From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755522AbZBFTba (ORCPT ); Fri, 6 Feb 2009 14:31:30 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753787AbZBFTbW (ORCPT ); Fri, 6 Feb 2009 14:31:22 -0500 Received: from rcsinet13.oracle.com ([148.87.113.125]:51602 "EHLO rgminet13.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753674AbZBFTbV (ORCPT ); Fri, 6 Feb 2009 14:31:21 -0500 Message-ID: <498C8FE8.8090608@oracle.com> Date: Fri, 06 Feb 2009 11:30:48 -0800 From: Randy Dunlap Organization: Oracle Linux Engineering User-Agent: Thunderbird 2.0.0.6 (X11/20070801) MIME-Version: 1.0 To: Ben Greear CC: Ingo Molnar , Yinghai Lu , "H. Peter Anvin" , Thomas Gleixner , "Maciej W. Rozycki" , linux-kernel , len.brown@intel.com Subject: Re: PATCH: (v2) Allow over-ride of smp_found_cfg with kernel cmd-line option. References: <498B421D.9090609@candelatech.com> <20090205195832.GD3129@elte.hu> <498C8DB7.3000005@candelatech.com> In-Reply-To: <498C8DB7.3000005@candelatech.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Source-IP: acsmt706.oracle.com [141.146.40.84] X-Auth-Type: Internal IP X-CT-RefId: str=0001.0A09020B.498C8FE0.02FD:SCFSTAT928724,ss=1,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ben Greear wrote: > Ingo Molnar wrote: >> * Ben Greear wrote: >> >>> Allow user to keep smp_found_cfg set to 1 even if MADT >>> cannot be parsed. This works around funky BIOS on FWA-7304 >>> (VIA CN700 chipset) system, and possibly other systems as well. >>> Without this override, performance drops by around 15% on >>> network throughput tests on this system. > >> I'd _much_ rather have a warning message printed and have a default, >> unconditional fallback to mptable parsing in this case. >> >> I.e. same end result just no ugly and inconvenient force_smp_found_cfg. >> >> The mptable works fine in most such cases to enumerate apic details. >> (as it does in your case, evidently) >> >> And if both the ACPI and the MPTABLE is hosed on a box, it cannot be >> of much use on other OSs either, right? >> >> So please do a patch that removes the 'smp_found_config' and which >> changes the warning message to warn about no ACPI table in the MADT >> table. Ok? > > An updated patch is attached. It's also inline below, but I'm sure the > inline version is white-space corrupted. > > Do not disable mptable parsing just because there is no ACPI table > in the MADT table. This effectively backs out changeset > 7b37b5fd9ba32c0c5afc3537eed7e7466f2173e2 > > Signed-Off-By: Ben Greear > > Thanks, > Ben > > > diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c > index d37593c..74a50b6 100644 > --- a/arch/x86/kernel/acpi/boot.c > +++ b/arch/x86/kernel/acpi/boot.c > @@ -1379,12 +1379,14 @@ static void __init acpi_process_madt(void) > * ACPI found no MADT, and so ACPI wants UP PIC mode. > * In the event an MPS table was found, forget it. > * Boot with "acpi=off" to use MPS on such a system. > + * > + * NOTE: This assumption seems wrong in at least some cases, > perhaps > + * when ACPI is off in the BIOS. Changing to a warning without > + * setting smp_found_config to zero. > */ > - if (smp_found_config) { > + if (smp_found_config) > printk(KERN_WARNING PREFIX > - "No APIC-table, disabling MPS\n"); > - smp_found_config = 0; > - } > + "WARNING: No ACPI-table found in the MADT\n"); APIC table > } > > /* > > > -- ~Randy