Re: [Qemu-devel] [PATCH v11] kvm: notify host when the guest is panicked

[Hu Tao <hutao@cn.fujitsu.com>]

Hi Marcelo,

On Tue, Nov 13, 2012 at 12:19:08AM -0200, Marcelo Tosatti wrote:
> On Fri, Nov 09, 2012 at 03:17:39PM -0500, Sasha Levin wrote:
> > On Mon, Nov 5, 2012 at 8:58 PM, Hu Tao <hutao@cn.fujitsu.com> wrote:
> > > But in the case of panic notification, more dependency means more
> > > chances of failure of panic notification. Say, if we use a virtio device
> > > to do panic notification, then we will fail if: virtio itself has
> > > problems, virtio for some reason can't be deployed(neither built-in or
> > > as a module), or guest doesn't support virtio, etc.
> > 
> > Add polling to your virtio device. If it didn't notify of a panic but
> > taking more than 20 sec to answer your poll request you can assume
> > it's dead.
> > 
> > Actually, just use virtio-serial and something in userspace on the guest.
> 
> They want the guest to stop, so a memory dump can be taken by management
> interface.
> 
> Hu Tao, lets assume port I/O is the preferred method for communication.

Okey.

> Now, the following comments have still not been addressed:
> 
> 1) Lifecycle of the stopped guest and interaction with other stopped
> states in QEMU.

Patch 3 already deals with run state transitions. But in case I'm
missing something, could you be more specific?

> 
> 2) Format of the interface for other architectures (you can choose
> a different KVM supported architecture and write an example).
> 
> 3) Clear/documented management interface for the feature.

It is documented in patch 0: Documentation/virtual/kvm/pv_event.txt.
Does it need to be improved?