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Date: Mon, 2 May 2016 10:50:58 -0700
From: Yuanhan Liu <yuanhan.liu@linux.intel.com>
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Subject: Re: [Qemu-devel] [PATCH 11/18] vhost-user: add shutdown support
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: =?iso-8859-1?Q?Marc-Andr=E9?= Lureau <marcandre.lureau@gmail.com>, QEMU <qemu-devel@nongnu.org>, Ilya Maximets <i.maximets@samsung.com>, jonshin@cisco.com, Tetsuya Mukawa <mukawa@igel.co.jp>, "Xie, Huawei" <huawei.xie@intel.com>

On Mon, May 02, 2016 at 03:04:30PM +0300, Michael S. Tsirkin wrote:
> On Mon, May 02, 2016 at 01:29:18PM +0200, Marc-André Lureau wrote:
> > Hi
> > 
> > On Mon, May 2, 2016 at 12:45 PM, Michael S. Tsirkin <mst@redhat.com> wrote:
> > > 1. Graceful disconnect
> > > - One should be able to do vmstop, disconnect, connect then vm start
> > >   This looks like a nice intermediate step.
> > > - Why would we always assume it's always remote initiating the disconnect?
> > >   Monitor commands for disconnecting seem called for.
> > 
> > Those two solutions involve VM management. This looks more complex to
> > communicate/synchronize vhost-user backend & vm management & qemu. The
> > use case I cover is request from the backend to shutdown,
> 
> Right, but flushing buffers + closing the socket looks like
> a cleaner interface than a ton of messages going back and forth.

I'd agree with Michael on that. It needs more cares when dealing with
two stream buffers: you can't quit backend soon after the shutdown
request, instead, you have to wait for the ACK from QEMU. Making request
from QEMU avoids that.

	--yliu