On Mon, Mar 09, 2020 at 10:42:25AM -0500, Eric Blake wrote: [...] > > > +qemu-img backing file without format (since 5.0.0) > > > +'''''''''''''''''''''''''''''''''''''''''''''''''' > > > + > > > +The use of ``qemu-img create``, ``qemu-img rebase``, ``qemu-img > > > +convert``, or ``qemu-img amend`` to create or modify an image that > > > +depends on a backing file now recommends that an explicit backing > > > +format be provided. Also for the `qemu-img amend` case, I'm not clear if the following scenario ought to throw the warning: $> ~/build/qemu/qemu-img info --backing-chain overlay1.qcow2 image: overlay1.qcow2 file format: qcow2 virtual size: 4 GiB (4294967296 bytes) disk size: 196 KiB cluster_size: 65536 backing file: base.raw Format specific information: compat: 1.1 lazy refcounts: false refcount bits: 16 corrupt: false image: base.raw file format: raw virtual size: 4 GiB (4294967296 bytes) disk size: 778 MiB $> ~/build/qemu/qemu-img amend -o compat=v3 overlay1.qcow2 $> echo $? 0 I'm just trying to work out the scenarios where the warnings ought to show up (for all the four cases: create, rebase, convert, amend). [...] -- /kashyap