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

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