On 13.04.2017 23:17, Eric Blake wrote: > On 04/13/2017 03:34 PM, Max Reitz wrote: >> It does not make much sense to use a backing image for the target when >> you concatenate multiple images (because then there is no correspondence >> between the source images' backing files and the target's); but it was >> still possible to give one by using -o backing_file=X instead of -B X. >> >> Fix this by moving the check. >> >> (Also, change the error message because -B is not the only way to >> specify the backing file, evidently.) > > For that matter, 'create -B' is intentionally? undocumented in the > qemu-img --help and man page. (Personally, I don't know why we don't > want it documented - is it because it it not a universal option because > not all formats support backing files?)
(I suppose you mean convert instead of create) Well, the man page at least documents that you can use backing_file for the destination and what it will do. So documenting would probably be just "Oh, you can also use -B, by the way." I won't promise to write a patch to fix that, but I do hope I will. :-) >> Cc: qemu-stable <qemu-sta...@nongnu.org> >> Signed-off-by: Max Reitz <mre...@redhat.com> >> --- >> qemu-img.c | 14 +++++++------- >> tests/qemu-iotests/122.out | 4 ++-- >> 2 files changed, 9 insertions(+), 9 deletions(-) >> > > Reviewed-by: Eric Blake <ebl...@redhat.com> Thanks, as always! Max > Having a backing file for the destination may still make sense for some > convoluted workflow, but you can get that with a followup qemu-img rebase.
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