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MPU-Plus™ — ARM Cortex-M MPU Support

MPU-Plus adds support for the ARM Cortex‑M Memory Protection Unit to SMX RTOS, and it can be added to other RTOSes following this example. The Cortex-M v7 MPU is difficult to use and has significant limitations. The primary goal of MPU-Plus is to make using the MPU as easy as possible, while offering as much protection as possible. A key idea of our approach is to allow progressively increasing the security of a system. (See blog Part 5 below for details about this.)


  • Adds strong security to existing and new products.
  • Per-task or task group isolation.
  • Supports privileged ptasks and unprivileged utasks.
  • SWI RTOS API for utasks with restricted services.
  • Direct RTOS API for ptasks with unrestricted services.
  • Switched background mode for improved ptask protection. (new)
  • Supports incrementally improving security.
  • Simple to use and effective protection.

MPU-Plus Press Release

Strong Security Using the Cortex-M MPU


A word from the developer:

Although some RTOSes offer MPU support, little is said about it, suggesting that little was done. I have put a lot of thought into how to make the MPU usable, and I have implemented what is likely the best solution.

Also, there is little documentation from ARM. I have written a series of blogs to explain more about the MPU and how to use it. These are linked above.

While you are here, I encourage you to learn more about SMX RTOS using the links below.

Ralph Moore
smx Architect

For more information, please register or email sales@smxrtos.com.
Indicate your interest in MPU-Plus. Full documentation will be supplied to qualified prospects.


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SMX RTOS Products Page

SMX Learning Kits are free, fully functional releases of the smx kernel for non-commercial use in personal and class projects, proofs of concept, and prototypes. They are available for several low-cost boards that are popular in the DIY / Maker community.

SMX Evaluation Kits are available for a much larger number of evaluation boards and include SMX middleware. They require registration, and a sales person will be in contact. Evaluation Kits are intended to allow developers to work with SMX in order to decide whether to purchase a license for their projects.

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