I'm using ubuntu 10.04 with qemu-kvm installed. I bridged my eth0 to br0. My problem is that The host OS loses connection. Here is my interfaces file
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet manual
auto br0
iface br0 inet dhcp
bridge_ports eth0
bridge_stp off
bridge_fd 0
bridge_maxwait 0