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Date: Tue, 13 Nov 2012 00:19:08 -0200
From: Marcelo Tosatti <mtosatti@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v11] kvm: notify host when the guest is
	panicked
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To: Sasha Levin <levinsasha928@gmail.com>
Cc: Andrew Jones <drjones@redhat.com>, kvm list <kvm@vger.kernel.org>, Hu Tao <hutao@cn.fujitsu.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Gleb Natapov <gleb@redhat.com>, qemu-devel <qemu-devel@nongnu.org>, Blue Swirl <blauwirbel@gmail.com>, Avi Kivity <avi@redhat.com>, Jan Kiszka <jan.kiszka@siemens.com>, Luiz Capitulino <lcapitulino@redhat.com>, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

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.
Now, the following comments have still not been addressed:

1) Lifecycle of the stopped guest and interaction with other stopped
states in QEMU.

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.