Re: Help needed for debugging OCaml failure on m68k

[Stéphane Glondu <glondu@debian.org>]

Hi Adrian and all,

Le 19/06/2024 à 14:04, John Paul Adrian Glaubitz a écrit :
> > [...] the address of
> > caml_state (a thread local variable) changes unexpectedly (goes from
> > 0x402e5fac to 0x402e7454) after the following goto:
> >
> >   
> > https://salsa.debian.org/ocaml-team/ocaml/-/blob/debian/experimental/runtime/interp.c?ref_type=heads#L295
> >
> > which leads to:
> >
> >   
> > https://salsa.debian.org/ocaml-team/ocaml/-/blob/debian/experimental/runtime/interp.c?ref_type=heads#L819
> >
> > ...confirmed by adding:
> >
> >     fprintf(stderr, "&caml_state = %p\n", &caml_state);
> >
> > before the goto and after the "Instruct(BRANCH):".
>
> Hmm, I guess then maybe Andreas Schwab or Geert Uytterhoeven might have an idea what
> the problem with the TLS variable is. I'll CC both.

I noticed that &caml_state changes when pc changes. Looking further, pc 
is a register variable pinned to a5. I guess this conflicts with the 
implementation of TLS...?

I've removed the register pin and launched a build, and it goes past the 
problematic point. We'll see how it goes...


Cheers,

--
Stéphane