Re: [libvirt] [PATCH 2/2] util: storage: add JSON backing volume parser 'raw' block driver

Hi, On Tue, 14 Feb 2017 15:58:45 +0000 "Richard W.M. Jones" <rjones(a)redhat.com&gt; wrote: > The patches compile. > > I looked at both commits and they at least superficially seem > sensible. I'm not intimately familiar enough with the original code > to review this fully. > > However I want to try to test this using libguestfs. I believe the > following test case should be sufficient: > > $ cd /var/tmp > $ truncate -s 1M backing.img > $ qemu-img create \ > -b 'json:{"driver":"raw", "file":{"filename":"/var/tmp/backing.img"}}' \ The problem lies in the JSON here. Libvirt lacks the driver probing mechanism QEMU has (which makes sense). That means one has to be explicit about the drivers. Try with the following backing definition: json:{"driver":"raw", "file":{ "driver":"file", "filename":"/var/tmp/backing.img"}}