Limine

What is Limine?

Limine is a modern, advanced x86/x86_64 BIOS/UEFI multiprotocol bootloader, used as the reference implementation for the Limine boot protocol.

Limine's boot menu

Photo by Martin Damboldt from Pexels

Supported boot protocols

• Linux
• Limine
• stivale and stivale2 (see their specifications for details)
• Multiboot 1
• Multiboot 2
• Chainloading

Supported filesystems

• ext2/3/4
• echfs
• FAT12/16/32
• NTFS
• ISO9660 (CDs/DVDs)

Supported partitioning schemes

• MBR
• GPT
• Unpartitioned media

Minimum system requirements

While Limine is made with modern, 64-bit, PCs in mind, it supports 32-bit ones as well, starting with PCs with Pentium Pro class CPUs.

Binary releases

For convenience, for point releases, binaries are distributed. These binaries are shipped in the -binary branches and tags of this repository (see branches and tags).

For example, to clone the latest binary release of the v3.x branch one can do

git clone https://github.com/limine-bootloader/limine.git --branch=v3.0-branch-binary --depth=1

or, to clone a specific binary point release (for example v3.5)

git clone https://github.com/limine-bootloader/limine.git --branch=v3.5-binary --depth=1

limine-deploy binaries are provided for Windows.

In order to rebuild limine-deploy, simply run make in the binary release directory.

Building the bootloader

The following steps are not necessary if cloning a binary release. If so, skip to "Installing Limine binaries".

Building the toolchain

This step can take a long time, but it will ensure that the toolchain will work with Limine. If on an x86_64 host, with GCC or Clang installed, it is possible that the host toolchain will suffice. You can skip to the next paragraph in order to use the system's toolchain instead. If that fails, you can still come back here later (remember to make clean and re-run ./configure after building the toolchain).

The toolchain's build process depends on the following packages: GNU make, GNU tar, texinfo, curl, gzip, bzip2, gcc/clang, g++/clang++.

Building the toolchain can be accomplished by running:

TARGET=<target architecture> ./make_toolchain.sh

where <target architecture> is something like i686 or x86_64.

Prerequisites

In order to build Limine, the following programs have to be installed: GNU make, grep, sed, find, awk, gzip, nasm, mtools (optional, necessary to build limine-cd-efi.bin). Furthermore, either the toolchain must have been built in the previous paragraph, or gcc or llvm/clang must also be installed, alongside the respective binutils. nasm is optional if the toolchain was built in the previous paragraph as it is built as part of it.

Configure

If using a release tarball (recommended, see https://github.com/limine-bootloader/limine/releases), run ./configure directly.

If checking out from the repository, run ./bootstrap first in order to download the necessary dependencies and generate the configure script (GNU autoconf and GNU automake required).

./configure takes arguments and environment variables; for more information on these, run ./configure --help.

To build using the LLVM toolchain, pass TOOLCHAIN=llvm to ./configure.

Limine supports both in-tree and out-of-tree builds. Simply run the configure script from the directory you wish to execute the build in. The following make commands are supposed to be ran inside the build directory.

Building Limine

To build Limine, run:

make    # (or gmake where applicable)

The generated bootloader files are going to be in bin.

Installing Limine binaries

This step is optional as the bootloader binaries can be used from the bin or release directory just fine. This step will only install them to a share and bin directories in the specified prefix (default is /usr/local, see ./configure --help, or the PREFIX variable if installing a binary release).

To install Limine, run:

make install    # (or gmake where applicable)

How to use

UEFI

The BOOTX64.EFI file is a vaild EFI application that can be simply copied to the /EFI/BOOT directory of a FAT formatted EFI system partition. This file can be installed there and coexist with a BIOS installation of Limine (see below) so that the disk will be bootable on both BIOS and UEFI systems.

The boot device must to contain the limine.cfg file in either the root or the boot directory of one of the partitions, formatted with a supported file system (the ESP partition is recommended).

BIOS/MBR

In order to install Limine on a MBR device (which can just be a raw image file), run limine-deploy as such:

limine-deploy <path to device/image>

The boot device must to contain the limine.sys and limine.cfg files in either the root or the boot directory of one of the partitions, formatted with a supported file system.

BIOS/GPT

If using a GPT formatted device, there are 2 options one can follow for installation:

• Specifying a dedicated stage 2 partition.
• Letting limine-deploy attempt to embed stage 2 within GPT structures.

In case one wants to specify a stage 2 partition, create a partition on the GPT device of at least 32KiB in size, and pass the 1-based number of the partition to limine-deploy as a second argument; such as:

limine-deploy <path to device/image> <1-based stage 2 partition number>

In case one wants to let limine-deploy embed stage 2 within GPT's structures, simply omit the partition number, and invoke limine-deploy the same as one would do for an MBR partitioned device.

The boot device must to contain the limine.sys and limine.cfg files in either the root or the boot directory of one of the partitions, formatted with a supported file system.

BIOS/UEFI hybrid ISO creation

In order to create a hybrid ISO with Limine, place the limine-cd-efi.bin, limine-cd.bin, limine.sys, and limine.cfg files into a directory which will serve as the root of the created ISO. (limine.sys and limine.cfg must either be in the root or inside a boot subdirectory; limine-cd-efi.bin and limine-cd.bin can reside anywhere).

Place any other file you want to be on the final ISO in said directory, then run:

xorriso -as mkisofs -b <relative path of limine-cd.bin> \
        -no-emul-boot -boot-load-size 4 -boot-info-table \
        --efi-boot <relative path of limine-cd-efi.bin> \
        -efi-boot-part --efi-boot-image --protective-msdos-label \
        <root directory> -o image.iso

Note: xorriso is required.

And do not forget to also run limine-deploy on the generated image:

limine-deploy image.iso

<relative path of limine-cd.bin> is the relative path of limine-cd.bin inside the root directory. For example, if it was copied in <root directory>/boot/limine-cd.bin, it would be boot/limine-cd.bin.

<relative path of limine-cd-efi.bin> is the relative path of limine-cd-efi.bin inside the root directory. For example, if it was copied in <root directory>/boot/limine-cd-efi.bin, it would be boot/limine-cd-efi.bin.

BIOS/PXE boot

The limine-pxe.bin binary is a valid PXE boot image. In order to boot Limine from PXE it is necessary to setup a DHCP server with support for PXE booting. This can either be accomplished using a single DHCP server or your existing DHCP server and a proxy DHCP server such as dnsmasq.

limine.cfg and limine.sys are expected to be on the server used for boot.

Configuration

The limine.cfg file contains Limine's configuration.

An example limine.cfg file can be found in test/limine.cfg.

More info on the format of limine.cfg can be found in CONFIG.md.

Acknowledgments

Limine uses a stripped-down version of tinf.

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