FRDM-MCXN236 mcuboot

[bottleneck]

Building MCUboot, Device Tree and Zephyr separately on FRDM-MCXN236

I am using the NXP FRDM-MCXN236 board and I am relatively new to Zephyr.

As part of my Zephyr training, I have successfully built and run a basic Zephyr project using Visual Studio Code. I would now like to understand the boot and board bring-up process at a lower level.

My goal is to try building the following components separately:

1. MCUboot

2. Device Tree

3. Zephyr application/kernel

I would then like to understand which parts are actually flashed to the board, flash them separately where possible, and observe the boot sequence.

I feel this would be a useful exercise for understanding board bring-up, bootloaders, Device Tree, Kconfig, linker scripts, and the relationship between MCUboot and the Zephyr application.

I would also like to understand whether Zephyr can be customized in a way similar to the Linux kernel menuconfig workflow.

My environment

• Board: NXP FRDM-MCXN236

• Host OS: Windows 11

• Build environment: Ubuntu 22.04 under WSL2

• Zephyr: 4.4.99

• Python: 3.10.12 currently installed

• West: 1.5.0

• CMake: 4.4.3

• Ninja: 1.10.1

• Zephyr SDK: 1.0.1

My workspace is:

~/zephyr-training/
├── zephyr/
├── mcuboot/
├── my-zephyr-app/
└── workspace/

MCUboot source

I cloned MCUboot separately under:

~/zephyr-training/mcuboot/

The Zephyr-specific MCUboot application is located at:

~/zephyr-training/mcuboot/boot/zephyr/

I found the following relevant CMake files:

mcuboot/boot/zephyr/CMakeLists.txt
mcuboot/boot/zephyr/sysbuild/CMakeLists.txt
mcuboot/boot/bootutil/CMakeLists.txt
mcuboot/boot/bootutil/zephyr/CMakeLists.txt

MCUboot build attempt

I first tried to build the MCUboot Zephyr application using:

cd ~/zephyr-training

west build \
  -b frdm_mcxn236 \
  -s ~/zephyr-training/mcuboot/boot/zephyr \
  -d ~/zephyr-training/build-mcuboot

The intention here is to tell West:

• -b frdm_mcxn236 → build for the FRDM-MCXN236 board

• -s .../mcuboot/boot/zephyr → use the Zephyr MCUboot application as the source

• -d .../build-mcuboot → keep the MCUboot build output separate from my normal Zephyr application

However, the build did not reach the actual CMake compilation stage.

I received this error:

Traceback (most recent call last):
  File "/usr/local/bin/west", line 8, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.10/dist-packages/west/app/main.py", line 1199, in main
    app.run(argv or sys.argv[1:])
  File "/usr/local/lib/python3.10/dist-packages/west/app/main.py", line 278, in run
    self.run_command(argv, early_args)
  File "/usr/local/lib/python3.10/dist-packages/west/app/main.py", line 584, in run_command
    self.run_extension(args.command, argv, self.topdir, manifest=self.manifest,
  File "/usr/local/lib/python3.10/dist-packages/west/app/main.py", line 739, in run_extension
    self.cmd.run(args, unknown, self.topdir, manifest=self.manifest,
  File "/home/umesh/zephyr-training/zephyr/scripts/west_commands/build.py", line 263, in do_run
    self._sanity_check()
  File "/home/umesh/zephyr-training/zephyr/scripts/west_commands/build.py", line 589, in _sanity_check_source_dir
    srcrel = pathlib.Path(self.source_dir).relative_to(
TypeError: PurePath.relative_to() got an unexpected keyword argument 'walk_up'

My Python version is:

python3 --version
Python 3.10.12

and:

west --version
West version: v1.5.0

which python3
/usr/bin/python3

which west
/usr/local/bin/west

It appears that the current Zephyr west build code is using:

Path.relative_to(..., walk_up=True)

which requires a newer Python version.

I also checked:

python3.12 --version

but Python 3.12 is not currently installed.

I tried installing it directly:

sudo apt update
sudo apt install python3.12 python3.12-venv

but Ubuntu 22.04 returned:

E: Unable to locate package python3.12
E: Couldn't find any package by glob 'python3.12'
E: Unable to locate package python3.12-venv
E: Couldn't find any package by glob 'python3.12-venv'

So I am currently trying to resolve the Python/West compatibility issue before continuing with the MCUboot build.

What I would like to understand

Once I get MCUboot building, I would like to proceed step by step and understand:

1. How to build MCUboot separately for FRDM-MCXN236.

2. How the FRDM-MCXN236 Device Tree is selected and compiled.

3. Whether Device Tree can be built/inspected separately from the Zephyr application.

4. How the Zephyr kernel/application is built separately.

5. Which of these are actual flashable binaries and which are build-time configuration.

6. Whether MCUboot can be flashed independently and then the Zephyr application flashed separately.

7. How the MCUboot image layout and application image/slots are defined.

8. How to sign the Zephyr application so that MCUboot can boot it.

9. How to observe and verify the MCUboot → Zephyr boot sequence on the board.

10. How to customize the Zephyr kernel/configuration using something similar to the Linux kernel menuconfig workflow.

My intention is not just to get the application running, but to understand the complete boot flow:

FRDM-MCXN236
      |
      v
   MCUboot
      |
      v
 Zephyr application
      |
      v
 Zephyr kernel / drivers
      |
      v
 Device Tree + Kconfig configuration

I believe doing this manually would help me better understand MCU/SoC startup, bootloader operation, flash layout, Device Tree, Kconfig, linker scripts, and board bring-up.

Any guidance on the correct sequence for doing this on the FRDM-MCXN236 would be appreciated.
MCUBOOT ZEPHYR-OS-EDGE @frdmuser