From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758039Ab1F3AnA (ORCPT ); Wed, 29 Jun 2011 20:43:00 -0400 Received: from rcsinet10.oracle.com ([148.87.113.121]:21710 "EHLO rcsinet10.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754704Ab1F3Am4 convert rfc822-to-8bit (ORCPT ); Wed, 29 Jun 2011 20:42:56 -0400 References: <4E0BA7FE.9050607@hp.com> In-Reply-To: <4E0BA7FE.9050607@hp.com> Mime-Version: 1.0 (iPhone Mail 8C148) Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset=us-ascii Message-Id: Cc: "tglx@linutronix.de" , "mingo@redhat.com" , "hpa@zytor.com" , "x86@kernel.org" , Feng Tang , "ebiederm@xmission.com" , "linux-kernel@vger.kernel.org" X-Mailer: iPhone Mail (8C148) From: Yinghai Subject: Re: MPS table vs ACPI Date: Wed, 29 Jun 2011 17:40:37 -0700 To: sreenivasa reddy berahalli X-Source-IP: acsinet21.oracle.com [141.146.126.237] X-Auth-Type: Internal IP X-CT-RefId: str=0001.0A090206.4E0BC61A.010D,ss=1,re=0.000,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Jun 29, 2011, at 3:32 PM, sreenivasa reddy berahalli wrote: > Hello All, > > Recent interaction with BIOS teams within in my Organization left me > wondering if MP table spec from Intel is no more a mandatory one > http://www.intel.com/design/pentium/datashts/24201606.pdf > > Section #8.4.5 http://www.intel.com/Assets/PDF/manual/253668.pdf > Talks as ACPI or MPS table. > That means BIOS can report through ACPI tables only. > > I looked through x86 boot sequence and notice Linux scanning for MPS > table in below locations and Linux doesn't seem to go further without > MPS table or doesn't know how to live with ACPI only. > 1) Scan the bottom 1K for a signature > 2) Scan the top 1K of base RAM > 3) Scan the 64K of bios Have one system with x2apic pre-enabled in bios, and it does not have mps table from bios. At least 2.6.32 based distribution kernel works well. Current kernel works well too if you have acpi enabled in kernel. Mptable assume apicid is 8 bits Thanks Yinghai