Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261317AbTIBSwg (ORCPT ); Tue, 2 Sep 2003 14:52:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261324AbTIBSwg (ORCPT ); Tue, 2 Sep 2003 14:52:36 -0400 Received: from caramon.arm.linux.org.uk ([212.18.232.186]:58126 "EHLO caramon.arm.linux.org.uk") by vger.kernel.org with ESMTP id S261317AbTIBSwe (ORCPT ); Tue, 2 Sep 2003 14:52:34 -0400 Date: Tue, 2 Sep 2003 19:52:22 +0100 From: Russell King To: Jamie Lokier Cc: "Paul J.Y. Lahaie" , linux-kernel@vger.kernel.org Subject: Re: x86, ARM, PARISC, PPC, MIPS and Sparc folks please run this Message-ID: <20030902195222.D9345@flint.arm.linux.org.uk> Mail-Followup-To: Jamie Lokier , "Paul J.Y. Lahaie" , linux-kernel@vger.kernel.org References: <20030829053510.GA12663@mail.jlokier.co.uk> <1062188787.4062.21.camel@elenuial.steamballoon.com> <20030901091524.A15370@flint.arm.linux.org.uk> <20030901101224.GB1638@mail.jlokier.co.uk> <20030901151710.A22682@flint.arm.linux.org.uk> <20030901165239.GB3556@mail.jlokier.co.uk> <20030901181148.C22682@flint.arm.linux.org.uk> <20030902053415.GA7619@mail.jlokier.co.uk> <20030902091553.A29984@flint.arm.linux.org.uk> <20030902115731.GA14354@mail.jlokier.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <20030902115731.GA14354@mail.jlokier.co.uk>; from jamie@shareable.org on Tue, Sep 02, 2003 at 12:57:31PM +0100 X-Message-Flag: Your copy of Microsoft Outlook is vulnerable to viruses. See www.mutt.org for more details. Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1334 Lines: 30 On Tue, Sep 02, 2003 at 12:57:31PM +0100, Jamie Lokier wrote: > You say that "reading from the first mapping _should_ return the > second write value no matter what", but that there's a bug in the > write buffer and it isn't doing that. > > I'm saying that the bug can't be that, because such a bug would affect > normal applications. I know of no other explaination which fits with the information I have available to me here. If you'd care to speculate further, you may, but I see further speculation as being rather academic, unless it comes from one of the people who designed the chip. All this is, however, immateral - the facts are that the write buffer is buggy, this test detects it, and we can take fairly easy measures to ensure we fix it up. Multiple mappings of the same object rarely occur in my experience, so the resulting performance loss caused by working around the cache and writebuffer is something we can live with. -- Russell King (rmk@arm.linux.org.uk) The developer of ARM Linux http://www.arm.linux.org.uk/personal/aboutme.html - 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/