make.txt

main.c

#include <stdio.h>
#include <caml/callback.h>

extern int fib(int n);
extern char * format_result(int n);

int main(int argc, char ** argv)
{
  int result;

  /* Initialize OCaml code */
  caml_startup(argv);
  /* Do some computation */
  result = fib(10);
  printf("fib(10) = %s\n", format_result(result));
  return 0;
}

Makefile

# This works
# mod.ml is some ocaml code
# modwrap.c is a wrapper which calls the registered callbacks
# libasmrun is a runtime library
simplewrapper:
	ocamlopt -output-obj -o modcaml.o mod.ml
	ocamlc -c modwrap.c ;\
	cp `ocamlc -where`/libasmrun.a libmod.a && chmod +w libmod.a ;\
	ar r libmod.a modcaml.o modwrap.o
main:
	 cc -o prog -I `ocamlc -where` main.c libmod.a

# Now has the compiler another mode 
# -output-complete-obj
# That includes the runtime library directly into modcaml.o
simplewrapper2:
	ocamlopt -output-complete-obj -o modcaml.o mod.ml
	ocamlc -c modwrap.c ;\
	ar rcs libmod.a modcaml.o modwrap.o
main2:
	 cc -o prog -I `ocamlc -where` main.c libmod.a
# BUT now can I not compile the main file anymore.
# Error:
# Undefined symbols for architecture x86_64:
#  "_caml_code_area_end", referenced from:
#      _segv_handler in libmod.a(modcaml.o)
#  "_caml_code_area_start", referenced from:
#      _segv_handler in libmod.a(modcaml.o)
#  "_caml_startup", referenced from:
#      _main in main-bd2140.o
#     (maybe you meant: _caml_startup__data_end, _caml_startup__data_begin , _caml_startup__frametable , _caml_startup__code_end , _caml_startup__code_begin )
#  "_caml_system__code_end", referenced from:
#      _segv_handler in libmod.a(modcaml.o)
# ld: symbol(s) not found for architect 86_64

did you fix this? I'm getting the same error :P