How do you non-interactively turn on features in a Linux kernel .config file?

Question

I have a situation where our software needs to work with several different Linux kernel distributions / kernel trees. (including Android forks)

In trying to automate our build process, I am finding that some of the defconfig files for particular builds we need to support do not include the kernel modules we depend on.

For example, let's imagine I need an option called XXX in my .config. For some dependencies, I can do something like this:

sed -i 's/# CONFIG_XXX is not set/CONFIG_XXX=m/' .config

For others, it's not so easy since the dependency may span multiple lines of .config statements.

Is there a more supported way to do this non-interactively, or am I stuck writing a more complex search-and-replace script?

Answer 1

To do a series of simple flipping of a single config while updating any and all config dependencies:

Single Option approach

./scripts/config --set-val CONFIG_OPTION y
./scripts/config --enable CONFIG_BRIDGE
./scripts/config --enable CONFIG_MODULES
./scripts/config --disable CONFIG_X25
./scripts/config --module CONFIG_NFT
make oldconfig
(updates dependencies; may prompt with new dependencies, but old deps silently goes away)

Multiple-File Merge approach

If you have several small snippets of .config-* files that you want to selectively merge into the main .config file, execute:

# Merge IP fragment CONFIG_ settings into the main .config file
./scripts/kconfig/merge_config.sh .config .config-fragment
# Merge  Notebook HW-specific CONFIG_ settings into main .config file
./scripts/kconfig/merge_config.sh .config .config-notebook-toshiba

# Auto-add/auto-remove CONFIG_ dependencies
make oldconfig

References

• https://www.kernel.org/doc/html/latest/kbuild/kconfig.html#nconfig-mode
• https://stackoverflow.com/questions/27090431/linux-kconfig-command-line-interface/70728869#70728869