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Date: Wed, 17 Jun 2015 10:35:39 +0200
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] [Qemu-block] RFC cdrom in own thread?
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To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Peter Lieven <pl@kamp.de>, qemu-devel <qemu-devel@nongnu.org>, qemu block <qemu-block@nongnu.org>

Am 16.06.2015 um 17:34 hat Stefan Hajnoczi geschrieben:
> On Tue, Jun 16, 2015 at 3:44 PM, Peter Lieven <pl@kamp.de> wrote:
> > I wonder how difficult it would be to have the IDE CDROM run in its own
> > thread?
> > We usually have ISOs mounted on an NFS share as CDROM. Problem: If the NFS
> > Share
> > goes down, it takes down monitor, qmp, vnc etc. with it.
> >
> > Maybe its already possible to do this via cmdline args?
> >
> > Any ideas, comments?
> 
> If QEMU hangs in the read/write/flush/discard code path due to NFS
> downtime it is a bug.
> 
> QEMU is expected to hang in open/reopen because those are performed in
> a blocking fashion.
> 
> Which of these cases applies to what you are seeing?  Maybe it can be fixed.

Don't forget bdrv_drain_all(), which is called a lot by the monitor. So
no matter what you do (and this includes moving to a thread as in a
hypothetical "ATAPI dataplane"), you end up with a hang sooner or later.

Kevin