I followed the instructions in https://help.ubuntu.com/community/Xen. Well, the first two steps. After the reboot, I am presented with:
Loading Xen 4.9-amd_64 ... WARNING: no console will be available to OS Loading Linux 4.15.0-20-generic ... Loading initial ramdisk ...
Does anyone run Ubuntu as dom0 in Xen these days? This is on a new HP Z8 workstation with dual "silver xeon 4114" which should have all the requisite functions.
I am a bit concerned about the lack of much detail in the BIOS. About the only thing I can tweak is the Hyper-threading setting.