Limine

Quick note

This fork of limine is taken from the flat-os which in turn is taken form limine.
FlatOS adds support for the FlatFS which is used in MandelbrotOS.

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.

Photo by Nishant Aneja from Pexels

Supported boot protocols

Linux
stivale and stivale2 (Limine's native boot protocols, see STIVALE{,2}.md for details)
Chainloading

Supported filesystems

ext2/3/4
echfs
FlatFS
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 v2.0 branch one can do

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

or, to clone a specific binary point release (for example v2.0.1)

git clone https://github.com/MandelbrotOS/limine.git --branch=v2.0.1-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 the
next paragraph.

It is necessary to first build the set of tools that the bootloader needs
in order to be built.

This can be accomplished by running:

make toolchain

The above step may take a while

After that is done, the bootloader itself can be built with:

make

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 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:

genisoimage -no-emul-boot -b <relative path of limine-cd.bin> \
            -boot-load-size 4 -boot-info-table -o myiso.iso <root directory>

Note: genisoimage is usually part of the cdrtools package.

<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.

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.

adamtherookie/limine