Proof with eauto with renamings id_renamings val_renamings.
intros.
constructor; constructor;
eauto with id_renamings; unfold id_ren; intros;
repeat match goal with
| [H: context[valid_block_dec ?M ?B] |- _] =>
destruct (valid_block_dec M B); simpl in *
| [H: _ = Some _ |- _] => inv H; clear H
end; auto.
now apply po_refl.
destruct (ZMap.get ofs (Mem.mem_contents m) # b2) eqn:Hget;
constructor.
destruct v0; constructor.
specialize (H _ v _ _ Hget).
simpl in H.
destruct (valid_block_dec m b); simpl; tauto.
Qed.

(** If a memory [m] injects into a memory [m'] then [m'] is at least as big as [m] *)
Lemma weak_mem_obs_eq_nextblock:
forall f m m'
(Hobs_eq: weak_mem_obs_eq f m m'),
(Mem.nextblock m <= Mem.nextblock m')%positive.