On Wed, 2010-03-03 at 11:10 +0530, James Bottomley wrote: > On Wed, 2010-03-03 at 16:10 +1100, Benjamin Herrenschmidt wrote: > > On Wed, 2010-03-03 at 12:47 +0900, FUJITA Tomonori wrote: > > > The ways to improve the approach (introducing PG_arch_2 or marking a > > > page clean on dma_unmap_* with DMA_FROM_DEVICE like ia64 does) is up > > > to architectures. > > > > How does the above work ? IE, the dma unmap will flush the D side but > > not the I side ... or is the ia64 flush primitive magic enough to do > > both ? > > The point is that in a well regulated system, the I cache shouldn't need > extra flushing in the kernel. We should only be faulting in R-X pages. > If we're operating on RWX pages (i.e. self modifying code), it's the job > of userspace to keep I/D coherency. > > So the only case the kernel needs to worry about is the R-X fault case > for executable text code. Still, you do need to flush I when a page cache page is recycled. Cheers, Ben. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
