The SAMM display mode is to display continous content on two display devices. Different VIA chipset supports different display combinations.

Follow the steps below to configure SAMM display mode.

1. Create two separate Device sections and assign each a separate screen

In each Device section, specify the display devices you intend to use to be ActiveDevice, list the BusID of the graphics card to be shared and assign the related Screen. Other configuration according to different display devices is the same as we demonstrate in Part III Chapter 1, Display Devices Configuration Instructions. Note that, except the assigned Screen is different, the other content in the two Device section keeps the same.

Edit the BusID with the location of your graphics card. You could run the command below to get it.

# lspci | grep VGA

Here takes Internal DVI + Internal LCD for example.

Section "Device"
       Driver "via"
       VendorName  "VIA Tech"
       BoardName   "via"
       Identifier  "Device0"
       BusID       "PCI:1:0:0"
       Option "ActiveDevice" "DVI,LCD"
       Option "PanelSize" "1024x768"
       Screen 0
EndSection

Section "Device"
        Driver "via"
        VendorName  "VIA Tech"
        BoardName   "via"
        Identifier  "Device1"
        BusID       "PCI:1:0:0"
        Option "ActiveDevice" "DVI,LCD"
        Option "PanelSize" "1024x768"
        Screen	1
EndSection

2. Create two Screen sections

In Screen sections, specify the display mode and assign the related Device and Monitor.

Section "Screen"
       Identifier "Screen0"
       SubSection "Display"
              Modes  "1920x1200" 
              Depth  24
       EndSubSection
       DefaultDepth	24
       Monitor  "Monitor0"
       Device   "Device0"
EndSection

Section "Screen"
        Identifier "Screen1"
        SubSection "Display"
               Modes  "1024x768"
               Depth  24
        EndSubSection
        DefaultDepth   24
        Monitor  "Monitor1"
        Device   "Device1"
EndSection

3. Create two Monitor sections

Section "Monitor"
       Identifier "Monitor0"
       VendorName   "Monitor Vendor"
       ModelName    "Monitor Model"
EndSection

Section "Monitor"
        Identifier "Monitor1"
        VendorName   "Monitor Vendor"
        ModelName    "Monitor Model"
EndSection

4. Define the primary screen and display position in Section "ServerLayout"

Screen 0 is specified to be the primary screen. Thus Screen 1 is the secondary screen. Usually, the display position for the primary screen starts from the left top, and the position for the secondary screen could be on left/right of, or below/above the primary one. Legal operators are "rightof", "leftof", "below", "above".

Option "Xinerama" "on"

This option is to use Xinerama extension to enable the SAMM display mode. 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. For example,

Section "ServerLayout" 
       Option          "RandR" "False" 
       Identifier        "X.org Configured"  
       Screen   0    "Screen0" 0 0        
       Screen   1    "Screen1" rightof "Screen0"        
       Option          "Xinerama" "on" 
       InputDevice    "Mouse0" "CorePointer"     
       InputDevice    "Keyboard0" "CoreKeyboard" 
EndSection