Custom implementation for a source file in the NRF connect SDK/ Zephyr

[Devanshu5]

Hi,

I need to make a few changes in the nRF Connect SDK's (particularly Zephyr's) source files to achieve certain functionality. I have made these changes in the SDK folder itself and tested the implementation and it works fine for us.

I now want a way by which I would be able to tell the CMAKE build system to ignore a particular source file in the SDK and use my custom source file instead, which I have placed in my project folder. I want to do this so that I don't have to provide a patch to all the developers in my team and I want to easily upgrade SDK as and when they are available. Our project is based on the matter-lock example provided by Nordic - NCS v2.1.0.

Path of the source file - C:\ncs\v2.1.0\zephyr\subsys\mgmt\mcumgr\lib\cmd\img_mgmt\src\zephyr_img_mgmt.c

Things that I have tried:

I have tried to make changes in the CMakeLists.txt located in my project to be able to do this. I added the following lines:

    get_filename_component(ZEPHYR_IMG_MGMT $ENV{ZEPHYR_BASE}/subsys/mgmt/mcumgr/lib/cmd/img_mgmt/src/zephyr_img_mgmt.c ABSOLUTE)

    list(REMOVE_ITEM SOURCES "${ZEPHYR_IMG_MGMT}")

    #list(REMOVE_ITEM lib_srcs "${ZEPHYR_IMG_MGMT}")

    

I have also added following line to add the source file located in my project folder:

     target_sources(app PRIVATE src/zephyr_img_mgmt.c)

 

But this gives me errors as it finds multiple definitions from both my project's source file and the SDK's source file. It isn't excluding the SDK's source file. Please help me with this.

If I comment the src/zephyr_img_mgmt.c in the CMakeLists.txt located at C:\ncs\v2.1.0\zephyr\subsys\mgmt\mcumgr\lib\cmd\img_mgmt the build system does not include the source file from the SDK and builds/works properly with the source file located in my project folder.

Screen-shot of how I have commented the source file in CMakeLists.txt:

But this change is again done in the SDK, and I don't want that.

Is there a way in which I can make the build system ignore this source file from SDK and instead use my own custom implementation? 

[Saleh]

As you are modifying the Zephyr stack, it means you'll have a custom implementation of Zephyr at the end. Each time you run "west update" command, it will try to override those changes.

If you wanna keep your changes, you should make a fork out of the origin project and maintain your custom one. It will be your responsibility to keep it updated with the origin project (github tools will helps you). Your team should use this forked version instead of the original one.

[Devanshu5]

Hi,

 

Thank you for taking the time and replying to my question. Creating a Fork is always an option that we can go ahead with if we don't find a solution. I have created this ticket to understand/explore ways in which I can avoid creating a fork and somehow make changes in CMakeLists.txt to include my source file in my project instead of SDK's source file. I have made the change in only one source file and hence I want to avoid creating a fork and maintaining it.

 

Regards,

Devanshu Agarwal

[Devanshu5]

Kaushik Parsana Prashant Humbre creightoncca  Yuelin.Li 

FYI / FYR

[Doug Shuffield]

Hello Devanshu,

We are wanting to do something similar.  Did you ever find a satisfactory means to do this?

[Doug Shuffield]

For any who need to do this in the future, I found a way to overwrite an NCS file with the CMake command "file".  I added this to my CMakeLists.txt:

file(COPY ${CMAKE_SOURCE_DIR}/src/gzll_glue.c
     DESTINATION $ENV{ZEPHYR_BASE}/../nrf/subsys/gazell)

This will copy the modified gzll_glue.c file from my src directory to the appropriate place in the NCS directory. Note, this will overwrite the file in the NCS directory so you should make a backup of the original.

Doug