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

Hello Romit,

From: romit dasgupta [mailto:romit@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 - 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