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Date: Tue, 12 Apr 2011 10:10:44 +0200
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] To O_EXCL or not to O_EXCL open host_cdrom
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To: "Daniel P. Berrange" <berrange@redhat.com>
Cc: Stefan Hajnoczi <stefanha@gmail.com>, qemu-devel <qemu-devel@nongnu.org>, Markus Armbruster <armbru@redhat.com>, Ryan Harper <ryanh@us.ibm.com>, Amit Shah <amit.shah@redhat.com>, Christoph Hellwig <hch@lst.de>

Am 12.04.2011 09:52, schrieb Daniel P. Berrange:
>  - If the -drive specification has  readonly=on (thus O_RDONLY to
>    open(2) call) , I expect QEMU (or the kernel) to forbid the
>    "eject" command on the host CDROM. This should prevent two guests
>    interfering seriously with each other.
> 
> So I think using O_EXCL would be OK, in the case where the block
> driver was  host_cdrom and readonly=off.

This would overload readonly with a completely unrelated option (should
eject be allowed). Doesn't sound like a great idea.

Kevin