How can I configure multiple monitors in Linux?

The ATI Proprietary Linux driver provides support for a wide variety of monitor configurations. The following fglrxconfig options can be used to configure displays:

  • Enable TV Out (if one of the displays is a TV)

    • Yes or No

  • Select Monitor configuration

    • See below for available configurations

  • Configure monitor arrangement (if more than one monitor is connected)

    • Horizontal: select whether screen 1 is left or right of screen 0

    • Vertical: select whether screen 1 is above or below screen 0

  • Set Primary and Secondary monitors

    • Secondary monitor may not have all the same features as Primary

  • Choose available resolutions

    • These should not exceed the capabilities of your monitor

Simply run 

fglrxconfig

and provide the desired answers at the appropriate prompts. Answer yes when asked to update the XF86Config file. Your new settings should take effect the next time you start X.

Monitor Layout Configurations

The following Monitor configurations are available:

Mode

Screens

Description

Single Head

1

single display only, the second remains dark

Laptop Mode

2

toggle between internal or external screen

Clone Mode

2

same content on both screens

Big Desktop

2

one desktop stretched across both screens

Dual Head

2

separate instances of XFree86 on each screen

For Big Desktop and Dual Head modes, a vertical or horizontal orientation can be selected. In some cases, it is also possible to select which monitor will be Primary and which will be Secondary.

Some of these configurations allow for extremely large desktop resolutions. Please note the maximum resolutions for OpenGL operation are as follows:

Resolution

Family

Boards

2560x2560

R300

Radeon 9500-9800, FireGL Z1/X1/X2

2048x2048

R200

Radeon 8500-9200, FireGL 8700/8800/E1

3D windows may corrupt or go blank if stretched beyond this limit.

The various monitor layout configurations have the following features and limitations:

Single Head
  • Single monitor operation only
  • If a second monitor is connected, it remains dark
  • Only mode available if you have only one monitor connected
  • Only mode in which Quad Buffer Stereo will work properly
  • The only mode in which full overlay support will be available
Clone
  • Contents of primary monitor are duplicated on the second monitor
  • If one of the monitors cannot display the selected resolution:
    • A lower resolution is automatically selected for that monitor
    • It will behave as a virtual desktop at the original resolution
    • The smaller screen will pan as the mouse moves around
Big Desktop
  • A single desktop is stretched across both monitors
  • Monitors may overlap by a configurable number of pixels
  • Both monitors have to operate with the same video mode settings
  • Both screens use a single framebuffer and only one window manager
    • The smaller display will NOT autoscroll as in Clone Mode
  • Big Desktop can be configured for Horizontal or Vertical operation
Dual Head
  • Independent displays and video modes are possible for each monitor
  • Each monitor uses a separate framebuffer and separate instance of XFree86
    • Items CANNOT be dragged from one screen to the other
  • It is possible to run two separate window managers in this configuration
    (one on each monitor)
  • Please note that fireglcontrol panel cannot be used to configure Dual Head mode.
    Dual Head mode must be configured manually or through fglrxconfig.

INFO-BASE#4485