From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.orcon.net.nz (unknown [219.88.242.52]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 243361A00C1 for ; Sat, 6 Sep 2014 06:41:45 +1000 (EST) Date: Sat, 6 Sep 2014 08:39:51 +1200 From: Michael Cree To: Peter Hurley Subject: Re: bit fields && data tearing Message-ID: <20140905203951.GA4053@omega> References: <1409824374.4246.62.camel@pasglop> <5408E458.3@zytor.com> <54090AF4.7060406@hurleysoftware.com> <54091B30.2090509@zytor.com> <20140905081648.GB5281@omega> <20140905180950.GU5001@linux.vnet.ibm.com> <540A05F7.1070202@hurleysoftware.com> <20140905190506.GV5001@linux.vnet.ibm.com> <8CA974F497CA064FA9926E10ABCC061F05F97E7B77@MAILSJ4.global.cadence.com> <540A19B8.4010907@hurleysoftware.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <540A19B8.4010907@hurleysoftware.com> Cc: Jakub Jelinek , "linux-arch@vger.kernel.org" , Tony Luck , David Laight , "linux-alpha@vger.kernel.org" , Oleg Nesterov , "linux-kernel@vger.kernel.org" , Marc Gauthier , Paul Mackerras , "H. Peter Anvin" , "linux-ia64@vger.kernel.org" , "paulmck@linux.vnet.ibm.com" , "linuxppc-dev@lists.ozlabs.org" , Miroslav Franc , Richard Henderson List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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. Cheers Michael.