Kevin Wolf <kw...@redhat.com> writes: > Am 20.11.2014 um 13:44 hat Max Reitz geschrieben: >> The 'change' QMP and HMP command allows replacing the medium in drives >> which support this, e.g. floppy disk drives. For some drives, the medium >> carries information about whether it can be written to or not (again, >> floppy drives). Therefore, it should be possible to change the read-only >> state of block devices when changing the loaded medium. >> >> This series adds an optional additional parameter to the 'change' QMP >> and HMP command which allows changing the read-only state in four ways: >> >> - 'retain': Just keep the status as it was before; this is the current >> behavior and thus this will be the default. >> - 'ro': Force read-only access >> - 'rw': Force writable access >> - 'auto': This opens the new file R/W first, if that fails, the file is >> opened read-only. > > Not sure if 'auto' is worth implementing (it's a typical HMP default > action that no QMP client would use, except that it isn't even the > default for HMP), but the implementation looks correct at least.
QMP eschews magic. I'd prefer to keep 'auto' out. HMP can offer it regardless, if it's useful. But I doubt it will be. Few users will need to control this, and fewer will realize they can by giving an extra argument. I wish I could tell you to leave change alone because it's a legacy dungpile. Alas, it's still only a dungpile. I hope we can create a set of sane media control commands relatively soon now.
