Eric Blake <ebl...@redhat.com> writes: > On 2/1/19 1:23 PM, Markus Armbruster wrote: > >>>>> +# @unknown-flags: any remaining flags not recognized by the current qemu >>>>> version >>>> >>>> Intended use cases for @unknown-flags? >>> >>> The qcow2 spec defines bit 2 extra_data_compatible; and also leaves the >>> door open for future extensions that may define other bits. If a new >>> version of qemu (or some non-qemu qcow2 creation app) creates an image >>> with additional feature bits set, THIS version of qemu doesn't know what >>> name to give those bits, but can still inform the user that those bits >>> are set via this field. It will be omitted for all images created by >>> this version of qemu. >> >> What would QMP clients do with this information? > > 'qemu-img info' is the intended QMP client; and it will print the > unknown-flags along with everything else. In other words, we're trying > to make qemu-img become useful for inspecting as much useful information > as possible from an image with unknown origins. Knowing that an image > uses bitmaps with flags unknown to THIS version of qemu is a good > indication that you should be careful about using/altering the image > without first upgrading qemu, as it may destroy data that some other > product desires to utilize.
Okay. Now work that into the documentation :)
