Am 21.05.2012 15:59, schrieb Richard W.M. Jones: > On Mon, May 21, 2012 at 03:29:22PM +0200, Kevin Wolf wrote: >> Am 17.05.2012 17:34, schrieb Richard W.M. Jones: >>> From: "Richard W.M. Jones" <rjo...@redhat.com> >>> >>> This produces a qcow2 file which is the difference between >>> two disk images. ie, if: >>> >>> base.img - is a disk image (in any format) >>> modified.img - is base.img, copied and modified >>> >>> then: >>> >>> qemu-img diff -b base.img modified.img diff.qcow2 >>> >>> creates 'diff.qcow2' which contains the differences between 'base.img' >>> and 'modified.img'. Note that 'diff.qcow2' has 'base.img' as its >>> backing file. >>> >>> Signed-off-by: Richard W.M. Jones <rjo...@redhat.com> >>> Cc: Matthew Booth <mbo...@redhat.com> >>> Cc: Pablo Iranzo Gómez <pablo.ira...@redhat.com> >>> Cc: Tomas Von Veschler <tvv...@redhat.com> >> >> Hm, I'm wondering... If I have a command line like this: >> >> qemu-img diff -b base.img modified.img diff.qcow2 >> >> Would this be equivalent to this sequence? >> >> qemu-img create -f qcow2 -b modified.img diff.qcow2 >> qemu-img rebase -b base.img diff.qcow2 >> >> Or is there some detail that I'm missing? If it is equivalent, this >> would suggest that either the new command isn't necessary at all or at >> least that it should reuse the qemu-img rebase code. > > Yes. I tried for a while to work out the sequence of commands that > could make a diff using 'qemu-img rebase', but it wasn't obvious and I > gave up. It should at least be documented. How about the attached > patch?
Looks good to me. As it already has a SoB, I've applied it to the block branch. Let me know if I should dequeue it again. Kevin
