Setting KConfig variables in CMakeLists.txt not working with sysbuild

Question

Prior to moving to sysbuild, we were dynamically settings a CONFIG_ variable in our `CMakeLists.txt` based on the board passed to west. And this was working fine.

if (BOARD MATCHES "^ourboard") 
 set (CONFIG_MEMFAULT_NCS_HW_VERSION " \" A9.1 \" " CACHE INTERNAL "" ) 
 elseif (BOARD MATCHES "^nrf9151dk" ) 
 set (CONFIG_MEMFAULT_NCS_HW_VERSION " \" nRF9151DK \" " CACHE INTERNAL "" ) 
 else () 
 message (FATAL_ERROR "No hardware BOARD has been set for this build." ) 
 endif ()

After upgrading to nRFSDK 2.9.0 and using sysbuild, this no longer works. In fact, `BOARD` variable isn't even available in `CMakeLists.txt`. I tried replacing that part with `if (1)` but the new values never make it into the `.config` file (although I can see them in the CMakeCache.txt). 
 
 One way I found to make this work is to put this into `sysbuild.cmake` but this feels wrong because ` CONFIG_MEMFAULT_NCS_HW_VERSION` is only needed in the app image and doesn't need to be available to mcuboot. 
 
 What's the proper way to handle this? Am I missing something? 
 
 Thanks, 
 
 Konstantin

Mariano Goluboff · Accepted Answer

Hi Konstantin, 
 I think this is covered by the default Kconfig namespacing in sysbuild: 
 https://docs.zephyrproject.org/latest/build/sysbuild/index.html#kconfig-namespacing 
 
 The following line: 
 Konstantin Klitenik said: set (CONFIG_MEMFAULT_NCS_HW_VERSION " \" nRF9151DK \" " CACHE INTERNAL "" ) 
 Since it's not namespaced, it should be propagated only to the main Zephyr application. 
 You can expressly namespace it as well. If your app image is named myapp, you could change the above to: 
 set(myapp_CONFIG_MEMFAULT_NCS_HW_VERSION "\"nRF9151DK\"" CACHE INTERNAL "") 
 
 Mariano 
 
 [Edit: I mean that it should be ok to have in sysbuild.cmake]

Setting KConfig variables in CMakeLists.txt not working with sysbuild

Top Replies