NCS 2.9.0 - sysbuild - mcuboot - using board specific config requests for general "prj.conf"?

[Achim Kraus]

NCS 2.9.0

Adding mcuboot to sysbuild and using "sysbuild/mcuboot.conf" works as described in Academy exercise-1-configuring-extra-image .

But if I want to use a board specifc config, e.g. using "sysbuild/mcuboot/boards/thingy91_nrf9160.conf", I get

-- Board: thingy91, qualifiers: nrf9160
CMake Error at /home/achim/ncs/v2.9.0/zephyr/cmake/modules/extensions.cmake:2923 (message):
  No prj.conf file(s) was found in the

To fix that, I use a "sysbuild/mcuboot/prj.conf".

Is that the right way? 

If yes, which "prj.conf" should be copied into that folder? 

I used one from the application samples, but I miss to find some documentation about that.

[Sigurd]

Hi!

But if I want to use a board specifc config, e.g. using "sysbuild/mcuboot/boards/thingy91_nrf9160.conf", I get

This looks correct. See how it's done e.g. here: https://github.com/nrfconnect/sdk-nrf/tree/main/applications/connectivity_bridge/sysbuild/mcuboot/boards

-- Board: thingy91, qualifiers: nrf9160
CMake Error at /home/achim/ncs/v2.9.0/zephyr/cmake/modules/extensions.cmake:2923 (message):
  No prj.conf file(s) was found in the

To fix that, I use a "sysbuild/mcuboot/prj.conf".

You likely need a prj.conf in <sysbuild/mcuboot> as well. If you only have board specific things you want to set, i.e. only have thingy91_nrf9160.conf, I think you can leave the sysbuild/mcuboot prj.conf empty. (but the file likely needs to be present anyways).

[Achim Kraus]

Thanks for the fast reply.

> You likely need a prj.conf in <sysbuild/mcuboot> as well. 

The question will be why?

The project specific stuff goes to "sysbuild/mcuboot.conf", the project & board specific stuff to "sysbuild/mcuboot/boards/<board>_<cpu>.conf". For me this looks more like something not considered, rather than really be intended.

> I think you can leave the sysbuild/mcuboot prj.conf empty

The build then fails with an empty "prj.conf" caused by config warnings.

"warning: FLASH_MAP (defined at subsys/storage/flash_map/Kconfig:10) has direct dependencies FLASH_HAS_DRIVER_ENABLED with value n, but is currently being y-selected by the following symbols:
 - MCUBOOT_DEVICE_SETTINGS (defined at ..../ncs/v2.9.0/bootloader/mcuboot/boot/zephyr/Kconfig:995), with value y, direct dependencies y (value: y)"

So, I guess for now it should be clear, which "prj.conf" should be used.

And for the future, if this is an issue, which will change in a future version.