GetDmaAlignment

The GetDmaAlignment routine returns the alignment requirements of the DMA system.

ULONG
  GetDmaAlignment(
    IN PDMA_ADAPTER  DmaAdapter
    );

Parameters

DmaAdapter

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

Return Value

GetDmaAlignment returns the alignment requirements of the DMA system.

Headers

Declared in wdm.h and ntddk.h. Include wdm.h or ntddk.h.

Comments

GetDmaAlignment is not a system routine that can be called directly by name. This routine is callable only by pointer from the address returned in a DMA_OPERATIONS structure. Drivers obtain the address of this routine by calling IoGetDmaAdapter.

A driver can call this routine to determine alignment requirements for DMA buffers it allocates. The returned value should be used to set the AlignmentRequirement field in the device object. A driver may need to increase this value because of additional hardware device restrictions. For more information, see Initializing a Device Object.

Callers of GetDmaAlignment must be running at IRQL = PASSIVE_LEVEL.

See Also

IoGetDmaAdapter, DMA_OPERATIONS , DEVICE_OBJECT