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Path: utzoo!watmath!clyde!bonnie!akgua!gatech!seismo!harvard!talcott!panda!genrad!decvax!yale!ISM780B!tim
From: tim@ISM780B.UUCP
Newsgroups: net.unix-wizards
Subject: Re: Orphaned Response
Message-ID: <28500046@ISM780B.UUCP>
Date: Tue, 29-Oct-85 13:12:00 EST
Article-I.D.: ISM780B.28500046
Posted: Tue Oct 29 13:12:00 1985
Date-Received: Sun, 24-Nov-85 03:48:15 EST
References: <2937@sun.UUCP>
Lines: 22
Nf-ID: #R:sun:-293700:ISM780B:28500046:177600:873
Nf-From: ISM780B!tim    Oct 29 13:12:00 1985


/* Written  7:23 pm  Oct 26, 1985 by guy@sun in net.unix-wizar */

don't think Motorola tells you 1) that it won't kill the system if you RTE
with arbitrary bits or 2) how to make sure that a bus error frame is safe.

/* End of text from net.unix-wizar */

If you want to see _wierd_ behaviour from a 68010, try changing the PC
in a bus error stack frame.

We had a case like this in the Callan Unistar 312 ( 68012 based box, running
a system V pageing system ).  We wanted to deliver a signal that a user was
wanting to trap, but we also want to rerun an instruction, since the reason
we are in kernel mode is that we have just finished a page fault.  By
experiment it was found that the 68012 is totally shpxrq(rot 13) by this.
We got around this with the trace bit.

				Tim Smith
				ihnp4!cithep!tim
				ihnp4!ima!ism780!ism780b!tim <- or something
								like that!