Understanding how .config for uboot is generated in buildroot

[Ignatius Rivaldi]

Hi all,

When I edit the config file in BR2_TARGET_UBOOT_CUSTOM_CONFIG_FILE in a
buildroot recipe, how does the config statements from that file got
converted into .config file in u-boot?

The background is that we're using a custom buildroot config file at here:
https://github.com/kubos/kubos-linux-build/tree/master to build u-boot for
a space grade computer. When I added a new config statement
(CONFIG_SD_SWITCH=y) in the BR2_TARGET_UBOOT_CUSTOM_CONFIG_FILE, it doesn't
write the config statement to the .config file in the uboot build repo.

 Unfortunately the company that owns that has been acquired several times
and all the engineers there already left, so I can't just ask them

Thanks
Ignatius