Third time's a charm right :-)

vcpu_avail is the configuration parameter that's tripping us up on large 
SMP systems.  Instead of modifying the XML-RPC layer, a much less 
invasive solution is just to remove vcpu_avail from the S-Expression 
that's passed over the wire.  The vcpu_avail parameter is not used by xm 
so this seems like a pretty reasonable thing to do.  It certainly feels 
less hacky.

Regards,

Anthony Liguori