Ubuntu Xen

Install the Xen hypervisor tools and kernel:

aptitude -y install xen-hypervisor-amd64

Download the Ubuntu 14.04 / trusty kernels to do a netboot off of, the one with the most recent updates here.

Sample configuration, using a netboot kernel:

kernel        = '/etc/xen/kernels/trusty-updates/vmlinuz'
ramdisk       = '/etc/xen/kernels/trusty-updates/initrd.gz'
memory  = 4096
vcpus   = 4
name    = 'ubuntu-xen1'
disk    = ['phy:/dev/xvg/ubuntu-xen1-root,xvda,rw','phy:/dev/xvg/ubuntu-xen1-swap,xvdb,rw']
vif     = ['bridge=br0']

Once the installation is finished, disable the kernel and ramdisk settings, and set the bootloader to pygrub:

bootloader = 'pygrub'
# kernel        = '/etc/xen/kernels/trusty-updates/vmlinuz'
# ramdisk       = '/etc/xen/kernels/trusty-updates/initrd.gz'