Step-1:
On your XenServer host, run the following commands as root:

    wget --no-check-certificate https://github.com/openstack-dev/devstack/zipball/master
    unzip -o master -d ./devstack
    cd devstack/*/

Step-2:
create localrc

Step-3:
Run `./install_os_domU.sh` from the `tools/xen` directory

    cd tools/xen
    ./install_os_domU.sh