On Thu, Dec 17, 2009 at 09:42:15AM -0800, Linus Torvalds wrote: > > I also think that the changes to bio_map_kernel() and bio_map_kern_endio() > are not just "fundamentally ugly", I think they are made worse by the fact > that it's not even done "right". You both flush the virtual caches before > the IO and invalidate after - when the real pattern should be that you > flush it before a write, and invalidate it after a read. > > And I really think that would be all much more properly done at the > _caller_ level, not by the BIO layer. > > You must have some locking and allocation etc logic at the caller anyway, > why doesn't _that_ level just do the flushing or invalidation? And then there are certain types of caches that need invalidation before _and_ after a DMA transaction as a workaround for a processor being grossly abused in a system that it should not be used in. Basically the issue is that falsly speculated stores may dirty caches. Ralf -- To unsubscribe from this list: send the line "unsubscribe linux-parisc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
