Recently there has been much talk about RandR 1.2 support with RadeonHD and Nouveau (among other drivers), and as a result we have been asked many times now "what is RandR, and why do I care?" Well, RandR is the "Resize and Rotate" extension in X.Org and the v1.2 update introduces new functionality such as dynamic hot-plugging support for display devices. To help those who may be new to Linux or just never took advantage of this X.Org technology, we have written a brief guide with some of the RandR basics.
As was mentioned in the introduction, RandR stands for Resize and Rotate. The RandR extension itself isn't new, with the original X Resize and Rotate Extension being drafted back in 2001, but RandR 1.2 had only premiered with X Server 1.3. Some of the common free software drivers that support RandR 1.2 include Nouveau, nv, xf86-video-ati, Avivo, and last but not least RadeonHD. Keith Packard does most of the RandR work, and the first open-source driver to support this updated extension was the open-source Intel driver. RandR 1.2 requires support from the X server as well as the driver supporting the extension specification, and then the system must have the Xrandr library.
While the most common way to control the RandR environment is through the xrandr CLI utility, there are several graphical-based programs for controlling RandR 1.2. One of the newest utilities to boast RandR 1.2 support is displayconfig-gtk from Ubuntu, while others include grandr (GTK+ interface), URandR (PyGTK interface), and in KDE 4.0 there will be support via KControl. If you are new to Linux or RandR usage, if you have a GUI utility available that would likely be your easiest solution. The usage in this guide is for those using the command-line xrandr utility.
Among the RandR features accessible through xrandr is for changing the resolution of the screen, rotating the screen, changing the DPI value and refresh rate of a monitor, and reflecting the screen over an axis. To the death of Xinerama, configuring all display devices and dynamically enabling or disabling them without restarting the X server can be done through xrandr / RandR 1.2. Aside from ensuring that the proper driver is loaded, you don't need to touch the xorg.conf when dealing with RandR nor should you need root access.