From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 86F57C282C4 for ; Tue, 12 Feb 2019 18:44:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 591D12190B for ; Tue, 12 Feb 2019 18:44:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732019AbfBLSoA (ORCPT ); Tue, 12 Feb 2019 13:44:00 -0500 Received: from foss.arm.com ([217.140.101.70]:42070 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727303AbfBLSn7 (ORCPT ); Tue, 12 Feb 2019 13:43:59 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 55107A78; Tue, 12 Feb 2019 10:43:59 -0800 (PST) Received: from fuggles.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 641D93F575; Tue, 12 Feb 2019 10:43:57 -0800 (PST) Date: Tue, 12 Feb 2019 18:43:54 +0000 From: Will Deacon To: "Paul E. McKenney" Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, Benjamin Herrenschmidt , Arnd Bergmann , Peter Zijlstra , Andrea Parri , Daniel Lustig , David Howells , Alan Stern , Linus Torvalds Subject: Re: [RFC PATCH] docs/memory-barriers.txt: Rewrite "KERNEL I/O BARRIER EFFECTS" section Message-ID: <20190212184354.GC20961@fuggles.cambridge.arm.com> References: <20190211172948.3322-1-will.deacon@arm.com> <20190211202218.GQ4240@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190211202218.GQ4240@linux.ibm.com> User-Agent: Mutt/1.11.1+86 (6f28e57d73f2) () Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 11, 2019 at 12:22:18PM -0800, Paul E. McKenney wrote: > On Mon, Feb 11, 2019 at 05:29:48PM +0000, Will Deacon wrote: > > The "KERNEL I/O BARRIER EFFECTS" section of memory-barriers.txt is vague, > > x86-centric, out-of-date, incomplete and demonstrably incorrect in places. > > This is largely because I/O ordering is a horrible can of worms, but also > > because the document has stagnated as our understanding has evolved. > > > > Attempt to address some of that, by rewriting the section based on > > recent(-ish) discussions with Arnd, BenH and others. Maybe one day we'll > > find a way to formalise this stuff, but for now let's at least try to > > make the English easier to understand. > > > > Cc: "Paul E. McKenney" > > Cc: Benjamin Herrenschmidt > > Cc: Arnd Bergmann > > Cc: Peter Zijlstra > > Cc: Andrea Parri > > Cc: Daniel Lustig > > Cc: David Howells > > Cc: Alan Stern > > cc: Linus Torvalds > > Signed-off-by: Will Deacon > > Hello, Will, > > The intent is to replace commit 3f305018dcf3 ("docs/memory-barriers.txt: > Enforce heavy ordering for port I/O accesses"), correct? Either way is > fine, just guessing based on the conflicts when applying this one. ;-) Yup, I decided to abandon the old patch: http://lkml.kernel.org/r/20190211153043.GC32385@fuggles.cambridge.arm.com Thanks, Will