> I confirm that ocamlopt/AIX works well (thanks to Christoph). 
> 
> The best solution is maybe to understand why ocamlopt cannot 
> be built ?

It's a long time since I worked on that. 

I suspected that ld, didn't export all needed symbols. 
Playing with linker flags didn't help.

With an older version (3.09.3) I also cannot load unix.cma.
I get this error message:

  Cannot load required shared library dllunix.
  Reason: dynamic loading not supported on this platform.

So in config/s.h I defined for 3.11.0

#define SUPPORT_DYNAMIC_LINKING

and tried to fix the compiler/linker flags in config/Makefile.
The linker is called with -bexpall, but as you can see, it doesn't solve the
case.

Regards,
Christoph Bauer

Ceterum censeo Ocaml 3.11.2 Issue #4844, #4034 et #4644 includam esse