[ros-dev] RE: [ros-diffs] [CVS reactos] FPU/SSE state saving ontaskswitching, FPU and SSE exception support.

[Hartmut Birr]

Hi,

> -----Original Message-----
> From: ros-dev-bounces at reactos.com 
> [mailto:ros-dev-bounces at reactos.com] On Behalf Of Anich Gregor
> Sent: Sunday, November 21, 2004 2:47 PM
> To: ReactOS Development List
> Subject: Re: [ros-dev] RE: [ros-diffs] [CVS reactos] FPU/SSE 
> state saving ontaskswitching, FPU and SSE exception support.
> 
> The KPCR is per-processor, isnt it?

Correct.


> Is it possible that in a SMP system there is one CPU which 
> has less features 
> than the other (i.e. FXSR) or is it somewhere specified that 
> you must use 
> exactly same CPUs?

The cpu's are the same and KiCheckFPU is called for both cpu's. I think that
the problem is NpxThread. If a thread uses the fpu and is switched between
different cpu's, the state of the fpu is only saved if an other thread uses
the fpu.


> I will try to find out how to fix the fpu stuff on SMP...
> 

I've revert some parts of fpu.c to your first patch. It works now on my smp
machine. 


The current cvs tree doesn't work on a smp machine. If someone will test ros
on a smp machine, I should clean up and commit my changes in ntoskrnl and in
hal.

- Hartmut

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