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BareMetal OS is an exokernel-based operating system crafted entirely in x86-64 assembly and is designed to provide unparalleled levels of flexibility and efficiency. By exposing hardware resources directly to applications, it empowers developers to finely tune and optimize their software for specific tasks. With the exokernel's minimalist design, it minimizes the overhead imposed by traditional operating systems, enabling applications to achieve peak performance. Its x86-64 assembly implementation speaks to its commitment to squeezing every ounce of performance from the hardware, making it a compelling choice for those who demand the utmost control and efficiency from their computing environments.


BareMetal OS is under active development. Some physical hardware configurations may not work correctly.

Table of Contents


The script in this repo depends on a Debian-based Linux system like Ubuntu or Elementary. macOS is also supported to build and test the OS, as well as the Assembly applications, if you are using Homebrew.

  • NASM - Assembly compiler to build the loader and kernel, as well as the apps written in Assembly.
  • QEMU - Computer emulator if you plan on running the OS for quick testing.
  • GCC - C compiler for building C/C++ applications.
  • Git - Version control software for pulling the source code from GitHub.
  • mtools - Utilities to access DOS (FAT32) disk images in Unix.

In Linux this can be completed with the following command:

sudo apt install nasm qemu-system-x86 gcc git mtools

In macOS via Homebrew this can be completed with the following command:

brew install nasm qemu gcc git mtools


BareMetal OS consists of several different projects:

Supported Hardware

  • CPU
    • Multi-core on 64-bit x86 systems (Intel/AMD)
  • Bus
    • PCIe
    • PCI
  • Network
    • Intel 8254x Gigabit (e1000)
    • Intel 8257x Gigabit (e1000e)
    • Realtek 816x/811x Gigabit (rtl8169)
    • Virtio-Net
  • Storage
    • NVMe
    • AHCI (SATA)
    • IDE
    • Virtio-Blk

Initial configuration

git clone
cd BareMetal-OS
./ setup setup automatically runs the build and install functions. Once the setup is complete you can execute run to verify that everything installed correctly.


./ build


Installing the system

./ install

This command installs the boot sector, loader (Pure64), kernel, and simple command line interface (Monitor) to the disk image. If you want to attach your own binary to the end of the kernel you can use ./ install mybinary.bin

Installing the demos

./ demos

This command installs the demo programs to the disk image.

Running on a virtual system


./ run


./ run-uefi

QEMU - Second Instance

./ run-2

Running a cloned second instance is useful for testing network connectivity between QEMU systems.


./ vmdk


./ vdi

The VDI script rewrites the disk ID of the VDI file to avoid the disk warning in VirtualBox.


bochs -f bochs.cfg


  • The bochs.cfg file may need to be adjusted for your usage. It was created for a Linux-based system.
  • display_libary is set to use x for X Windows with the GUI Debugger by default. On macOS or Windows you will need to use sdl2 with no additional options.
  • The file paths for romimage and vgaromimage will need to be updated if the Bochs BIOS files are in a different location.

Running on a physical system


Booting from a USB drive should work but BareMetal does not have a USB storage driver so you will not be able to load any programs after the command line interface comes up.


Doublecheck that you are writing the disk image to the correct disk

dd if=baremetal_os.img of=/dev/sdc

Once the disk image is written you can install the disk in the system and boot from it.

// EOF


Build script for BareMetal OS and its related utilities