(** ** Erased X86 machine is safe*)
From mathcomp.ssreflect Require Import ssreflect ssrbool ssrnat ssrfun eqtype seq fintype finfun.
Set Implicit Arguments.
(*NOTE: because of redefinition of [val], these imports must appear after Ssreflect eqtype.*)
Module InitialMemWD.

Lemma mem_valid_drop :
forall (m : mem) (b : block) (lo hi : Z) (p : permission) (m' : mem),
Mem.drop_perm m b lo hi p = Some m' ->
MemoryWD.valid_mem m -> MemoryWD.valid_mem m'.