Building:
-
Make sure you have the neccessary packages installed:
build-essential bc bison flex libncurses-dev libssl-dev libelf-dev -
Download the appropriate toolchain: https://android.googlesource.com/platform/prebuilts/gcc/linux-x86/arm/arm-linux-androideabi-4.9/+archive/refs/heads/ndk-release-r21.tar.gz
-
Make a folder, unpack it there:
tar -xf ndk-release-r21.tar.gz -
Apply a small fix:
cd *TOOLCHAIN_DIR* cd bin rm arm-linux-androideabi-gcc ln -s arm-linux-androideabi-gcc-4.9.x arm-linux-androideabi-gcc -
Edit
build_kernel.shto have the right path -
Run
build_kernel.sh
This should result in out/arch/arm/boot/Image
Rename to boot.img-kernel, repack your boot.img with it, and flash it with fastboot.