Re: Xen & VMI?

[Ingo Molnar <mingo@elte.hu>]

* Gerd Hoffmann <kraxel@suse.de> wrote:

> Ingo Molnar wrote:
> > btw., while we have everyone on the phone and talking ;) Technologically 
> > it would save us a whole lot of trouble in Linux if 'external' 
> > hypervisors could standardize around a single ABI - such as VMI. Is 
> > there any deep reason why Xen couldnt use VMI to talk to Linux? I 
> > suspect a range of VMI vectors could be set aside for Xen's dom0 (and 
> > other) APIs that have no current VMI equivalent - if there's broad 
> > agreement on the current 60+ base VMI vectors that center around basic 
> > x86 CPU capabilities - which make up the largest portion of our 
> > paravirtualization complexity. Pipe dream?
> 
> IIRC there was some proof-of-concept at least for xen guests.

yes - but de-facto contradicted by the Xen paravirt_ops patches sent to 
lkml ;)

> > there are already 5 major hypervisors we are going to support (in 
> > alphabetical order):
> > 
> >  - KVM
> >  - lguest
> >  - Windows
> >  - VMWare
> >  - Xen
> > 
> > the QA matrix is gonna be a _mess_.
> 
> I fail to see how xen-via-vmirom instead of xen-via-paravirt_ops 
> reduces the QA effort.  You still have 5 Hypervisors you have to test 
> against.

yes, just like we have thousands of separate PC boards to support. But 
as long as the basic ABI is the same, the QA effort on the Linux kernel 
side is alot more focused. (Distros still have 18446744073709551616 
total combinations to QA, and have to make an educated guess to reduce 
that to a more manageable number.)

	Ingo