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Path: utzoo!linus!security!genrad!mit-eddie!mit-vax!eagle!harpo!floyd!cmcl2!edler
From: edler@cmcl2.UUCP
Newsgroups: net.unix-wizards
Subject: Re: 2.8 exec bug fix wanted - (nf)
Message-ID: <983@cmcl2.UUCP>
Date: Wed, 21-Dec-83 13:22:36 EST
Article-I.D.: cmcl2.983
Posted: Wed Dec 21 13:22:36 1983
Date-Received: Fri, 23-Dec-83 01:39:36 EST
Sender: edler@cmcl2.UUCP
Organization: New York University
Lines: 17

#R:isrnix:14600002:cmcl2:5000003:000:694
cmcl2!edler    Dec 21 13:22:00 1983

Also watch out for programs doing "brk(0);".  On at least some versions
of unix for pdp11s without floating point hardware, this crashes
the system.  The problem is that there are some references to the
(non-existant) floating point registers in the kernel routine backup(),
and they cause a panic.  For some reason that was never clear to me,
they don't seem to get executed in normal practice, but brk(0) will do it.
A fix is to remove the offending instructions (at the location
of the pc printed by the panic).  Is there anyone that has taken the
time to understand backup() more completely, and can they say if this
is an ok fix?

	Jan Edler	cmcl2!edler	(New York University)
			edler@nyu