XM list Virtual Machine stateless

When executing "XM list" command, u may see this output below: [Root @ spark ~] # XM Li Name ID mem vcpus state time (s) 1-pv 1 256 1 ------ 1.5 2-pv 2 256 1 ------ 0.7 State line shows nothing, why? "I don't know why it's not progressing, but it's perfectly possible to have a state of" nothing "-it happens when the system is neither running (e.g. there's no available CPU for it) and not blocked, paused, shutdown, crashed or dying. it's just not scheduled, and it's waiting for a CPU to become available."