tested-by: Wen Ruo Lv&lt;lvroyce(a)linux.vnet.ibm.com&gt; tested 1.net-start cmd with bridge mac specified (failed) 2.attach-device cmd with a hot plug nic(ok) My network is as below: <network> <name>default</name> <uuid>361441af-e1f0-472d-a503-dfcbbefa03fb</uuid> <forward mode='nat'/> <bridge name='virbr0' stp='on' delay='0' /> <mac address='00:16:3E:5D:C7:9E'/> <ip address='192.168.122.1' netmask='255.255.255.0'> <dhcp> <range start='192.168.122.2' end='192.168.122.254' /> </dhcp> </ip> </network> It fails at brSetInterfaceMac-->return ioctl(ctl->fd, SIOCSIFHWADDR, &ifr) but SIOCGIFHWADDR succeed. error msg is: cannot create dummy tap device 'virbr0-nic' to set mac address on bridge 'virbr0':no such device