From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757689AbYBXPRs (ORCPT ); Sun, 24 Feb 2008 10:17:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750832AbYBXPRk (ORCPT ); Sun, 24 Feb 2008 10:17:40 -0500 Received: from aun.it.uu.se ([130.238.12.36]:35062 "EHLO aun.it.uu.se" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750738AbYBXPRj (ORCPT ); Sun, 24 Feb 2008 10:17:39 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <18369.35401.678391.183329@harpo.it.uu.se> Date: Sun, 24 Feb 2008 16:16:25 +0100 From: Mikael Pettersson To: Ingo Molnar Cc: Mikael Pettersson , linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, tglx@linutronix.de Subject: Re: [BUG] 2.6.25-rc2-git8 fails to boot on 486 due to TSC breakage In-Reply-To: <20080224135720.GA5323@elte.hu> References: <200802241107.m1OB7bHb022801@harpo.it.uu.se> <20080224135720.GA5323@elte.hu> X-Mailer: VM 7.17 under Emacs 20.7.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ingo Molnar writes: > > * Mikael Pettersson wrote: > > > The kernel for this 486 has CONFIG_M486=y and CONFIG_M586TSC=n, but > > the 2.6.25 kernels still try to access the TSC. Here's the oops from > > 2.6.25-rc2-git8: > > hm, could you send me the full .config you used? I've put it here: Meanwhile, I've traced the breakage to 2.6.24-git8. 2.6.24-git8 changed include/asm-x86/tsc.h:get_cycles() to call rdtscll() even if CONFIG_X86_TSC isn't set. The call is protected by a cpu_has_tsc test, but starting with 2.6.24-git8 cpu_has_tsc is non-zero on this machine, which is very very wrong. Diffing dmesg between git7 and git8 doesn't sched any light since git8 also removed the printouts of the x86 caps as they were being initialised and updated. I'm currently adding those printouts back in the hope of seeing where and when the caps get broken.