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? Neither does ordering, and __raw_readl() doesn't do byte-swap. 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. Linus -- 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
