Re: CVS commit: src/sys/arch/xen/xen

[David Laight <david%l8s.co.uk@localhost>]

On Sat, Feb 01, 2014 at 08:07:07PM +0000, Manuel Bouyer wrote:
> Module Name:  src
> Committed By: bouyer
> Date:         Sat Feb  1 20:07:07 UTC 2014
> 
> Modified Files:
>       src/sys/arch/xen/xen: hypervisor.c
> 
> Log Message:
> Revert previous: calling fpuinit() leads to a panic, as a domU is not
> allowed to manipulate cr0 directly. Xen doesn't need this, the fpu is
> handled by the hypervisor.

I probably remember seeing that panic as well.

XEN might need the bits of fpuinit() that don't play with cr0.
In particular a fninit and setting TS.
Although I'm not 100% sure the TS is needed on a single cpu system.
It isn't there on amd64, but really it does no harm.
Without it one process will have an indererminate fp state.

I can't say I've actuallly looked a xen.
Presumably we somewhere compile the hypervisor as part of a kernel?

        David

-- 
David Laight: david%l8s.co.uk@localhost