Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753564Ab2KWKid (ORCPT ); Fri, 23 Nov 2012 05:38:33 -0500 Received: from aserp1040.oracle.com ([141.146.126.69]:45755 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751413Ab2KWKia (ORCPT ); Fri, 23 Nov 2012 05:38:30 -0500 Date: Fri, 23 Nov 2012 11:37:26 +0100 From: Daniel Kiper To: Jan Beulich Cc: Andrew Cooper , "H. Peter Anvin" , "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" Subject: Re: [PATCH v2 01/11] kexec: introduce kexec_ops struct Message-ID: <20121123103726.GB2921@host-192-168-1-59.local.net-space.pl> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <50AF55B102000078000AABF3@nat28.tlf.novell.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: ucsinet21.oracle.com [156.151.31.93] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2264 Lines: 46 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. > It's just that parts of the kexec infrastructure can be re-used > (and hence that mechanism probably seemed the easier approach > to the implementer of the original kexec-on-Xen). If the kernel > folks dislike that re-use (quite understandably looking at how > much of it needs to be re-done), that shouldn't prevent us from > looking into the existing alternatives. This is last resort option. First I think we should try to find good solution which reuses existing code as much as possible. 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/