Date: Sun, 15 Feb 1998 13:30:56 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: Martin Stromberg <Martin DOT Stromberg AT lu DOT erisoft DOT se>
cc: djgpp AT delorie DOT com
Subject: Re: gdb crash while debugging df
In-Reply-To: <6c1jqi$4di$1@antares.lu.erisoft.se>
Message-ID: <Pine.SUN.3.91.980215132912.27889P-100000@is>
MIME-Version: 1.0
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On 13 Feb 1998, Martin Stromberg wrote:

> gdb crashed while I debugged df. When I ran it again I looked first at the 
> variable before dereferencing it, and it being 0xffffffff I'm not too
> surprised that it crashed, but should gdb really _crash_? Is it a bug
> in gdb or am I myself to blame?

No, it's GDB alright.  I doubt that this could be fixed in general,
since the exception handling in DJGPP debuggers is extremely tricky.
The problem is that the debugger and the debuggee is actually running
as a single program, as far as the OS is concerned, and it is very
hard to distinguish between exceptions generated by these two.
Ideally, exceptions generated by the debugged code should not crash
the debugger.

One great thing about GDB is that it will allow you to write a 
user-defined command called e.g. `safeprint' which will look at the 
pointer before dereferencing it (FFFFFFFFh will almost always trigger a 
Page Fault).