PROTECT_WC_MEMORY callback function (video.h)

Article
02/22/2024

The VideoPortProtectWCMemory callback routine protects Write Combined (WC) video memory from being accessed by the CPU.

Syntax

PROTECT_WC_MEMORY ProtectWcMemory;

VP_STATUS ProtectWcMemory(
  [in] IN PVOID Context,
  [in] IN PVOID HwDeviceExtension
)
{...}

Parameters

[in] Context

Pointer to a caller-determined context parameter to be passed to the CallbackRoutine. It typically points to the VIDEO_PORT_CONFIG_INFO buffer.

[in] HwDeviceExtension

Pointer to the miniport driver's hardware device extension.

Return value

VideoPortProtectWCMemory returns NO_ERROR if it successfully protects Write Combined video memory; otherwise, it returns an error status of ERROR_INVALID_FUNCTION or ERROR_NOT_ENOUGH_MEMORY.

Remarks

After VideoPortProtectWCMemory is called, the CPU cannot write to Write Combined (WC) memory until the VideoPortRestoreWCMemory callback routine is called.

When WC memory protection is no longer required, the display miniport driver should call VideoPortRestoreWCMemory to restore CPU access to WC memory.

Requirements

Requirement	Value
Minimum supported client	Available in Windows 2000 and later versions of the Windows operating systems.
Target Platform	Desktop
Header	video.h (include Video.h)