RE: sysbuild + mcuboot and board specific signature keys

Hung Bui — Fri, 29 Aug 2025 12:57:27 GMT

Hi Andreas,
For setting up custom key, I would suggest to take a look at our tutorial here: https://academy.nordicsemi.com/courses/nrf-connect-sdk-intermediate/lessons/lesson-9-bootloaders-and-dfu-fota/topic/exercise-2-dfu-over-usb-adding-external-flash/

Regarding your request, for more complex applications, we use different configuration folder for each board. You can take a look at our nRF_Desktop application:
https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/applications/nrf_desktop/README.html

\nrf\applications\nrf_desktop

You can find that the configurations including the sysbuild.conf is located in the configuration\{board}\ folder. So each board would has its own sysbuild.conf.

To do that we have this line in CMakeLists.txt :
set(APPLICATION_CONFIG_DIR "${CMAKE_CURRENT_LIST_DIR}/configuration/\${NORMALIZED_BOARD_TARGET}")

and sysbuild\CMakeLists.txt:

set(SB_APPLICATION_CONFIG_DIR "${CMAKE_CURRENT_LIST_DIR}/../configuration/\${NORMALIZED_BOARD_TARGET}")