Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753413AbbKXKRb (ORCPT ); Tue, 24 Nov 2015 05:17:31 -0500 Received: from mx2.suse.de ([195.135.220.15]:37774 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752494AbbKXKR2 (ORCPT ); Tue, 24 Nov 2015 05:17:28 -0500 Date: Tue, 24 Nov 2015 11:17:25 +0100 From: Petr Tesarik To: David Vrabel Cc: Malcolm Crossley , Jan Beulich , Daniel Kiper , Juergen Gross , , , , , , , David Mair , , , Subject: Re: [Xen-devel] crash tool - problem with new Xen linear virtual mapped sparse p2m list Message-ID: <20151124111725.4f45412e@hananiah.suse.cz> In-Reply-To: <5654373D.9070403@citrix.com> References: <20151123201830.GN4768@olila.local.net-space.pl> <565409DA.90908@suse.com> <565434F102000078000B8424@prv-mh.provo.novell.com> <56543412.7090104@citrix.com> <5654373D.9070403@citrix.com> Organization: SUSE Linux, s.r.o. X-Mailer: Claws Mail 3.11.0 (GTK+ 2.24.28; x86_64-suse-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1521 Lines: 36 On Tue, 24 Nov 2015 10:09:01 +0000 David Vrabel wrote: > On 24/11/15 09:55, Malcolm Crossley wrote: > > On 24/11/15 08:59, Jan Beulich wrote: > >>>>> On 24.11.15 at 07:55, wrote: > >>> What about: > >>> > >>> 4) Instead of relying on the kernel maintained p2m list for m2p > >>> conversion use the hypervisor maintained m2p list which should be > >>> available in the dump as well. This is the way the alive kernel is > >>> working, so mimic it during crash dump analysis. > >> > >> I fully agree; I have to admit that looking at the p2m when doing page > >> table walks for a PV Dom0 (having all machine addresses in page table > >> entries) seems kind of backwards. (But I say this knowing nothing > >> about the tool.) > >> > > I don't think we can reliably use the m2p for PV domains because > > PV domains don't always issue a m2p update hypercall when they change > > their p2m mapping. > > This only applies to foreign pages which won't be very interesting to a > crash tool. True. I think the main reason crash hasn't done this is that it cannot find the hypervisor maintained m2p list. It should be sufficient to add some more fields to XEN_VMCOREINFO, so that crash can locate the mapping in the dump. Petr T -- 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/