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Date:      Fri, 13 Aug 1999 18:25:22 -0700
From:      charon@freethought.org
To:        "NO DATA" <anorak@topsecret.net>, "freebsd-questions@FreeBSD. ORG" <freebsd-questions@FreeBSD.ORG>
Subject:   Re: options MATH_EMULATE
Message-ID:  <3.0.5.32.19990813182522.00a6a9f0@mail>
In-Reply-To: <NDBBJDFMIMOCFNNCEKADOEGMCOAA.anorak@topsecret.net>

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At 12:21 PM 8/13/99 -0400, NO DATA wrote:
>(the only dumb question is the one not asked - so here's two:)
>How can I tell if I have a math emulator?
>What is the penalty for including either of these lines in my kernel
>if it is not needed?
>
>quote from the handbook:
>================================================
>options MATH_EMULATE
>This line allows the kernel to simulate a math co-processor if your
>computer does not have one (386 or 486SX). If you have a Pentium, a
>486DX, or a 386 or 486SX with a separate 387 or 487 chip, you can
>comment this line out.

I assume your first question is asking how to tell if you have a math
co-processor?  A math "emulator" is what the kernel would provide -
necessary only if you don't have a math co-processor.

If I do understand you right, then you tell just by knowing what kind of
CPU you have.  If you don't know this offhand, typing 'dmesg | more' will
tell you.  Just like the handbook says, if you have a 486SX or 386, leave
the line in, and if you have a 486DX or higher (Pentium) system, comment it
out.

I don't know what exactly will happen if you leave the line in
unnecessarily, but I believe the computer will just ignore it (it _is_
uncommented in GENERIC, after all).  All that does is add some unnecessary
size to your kernel.


-Charon


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