[libvirt] Dependency between <vcpu> and <topology>

Eric Blake eblake at redhat.com
Fri Sep 16 14:25:24 UTC 2011

On 09/15/2011 11:50 PM, Bharata B Rao wrote:
> Hi,
> Is there a dependency b/n<vcpu>  and<topology>  ?

There should be, but isn't yet.

> Is specifying<vcpu>  mandatory for a SMP guest ?


> Can't I skip<vcpu>  but have<topology sockets= cores= threads=>  to
> define a SMP guest ?

It should be possible, but isn't yet.

> I see that if I skip<vcpu>, libvirt generates -smp 1 on qemu command
> line which results in qemu booting a VM with single CPU irrespective
> of the topology specified. Shouldn't libvirt arrive at correct CPU
> count (vcpus=sockets*cores*threads ?) even if vcpu isn't specified
> rather than defaulting to 1 ?

See also these bugs:

Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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