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Date: Mon, 11 Apr 2011 16:30:13 +0300
From: Avi Kivity <avi@redhat.com>
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Subject: Re: [Qemu-devel] Re: To O_EXCL or not to O_EXCL open host_cdrom
References: <BANLkTin3+Hz2kmLnVTDrLyzQUs-Ksvvc0w@mail.gmail.com>	<20110411050732.GA7523@amit-x200.redhat.com>
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To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Markus Armbruster <armbru@redhat.com>, qemu-devel <qemu-devel@nongnu.org>, Ryan Harper <ryanh@us.ibm.com>, Amit Shah <amit.shah@redhat.com>, Christoph Hellwig <hch@lst.de>

On 04/11/2011 11:31 AM, Stefan Hajnoczi wrote:
> On Mon, Apr 11, 2011 at 10:37:32AM +0530, Amit Shah wrote:
> >  On (Fri) 08 Apr 2011 [12:33:27], Stefan Hajnoczi wrote:
> >  >  The other concern I have about using O_EXCL is that we expose
> >  >  ourselves to race conditions if there is ever a need to re-open the
> >  >  device.  When QEMU closes its file descriptor another program may be
> >  >  scheduled to run and open the device with O_EXCL.  Now QEMU will not
> >  >  be able to open the CD-ROM anymore.
> >
> >  The admins should really be the ones worrying about this, not QEMU.
>
> Think of a desktop use case.  virt-manager lets me pass through the host
> CD-ROM today.  Desktops have hald/udisks and you can't expect users to
> disable/reenable those services just for QEMU.

It should be solved at that level then.  If I insert a disc into an 
assigned cd-rom drive, I shouldn't get a file manager or autorun window 
to pop in the host, just the guest.

So: libvirt should inform the rest of the system that it is taking over 
the cd-rom and as far as they're concerned, it no longer exists.

-- 
error compiling committee.c: too many arguments to function