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PAGP_FREE_VIRTUAL callback function (videoagp.h)

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The AgpFreeVirtual function frees virtual memory committed by a previous call to AgpCommitVirtual.

Syntax

PAGP_FREE_VIRTUAL PagpFreeVirtual;

void PagpFreeVirtual(
  [in] IN PVOID HwDeviceExtension,
  [in] IN PVOID VirtualReserveContext,
  [in] IN ULONG Pages,
  [in] IN ULONG Offset
)
{...}

Parameters

[in] HwDeviceExtension

Pointer to the miniport driver's device extension.

[in] VirtualReserveContext

Identifies a reserved virtual address range. This context handle was obtained from AgpReserveVirtual.

[in] Pages

Specifies the number of pages of virtual memory that the video port driver should unmap.

[in] Offset

Specifies the page offset into the reserved virtual address range identified by VirtualReserveContext that indicates the actual base address at which to unmap virtual memory.

Return value

None

Remarks

When a miniport driver calls AgpFreeVirtual, Pages pages of virtual addresses are unmapped. The unmapped range begins Offset pages into the range associated with VirtualReserveContext. The miniport driver must specify that the exact offset and number of pages be freed as were committed in a prior call to AgpCommitVirtual.

A call to AgpFreeVirtual must be paired with a previous call to AgpCommitVirtual, and that call to AgpCommitVirtual must be preceded by a successful call to AgpReserveVirtual. If AgpReserveVirtual fails (returns NULL), you must not call AgpCommitVirtual or AgpFreeVirtual.

Requirements

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

See also

AgpCommitVirtual