PRIME
PRIME is a technology used to manage hybrid graphics found on recent desktops and laptops (Optimus for NVIDIA, AMD Dynamic Switchable Graphics for Radeon). PRIME GPU offloading and Reverse PRIME are an attempt to support muxless hybrid graphics in the Linux kernel.
Installation
Open-source drivers
Remove any closed-source graphic drivers and replace them with the open source equivalent:
Reboot and check the list of attached graphic drivers:
$ xrandr --listproviders
Providers: number : 2 Provider 0: id: 0x7d cap: 0xb, Source Output, Sink Output, Sink Offload crtcs: 3 outputs: 4 associated providers: 1 name:Intel Provider 1: id: 0x56 cap: 0xf, Source Output, Sink Output, Source Offload, Sink Offload crtcs: 6 outputs: 1 associated providers: 1 name:radeon
We can see that there are two graphic cards: Intel, the integrated card (id 0x7d), and Radeon, the discrete card (id 0x56), which should be used for GPU-intensive applications.
By default the Intel card is always used:
$ glxinfo | grep "OpenGL renderer"
OpenGL renderer string: Mesa DRI Intel(R) Ivybridge Mobile
"HAINAN @ pci:0000:03:00.0", not radeon. In this case you should use "HAINAN @ pci:0000:03:00.0" as the provider in the next command.Closed-source drivers
To get PRIME functioning on the proprietary drivers, it is pretty much the same process. Follow the following articles to install the drivers:
- AMDGPU PRO to install drivers for AMD GPUs.
- NVIDIA to install drivers for NVIDIA GPUs.
After you have the driver installed, do not reboot or relaunch Xorg. Depending on your system configuration, this may render your Xorg system unusable until reconfigured.
Follow the instructions for the section on your designated use-case. You do not need to uninstall the open-source drivers for it to function, but you probably should, for the sake of preventing clutter and potential future issues.
PRIME GPU offloading
We want to render applications on the more powerful card and send the result to the card which has display connected.
The command xrandr --setprovideroffloadsink provider sink can be used to make a render offload provider send its output to the sink provider (the provider which has a display connected). The provider and sink identifiers can be numeric (0x7d, 0x56) or a case-sensitive name (Intel, radeon).
- This setting is no longer necessary when using the default intel/modesetting driver from the official repos, as they have DRI3 enabled by default and will therefore automatically make these assignments. Explicitly setting them again does no harm, though.
- GPU offloading is not supported by the closed-source drivers (for the NVIDIA driver this is no longer the case, for more info see #PRIME render offload below).
Example:
$ xrandr --setprovideroffloadsink radeon Intel
You may also use provider index instead of provider name:
$ xrandr --setprovideroffloadsink 1 0
For open source drivers - PRIME
To use your discrete card for the applications who need it the most (for example games, 3D modellers...), prepend the DRI_PRIME=1 environment variable:
$ DRI_PRIME=1 glxinfo | grep "OpenGL renderer"
OpenGL renderer string: Gallium 0.4 on AMD TURKS
Other applications will still use the less power-hungry integrated card. These settings are lost once the X server restarts, you may want to make a script and auto-run it at the startup of your desktop environment (alternatively, put it in /etc/X11/xinit/xinitrc.d/). This may reduce your battery life and increase heat though.
See Gentoo:AMDGPU#Test, if a discrete graphics card is in use for more information.
PRIME render offload
NVIDIA driver since version 435.17 supports this method. xf86-video-modesetting, xf86-video-amdgpu (450.57), and xf86-video-intel (455.38) are officially supported as iGPU drivers.
To run a program on the NVIDIA card you can use the prime-run script provided by nvidia-prime:
$ prime-run glxinfo | grep "OpenGL renderer" $ prime-run vulkaninfo
PCI-Express Runtime D3 (RTD3) Power Management
For Turing generation cards with Intel Coffee Lake or above CPUs (as well as the Ryzen 5800H Acer Nitro 5), it is possible to fully power down the GPU when not in use.
The following udev rules are needed -
/etc/udev/rules.d/80-nvidia-pm.rules
# Enable runtime PM for NVIDIA VGA/3D controller devices on driver bind
ACTION=="bind", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030000", TEST=="power/control", ATTR{power/control}="auto"
ACTION=="bind", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030200", TEST=="power/control", ATTR{power/control}="auto"
# Disable runtime PM for NVIDIA VGA/3D controller devices on driver unbind
ACTION=="unbind", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030000", TEST=="power/control", ATTR{power/control}="on"
ACTION=="unbind", SUBSYSTEM=="pci", ATTR{vendor}=="0x10de", ATTR{class}=="0x030200", TEST=="power/control", ATTR{power/control}="on"
together with the following module parameters -
/etc/modprobe.d/nvidia-pm.conf
options nvidia "NVreg_DynamicPowerManagement=0x02"
We also need to enable the nvidia-persistenced service to not make the kernel tear down the device state whenever the NVIDIA device resources are no longer in use. [1]
Configure applications to render using GPU
Even without enabling Dynamic Power Management, offload rendering of applications is required [2]
To run an application offloaded to the NVIDIA GPU with Dynamic Power Management enabled, add the following environment variables: [3]
__NV_PRIME_RENDER_OFFLOAD=1 __GLX_VENDOR_LIBRARY_NAME=nvidia command
When using on a Steam game, the launcher command line can be set to:
__NV_PRIME_RENDER_OFFLOAD=1 __GLX_VENDOR_LIBRARY_NAME=nvidia %command%
Troubleshooting
If you have bumblebee installed, you should remove it because it blacklists the nvidia_drm driver which is required to load the nvidia driver by X server for offloading.
PRIME synchronization
When using PRIME, the primary GPU renders the screen content / applications, and passes it to the secondary GPU for display. Quoting an NVIDIA thread, "Traditional vsync can synchronize the rendering of the application with the copy into system memory, but there needs to be an additional mechanism to synchronize the copy into system memory with the iGPU’s display engine. Such a mechanism would have to involve communication between the dGPU’s and the iGPU’s drivers, unlike traditional vsync."
This synchronization is achieved using PRIME sync. To check if PRIME synchronization is enabled for your display, check the output of xrandr --prop.
To enable it run:
$ xrandr --output <output-name> --set "PRIME Synchronization" 1
Reverse PRIME
- Reverse PRIME is not supported for AMDGPU + NVIDIA on NVIDIA driver prior to 470 beta. See [4] for more details. An alternative for older versions is to use NVIDIA as the primary card as described in #Discrete card as primary GPU.
- Currently when only external display is enabled, you will only get 1 FPS. See [5] for more details.
If the second GPU has outputs that are not accessible by the primary GPU, you can use Reverse PRIME to make use of them. This will involve using the primary GPU to render the images, and then pass them off to the second GPU.
It may work out of the box, however if not, please go through the following steps.
Configuration
First, identify integrated GPU BusID
lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation UHD Graphics 630 (Mobile) 01:00.0 VGA compatible controller: NVIDIA Corporation TU117M [GeForce GTX 1650 Mobile / Max-Q] (rev a1)
In the above example Intel card has 00:02.0 which translates to PCI:0:2:0.
Set up your xorg.conf as follows and adjust BusID.
/etc/X11/xorg.conf
Section "ServerLayout"
Identifier "layout"
Screen 0 "intel"
Inactive "nvidia"
Option "AllowNVIDIAGPUScreens"
EndSection
Section "Device"
Identifier "nvidia"
Driver "nvidia"
EndSection
Section "Screen"
Identifier "nvidia"
Device "nvidia"
EndSection
Section "Device"
Identifier "intel"
Driver "modesetting"
BusID "PCI:0:2:0"
EndSection
Section "Screen"
Identifier "intel"
Device "intel"
EndSection
The command xrandr --setprovideroutputsource provider source sets the provider as output for the source. For example:
$ xrandr --setprovideroutputsource radeon Intel
When this is done, the discrete card's outputs should be available in xrandr, and you could do something like:
$ xrandr --output HDMI-1 --auto --above LVDS1
to configure both internal as well as external displays.
Problems
If after reboot you only have one provider, it might be because when Xorg starts, the nvidia module is not loaded yet. You need to enable early module loading. See Kernel mode setting#Early KMS start for details.
User scenarios
Discrete card as primary GPU
Imagine following scenario: The LVDS1 (internal laptop screen) and VGA outputs are both only accessible through the integrated Intel GPU. The HDMI and Display Port outputs are attached to the discrete NVIDIA card. It is possible to use all four outputs by making use of the #Reverse PRIME technology as described above. However the performance might be slow, because all the rendering for all outputs is done by the integrated Intel card. To improve this situation it is possible to do the rendering by the discrete NVIDIA card, which then copies the framebuffers for the LVDS1 and VGA outputs to the Intel card.
Create the following Xorg configuration:
/etc/X11/xorg.conf.d/10-gpu.conf
Section "ServerLayout"
Identifier "layout"
Screen 0 "nouveau"
Inactive "intel"
EndSection
Section "Device"
Identifier "nouveau"
Driver "nouveau"
BusID "PCI:x:x:x" # Sample: "PCI:1:0:0"
EndSection
Section "Screen"
Identifier "nouveau"
Device "nouveau"
EndSection
Section "Device"
Identifier "intel"
Driver "intel"
BusID "PCI:x:x:x" # Sample: "PCI:0:2:0"
EndSection
Section "Screen"
Identifier "intel"
Device "intel"
EndSection
Restart Xorg. The discrete NVIDIA card should be used now. The HDMI and Display Port outputs are the main outputs. The LVDS1 and VGA outputs are off. To enable them run:
$ xrandr --setprovideroutputsource Intel nouveau
The internal card's outputs should be available now in xrandr.
Troubleshooting
XRandR specifies only 1 output provider
Delete/move /etc/X11/xorg.conf file and any other files relating to GPUs in /etc/X11/xorg.conf.d/. Restart the X server after this change.
If the video driver is blacklisted in /etc/modprobe.d/ or /usr/lib/modprobe.d/, load the module and restart X. This may be the case if you use the bbswitch module for Nvidia GPUs.
Another possible problem is that Xorg might try to automatically assign monitors to your second GPU. Check the logs:
$ grep "No modes" ~/.local/share/xorg/Xorg.0.log
AMDGPU(0): No modes.
To solve this add the ServerLayout section with inactive device to your xorg.conf:
/etc/X11/xorg.conf
Section "ServerLayout" Identifier "X.org Configured" Screen 0 "Screen0" 0 0 # Screen for your primary GPU Inactive "Card1" # Device for your second GPU EndSection
When an application is rendered with the discrete card, it only renders a black screen
In some cases PRIME needs a composition manager to properly work. If your window manager doesn’t do compositing, you can use xcompmgr on top of it.
If you use Xfce, you can go to Menu > Settings > Window Manager Tweaks > Compositor and enable compositing, then try again your application.
Black screen with GL-based compositors
Currently there are issues with GL-based compositors and PRIME offloading. While Xrender-based compositors (xcompmgr, xfwm, compton's default backend, cairo-compmgr, and a few others) will work without issue, GL-based compositors (Mutter/muffin, Compiz, compton with GLX backend, Kwin's OpenGL backend, etc) will initially show a black screen, as if there was no compositor running. While you can force an image to appear by resizing the offloaded window, this is not a practical solution as it will not work for things such as full screen Wine applications. This means that desktop environments such as GNOME3 and Cinnamon have issues with using PRIME offloading.
Additionally if you are using an Intel IGP you might be able to fix the GL Compositing issue by running the IGP as UXA instead of SNA, however this may cause issues with the offloading process (ie, xrandr --listproviders may not list the discrete GPU).
For details see FDO Bug #69101.
One other way to approach this issue is by enabling DRI3 in the Intel driver. See the below issue for a sample configuration.
GNOME
You may find that disabling fullscreen undirect allows PRIME offloading to work correctly for full-screen applications.
Kernel crash/oops when using PRIME and switching windows/workspaces
Using DRI3 WITH a config file for the integrated card seems to fix this issue.
To enable DRI3, you need to create a config for the integrated card adding the DRI3 option:
Section "Device"
Identifier "Intel Graphics"
Driver "intel"
Option "DRI" "3"
EndSection
After this you can use DRI_PRIME=1 WITHOUT having to run xrandr --setprovideroffloadsink radeon Intel as DRI3 will take care of the offloading.
Glitches/Ghosting synchronization problem on second monitor when using reverse PRIME
This problem can affect users when not using a composite manager, such as with i3. [7]
If you experience this problem under Gnome, then a possible fix is to set some environment variables in /etc/environment [8]
CLUTTER_PAINT=disable-clipped-redraws:disable-culling CLUTTER_VBLANK=True
Error "radeon: Failed to allocate virtual address for buffer:" when launching GL application
This error is given when the power management in the kernel driver is running.
You can overcome this error by appending radeon.runpm=0 to the kernel parameters in the bootloader.
Constant hangs/freezes with Vulkan applications/games using VSync with closed-source drivers and reverse PRIME
Some Vulkan applications (particularly ones using VK_PRESENT_MODE_FIFO_KHR and/or VK_PRESENT_MODE_FIFO_RELAXED_KHR, including Windows games ran with DXVK) will cause the GPU to lockup constantly (~5-10 seconds freezed, ~1 second working fine)[9] when ran on a system using reverse PRIME.
A GPU lockup will render any input unusable (this includes switching TTYs and using SysRq functions).
There is no known fix for this NVIDIA bug, but a few workarounds exist:
- Turning Vsync off (not possible for some applications)
- Turning PRIME Synchronization[10] off (will introduce screen tearing):
xrandr --output HDMI-0 --set "PRIME Synchronization" 0 #replace HDMI-0 with your xrandr output ID
You can verify if your configuration is affected by the issue simply by running vkcube from the vulkan-tools package.