Suspend/Pause not supported for libvirt

I use 2011.2~gamma2~bzr984-0ubuntu0ppa1~lucid1.

The suspend and pause commands are not supported by libvirt.

And when I try to use suspend or pause commands with OpenStack API, no message error are reported by the API but in nova-compute log, I can see the reason :

2011-04-14 10:55:23,289 DEBUG nova.rpc [-] received {u'_context_request_id': u'3IC9IU7K9O39RO4BBF1-', u'_context_read_deleted': False, u'args': {u'instance_i
d': u'1'}, u'_context_is_admin': None, u'_context_timestamp': u'2011-04-14T08:55:23Z', u'_context_user': u'user1', u'method': u'suspend_instance', u'_context
_project': u'simple', u'_context_remote_address': None} from (pid=1511) _receive /usr/lib/pymodules/python2.6/nova/rpc.py:167
2011-04-14 10:55:23,290 DEBUG nova.rpc [-] unpacked context: {'timestamp': u'2011-04-14T08:55:23Z', 'remote_address': None, 'project': u'simple', 'is_admin':
 None, 'user': u'user1', 'request_id': u'3IC9IU7K9O39RO4BBF1-', 'read_deleted': False} from (pid=1511) _unpack_context /usr/lib/pymodules/python2.6/nova/rpc.
py:331
2011-04-14 10:55:23,382 INFO nova.compute.manager [3IC9IU7K9O39RO4BBF1- user1 simple] check_instance_lock: decorating: |<function suspend_instance at 0x22af1
b8>|
2011-04-14 10:55:23,383 INFO nova.compute.manager [3IC9IU7K9O39RO4BBF1- user1 simple] check_instance_lock: arguments: |<nova.compute.manager.ComputeManager o
bject at 0x21a7410>| |<nova.context.RequestContext object at 0x3622650>| |1|
2011-04-14 10:55:23,383 DEBUG nova.compute.manager [3IC9IU7K9O39RO4BBF1- user1 simple] instance 1: getting locked state from (pid=1511) get_lock /usr/lib/pym
odules/python2.6/nova/compute/manager.py:680
2011-04-14 10:55:23,437 INFO nova.compute.manager [3IC9IU7K9O39RO4BBF1- user1 simple] check_instance_lock: locked: |False|
2011-04-14 10:55:23,438 INFO nova.compute.manager [3IC9IU7K9O39RO4BBF1- user1 simple] check_instance_lock: admin: |None|
2011-04-14 10:55:23,438 INFO nova.compute.manager [3IC9IU7K9O39RO4BBF1- user1 simple] check_instance_lock: executing: |<function suspend_instance at 0x22af1b
8>|
2011-04-14 10:55:23,494 AUDIT nova.compute.manager [3IC9IU7K9O39RO4BBF1- user1 simple] instance 1: suspending
2011-04-14 10:55:23,555 ERROR nova [-] Exception during message handling
(nova): TRACE: Traceback (most recent call last):
(nova): TRACE: File "/usr/lib/pymodules/python2.6/nova/rpc.py", line 188, in _receive
(nova): TRACE: rval = node_func(context=ctxt, **node_args)
(nova): TRACE: File "/usr/lib/pymodules/python2.6/nova/exception.py", line 120, in _wrap
(nova): TRACE: return f(*args, **kw)
(nova): TRACE: File "/usr/lib/pymodules/python2.6/nova/compute/manager.py", line 105, in decorated_function
(nova): TRACE: function(self, context, instance_id, *args, **kwargs)
(nova): TRACE: File "/usr/lib/pymodules/python2.6/nova/compute/manager.py", line 624, in suspend_instance
(nova): TRACE: lambda result: self._update_state_callback(self,
(nova): TRACE: File "/usr/lib/pymodules/python2.6/nova/exception.py", line 120, in _wrap
(nova): TRACE: return f(*args, **kw)
(nova): TRACE: File "/usr/lib/pymodules/python2.6/nova/virt/libvirt_conn.py", line 556, in suspend
(nova): TRACE: raise exception.ApiError("suspend not supported for libvirt")
(nova): TRACE: ApiError: ApiError: suspend not supported for libvirt
(nova): TRACE:
2011-04-14 10:56:05,568 INFO nova.compute.manager [-] DB/VM state mismatch. Changing state from '0' to '1'

So libvirt cannot Resume/pause instance and the instance continuous to running correctly.