limine/README.md

# Limine

### What is Limine?

Limine is a modern, advanced, portable, multiprotocol bootloader, also used
as the reference implementation for the [Limine boot protocol](/PROTOCOL.md).

### Limine's boot menu

![Reference screenshot](/screenshot.png?raw=true "Reference screenshot")

[Photo by Lívia Bittencourt](https://www.pexels.com/photo/big-sea-waves-under-rainbow-and-cloudy-sky-4636525/)

### Supported architectures
* IA-32 (32-bit x86)
* x86_64
* aarch64 (arm64)

### Supported boot protocols
* Linux
* [Limine](/PROTOCOL.md)
* Multiboot 1
* Multiboot 2
* Chainloading

### Supported filesystems
* ext2/3/4
* FAT12/16/32
* ISO9660 (CDs/DVDs)

Even though these are the filesystems Limine supports directly, *any*
filesystem can be utilised by the kernel provided that the kernel (and any
needed modules) are on a directly supported filesystem.

### Supported partitioning schemes
* MBR
* GPT
* Unpartitioned media

### Minimum system requirements
For 32-bit x86 systems, support is only ensured starting with those with
Pentium Pro (i686) class CPUs.

All x86_64 and aarch64 (UEFI) systems are supported.

[![Packaging status](https://repology.org/badge/vertical-allrepos/limine.svg)](https://repology.org/project/limine/versions)

## 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](https://github.com/limine-bootloader/limine/branches/all) and
[tags](https://github.com/limine-bootloader/limine/tags)).

For example, to clone the latest binary release of the `v4.x` branch one can do
```bash
git clone https://github.com/limine-bootloader/limine.git --branch=v4.x-branch-binary --depth=1
```
or, to clone a specific binary point release (for example `v4.20221007.0`)
```bash
git clone https://github.com/limine-bootloader/limine.git --branch=v4.20221007.0-binary --depth=1
```

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

`limine-deploy.exe` binaries are provided for Windows.

## Building the bootloader

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

### Prerequisites

In order to build Limine, the following programs have to be installed:
common UNIX tools (also known as `coreutils`),
`GNU make`, `grep`, `sed`, `find`, `awk`, `gzip`, `nasm`, `mtools`
(optional, necessary to build `limine-cd-efi.bin`).
Furthermore, `gcc` or `llvm/clang` must also be installed, alongside
the respective binutils.

### 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`.

**`./configure` by default does not build any Limine port. Make sure to read the**
**output of `./configure --help` and enable any or all ports!**

To build using the LLVM toolchain, pass `CROSS_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:
```bash
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 `share`, `include`, and
`bin` directories in the specified prefix (default is `/usr/local`, see
`./configure --help`, or the `PREFIX` variable if installing from a binary release).

To install Limine, run:
```bash
make install    # (or gmake where applicable)
```

## How to use

### UEFI
The `BOOT{IA32,X64,AA64}.EFI` files are valid EFI applications that can be simply copied to
the `/EFI/BOOT` directory of a FAT formatted EFI system partition. These files 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` files in
either the root, `limine`, `boot`, or `boot/limine` 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:

```bash
limine-deploy <path to device/image>
```

The boot device must to contain the `limine.sys` and `limine.cfg` files in
either the root, `limine`, `boot`, or `boot/limine` 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:

```bash
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, `limine`, `boot`, or `boot/limine` 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, `limine`, `boot`, or
`boot/limine` directory; `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.

### UEFI/PXE boot
The `BOOT{IA32,X64,AA64}.EFI` files are compatible with UEFI PXE.
The steps needed to boot Limine are the same as with BIOS PXE,
except that you don't need `limine.sys` in the server.

### Configuration
The `limine.cfg` file contains Limine's configuration.

An example `limine.cfg` file can be found in [`test/limine.cfg`](https://github.com/limine-bootloader/limine/blob/trunk/test/limine.cfg).

More info on the format of `limine.cfg` can be found in [`CONFIG.md`](https://github.com/limine-bootloader/limine/blob/trunk/CONFIG.md).

## Acknowledgments
Limine uses a stripped-down version of [tinf](https://github.com/jibsen/tinf).

## Discord server
We have a [Discord server](https://discord.gg/QEeZMz4) if you need support,
info, or you just want to hang out with us.