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From: cwitty@csli.Stanford.EDU (Carl Witty)
Newsgroups: comp.soft-sys.andrew
Subject: Re: console gets bus error, other nasties -- PL 6
Message-ID: <15035@csli.Stanford.EDU>
Date: 24 Aug 90 06:51:20 GMT
References: <14951@csli.Stanford.EDU>
Sender: cwitty@csli.Stanford.EDU (Carl Witty)
Distribution: comp
Organization: CSLI, Stanford University
Lines: 31
In-reply-to: cwitty@csli.Stanford.EDU's message of 18 Aug 90 01:50:35 GMT

In article <14951@csli.Stanford.EDU> cwitty@csli.Stanford.EDU (Carl Witty) writes:
   1) "console" compiled on a Sparcstation 1 gives a bus error in a
   function called by the application_Start() macro on line 202 of
   runapp.c.  It runs fine on a sun 3 or an IBM RT running AOS 4.3.  (The
   suns both run 4.0.3).

   How does one go about debugging this?  Normally, I'd go into a
   debugger and get a backtrace, to see where it died, and then look at
   the source code to see if I could figure out what was wrong.  With
   this dynamic loading stuff, I can't figure out how to get the debugger
   to tell me what function it died in, so I can't figure out how to
   start debugging it.

Thanks to Gary Keim <gk5g+@andrew.cmu.edu> for sending me information
on debugging dynamically loaded programs.  Unfortunately, when I
attempted to recompile the offending parts with debugging information,
the problem went away.  His information was enough to localize the
function in which the core dump occurred, though, and I used
printf()'s (ugh) to find the line it was dumping core on: the problem
is in the file .../andrew/atk/console/lib/vmmon.c, InitStats(), around
line 61, which is:

    mask = sigblock(1 << (SIGCHLD - 1));

Since the problem goes away when optimization is turned off, it's
probably just a compiler bug.  (/bin/cc, SunOS 4.0.3c.  SparcStation 1.)

For now, I'll just compile that file without optimization.

Carl Witty
cwitty@cs.stanford.edu