Merge Xen (the hypervisor) into Linux

Ingo Molnar
2009-06-02T23:29:48Z

* Steven Rostedt <rostedt@goodmis.org> wrote:

> Now here's a crazy solution. Merge the Xen hypervisor into Linux
> ;-)

That's not that crazy - it's the right technical solution if DOM0 is
desired for upstream. From what i've seen in DOM0 land the incestous
dependencies are really only long-term manageable if the whole thing
is in a single tree.

A lot of Xen legacies could be dropped: the crazy ring1 hack on
32-bit, the various wide interfaces to make pure-software
virtualization limp along. All major CPUs shipped with hardware
virtualization support in the past 2-3 years, so the availability of
VMX and SVM can be taken for granted for such a project.

That cuts down on a fair amount of crap. A lot of code on the Linux
side could be reused, and a pure CONFIG_PCI=y (all other things
disabled) would provide a "slim hypervisor" instance with a very
small and concentrated code base. (That 'slim hypervisor' might even
be built with CONFIG_NOMMU.)

That way dom0 would be a natural extension: a minimal interface
between Linux-Xen-minimal and the dom0 guest instance.

It's a sane technical model IMO, and makes dom0 a lot more
palatable. Having in-tree competition to KVM would also obviously be
good to Linux in general.

Ingo