install Xen and update grub

apt-get install xen-linux-system xen-tools
 
dpkg-divert --divert /etc/grub.d/08_linux_xen --rename /etc/grub.d/20_linux_xen
 
update-grub

/etc/xen/xend-config.sxp

vim /etc/xen/xend-config.sxp

change the following lines to use bridging network setting