Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1946394AbWJSTRP (ORCPT ); Thu, 19 Oct 2006 15:17:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1946392AbWJSTRP (ORCPT ); Thu, 19 Oct 2006 15:17:15 -0400 Received: from mx1.redhat.com ([66.187.233.31]:7880 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S1946389AbWJSTRO (ORCPT ); Thu, 19 Oct 2006 15:17:14 -0400 Date: Thu, 19 Oct 2006 15:16:44 -0400 From: Dave Jones To: Len Brown Cc: Linux Kernel , linux-acpi@vger.kernel.org Subject: Re: SMP broken on pre-ACPI machine. Message-ID: <20061019191644.GE26530@redhat.com> Mail-Followup-To: Dave Jones , Len Brown , Linux Kernel , linux-acpi@vger.kernel.org References: <20061018222433.GA4770@redhat.com> <200610190133.40581.len.brown@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200610190133.40581.len.brown@intel.com> User-Agent: Mutt/1.4.2.2i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1932 Lines: 45 On Thu, Oct 19, 2006 at 01:33:40AM -0400, Len Brown wrote: > On Wednesday 18 October 2006 18:24, Dave Jones wrote: > > I've been chasing a bug that got filed against the Fedora kernel > > a while back: https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=199052 > > This is a dual pentium pro from an era before we had ACPI, and > > it seems to be falling foul of this test in smpboot.c .. > > > > if (!smp_found_config && !acpi_lapic) { > > printk(KERN_NOTICE "SMP motherboard not detected.\n"); > > > > My initial reaction is that the !acpi_lapic test should be conditional > > on some variable that gets set if the ACPI parsing actually succeeded. > > acpi_lapic isn't related to the problem at hand -- that smp_found_config is not set. Right, it just seemed odd to me when I was eyeballing this code. > That said, allowing acpi_lapic=1 to bail out of this check has the sole > function of allowing SMP/PIC configurations. (smp_found_config > in ACPI mode is set if acpi_lapic and acpi_ioapic are set) > SMP/PIC configurations are not very interesting, except for debugging. > Indeed, MPS prohibits them by mandating an IOAPIC be present for SMP -- > but ACPI has no such rule. Why smp_found_config isn't set in that guys configuration is a mystery to me, as his MPS tables look sane.. MP Table: # APIC ID Version State Family Model Step Flags # 0 0x10 BSP, usable 6 2 1 0x0381 # 0 0x10 AP, usable 6 1 7 0xfbff Hmm, wait, he has unpaired CPUs. I wonder if that's the reason. I know *some* combinations of PPro's are valid to be paired, but I'll need to dig out the old docs to be sure. Dave -- http://www.codemonkey.org.uk - 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/