Gummiboot

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 EFISTUB, UEFI Shell, grub.efi, and such.

Warning: Gummiboot simply provides a boot menu for EFISTUB kernels. It does not directly launch a Linux Kernel like a traditional bootloader (GRUB, Syslinux) (hence it is called a Boot Manager, not a Boot Loader). In case you have issues booting EFISTUB kernels like in FS#33745, you should use a bootloader which does not use EFISTUB, like GRUB(2), Syslinux 6.xx or ELILO. rEFInd also uses EFISTUB so that cannot be used in such cases.

Note: In the entire article $esp denotes the mountpoint of the EFI System Partition aka ESP.

Installation

Install gummiboot and install gummiboot in ESP:

# mount -t efivarfs efivarfs /sys/firmware/efi/efivars              # ignore if already mounted
# pacman -S gummiboot
# gummiboot --path=$esp install

This will automatically copy the gummiboot binary to your EFI System Partition and create a boot entry in the EFI Boot Manager. If you are not booted via EFI, 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 ($esp/EFI/boot/bootx64.efi on x64 systems) (unless a non-gummiboot $esp/EFI/boot/bootx64.efi is already present).

Note:

• The gummiboot command by default assumes that your EFI System Partition is mounted on /boot. This means gummiboot in the ESP will not be updated automatically during pkg updates and you will have to call gummiboot --path=$esp update after every package update. Additionally you will have to make sure that the kernel and initramfs are copied onto the ESP as gummiboot cannot load EFI binaries from other partitions. It is therefore strongly recommended to mount your ESP to /boot if you use gummiboot, in which case updating will happen automatically by the post_install script of gummiboot during package updates.

• If gummiboot fails to create a boot entry, check whether all the conditions mentioned here are met.

Configuration

Basic Configuration

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.

Note: If no timeout is configured, which is the default setting, and no key pressed during bootup, the default entry is executed right away.

Adding boot entries

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 and version exist. Optional.

• efi – EFI program to start, relative to your ESP ($esp); 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 rw

Please note in the example above that PARTUUID/PARTLABEL identifies a GPT partition, and differs from UUID/LABEL, which identifies a filesystem. Using the PARTUUID/PARTLABEL is advantageous because it is invariant if you reformat the partition with another filesystem. It is also useful if you do not have a filesystem on the partition (or use LUKS, which does not support LABELs).

You can also add other EFI programs such as \EFI\arch\grub.efi.

Note: Gummiboot will automatically check for "Windows Boot Manager" (\EFI\Microsoft\Boot\Bootmgfw.efi), "EFI Shell" (\shellx64.efi) and "EFI Default Loader" (\EFI\Boot\bootx64.efi), and display entries for them if they are present, so you do not have to manually create entries for them. However it does not autodetect other EFI applications (unlike rEFInd), so for booting the kernel, manual config entries must be created as mentioned above.

Inside the boot menu

Keys

The following keys are used inside the menu:

• Up/Down - select entry
• Enter - boot the selected entry
• d - select the default entry to boot (stored in a non-volatile EFI variable)
• -/T - decrease the timeout (stored in a non-volatile EFI variable)
• +/t - increase the timeout (stored in a non-volatile EFI variable)
• e - edit the kernel command line
• v - show the gummiboot and UEFI version
• Q - quit
• P - print the current configuration
• h/? - help

These hotkeys will, when pressed inside the menu or during bootup, directly boot a specific entry:

• l - Linux
• w - Windows
• a - OS X
• s - EFI Shell
• 1-9 - number of entry

Troubleshooting

Manual entry using efibootmgr

If gummiboot install command failed, you can create a EFI boot entry manually using efibootmgr utility:

# efibootmgr -c -d /dev/sdX -p Y -l /EFI/gummiboot/gummibootx64.efi -L "Gummiboot"

where /dev/sdXY is the EFISYS partition.

References

• http://freedesktop.org/wiki/Software/gummiboot/