Path: utzoo!attcan!uunet!husc6!uwvax!oddjob!ncar!boulder!corbet
From: corbet@boulder.Colorado.EDU (Jon Corbet)
Newsgroups: comp.unix.microport
Subject: Re: Pcomm (actually, VAX protection)
Message-ID: <6232@sigi.Colorado.EDU>
Date: 24 May 88 21:22:17 GMT
References: <387@dalek.UUCP> <15105@sgi.SGI.COM>
Sender: news@sigi.Colorado.EDU
Reply-To: corbet@boulder.Colorado.EDU (Jon Corbet)
Organization: University of Colorado, Boulder
Lines: 10

A minor quibble:

jmb@patton.SGI.COM (Jim Barton):
>  Some primitive architectures (such as the VAX)
>allow you to de-reference 0 and get 0 back - most modern systems disallow this. 
The VAX, like any reasonable virtual-memory machine, has individual page
protection.  VMS sets page zero (which, obviously, contains the address zero)
to be no-read-no-write, thus causing an exception when a zero pointer is
dereferenced.  BSD, as I recall, will do this only if you pass a special
flag to ld.