Re: [Xen-ia64-devel] Question: Special linux dom0 handling in vcpu_translate()

[Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxxxxxxx>]

Am Donnerstag, 21. Juni 2007 schrieb tgingold@xxxxxxx:
> Quoting Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxxxxxxx>:
> > Hi,
> >
> > in vcpu_translate I found some lines of code which seems to be an
> > optimization
> > for the linux dom0:
>
> ...
>
> > I found this, because mini-os uses the same scheme. Now the hypervisor
> > does the itc for mini-os with a linux kernel identity mapped pte!
> > In general this may leads to problems if other systems with similar
> > region scheme are running on xen.
> > In particular I have here the problem that using protection keys for such
> > addresses is impossible!
> > Is it possible to do this optimization for the linux kernel another way?
>
> I think this special linux optimization should be enabled by the OS. We
> should add an hypercall (or a SAL call) for this.
>
> Tristan.

The question  is, should I add an optimization call specific to linux or 
specific to single optimization features.
Are there any other implicit optimisations for linux in the hypervisor?

I would add an hypercall. This can be called in setup_arch() after 
setup_xen_features().
 The struct arch_domain has to be extended with an optimisation flag.
What is your opinion?

Dietmar.

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