Ex1.

$ git clone --depth 1 https://github.com/raspberrypi/linux.git

$ sudo apt-get install flex
$ sudo apt-get install bison

$ make ARCH=arm help | grep "versatile\|bcm"
$ make ARCH=arm versatile_defconfig

$ vim .config

Ex 2.

$ wget https://ocw.cs.pub.ro/courses/_media/si/laboratoare/linux-arm-5.10.66.patch.txt
$ wget https://ocw.cs.pub.ro/courses/_media/si/laboratoare/config.txt

$ mv linux-arm-5.10.66.patch.txt linux-arm-5.10.66.patch
$ git apply linux-arm-5.10.66.patch

$ make ARCH=arm versatile_defconfig
$ mv config.txt .config

$ export PATH="<path_to_tools>/tools/arm-bcm2708/arm-linux-gnueabihf/bin:$PATH"
$ make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- -j$(nproc) bzImage dtbs
$ qemu-system-arm -M versatilepb -cpu arm1176 -m 256 \
	-drive "file=<path_to_rootfs>/2021-05-07-raspios-buster-armhf-lite.img,if=none,media=disk,format=raw,id=disk0" \
	-device "virtio-blk-pci,drive=disk0,disable-modern=on" \
	-dtb <path_to_dtb>?versatile-pb-buster-5.4.51.dtb \
	-kernel ./arch/arm/boot/zImage \
	-append "root=/dev/vda2" \
	-serial stdio

user: pi
parola: raspberry

$ uname -a

# fisierul .dts este /arch/arm/boot/dts/versatilepb.dts