Path: utzoo!attcan!uunet!brunix!rca
From: rca@cs.brown.edu (Ronald C.F. Antony)
Newsgroups: comp.sys.next
Subject: Re: in Time, again
Message-ID: <53117@brunix.UUCP>
Date: 13 Oct 90 07:00:03 GMT
References: <8969@helios.TAMU.EDU> <3258@uakari.primate.wisc.edu>
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Reply-To: rca@cs.brown.edu (Ronald C.F. Antony)
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Organization: Brown University Department of Computer Science
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In article <3258@uakari.primate.wisc.edu> bin@primate.wisc.edu writes:
>From article <8969@helios.TAMU.EDU>, by mcguire@cs.tamu.edu (Tim McGuire):
>> They tell me that the first large batch of 68040s had a bug which did not
>> affect any of the NeXT software because mach does not use the affected 
>> opcode.  This bug does sink most of the other companies who would use the 40.
>Hmm, maybe Mach itself doesn't use the opcode, but what's to stop *any*
>piece of application software from using it - and crashing?

There are two modes the processor can be running in: one is the
supervisor mode and the other is the user mode. Applications can only
use user mode instructions. Only the kernel is allowed to use the
priviledged instructions. So if the bug is in the supervisor mode
instruction set and MACH doesn't use it and you don't plan to
implement your own operating system on top of NeXT's hardware, there
shouldn't be any problem at all.

Ronald
------------------------------------------------------------------------------
"The reasonable man adapts himself to the world; the unreasonable one persists
in trying to adapt the world to himself. Therefore all progress depends on the
unreasonable man."  Bernhard Shaw | rca@cs.brown.edu or antony@browncog.bitnet