On Tue, 1 Sep 2009, Russell King - ARM Linux wrote: > On Tue, Sep 01, 2009 at 03:43:48PM +0200, Laurent Pinchart wrote: > > I might be missing something obvious, but I fail to see how VIVT caches > > could work at all with multiple mappings. If a kernel-allocated buffer > > is DMA'ed to, we certainly want to invalidate all cache lines that store > > buffer data. As the cache doesn't care about physical addresses we thus > > need to invalidate all virtual mappings for the buffer. If the buffer is > > mmap'ed in userspace I don't see how that would be done. > > You need to ask MM gurus about that. I don't touch the Linux MM very > often so tend to keep forgetting how it works. However, it does work > for shared mappings of files on CPUs with VIVT caches. I believe arch/arm/mm/flush.c __flush_dcache_aliases() is what does it. Hugh -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
