[fpc-pascal] GDB help needed please

Graeme Geldenhuys graeme at geldenhuys.co.uk
Thu Aug 30 00:13:45 CEST 2012


I hope somebody knows more about GDB that I. I'm trying to debug an 
error in one of our Master Maths projects. This error only occurs under 
Windows, where it bombs out at random times (in a specific section of 
our product) with a "Segmentation Fault" error. GDB pauses the program 
at that point, and the stack trace gives me the follow information 
(shown below).

That output unfortunately doesn't tell me much at all. :-(

Any idea how I can get more information from GDB? I have enabled the 
following FPC compiler options: -l -Mobjfpc -Sch -g -gl -gw -O- -godwarfsets

My fpc.cfg file is also set to NOT strip debug information (just in case).

I'm using FPC 2.6.0 (32-bit) released version to make sure I'm on a 
stable FPC (I recently had issues with 2.6.1).

I've also tried various GDB versions (6.8, 7.2 & 7.4) under Windows, 
thinking that newer versions might give me more information, but in all 
versions the crash output is exactly the same.

Signal received. Signal: SIGSEGV, Segmentation fault.

#1  01FB8D3C :0 ??()
#2  0040C51A :0 fpc_finalize()
#3  00000001 :0 ??()
#5  00520D80 :0 $MDLEXERCISE$_Ld37()
#6  00000001 :0 ??()
#7  01F0D888 :0 ??()
#8  00000000 :0 ??()

I've spent two days on this already and about to loose my mind. :-/ From 
the stacktrace above the only thing I can recognise, is the 
'mdlexercise' text, which is a unit in our project. But without any line 
numbers it is like looking for a needle in a very large haystack.

Any GDB tips somebody can share, that could help me get GDB to reveal 
more debug information?

   - Graeme -

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