Re: [Qemu-devel] [PATCH] qcow2: Allow qcow2 disk images with size zero

[Stefan Weil <weil@mail.berlios.de>]

Kevin Wolf schrieb:
> Am 27.10.2009 15:11, schrieb Anthony Liguori:
>   
>> Stefan Weil wrote:
>>     
>>> Images with disk size 0 may be used for
>>> VM snapshots, but not to save normal block data.
>>>
>>> It is possible to create such images using
>>> qemu-img, but opening them later fails.
>>>
>>> So even "qemu-img info image.qcow2" is not
>>> possible for an image created with
>>> "qemu-img create -f qcow2 image.qcow2 0".
>>>
>>> This is fixed here.
>>>
>>> Signed-off-by: Stefan Weil <weil@mail.berlios.de>
>>>   
>>>       
>> What do you think Kevin?
>>     
>
> That with malloc instead of qemu_malloc the patch would have been a bit
> smaller. ;-) I think it can make sense to have such images in some cases
> (although a 64k image isn't much worse) and I don't see any obvious
> problem with the patch. Not sure how guests like 0 byte disks, but I
> assume Stefan has tested that.
>
> I'm just wondering how Stefan did create his test image - with current
> qemu-img I can't create such images, so I needed to patch it first. For
> this one I'll send a fix.
>
> Kevin
>   

Hi Kevin,

obviously, I called an old version of qemu-img to create the test image
(from debian's qemu package).

Regards
Stefan