Subject: Re: Floating point emulation
To: Peter Seebach <firstname.lastname@example.org>
From: Nathan J. Williams <email@example.com>
Date: 11/06/2005 00:14:53
firstname.lastname@example.org (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
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.