Le 20-12-21 15:32:13, ygrek a écrit :
> On Mon, 21 Dec 2020 22:03:32 +0100
> Christophe Raffalli <christophe@raffalli.eu> wrote:
>
> > static void protect_callback(char *name, value f, value v1)
> > {
> >   caml_acquire_runtime_system();
> >   {
> >     CAMLparam2(f,v1);
> >     CAMLlocal1(res);
> >     res = caml_callback_exn(f, v1);
> >     if(Is_exception_result(res))
> >       fprintf(stderr, "Egl.main_loop: "
> > 	      "WARNING: %s raised an exception\n", name) ;
> >     CAMLdrop;
> >   }
> >   caml_release_runtime_system();
> > }
>
> Values pointed by f and v1 may be moved by gc prior to caml_acquire_runtime_system call, but the values passed to the function (in registers or via stack)
> will be pointing to old locations still. IOW need to pass ocaml values here by-reference (where the reference itself is registered with gc somehow), not by-value.
>
> --

Many thanks, this is clearly my problem and sounds completely logical! I should have see this myself!

Many the documentation should say this and show an example of callback acquiring the runtime system ? I update my issue in github.

Thanks again,
Christophe