From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753996Ab0J2Fxk (ORCPT ); Fri, 29 Oct 2010 01:53:40 -0400 Received: from mga02.intel.com ([134.134.136.20]:48558 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753481Ab0J2Fxf (ORCPT ); Fri, 29 Oct 2010 01:53:35 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.58,257,1286175600"; d="scan'208";a="568445078" Subject: Re: [PATCH -v3] x86: Disable x2apic if nox2apic is specified From: Suresh Siddha Reply-To: Suresh Siddha To: Yinghai Lu Cc: Thomas Gleixner , "H. Peter Anvin" , Ingo Molnar , Andrew Morton , Len Brown , "linux-kernel@vger.kernel.org" In-Reply-To: <4CC7C64A.4070809@kernel.org> References: <1287882149-29275-1-git-send-email-yinghai@kernel.org> <1287882149-29275-16-git-send-email-yinghai@kernel.org> <4CC4AEAB.4030505@kernel.org> <1288029002.2675.22.camel@sbsiddha-MOBL3.sc.intel.com> <4CC7C64A.4070809@kernel.org> Content-Type: text/plain Organization: Intel Corp Date: Thu, 28 Oct 2010 22:53:28 -0700 Message-Id: <1288331608.2717.14.camel@sbsiddha-MOBL3> Mime-Version: 1.0 X-Mailer: Evolution 2.26.3 (2.26.3-1.fc11) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2010-10-26 at 23:27 -0700, Yinghai Lu wrote: > For > 1. x2apic preenabled system > 2. first kernel have x2apic enabled, and try to kexec second kernel with "nox2apic" > > Will put back cpu with apic id < 255 into xapic mode, instead of panic. > > -v2: use x2apic_disabled instead of nox2apic, Suggested by Thomas > update x2apic_supported with x2apic_disabled, Suggested by Thomas > > -v3: add checking for boot cpu apic id > 255. in that case will just panic > --- pointed out by Suresh. > Can we please hold off in merging this patch for a bit? There are some subtleties in going back to xapic when the platform/cpu's are in x2apic mode. I will check and get back to you on this after KS. thanks, suresh