From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753919Ab2KWKvJ (ORCPT ); Fri, 23 Nov 2012 05:51:09 -0500 Received: from nat28.tlf.novell.com ([130.57.49.28]:47346 "EHLO nat28.tlf.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753224Ab2KWKvC convert rfc822-to-8bit (ORCPT ); Fri, 23 Nov 2012 05:51:02 -0500 Message-Id: <50AF635B02000078000AAD0C@nat28.tlf.novell.com> X-Mailer: Novell GroupWise Internet Agent 12.0.1 Date: Fri, 23 Nov 2012 10:51:55 +0000 From: "Jan Beulich" To: "Daniel Kiper" Cc: "Andrew Cooper" , "x86@kernel.org" , "tglx@linutronix.de" , "kexec@lists.infradead.org" , "virtualization@lists.linux-foundation.org" , "xen-devel@lists.xensource.com" , "konrad.wilk@oracle.com" , "mingo@redhat.com" , "linux-kernel@vger.kernel.org" , "Eric W. Biederman" , "H. Peter Anvin" 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> <50AED7B8.7040902@citrix.com> <50AF55B102000078000AABF3@nat28.tlf.novell.com> <20121123103726.GB2921@host-192-168-1-59.local.net-space.pl> In-Reply-To: <20121123103726.GB2921@host-192-168-1-59.local.net-space.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>> On 23.11.12 at 11:37, Daniel Kiper wrote: > On Fri, Nov 23, 2012 at 09:53:37AM +0000, Jan Beulich wrote: >> >>> On 23.11.12 at 02:56, Andrew Cooper wrote: >> > 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. >> >> But all of this _could_ be done completely independent of the >> Dom0 kernel's kexec infrastructure (i.e. fully from user space, >> invoking the necessary hypercalls through the privcmd driver). > > No, this is impossible. kexec/kdump image lives in dom0 kernel memory > until execution. That is why privcmd driver itself is not a solution > in this case. Even if so, there's no fundamental reason why that kernel image can't be put into Xen controlled space instead. Jan