From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261372AbVBGHjn (ORCPT ); Mon, 7 Feb 2005 02:39:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261371AbVBGHjn (ORCPT ); Mon, 7 Feb 2005 02:39:43 -0500 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:14478 "EHLO ebiederm.dsl.xmission.com") by vger.kernel.org with ESMTP id S261372AbVBGHjl (ORCPT ); Mon, 7 Feb 2005 02:39:41 -0500 To: Itsuro Oda Cc: fastboot , lkml Subject: Re: [Fastboot] Re: kdump on non-boot cpu References: <20050204082358.18ED.ODA@valinux.co.jp> <20050204144438.18F9.ODA@valinux.co.jp> From: ebiederm@xmission.com (Eric W. Biederman) Date: 07 Feb 2005 00:37:36 -0700 In-Reply-To: <20050204144438.18F9.ODA@valinux.co.jp> Message-ID: User-Agent: Gnus/5.0808 (Gnus v5.8.8) Emacs/21.2 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Itsuro Oda writes: > > So I believe the fix needs to be to enable apics before we calibrate > > the delay timer. I'm not certain off the top of my head what that > > patch will look like but it should not be fundamentally hard. > > With that code in place we also don't need to do any APIC shutdown > > as the kernel knows enough to completely setup the apics. > > I see. Thank you for your explanation. I have done a bit more digging. For some reason, likely historical we don't initialize the IO_APIC in init_IRQ(). Instead we wait until smp_prepare_cpus() or smp_init(). Both functions are called much later in the init process than calibrate_delay(). Given the separation that has happened between apics and SMP it should be possible to initialize the local apic and the IO_APIC of the boot cpu much earlier in the game. It looks like it may take some heavy lifting though. Eric