Linus Torvalds <torvalds at osdl.org> wrote: > > Linus explained recently that wmb() on x86 does not order stores to > > system memory w.r.t. stores to stores to prefetchable I/O memory (at > > least that's what I think he said ;). On i386 and x86_64, do IN and OUT instructions imply MFENCE? It's not obvious from the x86_64 docs. David