Date: Thu, 8 Aug 1996 11:08:51 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: Travis Brown-John <brownjoh AT sfu DOT ca>
Cc: djgpp AT delorie DOT com
Subject: Re: Hello World = Crash
In-Reply-To: <4u9cvg$ogv@felix.junction.net>
Message-Id: <Pine.SUN.3.91.960808110030.19168i-100000@is>
Mime-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII


On Wed, 7 Aug 1996, Travis Brown-John wrote:

> That's what I am running.  The demo code gives a GPF:
> 
> General Protection Fault at eip=0000356a
> eax=0000003f ebx=00001708 ecx=00003e80 edx=0000003f esi=00057000
> edi=d0000000
> ebp=0004f76c esp=0004f764 cs=00a7 ds=00af es=00af fs=0087 gs=00bf
> ss=00af
> Call frame traceback EIPs:
>   0x0000356a
>   0x0000187c
>   0x000035b8
>   0x0000194a
>   0x00004347

Compile and link the problem with -g switch.  When it segfaults, run
symify on it, and it will print the source filenames and source line
numbers right next to these addresses.  This will tell you where in the
program did the segfault happen.  Either this will give you enough info on
what's the bug, or you will be able to hunt it down with a debugger.  More
info about symify can be found in section 9.2 of the DJGPP FAQ list
(available as v2/faq201b.zip from the same place you get DJGPP).  It is 
not efficient to post tracebacks here, because people usually cannot tell 
you what's wrong with your program given the traceback alone.  If the 
above procedure won't help, at least post the traceback with the info 
that symify adds to it, and tell everything else you saw while trying to 
debug this; code fragments that cause the crash will also help.

If you wonder why a demo crashes, you should know that some bugs might go 
unnoticed on other platforms; or, if the program is ported from Unix, it 
might be some DOS-related issue that needs to be taken care of.