Subject: Re: sun3 - msoft-float
To: David Brownlee <>
From: Curt Sampson <>
List: port-sun3
Date: 08/24/2001 14:22:22
On Thu, 23 Aug 2001, David Brownlee wrote:

> 	The NetBSD kernel does not use floating point - see

That's a dead link, actually, and the specific question doesn't seem to
be anywhere on the web site anymore. However, Nishimura-san's explanation
of lazy FPU context switching, at:

gives enough insight that one should be able to figure out what's
going on.

(Summary: storing and reloading FPU state is expensive, and most code,
including the kernel, makes little to no use of the FPU. So it's
cheaper to do any floating point in the kernel in software than it is
to store/reload the FPU state with every entrance to the kernel.)

Curt Sampson  <>   +81 3 5778 0123
    Don't you know, in this new Dark Age, we're all light.  --XTC