Date: Tue, 13 Nov 2012 00:19:08 -0200
From: Marcelo Tosatti <mtosatti@redhat.com>
To: Sasha Levin <levinsasha928@gmail.com>
Cc: Hu Tao <hutao@cn.fujitsu.com>, Wen Congyang <wency@cn.fujitsu.com>,
        kvm list <kvm@vger.kernel.org>, qemu-devel <qemu-devel@nongnu.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Avi Kivity <avi@redhat.com>,
        "Daniel P. Berrange" <berrange@redhat.com>,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        Jan Kiszka <jan.kiszka@siemens.com>, Gleb Natapov <gleb@redhat.com>,
        Blue Swirl <blauwirbel@gmail.com>, Eric Blake <eblake@redhat.com>,
        Andrew Jones <drjones@redhat.com>,
        Luiz Capitulino <lcapitulino@redhat.com>
Subject: Re: [PATCH v11] kvm: notify host when the guest is panicked
Message-ID: <20121113021908.GA8176@amt.cnet>
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 <20121031011256.GC12325@amt.cnet>
 <50908354.5070608@cn.fujitsu.com>
 <CA+1xoqdcaeAm05_=rx3h9KHph+j7Ab8vRG_w9yUk7jtn+wHuBg@mail.gmail.com>
 <20121106015835.GA11971@localhost.localdomain>
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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.

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