XFree86 is an implementation of the X Window System. It was originally written for Unix-like operating systems on IBM PC compatibles and is now available for many other operating systems and platforms. It is free and open source software under the XFree86 License version 1.1. It is developed by the XFree86 Project, Inc.; the lead developer is David Dawes. The current version is 4.7.0.

For most of the 1990s and early 2000s, the project was the source of most innovation in X and was the de facto steward of X development. Until early 2004, it was almost universal on Linux and the BSDs.

In February 2004, with version 4.4.0, The XFree86 Project adopted a license change that the Free Software Foundation considered GPL incompatible. Most Linux distributions found the potential legal issues unacceptable and made plans to move to a fork from before the license change. At first there were multiple forks, but the X.Org fork soon became the dominant one. Most XFree86 developers who were already annoyed at other issues in the project also moved to X.Org.

Architecture

XFree86 consists of client libraries used to write X applications ("clients"), and an X server responsible for the display. Clients and servers communicate via the X protocol, which allows them to run on different computers.

The XFree86 server communicates with the host operating system's kernel to drive input and output devices, with the exception of graphics cards. These are generally managed directly by XFree86, so it includes its own drivers for all graphic cards a user might have. Some cards are supported by vendors themselves via binary-only drivers.

Since version 4.0, XFree86 has supported (some) accelerated 3D graphics cards via the GLX and DRI extensions.

Because the server usually needs low level access to graphics hardware, on many configurations it needs to run as the superuser, or a user with UID 0. However, on some systems and configurations it is possible to run the server as a normal user.

It is also possible to use XFree86 in a framebuffer device, which in turn uses a kernel graphics card driver.

On a typical POSIX-system, the directory /etc/X11 includes the configuration files. The basic configuration file is /etc/X11/XF86Config (or XF86Config-4) that includes variables about the screen (monitor), keyboard and graphics card. The program xf86config is often used, although xf86cfg also comes with the XFree86 server and is certainly friendlier. Many Linux distributions used to include a configuration tool that was easier to use (such as Debian's debconf) or autodetected most (if not all) settings (Red Hat Linux and Fedora's Anaconda, SuSE's YaST and Mandrake Linux used to choose this path).

History

Early history and naming

The project began in 1992 when David Wexelblat, Glenn Lai, David Dawes and Jim Tsillas joined forces addressing bugs in the X11 X386 source code (written by Thomas Roell), as contributed to X11R5. This version was initially called X386 1.2E. As newer versions of the (originally freeware) X386 were being sold under a proprietary software license by SGCS (of which Roell was a partner), confusion existed between the projects. After discussion, the project was renamed XFree86, as a pun (compare X-three-eighty-six to X-free-eighty-six). Roell has continued to sell proprietary X servers, most recently under the name Accelerated-X.

Rise with Linux

As Linux grew in popularity, XFree86 rose with it, as the main X project with drivers for PC video cards.

By the late 1990s, official X development was moribund http://www.computerworld.com/softwaretopics/software/appdev/story/0,10801,67861,00.html. Most technical advancement was happening in the XFree86 project. In 1999, XFree86 was sponsored onto X.Org (the official industry consortium) by various hardware companies http://slashdot.org/article.pl?sid=99/12/01/1342251&tid=104 interested in its use with Linux and its status as the most popular version of X.

2003: dissent within the project

By 2003, while Linux's popularity, and hence the installed base of X, surged, X.Org was all but inactive http://xfree86.org/pipermail/forum/2003-April/003127.html and active development was largely carried out by XFree86. However, there was considerable dissent within XFree86. It was perceived as far too cathedral-like in its development model: developers were unable to get CVS commit access http://www.xfree86.org/pipermail/forum/2003-March/002018.html and vendors had to maintain extensive patches http://www.advogato.org/person/mharris/diary.html?start=5. In March, long-term contributor Keith Packard was ejected from the Core Team with considerable ill-feeling http://www.xfree86.org/pipermail/forum/2003-March/001997.html http://www.xfree86.org/pipermail/forum/2003-March/002165.html http://www.xfree86.org/pipermail/forum/2003-April/003016.html. The Core Team claimed that Keith had been trying to fork the XFree86 project by working inside the project while trying to attract core developers to a new X Server project of his own making. Packard denied this had been his aim.

Disbanding of the Core Team

XFree86 used to have a Core Team which was made up of experienced developers, selected for their merits. Due to limited innovation capacity the XFree86 Core Team voted on December 30, 2003 to disband itself, effective the following day.

2004: Licensing controversy

Versions of XFree86 up to and including some release candidates for 4.4.0 were under the MIT License, a permissive, non-copyleft free software license. XFree86 4.4 was released in February 2004 with a change to the license: the addition of a credit clause^[1], similar to that in the original BSD license^[2], but broader in scope. Many projects relying on XFree86 found the new license unacceptable^[3], and the Free Software Foundation considered it incompatible with the GNU General Public License. The XFree86 Project contests this, maintaining that the license is compatible with the GPL^[4].

Some projects made releases (notably OpenBSD 3.5 and 3.6, and Debian 3.1 "Sarge") based on XFree86 version 4.4 RC2, the last version under the old license. Most operating systems incorporating XFree86 (including later versions of OpenBSD and Debian) migrated to the X.Org Server^[5].

Forks of XFree86

X.Org

The X.Org Server became the official reference implementation of X11. The first version, X11R6.7.0, was a fork from XFree86 version 4.4 RC2, with X11R6.6 changes merged in. Version X11R6.8 added many new extensions, drivers and fixes. It is not encumbered by the XFree86 license changes. It is hosted by and works closely with freedesktop.org.

Most of the open-source Unix-like operating systems have adopted the X.Org Server in place of XFree86, and most of the XFree86 developers moved to X.Org http://www.dwheeler.com/essays/gpl-compatible.html#xfree86.

Release history

See also

• DirectFB
• XFree86 logfile
• XFree86 Modeline
• XF86Config

References

• X Marks the Spot: Looking back at X11 Developments of Past Year (Oscar Boykin, OSNews 25 February 2004) — the licensing controversy and forks
• The History of XFree86: Over a Decade of Development (Michael J. Hammel, Linux Magazine, December 2001)
• Some perspective from the cheap seats ... (David Wexelblat, 20 March 2003) — on why Keith Packard was sacked from the core team
• A Call For Open Governance Of X Development (Keith Packard, 21 March 2003)
• XFree86 dust-up questions X11 model (Andrew Orlowski, The Register, 21 March 2003)
• The Cautionary Tale of XFree86 (from Make Your Open Source Software GPL-Compatible. Or Else. by David A. Wheeler, 16 February 2005)

External links

• Project home page
• Sample XFree86 configuration files
• What Happened to the XFree86 Project (essay)

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