From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Tue, 20 Nov 2007 11:55:01 +1100
Good question.
Some drivers are problematic (or were) because they put
DMA descriptor chaining information at the head of the
buffer, but those have been fixed either to use alternate
descriptor ring facilities or make the proper DMA sync
calls.
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