Comment # 2 on bug 1012288 from Charles Arnold

We need you to capture the output when booting the host and Xen is selected.

First attach a serial cable from the serial port on the server to a second
machine's serial port. That second machine could be running minicom (or some
other program that can be setup to read from the serial port). Do the
following to prepare Xen to send its output over this serial line.

Edit /etc/default/grub and add,

  GRUB_CMDLINE_XEN_DEFAULT="loglvl=all guest_loglvl=all console=com1
com1=115200,8n1"

Also append additional serial flags to the option below,

  GRUB_CMDLINE_LINUX_DEFAULT="<pre-existing flags> console=ttyS0, 115200"

where pre-existing flags are those options already present and then run,

  grub2-mkconfig -o /boot/grub2/grub.cfg

Reboot the host. If minicom is setup correctly you will see the output
appear there as the host boots. Please capture this output to a text file
and attach to the bug.