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From: jdb@mordor.UUCP
Newsgroups: comp.windows.x
Subject: Re: Bugs in uwm/menuwm for SUNs
Message-ID: <4529@mordor.s1.gov>
Date: Mon, 30-Mar-87 20:11:54 EST
Article-I.D.: mordor.4529
Posted: Mon Mar 30 20:11:54 1987
Date-Received: Wed, 1-Apr-87 02:46:44 EST
References: <5794@bu-cs.BU.EDU> <386@bacchus.MIT.EDU> <15815@sun.uucp>
Reply-To: jdb@mordor.UUCP (John Bruner)
Organization: S-1 Project, LLNL
Lines: 25

It has been some time since I've worked on it, but back in 4.2BSD I
made some (relatively minor) changes to the kernel and a few utility
program to implement a page-0-invalid executable format.  The file
format is identical to 0413 (ZMAGIC, -z) except for two things:
(1) the magic number is 0420, (2) the first page of the text segment
is filled with zeros and the entry point is 1024, not 0.  The kernel
doesn't map page 0, so a reference to NULL causes a bus error.
The loader recognizes the new flag "-Z" and zero fills the first
page.  There is a change to "nlist.h"; most programs which look at
object files in the standard ways need no (or minor) changes.

Back in the late summer of 1985 I reimplemented these changes in
beta 4.3BSD.  A summary of the changes to beta 4.3 is available
for anonymous FTP on MORDOR.S1.GOV as the file "z0magic".  Since 
I made these changes I've done a lot of other things to our
VAX kernel (e.g. installing NFS), so I can't provide a diff against
a standard 4.3 kernel without some more work.

If there is sufficient interest I'll try to put together a version
based upon vanilla 4.3.  However, my time for UNIX is pretty limited
right now, so I can't promise speedy action.
-- 
  John Bruner (S-1 Project, Lawrence Livermore National Laboratory)
  MILNET: jdb@mordor.s1.gov		(415) 422-0758
  UUCP: ...!ucbvax!decwrl!mordor!jdb 	...!seismo!mordor!jdb