Force west to NOT fully rebuild project

[Farhang]

Hi Nordic engineers,

I am using west to build the nRF NCS, my own project which is adopted from samples. Using Powershell (win10) to run west commands as below.

I need to do quick builds but west build -b with the following arguments keeps rebuilding everything:

west build -p=never -b nrf52840dk_nrf52840 -d <build_dir> -- -DBOARD_ROOT=<Board_root_dir> -DCMAKE_BUILD_TYPE=<build_type> -DZEPHYR_TOOLCHAIN_VARIANT=gnuarmemb -DGNUARMEMB_TOOLCHAIN_PATH="C:\gnuarm\gcc"

I set the pristine option to "never" as you can see above, and it has no effect, it still rebuilds everything, which takes quite some time....

Any idea how I can achieve a simple compile and build (i.e. only sources that have changed ) ?

[Carl Richard]

Hello, Farhang!

West should only do a full rebuild when it's required, for example when the prj.conf or overlays are changed. Can you confirm that the only changes you have made when this occurs are in .h and .c source files?

Best regards,
Carl Richard

[Farhang]

Yes only a C file has changed in this example. 

Even if nothing has changed it will do a full rebuild.

Could there be something in cmake,  proj.cfg or other configuration (e.g. west config) that forces a full rebuild?

[Carl Richard]

Hi again!

I did some testing and I manage to reproduce your behavior when specifying "DCMAKE_BUILD_TYPE". Could you try to omit that from the build command? Kconfig can be used for adjusting optimization if that is desired.

Best regards,
Carl Richard

[Farhang]

Thanks Carl, 

I need to define project specific configuration (e.g. for two different board types) via build type argument.

is that not a recommended approach? what is the alternative?

I have one main prj.conf and then each build type has its own extra configuration that is appended via the cmake file.

[Carl Richard]

Hello!

If you have different configurations for different board types the recommended approach is to make custom board files for the boards. They can then be configured individually using <board_name>.conf and <board_name>.overlay files. 

Alternatively it's also possible to merge custom configuration and overlay files into the project using the One-Time CMake Arguments DTC_OVERLAY_FILE and DOVERLAY_CONFIG.

Best regards,
Carl Richard