First, create a bridge device. Edit the script bridge.sh:

#!/usr/bin/ksh

# Configure a bridge device to use with qemu

# Bridged interface
if=eth0

# Bridge name
bridge=br0

# Bridge network
address=192.168.1.7
netmask=255.255.255.0
gateway=192.168.1.1
broadcast=192.168.1.255

case $1 in
  start)
    print "Configure $bridge bridge..."
    brctl addbr $bridge

    print "Add $if on $bridge..."
    brctl addif $bridge $if

    print "Activating promiscuous mode on $if..."
    ip addr flush dev $if
    ip link set $if promisc on
    ip link set up dev $if

    print "IP address on $bridge..."
    ip addr add $address/$netmask broadcast $broadcast dev $bridge 
    ip link set $bridge up

    print "Set default route..."
    ip route add default via $gateway
  ;;
  stop)
    ip link set $bridge down
    brctl delbr $bridge
    ip addr flush dev $if
    ip link set $if promisc off
    ip link set down dev $if
  ;;
  *)
    print -u2 "usage: $0 start|stop"
    exit 1
  ;;
esac

exit 0
        

Run the script to create the bridge:

./bridge.sh start

Then, edit the script that will add the qemu tap device on the bridge (/etc/qemu-ifup):

#!/usr/bin/ksh

tap=$1

bridge=br0

# put the $tap interface up
ip link set up dev $tap

# adding $tap to bridge interface $bridge...
brctl addif $bridge $tap

exit 0
        

You can now run qemu with tap network interfaces.