Path: utzoo!utgpu!watserv1!watmath!att!att!linac!uwm.edu!cs.utexas.edu!sun-barr!rutgers!uwvax!elliott@veronica.cs.wisc.edu
From: elliott@veronica.cs.wisc.edu (James Elliott)
Newsgroups: comp.sys.dec
Subject: Unaligned accesses on a DECstation 3100/Ultrix 4.0
Keywords: Disable the alignment fixer?
Message-ID: <11824@spool.cs.wisc.edu>
Date: 28 Nov 90 01:06:39 GMT
Sender: news@spool.cs.wisc.edu
Organization: U of Wisconsin CS Dept
Lines: 21


Ultrix 4.0 on a DECstation seems to have a nice feature of fixing up
unaligned accesses in executing programs. Rather than sending a
SIGBUS, it prints 

Fixed up unaligned data access for pid 5285 (adacs) at pc 0x41bc0c

on stderr (I'd guess), and continues execution.

Now, my problem is that I want to get >rid< of these unaligned
accesses, because I consider them bugs. So, I'd prefer to get the
signal, so I can trap into the debugger (and get lost trying to figure
out the code that Twig generated for me, but that's a different
problem). How can I do this? I tried providing a different handler for
SIGBUS, but it didn't get called; apparently the signal never gets
delivered even to that level?

Anyone have any ideas?
--
Jim Elliott		      "Like a bridge he'll come between us, not a wall"
elliott@veronica.cs.wisc.edu