From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753842AbYDFLWk (ORCPT ); Sun, 6 Apr 2008 07:22:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750748AbYDFLWb (ORCPT ); Sun, 6 Apr 2008 07:22:31 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:53782 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750720AbYDFLWa (ORCPT ); Sun, 6 Apr 2008 07:22:30 -0400 Date: Sun, 6 Apr 2008 13:22:08 +0200 From: Ingo Molnar To: Rusty Russell Cc: Linus Torvalds , Andi Kleen , "H. Anvin" , linux-kernel@vger.kernel.org, lguest , Thomas Gleixner Subject: Re: [PATCH] Fix booting pentium+ with dodgy TSC Message-ID: <20080406112207.GA26510@elte.hu> References: <200804061723.38766.rusty@rustcorp.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200804061723.38766.rusty@rustcorp.com.au> User-Agent: Mutt/1.5.17 (2007-11-01) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Rusty Russell wrote: > Linus please apply. Almost by definition this patch can't make things > worse. well, while i agree with the patch it could make things worse. In this case it can cause code that has been compiled to rely on TSC to malfunction. For if sched_clock() was using cpu_has_tsc it could return 0 all the time, breaking the scheduler without the user having a clear idea why it broke. It isnt, and sched_clock() will work fine, but still, your "this cant make things worse" statement is not completely correct. In any case: Acked-by: Ingo Molnar and i've also queued it up into the for-.25 queue of x86.git. Ingo