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176 Stars 40 Forks GNU General Public License v2.0 1.6K Commits 3 Opened issues


First published Open Source implementation of OpenFirmware

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Welcome to OpenBIOS

OpenBIOS is a free, portable implementation of IEEE 1275-1994 (Open Firmware). Find detailed information about OpenBIOS at

What is OpenBIOS?

OpenBIOS can replace your system firmware (BIOS) partly or completely. It can also be used as a bootloader to create an Open Firmware compatible interface between legacy firmware and an operating system.

This is achieved by a modular concept that consists of a portable Forth kernel and three interfaces for user interaction, device initialization and client (operating system) control.

While far not all possible applications of OpenBIOS are implemented yet, a lot of functionality is already there. OpenBIOS can be used to enhance LinuxBIOS (, or be booted from any multiboot capable bootloader to bring Open Firmware to your machine. OpenBIOS can also be used when an operating system is already running. It provides the needed OpenFirmware functionality to MOL (MacOnLinux) to boot MacOS 9 and X on PPC machines, as well as Linux (all supported platforms)

OpenBIOS build options

config/scripts/switch-arch - build for specified platform Look in config/example for platforms.

make - build all configured binaries

make run - run unix example.

How OpenBIOS works

The OpenBIOS forth core is split into a forth kernel written in portable C and a forth dictionary which operated on by the kernel.

When building the forth core, you get different versions of the forth kernel:

  • a unix executable program

    • to execute a forth dictionary from a file. This can be used for easily testing and developing OpenBIOS on a unix host.
    • to create a dictionary file. Such a dictionary file sets up all of the forth language. Primitives are indexed to save relocations.

    The default is to create a forth dictionary forth.dict from forth/start.fs. This file includes all of the basic forth language constructs from forth/bootstrap.fs and starts the interpreter.

    To achieve this, the hosted unix version contains a basic set of forth words coded in C that allow creating a full dictionary.

  • a varying number of target specific binaries. On x86 you can start openbios for example from GRUB or LinuxBIOS. They are all based on the same forth engine consisting of a dictionary scheduler, primitive words needed to build the forth environment, 2 stacks and a simple set of console functions. These binaries can not be started directly in the unix host environment.


  • gcc
  • gnu make
  • OpenBIOS FCode Utils Download with svn co svn://
  • grub or any other multiboot loader to run the multiboot binary "openbios.multiboot" with it's module "openbios-.dict"
  • xsltproc

Building & Usage

  • make

this builds "openbios.multiboot", the standalone image and "openbios-unix", the hosted image. Additionally it creates a forth dictionary file from forth/start.fs. All generated files are written to the absolute directory held by the variable BUILDDIR, which defaults to obj-[platform]. Some compile time parameters can be tweaked in include/config.h

  • use "openbios-unix" to create a forth dictionary on your own: $ obj-x86/openbios-unix -Iforth start.fs creates the file forth.dict from forth source forth/start.fs.

  • use "openbios-unix" to run a created dictionary: $ obj-x86/openbios-unix obj-x86/openbios-unix.dict This is useful for testing

  • booting openbios You can boot openbios i.e. in grub. Add the following lines to your menu.lst:

    title openbios kernel (hd0,2)/boot/openbios.multiboot module (hd0,2)/boot/openbios-x86.dict

Note: change (hd0,2) to the partition you copied the openbios image and openbios-x86.dict to.

To boot OpenBIOS from LinuxBIOS/etherboot, you can either use "openbios-plain.elf" or "openbios-builtin.elf":

  • openbios-plain.elf is the pure kernel that loads the dictionary from a hardcoded address in flash memory (0xfffe0000)

  • openbios-builtin.elf also includes the dictionary directly so that it can be easily used from etherboot or the LinuxBIOS builtin ELF loader without taking care of the dictionary


OpenBIOS was developed by Stefan Reinauer, Samuel Rydh and Patrick Mauritz. The OpenBIOS IDE driver was written by Jens Axboe. For license details on this piece of software, see the file COPYING.

If you have patches, questions, comments, feel free to contact the OpenBIOS mailinglist.

Regards, the OpenBIOS team

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