https://github.com/returninfinity/baremetal

A very minimal, resource efficient exo-kernel
https://github.com/returninfinity/baremetal

assembly baremetal baremetal-kernel kernel

Last synced: 21 days ago
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A very minimal, resource efficient exo-kernel

• Host: GitHub
• URL: https://github.com/returninfinity/baremetal
• Owner: ReturnInfinity
• License: mit
• Created: 2014-08-05T16:32:23.000Z (over 11 years ago)
• Default Branch: master
• Last Pushed: 2025-04-09T00:47:20.000Z (9 months ago)
• Last Synced: 2025-04-11T19:39:27.795Z (9 months ago)
• Topics: assembly, baremetal, baremetal-kernel, kernel
• Language: Assembly
• Homepage: http://www.returninfinity.com
• Size: 801 KB
• Stars: 709
• Watchers: 52
• Forks: 99
• Open Issues: 9
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          




# BareMetal

**Just enough kernel**

[![Assembly](https://img.shields.io/badge/x86--64-Assembly-blue)]()

[![License](https://img.shields.io/badge/license-MIT-blue.svg)](LICENSE)

[![CI](https://github.com/ReturnInfinity/BareMetal/actions/workflows/main.yml/badge.svg)](https://github.com/ReturnInfinity/BareMetal/actions/workflows/main.yml)

Exokernel • 100% Assembly • Virtual/Physical



Official repo of the BareMetal [exokernel](http://en.wikipedia.org/wiki/Exokernel). It's written from scratch in Assembly, designed for x86-64 hardware, with no dependencies except for the virtual/physical hardware. An ARM and/or RISC-V rewrite would be considered once hardware is standardized.

### Table of Contents

- [What it is](#what-it-is)

- [Architecture](#architecture)

- [Key features](#key-features)

- [Supported hardware](#supported-hardware)

- [Try it out](#try-it-out)

## What it is

BareMetal is a _very_ lean kernel. The name is a play on the phrase "bare metal" which means to run directly on physical or virtualized hardware. BareMetal also only offers the "bare essentials" required for a working operating system.

BareMetal provides basic support for symmetric multiprocessing, network, and storage access via a low-level abstraction layer.

## Architecture

BareMetal is an [exokernel](https://en.wikipedia.org/wiki/Exokernel) and offers a [single address space](https://en.wikipedia.org/wiki/Single_address_space_operating_system) system.

It is written in [assembly](https://en.wikipedia.org/wiki/Assembly_language) to achieve high-performance computing with a minimal footprint and a "[just enough operating system](https://en.wikipedia.org/wiki/JeOS)” approach.

The kernel is primarily targeted towards physical and [virtualized](https://en.wikipedia.org/wiki/Virtualization) environments for [cloud computing](https://en.wikipedia.org/wiki/Cloud_computing), or [HPC](https://en.wikipedia.org/wiki/High-performance_computing) clusters. It could also be used as a [unikernel](https://en.wikipedia.org/wiki/Unikernel).

> “Do not try to do everything. Do one thing well.” — Steve Jobs

The premise of the kernel is to "do one thing well" and that is to execute a program with zero overhead.

## Key features

* **BIOS/UEFI**: Both boot methods are supported via the companion Pure64 loader.

* **64-bit only**: Make use of the extra-wide and additional registers available in 64-bit mode.

* **Mono-processing, multi-core**: The system is able to execute a single program but can spread the work load amongst available CPU cores.

* **Extremely tiny memory footprint**: The kernel binary is less than 32KiB. BareMetal uses 4 MiB of RAM while running. The majority of its RAM usage is for required memory structures while operating in 64-bit mode, drivers/system buffers, and CPU stacks. All other system memory is dedicated to the running program.

* **Physical and virtual hardware support** with full virtualization, using [x86 hardware virtualization](https://en.wikipedia.org/wiki/X86_virtualization) whenever available (it is on most modern x86-64 CPU's). In principle BareMetal should run on any x86-64 hardware platform, even on a physical x86-64 computer, given appropriate drivers. Officially, we develop on [QEMU](http://www.qemu.org) and [VirtualBox](https://www.virtualbox.org), which means that you can run BareMetal on both Linux, Microsoft Windows, and Apple macOS.

## Supported Hardware

* CPU

  * Multi-core on 64-bit x86 systems (Intel/AMD)

* Bus

  * PCIe

  * PCI

  * xHCI (USB 3)

* Network

  * Gigabit

    * Intel 8254x Gigabit (e1000)

    * Intel 8257x Gigabit (e1000e)

  * 10 Gigabit

    * Intel 8259x 10 Gigabit (ixbge)

  * Virtual

    * Virtio-Net

* Storage

  * NVMe

  * AHCI (SATA)

  * Virtio-Blk

* HID (Human Interface Devices)

  * Input

    * PS/2 Keyboard

    * USB Keyboard

    * Serial

  * Output

    * LFB (linear frame buffer at native screen resolution with 1024x768x32bpp as fallback)

    * VGA text mode (80x25 characters with 16 colors)

    * Serial

## Try it out

See the [BareMetal-OS](https://github.com/ReturnInfinity/BareMetal-OS) repo for a full build environment.

// EOF