Configure Linux Kernel

• Kernel-specific optimizations: minimal modules, kernel parameters, initrd, and others
• Building a reduced kernel (with less modules for examples) for faster boot time

Please note in our usecase, we used the BeagleBoard BeaglePlay as our reference.

We used Linux kernel version 6.6, you can check some of our sources here

Generating a .cfg file for Linux Kernel configuration

You may want to customize your Linux Kernel configuration with a configuration fragment (called cfg).

An easy way to do that is to:

cd ${KERNEL_SOURCE}
cp .config .config.sav
make menuconfig
diff --unchanged-line-format= --old-line-format= --new-line-format="%L" ./.config.sav ./.config > 01-my-file.cfg

Merge a .cfg file to Linux Kernel configuration

If you want to merge a cfg configuration fragment to your Linux Kernel configuration just:

scripts/kconfig/merge_config.sh -m -r .config 01-my-file.cfg

If you have more than one cfg files:

for CFG in *.cfg; do
  scripts/kconfig/merge_config.sh -m -r .config ${CFG}
done

Test your new Kernel

After the build of your kernel packages, you can simply copy them to your board and install them.

scp ./kernel-modules-extra-${VER}-${REL}.rpbatz.aarch64.rpm \
    ./kernel-modules-${VER}-${REL}.rpbatz.aarch64.rpm \
    ./kernel-core-${VER}-${REL}.rpbatz.aarch64.rpm \
    ./kernel-${VER}-${REL}.rpbatz.aarch64.rpm \
    root@X.X.X.X:/;
ssh root@X.X.X.X dnf install -y /*; 

Disable unused drivers

Disabling unused drivers is a key step in optimizing the boot time of a Linux Kernel, especially for embedded or industrial systems where specific hardware configurations are well-defined.

Use make menuconfig to go to the configuration of the Kernel!

This requires to already have your defconfig declared and used. For more reference, go here!

So our goal is to disable unnecessary drivers. Navigate to Device Drivers and uncheck drivers not required for the system. See our examples below!

Tips for safe optimization

• Start with known requirements
  • Clearly define the hardware and peripherals your system uses
• Disable features incrementally
  • Test the system after disabling each set of features to verify functionality