How to generate and use "core" files Edit

This appendix is for Unix users. I dont know if other platforms have similar features, that when the program crashes unexpectedly the OS would dump the contents of the memory of the crashing process into a disk file for later inspection.

First make sure that PvPGN has been compiled with debugging ("-g" parameter to gcc) and with no optimizations ("-O0" parameter to gcc). PvPGN default build process puts "-g -O2" so you need to edit Makefile file before compile and change it to "-g -O0". Then something like "make clean; make".

On Unix/Linux to be able to get core dumps you first need to make sure your core file size limit is set acordingly. Use "ulimit -c" for querying and setting this limit (I recommend setting it to "unlimited"). After that when you start PvPGN make sure you are in a directory where you have write access (so the OS when it wants to do the core dump it will be allowed to do so). The last thing to do is when starting PvPGN make sure it starts in FOREGROUND, example:

$ /path/to/bnetd -f

If you did all this, you will get a core dump when PvPGN crashes.

On linux this is a file called "core", on *BSD it's called <processname>.core (for bnetd that means it's called bnetd.core).

Now that you got a core file it is time to use it to identify what happened wrong in the crashing process. We use gdb (the GNU debugger, should be available on all Unices) to do this. Run gdb like this:

$ gdb /path/to/bnetd /path/to/corefile

Then gdb should startup, print out a lot of messages and stop after printing a file and line number and quoting some C code where the crash has happened. You can find out a lot more information than this. Run gdb's command "bt full" and it will display a full backtrace of the moment of the crash. The backtrace will contain how the functions were called along the way (their parameters), and also any local variables. If you do not know what to do next from here contact a PvPGN developer and give him exactly that backtrace dump, he should know more.