How to add custom config lines to a Kconfig fragment?

RE: How to add custom config lines to a Kconfig fragment?

Hieu — Wed, 23 Jul 2025 07:35:19 GMT

[quote user="Nick_RA"]What you seem to have done is made a config for the application; what I need to do is add extra fragments to different build configurations so each build has its own Kconfig add-on.[/quote]

Ah I see. Adding a new Kconfig is exactly what the snippet you shared did, so I thought that was the intention.

If you want Kconfig fragment, you can just create a new .conf file with similar syntax to the familiar prj.conf, like this.

devzone.nordicsemi.com/.../c348718_5F00_custom_5F00_kconfig_5F00_250723_5F00_01.zip

[quote user="Nick_RA"]I wonder what you mean by wrong file type? Does it need to be a particular name and extension?[/quote]

Yes. Both file name and extension are significant to the build system. Please refer to both NCS and Zephyr application development guides:

NCS: Application development
Zephyr: Developing with Zephyr

RE: How to add custom config lines to a Kconfig fragment?

Nick_RA — Tue, 22 Jul 2025 16:39:34 GMT

I wonder what you mean by wrong file type? Does it need to be a particular name and extension?

What you seem to have done is made a config for the application; what I need to do is add extra fragments to different build configurations so each build has its own Kconfig add-on.

I saved your config into a text file, then added it to a test build configuration as an Extra Kconfig fragment like so:

source "Kconfig.zephyr"

menu "Custom Kconfig file"

config FOO
  bool "foobar"
  default n

endmenu

but this gives the same result.

(by the way, are the source, menu/endmenu required?)

RE: How to add custom config lines to a Kconfig fragment?

Hieu — Tue, 22 Jul 2025 12:12:08 GMT

Hi Nick_RA,

I wonder if you are using the wrong file type. Here is a setup I just tested in NCS v3.0.2 based on just Hello World sample.

devzone.nordicsemi.com/.../c348718_5F00_custom_5F00_kconfig_5F00_250722_5F00_01.zip

Hieu