Merge Xen (the hypervisor) into Linux

[Ingo Molnar <mingo@elte.hu>]

* 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