Re: cmpxchg is not available to generic code

[Nick Piggin]

Dave Airlie wrote:
> On 7/19/07, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> > On Thu, 19 Jul 2007 18:15:03 +1000 "Dave Airlie" <airlied@xxxxxxxxx> 
> > wrote:
> >
> > > Maybe we could add CONFIG_HAVE_CMPXCHG and let DRM depend on it..
> >
> > That would certainly be better than adding a sprinkle of architectures
> > in DRM Kconfig dependencies.
> >
> > I don't know how important DRM is on ARM.  Zero?
>
> I'd guess zero I suppose if you wanted you could hook up a PCI
> graphics card on ARM, but if you do that I think you could implement
> cmpxchg :-)

ARM does the locked load / store conditional thing which is at least as
strong as cmpxchg, so I imagine it could implement this API in kernel
and userspace quite easily if needed.

--
SUSE Labs, Novell Inc.
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