From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751114AbWACEqr (ORCPT ); Mon, 2 Jan 2006 23:46:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751155AbWACEqr (ORCPT ); Mon, 2 Jan 2006 23:46:47 -0500 Received: from e5.ny.us.ibm.com ([32.97.182.145]:707 "EHLO e5.ny.us.ibm.com") by vger.kernel.org with ESMTP id S1751114AbWACEqq (ORCPT ); Mon, 2 Jan 2006 23:46:46 -0500 Date: Tue, 3 Jan 2006 10:16:32 +0530 From: Vivek Goyal To: Andi Kleen Cc: "Eric W. Biederman" , Fastboot mailing list , linux kernel mailing list , Morton Andrew Morton Subject: Inclusion of x86_64 memorize ioapic at bootup patch Message-ID: <20060103044632.GA4969@in.ibm.com> Reply-To: vgoyal@in.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi Andi, Can you please include the following patch. This patch has already been pushed by Andrew. http://kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.15-rc5/2.6.15-rc5-mm3/broken-out/x86_64-io_apicc-memorize-at-bootup-where-the-i8259-is.patch This patch is regarding remembering at boot up time where i8259 is connected and restore the APIC settings back during kexec boot or kdump boot. This enables getting timer interrupts in new kernel in legacy mode. This patch is needed to make kexec and kdump work on some systems, especially opteron boxes. Otherwise the second kernel does not receive timer interrupts during early boot hence hangs. I understand, that you are inclined towards remembering all the APIC states and simply restore it back instead of putting hooks. This will work well for kexec but not for kdump because in kdump system can crash on non-boot cpu. Restoring BIOS APIC state can make sure that BIOS designated boot cpu will always be able to see timer interrupts in legacy mode but same does not hold good if new kernel boots on some other cpu as is the case with kdump. In case of kexec boot, we relocate to boot cpu but in case of kdump we don't because it was suggested that in some extreme cases of crash, boot cpu might not respond even to NMI and relocation to boot cpu will not be possible. Can you please re-consider this patch for inclusion. Thanks Vivek