From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755017Ab3KKRiZ (ORCPT ); Mon, 11 Nov 2013 12:38:25 -0500 Received: from e38.co.us.ibm.com ([32.97.110.159]:56539 "EHLO e38.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753890Ab3KKRiR (ORCPT ); Mon, 11 Nov 2013 12:38:17 -0500 Date: Mon, 11 Nov 2013 09:13:08 -0800 From: "Paul E. McKenney" To: tony.luck@intel.com Cc: peterz@infradead.org, linux-kernel@vger.kernel.org Subject: Does Itanium permit speculative stores? Message-ID: <20131111171307.GA27002@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13111117-1344-0000-0000-0000032B0865 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Tony, Does Itanium permit speculative stores? For example, on Itanium what are the permitted outcomes of the following litmus test, where both x and y are initially zero? CPU 0 CPU 1 r1 = ACCESS_ONCE(x); r2 = ACCESS_ONCE(y); if (r1) if (r2) ACCESS_ONCE(y) = 1; ACCESS_ONCE(x) = 1; In particular, is the outcome (r1 == 1 && r2 == 1) possible on Itanium given this litmus test? Thanx, Paul