PAGP_COMMIT_PHYSICAL callback function (videoagp.h)

Article
10/21/2021

The AgpCommitPhysical function maps system (physical) memory to the specified range of AGP-decodable physical addresses.

Syntax

PAGP_COMMIT_PHYSICAL PagpCommitPhysical;

BOOLEAN PagpCommitPhysical(
  [in] IN PVOID HwDeviceExtension,
  [in] IN PVOID PhysicalReserveContext,
  [in] IN ULONG Pages,
  [in] IN ULONG Offset
)
{...}

Parameters

[in] HwDeviceExtension

Pointer to the device extension of the miniport driver.

[in] PhysicalReserveContext

Identifies a reserved physical address range. The context handle is obtained from AgpReservePhysical.

[in] Pages

Specifies the number of pages of system memory to commit.

[in] Offset

Specifies the page offset at which to commit the pages. The offset is applied to the reserved physical address range associated with PhysicalReserveContext.

Return value

AgpCommitPhysical returns TRUE if the mapping was successful, and FALSE otherwise.

Remarks

A video miniport driver must first reserve physical addresses by calling AgpReservePhysical before it calls this function.

Do not call AgpCommitPhysical to commit addresses that have already been committed. If the range of pages that is specified by PhysicalReserveContext, Pages, and Offset includes any pages that were previously committed, AgpCommitPhysical might fail.

Video miniport drivers that run on Microsoft Windows 2000 should always reserve and commit a physical range whose size is a multiple of 64 kilobytes. Reserving or committing a physical range that is not a multiple of 64 kilobytes can result in AgpReserveVirtual or AgpCommitVirtual returning an invalid virtual address.

On Windows XP and later, AgpCommitPhysical automatically expands the committed range so that it is a multiple of 64 kilobytes.

When a video miniport driver calls AgpCommitPhysical, a portion of the physical address range identified by PhysicalReserveContext is mapped to locked pages of physical memory. The mapped portion begins Offset pages into the range identified by PhysicalReserveContext. The video miniport driver can access committed physical memory as if it were contiguous.

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