How does partition_manager.cmake get invoked such that its mergehex call is always the last step?

[Anthony Ambuehl]

NCS 2.9.1

NRF52840

Sysbuild but with only a single image (no bootloader)

I've been trying to figure out how to change the merged.hex output and how to perform additional steps after the merged.hex is generated.

I was finally able to track down the generation of merged.hex to the partition_manager function in nrf/cmake/sysbulid/partition_manager.cmake  I'm able to change the name of the merged.hex file by modifying the variable ${merged}  in this code:

set(merged zephyr-merged${merged_suffix})
set(MERGED ZEPHYR-MERGED${MERGED_SUFFIX})

Within the cmake function partition_manager, this command is added:

add_custom_command(
OUTPUT ${CMAKE_BINARY_DIR}/${container}.hex
COMMAND
${PYTHON_EXECUTABLE}
${ZEPHYR_BASE}/scripts/build/mergehex.py
-o ${CMAKE_BINARY_DIR}/${container}.hex
${${container}overlap_arg}
${${container}hex_files}
DEPENDS
${${container}targets}
${${container}hex_files}
)

Which has a corresponding custom target

add_custom_target(
${container}_hex
ALL DEPENDS
${CMAKE_BINARY_DIR}/${container}.hex
)

However I'm still confused by how these partition_manager targets are not usable from my project's CMakeLists.txt.  For example how can I make an additional custom target that depends on merged_hex.   Is this a different cmake run after the POST_BUILD that doesn't include the app CMakeLists.txt?

As well, there is this code which may be unrelated, but I'm not sure what it does:

if ("${container}" STREQUAL "merged")
update_runner(IMAGE ${DEFAULT_IMAGE} HEX ${CMAKE_BINARY_DIR}/${container}.hex)
endif()

[Einar Thorsrud]

Hi,

I am sorry for the late reply. I am checking internally, but so far I have not been able to find a simple way to achieve this. Can you buypass the problem by wrapping the build in a shell script you write where you first call make, and then do post build processing afterwards in the script?

[Anthony Ambuehl]

The client has requested a cmake build target that bundles many of the generated files into a release package.  They aren't comfortable with the idea that we can't achieve this within the cmake infrastructure.  Specifically they point out that they were able to do with in NCS 2.5 before sysbuild was introduced, and I would need to give them some explanation of why its not possible any longer.

[Einar Thorsrud]

Hi,

I understand. It is currently not suppoerted though, and I do not have a specific advice on how to achieve this at the moment. I have forwarded it internally, but for now my only recomendation is to solve this in another way.