Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754067AbbEVGnw (ORCPT ); Fri, 22 May 2015 02:43:52 -0400 Received: from mail-wg0-f49.google.com ([74.125.82.49]:32909 "EHLO mail-wg0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750715AbbEVGnt (ORCPT ); Fri, 22 May 2015 02:43:49 -0400 Date: Fri, 22 May 2015 08:43:44 +0200 From: Ingo Molnar To: Linus Torvalds Cc: Paul McKenney , Will Deacon , Linux Kernel Mailing List , "c++std-parallel@accu.org" , "linux-arch@vger.kernel.org" , "gcc@gcc.gnu.org" , p796231 , "mark.batty@cl.cam.ac.uk" , Peter Zijlstra , Ramana Radhakrishnan , David Howells , Andrew Morton , "michaelw@ca.ibm.com" Subject: Re: Compilers and RCU readers: Once more unto the breach! Message-ID: <20150522064344.GA17518@gmail.com> References: <20150520024148.GD6776@linux.vnet.ibm.com> <20150520114745.GC11498@arm.com> <20150520121522.GH6776@linux.vnet.ibm.com> <20150520154617.GE11498@arm.com> <20150520181606.GT6776@linux.vnet.ibm.com> <20150521192422.GC19204@arm.com> <20150521200212.GW6776@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1249 Lines: 32 * Linus Torvalds wrote: > (a) the "official" rules are completely pointless, and make sense > only because the standard is written for some random "abstract > machine" that doesn't actually exist. Presuming the intent of the abstract machine specification is to avoid being seen as biased towards any specific machine (politics), maybe write this as: (a) the "official" rules are written for a somewhat weird and complex "union of all known and theoretically possible CPU architectures that exist or which might exist in the future", which machine does not actually exist in practice, but which allows a single abstract set of rules to apply to all machines. These rules are complex, but if applied to a specific machine they become considerably simpler. Here's a few examples: ... ? (Assuming it's a goal of this standard to be human parseable to more than a few dozen people on the planet.) Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/