From xen-devel:
It is with great pleasure that I announce that now that the multiboot patch got commited in Xen’s unstable tree for the coming 4.0 release, I have merged GNU Mach’s Xen tree into master, i.e. although it has already been used for the Debian buildds for a couple of years already,
GNU Mach now officially has Xen domU support!
(yes, GNU Mach, not Hurd, as no change was needed in the Hurd part 😀 )
Updated builds are available as usual on
http://youpibouh.thefreecat.org/hurd-xen/