Re: [RFC, PATCH 1/24] i386 Vmi documentation II

Andi Kleen
2006-03-23T00:12:04Z

On Thursday 23 March 2006 00:54, Zachary Amsden wrote:
> Andi Kleen wrote:
> > On Wednesday 22 March 2006 23:45, Zachary Amsden wrote:
> >
> >
> >> I propose an entirely different approach - use segmentation.
> >>
> >
> > That would require a lot of changes to save/restore the segmentation
> > register at kernel entry/exit since there is no swapgs on i386.
> > And will be likely slower there too and also even slow down the
> > VMI-kernel-no-hypervisor.
> >
>
> There are no changes required to the kernel entry / exit paths. With
> save/restore segment support in the VMI, reserving one segment for the
> hypervisor data area is easy.

Ok that might work yes.

> > Still might be the best option.
> >
> > How did that rumoured Xenolinux-over-VMI implementation solve that problem?
> >
>
> !CONFIG_SMP -- as I believe I saw in the latest Xen patches sent out as
> well?

Ah, cheating. This means the rumoured benchmark numbers are dubious too I guess.

-Andi