Editing XFree86 (section)

== Architecture ==
[[File:Schema of the layers of the graphical user interface.svg|thumb|300px|XFree86 is a [[display server]].]]

The XFree86 server communicates with the host [[operating system]]'s [[Kernel (operating system)|kernel]] to drive input and output devices, with the exception of [[graphics card]]s. 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 certain accelerated 3D graphics cards via the [[GLX]] and [[Direct Rendering Infrastructure|DRI]] extensions. Version 4.0 also moved to a new driver model, from one X server binary per driver to a unique X server capable of loading several drivers at a time.

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 [[user identifier|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 [[Linux framebuffer|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 [[Computer display|screen]] (monitor), [[computer keyboard|keyboard]] and [[graphics card]]. The program ''xf86config'' is often used, although ''xf86cfg'' also comes with the XFree86 server and is friendlier. Many Linux distributions used to include a configuration tool that was easier to use (such as [[Debian]]'s [[debconf (software package)|debconf]]) or autodetected most (if not all) settings (such as [[Red Hat Linux]] and [[Fedora (operating system)|Fedora]]'s ''[[Anaconda installer|Anaconda]]'', [[SUSE S.A.|SuSE]]'s ''[[YaST]]'' and [[Mandrake Linux]]).