Am 14.06.2012 16:06, schrieb Dong Xu Wang: > On Thu, Jun 14, 2012 at 6:51 PM, Kevin Wolf <kw...@redhat.com> wrote: >> Am 13.06.2012 16:36, schrieb Dong Xu Wang: >>> add-cow file can't live alone, must together will image_file and >>> backing_file. >>> If we implement qemu-img convert operation for add-cow file format, we must >>> create image_file and backing_file manually, that will be confused for >>> users, >>> so we just ignore add-cow format while doing converting. >>> >>> Signed-off-by: Dong Xu Wang <wdon...@linux.vnet.ibm.com> >> >> NACK. >> >> This stupid "let's drop the feature, it might confuse users" attitude is >> known from Gnome, but not from qemu. >> >> There's no technical reason to forbid it and anyone who manages to >> create a valid add-cow image will also be able to specify the very same >> options to a convert command. Also, having image format specific code in >> qemu-img is evil. >> > > If I implement add-cow convert command, I am wondering which method should > I use: > 1) create add-cow, and its backing_file, and its image_file, then we > need 3 files. > 2) create add-cow(with all bitmap marked to allocated), and its > image_file, then we > need 2 files. > > 2) will be easier, I should let .add-cow file can live only with > image_file, without backing_file. > > I think both 1) and 2) need add code to qemu-img.c. Or I will have to create > image_file automaticly in add_cow_create function. > > Can you give some comments on how to implement convert? Thanks.
Just leave it alone and it will work. qemu-img convert takes the same options as qemu-img create. So like for any other image you specify the backing file with -b or -o backing_file, and for add-cow images to be successfully created you also need to specify -o image_file. Kevin
