Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!cica!tut.cis.ohio-state.edu!pt.cs.cmu.edu!b.gp.cs.cmu.edu!ralf
From: ralf@b.gp.cs.cmu.edu (Ralf Brown)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Brain-dead 286 - summary
Message-ID: <8332@pt.cs.cmu.edu>
Date: 8 Mar 90 12:43:17 GMT
References: <8681@rosevax.Rosemount.COM> <29405@amdcad.AMD.COM> <4983@jarthur.Claremont.EDU>
Distribution: usa
Organization: Carnegie-Mellon University, CS/RI
Lines: 15

In article <4983@jarthur.Claremont.EDU> jmerrill@jarthur.Claremont.EDU (Confusion Reigns) writes:
}from getting out of line.  The 286's lack of a protected -> real switch is
}not an obstacle to any 'random program'; observe the hack involving
}resetting the chip.  Your 'random program' could do that just as easily as
}send the protected -> real instruction to the 386.

Not quite the same.  The 386 protected->real switch can only be executed by a 
process running at the greatest (kernel) privilege.  And on a 386, the I/O
space can be virtualized such that unprivileged processes can't tell the
keyboard controller to reset the CPU.
-- 
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