build_linux_kernel.md

How to build

• install dependencies

sudo apt install build-essential libncurses-dev bison flex libssl-dev libelf-dev fakeroot dwarves

• download latest kernel from kernel.org in tarball format and extract it

wget https://cdn.kernel.org/pub/linux/kernel/v6.x/linux-6.9.9.tar.xz
tar -xf linux-6.9.9.tar.xz
rm linux-6.9.9.tar.xz

• configure kernel using current kernel config file

cd linux-6.9.9
cp -v /boot/config-$(uname -r) .config

• change config file so that just current loaded kernel modules included in the build to reduce build time

make localmodconfig

• some modification into config file to prevent build failure

scripts/config --disable SYSTEM_TRUSTED_KEYS
scripts/config --disable SYSTEM_REVOCATION_KEYS
scripts/config --set-str CONFIG_SYSTEM_TRUSTED_KEYS ""
scripts/config --set-str CONFIG_SYSTEM_REVOCATION_KEYS ""

• build the kernel

fakeroot make -j $(nproc)

• check build process completed successfully

echo $?

How to install

sudo make modules_install
sudo make headers_install
sudo make install

• get currently installed kernels in grub menu

sudo grub-mkconfig | \
     grep -iE "menuentry 'Ubuntu, with Linux" | \
     awk '{print i++ " : "$1, $2, $3, $4, $5, $6, $7}'

• update /etc/default/grub file (suppose want to set 4th boot entry as default option)

GRUB_DEFAULT="1>4"

• update grub

sudo update-grub

• reboot system to boot new kernel

How to customize

• change OS name in include/linux/uts.h file

#define UTS_SYSNAME "s4eidhp"

• recompile the kernel, install it and reboot