From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757187AbZBSXaa (ORCPT ); Thu, 19 Feb 2009 18:30:30 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754429AbZBSXaU (ORCPT ); Thu, 19 Feb 2009 18:30:20 -0500 Received: from mga03.intel.com ([143.182.124.21]:10945 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753645AbZBSXaU (ORCPT ); Thu, 19 Feb 2009 18:30:20 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.38,237,1233561600"; d="scan'208";a="112486643" Subject: Re: [PATCH] x86: enable x2apic early at the first point From: Suresh Siddha Reply-To: Suresh Siddha To: Yinghai Lu Cc: Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Andrew Morton , "linux-kernel@vger.kernel.org" , gleb@redhat.com In-Reply-To: <499DE05A.40804@kernel.org> References: <499DD40F.40102@kernel.org> <1235081612.14523.23.camel@vayu> <499DE05A.40804@kernel.org> Content-Type: text/plain Organization: Intel Corp Date: Thu, 19 Feb 2009 15:28:38 -0800 Message-Id: <1235086118.14523.40.camel@vayu> Mime-Version: 1.0 X-Mailer: Evolution 2.6.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2009-02-19 at 14:42 -0800, Yinghai Lu wrote: > Ingo want to decouple that x2apic and intr_remapping. > it seems it does work with x2apic without intr_remapping in one of setup. x2apic with out intr-remapping is not architectural. Even when we have < 255 logical cpu's, logical x2apic id's will be greater than 16 bits even on a single/two socket systems and this will break interrupt delivery. Please look at the x2apic logical destination mode definition in the SDM (Section 9.7.2.3 and 9.7.2.4 in my copy of SDM Vol3a) While it might work in certain configurations (for example, physical mode with < 8 bit apicids), it is not architectural and implementation dependent, which may break in future generations. And also, logical x2apic mode has more advantages compared to physical mode (like using lowest priority delivery mode etc). I will post couple of patches, which revert's Gleb's patch and another fix for the early boot failure issue, tomorrow. thanks, suresh