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

Hi, Is there a dependency b/n <vcpu> and <topology> ? Is specifying <vcpu> mandatory for a SMP guest ? Can't I skip <vcpu> but have <topology sockets= cores= threads=> to define a SMP guest ? 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 ? Regards, Bharata. -- http://bharata.sulekha.com/blog/posts.htm, http://raobharata.wordpress.com/