On Mon, Jun 02, 2014 at 01:33:34PM -0400, Waiman Long wrote: > On 06/02/2014 12:30 PM, Peter Zijlstra wrote: > >On Mon, Jun 02, 2014 at 06:25:25PM +0200, Peter Zijlstra wrote: > >>I'm almost inclined to just exclude parisc from using opt spinning. > >> > >>That said, this patch still doesn't address the far more interesting > >>problem of actually finding these issues for these few weird archs. > >So why do these archs provide xchg() and cmpxchg() at all? Wouldn't it > >be much simpler if archs that cannot sanely do this, not provide these > >primitives at all? > > I believe xchg() and cmpxchg() are used in quite a number of places within > the generic kernel code. So kernel compilation will fail if those APIs > aren't provided by an architecture. Yep.. so this is going to be painful for a while. But given their (parisc, sparc32, metag-lock1) constraints, who knows how many of those uses are actually broken. So the question is, do you prefer subtly broken code or hard compile fails? Me, I go for the compile fail. In any case, this all goes towards what hpa said, what are the minimal requirements we have for running Linux. -- To unsubscribe from this list: send the line "unsubscribe linux-parisc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
