Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937697AbXHPBVT (ORCPT ); Wed, 15 Aug 2007 21:21:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758529AbXHPBVG (ORCPT ); Wed, 15 Aug 2007 21:21:06 -0400 Received: from smtp108.mail.mud.yahoo.com ([209.191.85.218]:40843 "HELO smtp108.mail.mud.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1758441AbXHPBVE (ORCPT ); Wed, 15 Aug 2007 21:21:04 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:X-YMail-OSG:Message-ID:Date:From:User-Agent:X-Accept-Language:MIME-Version:To:CC:Subject:References:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=L5CrhetbDRBs1wq6FCTLPz9hLFIDupP15Stk0afimJEl0mHePlbcoyutbZ8sm71xSby2Ek7AEKcZD3QqkT+P5aK5oDhUqOYypKd6VUUM2odJD8EMSjeifbSDqDQULXwTxt95rSr/E5N2aXMbn1r0F5N5pOJxMvFOIYUE4Cdqb9c= ; X-YMail-OSG: wAYfujkVM1lUVkvZEunvK_WLE9nPdVRg47k4ylORgt_oz2OtYFWjo8qGQYv.MZYYmghjWbrLVA-- Message-ID: <46C3A675.7050108@yahoo.com.au> Date: Thu, 16 Aug 2007 11:20:53 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20051007 Debian/1.7.12-1 X-Accept-Language: en MIME-Version: 1.0 To: Segher Boessenkool CC: paulmck@linux.vnet.ibm.com, heiko.carstens@de.ibm.com, horms@verge.net.au, linux-kernel@vger.kernel.org, rpjday@mindspring.com, ak@suse.de, netdev@vger.kernel.org, cfriesen@nortel.com, akpm@linux-foundation.org, torvalds@linux-foundation.org, linux-arch@vger.kernel.org, jesper.juhl@gmail.com, zlynx@acm.org, schwidefsky@de.ibm.com, Chris Snook , davem@davemloft.net, wensong@linux-vs.org, wjiang@resilience.com, David Howells Subject: Re: [PATCH 6/24] make atomic_read() behave consistently on frv References: <20070809134150.GA14890@shell.boston.redhat.com> <2708.1186737826@redhat.com> <7680.1186822071@redhat.com> <46BFFDBD.6080804@redhat.com> <46C140DD.3060509@yahoo.com.au> <2cbda24e96a49c3ab7cf7039c515f9fc@kernel.crashing.org> <20070815191829.GJ9645@linux.vnet.ibm.com> <369924c4b3132a4b06258b7ac81b1006@kernel.crashing.org> <20070815195915.GL9645@linux.vnet.ibm.com> <20070815203836.GO9645@linux.vnet.ibm.com> <7131d547746a998fcec74d1c091f9f6a@kernel.crashing.org> In-Reply-To: <7131d547746a998fcec74d1c091f9f6a@kernel.crashing.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 848 Lines: 22 Segher Boessenkool wrote: >> Please check the definition of "cache coherence". > > > Which of the twelve thousand such definitions? :-) Every definition I have seen says that writes to a single memory location have a serial order as seen by all CPUs, and that a read will return the most recent write in the sequence (with a bit of extra mumbo jumbo to cover store queues and store forwarding). Within such a definition, I don't see how would be allowed for a single CPU to execute reads out of order and have the second read return an earlier write than the first read. -- SUSE Labs, Novell Inc. - 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/