Date: Mon, 22 Jul 2013 11:33:15 -0700
From: Greg KH <gregkh@linuxfoundation.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
        Daniel Kiper <daniel.kiper@oracle.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        linux-kernel@vger.kernel.org, Brandon Philips <brandon@ifup.org>,
        xen-devel@lists.xensource.com,
        virtualization@lists.linux-foundation.org
Subject: Re: is kexec on Xen domU possible?
Message-ID: <20130722183315.GA29273@kroah.com>
References: <20130719020603.GA22932@kroah.com>
 <20130719131819.GC11233@debian70-amd64.local.net-space.pl>
 <20130719151243.GA15488@kroah.com>
 <20130719183235.GA12267@debian70-amd64.local.net-space.pl>
 <20130719191449.GA1882@kroah.com>
 <51E9A85D.2060206@zytor.com>
 <20130722170307.GB14451@debian70-amd64.local.net-space.pl>
 <87wqoise9d.fsf@xmission.com>
 <51ED78EE.9020903@zytor.com>
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On Mon, Jul 22, 2013 at 11:24:46AM -0700, H. Peter Anvin wrote:
> On 07/22/2013 10:20 AM, Eric W. Biederman wrote:
> >>>
> >>> Also, in any virtualized environment the hypervisor can do a better job
> >>> for things like kdump, simply because it can provide two things that are
> >>> otherwise hard to do:
> >>>
> >>> 1. a known-good system state;
> >>> 2. a known-clean kdump image.
> >>>
> >>> As such, I do encourage the virtualization people to (also) develop
> >>> hypervisor-*aware* solutions for these kinds of things.
> >>
> >> In general I agree but if you could not change hypervisor
> >> and/or dom0 (e.g. you are using cloud providers which are
> >> stick to old versions of Xen) then you have no choice.
> > 
> > Which tends to be where kexec on panic comes in most cases.  Getting
> > platform vendors to do something sane tends to be a multi-year political
> > effort of dubious worth while just solving the problem locally actually
> > gets the problem solved for those who care.
> > 
> 
> It should not be a "one or the other" issue.

I don't care about kdump, I care about kexec on domU for people who are
running on cloud providers with old versions of Xen so that they can
control what kernel they can boot, when they want to boot it.  If kdump
works as well, that's just a bonus, but it's down on the list of things
for me to be concerned about.

thanks,

greg k-h
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