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, version 3.13 or higher, with CONFIG_DRM enabled.
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 nvidia-xconfig(1) utility can be used to update the X configuration file.
$ nvidia-xconfig --prime
See the nvidia-xconfig(1) man page for details.
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.
When running against X.Org X server with video driver ABI 23 or higher, synchronization is supported with compatible drivers. At the time of writing, synchronization is compatible with the “modesetting” driver with Intel devices on Linux version 4.5 or newer. If all requirements are met, synchronization will be used automatically.
X.Org X server version 1.19 or newer is required to support synchronization. Without synchronization, displays are prone to “tearing”. See Caveats for details.
If synchronization is being used but is not desired, it can be disabled with:
$ xrandr --output <output> --set "PRIME Synchronization" 0
and re-enabled with:
$ xrandr --output <output> --set "PRIME Synchronization" 1
See Vblank syncing for information on how OpenGL applications can synchronize with sink-provided outputs.
Support for PRIME Synchronization relies on DRM KMS support. See Chapter 35, Direct Rendering Manager Kernel Modesetting (DRM KMS) for more information.
Some Intel i915 DRM driver versions, such as that included with
Linux 4.5, have a bug where drmModeMoveCursor() and
drmModePageFlip() interfere with each other, resulting in only one
occurring per frame. If choppy performance is observed in
configurations using PRIME Synchronization and i915, it is
suggested to add Option
"SWCursor" to Intel's device section in xorg.conf. The bug
appears to be fixed as of Linux 4.6.
When running against X.Org X server version 1.18.x or lower, 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 expected due to limitations in the design of the X.Org X server prior to video driver ABI 23.
The NVIDIA driver currently only supports the Source Output capability. It cannot be used
as an output sink.
NVIDIA's implementation of PRIME requires support for DRM render
nodes, a feature first merged in Linux 3.12. However, the feature
was not enabled by default until Linux 3.17. To enable it on
earlier supported kernels, specify the drm.rnodes=1 kernel boot parameter.