Am 28.02.2024 um 12:30 hat Daniel P. Berrangé geschrieben: > On Wed, Feb 28, 2024 at 11:17:37AM +0100, Kevin Wolf wrote: > > Until now, @size has been mandatory for creating images with every > > driver. Maybe we should even have put it into BlockdevCreateOptions's > > base, because without a size, you're not really creating an image. > > NB, @size isn't mandatory for creating images. It isn't required > when creating qcow2 files with backing stores, as the size is > acquired from the backing file instead. > > $ qemu-img create demo.raw 1g > Formatting 'demo.raw', fmt=raw size=1073741824 > $ qemu-img create -o backing_file=demo.raw -o backing_fmt=raw -f qcow2 > demo.qcow2 > Formatting 'demo.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off > compression_type=zlib size=1073741824 backing_file=demo.raw backing_fmt=raw > lazy_refcounts=off refcount_bits=16
Yes, 'qemu-img create' is different, it adds some convenience magic like this. But for 'blockdev-create', it's mandatory for every driver. I double checked the QAPI schema. Kevin
