Re: [Qemu-devel] [PATCH] kvm: notify host when guest paniced

[Gleb Natapov]

On Wed, Feb 29, 2012 at 11:49:58AM +0200, Avi Kivity wrote:
> On 02/29/2012 03:29 AM, Wen Congyang wrote:
> > At 02/28/2012 07:23 PM, Avi Kivity Wrote:
> > > On 02/27/2012 05:01 AM, Wen Congyang wrote:
> > >> We can know the guest is paniced when the guest runs on xen.
> > >> But we do not have such feature on kvm. This patch implemnts
> > >> this feature, and the implementation is the same as xen:
> > >> register panic notifier, and call hypercall when the guest
> > >> is paniced.
> > > 
> > > What's the motivation for this?  "Xen does this" is insufficient.
> >
> > Another purpose is: management app(for example: libvirt) can do auto
> > dump when the guest is crashed. If management app does not do auto
> > dump, the guest's user can do dump by hand if he sees the guest is
> > paniced.
> >
> > I am thinking about another status: dumping. This status tells
> > the guest's user that the guest is paniced, and the OS's dump function
> > is working.
> >
> > These two status can tell the guest's user whether the guest is pancied,
> > and what should he do if the guest is paniced.
> >
> 
> How about using a virtio-serial channel for this?  You can transfer any
> amount of information (including the dump itself).
> 
Isn't it unreliable after the guest panicked? Having special kdump
kernel that transfers dump to a host via virtio-serial channel though
sounds interesting. May be that's what you mean.

--
                        Gleb.