WdfDmaTransactionWdmGetTransferContext function (wdfdmatransaction.h)

[Applies to KMDF only]

The WdfDmaTransactionWdmGetTransferContext method retrieves the WDM transfer context that is associated with a DMA transaction.

Syntax

PVOID WdfDmaTransactionWdmGetTransferContext(
  [in] WDFDMATRANSACTION DmaTransaction
);

Parameters

[in] DmaTransaction

A handle to an initialized DMA transaction object from which to retrieve the transfer context.

Return value

A pointer to the DMA transfer context (PTRANSFER_CONTEXT) associated with the transaction.

Remarks

The DMA transfer context for a transaction is allocated when the driver creates the transaction.

WdfDmaTransactionWdmGetTransferContext must be used with a DMA enabler that uses DMA version 3. To select version 3, set the WdmDmaVersionOverride member of WDF_DMA_ENABLER_CONFIG to 3.

Your driver can use the DMA transfer context to call the following WDM DMA library routines directly:

• AllocateAdapterChannelEx
• CancelAdapterChannel
• CancelMappedTransfer
• GetScatterGatherListEx
• BuildScatterGatherListEx

Requirements

See also

WdfDmaTransactionCreate