Re: [Xen-devel] [PATCH 2/2] Allow kdump with crash_kexec_post_notifiers

["Jan Beulich" <JBeulich@xxxxxxxx>]

(re-adding xen-devel)

>>> On 01.08.16 at 15:02, <PTesarik@xxxxxxxx> wrote:
> On Mon, 1 Aug 2016 13:55:01 +0200
> "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
> 
>> >>> On 13.07.16 at 14:53, <david.vrabel@xxxxxxxxxx> wrote:
>> > On 13/07/16 13:20, Petr Tesarik wrote:
>> >> If a crash kernel is loaded, do not crash the running domain. This is
>> >> needed if the kernel is loaded with crash_kexec_post_notifiers, because
>> >> panic notifiers are run before __crash_kexec() in that case, and this
>> >> Xen hook prevents its being called later.
>> > 
>> > Prioritising the in-kernel kexec image over the hypervisor one seems
>> > sensible behaviour to me.
>> 
>> For HVM guests certainly; does loading of an in-kernel crash kernel
>> properly fail for PV guests (and namely PV Dom0), or does such a
>> setup work nowadays?
> 
> This is a good question, but I don't think it is relevant to this
> patch. It does not change anything unless the kernel is booted with
> crash_kexec_post_notifiers.
> 
> I fully understand that Dom0 kernels want to load the panic kernel in
> the hypervisor and crash the complete machine, rather than just Dom0,
> but if you want that behaviour, simply pass the "crashkernel="
> parameter only to the Xen hypervisor and not to the Dom0 kernel.
> 
> Did I miss something?

For one there are still many people who, for varying reasons, add
"crashkernel=" also to Dom0's command line.

And then trying to invoke a locally loaded crash kernel which won't
work is bad - you really want the domain to be reported crashed
instead in such a case, to avoid further obfuscating whatever issue
had been encountered originally.

Jan


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