WDDM 适配器复位和资源的释放

通过获取的适配器信息将SupportNonVGA置为TRUE，表示支持使用DxgkDdiStopDeviceAndReleasePostDisplayOwnership函数重置显示设备并释放当前开机自检（POST）设备的所有权。

    InitialData.DxgkDdiStopDeviceAndReleasePostDisplayOwnership = BddDdiStopDeviceAndReleasePostDisplayOwnership;

函数原型为：

DXGKDDI_STOP_DEVICE_AND_RELEASE_POST_DISPLAY_OWNERSHIP DxgkddiStopDeviceAndReleasePostDisplayOwnership;

NTSTATUS DxgkddiStopDeviceAndReleasePostDisplayOwnership(
  PVOID MiniportDeviceContext,
  D3DDDI_VIDEO_PRESENT_TARGET_ID TargetId,
  PDXGK_DISPLAY_INFORMATION DisplayInfo
)

TargetId 表示设备ID.值为D3DDDI_VIDEO_PRESENT_TARGET_ID时表示连接到显示适配器的显示设置。
这里对目标设置黑屏处理，即将相应的内存填充为0即可。

NTSTATUS BASIC_DISPLAY_DRIVER::StopDeviceAndReleasePostDisplayOwnership(_In_  D3DDDI_VIDEO_PRESENT_TARGET_ID TargetId,
                                                                        _Out_ DXGK_DISPLAY_INFORMATION*      pDisplayInfo)
{
    PAGED_CODE();

    BDD_ASSERT(TargetId < MAX_CHILDREN);


    D3DDDI_VIDEO_PRESENT_SOURCE_ID SourceId = FindSourceForTarget(TargetId, TRUE);

    // In case BDD is the next driver to run, the monitor should not be off, since
    // this could cause the BIOS to hang when the EDID is retrieved on Start.
    if (m_MonitorPowerState > PowerDeviceD0)
    {
        SetPowerState(TargetId, PowerDeviceD0, PowerActionNone);
    }

    // The driver has to black out the display and ensure it is visible when releasing ownership
    BlackOutScreen(SourceId);

    *pDisplayInfo = m_CurrentModes[SourceId].DispInfo;

    return StopDevice();
}

VOID BASIC_DISPLAY_DRIVER::BlackOutScreen(D3DDDI_VIDEO_PRESENT_SOURCE_ID SourceId)
{
    PAGED_CODE();


    UINT ScreenHeight = m_CurrentModes[SourceId].DispInfo.Height;
    UINT ScreenPitch = m_CurrentModes[SourceId].DispInfo.Pitch;

    PHYSICAL_ADDRESS NewPhysAddrStart = m_CurrentModes[SourceId].DispInfo.PhysicAddress;
    PHYSICAL_ADDRESS NewPhysAddrEnd;
    NewPhysAddrEnd.QuadPart = NewPhysAddrStart.QuadPart + (ScreenHeight * ScreenPitch);

    if (m_CurrentModes[SourceId].Flags.FrameBufferIsActive)
    {
        BYTE* MappedAddr = reinterpret_cast<BYTE*>(m_CurrentModes[SourceId].FrameBuffer.Ptr);

        // Zero any memory at the start that hasn't been zeroed recently
        if (NewPhysAddrStart.QuadPart < m_CurrentModes[SourceId].ZeroedOutStart.QuadPart)
        {
            if (NewPhysAddrEnd.QuadPart < m_CurrentModes[SourceId].ZeroedOutStart.QuadPart)
            {
                // No overlap
                RtlZeroMemory(MappedAddr, ScreenHeight * ScreenPitch);
            }
            else
            {
                RtlZeroMemory(MappedAddr, (UINT)(m_CurrentModes[SourceId].ZeroedOutStart.QuadPart - NewPhysAddrStart.QuadPart));
            }
        }

        // Zero any memory at the end that hasn't been zeroed recently
        if (NewPhysAddrEnd.QuadPart > m_CurrentModes[SourceId].ZeroedOutEnd.QuadPart)
        {
            if (NewPhysAddrStart.QuadPart > m_CurrentModes[SourceId].ZeroedOutEnd.QuadPart)
            {
                // No overlap
                // NOTE: When actual pixels were the most recent thing drawn, ZeroedOutStart & ZeroedOutEnd will both be 0
                // and this is the path that will be used to black out the current screen.
                RtlZeroMemory(MappedAddr, ScreenHeight * ScreenPitch);
            }
            else
            {
                RtlZeroMemory(MappedAddr, (UINT)(NewPhysAddrEnd.QuadPart - m_CurrentModes[SourceId].ZeroedOutEnd.QuadPart));
            }
        }
    }

    m_CurrentModes[SourceId].ZeroedOutStart.QuadPart = NewPhysAddrStart.QuadPart;
    m_CurrentModes[SourceId].ZeroedOutEnd.QuadPart = NewPhysAddrEnd.QuadPart;

}

ScreenPitch是一行的字节数。