IDmaChannel::AllocateBuffer method (portcls.h)
The AllocateBuffer method allocates a common buffer that can be accessed by the port driver and DMA hardware.
Syntax
NTSTATUS AllocateBuffer(
ULONG BufferSize,
PPHYSICAL_ADDRESS PhysicalAddressConstraint
);
Parameters
BufferSize
Specifies the size in bytes of the buffer to be allocated.
PhysicalAddressConstraint
Specifies an optional constraint to place on the physical address of the buffer. If this parameter is non-NULL, only the bits that are set in the constraint address will vary from the beginning to the end of the buffer. For example, to request a buffer that does not cross a 64-kilobyte boundary, specify the physical address constraint 0x000000000000FFFF.
Return value
This method returns NTSTATUS. AllocateBuffer returns STATUS_SUCCESS if the call was successful. Otherwise, the method returns an appropriate error code.
Remarks
This method must be called only once following the creation of the DMA-channel object unless the previously allocated buffer is first freed by calling FreeBuffer.
Requirements
| Requirement | Value |
|---|---|
| Header | portcls.h |
| IRQL | PASSIVE_LEVEL |