On Thu, 2016-01-14 at 11:31 -0700, Jim Fehlig wrote: > Ian Campbell wrote: > > On Mon, 2016-01-11 at 10:00 -0700, Jim Fehlig wrote: > > > On 01/07/2016 10:13 AM, Ian Campbell wrote: > > > > On Tue, 2015-12-22 at 18:44 +0000, Ian Jackson wrote: > > > > > This allows code elsewhere in libxl to find out what options a > > > > > device > > > > > model executable supports. This is done by searching the usage > > > > > message for fixed strings. > > > > Has anyone (ever, not necessarily a Xen person nor in this context) > > > > approached upstream QEMU about a machine readable output of some > > > > sort? > > > > > > > > I know libvirt does something similar to this, but they want to > > > > support > > > > older versions, whereas we at least have the luxury of not caring > > > > about > > > > versions before the point this code lands. > > > Since qemu 1.2.0, libvirt has been using the various QMP commands to > > > probe for > > > qemu capabilities, instead of parsing help output. > > > > As in it spawns a qemu specifically to ask the questions and then kills > > it > > and starts what it needs _or_ it starts the qemu with minimal command > > line > > cfg and then dynamically pokes in the full config via qmp? > > The latter.
From the description I think you meant former? > When the qemu driver loads, it starts qemu, pokes it for > capabilities via qmp, caches what it finds, then terminates it. The cached > capabilities are used until the associated qemu binary is changed/updated. > > If interested in peeking at the code, see virQEMUCapsInitQMP() and the > functions > it calls in $libvirt_src/src/qemu/qemu_capabilities.c. E.g. > > virQEMUCapsInitQMP() > -> virQEMUCapsInitQMPMonitor() > -> virQEMUCapsInitQMPBasic() Thanks. When I spoke to Ian J yesterday we decided doing this properly (via QMP as above) would be nice it was out of scope for this series for now. It would make a nice future bit of cleanup though for sure. Ian. > > Regards, > Jim > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
