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Path: utzoo!watmath!clyde!cbosgd!ihnp4!tellab1!tellab2!thoth
From: thoth@tellab2.UUCP (Marcus Hall)
Newsgroups: net.arch
Subject: Re: Re: Where to do stack checking, etc.
Message-ID: <3563@tellab2.UUCP>
Date: Fri, 20-Sep-85 21:47:55 EDT
Article-I.D.: tellab2.3563
Posted: Fri Sep 20 21:47:55 1985
Date-Received: Thu, 26-Sep-85 06:30:07 EDT
References: <796@kuling.UUCP> <1713@orca.UUCP> <1599@peora.UUCP> <335@ihlpl.UUCP> <2384@uvacs.UUCP> <1232@hcrvx1.UUCP>
Reply-To: thoth@tellab2.UUCP (Marcus Hall)
Organization: Tellabs, Inc.  Lisle, Illinois
Lines: 17

In article <2384@uvacs.UUCP> mac@uvacs.UUCP (Alex Colvin) writes:
>
>I'm still looking for a machine that will trap references to uninitialized
>data.

Hasn't this been implemented in some system by faking a parity error on all
uninitialized data.  After trapping on the parity error, if what's there is
the same as the bit "special" pattern, it's a pretty good guess that it's
uninitialized (as distinguished from a real live parity error).

I'm fairly sure that I have seen this somewhere, but I'm not quite sure where
it was.  It requires being able to write a word with bad parity (not too
hard, I guess) and is essentially very kludgy, but it doesn't cost an extra
bit just to tell if the area is uninitialized.

marcus hall
..!ihnp4!tellab1!tellab2!thoth


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