When attempting to launch the Xen hypervisor from Grub2 on a machine that runs
with UEFI, the process fails. Depending on secure boot settings this happens
either immediately (i. e. Grub refuses to load xen and immediately returns to
the boot menu) or after attempting to launch Xen and boot up the kernel.

In this event the machine unexpectedly resets.

Switching repositories back to openSuSE from Virtualization doesn't help,
either, so Grub displays the same symptoms with either repository.

Booting a desktop kernel, however, works without any problems.