Subject: Re: Floating point emulation
To: Peter Seebach <>
From: Nathan J. Williams <>
List: current-users
Date: 11/06/2005 00:14:53 (Peter Seebach) writes:

> On some BSD somewhere, I was once told to use floating point emulation in
> the kernel so that the kernel wouldn't have to save and restore floating
> point registers as often when processing system calls.

Right. By convention, the kernel isn't supposed to use hardware FP

> The MATH_EMULATE stuff in options(4) seems to imply that this option
> is useless unless your hardware lacks hardware floating point
> entirely.

MATH_EMULATE is for the kernel to trap and emulate userspace FPU
instructions on processor families that might or might not have FPUs,
such as PowerPC or MIPS.

        - Nathan