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Date: Tue, 30 Mar 2010 14:49:20 +0200
From: Kevin Wolf <kwolf@redhat.com>
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Subject: [Qemu-devel] Re: qemu-img help missing backing file
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To: Alexander Graf <agraf@suse.de>
Cc: qemu-devel Developers <qemu-devel@nongnu.org>

Am 30.03.2010 14:32, schrieb Alexander Graf:
> 
> On 30.03.2010, at 14:30, Kevin Wolf wrote:
> 
>> Am 30.03.2010 14:22, schrieb Alexander Graf:
>>> Howdy,
>>>
>>> I just wanted to create a backed qcow2 image and was irritated by qemu-img not showing me the correct command line option. It's just missing from the list:
>> [...]
>>> Is this intentional? The actual command still works:
>>>
>>>> agraf@s390t27:~/git/qemu> qemu-img-kvm create -f qcow2 -b /media/studio/images/SUSE/s390/sles11.raw /dev/shm/sles11-zipl.qcow2
>>>> Formatting '/dev/shm/sles11-zipl.qcow2', fmt=qcow2 size=21474836480 backing_file='/media/studio/images/SUSE/s390/sles11.raw' encryption=off cluster_size=0 
>>
>> -b still works to maintain compatibility with older versions. The
>> documented way is -o backing_file=foo (the qemu-img output you quote
>> even contains this option).
> 
> Interesting O_o. Maybe it'd be a good idea to give some examples in the help output? The same way the -e and -b options were having examples there too. That really makes them easier to find.

Feel free to submit a patch. ;-)

Examples sound like an easy way to make these features more visible
again. Even better, but a bit more work, would be to include a
dynamically generated list of all supported options like this:

backing_file: File name of a base image (qcow, qcow2, vmdk)
backing_fmt:  Image format of the base image (qcow2)
encryption:   Encrypt the image (qcow, qcow2)

Kevin