> On Thu, 2008-08-21 at 12:57 +0200, Stefan Richter wrote:
> > Peter Zijlstra wrote:
> > > On Wed, 2008-08-20 at 20:50 -0600,
jmerkey@wolfmountaingroup.com wrote:
> > >
> > >> volatiles left in the code due to the previously stated
> > >> (and still present) severe breakage of the GNU compiler with SMP
> > >> shared data. most of the barrier() functions are just plain broken
> > >> and do not result in proper compiler behavior in this tree.
> > >
> > > Can you provide explicit detail?
> > >
> > > By using barrier() the compiler should clobber all its memory and
> > > registers therefore forcing a write/reload of the variable.
> >
> > I hope Jeff didn't try mere barrier()s only. smp_wmb() and smp_rmb()
> > are the more relevant barrier variants for mdb, from what I remember
> > when I last looked at it.
>
> Sure, but volatile isn't a replacement for memory barriers.
