On 07-08-2009, ivan chollet <ivan.chol...@free.fr> wrote: > > This GDB was configured as "i386-marcel-freebsd"...(no debugging symbols > found)... > > Not very informative. So here are my questions:
I suppose you are running freebsd ? Which version of freebsd, of ocaml ? > > > > - What is the best way to produce and analyze core dumps in ocaml? > Should I compile in bytecode or native? Is there any special gdb "trick" > that gives you more information? Is there any special "trick" while > compiling the ocaml runtime to make it throw more information? > gdb is not the perfect tool to debug ocaml program. You should give a try to ocamldebug which is a better option for bytecode (see below for options). Bytecode is more informative when coming to reporting backtrace (at least with old version of ocaml). Compile every program with "-g" option (just like gcc). If you have compiled everything with "-g" option, you can also use the environment variable OCAMLRUNPARAM="b" to get a backtrace for your exception, at runtime. > - Then, my main question is actually: in bytecode, what can produce > segfaults? My ocaml code is completely standard, excepted that I use the > Marshal module. So my question is rather: outside the Marshal module, what > can cause segfault? Some part of the bytecode are just standard C, everything can cause a segfault just as C. These errors are not very common but it is possible that some case are not well handled on freebsd. Most probably a porting issue. Marshal module can easily trigger a segfault when you map the loaded data to a type which doesn't match the dumped data. Example: List.length (Marshal.from_string (Marshal.to_string 1234 []) 0);; Here the integer value is marshalled and then unmarshalled as a list -> segfault. > > - Slightly unrelated question: I have been able to generate > segfaults by running ocaml code that: 1) iterates recursively through a list > reference 2) changes the reference while still iterating on it. For example, > you just do a "List.iter myfun !myref", and within the function myfun, you > do stuff like "myref := List.filter somefilterfunction !myref". It is not > good to program like this, but for some reason I thought ocaml would not > segfault on that. Is this expected behavior? If it's not, I'll be happy to > provide some simple source code that illustrates it. (nevermind I have > actually cleaned all my code base from these dirty uses of references) > Could you provide a minimal example code for this error ? I don't think this should generate a segfault. Regards Sylvain Le Gall _______________________________________________ Caml-list mailing list. Subscription management: http://yquem.inria.fr/cgi-bin/mailman/listinfo/caml-list Archives: http://caml.inria.fr Beginner's list: http://groups.yahoo.com/group/ocaml_beginners Bug reports: http://caml.inria.fr/bin/caml-bugs
