From a253ff15cd5e14fc8317d6d35d9ba2dbb6b5d309 Mon Sep 17 00:00:00 2001 From: Rick Peters Date: Thu, 1 Oct 2026 18:02:17 +0200 Subject: [PATCH] nvidia: results of the hardware test on the RTX 5080 PC --- nvidia/HARDWARE-RESULTS.md | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) create mode 100644 nvidia/HARDWARE-RESULTS.md diff --git a/nvidia/HARDWARE-RESULTS.md b/nvidia/HARDWARE-RESULTS.md new file mode 100644 index 0000000..29cb345 --- /dev/null +++ b/nvidia/HARDWARE-RESULTS.md @@ -0,0 +1,38 @@ +# NVIDIA fix: results on the RTX 5080 PC (2026-10-01) + +PC: RTX 5080 (GB203, 10de:2c02) + AMD Granite Ridge iGPU, MSI MAG 341C OLED on the NVIDIA DP-1 (3440x1440, 175 Hz), +CachyOS, Limine, kernel 7.2.8-1-cachyos, nvidia-open 615.71.09, gamescope 3.16.31-1, gamescope-session-cachyos 1.1.6-1. + +## Result: the kernel-parameter fix does not cure the picture +- Baseline (before): gaming mode corrupted without HDR; with HDR it worked but not at 175 Hz and not full screen. +- After `apply` + reboot (`modeset = Y`, `fbdev = Y`, NVIDIA modules in the initramfs): flickers heavily, artifacts, still no 175 Hz. + `modeset`/`fbdev` were already `Y` live before the fix (driver 615), so the fix changed little. +- Cause is not the parameters: NVIDIA's open bug "display modes above 2560x1440@120 with HDR cause flickering/corruption within + gamescope-session" (internal bug 5240452, April 2025, no fix as of March 2026; 555 up to 595+, RTX 3070 Ti/4090/5090; corruption is + display-side only): + https://forums.developer.nvidia.com/t/display-modes-above-2560x1440p-120hz-with-hdr-enabled-cause-flickering-corruption-within-gamescope-session/295314 + +## Bugs found in the fix on this PC (fixed in commit a5e9015 on feature/nvidia-gaming-fix) +- CachyOS writes Limine's line as `KERNEL_CMDLINE[default]+="..."`; the sed only matched `=`, so apply stopped with "Couldn't add the NVIDIA parameters". +- The kernel treats `nvidia_drm.modeset=1` and `nvidia-drm.modeset=1` alike; the check only knew the hyphen. +- tests/nvidia-hardware-test.sh did not set `SCRIPT_DIR`, so patch_file read `/patches/...`. + +## What gamescope did (journal, gaming mode) +- Picks the RTX 5080 (card1), DP-1, mode list has 3440x1440@175/144/100. It selected @60 by default; with + `-W 3440 -H 1440 -r 175` added (a copy of /usr/lib/steamos/gamescope-session, whose last line is `-O ... \` so args need a copy) + it selected @175 and did not crash, but the picture was the same. Steam then sets the Xwayland size to 1920x1080 (not full screen). +- `vkGetPhysicalDeviceFormatProperties2 returned zero modifiers` for 2 16-bit formats: harmless here. +- A gamescope SIGABRT (`double free or corruption`) at session exit, backtrace through libnvidia-eglcore and libvulkan_radeon. +- The PC froze once and was reset after a gaming-mode session (no kernel error logged). + +## What works: nested gamescope inside KDE (Wayland), borderless +- `gamescope -W 3440 -H 1440 -r 175 -f ...`: artifacts once the window is focused and fullscreen (unfocused it is fine). + Hypothesis, not proven: KWin's direct scanout of the fullscreen window. +- `gamescope -W 3440 -H 1440 -r 175 -b -e --hdr-enabled -- steam -gamepadui` (borderless): clean, full screen, about 175 Hz. +- So on NVIDIA the separate gamescope session (the SteamOS conversion) is blocked by the driver bug; a nested borderless gamescope works. + Whether Steamify gets a nested option for NVIDIA is the user's decision. + +## State of the PC after the test (to undo) +- The fix is applied (Limine file backup `/etc/default/limine.bak-gamescope-wizard`, early-load file, pacman hook): undo in INSTRUCTIONS.md. +- User override of the gaming session: `~/.config/systemd/user/gamescope-session.service.d/steamify-nvidia-test.conf` and + `~/.local/share/steamify/nvidia-test/`.