Scripted generation of Arch Linux ARM image to run in QEMU in an Arch Linux host (x86_64)

prepare.sh

#!/bin/bash
#
# Script to build and run Arch Linux ARM in QEMU inside of Arch Linux (x86_64)
#
# 
# Original how-to and script from:
# * https://gist.github.com/thalamus/561d028ff5b66310fac1224f3d023c12
# * https://git.sr.ht/~whynothugo/m1-vm/tree/main/item/prepare.sh

set -euo pipefail

TARBALL=ArchLinuxARM-aarch64-latest.tar.gz
TARGET_IMAGE_BASE=archlinux
TIMEZONE=America/Los_Angeles

# Check if all the dependencies are present.
check() {
  which qemu-img > /dev/null && \
  which fdisk > /dev/null && \
  which kpartx > /dev/null && \
  which bsdtar > /dev/null && \
  which curl > /dev/null ||
  return 1
}

# Install dependencies.
install_deps() {
  DEPS=(
    curl
    qemu-headless  # qemu-img
    multipath-tools  # kpartx
    util-linux  # fdisk
    libarchive  # bsdtar
  )

  # shellcheck disable=SC2068
  sudo pacman -S --needed --asdeps ${DEPS[@]}
}

check || install_deps


ls QEMU_EFI.fd 2> /dev/null || curl -LO https://releases.linaro.org/components/kernel/uefi-linaro/latest/release/qemu64/QEMU_EFI.fd

dd if=/dev/zero of=flash0.img bs=1M count=64
dd if=QEMU_EFI.fd of=flash0.img conv=notrunc
dd if=/dev/zero of=flash1.img bs=1M count=64

ls $TARBALL 2> /dev/null || curl -LO http://os.archlinuxarm.org/os/$TARBALL
qemu-img create $TARGET_IMAGE_BASE.img 32G

# Partition the disk:
sfdisk $TARGET_IMAGE_BASE.img <<EOF
label: gpt
label-id: 1745B3CF-E63C-4440-8A20-13CC871B5BE8
device: $TARGET_IMAGE_BASE.img
unit: sectors
first-lba: 2048
last-lba: 67108830
sector-size: 512

$TARGET_IMAGE_BASE.img1 : start=        2048, size=      614400, type=C12A7328-F81F-11D2-BA4B-00A0C93EC93B
$TARGET_IMAGE_BASE.img2 : start=      616448, size=    66492383, type=B921B045-1DF0-41C3-AF44-4C6F280D3FAE
EOF

set -x

# Treat this image as a block device.
# Extract both loop devices from the output.
LOOP_DEVS=$(sudo kpartx -av $TARGET_IMAGE_BASE.img | grep -Po 'loop.p.')
BOOT_DEV=$(echo "$LOOP_DEVS" | head -n1)
ROOT_DEV=$(echo "$LOOP_DEVS" | tail -n1)

# Format the partitions
sudo mkfs.vfat /dev/mapper/"$BOOT_DEV"
sudo mkfs.ext4 /dev/mapper/"$ROOT_DEV"

# Mount the partitions
mkdir -p root
sudo mount /dev/mapper/"$ROOT_DEV" root
sudo mkdir -p root/boot
sudo mount /dev/mapper/"$BOOT_DEV" root/boot
sudo bsdtar -xpf $TARBALL -C root

BOOT_UUID=$(lsblk -no uuid /dev/mapper/$BOOT_DEV)
ROOT_UUID=$(lsblk -no uuid /dev/mapper/$ROOT_DEV)


echo "UUID=$ROOT_UUID /     ext4 defaults 0 0" | sudo tee root/etc/fstab
echo "UUID=$BOOT_UUID /boot vfat defaults 0 0" | sudo tee -a root/etc/fstab

echo "Image root=UUID=$ROOT_UUID rw initrd=\initramfs-linux.img" | \
  sudo tee root/boot/startup.nsh

cat > first_run.sh << EOF
#!/bin/bash
set -xe
pacman-key --init
pacman-key --populate archlinuxarm
pacman -Syu --noconfirm
pacman -S efibootmgr --noconfirm
BLKID=\$(lsblk -no uuid /dev/vda2)
efibootmgr --disk /dev/vda --part 1 --create --label "Arch Linux ARM" --loader /Image --unicode "root=UUID=\$BLKID rw initrd=\initramfs-linux.img" --verbose

ln -sf /usr/share/zoneinfo/$TIMEZONE /etc/localtime
echo "en_US.UTF-8 UTF-8" >> /etc/locale.gen
locale-gen
localectl set-locale LANG=en_US.UTF-8
  
EOF
chmod +x first_run.sh
sudo mv first_run.sh root/root/

sudo umount root/boot
sudo umount root/
sudo kpartx -d $TARGET_IMAGE_BASE.img
sync

qemu-img convert -O qcow2 $TARGET_IMAGE_BASE.img $TARGET_IMAGE_BASE.qcow2
rm -rf root $TARGET_IMAGE_BASE.img

cat > run.sh << EOF
#!/bin/bash

qemu-system-aarch64 -m 4096 -smp 2 -cpu cortex-a72 -M virt -nographic \
  -pflash flash0.img \
  -pflash flash1.img \
  -drive "if=virtio,media=disk,id=drive2,file=archlinux.qcow2,cache=writethrough,format=qcow2" \
  -device virtio-net-device,netdev=user0 \
  -netdev user,id=user0,hostfwd=tcp::2222-:22

EOF
chmod +x run.sh

cat << EOF

************************************************************

After starting the VM run ./first_boot.sh to finish setting 
it up as described in the original how-to. The script may
time out if the mirror takes long so you may need to run it
a few times until it works.

Default user/pass is: root/root

************************************************************

EOF

You could replace your regular expressions to find the UUID with lsblk -no uuid "$BOOT_DEV".

You could replace your regular expressions to find the UUID with lsblk -no uuid "$BOOT_DEV".

Thanks. This is nicer.