Archlinux on encrypted btrfs with systemd-boot and KDE

I've been a Linux user since the 2000s starting on Mandrake with KDE2, however, it never became my main desktop. I always stuck with Windows XP, Windows 7 and then Mac OSX; Linux was still my love for anything server side, but not desktop.

About 6 years ago I decided the Apple premium wasn't worth it any more. Linux had better package managers, cli tools, and I spent most of my time in the web browser or terminal. I felt ready for a Linux desktop. I sold all my Apple hardware, bought an extra SSD and dual booted again. Archlinux with KDE became my desktop of choice.

There are plenty of guides for installing Arch, the Arch wiki being a one such resource, but I wanted to document how I configure mine all in one place with the following:

• UEFI with systemd-boot
• Full disk encryption on ssd/nvme
• btrfs with subvolumes, compression and snapshots
• Swapfile for hibernation
• Unlock encryption with USB flash drive

Getting started

Boot the Archlinux live environment and configure networking. If you're using ethernet then DHCP will already be running. Verify with ping.

ping archlinux.org

If you need Wi-Fi then run wifi-menu and enable the profile after:

wifi-menu # Let it scan networks, pick yours
netctl enable wlan-ssid # Can tab complete profile

(On my systems I use NetworkManager for desktops and Systemd-networkd for servers, but netctl is available within the live environment and provides wifi-menu so I use it during install.)

Ensure the system clock is accurate with:

timedatectl set-ntp true

Edit /etc/pacman.d/mirrorlist and move faster mirrors to the top (i.e. the ones closer geographically).

Partition and file system set up

Find the disk you wish to install Arch on using lsblk. For example an nvme drive at /dev/nvme0n1.

Create two partitions one for boot the other for the main OS. Boot will contain EFI/systemd-boot, and main will contain subvolumes for root and home.

EFI should be at least 260 MiB, and I tend to use 512 MiB for full compatibility.

Run gdisk:

gdisk /dev/nvme0n1
o (create a new empty GUID partition table (GPT))
Proceed? (Y/N): y

n (add a new partition)
Partition number (1-128, default 1): 1
First sector : (hit enter)
Last sector : +512MB (at least 260MiB, 512MiB for compability with old UEFI)
Hex code or GUID: ef00

n (add a new partition)
Partition number (2-128, default 2): 2
First sector : (hit enter)
Last sector : (hit enter - rest of disk)
Hex code or GUID: (hit enter, default, 8300)

w
Do you want to proceed? (Y/N): y

Set up encryption on the main partition:

cryptsetup luksFormat /dev/nvme0n1p2
Are you sure? YES
(enter passphrase)
cryptsetup luksOpen /dev/nvme0n1p2 cryptroot

Format the partitions:

mkfs.fat -F32 -n LINUXEFI /dev/nvme0n1p1
mkfs.btrfs -L Arch /dev/mapper/cryptroot

Now for the main partition create subvolumes for root and home, along with snapshots/@ and snapshots/@home (so you can run backups and restore independently).

It's also recommended creating subvolumes for directories we don't want backed up e.g. /var/cache, a subvol for swap if you're going to use a swapfile, and if we have VMs or databases, to disable copy-on-write (COW).

mount -o compress=zstd,noatime /dev/mapper/cryptroot /mnt
btrfs subvol create /mnt/@
btrfs subvol create /mnt/@home
btrfs subvol create /mnt/@swap

mkdir /mnt/snapshots
btrfs subvol create /mnt/snapshots/@
btrfs subvol create /mnt/snapshots/@home

umount /mnt
mount -o compress=zstd,noatime,subvol=@ /dev/mapper/cryptroot /mnt
mkdir -p /mnt/{boot,home}
mount -o compress=zstd,noatime,subvol=@home /dev/mapper/cryptroot /mnt/home
mount /dev/nvme0n1p1 /mnt/boot

mkdir /mnt/var
btrfs subvol create /mnt/var/cache
btrfs subvol create /mnt/var/log

mkdir -p /mnt/var/lib/{mysql,postgres,machines}
chattr +C /mnt/var/lib/{mysql,postgres,machines}

Note the use of noatime, and compress=zstd options.

noatime will disable writing of access times to each file when they're accessed. It's often recommended for COW file systems to help performance because writes cause COW.

compress=zstd adds transparent compression, helping to reduce file sizes; Its super fast, and I've never had performance issues.

Installation

Install the base system + extra packages:

pacstrap /mnt base base-devel linux linux-firmware intel-ucode amd-ucode \
wpa_supplicant btrfs-progs dosfstools e2fsprogs sudo zsh zsh-completions \
zsh-syntax-highlighting tmux rsync openssh git vim neovim htop networkmanager \
openvpn networkmanager-openvpn fzf ruby python nodejs

Generate fstab:

genfstab /mnt >> /mnt/etc/fstab

Note: change the boot partition to use UUID.

Example fstab:

/dev/mapper/cryptroot / btrfs rw,noatime,compress=zstd:3,space_cache,subvol=@ 0 0
/dev/mapper/cryptroot /home btrfs rw,noatime,compress=zstd:3,space_cache,subvol=@home 0 0
UUID=559E-32F1 /boot vfat rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,utf8,errors=remount-ro 0 2

Chroot into our system to finish installation:

cp /etc/pacman.d/mirrorlist /mnt/etc/pacman.d/mirrorlist
arch-choot /mnt

nvim /etc/locale.gen # Uncomment en_GB.UTF-8
locale-gen
echo LANG=en_GB.UTF-8 > /etc/locale.conf
echo keymap=uk > /etc/vconsole.conf
ln -sf /usr/share/zoneinfo/Europe/London /etc/localtime
hwclock --systohc

echo new-hostname > /etc/hostname

passwd # Set root password

Edit /etc/hosts to match:

127.0.0.1       localhost
::1             localhost
127.0.1.1       new-hostname.localdomain      new-hosthostname

Edit /etc/mkinitcpio.conf to add systemd, sd-vconsole, sd-encrypt and move keyboard.

- HOOKS=(base udev autodetect modconf block filesystems keyboard fsck)
+ HOOKS=(base systemd autodetect keyboard sd-vconsole modconf block sd-encrypt filesystems fsck)

- BINARIES=()
+ BINARIES=(btrfs)

Generate initramfs:

mkinitcpio -P

Install the systemd-boot loader:

bootctl --path=/boot install

Get the UUID of the luks partition (not cryptroot, but /dev/nvme0n1p2 for example) with blkid. This is the partition we want to unlock to create cryptroot.

blkid

Create /boot/loader/entries/arch.conf:

title Arch Linux
linux /vmlinuz-linux
initrd  /amd-ucode.img
initrd /initramfs-linux.img
options rd.luks.name=UUID_OF_LUKS_PARTITION=cryptroot root=/dev/mapper/cryptroot rootflags=subvol=@ rd.luks.options=discard rw

rd.luks.options=discard will be needed for TRIM support.

You need to pick the right ucode for your processor: amd-ucode or intel-ucode.

Change UUID_OF_LUKS_PARTITION to the UUID you found via blkid.

Edit /boot/loader/loader.conf:

default arch
timeout 2

Reboot:

exit
umount -R /mnt
reboot

You should have a functioning base system at this point.

Post install

These steps are more personalised towards how I want my desktop to work. Feel free to tweak as you need to.

Lets login as root and get some networking; we installed NetworkManager before so start and enable that now:

systemctl start NetworkManager NetworkManager-wait-online
systemctl enable NetworkManager NetworkManager-wait-online

If you need Wi-Fi you can run the following:

nmcli device wifi list
nmcli device wifi connect SSID password mysecurepass

Enable ssh and fstrim:

systemctl enable sshd fstrim.timer

fstrim runs a periodic service for TRIM (needed for SSDs). It's recommended to run weekly rather than continuous.

Ensure time is synced:

timedatectl set-ntp true

Create your user:

useradd -m -G wheel,users -s /usr/bin/zsh rich
passwd rich # Enter password

Edit sudo to enable wheel group access:

EDITOR=nvim visudo
## Uncomment to allow members of group wheel to execute any command
%wheel ALL=(ALL) ALL

Save the changes, exit and login as the new user.

Graphics:

sudo pacman -S xorg-server xf86-video-fbdev xf86-video-nouveau xf86-video-amdgpu

I install a lot of AUR packages; to make this easier I use the yay AUR manager:

git clone https://aur.archlinux.org/yay.git /tmp/yay

cd /tmp/yay
makepkg -si

Install KDE desktop:

sudo pacman -S plasma-meta sddm kdialog konsole dolphin noto-fonts \
phonon-qt5-vlc

You may wish to review the following, but these are the packages, themes and fonts I use:

sudo pacman -S adobe-source-code-pro-fonts noto-fonts-emoji ttf-opensans \
ttf-roboto ttf-fira-mono ttf-bitstream-vera \
inetutils firefox chromium \
virt-manager edk2-ovmf qemu libvirt docker docker-compose \
kubectl helm colord-kde kdeconnect exfat-utils

yay -S otf-san-francisco sierrabreeze-kwin-decoration-git archlinux-artwork \
materia-kde materia-gtk-theme plasma5-applets-eventcalendar

Add some groups to our user to make docker/kvm easier:

sudo usermod -a -G docker,libvirt,kvm rich
sudo systemctl enable docker libvirtd

To configure login manager, create the following folder:

sudo mkdir /etc/sddm.conf.d

Then create /etc/sddm.conf.d/kde_settings.conf:

[Autologin]
Relogin=false
Session=plasma
User=rich

[General]
HaltCommand=/usr/bin/systemctl poweroff
Numlock=none
RebootCommand=/usr/bin/systemctl reboot

[Theme]
Current=breeze

[Users]
MaximumUid=60000
MinimumUid=1000

(Note I auto login my user.)

At this point I clone my dotfiles, but feel free to skip this step as they only contain my configs for KDE themes, zsh, git, etc.

git clone --bare --recursive https://github.com/RichGuk/dotfiles.git $HOME/.dotfiles
alias config='/usr/bin/git --git-dir=$HOME/.dotfiles --work-tree=$HOME'

config checkout
config submodule update
config config --local status.showUntrackedFiles no

Enable login manager and reboot.

sudo systemctl enable sddm
sudo reboot

You should be all set!

USB based keyfile

Find the drive you wish to use with lsblk. You can use an existing partition, or create a new partition with gdisk. For example ext4 on /dev/sde3.

Mount the file system and generate a keyfile to use:

sudo mkdir /mnt/usb-keyfiles
sudo mount /dev/sde3 /mnt/usb-keyfiles
sudo dd bs=512 count=4 if=/dev/random of=/mnt/usb-keyfiles/myhostname.key iflag=fullblock
sudo chmod 600 /mnt/usb-keyfiles/myhostname.key

Find your luks partition with lsblk (this is not the btrfs partition). Add the keyfile:

sudo cryptsetup luksAddKey /dev/nvme0n1p2 /mnt/usb-keyfiles/myhostname.key
(enter your existing encryption password)

Get the UUID flash drive:

sudo blkid

Edit /boot/loader/entries/arch.conf:

title Arch Linux
linux /vmlinuz-linux
initrd  /amd-ucode.img
initrd /initramfs-linux.img
options rd.luks.key=UUID_OF_LUKS_PARTITION=/myhostname.key:UUID=UUID_OF_USB_PARTITION rd.luks.name=UUID_OF_LUKS_PARTITION=cryptroot root=/dev/mapper/cryptroot rootflags=subvol=@ rd.luks.options=discard,keyfile-timeout=10s rw

Add rd.luks.key and keyfile-timeout=10s to rd.luks.options.

rd.luks.key the first part is the luks we're trying to open, then the location of the keyfile (in our case root of flash drive), and then the UUID of the USB flash partition to use.

keyfile-timeout=10s needed to allow us to fallback to password unlock if USB key doesn't exist.

We need to add the partition type (in our case ext4) to initramfs. Edit /etc/mkinitcpio.conf:

- MODULES=()
+ MODULES=(ext4)

Regenerate initramfs:

mkinitcpio -P

You can now reboot with the USB flash drive plugged in and it should automatically unlock your encryption.

Swapfile / Hibernation

Swapfile cannot be on a snapshotted subvolume. This is why, in the earlier steps, we created the @swap subvolume. Lets mount it:

sudo mkdir /swapspace
sudo mount -o noatime,subvol=@swap /dev/mapper/cryptroot /swapspace

(Don't mount with compression.)

Create the swapfile:

sudo truncate -s 0 /swapspace/swapfile
sudo chattr +C /swapspace/swapfile
sudo btrfs property set /swapspace/swapfile compression none

sudo fallocate -l 32G /swapspace/swapfile
sudo mkswap /swapspace/swapfile

sudo chmod 600 /swapspace/swapfile

Activate the swapfile:

sudo swapon /swapspace/swapfile

Now edit /etc/fstab to mount swapspace and swapfile on boot:

/dev/mapper/cryptroot /swapspace btrfs rw,noatime,space_cachesubvol=@swap 0 0
/swapspace/swapfile none swap defaults,discard 0 0

If you want to be able to hibernate you need to follow this to get the offset. Then add resume and resume_offset to /boot/loader/entries/arch.conf:

title Arch Linux
linux /vmlinuz-linux
initrd  /amd-ucode.img
initrd /initramfs-linux.img
options rd.luks.key=UUID_OF_LUKS_PARTITION=/myhostname.key:UUID=UUID_OF_USB_PARTITION rd.luks.name=UUID_OF_LUKS_PARTITION=cryptroot root=/dev/mapper/cryptroot rootflags=subvol=@ rd.luks.options=discard,keyfile-timeout=10s resume=/dev/mapper/cryptroot resume_offset=OFFSET_CALC rw