To build source-based kernel: 1. Set CROSS_COMPILE to an appropriate path prefix, e.g., export CROSS_COMPILE=../../cm/prebuilt/linux-x86/toolchain/arm-eabi-4.4.3/bin/arm-eabi- 2. Build kernel and modules: cd kernel; make u1_na_spr_defconfig && make -j 4 && make INSTALL_MOD_PATH=.. INSTALL_MOD_STRIP=1 modules_install; cd .. 3. Copy newly-built modules to initramfs: find lib/modules -name '*.ko' -exec cp -a {} initramfs/lib/modules \; 4. Remove .empty files from initramfs: find initramfs -name '.empty' -exec rm {} + 5. Rebuild final zImage with updated initramfs: cd kernel; make zImage; cd .. The completed kernel is located at kernel/arch/arm/boot/zImage.