On Fri, Jun 16, 2000 at 07:31:50AM +0200, Jacques GANGLOFF wrote:
> Paolo Mantegazza wrote:
>
> > Tomasz Motylewski wrote:
> >
> > > I guess VT does not use FP, xterm (and Xserver) do use it.
> >
> > That's why you have to tell your real time scheduler that also Linux is
> > using the FPU. In fact the real time task swithching is optimized in
> > such a way to avoid saving/restoring the FPU if only one real time task
> > is using it.
>
> How can I tell the real-time scheduler that also linux is using the FPU in rt_linux ?
RTLinux does not directly support using FP in Linux kernel mode. It could, but this
would
complicate the scheduler and would make portability across architectures more
difficult.
>From the RTLinux point of view, Linux kernel/user mode differences are Linux problems.
What you can do is, by hand, save and restore Linux FP registers. It is easy to
take this code from the RTLinux code. But the correct solution is to move the FP
access into either user mode or RT thread mode for an RT thread with fp enabled.
> --
> _________________________________
> (
> ) Jacques GANGLOFF
> ( Associate Professor
> ) LSIIT / GRAViR
> ( Bd S�bastien Brant
> ) 67400 Illkirch
> ( Tel : +33 (0)3 88 65 50 84
> ) Fax : +33 (0)3 88 65 54 89
> ( http://gravir.u-strasbg.fr
> )_________________________________
>
>
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