Subject: Re: kernel options MATH_EMULATE (was: Re: mk.conf and "I387_LIBM")
To: Richard Rauch <email@example.com>
From: Manuel Bouyer <firstname.lastname@example.org>
Date: 10/23/2000 10:51:41
On Sun, Oct 22, 2000 at 09:03:06PM -0500, Richard Rauch wrote:
> My understanding is that MATH_EMULATE is used in the kernel config solely
> to determine whether the kernel will use FP instructions (and hence
> registers). By turning on MATH_EMULATE, you cause kernel FP operations to
> be emulated, so the kernel doesn't need to fret with the FP registers,
> and/or if the kernel has the FP registers saved, it may then freely use
> them as temporaries for data-copy loops.
No. This enable the kernel floating point emulator, which is used when an
FPU instruction is encountered on a FPU-less CPU. On a CPU with a FPU,
MATH_EMULATE doesn't change anything.
The kernel doesn't use any FP instruction.
Manuel Bouyer, LIP6, Universite Paris VI. Manuel.Bouyer@lip6.fr