Re: Paravirt KVM capabilities

[Ingo Molnar <mingo-X9Un+BFzKDI@public.gmane.org>]

* Rusty Russell <rusty-8n+1lVoiYb80n/F98K4Iww@public.gmane.org> wrote:

> > It's also something for the Linux community in general to decide: if 
> > we want separate interfaces for paravirtualization and full 
> > virtualization (lhype and kvm) or a merged interface.  I can see 
> > arguments in favor of both positions.
> 
> Yeah, me too.
> 
> 	Ignoring technical questions for a moment, the main issue is 
> that lhype doesn't have an ABI; you have to run the same(ish) kernel 
> as guest and host.  This is by design: I wanted it to be a platform 
> for experimentation and hacking, because I think we're still at that 
> stage with x86 Linux virtualization.

i really really think KVM and lhype should merge, creating KVM/HVM 
(Hardware Virtual Machine) and KVM/LL (Linux on Linux). But that's 
really your business to decide, not mine :-) I guess it's not a pure 
technical decision :-/

( later on KVM/LL could be extended to also run unmodified guests 
  similar to how kqemu does it: by running guest user-space on ring 3 
  and letting Qemu do all of ring0 emulation. That is already leagues 
  faster than default Qemu, and it would also nicely test lhype's 
  cr3/pagetable management infrastructure. It can also run most 32-bit 
  OSs out there - largely extending the userbase even on legacy 
  hardware. )

regarding ABI: agreed that it's experimental right now and should stay 
so for some time, but i dont see a reason why the hypercall API that 
i've posted in the past few days couldnt be evolved in the way Linux 
syscalls evolve, by only adding to them. That doesnt really impact the 
flexibility of the virtualization subsystem. We could also possibly 
phase out older hypercalls, because the number of "applications" relying 
on it will be very low.

	Ingo

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