From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751601Ab2LTQtR (ORCPT ); Thu, 20 Dec 2012 11:49:17 -0500 Received: from terminus.zytor.com ([198.137.202.10]:54554 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751181Ab2LTQtI (ORCPT ); Thu, 20 Dec 2012 11:49:08 -0500 Message-ID: <50D3415F.8010205@zytor.com> Date: Thu, 20 Dec 2012 08:48:31 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Yinghai Lu CC: "Zhang, Lin-Bao (Linux Kernel R&D)" , "linux-kernel@vger.kernel.org" , "alan@lxorguk.ukuu.org.uk" , "mingo@redhat.com" , "tglx@linutronix.de" , "x86@kernel.org" , "a.p.zijlstra@chello.nl" , "jarkko.sakkinen@intel.com" , "joerg.roedel@amd.com" , "agordeev@redhat.com" Subject: Re: Why Linux kernel forced to enter X2APIC mode( just because of booting cpu has supported x2apic) without depending on BIOS' setting in MSR->x2apic enablement bit ? References: <92645B27BF79D04FBD2B0F8494FFD0F91F1CAF@G1W3649.americas.hpqcorp.net> <92645B27BF79D04FBD2B0F8494FFD0F91F2222@G1W3649.americas.hpqcorp.net> <92645B27BF79D04FBD2B0F8494FFD0F91F2600@G1W3649.americas.hpqcorp.net> In-Reply-To: X-Enigmail-Version: 1.4.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/20/2012 08:46 AM, Yinghai Lu wrote: > On Thu, Dec 20, 2012 at 2:38 AM, Zhang, Lin-Bao (Linux Kernel R&D) > wrote: >> I think current core argument is our BIOS did following judgement , >> but Linux kernel did not(Linux seems just judge BSP supports x2apic mode or not by CPUID method) > > kernel checks that, if the BSP in x2apic mode, kernel will check if > intr-remapping can be enabled, otherwise > it will switch back to xapic mode. > >> Our BSP really supports x2apic mode, however,as this spec, our BIOS think some of configuration of server >> could not meet x2apic conditions ,So didn't place local xAPICs into x2apic mode. >> But linux kernel indeed enable x2apic mode(just believe BSP, didn't do above judgement) . so this is the conflict. > > so your BIOS is wrong, it does not enable intr-remapping. > FWIW, I bought a *server* today and it didn't have interrupt remapping and x2APIC, I would consider it defective and return it. -hpa