{
	"title": "Arch Linux installation",
	"subtitle": "Installation guide for the Arch Linux operating system"
}

#### Introduction

This article describes how to install [Arch Linux][1]. It is based on the
[official installation guide][2].

This primary documentation does not describe one specific installation option
but instead points out the different options the user has like selecting
bootloaders, boot modes or filesystems.

As a complement this article documents one specific installation inside a QEMU
virtual machine (VM). It might be used as a VM or converted to a binary image
file which can be written to a physical drive like an USB stick or SSD.

#### Design decisions

The installation is based on the following design decisions.

- MBR-based partition table and BIOS / legacy boot
- full disc encryption
- Btrfs file system
- only a minimalistic set of installed packages (no graphical environment)

Those might change in the future. A GPT-based partition table and a UEFI boot
based on a unified kernel image would be appreciated to support secure boot but
could not be achieved so far.

#### Installation

First a virtual drive is created as a file as a starting point for the VM
installation.

```
qemu-img create -f qcow2 archlinux.qcow2 8G
```

It is expected that the Arch Linux `*.iso` installation image is downloaded,
verified and saved in the same folder. See the [download page][3] for details.

The installation image can be booted with `qemu-system-x86_64`. The just
created virtual machine disk is attached as an additional drive.

```
qemu-system-x86_64 \
    -enable-kvm \
    -m 4G \
    -nic user,model=virtio \
    -drive file=archlinux.qcow2,media=disk,if=virtio \
    -smp cpus=4 \
    -nographic \
    -boot order=d \
    -cdrom archlinux-*.iso
```

On the first screen of the bootloader it needs to be specified that only the
serial console should be used which is mapped to the host terminal. For that
purpose the text below has to be typed before the bootloader picks the default
options.

```
<TAB> console=ttyS0
```

This is annoying but worth it since it allows to copy and paste all subsequent
commands instead of typing them by hand.

After specifying the console the installation image should boot. Next the user
`root` without password is used to log in.

The following command allows to check if the time is properly synchronized.

```
timedatectl
```

The virtual machine disk can be partitioned with `parted`.

```
parted /dev/vda --script mklabel msdos
parted /dev/vda --script mkpart primary fat32 1MiB 2GiB
parted /dev/vda --script mkpart primary 2GiB 100%
parted /dev/vda --script set 1 boot on
```

Answer following questions of luksFormat.

```
cryptsetup luksFormat --batch-mode --label CRYPTO_ROOT /dev/vda2
cryptsetup open /dev/vda2 root
```

```
mkfs.vfat -n BOOT /dev/vda1
mkfs.btrfs -L ROOT /dev/mapper/root
```

```
mount /dev/mapper/root /mnt
mount --mkdir /dev/vda1 /mnt/boot
```

```
systemctl start reflector
```

```
pacstrap -K /mnt \
    base \
    linux \
    linux-firmware \
    parted \
    syslinux \
    btrfs-progs \
    networkmanager \
    chrony \
    nano \
    htop \
    openssh \
    man-db \
    man-pages \
    texinfo
```

```
genfstab -L /mnt | tee /mnt/etc/fstab
```

```
arch-chroot /mnt
```

```
ln -sf /usr/share/zoneinfo/Europe/Berlin /etc/localtime
hwclock --systohc
sed -i 's/#en_US.UTF-8 UTF-8/en_US.UTF-8 UTF-8/g' /etc/locale.gen
locale-gen
echo 'LANG=en_US.UTF-8' > /etc/locale.conf
echo 'archlinux' > /etc/hostname
echo 'root' | passwd -s
systemctl enable NetworkManager
systemctl enable chronyd
```

```
mkdir -p /boot/syslinux
cp /usr/lib/syslinux/bios/*.c32 /boot/syslinux/
extlinux --install /boot/syslinux
dd bs=440 count=1 conv=notrunc if=/usr/lib/syslinux/bios/mbr.bin of=/dev/vda
cp /usr/share/syslinux/syslinux.cfg /boot/syslinux/
sed -i 's|root=/dev/sda3 rw|cryptdevice=/dev/disk/by-label/CRYPTO_ROOT:root root=/dev/mapper/root rw|g' /boot/syslinux/syslinux.cfg
```

```
sed -i 's/^HOOKS.*$/HOOKS=(base udev autodetect microcode modconf kms keyboard keymap consolefont block encrypt btrfs filesystems fsck)/g' /etc/mkinitcpio.conf
mkinitcpio -P
```

```
exit
poweroff
```

```
qemu-img convert -f qcow2 -O raw archlinux.qcow2 archlinux.img
```

```
dd if=archlinux.img of=/dev/sdb bs=512 status=progress
```

Resizing last partition to full extend

```
parted /dev/sdb --script resizepart 2 100%  # TODO replace static path
cryptsetup resize root  # interactive / password required
btrfs filesystem resize max /
```

[1]: https://archlinux.org/
[2]: https://wiki.archlinux.org/title/Installation_guide
[3]: https://archlinux.org/download/