linux-kernel - Re: [Xen-devel] [PATCH] x86/xen: Return from panic notifier

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Message-ID: <63155d02-1082-3f26-6c2f-76aa3b753302@suse.com>
Date:   Wed, 2 Oct 2019 16:59:16 +0200
From:   Jan Beulich <jbeulich@...e.com>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc:     james@...gwall.me.uk, xen-devel@...ts.xenproject.org,
        Juergen Gross <jgross@...e.com>, linux-kernel@...r.kernel.org
Subject: Re: [Xen-devel] [PATCH] x86/xen: Return from panic notifier

On 02.10.2019 16:14, Boris Ostrovsky wrote:
> On 10/2/19 9:42 AM, Jan Beulich wrote:
>>
>> I can only guess that the thinking probably was that e.g. external
>> dumping (by the tool stack) would be more reliable (including but
>> not limited to this meaning less change of state from when the
>> original crash reason was detected) than having the domain dump
>> itself.
> 
> 
> We could register an external dumper (controlled by a boot option
> perhaps, off by default) that will call directly into hypervisor with
> SHUTDOWN_crash. That will guarantee that we will complete the notifier
> chain without relying on priorities. (Of course this still won't address
> a possible new feature in panic() that might be called post-dumping)
> 
> If you think it's worth doing this can be easily added.

Well, I think this is the better option than potentially
pingponging between the two extremes, because one wants it the
way it currently is and another wants it the way this patch
changes things to.

Jan