On Jan 21, 2012, at 3:06 AM, David Laight wrote: > On Thu, Jan 19, 2012 at 10:59:01AM -0800, Matt Thomas wrote: >> >> For prefetchable regions (like framebuffers) mapped by bus_space_map, >> there is a need to able force the contents out of the cache back into >> memory (especially when the cache is a writeback cache). > > Don't some ethernet drivers already have to do this - for systems > where the cpu's cache isn't snooped by the dma accesses.
That's a different API (bus_dmamap_sync). > There is subtle difference as to whether would need an 'invalidate' > the cache line (with or without a writeback). Which is why i left invalidate out. Some x86 don't have it.