anchor.diff:  			Ports
   		),
   
  -	[{vif, 'bridge=xenbr0'}] ++ Vifs ++
  +	Xenbr0 =
  +		case Xenbr0_Mac of
  +			undefined ->
  +				{vif, 'bridge=xenbr0'};
  +			Mac ->
  +				{vif, list_to_atom("bridge=xenbr0,mac=" ++ Mac)}
  +		end,
  +
  +
  +	[Xenbr0 | Vifs] ++
   	[
   		{extra, Ipconf},
   		{extra, Mount},
  
positive.code: 				"-secret " ++ S
  		end,
  
  	conf(Ports, Queues, Controllers, Ipconf, ListenIp, ListenPort, Memory, NineP ++ " " ++ Secret).
  
  check_opt({"ipconf", Ipconf}) when is_list(Ipconf) ->
  	lists:foreach(
  
negative.code: 				check_ip(Netmask);
  			({"gateway", Gateway}) ->
  				check_ip(Gateway);
  			({"vif_mac", VifMac}) when is_list(VifMac) ->
  				ok;
  			(Unknown) ->
  				throw(io_lib:format("unknown ipconf field: ~p", [Unknown]))
  		end,
  