>Unlike full-featured Linux-based hypervisors like KVM or Xen
I'm being pedantic about a random part of their description, but Xen is not based on linux. It is a microkernel sort-of based off of Nemesis OS. The dom0 is not Xen itself, it is just the control domain. Linux is probably the most heavily used dom0, but it is by no means the only dom0 - Solaris, FreeBSD, etc, can or previously could be used as dom0.
The description didn't say Xen was originally based on Linux. What the description said was that full-featured Linux-based hypervisors like KVM or Xen manage the resources to scale beyond what is physically available. Given the context of that quote was that Jailhouse is based on Linux, KVM and Xen have Linux-based versions, and Jailhouse is different because it doesn't oversubscribe hardware, I would say that there's little reason to nitpick the comment.
> full-featured Linux-based hypervisors like KVM or Xen
> KVM and Xen have Linux-based versions
There is no such thing as a Linux-based Xen. KVM and Xen are fundamentally different in that regard.
When you are running Xen, you are not running Linux. If you have a Linux dom0, that is still not Linux-based Xen. That is a control domain (a VM) where the management toolstack is installed. It's also the default driver domain, but you can have stub domains just for drivers too.
The point is that there is nothing Linux about the Xen hypervisor, at all. When you see a linux kernel with xen in the name, that isn't because it contains the xen hypervisor - it's because it is a kernel modified to utilize hypercalls, etc.
I'm being pedantic about a random part of their description, but Xen is not based on linux. It is a microkernel sort-of based off of Nemesis OS. The dom0 is not Xen itself, it is just the control domain. Linux is probably the most heavily used dom0, but it is by no means the only dom0 - Solaris, FreeBSD, etc, can or previously could be used as dom0.