Hi Paul, On Fri, Feb 07, 2014 at 04:50:28PM +0000, Paul E. McKenney wrote: > On Fri, Feb 07, 2014 at 08:44:05AM +0100, Peter Zijlstra wrote: > > On Thu, Feb 06, 2014 at 08:20:51PM -0800, Paul E. McKenney wrote: > > > Hopefully some discussion of out-of-thin-air values as well. > > > > Yes, absolutely shoot store speculation in the head already. Then drive > > a wooden stake through its hart. > > > > C11/C++11 should not be allowed to claim itself a memory model until that > > is sorted. > > There actually is a proposal being put forward, but it might not make ARM > and Power people happy because it involves adding a compare, a branch, > and an ISB/isync after every relaxed load... Me, I agree with you, > much preferring the no-store-speculation approach. Can you elaborate a bit on this please? We don't permit speculative stores in the ARM architecture, so it seems counter-intuitive that GCC needs to emit any additional instructions to prevent that from happening. Stores can, of course, be observed out-of-order but that's a lot more reasonable :) Will -- 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
