Re: [libvirt] [PATCH 1/2] conf: add crash to hyperv features
On 05.11.2015 14:06, Jiri Denemark wrote:
On Mon, Oct 26, 2015 at 13:23:32 +0300, 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.
Just to make it clear, NACK until the design is sorted out.
Jirka
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