From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261337AbTIROGZ (ORCPT ); Thu, 18 Sep 2003 10:06:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261344AbTIROGZ (ORCPT ); Thu, 18 Sep 2003 10:06:25 -0400 Received: from pix-525-pool.redhat.com ([66.187.233.200]:273 "EHLO lacrosse.corp.redhat.com") by vger.kernel.org with ESMTP id S261337AbTIROGY (ORCPT ); Thu, 18 Sep 2003 10:06:24 -0400 Date: Thu, 18 Sep 2003 15:05:09 +0100 From: Dave Jones To: Pavel Machek Cc: richard.brunner@amd.com, alan@lxorguk.ukuu.org.uk, davidsen@tmr.com, zwane@linuxpower.ca, linux-kernel@vger.kernel.org Subject: Re: [PATCH] 2.6 workaround for Athlon/Opteron prefetch errata Message-ID: <20030918140509.GM8764@redhat.com> Mail-Followup-To: Dave Jones , Pavel Machek , richard.brunner@amd.com, alan@lxorguk.ukuu.org.uk, davidsen@tmr.com, zwane@linuxpower.ca, linux-kernel@vger.kernel.org References: <99F2150714F93F448942F9A9F112634C0638B1DE@txexmtae.amd.com> <20030918074331.GA386@elf.ucw.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20030918074331.GA386@elf.ucw.cz> User-Agent: Mutt/1.5.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 18, 2003 at 09:43:31AM +0200, Pavel Machek wrote: > > The user space problem worries me more, because the expectation > > is that if CPUID says the program can use perfetch, it could > > and should regardless of what the kernel decided to do here. > > User programs should not rely on cpuid; Depends. /dev/cpu/x/cpuid is preferred over cpuinfo, as it remains constant across kernel versions. > they should read /proc/cpuinfo exactly because this kind of errata. We don't do any change to /proc/cpuinfo in this case. As I mentioned in an earlier mail, the only way you could disable prefetch in this way would be by reporting the entire sse/3dnow instruction sets as unavailable which is overkill. With Andi's fix, userspace programs doing prefetch get fixed up transparently, making this a non-issue. Dave -- Dave Jones http://www.codemonkey.org.uk