Controller input not working with gamescope on Gentoo: pressure-vessel missing /run/host bind mount

Your system information

• System information from steam:
  Computer Information:
  Manufacturer: ASRock
  Model: B850M Steel Legend WiFi
  Form Factor: Desktop
  No Touch Input Detected
  Processor Information:
  CPU Vendor: AuthenticAMD
  CPU Brand: AMD Ryzen 7 9800X3D 8-Core Processor
  CPU Family: 0x1a
  CPU Model: 0x44
  CPU Stepping: 0x0
  CPU Type: 0x0
  Speed: 5455 MHz
  16 logical processors
  8 physical processors
  Hyper-threading: Supported
  FCMOV: Supported
  SSE2: Supported
  SSE3: Supported
  SSSE3: Supported
  SSE4a: Supported
  SSE41: Supported
  SSE42: Supported
  AES: Supported
  AVX: Supported
  AVX2: Supported
  AVX512F: Supported
  AVX512PF: Unsupported
  AVX512ER: Unsupported
  AVX512CD: Supported
  AVX512VNNI: Supported
  SHA: Supported
  CMPXCHG16B: Supported
  LAHF/SAHF: Supported
  PrefetchW: Unsupported
  BMI1: Supported
  BMI2: Supported
  F16C: Supported
  FMA: Supported
  Operating System Version:
  "Gentoo Linux" (64 bit)
  Kernel Name: Linux
  Kernel Version: 6.17.0-cachyos
  X Server Vendor: The X.Org Foundation
  X Server Release: 12401008
  X Window Manager: Hyprland :D
  Steam Runtime Version: steam-runtime_1.0.20250616.139563
  Client Information:
  Version: 1757650573
  Browser GPU Acceleration Status: Enabled
  Browser Canvas: Enabled
  Browser Canvas out-of-process rasterization: Enabled
  Browser Direct Rendering Display Compositor: Disabled
  Browser Compositing: Enabled
  Browser Multiple Raster Threads: Enabled
  Browser OpenGL: Enabled
  Browser Rasterization: Enabled
  Browser Raw Draw: Disabled
  Browser Skia Graphite: Disabled
  Browser Video Decode: Enabled
  Browser Video Encode: Disabled
  Browser Vulkan: Disabled
  Browser WebGL: Enabled
  Browser WebGL2: Enabled
  Browser WebGPU: Disabled
  Browser WebNN: Disabled
  Video Card:
  Driver: NVIDIA Corporation NVIDIA GeForce RTX 5070 Ti/PCIe/SSE2
  Driver Version: 4.6.0 NVIDIA 580.95.05
  Desktop Color Depth: 24 bits per pixel
  Monitor Refresh Rate: 164 Hz
  VendorID: 0x1002
  DeviceID: 0x13c0
  Revision Not Detected
  Number of Monitors: 2
  Number of Logical Video Cards: 2
  Primary Display Resolution: 2560 x 1440
  Desktop Resolution: 5120 x 1440
  Primary Display Size: 23.62" x 13.39" (27.13" diag), 60.0cm x 34.0cm (68.9cm diag)
  Primary VRAM: 16303 MB
  Sound card:
  Audio device: Nvidia GPU ab HDMI/DP
  Memory:
  RAM: 31166 Mb
  VR Hardware:
  VR Headset: None detected
  Miscellaneous:
  UI Language: English
  LANG: en_US.utf8
  Total Hard Disk Space Available: 936002 MB
  Largest Free Hard Disk Block: 31794 MB
  Storage:
  Number of SSDs: 5
  SSD sizes: 2000G,1000G,500G,500G,0B
  Number of HDDs: 0
  Number of removable drives: 0
• Have you checked for system updates?: Yes
• Distribution: Gentoo Linux
• Kernel version: 6.17.0-cachyos
• Graphics driver version: Nvidia (open) 580.95.05
• Gamescope version: 3.16.2 (any newer breaks --force-grab-cursor on Hyprland, unrelated to this issue)

Please describe your issue in as much detail as possible:

Controller input does not work in games when launching through gamescope on Gentoo Linux with Steam Input enabled. The controller works correctly:

• Without gamescope
• With gamescope when Steam Input is disabled

Steps for reproducing this issue:

1. Install Gentoo Linux with standard multilib layout (/usr/lib for 32-bit, /usr/lib64 for 64-bit)
2. Install Steam, gamescope, and dev-libs/libei (which provides libextest.so)
3. Enable Steam Input for a controller (tested with 8BitDo Ultimate 2)
4. Launch any game with gamescope using a launch option like: gamescope -- %command%
5. Controller input does not work in the game

Technical Details

The root cause is that pressure-vessel attempts to preload --ld-preload=/run/host/usr/lib/libextest.so, but the /run/host directory is never created as a bind mount inside the container on Gentoo systems.

Evidence from logs (~/.local/share/Steam/logs/console-linux.txt):

ERROR: ld.so: object '/run/host/usr/lib/libextest.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.
ERROR: ld.so: object '/usr/lib/libextest.so' from LD_PRELOAD cannot be preloaded (wrong ELF class: ELFCLASS32): ignored.

The "wrong ELF class" errors occur because 64-bit processes are attempting to load the 32-bit /usr/lib/libextest.so when they should be loading /usr/lib64/libextest.so.

Observations:

• libextest.so exists at both /usr/lib/libextest.so (32-bit ELF) and /usr/lib64/libextest.so (64-bit ELF)
• Inside the pressure-vessel container (verified via /proc/[PID]/root/):
  • /usr/lib/libextest.so is visible and accessible
  • /run/host directory does not exist at all
• When launching without gamescope, pressure-vessel correctly preloads both gameoverlayrenderer.so and libextest.so
• When launching with gamescope, only libextest.so is attempted for preload, and gameoverlayrenderer.so is missing entirely

Comparison with Arch Linux:
This issue does not occur on Arch Linux with identical versions of gamescope and Hyprland, suggesting this is specific to how pressure-vessel handles Gentoo's multilib filesystem layout.

Comparison: With vs Without Gamescope

Without gamescope (controller works):

--ld-preload=/run/host/usr/lib/libextest.so
--ld-preload=/home/user/.local/share/Steam/ubuntu12_32/gameoverlayrenderer.so
--ld-preload=/home/user/.local/share/Steam/ubuntu12_64/gameoverlayrenderer.so

With gamescope (controller doesn't work):

--ld-preload=/run/host/usr/lib/libextest.so
(No gameoverlayrenderer.so preloaded, and /run/host path doesn't exist)

Proposed Solution

Either:

1. Pressure-vessel should create proper /run/host/usr/{lib,lib64} bind mounts on Gentoo's multilib layout
2. When the bind mount doesn't exist, fall back to using direct paths (/usr/lib/libextest.so, /usr/lib64/libextest.so)
3. Ensure gameoverlayrenderer.so is still preloaded when gamescope is in the launch chain

Workaround

Disable Steam Input for games launched with gamescope. The controller works correctly using raw input.

Start with the pressure-vessel launch and preload behavior described in the issue, then inspect the console-linux.txt comparison for launches with and without gamescope. Reproduce the missing /run/host bind mount and the ELF-class errors on Gentoo's /usr/lib and /usr/lib64 layout. Done means controller input works with Steam Input through gamescope and the required preload libraries resolve correctly.