Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764191AbXK3C62 (ORCPT ); Thu, 29 Nov 2007 21:58:28 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1763038AbXK3C6U (ORCPT ); Thu, 29 Nov 2007 21:58:20 -0500 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:51514 "EHLO ebiederm.dsl.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758190AbXK3C6T (ORCPT ); Thu, 29 Nov 2007 21:58:19 -0500 From: ebiederm@xmission.com (Eric W. Biederman) To: Ben Woodard Cc: Vivek Goyal , Neil Horman , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Andi Kleen , hbabu@us.ibm.com, Andi Kleen Subject: Re: [PATCH] kexec: force x86_64 arches to boot kdump kernels on boot cpu References: <200711271445.56792.ak@suse.de> <474C64CB.7080004@redhat.com> <20071127194220.GG14887@hmsendeavour.rdu.redhat.com> <20071127200011.GA3703@redhat.com> <20071127222408.GH24223@one.firstfloor.org> <474CA733.9050908@redhat.com> <20071128153649.GC3192@redhat.com> <20071128160206.GA21286@hmsendeavour.rdu.redhat.com> <20071128190525.GD3192@redhat.com> <474F7290.8010504@redhat.com> Date: Thu, 29 Nov 2007 19:54:16 -0700 In-Reply-To: <474F7290.8010504@redhat.com> (Ben Woodard's message of "Thu, 29 Nov 2007 18:16:48 -0800") Message-ID: User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/21.4 (gnu/linux) 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 Content-Length: 1939 Lines: 51 Ben Woodard writes: > Eric W. Biederman wrote: >> Vivek Goyal writes: >> >>> Ok. Got it. So in this case we route the interrupts directly through LAPIC >>> and put LVT0 in ExtInt mode and IOAPIC is bypassed. >>> >>> I am looking at Intel Multiprocessor specification v1.4 and as per figure >>> 3-3 on page 3-9, 8259 is connected to LINTIN0 line, which in turn is >>> connected to LINTIN0 pin on all processors. If that is the case, even in >>> this mode, all the CPU should see the timer interrupts (which is coming >>> from 8259)? >> >> However things are implemented completely differently now. I don't think >> the coherent hypertransport domain of AMD processors actually routes >> ExtINT interrupts to all cpus but instead one (the default route?) is >> picked. >> >> So I think for the kdump case we pretty much need to use an IOAPIC >> in virtual wire mode for recent AMD systems. >> >> For current Intel systems I believe either scenario still works. >> >>> Can you print the LAPIC registers (print_local_APIC) during normal boot >>> and during kdump boot and paste here? >> >> It's worth a look. >> >> I still think we need to just use apic mode at kernel startup, and >> be done with it. >> > > Neil whipped up a patch to try this and evidently it worked on his test boxes > but it didn't work very well on our problem tests box. It hung after the kernel > printed "Ready". i.e. on a normal boot I get: Interesting can you please try an early_printk console. I expect you made it a fair ways and it just didn't show up because you didn't get as far as the normal serial port setup. You don't have any output from your linux kernel. Eric - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/