Xen dom0 with FreeBSD 12.0

[Sam Pringle]

Hi.  Ran thru the instructions in https://www.freebsd.org/doc/handbook/virtualization-host-xen.html.
It did specify FreeBSD 11, not 12, so I assumed that bey now, Xen 4.11 could be used.  Perhaps that was my mistake.

Made all the changes as suggested.  On reboot, I get: "failed to load kernel /boot/xen".

There does not appear to be any menu-based means to disable the Xen choice, despite the /boot/menu.rc.local including the xen.4th file.

I am able to recover by doing "unset xen_kernel" then "boot".  However, no Xen kernel.

If this supposed to work?
I am running on an HP Z8 G4 with IOMMU enabled and 64MB memory.
I just blew away a Qubes-OS install as it was a bit too flakey and I was hoping FreeBSD would serve as a dom0.  It was running Xen and domU kernels fine.

I note the /boot/xen is 32-bit, whereas /boot/kernel/lkernel is 64 bit.  Does this matter?