[libvirt] [PATCH 0/9] Add runnability info to query-cpu-definitions

David Hildenbrand dahi at linux.vnet.ibm.com
Mon May 9 07:24:15 UTC 2016

> This series extends query-cpu-definitions to include two extra
> fields: "runnable", and "unavailable-features".
> This will return information based on the current machine and
> accelerator only. In the future we may extend these mechanisms to
> allow querying other machines and other accelerators without
> restarting QEMU, but it will require some reorganization of
> QEMU's main code.

Hi Eduardo,

just as discussed during/after the last kvm forum offline, we are currently
working on a new set of qmp functions to keep all the cpu model details
in QEMU and not have to replicate them in libvirt and to have a nice way
to query the host cpu model.

We already have a prototype running, just need to clarify some s390x details
(feature set of the CPU generations) before we can send out an RFC. I could,
however, send out just the interface changes + details on the concept upfront,
if anybody is interested.

In the current implementation:
- s390x cpu models will be independent of the QEMU machine, so for s390x the
  runnability information will only depend on the accelerator (host cpu model).
  However, for compatibility machines, cpu models will be disabled, and we won't
  therefore have any runnability information.
- we will not touch query-cpu-definitions
- the new interfaces will also make use of the current accelerator and the
  current machine, so the context of these functions are the same.
Adding functionality to query for other machines is not necessary for s390x.
Other accelerators don't really make sense to me, let's keep it simple here.

So this change is fine from my point of view. It doesn't contradict to out


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