Hi,

issue 4145 (http://caml.inria.fr/mantis/view.php?id=4145) has
been closed in the meantime because

    doligez - 2006-11-15 13:19  
   ---------------------------------------------------------------------- 
   Unfortunately, we cannot know which global C roots point to the minor heap,
   since we don't have a write barrier on C variables.

I find this reason not satisfying at all. If a write barrier is
needed, then one could easily stipulate one by providing a
suitable macro CAML_modify_global_root.

With the above line of reasoning it should not be allowed to hold
any ocaml value in a C variable, because a write barrier is
needed for objects that are not in the young generation.

Hendrik