On Tue, Jan 23, 2018 at 11:08:31AM +0100, Andrea Bolognani wrote: > On Fri, 2018-01-19 at 15:34 +0100, Andrea Bolognani wrote: > > > > This won't solve the libvirt problem we were discussing, because it > > > > needs an existing instance of the object. libvirt wants to know the > > > > machine properties *without* instantiating an instance. > > > > > > My patch works with types, it creates an instance for a short time itself, > > > this is why it does not do a thing for "pseries" as it is not a type and > > > prints properties for the "pseries-2.12-machine" type. > > > > Yeah, I took this for a spin and can confirm that it's pretty much > > exactly what I was thinking about. The fact that the QMP command > > instantiates objects behind the scenes is not an issue, at least > > from libvirt's point of view: device-list-properties does the same > > thing and we already use it quite happily; what matters is that we > > can call this, along with all the other capabilities-collecting > > QMP commands, in one go and on a single QEMU instance. > > David, I know you're busy with linux.conf.au, but it would be > really helpful if you could carve out five minutes to look over > Alexey's proposal again, with my reply above in mind, and let us > know whether it looks a reasonable design. Doesn't have to be a > review, just a quick feedback on the high-level idea.
It looks ok, I think, but I don't think I'm really the right person to ask. I do wonder if creating a throwaway instance could cause trouble, especially for something like machine that might well have gotten away with having global side-effects in the past. I think we need to talk with someone who knows more about qom and qapi - Markus seems the obvious choice. > I'm moving forward with the libvirt implementation of pSeries > capabilities and I would have to start implementing support for > this new QMP command, well, pretty much... Right now :) But I'd > rather not start at all if I'm just going to have to scrap > everything later. Yeah, unfortunately because its part of the core infrastructure, not power specific, this isn't something I can make call on. -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson
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