Proton, Wine prefixes, DXVK, VKD3D-Proton, and Steam Runtime

Scope

Proton is Valve's Steam Play compatibility tool based on Wine plus additional components. It translates Windows interfaces; it is not a virtual machine and does not contain a Windows installation.

Start with Steam's default recommended runtime and no launch options. Old community flags can disable newer fixes or hide the actual regression.

Execution paths

Native Linux

Windows

D3D 8-11

D3D 12

OpenGL fallback

Steam game

Build selected

Steam Linux Runtime

Proton and Wine services

Wine prefix / compatdata

Graphics API

DXVK

VKD3D-Proton

wined3d

Vulkan driver

Linux driver and services

Component boundaries

ComponentResponsibilityPersistent stateTypical failure surface
Proton
Steam integration and Windows compatibility bundle
Version selection and logs
Launcher, media, API, anti-cheat
Wine prefix
Per-App-ID Windows-like filesystem and registry
Compatdata
Saves, dependencies, corrupt state
DXVK
Direct3D 8/9/10/11 to Vulkan
Caches/logs
Vulkan driver and feature support
VKD3D-Proton
Direct3D 12 to Vulkan
Caches/logs
Vulkan extensions and D3D12 behavior
Steam Linux Runtime
Controlled Linux userspace for native games and Proton
Runtime deployment
Library/runtime mismatch

Prefix and compatdata

Steam normally keeps a per-game prefix under compatdata. It can include registry data, launchers, redistributables, and saves that are not protected by Steam Cloud. Treat prefix deletion as data removal, not routine cache clearing.

Version selection

Use this order: Steam recommended runtime, current stable Proton, Proton Experimental only for a named fix, then a custom build only with its upstream source and rollback. Change one layer at a time and restart Steam between comparison runs when required.

Reversible diagnostics

Enable a Proton log for one reproduction:

Remove the launch option after capturing the log. Record App ID, game build, Proton version, SteamOS, kernel, GPU driver/Mesa, and all launch options. Logs can contain paths and user-identifying data; review before sharing.

Native Linux is a runtime choice

A native Linux build may still use Steam Linux Runtime libraries. Valve's compatibility review can prefer Proton when the Windows build behaves better. Compare current builds rather than applying “native always wins” or “Proton always wins.”

Rollback

Remove added launch options, return to Steam's recommended compatibility tool, restore any backed-up prefix, and retest a clean launch. Do not delete the original compatdata until saves and launcher state are verified elsewhere.

Frequently asked questions

Are DXVK and VKD3D-Proton two consecutive stages?
Are DXVK and VKD3D-Proton two consecutive stages?
No. DXVK normally handles Direct3D 8/9/10/11 paths while VKD3D-Proton handles Direct3D 12. They are parallel choices selected by the game API.
Should I delete compatdata when a game fails?
Should I delete compatdata when a game fails?
Not as a first step. The prefix can contain saves, launcher state, and installed dependencies. Preserve data and test reversible launch/runtime changes before rebuilding a prefix.

Sources

Version history

  • 2026-07-15: Phase 5 publication with runtime, prefix, graphics-path, logging, and rollback boundaries.