Tested on OpenBSD 6.3 and 6.4

OpenBSD VM Guest OS Compatibility

vmd(8) runs virtual machines (VMs) on a host, it’s controlled via vmctl(8).

Works  
Ubuntu 18 @canadianbryan
Debian 9 @ben_bai @vext01
Alpine @voutilad
boot2docker @jon: needs a dummy disc to boot off ISO
 

Doesn’t
OpenIndiana Hipster @jon
netboot.xyz @jon
xv6 @jon: hangs after Booting from 0000:7c00
HelenOS @jon: hangs at kernel monitor prompt
TempleOS @jon
Minix 3 @jon: VGA to Serial stuff breaks down
tor-ramdisk @jon: no serial console, no network traffic