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5: Troubleshooting
Configuring a System for Dual-Channel Operation
To configure a system for dual-channel operation, follow the steps in this section.
Note:
If any pipes managed by an X server have their second channel enabled, then
every pipe managed by that X server must have its second channel enabled.
Note:
Both channels on a pipe must have the same display resolution.
1.
Create a copy of the XF86Config file to be customized for dual-channel operation:
# cp /etc/X11/XF86Config /etc/X11/XF86Config.DualChannel
2. Edit the new
XF86Config.DualChannel
file to include the following line at the
end of each “Device” section:
Option "DesktopSetup"
mode
where mode is one of the following:
"0x00000100" [this mode clones the managed area]
"0x00000200" [this mode scales the managed area by 2 horizontally]
"0x00000300" [this mode scales the managed area by 2 vertically]
(see the example “Device” section on page 139).
Note:
All pipes managed by the same X server must be set to the same mode.
3. When using monitors or monitor cables which do not conform to the VESA Display
Data Channel (DDC) standard, append the following entry in the “Device” section
to enable proper display configuration:
Option "NoDDC" "on"
4. Make a backup copy of the default
/etc/X11/gdm/gdm.conf
file:
# cp /etc/X11/gdm/gdm.conf /etc/X11/gdm/gdm.conf-old
5. Edit the
/etc/X11/gdm/gdm.conf
file to use the new
XF86Config.DualChannel
file you created:
Replace the line:
command=/usr/X11R6/bin/X