[PATCH] Updates to FXSR/SSE support in 2.4.0-test1

[Gareth Hughes]

Alan Cox wrote:
> 
> > What happens when a signal occurs in a time slice where the application
> > hasn't used the FPU?  Having the regular FPU environment around means we
> 
> You touch the FPU, it loads the FPU state you save both. If the FPU state
> is already loaded it costs nothing. The FNSAVE stuff is horribly slow so
> it is a real concern.

I'm not sure I understand what you're advocating here.  If you're okay
with converting the FXSAVE data back and forth, then so am I.

> > I'll play around with the conversion into/out of the signal handler and
> > GETFPREGS request.  Should only take a short while, so don't do anything
> > with the stuff I sent out yesterday.
> 
> Right now its correct, this is about being correct clean and fast so we are
> going the right way

I certainly agree with making it clean and fast, as well as correct. 
Would you prefer the conversion and just using FXSAVE/FXRSTOR?

-- Gareth