From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750819AbbJAVls (ORCPT ); Thu, 1 Oct 2015 17:41:48 -0400 Received: from www.linutronix.de ([62.245.132.108]:39287 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750745AbbJAVlr (ORCPT ); Thu, 1 Oct 2015 17:41:47 -0400 Date: Thu, 1 Oct 2015 23:41:02 +0200 (CEST) From: Thomas Gleixner To: Andi Kleen cc: Andi Kleen , x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86: Fix thermal throttling reporting after kexec In-Reply-To: <20151001172737.GC26924@tassilo.jf.intel.com> Message-ID: References: <1443125443-24691-1-git-send-email-andi@firstfloor.org> <20151001172737.GC26924@tassilo.jf.intel.com> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 1 Oct 2015, Andi Kleen wrote: > On Thu, Oct 01, 2015 at 02:15:54PM +0200, Thomas Gleixner wrote: > > On Thu, 24 Sep 2015, Andi Kleen wrote: > > > The per CPU thermal vector init code checks if the thermal > > > vector is already installed and complains and bails out if > > > it is. > > > > > > This happens after kexec, as kernel shut down does > > > not clear the thermal vector APIC register. > > > > So the obvious question is, why don't we do that. > > It wouldn't help if the previous kernel is some older kernel. I know. > > > > > Just remove the check. I checked the code and there's > > > no valid code paths where the thermal init code for a CPU > > > could be called multiple times. > > > > I'm not against removing that check as it does not really add value, > > but we still should clear the APIC register at shut down, right? > > The vector register is really harmless by itself and apart from > bogus checking it's not really affecting anyone. It may make > more sense to disable thermal reporting on shut down though. > > I can add that, although it would only be useful for the more > theoretical case when you boot non Linux after kexec (as normal > Linux always reenables it anyways) I see it under the correctness aspect. Mop up before you shut down. > But the check should still be removed imho. As I said before: I have no objections against that. Thanks, tglx