gdb 6.4 does not stop unwinding even after reaching the last frame.

["Kalpana Ramamurthy" <kal_pana@hotmail.com>]

Hello,

I am using gdb 6.4 for debugging the product that I work on. When I try to 
print a bactrace, I get
an extra frame at the end which looks like this :

#6 0x00000000 in ?? ()

The newer frame (which is frame 5) is supposed to be the last frame. But for 
some reason gdb does
not stop unwinding even after it reaches the last frame and tries to unwind 
further hence hitting
a null backpointer where it cannot unwind any further. The instruction 
pointer is null too.

When I tried using gdb 5.3 to debug the same binary and analyse the same set 
of cores which I had analysed using gdb 6.4, I do not get this extra frame 
problem. The frame unwinding stops
at frame 5. Ther is no null 6th frame.

What is wrong here ? Why the difference in behaviour between gdb 6.4 and gdb 
5.3. I know that gdb 5.3 uses stabs debugging format and gdb 6.4 uses dwarf. 
Could this be a reason for the problem ?

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