Path: utzoo!mnetor!uunet!lll-winken!lll-tis!ames!mailrus!tut.cis.ohio-state.edu!bloom-beacon!mit-eddie!uw-beaver!cornell!rochester!pt.cs.cmu.edu!IUS3.IUS.CS.CMU.EDU!ralphw
From: ralphw@IUS3.IUS.CS.CMU.EDU (Ralph Hyre)
Newsgroups: comp.unix.aux
Subject: Re: A/UX MacOS co-existence
Message-ID: <1496@pt.cs.cmu.edu>
Date: 22 Apr 88 14:24:29 GMT
References: <232@voysys.UUCP> <1711@desint.UUCP> <8075@apple.Apple.Com> <8398@oberon.USC.EDU> <347@caldwr.caldwr.gov> <1451@pt.cs.cmu.edu> <4036@sphinx.uchicago.edu>
Sender: netnews@pt.cs.cmu.edu
Organization: Carnegie-Mellon University, CS/RI
Lines: 26
Keywords: Macintosh A/UX HFS

In article <4036@sphinx.uchicago.edu> sas1@sphinx.uchicago.edu.UUCP (Stuart Schmukler) writes:
>In article <1451@pt.cs.cmu.edu> ralphw@IUS3.IUS.CS.CMU.EDU (Ralph Hyre) writes:
>
...
>>The 68020 supports the idea of a virtual machines, you can run any
>>number of independent 680X0 programs in user mode, even if they
>>want to run in supervisor mode.  ... [386 stuff deleted]
>
>One of the problems (I think) is that both the MacOS and its programs
>are running in supervisor mode.  Some programs take advantage of that
>fact even tho Apple has told them that it is not wise to rely on
>supervisor mode instructions.
This was part of my point, the Apple software will have no way of knowing
it's not running in supervisor mode, since executing a priviledged instruction
in user mode will cause a priviledge violation, which will invoke the
(mythical) A/UX handler for that which will provide the proper results to the
MacOS for the 'illegal' instruction.  [This all presumes that you can
control whether something runs in user or supervisor mode (on the Mac ][,
I presume you can since it's running Unix)] 

[apologies for terminology wierdness - I'm not a 680X0 hacker]

-- 
					- Ralph W. Hyre, Jr.

Internet: ralphw@ius2.cs.cmu.edu    Phone:(412)268-{2847,3275} CMU-{BUGS,DARK}
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