How to configure a custom MCUBoot in NCS v2.9.0

[Leo]

hi,

  I need to develop some custom features for MCUBoot, so I transplanted the entire bootloader folder from NCS into my project. In the project's root directory, I added list(APPEND ZEPHYR_EXTRA_MODULES "${CMAKE_CURRENT_SOURCE_DIR}/bootloader/mcuboot") in the CMakeLists.txt file to include MCUBoot in the project. However, after the compilation, I found that the actual MCUBoot being compiled is the one from NCS, not my custom MCUBoot.

   Try modifying the sysbuild.cmake file according to the example in v2.9.0\zephyr\samples\sysbuild\hello_world, and add the following content.

set(image mcuboot)
ExternalZephyrProject_Add(
    APPLICATION ${image}
    SOURCE_DIR ${CMAKE_CURRENT_LIST_DIR}/bootloader/mcuboot/boot/Zephyr/
    APP_TYPE BOOTLOADER
  )

Error message：ExternalZephyrProject_Add(APPLICATION mcuboot ...) already exists.

How should I configure the system to compile a custom mcuboot ?
sdk：NCS v2.9.0
soc：nrf9160

[Sigurd Hellesvik]

Hi,

MCUboot is tightly coupled with the nRF Connect SDK. Because of this, it is not trivial to add it as a custom sysbuild image.

If you want add custom features to MCUboot, I suggest that you fork MCUboot.
See Adding your own code.

Then use MCUboot as normal, with SB_CONFIG_BOOTLOADER_MCUBOOT=y

Regards,
Sigurd Hellesvik

[Leo]

In NCS 2.6.1, it's possible to directly specify using list(APPEND ZEPHYR_EXTRA_MODULES "${CMAKE_CURRENT_SOURCE_DIR}/bootloader/mcuboot"), but why doesn't it work in the new version?

[Sigurd Hellesvik]

Try to do that in sysbuild.cmake in newer versions. Does that work?

[Leo]

It doesn't work, still compiling MCUBoot in NCS.

[Sigurd Hellesvik]

I asked internally, and they say that you would the list(APPEND) method will not work with Sysbuild.

Instead, you can use west.yml to add your code, as explained in Workflow 3 or Workflow 4 in  Adding your own code.