Fedora Linux

3.4.1. How Do I Do That?

Output from one card to multiple monitors is supported only by some drivers. The most commonly used ones are the NVIDIA and ATI proprietary drivers, and the open source Radeon driver. All of these drivers have some limitations; for example, the NVIDIA driver, when used on a laptop, will always configure an external monitor as primary (screen 0), and the ATI drivers permit only general monitor positioning (you can specify that one monitor is to the right of another, but you can't indicate a difference in their vertical alignment).

3.4.1.1. Configuring dual video on an NVIDIA card

Note that for the changes described in this section to take effect, you will need to restart the X server in one of these ways: changing to runlevel 3 and then back to 5, restarting the system, or terminating the running X server with Ctrl-Alt-Backspace (save your work first!).

First, configure and test your system using the NVIDIA proprietary driver (see Lab 5.3, 'Using Repositories '), and then add the highlighted lines to the Device section of your /etc/X11/ xorg.conf file:

Section 'Device'
 Identifier 'Card0'
 Driver 'nvidia'
 VendorName 'nVidia Corporation'
 BoardName 'NV34 [GeForce FX 5200]'
 BusID 'PCI:1:0:0'
 Option 'TwinView'
 Option 'SecondMonitorHorizSync' '31.0 - 80.0'
 Option 'SecondMonitorVertRefresh' '50.0 - 75.0'
 Option 'TwinViewXineramaInfo' 'on'
 Option 'MetaModes' '800x600,1024x768'
 Option 'TwinViewOrientation' 'LeftOf'
EndSection

The SecondMonitorHorizSync and SecondMonitorVertRefresh options configure the horizontal and vertical frequency ranges for the second monitor (the settings for the primary monitor are in the Monitor section of the file). The values given here are reasonable for most small monitors. The TwinViewXineramaInfo line configures the driver to inform applications about the fact that the desktop is on two screens, so that windows can be placed intelligently (avoiding dialog boxes that span both screens, for example).

The MetaModes option configures the relative sizes of the two screens; the first screen is always the external display. The TwinViewOrientation specifies the position of the second display relative to the first for the purpose of mouse movement and window positioning (possible values are Above , Below , LeftOf , or RightOf ).

For finer control over the monitor relationships, the positions of each monitor may be specified in the MetaModes line as an absolute position within the entire desktop. These values are given in the form + X + Y after each resolution; for example, '800x600+0+0,1024x768+800+0' specifies that the primary monitor is to the left of the secondary monitor and that the two monitors are aligned at the top, and '800x600+1024+168,1024x768+0+0' specifies that the primary monitor is on the right and that the monitors are aligned at the bottom (168 pixels is the difference between the two monitor heights, 768 and 600 pixels).

When using the external monitor connection for projection, it can be convenient to project a subset of what is shown on the laptop's panel. Using the NVIDIA driver, this can be configured by overlapping the two display regions using the MetaModes option. On a laptop with a 1400x1050 display, for example, you can project an 800x600 pixel subset to your audience:

Section 'Device'
 Identifier 'Card0'
 Driver 'nvidia'
 VendorName 'nVidia Corporation'
 BoardName 'NV34 [GeForce FX 5200]'
 BusID 'PCI:1:0:0'
 Option 'TwinView'
 Option 'SecondMonitorHorizSync' '31.0 - 80.0'
 Option 'SecondMonitorVertRefresh' '50.0 - 75.0'
 Option 'TwinViewXineramaInfo' 'on'
 Option 'MetaModes' '800x600+200+200,1400x1050+0+0'
EndSection

When you restart the X server, the GNOME panel bars will be located in the middle of the screen, because the smaller 800x600 subset display is considered 'Primary.' Drag the panels to the top and bottom of the laptop display. You can then start an application and position the portion of the window that you wish to display into the 800x600 pixel area that starts 200 pixels down and 200 pixels to the right of the upper-left corner of the screen.

This works well with OpenOffice.org Impress in 'Normal' mode, which displays three panes, including the current image in the center and a preview of slides on the left (the panes can be rearranged if it is more convenient to see the preview on the right). Reposition the dividing line between the panes and scroll the center pane until the current slide completely fills the external display.

This configuration enables you to preview the slides using the OpenOffice.org preview plane as shown in Figure 3-22 without changing the projected slide. Once you select and then click on a slide, it becomes the current slide and is displayed both in the center plane of the LCD image and on the external projector, shown in Figure 3- 23 .

Figure 3-22. LCD display, including slide preview pane (right)

Figure 3-23. Projected 800 600 subset of LCD image, showing only the current slide

3.4.1.2. Configuring dual video on an ATI graphics card using the open source driver

First, configure and test your system using the ATI open source driver radeon , and then add the lines highlighted in bold to the Device section of your /etc/X11/