Hardware #

NVIDIA WIRED VR ISSUES: Nvidia proprietary drivers currently have a number of critical issues with DRM lease causing substantial presentation latency for wired VR headsets, or making DRM lease impossible, resulting in discomfort or breakage. Wireless VR through WiVRn is entirely unaffected only direct display type wired headsets. Users with Nvidia GPUs should consider the Nvidia Wired VR Workaround footnotes of the GPU table below or switch to AMD for the best experience. For details and to report your experience, see this forum thread and this issue as well.

GPU support matrix #

Notes:

• Nvidia Wired VR Workaround: Wired users should certainly set XRT_COMPOSITOR_USE_PRESENT_WAIT to 1 which changes the swapchain to explicit sync behavior and U_PACING_COMP_TIME_FRACTION_PERCENT to 90, representing 90% of the time it takes to render a frame can significantly reduce the latency effect with Nvidia GPUs. There are notable frametime issues in the driver still which may result in stutter but this should vastly improve the experience.
• For Nvidia proprietary drivers older than 565, (please try to update!), the vulkan-layers must be installed in order to not crash: AUR・Fedora
• Audio over DisplayPort is known to temporarily cut out whenever new audio sources spring up on PipeWire without a fix to add ALSA headroom.
  • This fix’s default values adds a lot of audio latency to the entire system. If you’re someone who is sensitive to audio latency, you can try changing period-size=64 and headroom=512. If audio continues to cut off, double these values.
  • Also, this fix will change the latency of all audio output devices. To tweak the audio output latency of your HMD only, which is usually sufficient to prevent cutouts, use pactl list sinks to identify the Sink Name that your HMD is currently connected to, and edit the headroom fix file by changing the node.name.
  • For example: node.name = "alsa_output.pci-0000_03_00.1.hdmi-stereo-extra2" (not a typo, it’s still connected via DisplayPort)

XR Devices #

A non-comprehensive table of various VR/XR devices and the drivers that support them. Note that wired headset experiences with Nvidia GPUs will be affected by the DRM lease presentation latency issue.

Hardware note #

• Nvidia GPU users: Due to the DRM lease presentation latency issue, wired VR headsets will experience a delayed viewport effect on Nvidia GPUs. This affects all driver versions since 550. Consider these workarounds:
  • Use WiVRn or ALVR with standalone headsets for wireless VR (recommended)
  • Try setting U_PACING_COMP_MIN_TIME_MS=10 as an environment variable to slightly reduce the effect
  • Consider switching to AMD GPUs for the best wired VR experience
  • Monitor the bug report thread for updates
• AMD GPU users: If using WiVRn, make sure you are using the RADV Vulkan driver. A green and broken video stream in WiVRn is a telltale sign that you’re using the incompatible AMDVLK driver. Remove AMDVLK and install RADV as AMDVLK is known to be difficult to opt out of as a driver when installed on system.
• WiVRn PC XR to WiVRn PC client streaming remains mainly for debug use.
• Vive Pro microphones should be set to use 44.1khz sample rates as feeding in 48khz raises the pitch of the audio.
• Vive Pro creates HDMI Output Source after startup of SteamVR/Monado/etc. Use it instead of Vive Pro USB Audio Source, since the audio might appear distorted.
• Valve Index audio output should be set to 48khz or no audio will output.
• Valve Index first presentation to system each fresh boot or first runtime plug in will yield no display, resulting in VR refusing to start. Replug the barrel connector that provides power to the HMD to reset it to make it available.
• Valve Index may also exhibit unexpected activity with its microphone. If the microphone doesn’t transmit at all during regular VR use, consider changing the DisplayPort slot the headset is currently plugged into. Also, as a reminder, the Index mic only works if the headset is actively being used to display something.
• Vive Pro Eye HMD functional, eye tracking functionality with ReVision
• Pimax initialization code WIP. Distortion matrix dump work in progress.
• Eyetrack VR and Project Babble will both be implemented through oscavmgr to emit proper unified flexes over OSC.
• Tracking technologies can be mixed Monado/WiVRn by using motoc.

Applying a kernel patch (for Vive Pro 2, Bigscreen Beyond, Pimax) #

Arch #

1. download the patch(es), then follow the steps on https://wiki.archlinux.org/title/Kernel/Arch_build_system, which should be roughly: mkdir ~/build/ -> cd ~/build/ -> pkgctl repo clone --protocol=https linux -> cd linux
2. (section 2 of link) open PKGBUILD in that directory and modify the pkgbase line (at the top) to read e.g. “pkgbase=linux-customvr”. then add a line containing “<patchfilename>.patch” to the source array:

source=(
  https://cdn.kernel.org/pub/linux/kernel/v${pkgver%%.*}.x/${_srcname}.tar.{xz,sign}
  <patchfilename>.patch
  $url/releases/download/$_srctag/linux-$_srctag.patch.zst{,.sig}
  config  # the main kernel config file
)

4. close PKGBUILD. (may not be necessary but i ran updpkgsums) -> makepkg -s --skippgpcheck (i didn’t feel like fixing a pgp error)
5. then section 4 of https://wiki.archlinux.org/title/Kernel/Arch_build_system#Installing and restart

Fedora #

1. Prepare the kernel

git clone https://src.fedoraproject.org/rpms/kernel.git
cd kernel

# replace 41 with your fedora version
git switch f41

# install the build dependencies for the kernel, if you haven't already
sudo dnf builddep kernel.spec

# name this the 'bsb' build
sed -i 's/# define buildid .*/%define buildid .bsb/g' kernel.spec

2. Replace linux-kernel-test.patch with the actual patch file downloaded from the table above

3. Build RPMs:

fedpkg local

4. Install kernel:

sudo dnf install --nogpgcheck ./x86_64/kernel-*.rpm

5. Reboot and check that using uname -a that the bsb kernel is running.

Official guide: Building a Kernel from the Fedora dist-git

NixOS #

1. download the patch(es)
2. add this to your configuration.nix or other nix file you use:

  boot.kernelPatches = [
    {
      name = "type what the patch is for here";
      patch = /path/to/patch/file.patch;
    }
  ];

reference commit on my nix files: https://github.com/TayouVR/nixfiles/commit/d6ef568a2642c5a26eb92611be7335afdb6047de