On 06/26/14 14:09, Eric Blake wrote: > On 06/26/2014 05:11 AM, Laszlo Ersek wrote: >> In addition to the on-line reporting added in the previous patch, allow >> libvirt to query frontend state independently of events. >> >> Libvirt's path to identify the guest agent channel it cares about differs >> between the event added in the previous patch and the QMP response field >> added here. The event identifies the frontend device, by "id". The >> 'query-chardev' QMP command identifies the backend device (again by "id"). >> The association is under libvirt's control. >> >> RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=1080376 >> Signed-off-by: Laszlo Ersek <ler...@redhat.com> >> --- >> > >> ## >> -{ 'type': 'ChardevInfo', 'data': {'label': 'str', 'filename': 'str'} } >> +{ 'type': 'ChardevInfo', 'data': {'label': 'str', >> + 'filename': 'str', >> + 'frontend-open': 'bool'} } > > Hmm; I wonder if this should instead be > 'frontend-status':'VirtioSerialPortStatus', to reuse the type from patch > 1/2. That way, if we ever add a third state, then both the event and > the poll will be reusing the same enum values to report that state.
I expected this remark :) The difference is rooted in the fact that the event approaches the virtio-serial port status from the frontend (ie. guest) side, while the query approaches the same from the backend (ie. host, chardev) side. If I wanted to bring those in future-proof sync, then I would have to change the underlying, generic chardev machinery -- namely, the fe_open field, and everything that operates on it. I actually considered the other direction too: rather than introducing status:VirtioSerialPortStatus, just add open:bool (which was your original suggestion in your v1 review). I decided against it because the current list of enum constants (connected, disconnected) expresses just the same, and it'll be a *tiny* bit easier to extend, should that necessity arise. Sounds acceptible? :) If not, then I'm OK to replace status:VirtioSerialPortStatus with open:bool in the first patch. Thanks, Laszlo
