Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758835Ab2KWB4O (ORCPT ); Thu, 22 Nov 2012 20:56:14 -0500 Received: from smtp.eu.citrix.com ([46.33.159.39]:1209 "EHLO SMTP.EU.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753039Ab2KWB4K (ORCPT ); Thu, 22 Nov 2012 20:56:10 -0500 X-IronPort-AV: E=Sophos;i="4.83,304,1352073600"; d="scan'208";a="15964046" Message-ID: <50AED7B8.7040902@citrix.com> Date: Fri, 23 Nov 2012 01:56:08 +0000 From: Andrew Cooper User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: "H. Peter Anvin" CC: "Eric W. Biederman" , Daniel Kiper , "jbeulich@suse.com" , "konrad.wilk@oracle.com" , "mingo@redhat.com" , "tglx@linutronix.de" , "x86@kernel.org" , "kexec@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "virtualization@lists.linux-foundation.org" , "xen-devel@lists.xensource.com" Subject: Re: [PATCH v2 01/11] kexec: introduce kexec_ops struct References: <1353423893-23125-1-git-send-email-daniel.kiper@oracle.com> <1353423893-23125-2-git-send-email-daniel.kiper@oracle.com> <87lidwtego.fsf@xmission.com> <20121121105221.GA2925@host-192-168-1-59.local.net-space.pl> <87txshx28b.fsf@xmission.com> <50AE6542.3020302@zytor.com> <50AEBF86.50501@citrix.com> <18e831d4-910d-4f58-8911-1398b96e3a47@email.android.com> In-Reply-To: <18e831d4-910d-4f58-8911-1398b96e3a47@email.android.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1406 Lines: 29 On 23/11/2012 01:38, H. Peter Anvin wrote: > I still don't really get why it can't be isolated from dom0, which would make more sense to me, even for a Xen crash. > The crash region (as specified by crashkernel= on the Xen command line) is isolated from dom0. dom0 (using the kexec utility etc) has the task of locating the Xen crash notes (using the kexec hypercall interface), constructing a binary blob containing kernel, initram and gubbins, and asking Xen to put this blob in the crash region (again, using the kexec hypercall interface). I do not see how this is very much different from the native case currently (although please correct me if I am misinformed). Linux has extra work to do by populating /proc/iomem with the Xen crash regions boot (so the kexec utility can reference their physical addresses when constructing the blob), and should just act as a conduit between the kexec system call and the kexec hypercall to load the blob. For within-guest kexec/kdump functionality, I agree that it is barking mad. However, we do see cloud operators interested in the idea so VM administrators can look after their crashes themselves. ~Andrew -- 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/