For the longest time I wanted to see OpenBSD on Rackspace Public Cloud. With their boot.iso you are able to attempt to boot into a pxe environment and boot OpenBSD 5.7, but it lacks the necessary drivers for xen. I gave up for a while. but tried with the release of OpenBSD 6. I am happy to report, that you CAN and it WORKS! To do so, you boot into a linux distro, download bsd.