ocamldebug must not be stripped!

ocamldebug must not be stripped!

[Markus Mottl]

Bonjour - Hello,

L'executable "ocamldebug" (version 1.07) ne marche pas s'il est
"stripé" (? :-) )

I have just found out that "ocamldebug" itself must not be stripped in
order to work (at least under i686 - Linux 2.0.30 and Alpha - Digital
Unix 4.0d). I didn't find this anywhere in the documentation.
Does "ocamldebug" really need its own debug information or is this a bug?
It will probably need it in any case... ;-)

Do the other programs need their debug information? Until now I have
not encountered any problems, but who knows...

                   Amicalement - Best regards,
                            Markus Mottl

-- 
*  Markus Mottl              |  University of Economics and       *
*  Department of Applied     |  Business Administration           *
*  Computer Science          |  Vienna, Austria                   *
*  mottl@miss.wu-wien.ac.at  |  http://miss.wu-wien.ac.at/~mottl  *

Re: ocamldebug must not be stripped!

[Xavier Leroy]

> I have just found out that "ocamldebug" itself must not be stripped in
> order to work (at least under i686 - Linux 2.0.30 and Alpha - Digital
> Unix 4.0d). I didn't find this anywhere in the documentation.
> Does "ocamldebug" really need its own debug information or is this a bug?
> It will probably need it in any case... ;-)
> 
> Do the other programs need their debug information? Until now I have
> not encountered any problems, but who knows...

All executables generated by "ocamlc -custom" must not be stripped.

The reason is that they are composed of a C executable (the custom
runtime system) concatenated with the OCaml bytecode for the program.
The C executable looks at "itself" (the file it comes from) to load
the bytecode.

"strip" on most Unix machines just discards the C debugging
information as well as everything that follows it, thus discarding the
bytecode as well.

ocamldebug is just an instance of the general case, since it is
produced by "ocamlc -custom".

- Xavier Leroy

Re: ocamldebug must not be stripped!

[Markus Mottl]

Bonjour - Hello,

                        english version
                        ---------------

Ah, I see... The only program of the ocaml-distribution compiled to
bytecode even if native code is desired is the debugger!  I didn't
know this...

[from Patrick.Loiseleur@lri.fr]
> However, it must be possible to modify the Makefile in order
> to compile it in native code. Or is it a special reason that makes
> compilation of ocamldebug in native code not possible ?

Although it is probably not necessary to compile the debugger in native
code (it is fast enough, I think), I had a look on that, but did not
succeed to link everything after having manipulated the Makefile:

I replaced all occurrences of ".cmo" by ".cmx", ".cma" by ".cmxa"
and added some object files, that implement otherwise missing symbols,
to the linking process:

  ../byterun/meta.o
  ../byterun/stacks.o
  ../byterun/fix_code.o
  ../byterun/prims.o
  ../byterun/debugger.o
  ../byterun/array.o
  ../byterun/fail.o

Unfortunately, the files "fail.o" and "array.o" contain some symbols
that also exist in "libasmrun.a", which is implicitly linked against
the executable. I thought, it would not be very wise to hack any further
into the build process of the debugger, since I am content with the
debugger anyway...

                       version francaise(?)
                       --------------------

Ah, je comprends... Seulement le debugger est compilé en "bytecode", même
si on demande code natif! Je ne l'ai pas su...

[de Patrick.Loiseleur@lri.fr]
> A moins d'une raison particulière (mais laquelle) je pense qu'il est
> possible de compiler ce programme en natif si on le désire.

Je ne pense pas qu'il soit nécessaire de compiler le debugger en natif
(il est assez vite), mais je l'ai essayé (sans succès):

J'ai remplacé ".cmo" par ".cmx", ".cma" par ".cmxa" au "Makefile" et j'ai
ajouté les fichiers suivants (ils contiennent des symbols nécessaires)
pour "linkage":

  ../byterun/meta.o
  ../byterun/stacks.o
  ../byterun/fix_code.o
  ../byterun/prims.o
  ../byterun/debugger.o
  ../byterun/array.o
  ../byterun/fail.o

Malheuresement, les fichiers "fail.o" et "array.o" contiennent quelques
symbols qui aussi existent en "libasmrun.a", qui est implicitement
utilisé pendant "linkage". Je n'ai pas continué á chercher une solution -
je n'ai pas besoin d'un debugger plus vite...

                       Best regards - bien amicalement,
                                   Markus

-- 
*  Markus Mottl              |  University of Economics and       *
*  Department of Applied     |  Business Administration           *
*  Computer Science          |  Vienna, Austria                   *
*  mottl@miss.wu-wien.ac.at  |  http://miss.wu-wien.ac.at/~mottl  *