31.01.2022 16:59, Hanna Reitz wrote:
qemu-img convert documents the backing file and backing format options as follows: [-B backing_file [-F backing_fmt]] whereas qemu-img create has this: [-b backing_file] [-F backing_fmt]That is, for convert, we document that -F cannot be given without -B, while for create, way say that they are independent. Indeed, it is technically possible to give -F without -b, because it is left to the block driver to decide whether this is an error or not, so sometimes it is: $ qemu-img create -f qed -F qed test.qed 64M Formatting 'test.qed', fmt=qed size=67108864 backing_fmt=qed [...] And sometimes it is not: $ qemu-img create -f qcow2 -F qcow2 test.qcow2 64M Formatting 'test.qcow2', fmt=qcow2 cluster_size=65536 [...] qemu-img: test.qcow2: Backing format cannot be used without backing file Generally, it does not make much sense, though, and users should only give -F with -b, so document it that way, as we have already done for qemu-img convert (commit 1899bf47375ad40555dcdff12ba49b4b8b82df38). Reported-by: Tingting Mao<ti...@redhat.com> Signed-off-by: Hanna Reitz<hre...@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> -- Best regards, Vladimir
