Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755158AbYHKUIh (ORCPT ); Mon, 11 Aug 2008 16:08:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752375AbYHKUI3 (ORCPT ); Mon, 11 Aug 2008 16:08:29 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:42753 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751204AbYHKUI2 (ORCPT ); Mon, 11 Aug 2008 16:08:28 -0400 Date: Mon, 11 Aug 2008 22:08:08 +0200 From: Ingo Molnar To: Yinghai Lu Cc: Jeff Chua , Linus Torvalds , David Miller , Max Krasnyansky , Li Zefan , lkml Subject: Re: 2.6.27rc1 cannot boot more than 8CPUs Message-ID: <20080811200808.GB24111@elte.hu> References: <20080811195939.GA16716@elte.hu> <86802c440808111303x16922f43g4e17fa43972e9076@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <86802c440808111303x16922f43g4e17fa43972e9076@mail.gmail.com> User-Agent: Mutt/1.5.18 (2008-05-17) 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 Content-Length: 2353 Lines: 57 * Yinghai Lu wrote: > On Mon, Aug 11, 2008 at 12:59 PM, Ingo Molnar wrote: > > > > * Jeff Chua wrote: > > > >> On Wed, Aug 6, 2008 at 2:42 PM, Jeff Chua wrote: > >> > On Wed, Aug 6, 2008 at 2:01 PM, Linus Torvalds > >> > wrote: > >> >> One trivial thing to try would be to just bisect it. I assume 2.6.26 is > >> > Bisecting now. > >> > >> Thanks to all the great helpful suggestions from everyone, and this > >> turns out that I just need to enable the following switches, so I > >> didn't bisect further, and since it's first machine that I've tried > >> with more than 8 CPUs so I wasn't sure whether 2.6.16 has the same > >> problem, but if you wish, I could give 2.6.16 a try. > >> > >> > CONFIG_X86_GENERICARCH=y > >> > CONFIG_X86_BIGSMP=y > >> > >> Thank you all for the great linux kernel! > > > > i still consider a silent boot hang a bug we need to fix. > > > > bigsmp might be required to have all cpus available on your box, but the > > kernel is still supposed to transparently fall back to less CPUs (and > > print a warning) if it cannot do that. > > > in setup.c::setup_arch() after go over with madt or mptable > > #if defined(CONFIG_SMP) && defined(CONFIG_X86_PC) && defined(CONFIG_X86_32) > if (def_to_bigsmp) > printk(KERN_WARNING "More than 8 CPUs detected and " > "CONFIG_X86_PC cannot handle it.\nUse " > "CONFIG_X86_GENERICARCH or > CONFIG_X86_BIGSMP.\n"); ===> here need to change "or" to "and" > #endif > > or just panic here? because screen scroll to pass it, and user will > not notice that... a panic is better but still quite rude and doesnt give a user a system under which he can build an even greater kernel [after having discovered the warning in the syslog] ;-) best would be to use as many CPUs as we can support, and skip the rest and boot up fine. (and print the warning prominently - the user does not make maximum use of available physical resources) Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/