Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755638Ab2KWLJJ (ORCPT ); Fri, 23 Nov 2012 06:09:09 -0500 Received: from aserp1040.oracle.com ([141.146.126.69]:29481 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755326Ab2KWLJG (ORCPT ); Fri, 23 Nov 2012 06:09:06 -0500 Date: Fri, 23 Nov 2012 12:08:08 +0100 From: Daniel Kiper To: Jan Beulich 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 Message-ID: <20121123110808.GA3002@host-192-168-1-59.local.net-space.pl> References: <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> <50AF635B02000078000AAD0C@nat28.tlf.novell.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <50AF635B02000078000AAD0C@nat28.tlf.novell.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: acsinet22.oracle.com [141.146.126.238] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2369 Lines: 46 On Fri, Nov 23, 2012 at 10:51:55AM +0000, Jan Beulich wrote: > >>> 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. Yep, but we must change Xen kexec interface and/or its behavior first. If we take that option then we could also move almost all needed things from dom0 kernel to Xen. This way we could simplify Linux Kernel kexec/kdump infrastructure needed to run on Xen. Daniel -- 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/