diff -Nura xen-unstable.orig/tools/examples/xend-config.sxp xen-unstable/tools/examples/xend-config.sxp
--- xen-unstable.orig/tools/examples/xend-config.sxp	2008-08-06 17:26:37.000000000 +0800
+++ xen-unstable/tools/examples/xend-config.sxp	2008-08-06 17:28:45.000000000 +0800
@@ -63,6 +63,12 @@
 
 #(xend-unix-path /var/lib/xend/xend-socket)
 
+# External locking utility for get/release domain running lock. By default,
+# no utility is specified. Thus there will be no lock as VM running.
+# The locking utility should accept:
+# <--lock | --unlock> --name <name> --uuid <uuid>
+# command line options, and returns zero on success, others on error.
+#(xend-domains-lock-path '')
 
 # Address and port xend should use for the legacy TCP XMLRPC interface, 
 # if xend-tcp-xmlrpc-server is set.
diff -Nura xen-unstable.orig/tools/python/xen/xend/XendDomainInfo.py xen-unstable/tools/python/xen/xend/XendDomainInfo.py
--- xen-unstable.orig/tools/python/xen/xend/XendDomainInfo.py	2008-08-06 17:26:39.000000000 +0800
+++ xen-unstable/tools/python/xen/xend/XendDomainInfo.py	2008-08-06 17:31:27.000000000 +0800
@@ -328,6 +328,8 @@
     @type state_updated: threading.Condition
     @ivar refresh_shutdown_lock: lock for polling shutdown state
     @type refresh_shutdown_lock: threading.Condition
+    @ivar running_lock: lock for running VM
+    @type running_lock: bool or None
     @ivar _deviceControllers: device controller cache for this domain
     @type _deviceControllers: dict 'string' to DevControllers
     """
@@ -395,6 +397,8 @@
         self.refresh_shutdown_lock = threading.Condition()
         self._stateSet(DOM_STATE_HALTED)
 
+        self.running_lock = None
+
         self._deviceControllers = {}
 
         for state in DOM_STATES_OLD:
@@ -421,6 +425,7 @@
 
         if self._stateGet() in (XEN_API_VM_POWER_STATE_HALTED, XEN_API_VM_POWER_STATE_SUSPENDED, XEN_API_VM_POWER_STATE_CRASHED):
             try:
+                self.acquire_running_lock();
                 XendTask.log_progress(0, 30, self._constructDomain)
                 XendTask.log_progress(31, 60, self._initDomain)
                 
@@ -453,6 +458,7 @@
         state = self._stateGet()
         if state in (DOM_STATE_SUSPENDED, DOM_STATE_HALTED):
             try:
+                self.acquire_running_lock();
                 self._constructDomain()
                 self._storeVmDetails()
                 self._createDevices()
@@ -2292,6 +2298,11 @@
 
             self._stateSet(DOM_STATE_HALTED)
             self.domid = None  # Do not push into _stateSet()!
+      
+            try:
+                self.release_running_lock()
+            except:
+                log.exception("Release running lock failed: %s" % status)
         finally:
             self.refresh_shutdown_lock.release()
 
@@ -3520,6 +3531,28 @@
     def has_device(self, dev_class, dev_uuid):
         return (dev_uuid in self.info['%s_refs' % dev_class.lower()])
 
+    def acquire_running_lock(self):
+        if not self.running_lock:
+            lock_path = xoptions.get_xend_domains_lock_path()
+            if lock_path:
+                status = os.system('%s --lock --name %s --uuid %s' % \
+                                   (lock_path, self.info['name_label'], self.info['uuid']))
+                if status == 0:
+                    self.running_lock = True
+                else:
+                    raise XendError('Acquire running lock failed: %s' % status)
+
+    def release_running_lock(self):
+        if self.running_lock:
+            lock_path = xoptions.get_xend_domains_lock_path()
+            if lock_path:
+                status = os.system('%s --unlock --name %s --uuid %s' % \
+                                   (lock_path, self.info['name_label'], self.info['uuid']))
+                if status == 0:
+                    self.running_lock = False
+                else:
+                    raise XendError('Release running lock failed: %s' % status)
+
     def __str__(self):
         return '<domain id=%s name=%s memory=%s state=%s>' % \
                (str(self.domid), self.info['name_label'],
diff -Nura xen-unstable.orig/tools/python/xen/xend/XendDomain.py xen-unstable/tools/python/xen/xend/XendDomain.py
--- xen-unstable.orig/tools/python/xen/xend/XendDomain.py	2008-08-06 17:26:39.000000000 +0800
+++ xen-unstable/tools/python/xen/xend/XendDomain.py	2008-08-06 17:30:23.000000000 +0800
@@ -1295,6 +1295,7 @@
                              POWER_STATE_NAMES[dominfo._stateGet()])
 
         """ The following call may raise a XendError exception """
+        dominfo.release_running_lock();
         dominfo.testMigrateDevices(True, dst)
 
         if live:
diff -Nura xen-unstable.orig/tools/python/xen/xend/XendOptions.py xen-unstable/tools/python/xen/xend/XendOptions.py
--- xen-unstable.orig/tools/python/xen/xend/XendOptions.py	2008-08-06 17:26:39.000000000 +0800
+++ xen-unstable/tools/python/xen/xend/XendOptions.py	2008-08-06 17:28:45.000000000 +0800
@@ -271,6 +271,11 @@
         """
         return self.get_config_string("xend-domains-path", self.xend_domains_path_default)
 
+    def get_xend_domains_lock_path(self):
+        """ Get the path of the lock utility for running domains.
+        """
+        return self.get_config_string("xend-domains-lock-path")
+
     def get_xend_state_path(self):
         """ Get the path for persistent domain configuration storage
         """