On Wed, Mar 28, 2018 at 10:57:11AM -0700, Tony Luck wrote: > On Wed, Mar 28, 2018 at 6:02 AM, Sinan Kaya <okaya@xxxxxxxxxxxxxx> wrote: > > +linux-ia64 > > Does IA64 follow this requirement? If not, is implementation planned? > > > > "no wmb() before writel()" > > > > Linus asked us to get rid of wmb() in front of writel() for UC memory. > > Just checking that we are not breaking anything for IA64. > > We should be OK on ia64, writel() uses a cast to: > > *(volatile unsigned int __force *) > > which the compiler takes as a request to use a "st4.rel" instruction > (meaning "store with release semantics"). So the value stored will > be visible to anything that follows. Just to nitpick, regular release semantics don't guarantee anything like that, but ia64 never actually got around to implementing proper release and it's a full barrier and thus what you say is true. -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
