From: "Michael S. Tsirkin" <[email protected]> On x86, we *do* still use the non-nop rmb()/wmb() for IO barriers, but even that is generally questionable.
Leave them around for historical reasons, unless somebody can point to a case where they care about the performance. Tweak the comment so people don't think they are strictly required in all cases. Signed-off-by: Michael S. Tsirkin <[email protected]> Cc: Andrey Konovalov <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Arnd Bergmann <[email protected]> Cc: Davidlohr Bueso <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: "Paul E. McKenney" <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: virtualization <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Borislav Petkov <[email protected]> --- arch/x86/include/asm/barrier.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h index d2aa66a3a4b5..4f95b2affd88 100644 --- a/arch/x86/include/asm/barrier.h +++ b/arch/x86/include/asm/barrier.h @@ -6,8 +6,8 @@ /* * Force strict CPU ordering. - * And yes, this is required on UP too when we're talking - * to devices. + * + * And yes, this might be required on UP too when we're talking to devices. */ #ifdef CONFIG_X86_32 -- 2.3.5
