On Mon, Apr 22, 2013 at 17:38:23 +0800, Li Zhang wrote:
On 2013年04月22日 17:10, Jiri Denemark wrote:
If you want to add powernv feature just because you need to distinguish if the host supports KVM or not, there's much better way... In guest section of capabilities XML, KVM support is indicated by <domain type='kvm'> element. And that's what existing apps already use to detect KVM presence/absence.
As my understanding, there is still some difference from 'kvm' capability. 'powernv' is only considered as one CPU feature of PPC64. If other PPC platforms support KVM in the future, this feature can be used to identify whether migration can be executed . :)
Well, as I already said, unless there is a way to explicitly enable/disable powernv feature in guest CPU, I don't see any reason for exposing the feature to users/apps. We definitely don't want apps/users to detect support for migration (or anything else) by checking host CPU features. If migration is not supported, then any migration API can fail with VIR_ERR_OPERATION_UNSUPPORTED. That said, powernv feature can be used internally by libvirt to check if some configurations/operations are supported but it doesn't have to be exposed to users/apps. The CPU driver stuff is there for configuring *guest* CPU. Jirka