Commands for cross-compiling Linux kernel for Raspberry Pi 3, 4

jjs-cross-compile-linux-kernel-rpi3b.txt

## Cross-compile Linux kernel for Raspberry Pi 3B
## This is for VM with a username “jjs” 
## Cross-compiler is installed at /home/jjs/rp_tool/
## SD card mount paths are for sdb1 and sdb2 

KERNEL=kernel7 

make ARCH=arm CROSS_COMPILE=/home/jjs/rp_tool/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin/arm-linux-gnueabihf- bcm2709_defconfig 
make ARCH=arm CROSS_COMPILE=/home/jjs/rp_tool/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin/arm-linux-gnueabihf- zImage modules dtbs -j 6 
 
sudo mount /dev/sdb1 mnt/fat32
sudo mount /dev/sdb2 mnt/ext4

sudo cp mnt/fat32/$KERNEL.img mnt/fat32/$KERNEL-backup.img
sudo cp arch/arm/boot/zImage mnt/fat32/$KERNEL.img
sudo cp arch/arm/boot/dts/*.dtb mnt/fat32/
sudo cp arch/arm/boot/dts/overlays/*.dtb* mnt/fat32/overlays/
sudo cp arch/arm/boot/dts/overlays/README mnt/fat32/overlays/ 
sudo make ARCH=arm CROSS_COMPILE=/home/jjs/rp_tool/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin/arm-linux-gnueabihf- INSTALL_MOD_PATH=mnt/ext4 modules_install

sudo umount mnt/fat32
sudo umount mnt/ext4

jjs-cross-compile-linux-kernel-rpi4.txt

## Cross-compile Linux kernel for Raspberry Pi 4
## This is for VM with a username “jjs” 
## Cross-compiler is installed at /home/jjs/rp_tool/
## SD card mount paths are for sdb1 and sdb2 

KERNEL=kernel7l 

make ARCH=arm CROSS_COMPILE=/home/jjs/rp_tool/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin/arm-linux-gnueabihf- bcm2711_defconfig 
make ARCH=arm CROSS_COMPILE=/home/jjs/rp_tool/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin/arm-linux-gnueabihf- zImage modules dtbs -j 6 
 
sudo mount /dev/sdb1 mnt/fat32
sudo mount /dev/sdb2 mnt/ext4

sudo cp mnt/fat32/$KERNEL.img mnt/fat32/$KERNEL-backup.img
sudo cp arch/arm/boot/zImage mnt/fat32/$KERNEL.img
sudo cp arch/arm/boot/dts/*.dtb mnt/fat32/
sudo cp arch/arm/boot/dts/overlays/*.dtb* mnt/fat32/overlays/
sudo cp arch/arm/boot/dts/overlays/README mnt/fat32/overlays/ 
sudo make ARCH=arm CROSS_COMPILE=/home/jjs/rp_tool/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin/arm-linux-gnueabihf- INSTALL_MOD_PATH=mnt/ext4 modules_install

sudo umount mnt/fat32
sudo umount mnt/ext4

Reference: https://www.raspberrypi.org/documentation/linux/kernel/building.md