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Boot Loader

systemd-boot

Install

systemd comes with systemd-boot already, so no additional packages need to be installed.

ATTENTION: By default, systemd-boot will install itself to either of the well-known ESP locations, e.g. /efi, /boot, or /boot/efi. If your ESP is located somewhere else pass the localtion with the --esp-path parameter.

bootctl install

Configure

systemd-boot has two configs:

  • one for the loader itself located at $YOUR_ESP/loader/loader.conf
  • one for each individual boot entry located at $YOUR_ESP/loader/entries/*.conf

Loader

NOTE: For a full list of options and their explanation refer to man loader.conf(5) (alternatively: Web Version)

An example loader configuration could look something like this:

default       arch
timeout       3
auto-entries  1
auto-firmware 1
console-mode  keep
Key Value Description
default file name The default selected entry (e.g. arch.conf)
timeout number Seconds until the default entry is booted (e.g. 3)
auto-entries boolean Show or hide other boot entries found by scanning the boot partition
auto-firmware boolean Show or hide "Reboot into firmware" entry
console-mode number/string Resolution of the console (e.g. keep to keep the resolution selected by firmware)

Boot entry

NOTE: For a full list of options and their explanation refer to the Boot Loader Specification. All paths are relative to the path of your ESP.

Bootloader entry for the main kernel, located at $YOUR_ESP/loader/entries/arch.conf

title	Arch Linux
linux	/vmlinuz-linux
initrd	/amd-ucode.img
initrd	/initramfs-linux.img
options	root=/dev/mapper/vg0-lv_root rw rootflags=subvol=@ quiet splash
Key Value Description
title string The name of the entry in the boot menu
linux path Location of the Linux kernel (relative to ESP)
initrd path Location of the Linux initrd image (relative to ESP)
options string Kernel command line parameters

When using a unified kernel image (e.g. as an .efi executable) you will need to supply the efi key instead of initrd.

NOTE: Unified kernel images have most things needed to boot baked in, so a loader entry really only consists of two lines.

title	Arch Linux
efi     /EFI/Arch/linux.efi

rEFInd

Install

pacman -S refind
refind-install

Configure

ATTENTION: In this example the ESP is mounted at /boot. Change accordingly!

Default options for every entry, located at /boot/refind_linux.conf

"Boot using default options"     "root=/dev/mapper/vg0-lv_root rw rootflags=subvol=@ amdgpu.dpm=0 add_efi_memmap initrd=amd-ucode.img initrd=initramfs-%v.img"
"Boot using fallback initramfs"  "root=/dev/mapper/vg0-lv_root rw rootflags=subvol=@ amdgpu.dpm=0 add_efi_memmap initrd=amd-ucode.img initrd=initramfs-%v-fallback.img"
"Boot to terminal"               "root=/dev/mapper/vg0-lv_root rw rootflags=subvol=@ amdgpu.dpm=0 add_efi_memmap initrd=amd-ucode.img initrd=initramfs-%v.img systemd.unit=multi-user.target"

EFISTUB

Install

pacman -S efibootmgr

Configure

WARNING: efibootmgr can only be run as root!

efibootmgr cannot overwrite existing boot entries and will disregard the creation of a boot entry if one with the same label already exists. If this is the case, delete the boot entry you want to replace first by listing current boot entries with

efibootmgr

and then delete the boot entry with

efibootmgr -Bb XXXX # Your corresponding bootnum

To create a new entry efibootmgr needs to know the disk and partition where your bootloader resides. This is typically the ESP (EFI System Partition).

In this example the ESP is the first partition of /dev/nvme0n1. Kernel parameters are part of the --unicode argument. The root partition needs to be passed as a persistent block device name (further reading: Arch Wiki: Persistent block device naming). You can get the persistent block device name with the blkid command, i.e. to get the UUID of the second partition on /dev/nvme0n1:

blkid -s UUID -o value /dev/nvme0n1p2

You can also supply a different identifier like PARTUUID.

NOTE: If you use LVM, you can supply device mapper paths as these already are persistent.

For ease of scriptability, save the values to environment variables:

ASSUMPTIONS: rootfs is on /dev/nvme0n1, there is a swap partition, and the file system is btrfs.

export ROOT=$(blkid -s UUID -o value /dev/nvme0n1p2)
export SWAP=$(blkid -s UUID -o value /dev/nvme0n1p3)
export CMDL=$(echo 'root=UUID='$ROOT' resume=UUID='$SWAP' rw quiet splash rootflags=subvol=@ add_efi_memmap initrd=\\amd-ucode.img initrd=\\initramfs-linux.img')

Then create the boot entry to load the kernel directly:

efibootmgr --create --label "Arch Linux" --disk /dev/nvme0n1 --part 1 --loader /vmlinuz-linux --unicode $CMDL --verbose

When using a unified kernel image create the boot entry like this:

efibootmgr --create --label "Arch Linux" --disk /dev/nvme0n1 --part 1 --loader "EFI\Arch\linux-signed.efi" --verbose

GRUB2

Install

Install GRUB for either target x86_64-efi or i386-pc. Install to a drive, not a partition!

pacman -S grub
grub-install --target=x86_64-efi /dev/nvme0n1

Configure

Edit /etc/default/grub with desired options and run

grub-mkconfig -o /boot/grub/grub.cfg
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