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Date:      Wed, 21 Aug 1996 10:32:51 +0200 (MET DST)
From:      Christoph Kukulies <kuku@gilberto.physik.rwth-aachen.de>
To:        joerg_wunsch@uriah.heep.sax.de
Cc:        freebsd-hackers@freebsd.org, kuku@gilberto.physik.rwth-aachen.de
Subject:   Re: max math performance - how?
Message-ID:  <199608210832.KAA08275@gilberto.physik.rwth-aachen.de>
In-Reply-To: <199608202032.WAA17791@uriah.heep.sax.de> from J Wunsch at "Aug 20, 96 10:32:27 pm"

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> As Bruce Evans wrote:
> 
> > 386BSD used libm, which is slow.  -current uses msun, which is
> > slower, except possibly if it is compiled with option HAVE_FPU.
> 
> Why don't we compile it with this option?  I thought the emulator will
> serve those folks who don't have an FPU?  We could also ship the
> non-FPU lib in a separate package in releases, but i think a large
> number of machines now come with an FPU as an integral part of their
> system, so still defaulting to non-FPU math libs seems a little silly.

Another idea comes into mind: (don't know 386 architecture so well though):
Assumed you have an FPU inlined libm. Would it be possible to
run the emulator through a trap (emulator trap instruction) or
intercepting the illegal instruction trap, checking the stack for a valid
FPU instruction and pass instruction execution to the emulator
in that case.

> 
> -- 
> cheers, J"org
> 
> joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE
> Never trust an operating system you don't have sources for. ;-)
> 

--Chris Christoph P. U. Kukulies kuku@gil.physik.rwth-aachen.de



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