From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761982AbXEVX2M (ORCPT ); Tue, 22 May 2007 19:28:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761158AbXEVX14 (ORCPT ); Tue, 22 May 2007 19:27:56 -0400 Received: from ozlabs.org ([203.10.76.45]:37106 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760936AbXEVX1z (ORCPT ); Tue, 22 May 2007 19:27:55 -0400 Subject: Re: lguest broken in 2.6.22-rc1-mm1 From: Rusty Russell To: Matt Mackall Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org In-Reply-To: <20070522223828.GV11115@waste.org> References: <20070522223828.GV11115@waste.org> Content-Type: text/plain Date: Wed, 23 May 2007 09:27:40 +1000 Message-Id: <1179876460.20705.157.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.10.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2007-05-22 at 17:38 -0500, Matt Mackall wrote: > [ 0.120007] EIP is at resync_sc_freq+0x4b/0x56 Hi Matt, Thanks for the report! Andrew should have these two patches queued, but here they are again: If you set tsc_disable (eg "notsc" on cmdline), sched-clock.c gives a divide by zero on boot. Signed-off-by: Rusty Russell --- arch/i386/kernel/sched-clock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) =================================================================== --- a/arch/i386/kernel/sched-clock.c +++ b/arch/i386/kernel/sched-clock.c @@ -103,7 +103,7 @@ static void resync_sc_freq(struct sc_dat static void resync_sc_freq(struct sc_data *sc, unsigned int newfreq) { sc->sync_base = jiffies; - if (!cpu_has_tsc) { + if (!cpu_has_tsc || tsc_disable) { sc->unstable = 1; return; } Lguest guests don't use the TSC, and so we must disable it otherwise sched-clock.c barfs. Also, we no longer need to explicitly set the PGE feature bit: cpu_detect->cpuid->lguest_cpuid does that for us now that cpu_detect uses paravirt_ops (IIRC it used to do a direct cpuid from assembler). Signed-off-by: Rusty Russell --- drivers/lguest/lguest.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) =================================================================== --- a/drivers/lguest/lguest.c +++ b/drivers/lguest/lguest.c @@ -504,10 +504,10 @@ __init void lguest_init(void *boot) reserve_top_address(lguest_data.reserve_mem); cpu_detect(&new_cpu_data); - /* Need this before paging_init. */ - set_bit(X86_FEATURE_PGE, new_cpu_data.x86_capability); /* Math is always hard! */ new_cpu_data.hard_math = 1; + + tsc_disable = 1; #ifdef CONFIG_X86_MCE mce_disabled = 1;