Boot Loader

`systemd-boot`

Install

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

Install

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

Loader

NOTE: For a full list of options and their explanation refer to man loader.conf(5) § OPTIONS ~~(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)

An example loader configuration could look something like this:

default       arch
timeout       3
auto-entries  1
auto-firmware 1
console-mode  keep

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/ESP/loader/entries/arch.conf (assuming $ESP is mounted at /boot):

title	Arch Linux
linux	/vmlinuz-linux
initrd	/amd-ucode.img
initrd	/initramfs-linux.img
options	root=/dev/mapper/vg0-lv_root rw quiet splash 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), any image placed under $ESP/EFI/Linux/ will be automatically picked up by systemd-boot and any metadata extracted from that image (such as title, version, options, etc.)

In case you place your images someplace else, you will need to supply the efi key instead of initrd.

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

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

rEFIndEFISTUB

EFISTUB is a method of booting the kernel directly as an EFI executable by the firmware without the need to use a boot loader. This can be useful in cases where you want to reduce the attack surface a boot loader can introduce, or you intend to only ever boot one image. However, some UEFI firmware implementations can be flaky, so this isn't always practical.

Install

pacman

To -Sbe 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"
"Bootable to terminal"manipulate "root=/dev/mapper/vg0-lv_rootEFI rwboot rootflags=subvol=@variables amdgpu.dpm=0install add_efi_memmap initrd=amd-ucode.img initrd=initramfs-%v.img systemd.unit=multi-user.target"
efibootmgr


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 withentries:
efibootmgr

andThis thenwill list all boot entries currently stored in your firmware's EFI variables. To delete thean entry, note it's 4-digit boot entry withorder and instruct efibootmgr to delete it:
efibootmgr -Bb XXXX # Your corresponding bootnum

To create a new entry efibootmgr needs to know the disk and partition where yourthe bootloaderkernel resides.image Thisresides is typicallyon the ESP (EFI System Partition).ESP.
In this example the ESP is the first partition of the block device /dev/nvme0n1. Kernel parameters are part of the --unicodeu argument.option. The partition that holds your root partitionfile system needs to be passed as a persistent block device name (further reading:see: Arch Wiki: Persistent block device naming).
NOTE: If you use LVM, you can supply device mapper paths as these already are persistent.

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

Then create the boot entry to load the kernel directly:
efibootmgr --createc --labelL "Arch Linux" --diskd /dev/nvme0n1 --partp 1 --loaderl /vmlinuz-linux --unicodeu $CMDL --verbosev

When using a unified kernel image createyou can instead just point to the bootimage entrywithout likespecifying this:any kernel parameters via the -u option:

ATTENTION: If Secure Boot is enabled and the command line parameters are embedded in the unified kernel image, any attempt to override them by supplying the -u option anyways will be ignored.
efibootmgr --createc --labelL "Arch Linux" --diskd /dev/nvme0n1 --partp 1 --loaderl "EFI\Arch\linux-signed.Linux\archlinux-linux.efi" --verbosev

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