NdisFlushBuffer

VOID
NdisFlushBuffer(
IN PNDIS_BUFFER Buffer,
IN BOOLEAN WriteToDevice
);

NdisFlushBuffer flushes the memory region described by a given buffer descriptor from all processor caches.

Parameters

Buffer: Points to a buffer description mapping a buffer from which or into which data is transferred as a busmaster DMA operation.
WriteToDevice: Specifies TRUE if the NIC driver calls this function to flush a buffer before making a transfer from host memory to the NIC.
If the NIC driver specifies FALSE, it must ensure the buffer begins and ends on a cache-line boundary.

Comments

Drivers of busmaster DMA NICs call NdisFlushBuffer to maintain data integrity in shared memory. Flushing the buffer ensures coherency between the host memory cache and processor physical memory before a DMA transfer to or from the network interface card.

The driver flushes such a buffer when data that it shares with its NIC might be cached. For any transfer between host memory and a busmaster DMA NIC, the miniport must flush the buffer before the transfer starts. Such a driver also must ensure that host memory is not accessed until the transfer completes.

Callers of NdisFlushBuffer run at IRQL <= DISPATCH_LEVEL.