From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 22 May 2002 13:01:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 22 May 2002 13:01:07 -0400 Received: from bdsl.66.13.29.10.gte.net ([66.13.29.10]:39808 "EHLO Bluesong.NET") by vger.kernel.org with ESMTP id ; Wed, 22 May 2002 13:01:06 -0400 Message-Id: <200205221710.g4MHAhX05491@Bluesong.NET> Content-Type: text/plain; charset=US-ASCII From: "Jack F. Vogel" Reply-To: jfv@bluesong.net To: Greg KH , mingo@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] 2.5.17 fix for running a SMP kernel on a UP box Date: Wed, 22 May 2002 10:10:43 -0700 X-Mailer: KMail [version 1.3.1] In-Reply-To: <20020521215217.GA3784@kroah.com> Cc: jfv@us.ibm.com MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 21 May 2002 02:52 pm, Greg KH wrote: > I can't seem to run a SMP 2.5.17 kernel on a UP machine, it locks up > during the boot process. In talking to Jack Vogel, he suggested I make > the following patch, which seems to solve the problem for me. In > looking at the code, I have no idea of why this seems to work, so there > probably is a better fix out there. > > Any suggestions? > > thanks, > > greg k-h I should add one bit of information. I originally saw this problem on a UP IBM Netvista machine, its the same box Greg had it happen on. However, I have a 933Mhz PIII HP box at home and it does not have the problem. Since we are limited in the variety of machines to test on I am not sure about this, but I believe its only going to occur on UP systems with an IOAPIC. If you apply the irq_balance patch to a 2.4.* kernel you can recreate the same hang, in fact it was on 2.4.18 that i first ran into it. I realize its kinda a corner case, running an SMP kernel on a subset of UP machines, but hey, I figure its supposed to work :) > > diff -Nru a/arch/i386/kernel/io_apic.c b/arch/i386/kernel/io_apic.c > --- a/arch/i386/kernel/io_apic.c Tue May 21 14:47:06 2002 > +++ b/arch/i386/kernel/io_apic.c Tue May 21 14:47:06 2002 > @@ -205,7 +205,7 @@ > } ____cacheline_aligned irq_balance_t; > > static irq_balance_t irq_balance[NR_IRQS] __cacheline_aligned > - = { [ 0 ... NR_IRQS-1 ] = { 1, 0 } }; > + = { [ 0 ... NR_IRQS-1 ] = { 0, 0 } }; > > extern unsigned long irq_affinity [NR_IRQS]; Cheers, -- Jack F. Vogel IBM Linux Solutions jfv@us.ibm.com (work) jfv@Bluesong.NET (home)