On Tue, 2008-05-27 at 14:55 -0700, Linus Torvalds wrote: > > On Wed, 28 May 2008, Benjamin Herrenschmidt wrote: > > > > A problem with __raw_ though is that they -also- don't do byteswap, > > Well, that's why there is __readl() and __raw_readl(), no? As I replied to somebody else, __readl() is news to me :-) we dont' have those on powerpc. > Neither does ordering, and __raw_readl() doesn't do byte-swap. But I can add them :-) > Of course, I'm not going to guarantee every architecture even has all > those versions, nor am I going to guarantee they all work as advertised :) > > For x86, they have historially all been 100% identical. With the inline > asm patch I posted, the "__" version (whether "raw" or not) lack the > "memory" barrier, so they allow a *little* bit more re-ordering. > > (They won't be re-ordered wrt spinlocks etc, unless gcc starts reordering > volatile asm's against each other, which would be a bug). > > In practice, I doubt it matters. Whatever small compiler re-ordering it > might affect won't have any real performance impack one way or the other, > I think. I prefer explicit endian. Always. Thus I prefer introducing _be variants (we already have those on powerpc and iomap has it's own _be versions too) so we should probably generalize _be. Ben. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
