> On Fri, May 01, 2009 at 05:37:18PM -0400, John David Anglin wrote:
> > On Fri, 01 May 2009, Carlos O'Donell wrote:
> >
> > > Historical note...
> > >
> > > We clobber all of memory in userspace, like this:
> > > ~~~
> > > #define __ldcw(a) \
> > > ({ \
> > > unsigned int __ret; \
> > > __asm__ __volatile__("ldcw 0(%1),%0" \
> > > : "=r" (__ret) : "r" (a) : "memory"); \
> > > __ret; \
> > > })
> > > ~~~
> > > I wonder if I should change that to match the kernel?
> >
> > The above is perfectly safe. I believe the kernel provides a memory
> > barrier when necessary. There's a discussion somewhere in the mail
> > archives.
> >
>
> I, er, don't think we do, not for the spinlock primitives at least, as
> far as I can tell...
Ok, I'm going to see if the "memory" clobber improves life.
Dave
--
J. David Anglin dave.anglin@xxxxxxxxxxxxxx
National Research Council of Canada (613) 990-0752 (FAX: 952-6602)
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