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# Nvidia-xrun

From ArchWiki

Nvidia-xrun is a utility to allow Nvidia optimus enabled laptops run X server with discrete nvidia graphics on demand. This solution offers full GPU utilization, compatibility and better performance than Bumblebee.

X server can only be used with integrated graphics or discrete Nvidia graphics, but not both, so user might want to switch to separate virtual console and start another X server using different graphics from what was used for the first X server.

## Installation

Install:

- nvidia - if using nvidia-390xx - you have to edit nvidia-xrun*'s PKGBUILD and remove the nvidia depend
- nvidia-xrun-gitAUR(recommended) or nvidia-xrunAUR (old method, uses bumblebee to switch off the dGPU)
- Any Window manager, since running application directly like so `nvidia-xrun <application>` is not recommended.

## Configuration

### Setting the right bus id

Note: If you installed package from AUR, the bus id has been automatically set in `/etc/X11/nvidia-xorg.conf`. Make sure the bus ID has been correctly set, otherwise change it (you can find correct bus ID using `lspci` command). In some cases you need to convert the hex output from `lspci` to decimal for nvidia-xorg.conf, e.g. 3b:00.0 becomes "PCI:59:0:0"

Find your display device bus id:

     $ lspci | grep -i nvidia | awk '{print $1}'

It might return something similar to `01:00.0`. Then create a file (for example `/etc/X11/nvidia-xorg.conf.d/30-nvidia.conf`) to set the proper bus id:

    /etc/X11/nvidia-xorg.conf.d/30-nvidia.conf

    Section "Device"
        Identifier "nvidia"
        Driver "nvidia"
        BusID "PCI:1:0:0"
        #  Option "DPI" "96 x 96"
    EndSection

Also this way you can adjust some nvidia settings if you encounter issues:

    /etc/X11/nvidia-xorg.conf.d/30-nvidia.conf

    Section "Screen"
        Identifier "nvidia"
        Device "nvidia"
        #  Option "AllowEmptyInitialConfiguration" "Yes"
        #  Option "UseDisplayDevice" "none"
    EndSection

### eGPU setup

You can also use this in an eGPU setup. Make sure to load the nvidia-modeset and nvidia-drm modules and add the option `Option "AllowExternalGpus" "true"` to the "Device" section.

Change the auto-generated configuration to use the internal display on devices with multiple NVIDIA cards:

    /etc/X11/nvidia-xorg.conf.d/30-nvidia.conf

    Section "ServerLayout"
      Identifier "layout"
      Screen 0 "nvidia" 0 0
      Inactive "intel"
      Option  "AutoAddGPU" "false"
    EndSection

    Section "Device"
      Identifier "nvidia"
      Driver "nvidia"
      BusID "PCI:9:0:0"
      Option "AllowExternalGpus" "true"
      Option "ProbeAllGpus" "false"
      Option "HardDPMS" "false"
      Option "NoLogo" "true"
      Option "UseEDID" "false"
    #    Option "UseDisplayDevice" "none"
    EndSection

    Section "Screen"
      Identifier "nvidia"
      Device "nvidia"
      Option "AllowEmptyInitialConfiguration" "Yes"
    #  Option "UseDisplayDevice" "None"
    EndSection

Remember to set the bus id to the correct graphics card.

### Automatically run window manager

For convenience you can create an `$XDG_CONFIG_HOME/X11/nvidia-xinitrc` file with your favourite window manager. (if using nvidia-xrun < v.0.3.79 create `$HOME/.nvidia-xinitrc`)

    if [ $# -gt 0 ]; then
      $*
    else
      openbox-session
      # Alternatively, you can also use xfce4 or bspwm:
      # xfce4-session
      # bspwm
    fi

With it you do not need to specify the app and can simply execute:

    $ nvidia-xrun

Since this method starts an isolated X server, it is also a good idea to get a copy of all the other configurations files that you have located at `/etc/X11/xorg.conf.d/`, except for your prior standard iGPU configurations.

### Use bbswitch to manage nvidia

Note: nvidia-xrun > 0.3.78 should disable the card automatically so this method is unneccessary

When the nvidia card is not needed, bbswitch can be used to turn it off. The nvidia-xrun script will automatically take care of running a window manager and waking up the nvidia card. To achieve that, you need to:

- Load the `bbswitch` module on boot

    # echo 'bbswitch' > /etc/modules-load.d/bbswitch.conf

- Disable the `nvidia` module on boot:

    # echo 'options bbswitch load_state=0 unload_state=1' > /etc/modprobe.d/bbswitch.conf

After a reboot, the nvidia card will be off. This can be seen by querying `bbswitch`'s status:

    $ cat /proc/acpi/bbswitch

To force the card to turn on/off respectively run:

    # tee /proc/acpi/bbswitch <<<OFF
    # tee /proc/acpi/bbswitch <<<ON

For more about bbswitch see Bumblebee-Project/bbswitch.

## Usage

### Start at boot

Enable `nvidia-xrun-pm.service` - this shuts down the nvidia card during boot.

Once the system boots, from the virtual console, login to your user, and run `nvidia-xrun application`.

If above does not work, switch to unused virtual console and try again.

As mentioned before, running apps directly with `nvidia-xrun application` does not work well, so it is best to create an `nvidia-xinitrc` file as outlined earlier, and use `nvidia-xrun` to launch your window manager.

## Troubleshooting

### NVIDIA GPU fails to switch off or is set to be default

See #Use bbswitch to manage nvidia.

If Nvidia GPU still fails to switch off, or is somehow set to be default whenever you use or not `nvidia-xrun`, then you might likely need to blacklist specific modules (which were previously blacklisted by Bumblebee). Create this file and restart your system:

    /usr/lib/modprobe.d/nvidia-xrun.conf

    blacklist nvidia
    blacklist nvidia-drm
    blacklist nvidia-modeset
    blacklist nvidia-uvm
    blacklist nouveau

There seems to be a race condition between `nvidia-xrun-pm.service` and `systemd-moudules-load.service` which loads the nvidia modules. If the latter runs first, `nvidia-xrun-pm` will hang (actually the `tee` command) during device removal. If on the other hand `nvidia-xrun-pm` runs first then it will succeed, and later the modules will fail to load with an error (which is harmless but ugly). For this reason it might be better to always blacklist the above modules.

DRM kernel mode setting should be enabled for PRIME synchronisation to work (for example on muxless devices where only the Intel GPU is connected to outputs). However, consider disabling it in case there is an issue. See NVIDIA#DRM kernel mode setting

Category:

- Graphics