[ixp1200] Doubt reg. Floating Point Operations support in IXP 1200

[David Mentre]

Hello Romit,

> From: romit dasgupta [mailto:romit at myrealbox.com]
> Sent: Tuesday, March 09, 2004 10:04 AM

>                     Thanks for your mail. Once I did a division 
> operation in the kernel and I got an error given by the assembler. I 
> enabled CONFIG_FPE_FASTFPE and the error vanished.

Oh, I see. The CONFIG_FPE_FASTFPE option adds an handler on FP exception, so
it also works within the kernel. I was wrong for that.

> You are 
> right we are 
> not supposed to do FP operations in Kernel but my 
> understanding is that, 
> if we do really need FP operations in kernel we have to 
> explicitly save 
> the FP context. Correct me if I am wrong.  

I think you are right. However it might raise subtle bugs if you fail to
save/restore the FP context at one scheduling point.

> By the way, if we dont enable CONFIG_FPE_FASTFPE, cant we 
> still use libm 
> from userspace?

I don't know.

Yours,
d.
-- 
David Mentré <mentre at tcl.ite.mee.com> - Research engineer (Ph.D.)
Mitsubishi Electric ITE-TCL / European Telecommunication Research Lab
Phone: +33 2 23 45 58 29 / Fax: +33 2 23 45 58 59 
http://www.mitsubishi-electric-itce.fr