1. Install emulators/xen-kernel
2. Do the prescribed steps in pkg-message
3. Reboot
4. If your system has VT-d CPUID capability, xen_kernel will be loaded
and the machine will boot. sysctl kern.bootfile shows the Xen kernel
otherwise the Xen kernel will kernel panic.
5. Reboot and this time go into the Boot Options submenu and toggle
Xen Kernel to "off" and press Enter to boot. sysctl kern.bootfile shows
the normal FreeBSD kernel.
6. If as-described above, the toggle is working as expected.