On Wed, 07/17 14:36, Paolo Bonzini wrote: > Il 17/07/2013 11:42, Fam Zheng ha scritto: > > This option allows overriding backing hd of drive. If the target drive > > exists, it's referenced as the backing file and refcount incremented. > > > > Example: > > qemu-system-x86_64 -drive \ > > file.filename=foo.qcow2,if=none,id=foo \ > > -drive file=bar.qcow2,backing=foo > > I guess this is where we need the soft reference. > > This has a _lot_ of potential for misuse, I think Kevin bashed me and > Federico very heavily when we tried to do something similar. > > block/backup.c is the right place where we can override the backing hd > of the drive. Perhaps we can add a way to open a file with > BDRV_O_NO_BACKING from the command line.
OK. If we get the override in block/backup.c, the only thing we need is naming the target so we can add it to nbd server. If refcounting, overriding backing with option and blockdev-backup are still good to have, I can split them and targeting to future releases. -- Fam
