Subject: Re: Floating point emulation
To: Nathan J. Williams <>
From: Peter Seebach <>
List: current-users
Date: 11/05/2005 23:20:47
In message <>, "Nathan J. Willia
ms" writes:
> (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.


So the kernel already DTRT anyway?  Or is this a separate option, such
as -msoft-float?