From 1248a2e20e3f2ea9e28d9f1f45fed579e9b24836 Mon Sep 17 00:00:00 2001
From: Jonathan Pallant <jonathan.pallant@ferrous-systems.com>
Date: Mon, 8 Jun 2026 09:19:04 +0100
Subject: [PATCH 1/2] Make EL1 and EL2 MPUs !Send

---
 aarch32-cpu/src/pmsav8.rs | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/aarch32-cpu/src/pmsav8.rs b/aarch32-cpu/src/pmsav8.rs
index 5508fa8..47984fa 100644
--- a/aarch32-cpu/src/pmsav8.rs
+++ b/aarch32-cpu/src/pmsav8.rs
@@ -6,6 +6,8 @@
 //!
 //! [armv8r]: https://developer.arm.com/documentation/ddi0568/latest/
 
+use core::marker::PhantomData;
+
 use arbitrary_int::{u26, u3};
 
 use crate::register;
@@ -28,7 +30,12 @@ pub enum Error {
 }
 
 /// Represents our PMSAv8-32 EL1 MPU
-pub struct El1Mpu();
+///
+/// This type is not [Send] because it is a per-core type and should not be moved across
+/// cores on an SMP system.
+pub struct El1Mpu {
+    _phantom: PhantomData<*const u8>,
+}
 
 impl El1Mpu {
     /// Create an MPU handle
@@ -38,7 +45,9 @@ impl El1Mpu {
     /// Only create one of these at any given time, as they access shared
     /// mutable state within the processor and do read-modify-writes on that state.
     pub unsafe fn new() -> El1Mpu {
-        El1Mpu()
+        El1Mpu {
+            _phantom: PhantomData,
+        }
     }
 
     /// How many MPU regions are there?
@@ -199,7 +208,12 @@ impl El1Mpu {
 }
 
 /// Represents our PMSAv8-32 EL2 MPU
-pub struct El2Mpu();
+///
+/// This type is not [Send] because it is a per-core type and should not be moved across
+/// cores on an SMP system.
+pub struct El2Mpu {
+    _phantom: PhantomData<*const u8>,
+}
 
 impl El2Mpu {
     /// Create an EL2 MPU handle
@@ -209,7 +223,9 @@ impl El2Mpu {
     /// Only create one of these at any given time, as they access shared
     /// mutable state within the processor and do read-modify-writes on that state.
     pub unsafe fn new() -> El2Mpu {
-        El2Mpu()
+        El2Mpu {
+            _phantom: PhantomData,
+        }
     }
 
     /// How many EL2 MPU regions are there?
@@ -407,6 +423,7 @@ pub struct El1Region {
 
 // Creating a static Region is fine - the pointers within it
 // only go to the MPU and aren't accessed via Rust code
+unsafe impl Send for El1Region {}
 unsafe impl Sync for El1Region {}
 
 /// Configuration for the PMSAv8-32 EL2 MPU
@@ -454,6 +471,7 @@ pub struct El2Region {
 
 // Creating a static El2Region is fine - the pointers within it
 // only go to the MPU and aren't accessed via Rust code
+unsafe impl Send for El2Region {}
 unsafe impl Sync for El2Region {}
 
 /// Describes the memory ordering and cacheability of a region

From 112b42d1644edeb4239bb0feb5e0520d3e2b0585 Mon Sep 17 00:00:00 2001
From: Jonathan Pallant <jonathan.pallant@ferrous-systems.com>
Date: Mon, 8 Jun 2026 10:24:27 +0100
Subject: [PATCH 2/2] Make PMSAv7 MPU !Send

---
 aarch32-cpu/src/pmsav7.rs | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/aarch32-cpu/src/pmsav7.rs b/aarch32-cpu/src/pmsav7.rs
index 0db24a8..e6c8b8a 100644
--- a/aarch32-cpu/src/pmsav7.rs
+++ b/aarch32-cpu/src/pmsav7.rs
@@ -5,6 +5,8 @@
 //!
 //! [armv7]: https://developer.arm.com/documentation/ddi0406/latest
 
+use core::marker::PhantomData;
+
 use crate::register;
 
 use arbitrary_int::{u2, u3};
@@ -23,7 +25,12 @@ pub enum Error {
 }
 
 /// Represents our PMSAv7 MPU
-pub struct Mpu();
+///
+/// This type is not [Send] because it is a per-core type and should not be moved across
+/// cores on an SMP system.
+pub struct Mpu {
+    _phantom: PhantomData<*const u8>,
+}
 
 impl Mpu {
     /// Create an MPU handle
@@ -33,7 +40,9 @@ impl Mpu {
     /// Only create one of these at any given time, as they access shared
     /// mutable state within the processor and do read-modify-writes on that state.
     pub unsafe fn new() -> Mpu {
-        Mpu()
+        Mpu {
+            _phantom: PhantomData,
+        }
     }
 
     /// How many MPU instruction regions are there?