On Thu, Sep 29, 2016 at 10:43:37AM +0100, Daniel P. Berrange wrote: > On Thu, Sep 29, 2016 at 11:17:52AM +0200, Kevin Wolf wrote:
[...] > > Just to clarify what "not stable" means: Literally none of the > > blockdev-add commands that used to work when it was originally merged > > are still working. And we're considering another similar change > > (removing the "options" indirection) that will change the command for > > all users. So while I would encourage libvirt to write prototyp code for > > supporting blockdev-add now, I would advise against enabling it in a > > release yet. > > Urgh, arbitrarily changing behaviour of existing commands is really > very bad for libvirt, as it means we have to now write special case > logic to detect whether we can use the command or not, instead of > merely detecting whether it exists. > > If commands are expected to change, they should have an 'x-' prefix > and once that's removed they should never be changed in an incompatible > manner again. I too wondered about the "x-" prefix for 'blockdev-add' when I was digging into the details a month ago. I came to the conclusion that it was just an inadvertant mistake that it wasn't marked as such -- because, you could see the experimental prefix for rest of them commands: x-blockdev-change x-blockdev-del, x-blockdev-insert-medium, x-blockdev-remove-medium -- /kashyap
