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Date: Thu, 18 Jun 2009 13:37:59 +0100
From: "Richard W.M. Jones" <rjones@redhat.com>
Subject: Re: [Qemu-devel] Regression opening read-only cdroms
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To: Jamie Lokier <jamie@shareable.org>
Cc: qemu-devel <qemu-devel@nongnu.org>, Avi Kivity <avi@redhat.com>, Christoph Hellwig <hch@lst.de>

On Tue, Jun 16, 2009 at 03:33:00PM +0100, Jamie Lokier wrote:
> Avi Kivity wrote:
> > qemu used to be quite happy opening read-only cdrom images, and I was 
> > quite happy feeding kvm-autotest a library of read-only iso images.
> 
> 1. While we're here, an _option_ to open an image read-only even when
>    you have write permission would be useful, for those occasions when
>    you want to boot from some valuable image and be certain you aren't
>    modifying it - without having to chmod back and forth in
>    Qemu-wrapper scripts, or copy the image first.

FWIW we went round the houses on this one for libguestfs and settled
on using '-drive ...,snapshot=on' instead.  The guest sees the drive
as writable, and any writes are discarded when libguestfs/qemu quits.

Rich.

-- 
Richard Jones, Emerging Technologies, Red Hat  http://et.redhat.com/~rjones
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