The operating system supports multiple bootloaders. The bootloader is
bootloader-configuration declaration. All the
fields of this structure are bootloader agnostic except for one field,
bootloader that indicates the bootloader to be configured and
Some of the bootloaders do not honor every field of
bootloader-configuration. For instance, the extlinux bootloader does
not support themes and thus ignores the
The type of a bootloader configuration declaration.
The bootloader to use, as a
bootloader object. For now
u-boot-bootloader are supported.
Available bootloaders are described in
(gnu bootloader …)
modules. In particular,
(gnu bootloader u-boot) contains definitions
of bootloaders for a wide range of ARM and AArch64 systems, using the
grub-efi-bootloader allows to boot on modern systems using the
Unified Extensible Firmware Interface (UEFI). This is what you should
use if the installation image contains a /sys/firmware/efi directory
when you boot it on your system.
grub-bootloader allows you to boot in particular Intel-based machines
in “legacy” BIOS mode.
grub-efi-netboot-bootloader allows you to boot your system over
network through TFTP. In combination with an NFS root file system this
allows you to build a diskless Guix system.
The installation of the
grub-efi-netboot-bootloader generates the
content of the TFTP root directory at
target), to be served by a TFTP server. You may want
to mount your TFTP server directory onto
target to move the required
files to the TFTP server automatically.
If you plan to use an NFS root file system as well (actually if you mount
the store from an NFS share), then the TFTP server needs to serve the file
/boot/grub/grub.cfg and other files from the store (like GRUBs
background image, the kernel (see
kernel) and the initrd (see
initrd)), too. All these files from the store will be accessed by
GRUB through TFTP with their normal store path, for example as
Two symlinks are created to make this possible. The first symlink is
target/efi/Guix/boot/grub/grub.cfg pointing to
target may be
/boot. In this case the link is not leaving the served TFTP root
directory, but otherwise it does. The second link is
target/gnu/store and points to ../gnu/store. This link
is leaving the served TFTP root directory.
The assumption behind all this is that you have an NFS server exporting the
root file system for your Guix system, and additionally a TFTP server
target directory—usually /boot—from that same
root file system for your Guix system. In this constellation the symlinks
For other constellations you will have to program your own bootloader
installer, which then takes care to make necessary files from the store
accessible through TFTP, for example by copying them into the TFTP root
It is important to note that symlinks pointing outside the TFTP root directory may need to be allowed in the configuration of your TFTP server. Further the store link exposes the whole store through TFTP. Both points need to be considered carefully for security aspects.
grub-efi-netboot-bootloader, the already mentioned TFTP
and NFS servers, you also need a properly configured DHCP server to make the
booting over netboot possible. For all this we can currently only recommend
you to look for instructions about PXE (Preboot eXecution
This is a string denoting the target onto which to install the bootloader.
The interpretation depends on the bootloader in question. For
grub-bootloader, for example, it should be a device name understood
by the bootloader
installer command, such as
(hd0) (see Invoking grub-install in GNU GRUB Manual). For
grub-efi-bootloader, it should be the mount point of the EFI file
system, usually /boot/efi. For
target should be the mount point corresponding to the TFTP root
directory of your TFTP server.
A possibly empty list of
menu-entry objects (see below), denoting
entries to appear in the bootloader menu, in addition to the current system
entry and the entry pointing to previous system generations.
The index of the default boot menu entry. Index 0 is for the entry of the current system.
The number of seconds to wait for keyboard input before booting. Set to 0 to boot immediately, and to -1 to wait indefinitely.
If this is
#f, the bootloader’s menu (if any) uses the default
keyboard layout, usually US English (“qwerty”).
Otherwise, this must be a
keyboard-layout object (see Раскладка клавиатуры).
Примечание: This option is currently ignored by bootloaders other than
The bootloader theme object describing the theme to use. If no theme is provided, some bootloaders might use a default theme, that’s true for GRUB.
The output terminals used for the bootloader boot menu, as a list of
symbols. GRUB accepts the values:
pkmodem. This field corresponds to the GRUB
GRUB_TERMINAL_OUTPUT (see Simple configuration in GNU GRUB manual).
The input terminals used for the bootloader boot menu, as a list of
symbols. For GRUB, the default is the native platform terminal as
determined at run-time. GRUB accepts the values:
usb_keyboard. This field corresponds to the GRUB variable
GRUB_TERMINAL_INPUT (see Simple configuration in GNU GRUB
The serial unit used by the bootloader, as an integer from 0 to 3. For GRUB, it is chosen at run-time; currently GRUB chooses 0, which corresponds to COM1 (see Serial terminal in GNU GRUB manual).
The speed of the serial interface, as an integer. For GRUB, the default value is chosen at run-time; currently GRUB chooses 9600 bps (see Serial terminal in GNU GRUB manual).
Should you want to list additional boot menu entries via the
menu-entries field above, you will need to create them with the
menu-entry form. For example, imagine you want to be able to boot
another distro (hard to imagine!), you can define a menu entry along these
(menu-entry (label "The Other Distro") (linux "/boot/old/vmlinux-2.6.32") (linux-arguments '("root=/dev/sda2")) (initrd "/boot/old/initrd"))
The type of an entry in the bootloader menu.
The label to show in the menu—e.g.,
The Linux kernel image to boot, for example:
(file-append linux-libre "/bzImage")
For GRUB, it is also possible to specify a device explicitly in the file path using GRUB’s device naming convention (see Naming convention in GNU GRUB manual), for example:
If the device is specified explicitly as above, then the
is ignored entirely.
The list of extra Linux kernel command-line arguments—e.g.,
A G-Expression or string denoting the file name of the initial RAM disk to use (see G-Expressions).
The device where the kernel and initrd are to be found—i.e., for GRUB, root for this menu entry (see root in GNU GRUB manual).
This may be a file system label (a string), a file system UUID (a
bytevector, see Файловые системы), or
#f, in which case the
bootloader will search the device containing the file specified by the
linux field (see search in GNU GRUB manual). It must
not be an OS device name such as /dev/sda1.
The kernel to boot in Multiboot-mode (see multiboot in GNU GRUB manual). When this field is set, a Multiboot menu-entry is generated. For example:
(file-append mach "/boot/gnumach")
The list of extra command-line arguments for the multiboot-kernel.
The list of commands for loading Multiboot modules. For example:
For now only GRUB has theme support. GRUB themes are created using the
grub-theme form, which is not fully documented yet.
Data type representing the configuration of the GRUB theme.
gfxmode to set (a list of screen resolution strings,
see gfxmode in GNU GRUB manual).
Return the default GRUB theme used by the operating system if no
theme field is specified in
It comes with a fancy background image displaying the GNU and Guix logos.
For example, to override the default resolution, you may use something like
(bootloader (bootloader-configuration ;; … (theme (grub-theme (inherit (grub-theme)) (gfxmode '("1024x786x32" "auto"))))))