On Wed, May 21, 2008 at 11:27:03AM -0400, Benjamin Herrenschmidt wrote:
>
> On Wed, 2008-05-21 at 16:10 +0200, Nick Piggin wrote:
> > Hi,
> >
> > I'm sure I've sent these patches before, but I can't remember why they
> > weren't merged. They still seem obviously correct to me.
>
> We should already do all that's needed in our IO accessors no ?
More than one device driver does raw/relaxed io accessors and expects the
*mb functions to order them.
>
> > --
> >
> > lwsync is explicitly defined not to have any effect on the ordering of
> > accesses to device memory, so it cannot be used for rmb(). sync appears
> > to be the only barrier which fits the bill.
> >
> > Signed-off-by: Nick Piggin <[EMAIL PROTECTED]>
> > ---
> > Index: linux-2.6/include/asm-powerpc/system.h
> > ===================================================================
> > --- linux-2.6.orig/include/asm-powerpc/system.h
> > +++ linux-2.6/include/asm-powerpc/system.h
> > @@ -34,7 +34,7 @@
> > * SMP since it is only used to order updates to system memory.
> > */
> > #define mb() __asm__ __volatile__ ("sync" : : : "memory")
> > -#define rmb() __asm__ __volatile__ (__stringify(LWSYNC) : : : "memory")
> > +#define rmb() __asm__ __volatile__ ("sync" : : : "memory")
> > #define wmb() __asm__ __volatile__ ("sync" : : : "memory")
> > #define read_barrier_depends() do { } while(0)
> >
> > _______________________________________________
> > Linuxppc-dev mailing list
> > Linuxppc-dev@ozlabs.org
> > https://ozlabs.org/mailman/listinfo/linuxppc-dev
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