On Fri, Sep 05, 2014 at 05:12:28PM -0400, Peter Hurley wrote: > On 09/05/2014 04:39 PM, Michael Cree wrote: > > On Fri, Sep 05, 2014 at 04:14:48PM -0400, Peter Hurley wrote: > >> Second, in the body of the document: > >> > >> "The Linux kernel no longer supports pre-EV56 Alpha CPUs, because these > >> older CPUs _do not provide_ atomic one-byte and two-byte loads and stores." > > > > Let's be clear here, the pre-EV56 Alpha CPUs do provide an atomic > > one-byte and two-byte load and store; it's just that one must use > > locked load and store sequences to achieve atomicity. The point, > > I think, is that the pre-EV56 Alpha CPUs provide non-atomic one-byte > > and two-byte load and stores as the norm, and that is the problem. > > I'm all for an Alpha expert to jump in here and meet the criteria; > which is that byte stores cannot corrupt adjacent storage (nor can > aligned short stores). > > To my mind, a quick look at Documentation/circular-buffers.txt will > pretty much convince anyone that trying to differentiate by execution > context is undoable. > > If someone wants to make Alphas do cmpxchg loops for every byte store, > then ok. Or any other solution that doesn't require subsystem code > changes. I am not suggesting that anyone do that work. I'm certainly not going to do it. All I was pointing out is that the claim that "_do not provide_" made above with emphasis is, strictly interpreted, not true, thus should not be committed to the documentation without further clarification. Cheers Michael. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
