Systemd-boot

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Revision as of 11:21, 12 March 2013 by 65kid (Talk | contribs) (remove note about /boot <-> /boot/efi, this is explained in the installing section)

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Gummiboot is a UEFI boot manager written by Kay Sievers and Harald Hoyer. It is simple to configure, but can only start EFI executables, the Linux kernel (with CONFIG_EFI_STUB enabled), grub.efi, and such.

Installing

Note: gummiboot assumes that your EFI System Partition is mounted on /boot. If your ESP is mounted on /boot/efi you have to call the following gummiboot install command with the additional --path switch. This also means that gummiboot will not be able to update itself automatically and you will have to call gummiboot --path /boot/efi update after every package update. It is therefore strongly recommended to mount your ESP to /boot if you use gummiboot.

Install gummiboot from [extra] and run the following to install gummiboot:

# gummiboot install

This will automatically copy the gummiboot binary to your EFI System Partition and create a boot entry in the EFI Boot Manager. However, creating the boot entry requires that you are already running in EFI mode and are running kernel 3.8 which is currently still in [testing]. If you are still running kernel 3.7 or have not booted in EFI mode, creating the boot entry will fail. You should however still be able to boot gummiboot as it copies the binary to the default EFI binary location on your ESP (/boot/EFI/BOOT/BOOTX64.EFI on x64 systems). Note that the installing process only has to be done once, updating will happen automatically.

Configuring

The basic configuration is kept in $esp/loader/loader.conf, with just two possible configuration options:

  • default – default entry to select (without the .conf suffix); can be a wildcard like arch-*
  • timeout – menu timeout in seconds. If this is not set, the menu will only be shown when you hold the space key while booting.

Example:

$esp/loader/loader.conf
default  arch
timeout  4

Note that both options can be changed in the boot menu itself, which will store them as EFI variables.

Adding boot entries

Note:

If you have separate partitions for /boot and /boot/efi, you must copy the kernel and initramfs to the EFI partition. Gummiboot does not support loading kernels from other partitions than itself. See UEFI_Bootloaders#Sync_EFISTUB_Kernel on how to automate this copy.

Gummiboot searches for boot menu items in $esp/loader/entries/*.conf – each file found must contain exactly one boot entry. The possible options are:

  • title – operating system name. Required.
  • version – kernel version, shown only when multiple entries with same title exist. Optional.
  • machine-id – machine identifier from /etc/machine-id, shown only when multiple entries with same title+version exist. Optional.
  • efi – EFI program to start; e.g. /vmlinuz-linux. Either this or linux (see below) is required.
  • options – Command-line options to pass to the EFI program. Optional, but you will need at least initrd=efipath and root=dev if booting Linux.

For Linux, you can specify linux path-to-vmlinuz and initrd path-to-initramfs; this will be automatically translated to efi path and options initrd=path – this syntax is only supported for convenience and has no differences in function.

An example entry for Arch Linux:

$esp/loader/entries/arch.conf
title          Arch Linux
linux          /vmlinuz-linux
initrd         /initramfs-linux.img
options        root=PARTUUID=14420948-2cea-4de7-b042-40f67c618660 ro

You can also add other EFI programs such as \EFI\arch\grub.efi or \EFI\Microsoft\Boot\Bootmgfw.efi (the Windows 7 boot manager). The EFI Shell, if installed, will be shown automatically.

$esp/loader/entries/shell.conf
title          UEFI Shell
efi            \shellx64.efi

Separate boot and EFI partitions

TODO: link my kernel-post-upgrade stuff, https://github.com/grawity/code/tree/master/os/arch

Inside the boot menu

TODO: document keybindings from http://freedesktop.org/wiki/Software/gummiboot

Troubleshooting

Transferring to new HDD causes breakage

Twice now I have transferred my installation from one disk to another, ESP included, and both times this broke my gummiboot setup. With a lot of trial and error, I have discovered that gummiboot does not like configuration files that have been tranfserred from one disk to another (I used rsync).

To solve this, delete the $ESP/loader directory and all of its contents, and recreate the necessary configuration files.

Though it has no additional info, here is my relevent forum thread.