Arch Linux

Arch is a lightweight and simple distribution of Linux which aims to provide the bleeding edge of most software by following a rolling release model.

This page is mainly following research and steps involved in setting up a new Arch installation.

Entry and verification

What is UEFI?

UEFI (Unified Extensible Firmware Interface) is the second coming of BIOS, and is the platform that generally all modern computers use for booting. It allows for secure boot, 64-bit pre-OS environments and the ability to boot from large partitions (greater than 2TB). Even if your computer claims to have a 'BIOS', it is probably actually just using UEFI.

Boot mode is found in /sys/firmware/efi/fw_platform_size, and should probably always be 64, which means the system is booted and has a 64-bit x86 UEFI.

To show network interfaces:

ip link

Time zone stuff:

# Get current time & timezone
timedatectl

# List timezones
timedatectl list-timezones

# Set yours, ie to Melbourne
timedatectl set-timezone Australia/Melbourne

Partitioning

Checkup and setup

If the disk from which you want to boot already has an EFI system partition, do not create another one, but use the existing partition instead.

Arch Wiki In my case, the drive already had a EFI system partition.

Start by backing up the existing partition table:

# This makes the partition dump
sfdisk -d /dev/sdb > sdb.dump

# This restores the partition dump into the disk
sfdisk /dev/sdb < sdb.dump

Choosing a partition table format

You will generally want to use GUID partition table (GPT) over master boot record (MBR) as it is the more recent standard and has supports for larger partition sizes, more partitions, data integrity, etc. The only downside is compatibility with older systems.

The GUID partition table is part of the UEFI specification, so you probably want to use it if using UEFI. Which you likely are.

Ensuring optimal sector size

"Sector" and "block" can be pretty much used interchangeably. For SSDs, they're called "pages".

A disk sector is the minimum storage unit available on a hard drive.

For a HDD, this is represented by known subdivisions on a physical disk. SDDs do have a 'true' page size, but this is not exposed. Instead, whatever they report as their physical sector size will be the same as their logical sector size.

Using hdparm you can find the sector size of your drive.

# Get the sector size of /dev/sdb
dhparm -I /dev/sdb | grep 'Sector size:'

# This resulted in:
Logical Sector size:              512 bytes
Physical Sector size:             512 bytes

If a drive supports multiple sector sizes, it will look like:

Logical  Sector size:                   512 bytes [ Supported: 512 4096 ]
Physical Sector size:                  4096 bytes

Since mine did not, 512 bytes is the only available option. Nothing to do here.

Creating the new partition table

Looked into completely resetting the SSD, determined it wasn't necessary as I'm not selling this drive to someone else and there's nothing fishy going on 🐟.

Start by listing what partitions currently exist:

fdisk -l /dev/sdb

Open the fdisk tool to create and edit a new partition table:

fdisk /dev/sdb

1. Create a new table with g.
2. Create the new EFI partition with n, partition number 1, first sector 2048, last +1G
   1. The partition contained an existing vfat signature.
   2. Looking into it, seems like a vfat signature is an indicator of existing data, and deleting it would be equivalent to wiping the partition.
3. Created the remaining partition 2 as 8GiB of swap, and partition 3 as the remaining drive.
4. Used t to update the first partition to EFI System
5. Used p to print out the partition table to make sure everything looked OK
6. Used w to write it onto the disk.

Creating the file system

Had another choice to make with which filesystem to go with.

The choice here seems to be between ext4, xfs and btrfs.

• Features of btrfs include snapshots & rollbacks, support for RAID and self-healing. Lowest reliability, most features.
• XFS seems to mainly focus on scalability, high speed and performance.
• ext4 is the historically stable option with the highest reliability. Ended up choosing ext4.

Creating an ext4 filesystem on /dev/sdb3 as the largest regular filesystem:

mkfs.ext4 -L ROOT /dev/sdb3

Then creating swap on /dev/sdb2

mkswap -L SWAP /dev/sdb2

(For context, later re-partitioned the disk to get rid of existing stuff from a previous Linux install)

mkfs.fat -F 32 -n EFI /dev/sdb1

Mounting the file system

Using --mkdir to create the mount point if it does not exist.

# Mount the ROOT filesystem
mount --mkdir /dev/sdb3 /mnt

# Mount the EFI filesystem
mount --mkdir /dev/sdb1 /mnt/boot

# Enable the swap partition
swapon /dev/sdb2

Preparing to bootstrap the new system

Update the mirror list with:

reflector --delay 1 -f 10 > /etc/pacman.d/mirrorlist

Enable ParallelDownloads in /etc/pacman.conf by uncommenting a line in the config that should be there.

Bootstrapping the new system

Command for bootstrapping packages onto a new drive is pacstrap.

Base packagesbase linux linux-firmware

Filesystem toolinge2fsprogs dosfstools

Text editorvim

Manpagesman-db man-pages texinfo

Shellzsh

Desktop environment, network manager, utilitiesplasma-meta kde-applications

You could also install plasma here, which is a group instead of a meta-package. For reasons behind installing one or the other check out the Arch Wiki page on this.

In a similar vein, you could install kde-applications-meta instead, but I'd like to be able to manage the KDE applications separately.

Configuring the system

Filesystem table Since we labelled the partitions before, the fstab will use labels instead of UUIDs for simplicity.

genfstab -L /mnt >> /mnt/etc/fstab

Changing root

arch-chroot /mnt

Setting the time zone

ln -sf /usr/share/zoneinfo/Australia/Melbourne /etc/localtime
hwclock --systohc

Localization Edited the /etc/locale.gen file to uncomment en_US.UTF-8 UTF-8 and en_AU.UTF-8 UTF-8.

# Generate the locales
locale-gen

# Configure to choose one, in my case AU 🇦🇺
echo "LANG=en_AU.UTF-8" > /etc/locale.conf

Hostname and password

# Set the hostname
echo pinky > /etc/hostname

# Set the password
passwd

Setting up a boot loader

What is a boot loader?

A boot loader is some executable file generally present in your EFI system partition under the path /EFI/BOOT/BOOTx64.EFI. EFI is its' own kind of executable that must match the UEFI specification to be run.

Note

BIOS works differently to UEFI with regard to this, however you generally don't need to care about BIOS. And I certainly don't.

The executable could be the kernel itself, but is generally going to be a boot loader.

The boot loader's sole purpose (other than providing a cool menu to pick loader options) is to pass off control to a kernel image. Usually this will be vmlinux or vmlinuz (compressed or zipped virtual memory Linux kernel).

Kernel images start a temporary root file system in RAM. The root file system / starts out completely empty, but the kernel will unpack its builtin system dependencies into it.

The kernel will then unpack any other external files, overriding the builtins, from paths provided by the boot loader.

The boot process continues from here without input from the boot loader, setting up the system to where it can access the regular root file system.

What is microcode?

Microcode is an intermediary layer between the instruction set (ie. x86 Assembly) and the CPU architecture. It is essentially the code which controls how your CPU runs.

Your CPU stores this microcode out of the factory in its own ROM. Being able to update this microcode is critical as occasionally manufacturers will need to provide important security updates or performance enhancements.

So to update it, the Linux kernel ships with updated microcode. However, this is often also not on a sufficiently fast enough cycle. So, the boot loader will also override and update the microcode if shipped with any.

# Install AMD microcode
pacman -S amd-ucode

Which boot loader should I choose?

To be honest, I have no idea. There are many to choose from. Here's some takeaways from some vague community reading:

• Systemd-boot is the stable option which is easiest to set up for in Arch, but does not support dual boot well.
• GRUB is unwieldy and gigantic, but supports everything ever.
• REFInd is the new kid on the block with the simplest setup. In my experience this could only realistically be configured post first-boot.

Sample setup for systemd-boot

Start by installing systemd-boot

bootctl install

Then you need to configure a loader. systemd-boot will search for valid items under ESP/loader/entries/*.conf. Something like:

title Arch Linux                       -- The thing that gets displayed
linux   /vmlinuz-linux                 -- The path to vmlinux
initrd  /intel-ucode.img               -- The path to microcode
initrd  /initramfs-linux.img           -- The path to the initramfs image
options root=LABEL=ROOT                -- Where to find the root filesystem

Which is enough to boot.

Sample setup for rEFInd

Start by installing rEFInd

pacman -S refind

If you are already booted into Linux, then the entire configuration script is

refind-install

For a bit of fun, to install the popular rEFInd-minimal theme, first create a themes folder.

This will usually be

# You also need to cd into it
mkdir /boot/EFI/refind/themes
cd /boot/EFI/refind/themes

Then clone the repository into it

git clone https://github.com/evanpurkhiser/rEFInd-minimal.git

Then append a command to the end of the rEFInd config

echo "include themes/rEFInd-minimal/theme.conf" >> /boot/EFI/refind/refind.conf

Note

After you install any new bootloader, you will probably need to update the boot load order in your motherboard firmware.

Setting up users, sudoers, desktop environment on launch

After this was just a reboot.

reboot

As plasma-meta comes with NetworkManager that needed to be started up.

systemctl enable --now NetworkManager

Then needed to install and update the sudo config to enable privilege escalation.

pacman -S sudo

# This edit was to enable the wheel group sudo access:
# %wheel      ALL=(ALL:ALL) ALL
# You should probably use the visudo command instead
vim /etc/sudoers

Create the login user

# The specified shell needs to be an absolute path
useradd -m -G wheel -s /usr/bin/zsh aaron