Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!oliveb!sun!sally!plocher
From: plocher%sally@Sun.COM (John Plocher)
Newsgroups: comp.unix.microport
Subject: Re: uport V386 fp
Summary: V/386 stuff
Message-ID: <102273@sun.Eng.Sun.COM>
Date: 2 May 89 00:50:47 GMT
References: <3452@alembic.UUCP> <757@pcrat.UUCP>
Sender: news@sun.Eng.Sun.COM
Reply-To: plocher@sun.UUCP (John Plocher)
Organization: Sun Microsystems, Mountain View
Lines: 22


The Erratum-21 bug which many have written about is a 386/387 hardware
bug.  Microport 3.0e and DosMerge 1.1.x do NOT have code to work around
this bug.  ATT 3.2 Unix (and thus Everex, ISC, SCO, BT, et al) has a
software fix for this problem.

The other thing which has come up is the fact that on several machines
(compaq and compaq clones especially) the co-processor detection is done
differently than Intel recomends (and thus different from the method
Microport assumed would be used).  In V/386 2.2 (and prev) we used the
Intel algorithm only.  In 3.0e we added special support for non-standard
coproc detection.  DosMerge 1.1 was built from the V/386 2.2 fp modules,
and thus does not handle fp detection on the compaq.  This was changed in
the Merge 1.1.1 engineering refresh to use the 3.0e fp modules.

Lastly, there have always been severe problems with the floating point handling in
ALL the versions of AT&Ts Unix for the [23]86 processors.  This includes Bills
commments about multiple fp intensive processes and the like.  I have NO first
hand experience that 3.2 has fixed this problem, but then again, I'm not a fp
deamon either :-)

   -John Plocher