No cosole output on Xen until booted

When booting VyOS 1.1.7 as a DomU in Xen (Version: 4.4.1-9+deb8u6) with following xen config:

[code]# Configuration file for the Xen instance vyos

name = ‘vyos’

vcpus = ‘2’
memory = ‘512’
maxmem = ‘1024’

bootloader = “pygrub”
root = ‘/dev/xvda1 ro’

When using pygrub to boot from the ISO, the .iso must be the first disk listed

disk = [

vif = [ ‘bridge=xenbr0, ip=, mac=00:16:3e:57:49:9c’,
‘bridge=xenbr1, ip=, mac=00:16:3e:57:49:9d’

And using xl tools

xl create vyos.cfg xl console <id>

We only get the console once vyos boots correctly and the configured hvc console is started

system { config-management { commit-revisions 20 } console { device hvc0 { speed 9600 } device ttyS0 { speed 9600 } }

How can we get the live output from the whole boot process?
If ever something goes wrong during boot, this would be invaluable.