Definition val_inject_opt (j: meminj) (v1 v2: option val) :=
  match v1, v2 with Some v1', Some v2' => val_inject j v1' v2'
  | None, None => True
  | _, _ => False
  end.

Lemma storev_valid_block_2: forall ch m addr v m', Mem.storev ch m addr v = Some m' -> (forall b, Mem.valid_block m' b -> Mem.valid_block m b).