.. _mpu_test:

Memory Protection Unit (MPU) TEST
#################################

Overview
********
This test provides a set options to check the correct MPU configuration
against the following security issues:

* Read at an address that is reserved in the memory map.
* Write into the boot Flash/ROM.
* Run code located in SRAM.

If the MPU configuration is correct each option selected ends up in an MPU
fault.

Building and Running
********************

This project can be built and executed as follows:

.. zephyr-app-commands::
   :zephyr-app: samples/mpu/mpu_test
   :board: v2m_beetle
   :goals: build flash
   :compact:

Reset the board and you should be able to see on the corresponding
Serial Port the following message:

.. code-block:: console

   ***** BOOTING ZEPHYR OS v1.7.99 - BUILD: Mar  9 2017 13:01:59 *****
   *** MPU test options ***
   1 - Read a reserved address in the memory map
   2 - Write in to boot FLASH/ROM
   3 - Run code located in RAM
   Select an option:

To build the single thread version, use the supplied configuration file for
single thread: :file:`prj_single.conf`:

.. zephyr-app-commands::
   :zephyr-app: samples/mpu/mpu_test
   :board: v2m_beetle
   :conf: prj_single.conf
   :goals: run
   :compact:

To build a version that allows writes to the flash device, edit
``prj.conf``, and follow the directions in the comments to enable the
proper configs.

Sample Output
=============

.. code-block:: console

   ***** BOOTING ZEPHYR OS v1.7.99 - BUILD: May 12 2017 09:47:02 *****
   shell> select mpu_test
   mpu_test> read
   ***** BUS FAULT *****
     Executing thread ID (thread): 0x200003b8
     Faulting instruction address:  0x290
     Precise data bus error
     Address: 0x24000000
   Fatal fault in thread 0x200003b8! Aborting.