[qemu] Add vncunused option.

If the port used for the requested display number is in use, try
additional ports until a free port is found.

Signed-off-by: Christian Limpach <Christian.Limpach@xensource.com>

tools/python/xen/xend/image.py

@@ -307,6 +307,7 @@ class HVMImageHandler(ImageHandler):
         vnc = sxp.child_value(config, 'vnc')
         vncdisplay = sxp.child_value(config, 'vncdisplay',
                                      int(self.vm.getDomid()))
+        vncunused = sxp.child_value(config, 'vncunused')
         sdl = sxp.child_value(config, 'sdl')
         ret = []
         nographic = sxp.child_value(config, 'nographic')
@@ -315,6 +316,8 @@ class HVMImageHandler(ImageHandler):
             return ret
         if vnc:
             ret = ret + ['-vnc', '%d' % vncdisplay, '-k', 'en-us']
+        if vncunused:
+            ret += ['-vncunused']
         return ret
 
     def createDeviceModel(self):

tools/python/xen/xm/create.py

@@ -412,6 +412,11 @@ gopts.var('vncdisplay', val='',
           fn=set_value, default=None,
           use="""VNC display to use""")
 
+gopts.var('vncunused', val='',
+          fn=set_bool, default=1,
+          use="""Try to find an unused port for the VNC server.
+          Only valid when vnc=1.""")
+
 gopts.var('sdl', val='',
           fn=set_value, default=None,
           use="""Should the device model use SDL?""")
@@ -627,7 +632,7 @@ def configure_hvm(config_image, vals):
     """
     args = [ 'device_model', 'pae', 'vcpus', 'boot', 'fda', 'fdb',
              'localtime', 'serial', 'stdvga', 'isa', 'nographic', 'soundhw',
-             'vnc', 'vncdisplay', 'vncconsole', 'sdl', 'display',
+             'vnc', 'vncdisplay', 'vncunused', 'vncconsole', 'sdl', 'display',
              'acpi', 'apic', 'xauthority', 'usb', 'usbdevice' ]
     for a in args:
         if (vals.__dict__[a]):