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.
X.Org X server version 1.13 or higher.
A Linux kernel with CONFIG_DRM enabled and the appropriate driver interfaces present:
drm_gem_prime_export
drm_gem_prime_import
gem_prime_pin
gem_prime_get_sg_table
gem_prime_import_sg_table
gem_prime_vmap
gem_prime_vunmap
Version 1.4.0 of the xrandr command-line utility.
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. This can be achieved by placing the following in
/etc/X11/xorg.conf:
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
See “What is the format of a PCI Bus ID?” for information on determining the appropriate BusID string for your graphics card.
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.
There is no synchronization between the images rendered by the NVIDIA GPU and the output device. This means that the output device can start reading the next frame of video while it is still being updated, producing a graphical artifact known as “tearing”. Tearing is currently expected due to limitations in the design of the X.Org X server.
The NVIDIA driver currently only supports the Source Output capability. It does not
support render offload and cannot be used as an output sink.