDMIMEHasFileURLs(pszFormat, strlen(pszFormat)))
+    {
+        DNDTRANSFERLIST lstTransfer;
+        RT_ZERO(lstTransfer);
+
+        rc = DnDTransferListInit(&lstTransfer);
+        if (RT_SUCCESS(rc))
+        {
+            /** @todo Add symlink support (DNDTRANSFERLIST_FLAGS_RESOLVE_SYMLINKS) here. */
+            /** @todo Add lazy loading (DNDTRANSFERLIST_FLAGS_LAZY) here. */
+            const DNDTRANSFERLISTFLAGS fFlags = DNDTRANSFERLIST_FLAGS_RECURSIVE;
+
+            rc = DnDTransferListAppendPathsFromBuffer(&lstTransfer, DNDTRANSFERLISTFMT_URI, (const char *)pvData, cbData,
+                                                      DND_PATH_SEPARATOR_STR, fFlags);
+            if (RT_SUCCESS(rc))
+                rc = vbglR3DnDGHSendTransferData(pCtx, &lstTransfer);
+            DnDTransferListDestroy(&lstTransfer);
+        }
+    }
+    else
+        rc = vbglR3DnDGHSendRawData(pCtx, pvData, cbData);
+
+    if (RT_FAILURE(rc))
+    {
+        LogRel(("DnD: Sending data failed with rc=%Rrc\n", rc));
+
+        if (rc != VERR_CANCELLED)
+        {
+            int rc2 = VbglR3DnDSendError(pCtx, rc);
+            if (RT_FAILURE(rc2))
+                LogFlowFunc(("Unable to send error (%Rrc) to host, rc=%Rrc\n", rc, rc2));
+        }
+    }
+
+    return rc;
+}
+#endif /* VBOX_WITH_DRAG_AND_DROP_GH */
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibDrmClient.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibDrmClient.cpp
new file mode 100644
index 00000000..66a8bca7
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibDrmClient.cpp
@@ -0,0 +1,199 @@
+/* $Id: VBoxGuestR3LibDrmClient.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, DRM client handling.
+ */
+
+/*
+ * Copyright (C) 2020-2023 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 "VBoxGuestR3LibInternal.h"
+
+#include <iprt/env.h>
+#include <iprt/path.h>
+#include <iprt/process.h>
+
+#if defined(RT_OS_LINUX)
+# include <VBox/HostServices/GuestPropertySvc.h>
+
+/** Defines the DRM client executable (image). */
+# define VBOX_DRMCLIENT_EXECUTABLE           "/usr/bin/VBoxDRMClient"
+# define VBOX_DRMCLIENT_LEGACY_EXECUTABLE    "/usr/bin/VBoxClient"
+/** Defines the guest property that defines if the DRM resizing client needs to be active or not. */
+# define VBOX_DRMCLIENT_GUEST_PROP_RESIZE    "/VirtualBox/GuestAdd/DRMResize"
+
+/**
+ * Check if specified guest property exist.
+ *
+ * @returns \c true if the property exists and its flags do match, \c false otherwise.
+ * @param   pszPropName     Guest property name.
+ * @param   fPropFlags      Guest property flags mask to verify if property exist.
+ *                          If \p fPropFlags is 0, flags verification is omitted.
+ */
+static bool vbglR3DrmClientCheckProp(const char *pszPropName, uint32_t fPropFlags)
+{
+    bool fExist = false;
+# if defined(VBOX_WITH_GUEST_PROPS)
+    uint32_t idClient;
+
+    int rc = VbglR3GuestPropConnect(&idClient);
+    if (RT_SUCCESS(rc))
+    {
+        char *pcszFlags = NULL;
+
+        rc = VbglR3GuestPropReadEx(idClient, pszPropName, NULL /* ppszValue */, &pcszFlags, NULL);
+        if (RT_SUCCESS(rc))
+        {
+            /* Check property flags match. */
+            if (fPropFlags)
+            {
+                uint32_t fFlags = 0;
+
+                rc = GuestPropValidateFlags(pcszFlags, &fFlags);
+                fExist = RT_SUCCESS(rc) && (fFlags == fPropFlags);
+            }
+            else
+                fExist = true;
+
+            RTStrFree(pcszFlags);
+        }
+
+        VbglR3GuestPropDisconnect(idClient);
+    }
+# endif /* VBOX_WITH_GUEST_PROPS */
+    return fExist;
+}
+#endif /* RT_OS_LINUX */
+
+/**
+ * Returns true if the DRM resizing client is needed.
+ * This is achieved by querying existence of a guest property.
+ *
+ * @returns \c true if the DRM resizing client is needed, \c false if not.
+ */
+VBGLR3DECL(bool) VbglR3DrmClientIsNeeded(void)
+{
+#if defined(RT_OS_LINUX)
+    return vbglR3DrmClientCheckProp(VBOX_DRMCLIENT_GUEST_PROP_RESIZE, 0);
+#else
+    return false;
+#endif
+}
+
+/**
+ * Returns true if the DRM IPC server socket access should be restricted.
+ *
+ * Restricted access means that only users from a certain group should
+ * be granted with read and write access permission to IPC socket. Check
+ * is done by examining \c VBGLR3DRMIPCPROPRESTRICT guest property. Property
+ * is only considered valid if is read-only for guest. I.e., the following
+ * property should be set on the host side:
+ *
+ *  VBoxManage guestproperty set <VM> /VirtualBox/GuestAdd/DRMIpcRestricted 1 --flags RDONLYGUEST
+ *
+ * @returns \c true if restricted socket access is required, \c false otherwise.
+ */
+VBGLR3DECL(bool) VbglR3DrmRestrictedIpcAccessIsNeeded(void)
+{
+#if defined(RT_OS_LINUX)
+    return vbglR3DrmClientCheckProp(VBGLR3DRMIPCPROPRESTRICT, GUEST_PROP_F_RDONLYGUEST);
+#else
+    return false;
+#endif
+}
+
+/**
+ * Returns true if the DRM resizing client already is running.
+ * This is achieved by querying existence of a guest property.
+ *
+ * @returns \c true if the DRM resizing client is running, \c false if not.
+ */
+VBGLR3DECL(bool) VbglR3DrmClientIsRunning(void)
+{
+    return VbglR3DrmClientIsNeeded();
+}
+
+#if defined(RT_OS_LINUX)
+static int VbglR3DrmStart(const char *pszCmd, const char **apszArgs)
+{
+    return RTProcCreate(pszCmd, apszArgs, RTENV_DEFAULT,
+                        RTPROC_FLAGS_DETACHED | RTPROC_FLAGS_SEARCH_PATH, NULL);
+}
+#endif
+
+/**
+ * Starts (executes) the DRM resizing client process ("VBoxDRMClient").
+ *
+ * @returns VBox status code.
+ */
+VBGLR3DECL(int) VbglR3DrmClientStart(void)
+{
+#if defined(RT_OS_LINUX)
+    const char *apszArgs[2] = { VBOX_DRMCLIENT_EXECUTABLE, NULL }; /** @todo r=andy Pass path + process name as argv0? */
+    return VbglR3DrmStart(VBOX_DRMCLIENT_EXECUTABLE, apszArgs);
+#else
+    return VERR_NOT_SUPPORTED;
+#endif
+}
+
+/**
+ * Starts (executes) the legacy DRM resizing client process ("VBoxClient --vmsvga").
+ *
+ * @returns VBox status code.
+ */
+VBGLR3DECL(int) VbglR3DrmLegacyClientStart(void)
+{
+#if defined(RT_OS_LINUX)
+    const char *apszArgs[3] = { VBOX_DRMCLIENT_LEGACY_EXECUTABLE, "--vmsvga", NULL };
+    return VbglR3DrmStart(VBOX_DRMCLIENT_LEGACY_EXECUTABLE, apszArgs);
+#else
+    return VERR_NOT_SUPPORTED;
+#endif
+}
+
+/**
+ * Starts (executes) the legacy X11 resizing agent process ("VBoxClient --display").
+ *
+ * @returns VBox status code.
+ */
+VBGLR3DECL(int) VbglR3DrmLegacyX11AgentStart(void)
+{
+#if defined(RT_OS_LINUX)
+    const char *apszArgs[3] = { VBOX_DRMCLIENT_LEGACY_EXECUTABLE, "--display", NULL };
+    return VbglR3DrmStart(VBOX_DRMCLIENT_LEGACY_EXECUTABLE, apszArgs);
+#else
+    return VERR_NOT_SUPPORTED;
+#endif
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibEvent.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibEvent.cpp
new file mode 100644
index 00000000..f459f607
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibEvent.cpp
@@ -0,0 +1,103 @@
+/* $Id: VBoxGuestR3LibEvent.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, Events.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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 <VBox/log.h>
+#include <iprt/assert.h>
+#include "VBoxGuestR3LibInternal.h"
+
+
+/**
+ * Wait for the host to signal one or more events and return which.
+ *
+ * The events will only be delivered by the host if they have been enabled
+ * previously using @a VbglR3CtlFilterMask.  If one or several of the events
+ * have already been signalled but not yet waited for, this function will return
+ * immediately and return those events.
+ *
+ * @returns IPRT status code.
+ *
+ * @param   fMask       The events we want to wait for, or-ed together.
+ * @param   cMillies    How long to wait before giving up and returning
+ *                      (VERR_TIMEOUT). Use RT_INDEFINITE_WAIT to wait until we
+ *                      are interrupted or one of the events is signalled.
+ * @param   pfEvents    Where to store the events signalled. Optional.
+ */
+VBGLR3DECL(int) VbglR3WaitEvent(uint32_t fMask, uint32_t cMillies, uint32_t *pfEvents)
+{
+    LogFlow(("VbglR3WaitEvent: fMask=%#x, cMillies=%u, pfEvents=%p\n", fMask, cMillies, pfEvents));
+    AssertReturn((fMask & ~VMMDEV_EVENT_VALID_EVENT_MASK) == 0, VERR_INVALID_PARAMETER);
+    AssertPtrNullReturn(pfEvents, VERR_INVALID_POINTER);
+
+    VBGLIOCWAITFOREVENTS WaitEvents;
+    VBGLREQHDR_INIT(&WaitEvents.Hdr, WAIT_FOR_EVENTS);
+    WaitEvents.u.In.fEvents     = fMask;
+    WaitEvents.u.In.cMsTimeOut  = cMillies;
+    int rc = vbglR3DoIOCtl(VBGL_IOCTL_WAIT_FOR_EVENTS, &WaitEvents.Hdr, sizeof(WaitEvents));
+    if (pfEvents)
+    {
+        if (RT_SUCCESS(rc))
+            *pfEvents = WaitEvents.u.Out.fEvents;
+        else
+            *pfEvents = 0;
+    }
+
+    LogFlow(("VbglR3WaitEvent: rc=%Rrc fEvents=%#x\n", rc, WaitEvents.u.Out.fEvents));
+    return rc;
+}
+
+
+/**
+ * Causes any pending VbglR3WaitEvent calls (VBGL_IOCTL_WAIT_FOR_EVENTS) to
+ * return with a VERR_INTERRUPTED status.
+ *
+ * Can be used in combination with a termination flag variable for interrupting
+ * event loops.  After calling this, VBGL_IOCTL_WAIT_FOR_EVENTS should no longer
+ * be called in the same session.  At the time of writing this is not enforced;
+ * at the time of reading it may be.
+ *
+ * @returns IPRT status code.
+ */
+VBGLR3DECL(int) VbglR3InterruptEventWaits(void)
+{
+    VBGLREQHDR Req;
+    VBGLREQHDR_INIT(&Req, INTERRUPT_ALL_WAIT_FOR_EVENTS);
+    return vbglR3DoIOCtl(VBGL_IOCTL_INTERRUPT_ALL_WAIT_FOR_EVENTS, &Req, sizeof(Req));
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibGR.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibGR.cpp
new file mode 100644
index 00000000..e80f1f55
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibGR.cpp
@@ -0,0 +1,90 @@
+/* $Id: VBoxGuestR3LibGR.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, GR.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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 <iprt/mem.h>
+#include <iprt/assert.h>
+#include <iprt/string.h>
+#include <iprt/errcore.h>
+#include "VBoxGuestR3LibInternal.h"
+
+
+int vbglR3GRAlloc(VMMDevRequestHeader **ppReq, size_t cb, VMMDevRequestType enmReqType)
+{
+    VMMDevRequestHeader *pReq;
+
+    AssertPtrReturn(ppReq, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(cb >= sizeof(VMMDevRequestHeader) && cb < _1G, ("%#zx vs %#zx\n", cb, sizeof(VMMDevRequestHeader)),
+                    VERR_INVALID_PARAMETER);
+
+    pReq = (VMMDevRequestHeader *)RTMemTmpAlloc(cb);
+    if (RT_LIKELY(pReq))
+    {
+        pReq->size        = (uint32_t)cb;
+        pReq->version     = VMMDEV_REQUEST_HEADER_VERSION;
+        pReq->requestType = enmReqType;
+        pReq->rc          = VERR_GENERAL_FAILURE;
+        pReq->reserved1   = 0;
+        pReq->fRequestor  = 0;
+
+        *ppReq = pReq;
+
+        return VINF_SUCCESS;
+    }
+    return VERR_NO_MEMORY;
+}
+
+
+int vbglR3GRPerform(VMMDevRequestHeader *pReq)
+{
+    PVBGLREQHDR    pReqHdr = (PVBGLREQHDR)pReq;
+    uint32_t const cbReq   = pReqHdr->cbIn;
+    Assert(pReqHdr->cbOut == 0 || pReqHdr->cbOut == cbReq);
+    pReqHdr->cbOut = cbReq;
+    if (pReq->size < _1K)
+        return vbglR3DoIOCtl(VBGL_IOCTL_VMMDEV_REQUEST(cbReq), pReqHdr, cbReq);
+    return vbglR3DoIOCtl(VBGL_IOCTL_VMMDEV_REQUEST_BIG, pReqHdr, cbReq);
+}
+
+
+void vbglR3GRFree(VMMDevRequestHeader *pReq)
+{
+    RTMemTmpFree(pReq);
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibGuestCtrl.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibGuestCtrl.cpp
new file mode 100644
index 00000000..fc29936c
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibGuestCtrl.cpp
@@ -0,0 +1,2214 @@
+/* $Id: VBoxGuestR3LibGuestCtrl.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, guest control.
+ */
+
+/*
+ * Copyright (C) 2010-2023 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 <iprt/string.h>
+#include <iprt/mem.h>
+#include <iprt/assert.h>
+#include <iprt/cpp/autores.h>
+#include <iprt/stdarg.h>
+#include <VBox/err.h>
+#include <VBox/log.h>
+#include <VBox/GuestHost/GuestControl.h>
+#include <VBox/HostServices/GuestControlSvc.h>
+
+#ifndef RT_OS_WINDOWS
+# include <signal.h>
+# ifdef RT_OS_DARWIN
+#  include <pthread.h>
+#  define sigprocmask pthread_sigmask /* On xnu sigprocmask works on the process, not the calling thread as elsewhere. */
+# endif
+#endif
+
+#include "VBoxGuestR3LibInternal.h"
+
+using namespace guestControl;
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/** Set if GUEST_MSG_PEEK_WAIT and friends are supported. */
+static int g_fVbglR3GuestCtrlHavePeekGetCancel = -1;
+
+
+/**
+ * Connects to the guest control service.
+ *
+ * @returns VBox status code
+ * @param   pidClient     Where to put The client ID on success. The client ID
+ *                        must be passed to all the other calls to the service.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlConnect(uint32_t *pidClient)
+{
+    return VbglR3HGCMConnect("VBoxGuestControlSvc", pidClient);
+}
+
+
+/**
+ * Disconnect from the guest control service.
+ *
+ * @returns VBox status code.
+ * @param   idClient        The client ID returned by VbglR3GuestCtrlConnect().
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlDisconnect(uint32_t idClient)
+{
+    return VbglR3HGCMDisconnect(idClient);
+}
+
+
+/**
+ * Waits until a new host message arrives.
+ * This will block until a message becomes available.
+ *
+ * @returns VBox status code.
+ * @param   idClient        The client ID returned by VbglR3GuestCtrlConnect().
+ * @param   pidMsg          Where to store the message id.
+ * @param   pcParameters    Where to store the number  of parameters which will
+ *                          be received in a second call to the host.
+ */
+static int vbglR3GuestCtrlMsgWaitFor(uint32_t idClient, uint32_t *pidMsg, uint32_t *pcParameters)
+{
+    AssertPtrReturn(pidMsg, VERR_INVALID_POINTER);
+    AssertPtrReturn(pcParameters, VERR_INVALID_POINTER);
+
+    HGCMMsgWaitFor Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, idClient,
+                       GUEST_MSG_WAIT,      /* Tell the host we want our next message. */
+                       2);                  /* Just peek for the next message! */
+    VbglHGCMParmUInt32Set(&Msg.msg, 0);
+    VbglHGCMParmUInt32Set(&Msg.num_parms, 0);
+
+    /*
+     * We should always get a VERR_TOO_MUCH_DATA response here, see
+     * guestControl::HostMessage::Peek() and its caller ClientState::SendReply().
+     * We accept success too here, in case someone decide to make the protocol
+     * slightly more sane.
+     *
+     * Note! A really sane protocol design would have a separate call for getting
+     *       info about a pending message (returning VINF_SUCCESS), and a separate
+     *       one for retriving the actual message parameters.  Not this weird
+     *       stuff, to put it rather bluntly.
+     *
+     * Note! As a result of this weird design, we are not able to correctly
+     *       retrieve message if we're interrupted by a signal, like SIGCHLD.
+     *       Because IPRT wants to use waitpid(), we're forced to have a handler
+     *       installed for SIGCHLD, so when working with child processes there
+     *       will be signals in the air and we will get VERR_INTERRUPTED returns.
+     *       The way HGCM handles interrupted calls is to silently (?) drop them
+     *       as they complete (see VMMDev), so the server knows little about it
+     *       and just goes on to the next message inline.
+     *
+     *       So, as a "temporary" mesasure, we block SIGCHLD here while waiting,
+     *       because it will otherwise be impossible do simple stuff like 'mkdir'
+     *       on a mac os x guest, and probably most other unix guests.
+     */
+#ifdef RT_OS_WINDOWS
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+#else
+    sigset_t SigSet;
+    sigemptyset(&SigSet);
+    sigaddset(&SigSet, SIGCHLD);
+    sigprocmask(SIG_BLOCK, &SigSet, NULL);
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    sigprocmask(SIG_UNBLOCK, &SigSet, NULL);
+#endif
+    if (   rc == VERR_TOO_MUCH_DATA
+        || RT_SUCCESS(rc))
+    {
+        int rc2 = VbglHGCMParmUInt32Get(&Msg.msg, pidMsg);
+        if (RT_SUCCESS(rc2))
+        {
+            rc2 = VbglHGCMParmUInt32Get(&Msg.num_parms, pcParameters);
+            if (RT_SUCCESS(rc2))
+            {
+                /* Ok, so now we know what message type and how much parameters there are. */
+                return rc;
+            }
+        }
+        rc = rc2;
+    }
+    *pidMsg       = UINT32_MAX - 1;
+    *pcParameters = UINT32_MAX - 2;
+    return rc;
+}
+
+
+/**
+ * Determins the value of g_fVbglR3GuestCtrlHavePeekGetCancel.
+ *
+ * @returns true if supported, false if not.
+ * @param   idClient         The client ID to use for the testing.
+ */
+DECL_NO_INLINE(static, bool) vbglR3GuestCtrlDetectPeekGetCancelSupport(uint32_t idClient)
+{
+    /*
+     * Seems we get VINF_SUCCESS back from the host if we try unsupported
+     * guest control messages, so we need to supply some random message
+     * parameters and check that they change.
+     */
+    uint32_t const idDummyMsg      = UINT32_C(0x8350bdca);
+    uint32_t const cDummyParmeters = UINT32_C(0x7439604f);
+    uint32_t const cbDummyMask     = UINT32_C(0xc0ffe000);
+    Assert(cDummyParmeters > VMMDEV_MAX_HGCM_PARMS);
+
+    int rc;
+    struct
+    {
+        VBGLIOCHGCMCALL         Hdr;
+        HGCMFunctionParameter   idMsg;
+        HGCMFunctionParameter   cParams;
+        HGCMFunctionParameter   acbParams[14];
+    } PeekCall;
+    Assert(RT_ELEMENTS(PeekCall.acbParams) + 2 < VMMDEV_MAX_HGCM_PARMS);
+
+    do
+    {
+        memset(&PeekCall, 0xf6, sizeof(PeekCall));
+        VBGL_HGCM_HDR_INIT(&PeekCall.Hdr, idClient, GUEST_MSG_PEEK_NOWAIT, 16);
+        VbglHGCMParmUInt32Set(&PeekCall.idMsg, idDummyMsg);
+        VbglHGCMParmUInt32Set(&PeekCall.cParams, cDummyParmeters);
+        for (uint32_t i = 0; i < RT_ELEMENTS(PeekCall.acbParams); i++)
+            VbglHGCMParmUInt32Set(&PeekCall.acbParams[i], i | cbDummyMask);
+
+        rc = VbglR3HGCMCall(&PeekCall.Hdr, sizeof(PeekCall));
+    } while (rc == VERR_INTERRUPTED);
+
+    LogRel2(("vbglR3GuestCtrlDetectPeekGetCancelSupport: rc=%Rrc %#x %#x %#x %#x %#x %#x %#x %#x %#x %#x %#x %#x %#x %#x %#x %#x\n",
+             rc, PeekCall.idMsg.u.value32,     PeekCall.cParams.u.value32,
+             PeekCall.acbParams[ 0].u.value32, PeekCall.acbParams[ 1].u.value32,
+             PeekCall.acbParams[ 2].u.value32, PeekCall.acbParams[ 3].u.value32,
+             PeekCall.acbParams[ 4].u.value32, PeekCall.acbParams[ 5].u.value32,
+             PeekCall.acbParams[ 6].u.value32, PeekCall.acbParams[ 7].u.value32,
+             PeekCall.acbParams[ 8].u.value32, PeekCall.acbParams[ 9].u.value32,
+             PeekCall.acbParams[10].u.value32, PeekCall.acbParams[11].u.value32,
+             PeekCall.acbParams[12].u.value32, PeekCall.acbParams[13].u.value32));
+
+    /*
+     * VERR_TRY_AGAIN is likely and easy.
+     */
+    if (   rc == VERR_TRY_AGAIN
+        && PeekCall.idMsg.u.value32 == 0
+        && PeekCall.cParams.u.value32 == 0
+        && PeekCall.acbParams[0].u.value32 == 0
+        && PeekCall.acbParams[1].u.value32 == 0
+        && PeekCall.acbParams[2].u.value32 == 0
+        && PeekCall.acbParams[3].u.value32 == 0)
+    {
+        g_fVbglR3GuestCtrlHavePeekGetCancel = 1;
+        LogRel(("vbglR3GuestCtrlDetectPeekGetCancelSupport: Supported (#1)\n"));
+        return true;
+    }
+
+    /*
+     * VINF_SUCCESS is annoying but with 16 parameters we've got plenty to check.
+     */
+    if (   rc == VINF_SUCCESS
+        && PeekCall.idMsg.u.value32 != idDummyMsg
+        && PeekCall.idMsg.u.value32 != 0
+        && PeekCall.cParams.u.value32 <= VMMDEV_MAX_HGCM_PARMS)
+    {
+        for (uint32_t i = 0; i < RT_ELEMENTS(PeekCall.acbParams); i++)
+            if (PeekCall.acbParams[i].u.value32 != (i | cbDummyMask))
+            {
+                g_fVbglR3GuestCtrlHavePeekGetCancel = 0;
+                LogRel(("vbglR3GuestCtrlDetectPeekGetCancelSupport: Not supported (#1)\n"));
+                return false;
+            }
+        g_fVbglR3GuestCtrlHavePeekGetCancel = 1;
+        LogRel(("vbglR3GuestCtrlDetectPeekGetCancelSupport: Supported (#2)\n"));
+        return true;
+    }
+
+    /*
+     * Okay, pretty sure it's not supported then.
+     */
+    LogRel(("vbglR3GuestCtrlDetectPeekGetCancelSupport: Not supported (#3)\n"));
+    g_fVbglR3GuestCtrlHavePeekGetCancel = 0;
+    return false;
+}
+
+
+/**
+ * Reads g_fVbglR3GuestCtrlHavePeekGetCancel and resolved -1.
+ *
+ * @returns true if supported, false if not.
+ * @param   idClient         The client ID to use for the testing.
+ */
+DECLINLINE(bool) vbglR3GuestCtrlSupportsPeekGetCancel(uint32_t idClient)
+{
+    int fState = g_fVbglR3GuestCtrlHavePeekGetCancel;
+    if (RT_LIKELY(fState != -1))
+        return fState != 0;
+    return vbglR3GuestCtrlDetectPeekGetCancelSupport(idClient);
+}
+
+
+/**
+ * Figures which getter function to use to retrieve the message.
+ */
+DECLINLINE(uint32_t) vbglR3GuestCtrlGetMsgFunctionNo(uint32_t idClient)
+{
+    return vbglR3GuestCtrlSupportsPeekGetCancel(idClient) ? GUEST_MSG_GET : GUEST_MSG_WAIT;
+}
+
+
+/**
+ * Checks if the host supports the optimizes message and session functions.
+ *
+ * @returns true / false.
+ * @param   idClient    The client ID returned by VbglR3GuestCtrlConnect().
+ *                      We may need to use this for checking.
+ * @since   6.0
+ */
+VBGLR3DECL(bool) VbglR3GuestCtrlSupportsOptimizations(uint32_t idClient)
+{
+    return vbglR3GuestCtrlSupportsPeekGetCancel(idClient);
+}
+
+
+/**
+ * Make us the guest control master client.
+ *
+ * @returns VBox status code.
+ * @param   idClient    The client ID returned by VbglR3GuestCtrlConnect().
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlMakeMeMaster(uint32_t idClient)
+{
+    int rc;
+    do
+    {
+        VBGLIOCHGCMCALL Hdr;
+        VBGL_HGCM_HDR_INIT(&Hdr, idClient, GUEST_MSG_MAKE_ME_MASTER, 0);
+        rc = VbglR3HGCMCall(&Hdr, sizeof(Hdr));
+    } while (rc == VERR_INTERRUPTED);
+    return rc;
+}
+
+
+/**
+ * Reports features to the host and retrieve host feature set.
+ *
+ * @returns VBox status code.
+ * @param   idClient        The client ID returned by VbglR3GuestCtrlConnect().
+ * @param   fGuestFeatures  Features to report, VBOX_GUESTCTRL_GF_XXX.
+ * @param   pfHostFeatures  Where to store the features VBOX_GUESTCTRL_HF_XXX.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlReportFeatures(uint32_t idClient, uint64_t fGuestFeatures, uint64_t *pfHostFeatures)
+{
+    int rc;
+    do
+    {
+        struct
+        {
+            VBGLIOCHGCMCALL         Hdr;
+            HGCMFunctionParameter   f64Features0;
+            HGCMFunctionParameter   f64Features1;
+        } Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.Hdr, idClient, GUEST_MSG_REPORT_FEATURES, 2);
+        VbglHGCMParmUInt64Set(&Msg.f64Features0, fGuestFeatures);
+        VbglHGCMParmUInt64Set(&Msg.f64Features1, VBOX_GUESTCTRL_GF_1_MUST_BE_ONE);
+
+        rc = VbglR3HGCMCall(&Msg.Hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            Assert(Msg.f64Features0.type == VMMDevHGCMParmType_64bit);
+            Assert(Msg.f64Features1.type == VMMDevHGCMParmType_64bit);
+            if (Msg.f64Features1.u.value64 & VBOX_GUESTCTRL_GF_1_MUST_BE_ONE)
+                rc = VERR_NOT_SUPPORTED;
+            else if (pfHostFeatures)
+                *pfHostFeatures = Msg.f64Features0.u.value64;
+            break;
+        }
+    } while (rc == VERR_INTERRUPTED);
+    return rc;
+
+}
+
+
+/**
+ * Query the host features.
+ *
+ * @returns VBox status code.
+ * @param   idClient        The client ID returned by VbglR3GuestCtrlConnect().
+ * @param   pfHostFeatures  Where to store the host feature, VBOX_GUESTCTRL_HF_XXX.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlQueryFeatures(uint32_t idClient, uint64_t *pfHostFeatures)
+{
+    int rc;
+    do
+    {
+        struct
+        {
+            VBGLIOCHGCMCALL         Hdr;
+            HGCMFunctionParameter   f64Features0;
+            HGCMFunctionParameter   f64Features1;
+        } Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.Hdr, idClient, GUEST_MSG_QUERY_FEATURES, 2);
+        VbglHGCMParmUInt64Set(&Msg.f64Features0, 0);
+        VbglHGCMParmUInt64Set(&Msg.f64Features1, RT_BIT_64(63));
+
+        rc = VbglR3HGCMCall(&Msg.Hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            Assert(Msg.f64Features0.type == VMMDevHGCMParmType_64bit);
+            Assert(Msg.f64Features1.type == VMMDevHGCMParmType_64bit);
+            if (Msg.f64Features1.u.value64 & RT_BIT_64(63))
+                rc = VERR_NOT_SUPPORTED;
+            else if (pfHostFeatures)
+                *pfHostFeatures = Msg.f64Features0.u.value64;
+            break;
+        }
+    } while (rc == VERR_INTERRUPTED);
+    return rc;
+
+}
+
+
+/**
+ * Peeks at the next host message, waiting for one to turn up.
+ *
+ * @returns VBox status code.
+ * @retval  VERR_INTERRUPTED if interrupted.  Does the necessary cleanup, so
+ *          caller just have to repeat this call.
+ * @retval  VERR_VM_RESTORED if the VM has been restored (idRestoreCheck).
+ *
+ * @param   idClient        The client ID returned by VbglR3GuestCtrlConnect().
+ * @param   pidMsg          Where to store the message id.
+ * @param   pcParameters    Where to store the number  of parameters which will
+ *                          be received in a second call to the host.
+ * @param   pidRestoreCheck Pointer to the VbglR3GetSessionId() variable to use
+ *                          for the VM restore check.  Optional.
+ *
+ * @note    Restore check is only performed optimally with a 6.0 host.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlMsgPeekWait(uint32_t idClient, uint32_t *pidMsg, uint32_t *pcParameters, uint64_t *pidRestoreCheck)
+{
+    AssertPtrReturn(pidMsg, VERR_INVALID_POINTER);
+    AssertPtrReturn(pcParameters, VERR_INVALID_POINTER);
+
+    int rc;
+    if (vbglR3GuestCtrlSupportsPeekGetCancel(idClient))
+    {
+        struct
+        {
+            VBGLIOCHGCMCALL Hdr;
+            HGCMFunctionParameter idMsg;       /* Doubles as restore check on input. */
+            HGCMFunctionParameter cParameters;
+        } Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.Hdr, idClient, GUEST_MSG_PEEK_WAIT, 2);
+        VbglHGCMParmUInt64Set(&Msg.idMsg, pidRestoreCheck ? *pidRestoreCheck : 0);
+        VbglHGCMParmUInt32Set(&Msg.cParameters, 0);
+        rc = VbglR3HGCMCall(&Msg.Hdr, sizeof(Msg));
+        LogRel2(("VbglR3GuestCtrlMsgPeekWait -> %Rrc\n", rc));
+        if (RT_SUCCESS(rc))
+        {
+            AssertMsgReturn(   Msg.idMsg.type       == VMMDevHGCMParmType_64bit
+                            && Msg.cParameters.type == VMMDevHGCMParmType_32bit,
+                            ("msg.type=%d num_parms.type=%d\n", Msg.idMsg.type, Msg.cParameters.type),
+                            VERR_INTERNAL_ERROR_3);
+
+            *pidMsg       = (uint32_t)Msg.idMsg.u.value64;
+            *pcParameters = Msg.cParameters.u.value32;
+            return rc;
+        }
+
+        /*
+         * If interrupted we must cancel the call so it doesn't prevent us from making another one.
+         */
+        if (rc == VERR_INTERRUPTED)
+        {
+            VBGL_HGCM_HDR_INIT(&Msg.Hdr, idClient, GUEST_MSG_CANCEL, 0);
+            int rc2 = VbglR3HGCMCall(&Msg.Hdr, sizeof(Msg.Hdr));
+            AssertRC(rc2);
+        }
+
+        /*
+         * If restored, update pidRestoreCheck.
+         */
+        if (rc == VERR_VM_RESTORED && pidRestoreCheck)
+            *pidRestoreCheck = Msg.idMsg.u.value64;
+
+        *pidMsg       = UINT32_MAX - 1;
+        *pcParameters = UINT32_MAX - 2;
+        return rc;
+    }
+
+    /*
+     * Fallback if host < v6.0.
+     *
+     * Note! The restore check isn't perfect. Would require checking afterwards
+     *       and stash the result if we were restored during the call.  Too much
+     *       hazzle for a downgrade scenario.
+     */
+    if (pidRestoreCheck)
+    {
+        uint64_t idRestoreCur = *pidRestoreCheck;
+        rc = VbglR3GetSessionId(&idRestoreCur);
+        if (RT_SUCCESS(rc) && idRestoreCur != *pidRestoreCheck)
+        {
+            *pidRestoreCheck = idRestoreCur;
+            return VERR_VM_RESTORED;
+        }
+    }
+
+    rc = vbglR3GuestCtrlMsgWaitFor(idClient, pidMsg, pcParameters);
+    if (rc == VERR_TOO_MUCH_DATA)
+        rc = VINF_SUCCESS;
+    return rc;
+}
+
+
+/**
+ * Asks the host guest control service to set a message filter to this
+ * client so that it only will receive certain messages in the future.
+ * The filter(s) are a bitmask for the context IDs, served from the host.
+ *
+ * @return  IPRT status code.
+ * @param   idClient        The client ID returned by VbglR3GuestCtrlConnect().
+ * @param   uValue          The value to filter messages for.
+ * @param   uMaskAdd        Filter mask to add.
+ * @param   uMaskRemove     Filter mask to remove.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlMsgFilterSet(uint32_t idClient, uint32_t uValue, uint32_t uMaskAdd, uint32_t uMaskRemove)
+{
+    HGCMMsgFilterSet Msg;
+
+    /* Tell the host we want to set a filter. */
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, idClient, GUEST_MSG_FILTER_SET, 4);
+    VbglHGCMParmUInt32Set(&Msg.value, uValue);
+    VbglHGCMParmUInt32Set(&Msg.mask_add, uMaskAdd);
+    VbglHGCMParmUInt32Set(&Msg.mask_remove, uMaskRemove);
+    VbglHGCMParmUInt32Set(&Msg.flags, 0 /* Flags, unused */);
+
+    return VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+}
+
+
+/**
+ * Replies to a message from the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Guest control command context to use.
+ * @param   rc                  Guest rc to reply.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlMsgReply(PVBGLR3GUESTCTRLCMDCTX pCtx,
+                                        int rc)
+{
+    return VbglR3GuestCtrlMsgReplyEx(pCtx, rc, 0 /* uType */,
+                                     NULL /* pvPayload */, 0 /* cbPayload */);
+}
+
+
+/**
+ * Replies to a message from the host, extended version.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Guest control command context to use.
+ * @param   rc                  Guest rc to reply.
+ * @param   uType               Reply type; not used yet and must be 0.
+ * @param   pvPayload           Pointer to data payload to reply. Optional.
+ * @param   cbPayload           Size of data payload (in bytes) to reply.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlMsgReplyEx(PVBGLR3GUESTCTRLCMDCTX pCtx,
+                                          int rc, uint32_t uType,
+                                          void *pvPayload, uint32_t cbPayload)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+    /* Everything else is optional. */
+
+    HGCMMsgReply Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_MSG_REPLY, 4);
+    VbglHGCMParmUInt32Set(&Msg.context, pCtx->uContextID);
+    VbglHGCMParmUInt32Set(&Msg.type, uType);
+    VbglHGCMParmUInt32Set(&Msg.rc, (uint32_t)rc); /* int vs. uint32_t */
+    VbglHGCMParmPtrSet(&Msg.payload, pvPayload, cbPayload);
+
+    return VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+}
+
+/**
+ * Tell the host to skip the current message replying VERR_NOT_SUPPORTED
+ *
+ * @return  IPRT status code.
+ * @param   idClient        The client ID returned by VbglR3GuestCtrlConnect().
+ * @param   rcSkip          The status code to pass back to Main when skipping.
+ * @param   idMsg           The message ID to skip, pass UINT32_MAX to pass any.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlMsgSkip(uint32_t idClient, int rcSkip, uint32_t idMsg)
+{
+    if (vbglR3GuestCtrlSupportsPeekGetCancel(idClient))
+    {
+        struct
+        {
+            VBGLIOCHGCMCALL         Hdr;
+            HGCMFunctionParameter   rcSkip;
+            HGCMFunctionParameter   idMsg;
+        } Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.Hdr, idClient, GUEST_MSG_SKIP, 2);
+        VbglHGCMParmUInt32Set(&Msg.rcSkip, (uint32_t)rcSkip);
+        VbglHGCMParmUInt32Set(&Msg.idMsg, idMsg);
+        return VbglR3HGCMCall(&Msg.Hdr, sizeof(Msg));
+    }
+
+    /* This is generally better than nothing... */
+    return VbglR3GuestCtrlMsgSkipOld(idClient);
+}
+
+
+/**
+ * Tells the host service to skip the current message returned by
+ * VbglR3GuestCtrlMsgWaitFor().
+ *
+ * @return  IPRT status code.
+ * @param   idClient        The client ID returned by VbglR3GuestCtrlConnect().
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlMsgSkipOld(uint32_t idClient)
+{
+    HGCMMsgSkip Msg;
+
+    /* Tell the host we want to skip the current assigned message. */
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, idClient, GUEST_MSG_SKIP_OLD, 1);
+    VbglHGCMParmUInt32Set(&Msg.flags, 0 /* Flags, unused */);
+    return VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+}
+
+
+/**
+ * Asks the host to cancel (release) all pending waits which were deferred.
+ *
+ * @returns VBox status code.
+ * @param   idClient        The client ID returned by VbglR3GuestCtrlConnect().
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlCancelPendingWaits(uint32_t idClient)
+{
+    HGCMMsgCancelPendingWaits Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, idClient, GUEST_MSG_CANCEL, 0);
+    return VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+}
+
+
+/**
+ * Prepares a session.
+ * @since   6.0
+ * @sa      GUEST_SESSION_PREPARE
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlSessionPrepare(uint32_t idClient, uint32_t idSession, void const *pvKey, uint32_t cbKey)
+{
+    int rc;
+    do
+    {
+        struct
+        {
+            VBGLIOCHGCMCALL         Hdr;
+            HGCMFunctionParameter   idSession;
+            HGCMFunctionParameter   pKey;
+        } Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.Hdr, idClient, GUEST_MSG_SESSION_PREPARE, 2);
+        VbglHGCMParmUInt32Set(&Msg.idSession, idSession);
+        VbglHGCMParmPtrSet(&Msg.pKey, (void *)pvKey, cbKey);
+        rc = VbglR3HGCMCall(&Msg.Hdr, sizeof(Msg));
+    } while (rc == VERR_INTERRUPTED);
+    return rc;
+}
+
+
+/**
+ * Accepts a session.
+ * @since   6.0
+ * @sa      GUEST_SESSION_ACCEPT
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlSessionAccept(uint32_t idClient, uint32_t idSession, void const *pvKey, uint32_t cbKey)
+{
+    int rc;
+    do
+    {
+        struct
+        {
+            VBGLIOCHGCMCALL         Hdr;
+            HGCMFunctionParameter   idSession;
+            HGCMFunctionParameter   pKey;
+        } Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.Hdr, idClient, GUEST_MSG_SESSION_ACCEPT, 2);
+        VbglHGCMParmUInt32Set(&Msg.idSession, idSession);
+        VbglHGCMParmPtrSet(&Msg.pKey, (void *)pvKey, cbKey);
+        rc = VbglR3HGCMCall(&Msg.Hdr, sizeof(Msg));
+    } while (rc == VERR_INTERRUPTED);
+    return rc;
+}
+
+
+/**
+ * Cancels a prepared session.
+ * @since   6.0
+ * @sa      GUEST_SESSION_CANCEL_PREPARED
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlSessionCancelPrepared(uint32_t idClient, uint32_t idSession)
+{
+    int rc;
+    do
+    {
+        struct
+        {
+            VBGLIOCHGCMCALL         Hdr;
+            HGCMFunctionParameter   idSession;
+        } Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.Hdr, idClient, GUEST_MSG_SESSION_CANCEL_PREPARED, 1);
+        VbglHGCMParmUInt32Set(&Msg.idSession, idSession);
+        rc = VbglR3HGCMCall(&Msg.Hdr, sizeof(Msg));
+    } while (rc == VERR_INTERRUPTED);
+    return rc;
+}
+
+
+/**
+ * Invalidates the internal state because the (VM) session has been changed (i.e. restored).
+ *
+ * @returns VBox status code.
+ * @param   idClient                Client ID to use for invalidating state.
+ * @param   idNewControlSession     New control session ID. Currently unused.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlSessionHasChanged(uint32_t idClient, uint64_t idNewControlSession)
+{
+    RT_NOREF(idNewControlSession);
+
+    vbglR3GuestCtrlDetectPeekGetCancelSupport(idClient);
+
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Asks a specific guest session to close.
+ *
+ * @return  IPRT status code.
+ * @param   pCtx                    Guest control command context to use.
+ * @param   fFlags                  Some kind of flag. Figure it out yourself.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlSessionClose(PVBGLR3GUESTCTRLCMDCTX pCtx, uint32_t fFlags)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+    AssertReturn(pCtx->uNumParms == 2, VERR_INVALID_PARAMETER);
+
+    HGCMMsgSessionClose Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_MSG_SESSION_CLOSE, pCtx->uNumParms);
+    VbglHGCMParmUInt32Set(&Msg.context, pCtx->uContextID);
+    VbglHGCMParmUInt32Set(&Msg.flags, fFlags);
+
+    return VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+}
+
+
+/**
+ * Notifies a guest session.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                    Guest control command context to use.
+ * @param   uType                   Notification type of type GUEST_SESSION_NOTIFYTYPE_XXX.
+ * @param   iResult                 Result code (rc) to notify.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlSessionNotify(PVBGLR3GUESTCTRLCMDCTX pCtx, uint32_t uType, int32_t iResult)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    HGCMMsgSessionNotify Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_MSG_SESSION_NOTIFY, 3);
+    VbglHGCMParmUInt32Set(&Msg.context, pCtx->uContextID);
+    VbglHGCMParmUInt32Set(&Msg.type, uType);
+    VbglHGCMParmUInt32Set(&Msg.result, (uint32_t)iResult);
+
+    return VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+}
+
+/**
+ * Initializes a session startup info, extended version.
+ *
+ * @returns VBox status code.
+ * @param   pStartupInfo        Session startup info to initializes.
+ * @param   cbUser              Size (in bytes) to use for the user name buffer.
+ * @param   cbPassword          Size (in bytes) to use for the password buffer.
+ * @param   cbDomain            Size (in bytes) to use for the domain name buffer.
+ */
+VBGLR3DECL(int)  VbglR3GuestCtrlSessionStartupInfoInitEx(PVBGLR3GUESTCTRLSESSIONSTARTUPINFO pStartupInfo,
+                                                         size_t cbUser, size_t cbPassword, size_t cbDomain)
+{
+    AssertPtrReturn(pStartupInfo, VERR_INVALID_POINTER);
+
+    RT_BZERO(pStartupInfo, sizeof(VBGLR3GUESTCTRLSESSIONSTARTUPINFO));
+
+#define ALLOC_STR(a_Str, a_cb) \
+    if ((a_cb) > 0) \
+    { \
+        pStartupInfo->psz##a_Str = RTStrAlloc(a_cb); \
+        AssertPtrBreak(pStartupInfo->psz##a_Str); \
+        pStartupInfo->cb##a_Str  = (uint32_t)a_cb; \
+    }
+
+    do
+    {
+        ALLOC_STR(User,     cbUser);
+        ALLOC_STR(Password, cbPassword);
+        ALLOC_STR(Domain,   cbDomain);
+
+        return VINF_SUCCESS;
+
+    } while (0);
+
+#undef ALLOC_STR
+
+    VbglR3GuestCtrlSessionStartupInfoDestroy(pStartupInfo);
+    return VERR_NO_MEMORY;
+}
+
+/**
+ * Initializes a session startup info.
+ *
+ * @returns VBox status code.
+ * @param   pStartupInfo        Session startup info to initializes.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlSessionStartupInfoInit(PVBGLR3GUESTCTRLSESSIONSTARTUPINFO pStartupInfo)
+{
+    return VbglR3GuestCtrlSessionStartupInfoInitEx(pStartupInfo,
+                                                   GUEST_PROC_DEF_USER_LEN, GUEST_PROC_DEF_PASSWORD_LEN,
+                                                   GUEST_PROC_DEF_DOMAIN_LEN);
+}
+
+/**
+ * Destroys a session startup info.
+ *
+ * @param   pStartupInfo        Session startup info to destroy.
+ */
+VBGLR3DECL(void) VbglR3GuestCtrlSessionStartupInfoDestroy(PVBGLR3GUESTCTRLSESSIONSTARTUPINFO pStartupInfo)
+{
+    if (!pStartupInfo)
+        return;
+
+    RTStrFree(pStartupInfo->pszUser);
+    RTStrFree(pStartupInfo->pszPassword);
+    RTStrFree(pStartupInfo->pszDomain);
+
+    RT_BZERO(pStartupInfo, sizeof(VBGLR3GUESTCTRLSESSIONSTARTUPINFO));
+}
+
+/**
+ * Free's a session startup info.
+ *
+ * @param   pStartupInfo        Session startup info to free.
+ *                              The pointer will not be valid anymore after return.
+ */
+VBGLR3DECL(void) VbglR3GuestCtrlSessionStartupInfoFree(PVBGLR3GUESTCTRLSESSIONSTARTUPINFO pStartupInfo)
+{
+    if (!pStartupInfo)
+        return;
+
+    VbglR3GuestCtrlSessionStartupInfoDestroy(pStartupInfo);
+
+    RTMemFree(pStartupInfo);
+    pStartupInfo = NULL;
+}
+
+/**
+ * Duplicates a session startup info.
+ *
+ * @returns Duplicated session startup info on success, or NULL on error.
+ * @param   pStartupInfo        Session startup info to duplicate.
+ */
+VBGLR3DECL(PVBGLR3GUESTCTRLSESSIONSTARTUPINFO) VbglR3GuestCtrlSessionStartupInfoDup(PVBGLR3GUESTCTRLSESSIONSTARTUPINFO pStartupInfo)
+{
+    AssertPtrReturn(pStartupInfo, NULL);
+
+    PVBGLR3GUESTCTRLSESSIONSTARTUPINFO pStartupInfoDup = (PVBGLR3GUESTCTRLSESSIONSTARTUPINFO)
+                                                                RTMemDup(pStartupInfo, sizeof(VBGLR3GUESTCTRLSESSIONSTARTUPINFO));
+    if (pStartupInfoDup)
+    {
+        do
+        {
+            pStartupInfoDup->pszUser     = NULL;
+            pStartupInfoDup->pszPassword = NULL;
+            pStartupInfoDup->pszDomain   = NULL;
+
+#define DUP_STR(a_Str) \
+    if (pStartupInfo->cb##a_Str) \
+    { \
+        pStartupInfoDup->psz##a_Str = (char *)RTStrDup(pStartupInfo->psz##a_Str); \
+        AssertPtrBreak(pStartupInfoDup->psz##a_Str); \
+        pStartupInfoDup->cb##a_Str  = (uint32_t)strlen(pStartupInfoDup->psz##a_Str) + 1 /* Include terminator */; \
+    }
+            DUP_STR(User);
+            DUP_STR(Password);
+            DUP_STR(Domain);
+
+#undef DUP_STR
+
+            return pStartupInfoDup;
+
+        } while (0); /* To use break macros above. */
+
+        VbglR3GuestCtrlSessionStartupInfoFree(pStartupInfoDup);
+    }
+
+    return NULL;
+}
+
+/**
+ * Retrieves a HOST_SESSION_CREATE message.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Guest control command context to use.
+ * @param   ppStartupInfo       Where to store the allocated session startup info.
+ *                              Needs to be free'd by VbglR3GuestCtrlSessionStartupInfoFree().
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlSessionGetOpen(PVBGLR3GUESTCTRLCMDCTX pCtx, PVBGLR3GUESTCTRLSESSIONSTARTUPINFO *ppStartupInfo)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+    AssertReturn(pCtx->uNumParms == 6, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(ppStartupInfo, VERR_INVALID_POINTER);
+
+    PVBGLR3GUESTCTRLSESSIONSTARTUPINFO pStartupInfo
+        = (PVBGLR3GUESTCTRLSESSIONSTARTUPINFO)RTMemAlloc(sizeof(VBGLR3GUESTCTRLSESSIONSTARTUPINFO));
+    if (!pStartupInfo)
+        return VERR_NO_MEMORY;
+
+    int rc = VbglR3GuestCtrlSessionStartupInfoInit(pStartupInfo);
+    if (RT_FAILURE(rc))
+    {
+        VbglR3GuestCtrlSessionStartupInfoFree(pStartupInfo);
+        return rc;
+    }
+
+    do
+    {
+        HGCMMsgSessionOpen Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, vbglR3GuestCtrlGetMsgFunctionNo(pCtx->uClientID), pCtx->uNumParms);
+        VbglHGCMParmUInt32Set(&Msg.context, HOST_MSG_SESSION_CREATE);
+        VbglHGCMParmUInt32Set(&Msg.protocol, 0);
+        VbglHGCMParmPtrSet(&Msg.username, pStartupInfo->pszUser, pStartupInfo->cbUser);
+        VbglHGCMParmPtrSet(&Msg.password, pStartupInfo->pszPassword, pStartupInfo->cbPassword);
+        VbglHGCMParmPtrSet(&Msg.domain, pStartupInfo->pszDomain, pStartupInfo->cbDomain);
+        VbglHGCMParmUInt32Set(&Msg.flags, 0);
+
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            Msg.context.GetUInt32(&pCtx->uContextID);
+            Msg.protocol.GetUInt32(&pStartupInfo->uProtocol);
+            Msg.flags.GetUInt32(&pStartupInfo->fFlags);
+
+            pStartupInfo->uSessionID = VBOX_GUESTCTRL_CONTEXTID_GET_SESSION(pCtx->uContextID);
+        }
+
+    } while (rc == VERR_INTERRUPTED && g_fVbglR3GuestCtrlHavePeekGetCancel);
+
+    if (RT_SUCCESS(rc))
+    {
+        *ppStartupInfo = pStartupInfo;
+    }
+    else
+        VbglR3GuestCtrlSessionStartupInfoFree(pStartupInfo);
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+
+/**
+ * Retrieves a HOST_SESSION_CLOSE message.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlSessionGetClose(PVBGLR3GUESTCTRLCMDCTX pCtx, uint32_t *pfFlags, uint32_t *pidSession)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+    AssertReturn(pCtx->uNumParms == 2, VERR_INVALID_PARAMETER);
+
+    AssertPtrReturn(pfFlags, VERR_INVALID_POINTER);
+
+    int rc;
+    do
+    {
+        HGCMMsgSessionClose Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, vbglR3GuestCtrlGetMsgFunctionNo(pCtx->uClientID), pCtx->uNumParms);
+        VbglHGCMParmUInt32Set(&Msg.context, HOST_MSG_SESSION_CLOSE);
+        VbglHGCMParmUInt32Set(&Msg.flags, 0);
+
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            Msg.context.GetUInt32(&pCtx->uContextID);
+            Msg.flags.GetUInt32(pfFlags);
+
+            if (pidSession)
+                *pidSession = VBOX_GUESTCTRL_CONTEXTID_GET_SESSION(pCtx->uContextID);
+        }
+    } while (rc == VERR_INTERRUPTED && g_fVbglR3GuestCtrlHavePeekGetCancel);
+    return rc;
+}
+
+
+/**
+ * Retrieves a HOST_PATH_RENAME message.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlPathGetRename(PVBGLR3GUESTCTRLCMDCTX     pCtx,
+                                             char     *pszSource,       uint32_t cbSource,
+                                             char     *pszDest,         uint32_t cbDest,
+                                             uint32_t *pfFlags)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+    AssertReturn(pCtx->uNumParms == 4, VERR_INVALID_PARAMETER);
+
+    AssertPtrReturn(pszSource, VERR_INVALID_POINTER);
+    AssertReturn(cbSource, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(pszDest, VERR_INVALID_POINTER);
+    AssertReturn(cbDest, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(pfFlags, VERR_INVALID_POINTER);
+
+    int rc;
+    do
+    {
+        HGCMMsgPathRename Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, vbglR3GuestCtrlGetMsgFunctionNo(pCtx->uClientID), pCtx->uNumParms);
+        VbglHGCMParmUInt32Set(&Msg.context, HOST_MSG_PATH_RENAME);
+        VbglHGCMParmPtrSet(&Msg.source, pszSource, cbSource);
+        VbglHGCMParmPtrSet(&Msg.dest, pszDest, cbDest);
+        VbglHGCMParmUInt32Set(&Msg.flags, 0);
+
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            Msg.context.GetUInt32(&pCtx->uContextID);
+            Msg.flags.GetUInt32(pfFlags);
+        }
+
+    } while (rc == VERR_INTERRUPTED && g_fVbglR3GuestCtrlHavePeekGetCancel);
+    return rc;
+}
+
+
+/**
+ * Retrieves a HOST_PATH_USER_DOCUMENTS message.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlPathGetUserDocuments(PVBGLR3GUESTCTRLCMDCTX pCtx)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+    AssertReturn(pCtx->uNumParms == 1, VERR_INVALID_PARAMETER);
+
+    int rc;
+    do
+    {
+        HGCMMsgPathUserDocuments Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, vbglR3GuestCtrlGetMsgFunctionNo(pCtx->uClientID), pCtx->uNumParms);
+        VbglHGCMParmUInt32Set(&Msg.context, HOST_MSG_PATH_USER_DOCUMENTS);
+
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+            Msg.context.GetUInt32(&pCtx->uContextID);
+    } while (rc == VERR_INTERRUPTED && g_fVbglR3GuestCtrlHavePeekGetCancel);
+    return rc;
+}
+
+
+/**
+ * Retrieves a HOST_PATH_USER_HOME message.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlPathGetUserHome(PVBGLR3GUESTCTRLCMDCTX pCtx)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+    AssertReturn(pCtx->uNumParms == 1, VERR_INVALID_PARAMETER);
+
+    int rc;
+    do
+    {
+        HGCMMsgPathUserHome Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, vbglR3GuestCtrlGetMsgFunctionNo(pCtx->uClientID), pCtx->uNumParms);
+        VbglHGCMParmUInt32Set(&Msg.context, HOST_MSG_PATH_USER_HOME);
+
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+            Msg.context.GetUInt32(&pCtx->uContextID);
+    } while (rc == VERR_INTERRUPTED && g_fVbglR3GuestCtrlHavePeekGetCancel);
+    return rc;
+}
+
+/**
+ * Retrieves a HOST_MSG_SHUTDOWN message.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Guest control command context to use.
+ * @param   pfAction            Where to store the action flags on success.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlGetShutdown(PVBGLR3GUESTCTRLCMDCTX pCtx, uint32_t *pfAction)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+    AssertReturn(pCtx->uNumParms == 2, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(pfAction, VERR_INVALID_POINTER);
+
+    int rc;
+    do
+    {
+        HGCMMsgShutdown Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, vbglR3GuestCtrlGetMsgFunctionNo(pCtx->uClientID), pCtx->uNumParms);
+        VbglHGCMParmUInt32Set(&Msg.context, HOST_MSG_SHUTDOWN);
+        VbglHGCMParmUInt32Set(&Msg.action,  0);
+
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            Msg.context.GetUInt32(&pCtx->uContextID);
+            Msg.action.GetUInt32(pfAction);
+        }
+    } while (rc == VERR_INTERRUPTED && g_fVbglR3GuestCtrlHavePeekGetCancel);
+    return rc;
+}
+
+/**
+ * Initializes a process startup info, extended version.
+ *
+ * @returns VBox status code.
+ * @param   pStartupInfo        Process startup info to initializes.
+ * @param   cbCmd               Size (in bytes) to use for the command buffer.
+ * @param   cbUser              Size (in bytes) to use for the user name buffer.
+ * @param   cbPassword          Size (in bytes) to use for the password buffer.
+ * @param   cbDomain            Size (in bytes) to use for the domain buffer.
+ * @param   cbArgs              Size (in bytes) to use for the arguments buffer.
+ * @param   cbEnv               Size (in bytes) to use for the environment buffer.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlProcStartupInfoInitEx(PVBGLR3GUESTCTRLPROCSTARTUPINFO pStartupInfo,
+                                                     size_t cbCmd,
+                                                     size_t cbUser, size_t cbPassword, size_t cbDomain,
+                                                     size_t cbArgs, size_t cbEnv)
+{
+    AssertPtrReturn(pStartupInfo, VERR_INVALID_POINTER);
+    AssertReturn(cbCmd,           VERR_INVALID_PARAMETER);
+    AssertReturn(cbUser,          VERR_INVALID_PARAMETER);
+    AssertReturn(cbPassword,      VERR_INVALID_PARAMETER);
+    AssertReturn(cbDomain,        VERR_INVALID_PARAMETER);
+    AssertReturn(cbArgs,          VERR_INVALID_PARAMETER);
+    AssertReturn(cbEnv,           VERR_INVALID_PARAMETER);
+
+    RT_BZERO(pStartupInfo, sizeof(VBGLR3GUESTCTRLPROCSTARTUPINFO));
+
+#define ALLOC_STR(a_Str, a_cb) \
+    if ((a_cb) > 0) \
+    { \
+        pStartupInfo->psz##a_Str = RTStrAlloc(a_cb); \
+        AssertPtrBreak(pStartupInfo->psz##a_Str); \
+        pStartupInfo->cb##a_Str  = (uint32_t)a_cb; \
+    }
+
+    do
+    {
+        ALLOC_STR(Cmd,      cbCmd);
+        ALLOC_STR(Args,     cbArgs);
+        ALLOC_STR(Env,      cbEnv);
+        ALLOC_STR(User,     cbUser);
+        ALLOC_STR(Password, cbPassword);
+        ALLOC_STR(Domain,   cbDomain);
+
+        return VINF_SUCCESS;
+
+    } while (0);
+
+#undef ALLOC_STR
+
+    VbglR3GuestCtrlProcStartupInfoDestroy(pStartupInfo);
+    return VERR_NO_MEMORY;
+}
+
+/**
+ * Initializes a process startup info with default values.
+ *
+ * @param   pStartupInfo        Process startup info to initializes.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlProcStartupInfoInit(PVBGLR3GUESTCTRLPROCSTARTUPINFO pStartupInfo)
+{
+    return VbglR3GuestCtrlProcStartupInfoInitEx(pStartupInfo,
+                                                GUEST_PROC_DEF_CMD_LEN,
+                                                GUEST_PROC_DEF_USER_LEN     /* Deprecated, now handled via session creation. */,
+                                                GUEST_PROC_DEF_PASSWORD_LEN /* Ditto. */,
+                                                GUEST_PROC_DEF_DOMAIN_LEN   /* Ditto. */,
+                                                GUEST_PROC_DEF_ARGS_LEN, GUEST_PROC_DEF_ENV_LEN);
+}
+
+/**
+ * Destroys a process startup info.
+ *
+ * @param   pStartupInfo        Process startup info to destroy.
+ */
+VBGLR3DECL(void) VbglR3GuestCtrlProcStartupInfoDestroy(PVBGLR3GUESTCTRLPROCSTARTUPINFO pStartupInfo)
+{
+    if (!pStartupInfo)
+        return;
+
+    RTStrFree(pStartupInfo->pszCmd);
+    RTStrFree(pStartupInfo->pszArgs);
+    RTStrFree(pStartupInfo->pszEnv);
+    RTStrFree(pStartupInfo->pszUser);
+    RTStrFree(pStartupInfo->pszPassword);
+    RTStrFree(pStartupInfo->pszDomain);
+
+    RT_BZERO(pStartupInfo, sizeof(VBGLR3GUESTCTRLPROCSTARTUPINFO));
+}
+
+/**
+ * Free's a process startup info.
+ *
+ * @param   pStartupInfo        Process startup info to free.
+ *                              The pointer will not be valid anymore after return.
+ */
+VBGLR3DECL(void) VbglR3GuestCtrlProcStartupInfoFree(PVBGLR3GUESTCTRLPROCSTARTUPINFO pStartupInfo)
+{
+    if (!pStartupInfo)
+        return;
+
+    VbglR3GuestCtrlProcStartupInfoDestroy(pStartupInfo);
+
+    RTMemFree(pStartupInfo);
+    pStartupInfo = NULL;
+}
+
+/**
+ * Duplicates a process startup info.
+ *
+ * @returns Duplicated process startup info on success, or NULL on error.
+ * @param   pStartupInfo        Process startup info to duplicate.
+ */
+VBGLR3DECL(PVBGLR3GUESTCTRLPROCSTARTUPINFO) VbglR3GuestCtrlProcStartupInfoDup(PVBGLR3GUESTCTRLPROCSTARTUPINFO pStartupInfo)
+{
+    AssertPtrReturn(pStartupInfo, NULL);
+
+    PVBGLR3GUESTCTRLPROCSTARTUPINFO pStartupInfoDup = (PVBGLR3GUESTCTRLPROCSTARTUPINFO)
+                                                            RTMemDup(pStartupInfo, sizeof(VBGLR3GUESTCTRLPROCSTARTUPINFO));
+    if (pStartupInfoDup)
+    {
+        do
+        {
+            pStartupInfoDup->pszCmd      = NULL;
+            pStartupInfoDup->pszArgs     = NULL;
+            pStartupInfoDup->pszEnv      = NULL;
+            pStartupInfoDup->pszUser     = NULL;
+            pStartupInfoDup->pszPassword = NULL;
+            pStartupInfoDup->pszDomain   = NULL;
+
+#define DUP_STR(a_Str) \
+    if (pStartupInfo->cb##a_Str) \
+    { \
+        pStartupInfoDup->psz##a_Str = (char *)RTStrDup(pStartupInfo->psz##a_Str); \
+        AssertPtrBreak(pStartupInfoDup->psz##a_Str); \
+        pStartupInfoDup->cb##a_Str  = (uint32_t)strlen(pStartupInfoDup->psz##a_Str) + 1 /* Include terminator */; \
+    }
+
+#define DUP_MEM(a_Str) \
+    if (pStartupInfo->cb##a_Str) \
+    { \
+        pStartupInfoDup->psz##a_Str = (char *)RTMemDup(pStartupInfo->psz##a_Str, pStartupInfo->cb##a_Str); \
+        AssertPtrBreak(pStartupInfoDup->psz##a_Str); \
+        pStartupInfoDup->cb##a_Str  = (uint32_t)pStartupInfo->cb##a_Str; \
+    }
+
+            DUP_STR(Cmd);
+            DUP_MEM(Args);
+            DUP_MEM(Env);
+            DUP_STR(User);
+            DUP_STR(Password);
+            DUP_STR(Domain);
+
+#undef DUP_STR
+#undef DUP_MEM
+
+            return pStartupInfoDup;
+
+        } while (0); /* To use break macros above. */
+
+        VbglR3GuestCtrlProcStartupInfoFree(pStartupInfoDup);
+    }
+
+    return NULL;
+}
+
+/**
+ * Retrieves a HOST_EXEC_CMD message.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Guest control command context to use.
+ * @param   ppStartupInfo       Where to store the allocated session startup info.
+ *                              Needs to be free'd by VbglR3GuestCtrlProcStartupInfoFree().
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlProcGetStart(PVBGLR3GUESTCTRLCMDCTX pCtx, PVBGLR3GUESTCTRLPROCSTARTUPINFO *ppStartupInfo)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+    AssertPtrReturn(ppStartupInfo, VERR_INVALID_POINTER);
+
+    PVBGLR3GUESTCTRLPROCSTARTUPINFO pStartupInfo
+        = (PVBGLR3GUESTCTRLPROCSTARTUPINFO)RTMemAlloc(sizeof(VBGLR3GUESTCTRLPROCSTARTUPINFO));
+    if (!pStartupInfo)
+        return VERR_NO_MEMORY;
+
+    int rc = VbglR3GuestCtrlProcStartupInfoInit(pStartupInfo);
+    if (RT_FAILURE(rc))
+    {
+        VbglR3GuestCtrlProcStartupInfoFree(pStartupInfo);
+        return rc;
+    }
+
+    unsigned       cRetries      = 0;
+    const unsigned cMaxRetries   = 32; /* Should be enough for now. */
+    const unsigned cGrowthFactor = 2;  /* By how much the buffers will grow if they're too small yet. */
+
+    do
+    {
+        LogRel(("VbglR3GuestCtrlProcGetStart: Retrieving\n"));
+
+        HGCMMsgProcExec Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, vbglR3GuestCtrlGetMsgFunctionNo(pCtx->uClientID), pCtx->uNumParms);
+        VbglHGCMParmUInt32Set(&Msg.context, HOST_MSG_EXEC_CMD);
+        VbglHGCMParmPtrSet(&Msg.cmd, pStartupInfo->pszCmd, pStartupInfo->cbCmd);
+        VbglHGCMParmUInt32Set(&Msg.flags, 0);
+        VbglHGCMParmUInt32Set(&Msg.num_args, 0);
+        VbglHGCMParmPtrSet(&Msg.args, pStartupInfo->pszArgs, pStartupInfo->cbArgs);
+        VbglHGCMParmUInt32Set(&Msg.num_env, 0);
+        VbglHGCMParmUInt32Set(&Msg.cb_env, 0);
+        VbglHGCMParmPtrSet(&Msg.env, pStartupInfo->pszEnv, pStartupInfo->cbEnv);
+        if (pCtx->uProtocol < 2)
+        {
+            VbglHGCMParmPtrSet(&Msg.u.v1.username, pStartupInfo->pszUser, pStartupInfo->cbUser);
+            VbglHGCMParmPtrSet(&Msg.u.v1.password, pStartupInfo->pszPassword, pStartupInfo->cbPassword);
+            VbglHGCMParmUInt32Set(&Msg.u.v1.timeout, 0);
+        }
+        else
+        {
+            VbglHGCMParmUInt32Set(&Msg.u.v2.timeout, 0);
+            VbglHGCMParmUInt32Set(&Msg.u.v2.priority, 0);
+            VbglHGCMParmUInt32Set(&Msg.u.v2.num_affinity, 0);
+            VbglHGCMParmPtrSet(&Msg.u.v2.affinity, pStartupInfo->uAffinity, sizeof(pStartupInfo->uAffinity));
+        }
+
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+        if (RT_FAILURE(rc))
+        {
+            LogRel(("VbglR3GuestCtrlProcGetStart: 1 - %Rrc (retry %u, cbCmd=%RU32, cbArgs=%RU32, cbEnv=%RU32)\n",
+                    rc, cRetries, pStartupInfo->cbCmd, pStartupInfo->cbArgs, pStartupInfo->cbEnv));
+
+            if (   rc == VERR_BUFFER_OVERFLOW
+                && cRetries++ < cMaxRetries)
+            {
+#define GROW_STR(a_Str, a_cbMax) \
+        pStartupInfo->psz##a_Str = (char *)RTMemRealloc(pStartupInfo->psz##a_Str, \
+           RT_MIN(pStartupInfo->cb##a_Str * cGrowthFactor, a_cbMax)); \
+        AssertPtrBreakStmt(pStartupInfo->psz##a_Str, VERR_NO_MEMORY); \
+        pStartupInfo->cb##a_Str  = RT_MIN(pStartupInfo->cb##a_Str * cGrowthFactor, a_cbMax);
+
+                /* We can't tell which parameter doesn't fit, so we have to resize all. */
+                GROW_STR(Cmd , GUEST_PROC_MAX_CMD_LEN);
+                GROW_STR(Args, GUEST_PROC_MAX_ARGS_LEN);
+                GROW_STR(Env,  GUEST_PROC_MAX_ENV_LEN);
+
+#undef GROW_STR
+                LogRel(("VbglR3GuestCtrlProcGetStart: 2 - %Rrc (retry %u, cbCmd=%RU32, cbArgs=%RU32, cbEnv=%RU32)\n",
+                        rc, cRetries, pStartupInfo->cbCmd, pStartupInfo->cbArgs, pStartupInfo->cbEnv));
+                LogRel(("g_fVbglR3GuestCtrlHavePeekGetCancel=%RTbool\n", RT_BOOL(g_fVbglR3GuestCtrlHavePeekGetCancel)));
+            }
+            else
+                break;
+        }
+        else
+        {
+            Msg.context.GetUInt32(&pCtx->uContextID);
+            Msg.flags.GetUInt32(&pStartupInfo->fFlags);
+            Msg.num_args.GetUInt32(&pStartupInfo->cArgs);
+            Msg.num_env.GetUInt32(&pStartupInfo->cEnvVars);
+            Msg.cb_env.GetUInt32(&pStartupInfo->cbEnv);
+            if (pCtx->uProtocol < 2)
+                Msg.u.v1.timeout.GetUInt32(&pStartupInfo->uTimeLimitMS);
+            else
+            {
+                Msg.u.v2.timeout.GetUInt32(&pStartupInfo->uTimeLimitMS);
+                Msg.u.v2.priority.GetUInt32(&pStartupInfo->uPriority);
+                Msg.u.v2.num_affinity.GetUInt32(&pStartupInfo->cAffinity);
+            }
+        }
+    } while ((   rc == VERR_INTERRUPTED
+              || rc == VERR_BUFFER_OVERFLOW) && g_fVbglR3GuestCtrlHavePeekGetCancel);
+
+    if (RT_SUCCESS(rc))
+    {
+        *ppStartupInfo = pStartupInfo;
+    }
+    else
+        VbglR3GuestCtrlProcStartupInfoFree(pStartupInfo);
+
+    LogRel(("VbglR3GuestCtrlProcGetStart: Returning %Rrc (retry %u, cbCmd=%RU32, cbArgs=%RU32, cbEnv=%RU32)\n",
+            rc, cRetries, pStartupInfo->cbCmd, pStartupInfo->cbArgs, pStartupInfo->cbEnv));
+
+    LogFlowFuncLeaveRC(rc);
+    return rc;
+}
+
+/**
+ * Allocates and gets host data, based on the message ID.
+ *
+ * This will block until data becomes available.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                    Guest control command context to use.
+ * @param   puPID                   Where to return the guest PID to retrieve output from on success.
+ * @param   puHandle                Where to return the guest process handle to retrieve output from on success.
+ * @param   pfFlags                 Where to return the output flags on success.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlProcGetOutput(PVBGLR3GUESTCTRLCMDCTX pCtx,
+                                             uint32_t *puPID, uint32_t *puHandle, uint32_t *pfFlags)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+    AssertReturn(pCtx->uNumParms == 4, VERR_INVALID_PARAMETER);
+
+    AssertPtrReturn(puPID, VERR_INVALID_POINTER);
+    AssertPtrReturn(puHandle, VERR_INVALID_POINTER);
+    AssertPtrReturn(pfFlags, VERR_INVALID_POINTER);
+
+    int rc;
+    do
+    {
+        HGCMMsgProcOutput Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, vbglR3GuestCtrlGetMsgFunctionNo(pCtx->uClientID), pCtx->uNumParms);
+        VbglHGCMParmUInt32Set(&Msg.context, HOST_MSG_EXEC_GET_OUTPUT);
+        VbglHGCMParmUInt32Set(&Msg.pid, 0);
+        VbglHGCMParmUInt32Set(&Msg.handle, 0);
+        VbglHGCMParmUInt32Set(&Msg.flags, 0);
+
+        rc = VbglR3HGCMCall(&Msg.hdr, RT_UOFFSETOF(HGCMMsgProcOutput, data));
+        if (RT_SUCCESS(rc))
+        {
+            Msg.context.GetUInt32(&pCtx->uContextID);
+            Msg.pid.GetUInt32(puPID);
+            Msg.handle.GetUInt32(puHandle);
+            Msg.flags.GetUInt32(pfFlags);
+        }
+    } while (rc == VERR_INTERRUPTED && g_fVbglR3GuestCtrlHavePeekGetCancel);
+    return rc;
+}
+
+
+/**
+ * Retrieves the input data from host which then gets sent to the started
+ * process (HOST_EXEC_SET_INPUT).
+ *
+ * This will block until data becomes available.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlProcGetInput(PVBGLR3GUESTCTRLCMDCTX  pCtx,
+                                            uint32_t  *puPID,       uint32_t *pfFlags,
+                                            void      *pvData,      uint32_t  cbData,
+                                            uint32_t  *pcbSize)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+    AssertReturn(pCtx->uNumParms == 5, VERR_INVALID_PARAMETER);
+
+    AssertPtrReturn(puPID, VERR_INVALID_POINTER);
+    AssertPtrReturn(pfFlags, VERR_INVALID_POINTER);
+    AssertPtrReturn(pvData, VERR_INVALID_POINTER);
+    AssertPtrReturn(pcbSize, VERR_INVALID_POINTER);
+
+    int rc;
+    do
+    {
+        HGCMMsgProcInput Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, vbglR3GuestCtrlGetMsgFunctionNo(pCtx->uClientID), pCtx->uNumParms);
+        VbglHGCMParmUInt32Set(&Msg.context, HOST_MSG_EXEC_SET_INPUT);
+        VbglHGCMParmUInt32Set(&Msg.pid, 0);
+        VbglHGCMParmUInt32Set(&Msg.flags, 0);
+        VbglHGCMParmPtrSet(&Msg.data, pvData, cbData);
+        VbglHGCMParmUInt32Set(&Msg.size, 0);
+
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            Msg.context.GetUInt32(&pCtx->uContextID);
+            Msg.pid.GetUInt32(puPID);
+            Msg.flags.GetUInt32(pfFlags);
+            Msg.size.GetUInt32(pcbSize);
+        }
+    } while (rc == VERR_INTERRUPTED && g_fVbglR3GuestCtrlHavePeekGetCancel);
+
+    if (   rc != VERR_TOO_MUCH_DATA
+        || g_fVbglR3GuestCtrlHavePeekGetCancel)
+        return rc;
+    return VERR_BUFFER_OVERFLOW;
+}
+
+
+/**
+ * Retrieves a HOST_DIR_REMOVE message.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlDirGetRemove(PVBGLR3GUESTCTRLCMDCTX     pCtx,
+                                            char     *pszPath,         uint32_t cbPath,
+                                            uint32_t *pfFlags)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+    AssertReturn(pCtx->uNumParms == 3, VERR_INVALID_PARAMETER);
+
+    AssertPtrReturn(pszPath, VERR_INVALID_POINTER);
+    AssertReturn(cbPath, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(pfFlags, VERR_INVALID_POINTER);
+
+    int rc;
+    do
+    {
+        HGCMMsgDirRemove Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, vbglR3GuestCtrlGetMsgFunctionNo(pCtx->uClientID), pCtx->uNumParms);
+        VbglHGCMParmUInt32Set(&Msg.context, HOST_MSG_DIR_REMOVE);
+        VbglHGCMParmPtrSet(&Msg.path, pszPath, cbPath);
+        VbglHGCMParmUInt32Set(&Msg.flags, 0);
+
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            Msg.context.GetUInt32(&pCtx->uContextID);
+            Msg.flags.GetUInt32(pfFlags);
+        }
+    } while (rc == VERR_INTERRUPTED && g_fVbglR3GuestCtrlHavePeekGetCancel);
+    return rc;
+}
+
+
+/**
+ * Retrieves a HOST_FILE_OPEN message.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlFileGetOpen(PVBGLR3GUESTCTRLCMDCTX      pCtx,
+                                           char     *pszFileName,      uint32_t cbFileName,
+                                           char     *pszAccess,        uint32_t cbAccess,
+                                           char     *pszDisposition,   uint32_t cbDisposition,
+                                           char     *pszSharing,       uint32_t cbSharing,
+                                           uint32_t *puCreationMode,
+                                           uint64_t *poffAt)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+    AssertReturn(pCtx->uNumParms == 7, VERR_INVALID_PARAMETER);
+
+    AssertPtrReturn(pszFileName, VERR_INVALID_POINTER);
+    AssertReturn(cbFileName, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(pszAccess, VERR_INVALID_POINTER);
+    AssertReturn(cbAccess, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(pszDisposition, VERR_INVALID_POINTER);
+    AssertReturn(cbDisposition, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(pszSharing, VERR_INVALID_POINTER);
+    AssertReturn(cbSharing, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(puCreationMode, VERR_INVALID_POINTER);
+    AssertPtrReturn(poffAt, VERR_INVALID_POINTER);
+
+    int rc;
+    do
+    {
+        HGCMMsgFileOpen Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, vbglR3GuestCtrlGetMsgFunctionNo(pCtx->uClientID), pCtx->uNumParms);
+        VbglHGCMParmUInt32Set(&Msg.context, HOST_MSG_FILE_OPEN);
+        VbglHGCMParmPtrSet(&Msg.filename, pszFileName, cbFileName);
+        VbglHGCMParmPtrSet(&Msg.openmode, pszAccess, cbAccess);
+        VbglHGCMParmPtrSet(&Msg.disposition, pszDisposition, cbDisposition);
+        VbglHGCMParmPtrSet(&Msg.sharing, pszSharing, cbSharing);
+        VbglHGCMParmUInt32Set(&Msg.creationmode, 0);
+        VbglHGCMParmUInt64Set(&Msg.offset, 0);
+
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            Msg.context.GetUInt32(&pCtx->uContextID);
+            Msg.creationmode.GetUInt32(puCreationMode);
+            Msg.offset.GetUInt64(poffAt);
+        }
+    } while (rc == VERR_INTERRUPTED && g_fVbglR3GuestCtrlHavePeekGetCancel);
+    return rc;
+}
+
+
+/**
+ * Retrieves a HOST_FILE_CLOSE message.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlFileGetClose(PVBGLR3GUESTCTRLCMDCTX pCtx, uint32_t *puHandle)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    AssertReturn(pCtx->uNumParms == 2, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(puHandle, VERR_INVALID_POINTER);
+
+    int rc;
+    do
+    {
+        HGCMMsgFileClose Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, vbglR3GuestCtrlGetMsgFunctionNo(pCtx->uClientID), pCtx->uNumParms);
+        VbglHGCMParmUInt32Set(&Msg.context, HOST_MSG_FILE_CLOSE);
+        VbglHGCMParmUInt32Set(&Msg.handle, 0);
+
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            Msg.context.GetUInt32(&pCtx->uContextID);
+            Msg.handle.GetUInt32(puHandle);
+        }
+    } while (rc == VERR_INTERRUPTED && g_fVbglR3GuestCtrlHavePeekGetCancel);
+    return rc;
+}
+
+
+/**
+ * Retrieves a HOST_FILE_READ message.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlFileGetRead(PVBGLR3GUESTCTRLCMDCTX pCtx, uint32_t *puHandle, uint32_t *puToRead)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    AssertReturn(pCtx->uNumParms == 3, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(puHandle, VERR_INVALID_POINTER);
+    AssertPtrReturn(puToRead, VERR_INVALID_POINTER);
+
+    int rc;
+    do
+    {
+        HGCMMsgFileRead Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, vbglR3GuestCtrlGetMsgFunctionNo(pCtx->uClientID), pCtx->uNumParms);
+        VbglHGCMParmUInt32Set(&Msg.context, HOST_MSG_FILE_READ);
+        VbglHGCMParmUInt32Set(&Msg.handle, 0);
+        VbglHGCMParmUInt32Set(&Msg.size, 0);
+
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            Msg.context.GetUInt32(&pCtx->uContextID);
+            Msg.handle.GetUInt32(puHandle);
+            Msg.size.GetUInt32(puToRead);
+        }
+    } while (rc == VERR_INTERRUPTED && g_fVbglR3GuestCtrlHavePeekGetCancel);
+    return rc;
+}
+
+
+/**
+ * Retrieves a HOST_FILE_READ_AT message.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlFileGetReadAt(PVBGLR3GUESTCTRLCMDCTX pCtx,
+                                             uint32_t *puHandle, uint32_t *puToRead, uint64_t *poffAt)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    AssertReturn(pCtx->uNumParms == 4, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(puHandle, VERR_INVALID_POINTER);
+    AssertPtrReturn(puToRead, VERR_INVALID_POINTER);
+
+    int rc;
+    do
+    {
+        HGCMMsgFileReadAt Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, vbglR3GuestCtrlGetMsgFunctionNo(pCtx->uClientID), pCtx->uNumParms);
+        VbglHGCMParmUInt32Set(&Msg.context, HOST_MSG_FILE_READ_AT);
+        VbglHGCMParmUInt32Set(&Msg.handle, 0);
+        VbglHGCMParmUInt64Set(&Msg.offset, 0);
+        VbglHGCMParmUInt32Set(&Msg.size, 0);
+
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            Msg.context.GetUInt32(&pCtx->uContextID);
+            Msg.handle.GetUInt32(puHandle);
+            Msg.offset.GetUInt64(poffAt);
+            Msg.size.GetUInt32(puToRead);
+        }
+    } while (rc == VERR_INTERRUPTED && g_fVbglR3GuestCtrlHavePeekGetCancel);
+    return rc;
+}
+
+
+/**
+ * Retrieves a HOST_FILE_WRITE message.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlFileGetWrite(PVBGLR3GUESTCTRLCMDCTX pCtx, uint32_t *puHandle,
+                                            void *pvData, uint32_t cbData, uint32_t *pcbSize)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    AssertReturn(pCtx->uNumParms == 4, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(puHandle, VERR_INVALID_POINTER);
+    AssertPtrReturn(pvData, VERR_INVALID_POINTER);
+    AssertReturn(cbData, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(pcbSize, VERR_INVALID_POINTER);
+
+    int rc;
+    do
+    {
+        HGCMMsgFileWrite Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, vbglR3GuestCtrlGetMsgFunctionNo(pCtx->uClientID), pCtx->uNumParms);
+        VbglHGCMParmUInt32Set(&Msg.context, HOST_MSG_FILE_WRITE);
+        VbglHGCMParmUInt32Set(&Msg.handle, 0);
+        VbglHGCMParmPtrSet(&Msg.data, pvData, cbData);
+        VbglHGCMParmUInt32Set(&Msg.size, 0);
+
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            Msg.context.GetUInt32(&pCtx->uContextID);
+            Msg.handle.GetUInt32(puHandle);
+            Msg.size.GetUInt32(pcbSize);
+        }
+    } while (rc == VERR_INTERRUPTED && g_fVbglR3GuestCtrlHavePeekGetCancel);
+
+    if (   rc != VERR_TOO_MUCH_DATA
+        || g_fVbglR3GuestCtrlHavePeekGetCancel)
+        return rc;
+    return VERR_BUFFER_OVERFLOW;
+}
+
+
+/**
+ * Retrieves a HOST_FILE_WRITE_AT message.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlFileGetWriteAt(PVBGLR3GUESTCTRLCMDCTX pCtx, uint32_t *puHandle,
+                                              void *pvData, uint32_t cbData, uint32_t *pcbSize, uint64_t *poffAt)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    AssertReturn(pCtx->uNumParms == 5, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(puHandle, VERR_INVALID_POINTER);
+    AssertPtrReturn(pvData, VERR_INVALID_POINTER);
+    AssertReturn(cbData, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(pcbSize, VERR_INVALID_POINTER);
+
+    int rc;
+    do
+    {
+        HGCMMsgFileWriteAt Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, vbglR3GuestCtrlGetMsgFunctionNo(pCtx->uClientID), pCtx->uNumParms);
+        VbglHGCMParmUInt32Set(&Msg.context, HOST_MSG_FILE_WRITE_AT);
+        VbglHGCMParmUInt32Set(&Msg.handle, 0);
+        VbglHGCMParmPtrSet(&Msg.data, pvData, cbData);
+        VbglHGCMParmUInt32Set(&Msg.size, 0);
+        VbglHGCMParmUInt64Set(&Msg.offset, 0);
+
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            Msg.context.GetUInt32(&pCtx->uContextID);
+            Msg.handle.GetUInt32(puHandle);
+            Msg.size.GetUInt32(pcbSize);
+            Msg.offset.GetUInt64(poffAt);
+        }
+    } while (rc == VERR_INTERRUPTED && g_fVbglR3GuestCtrlHavePeekGetCancel);
+
+    if (   rc != VERR_TOO_MUCH_DATA
+        || g_fVbglR3GuestCtrlHavePeekGetCancel)
+        return rc;
+    return VERR_BUFFER_OVERFLOW;
+}
+
+
+/**
+ * Retrieves a HOST_FILE_SEEK message.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlFileGetSeek(PVBGLR3GUESTCTRLCMDCTX pCtx,
+                                           uint32_t *puHandle, uint32_t *puSeekMethod, uint64_t *poffAt)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    AssertReturn(pCtx->uNumParms == 4, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(puHandle, VERR_INVALID_POINTER);
+    AssertPtrReturn(puSeekMethod, VERR_INVALID_POINTER);
+    AssertPtrReturn(poffAt, VERR_INVALID_POINTER);
+
+    int rc;
+    do
+    {
+        HGCMMsgFileSeek Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, vbglR3GuestCtrlGetMsgFunctionNo(pCtx->uClientID), pCtx->uNumParms);
+        VbglHGCMParmUInt32Set(&Msg.context, HOST_MSG_FILE_SEEK);
+        VbglHGCMParmUInt32Set(&Msg.handle, 0);
+        VbglHGCMParmUInt32Set(&Msg.method, 0);
+        VbglHGCMParmUInt64Set(&Msg.offset, 0);
+
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            Msg.context.GetUInt32(&pCtx->uContextID);
+            Msg.handle.GetUInt32(puHandle);
+            Msg.method.GetUInt32(puSeekMethod);
+            Msg.offset.GetUInt64(poffAt);
+        }
+    } while (rc == VERR_INTERRUPTED && g_fVbglR3GuestCtrlHavePeekGetCancel);
+    return rc;
+}
+
+
+/**
+ * Retrieves a HOST_FILE_TELL message.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlFileGetTell(PVBGLR3GUESTCTRLCMDCTX pCtx, uint32_t *puHandle)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    AssertReturn(pCtx->uNumParms == 2, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(puHandle, VERR_INVALID_POINTER);
+
+    int rc;
+    do
+    {
+        HGCMMsgFileTell Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, vbglR3GuestCtrlGetMsgFunctionNo(pCtx->uClientID), pCtx->uNumParms);
+        VbglHGCMParmUInt32Set(&Msg.context, HOST_MSG_FILE_TELL);
+        VbglHGCMParmUInt32Set(&Msg.handle, 0);
+
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            Msg.context.GetUInt32(&pCtx->uContextID);
+            Msg.handle.GetUInt32(puHandle);
+        }
+    } while (rc == VERR_INTERRUPTED && g_fVbglR3GuestCtrlHavePeekGetCancel);
+    return rc;
+}
+
+
+/**
+ * Retrieves a HOST_FILE_SET_SIZE message.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlFileGetSetSize(PVBGLR3GUESTCTRLCMDCTX pCtx, uint32_t *puHandle, uint64_t *pcbNew)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    AssertReturn(pCtx->uNumParms == 3, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(puHandle, VERR_INVALID_POINTER);
+    AssertPtrReturn(pcbNew, VERR_INVALID_POINTER);
+
+    int rc;
+    do
+    {
+        HGCMMsgFileSetSize Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.Hdr, pCtx->uClientID, vbglR3GuestCtrlGetMsgFunctionNo(pCtx->uClientID), pCtx->uNumParms);
+        VbglHGCMParmUInt32Set(&Msg.id32Context, HOST_MSG_FILE_SET_SIZE);
+        VbglHGCMParmUInt32Set(&Msg.id32Handle, 0);
+        VbglHGCMParmUInt64Set(&Msg.cb64NewSize, 0);
+
+        rc = VbglR3HGCMCall(&Msg.Hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            Msg.id32Context.GetUInt32(&pCtx->uContextID);
+            Msg.id32Handle.GetUInt32(puHandle);
+            Msg.cb64NewSize.GetUInt64(pcbNew);
+        }
+    } while (rc == VERR_INTERRUPTED && g_fVbglR3GuestCtrlHavePeekGetCancel);
+    return rc;
+}
+
+
+/**
+ * Retrieves a HOST_EXEC_TERMINATE message.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlProcGetTerminate(PVBGLR3GUESTCTRLCMDCTX pCtx, uint32_t *puPID)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    AssertReturn(pCtx->uNumParms == 2, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(puPID, VERR_INVALID_POINTER);
+
+    int rc;
+    do
+    {
+        HGCMMsgProcTerminate Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, vbglR3GuestCtrlGetMsgFunctionNo(pCtx->uClientID), pCtx->uNumParms);
+        VbglHGCMParmUInt32Set(&Msg.context, HOST_MSG_EXEC_TERMINATE);
+        VbglHGCMParmUInt32Set(&Msg.pid, 0);
+
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            Msg.context.GetUInt32(&pCtx->uContextID);
+            Msg.pid.GetUInt32(puPID);
+        }
+    } while (rc == VERR_INTERRUPTED && g_fVbglR3GuestCtrlHavePeekGetCancel);
+    return rc;
+}
+
+
+/**
+ * Retrieves a HOST_EXEC_WAIT_FOR message.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlProcGetWaitFor(PVBGLR3GUESTCTRLCMDCTX pCtx,
+                                              uint32_t *puPID, uint32_t *puWaitFlags, uint32_t *puTimeoutMS)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    AssertReturn(pCtx->uNumParms == 5, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(puPID, VERR_INVALID_POINTER);
+
+    int rc;
+    do
+    {
+        HGCMMsgProcWaitFor Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, vbglR3GuestCtrlGetMsgFunctionNo(pCtx->uClientID), pCtx->uNumParms);
+        VbglHGCMParmUInt32Set(&Msg.context, HOST_MSG_EXEC_WAIT_FOR);
+        VbglHGCMParmUInt32Set(&Msg.pid, 0);
+        VbglHGCMParmUInt32Set(&Msg.flags, 0);
+        VbglHGCMParmUInt32Set(&Msg.timeout, 0);
+
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            Msg.context.GetUInt32(&pCtx->uContextID);
+            Msg.pid.GetUInt32(puPID);
+            Msg.flags.GetUInt32(puWaitFlags);
+            Msg.timeout.GetUInt32(puTimeoutMS);
+        }
+    } while (rc == VERR_INTERRUPTED && g_fVbglR3GuestCtrlHavePeekGetCancel);
+    return rc;
+}
+
+
+/**
+ * Replies to a HOST_MSG_FILE_OPEN message.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Guest control command context to use.
+ * @param   uRc                 Guest rc of operation (note: IPRT-style signed int).
+ * @param   uFileHandle         File handle of opened file on success.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlFileCbOpen(PVBGLR3GUESTCTRLCMDCTX pCtx,
+                                          uint32_t uRc, uint32_t uFileHandle)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    HGCMReplyFileNotify Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_MSG_FILE_NOTIFY, 4);
+    VbglHGCMParmUInt32Set(&Msg.context, pCtx->uContextID);
+    VbglHGCMParmUInt32Set(&Msg.type, GUEST_FILE_NOTIFYTYPE_OPEN);
+    VbglHGCMParmUInt32Set(&Msg.rc, uRc);
+    VbglHGCMParmUInt32Set(&Msg.u.open.handle, uFileHandle);
+
+    return VbglR3HGCMCall(&Msg.hdr, RT_UOFFSET_AFTER(HGCMReplyFileNotify, u.open));
+}
+
+
+/**
+ * Replies to a HOST_MSG_FILE_CLOSE message.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Guest control command context to use.
+ * @param   uRc                 Guest rc of operation (note: IPRT-style signed int).
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlFileCbClose(PVBGLR3GUESTCTRLCMDCTX pCtx,
+                                           uint32_t uRc)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    HGCMReplyFileNotify Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_MSG_FILE_NOTIFY, 3);
+    VbglHGCMParmUInt32Set(&Msg.context, pCtx->uContextID);
+    VbglHGCMParmUInt32Set(&Msg.type, GUEST_FILE_NOTIFYTYPE_CLOSE);
+    VbglHGCMParmUInt32Set(&Msg.rc, uRc);
+
+    return VbglR3HGCMCall(&Msg.hdr, RT_UOFFSETOF(HGCMReplyFileNotify, u));
+}
+
+
+/**
+ * Sends an unexpected file handling error to the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Guest control command context to use.
+ * @param   uRc                 Guest rc of operation (note: IPRT-style signed int).
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlFileCbError(PVBGLR3GUESTCTRLCMDCTX pCtx, uint32_t uRc)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    HGCMReplyFileNotify Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_MSG_FILE_NOTIFY, 3);
+    VbglHGCMParmUInt32Set(&Msg.context, pCtx->uContextID);
+    VbglHGCMParmUInt32Set(&Msg.type, GUEST_FILE_NOTIFYTYPE_ERROR);
+    VbglHGCMParmUInt32Set(&Msg.rc, uRc);
+
+    return VbglR3HGCMCall(&Msg.hdr, RT_UOFFSETOF(HGCMReplyFileNotify, u));
+}
+
+
+/**
+ * Replies to a HOST_MSG_FILE_READ message.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Guest control command context to use.
+ * @param   uRc                 Guest rc of operation (note: IPRT-style signed int).
+ * @param   pvData              Pointer to read file data from guest on success.
+ * @param   cbData              Size (in bytes) of read file data from guest on success.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlFileCbRead(PVBGLR3GUESTCTRLCMDCTX pCtx,
+                                          uint32_t uRc,
+                                          void *pvData, uint32_t cbData)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    HGCMReplyFileNotify Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_MSG_FILE_NOTIFY, 4);
+    VbglHGCMParmUInt32Set(&Msg.context, pCtx->uContextID);
+    VbglHGCMParmUInt32Set(&Msg.type, GUEST_FILE_NOTIFYTYPE_READ);
+    VbglHGCMParmUInt32Set(&Msg.rc, uRc);
+    VbglHGCMParmPtrSet(&Msg.u.read.data, pvData, cbData);
+
+    return VbglR3HGCMCall(&Msg.hdr, RT_UOFFSET_AFTER(HGCMReplyFileNotify, u.read));
+}
+
+
+/**
+ * Replies to a HOST_MSG_FILE_READ_AT message.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Guest control command context to use.
+ * @param   uRc                 Guest rc of operation (note: IPRT-style signed int).
+ * @param   pvData              Pointer to read file data from guest on success.
+ * @param   cbData              Size (in bytes) of read file data from guest on success.
+ * @param   offNew              New offset (in bytes) the guest file pointer points at on success.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlFileCbReadOffset(PVBGLR3GUESTCTRLCMDCTX pCtx, uint32_t uRc,
+                                                void *pvData, uint32_t cbData, int64_t offNew)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    HGCMReplyFileNotify Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_MSG_FILE_NOTIFY, 5);
+    VbglHGCMParmUInt32Set(&Msg.context, pCtx->uContextID);
+    VbglHGCMParmUInt32Set(&Msg.type, GUEST_FILE_NOTIFYTYPE_READ_OFFSET);
+    VbglHGCMParmUInt32Set(&Msg.rc, uRc);
+    VbglHGCMParmPtrSet(&Msg.u.ReadOffset.pvData, pvData, cbData);
+    VbglHGCMParmUInt64Set(&Msg.u.ReadOffset.off64New, (uint64_t)offNew);
+
+    return VbglR3HGCMCall(&Msg.hdr, RT_UOFFSET_AFTER(HGCMReplyFileNotify, u.ReadOffset));
+}
+
+
+/**
+ * Replies to a HOST_MSG_FILE_WRITE message.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Guest control command context to use.
+ * @param   uRc                 Guest rc of operation (note: IPRT-style signed int).
+ * @param   cbWritten           Size (in bytes) of file data successfully written to guest file. Can be partial.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlFileCbWrite(PVBGLR3GUESTCTRLCMDCTX pCtx, uint32_t uRc, uint32_t cbWritten)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    HGCMReplyFileNotify Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_MSG_FILE_NOTIFY, 4);
+    VbglHGCMParmUInt32Set(&Msg.context, pCtx->uContextID);
+    VbglHGCMParmUInt32Set(&Msg.type, GUEST_FILE_NOTIFYTYPE_WRITE);
+    VbglHGCMParmUInt32Set(&Msg.rc, uRc);
+    VbglHGCMParmUInt32Set(&Msg.u.write.written, cbWritten);
+
+    return VbglR3HGCMCall(&Msg.hdr, RT_UOFFSET_AFTER(HGCMReplyFileNotify, u.write));
+}
+
+
+/**
+ * Replies to a HOST_MSG_FILE_WRITE_AT message.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Guest control command context to use.
+ * @param   uRc                 Guest rc of operation (note: IPRT-style signed int).
+ * @param   cbWritten           Size (in bytes) of file data successfully written to guest file. Can be partial.
+ * @param   offNew              New offset (in bytes) the guest file pointer points at on success.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlFileCbWriteOffset(PVBGLR3GUESTCTRLCMDCTX pCtx, uint32_t uRc, uint32_t cbWritten, int64_t offNew)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    HGCMReplyFileNotify Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_MSG_FILE_NOTIFY, 5);
+    VbglHGCMParmUInt32Set(&Msg.context, pCtx->uContextID);
+    VbglHGCMParmUInt32Set(&Msg.type, GUEST_FILE_NOTIFYTYPE_WRITE_OFFSET);
+    VbglHGCMParmUInt32Set(&Msg.rc, uRc);
+    VbglHGCMParmUInt32Set(&Msg.u.WriteOffset.cb32Written, cbWritten);
+    VbglHGCMParmUInt64Set(&Msg.u.WriteOffset.off64New, (uint64_t)offNew);
+
+    return VbglR3HGCMCall(&Msg.hdr, RT_UOFFSET_AFTER(HGCMReplyFileNotify, u.WriteOffset));
+}
+
+
+/**
+ * Replies to a HOST_MSG_FILE_SEEK message.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Guest control command context to use.
+ * @param   uRc                 Guest rc of operation (note: IPRT-style signed int).
+ * @param   offCurrent          New offset (in bytes) the guest file pointer points at on success.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlFileCbSeek(PVBGLR3GUESTCTRLCMDCTX pCtx, uint32_t uRc, uint64_t offCurrent)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    HGCMReplyFileNotify Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_MSG_FILE_NOTIFY, 4);
+    VbglHGCMParmUInt32Set(&Msg.context, pCtx->uContextID);
+    VbglHGCMParmUInt32Set(&Msg.type, GUEST_FILE_NOTIFYTYPE_SEEK);
+    VbglHGCMParmUInt32Set(&Msg.rc, uRc);
+    VbglHGCMParmUInt64Set(&Msg.u.seek.offset, offCurrent);
+
+    return VbglR3HGCMCall(&Msg.hdr, RT_UOFFSET_AFTER(HGCMReplyFileNotify, u.seek));
+}
+
+
+/**
+ * Replies to a HOST_MSG_FILE_TELL message.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Guest control command context to use.
+ * @param   uRc                 Guest rc of operation (note: IPRT-style signed int).
+ * @param   offCurrent          Current offset (in bytes) the guest file pointer points at on success.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlFileCbTell(PVBGLR3GUESTCTRLCMDCTX pCtx, uint32_t uRc, uint64_t offCurrent)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    HGCMReplyFileNotify Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_MSG_FILE_NOTIFY, 4);
+    VbglHGCMParmUInt32Set(&Msg.context, pCtx->uContextID);
+    VbglHGCMParmUInt32Set(&Msg.type, GUEST_FILE_NOTIFYTYPE_TELL);
+    VbglHGCMParmUInt32Set(&Msg.rc, uRc);
+    VbglHGCMParmUInt64Set(&Msg.u.tell.offset, offCurrent);
+
+    return VbglR3HGCMCall(&Msg.hdr, RT_UOFFSET_AFTER(HGCMReplyFileNotify, u.tell));
+}
+
+
+/**
+ * Replies to a HOST_MSG_FILE_SET_SIZE message.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Guest control command context to use.
+ * @param   uRc                 Guest rc of operation (note: IPRT-style signed int).
+ * @param   cbNew               New file size (in bytes) of the guest file on success.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlFileCbSetSize(PVBGLR3GUESTCTRLCMDCTX pCtx, uint32_t uRc, uint64_t cbNew)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    HGCMReplyFileNotify Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_MSG_FILE_NOTIFY, 4);
+    VbglHGCMParmUInt32Set(&Msg.context, pCtx->uContextID);
+    VbglHGCMParmUInt32Set(&Msg.type, GUEST_FILE_NOTIFYTYPE_SET_SIZE);
+    VbglHGCMParmUInt32Set(&Msg.rc, uRc);
+    VbglHGCMParmUInt64Set(&Msg.u.SetSize.cb64Size, cbNew);
+
+    return VbglR3HGCMCall(&Msg.hdr, RT_UOFFSET_AFTER(HGCMReplyFileNotify, u.SetSize));
+}
+
+
+/**
+ * Callback for reporting a guest process status (along with some other stuff) to the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Guest control command context to use.
+ * @param   uPID                Guest process PID to report status for.
+ * @param   uStatus             Status to report. Of type PROC_STS_XXX.
+ * @param   fFlags              Additional status flags, depending on the reported status. See RTPROCSTATUS.
+ * @param   pvData              Pointer to additional status data. Optional.
+ * @param   cbData              Size (in bytes) of additional status data.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlProcCbStatus(PVBGLR3GUESTCTRLCMDCTX pCtx,
+                                            uint32_t uPID, uint32_t uStatus, uint32_t fFlags,
+                                            void  *pvData, uint32_t cbData)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    HGCMMsgProcStatus Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_MSG_EXEC_STATUS, 5);
+    VbglHGCMParmUInt32Set(&Msg.context, pCtx->uContextID);
+    VbglHGCMParmUInt32Set(&Msg.pid, uPID);
+    VbglHGCMParmUInt32Set(&Msg.status, uStatus);
+    VbglHGCMParmUInt32Set(&Msg.flags, fFlags);
+    VbglHGCMParmPtrSet(&Msg.data, pvData, cbData);
+
+    return VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+}
+
+
+/**
+ * Sends output (from stdout/stderr) from a running process.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Guest control command context to use.
+ * @param   uPID                Guest process PID to report status for.
+ * @param   uHandle             Guest process handle the output belong to.
+ * @param   fFlags              Additional output flags.
+ * @param   pvData              Pointer to actual output data.
+ * @param   cbData              Size (in bytes) of output data.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlProcCbOutput(PVBGLR3GUESTCTRLCMDCTX pCtx,
+                                            uint32_t uPID,uint32_t uHandle, uint32_t fFlags,
+                                            void *pvData, uint32_t cbData)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    HGCMMsgProcOutput Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_MSG_EXEC_OUTPUT, 5);
+    VbglHGCMParmUInt32Set(&Msg.context, pCtx->uContextID);
+    VbglHGCMParmUInt32Set(&Msg.pid, uPID);
+    VbglHGCMParmUInt32Set(&Msg.handle, uHandle);
+    VbglHGCMParmUInt32Set(&Msg.flags, fFlags);
+    VbglHGCMParmPtrSet(&Msg.data, pvData, cbData);
+
+    return VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+}
+
+
+/**
+ * Callback for reporting back the input status of a guest process to the host.
+ *
+ * @returns VBox status code.
+ * @param   pCtx                Guest control command context to use.
+ * @param   uPID                Guest process PID to report status for.
+ * @param   uStatus             Status to report. Of type INPUT_STS_XXX.
+ * @param   fFlags              Additional input flags.
+ * @param   cbWritten           Size (in bytes) of input data handled.
+ */
+VBGLR3DECL(int) VbglR3GuestCtrlProcCbStatusInput(PVBGLR3GUESTCTRLCMDCTX pCtx,
+                                                 uint32_t uPID, uint32_t uStatus,
+                                                 uint32_t fFlags, uint32_t cbWritten)
+{
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    HGCMMsgProcStatusInput Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, pCtx->uClientID, GUEST_MSG_EXEC_INPUT_STATUS, 5);
+    VbglHGCMParmUInt32Set(&Msg.context, pCtx->uContextID);
+    VbglHGCMParmUInt32Set(&Msg.pid, uPID);
+    VbglHGCMParmUInt32Set(&Msg.status, uStatus);
+    VbglHGCMParmUInt32Set(&Msg.flags, fFlags);
+    VbglHGCMParmUInt32Set(&Msg.written, cbWritten);
+
+    return VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibGuestProp.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibGuestProp.cpp
new file mode 100644
index 00000000..106be26e
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibGuestProp.cpp
@@ -0,0 +1,1032 @@
+/* $Id: VBoxGuestR3LibGuestProp.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, guest properties.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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
+ */
+
+#if defined(VBOX_VBGLR3_XFREE86) || defined(VBOX_VBGLR3_XORG)
+# define VBOX_VBGLR3_XSERVER
+#endif
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/string.h>
+#ifndef VBOX_VBGLR3_XSERVER
+# include <iprt/mem.h>
+#endif
+#include <iprt/assert.h>
+#include <iprt/mem.h>
+#include <iprt/stdarg.h>
+#include <VBox/err.h>
+#include <VBox/log.h>
+#include <VBox/HostServices/GuestPropertySvc.h>
+
+#include "VBoxGuestR3LibInternal.h"
+
+#ifdef VBOX_VBGLR3_XFREE86
+/* Rather than try to resolve all the header file conflicts, I will just
+   prototype what we need here. */
+extern "C" char* xf86strcpy(char*,const char*);
+# undef strcpy
+# define strcpy xf86strcpy
+extern "C" void* xf86memchr(const void*,int,xf86size_t);
+# undef memchr
+# define memchr xf86memchr
+extern "C" void* xf86memset(const void*,int,xf86size_t);
+# undef memset
+# define memset xf86memset
+
+#endif /* VBOX_VBGLR3_XFREE86 */
+
+#ifdef VBOX_VBGLR3_XSERVER
+
+# undef RTStrEnd
+# define RTStrEnd xf86RTStrEnd
+
+DECLINLINE(char const *) RTStrEnd(char const *pszString, size_t cchMax)
+{
+    /* Avoid potential issues with memchr seen in glibc.
+     * See sysdeps/x86_64/memchr.S in glibc versions older than 2.11 */
+    while (cchMax > RTSTR_MEMCHR_MAX)
+    {
+        char const *pszRet = (char const *)memchr(pszString, '\0', RTSTR_MEMCHR_MAX);
+        if (RT_LIKELY(pszRet))
+            return pszRet;
+        pszString += RTSTR_MEMCHR_MAX;
+        cchMax    -= RTSTR_MEMCHR_MAX;
+    }
+    return (char const *)memchr(pszString, '\0', cchMax);
+}
+
+DECLINLINE(char *) RTStrEnd(char *pszString, size_t cchMax)
+{
+    /* Avoid potential issues with memchr seen in glibc.
+     * See sysdeps/x86_64/memchr.S in glibc versions older than 2.11 */
+    while (cchMax > RTSTR_MEMCHR_MAX)
+    {
+        char *pszRet = (char *)memchr(pszString, '\0', RTSTR_MEMCHR_MAX);
+        if (RT_LIKELY(pszRet))
+            return pszRet;
+        pszString += RTSTR_MEMCHR_MAX;
+        cchMax    -= RTSTR_MEMCHR_MAX;
+    }
+    return (char *)memchr(pszString, '\0', cchMax);
+}
+
+#endif /* VBOX_VBGLR3_XSERVER */
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+/**
+ * Structure containing information needed to enumerate through guest
+ * properties.
+ *
+ * @remarks typedef in VBoxGuestLib.h.
+ */
+struct VBGLR3GUESTPROPENUM
+{
+    /** @todo add a magic and validate the handle. */
+    /** The buffer containing the raw enumeration data */
+    char *pchBuf;
+    /** The end of the buffer */
+    char *pchBufEnd;
+    /** Pointer to the next entry to enumerate inside the buffer */
+    char *pchNext;
+};
+
+
+
+/**
+ * Connects to the guest property service.
+ *
+ * @returns VBox status code
+ * @returns VERR_NOT_SUPPORTED if guest properties are not available on the host.
+ * @param   pidClient       Where to put the client ID on success. The client ID
+ *                          must be passed to all the other calls to the service.
+ */
+VBGLR3DECL(int) VbglR3GuestPropConnect(HGCMCLIENTID *pidClient)
+{
+    int rc = VbglR3HGCMConnect("VBoxGuestPropSvc", pidClient);
+    if (rc == VERR_NOT_IMPLEMENTED || rc == VERR_HGCM_SERVICE_NOT_FOUND)
+        rc = VERR_NOT_SUPPORTED;
+    return rc;
+}
+
+
+/**
+ * Disconnect from the guest property service.
+ *
+ * @returns VBox status code.
+ * @param   idClient        The client id returned by VbglR3InfoSvcConnect().
+ */
+VBGLR3DECL(int) VbglR3GuestPropDisconnect(HGCMCLIENTID idClient)
+{
+    return VbglR3HGCMDisconnect(idClient);
+}
+
+
+/**
+ * Checks if @a pszPropName exists.
+ *
+ * @returns \c true if the guest property exists, \c false if not.
+ * @param   idClient            The HGCM client ID for the guest property session.
+ * @param   pszPropName         The property name.
+ */
+VBGLR3DECL(bool) VbglR3GuestPropExist(uint32_t idClient, const char *pszPropName)
+{
+    return RT_SUCCESS(VbglR3GuestPropReadEx(idClient, pszPropName, NULL /*ppszValue*/, NULL /* ppszFlags */, NULL /* puTimestamp */));
+}
+
+
+/**
+ * Write a property value.
+ *
+ * @returns VBox status code.
+ * @param   idClient        The client id returned by VbglR3InvsSvcConnect().
+ * @param   pszName         The property to save to.  Utf8
+ * @param   pszValue        The value to store.  Utf8.  If this is NULL then
+ *                          the property will be removed.
+ * @param   pszFlags        The flags for the property
+ */
+VBGLR3DECL(int) VbglR3GuestPropWrite(HGCMCLIENTID idClient, const char *pszName, const char *pszValue, const char *pszFlags)
+{
+    int rc;
+
+    if (pszValue != NULL)
+    {
+        GuestPropMsgSetProperty Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, idClient, GUEST_PROP_FN_SET_PROP_VALUE, 3);
+        VbglHGCMParmPtrSetString(&Msg.name,  pszName);
+        VbglHGCMParmPtrSetString(&Msg.value, pszValue);
+        VbglHGCMParmPtrSetString(&Msg.flags, pszFlags);
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    }
+    else
+    {
+        GuestPropMsgDelProperty Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, idClient, GUEST_PROP_FN_DEL_PROP, 1);
+        VbglHGCMParmPtrSetString(&Msg.name, pszName);
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    }
+    return rc;
+}
+
+
+/**
+ * Write a property value.
+ *
+ * @returns VBox status code.
+ *
+ * @param   idClient        The client id returned by VbglR3InvsSvcConnect().
+ * @param   pszName         The property to save to.  Must be valid UTF-8.
+ * @param   pszValue        The value to store.  Must be valid UTF-8.
+ *                          If this is NULL then the property will be removed.
+ *
+ * @note  if the property already exists and pszValue is not NULL then the
+ *        property's flags field will be left unchanged
+ */
+VBGLR3DECL(int) VbglR3GuestPropWriteValue(HGCMCLIENTID idClient, const char *pszName, const char *pszValue)
+{
+    int rc;
+
+    if (pszValue != NULL)
+    {
+        GuestPropMsgSetPropertyValue Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, idClient, GUEST_PROP_FN_SET_PROP_VALUE, 2);
+        VbglHGCMParmPtrSetString(&Msg.name, pszName);
+        VbglHGCMParmPtrSetString(&Msg.value, pszValue);
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    }
+    else
+    {
+        GuestPropMsgDelProperty Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.hdr, idClient, GUEST_PROP_FN_DEL_PROP, 1);
+        VbglHGCMParmPtrSetString(&Msg.name, pszName);
+        rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    }
+    return rc;
+}
+
+#ifndef VBOX_VBGLR3_XSERVER
+/**
+ * Write a property value where the value is formatted in RTStrPrintfV fashion.
+ *
+ * @returns The same as VbglR3GuestPropWriteValue with the addition of VERR_NO_STR_MEMORY.
+ *
+ * @param   idClient        The client ID returned by VbglR3InvsSvcConnect().
+ * @param   pszName         The property to save to.  Must be valid UTF-8.
+ * @param   pszValueFormat  The value format. This must be valid UTF-8 when fully formatted.
+ * @param   va              The format arguments.
+ */
+VBGLR3DECL(int) VbglR3GuestPropWriteValueV(HGCMCLIENTID idClient, const char *pszName, const char *pszValueFormat, va_list va)
+{
+    /*
+     * Format the value and pass it on to the setter.
+     */
+    int rc = VERR_NO_STR_MEMORY;
+    char *pszValue;
+    if (RTStrAPrintfV(&pszValue, pszValueFormat, va) >= 0)
+    {
+        rc = VbglR3GuestPropWriteValue(idClient, pszName, pszValue);
+        RTStrFree(pszValue);
+    }
+    return rc;
+}
+
+
+/**
+ * Write a property value where the value is formatted in RTStrPrintf fashion.
+ *
+ * @returns The same as VbglR3GuestPropWriteValue with the addition of VERR_NO_STR_MEMORY.
+ *
+ * @param   idClient        The client ID returned by VbglR3InvsSvcConnect().
+ * @param   pszName         The property to save to.  Must be valid UTF-8.
+ * @param   pszValueFormat  The value format. This must be valid UTF-8 when fully formatted.
+ * @param   ...             The format arguments.
+ */
+VBGLR3DECL(int) VbglR3GuestPropWriteValueF(HGCMCLIENTID idClient, const char *pszName, const char *pszValueFormat, ...)
+{
+    va_list va;
+    va_start(va, pszValueFormat);
+    int rc = VbglR3GuestPropWriteValueV(idClient, pszName, pszValueFormat, va);
+    va_end(va);
+    return rc;
+}
+#endif /* VBOX_VBGLR3_XSERVER */
+
+/**
+ * Retrieve a property.
+ *
+ * @returns VBox status code.
+ * @retval  VINF_SUCCESS on success, pszValue, pu64Timestamp and pszFlags
+ *          containing valid data.
+ * @retval  VERR_BUFFER_OVERFLOW if the scratch buffer @a pcBuf is not large
+ *          enough.  In this case the size needed will be placed in
+ *          @a pcbBufActual if it is not NULL.
+ * @retval  VERR_NOT_FOUND if the key wasn't found.
+ *
+ * @param   idClient        The client id returned by VbglR3GuestPropConnect().
+ * @param   pszName         The value to read.  Utf8
+ * @param   pvBuf           A scratch buffer to store the data retrieved into.
+ *                          The returned data is only valid for it's lifetime.
+ *                          @a ppszValue will point to the start of this buffer.
+ * @param   cbBuf           The size of @a pcBuf
+ * @param   ppszValue       Where to store the pointer to the value retrieved.
+ *                          Optional.
+ * @param   pu64Timestamp   Where to store the timestamp.  Optional.
+ * @param   ppszFlags       Where to store the pointer to the flags.  Optional.
+ * @param   pcbBufActual    If @a pcBuf is not large enough, the size needed.
+ *                          Optional.
+ */
+VBGLR3DECL(int) VbglR3GuestPropRead(HGCMCLIENTID idClient, const char *pszName,
+                                    void *pvBuf, uint32_t cbBuf,
+                                    char **ppszValue, uint64_t *pu64Timestamp,
+                                    char **ppszFlags,
+                                    uint32_t *pcbBufActual)
+{
+    /*
+     * Create the GET_PROP message and call the host.
+     */
+    GuestPropMsgGetProperty Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, idClient, GUEST_PROP_FN_GET_PROP, 4);
+    VbglHGCMParmPtrSetString(&Msg.name, pszName);
+    VbglHGCMParmPtrSet(&Msg.buffer, pvBuf, cbBuf);
+    VbglHGCMParmUInt64Set(&Msg.timestamp, 0);
+    VbglHGCMParmUInt32Set(&Msg.size, 0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+
+    /*
+     * The cbBufActual parameter is also returned on overflow so the call can
+     * adjust his/her buffer.
+     */
+    if (    rc == VERR_BUFFER_OVERFLOW
+        ||  pcbBufActual != NULL)
+    {
+        int rc2 = VbglHGCMParmUInt32Get(&Msg.size, pcbBufActual);
+        AssertRCReturn(rc2, RT_FAILURE(rc) ? rc : rc2);
+    }
+    if (RT_FAILURE(rc))
+        return rc;
+
+    /*
+     * Buffer layout: Value\0Flags\0.
+     *
+     * If the caller cares about any of these strings, make sure things are
+     * properly terminated (paranoia).
+     */
+    if (    RT_SUCCESS(rc)
+        &&  (ppszValue != NULL || ppszFlags != NULL))
+    {
+        /* Validate / skip 'Name'. */
+        char *pszFlags = RTStrEnd((char *)pvBuf, cbBuf) + 1;
+        AssertPtrReturn(pszFlags, VERR_TOO_MUCH_DATA);
+        if (ppszValue)
+            *ppszValue = (char *)pvBuf;
+
+        if (ppszFlags)
+        {
+            /* Validate 'Flags'. */
+            char *pszEos = RTStrEnd(pszFlags, cbBuf - (pszFlags - (char *)pvBuf));
+            AssertPtrReturn(pszEos, VERR_TOO_MUCH_DATA);
+            *ppszFlags = pszFlags;
+        }
+    }
+
+    /* And the timestamp, if requested. */
+    if (pu64Timestamp != NULL)
+    {
+        rc = VbglHGCMParmUInt64Get(&Msg.timestamp, pu64Timestamp);
+        AssertRCReturn(rc, rc);
+    }
+
+    return VINF_SUCCESS;
+}
+
+/**
+ * Reads a guest property by returning allocated values.
+ *
+ * @returns VBox status code, fully bitched.
+ *
+ * @param   idClient            The HGCM client ID for the guest property session.
+ * @param   pszPropName         The property name.
+ * @param   ppszValue           Where to return the value.  This is always set
+ *                              to NULL.  Needs to be free'd using RTStrFree().  Optional.
+ * @param   ppszFlags           Where to return the value flags.
+ *                              Needs to be free'd using RTStrFree().  Optional.
+ * @param   puTimestamp         Where to return the timestamp.  This is only set
+ *                              on success.  Optional.
+ */
+VBGLR3DECL(int) VbglR3GuestPropReadEx(uint32_t idClient,
+                                      const char *pszPropName, char **ppszValue, char **ppszFlags, uint64_t *puTimestamp)
+{
+    AssertPtrReturn(pszPropName, VERR_INVALID_POINTER);
+
+    uint32_t    cbBuf = _1K;
+    void       *pvBuf = NULL;
+    int         rc    = VINF_SUCCESS;  /* MSC can't figure out the loop */
+
+    if (ppszValue)
+        *ppszValue = NULL;
+
+    for (unsigned cTries = 0; cTries < 10; cTries++)
+    {
+        /*
+         * (Re-)Allocate the buffer and try read the property.
+         */
+        RTMemFree(pvBuf);
+        pvBuf = RTMemAlloc(cbBuf);
+        if (!pvBuf)
+        {
+            rc = VERR_NO_MEMORY;
+            break;
+        }
+        char    *pszValue;
+        char    *pszFlags;
+        uint64_t uTimestamp;
+        rc = VbglR3GuestPropRead(idClient, pszPropName, pvBuf, cbBuf, &pszValue, &uTimestamp, &pszFlags, NULL);
+        if (RT_FAILURE(rc))
+        {
+            if (rc == VERR_BUFFER_OVERFLOW)
+            {
+                /* try again with a bigger buffer. */
+                cbBuf *= 2;
+                continue;
+            }
+            break;
+        }
+
+        if (ppszValue)
+        {
+            *ppszValue = RTStrDup(pszValue);
+            if (!*ppszValue)
+            {
+                rc = VERR_NO_MEMORY;
+                break;
+            }
+        }
+
+        if (puTimestamp)
+            *puTimestamp = uTimestamp;
+        if (ppszFlags)
+            *ppszFlags = RTStrDup(pszFlags);
+        break; /* done */
+    }
+
+    if (pvBuf)
+        RTMemFree(pvBuf);
+    return rc;
+}
+
+#ifndef VBOX_VBGLR3_XSERVER
+/**
+ * Retrieve a property value, allocating space for it.
+ *
+ * @returns VBox status code.
+ * @retval  VINF_SUCCESS on success, *ppszValue containing valid data.
+ * @retval  VERR_NOT_FOUND if the key wasn't found.
+ * @retval  VERR_TOO_MUCH_DATA if we were unable to determine the right size
+ *          to allocate for the buffer.  This can happen as the result of a
+ *          race between our allocating space and the host changing the
+ *          property value.
+ *
+ * @param   idClient        The client id returned by VbglR3GuestPropConnect().
+ * @param   pszName         The value to read. Must be valid UTF-8.
+ * @param   ppszValue       Where to store the pointer to the value returned.
+ *                          This is always set to NULL or to the result, even
+ *                          on failure.
+ */
+VBGLR3DECL(int) VbglR3GuestPropReadValueAlloc(HGCMCLIENTID idClient, const char *pszName, char **ppszValue)
+{
+    /*
+     * Quick input validation.
+     */
+    AssertPtr(ppszValue);
+    *ppszValue = NULL;
+    AssertPtrReturn(pszName, VERR_INVALID_PARAMETER);
+
+    /*
+     * There is a race here between our reading the property size and the
+     * host changing the value before we read it.  Try up to ten times and
+     * report the problem if that fails.
+     */
+    char       *pszValue = NULL;
+    void       *pvBuf    = NULL;
+    uint32_t    cbBuf    = GUEST_PROP_MAX_VALUE_LEN;
+    int         rc       = VERR_BUFFER_OVERFLOW;
+    for (unsigned i = 0; i < 10 && rc == VERR_BUFFER_OVERFLOW; ++i)
+    {
+        /* We leave a bit of space here in case the maximum value is raised. */
+        cbBuf += 1024;
+        void *pvTmpBuf = RTMemRealloc(pvBuf, cbBuf);
+        if (pvTmpBuf)
+        {
+            pvBuf = pvTmpBuf;
+            rc = VbglR3GuestPropRead(idClient, pszName, pvBuf, cbBuf, &pszValue, NULL, NULL, &cbBuf);
+        }
+        else
+            rc = VERR_NO_MEMORY;
+    }
+    if (RT_SUCCESS(rc))
+    {
+        Assert(pszValue == (char *)pvBuf);
+        *ppszValue = pszValue;
+    }
+    else
+    {
+        RTMemFree(pvBuf);
+        if (rc == VERR_BUFFER_OVERFLOW)
+            /* VERR_BUFFER_OVERFLOW has a different meaning here as a
+             * return code, but we need to report the race. */
+            rc = VERR_TOO_MUCH_DATA;
+    }
+
+    return rc;
+}
+
+
+/**
+ * Free the memory used by VbglR3GuestPropReadValueAlloc for returning a
+ * value.
+ *
+ * @param pszValue   the memory to be freed.  NULL pointers will be ignored.
+ */
+VBGLR3DECL(void) VbglR3GuestPropReadValueFree(char *pszValue)
+{
+    RTMemFree(pszValue);
+}
+#endif /* VBOX_VBGLR3_XSERVER */
+
+/**
+ * Retrieve a property value, using a user-provided buffer to store it.
+ *
+ * @returns VBox status code.
+ * @retval  VINF_SUCCESS on success, pszValue containing valid data.
+ * @retval  VERR_BUFFER_OVERFLOW and the size needed in pcchValueActual if the
+ *          buffer provided was too small
+ * @retval  VERR_NOT_FOUND if the key wasn't found.
+ *
+ * @note    There is a race here between obtaining the size of the buffer
+ *          needed to hold the value and the value being updated.
+ *
+ * @param   idClient        The client id returned by VbglR3GuestPropConnect().
+ * @param   pszName         The value to read.  Utf8
+ * @param   pszValue        Where to store the value retrieved.
+ * @param   cchValue        The size of the buffer pointed to by @a pszValue
+ * @param   pcchValueActual Where to store the size of the buffer needed if
+ *                          the buffer supplied is too small.  Optional.
+ */
+VBGLR3DECL(int) VbglR3GuestPropReadValue(HGCMCLIENTID idClient, const char *pszName,
+                                         char *pszValue, uint32_t cchValue,
+                                         uint32_t *pcchValueActual)
+{
+    void *pvBuf = pszValue;
+    uint32_t cchValueActual;
+    int rc = VbglR3GuestPropRead(idClient, pszName, pvBuf, cchValue, &pszValue, NULL, NULL, &cchValueActual);
+    if (pcchValueActual != NULL)
+        *pcchValueActual = cchValueActual;
+    return rc;
+}
+
+
+#ifndef VBOX_VBGLR3_XSERVER
+/**
+ * Raw API for enumerating guest properties which match a given pattern.
+ *
+ * @returns VBox status code.
+ * @retval  VINF_SUCCESS on success and pcBuf points to a packed array
+ *          of the form \<name\>, \<value\>, \<timestamp string\>, \<flags\>,
+ *          terminated by four empty strings.  pcbBufActual will contain the
+ *          total size of the array.
+ * @retval  VERR_BUFFER_OVERFLOW if the buffer provided was too small.  In
+ *          this case pcbBufActual will contain the size of the buffer needed.
+ * @returns IPRT error code in other cases, and pchBufActual is undefined.
+ *
+ * @param   idClient      The client ID returned by VbglR3GuestPropConnect
+ * @param   pszzPatterns  A packed array of zero terminated strings, terminated
+ *                        by an empty string.
+ * @param   pcBuf         The buffer to store the results to.
+ * @param   cbBuf         The size of the buffer
+ * @param   pcbBufActual  Where to store the size of the returned data on
+ *                        success or the buffer size needed if @a pcBuf is too
+ *                        small.
+ */
+VBGLR3DECL(int) VbglR3GuestPropEnumRaw(HGCMCLIENTID idClient,
+                                       const char *pszzPatterns,
+                                       char *pcBuf,
+                                       uint32_t cbBuf,
+                                       uint32_t *pcbBufActual)
+{
+    GuestPropMsgEnumProperties Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, idClient, GUEST_PROP_FN_ENUM_PROPS, 3);
+
+    /* Get the length of the patterns array... */
+    size_t cchPatterns = 0;
+    for (size_t cchCurrent = strlen(pszzPatterns); cchCurrent != 0;
+         cchCurrent = strlen(pszzPatterns + cchPatterns))
+        cchPatterns += cchCurrent + 1;
+    /* ...including the terminator. */
+    ++cchPatterns;
+    VbglHGCMParmPtrSet(&Msg.patterns, (char *)pszzPatterns, (uint32_t)cchPatterns);
+    VbglHGCMParmPtrSet(&Msg.strings, pcBuf, cbBuf);
+    VbglHGCMParmUInt32Set(&Msg.size, 0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+    if (   pcbBufActual
+        && (    RT_SUCCESS(rc)
+            ||  rc == VERR_BUFFER_OVERFLOW))
+    {
+        int rc2 = VbglHGCMParmUInt32Get(&Msg.size, pcbBufActual);
+        if (RT_FAILURE(rc2))
+            rc = rc2;
+    }
+    return rc;
+}
+
+
+/**
+ * Start enumerating guest properties which match a given pattern.
+ *
+ * This function creates a handle which can be used to continue enumerating.
+ *
+ * @returns VBox status code.
+ * @retval  VINF_SUCCESS on success, *ppHandle points to a handle for continuing
+ *          the enumeration and *ppszName, *ppszValue, *pu64Timestamp and
+ *          *ppszFlags are set.
+ * @retval  VERR_TOO_MUCH_DATA if it was not possible to determine the amount
+ *          of local space needed to store all the enumeration data.  This is
+ *          due to a race between allocating space and the host adding new
+ *          data, so retrying may help here.  Other parameters are left
+ *          uninitialised
+ *
+ * @param   idClient        The client id returned by VbglR3InfoSvcConnect().
+ * @param   papszPatterns   The patterns against which the properties are
+ *                          matched.  Pass NULL if everything should be matched.
+ * @param   cPatterns       The number of patterns in @a papszPatterns.  0 means
+ *                          match everything.
+ * @param   ppHandle        where the handle for continued enumeration is stored
+ *                          on success.  This must be freed with
+ *                          VbglR3GuestPropEnumFree when it is no longer needed.
+ * @param   ppszName        Where to store the next property name.  This will be
+ *                          set to NULL if there are no more properties to
+ *                          enumerate.  This pointer should not be freed. Optional.
+ * @param   ppszValue       Where to store the next property value.  This will be
+ *                          set to NULL if there are no more properties to
+ *                          enumerate.  This pointer should not be freed. Optional.
+ * @param   pu64Timestamp   Where to store the next property timestamp.  This
+ *                          will be set to zero if there are no more properties
+ *                          to enumerate. Optional.
+ * @param   ppszFlags       Where to store the next property flags.  This will be
+ *                          set to NULL if there are no more properties to
+ *                          enumerate.  This pointer should not be freed. Optional.
+ *
+ * @remarks While all output parameters are optional, you need at least one to
+ *          figure out when to stop.
+ */
+VBGLR3DECL(int) VbglR3GuestPropEnum(HGCMCLIENTID idClient,
+                                    char const * const *papszPatterns,
+                                    uint32_t cPatterns,
+                                    PVBGLR3GUESTPROPENUM *ppHandle,
+                                    char const **ppszName,
+                                    char const **ppszValue,
+                                    uint64_t *pu64Timestamp,
+                                    char const **ppszFlags)
+{
+    /* Create the handle. */
+    PVBGLR3GUESTPROPENUM pHandle = (PVBGLR3GUESTPROPENUM)RTMemAllocZ(sizeof(VBGLR3GUESTPROPENUM));
+    if (RT_LIKELY(pHandle))
+    {/* likely */}
+    else
+        return VERR_NO_MEMORY;
+
+    /* Get the length of the pattern string, including the final terminator. */
+    size_t cbPatterns = 1;
+    for (uint32_t i = 0; i < cPatterns; ++i)
+        cbPatterns += strlen(papszPatterns[i]) + 1;
+
+    /* Pack the pattern array. */
+    char *pszzPatterns = (char *)RTMemAlloc(cbPatterns);
+    size_t off = 0;
+    for (uint32_t i = 0; i < cPatterns; ++i)
+    {
+        size_t cb = strlen(papszPatterns[i]) + 1;
+        memcpy(&pszzPatterns[off], papszPatterns[i], cb);
+        off += cb;
+    }
+    pszzPatterns[off] = '\0';
+
+    /* In reading the guest property data we are racing against the host
+     * adding more of it, so loop a few times and retry on overflow. */
+    uint32_t cbBuf  = 4096; /* picked out of thin air */
+    char    *pchBuf = NULL;
+    int      rc     = VINF_SUCCESS;
+    for (int i = 0; i < 10; ++i)
+    {
+        void *pvNew = RTMemRealloc(pchBuf, cbBuf);
+        if (pvNew)
+            pchBuf = (char *)pvNew;
+        else
+        {
+            rc = VERR_NO_MEMORY;
+            break;
+        }
+        rc = VbglR3GuestPropEnumRaw(idClient, pszzPatterns, pchBuf, cbBuf, &cbBuf);
+        if (rc != VERR_BUFFER_OVERFLOW)
+            break;
+        cbBuf += 4096;  /* Just to increase our chances */
+    }
+    RTMemFree(pszzPatterns);
+    if (RT_SUCCESS(rc))
+    {
+        /*
+         * Complete the handle and call VbglR3GuestPropEnumNext to retrieve the first entry.
+         */
+        pHandle->pchNext   = pchBuf;
+        pHandle->pchBuf    = pchBuf;
+        pHandle->pchBufEnd = pchBuf + cbBuf;
+
+        const char *pszNameTmp;
+        if (!ppszName)
+            ppszName = &pszNameTmp;
+        rc = VbglR3GuestPropEnumNext(pHandle, ppszName, ppszValue, pu64Timestamp, ppszFlags);
+        if (RT_SUCCESS(rc))
+        {
+            *ppHandle = pHandle;
+            return rc;
+        }
+    }
+    else if (rc == VERR_BUFFER_OVERFLOW)
+        rc = VERR_TOO_MUCH_DATA;
+    RTMemFree(pchBuf);
+    RTMemFree(pHandle);
+    return rc;
+}
+
+
+/**
+ * Get the next guest property.
+ *
+ * See @a VbglR3GuestPropEnum.
+ *
+ * @returns VBox status code.
+ *
+ * @param  pHandle       Handle obtained from @a VbglR3GuestPropEnum.
+ * @param  ppszName      Where to store the next property name.  This will be
+ *                       set to NULL if there are no more properties to
+ *                       enumerate.  This pointer should not be freed. Optional.
+ * @param  ppszValue     Where to store the next property value.  This will be
+ *                       set to NULL if there are no more properties to
+ *                       enumerate.  This pointer should not be freed. Optional.
+ * @param  pu64Timestamp Where to store the next property timestamp.  This
+ *                       will be set to zero if there are no more properties
+ *                       to enumerate. Optional.
+ * @param  ppszFlags     Where to store the next property flags.  This will be
+ *                       set to NULL if there are no more properties to
+ *                       enumerate.  This pointer should not be freed. Optional.
+ *
+ * @remarks While all output parameters are optional, you need at least one to
+ *          figure out when to stop.
+ */
+VBGLR3DECL(int) VbglR3GuestPropEnumNext(PVBGLR3GUESTPROPENUM pHandle,
+                                        char const **ppszName,
+                                        char const **ppszValue,
+                                        uint64_t *pu64Timestamp,
+                                        char const **ppszFlags)
+{
+    /*
+     * The VBGLR3GUESTPROPENUM structure contains a buffer containing the raw
+     * properties data and a pointer into the buffer which tracks how far we
+     * have parsed so far.  The buffer contains packed strings in groups of
+     * four - name, value, timestamp (as a decimal string) and flags.  It is
+     * terminated by four empty strings.  We can rely on this layout unless
+     * the caller has been poking about in the structure internals, in which
+     * case they must take responsibility for the results.
+     *
+     * Layout:
+     *   Name\0Value\0Timestamp\0Flags\0
+     */
+    char *pchNext = pHandle->pchNext;       /* The cursor. */
+    char *pchEnd  = pHandle->pchBufEnd;     /* End of buffer, for size calculations. */
+
+    char *pszName      = pchNext;
+    char *pszValue     = pchNext = RTStrEnd(pchNext, pchEnd - pchNext) + 1;
+    AssertPtrReturn(pchNext, VERR_PARSE_ERROR);  /* 0x1 is also an invalid pointer :) */
+
+    char *pszTimestamp = pchNext = RTStrEnd(pchNext, pchEnd - pchNext) + 1;
+    AssertPtrReturn(pchNext, VERR_PARSE_ERROR);
+
+    char *pszFlags     = pchNext = RTStrEnd(pchNext, pchEnd - pchNext) + 1;
+    AssertPtrReturn(pchNext, VERR_PARSE_ERROR);
+
+    /*
+     * Don't move the index pointer if we found the terminating "\0\0\0\0" entry.
+     * Don't try convert the timestamp either.
+     */
+    uint64_t u64Timestamp;
+    if (*pszName != '\0')
+    {
+        pchNext = RTStrEnd(pchNext, pchEnd - pchNext) + 1;
+        AssertPtrReturn(pchNext, VERR_PARSE_ERROR);
+
+        /* Convert the timestamp string into a number. */
+        int rc = RTStrToUInt64Full(pszTimestamp, 0, &u64Timestamp);
+        AssertRCSuccessReturn(rc, VERR_PARSE_ERROR);
+
+        pHandle->pchNext = pchNext;
+        AssertPtr(pchNext);
+    }
+    else
+    {
+        u64Timestamp = 0;
+        AssertMsgReturn(!*pszValue && !*pszTimestamp && !*pszFlags,
+                        ("'%s' '%s' '%s'\n", pszValue, pszTimestamp, pszFlags),
+                        VERR_PARSE_ERROR);
+    }
+
+    /*
+     * Everything is fine, set the return values.
+     */
+    if (ppszName)
+        *ppszName  = *pszName  != '\0' ? pszName  : NULL;
+    if (ppszValue)
+        *ppszValue = *pszValue != '\0' ? pszValue : NULL;
+    if (pu64Timestamp)
+        *pu64Timestamp = u64Timestamp;
+    if (ppszFlags)
+        *ppszFlags = *pszFlags != '\0' ? pszFlags : NULL;
+    return VINF_SUCCESS;
+}
+
+
+/**
+ * Free an enumeration handle returned by @a VbglR3GuestPropEnum.
+ * @param pHandle the handle to free
+ */
+VBGLR3DECL(void) VbglR3GuestPropEnumFree(PVBGLR3GUESTPROPENUM pHandle)
+{
+    if (!pHandle)
+        return;
+    RTMemFree(pHandle->pchBuf);
+    RTMemFree(pHandle);
+}
+
+
+/**
+ * Deletes a guest property.
+ *
+ * @returns VBox status code.
+ * @param   idClient        The client id returned by VbglR3InvsSvcConnect().
+ * @param   pszName         The property to delete.  Utf8
+ */
+VBGLR3DECL(int) VbglR3GuestPropDelete(HGCMCLIENTID idClient, const char *pszName)
+{
+    AssertPtrReturn(pszName,  VERR_INVALID_POINTER);
+
+    GuestPropMsgDelProperty Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.hdr, idClient, GUEST_PROP_FN_DEL_PROP, 1);
+    VbglHGCMParmPtrSetString(&Msg.name, pszName);
+    return VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+}
+
+
+/**
+ * Deletes a set of keys.
+ *
+ * The set is specified in the same way as for VbglR3GuestPropEnum.
+ *
+ * @returns VBox status code. Stops on first failure.
+ *          See also VbglR3GuestPropEnum.
+ *
+ * @param   idClient        The client id returned by VbglR3InfoSvcConnect().
+ * @param   papszPatterns   The patterns against which the properties are
+ *                          matched.  Pass NULL if everything should be matched.
+ * @param   cPatterns       The number of patterns in @a papszPatterns.  0 means
+ *                          match everything.
+ */
+VBGLR3DECL(int) VbglR3GuestPropDelSet(HGCMCLIENTID idClient,
+                                      const char * const *papszPatterns,
+                                      uint32_t cPatterns)
+{
+    PVBGLR3GUESTPROPENUM pHandle;
+    char const *pszName, *pszValue, *pszFlags;
+    uint64_t pu64Timestamp;
+    int rc = VbglR3GuestPropEnum(idClient,
+                                 (char **)papszPatterns, /** @todo fix this cast. */
+                                 cPatterns,
+                                 &pHandle,
+                                 &pszName,
+                                 &pszValue,
+                                 &pu64Timestamp,
+                                 &pszFlags);
+
+    while (RT_SUCCESS(rc) && pszName)
+    {
+        rc = VbglR3GuestPropWriteValue(idClient, pszName, NULL);
+        if (RT_FAILURE(rc))
+            break;
+
+        rc = VbglR3GuestPropEnumNext(pHandle,
+                                     &pszName,
+                                     &pszValue,
+                                     &pu64Timestamp,
+                                     &pszFlags);
+    }
+
+    VbglR3GuestPropEnumFree(pHandle);
+    return rc;
+}
+
+
+/**
+ * Wait for notification of changes to a guest property.  If this is called in
+ * a loop, the timestamp of the last notification seen can be passed as a
+ * parameter to be sure that no notifications are missed.
+ *
+ * @returns VBox status code.
+ * @retval  VINF_SUCCESS on success, @a ppszName, @a ppszValue,
+ *          @a pu64Timestamp and @a ppszFlags containing valid data.
+ * @retval  VINF_NOT_FOUND if no previous notification could be found with the
+ *          timestamp supplied.  This will normally mean that a large number
+ *          of notifications occurred in between.
+ * @retval  VERR_BUFFER_OVERFLOW if the scratch buffer @a pvBuf is not large
+ *          enough.  In this case the size needed will be placed in
+ *          @a pcbBufActual if it is not NULL.
+ * @retval  VERR_TIMEOUT if a timeout occurred before a notification was seen.
+ *
+ * @param   idClient        The client id returned by VbglR3GuestPropConnect().
+ * @param   pszPatterns     The patterns that the property names must matchfor
+ *                          the change to be reported.
+ * @param   pvBuf           A scratch buffer to store the data retrieved into.
+ *                          The returned data is only valid for it's lifetime.
+ *                          @a ppszValue will point to the start of this buffer.
+ * @param   cbBuf           The size of @a pvBuf
+ * @param   u64Timestamp    The timestamp of the last event seen.  Pass zero
+ *                          to wait for the next event.
+ * @param   cMillies        Timeout in milliseconds.  Use RT_INDEFINITE_WAIT
+ *                          to wait indefinitely.
+ * @param   ppszName        Where to store the pointer to the name retrieved.
+ *                          Optional.
+ * @param   ppszValue       Where to store the pointer to the value retrieved.
+ *                          Optional.
+ * @param   pu64Timestamp   Where to store the timestamp.  Optional.
+ * @param   ppszFlags       Where to store the pointer to the flags.  Optional.
+ * @param   pcbBufActual    If @a pcBuf is not large enough, the size needed.
+ *                          Optional.
+ * @param   pfWasDeleted    A flag which indicates that property was deleted.
+ *                          Optional.
+ */
+VBGLR3DECL(int) VbglR3GuestPropWait(HGCMCLIENTID idClient,
+                                    const char *pszPatterns,
+                                    void *pvBuf, uint32_t cbBuf,
+                                    uint64_t u64Timestamp, uint32_t cMillies,
+                                    char ** ppszName, char **ppszValue,
+                                    uint64_t *pu64Timestamp, char **ppszFlags,
+                                    uint32_t *pcbBufActual, bool *pfWasDeleted)
+{
+    /*
+     * Create the GET_NOTIFICATION message and call the host.
+     */
+    GuestPropMsgGetNotification Msg;
+    VBGL_HGCM_HDR_INIT_TIMED(&Msg.hdr, idClient, GUEST_PROP_FN_GET_NOTIFICATION, 4, cMillies);
+
+    VbglHGCMParmPtrSetString(&Msg.patterns, pszPatterns);
+    RT_BZERO(pvBuf, cbBuf);
+    VbglHGCMParmPtrSet(&Msg.buffer, pvBuf, cbBuf);
+    VbglHGCMParmUInt64Set(&Msg.timestamp, u64Timestamp);
+    VbglHGCMParmUInt32Set(&Msg.size, 0);
+
+    int rc = VbglR3HGCMCall(&Msg.hdr, sizeof(Msg));
+
+    /*
+     * The cbBufActual parameter is also returned on overflow so the caller can
+     * adjust their buffer.
+     */
+    if (    rc == VERR_BUFFER_OVERFLOW
+        &&  pcbBufActual != NULL)
+    {
+        int rc2 = Msg.size.GetUInt32(pcbBufActual);
+        AssertRCReturn(rc2, RT_FAILURE(rc) ? rc : rc2);
+    }
+    if (RT_FAILURE(rc))
+        return rc;
+
+    /*
+     * Buffer layout: Name\0Value\0Flags\0fWasDeleted\0.
+     *
+     * If the caller cares about any of these strings, make sure things are
+     * properly terminated (paranoia).
+     */
+    if (    RT_SUCCESS(rc)
+        &&  (ppszName != NULL || ppszValue != NULL || ppszFlags != NULL || pfWasDeleted != NULL))
+    {
+        /* Validate / skip 'Name'. */
+        char *pszValue = RTStrEnd((char *)pvBuf, cbBuf) + 1;
+        AssertPtrReturn(pszValue, VERR_TOO_MUCH_DATA);
+        if (ppszName)
+            *ppszName = (char *)pvBuf;
+
+        /* Validate / skip 'Value'. */
+        char *pszFlags = RTStrEnd(pszValue, cbBuf - (pszValue - (char *)pvBuf)) + 1;
+        AssertPtrReturn(pszFlags, VERR_TOO_MUCH_DATA);
+        if (ppszValue)
+            *ppszValue = pszValue;
+
+        if (ppszFlags)
+            *ppszFlags = pszFlags;
+
+        /* Skip 'Flags' and deal with 'fWasDeleted' if it's present. */
+        char *pszWasDeleted = RTStrEnd(pszFlags, cbBuf - (pszFlags - (char *)pvBuf)) + 1;
+        AssertPtrReturn(pszWasDeleted, VERR_TOO_MUCH_DATA);
+        char chWasDeleted = 0;
+        if (   (size_t)pszWasDeleted - (size_t)pvBuf < cbBuf
+            && (chWasDeleted = *pszWasDeleted) != '\0')
+            AssertMsgReturn((chWasDeleted == '0' || chWasDeleted == '1') && pszWasDeleted[1] == '\0',
+                            ("'%s'\n", pszWasDeleted), VERR_PARSE_ERROR);
+        if (pfWasDeleted)
+            *pfWasDeleted = chWasDeleted == '1';
+    }
+
+    /* And the timestamp, if requested. */
+    if (pu64Timestamp != NULL)
+    {
+        rc = Msg.timestamp.GetUInt64(pu64Timestamp);
+        AssertRCReturn(rc, rc);
+    }
+
+    return VINF_SUCCESS;
+}
+#endif /* VBOX_VBGLR3_XSERVER */
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibGuestUser.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibGuestUser.cpp
new file mode 100644
index 00000000..afa280fa
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibGuestUser.cpp
@@ -0,0 +1,119 @@
+/* $Id: VBoxGuestR3LibGuestUser.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions,
+ *                  guest user reporting / utility functions.
+ */
+
+/*
+ * 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 <iprt/assert.h>
+#include <VBox/log.h>
+#include <iprt/errcore.h>
+#include <iprt/mem.h>
+#include <iprt/string.h>
+
+#include "VBoxGuestR3LibInternal.h"
+
+
+/**
+ * Reports a state change of a specific guest user.
+ *
+ * @returns IPRT status value
+ * @param   pszUser         Guest user name to report state for.
+ * @param   pszDomain       Domain the guest user's account is bound to.
+ * @param   enmState        Guest user state to report.
+ * @param   puDetails       Pointer to state details. Optional.
+ * @param   cbDetails       Size (in bytes) of state details. Pass 0
+ *                          if puDetails is NULL.
+ */
+VBGLR3DECL(int) VbglR3GuestUserReportState(const char *pszUser, const char *pszDomain, VBoxGuestUserState enmState,
+                                           uint8_t *puDetails, uint32_t cbDetails)
+{
+    AssertPtrReturn(pszUser, VERR_INVALID_POINTER);
+    /* pszDomain is optional. */
+    /* puDetails is optional. */
+    AssertReturn(cbDetails == 0 || puDetails != NULL, VERR_INVALID_PARAMETER);
+    AssertReturn(cbDetails < 16U*_1M, VERR_OUT_OF_RANGE);
+
+    uint32_t cbBase   = sizeof(VMMDevReportGuestUserState);
+    uint32_t cbUser   = (uint32_t)strlen(pszUser) + 1; /* Include terminating zero */
+    uint32_t cbDomain = pszDomain ? (uint32_t)strlen(pszDomain) + 1 /* Ditto */ : 0;
+
+    /* Allocate enough space for all fields. */
+    uint32_t cbSize = cbBase
+                    + cbUser
+                    + cbDomain
+                    + cbDetails;
+    VMMDevReportGuestUserState *pReport = (VMMDevReportGuestUserState *)RTMemAllocZ(cbSize);
+    if (!pReport)
+        return VERR_NO_MEMORY;
+
+    int rc = vmmdevInitRequest(&pReport->header, VMMDevReq_ReportGuestUserState);
+    if (RT_SUCCESS(rc))
+    {
+        pReport->header.size      = cbSize;
+
+        pReport->status.state     = enmState;
+        pReport->status.cbUser    = cbUser;
+        pReport->status.cbDomain  = cbDomain;
+        pReport->status.cbDetails = cbDetails;
+
+        /*
+         * Note: cbOffDynamic contains the first dynamic array entry within
+         *       VBoxGuestUserStatus.
+         *       Therefore it's vital to *not* change the order of the struct members
+         *       without altering this code. Don't try this at home.
+         */
+        uint32_t cbOffDynamic = RT_UOFFSETOF(VBoxGuestUserStatus, szUser);
+
+        /* pDynamic marks the beginning for the dynamically allocated areas. */
+        uint8_t *pDynamic = (uint8_t *)&pReport->status;
+        pDynamic += cbOffDynamic;
+        AssertPtr(pDynamic);
+
+        memcpy(pDynamic, pszUser, cbUser);
+        if (cbDomain)
+            memcpy(pDynamic + cbUser, pszDomain, cbDomain);
+        if (cbDetails)
+            memcpy(pDynamic + cbUser + cbDomain, puDetails, cbDetails);
+
+        rc = vbglR3GRPerform(&pReport->header);
+    }
+
+    RTMemFree(pReport);
+    return rc;
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibHGCM.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibHGCM.cpp
new file mode 100644
index 00000000..8053f0be
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibHGCM.cpp
@@ -0,0 +1,108 @@
+/* $Id: VBoxGuestR3LibHGCM.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions,
+ * generic HGCM.
+ */
+
+/*
+ * Copyright (C) 2015-2023 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 "VBoxGuestR3LibInternal.h"
+#include <VBox/VBoxGuestLib.h>
+#include <iprt/string.h>
+
+
+/**
+ * Connects to an HGCM service.
+ *
+ * @returns VBox status code
+ * @param   pszServiceName  Name of the host service.
+ * @param   pidClient       Where to put the client ID on success. The client ID
+ *                          must be passed to all the other calls to the service.
+ */
+VBGLR3DECL(int) VbglR3HGCMConnect(const char *pszServiceName, HGCMCLIENTID *pidClient)
+{
+    AssertPtrReturn(pszServiceName, VERR_INVALID_POINTER);
+    AssertPtrReturn(pidClient,      VERR_INVALID_POINTER);
+
+    VBGLIOCHGCMCONNECT Info;
+    RT_ZERO(Info);
+    VBGLREQHDR_INIT(&Info.Hdr, HGCM_CONNECT);
+    Info.u.In.Loc.type = VMMDevHGCMLoc_LocalHost_Existing;
+    int rc = RTStrCopy(Info.u.In.Loc.u.host.achName, sizeof(Info.u.In.Loc.u.host.achName), pszServiceName);
+    if (RT_FAILURE(rc))
+        return rc;
+    rc = vbglR3DoIOCtl(VBGL_IOCTL_HGCM_CONNECT, &Info.Hdr, sizeof(Info));
+    if (RT_SUCCESS(rc))
+        *pidClient = Info.u.Out.idClient;
+    return rc;
+}
+
+
+/**
+ * Disconnect from an HGCM service.
+ *
+ * @returns VBox status code.
+ * @param   idClient        The client id returned by VbglR3HGCMConnect().
+ */
+VBGLR3DECL(int) VbglR3HGCMDisconnect(HGCMCLIENTID idClient)
+{
+    VBGLIOCHGCMDISCONNECT Info;
+    VBGLREQHDR_INIT(&Info.Hdr, HGCM_DISCONNECT);
+    Info.u.In.idClient = idClient;
+
+    return vbglR3DoIOCtl(VBGL_IOCTL_HGCM_DISCONNECT, &Info.Hdr, sizeof(Info));
+}
+
+
+/**
+ * Makes a fully prepared HGCM call.
+ *
+ * @returns VBox status code.
+ * @param   pInfo           Fully prepared HGCM call info.
+ * @param   cbInfo          Size of the info.  This may sometimes be larger than
+ *                          what the parameter count indicates because of
+ *                          parameter changes between versions and such.
+ */
+VBGLR3DECL(int) VbglR3HGCMCall(PVBGLIOCHGCMCALL pInfo, size_t cbInfo)
+{
+    /* Expect caller to have filled in pInfo. */
+    AssertMsg(pInfo->Hdr.cbIn  == cbInfo, ("cbIn=%#x cbInfo=%#zx\n", pInfo->Hdr.cbIn, cbInfo));
+    AssertMsg(pInfo->Hdr.cbOut == cbInfo, ("cbOut=%#x cbInfo=%#zx\n", pInfo->Hdr.cbOut, cbInfo));
+    Assert(sizeof(*pInfo) + pInfo->cParms * sizeof(HGCMFunctionParameter) <= cbInfo);
+    Assert(pInfo->u32ClientID != 0);
+
+    return vbglR3DoIOCtl(VBGL_IOCTL_HGCM_CALL(cbInfo), &pInfo->Hdr, cbInfo);
+}
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibHostChannel.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibHostChannel.cpp
new file mode 100644
index 00000000..9c9e377e
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibHostChannel.cpp
@@ -0,0 +1,235 @@
+/* $Id: VBoxGuestR3LibHostChannel.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, Host Channel.
+ */
+
+/*
+ * 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
+ */
+
+
+#include <iprt/mem.h>
+
+#include <VBox/HostServices/VBoxHostChannel.h>
+
+#include "VBoxGuestR3LibInternal.h"
+
+
+VBGLR3DECL(int) VbglR3HostChannelInit(uint32_t *pidClient)
+{
+    return VbglR3HGCMConnect("VBoxHostChannel", pidClient);
+}
+
+VBGLR3DECL(void) VbglR3HostChannelTerm(uint32_t idClient)
+{
+    VbglR3HGCMDisconnect(idClient);
+}
+
+VBGLR3DECL(int) VbglR3HostChannelAttach(uint32_t *pu32ChannelHandle,
+                                        uint32_t u32HGCMClientId,
+                                        const char *pszName,
+                                        uint32_t u32Flags)
+{
+    /* Make a heap copy of the name, because HGCM can not use some of other memory types. */
+    size_t cbName = strlen(pszName) + 1;
+    char *pszCopy = (char *)RTMemAlloc(cbName);
+    if (pszCopy == NULL)
+    {
+        return VERR_NO_MEMORY;
+    }
+
+    memcpy(pszCopy, pszName, cbName);
+
+    VBoxHostChannelAttach parms;
+    VBGL_HGCM_HDR_INIT(&parms.hdr, u32HGCMClientId, VBOX_HOST_CHANNEL_FN_ATTACH, 3);
+    VbglHGCMParmPtrSet(&parms.name, pszCopy, (uint32_t)cbName);
+    VbglHGCMParmUInt32Set(&parms.flags, u32Flags);
+    VbglHGCMParmUInt32Set(&parms.handle, 0);
+
+    int rc = VbglR3HGCMCall(&parms.hdr, sizeof(parms));
+
+    if (RT_SUCCESS(rc))
+        *pu32ChannelHandle = parms.handle.u.value32;
+
+    RTMemFree(pszCopy);
+
+    return rc;
+}
+
+VBGLR3DECL(void) VbglR3HostChannelDetach(uint32_t u32ChannelHandle,
+                                         uint32_t u32HGCMClientId)
+{
+    VBoxHostChannelDetach parms;
+    VBGL_HGCM_HDR_INIT(&parms.hdr, u32HGCMClientId, VBOX_HOST_CHANNEL_FN_DETACH, 1);
+    VbglHGCMParmUInt32Set(&parms.handle, u32ChannelHandle);
+
+    VbglR3HGCMCall(&parms.hdr, sizeof(parms));
+}
+
+VBGLR3DECL(int) VbglR3HostChannelSend(uint32_t u32ChannelHandle,
+                                      uint32_t u32HGCMClientId,
+                                      void *pvData,
+                                      uint32_t cbData)
+{
+    VBoxHostChannelSend parms;
+    VBGL_HGCM_HDR_INIT(&parms.hdr, u32HGCMClientId, VBOX_HOST_CHANNEL_FN_SEND, 2);
+    VbglHGCMParmUInt32Set(&parms.handle, u32ChannelHandle);
+    VbglHGCMParmPtrSet(&parms.data, pvData, cbData);
+
+    return VbglR3HGCMCall(&parms.hdr, sizeof(parms));
+}
+
+VBGLR3DECL(int) VbglR3HostChannelRecv(uint32_t u32ChannelHandle,
+                                      uint32_t u32HGCMClientId,
+                                      void *pvData,
+                                      uint32_t cbData,
+                                      uint32_t *pu32SizeReceived,
+                                      uint32_t *pu32SizeRemaining)
+{
+    VBoxHostChannelRecv parms;
+    VBGL_HGCM_HDR_INIT(&parms.hdr, u32HGCMClientId, VBOX_HOST_CHANNEL_FN_RECV, 4);
+    VbglHGCMParmUInt32Set(&parms.handle, u32ChannelHandle);
+    VbglHGCMParmPtrSet(&parms.data, pvData, cbData);
+    VbglHGCMParmUInt32Set(&parms.sizeReceived, 0);
+    VbglHGCMParmUInt32Set(&parms.sizeRemaining, 0);
+
+    int rc = VbglR3HGCMCall(&parms.hdr, sizeof(parms));
+
+    if (RT_SUCCESS(rc))
+    {
+        *pu32SizeReceived = parms.sizeReceived.u.value32;
+        *pu32SizeRemaining = parms.sizeRemaining.u.value32;
+    }
+
+    return rc;
+}
+
+VBGLR3DECL(int) VbglR3HostChannelControl(uint32_t u32ChannelHandle,
+                                         uint32_t u32HGCMClientId,
+                                         uint32_t u32Code,
+                                         void *pvParm,
+                                         uint32_t cbParm,
+                                         void *pvData,
+                                         uint32_t cbData,
+                                         uint32_t *pu32SizeDataReturned)
+{
+    VBoxHostChannelControl parms;
+    VBGL_HGCM_HDR_INIT(&parms.hdr, u32HGCMClientId, VBOX_HOST_CHANNEL_FN_CONTROL, 5);
+    VbglHGCMParmUInt32Set(&parms.handle, u32ChannelHandle);
+    VbglHGCMParmUInt32Set(&parms.code, u32Code);
+    VbglHGCMParmPtrSet(&parms.parm, pvParm, cbParm);
+    VbglHGCMParmPtrSet(&parms.data, pvData, cbData);
+    VbglHGCMParmUInt32Set(&parms.sizeDataReturned, 0);
+
+    int rc = VbglR3HGCMCall(&parms.hdr, sizeof(parms));
+
+    if (RT_SUCCESS(rc))
+    {
+        *pu32SizeDataReturned = parms.sizeDataReturned.u.value32;
+    }
+
+    return rc;
+}
+
+VBGLR3DECL(int) VbglR3HostChannelEventWait(uint32_t *pu32ChannelHandle,
+                                           uint32_t u32HGCMClientId,
+                                           uint32_t *pu32EventId,
+                                           void *pvParm,
+                                           uint32_t cbParm,
+                                           uint32_t *pu32SizeReturned)
+{
+    VBoxHostChannelEventWait parms;
+    VBGL_HGCM_HDR_INIT(&parms.hdr, u32HGCMClientId, VBOX_HOST_CHANNEL_FN_EVENT_WAIT, 4);
+    VbglHGCMParmUInt32Set(&parms.handle, 0);
+    VbglHGCMParmUInt32Set(&parms.id, 0);
+    VbglHGCMParmPtrSet(&parms.parm, pvParm, cbParm);
+    VbglHGCMParmUInt32Set(&parms.sizeReturned, 0);
+
+    int rc = VbglR3HGCMCall(&parms.hdr, sizeof(parms));
+
+    if (RT_SUCCESS(rc))
+    {
+        *pu32ChannelHandle = parms.handle.u.value32;
+        *pu32EventId = parms.id.u.value32;
+        *pu32SizeReturned = parms.sizeReturned.u.value32;
+    }
+
+    return rc;
+}
+
+VBGLR3DECL(int) VbglR3HostChannelEventCancel(uint32_t u32ChannelHandle,
+                                             uint32_t u32HGCMClientId)
+{
+    RT_NOREF1(u32ChannelHandle);
+
+    VBoxHostChannelEventCancel parms;
+    VBGL_HGCM_HDR_INIT(&parms.hdr, u32HGCMClientId, VBOX_HOST_CHANNEL_FN_EVENT_CANCEL, 0);
+
+    return VbglR3HGCMCall(&parms.hdr, sizeof(parms));
+}
+
+VBGLR3DECL(int) VbglR3HostChannelQuery(const char *pszName,
+                                       uint32_t u32HGCMClientId,
+                                       uint32_t u32Code,
+                                       void *pvParm,
+                                       uint32_t cbParm,
+                                       void *pvData,
+                                       uint32_t cbData,
+                                       uint32_t *pu32SizeDataReturned)
+{
+    /* Make a heap copy of the name, because HGCM can not use some of other memory types. */
+    size_t cbName = strlen(pszName) + 1;
+    char *pszCopy = (char *)RTMemAlloc(cbName);
+    if (pszCopy == NULL)
+    {
+        return VERR_NO_MEMORY;
+    }
+
+    memcpy(pszCopy, pszName, cbName);
+
+    VBoxHostChannelQuery parms;
+    VBGL_HGCM_HDR_INIT(&parms.hdr, u32HGCMClientId, VBOX_HOST_CHANNEL_FN_QUERY, 5);
+    VbglHGCMParmPtrSet(&parms.name, pszCopy, (uint32_t)cbName);
+    VbglHGCMParmUInt32Set(&parms.code, u32Code);
+    VbglHGCMParmPtrSet(&parms.parm, pvParm, cbParm);
+    VbglHGCMParmPtrSet(&parms.data, pvData, cbData);
+    VbglHGCMParmUInt32Set(&parms.sizeDataReturned, 0);
+
+    int rc = VbglR3HGCMCall(&parms.hdr, sizeof(parms));
+
+    if (RT_SUCCESS(rc))
+    {
+        *pu32SizeDataReturned = parms.sizeDataReturned.u.value32;
+    }
+
+    RTMemFree(pszCopy);
+
+    return rc;
+}
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibHostVersion.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibHostVersion.cpp
new file mode 100644
index 00000000..f3d7740f
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibHostVersion.cpp
@@ -0,0 +1,226 @@
+/* $Id: */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, host version check.
+ */
+
+/*
+ * 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 <iprt/string.h>
+#include <VBox/log.h>
+
+#ifdef RT_OS_WINDOWS
+ #define WIN32_LEAN_AND_MEAN
+ #include <iprt/win/windows.h>
+#endif
+
+#include "VBoxGuestR3LibInternal.h"
+
+
+/**
+ * Checks for a Guest Additions update by comparing the installed version on the
+ * guest and the reported host version.
+ *
+ * @returns VBox status code
+ *
+ * @param   idClient            The client id returned by
+ *                              VbglR3InfoSvcConnect().
+ * @param   pfUpdate            Receives pointer to boolean flag indicating
+ *                              whether an update was found or not.
+ * @param   ppszHostVersion     Receives pointer of allocated version string.
+ *                              The returned pointer must be freed using
+ *                              VbglR3GuestPropReadValueFree().  Always set to
+ *                              NULL.
+ * @param   ppszGuestVersion    Receives pointer of allocated revision string.
+ *                              The returned pointer must be freed using
+ *                              VbglR3GuestPropReadValueFree().  Always set to
+ *                              NULL.
+ */
+VBGLR3DECL(int) VbglR3HostVersionCheckForUpdate(HGCMCLIENTID idClient, bool *pfUpdate, char **ppszHostVersion, char **ppszGuestVersion)
+{
+#ifdef VBOX_WITH_GUEST_PROPS
+    Assert(idClient > 0);
+    AssertPtr(pfUpdate);
+    AssertPtr(ppszHostVersion);
+    AssertPtr(ppszGuestVersion);
+
+    *ppszHostVersion = NULL;
+    *ppszGuestVersion = NULL;
+
+    /* We assume we have an update initially.
+       Every block down below is allowed to veto */
+    *pfUpdate = true;
+
+    /* Do we need to do all this stuff? */
+    char *pszCheckHostVersion;
+    int rc = VbglR3GuestPropReadValueAlloc(idClient, "/VirtualBox/GuestAdd/CheckHostVersion", &pszCheckHostVersion);
+    if (RT_FAILURE(rc))
+    {
+        if (rc == VERR_NOT_FOUND)
+            rc = VINF_SUCCESS; /* If we don't find the value above we do the check by default */
+        else
+            LogFlow(("Could not read check host version flag! rc = %Rrc\n", rc));
+    }
+    else
+    {
+        /* Only don't do the check if we have a valid "0" in it */
+        if (!strcmp(pszCheckHostVersion, "0"))
+        {
+            LogRel(("No host version update check performed (disabled).\n"));
+            *pfUpdate = false;
+        }
+        VbglR3GuestPropReadValueFree(pszCheckHostVersion);
+    }
+
+    /* Collect all needed information */
+    /* Make sure we only notify the user once by comparing the host version with
+     * the last checked host version (if any) */
+    if (RT_SUCCESS(rc) && *pfUpdate)
+    {
+        /* Look up host version */
+        rc = VbglR3GuestPropReadValueAlloc(idClient, "/VirtualBox/HostInfo/VBoxVer", ppszHostVersion);
+        if (RT_FAILURE(rc))
+        {
+            LogFlow(("Could not read VBox host version! rc = %Rrc\n", rc));
+        }
+        else
+        {
+            LogFlow(("Host version: %s\n", *ppszHostVersion));
+
+            /* Get last checked host version */
+            char *pszLastCheckedHostVersion;
+            rc = VbglR3HostVersionLastCheckedLoad(idClient, &pszLastCheckedHostVersion);
+            if (RT_SUCCESS(rc))
+            {
+                LogFlow(("Last checked host version: %s\n", pszLastCheckedHostVersion));
+                if (strcmp(*ppszHostVersion, pszLastCheckedHostVersion) == 0)
+                    *pfUpdate = false; /* We already notified this version, skip */
+                VbglR3GuestPropReadValueFree(pszLastCheckedHostVersion);
+            }
+            else if (rc == VERR_NOT_FOUND) /* Never wrote a last checked host version before */
+            {
+                LogFlow(("Never checked a host version before.\n"));
+                rc = VINF_SUCCESS;
+            }
+        }
+
+        /* Look up guest version */
+        if (RT_SUCCESS(rc))
+        {
+            rc = VbglR3GetAdditionsVersion(ppszGuestVersion, NULL /* Extended version not needed here */,
+                                           NULL /* Revision not needed here */);
+            if (RT_FAILURE(rc))
+                LogFlow(("Could not read VBox guest version! rc = %Rrc\n", rc));
+        }
+    }
+
+    /* Do the actual version comparison (if needed, see block(s) above) */
+    if (RT_SUCCESS(rc) && *pfUpdate)
+    {
+        if (RTStrVersionCompare(*ppszHostVersion, *ppszGuestVersion) > 0) /* Is host version greater than guest add version? */
+        {
+            /* Yay, we have an update! */
+            LogRel(("Guest Additions update found! Please upgrade this machine to the latest Guest Additions.\n"));
+        }
+        else
+        {
+            /* How sad ... */
+            *pfUpdate = false;
+        }
+    }
+
+    /* Cleanup on failure */
+    if (RT_FAILURE(rc))
+    {
+        if (*ppszHostVersion)
+        {
+            VbglR3GuestPropReadValueFree(*ppszHostVersion);
+            *ppszHostVersion = NULL;
+        }
+        if (*ppszGuestVersion)
+        {
+            VbglR3GuestPropReadValueFree(*ppszGuestVersion);
+            *ppszGuestVersion = NULL;
+        }
+    }
+    return rc;
+#else /* !VBOX_WITH_GUEST_PROPS */
+    RT_NOREF(idClient, pfUpdate, ppszHostVersion, ppszGuestVersion);
+    return VERR_NOT_SUPPORTED;
+#endif
+}
+
+
+/** Retrieves the last checked host version.
+ *
+ * @returns VBox status code.
+ *
+ * @param   idClient        The client id returned by VbglR3InfoSvcConnect().
+ * @param   ppszVer         Receives pointer of allocated version string.
+ *                          The returned pointer must be freed using RTStrFree() on VINF_SUCCESS.
+ */
+VBGLR3DECL(int) VbglR3HostVersionLastCheckedLoad(HGCMCLIENTID idClient, char **ppszVer)
+{
+#ifdef VBOX_WITH_GUEST_PROPS
+    Assert(idClient > 0);
+    AssertPtr(ppszVer);
+    return VbglR3GuestPropReadValueAlloc(idClient, "/VirtualBox/GuestAdd/HostVerLastChecked", ppszVer);
+#else /* !VBOX_WITH_GUEST_PROPS */
+    RT_NOREF(idClient, ppszVer);
+    return VERR_NOT_SUPPORTED;
+#endif
+}
+
+
+/** Stores the last checked host version for later lookup.
+ *  Requires strings in form of "majorVer.minorVer.build".
+ *
+ * @returns VBox status code.
+ *
+ * @param   idClient        The client id returned by VbglR3InfoSvcConnect().
+ * @param   pszVer          Pointer to version string to store.
+ */
+VBGLR3DECL(int) VbglR3HostVersionLastCheckedStore(HGCMCLIENTID idClient, const char *pszVer)
+{
+#ifdef VBOX_WITH_GUEST_PROPS
+    Assert(idClient > 0);
+    AssertPtr(pszVer);
+    return VbglR3GuestPropWriteValue(idClient, "/VirtualBox/GuestAdd/HostVerLastChecked", pszVer);
+#else /* !VBOX_WITH_GUEST_PROPS */
+    RT_NOREF(idClient, pszVer);
+    return VERR_NOT_SUPPORTED;
+#endif
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibInternal.h b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibInternal.h
new file mode 100644
index 00000000..fb97ace3
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibInternal.h
@@ -0,0 +1,131 @@
+/* $Id: VBoxGuestR3LibInternal.h $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 support library for the guest additions, Internal header.
+ */
+
+/*
+ * 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 GA_INCLUDED_SRC_common_VBoxGuest_lib_VBoxGuestR3LibInternal_h
+#define GA_INCLUDED_SRC_common_VBoxGuest_lib_VBoxGuestR3LibInternal_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <VBox/VMMDev.h>
+#include <VBox/VBoxGuest.h>
+#include <VBox/VBoxGuestLib.h>
+
+#ifdef VBOX_VBGLR3_XFREE86
+/* Rather than try to resolve all the header file conflicts, I will just
+   prototype what we need here. */
+typedef unsigned long xf86size_t;
+extern "C" xf86size_t xf86strlen(const char*);
+# undef strlen
+# define strlen xf86strlen
+#endif /* VBOX_VBGLR3_XFREE86 */
+
+RT_C_DECLS_BEGIN
+
+int     vbglR3DoIOCtl(uintptr_t uFunction, PVBGLREQHDR pReq, size_t cbReq);
+int     vbglR3DoIOCtlRaw(uintptr_t uFunction, PVBGLREQHDR pReq, size_t cbReq);
+int     vbglR3GRAlloc(VMMDevRequestHeader **ppReq, size_t cb, VMMDevRequestType enmReqType);
+int     vbglR3GRPerform(VMMDevRequestHeader *pReq);
+void    vbglR3GRFree(VMMDevRequestHeader *pReq);
+
+
+
+DECLINLINE(void) VbglHGCMParmUInt32Set(HGCMFunctionParameter *pParm, uint32_t u32)
+{
+    pParm->type = VMMDevHGCMParmType_32bit;
+    pParm->u.value64 = 0; /* init unused bits to 0 */
+    pParm->u.value32 = u32;
+}
+
+
+DECLINLINE(int) VbglHGCMParmUInt32Get(HGCMFunctionParameter *pParm, uint32_t *pu32)
+{
+    if (pParm->type == VMMDevHGCMParmType_32bit)
+    {
+        *pu32 = pParm->u.value32;
+        return VINF_SUCCESS;
+    }
+    *pu32 = UINT32_MAX; /* shut up gcc */
+    return VERR_WRONG_PARAMETER_TYPE;
+}
+
+
+DECLINLINE(void) VbglHGCMParmUInt64Set(HGCMFunctionParameter *pParm, uint64_t u64)
+{
+    pParm->type      = VMMDevHGCMParmType_64bit;
+    pParm->u.value64 = u64;
+}
+
+
+DECLINLINE(int) VbglHGCMParmUInt64Get(HGCMFunctionParameter *pParm, uint64_t *pu64)
+{
+    if (pParm->type == VMMDevHGCMParmType_64bit)
+    {
+        *pu64 = pParm->u.value64;
+        return VINF_SUCCESS;
+    }
+    *pu64 = UINT64_MAX; /* shut up gcc */
+    return VERR_WRONG_PARAMETER_TYPE;
+}
+
+
+DECLINLINE(void) VbglHGCMParmPtrSet(HGCMFunctionParameter *pParm, void *pv, uint32_t cb)
+{
+    pParm->type                    = VMMDevHGCMParmType_LinAddr;
+    pParm->u.Pointer.size          = cb;
+    pParm->u.Pointer.u.linearAddr  = (uintptr_t)pv;
+}
+
+
+#ifdef IPRT_INCLUDED_string_h
+
+DECLINLINE(void) VbglHGCMParmPtrSetString(HGCMFunctionParameter *pParm, const char *psz)
+{
+    pParm->type                    = VMMDevHGCMParmType_LinAddr_In;
+    pParm->u.Pointer.size          = (uint32_t)strlen(psz) + 1;
+    pParm->u.Pointer.u.linearAddr  = (uintptr_t)psz;
+}
+
+#endif /* IPRT_INCLUDED_string_h */
+
+#ifdef VBOX_VBGLR3_XFREE86
+# undef strlen
+#endif /* VBOX_VBGLR3_XFREE86 */
+
+RT_C_DECLS_END
+
+#endif /* !GA_INCLUDED_SRC_common_VBoxGuest_lib_VBoxGuestR3LibInternal_h */
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibLog.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibLog.cpp
new file mode 100644
index 00000000..04a167e0
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibLog.cpp
@@ -0,0 +1,94 @@
+/* $Id: VBoxGuestR3LibLog.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, Logging.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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 <iprt/err.h>
+#include <iprt/mem.h>
+#include <iprt/string.h>
+#include "VBoxGuestR3LibInternal.h"
+
+
+/**
+ * Write to the backdoor logger from ring 3 guest code.
+ *
+ * @returns IPRT status code.
+ *
+ * @param   pch     The string to log.  Does not need to be terminated.
+ * @param   cch     The number of chars (bytes) to log.
+ *
+ * @remarks This currently does not accept more than 255 bytes of data at
+ *          one time. It should probably be rewritten to use pass a pointer
+ *          in the IOCtl.
+ */
+VBGLR3DECL(int) VbglR3WriteLog(const char *pch, size_t cch)
+{
+    /*
+     * Quietly skip empty strings.
+     * (Happens in the RTLogBackdoorPrintf case.)
+     */
+    int rc;
+    if (cch > 0)
+    {
+        if (RT_VALID_PTR(pch))
+        {
+            /*
+             * We need to repackage the string for ring-0.
+             */
+            size_t      cbMsg = VBGL_IOCTL_LOG_SIZE(cch);
+            PVBGLIOCLOG pMsg  = (PVBGLIOCLOG)RTMemTmpAlloc(cbMsg);
+            if (pMsg)
+            {
+                VBGLREQHDR_INIT_EX(&pMsg->Hdr, VBGL_IOCTL_LOG_SIZE_IN(cch), VBGL_IOCTL_LOG_SIZE_OUT);
+                memcpy(pMsg->u.In.szMsg, pch, cch);
+                pMsg->u.In.szMsg[cch] = '\0';
+                rc = vbglR3DoIOCtl(VBGL_IOCTL_LOG(cch), &pMsg->Hdr, cbMsg);
+
+                RTMemTmpFree(pMsg);
+            }
+            else
+                rc = VERR_NO_TMP_MEMORY;
+        }
+        else
+            rc = VERR_INVALID_POINTER;
+    }
+    else
+        rc = VINF_SUCCESS;
+    return rc;
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibMisc.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibMisc.cpp
new file mode 100644
index 00000000..81e7b272
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibMisc.cpp
@@ -0,0 +1,135 @@
+/* $Id: VBoxGuestR3LibMisc.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, Misc.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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 <VBox/log.h>
+#include "VBoxGuestR3LibInternal.h"
+
+
+/**
+ * Change the IRQ filter mask.
+ *
+ * @returns IPRT status code.
+ * @param   fOr     The OR mask.
+ * @param   fNot    The NOT mask.
+ */
+VBGLR3DECL(int) VbglR3CtlFilterMask(uint32_t fOr, uint32_t fNot)
+{
+    VBGLIOCCHANGEFILTERMASK Info;
+    VBGLREQHDR_INIT(&Info.Hdr, CHANGE_FILTER_MASK);
+    Info.u.In.fOrMask  = fOr;
+    Info.u.In.fNotMask = fNot;
+    return vbglR3DoIOCtl(VBGL_IOCTL_CHANGE_FILTER_MASK, &Info.Hdr, sizeof(Info));
+}
+
+
+/**
+ * Report a change in the capabilities that we support to the host.
+ *
+ * @returns IPRT status code.
+ * @param   fOr     Capabilities which have been added.
+ * @param   fNot    Capabilities which have been removed.
+ *
+ * @todo    Move to a different file.
+ */
+VBGLR3DECL(int) VbglR3SetGuestCaps(uint32_t fOr, uint32_t fNot)
+{
+    VBGLIOCSETGUESTCAPS Info;
+    VBGLREQHDR_INIT(&Info.Hdr, CHANGE_GUEST_CAPABILITIES);
+    Info.u.In.fOrMask  = fOr;
+    Info.u.In.fNotMask = fNot;
+    return vbglR3DoIOCtl(VBGL_IOCTL_CHANGE_GUEST_CAPABILITIES, &Info.Hdr, sizeof(Info));
+}
+
+
+/**
+ * Acquire capabilities to report to the host.
+ *
+ * The capabilities which can be acquired are the same as those reported by
+ * VbglR3SetGuestCaps, and once a capability has been acquired once is is
+ * switched to "acquire mode" and can no longer be set using VbglR3SetGuestCaps.
+ * Capabilities can also be switched to acquire mode without actually being
+ * acquired.  A client can not acquire a capability which has been acquired and
+ * not released by another client.  Capabilities acquired are automatically
+ * released on session termination.
+ *
+ * @returns IPRT status code
+ * @returns VERR_RESOURCE_BUSY and acquires nothing if another client has
+ *          acquired and not released at least one of the @a fOr capabilities
+ * @param   fOr      Capabilities to acquire or to switch to acquire mode
+ * @param   fNot     Capabilities to release
+ * @param   fConfig  if set, capabilities in @a fOr are switched to acquire mode
+ *                   but not acquired, and @a fNot is ignored.  See
+ *                   VBGL_IOC_AGC_FLAGS_CONFIG_ACQUIRE_MODE for details.
+ */
+VBGLR3DECL(int) VbglR3AcquireGuestCaps(uint32_t fOr, uint32_t fNot, bool fConfig)
+{
+    VBGLIOCACQUIREGUESTCAPS Info;
+    VBGLREQHDR_INIT(&Info.Hdr, ACQUIRE_GUEST_CAPABILITIES);
+    Info.u.In.fFlags   = fConfig ? VBGL_IOC_AGC_FLAGS_CONFIG_ACQUIRE_MODE : VBGL_IOC_AGC_FLAGS_DEFAULT;
+    Info.u.In.fOrMask  = fOr;
+    Info.u.In.fNotMask = fNot;
+    return vbglR3DoIOCtl(VBGL_IOCTL_ACQUIRE_GUEST_CAPABILITIES, &Info.Hdr, sizeof(Info));
+}
+
+
+/**
+ * Query the session ID of this VM.
+ *
+ * The session id is an unique identifier that gets changed for each VM start,
+ * reset or restore.  Useful for detection a VM restore.
+ *
+ * @returns IPRT status code.
+ * @param   pu64IdSession       Session id (out).  This is NOT changed on
+ *                              failure, so the caller can depend on this to
+ *                              deal with backward compatibility (see
+ *                              VBoxServiceVMInfoWorker() for an example.)
+ */
+VBGLR3DECL(int) VbglR3GetSessionId(uint64_t *pu64IdSession)
+{
+    VMMDevReqSessionId Req;
+
+    vmmdevInitRequest(&Req.header, VMMDevReq_GetSessionId);
+    Req.idSession = 0;
+    int rc = vbglR3GRPerform(&Req.header);
+    if (RT_SUCCESS(rc))
+        *pu64IdSession = Req.idSession;
+
+    return rc;
+}
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibModule.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibModule.cpp
new file mode 100644
index 00000000..371b42d7
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibModule.cpp
@@ -0,0 +1,180 @@
+/* $Id: VBoxGuestR3LibModule.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, Shared modules.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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 "VBoxGuestR3LibInternal.h"
+#include <iprt/mem.h>
+#include <iprt/string.h>
+
+/**
+ * Registers a new shared module for the VM
+ *
+ * @returns IPRT status code.
+ * @param   pszModuleName       Module name
+ * @param   pszVersion          Module version
+ * @param   GCBaseAddr          Module base address
+ * @param   cbModule            Module size
+ * @param   cRegions            Number of shared region descriptors
+ * @param   pRegions            Shared region(s)
+ */
+VBGLR3DECL(int) VbglR3RegisterSharedModule(char *pszModuleName, char *pszVersion,
+                                           RTGCPTR64  GCBaseAddr, uint32_t cbModule,
+                                           unsigned cRegions, VMMDEVSHAREDREGIONDESC *pRegions)
+{
+    VMMDevSharedModuleRegistrationRequest *pReq;
+    int rc;
+
+    /* Sanity check. */
+    AssertReturn(cRegions < VMMDEVSHAREDREGIONDESC_MAX, VERR_INVALID_PARAMETER);
+
+    pReq = (VMMDevSharedModuleRegistrationRequest *)RTMemAllocZ(RT_UOFFSETOF_DYN(VMMDevSharedModuleRegistrationRequest,
+                                                                                 aRegions[cRegions]));
+    AssertReturn(pReq, VERR_NO_MEMORY);
+
+    vmmdevInitRequest(&pReq->header, VMMDevReq_RegisterSharedModule);
+    pReq->header.size   = RT_UOFFSETOF_DYN(VMMDevSharedModuleRegistrationRequest, aRegions[cRegions]);
+    pReq->GCBaseAddr    = GCBaseAddr;
+    pReq->cbModule      = cbModule;
+    pReq->cRegions      = cRegions;
+#ifdef RT_OS_WINDOWS
+# if ARCH_BITS == 32
+    pReq->enmGuestOS    = VBOXOSFAMILY_Windows32;
+# else
+    pReq->enmGuestOS    = VBOXOSFAMILY_Windows64;
+# endif
+#else
+    /** @todo */
+    pReq->enmGuestOS    = VBOXOSFAMILY_Unknown;
+#endif
+    for (unsigned i = 0; i < cRegions; i++)
+        pReq->aRegions[i] = pRegions[i];
+
+    if (    RTStrCopy(pReq->szName, sizeof(pReq->szName), pszModuleName) != VINF_SUCCESS
+        ||  RTStrCopy(pReq->szVersion, sizeof(pReq->szVersion), pszVersion) != VINF_SUCCESS)
+    {
+        rc = VERR_BUFFER_OVERFLOW;
+        goto end;
+    }
+
+    rc = vbglR3GRPerform(&pReq->header);
+
+end:
+    RTMemFree(pReq);
+    return rc;
+
+}
+
+/**
+ * Unregisters a shared module for the VM
+ *
+ * @returns IPRT status code.
+ * @param   pszModuleName       Module name
+ * @param   pszVersion          Module version
+ * @param   GCBaseAddr          Module base address
+ * @param   cbModule            Module size
+ */
+VBGLR3DECL(int) VbglR3UnregisterSharedModule(char *pszModuleName, char *pszVersion, RTGCPTR64 GCBaseAddr, uint32_t cbModule)
+{
+    VMMDevSharedModuleUnregistrationRequest Req;
+
+    vmmdevInitRequest(&Req.header, VMMDevReq_UnregisterSharedModule);
+    Req.GCBaseAddr    = GCBaseAddr;
+    Req.cbModule      = cbModule;
+
+    if (    RTStrCopy(Req.szName, sizeof(Req.szName), pszModuleName) != VINF_SUCCESS
+        ||  RTStrCopy(Req.szVersion, sizeof(Req.szVersion), pszVersion) != VINF_SUCCESS)
+    {
+        return VERR_BUFFER_OVERFLOW;
+    }
+    return vbglR3GRPerform(&Req.header);
+}
+
+/**
+ * Checks registered modules for shared pages
+ *
+ * @returns IPRT status code.
+ */
+VBGLR3DECL(int) VbglR3CheckSharedModules()
+{
+    VMMDevSharedModuleCheckRequest Req;
+
+    vmmdevInitRequest(&Req.header, VMMDevReq_CheckSharedModules);
+    return vbglR3GRPerform(&Req.header);
+}
+
+/**
+ * Checks if page sharing is enabled.
+ *
+ * @returns true/false enabled/disabled
+ */
+VBGLR3DECL(bool) VbglR3PageSharingIsEnabled()
+{
+    VMMDevPageSharingStatusRequest Req;
+
+    vmmdevInitRequest(&Req.header, VMMDevReq_GetPageSharingStatus);
+    int rc = vbglR3GRPerform(&Req.header);
+    if (RT_SUCCESS(rc))
+        return Req.fEnabled;
+    return false;
+}
+
+/**
+ * Checks if page sharing is enabled.
+ *
+ * @returns true/false enabled/disabled
+ */
+VBGLR3DECL(int) VbglR3PageIsShared(RTGCPTR pPage, bool *pfShared, uint64_t *puPageFlags)
+{
+#ifdef DEBUG
+    VMMDevPageIsSharedRequest Req;
+
+    vmmdevInitRequest(&Req.header, VMMDevReq_DebugIsPageShared);
+    Req.GCPtrPage = pPage;
+    int rc = vbglR3GRPerform(&Req.header);
+    if (RT_SUCCESS(rc))
+    {
+        *pfShared    = Req.fShared;
+        *puPageFlags = Req.uPageFlags;
+    }
+    return rc;
+#else
+    RT_NOREF3(pPage, pfShared, puPageFlags);
+    return VERR_NOT_IMPLEMENTED;
+#endif
+}
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibMouse.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibMouse.cpp
new file mode 100644
index 00000000..b93872d4
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibMouse.cpp
@@ -0,0 +1,90 @@
+/* $Id: VBoxGuestR3LibMouse.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, Mouse.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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 "VBoxGuestR3LibInternal.h"
+
+
+/**
+ * Retrieve mouse coordinates and features from the host.
+ *
+ * @returns VBox status code.
+ *
+ * @param   pfFeatures  Where to store the mouse features.
+ * @param   px          Where to store the X co-ordinate.
+ * @param   py          Where to store the Y co-ordinate.
+ */
+VBGLR3DECL(int) VbglR3GetMouseStatus(uint32_t *pfFeatures, uint32_t *px, uint32_t *py)
+{
+    VMMDevReqMouseStatus Req;
+    vmmdevInitRequest(&Req.header, VMMDevReq_GetMouseStatus);
+    Req.mouseFeatures = 0;
+    Req.pointerXPos = 0;
+    Req.pointerYPos = 0;
+    int rc = vbglR3GRPerform(&Req.header);
+    if (RT_SUCCESS(rc))
+    {
+        if (pfFeatures)
+            *pfFeatures = Req.mouseFeatures;
+        if (px)
+            *px = Req.pointerXPos;
+        if (py)
+            *py = Req.pointerYPos;
+    }
+    return rc;
+}
+
+
+/**
+ * Send mouse features to the host.
+ *
+ * @returns VBox status code.
+ *
+ * @param   fFeatures  Supported mouse pointer features.  The main guest driver
+ *                     will mediate different callers and show the host any
+ *                     feature enabled by any guest caller.
+ */
+VBGLR3DECL(int) VbglR3SetMouseStatus(uint32_t fFeatures)
+{
+    VBGLIOCSETMOUSESTATUS Req;
+    VBGLREQHDR_INIT(&Req.Hdr, SET_MOUSE_STATUS);
+    Req.u.In.fStatus = fFeatures;
+    return vbglR3DoIOCtl(VBGL_IOCTL_SET_MOUSE_STATUS, &Req.Hdr, sizeof(Req));
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibPidFile.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibPidFile.cpp
new file mode 100644
index 00000000..ff7c312d
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibPidFile.cpp
@@ -0,0 +1,151 @@
+/** $Id: VBoxGuestR3LibPidFile.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions,
+ * Create a PID file.
+ */
+
+/*
+ * Copyright (C) 2015-2023 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 <iprt/file.h>
+#include <iprt/string.h>
+#include <iprt/process.h>
+#include <iprt/thread.h>
+#include <iprt/err.h>
+#include "VBoxGuestR3LibInternal.h"
+
+/* A time to wait before starting the next attempt to check a pidfile. */
+#define VBGL_PIDFILE_WAIT_RELAX_TIME_MS (250)
+
+/**
+ * Creates a PID File and returns the open file descriptor.
+ *
+ * On DOS based system, file sharing (deny write) is used for locking the PID
+ * file.
+ *
+ * On Unix-y systems, an exclusive advisory lock is used for locking the PID
+ * file since the file sharing support is usually missing there.
+ *
+ * This API will overwrite any existing PID Files without a lock on them, on the
+ * assumption that they are stale files which an old process did not properly
+ * clean up.
+ *
+ * @returns IPRT status code.
+ * @param   pszPath  The path and filename to create the PID File under
+ * @param   phFile   Where to store the file descriptor of the open (and locked
+ *                   on Unix-y systems) PID File. On failure, or if another
+ *                   process owns the PID File, this will be set to NIL_RTFILE.
+ */
+VBGLR3DECL(int) VbglR3PidFile(const char *pszPath, PRTFILE phFile)
+{
+    AssertPtrReturn(pszPath, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(phFile, VERR_INVALID_PARAMETER);
+    *phFile = NIL_RTFILE;
+
+    RTFILE hPidFile;
+    int rc = RTFileOpen(&hPidFile, pszPath,
+                        RTFILE_O_READWRITE | RTFILE_O_OPEN_CREATE | RTFILE_O_DENY_WRITE
+                        | (0644 << RTFILE_O_CREATE_MODE_SHIFT));
+    if (RT_SUCCESS(rc))
+    {
+#if !defined(RT_OS_WINDOWS) && !defined(RT_OS_OS2)
+        /** @todo using size 0 for locking means lock all on Posix.
+         * We should adopt this as our convention too, or something
+         * similar. */
+        rc = RTFileLock(hPidFile, RTFILE_LOCK_WRITE, 0, 0);
+        if (RT_FAILURE(rc))
+            RTFileClose(hPidFile);
+        else
+#endif
+        {
+            char szBuf[256];
+            size_t cbPid = RTStrPrintf(szBuf, sizeof(szBuf), "%d\n",
+                                       RTProcSelf());
+            RTFileWrite(hPidFile, szBuf, cbPid, NULL);
+            *phFile = hPidFile;
+        }
+    }
+    return rc;
+}
+
+
+/**
+ * Close and remove an open PID File.
+ *
+ * @param  pszPath  The path to the PID File,
+ * @param  hFile    The handle for the file. NIL_RTFILE is ignored as usual.
+ */
+VBGLR3DECL(void) VbglR3ClosePidFile(const char *pszPath, RTFILE hFile)
+{
+    AssertPtrReturnVoid(pszPath);
+    if (hFile != NIL_RTFILE)
+    {
+#if defined(RT_OS_WINDOWS) || defined(RT_OS_OS2)
+        RTFileWriteAt(hFile, 0, "-1", 2, NULL);
+#else
+        RTFileDelete(pszPath);
+#endif
+        RTFileClose(hFile);
+    }
+}
+
+
+/**
+ * Wait for other process to release pidfile.
+ *
+ * This function is a wrapper to VbglR3PidFile().
+ *
+ * @returns IPRT status code.
+ * @param   szPidfile       Path to pidfile.
+ * @param   phPidfile       Handle to pidfile.
+ * @param   u64TimeoutMs    A timeout value in milliseconds to wait for
+ *                          other process to release pidfile.
+ */
+VBGLR3DECL(int) VbglR3PidfileWait(const char *szPidfile, RTFILE *phPidfile, uint64_t u64TimeoutMs)
+{
+    int rc = VERR_FILE_LOCK_VIOLATION;
+    uint64_t u64Start = RTTimeSystemMilliTS();
+
+    AssertPtrReturn(szPidfile, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(phPidfile, VERR_INVALID_PARAMETER);
+
+    while (   !RT_SUCCESS((rc = VbglR3PidFile(szPidfile, phPidfile)))
+           && (RTTimeSystemMilliTS() - u64Start < u64TimeoutMs))
+    {
+        RTThreadSleep(VBGL_PIDFILE_WAIT_RELAX_TIME_MS);
+    }
+
+    return rc;
+}
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibRuntimeXF86.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibRuntimeXF86.cpp
new file mode 100644
index 00000000..8a9d15c0
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibRuntimeXF86.cpp
@@ -0,0 +1,108 @@
+/* $Id: VBoxGuestR3LibRuntimeXF86.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions,
+ *                  implements the minimum of runtime functions needed for
+ *                  XFree86 driver code.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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 <iprt/assert.h>
+#include <iprt/log.h>
+#include <iprt/mem.h>
+#if defined(VBOX_VBGLR3_XFREE86)
+extern "C" {
+# define XFree86LOADER
+# include <xf86_ansic.h>
+# undef size_t
+}
+#else
+# include <stdarg.h>
+# include <stdlib.h>
+# define xalloc malloc
+# define xfree free
+extern "C" void ErrorF(const char *f, ...);
+#endif
+
+RTDECL(void)    RTAssertMsg1Weak(const char *pszExpr, unsigned uLine, const char *pszFile, const char *pszFunction)
+{
+    ErrorF("Assertion failed!  Expression: %s at %s in\n", pszExpr,
+           pszFunction);
+    ErrorF("%s:%u\n", pszFile, uLine);
+}
+
+RTDECL(void)    RTAssertMsg2Weak(const char *pszFormat, ...)
+{
+    NOREF(pszFormat);
+}
+
+RTDECL(bool)    RTAssertShouldPanic(void)
+{
+    return false;
+}
+
+RTDECL(PRTLOGGER) RTLogDefaultInstanceEx(uint32_t fFlagsAndGroup)
+{
+    NOREF(fFlagsAndGroup);
+    return NULL;
+}
+
+RTDECL(PRTLOGGER) RTLogRelGetDefaultInstance(void)
+{
+    return NULL;
+}
+
+RTDECL(PRTLOGGER) RTLogRelGetDefaultInstanceEx(uint32_t fFlagsAndGroup)
+{
+    NOREF(fFlagsAndGroup);
+    return NULL;
+}
+
+RTDECL(void) RTLogLoggerEx(PRTLOGGER, unsigned, unsigned, const char *pszFormat, ...)
+{
+    NOREF(pszFormat);
+}
+
+RTDECL(void *)  RTMemTmpAllocTag(size_t cb, const char *pszTag)
+{
+    NOREF(pszTag);
+    return xalloc(cb);
+}
+
+RTDECL(void)    RTMemTmpFree(void *pv)
+{
+    xfree(pv);
+}
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibSeamless.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibSeamless.cpp
new file mode 100644
index 00000000..a13a77b9
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibSeamless.cpp
@@ -0,0 +1,209 @@
+/* $Id: VBoxGuestR3LibSeamless.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, Seamless mode.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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 <iprt/assert.h>
+#include <iprt/errcore.h>
+#include <iprt/string.h>
+
+#include <VBox/log.h>
+
+#include "VBoxGuestR3LibInternal.h"
+
+#ifdef VBOX_VBGLR3_XFREE86
+/* Rather than try to resolve all the header file conflicts, I will just
+   prototype what we need here. */
+extern "C" void* xf86memcpy(void*,const void*,xf86size_t);
+# undef memcpy
+# define memcpy xf86memcpy
+#endif /* VBOX_VBGLR3_XFREE86 */
+
+/**
+ * Tell the host that we support (or no longer support) seamless mode.
+ *
+ * @returns IPRT status value
+ * @param   fState whether or not we support seamless mode
+ */
+VBGLR3DECL(int) VbglR3SeamlessSetCap(bool fState)
+{
+    if (fState)
+        return VbglR3SetGuestCaps(VMMDEV_GUEST_SUPPORTS_SEAMLESS, 0);
+    return VbglR3SetGuestCaps(0, VMMDEV_GUEST_SUPPORTS_SEAMLESS);
+}
+
+/**
+ * Wait for a seamless mode change event.
+ *
+ * @returns IPRT status value.
+ * @param[out] pMode    On success, the seamless mode to switch into (i.e.
+ *                      disabled, visible region or host window).
+ */
+VBGLR3DECL(int) VbglR3SeamlessWaitEvent(VMMDevSeamlessMode *pMode)
+{
+    AssertPtrReturn(pMode, VERR_INVALID_POINTER);
+
+    /** @todo r=andy The (similar / duplicate) Windows code does similar waiting. Merge / fix this. */
+    uint32_t fEvent = 0;
+    int rc = VbglR3WaitEvent(VMMDEV_EVENT_SEAMLESS_MODE_CHANGE_REQUEST, 1000 /* ms */, &fEvent);
+    if (RT_SUCCESS(rc))
+    {
+        /* did we get the right event? */
+        if (fEvent & VMMDEV_EVENT_SEAMLESS_MODE_CHANGE_REQUEST)
+        {
+            VMMDevSeamlessChangeRequest seamlessChangeRequest;
+
+            /* get the seamless change request */
+            vmmdevInitRequest(&seamlessChangeRequest.header, VMMDevReq_GetSeamlessChangeRequest);
+            seamlessChangeRequest.mode = (VMMDevSeamlessMode)-1;
+            seamlessChangeRequest.eventAck = VMMDEV_EVENT_SEAMLESS_MODE_CHANGE_REQUEST;
+            rc = vbglR3GRPerform(&seamlessChangeRequest.header);
+            if (RT_SUCCESS(rc))
+            {
+                *pMode = seamlessChangeRequest.mode;
+                return VINF_SUCCESS;
+            }
+        }
+        else
+            rc = VERR_TRY_AGAIN;
+    }
+    else if (   rc == VERR_INTERRUPTED
+             || rc == VERR_TIMEOUT /* just in case */)
+        rc = VERR_TRY_AGAIN;
+    return rc;
+}
+
+/**
+ * Request the last seamless mode switch from the host again.
+ *
+ * @returns IPRT status value.
+ * @param[out] pMode    On success, the seamless mode that was switched
+ *                      into (i.e. disabled, visible region or host window).
+ */
+VBGLR3DECL(int) VbglR3SeamlessGetLastEvent(VMMDevSeamlessMode *pMode)
+{
+    VMMDevSeamlessChangeRequest seamlessChangeRequest;
+    int rc;
+
+    AssertPtrReturn(pMode, VERR_INVALID_PARAMETER);
+
+    /* get the seamless change request */
+    vmmdevInitRequest(&seamlessChangeRequest.header, VMMDevReq_GetSeamlessChangeRequest);
+    seamlessChangeRequest.mode = (VMMDevSeamlessMode)-1;
+    seamlessChangeRequest.eventAck = VMMDEV_EVENT_SEAMLESS_MODE_CHANGE_REQUEST;
+    rc = vbglR3GRPerform(&seamlessChangeRequest.header);
+    if (RT_SUCCESS(rc))
+    {
+        *pMode = seamlessChangeRequest.mode;
+        return VINF_SUCCESS;
+    }
+    return rc;
+}
+
+/**
+ * Inform the host about the visible region
+ *
+ * @returns IPRT status code
+ * @param   cRects number of rectangles in the list of visible rectangles
+ * @param   pRects list of visible rectangles on the guest display
+ *
+ * @todo A scatter-gather version of vbglR3GRPerform would be nice, so that we don't have
+ *       to copy our rectangle and header data into a single structure and perform an
+ *       additional allocation.
+ * @todo Would that really gain us much, given that the rectangles may not
+ *       be grouped at all, or in the format we need?  Keeping the memory
+ *       for our "single structure" around (re-alloc-ing it if necessary)
+ *       sounds like a simpler optimisation if we need it.
+ */
+VBGLR3DECL(int) VbglR3SeamlessSendRects(uint32_t cRects, PRTRECT pRects)
+{
+    VMMDevVideoSetVisibleRegion *pReq;
+    int rc;
+
+    AssertReturn(pRects || cRects == 0, VERR_INVALID_PARAMETER);
+    AssertMsgReturn(cRects <= _1M, ("%u\n", cRects), VERR_OUT_OF_RANGE);
+
+    rc = vbglR3GRAlloc((VMMDevRequestHeader **)&pReq,
+                         sizeof(VMMDevVideoSetVisibleRegion)
+                       + cRects * sizeof(RTRECT)
+                       - sizeof(RTRECT),
+                       VMMDevReq_VideoSetVisibleRegion);
+    if (RT_SUCCESS(rc))
+    {
+        pReq->cRect = cRects;
+        if (cRects)
+            memcpy(&pReq->Rect, pRects, cRects * sizeof(RTRECT));
+        /* This will fail harmlessly for cRect == 0 and older host code */
+        rc = vbglR3GRPerform(&pReq->header);
+        LogFunc(("Visible region request returned %Rrc, internal %Rrc.\n",
+                 rc, pReq->header.rc));
+        if (RT_SUCCESS(rc))
+            rc = pReq->header.rc;
+        vbglR3GRFree(&pReq->header);
+    }
+    LogFunc(("Sending %u rectangles to the host: %Rrc\n", cRects, rc));
+    return rc;
+}
+
+VBGLR3DECL(int) VbglR3SeamlessSendMonitorPositions(uint32_t cPositions, PRTPOINT pPositions)
+{
+    if (!pPositions || cPositions <= 0)
+        return VERR_INVALID_PARAMETER;
+
+    VMMDevVideoUpdateMonitorPositions *pReq;
+    int rc;
+
+    rc = vbglR3GRAlloc((VMMDevRequestHeader **)&pReq,
+                         sizeof(VMMDevVideoUpdateMonitorPositions)
+                       + (cPositions - 1) * sizeof(RTPOINT),
+                       VMMDevReq_VideoUpdateMonitorPositions);
+    if (RT_SUCCESS(rc))
+    {
+        pReq->cPositions = cPositions;
+        if (cPositions)
+            memcpy(&pReq->aPositions, pPositions, cPositions * sizeof(RTPOINT));
+        rc = vbglR3GRPerform(&pReq->header);
+        LogFunc(("Monitor position update request returned %Rrc, internal %Rrc.\n",
+                 rc, pReq->header.rc));
+        if (RT_SUCCESS(rc))
+            rc = pReq->header.rc;
+        vbglR3GRFree(&pReq->header);
+    }
+    LogFunc(("Sending monitor positions (%u of them)  to the host: %Rrc\n", cPositions, rc));
+    return rc;
+}
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibSharedFolders.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibSharedFolders.cpp
new file mode 100644
index 00000000..47137fd2
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibSharedFolders.cpp
@@ -0,0 +1,432 @@
+/* $Id: VBoxGuestR3LibSharedFolders.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, shared folders.
+ */
+
+/*
+ * Copyright (C) 2010-2023 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 <iprt/string.h>
+#include <iprt/mem.h>
+#include <iprt/assert.h>
+#include <iprt/cpp/autores.h>
+#include <iprt/stdarg.h>
+#include <VBox/log.h>
+#include <VBox/shflsvc.h> /** @todo File should be moved to VBox/HostServices/SharedFolderSvc.h */
+
+#include "VBoxGuestR3LibInternal.h"
+
+
+/**
+ * Connects to the shared folder service.
+ *
+ * @returns VBox status code
+ * @param   pidClient       Where to put the client id on success. The client id
+ *                          must be passed to all the other calls to the service.
+ */
+VBGLR3DECL(int) VbglR3SharedFolderConnect(HGCMCLIENTID *pidClient)
+{
+    return VbglR3HGCMConnect("VBoxSharedFolders", pidClient);
+}
+
+
+/**
+ * Disconnect from the shared folder service.
+ *
+ * @returns VBox status code.
+ * @param   idClient        The client id returned by VbglR3InfoSvcConnect().
+ */
+VBGLR3DECL(int) VbglR3SharedFolderDisconnect(HGCMCLIENTID idClient)
+{
+    return VbglR3HGCMDisconnect(idClient);
+}
+
+
+/**
+ * Checks whether a shared folder share exists or not.
+ *
+ * @returns True if shared folder exists, false if not.
+ * @param   idClient        The client id returned by VbglR3InfoSvcConnect().
+ * @param   pszShareName    Shared folder name to check.
+ */
+VBGLR3DECL(bool) VbglR3SharedFolderExists(HGCMCLIENTID idClient, const char *pszShareName)
+{
+    AssertPtr(pszShareName);
+
+    uint32_t cMappings;
+    VBGLR3SHAREDFOLDERMAPPING *paMappings;
+
+    /** @todo Use some caching here? */
+    bool fFound = false;
+    int rc = VbglR3SharedFolderGetMappings(idClient, true /* Only process auto-mounted folders */, &paMappings, &cMappings);
+    if (RT_SUCCESS(rc))
+    {
+        for (uint32_t i = 0; i < cMappings && !fFound; i++)
+        {
+            char *pszName = NULL;
+            rc = VbglR3SharedFolderGetName(idClient, paMappings[i].u32Root, &pszName);
+            if (   RT_SUCCESS(rc)
+                && *pszName)
+            {
+                if (RTStrICmp(pszName, pszShareName) == 0)
+                    fFound = true;
+                RTStrFree(pszName);
+            }
+        }
+        VbglR3SharedFolderFreeMappings(paMappings);
+    }
+    return fFound;
+}
+
+
+/**
+ * Get the list of available shared folders.
+ *
+ * @returns VBox status code.
+ * @param   idClient        The client id returned by VbglR3SharedFolderConnect().
+ * @param   fAutoMountOnly  Flag whether only auto-mounted shared folders
+ *                          should be reported.
+ * @param   ppaMappings     Allocated array which will retrieve the mapping info.  Needs
+ *                          to be freed with VbglR3SharedFolderFreeMappings() later.
+ * @param   pcMappings      The number of mappings returned in @a ppaMappings.
+ */
+VBGLR3DECL(int) VbglR3SharedFolderGetMappings(HGCMCLIENTID idClient, bool fAutoMountOnly,
+                                              PVBGLR3SHAREDFOLDERMAPPING *ppaMappings, uint32_t *pcMappings)
+{
+    AssertPtrReturn(pcMappings, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(ppaMappings, VERR_INVALID_PARAMETER);
+
+    *pcMappings = 0;
+    *ppaMappings = NULL;
+
+    VBoxSFQueryMappings Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.callInfo, idClient, SHFL_FN_QUERY_MAPPINGS, 3);
+
+    /* Set the mapping flags. */
+    uint32_t u32Flags = 0; /** @todo SHFL_MF_UTF8 is not implemented yet. */
+    if (fAutoMountOnly) /* We only want the mappings which get auto-mounted. */
+        u32Flags |= SHFL_MF_AUTOMOUNT;
+    VbglHGCMParmUInt32Set(&Msg.flags, u32Flags);
+
+    /*
+     * Prepare and get the actual mappings from the host service.
+     */
+    int rc = VINF_SUCCESS;
+    uint32_t cMappings = 8; /* Should be a good default value. */
+    uint32_t cbSize = cMappings * sizeof(VBGLR3SHAREDFOLDERMAPPING);
+    VBGLR3SHAREDFOLDERMAPPING *ppaMappingsTemp = (PVBGLR3SHAREDFOLDERMAPPING)RTMemAllocZ(cbSize);
+    if (!ppaMappingsTemp)
+        return VERR_NO_MEMORY;
+
+    do
+    {
+        VbglHGCMParmUInt32Set(&Msg.numberOfMappings, cMappings);
+        VbglHGCMParmPtrSet(&Msg.mappings, ppaMappingsTemp, cbSize);
+
+        rc = VbglR3HGCMCall(&Msg.callInfo, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            VbglHGCMParmUInt32Get(&Msg.numberOfMappings, pcMappings);
+
+            /* Do we have more mappings than we have allocated space for? */
+            if (rc == VINF_BUFFER_OVERFLOW)
+            {
+                cMappings = *pcMappings;
+                cbSize = cMappings * sizeof(VBGLR3SHAREDFOLDERMAPPING);
+                void *pvNew = RTMemRealloc(ppaMappingsTemp, cbSize);
+                AssertPtrBreakStmt(pvNew, rc = VERR_NO_MEMORY);
+                ppaMappingsTemp = (PVBGLR3SHAREDFOLDERMAPPING)pvNew;
+            }
+        }
+    } while (rc == VINF_BUFFER_OVERFLOW); /** @todo r=bird: This won't happen because the weird host code never returns it. */
+
+    if (   RT_FAILURE(rc)
+        || !*pcMappings)
+    {
+        RTMemFree(ppaMappingsTemp);
+        ppaMappingsTemp = NULL;
+    }
+
+    /* In this case, just return success with 0 mappings */
+    if (   rc == VERR_INVALID_PARAMETER
+        && fAutoMountOnly)
+        rc = VINF_SUCCESS;
+
+    *ppaMappings = ppaMappingsTemp;
+
+    return rc;
+}
+
+
+/**
+ * Frees the shared folder mappings allocated by
+ * VbglR3SharedFolderGetMappings() before.
+ *
+ * @param   paMappings     What
+ */
+VBGLR3DECL(void) VbglR3SharedFolderFreeMappings(PVBGLR3SHAREDFOLDERMAPPING paMappings)
+{
+    if (paMappings)
+        RTMemFree(paMappings);
+}
+
+
+/**
+ * Get the real name of a shared folder.
+ *
+ * @returns VBox status code.
+ * @param   idClient        The client id returned by VbglR3InvsSvcConnect().
+ * @param   u32Root         Root ID of shared folder to get the name for.
+ * @param   ppszName        Where to return the name string.  This shall be
+ *                          freed by calling RTStrFree.
+ */
+VBGLR3DECL(int) VbglR3SharedFolderGetName(HGCMCLIENTID idClient, uint32_t u32Root, char **ppszName)
+{
+    AssertPtr(ppszName);
+
+    VBoxSFQueryMapName Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.callInfo, idClient, SHFL_FN_QUERY_MAP_NAME, 2);
+
+    int         rc;
+    uint32_t    cbString = SHFLSTRING_HEADER_SIZE + SHFL_MAX_LEN * sizeof(RTUTF16);
+    PSHFLSTRING pString = (PSHFLSTRING)RTMemAlloc(cbString);
+    if (pString)
+    {
+        if (!ShflStringInitBuffer(pString, cbString))
+        {
+            RTMemFree(pString);
+            return VERR_INVALID_PARAMETER;
+        }
+
+        VbglHGCMParmUInt32Set(&Msg.root, u32Root);
+        VbglHGCMParmPtrSet(&Msg.name, pString, cbString);
+
+        rc = VbglR3HGCMCall(&Msg.callInfo, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            *ppszName = NULL;
+            rc = RTUtf16ToUtf8(&pString->String.ucs2[0], ppszName);
+        }
+        RTMemFree(pString);
+    }
+    else
+        rc = VERR_NO_MEMORY;
+    return rc;
+}
+
+
+/**
+ * Queries information about a shared folder.
+ *
+ * @returns VBox status code.
+ *
+ * @param   idClient        The client ID.
+ * @param   idRoot          The root ID of the folder to query information for.
+ * @param   fQueryFlags     SHFL_MIQF_XXX.
+ * @param   ppszName        Where to return the pointer to the name.
+ *                          Free using RTStrFree.  Optional.
+ * @param   ppszMountPoint  Where to return the pointer to the auto mount point.
+ *                          Free using RTStrFree.  Optional.
+ * @param   pfFlags         Where to return the flags (SHFL_MIF_XXX).  Optional.
+ * @param   puRootIdVersion where to return the root ID version.  Optional.
+ *                          This helps detecting root-id reuse.
+ *
+ * @remarks ASSUMES UTF-16 connection to host.
+ */
+VBGLR3DECL(int) VbglR3SharedFolderQueryFolderInfo(HGCMCLIENTID idClient, uint32_t idRoot, uint64_t fQueryFlags,
+                                                  char **ppszName, char **ppszMountPoint,
+                                                  uint64_t *pfFlags, uint32_t *puRootIdVersion)
+{
+    AssertReturn(!(fQueryFlags & ~(SHFL_MIQF_DRIVE_LETTER | SHFL_MIQF_PATH)), VERR_INVALID_FLAGS);
+
+    /*
+     * Allocate string buffers first.
+     */
+    int rc;
+    PSHFLSTRING pNameBuf    = (PSHFLSTRING)RTMemAlloc(SHFLSTRING_HEADER_SIZE + (SHFL_MAX_LEN + 1) * sizeof(RTUTF16));
+    PSHFLSTRING pMountPoint = (PSHFLSTRING)RTMemAlloc(SHFLSTRING_HEADER_SIZE + (260          + 1) * sizeof(RTUTF16));
+    if (pNameBuf && pMountPoint)
+    {
+        ShflStringInitBuffer(pNameBuf,    SHFLSTRING_HEADER_SIZE + (SHFL_MAX_LEN + 1) * sizeof(RTUTF16));
+        ShflStringInitBuffer(pMountPoint, SHFLSTRING_HEADER_SIZE + (260          + 1) * sizeof(RTUTF16));
+
+        /*
+         * Make the call.
+         */
+        VBoxSFQueryMapInfo Msg;
+        VBGL_HGCM_HDR_INIT(&Msg.callInfo, idClient, SHFL_FN_QUERY_MAP_INFO, 5);
+        VbglHGCMParmUInt32Set(&Msg.root, idRoot);
+        VbglHGCMParmPtrSet(&Msg.name, pNameBuf, SHFLSTRING_HEADER_SIZE + pNameBuf->u16Size);
+        VbglHGCMParmPtrSet(&Msg.mountPoint, pMountPoint, SHFLSTRING_HEADER_SIZE + pMountPoint->u16Size);
+        VbglHGCMParmUInt64Set(&Msg.flags, fQueryFlags);
+        VbglHGCMParmUInt32Set(&Msg.rootIdVersion, 0);
+
+        rc = VbglR3HGCMCall(&Msg.callInfo, sizeof(Msg));
+        if (RT_SUCCESS(rc))
+        {
+            /*
+             * Copy out the results.
+             */
+            if (puRootIdVersion)
+                *puRootIdVersion = Msg.rootIdVersion.u.value64;
+
+            if (pfFlags)
+                *pfFlags = Msg.flags.u.value64;
+
+            if (ppszName)
+            {
+                *ppszName = NULL;
+                rc = RTUtf16ToUtf8Ex(pNameBuf->String.utf16, pNameBuf->u16Length / sizeof(RTUTF16), ppszName, 0, NULL);
+            }
+
+            if (ppszMountPoint && RT_SUCCESS(rc))
+            {
+                *ppszMountPoint = NULL;
+                rc = RTUtf16ToUtf8Ex(pMountPoint->String.utf16, pMountPoint->u16Length / sizeof(RTUTF16), ppszMountPoint, 0, NULL);
+                if (RT_FAILURE(rc) && ppszName)
+                {
+                    RTStrFree(*ppszName);
+                    *ppszName = NULL;
+                }
+            }
+        }
+    }
+    else
+        rc = VERR_NO_MEMORY;
+    RTMemFree(pMountPoint);
+    RTMemFree(pNameBuf);
+    return rc;
+}
+
+
+/**
+ * Waits for changes to the mappings (add, remove, restore).
+ *
+ * @returns VBox status code.
+ * @retval  VINF_SUCCESS on change
+ * @retval  VINF_TRY_AGAIN on restore.
+ * @retval  VERR_OUT_OF_RESOURCES if there are too many guys waiting.
+ *
+ * @param   idClient        The client ID.
+ * @param   uPrevVersion    The mappings config version number returned the last
+ *                          time around.  Use UINT32_MAX for the first call.
+ * @param   puCurVersion    Where to return the current mappings config version.
+ */
+VBGLR3DECL(int) VbglR3SharedFolderWaitForMappingsChanges(HGCMCLIENTID idClient, uint32_t uPrevVersion, uint32_t *puCurVersion)
+{
+    VBoxSFWaitForMappingsChanges Msg;
+    VBGL_HGCM_HDR_INIT(&Msg.callInfo, idClient, SHFL_FN_WAIT_FOR_MAPPINGS_CHANGES, 1);
+    VbglHGCMParmUInt32Set(&Msg.version, uPrevVersion);
+
+    int rc = VbglR3HGCMCall(&Msg.callInfo, sizeof(Msg));
+
+    *puCurVersion = Msg.version.u.value32;
+    return rc;
+}
+
+
+/**
+ * Cancels all threads currently waiting for changes for this client.
+ *
+ * @returns VBox status code.
+ * @param   idClient        The client ID.
+ */
+VBGLR3DECL(int) VbglR3SharedFolderCancelMappingsChangesWaits(HGCMCLIENTID idClient)
+{
+    VBGLIOCHGCMCALL CallInfo;
+    VBGL_HGCM_HDR_INIT(&CallInfo, idClient, SHFL_FN_CANCEL_MAPPINGS_CHANGES_WAITS, 0);
+
+    return VbglR3HGCMCall(&CallInfo, sizeof(CallInfo));
+}
+
+
+/**
+ * Retrieves the prefix for a shared folder mount point.  If no prefix
+ * is set in the guest properties "sf_" is returned.
+ *
+ * @returns VBox status code.
+ * @param   ppszPrefix      Where to return the prefix string.  This shall be
+ *                          freed by calling RTStrFree.
+ */
+VBGLR3DECL(int) VbglR3SharedFolderGetMountPrefix(char **ppszPrefix)
+{
+    AssertPtrReturn(ppszPrefix, VERR_INVALID_POINTER);
+    int rc;
+#ifdef VBOX_WITH_GUEST_PROPS
+    HGCMCLIENTID idClientGuestProp;
+    rc = VbglR3GuestPropConnect(&idClientGuestProp);
+    if (RT_SUCCESS(rc))
+    {
+        rc = VbglR3GuestPropReadValueAlloc(idClientGuestProp, "/VirtualBox/GuestAdd/SharedFolders/MountPrefix", ppszPrefix);
+        if (rc == VERR_NOT_FOUND) /* No prefix set? Then set the default. */
+        {
+#endif
+/** @todo r=bird: Inconsistent! VbglR3SharedFolderGetMountDir does not return a default. */
+            rc = RTStrDupEx(ppszPrefix, "sf_");
+#ifdef VBOX_WITH_GUEST_PROPS
+        }
+        VbglR3GuestPropDisconnect(idClientGuestProp);
+    }
+#endif
+    return rc;
+}
+
+
+/**
+ * Retrieves the mount root directory for auto-mounted shared
+ * folders. mount point. If no string is set (VERR_NOT_FOUND)
+ * it's up on the caller (guest) to decide where to mount.
+ *
+ * @returns VBox status code.
+ * @param   ppszDir         Where to return the directory
+ *                          string. This shall be freed by
+ *                          calling RTStrFree.
+ */
+VBGLR3DECL(int) VbglR3SharedFolderGetMountDir(char **ppszDir)
+{
+    AssertPtrReturn(ppszDir, VERR_INVALID_POINTER);
+    int rc = VERR_NOT_FOUND;
+#ifdef VBOX_WITH_GUEST_PROPS
+    HGCMCLIENTID idClientGuestProp;
+    rc = VbglR3GuestPropConnect(&idClientGuestProp);
+    if (RT_SUCCESS(rc))
+    {
+        rc = VbglR3GuestPropReadValueAlloc(idClientGuestProp, "/VirtualBox/GuestAdd/SharedFolders/MountDir", ppszDir);
+        VbglR3GuestPropDisconnect(idClientGuestProp);
+    }
+#endif
+    return rc;
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibStat.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibStat.cpp
new file mode 100644
index 00000000..30bc4631
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibStat.cpp
@@ -0,0 +1,79 @@
+/* $Id: VBoxGuestR3LibStat.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, Statistics.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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 "VBoxGuestR3LibInternal.h"
+
+
+/**
+ * Query the current statistics update interval.
+ *
+ * @returns IPRT status code.
+ * @param   pcMsInterval    Update interval in ms (out).
+ */
+VBGLR3DECL(int) VbglR3StatQueryInterval(PRTMSINTERVAL pcMsInterval)
+{
+    VMMDevGetStatisticsChangeRequest Req;
+
+    vmmdevInitRequest(&Req.header, VMMDevReq_GetStatisticsChangeRequest);
+    Req.eventAck = VMMDEV_EVENT_STATISTICS_INTERVAL_CHANGE_REQUEST;
+    Req.u32StatInterval = 1;
+    int rc = vbglR3GRPerform(&Req.header);
+    if (RT_SUCCESS(rc))
+    {
+        *pcMsInterval = Req.u32StatInterval * 1000;
+        if (*pcMsInterval / 1000 != Req.u32StatInterval)
+            *pcMsInterval = ~(RTMSINTERVAL)0;
+    }
+    return rc;
+}
+
+
+/**
+ * Report guest statistics.
+ *
+ * @returns IPRT status code.
+ * @param   pReq        Request packet with statistics.
+ */
+VBGLR3DECL(int) VbglR3StatReport(VMMDevReportGuestStats *pReq)
+{
+    vmmdevInitRequest(&pReq->header, VMMDevReq_ReportGuestStats);
+    return vbglR3GRPerform(&pReq->header);
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibTime.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibTime.cpp
new file mode 100644
index 00000000..603e83f7
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibTime.cpp
@@ -0,0 +1,55 @@
+/* $Id: VBoxGuestR3LibTime.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, Time.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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 <iprt/time.h>
+#include "VBoxGuestR3LibInternal.h"
+
+
+VBGLR3DECL(int) VbglR3GetHostTime(PRTTIMESPEC pTime)
+{
+    VMMDevReqHostTime Req;
+    vmmdevInitRequest(&Req.header, VMMDevReq_GetHostTime);
+    Req.time = UINT64_MAX;
+    int rc = vbglR3GRPerform(&Req.header);
+    if (RT_SUCCESS(rc))
+        RTTimeSpecSetMilli(pTime, (int64_t)Req.time);
+    return rc;
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibVideo.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibVideo.cpp
new file mode 100644
index 00000000..38a79c58
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibVideo.cpp
@@ -0,0 +1,618 @@
+/* $Id: VBoxGuestR3LibVideo.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, Video.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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 "VBoxGuestR3LibInternal.h"
+
+#include <VBox/log.h>
+#include <VBox/HostServices/GuestPropertySvc.h>  /* For Save and RetrieveVideoMode */
+#include <iprt/assert.h>
+#include <iprt/mem.h>
+#include <iprt/string.h>
+
+#ifdef VBOX_VBGLR3_XFREE86
+/* Rather than try to resolve all the header file conflicts, I will just
+   prototype what we need here. */
+extern "C" void* xf86memcpy(void*,const void*,xf86size_t);
+# undef memcpy
+# define memcpy xf86memcpy
+extern "C" void* xf86memset(const void*,int,xf86size_t);
+# undef memset
+# define memset xf86memset
+#endif /* VBOX_VBGLR3_XFREE86 */
+
+
+/*********************************************************************************************************************************
+*   Defined Constants And Macros                                                                                                 *
+*********************************************************************************************************************************/
+#define VIDEO_PROP_PREFIX "/VirtualBox/GuestAdd/Vbgl/Video/"
+
+
+/**
+ * Enable or disable video acceleration.
+ *
+ * @returns VBox status code.
+ *
+ * @param   fEnable       Pass zero to disable, any other value to enable.
+ */
+VBGLR3DECL(int) VbglR3VideoAccelEnable(bool fEnable)
+{
+    VMMDevVideoAccelEnable Req;
+    vmmdevInitRequest(&Req.header, VMMDevReq_VideoAccelEnable);
+    Req.u32Enable = fEnable;
+    Req.cbRingBuffer = VMMDEV_VBVA_RING_BUFFER_SIZE;
+    Req.fu32Status = 0;
+    return vbglR3GRPerform(&Req.header);
+}
+
+
+/**
+ * Flush the video buffer.
+ *
+ * @returns VBox status code.
+ */
+VBGLR3DECL(int) VbglR3VideoAccelFlush(void)
+{
+    VMMDevVideoAccelFlush Req;
+    vmmdevInitRequest(&Req.header, VMMDevReq_VideoAccelFlush);
+    return vbglR3GRPerform(&Req.header);
+}
+
+
+/**
+ * Send mouse pointer shape information to the host.
+ *
+ * @returns VBox status code.
+ *
+ * @param   fFlags      Mouse pointer flags.
+ * @param   xHot        X coordinate of hot spot.
+ * @param   yHot        Y coordinate of hot spot.
+ * @param   cx          Pointer width.
+ * @param   cy          Pointer height.
+ * @param   pvImg       Pointer to the image data (can be NULL).
+ * @param   cbImg       Size of the image data pointed to by pvImg.
+ */
+VBGLR3DECL(int) VbglR3SetPointerShape(uint32_t fFlags, uint32_t xHot, uint32_t yHot, uint32_t cx, uint32_t cy,
+                                      const void *pvImg, size_t cbImg)
+{
+    VMMDevReqMousePointer *pReq;
+    size_t cbReq = vmmdevGetMousePointerReqSize(cx, cy);
+    AssertReturn(   !pvImg
+                 || cbReq == RT_UOFFSETOF(VMMDevReqMousePointer, pointerData) + cbImg,
+                 VERR_INVALID_PARAMETER);
+    int rc = vbglR3GRAlloc((VMMDevRequestHeader **)&pReq, cbReq, VMMDevReq_SetPointerShape);
+    if (RT_SUCCESS(rc))
+    {
+        pReq->fFlags = fFlags;
+        pReq->xHot = xHot;
+        pReq->yHot = yHot;
+        pReq->width = cx;
+        pReq->height = cy;
+        if (pvImg)
+            memcpy(pReq->pointerData, pvImg, cbImg);
+
+        rc = vbglR3GRPerform(&pReq->header);
+        if (RT_SUCCESS(rc))
+            rc = pReq->header.rc;
+        vbglR3GRFree(&pReq->header);
+    }
+    return rc;
+}
+
+
+/**
+ * Send mouse pointer shape information to the host.
+ * This version of the function accepts a request for clients that
+ * already allocate and manipulate the request structure directly.
+ *
+ * @returns VBox status code.
+ *
+ * @param   pReq        Pointer to the VMMDevReqMousePointer structure.
+ */
+VBGLR3DECL(int) VbglR3SetPointerShapeReq(VMMDevReqMousePointer *pReq)
+{
+    int rc = vbglR3GRPerform(&pReq->header);
+    if (RT_SUCCESS(rc))
+        rc = pReq->header.rc;
+    return rc;
+}
+
+
+/**
+ * Query the last display change request sent from the host to the guest.
+ *
+ * @returns iprt status value
+ * @param   pcx         Where to store the horizontal pixel resolution
+ * @param   pcy         Where to store the vertical pixel resolution
+ *                      requested (a value of zero means do not change).
+ * @param   pcBits      Where to store the bits per pixel requested (a value
+ *                      of zero means do not change).
+ * @param   piDisplay   Where to store the display number the request was for
+ *                      - 0 for the primary display, 1 for the first
+ *                      secondary display, etc.
+ * @param   fAck        whether or not to acknowledge the newest request sent by
+ *                      the host.  If this is set, the function will return the
+ *                      most recent host request, otherwise it will return the
+ *                      last request to be acknowledged.
+ *
+ */
+static int getDisplayChangeRequest2(uint32_t *pcx, uint32_t *pcy,
+                                    uint32_t *pcBits, uint32_t *piDisplay,
+                                    bool fAck)
+{
+    VMMDevDisplayChangeRequest2 Req;
+
+    AssertPtrReturn(pcx, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(pcy, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(pcBits, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(piDisplay, VERR_INVALID_PARAMETER);
+    RT_ZERO(Req);
+    vmmdevInitRequest(&Req.header, VMMDevReq_GetDisplayChangeRequest2);
+    if (fAck)
+        Req.eventAck = VMMDEV_EVENT_DISPLAY_CHANGE_REQUEST;
+    int rc = vbglR3GRPerform(&Req.header);
+    if (RT_SUCCESS(rc))
+        rc = Req.header.rc;
+    if (RT_SUCCESS(rc))
+    {
+        *pcx = Req.xres;
+        *pcy = Req.yres;
+        *pcBits = Req.bpp;
+        *piDisplay = Req.display;
+    }
+    return rc;
+}
+
+
+/**
+ * Query the last display change request sent from the host to the guest.
+ *
+ * @returns iprt status value
+ * @param   pcx         Where to store the horizontal pixel resolution
+ *                      requested (a value of zero means do not change).
+ * @param   pcy         Where to store the vertical pixel resolution
+ *                      requested (a value of zero means do not change).
+ * @param   pcBits      Where to store the bits per pixel requested (a value
+ *                      of zero means do not change).
+ * @param   piDisplay   Where to store the display number the request was for
+ *                      - 0 for the primary display, 1 for the first
+ *                      secondary display, etc.
+ * @param   fAck        whether or not to acknowledge the newest request sent by
+ *                      the host.  If this is set, the function will return the
+ *                      most recent host request, otherwise it will return the
+ *                      last request to be acknowledged.
+ *
+ * @param   pdx         New horizontal position of the secondary monitor.
+ *                      Optional.
+ * @param   pdy         New vertical position of the secondary monitor.
+ *                      Optional.
+ * @param   pfEnabled   Secondary monitor is enabled or not. Optional.
+ * @param   pfChangeOrigin  Whether the mode hint retrieved included
+ *                      information about origin/display offset inside the
+ *                      frame-buffer. Optional.
+ *
+ */
+VBGLR3DECL(int) VbglR3GetDisplayChangeRequest(uint32_t *pcx, uint32_t *pcy,
+                                              uint32_t *pcBits,
+                                              uint32_t *piDisplay,
+                                              uint32_t *pdx, uint32_t *pdy,
+                                              bool *pfEnabled,
+                                              bool *pfChangeOrigin,
+                                              bool fAck)
+{
+    VMMDevDisplayChangeRequestEx Req;
+    int rc = VINF_SUCCESS;
+
+    AssertPtrReturn(pcx, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(pcy, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(pcBits, VERR_INVALID_PARAMETER);
+    AssertPtrNullReturn(pdx, VERR_INVALID_PARAMETER);
+    AssertPtrNullReturn(pdy, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(piDisplay, VERR_INVALID_PARAMETER);
+    AssertPtrNullReturn(pfEnabled, VERR_INVALID_PARAMETER);
+    AssertPtrNullReturn(pfChangeOrigin, VERR_INVALID_PARAMETER);
+
+    RT_ZERO(Req);
+    rc = vmmdevInitRequest(&Req.header, VMMDevReq_GetDisplayChangeRequestEx);
+    AssertRCReturn(rc, rc);
+    if (fAck)
+        Req.eventAck = VMMDEV_EVENT_DISPLAY_CHANGE_REQUEST;
+    rc = vbglR3GRPerform(&Req.header);
+    if (RT_SUCCESS(rc))
+        rc = Req.header.rc;
+    if (RT_SUCCESS(rc))
+    {
+        *pcx = Req.xres;
+        *pcy = Req.yres;
+        *pcBits = Req.bpp;
+        *piDisplay = Req.display;
+        if (pdx)
+            *pdx = Req.cxOrigin;
+        if (pdy)
+            *pdy = Req.cyOrigin;
+        if (pfEnabled)
+            *pfEnabled = Req.fEnabled;
+        if (pfChangeOrigin)
+            *pfChangeOrigin = Req.fChangeOrigin;
+        return VINF_SUCCESS;
+    }
+
+    /* NEEDS TESTING: test below with current Additions on VBox 4.1 or older. */
+    /** @todo Can we find some standard grep-able string for "NEEDS TESTING"? */
+    if (rc == VERR_NOT_IMPLEMENTED)  /* Fall back to the old API. */
+    {
+        if (pfEnabled)
+            *pfEnabled = true;
+        if (pfChangeOrigin)
+            *pfChangeOrigin = false;
+        return getDisplayChangeRequest2(pcx, pcy, pcBits, piDisplay, fAck);
+    }
+    return rc;
+}
+
+
+/**
+ * Query the last display change request sent from the host to the guest.
+ *
+ * @returns iprt status value
+ * @param   cDisplaysIn   How many elements in the paDisplays array.
+ * @param   pcDisplaysOut How many elements were returned.
+ * @param   paDisplays    Display information.
+ * @param   fAck          Whether or not to acknowledge the newest request sent by
+ *                        the host.  If this is set, the function will return the
+ *                        most recent host request, otherwise it will return the
+ *                        last request to be acknowledged.
+ */
+VBGLR3DECL(int) VbglR3GetDisplayChangeRequestMulti(uint32_t cDisplaysIn,
+                                                   uint32_t *pcDisplaysOut,
+                                                   VMMDevDisplayDef *paDisplays,
+                                                   bool fAck)
+{
+    VMMDevDisplayChangeRequestMulti *pReq;
+    size_t cbDisplays;
+    size_t cbAlloc;
+    int rc = VINF_SUCCESS;
+
+    AssertReturn(cDisplaysIn > 0 && cDisplaysIn <= 64 /* VBOX_VIDEO_MAX_SCREENS */, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(pcDisplaysOut, VERR_INVALID_PARAMETER);
+    AssertPtrReturn(paDisplays, VERR_INVALID_PARAMETER);
+
+    cbDisplays = cDisplaysIn * sizeof(VMMDevDisplayDef);
+    cbAlloc = RT_UOFFSETOF(VMMDevDisplayChangeRequestMulti, aDisplays) + cbDisplays;
+    pReq = (VMMDevDisplayChangeRequestMulti *)RTMemTmpAlloc(cbAlloc);
+    AssertPtrReturn(pReq, VERR_NO_MEMORY);
+
+    memset(pReq, 0, cbAlloc);
+    rc = vmmdevInitRequest(&pReq->header, VMMDevReq_GetDisplayChangeRequestMulti);
+    AssertRCReturnStmt(rc, RTMemTmpFree(pReq), rc);
+
+    pReq->header.size += (uint32_t)cbDisplays;
+    pReq->cDisplays = cDisplaysIn;
+    if (fAck)
+        pReq->eventAck = VMMDEV_EVENT_DISPLAY_CHANGE_REQUEST;
+
+    rc = vbglR3GRPerform(&pReq->header);
+    AssertRCReturnStmt(rc, RTMemTmpFree(pReq), rc);
+
+    rc = pReq->header.rc;
+    if (RT_SUCCESS(rc))
+    {
+        memcpy(paDisplays, pReq->aDisplays, pReq->cDisplays * sizeof(VMMDevDisplayDef));
+        *pcDisplaysOut = pReq->cDisplays;
+    }
+
+    RTMemTmpFree(pReq);
+    return rc;
+}
+
+
+/**
+ * Query the host as to whether it likes a specific video mode.
+ *
+ * @returns the result of the query
+ * @param   cx     the width of the mode being queried
+ * @param   cy     the height of the mode being queried
+ * @param   cBits  the bpp of the mode being queried
+ */
+VBGLR3DECL(bool) VbglR3HostLikesVideoMode(uint32_t cx, uint32_t cy, uint32_t cBits)
+{
+    bool fRc = true;  /* If for some reason we can't contact the host then
+                       * we like everything. */
+    int rc;
+    VMMDevVideoModeSupportedRequest req;
+
+    vmmdevInitRequest(&req.header, VMMDevReq_VideoModeSupported);
+    req.width      = cx;
+    req.height     = cy;
+    req.bpp        = cBits;
+    req.fSupported = true;
+    rc = vbglR3GRPerform(&req.header);
+    if (RT_SUCCESS(rc) && RT_SUCCESS(req.header.rc))
+        fRc = req.fSupported;
+    return fRc;
+}
+
+/**
+ * Get the highest screen number for which there is a saved video mode or "0"
+ * if there are no saved modes.
+ *
+ * @returns iprt status value
+ * @returns VERR_NOT_SUPPORTED if the guest property service is not available.
+ * @param   pcScreen   where to store the virtual screen number
+ */
+VBGLR3DECL(int) VbglR3VideoModeGetHighestSavedScreen(unsigned *pcScreen)
+{
+#if defined(VBOX_WITH_GUEST_PROPS)
+    int rc;
+    HGCMCLIENTID idClient = 0;
+    PVBGLR3GUESTPROPENUM pHandle = NULL;
+    const char *pszName = NULL;
+    unsigned cHighestScreen = 0;
+
+    /* Validate input. */
+    AssertPtrReturn(pcScreen, VERR_INVALID_POINTER);
+
+    /* Query the data. */
+    rc = VbglR3GuestPropConnect(&idClient);
+    if (RT_SUCCESS(rc))
+    {
+        const char *pszPattern = VIDEO_PROP_PREFIX"*";
+        rc = VbglR3GuestPropEnum(idClient, &pszPattern, 1, &pHandle, &pszName, NULL, NULL, NULL);
+        int rc2 = VbglR3GuestPropDisconnect(idClient);
+        if (RT_FAILURE(rc2) && RT_SUCCESS(rc))
+            rc = rc2;
+    }
+
+    /* Process the data. */
+    while (RT_SUCCESS(rc) && pszName != NULL)
+    {
+        uint32_t cScreen;
+
+        rc = RTStrToUInt32Full(pszName + sizeof(VIDEO_PROP_PREFIX) - 1, 10, &cScreen);
+        if (RT_SUCCESS(rc))  /* There may be similar properties with text. */
+            cHighestScreen = RT_MAX(cHighestScreen, cScreen);
+        rc = VbglR3GuestPropEnumNext(pHandle, &pszName, NULL, NULL, NULL);
+    }
+
+    VbglR3GuestPropEnumFree(pHandle);
+
+    /* Return result. */
+    if (RT_SUCCESS(rc))
+        *pcScreen = cHighestScreen;
+    return rc;
+#else /* !VBOX_WITH_GUEST_PROPS */
+    RT_NOREF(pcScreen);
+    return VERR_NOT_SUPPORTED;
+#endif /* !VBOX_WITH_GUEST_PROPS */
+}
+
+/**
+ * Save video mode parameters to the guest property store.
+ *
+ * @returns iprt status value
+ * @param   idScreen  The virtual screen number.
+ * @param   cx        mode width
+ * @param   cy        mode height
+ * @param   cBits     bits per pixel for the mode
+ * @param   x         virtual screen X offset
+ * @param   y         virtual screen Y offset
+ * @param   fEnabled  is this virtual screen enabled?
+ */
+VBGLR3DECL(int) VbglR3SaveVideoMode(unsigned idScreen, unsigned cx, unsigned cy, unsigned cBits,
+                                    unsigned x, unsigned y, bool fEnabled)
+{
+#ifdef VBOX_WITH_GUEST_PROPS
+    unsigned cHighestScreen = 0;
+    int rc = VbglR3VideoModeGetHighestSavedScreen(&cHighestScreen);
+    if (RT_SUCCESS(rc))
+    {
+        HGCMCLIENTID idClient = 0;
+        rc = VbglR3GuestPropConnect(&idClient);
+        if (RT_SUCCESS(rc))
+        {
+            int rc2;
+            char szModeName[GUEST_PROP_MAX_NAME_LEN];
+            char szModeParms[GUEST_PROP_MAX_VALUE_LEN];
+            RTStrPrintf(szModeName, sizeof(szModeName), VIDEO_PROP_PREFIX "%u", idScreen);
+            RTStrPrintf(szModeParms, sizeof(szModeParms), "%ux%ux%u,%ux%u,%u", cx, cy, cBits, x, y, (unsigned) fEnabled);
+
+            rc = VbglR3GuestPropWriteValue(idClient, szModeName, szModeParms);
+            /* Write out the mode using the legacy name too, in case the user
+             * re-installs older Additions. */
+            if (idScreen == 0)
+            {
+                RTStrPrintf(szModeParms, sizeof(szModeParms), "%ux%ux%u", cx, cy, cBits);
+                VbglR3GuestPropWriteValue(idClient, VIDEO_PROP_PREFIX "SavedMode", szModeParms);
+            }
+
+            rc2 = VbglR3GuestPropDisconnect(idClient);
+            if (rc != VINF_PERMISSION_DENIED)
+            {
+                if (RT_SUCCESS(rc))
+                    rc = rc2;
+                if (RT_SUCCESS(rc))
+                {
+                    /* Sanity check 1.  We do not try to make allowance for someone else
+                     * changing saved settings at the same time as us. */
+                    bool     fEnabled2 = false;
+                    unsigned cx2       = 0;
+                    unsigned cy2       = 0;
+                    unsigned cBits2    = 0;
+                    unsigned x2        = 0;
+                    unsigned y2        = 0;
+                    rc = VbglR3RetrieveVideoMode(idScreen, &cx2, &cy2, &cBits2, &x2, &y2, &fEnabled2);
+                    if (   RT_SUCCESS(rc)
+                        && (cx != cx2 || cy != cy2 || cBits != cBits2 || x != x2 || y != y2 || fEnabled != fEnabled2))
+                        rc = VERR_WRITE_ERROR;
+                    /* Sanity check 2.  Same comment. */
+                    else if (RT_SUCCESS(rc))
+                    {
+                        unsigned cHighestScreen2 = 0;
+                        rc = VbglR3VideoModeGetHighestSavedScreen(&cHighestScreen2);
+                        if (RT_SUCCESS(rc))
+                            if (cHighestScreen2 != RT_MAX(cHighestScreen, idScreen))
+                                rc = VERR_INTERNAL_ERROR;
+                    }
+                }
+            }
+        }
+    }
+    return rc;
+#else /* !VBOX_WITH_GUEST_PROPS */
+    RT_NOREF(idScreen, cx, cy, cBits, x, y, fEnabled);
+    return VERR_NOT_SUPPORTED;
+#endif /* !VBOX_WITH_GUEST_PROPS */
+}
+
+
+/**
+ * Retrieve video mode parameters from the guest property store.
+ *
+ * @returns iprt status value
+ * @param   idScreen   The virtual screen number.
+ * @param   pcx        where to store the mode width
+ * @param   pcy        where to store the mode height
+ * @param   pcBits     where to store the bits per pixel for the mode
+ * @param   px         where to store the virtual screen X offset
+ * @param   py         where to store the virtual screen Y offset
+ * @param   pfEnabled  where to store whether this virtual screen is enabled
+ */
+VBGLR3DECL(int) VbglR3RetrieveVideoMode(unsigned idScreen,
+                                        unsigned *pcx, unsigned *pcy,
+                                        unsigned *pcBits,
+                                        unsigned *px, unsigned *py,
+                                        bool *pfEnabled)
+{
+#ifdef VBOX_WITH_GUEST_PROPS
+    /*
+     * First we retrieve the video mode which is saved as a string in the
+     * guest property store.
+     */
+    HGCMCLIENTID idClient = 0;
+    int rc = VbglR3GuestPropConnect(&idClient);
+    if (RT_SUCCESS(rc))
+    {
+        int rc2;
+        /* The buffer for VbglR3GuestPropReadValue.  If this is too small then
+         * something is wrong with the data stored in the property. */
+        char szModeParms[1024];
+        char szModeName[GUEST_PROP_MAX_NAME_LEN]; /** @todo add a VbglR3GuestPropReadValueF/FV that does the RTStrPrintf for you. */
+        RTStrPrintf(szModeName, sizeof(szModeName), VIDEO_PROP_PREFIX "%u", idScreen);
+        rc = VbglR3GuestPropReadValue(idClient, szModeName, szModeParms, sizeof(szModeParms), NULL);
+        /* Try legacy single screen name. */
+        if (rc == VERR_NOT_FOUND && idScreen == 0)
+            rc = VbglR3GuestPropReadValue(idClient,
+                                          VIDEO_PROP_PREFIX"SavedMode",
+                                          szModeParms, sizeof(szModeParms),
+                                          NULL);
+        rc2 = VbglR3GuestPropDisconnect(idClient);
+        if (RT_SUCCESS(rc))
+            rc = rc2;
+
+        /*
+         * Now we convert the string returned to numeric values.
+         */
+        if (RT_SUCCESS(rc))
+        {
+            /* Mandatory chunk: 640x480x32 */
+            char       *pszNext;
+            uint32_t    cx = 0;
+            rc = VERR_PARSE_ERROR;
+            rc2 = RTStrToUInt32Ex(szModeParms, &pszNext, 10, &cx);
+            if (rc2 == VWRN_TRAILING_CHARS && *pszNext == 'x')
+            {
+                uint32_t cy = 0;
+                rc2 = RTStrToUInt32Ex(pszNext + 1, &pszNext, 10, &cy);
+                if (rc2 == VWRN_TRAILING_CHARS && *pszNext == 'x')
+                {
+                    uint8_t cBits = 0;
+                    rc2 = RTStrToUInt8Ex(pszNext + 1, &pszNext, 10, &cBits);
+                    if (rc2 == VINF_SUCCESS || rc2 == VWRN_TRAILING_CHARS)
+                    {
+                        /* Optional chunk: ,32x64,1  (we fail if this is partially there) */
+                        uint32_t x        = 0;
+                        uint32_t y        = 0;
+                        uint8_t  fEnabled = 1;
+                        if (rc2 == VINF_SUCCESS)
+                            rc = VINF_SUCCESS;
+                        else if (*pszNext == ',')
+                        {
+                            rc2 = RTStrToUInt32Ex(pszNext + 1, &pszNext, 10, &x);
+                            if (rc2 == VWRN_TRAILING_CHARS && *pszNext == 'x')
+                            {
+                                rc2 = RTStrToUInt32Ex(pszNext + 1, &pszNext, 10, &y);
+                                if (rc2 == VWRN_TRAILING_CHARS && *pszNext == ',')
+                                {
+                                    rc2 = RTStrToUInt8Ex(pszNext + 1, &pszNext, 10, &fEnabled);
+                                    if (rc2 == VINF_SUCCESS)
+                                        rc = VINF_SUCCESS;
+                                }
+                            }
+                        }
+
+                        /*
+                         * Set result if successful.
+                         */
+                        if (rc == VINF_SUCCESS)
+                        {
+                            if (pcx)
+                                *pcx = cx;
+                            if (pcy)
+                                *pcy = cy;
+                            if (pcBits)
+                                *pcBits = cBits;
+                            if (px)
+                                *px = x;
+                            if (py)
+                                *py = y;
+                            if (pfEnabled)
+                                *pfEnabled = RT_BOOL(fEnabled);
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    return rc;
+#else /* !VBOX_WITH_GUEST_PROPS */
+    RT_NOREF(idScreen, pcx, pcy, pcBits, px, py, pfEnabled);
+    return VERR_NOT_SUPPORTED;
+#endif /* !VBOX_WITH_GUEST_PROPS */
+}
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibVrdp.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibVrdp.cpp
new file mode 100644
index 00000000..89a19d09
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibVrdp.cpp
@@ -0,0 +1,64 @@
+/* $Id: VBoxGuestR3LibVrdp.cpp $ */
+/** @file
+ * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, VRDP.
+ */
+
+/*
+ * Copyright (C) 2007-2023 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 <iprt/time.h>
+#include <iprt/string.h>
+#include "VBoxGuestR3LibInternal.h"
+
+
+VBGLR3DECL(int) VbglR3VrdpGetChangeRequest(bool *pfActive, uint32_t *puExperienceLevel)
+{
+    VMMDevVRDPChangeRequest Req;
+    RT_ZERO(Req); /* implicit padding */
+    vmmdevInitRequest(&Req.header, VMMDevReq_GetVRDPChangeRequest); //VMMDEV_REQ_HDR_INIT(&Req.header, sizeof(Req), VMMDevReq_GetVRDPChangeRequest);
+    int rc = vbglR3GRPerform(&Req.header);
+    if (RT_SUCCESS(rc))
+    {
+        *pfActive          = Req.u8VRDPActive != 0;
+        *puExperienceLevel = Req.u32VRDPExperienceLevel;
+    }
+    else
+    {
+        *pfActive          = false;
+        *puExperienceLevel = 0;
+    }
+    return rc;
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/VbglR0CanUsePhysPageList.cpp b/src/VBox/Additions/common/VBoxGuest/lib/VbglR0CanUsePhysPageList.cpp
new file mode 100644
index 00000000..38646784
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/VbglR0CanUsePhysPageList.cpp
@@ -0,0 +1,52 @@
+/* $Id: VbglR0CanUsePhysPageList.cpp $ */
+/** @file
+ * VBoxGuestLibR0 - Physical memory heap.
+ */
+
+/*
+ * Copyright (C) 2006-2023 Oracle and/or its affiliates.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include "VBoxGuestR0LibInternal.h"
+
+
+/**
+ * Checks whether the host supports physical page lists or not.
+ *
+ * @returns true if it does, false if it doesn't.
+ */
+DECLR0VBGL(bool) VbglR0CanUsePhysPageList(void)
+{
+    /* a_fLocked is false, because the actual capability of the host is requested.
+     * See VBGLR0_CAN_USE_PHYS_PAGE_LIST definition.
+     */
+    int rc = vbglR0Enter();
+    return RT_SUCCESS(rc)
+        && VBGLR0_CAN_USE_PHYS_PAGE_LIST(/*a_fLocked =*/ false);
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/testcase/Makefile.kmk b/src/VBox/Additions/common/VBoxGuest/lib/testcase/Makefile.kmk
new file mode 100644
index 00000000..6d99a40f
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/testcase/Makefile.kmk
@@ -0,0 +1,52 @@
+# $Id: Makefile.kmk $
+## @file
+# Sub-Makefile for the common guest addition code library testcases.
+#
+
+#
+# Copyright (C) 2022-2023 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
+#
+
+SUB_DEPTH = ../../../../../../..
+include $(KBUILD_PATH)/subheader.kmk
+if defined(VBOX_WITH_TESTCASES) && !defined(VBOX_ONLY_BUILD)
+
+ #
+ # Testcase for the physical heap.
+ #
+ PROGRAMS += tstVbglR0PhysHeap-1
+ tstVbglR0PhysHeap-1_TEMPLATE = VBoxR3TstExe
+ tstVbglR0PhysHeap-1_SOURCES = \
+ 	tstVbglR0PhysHeap-1.cpp
+
+
+endif # defined(VBOX_WITH_TESTCASES) && !defined(VBOX_ONLY_BUILD)
+include $(FILE_KBUILD_SUB_FOOTER)
+
diff --git a/src/VBox/Additions/common/VBoxGuest/lib/testcase/tstVbglR0PhysHeap-1.cpp b/src/VBox/Additions/common/VBoxGuest/lib/testcase/tstVbglR0PhysHeap-1.cpp
new file mode 100644
index 00000000..3646fd95
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/lib/testcase/tstVbglR0PhysHeap-1.cpp
@@ -0,0 +1,415 @@
+/* $Id: tstVbglR0PhysHeap-1.cpp $ */
+/** @file
+ * IPRT Testcase - Offset Based Heap.
+ */
+
+/*
+ * 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 <iprt/assert.h>
+#include <iprt/errcore.h>
+#include <iprt/initterm.h>
+#include <iprt/log.h>
+#include <iprt/mem.h>
+#include <iprt/rand.h>
+#include <iprt/stream.h>
+#include <iprt/string.h>
+#include <iprt/param.h>
+#include <iprt/test.h>
+#include <iprt/time.h>
+
+#define IN_TESTCASE
+#define IN_RING0 /* pretend we're in ring-0 so we get access to the functions */
+#include "../VBoxGuestR0LibInternal.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+typedef struct
+{
+    uint32_t cb;
+    void    *pv;
+} TSTHISTORYENTRY;
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+VBGLDATA g_vbgldata;
+
+int      g_cChunks  = 0;
+size_t   g_cbChunks = 0;
+
+/** Drop-in replacement for RTMemContAlloc   */
+static void *tstMemContAlloc(PRTCCPHYS pPhys, size_t cb)
+{
+    RTTESTI_CHECK(cb > 0);
+
+#define TST_MAX_CHUNKS 24
+    if (g_cChunks < TST_MAX_CHUNKS)
+    {
+        void *pvRet = RTMemAlloc(cb);
+        if (pvRet)
+        {
+            g_cChunks++;
+            g_cbChunks += cb;
+            *pPhys = (uint32_t)(uintptr_t)pvRet ^ (UINT32_C(0xf0f0f0f0) & ~(uint32_t)PAGE_OFFSET_MASK);
+
+            /* Avoid problematic values that won't happen in real life:  */
+            if (!*pPhys)
+                *pPhys = 4U << PAGE_SHIFT;
+            if (UINT32_MAX - *pPhys < cb)
+                *pPhys -= RT_ALIGN_32(cb, PAGE_SIZE);
+
+            return pvRet;
+        }
+    }
+
+    *pPhys = NIL_RTCCPHYS;
+    return NULL;
+}
+
+
+/** Drop-in replacement for RTMemContFree   */
+static void tstMemContFree(void *pv, size_t cb)
+{
+    RTTESTI_CHECK(RT_VALID_PTR(pv));
+    RTTESTI_CHECK(cb > 0);
+    RTTESTI_CHECK(g_cChunks > 0);
+    RTMemFree(pv);
+    g_cChunks--;
+    g_cbChunks -= cb;
+}
+
+
+#define RTMemContAlloc  tstMemContAlloc
+#define RTMemContFree   tstMemContFree
+#include "../VBoxGuestR0LibPhysHeap.cpp"
+
+
+static void PrintStats(TSTHISTORYENTRY const *paHistory, size_t cHistory, const char *pszDesc)
+{
+    size_t   cbAllocated  = 0;
+    unsigned cLargeBlocks = 0;
+    unsigned cAllocated   = 0;
+    for (size_t i = 0; i < cHistory; i++)
+        if (paHistory[i].pv)
+        {
+            cAllocated   += 1;
+            cbAllocated  += paHistory[i].cb;
+            cLargeBlocks += paHistory[i].cb > _1K;
+        }
+
+    size_t const cbOverhead      = g_cChunks * sizeof(VBGLPHYSHEAPCHUNK) + cAllocated * sizeof(VBGLPHYSHEAPBLOCK);
+    size_t const cbFragmentation = g_cbChunks - cbOverhead - cbAllocated;
+    RTTestIPrintf(RTTESTLVL_ALWAYS,
+                  "%s: %'9zu bytes in %2d chunks; %'9zu bytes in %4u blocks (%2u large)\n"
+                  " => int-frag  %'9zu (%2zu.%1zu%%)    overhead %'9zu (%1zu.%02zu%%)\n",
+                  pszDesc,
+                  g_cbChunks, g_cChunks,
+                  cbAllocated, cAllocated, cLargeBlocks,
+                  cbFragmentation, cbFragmentation * 100 / g_cbChunks, (cbFragmentation * 1000 / g_cbChunks) % 10,
+                  cbOverhead, cbOverhead * 100 / g_cbChunks, (cbOverhead * 10000 / g_cbChunks) % 100);
+}
+
+
+int main(int argc, char **argv)
+{
+    RT_NOREF_PV(argc); RT_NOREF_PV(argv);
+
+    /*
+     * Init runtime.
+     */
+    RTTEST hTest;
+    int rc = RTTestInitAndCreate("tstVbglR0PhysHeap-1", &hTest);
+    if (rc)
+        return rc;
+    RTTestBanner(hTest);
+
+    /*
+     * Arguments are taken to be random seeding.
+     */
+    uint64_t uRandSeed = RTTimeNanoTS();
+    for (int i = 1; i < argc; i++)
+    {
+        rc = RTStrToUInt64Full(argv[i], 0, &uRandSeed);
+        if (rc != VINF_SUCCESS)
+        {
+            RTTestIFailed("Invalid parameter: %Rrc: %s\n", rc, argv[i]);
+            return RTTestSummaryAndDestroy(hTest);
+        }
+    }
+
+    /*
+     * Create a heap.
+     */
+    RTTestSub(hTest, "Basics");
+    RTTESTI_CHECK_RC(rc = VbglR0PhysHeapInit(), VINF_SUCCESS);
+    if (RT_FAILURE(rc))
+        return RTTestSummaryAndDestroy(hTest);
+    RTTESTI_CHECK_RC_OK(VbglR0PhysHeapCheck(NULL));
+
+#define CHECK_PHYS_ADDR(a_pv) do { \
+        uint32_t const uPhys = VbglR0PhysHeapGetPhysAddr(a_pv); \
+        if (uPhys == 0 || uPhys == UINT32_MAX || (uPhys & PAGE_OFFSET_MASK) != ((uintptr_t)(a_pv) & PAGE_OFFSET_MASK)) \
+            RTTestIFailed("line %u: %s=%p: uPhys=%#x\n", __LINE__, #a_pv, (a_pv), uPhys); \
+    } while (0)
+
+    /*
+     * Try allocate.
+     */
+    static struct TstPhysHeapOps
+    {
+        uint32_t    cb;
+        unsigned    iFreeOrder;
+        void       *pvAlloc;
+    } s_aOps[] =
+    {
+        {        16,  0,  NULL },  // 0
+        {        16,  1,  NULL },
+        {        16,  2,  NULL },
+        {        16,  5,  NULL },
+        {        16,  4,  NULL },
+        {        32,  3,  NULL },  // 5
+        {        31,  6,  NULL },
+        {      1024,  8,  NULL },
+        {      1024, 10,  NULL },
+        {      1024, 12,  NULL },
+        { PAGE_SIZE, 13,  NULL },  // 10
+        {      1024,  9,  NULL },
+        { PAGE_SIZE, 11,  NULL },
+        { PAGE_SIZE, 14,  NULL },
+        {        16, 15,  NULL },
+        {         9,  7,  NULL },  // 15
+        {        16,  7,  NULL },
+        {        36,  7,  NULL },
+        {        16,  7,  NULL },
+        {     12344,  7,  NULL },
+        {        50,  7,  NULL },  // 20
+        {        16,  7,  NULL },
+    };
+    uint32_t i;
+    //RTHeapOffsetDump(Heap, (PFNRTHEAPOFFSETPRINTF)(uintptr_t)RTPrintf); /** @todo Add some detail info output with a signature identical to RTPrintf. */
+    //size_t cbBefore = VbglR0PhysHeapGetFreeSize();
+    static char const s_szFill[] = "01234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
+
+    /* allocate */
+    for (i = 0; i < RT_ELEMENTS(s_aOps); i++)
+    {
+        s_aOps[i].pvAlloc = VbglR0PhysHeapAlloc(s_aOps[i].cb);
+        RTTESTI_CHECK_MSG(s_aOps[i].pvAlloc, ("VbglR0PhysHeapAlloc(%#x) -> NULL i=%d\n", s_aOps[i].cb, i));
+        if (!s_aOps[i].pvAlloc)
+            return RTTestSummaryAndDestroy(hTest);
+
+        memset(s_aOps[i].pvAlloc, s_szFill[i], s_aOps[i].cb);
+        RTTESTI_CHECK_MSG(RT_ALIGN_P(s_aOps[i].pvAlloc, sizeof(void *)) == s_aOps[i].pvAlloc,
+                          ("VbglR0PhysHeapAlloc(%#x) -> %p\n", s_aOps[i].cb, i));
+
+        CHECK_PHYS_ADDR(s_aOps[i].pvAlloc);
+
+        /* Check heap integrity: */
+        RTTESTI_CHECK_RC_OK(VbglR0PhysHeapCheck(NULL));
+    }
+
+    /* free and allocate the same node again. */
+    for (i = 0; i < RT_ELEMENTS(s_aOps); i++)
+    {
+        if (!s_aOps[i].pvAlloc)
+            continue;
+        //RTPrintf("debug: i=%d pv=%#x cb=%#zx align=%#zx cbReal=%#zx\n", i, s_aOps[i].pvAlloc,
+        //         s_aOps[i].cb, s_aOps[i].uAlignment, RTHeapOffsetSize(Heap, s_aOps[i].pvAlloc));
+        size_t cbBeforeSub = VbglR0PhysHeapGetFreeSize();
+        VbglR0PhysHeapFree(s_aOps[i].pvAlloc);
+        size_t cbAfterSubFree = VbglR0PhysHeapGetFreeSize();
+        RTTESTI_CHECK_RC_OK(VbglR0PhysHeapCheck(NULL));
+
+        void *pv;
+        pv = VbglR0PhysHeapAlloc(s_aOps[i].cb);
+        RTTESTI_CHECK_MSG(pv, ("VbglR0PhysHeapAlloc(%#x) -> NULL i=%d\n", s_aOps[i].cb, i));
+        if (!pv)
+            return RTTestSummaryAndDestroy(hTest);
+        CHECK_PHYS_ADDR(pv);
+        RTTESTI_CHECK_RC_OK(VbglR0PhysHeapCheck(NULL));
+
+        //RTPrintf("debug: i=%d pv=%p cbReal=%#zx cbBeforeSub=%#zx cbAfterSubFree=%#zx cbAfterSubAlloc=%#zx \n", i, pv, RTHeapOffsetSize(Heap, pv),
+        //         cbBeforeSub, cbAfterSubFree, VbglR0PhysHeapGetFreeSize());
+
+        if (pv != s_aOps[i].pvAlloc)
+            RTTestIPrintf(RTTESTLVL_ALWAYS, "Warning: Free+Alloc returned different address. new=%p old=%p i=%d\n", pv, s_aOps[i].pvAlloc, i);
+        s_aOps[i].pvAlloc = pv;
+        size_t cbAfterSubAlloc = VbglR0PhysHeapGetFreeSize();
+        if (cbBeforeSub != cbAfterSubAlloc)
+        {
+            RTTestIPrintf(RTTESTLVL_ALWAYS, "Warning: cbBeforeSub=%#zx cbAfterSubFree=%#zx cbAfterSubAlloc=%#zx. i=%d\n",
+                          cbBeforeSub, cbAfterSubFree, cbAfterSubAlloc, i);
+            //return 1; - won't work correctly until we start creating free block instead of donating memory on alignment.
+        }
+    }
+
+    VbglR0PhysHeapTerminate();
+    RTTESTI_CHECK_MSG(g_cChunks == 0, ("g_cChunks=%d\n", g_cChunks));
+
+
+    /*
+     * Use random allocation pattern
+     */
+    RTTestSub(hTest, "Random Test");
+    RTTESTI_CHECK_RC(rc = VbglR0PhysHeapInit(), VINF_SUCCESS);
+    if (RT_FAILURE(rc))
+        return RTTestSummaryAndDestroy(hTest);
+
+    RTRAND hRand;
+    RTTESTI_CHECK_RC(rc = RTRandAdvCreateParkMiller(&hRand), VINF_SUCCESS);
+    if (RT_FAILURE(rc))
+        return RTTestSummaryAndDestroy(hTest);
+    RTRandAdvSeed(hRand, uRandSeed);
+    RTTestValue(hTest, "RandSeed", uRandSeed, RTTESTUNIT_NONE);
+
+    static TSTHISTORYENTRY s_aHistory[3072];
+    RT_ZERO(s_aHistory);
+
+    for (unsigned iTest = 0; iTest < 131072; iTest++)
+    {
+        i = RTRandAdvU32Ex(hRand, 0, RT_ELEMENTS(s_aHistory) - 1);
+        if (!s_aHistory[i].pv)
+        {
+            s_aHistory[i].cb = RTRandAdvU32Ex(hRand, 8, 1024);
+            s_aHistory[i].pv = VbglR0PhysHeapAlloc(s_aHistory[i].cb);
+            if (!s_aHistory[i].pv)
+            {
+                s_aHistory[i].cb = 9;
+                s_aHistory[i].pv = VbglR0PhysHeapAlloc(s_aHistory[i].cb);
+            }
+            if (s_aHistory[i].pv)
+            {
+                memset(s_aHistory[i].pv, 0xbb, s_aHistory[i].cb);
+                CHECK_PHYS_ADDR(s_aHistory[i].pv);
+            }
+        }
+        else
+        {
+            VbglR0PhysHeapFree(s_aHistory[i].pv);
+            s_aHistory[i].pv = NULL;
+        }
+
+#if 1
+        /* Check heap integrity: */
+        RTTESTI_CHECK_RC_OK(VbglR0PhysHeapCheck(NULL));
+        int cChunks = 0;
+        for (VBGLPHYSHEAPCHUNK *pCurChunk = g_vbgldata.pChunkHead; pCurChunk; pCurChunk = pCurChunk->pNext)
+            cChunks++;
+        RTTESTI_CHECK_MSG(cChunks == g_cChunks, ("g_cChunks=%u, but only %u chunks in the list!\n", g_cChunks, cChunks));
+#endif
+
+        if ((iTest % 7777) == 7776)
+        {
+            /* exhaust the heap */
+            PrintStats(s_aHistory, RT_ELEMENTS(s_aHistory), "Exhaust-pre ");
+
+            for (i = 0; i < RT_ELEMENTS(s_aHistory) && (VbglR0PhysHeapGetFreeSize() >= 256 || g_cChunks < TST_MAX_CHUNKS); i++)
+                if (!s_aHistory[i].pv)
+                {
+                    s_aHistory[i].cb = RTRandAdvU32Ex(hRand, VBGL_PH_CHUNKSIZE / 8, VBGL_PH_CHUNKSIZE / 2 + VBGL_PH_CHUNKSIZE / 4);
+                    s_aHistory[i].pv = VbglR0PhysHeapAlloc(s_aHistory[i].cb);
+                    if (s_aHistory[i].pv)
+                    {
+                        memset(s_aHistory[i].pv, 0x55, s_aHistory[i].cb);
+                        CHECK_PHYS_ADDR(s_aHistory[i].pv);
+                    }
+                }
+
+            size_t cbFree = VbglR0PhysHeapGetFreeSize();
+            if (cbFree)
+                for (i = 0; i < RT_ELEMENTS(s_aHistory); i++)
+                    if (!s_aHistory[i].pv)
+                    {
+                        s_aHistory[i].cb = RTRandAdvU32Ex(hRand, 1, (uint32_t)cbFree);
+                        s_aHistory[i].pv = VbglR0PhysHeapAlloc(s_aHistory[i].cb);
+                        while (s_aHistory[i].pv == NULL && s_aHistory[i].cb > 2)
+                        {
+                            s_aHistory[i].cb >>= 1;
+                            s_aHistory[i].pv = VbglR0PhysHeapAlloc(s_aHistory[i].cb);
+                        }
+                        if (s_aHistory[i].pv)
+                        {
+                            memset(s_aHistory[i].pv, 0x55, s_aHistory[i].cb);
+                            CHECK_PHYS_ADDR(s_aHistory[i].pv);
+                        }
+
+                        cbFree = VbglR0PhysHeapGetFreeSize();
+                        if (!cbFree)
+                            break;
+                    }
+
+            RTTESTI_CHECK_MSG(VbglR0PhysHeapGetFreeSize() == 0, ("%zu\n", VbglR0PhysHeapGetFreeSize()));
+            PrintStats(s_aHistory, RT_ELEMENTS(s_aHistory), "Exhaust-post");
+        }
+        else if ((iTest % 7777) == 1111)
+        {
+            /* free all */
+            RTTestIPrintf(RTTESTLVL_ALWAYS, "Free-all-pre:  cFreeBlocks=%u cAllocedBlocks=%u in %u chunk(s)\n",
+                          g_vbgldata.cFreeBlocks, g_vbgldata.cBlocks - g_vbgldata.cFreeBlocks, g_cChunks);
+            for (i = 0; i < RT_ELEMENTS(s_aHistory); i++)
+            {
+                VbglR0PhysHeapFree(s_aHistory[i].pv);
+                s_aHistory[i].pv = NULL;
+            }
+            RTTestIPrintf(RTTESTLVL_ALWAYS, "Free-all-post: cFreeBlocks=%u in %u chunk(s)\n", g_vbgldata.cFreeBlocks, g_cChunks);
+            RTTESTI_CHECK_MSG(g_cChunks == 1, ("g_cChunks=%d\n", g_cChunks));
+            RTTESTI_CHECK_MSG(g_vbgldata.cFreeBlocks == g_vbgldata.cBlocks,
+                              ("g_vbgldata.cFreeBlocks=%d cBlocks=%d\n", g_vbgldata.cFreeBlocks, g_vbgldata.cBlocks));
+
+            //size_t cbAfterRand = VbglR0PhysHeapGetFreeSize();
+            //RTTESTI_CHECK_MSG(cbAfterRand == cbAfter, ("cbAfterRand=%zu cbAfter=%zu\n", cbAfterRand, cbAfter));
+        }
+    }
+
+    /* free the rest. */
+    for (i = 0; i < RT_ELEMENTS(s_aHistory); i++)
+    {
+        VbglR0PhysHeapFree(s_aHistory[i].pv);
+        s_aHistory[i].pv = NULL;
+    }
+
+    RTTESTI_CHECK_MSG(g_cChunks == 1, ("g_cChunks=%d\n", g_cChunks));
+
+    VbglR0PhysHeapTerminate();
+    RTTESTI_CHECK_MSG(g_cChunks == 0, ("g_cChunks=%d\n", g_cChunks));
+
+    RTTESTI_CHECK_RC(rc = RTRandAdvDestroy(hRand), VINF_SUCCESS);
+    return RTTestSummaryAndDestroy(hTest);
+}
+
diff --git a/src/VBox/Additions/common/VBoxGuest/linux/Makefile b/src/VBox/Additions/common/VBoxGuest/linux/Makefile
new file mode 100644
index 00000000..65384f7f
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/linux/Makefile
@@ -0,0 +1,213 @@
+# $Id: Makefile $
+## @file
+# VirtualBox Guest Additions Module Makefile.
+#
+
+#
+# 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
+#
+
+# Linux kbuild sets this to our source directory if we are called from there
+obj ?= $(CURDIR)
+include $(obj)/Makefile-header.gmk
+VBOXGUEST_DIR = $(VBOX_MODULE_SRC_DIR)
+
+#VBOX_WITHOUT_COMBINED_SOURCES=1
+
+VBOXMOD_NAME = vboxguest
+VBOXMOD_OBJS = \
+	VBoxGuest-linux.o \
+	VBoxGuest-common.o
+ifndef VBOX_WITHOUT_COMBINED_SOURCES
+VBOXMOD_OBJS += \
+	common/string/strformatrt.o \
+	combined-agnostic.o \
+	combined-os-specific.o
+else  # VBOX_WITHOUT_COMBINED_SOURCES
+VBOXMOD_OBJS += \
+	VBoxGuestR0LibGenericRequest.o \
+	VBoxGuestR0LibHGCMInternal.o \
+	VBoxGuestR0LibInit.o \
+	VBoxGuestR0LibPhysHeap.o \
+	VBoxGuestR0LibVMMDev.o \
+	r0drv/alloc-r0drv.o \
+	r0drv/initterm-r0drv.o \
+	r0drv/memobj-r0drv.o \
+	r0drv/mpnotification-r0drv.o \
+	r0drv/powernotification-r0drv.o \
+	r0drv/linux/alloc-r0drv-linux.o \
+	r0drv/linux/assert-r0drv-linux.o \
+	r0drv/linux/initterm-r0drv-linux.o \
+	r0drv/linux/memobj-r0drv-linux.o \
+	r0drv/linux/memuserkernel-r0drv-linux.o \
+	r0drv/linux/mp-r0drv-linux.o \
+	r0drv/linux/mpnotification-r0drv-linux.o \
+	r0drv/linux/process-r0drv-linux.o \
+	r0drv/linux/semevent-r0drv-linux.o \
+	r0drv/linux/semeventmulti-r0drv-linux.o \
+	r0drv/linux/semfastmutex-r0drv-linux.o \
+	r0drv/linux/semmutex-r0drv-linux.o \
+	r0drv/linux/spinlock-r0drv-linux.o \
+	r0drv/linux/thread-r0drv-linux.o \
+	r0drv/linux/thread2-r0drv-linux.o \
+	r0drv/linux/time-r0drv-linux.o \
+	r0drv/linux/timer-r0drv-linux.o \
+	r0drv/linux/RTLogWriteDebugger-r0drv-linux.o \
+	r0drv/generic/semspinmutex-r0drv-generic.o \
+	common/alloc/alloc.o \
+	common/checksum/crc32.o \
+	common/err/RTErrConvertFromErrno.o \
+	common/err/RTErrConvertToErrno.o \
+	common/err/errinfo.o \
+	common/log/log.o \
+	common/log/logellipsis.o \
+	common/log/logrel.o \
+	common/log/logrelellipsis.o \
+	common/log/logcom.o \
+	common/log/logformat.o \
+	common/log/RTLogCreateEx.o \
+	common/misc/RTAssertMsg1Weak.o \
+	common/misc/RTAssertMsg2.o \
+	common/misc/RTAssertMsg2Add.o \
+	common/misc/RTAssertMsg2AddWeak.o \
+	common/misc/RTAssertMsg2AddWeakV.o \
+	common/misc/RTAssertMsg2Weak.o \
+	common/misc/RTAssertMsg2WeakV.o \
+	common/misc/assert.o \
+	common/misc/thread.o \
+	common/string/RTStrCat.o \
+	common/string/RTStrCmp.o \
+	common/string/RTStrCopy.o \
+	common/string/RTStrCopyEx.o \
+	common/string/RTStrCopyP.o \
+	common/string/RTStrEnd.o \
+	common/string/RTStrICmpAscii.o \
+	common/string/RTStrNICmpAscii.o \
+	common/string/RTStrNCmp.o \
+	common/string/RTStrNLen.o \
+	common/string/stringalloc.o \
+	common/string/strformat.o \
+	common/string/RTStrFormat.o \
+	common/string/strformatnum.o \
+	common/string/strformatrt.o \
+	common/string/strformattype.o \
+	common/string/strprintf.o \
+	common/string/strprintf-ellipsis.o \
+	common/string/strprintf2.o \
+	common/string/strprintf2-ellipsis.o \
+	common/string/strtonum.o \
+	common/string/utf-8.o \
+	common/table/avlpv.o \
+	common/time/time.o \
+	generic/RTAssertShouldPanic-generic.o \
+	generic/RTLogWriteStdErr-stub-generic.o \
+	generic/RTLogWriteStdOut-stub-generic.o \
+	generic/RTMpGetCoreCount-generic.o \
+	generic/RTSemEventWait-2-ex-generic.o \
+	generic/RTSemEventWaitNoResume-2-ex-generic.o \
+	generic/RTSemEventMultiWait-2-ex-generic.o \
+	generic/RTSemEventMultiWaitNoResume-2-ex-generic.o \
+	generic/rtStrFormatKernelAddress-generic.o \
+	generic/errvars-generic.o \
+	generic/mppresent-generic.o \
+	VBox/log-vbox.o \
+	VBox/logbackdoor.o \
+	VBox/RTLogWriteVmm-amd64-x86.o
+ ifeq ($(VBOX_KBUILD_TARGET_ARCH),amd64)
+VBOXMOD_OBJS += common/alloc/heapsimple.o
+ endif
+endif # VBOX_WITHOUT_COMBINED_SOURCES
+ifeq ($(VBOX_KBUILD_TARGET_ARCH),x86)
+VBOXMOD_OBJS += \
+	common/math/gcc/divdi3.o \
+	common/math/gcc/divmoddi4.o \
+	common/math/gcc/moddi3.o \
+	common/math/gcc/udivdi3.o \
+	common/math/gcc/udivmoddi4.o \
+	common/math/gcc/umoddi3.o \
+	common/math/gcc/qdivrem.o
+endif
+
+VBOXMOD_DEFS = \
+	VBOX \
+	RT_OS_LINUX \
+	IN_RING0 \
+	IN_RT_R0 \
+	IN_GUEST \
+	IN_GUEST_R0 \
+	IN_MODULE \
+	RT_WITH_VBOX \
+	VBGL_VBOXGUEST \
+	VBOX_WITH_HGCM
+ifeq ($(VBOX_KBUILD_TARGET_ARCH),amd64)
+VBOXMOD_DEFS += VBOX_WITH_64_BITS_GUESTS
+endif
+ifeq ($(KERN_VERSION),24)
+VBOXMOD_DEFS += EXPORT_SYMTAB
+endif
+
+VBOXMOD_INCL = \
+	$(VBOXGUEST_DIR) \
+	$(VBOXGUEST_DIR)include \
+	$(VBOXGUEST_DIR)r0drv/linux
+
+VBOXMOD_CFLAGS := $(call VBOX_GCC_CHECK_CC,-Wno-declaration-after-statement,-Wno-declaration-after-statement,,)
+VBOXMOD_CFLAGS += $(call VBOX_GCC_CHECK_CC,-fno-pie,-fno-pie,,)
+ifneq ($(KERN_VERSION),24)
+VBOXMOD_CFLAGS += -include $(VBOXGUEST_DIR)include/VBox/VBoxGuestMangling.h
+endif
+
+VBOXMOD_CLEAN = \
+	. \
+	linux \
+	r0drv \
+	generic \
+	r0drv/linux \
+	r0drv/generic \
+	VBox \
+	common/alloc \
+	common/err \
+	common/log \
+	common/math/gcc \
+	common/misc \
+	common/string \
+	common/table \
+	common/time
+
+include $(obj)/Makefile-footer.gmk
+
+check: $(VBOXMOD_NAME)
+	@if ! readelf -p __ksymtab_strings vboxguest.ko | grep -E "\[.*\]  *(RT|g_..*RT.*)"; then \
+	    echo "All exported IPRT symbols are properly renamed!"; \
+	 else \
+	    echo "error: Some exported IPRT symbols was not properly renamed! See above." >&2; \
+	    false; \
+	 fi
+
diff --git a/src/VBox/Additions/common/VBoxGuest/linux/Makefile.kup b/src/VBox/Additions/common/VBoxGuest/linux/Makefile.kup
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/linux/Makefile.kup
diff --git a/src/VBox/Additions/common/VBoxGuest/linux/combined-agnostic.c b/src/VBox/Additions/common/VBoxGuest/linux/combined-agnostic.c
new file mode 100644
index 00000000..8509f97f
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/linux/combined-agnostic.c
@@ -0,0 +1,189 @@
+/* $Id: combined-agnostic.c $ */
+/** @file
+ * VBoxGuest - Combine a bunch of OS agnostic sources into one compile unit.
+ */
+
+/*
+ * 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
+ */
+
+#define LOG_GROUP LOG_GROUP_DEFAULT
+#include "internal/iprt.h"
+#include <VBox/log.h>
+
+//#undef LOG_GROUP
+#include "VBoxGuestR0LibGenericRequest.c"
+#undef LOG_GROUP
+#include "VBoxGuestR0LibHGCMInternal.c"
+//#undef LOG_GROUP
+#include "VBoxGuestR0LibInit.c"
+//#undef LOG_GROUP
+#include "VBoxGuestR0LibPhysHeap.c"
+#undef LOG_GROUP
+#include "VBoxGuestR0LibVMMDev.c"
+#undef LOG_GROUP
+#include "r0drv/alloc-r0drv.c"
+#undef LOG_GROUP
+#include "r0drv/initterm-r0drv.c"
+#undef LOG_GROUP
+#include "r0drv/memobj-r0drv.c"
+#undef LOG_GROUP
+#include "r0drv/mpnotification-r0drv.c"
+#undef LOG_GROUP
+#include "r0drv/powernotification-r0drv.c"
+#undef LOG_GROUP
+#include "r0drv/generic/semspinmutex-r0drv-generic.c"
+#undef LOG_GROUP
+#include "common/alloc/alloc.c"
+#undef LOG_GROUP
+#include "common/checksum/crc32.c"
+#undef LOG_GROUP
+#include "common/err/errinfo.c"
+#undef LOG_GROUP
+#include "common/log/log.c"
+#undef LOG_GROUP
+#include "common/log/logellipsis.c"
+#undef LOG_GROUP
+#include "common/log/logrel.c"
+#undef LOG_GROUP
+#include "common/log/logrelellipsis.c"
+#undef LOG_GROUP
+#include "common/log/logcom.c"
+#undef LOG_GROUP
+#include "common/log/logformat.c"
+#undef LOG_GROUP
+#include "common/log/RTLogCreateEx.c"
+#undef LOG_GROUP
+#include "common/misc/RTAssertMsg1Weak.c"
+#undef LOG_GROUP
+#include "common/misc/RTAssertMsg2.c"
+#undef LOG_GROUP
+#include "common/misc/RTAssertMsg2Add.c"
+#undef LOG_GROUP
+#include "common/misc/RTAssertMsg2AddWeak.c"
+#undef LOG_GROUP
+#include "common/misc/RTAssertMsg2AddWeakV.c"
+#undef LOG_GROUP
+#include "common/misc/RTAssertMsg2Weak.c"
+#undef LOG_GROUP
+#include "common/misc/RTAssertMsg2WeakV.c"
+#undef LOG_GROUP
+#include "common/misc/assert.c"
+#undef LOG_GROUP
+#include "common/misc/thread.c"
+#undef LOG_GROUP
+#include "common/string/RTStrCat.c"
+#undef LOG_GROUP
+#include "common/string/RTStrCmp.c"
+#undef LOG_GROUP
+#include "common/string/RTStrCopy.c"
+#undef LOG_GROUP
+#include "common/string/RTStrCopyEx.c"
+#undef LOG_GROUP
+#include "common/string/RTStrCopyP.c"
+#undef LOG_GROUP
+#include "common/string/RTStrEnd.c"
+#undef LOG_GROUP
+#include "common/string/RTStrICmpAscii.c"
+#undef LOG_GROUP
+#include "common/string/RTStrNICmpAscii.c"
+#undef LOG_GROUP
+#include "common/string/RTStrNCmp.c"
+#undef LOG_GROUP
+#include "common/string/RTStrNLen.c"
+#undef LOG_GROUP
+#include "common/string/stringalloc.c"
+#undef LOG_GROUP
+#include "common/string/strformat.c"
+#undef LOG_GROUP
+#include "common/string/RTStrFormat.c"
+#undef LOG_GROUP
+#include "common/string/strformatnum.c"
+#undef LOG_GROUP
+#include "common/string/strformattype.c"
+#undef LOG_GROUP
+#include "common/string/strprintf.c"
+#undef LOG_GROUP
+#include "common/string/strprintf-ellipsis.c"
+#undef LOG_GROUP
+#include "common/string/strprintf2.c"
+#undef LOG_GROUP
+#include "common/string/strprintf2-ellipsis.c"
+#undef LOG_GROUP
+#include "common/string/strtonum.c"
+#undef LOG_GROUP
+#include "common/string/utf-8.c"
+#undef LOG_GROUP
+#include "common/table/avlpv.c"
+#undef LOG_GROUP
+#include "common/time/time.c"
+#undef LOG_GROUP
+#include "generic/RTAssertShouldPanic-generic.c"
+#undef LOG_GROUP
+#include "generic/RTLogWriteStdErr-stub-generic.c"
+#undef LOG_GROUP
+#include "generic/RTLogWriteStdOut-stub-generic.c"
+#undef LOG_GROUP
+#include "generic/RTMpGetCoreCount-generic.c"
+#undef LOG_GROUP
+#include "generic/RTSemEventWait-2-ex-generic.c"
+#undef LOG_GROUP
+#include "generic/RTSemEventWaitNoResume-2-ex-generic.c"
+#undef LOG_GROUP
+#include "generic/RTSemEventMultiWait-2-ex-generic.c"
+#undef LOG_GROUP
+#include "generic/RTSemEventMultiWaitNoResume-2-ex-generic.c"
+#undef LOG_GROUP
+#include "generic/rtStrFormatKernelAddress-generic.c"
+#undef LOG_GROUP
+#include "generic/errvars-generic.c"
+#undef LOG_GROUP
+#include "generic/mppresent-generic.c"
+#undef LOG_GROUP
+#include "VBox/log-vbox.c"
+#undef LOG_GROUP
+#include "VBox/logbackdoor.c"
+#undef LOG_GROUP
+#include "VBox/RTLogWriteVmm-amd64-x86.c"
+
+#ifdef RT_ARCH_AMD64
+# undef LOG_GROUP
+# include "common/alloc/heapsimple.c"
+#endif
+
+#if 0 //def RT_ARCH_X86 - iprt/nocrt/limit.h clashes.
+# include "common/math/gcc/divdi3.c"
+# include "common/math/gcc/moddi3.c"
+# include "common/math/gcc/udivdi3.c"
+# include "common/math/gcc/udivmoddi4.c"
+# include "common/math/gcc/umoddi3.c"
+# include "common/math/gcc/qdivrem.c"
+#endif
+
diff --git a/src/VBox/Additions/common/VBoxGuest/linux/combined-os-specific.c b/src/VBox/Additions/common/VBoxGuest/linux/combined-os-specific.c
new file mode 100644
index 00000000..8981b058
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/linux/combined-os-specific.c
@@ -0,0 +1,61 @@
+/* $Id: combined-os-specific.c $ */
+/** @file
+ * VBoxGuest - Combine a bunch of OS specific sources into one compile unit.
+ */
+
+/*
+ * 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
+ */
+
+
+#include "the-linux-kernel.h"
+
+#include "r0drv/linux/alloc-r0drv-linux.c"
+#include "r0drv/linux/assert-r0drv-linux.c"
+#include "r0drv/linux/initterm-r0drv-linux.c"
+#include "r0drv/linux/memobj-r0drv-linux.c"
+#include "r0drv/linux/memuserkernel-r0drv-linux.c"
+#include "r0drv/linux/mp-r0drv-linux.c"
+#include "r0drv/linux/mpnotification-r0drv-linux.c"
+#include "r0drv/linux/process-r0drv-linux.c"
+#include "r0drv/linux/semevent-r0drv-linux.c"
+#include "r0drv/linux/semeventmulti-r0drv-linux.c"
+#include "r0drv/linux/semfastmutex-r0drv-linux.c"
+#include "r0drv/linux/semmutex-r0drv-linux.c"
+#include "r0drv/linux/spinlock-r0drv-linux.c"
+#include "r0drv/linux/thread-r0drv-linux.c"
+#include "r0drv/linux/thread2-r0drv-linux.c"
+#undef LOG_GROUP
+#include "r0drv/linux/time-r0drv-linux.c"
+#include "r0drv/linux/timer-r0drv-linux.c"
+#include "r0drv/linux/RTLogWriteDebugger-r0drv-linux.c"
+#include "common/err/RTErrConvertFromErrno.c"
+#include "common/err/RTErrConvertToErrno.c"
+
diff --git a/src/VBox/Additions/common/VBoxGuest/linux/files_vboxguest b/src/VBox/Additions/common/VBoxGuest/linux/files_vboxguest
new file mode 100755
index 00000000..5df520b6
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/linux/files_vboxguest
@@ -0,0 +1,237 @@
+#!/bin/sh
+# $Id: files_vboxguest $
+## @file
+# Shared file between Makefile.kmk and export_modules.sh.
+#
+
+#
+# Copyright (C) 2007-2023 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
+#
+
+FILES_VBOXGUEST_NOBIN=" \
+    ${PATH_ROOT}/include/iprt/nocrt/limits.h=>include/iprt/nocrt/limits.h \
+    ${PATH_ROOT}/include/iprt/alloca.h=>include/iprt/alloca.h \
+    ${PATH_ROOT}/include/iprt/alloc.h=>include/iprt/alloc.h \
+    ${PATH_ROOT}/include/iprt/asm.h=>include/iprt/asm.h \
+    ${PATH_ROOT}/include/iprt/asm-amd64-x86.h=>include/iprt/asm-amd64-x86.h \
+    ${PATH_ROOT}/include/iprt/asm-math.h=>include/iprt/asm-math.h \
+    ${PATH_ROOT}/include/iprt/assert.h=>include/iprt/assert.h \
+    ${PATH_ROOT}/include/iprt/assertcompile.h=>include/iprt/assertcompile.h \
+    ${PATH_ROOT}/include/iprt/avl.h=>include/iprt/avl.h \
+    ${PATH_ROOT}/include/iprt/cdefs.h=>include/iprt/cdefs.h \
+    ${PATH_ROOT}/include/iprt/cpuset.h=>include/iprt/cpuset.h \
+    ${PATH_ROOT}/include/iprt/crc.h=>include/iprt/crc.h \
+    ${PATH_ROOT}/include/iprt/ctype.h=>include/iprt/ctype.h \
+    ${PATH_ROOT}/include/iprt/err.h=>include/iprt/err.h \
+    ${PATH_ROOT}/include/iprt/errcore.h=>include/iprt/errcore.h \
+    ${PATH_ROOT}/include/iprt/errno.h=>include/iprt/errno.h \
+    ${PATH_ROOT}/include/iprt/heap.h=>include/iprt/heap.h \
+    ${PATH_ROOT}/include/iprt/initterm.h=>include/iprt/initterm.h \
+    ${PATH_ROOT}/include/iprt/latin1.h=>include/iprt/latin1.h \
+    ${PATH_ROOT}/include/iprt/list.h=>include/iprt/list.h \
+    ${PATH_ROOT}/include/iprt/lockvalidator.h=>include/iprt/lockvalidator.h \
+    ${PATH_ROOT}/include/iprt/log.h=>include/iprt/log.h \
+    ${PATH_ROOT}/include/iprt/mangling.h=>include/iprt/mangling.h \
+    ${PATH_ROOT}/include/iprt/mem.h=>include/iprt/mem.h \
+    ${PATH_ROOT}/include/iprt/memobj.h=>include/iprt/memobj.h \
+    ${PATH_ROOT}/include/iprt/mp.h=>include/iprt/mp.h \
+    ${PATH_ROOT}/include/iprt/net.h=>include/iprt/net.h \
+    ${PATH_ROOT}/include/iprt/param.h=>include/iprt/param.h \
+    ${PATH_ROOT}/include/iprt/path.h=>include/iprt/path.h \
+    ${PATH_ROOT}/include/iprt/power.h=>include/iprt/power.h \
+    ${PATH_ROOT}/include/iprt/process.h=>include/iprt/process.h \
+    ${PATH_ROOT}/include/iprt/semaphore.h=>include/iprt/semaphore.h \
+    ${PATH_ROOT}/include/iprt/spinlock.h=>include/iprt/spinlock.h \
+    ${PATH_ROOT}/include/iprt/stdarg.h=>include/iprt/stdarg.h \
+    ${PATH_ROOT}/include/iprt/stdint.h=>include/iprt/stdint.h \
+    ${PATH_ROOT}/include/iprt/string.h=>include/iprt/string.h \
+    ${PATH_ROOT}/include/iprt/thread.h=>include/iprt/thread.h \
+    ${PATH_ROOT}/include/iprt/time.h=>include/iprt/time.h \
+    ${PATH_ROOT}/include/iprt/timer.h=>include/iprt/timer.h \
+    ${PATH_ROOT}/include/iprt/types.h=>include/iprt/types.h \
+    ${PATH_ROOT}/include/iprt/uint64.h=>include/iprt/uint64.h \
+    ${PATH_ROOT}/include/iprt/uni.h=>include/iprt/uni.h \
+    ${PATH_ROOT}/include/iprt/utf16.h=>include/iprt/utf16.h \
+    ${PATH_ROOT}/include/iprt/x86.h=>include/iprt/x86.h \
+    ${PATH_ROOT}/include/iprt/x86-helpers.h=>include/iprt/x86-helpers.h \
+    ${PATH_ROOT}/include/iprt/linux/version.h=>include/iprt/linux/version.h \
+    ${PATH_ROOT}/include/VBox/cdefs.h=>include/VBox/cdefs.h \
+    ${PATH_ROOT}/include/VBox/err.h=>include/VBox/err.h \
+    ${PATH_ROOT}/include/VBox/log.h=>include/VBox/log.h \
+    ${PATH_ROOT}/include/VBox/param.h=>include/VBox/param.h \
+    ${PATH_ROOT}/include/VBox/types.h=>include/VBox/types.h \
+    ${PATH_ROOT}/include/VBox/ostypes.h=>include/VBox/ostypes.h \
+    ${PATH_ROOT}/include/VBox/VMMDev.h=>include/VBox/VMMDev.h \
+    ${PATH_ROOT}/include/VBox/VMMDevCoreTypes.h=>include/VBox/VMMDevCoreTypes.h \
+    ${PATH_ROOT}/include/VBox/VBoxGuest.h=>include/VBox/VBoxGuest.h \
+    ${PATH_ROOT}/include/VBox/VBoxGuestCoreTypes.h=>include/VBox/VBoxGuestCoreTypes.h \
+    ${PATH_ROOT}/include/VBox/VBoxGuestLib.h=>include/VBox/VBoxGuestLib.h \
+    ${PATH_ROOT}/include/VBox/VBoxGuestMangling.h=>include/VBox/VBoxGuestMangling.h \
+    ${PATH_ROOT}/include/VBox/version.h=>include/VBox/version.h \
+    ${PATH_ROOT}/include/VBox/HostServices/GuestPropertySvc.h=>include/VBox/HostServices/GuestPropertySvc.h \
+    ${PATH_ROOT}/include/VBox/vmm/cpuidcall.h=>include/VBox/vmm/cpuidcall.h \
+    ${PATH_ROOT}/src/VBox/Additions/common/VBoxGuest/VBoxGuest.cpp=>VBoxGuest-common.c \
+    ${PATH_ROOT}/src/VBox/Additions/common/VBoxGuest/VBoxGuest-linux.c=>VBoxGuest-linux.c \
+    ${PATH_ROOT}/src/VBox/Additions/common/VBoxGuest/VBoxGuestInternal.h=>VBoxGuestInternal.h \
+    ${PATH_ROOT}/src/VBox/Additions/common/VBoxGuest/linux/Makefile=>Makefile \
+    ${PATH_ROOT}/src/VBox/Additions/common/VBoxGuest/linux/combined-agnostic.c=>combined-agnostic.c \
+    ${PATH_ROOT}/src/VBox/Additions/common/VBoxGuest/linux/combined-os-specific.c=>combined-os-specific.c \
+    ${PATH_ROOT}/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibInternal.h=>VBoxGuestR0LibInternal.h \
+    ${PATH_ROOT}/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibGenericRequest.cpp=>VBoxGuestR0LibGenericRequest.c \
+    ${PATH_ROOT}/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibHGCMInternal.cpp=>VBoxGuestR0LibHGCMInternal.c \
+    ${PATH_ROOT}/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibInit.cpp=>VBoxGuestR0LibInit.c \
+    ${PATH_ROOT}/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibPhysHeap.cpp=>VBoxGuestR0LibPhysHeap.c \
+    ${PATH_ROOT}/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR0LibVMMDev.cpp=>VBoxGuestR0LibVMMDev.c \
+    ${PATH_ROOT}/src/VBox/Installer/linux/Makefile-header.gmk=>Makefile-header.gmk \
+    ${PATH_ROOT}/src/VBox/Installer/linux/Makefile-footer.gmk=>Makefile-footer.gmk \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/assert.h=>include/internal/assert.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/initterm.h=>include/internal/initterm.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/iprt.h=>include/internal/iprt.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/lockvalidator.h=>include/internal/lockvalidator.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/magics.h=>include/internal/magics.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/mem.h=>include/internal/mem.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/memobj.h=>include/internal/memobj.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/string.h=>include/internal/string.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/thread.h=>include/internal/thread.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/time.h=>include/internal/time.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/sched.h=>include/internal/sched.h \
+    ${PATH_ROOT}/src/VBox/Runtime/include/internal/process.h=>include/internal/process.h \
+    ${PATH_ROOT}/src/VBox/Runtime/common/alloc/alloc.cpp=>common/alloc/alloc.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/alloc/heapsimple.cpp=>common/alloc/heapsimple.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/checksum/crc32.cpp=>common/checksum/crc32.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/err/RTErrConvertFromErrno.cpp=>common/err/RTErrConvertFromErrno.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/err/RTErrConvertToErrno.cpp=>common/err/RTErrConvertToErrno.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/err/errinfo.cpp=>common/err/errinfo.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/log/log.cpp=>common/log/log.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/log/logellipsis.cpp=>common/log/logellipsis.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/log/logrel.cpp=>common/log/logrel.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/log/logrelellipsis.cpp=>common/log/logrelellipsis.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/log/logformat.cpp=>common/log/logformat.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/log/logcom.cpp=>common/log/logcom.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/log/RTLogCreateEx.cpp=>common/log/RTLogCreateEx.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/math/gcc/divdi3.c=>common/math/gcc/divdi3.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/math/gcc/divmoddi4.c=>common/math/gcc/divmoddi4.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/math/gcc/moddi3.c=>common/math/gcc/moddi3.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/math/gcc/qdivrem.c=>common/math/gcc/qdivrem.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/math/gcc/quad.h=>common/math/gcc/quad.h \
+    ${PATH_ROOT}/src/VBox/Runtime/common/math/gcc/udivdi3.c=>common/math/gcc/udivdi3.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/math/gcc/udivmoddi4.c=>common/math/gcc/udivmoddi4.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/math/gcc/umoddi3.c=>common/math/gcc/umoddi3.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/misc/RTAssertMsg1Weak.cpp=>common/misc/RTAssertMsg1Weak.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/misc/RTAssertMsg2.cpp=>common/misc/RTAssertMsg2.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/misc/RTAssertMsg2Add.cpp=>common/misc/RTAssertMsg2Add.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/misc/RTAssertMsg2AddWeak.cpp=>common/misc/RTAssertMsg2AddWeak.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/misc/RTAssertMsg2AddWeakV.cpp=>common/misc/RTAssertMsg2AddWeakV.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/misc/RTAssertMsg2Weak.cpp=>common/misc/RTAssertMsg2Weak.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/misc/RTAssertMsg2WeakV.cpp=>common/misc/RTAssertMsg2WeakV.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/misc/assert.cpp=>common/misc/assert.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/misc/thread.cpp=>common/misc/thread.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/RTStrCat.cpp=>common/string/RTStrCat.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/RTStrCmp.cpp=>common/string/RTStrCmp.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/RTStrCopy.cpp=>common/string/RTStrCopy.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/RTStrCopyEx.cpp=>common/string/RTStrCopyEx.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/RTStrCopyP.cpp=>common/string/RTStrCopyP.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/RTStrEnd.cpp=>common/string/RTStrEnd.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/RTStrICmpAscii.cpp=>common/string/RTStrICmpAscii.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/RTStrNICmpAscii.cpp=>common/string/RTStrNICmpAscii.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/RTStrNCmp.cpp=>common/string/RTStrNCmp.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/RTStrNLen.cpp=>common/string/RTStrNLen.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/stringalloc.cpp=>common/string/stringalloc.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/strformat.cpp=>common/string/strformat.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/RTStrFormat.cpp=>common/string/RTStrFormat.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/strformatnum.cpp=>common/string/strformatnum.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/strformatrt.cpp=>common/string/strformatrt.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/strformattype.cpp=>common/string/strformattype.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/strprintf.cpp=>common/string/strprintf.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/strprintf-ellipsis.cpp=>common/string/strprintf-ellipsis.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/strprintf2.cpp=>common/string/strprintf2.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/strprintf2-ellipsis.cpp=>common/string/strprintf2-ellipsis.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/strtonum.cpp=>common/string/strtonum.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/string/utf-8.cpp=>common/string/utf-8.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/table/avlpv.cpp=>common/table/avlpv.c \
+    ${PATH_ROOT}/src/VBox/Runtime/common/table/avl_Base.cpp.h=>common/table/avl_Base.cpp.h \
+    ${PATH_ROOT}/src/VBox/Runtime/common/table/avl_Get.cpp.h=>common/table/avl_Get.cpp.h \
+    ${PATH_ROOT}/src/VBox/Runtime/common/table/avl_GetBestFit.cpp.h=>common/table/avl_GetBestFit.cpp.h \
+    ${PATH_ROOT}/src/VBox/Runtime/common/table/avl_RemoveBestFit.cpp.h=>common/table/avl_RemoveBestFit.cpp.h \
+    ${PATH_ROOT}/src/VBox/Runtime/common/table/avl_DoWithAll.cpp.h=>common/table/avl_DoWithAll.cpp.h \
+    ${PATH_ROOT}/src/VBox/Runtime/common/table/avl_Destroy.cpp.h=>common/table/avl_Destroy.cpp.h \
+    ${PATH_ROOT}/src/VBox/Runtime/common/time/time.cpp=>common/time/time.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/RTAssertShouldPanic-generic.cpp=>generic/RTAssertShouldPanic-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/RTLogWriteStdErr-stub-generic.cpp=>generic/RTLogWriteStdErr-stub-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/RTLogWriteStdOut-stub-generic.cpp=>generic/RTLogWriteStdOut-stub-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/RTMpGetCoreCount-generic.cpp=>generic/RTMpGetCoreCount-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/RTSemEventWait-2-ex-generic.cpp=>generic/RTSemEventWait-2-ex-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/RTSemEventWaitNoResume-2-ex-generic.cpp=>generic/RTSemEventWaitNoResume-2-ex-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/RTSemEventMultiWait-2-ex-generic.cpp=>generic/RTSemEventMultiWait-2-ex-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/RTSemEventMultiWaitNoResume-2-ex-generic.cpp=>generic/RTSemEventMultiWaitNoResume-2-ex-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/rtStrFormatKernelAddress-generic.cpp=>generic/rtStrFormatKernelAddress-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/errvars-generic.cpp=>generic/errvars-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/generic/mppresent-generic.cpp=>generic/mppresent-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/alloc-r0drv.cpp=>r0drv/alloc-r0drv.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/alloc-r0drv.h=>r0drv/alloc-r0drv.h \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/initterm-r0drv.cpp=>r0drv/initterm-r0drv.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/memobj-r0drv.cpp=>r0drv/memobj-r0drv.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/mp-r0drv.h=>r0drv/mp-r0drv.h \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/mpnotification-r0drv.c=>r0drv/mpnotification-r0drv.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/power-r0drv.h=>r0drv/power-r0drv.h \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/powernotification-r0drv.c=>r0drv/powernotification-r0drv.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/linux/alloc-r0drv-linux.c=>r0drv/linux/alloc-r0drv-linux.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/linux/assert-r0drv-linux.c=>r0drv/linux/assert-r0drv-linux.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/linux/initterm-r0drv-linux.c=>r0drv/linux/initterm-r0drv-linux.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/linux/memobj-r0drv-linux.c=>r0drv/linux/memobj-r0drv-linux.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/linux/memuserkernel-r0drv-linux.c=>r0drv/linux/memuserkernel-r0drv-linux.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/linux/mp-r0drv-linux.c=>r0drv/linux/mp-r0drv-linux.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/linux/mpnotification-r0drv-linux.c=>r0drv/linux/mpnotification-r0drv-linux.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/linux/process-r0drv-linux.c=>r0drv/linux/process-r0drv-linux.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/linux/semevent-r0drv-linux.c=>r0drv/linux/semevent-r0drv-linux.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/linux/semeventmulti-r0drv-linux.c=>r0drv/linux/semeventmulti-r0drv-linux.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/linux/semfastmutex-r0drv-linux.c=>r0drv/linux/semfastmutex-r0drv-linux.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/linux/semmutex-r0drv-linux.c=>r0drv/linux/semmutex-r0drv-linux.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/linux/spinlock-r0drv-linux.c=>r0drv/linux/spinlock-r0drv-linux.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/linux/string.h=>r0drv/linux/string.h \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/linux/the-linux-kernel.h=>r0drv/linux/the-linux-kernel.h \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/linux/thread-r0drv-linux.c=>r0drv/linux/thread-r0drv-linux.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/linux/thread2-r0drv-linux.c=>r0drv/linux/thread2-r0drv-linux.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/linux/time-r0drv-linux.c=>r0drv/linux/time-r0drv-linux.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/linux/timer-r0drv-linux.c=>r0drv/linux/timer-r0drv-linux.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/linux/waitqueue-r0drv-linux.h=>r0drv/linux/waitqueue-r0drv-linux.h \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/linux/RTLogWriteDebugger-r0drv-linux.c=>r0drv/linux/RTLogWriteDebugger-r0drv-linux.c \
+    ${PATH_ROOT}/src/VBox/Runtime/r0drv/generic/semspinmutex-r0drv-generic.c=>r0drv/generic/semspinmutex-r0drv-generic.c \
+    ${PATH_ROOT}/src/VBox/Runtime/VBox/log-vbox.cpp=>VBox/log-vbox.c \
+    ${PATH_ROOT}/src/VBox/Runtime/VBox/logbackdoor.cpp=>VBox/logbackdoor.c \
+    ${PATH_ROOT}/src/VBox/Runtime/VBox/RTLogWriteVmm-amd64-x86.cpp=>VBox/RTLogWriteVmm-amd64-x86.c \
+    ${PATH_OUT}/version-generated.h=>version-generated.h \
+    ${PATH_OUT}/product-generated.h=>product-generated.h \
+    ${PATH_OUT}/revision-generated.h=>revision-generated.h \
+"
+
+FILES_VBOXGUEST_BIN=" \
+"
+
diff --git a/src/VBox/Additions/common/VBoxGuest/netbsd/locators.h b/src/VBox/Additions/common/VBoxGuest/netbsd/locators.h
new file mode 100644
index 00000000..91272794
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/netbsd/locators.h
@@ -0,0 +1,8 @@
+/* $Id: locators.h $ */
+/** @file
+ * Placeholder "locators.h" that wsmousevar.h needs (bad hygiene).
+ *
+ * It's normally generated by config(8), but see the explanatory
+ * comment in vboxguest.ioconf
+ */
+#define WSMOUSEDEVCF_MUX 0
diff --git a/src/VBox/Additions/common/VBoxGuest/netbsd/vboxguest.ioconf b/src/VBox/Additions/common/VBoxGuest/netbsd/vboxguest.ioconf
new file mode 100644
index 00000000..21beed84
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/netbsd/vboxguest.ioconf
@@ -0,0 +1,66 @@
+# $Id: vboxguest.ioconf $
+## @file
+# NetBSD vboxguest module configuration
+#
+
+#
+# Copyright (C) 2017-2023 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
+#
+
+# XXX:
+#
+# VBoxGuest-netbsd.c has manually edited copy of the config glue and
+# we also provide stub "locators.h" in this directory.  Both should
+# really be generated by config(8) from this ioconf file but that runs
+# into a couple of problems.
+#
+# We want to attach wsmouse(4) as a child, but we cannot expect the
+# kernel that loads us to have "wsmouse* at wsmousedev?" attachment
+# and in fact until recently x86 kernels didn't have it.
+#
+# But when we specify "wsmouse* at vboxguest?" attachment below
+# config(8) thinks that this module defines wsmouse and generates
+# CFDRIVER_DECL() for it and also includes it into cfdriver and
+# cfattachinit arrays it emits.
+
+ioconf vboxguest
+
+include "conf/files"
+
+include "dev/i2o/files.i2o"	# XXX: pci needs device iop
+include "dev/pci/files.pci"
+
+device	vboxguest: wsmousedev
+attach	vboxguest at pci
+
+pseudo-root	pci*
+vboxguest0	at pci? dev ? function ?
+
+wsmouse*	at vboxguest?
diff --git a/src/VBox/Additions/common/VBoxGuest/solaris/deps.asm b/src/VBox/Additions/common/VBoxGuest/solaris/deps.asm
new file mode 100644
index 00000000..a6abf2bf
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/solaris/deps.asm
@@ -0,0 +1,48 @@
+; $Id: deps.asm $
+;; @file
+; Solaris kernel module dependency
+;
+
+;
+; 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
+;
+
+%include "iprt/solaris/kmoddeps.mac"
+
+kmoddeps_header  ; ELF header, section table and shared string table
+
+kmoddeps_dynstr_start  ; ELF .dynstr section
+kmoddeps_dynstr_string str_misc_ctf, "misc/ctf"
+kmoddeps_dynstr_end
+
+kmoddeps_dynamic_start  ; ELF .dynamic section
+kmoddeps_dynamic_needed str_misc_ctf
+kmoddeps_dynamic_end
+
diff --git a/src/VBox/Additions/common/VBoxGuest/solaris/load.sh b/src/VBox/Additions/common/VBoxGuest/solaris/load.sh
new file mode 100755
index 00000000..379cba0c
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/solaris/load.sh
@@ -0,0 +1,108 @@
+#!/bin/bash
+# $Id: load.sh $
+## @file
+# For GA development.
+#
+
+#
+# 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
+#
+
+DRVNAME="vboxguest"
+DRIVERS_USING_IT="vboxfs"
+
+DRVFILE=`dirname "$0"`
+DRVFILE=`cd "$DRVFILE" && pwd`
+DRVFILE="$DRVFILE/$DRVNAME"
+if [ ! -f "$DRVFILE" ]; then
+    echo "load.sh: Cannot find $DRVFILE or it's not a file..."
+    exit 1;
+fi
+
+SUDO=sudo
+#set -x
+
+# Unload driver that may depend on the driver we're going to (re-)load
+# as well as the driver itself.
+for drv in $DRIVERS_USING_IT $DRVNAME;
+do
+    LOADED=`modinfo | grep -w "$drv"`
+    if test -n "$LOADED"; then
+        MODID=`echo "$LOADED" | cut -d ' ' -f 1`
+        $SUDO modunload -i $MODID;
+        LOADED=`modinfo | grep -w "$drv"`;
+        if test -n "$LOADED"; then
+            echo "load.sh: failed to unload $drv";
+            dmesg | tail
+            exit 1;
+        fi
+    fi
+done
+
+#
+# Update the devlink.tab file so we get a /dev/vboxguest node.
+#
+set -e
+sed -e '/name=vboxguest/d' /etc/devlink.tab > /tmp/devlink.vbox
+echo -e "type=ddi_pseudo;name=vboxguest\t\D" >> /tmp/devlink.vbox
+$SUDO cp /tmp/devlink.vbox /etc/devlink.tab
+$SUDO ln -fs ../devices/pci@0,0/pci80ee,cafe@4:vboxguest /dev/vboxguest
+set +e
+
+#
+# The add_drv command will load the driver, so we need to temporarily put it
+# in a place that is searched in order to load it.
+#
+MY_RC=1
+set -e
+$SUDO rm -f \
+    "/usr/kernel/drv/${DRVNAME}" \
+    "/usr/kernel/drv/amd64/${DRVNAME}"
+sync
+$SUDO cp "${DRVFILE}"      /platform/i86pc/kernel/drv/amd64/
+set +e
+
+$SUDO rem_drv $DRVNAME
+if $SUDO add_drv -ipci80ee,cafe -m"* 0666 root sys" -v $DRVNAME; then
+    sync
+    $SUDO /usr/sbin/devfsadm -i $DRVNAME
+    MY_RC=0
+else
+    dmesg | tail
+    echo "load.sh: add_drv failed."
+fi
+
+$SUDO rm -f \
+    "/usr/kernel/drv/${DRVNAME}" \
+    "/usr/kernel/drv/amd64/${DRVNAME}"
+sync
+
+exit $MY_RC;
+
diff --git a/src/VBox/Additions/common/VBoxGuest/win/Makefile.kup b/src/VBox/Additions/common/VBoxGuest/win/Makefile.kup
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/win/Makefile.kup
diff --git a/src/VBox/Additions/common/VBoxGuest/win/VBoxGuest.inf b/src/VBox/Additions/common/VBoxGuest/win/VBoxGuest.inf
new file mode 100644
index 00000000..ce64cf7b
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/win/VBoxGuest.inf
@@ -0,0 +1,98 @@
+; $Id: VBoxGuest.inf $
+;; @file
+; INF file for installing the VirtualBox Windows guest driver, XP and later.
+;
+
+;
+; 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
+;
+
+[Version]
+Signature="$WINDOWS NT$"
+Provider=%ORACLE%
+ClassGuid={4D36E97D-E325-11CE-BFC1-08002BE10318}
+Class=System
+DriverPackageType=PlugAndPlay
+;edit-DriverVer=08/26/2008,2.00.0000
+;cat CatalogFile=VBoxGuest.cat
+
+[SourceDisksNames]
+1 = %VBoxGuest.MediaDesc%
+
+[SourceDisksFiles]
+VBoxGuest.sys = 1
+VBoxControl.exe = 1
+VBoxTray.exe = 1
+
+[DestinationDirs]
+DefaultDestDir = 12 ; drivers
+VBoxTray_CopyFiles = 11 ; system32
+
+[Manufacturer]
+%ORACLE%=VBoxGuest@COMMA-NT-ARCH@
+
+[VBoxGuest@DOT-NT-ARCH@]
+%VBoxGuest.DeviceDesc%=VBoxGuest_Install,PCI\VEN_80ee&DEV_cafe
+
+[VBoxGuest_Install]
+CopyFiles = VBoxGuest_CopyFiles, VBoxTray_CopyFiles
+AddReg = VBoxTray_Add_Reg
+
+[VBoxGuest_CopyFiles]
+VBoxGuest.sys
+
+[VBoxTray_CopyFiles]
+VBoxTray.exe
+VBoxControl.exe
+
+[VBoxGuest_Install.Services]
+AddService = VBoxGuest, 0x00000002, VBoxGuest_ServiceInstallSection
+DelService = VBoxTray, 0x00000004
+
+[VBoxGuest_ServiceInstallSection]
+DisplayName    = %VBoxGuest_svcdesc%
+ServiceType    = 0x00000001 ; kernel driver
+StartType      = 0x00000000 ; boot start
+ErrorControl   = 0x00000001 ; normal error handling
+LoadOrderGroup = Base
+ServiceBinary  = %12%\VBoxGuest.sys
+
+[VBoxTray_Add_Reg]
+HKLM, SOFTWARE\Microsoft\Windows\CurrentVersion\Run, VBoxTray, 0x00020000, %%SystemRoot%%\system32\VBoxTray.exe
+
+[ClassInstall32]
+; This should fix the error 0xe0000101 (The required section was not found in the INF).
+
+[Strings]
+ORACLE = "Oracle Corporation"
+VBoxGuest.DeviceDesc = "VirtualBox Guest Device"
+VBoxGuest_svcdesc = "VirtualBox Guest Driver"
+VBoxTray_svcdesc = "VirtualBox Guest Tray"
+VBoxGuest.MediaDesc = "VirtualBox Guest Driver Installation Disk"
diff --git a/src/VBox/Additions/common/VBoxGuest/win/VBoxGuest.rc b/src/VBox/Additions/common/VBoxGuest/win/VBoxGuest.rc
new file mode 100644
index 00000000..ba7d500e
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/win/VBoxGuest.rc
@@ -0,0 +1,72 @@
+/* $Id: VBoxGuest.rc $ */
+/** @file
+ * VBoxGuest - Resource file containing version info and icon.
+ */
+
+/*
+ * 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
+ */
+
+#include <windows.h>
+#include <VBox/version.h>
+
+LANGUAGE LANG_ENGLISH, SUBLANG_ENGLISH_US
+
+VS_VERSION_INFO VERSIONINFO
+   FILEVERSION      VBOX_RC_FILE_VERSION
+   PRODUCTVERSION   VBOX_RC_FILE_VERSION
+   FILEFLAGSMASK    VS_FFI_FILEFLAGSMASK
+   FILEFLAGS        VBOX_RC_FILE_FLAGS
+   FILEOS           VBOX_RC_FILE_OS
+   FILETYPE         VBOX_RC_TYPE_DLL
+   FILESUBTYPE      VFT2_UNKNOWN
+BEGIN
+   BLOCK "StringFileInfo"
+   BEGIN
+      BLOCK "040904b0"
+      BEGIN
+         VALUE "FileDescription",  "VirtualBox Guest Driver\0"
+         VALUE "InternalName",     "VBoxGuest\0"
+         VALUE "OriginalFilename", "VBoxGuest.sys\0"
+         VALUE "CompanyName",      VBOX_RC_COMPANY_NAME
+         VALUE "FileVersion",      VBOX_RC_FILE_VERSION_STR
+         VALUE "LegalCopyright",   VBOX_RC_LEGAL_COPYRIGHT
+         VALUE "ProductName",      VBOX_RC_PRODUCT_NAME_GA_STR
+         VALUE "ProductVersion",   VBOX_RC_PRODUCT_VERSION_STR
+         VBOX_RC_MORE_STRINGS
+      END
+   END
+   BLOCK "VarFileInfo"
+   BEGIN
+      VALUE "Translation", 0x409, 1200
+   END
+END
+
+// #include <VBoxGuestMsg.rc>
diff --git a/src/VBox/Additions/common/VBoxGuest/win/VBoxGuestEarlyNT.inf b/src/VBox/Additions/common/VBoxGuest/win/VBoxGuestEarlyNT.inf
new file mode 100644
index 00000000..c0bfd4e5
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/win/VBoxGuestEarlyNT.inf
@@ -0,0 +1,100 @@
+; $Id: VBoxGuestEarlyNT.inf $
+;; @file
+; INF file for installing the VirtualBox Windows guest driver, pre-XP variant.
+;
+
+;
+; 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
+;
+
+[Version]
+Signature="$WINDOWS NT$"
+Provider=%ORACLE%
+ClassGuid={4D36E97D-E325-11CE-BFC1-08002BE10318}
+Class=System
+DriverPackageType=PlugAndPlay
+;edit-DriverVer=08/26/2008,2.00.0000
+;cat CatalogFile=VBoxGuestEarlyNT.cat
+
+[SourceDisksNames]
+1 = %VBoxGuest.MediaDesc%
+
+[SourceDisksFiles]
+VBoxGuest.sys = 1
+VBoxControl.exe = 1
+VBoxTray.exe = 1
+
+[DestinationDirs]
+DefaultDestDir = 12 ; drivers
+VBoxTray_CopyFiles = 11 ; system32
+
+; Windows 2000 and NT4 treats entries here as pure 'name=section' and will not
+; split the value on commas. Newer InfVerif.exe requires the comma stuff here.
+[Manufacturer]
+%ORACLE%=VBoxGuest
+
+[VBoxGuest]
+%VBoxGuest.DeviceDesc%=VBoxGuest_Install,PCI\VEN_80ee&DEV_cafe
+
+[VBoxGuest_Install]
+CopyFiles = VBoxGuest_CopyFiles, VBoxTray_CopyFiles
+AddReg = VBoxTray_Add_Reg
+
+[VBoxGuest_CopyFiles]
+VBoxGuest.sys
+
+[VBoxTray_CopyFiles]
+VBoxTray.exe
+VBoxControl.exe
+
+[VBoxGuest_Install.Services]
+AddService = VBoxGuest, 0x00000002, VBoxGuest_ServiceInstallSection
+DelService = VBoxTray, 0x00000004
+
+[VBoxGuest_ServiceInstallSection]
+DisplayName    = %VBoxGuest_svcdesc%
+ServiceType    = 0x00000001 ; kernel driver
+StartType      = 0x00000000 ; boot start
+ErrorControl   = 0x00000001 ; normal error handling
+LoadOrderGroup = Base
+ServiceBinary  = %12%\VBoxGuest.sys
+
+[VBoxTray_Add_Reg]
+HKLM, SOFTWARE\Microsoft\Windows\CurrentVersion\Run, VBoxTray, 0x00020000, %%SystemRoot%%\system32\VBoxTray.exe
+
+[ClassInstall32]
+; This should fix the error 0xe0000101 (The required section was not found in the INF).
+
+[Strings]
+ORACLE = "Oracle Corporation"
+VBoxGuest.DeviceDesc = "VirtualBox Guest Device"
+VBoxGuest_svcdesc = "VirtualBox Guest Driver"
+VBoxTray_svcdesc = "VirtualBox Guest Tray"
+VBoxGuest.MediaDesc = "VirtualBox Guest Driver Installation Disk"
diff --git a/src/VBox/Additions/common/VBoxGuest/win/VBoxGuestInst.cpp b/src/VBox/Additions/common/VBoxGuest/win/VBoxGuestInst.cpp
new file mode 100644
index 00000000..2429280c
--- /dev/null
+++ b/src/VBox/Additions/common/VBoxGuest/win/VBoxGuestInst.cpp
@@ -0,0 +1,227 @@
+/* $Id: VBoxGuestInst.cpp $ */
+/** @file
+ * Small tool to (un)install the VBoxGuest device driver (for testing).
+ */
+
+/*
+ * 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 <iprt/win/windows.h>
+
+#include <VBox/VBoxGuest.h> /* for VBOXGUEST_SERVICE_NAME */
+#include <iprt/errcore.h>
+#include <iprt/message.h>
+#include <iprt/stream.h>
+#include <iprt/utf16.h>
+
+
+
+
+static RTEXITCODE installDriver(bool fStartIt)
+{
+    /*
+     * Assume it didn't exist, so we'll create the service.
+     */
+    SC_HANDLE   hSMgrCreate = OpenSCManagerW(NULL, NULL, SERVICE_CHANGE_CONFIG);
+    if (!hSMgrCreate)
+        return RTMsgErrorExitFailure("OpenSCManager(,,create) failed: %u", GetLastError());
+
+    const wchar_t  *pwszSlashName = L"\\VBoxGuest.sys";
+    wchar_t         wszDriver[MAX_PATH * 2];
+    GetCurrentDirectoryW(MAX_PATH, wszDriver);
+    RTUtf16Cat(wszDriver, RT_ELEMENTS(wszDriver), pwszSlashName);
+    if (GetFileAttributesW(wszDriver) == INVALID_FILE_ATTRIBUTES)
+    {
+        GetSystemDirectoryW(wszDriver, MAX_PATH);
+        RTUtf16Cat(wszDriver, RT_ELEMENTS(wszDriver), L"\\drivers");
+        RTUtf16Cat(wszDriver, RT_ELEMENTS(wszDriver), pwszSlashName);
+
+        /* Try FAT name abbreviation. */
+        if (GetFileAttributesW(wszDriver) == INVALID_FILE_ATTRIBUTES)
+        {
+            pwszSlashName = L"\\VBoxGst.sys";
+            GetCurrentDirectoryW(MAX_PATH, wszDriver);
+            RTUtf16Cat(wszDriver, RT_ELEMENTS(wszDriver), pwszSlashName);
+            if (GetFileAttributesW(wszDriver) == INVALID_FILE_ATTRIBUTES)
+            {
+                GetSystemDirectoryW(wszDriver, MAX_PATH);
+                RTUtf16Cat(wszDriver, RT_ELEMENTS(wszDriver), L"\\drivers");
+                RTUtf16Cat(wszDriver, RT_ELEMENTS(wszDriver), pwszSlashName);
+            }
+        }
+    }
+
+    RTEXITCODE rcExit;
+    SC_HANDLE hService = CreateServiceW(hSMgrCreate,
+                                        RT_CONCAT(L,VBOXGUEST_SERVICE_NAME),
+                                        L"VBoxGuest Support Driver",
+                                        SERVICE_QUERY_STATUS | (fStartIt ? SERVICE_START : 0),
+                                        SERVICE_KERNEL_DRIVER,
+                                        SERVICE_BOOT_START,
+                                        SERVICE_ERROR_NORMAL,
+                                        wszDriver,
+                                        L"System",
+                                        NULL, NULL, NULL, NULL);
+    if (hService)
+    {
+        RTMsgInfo("Successfully created service '%s' for driver '%ls'.\n", VBOXGUEST_SERVICE_NAME, wszDriver);
+        rcExit = RTEXITCODE_SUCCESS;
+        if (fStartIt)
+        {
+            if (StartService(hService, 0, NULL))
+                RTMsgInfo("successfully started driver '%ls'\n", wszDriver);
+            else
+                rcExit = RTMsgErrorExitFailure("StartService failed: %u", GetLastError());
+        }
+        CloseServiceHandle(hService);
+    }
+    else
+        rcExit = RTMsgErrorExitFailure("CreateService failed! %u (wszDriver=%ls)\n", GetLastError(), wszDriver);
+    CloseServiceHandle(hSMgrCreate);
+    return rcExit;
+}
+
+
+static RTEXITCODE uninstallDriver(void)
+{
+    SC_HANDLE hSMgr = OpenSCManagerW(NULL, NULL, SERVICE_CHANGE_CONFIG);
+    if (!hSMgr)
+        return RTMsgErrorExitFailure("OpenSCManager(,,change_config) failed: %u", GetLastError());
+
+    RTEXITCODE rcExit;
+    SC_HANDLE hService = OpenServiceW(hSMgr, RT_CONCAT(L, VBOXGUEST_SERVICE_NAME), SERVICE_STOP | SERVICE_QUERY_STATUS | DELETE);
+    if (hService)
+    {
+        /*
+         * Try stop it if it's running.
+         */
+        SERVICE_STATUS  Status = { 0, 0, 0, 0, 0, 0, 0 };
+        QueryServiceStatus(hService, &Status);
+        if (Status.dwCurrentState == SERVICE_STOPPED)
+            rcExit = RTEXITCODE_SUCCESS;
+        else if (ControlService(hService, SERVICE_CONTROL_STOP, &Status))
+        {
+            int iWait = 100;
+            while (Status.dwCurrentState == SERVICE_STOP_PENDING && iWait-- > 0)
+            {
+                Sleep(100);
+                QueryServiceStatus(hService, &Status);
+            }
+            if (Status.dwCurrentState == SERVICE_STOPPED)
+                rcExit = RTEXITCODE_SUCCESS;
+            else
+                rcExit = RTMsgErrorExitFailure("Failed to stop service! Service status: %u (%#x)\n",
+                                                Status.dwCurrentState, Status.dwCurrentState);
+        }
+        else
+            rcExit = RTMsgErrorExitFailure("ControlService failed: %u, Service status: %u (%#x)",
+                                            GetLastError(), Status.dwCurrentState, Status.dwCurrentState);
+
+        /*
+         * Delete the service.
+         */
+        if (rcExit == RTEXITCODE_SUCCESS)
+        {
+            if (DeleteService(hService))
+                RTMsgInfo("Successfully deleted the %s service\n", VBOXGUEST_SERVICE_NAME);
+            else
+                rcExit = RTMsgErrorExitFailure("DeleteService failed: %u", GetLastError());
+        }
+
+        CloseServiceHandle(hService);
+    }
+    else if (GetLastError() == ERROR_SERVICE_DOES_NOT_EXIST)
+    {
+        RTMsgInfo("Nothing to do, the service %s does not exist.\n", VBOXGUEST_SERVICE_NAME);
+        rcExit = RTEXITCODE_SUCCESS;
+    }
+    else
+        rcExit = RTMsgErrorExitFailure("OpenService failed: %u", GetLastError());
+
+    CloseServiceHandle(hSMgr);
+    return rcExit;
+}
+
+
+static RTEXITCODE performTest(void)
+{
+    HANDLE hDevice = CreateFileW(RT_CONCAT(L,VBOXGUEST_DEVICE_NAME), // Win2k+: VBOXGUEST_DEVICE_NAME_GLOBAL
+                                 GENERIC_READ | GENERIC_WRITE,
+                                 FILE_SHARE_READ | FILE_SHARE_WRITE,
+                                 NULL,
+                                 OPEN_EXISTING,
+                                 FILE_ATTRIBUTE_NORMAL,
+                                 NULL);
+    if (hDevice != INVALID_HANDLE_VALUE)
+    {
+        CloseHandle(hDevice);
+        RTMsgInfo("Test succeeded\n");
+        return RTEXITCODE_SUCCESS;
+    }
+    return RTMsgErrorExitFailure("Test failed! Unable to open driver (CreateFileW -> %u).", GetLastError());
+}
+
+
+static RTEXITCODE usage(const char *pszProgName)
+{
+    RTPrintf("\n"
+             "Usage: %s [install|uninstall|test]\n", pszProgName);
+    return RTEXITCODE_SYNTAX;
+}
+
+
+int main(int argc, char **argv)
+{
+    if (argc != 2)
+    {
+        RTMsgError(argc < 2 ? "Too few arguments! Expected one." : "Too many arguments! Expected only one.");
+        return usage(argv[0]);
+    }
+
+    RTEXITCODE rcExit;
+    if (strcmp(argv[1], "install") == 0)
+        rcExit = installDriver(true);
+    else if (strcmp(argv[1], "uninstall") == 0)
+        rcExit = uninstallDriver();
+    else if (strcmp(argv[1], "test") == 0)
+        rcExit = performTest();
+    else
+    {
+        RTMsgError("Unknown argument: '%s'", argv[1]);
+        rcExit = usage(argv[0]);
+    }
+    return rcExit;
+}
+