From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752947Ab0IBG5o (ORCPT ); Thu, 2 Sep 2010 02:57:44 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:55070 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751649Ab0IBG5m (ORCPT ); Thu, 2 Sep 2010 02:57:42 -0400 Date: Thu, 2 Sep 2010 08:57:31 +0200 From: Ingo Molnar To: Peter P Waskiewicz Jr Cc: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, linux-kernel@vger.kernel.org, andi@firstfloor.org, netdev@vger.kernel.org Subject: Re: [PATCH] [arch-x86] Allow SRAT integrity check to be skipped Message-ID: <20100902065731.GB29972@elte.hu> References: <20100901213318.19353.54619.stgit@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100901213318.19353.54619.stgit@localhost.localdomain> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -2.0 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 * Peter P Waskiewicz Jr wrote: > On certain BIOSes, SRAT enumeration isn't exported correctly. This > leads to NUMA node enumeration failure, and causes the kernel to fall > back onto a single node treated as flat memory. This can happen on > large, multi-socket systems (4 or more sockets), and becomes > problematic for performance. > > This patch adds a boot parameter to allow a kernel to be booted with > the option to skip the SRAT check. There are BIOSes in production > that have these failures, so this will allow people in the field to > work around these BIOS issues. > + sratbypassbios > + If specified, will skip an SRAT check for PXM coverage > + from BIOS enumeration. Only to be used on systems with > + buggy BIOSes that munge the SRAT enumeration. This isnt a particularly useful solution to users of said systems - they have to figure out that this option exists, and then they have to enter this option on the boot line. A better solution would be to match these systems using DMI filters - _and_ to also have the boot time option to cover the case where a new system comes out with such a breakage. (or there's some system not yet mapped) Ingo