Version 1.4 of the X Resize, Rotate, and Reflect Extension (RandR 1.4 for short) adds a way for drivers to work together so that one graphics device can display images rendered by another. This can be used on Optimus-based laptops to display a desktop rendered by an NVIDIA GPU on a screen connected to another graphics device, such as an Intel integrated graphics device or a USB-to-VGA adapter.

System Requirements

Using the NVIDIA Driver as a RandR 1.4 Output Source Provider

To use the NVIDIA driver as an RandR 1.4 output source provider, the X server needs to be configured to use the NVIDIA driver for its primary screen and to use the “modesetting” driver for the other graphics device. If X.Org X server version 1.17.2 or higher is installed, this can be achieved by placing the following in /etc/X11/xorg.conf:

Section "Module"
    Load "modesetting"
EndSection

Section "Device"
    Identifier "nvidia"
    Driver "nvidia"
    BusID "<BusID for NVIDIA device here>"
    Option "AllowEmptyInitialConfiguration"
EndSection

See “What is the format of a PCI Bus ID?” for information on determining the appropriate BusID string for your graphics card.

Older X servers require a slightly more complicated configuration:

Section "ServerLayout"
    Identifier "layout"
    Screen 0 "nvidia"
    Inactive "intel"
EndSection

Section "Device"
    Identifier "nvidia"
    Driver "nvidia"
    BusID "<BusID for NVIDIA device here>"
EndSection

Section "Screen"
    Identifier "nvidia"
    Device "nvidia"
    Option "AllowEmptyInitialConfiguration"
EndSection

Section "Device"
    Identifier "intel"
    Driver "modesetting"
EndSection

Section "Screen"
    Identifier "intel"
    Device "intel"
EndSection

The X server does not automatically enable displays attached to the non-NVIDIA graphics device in this configuration. To do that, use the xrandr command line tool:

$ xrandr --setprovideroutputsource modesetting NVIDIA-0
$ xrandr --auto

This pair of commands can be added to your X session startup scripts, for example by putting them in $HOME/.xinitrc before running startx.

Use the

$ xrandr --listproviders

command to query the capabilities of the graphics devices. If the system requirements are met and the X server is configured correctly, there should be a provider named NVIDIA-0 with the Source Output capability and one named modesetting with the Sink Output capability. If either provider is missing or doesn't have the expected capability, check your system configuration.

Caveats