[VIDEOPRT] Implement support for dynamically choosing V86 vs. X86 emulator on x86 32-bit builds (#8451)

The choice is done by looking for the presence or absence of the `HKLM\System\CurrentControlSet\Control\GraphicsDrivers\DisableEmulator` registry key. For more details, see: https://www.geoffchappell.com/studies/windows/km/hal/api/x86bios/call.htm By default, use V86 in 32-bit Win2k3-compatible builds, otherwise (Vista+) check the presence of the registry key. The X86 emulator routines are exported by the HAL.DLL. They are always exported by the non-x86 HAL. However, they may or may not be exported by the x86 (32-bit) HAL: on NT 5.2 and below they are not exported, while on NT 6.x (Vista+) they are. Therefore: - in our NT <= 5.2 x86 builds, we load the routines at runtime. If they aren't found, we fail emulator support initialization and fall back to VDM V86 support. - in our NT 6.x (x86 or not) builds, we always directly link with the HAL routines, since they are guaranteed to be present there.
2026-06-01 08:50:24 +08:00 · 2023-07-26 22:05:53 +02:00
parent 6313ef9d69
commit 89d5a3dbb8
4 changed files with 473 additions and 144 deletions
--- a/win32ss/drivers/videoprt/dispatch.c
+++ b/win32ss/drivers/videoprt/dispatch.c
@@ -385,10 +385,10 @@ IntVideoPortDispatchOpen(
        ObReferenceObject(CsrProcess);
        INFO_(VIDEOPRT, "CsrProcess 0x%p\n", CsrProcess);

-        Status = IntInitializeVideoAddressSpace();
+        Status = IntInitializeInt10();
        if (!NT_SUCCESS(Status))
        {
-            ERR_(VIDEOPRT, "IntInitializeVideoAddressSpace() failed: 0x%lx\n", Status);
+            ERR_(VIDEOPRT, "IntInitializeInt10() failed: 0x%lx\n", Status);
            ObDereferenceObject(CsrProcess);
            CsrProcess = NULL;
            return Status;
--- a/win32ss/drivers/videoprt/int10.c
+++ b/win32ss/drivers/videoprt/int10.c
@@ -22,20 +22,96 @@
 #include "videoprt.h"

 #include <ndk/kefuncs.h>
-#include <ndk/halfuncs.h>
 #include <ndk/mmfuncs.h>

 #define NDEBUG
 #include <debug.h>

-/* PRIVATE FUNCTIONS **********************************************************/
+/* GLOBAL VARIABLES ***********************************************************/
+
+#ifdef _M_IX86
+/* Use the 32-bit x86 emulator by default, on NT 6.x (Vista+), or on NT 5.x
+ * if the HAL has the necessary exports. Otherwise fall back to V86 mode. */
+BOOLEAN VideoPortDisableX86Emulator = FALSE;
+#endif
+
+KMUTEX VideoPortInt10Mutex;
+
+
+/* X86 EMULATOR & V86 MODE INITIALIZATION *************************************/
+
+#if (NTDDI_VERSION < NTDDI_VISTA) && (DLL_EXPORT_VERSION < _WIN32_WINNT_VISTA)
+/*
+ * x86 Emulator callbacks
+ */
+#include <ndk/haltypes.h> // For X86_BIOS_REGISTERS
+
+static BOOLEAN
+(NTAPI *x86BiosCall)(
+    _In_ ULONG InterruptNumber,
+    _Inout_ PX86_BIOS_REGISTERS Registers);
+
+static NTSTATUS
+(NTAPI *x86BiosAllocateBuffer)(
+    _Inout_ PULONG Size,
+    _Out_ PUSHORT Segment,
+    _Out_ PUSHORT Offset);
+
+static NTSTATUS
+(NTAPI *x86BiosFreeBuffer)(
+    _In_ USHORT Segment,
+    _In_ USHORT Offset);
+
+static NTSTATUS
+(NTAPI *x86BiosReadMemory)(
+    _In_ USHORT Segment,
+    _In_ USHORT Offset,
+    _Out_writes_bytes_(Size) PVOID Buffer,
+    _In_ ULONG Size);
+
+static NTSTATUS
+(NTAPI *x86BiosWriteMemory)(
+    _In_ USHORT Segment,
+    _In_ USHORT Offset,
+    _In_reads_bytes_(Size) PVOID Buffer,
+    _In_ ULONG Size);
+
+#else // (NTDDI_VERSION >= NTDDI_VISTA) || (DLL_EXPORT_VERSION >= _WIN32_WINNT_VISTA)
+#include <ndk/halfuncs.h> // For x86Bios*()
+#endif
+
+static BOOLEAN
+IntInitializeX86Emu(VOID)
+{
+#if (NTDDI_VERSION < NTDDI_VISTA) && (DLL_EXPORT_VERSION < _WIN32_WINNT_VISTA)
+    UNICODE_STRING ImportName;
+#define LOAD_IMPORT(func) \
+    (RtlInitUnicodeString(&ImportName, L ## #func), \
+     (func) = MmGetSystemRoutineAddress(&ImportName))
+
+    if (!LOAD_IMPORT(x86BiosCall)) // Check also HalInitializeBios ?
+        return FALSE; /* No emulator available */
+    if (!LOAD_IMPORT(x86BiosAllocateBuffer))
+        return FALSE;
+    if (!LOAD_IMPORT(x86BiosFreeBuffer))
+        return FALSE;
+    if (!LOAD_IMPORT(x86BiosReadMemory))
+        return FALSE;
+    if (!LOAD_IMPORT(x86BiosWriteMemory))
+        return FALSE;
+#undef LOAD_IMPORT
+#endif
+
+    return TRUE;
+}
+
+#ifdef _M_IX86

 #define IsLowV86Mem(_Seg, _Off) ((((_Seg) << 4) + (_Off)) < (0xa0000))

 /* Those two functions below are there so that CSRSS can't access low mem.
 * Especially, MAKE IT CRASH ON NULL ACCESS */
-static
-VOID
+static VOID
 ProtectLowV86Mem(VOID)
 {
    /* We pass a non-NULL address so that ZwAllocateVirtualMemory really does it
@@ -57,8 +133,7 @@ ProtectLowV86Mem(VOID)
    ASSERT(NT_SUCCESS(Status));
 }

-static
-VOID
+static VOID
 UnprotectLowV86Mem(VOID)
 {
    /* We pass a non-NULL address so that ZwAllocateVirtualMemory really does it
@@ -80,9 +155,8 @@ UnprotectLowV86Mem(VOID)
    ASSERT(NT_SUCCESS(Status));
 }

-#if defined(_M_IX86) || defined(_M_AMD64)
+static inline
 NTSTATUS
-NTAPI
 IntInitializeVideoAddressSpace(VOID)
 {
    OBJECT_ATTRIBUTES ObjectAttributes;
@@ -92,9 +166,7 @@ IntInitializeVideoAddressSpace(VOID)
    PVOID BaseAddress;
    LARGE_INTEGER Offset;
    SIZE_T ViewSize;
-#ifdef _M_IX86
    CHAR IVTAndBda[1024 + 256];
-#endif // _M_IX86

    /* We should only do that for CSRSS */
    ASSERT(PsGetCurrentProcess() == (PEPROCESS)CsrProcess);
@@ -181,7 +253,6 @@ IntInitializeVideoAddressSpace(VOID)
        return 0;
    }

-#ifdef _M_IX86
    /* Get the real mode IVT and BDA from the kernel */
    Status = NtVdmControl(VdmInitialize, IVTAndBda);
    if (!NT_SUCCESS(Status))
@@ -189,7 +260,6 @@ IntInitializeVideoAddressSpace(VOID)
        DPRINT1("NtVdmControl failed (status %x)\n", Status);
        return Status;
    }
-#endif // _M_IX86

    /* Protect the V86 address space after this */
    ProtectLowV86Mem();
@@ -197,33 +267,62 @@ IntInitializeVideoAddressSpace(VOID)
    /* Return success */
    return STATUS_SUCCESS;
 }
-#else
-NTSTATUS
-NTAPI
-IntInitializeVideoAddressSpace(VOID)
-{
-    UNIMPLEMENTED;
-    NT_ASSERT(FALSE);
-    return STATUS_NOT_IMPLEMENTED;
-}
-#endif

-VP_STATUS
+#endif // _M_IX86
+
+
+/* VideoPortServicesInt10 CALLBACKS *******************************************/
+
+#ifdef _M_IX86
+typedef struct _INT10_INTERFACE
+{
+    PINT10_ALLOCATE_BUFFER Int10AllocateBuffer;
+    PINT10_FREE_BUFFER Int10FreeBuffer;
+    PINT10_READ_MEMORY Int10ReadMemory;
+    PINT10_WRITE_MEMORY Int10WriteMemory;
+    PINT10_CALL_BIOS Int10CallBios;
+} INT10_INTERFACE;
+
+// Remark: Instead of `Int10Vtbl->`, one could use: `Int10IFace[VideoPortDisableX86Emulator].`
+static const INT10_INTERFACE *Int10Vtbl; // Int10IFace[2];
+#define INT10(func) Int10Vtbl->Int10##func
+#else
+#define INT10(func) IntInt10##func##Emu
+#endif // _M_IX86
+
+
+static VP_STATUS
 NTAPI
-IntInt10AllocateBuffer(
-    IN PVOID Context,
-    OUT PUSHORT Seg,
-    OUT PUSHORT Off,
-    IN OUT PULONG Length)
+IntInt10AllocateBufferEmu(
+    _In_ PVOID Context,
+    _Out_ PUSHORT Seg,
+    _Out_ PUSHORT Off,
+    _Inout_ PULONG Length)
 {
    NTSTATUS Status;
+
+    UNREFERENCED_PARAMETER(Context);
+
+    Status = x86BiosAllocateBuffer(Length, Seg, Off);
+    return (NT_SUCCESS(Status) ? NO_ERROR : ERROR_NOT_ENOUGH_MEMORY);
+}
+
 #ifdef _M_IX86
+static VP_STATUS
+NTAPI
+IntInt10AllocateBufferV86(
+    _In_ PVOID Context,
+    _Out_ PUSHORT Seg,
+    _Out_ PUSHORT Off,
+    _Inout_ PULONG Length)
+{
+    NTSTATUS Status;
    PVOID MemoryAddress;
    PKPROCESS CallingProcess;
    KAPC_STATE ApcState;
    SIZE_T Size;

-    TRACE_(VIDEOPRT, "IntInt10AllocateBuffer\n");
+    UNREFERENCED_PARAMETER(Context);

    /* Perform the call in the CSRSS context */
    if (!IntAttachToCSRSS(&CallingProcess, &ApcState))
@@ -262,34 +361,63 @@ IntInt10AllocateBuffer(
    *Seg = (USHORT)((ULONG_PTR)MemoryAddress >> 4);
    *Off = (USHORT)((ULONG_PTR)MemoryAddress & 0xF);

-    INFO_(VIDEOPRT, "- Segment: %x\n", *Seg);
-    INFO_(VIDEOPRT, "- Offset: %x\n", *Off);
-    INFO_(VIDEOPRT, "- Length: %x\n", *Length);
-
    return NO_ERROR;
-#else
-    Status = x86BiosAllocateBuffer(Length, Seg, Off);
-    return NT_SUCCESS(Status) ? NO_ERROR : ERROR_NOT_ENOUGH_MEMORY;
-#endif
 }
+#endif // _M_IX86

 VP_STATUS
 NTAPI
-IntInt10FreeBuffer(
-    IN PVOID Context,
-    IN USHORT Seg,
-    IN USHORT Off)
+IntInt10AllocateBuffer(
+    _In_ PVOID Context,
+    _Out_ PUSHORT Seg,
+    _Out_ PUSHORT Off,
+    _Inout_ PULONG Length)
+{
+    VP_STATUS Status;
+
+    TRACE_(VIDEOPRT, "IntInt10AllocateBuffer\n");
+
+    Status = INT10(AllocateBuffer)(Context, Seg, Off, Length);
+    if (Status == NO_ERROR)
+    {
+        INFO_(VIDEOPRT, "- Segment: 0x%x\n", *Seg);
+        INFO_(VIDEOPRT, "- Offset : 0x%x\n", *Off);
+        INFO_(VIDEOPRT, "- Length : 0x%x\n", *Length);
+    }
+    return Status;
+}
+
+
+static VP_STATUS
+NTAPI
+IntInt10FreeBufferEmu(
+    _In_ PVOID Context,
+    _In_ USHORT Seg,
+    _In_ USHORT Off)
 {
    NTSTATUS Status;
+
+    UNREFERENCED_PARAMETER(Context);
+
+    Status = x86BiosFreeBuffer(Seg, Off);
+    return (NT_SUCCESS(Status) ? NO_ERROR : ERROR_INVALID_PARAMETER);
+}
+
 #ifdef _M_IX86
+static VP_STATUS
+NTAPI
+IntInt10FreeBufferV86(
+    _In_ PVOID Context,
+    _In_ USHORT Seg,
+    _In_ USHORT Off)
+{
+    NTSTATUS Status;
    PVOID MemoryAddress = (PVOID)((ULONG_PTR)(Seg << 4) | Off);
    PKPROCESS CallingProcess;
    KAPC_STATE ApcState;
    SIZE_T Size = 0;

-    TRACE_(VIDEOPRT, "IntInt10FreeBuffer\n");
-    INFO_(VIDEOPRT, "- Segment: %x\n", Seg);
-    INFO_(VIDEOPRT, "- Offset: %x\n", Off);
+    UNREFERENCED_PARAMETER(Context);

    /* Perform the call in the CSRSS context */
    if (!IntAttachToCSRSS(&CallingProcess, &ApcState))
@@ -303,30 +431,55 @@ IntInt10FreeBuffer(
    IntDetachFromCSRSS(CallingProcess, &ApcState);

    return Status;
-#else
-    Status = x86BiosFreeBuffer(Seg, Off);
-    return NT_SUCCESS(Status) ? NO_ERROR : ERROR_INVALID_PARAMETER;
-#endif
 }
+#endif // _M_IX86

 VP_STATUS
 NTAPI
-IntInt10ReadMemory(
-    IN PVOID Context,
-    IN USHORT Seg,
-    IN USHORT Off,
-    OUT PVOID Buffer,
-    IN ULONG Length)
+IntInt10FreeBuffer(
+    _In_ PVOID Context,
+    _In_ USHORT Seg,
+    _In_ USHORT Off)
 {
+    TRACE_(VIDEOPRT, "IntInt10FreeBuffer\n");
+    INFO_(VIDEOPRT, "- Segment: 0x%x\n", Seg);
+    INFO_(VIDEOPRT, "- Offset : 0x%x\n", Off);
+
+    return INT10(FreeBuffer)(Context, Seg, Off);
+}
+
+
+static VP_STATUS
+NTAPI
+IntInt10ReadMemoryEmu(
+    _In_ PVOID Context,
+    _In_ USHORT Seg,
+    _In_ USHORT Off,
+    _Out_writes_bytes_(Length) PVOID Buffer,
+    _In_ ULONG Length)
+{
+    NTSTATUS Status;
+
+    UNREFERENCED_PARAMETER(Context);
+
+    Status = x86BiosReadMemory(Seg, Off, Buffer, Length);
+    return (NT_SUCCESS(Status) ? NO_ERROR : ERROR_INVALID_PARAMETER);
+}
+
 #ifdef _M_IX86
+static VP_STATUS
+NTAPI
+IntInt10ReadMemoryV86(
+    _In_ PVOID Context,
+    _In_ USHORT Seg,
+    _In_ USHORT Off,
+    _Out_writes_bytes_(Length) PVOID Buffer,
+    _In_ ULONG Length)
+{
    PKPROCESS CallingProcess;
    KAPC_STATE ApcState;

-    TRACE_(VIDEOPRT, "IntInt10ReadMemory\n");
-    INFO_(VIDEOPRT, "- Segment: %x\n", Seg);
-    INFO_(VIDEOPRT, "- Offset: %x\n", Off);
-    INFO_(VIDEOPRT, "- Buffer: %x\n", Buffer);
-    INFO_(VIDEOPRT, "- Length: %x\n", Length);
+    UNREFERENCED_PARAMETER(Context);

    /* Perform the call in the CSRSS context */
    if (!IntAttachToCSRSS(&CallingProcess, &ApcState))
@@ -341,32 +494,59 @@ IntInt10ReadMemory(
    IntDetachFromCSRSS(CallingProcess, &ApcState);

    return NO_ERROR;
-#else
-    NTSTATUS Status;
-
-    Status = x86BiosReadMemory(Seg, Off, Buffer, Length);
-    return NT_SUCCESS(Status) ? NO_ERROR : ERROR_INVALID_PARAMETER;
-#endif
 }
+#endif // _M_IX86

 VP_STATUS
 NTAPI
-IntInt10WriteMemory(
-    IN PVOID Context,
-    IN USHORT Seg,
-    IN USHORT Off,
-    IN PVOID Buffer,
-    IN ULONG Length)
+IntInt10ReadMemory(
+    _In_ PVOID Context,
+    _In_ USHORT Seg,
+    _In_ USHORT Off,
+    _Out_writes_bytes_(Length) PVOID Buffer,
+    _In_ ULONG Length)
 {
+    TRACE_(VIDEOPRT, "IntInt10ReadMemory\n");
+    INFO_(VIDEOPRT, "- Segment: 0x%x\n", Seg);
+    INFO_(VIDEOPRT, "- Offset : 0x%x\n", Off);
+    INFO_(VIDEOPRT, "- Buffer : 0x%x\n", Buffer);
+    INFO_(VIDEOPRT, "- Length : 0x%x\n", Length);
+
+    return INT10(ReadMemory)(Context, Seg, Off, Buffer, Length);
+}
+
+
+static VP_STATUS
+NTAPI
+IntInt10WriteMemoryEmu(
+    _In_ PVOID Context,
+    _In_ USHORT Seg,
+    _In_ USHORT Off,
+    _In_reads_bytes_(Length) PVOID Buffer,
+    _In_ ULONG Length)
+{
+    NTSTATUS Status;
+
+    UNREFERENCED_PARAMETER(Context);
+
+    Status = x86BiosWriteMemory(Seg, Off, Buffer, Length);
+    return (NT_SUCCESS(Status) ? NO_ERROR : ERROR_INVALID_PARAMETER);
+}
+
 #ifdef _M_IX86
+static VP_STATUS
+NTAPI
+IntInt10WriteMemoryV86(
+    _In_ PVOID Context,
+    _In_ USHORT Seg,
+    _In_ USHORT Off,
+    _In_reads_bytes_(Length) PVOID Buffer,
+    _In_ ULONG Length)
+{
    PKPROCESS CallingProcess;
    KAPC_STATE ApcState;

-    TRACE_(VIDEOPRT, "IntInt10WriteMemory\n");
-    INFO_(VIDEOPRT, "- Segment: %x\n", Seg);
-    INFO_(VIDEOPRT, "- Offset: %x\n", Off);
-    INFO_(VIDEOPRT, "- Buffer: %x\n", Buffer);
-    INFO_(VIDEOPRT, "- Length: %x\n", Length);
+    UNREFERENCED_PARAMETER(Context);

    /* Perform the call in the CSRSS context */
    if (!IntAttachToCSRSS(&CallingProcess, &ApcState))
@@ -381,29 +561,90 @@ IntInt10WriteMemory(
    IntDetachFromCSRSS(CallingProcess, &ApcState);

    return NO_ERROR;
-#else
-    NTSTATUS Status;
-
-    Status = x86BiosWriteMemory(Seg, Off, Buffer, Length);
-    return NT_SUCCESS(Status) ? NO_ERROR : ERROR_INVALID_PARAMETER;
-#endif
 }
+#endif // _M_IX86

 VP_STATUS
 NTAPI
-IntInt10CallBios(
-    IN PVOID Context,
-    IN OUT PINT10_BIOS_ARGUMENTS BiosArguments)
+IntInt10WriteMemory(
+    _In_ PVOID Context,
+    _In_ USHORT Seg,
+    _In_ USHORT Off,
+    _In_reads_bytes_(Length) PVOID Buffer,
+    _In_ ULONG Length)
+{
+    TRACE_(VIDEOPRT, "IntInt10WriteMemory\n");
+    INFO_(VIDEOPRT, "- Segment: 0x%x\n", Seg);
+    INFO_(VIDEOPRT, "- Offset : 0x%x\n", Off);
+    INFO_(VIDEOPRT, "- Buffer : 0x%x\n", Buffer);
+    INFO_(VIDEOPRT, "- Length : 0x%x\n", Length);
+
+    return INT10(WriteMemory)(Context, Seg, Off, Buffer, Length);
+}
+
+
+static VP_STATUS
+NTAPI
+IntInt10CallBiosEmu(
+    _In_ PVOID Context,
+    _Inout_ PINT10_BIOS_ARGUMENTS BiosArguments)
 {
-#ifdef _M_AMD64
    X86_BIOS_REGISTERS BiosContext;
-#else
+    BOOLEAN Success;
+
+    UNREFERENCED_PARAMETER(Context);
+
+    /* Clear the context and fill out the BIOS arguments */
+    RtlZeroMemory(&BiosContext, sizeof(BiosContext));
+    BiosContext.Eax = BiosArguments->Eax;
+    BiosContext.Ebx = BiosArguments->Ebx;
+    BiosContext.Ecx = BiosArguments->Ecx;
+    BiosContext.Edx = BiosArguments->Edx;
+    BiosContext.Esi = BiosArguments->Esi;
+    BiosContext.Edi = BiosArguments->Edi;
+    BiosContext.Ebp = BiosArguments->Ebp;
+    BiosContext.SegDs = BiosArguments->SegDs;
+    BiosContext.SegEs = BiosArguments->SegEs;
+
+    /* Do the ROM BIOS call */
+    (void)KeWaitForMutexObject(&VideoPortInt10Mutex,
+                               Executive,
+                               KernelMode,
+                               FALSE,
+                               NULL);
+
+    Success = x86BiosCall(0x10, &BiosContext);
+
+    KeReleaseMutex(&VideoPortInt10Mutex, FALSE);
+
+    /* Return the arguments */
+    BiosArguments->Eax = BiosContext.Eax;
+    BiosArguments->Ebx = BiosContext.Ebx;
+    BiosArguments->Ecx = BiosContext.Ecx;
+    BiosArguments->Edx = BiosContext.Edx;
+    BiosArguments->Esi = BiosContext.Esi;
+    BiosArguments->Edi = BiosContext.Edi;
+    BiosArguments->Ebp = BiosContext.Ebp;
+    BiosArguments->SegDs = (USHORT)BiosContext.SegDs;
+    BiosArguments->SegEs = (USHORT)BiosContext.SegEs;
+
+    return (Success ? NO_ERROR : ERROR_INVALID_PARAMETER);
+}
+
+#ifdef _M_IX86
+static VP_STATUS
+NTAPI
+IntInt10CallBiosV86(
+    _In_ PVOID Context,
+    _Inout_ PINT10_BIOS_ARGUMENTS BiosArguments)
+{
    CONTEXT BiosContext;
-#endif
    NTSTATUS Status;
    PKPROCESS CallingProcess;
    KAPC_STATE ApcState;

+    UNREFERENCED_PARAMETER(Context);
+
    /* Clear the context and fill out the BIOS arguments */
    RtlZeroMemory(&BiosContext, sizeof(BiosContext));
    BiosContext.Eax = BiosArguments->Eax;
@@ -429,11 +670,18 @@ IntInt10CallBios(

    /* The kernel needs access here */
    UnprotectLowV86Mem();
-#ifdef _M_AMD64
-    Status = x86BiosCall(0x10, &BiosContext) ? STATUS_SUCCESS : STATUS_UNSUCCESSFUL;
-#else
-    Status = Ke386CallBios(0x10, &BiosContext);
-#endif
+
+    /* Invoke the V86 monitor under SEH, as it can raise exceptions */
+    _SEH2_TRY
+    {
+        Status = Ke386CallBios(0x10, &BiosContext);
+    }
+    _SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
+    {
+        Status = _SEH2_GetExceptionCode();
+    }
+    _SEH2_END;
+
    ProtectLowV86Mem();

    KeReleaseMutex(&VideoPortInt10Mutex, FALSE);
@@ -451,8 +699,67 @@ IntInt10CallBios(
    BiosArguments->SegDs = (USHORT)BiosContext.SegDs;
    BiosArguments->SegEs = (USHORT)BiosContext.SegEs;

-    return NT_SUCCESS(Status) ? NO_ERROR : ERROR_INVALID_PARAMETER;
+    return (NT_SUCCESS(Status) ? NO_ERROR : ERROR_INVALID_PARAMETER);
 }
+#endif // _M_IX86
+
+VP_STATUS
+NTAPI
+IntInt10CallBios(
+    _In_ PVOID Context,
+    _Inout_ PINT10_BIOS_ARGUMENTS BiosArguments)
+{
+    return INT10(CallBios)(Context, BiosArguments);
+}
+
+
+#ifdef _M_IX86
+static const INT10_INTERFACE Int10IFace[2] =
+{ { IntInt10AllocateBufferEmu,
+    IntInt10FreeBufferEmu,
+    IntInt10ReadMemoryEmu,
+    IntInt10WriteMemoryEmu,
+    IntInt10CallBiosEmu }
+  ,
+  { IntInt10AllocateBufferV86,
+    IntInt10FreeBufferV86,
+    IntInt10ReadMemoryV86,
+    IntInt10WriteMemoryV86,
+    IntInt10CallBiosV86 }
+};
+static const INT10_INTERFACE *Int10Vtbl = &Int10IFace[0];
+#endif
+
+
+/* PRIVATE FUNCTIONS **********************************************************/
+
+NTSTATUS
+IntInitializeInt10(VOID)
+{
+#ifdef _M_IX86
+    /* We should only do that for CSRSS */
+    ASSERT(PsGetCurrentProcess() == (PEPROCESS)CsrProcess);
+
+    /* Initialize the x86 emulator if necessary, otherwise fall back to V86 mode */
+    if (!VideoPortDisableX86Emulator)
+    {
+        /* Use the emulation routines */
+        //Int10Vtbl = &Int10IFace[0];
+        if (IntInitializeX86Emu())
+            return STATUS_SUCCESS;
+        DPRINT1("Could not initialize the x86 emulator; falling back to V86 mode\n");
+        VideoPortDisableX86Emulator = TRUE;
+    }
+
+    /* Fall back to the V86 routines */
+    Int10Vtbl = &Int10IFace[1];
+    return IntInitializeVideoAddressSpace();
+#else
+    /* Initialize the x86 emulator */
+    return (IntInitializeX86Emu() ? STATUS_SUCCESS : STATUS_NOT_SUPPORTED);
+#endif
+}
+

 /* PUBLIC FUNCTIONS ***********************************************************/

@@ -465,13 +772,8 @@ VideoPortInt10(
    IN PVOID HwDeviceExtension,
    IN PVIDEO_X86_BIOS_ARGUMENTS BiosArguments)
 {
-    INT10_BIOS_ARGUMENTS Int10BiosArguments;
    VP_STATUS Status;
-
-    if (!CsrProcess)
-    {
-        return ERROR_INVALID_PARAMETER;
-    }
+    INT10_BIOS_ARGUMENTS Int10BiosArguments;

    /* Copy arguments to other format */
    RtlCopyMemory(&Int10BiosArguments, BiosArguments, sizeof(*BiosArguments));
--- a/win32ss/drivers/videoprt/videoprt.c
+++ b/win32ss/drivers/videoprt/videoprt.c
@@ -39,7 +39,7 @@ BOOLEAN VpNoVesa = FALSE;
 PKPROCESS CsrProcess = NULL;
 static ULONG VideoPortMaxObjectNumber = -1;
 BOOLEAN VideoPortUseNewKey = FALSE;
-KMUTEX VideoPortInt10Mutex;
+
 KSPIN_LOCK HwResetAdaptersLock;
 RTL_STATIC_LIST_HEAD(HwResetAdaptersList);

@@ -628,21 +628,21 @@ IntLoadRegistryParameters(VOID)
 {
    NTSTATUS Status;
    HANDLE KeyHandle;
-    UNICODE_STRING UseNewKeyPath = RTL_CONSTANT_STRING(L"\\Registry\\Machine\\System\\CurrentControlSet\\Control\\GraphicsDrivers\\UseNewKey");
-    UNICODE_STRING Path = RTL_CONSTANT_STRING(L"\\Registry\\Machine\\System\\CurrentControlSet\\Control");
+    UNICODE_STRING KeyPath;
    UNICODE_STRING ValueName = RTL_CONSTANT_STRING(L"SystemStartOptions");
    OBJECT_ATTRIBUTES ObjectAttributes;
    PKEY_VALUE_PARTIAL_INFORMATION KeyInfo;
    ULONG Length, NewLength;

    /* Check if we need to use new registry */
+    RtlInitUnicodeString(&KeyPath, L"\\Registry\\Machine\\System\\CurrentControlSet\\Control\\GraphicsDrivers\\UseNewKey");
    InitializeObjectAttributes(&ObjectAttributes,
-                               &UseNewKeyPath,
+                               &KeyPath,
                               OBJ_CASE_INSENSITIVE | OBJ_KERNEL_HANDLE,
                               NULL,
                               NULL);
    Status = ZwOpenKey(&KeyHandle,
-                       GENERIC_READ | GENERIC_WRITE,
+                       KEY_QUERY_VALUE,
                       &ObjectAttributes);
    if (NT_SUCCESS(Status))
    {
@@ -650,9 +650,29 @@ IntLoadRegistryParameters(VOID)
        ZwClose(KeyHandle);
    }

-    /* Initialize object attributes with the path we want */
+#ifdef _M_IX86
+    /* Check whether we need to use the 32-bit x86 emulator instead of V86 mode */
+    RtlInitUnicodeString(&KeyPath, L"\\Registry\\Machine\\System\\CurrentControlSet\\Control\\GraphicsDrivers\\DisableEmulator");
    InitializeObjectAttributes(&ObjectAttributes,
-                               &Path,
+                               &KeyPath,
+                               OBJ_CASE_INSENSITIVE | OBJ_KERNEL_HANDLE,
+                               NULL,
+                               NULL);
+    Status = ZwOpenKey(&KeyHandle,
+                       KEY_QUERY_VALUE,
+                       &ObjectAttributes);
+    if (NT_SUCCESS(Status))
+    {
+        VideoPortDisableX86Emulator = TRUE;
+        ZwClose(KeyHandle);
+    }
+    DPRINT1("Using %s\n", VideoPortDisableX86Emulator ? "V86 mode" : "x86 emulator");
+#endif // _M_IX86
+
+    /* Initialize object attributes with the path we want */
+    RtlInitUnicodeString(&KeyPath, L"\\Registry\\Machine\\System\\CurrentControlSet\\Control");
+    InitializeObjectAttributes(&ObjectAttributes,
+                               &KeyPath,
                               OBJ_CASE_INSENSITIVE | OBJ_KERNEL_HANDLE,
                               NULL,
                               NULL);
@@ -677,7 +697,7 @@ IntLoadRegistryParameters(VOID)
    if (Status != STATUS_BUFFER_OVERFLOW && Status != STATUS_BUFFER_TOO_SMALL)
    {
        VideoPortDebugPrint(Error, "ZwQueryValueKey failed (0x%x)\n", Status);
-        ObCloseHandle(KeyHandle, KernelMode);
+        ZwClose(KeyHandle);
        return;
    }

@@ -686,7 +706,7 @@ IntLoadRegistryParameters(VOID)
    if (!KeyInfo)
    {
        VideoPortDebugPrint(Error, "Out of memory\n");
-        ObCloseHandle(KeyHandle, KernelMode);
+        ZwClose(KeyHandle);
        return;
    }

@@ -697,7 +717,7 @@ IntLoadRegistryParameters(VOID)
                             KeyInfo,
                             Length,
                             &NewLength);
-    ObCloseHandle(KeyHandle, KernelMode);
+    ZwClose(KeyHandle);

    if (!NT_SUCCESS(Status))
    {
@@ -733,10 +753,9 @@ IntLoadRegistryParameters(VOID)
    /* If we are in BASEVIDEO, create the volatile registry key for Win32k */
    if (VpBaseVideo)
    {
-        RtlInitUnicodeString(&Path, L"\\Registry\\Machine\\System\\CurrentControlSet\\Control\\GraphicsDrivers\\BaseVideo");
-
+        RtlInitUnicodeString(&KeyPath, L"\\Registry\\Machine\\System\\CurrentControlSet\\Control\\GraphicsDrivers\\BaseVideo");
        InitializeObjectAttributes(&ObjectAttributes,
-                                   &Path,
+                                   &KeyPath,
                                   OBJ_CASE_INSENSITIVE | OBJ_KERNEL_HANDLE,
                                   NULL,
                                   NULL);
@@ -749,7 +768,7 @@ IntLoadRegistryParameters(VOID)
                             REG_OPTION_VOLATILE,
                             NULL);
        if (NT_SUCCESS(Status))
-            ObCloseHandle(KeyHandle, KernelMode);
+            ZwClose(KeyHandle);
        else
            ERR_(VIDEOPRT, "Failed to create the BaseVideo key (0x%x)\n", Status);
    }
--- a/win32ss/drivers/videoprt/videoprt.h
+++ b/win32ss/drivers/videoprt/videoprt.h
@@ -254,7 +254,7 @@ IntVideoPortMapPhysicalMemory(
 extern PKPROCESS CsrProcess;
 extern ULONG VideoPortDeviceNumber;
 extern BOOLEAN VideoPortUseNewKey;
-extern KMUTEX VideoPortInt10Mutex;
+
 extern KSPIN_LOCK HwResetAdaptersLock;
 extern LIST_ENTRY HwResetAdaptersList;

@@ -298,43 +298,52 @@ IntVideoPortEnumerateChildren(

 /* int10.c */

+#ifdef _M_IX86
+extern BOOLEAN VideoPortDisableX86Emulator;
+#endif
+extern KMUTEX VideoPortInt10Mutex;
+
 NTSTATUS
+IntInitializeInt10(VOID);
+
+VP_STATUS
 NTAPI
-IntInitializeVideoAddressSpace(VOID);
-
-VP_STATUS NTAPI
 IntInt10AllocateBuffer(
-   IN PVOID Context,
-   OUT PUSHORT Seg,
-   OUT PUSHORT Off,
-   IN OUT PULONG Length);
+    _In_ PVOID Context,
+    _Out_ PUSHORT Seg,
+    _Out_ PUSHORT Off,
+    _Inout_ PULONG Length);

-VP_STATUS NTAPI
+VP_STATUS
+NTAPI
 IntInt10FreeBuffer(
-   IN PVOID Context,
-   IN USHORT Seg,
-   IN USHORT Off);
+    _In_ PVOID Context,
+    _In_ USHORT Seg,
+    _In_ USHORT Off);

-VP_STATUS NTAPI
+VP_STATUS
+NTAPI
 IntInt10ReadMemory(
-   IN PVOID Context,
-   IN USHORT Seg,
-   IN USHORT Off,
-   OUT PVOID Buffer,
-   IN ULONG Length);
+    _In_ PVOID Context,
+    _In_ USHORT Seg,
+    _In_ USHORT Off,
+    _Out_writes_bytes_(Length) PVOID Buffer,
+    _In_ ULONG Length);

-VP_STATUS NTAPI
+VP_STATUS
+NTAPI
 IntInt10WriteMemory(
-   IN PVOID Context,
-   IN USHORT Seg,
-   IN USHORT Off,
-   IN PVOID Buffer,
-   IN ULONG Length);
+    _In_ PVOID Context,
+    _In_ USHORT Seg,
+    _In_ USHORT Off,
+    _In_reads_bytes_(Length) PVOID Buffer,
+    _In_ ULONG Length);

-VP_STATUS NTAPI
+VP_STATUS
+NTAPI
 IntInt10CallBios(
-   IN PVOID Context,
-   IN OUT PINT10_BIOS_ARGUMENTS BiosArguments);
+    _In_ PVOID Context,
+    _Inout_ PINT10_BIOS_ARGUMENTS BiosArguments);

 /* registry.c */

@@ -368,5 +377,4 @@ IntCreateRegistryPath(
    IN ULONG DeviceNumber,
    OUT PUNICODE_STRING DeviceRegistryPath);

-
 #endif /* VIDEOPRT_H */