VKD3D-Proton version: 3.0.1
GPU: AMD Radeon RX 9070 XT (RADV GFX1201 / RDNA 4)
Mesa: 26.1.0
OS: PikaOS (Debian-based), kernel 7.0.6
Proton: GE-Proton10-34
Game: Forza Horizon 6 (Steam AppID 2483190)

Description

Enabling any ray tracing feature in Forza Horizon 6 causes a crash during the loading screen. Without RT the game runs perfectly at 4K/Extreme settings. The issue is specific to RDNA 4 — no
equivalent failure occurs on other hardware.

Steps to Reproduce

1. Launch Forza Horizon 6 via GE-Proton10-34 with VKD3D-Proton 3.0.1
2. Enable RTGI (Low) or RT Reflections (Low) in graphics settings
3. Restart the game
4. Crash occurs during loading screen (~70 seconds in)

Expected Behavior

Game loads with ray tracing enabled.

Actual Behavior

Game crashes on load. The game's crash reporter logs:

REASON: Video card
BUCKET: Device removed: Unknown error: 0x00000102
REASON_INFO: 0x0000000000000102
EXCEPTION: ACCESS_VIOLATION_WRITE
UI_SCENE: Loading
UPTIME: 70.790001

PROTON_LOG shows these warnings consistently before the crash:

fixme:vkd3d-proton:d3d12_command_list_process_enhanced_barrier_texture: Transitioning away from UNDEFINED, but there is no DISCARD flag. Uncertain what is expected here. vkd3d-proton will
force a discard.
warn:vkd3d-proton:d3d12_fence_set_native_sync_handle_on_completion_explicit: Event completion for native sync handle is already in the list.

The enhanced barrier warning appears only when RT is enabled. With the previous bundled VKD3D in GE-Proton10-34, the crash produced VK_ERROR_DEVICE_LOST. With 3.0.1 the device lost is gone
but the game-side timeout remains, suggesting progress in translation but the RT pipeline submission or compilation is still hanging.

Notes

• RADV_DEBUG=noopt, RADV_PERFTEST=gpl, RADV_PERFTEST=rt,gpl all tried — no change
• Shader caches cleared — no change
• VRAM at crash: ~5 GB used of 16 GB — not a VRAM issue
• Crash is during loading, pointing to RT pipeline compilation rather than RT rendering
• A Mesa/RADV bug report has also been filed as this may be shared root cause