From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757080AbYCJXP2 (ORCPT ); Mon, 10 Mar 2008 19:15:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757787AbYCJXOv (ORCPT ); Mon, 10 Mar 2008 19:14:51 -0400 Received: from fmmailgate02.web.de ([217.72.192.227]:33326 "EHLO fmmailgate02.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757766AbYCJXOt (ORCPT ); Mon, 10 Mar 2008 19:14:49 -0400 From: Stephan Diestelhorst To: Andi Kleen Subject: Re: [PATCH 1/1] Speedfreq-SMI call clobbers ECX Date: Tue, 11 Mar 2008 00:14:39 +0100 User-Agent: KMail/1.9.6 Cc: Ingo Molnar , davej@codemonkey.org.uk, cpufreq@lists.linux.org.uk, linux-kernel@vger.kernel.org References: <200803051559.09962.langer_mann@web.de> <87iqzu8r2q.fsf@basil.nowhere.org> <200803102226.39044.langer_mann@web.de> In-Reply-To: <200803102226.39044.langer_mann@web.de> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200803110014.40246.langer_mann@web.de> X-Provags-ID: V01U2FsdGVkX18BclyNJYWPcO+wGsAb8yCVmcCl1Qy7ytdQC0kh yX3sH4gpoXv9QuGBA74qvpkpuIcVq9/9Ne3K96j5cvbYUP/4o5 2xgtHd/xg= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Stephan Diestelhorst wrote: > Andi Kleen wrote: > > Stephan Diestelhorst writes: > > > > > > New attempt with full clobbers, note that I deliberatly did not change > > > the order of the output registers. Real output operands still preceede > > > outputs used for potential clobbering. > > > > > > I'm not too sure about the EBP push/pop frame, but as folks pointed > > > out already, we should not trust the SMI code too much. > > > > Be careful -- older gcc versions tend to abort for inline asm > > that clobbers too many registers. Especially when the register > > is already used (like ebp in a frame pointer enabled kernel) > > > Make sure it at least works on the oldest supported gcc version > > (gcc 3.2) and with frame pointer on. > > As I've said, I do not expect this to be problematic, but will test, > just to be sure! I've tried it on the following GCCs: 3.3, 3.4, 4.0, 4.1, all with and without frame-pointer ommission. Result: As expected. Worked w/o problems, warnings anything. Apologies for not testing gcc-3.2, but compiling it from source did not work with libtool complaining about tags in libmath. I'd be grateful if someone with working gcc-3.2 could try this out. Cheers, Stephan