[libvirt] [PATCH 1/2] conf: add crash to hyperv features

Dmitry Andreev dandreev at virtuozzo.com
Tue Nov 10 15:55:12 UTC 2015

Paolo, Jiri, can I do something more for this patch to be accepted?

On 05.11.2015 17:32, Paolo Bonzini wrote:
> On 05/11/2015 14:54, Dmitry Andreev wrote:
>>>> Add crash CPU feature for Hyper-V. Hyper-V crash MSR's can be used
>>>> by Hyper-V based guests to notify about occurred guest crash.
>>>> XML:
>>>> <features>
>>>>     <hyperv>
>>>>       <crash state='on'/>
>>>>     </hyperv>
>>>> </features>
>>> Sounds like this is related to an existing panic device we already
>>> support. So what does enabling hv_crash do in QEMU? Is it an additional
>>> channel to a panic device or is the panic device still needed even if
>>> hv_crash is enabled? In any case, I think we should map this somehow to
>>> the panic device instead of copying 1:1 the way QEMU enables hv_crash.
>> pvpanic and Hyper-V crash are independent ways for guest to notify about
>> OS crash. Both ways rise the 'qemu guest panicked' event. Domain can
>> have both hv_crash and pvpanic enabled at the same time.
>> pvpanic is in <devices> section in domain configuration because it is an
>> ISA device. Hyper-V crash is a hypervisor's feature, which enables a set
>> of model-specific registers. Guest can use this registers to send
>> notification and store additional information about a crash. This is a
>> part of Microsoft hypervisor interface.
>> That's why I think hv_crash should be in <features> section.
> I agree.
> Paolo

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