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WdfDmaTransactionFreeResources method

[Applies to KMDF only]

The WdfDmaTransactionFreeResources method releases DMA resources that the driver previously allocated by calling WdfDmaTransactionAllocateResources.

Syntax


void WdfDmaTransactionFreeResources(
  [in]  WDFDMATRANSACTION DmaTransaction
);

Parameters

DmaTransaction [in]

A handle to the DMA transaction object that the driver provided in a previous call to WdfDmaTransactionAllocateResources.

Return value

This method does not return a value.

Remarks

WdfDmaTransactionFreeResources must be used with a DMA enabler that specifies a packet or system profile.

On operating systems earlier than Windows 8, WdfDmaTransactionFreeResources must be used with an enabler that specifies a single-packet DMA enabler. Starting with Windows 8, WdfDmaTransactionFreeResources can also be used with an enabler that specifies a system-mode DMA enabler.

When called with a scatter/gather DMA enabler, WdfDmaTransactionFreeResources causes a verifier bug check.

The driver's call to WdfDmaTransactionFreeResources may cause the framework to call EvtProgramDma or EvtReserveDma immediately.

For more information about system-mode DMA, see Supporting System-Mode DMA.

Requirements

Minimum KMDF version

1.11

Header

Wdfdmatransaction.h (include Wdf.h)

Library

Wdf01000.sys (see Framework Library Versioning.)

IRQL

<=DISPATCH_LEVEL

DDI compliance rules

DriverCreate

See also

WdfDmaTransactionAllocateResources

 

 

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