uint32_t VBoxGetHeightReduction()
{
    uint32_t retHeight = 0;
    int rc;

    LOGF_ENTER();

    VMMDevGetHeightReductionRequest *req = NULL;

    rc = VbglGRAlloc((VMMDevRequestHeader**)&req, sizeof(VMMDevGetHeightReductionRequest), VMMDevReq_GetHeightReduction);
    if (RT_FAILURE(rc))
    {
        WARN(("ERROR allocating request, rc = %#xrc", rc));
    }
    else
    {
        rc = VbglGRPerform(&req->header);
        if (RT_SUCCESS(rc))
        {
            retHeight = req->heightReduction;
        }
        else
        {
            WARN(("ERROR querying height reduction value from VMMDev. rc = %#xrc", rc));
        }
        VbglGRFree(&req->header);
    }

    LOGF_LEAVE();
    return retHeight;
}

/*
 * Display driver callbacks.
 */
BOOL APIENTRY VBoxDispDrvSetPalette(DHPDEV dhpdev, PALOBJ *ppalo, FLONG fl, ULONG iStart, ULONG cColors)
{
    BYTE aClut[MAX_CLUT_SIZE];
    PVIDEO_CLUT pClut = (PVIDEO_CLUT) aClut;
    PVIDEO_CLUTDATA pData = &pClut->LookupTable[0].RgbArray;
    PVBOXDISPDEV pDev = (PVBOXDISPDEV)dhpdev;
    NOREF(fl);
    int rc;
    LOGF_ENTER();

    pClut->NumEntries = (USHORT) cColors;
    pClut->FirstEntry = (USHORT) iStart;

    /* Copy PALOBJ colors to PVIDEO_CLUT */
    if (cColors != PALOBJ_cGetColors(ppalo, iStart, cColors, (ULONG*) pData))
    {
        WARN(("PALOBJ_cGetColors failed"));
        return FALSE;
    }

    /* Set reserved bytes to 0 and perform shifting if needed */
    for (ULONG idx=0; idx<cColors; ++idx)
    {
        pData[idx].Unused = 0;
        if (pDev->mode.ulPaletteShift)
        {
            pData[idx].Red >>= pDev->mode.ulPaletteShift;
            pData[idx].Green >>= pDev->mode.ulPaletteShift;
            pData[idx].Blue >>= pDev->mode.ulPaletteShift;
        }
    }

VOID APIENTRY VBoxDispDrvDisableSurface(DHPDEV dhpdev)
{
    PVBOXDISPDEV pDev = (PVBOXDISPDEV)dhpdev;
    LOGF_ENTER();

    if (pDev->surface.hSurface)
    {
        EngDeleteSurface(pDev->surface.hSurface);
        pDev->surface.hSurface = NULL;
    }

    if (pDev->surface.psoBitmap)
    {
        Assert(pDev->surface.hBitmap);
        EngUnlockSurface(pDev->surface.psoBitmap);
        pDev->surface.psoBitmap = NULL;
    }

    if (pDev->surface.hBitmap)
    {
        EngDeleteSurface((HSURF) pDev->surface.hBitmap);
        pDev->surface.hBitmap = NULL;
    }

    int rc;
    rc = VBoxDispMPUnmapMemory(pDev);
    VBOX_WARNRC(rc);

    LOGF_LEAVE();
}

BOOL APIENTRY
VBoxDispDrvRealizeBrush(BRUSHOBJ *pbo, SURFOBJ *psoTarget, SURFOBJ *psoPattern, SURFOBJ *psoMask,
                        XLATEOBJ *pxlo, ULONG iHatch)
{
    BOOL bRc = FALSE;
    LOGF_ENTER();

    if (VBoxDispIsScreenSurface(psoTarget))
    {
        PVBOXDISPDEV pDev = (PVBOXDISPDEV)psoTarget->dhpdev;

        if (pDev->vbvaCtx.pVBVA && (pDev->vbvaCtx.pVBVA->hostFlags.u32HostEvents & VBVA_F_MODE_ENABLED))
        {
            if (pDev->vbvaCtx.pVBVA->hostFlags.u32HostEvents & VBOX_VIDEO_INFO_HOST_EVENTS_F_VRDP_RESET)
            {
                vrdpReset(pDev);
                pDev->vbvaCtx.pVBVA->hostFlags.u32HostEvents &= ~VBOX_VIDEO_INFO_HOST_EVENTS_F_VRDP_RESET;
            }

            if (pDev->vbvaCtx.pVBVA->hostFlags.u32HostEvents & VBVA_F_MODE_VRDP)
            {
                bRc = vrdpDrvRealizeBrush(pbo, psoTarget, psoPattern, psoMask, pxlo, iHatch);
            }
        }
    }

    LOGF_LEAVE();
    return bRc;
}

/* Called to reset adapter to a given character mode. */
static BOOLEAN
VBoxDrvResetHW(PVOID HwDeviceExtension, ULONG Columns, ULONG Rows)
{
    RT_NOREF(Columns, Rows);
    PVBOXMP_DEVEXT pExt = (PVBOXMP_DEVEXT) HwDeviceExtension;

    LOGF_ENTER();

    if (pExt->iDevice==0) /* Primary device */
    {
        VideoPortWritePortUshort((PUSHORT)VBE_DISPI_IOPORT_INDEX, VBE_DISPI_INDEX_ENABLE);
        VideoPortWritePortUshort((PUSHORT)VBE_DISPI_IOPORT_DATA, VBE_DISPI_DISABLED);

#if 0
        /* ResetHW is not the place to do such cleanup. See MSDN. */
        if (pExt->u.primary.pvReqFlush != NULL)
        {
            VbglR0GRFree((VMMDevRequestHeader *)pExt->u.primary.pvReqFlush);
            pExt->u.primary.pvReqFlush = NULL;
        }

        VbglR0TerminateClient();

        VBoxFreeDisplaysHGSMI(VBoxCommonFromDeviceExt(pExt));
#endif
    }
    else
    {
        LOG(("ignoring non primary device %d", pExt->iDevice));
    }

    LOGF_LEAVE();
    /* Tell the system to use VGA BIOS to set the text video mode. */
    return FALSE;
}

/* Called to enumerate child devices of our adapter, attached monitor(s) in our case */
static VP_STATUS
VBoxDrvGetVideoChildDescriptor(PVOID HwDeviceExtension, PVIDEO_CHILD_ENUM_INFO ChildEnumInfo,
                               PVIDEO_CHILD_TYPE VideoChildType, PUCHAR pChildDescriptor, PULONG pUId,
                               PULONG pUnused)
{
    RT_NOREF(pChildDescriptor, pUnused);
    PVBOXMP_DEVEXT pExt = (PVBOXMP_DEVEXT) HwDeviceExtension;

    PAGED_CODE();
    LOGF_ENTER();

    if (ChildEnumInfo->ChildIndex>0)
    {
        if ((int)ChildEnumInfo->ChildIndex <= VBoxCommonFromDeviceExt(pExt)->cDisplays)
        {
            *VideoChildType = Monitor;
            *pUId = ChildEnumInfo->ChildIndex;

            LOGF_LEAVE();
            return VIDEO_ENUM_MORE_DEVICES;
        }
    }
    LOGF_LEAVE();
    return ERROR_NO_MORE_DEVICES;
}

VOID APIENTRY VBoxDispDrvDisableDirectDraw(DHPDEV  dhpdev)
{
    RT_NOREF(dhpdev);
    LOGF_ENTER();
    LOGF_LEAVE();
    return;
}

/* Initial device configuration. */
static BOOLEAN
VBoxDrvInitialize(PVOID HwDeviceExtension)
{
    PVBOXMP_DEVEXT pExt = (PVBOXMP_DEVEXT) HwDeviceExtension;
    USHORT DispiId;

    PAGED_CODE();
    LOGF_ENTER();

    /* Initialize the request pointer. */
    pExt->u.primary.pvReqFlush = NULL;

    /* Check if the chip restricts horizontal resolution or not. */
    VideoPortWritePortUshort((PUSHORT)VBE_DISPI_IOPORT_INDEX, VBE_DISPI_INDEX_ID);
    VideoPortWritePortUshort((PUSHORT)VBE_DISPI_IOPORT_DATA, VBE_DISPI_ID_ANYX);
    DispiId = VideoPortReadPortUshort((PUSHORT)VBE_DISPI_IOPORT_DATA);

    if (DispiId == VBE_DISPI_ID_ANYX)
        pExt->fAnyX = TRUE;
    else
        pExt->fAnyX = FALSE;

    VBoxMPCmnInitCustomVideoModes(pExt);

    LOGF_LEAVE();
    return TRUE;
}

/* Driver entry point */
NTSTATUS DriverEntry(IN PDRIVER_OBJECT DriverObject, IN PUNICODE_STRING RegistryPath)
{
    NOREF(RegistryPath);
    PAGED_CODE();

    int irc = RTR0Init(0);
    if (RT_FAILURE(irc))
    {
        LOGREL(("failed to init IPRT (rc=%#x)", irc));
        return STATUS_INTERNAL_ERROR;
    }
    LOGF_ENTER();

    DriverObject->DriverUnload = VBoxDrvUnload;
    DriverObject->DriverExtension->AddDevice = VBoxDrvAddDevice;

    for (int i=0; i<=IRP_MJ_MAXIMUM_FUNCTION; ++i)
    {
        DriverObject->MajorFunction[i] = VBoxIrpPassthrough;
    }

    DriverObject->MajorFunction[IRP_MJ_INTERNAL_DEVICE_CONTROL] = VBoxIrpInternalIOCTL;
    DriverObject->MajorFunction[IRP_MJ_PNP] = VBoxIrpPnP;
    DriverObject->MajorFunction[IRP_MJ_POWER] = VBoxIrpPower;

    NTSTATUS tmpStatus = VBoxNewProtInit();
    if (!NT_SUCCESS(tmpStatus))
    {
        WARN(("VBoxNewProtInit failed Status (0x%x)", tmpStatus));
    }

    LOGF_LEAVE();
    return STATUS_SUCCESS;
}

/* Called for IOCTL_VIDEO_QUERY_HGSMI_INFO.
 * Returns hgsmi info for this adapter.
 */
BOOLEAN VBoxMPQueryHgsmiInfo(PVBOXMP_DEVEXT pExt, QUERYHGSMIRESULT *pResult, PSTATUS_BLOCK pStatus)
{
    BOOLEAN bRC = TRUE;
    LOGF_ENTER();

    if (VBoxCommonFromDeviceExt(pExt)->bHGSMI)
    {
        pResult->iDevice = pExt->iDevice;
        pResult->ulFlags = 0;
        pResult->areaDisplay = pExt->areaDisplay;
        pResult->u32DisplayInfoSize   = VBVA_DISPLAY_INFORMATION_SIZE;
        pResult->u32MinVBVABufferSize = VBVA_MIN_BUFFER_SIZE;
        pResult->IOPortGuestCommand = VBoxCommonFromDeviceExt(pExt)->guestCtx.port;

        pStatus->Information = sizeof(QUERYHGSMIRESULT);
    }
    else
    {
        pStatus->Status = ERROR_INVALID_FUNCTION;
        bRC=FALSE;
    }

    LOGF_LEAVE();
    return bRC;
}

BOOLEAN VBoxMPQueryRegistryFlags(PVBOXMP_DEVEXT pExt, ULONG *pulFlags, PSTATUS_BLOCK pStatus)
{
    BOOLEAN bRC = TRUE;
    LOGF_ENTER();

    VBOXMPCMNREGISTRY Registry;

    int rc = VBoxMPCmnRegInit(pExt, &Registry);
    VBOXMP_WARN_VPS_NOBP(rc);

    if (rc == NO_ERROR)
    {
        uint32_t u32Flags = 0;
        rc = VBoxMPCmnRegQueryDword(Registry, L"VBoxVideoFlags", &u32Flags);
        VBOXMP_WARN_VPS_NOBP(rc);
        if (rc != NO_ERROR)
        {
            u32Flags = 0;
        }

        LOG(("Registry flags 0x%08X", u32Flags));
        *pulFlags = u32Flags;
        pStatus->Information = sizeof(ULONG);
    }

    rc = VBoxMPCmnRegFini(Registry);
    VBOXMP_WARN_VPS_NOBP(rc);

    LOGF_LEAVE();
    return bRC;
}

/* Called to provide us GDI handle for our device, which we should use later for GDI calls */
VOID APIENTRY VBoxDispDrvCompletePDEV(DHPDEV dhpdev, HDEV hdev)
{
    LOGF_ENTER();

    ((PVBOXDISPDEV)dhpdev)->hDevGDI = hdev;

    LOGF_LEAVE();
}

/* Free all resources allocated in DrvEnableDriver */
VOID APIENTRY VBoxDispDrvDisableDriver()
{
    LOGF_ENTER();

    /* Intentionally left blank */

    LOGF_LEAVE();
    return;
}

DWORD APIENTRY VBoxDispDDAddAttachedSurface(PDD_ADDATTACHEDSURFACEDATA lpAddAttachedSurface)
{
    LOGF_ENTER();

    lpAddAttachedSurface->ddRVal = DD_OK;

    LOGF_LEAVE();
    return DDHAL_DRIVER_HANDLED;
}

/* Called for IOCTL_VIDEO_UNSHARE_VIDEO_MEMORY.
 * Unmaps framebuffer previously mapped with IOCTL_VIDEO_SHARE_VIDEO_MEMORY.
 */
BOOLEAN VBoxMPUnshareVideoMemory(PVBOXMP_DEVEXT pExt, PVIDEO_SHARE_MEMORY pMem, PSTATUS_BLOCK pStatus)
{
    LOGF_ENTER();

    pStatus->Status = VideoPortUnmapMemory(pExt, pMem->RequestedVirtualAddress, pMem->ProcessHandle);

    LOGF_LEAVE();
    return TRUE;
}

/* Called for IOCTL_VIDEO_UNMAP_VIDEO_MEMORY.
 * Unmaps previously mapped FrameBuffer and video RAM from caller's virtual adress space.
 */
BOOLEAN VBoxMPUnmapVideoMemory(PVBOXMP_DEVEXT pExt, PVIDEO_MEMORY VideoMemory, PSTATUS_BLOCK pStatus)
{
    LOGF_ENTER();

    HGSMIAreaClear(&pExt->areaDisplay);
    pStatus->Status = VideoPortUnmapMemory(pExt, VideoMemory->RequestedVirtualAddress, NULL);

    LOGF_LEAVE();
    return TRUE;
}

/* Called to free resources allocated for device in VBoxDispDrvEnablePDEV */
VOID APIENTRY VBoxDispDrvDisablePDEV(DHPDEV dhpdev)
{
    LOGF_ENTER();

    VBoxDispDestroyPalette((PVBOXDISPDEV) dhpdev);

    EngFreeMem(dhpdev);

    LOGF_LEAVE();
}

DWORD APIENTRY VBoxDispDDSetOverlayPosition(PDD_SETOVERLAYPOSITIONDATA lpSetOverlayPosition)
{
    PVBOXDISPDEV pDev = (PVBOXDISPDEV) lpSetOverlayPosition->lpDD->dhpdev;
    DD_SURFACE_LOCAL *pSrcSurf = lpSetOverlayPosition->lpDDSrcSurface;
    DD_SURFACE_LOCAL *pDstSurf = lpSetOverlayPosition->lpDDDestSurface;
    PVBOXVHWASURFDESC pSrcDesc = (PVBOXVHWASURFDESC) pSrcSurf->lpGbl->dwReserved1;
    PVBOXVHWASURFDESC pDstDesc = (PVBOXVHWASURFDESC) pDstSurf->lpGbl->dwReserved1;

    LOGF_ENTER();

    if (pSrcDesc && pDstDesc)
    {
        if (!pSrcDesc->bVisible)
        {
            WARN(("!pSrcDesc->bVisible"));
            lpSetOverlayPosition->ddRVal = DDERR_GENERIC;
            return DDHAL_DRIVER_HANDLED;
        }

        VBOXVHWACMD *pCmd;

        pCmd = VBoxDispVHWACommandCreate(pDev, VBOXVHWACMD_TYPE_SURF_OVERLAY_SETPOSITION, sizeof(VBOXVHWACMD_SURF_OVERLAY_SETPOSITION));
        if (pCmd)
        {
            VBOXVHWACMD_SURF_OVERLAY_SETPOSITION *pBody = VBOXVHWACMD_BODY(pCmd, VBOXVHWACMD_SURF_OVERLAY_SETPOSITION);
            memset(pBody, 0, sizeof(VBOXVHWACMD_SURF_OVERLAY_SETPOSITION));

            pBody->u.in.offSrcSurface = VBoxDispVHWAVramOffsetFromPDEV(pDev, pSrcSurf->lpGbl->fpVidMem);
            pBody->u.in.offDstSurface = VBoxDispVHWAVramOffsetFromPDEV(pDev, pDstSurf->lpGbl->fpVidMem);

            pBody->u.in.hSrcSurf = pSrcDesc->hHostHandle;
            pBody->u.in.hDstSurf = pDstDesc->hHostHandle;

            pBody->u.in.xPos = lpSetOverlayPosition->lXPos;
            pBody->u.in.yPos = lpSetOverlayPosition->lYPos;

            VBoxDispVHWACommandSubmitAsynchAndComplete(pDev, pCmd);

            lpSetOverlayPosition->ddRVal = DD_OK;
        }
        else
        {
            WARN(("VBoxDispVHWACommandCreate failed!"));
            lpSetOverlayPosition->ddRVal = DDERR_GENERIC;
        }
    }
    else
    {
        WARN(("!(pSrcDesc && pDstDesc)"));
        lpSetOverlayPosition->ddRVal = DDERR_GENERIC;
    }

    LOGF_LEAVE();
    return DDHAL_DRIVER_HANDLED;
}

/* Called to check if our hardware supports given power state. */
static VP_STATUS
VBoxDrvGetPowerState(PVOID HwDeviceExtension, ULONG HwId, PVIDEO_POWER_MANAGEMENT VideoPowerControl)
{
    PAGED_CODE();
    LOGF_ENTER();

    /*Not implemented*/

    LOGF_LEAVE();
    return NO_ERROR;
}

NTSTATUS VBoxIrpPower(IN PDEVICE_OBJECT DeviceObject, IN PIRP Irp)
{
    PVBOXMOUSE_DEVEXT pDevExt;
    PAGED_CODE();
    LOGF_ENTER();
    pDevExt = (PVBOXMOUSE_DEVEXT) DeviceObject->DeviceExtension;
    PoStartNextPowerIrp(Irp);
    IoSkipCurrentIrpStackLocation(Irp);
    LOGF_LEAVE();
    return PoCallDriver(pDevExt->pdoParent, Irp);
}