# Gummiboot

Related articles

- Arch boot process
- Boot loaders
- Unified Extensible Firmware Interface

From Gummiboot homepage:

  Gummiboot is a simple UEFI boot manager which executes configured EFI images. The default entry is selected by a configured pattern (glob) or an on-screen menu.

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. In case you have issues booting EFISTUB kernels like in FS#33745, you should use a boot loader which does not use EFISTUB, like GRUB, Syslinux or ELILO.
Note: In the entire article `$esp` denotes the mountpoint of the EFI System Partition aka ESP.

## Installation

For the rest of this document, we assume `$esp` is the mount point of your EFI system partition.

Install gummiboot and install gummiboot in ESP:

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

### Updating

Gummiboot assumes that your EFI System Partition is mounted on `/boot`. If the ESP is not mounted on `/boot`, gummiboot 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.

## 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.

You can find your PARTUUID with `blkid -s PARTUUID -o value /dev/sdxx` (/dev/sdxx should be your root partition and not $esp)

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 or the /dev/sd* mapping changed for some reason. It is also useful if you do not have a filesystem on the partition (or use LUKS, which does not support LABELs).

An example entry for encrypted root (dm-crypt with LUKS)

    $esp/loader/entries/arch-encrypted.conf

    title          Arch Linux (Encrypted)
    linux          /path/to/vmlinuz-linux
    options        initrd=/path/to/initramfs-linux.img cryptdevice=UUID=<UUID>:luks-<UUID> root=UUID=<luks-UUID> rw

In the encrypted example, note that the initrd is in options -- this does not appear to be discretionary at this time. Note that UUID is used for in this example. PARTUUID should be able to replace the UUID, if so desired.

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.

### Menu does not appear after Windows upgrade

For example, if you upgraded from Windows 8 to Windows 8.1, and you no longer see a boot menu after the upgrade (i.e., Windows boots immediately):

- Make sure Secure Boot (BIOS setting) and Fast Startup (Windows power option setting) are both disabled.
- Make sure your BIOS prefers Linux Boot Manager over Windows Boot Manager (depending on your BIOS, this might appear under a BIOS setting like Hard Disk Drive Priority).

## References

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

Category:

- Boot loaders