On Tue, 23 Apr 2013 09:32:31 -0600 Eric Blake <ebl...@redhat.com> wrote:
> On 04/23/2013 07:20 AM, Luiz Capitulino wrote: > > On Mon, 22 Apr 2013 09:00:05 -0600 > > Eric Blake <ebl...@redhat.com> wrote: > > > >> At any rate, we really DO want introspection, and having it in 1.5 is a > >> worthwhile goal. Even if the introspection turns up empty on legacy > >> options, having it for the sake of new options is worth the effort. > > > > Agreed. But as you said in another email, we need a JSON representation > > for this command. Dumping all options as strings is just like using -help. > > > > Something else that has occurred to me is that, do we want this to be > > a QMP command or do we want this to be a command-line option? If we do this > > as a QMP command then libvirt would have to actually start QEMU just to > > query supported options. > > A command-line option might (or might not) be useful to humans, but a > QMP command is what libvirt wants. Libvirt already starts a QMP session > for lots of other queries (not the least of which is the > 'query-commands' query which would let us know whether to even expect > the new QMP command for command-line introspection to work). Adding one > more QMP query to the mix called by libvirt is easy (no additional > processes, and the response already goes through the JSON parser that > handles all QMP responses); That's right. > adding a new command line option is more > expensive (we would have to start qemu once to use the command line > option, then again for the QMP queries; also, it's more coding effort to > wire up libvirt to pass the stdout from the command line call into the > JSON parser that was normally expecting data from a Unix socket). > > > > > Another interesting point is about full schema introspection. This patch > > only supports command-line options. It would be desirable to be able to > > introspect all QAPI types and QMP commands, although I'm aware that this > > might be a lot of work to do for 1.5. > > Based on the call today, getting introspection for command line > additions in time for 1.5, and saving full QMP introspection until 1.6, > would be reasonable; libvirt's immediate goal is to determine when it is > safe to use new command line options while doing its one-shot QMP > probing of a qemu binary. Yes. All my points have been clarified in today's meeting.
