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

On 11/10/2015 06:55 PM, Dmitry Andreev wrote: > 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 > Please. This feature is very interesting for us for guest debugging especially during guest installation where specific drivers are not available or not ready or not that easy to supply.