You may encounter this error when you try to run Windows game with umu-launcher or wine, on 64bit Fedora.

libGL error: MESA-LOADER: failed to open iris: /usr/lib/pressure-vessel/overrides/lib/x86_64-linux-gnu/dri/iris_dri.so: wrong ELF class: ELFCLASS64 (search paths /usr/lib/pressure-vessel/overrides/lib/x86_64-linux-gnu/dri)
libGL error: failed to load driver: iris
libGL error: MESA-LOADER: failed to open swrast: /usr/lib/pressure-vessel/overrides/lib/x86_64-linux-gnu/dri/swrast_dri.so: wrong ELF class: ELFCLASS64 (search paths /usr/lib/pressure-vessel/overrides/lib/x86_64-linux-gnu/dri)
libGL error: failed to load driver: swrast
X Error of failed request:  GLXBadContext
  Major opcode of failed request:  150 (GLX)
  Minor opcode of failed request:  6 (X_GLXIsDirect)
  Serial number of failed request:  537
  Current serial number in output stream:  536

Solution

Solution is very simple. Just install 32bit library.

sudo dnf install mesa-libGL.i686

I use Linux for laptop. I installed WiVRn and OpenComposite¹ for VR gaming on Linux, as recommended by perillamint.

It works well for Linux native VR programs (e.g. xrgears) and Steam games.

However, it had a problem that non-Steam Windows games don't work.

First try

Steam games works well for VR. Steam uses Proton. Then, How about using Proton for non-Steam games?

umu-launcher

I tried umu-launcher, a program to run Proton for games not in Steam. (Actually, It uses Proton GE, not Proton by Valve. But, it doesn't matter in this post.)

Proton includes OpenXR/VR support. So I expected that it will work well if I set environment variables following SteamVR documentation of WinVR. But it didn't work.

PRESSURE_VESSEL_FILESYSTEMS_RW=/run/user/1000/wivrn/comp_ipc
XR_RUNTIME_JSON=/run/host/usr/share/openxr/1/openxr_wivrn.json

Why?

Reason

After some googling, I found that It needs Steam to be launched to use OpenVR/XR on Proton, and umu launcher doesn't launch Steam by default.

How can I resolve it with minimum efforts?

Solution: Then run Steam :D

Simple. Just run Steam.

Firstly, Let's check where the Proton is. Check debug log by running this command (Type /tmp/2q3ef32t part randomly. It doesn't matter)

UMU_LOG=debug umu-run /tmp/2q3ef32t

Then, you can see the location of proton from the console log. (e.g. /home/foo/.local/share/Steam/compatibilitytools.d/UMU-Proton-9.0-4e/proton) The below is example part of console log.

[umu.umu_run:887] DEBUG: (PosixPath('/home/foo/.local/share/umu/steamrt3/umu'), '--verb', 'waitforexitandrun', '--', PosixPath('/home/foo/.local/share/umu/steamrt3/umu-shim'), PosixPath('/home/foo/.local/share/Steam/compatibilitytools.d/UMU-Proton-9.0-4e/proton'), 'waitforexitandrun', './asdf')

Find this code from the proton file with editor

        # CoD: Black Ops 3 workaround
        if os.environ.get("SteamGameId", 0) in [
                    "311210",   # CoD: Black Ops 3
                    "1549250",  # Undecember
                ]:
            argv = [g_proton.wine_bin, "c:\\Program Files (x86)\\Steam\\steam.exe"]

Replace above code to below.

        if os.environ.get("UMU_RUN_STEAM", 0) == "1":
            argv = [g_proton.wine64_bin, "c:\\windows\\system32\\steam.exe"]
        # CoD: Black Ops 3 workaround
        elif os.environ.get("SteamGameId", 0) in [
                    "311210",   # CoD: Black Ops 3
                    "1549250",  # Undecember
                ]:
            argv = [g_proton.wine_bin, "c:\\Program Files (x86)\\Steam\\steam.exe"]

Finally, Run game UMU_RUN_STEAM environment variable and WiVRn-related environment variables. Check this script for details.

#!/bin/sh
export UMU_RUN_STEAM=1 
export PRESSURE_VESSEL_FILESYSTEMS_RW=/run/user/1000/wivrn/comp_ipc
export XR_RUNTIME_JSON=/run/host/usr/share/openxr/1/openxr_wivrn.json
export PRESSURE_VESSEL_IMPORT_OPENXR_1_RUNTIMES=1
umu-run ./Game.exe

Then It works.

Final words

It's not fundamental solution but simple solution. I wish it could help...

I tried to run games made with RPG Maker MV, but it stucks at loading.

Solution

I thought installing Windows on VM, but I found nwjs.dll file. The structure of package.json in the www directory of the game is also similar with the one of nwjs applications.

What if I just use nwjs binary for Linux? I tried it, and it actually worked.

1. Download Linux binaries from nwjs homepage (No need to use SDK versions)
2. Find a directory having package.json (Usually www directory)
3. Run the nwjs binary, downloading in the Step 1, with the directory found in the Step 2 as parameter. (e.g. ~/nwjs-binary/nwjs ~/game/www)
4. If it didn't work, the package.json file might have empty name. Update the name property of package.json file to arbitary random value.

If you follow this guide, it should work. It might not work for some games, but... it works for me.