Limine

What is Limine?

Limine is an advanced x86/x86_64 BIOS/UEFI Bootloader which supports modern PC features such as Long Mode, 5-level paging, and SMP (multicore), to name a few.

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Limine's boot menu

Photo by Nishant Aneja from Pexels

Supported boot protocols

• Linux
• stivale and stivale2 (Limine's native boot protocols, see their specifications for details)
• Chainloading

Supported filesystems

• ext2/3/4
• echfs
• FAT16/32
• ISO9660 (CDs/DVDs)

Supported partitioning schemes

• MBR
• GPT
• Unpartitioned media

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 v2.x branch one can do

git clone https://github.com/limine-bootloader/limine.git --branch=v2.0-branch-binary --depth=1

or, to clone a specific binary point release (for example v2.4)

git clone https://github.com/limine-bootloader/limine.git --branch=v2.4-binary --depth=1

Additionally, the absolute latest Limine binary release can be obtained by fetching the latest-binary branch:

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

limine-install binaries are provided for Linux and Windows. In case one wants to rebuild limine-install, simply use make in the binary release.

Building the bootloader

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

Note that the build system does not support building from a directory whose full path contains spaces.

Building the toolchain

This step can take a long time, but it will ensure that the compiler will work with Limine. If on an x86_64 host, with GCC installed, you can also skip to the next paragraph.

The toolchain building process depends on the following packages: bash, make, wget, gcc, g++, binutils.

Building the toolchain can be accomplished by running:

make toolchain

The above step may take a while

Building Limine

In order to build Limine, the following packages have to be installed: bash, make, git, which, nasm, mtools. Furthermore, either the toolchain must have been built in the previous paragraph, or gcc and binutils must also be installed.

The bootloader can then be built with:

make

It is possible to pass make additional flags, most relevantly, TOOLCHAIN= which allows one to specify an alternative toolchain for the build system to use (the default is x86_64-elf, falling back to no-triple, or host, toolchain).

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 in a share and bin directories in the specified PREFIX (default is /usr/local).

Use make install to install Limine binaries, optionally specifying a prefix with a PREFIX=... option.

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 FAT32 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 by both BIOS and UEFI.

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-install as such:

limine-install <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-install 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-install as a second argument; such as:

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

In case one wants to let limine-install embed stage 2 within GPT's structures, simply omit the partition number, and invoke limine-install 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 CD-ROM ISO creation

In order to create a bootable BIOS ISO with Limine, place the 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.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 <root directory> -o image.iso

Note: xorriso is required.

<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.

UEFI CD-ROM ISO creation

In order to create a bootable UEFI ISO with Limine, place the limine-eltorito-efi.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-eltorito-efi.bin can reside anywhere).

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

xorriso -as mkisofs -eltorito-alt-boot -e <relative path of limine-eltorito-efi.bin> \
        -no-emul-boot <root directory> -o image.iso

Note: xorriso is required.

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

BIOS+UEFI CD-ROM ISO creation

Additionally, it is possible to combine the 2 aformentioned commands into a single one in order to create a CD ISO which will boot on both BIOS and UEFI:

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

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.

Example

For example, to create an empty image file of 64MiB in size, 1 echfs partition on the image spanning the whole device, format it, copy the relevant files over, and install Limine, one can do:

dd if=/dev/zero bs=1M count=0 seek=64 of=test.img
parted -s test.img mklabel msdos
parted -s test.img mkpart primary 1 100%
parted -s test.img set 1 boot on # Workaround for buggy BIOSes

echfs-utils -m -p0 test.img quick-format 32768
echfs-utils -m -p0 test.img import path/to/limine.sys limine.sys
echfs-utils -m -p0 test.img import path/to/limine.cfg limine.cfg
echfs-utils -m -p0 test.img import path/to/kernel.elf kernel.elf
echfs-utils -m -p0 test.img import <path to file> <path in image>
...
limine-install test.img

One can get echfs-utils by installing https://github.com/echfs/echfs.

Acknowledgments

Limine uses a stripped-down version of tinf.

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