Emulate_Alpine_RPi.md

Emulate Apline for RPi with QEMU

Instructions for Ubuntu 20.04LTS and QEMU installed from APT Based on Alpine Wiki

Install syslinux sudo apt-get install syslinux -y

Make an empty disk image sudo dd if=/dev/zero of=./alpine_rpi.img bs=1M count=512

Attach image as a loop device sudo losetup -P -f ./alpine_rpi.img

Find the created loop device id sudo fdisk -l

/dev/loopX will have to be replaced by the proper loop device id (/dev/loop0 in my case) in the next steps

Make a primary FAT32 parition on the device

sudo fdisk -w always /dev/loopX <<EOF
  o
  n
  p
  1
  2048
  -0
  t
  0c
  a
  w
EOF

Format the newly created partition sudo mkdosfs -F32 /dev/loopXp1

Copy Linux MBR to the device sudo dd bs=440 count=1 conv=notrunc if=/usr/lib/syslinux/mbr/mbr.bin of=/dev/loopX

Install syslinux on device sudo syslinux /dev/loopXp1

Mount the device to the host sudo mkdir /media/alpine_rpi && sudo mount /dev/loopXp1 /media/alpine_rpi

Download Alpine archive: wget https://dl-cdn.alpinelinux.org/alpine/v3.17/releases/aarch64/alpine-rpi-3.17.2-aarch64.tar.gz

Untar the archive into the mounted image sudo tar -p -s --atime-preserve --same-owner --one-top-level=/media/alpine_rpi -zxvf ./alpine-rpi-3.17.2-aarch64.tar.gz

Launch the emulator

sudo qemu-system-aarch64 \
        -nographic \
        -machine raspi3b \
        -cpu cortex-a53 \
        -drive file=./alpine_rpi.img,format=raw,readonly=off \
        -dtb /media/alpine_rpi/bcm2710-rpi-3-b.dtb \
        -m 1G \
        -smp 4 \
        -device usb-net,netdev=net0 \
        -netdev user,id=net0 \
        -kernel /media/alpine_rpi/boot/vmlinuz-rpi \
        -initrd /media/alpine_rpi/boot/initramfs-rpi \
        -append "modules=loop,squashfs,sd-mod,usb-storage quiet console=ttyAMA0 modloop=/boot/modloop-rpi"

That's it !