HowTo: Dual Monitors (Xinerama/TwinView/MergedFB/Big-Desktop)
Features of this HowTo:
The following howto addresses and solves the problems of Linux's,especially (X)(K)Ubuntu's,
support (or lack of) for dual monitors.The howto is assorted into four driver-specific categorizes.
· Xinerama (open source and binary driver)
· nVidia-only TwinView (binary driver)
· ATI, Matrox MergedFB (open source driver)
· ATI-only BigDesktop (binary driver)
All four options perform the same function. However, because of the variations of graphics cards in the market, and the different supports provided by the card makers, procedures that enable dual monitor on one computer/card do not work for other computer/card. Each of the four methods has pros and cons of its own. They are listed below.
· “Xinerama is an extension to the X Window System which allows applications and window managers to use the two, or more, physical displays as one large virtual display.” --Wikipedia. In other words, it allows X, as we'll call the X Window System, to use more than one monitor for display.
o Pros: Since Xinerama is an extension of X, most graphics cards, including Intel Integrated Cards and Matrox Cards, work well with it.
o Cons: There are several known problems with Xinerama. It requires that the physical screens to have the same bit depth. Also in most implementations, OpenGL (3D) direct-rendering only works on one of the screns. Windows that should show 3D graphics on other screens tend to just appear black. However, the Solaris SPARC OpenGL implementation allows direct rendering to all screens in Xinerama mode.
· “TwinView is a mode of operation where two display devices (digital flat panels, CRTs, and TVs) can display the contents of a single X screen in any arbitrary configuration.” -TwinView Appendix G.
o Pros: Twinview merges two screens into one, “tricking” X to think that there is only one screen. This always provide better OpenGL direct-rendering.
o Cons: TwinView requires the binary nVidia Driver, which means only nVidia cards are supported.
· “Merged Framebuffer mode allows you to use 3D acceleration on both heads of a dualheaded Radeon card.” --MergedFB Wiki
o Pros: Similar to TwinView, MergedFB merges two screens into one, therefore supporting 3D direct-rendering on both screens.
o Cons: MergedFB only works with the open sources drivers (mga, ati, , which lack direct-rendering support for many Radeon models. MergedFB also limits 3D contexts to 2048x2048.
· BigDesktop allows for dual screen control by merging the 2 screens into one single screen, allowing direct rendering on both monitors.
Common Step for Each HowTo:
These steps are essential for the HowTos to work, please follow them precisely.
All commands give should be executed within terminal.
Refer to : http://ubuntuforums.org/showthread.php?t=221174