PBUILD_MDL_FROM_SCATTER_GATHER_LIST callback function (wdm.h)

Article
02/22/2024

The BuildMdlFromScatterGatherList routine builds an MDL from a scatter/gather list allocated by the system.

This routine is reserved for system use.

Syntax

PBUILD_MDL_FROM_SCATTER_GATHER_LIST PbuildMdlFromScatterGatherList;

NTSTATUS PbuildMdlFromScatterGatherList(
  [in]  PDMA_ADAPTER DmaAdapter,
  [in]  PSCATTER_GATHER_LIST ScatterGather,
  [in]  PMDL OriginalMdl,
  [out] PMDL *TargetMdl
)
{...}

Parameters

[in] DmaAdapter

Pointer to the DMA_ADAPTER structure returned by IoGetDmaAdapter that represents the bus-master adapter or DMA controller.

[in] ScatterGather

Pointer to the SCATTER_GATHER_LIST structure passed to the driver's AdapterListControl routine.

[in] OriginalMdl

Pointer to the original MDL that the driver used to build the scatter/gather list.

[out] TargetMdl

Pointer to a variable the routine uses to return the MDL created to hold the buffer described by the scatter/gather list. The value returned can be the same as OriginalMdl.

Return value

BuildMdlFromScatterGatherList returns one of the following status codes:

Return code	Description
STATUS_SUCCESS	The operation succeeded.
STATUS_INVALID_PARAMETER	The OriginalMdl parameter is NULL.
STATUS_INSUFFICIENT_RESOURCES	There is not enough memory available to allocate a new MDL.
STATUS_NONE_MAPPED	The system has already created a new MDL for the memory locations in the scatter/gather list. (This only happens if the routine is called twice on the same scatter/gather list.)

Remarks

BuildMdlFromScatterGatherList is not a system routine that can be called directly by name. This routine can be called only by pointer from the address returned in a DMA_OPERATIONS structure. Drivers obtain the address of this routine by calling IoGetDmaAdapter with the Version member of the DeviceDescription parameter set to DEVICE_DESCRIPTION_VERSION2. If IoGetDmaAdapter returns NULL, the routine is not available on your platform.

When a driver creates a scatter/gather list to write to a device, the system can make a copy of the data to be written, and use that copy to perform the DMA operation. Use this routine to access the memory locations in the scatter/gather list, regardless of whether those locations are a copy.

Requirements

Requirement	Value
Minimum supported client	Available in Windows XP and later versions of Windows.
Target Platform	Desktop
Header	wdm.h (include Wdm.h)
IRQL	<= DISPATCH_LEVEL
DDI compliance rules	IrqlDispatch(wdm)