>Date: Wed, 13 Mar 1996 10:07:29 -0600
>From: VaX#n8 <vax@linkdead.paranoia.com>

>1) If you have a 486DX with a math fpu, do you want or need the npx line
>   in the kernel config?
>
>2) If you have this line, will fpu instructions invoke it, despite the
>   fact you have hardware to do it?

I don't know exactly what removing npx0 would do, but it probably
wouldn't be pretty.

What you *do* want to eliminate if you have an FPU is 'options
MATH_EMULATE'.

>1) Currently, to get the math libraries (libm) to compile right, you
>   must edit the libm makefile.  What is the diff here?
>   If you do not use i387 in this makefile, does it do emulation with
>   integer code or something, or what?  It is somehow unoptimal to
>   simply use the same routines and simply emulate the unimplemented
>   fp instructions in the kernel?

The assembly code in .../libm/arch/i387 uses FPU opcodes that are not
supported by the current FPU emulator, so by default we use the
generic C code in .../libm/src.  The compiler uses a subset of the FPU
opcodes that the emulator handles properly.
-- 
Mike Long <mike.long@analog.com>     <URL:http://www.shore.net/~mikel>
VLSI Design Engineer         finger mikel@shore.net for PGP public key
Analog Devices, CPD Division          CCBF225E7D3F7ECB2C8F7ABB15D9BE7B
Norwood, MA 02062 USA       (eq (opinion 'ADI) (opinion 'mike)) -> nil