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

[Paolo Bonzini]

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