From patchwork Tue Jan 26 10:32:00 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Zijlstra X-Patchwork-Id: 8119991 Return-Path: X-Original-To: patchwork-xen-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 85C119F859 for ; Tue, 26 Jan 2016 10:35:20 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id AF0F820259 for ; Tue, 26 Jan 2016 10:35:19 +0000 (UTC) Received: from lists.xen.org (lists.xenproject.org [50.57.142.19]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9C08620145 for ; Tue, 26 Jan 2016 10:35:14 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=lists.xen.org) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1aO0vF-0005Ye-7a; Tue, 26 Jan 2016 10:32:29 +0000 Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1aO0vE-0005YN-24 for xen-devel@lists.xenproject.org; Tue, 26 Jan 2016 10:32:28 +0000 Received: from [85.158.137.68] by server-1.bemta-3.messagelabs.com id FA/E4-02745-B3B47A65; Tue, 26 Jan 2016 10:32:27 +0000 X-Env-Sender: peterz@infradead.org X-Msg-Ref: server-3.tower-31.messagelabs.com!1453804345!18155170!1 X-Originating-IP: [198.137.202.9] X-SpamReason: No, hits=0.0 required=7.0 tests= X-StarScan-Received: X-StarScan-Version: 7.35.1; banners=-,-,- X-VirusChecked: Checked Received: (qmail 52310 invoked from network); 26 Jan 2016 10:32:26 -0000 Received: from bombadil.infradead.org (HELO bombadil.infradead.org) (198.137.202.9) by server-3.tower-31.messagelabs.com with AES128-GCM-SHA256 encrypted SMTP; 26 Jan 2016 10:32:26 -0000 Received: from j217066.upc-j.chello.nl ([24.132.217.66] helo=twins) by bombadil.infradead.org with esmtpsa (Exim 4.80.1 #2 (Red Hat Linux)) id 1aO0uo-0000LD-IL; Tue, 26 Jan 2016 10:32:02 +0000 Received: by twins (Postfix, from userid 1000) id 16BA51257A0D8; Tue, 26 Jan 2016 11:32:00 +0100 (CET) Date: Tue, 26 Jan 2016 11:32:00 +0100 From: Peter Zijlstra To: "Paul E. McKenney" Message-ID: <20160126103200.GI6375@twins.programming.kicks-ass.net> References: <20160113104516.GE25458@arm.com> <56969F4B.7070001@imgtec.com> <20160113204844.GV6357@twins.programming.kicks-ass.net> <5696BA6E.4070508@imgtec.com> <20160114120445.GB15828@arm.com> <56980145.5030901@imgtec.com> <20160114204827.GE3818@linux.vnet.ibm.com> <56981212.7050301@imgtec.com> <20160114222046.GH3818@linux.vnet.ibm.com> <20160126102402.GE6357@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20160126102402.GE6357@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2012-12-30) Cc: linux-mips@linux-mips.org, linux-ia64@vger.kernel.org, "Michael S. Tsirkin" , Will Deacon , virtualization@lists.linux-foundation.org, "H. Peter Anvin" , sparclinux@vger.kernel.org, Ingo Molnar , linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, Russell King - ARM Linux , user-mode-linux-devel@lists.sourceforge.net, linux-sh@vger.kernel.org, Michael Ellerman , x86@kernel.org, xen-devel@lists.xenproject.org, Ingo Molnar , linux-xtensa@linux-xtensa.org, james.hogan@imgtec.com, Arnd Bergmann , Stefano Stabellini , adi-buildroot-devel@lists.sourceforge.net, Leonid Yegoshin , ddaney.cavm@gmail.com, Thomas Gleixner , linux-metag@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Andrew Cooper , linux-kernel@vger.kernel.org, Ralf Baechle , Joe Perches , linuxppc-dev@lists.ozlabs.org, David Miller Subject: Re: [Xen-devel] [v3,11/41] mips: reuse asm-generic/barrier.h X-BeenThere: xen-devel@lists.xen.org X-Mailman-Version: 2.1.13 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On Tue, Jan 26, 2016 at 11:24:02AM +0100, Peter Zijlstra wrote: > Yeah, this goes under the header: memory-barriers.txt is _NOT_ a > specification (I seem to keep repeating this). Do we want this ? --- Documentation/memory-barriers.txt | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt index a61be39c7b51..433326ebdc26 100644 --- a/Documentation/memory-barriers.txt +++ b/Documentation/memory-barriers.txt @@ -1,3 +1,4 @@ + ============================ LINUX KERNEL MEMORY BARRIERS ============================ @@ -5,6 +6,22 @@ By: David Howells Paul E. McKenney +========== +DISCLAIMER +========== + +This document is not a specification; it is intentionally (for the sake of +brevity) and unintentionally (due to being human) incomplete. This document is +meant as a guide to using the various memory barriers provided by Linux, but +in case of any doubt (and there are many) please ask. + +I repeat, this document is not a specification of what Linux expects from +hardware. + +===== +INDEX +===== + Contents: (*) Abstract memory access model.