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.