Proton

Introduction

Proton is a tool for use with the Steam client which allows games which are exclusive to Windows to run on the Linux operating system. It uses Wine to facilitate this.

Most users should use Proton provided by the Steam Client itself. See this Steam Community post for more details.

The source code is provided to enable advanced users the ability to alter Proton. For example, some users may wish to use a different version of Wine with a particular title.

The changelog is available on our wiki.

Obtaining Proton sources

Acquire Proton's source by cloning https://github.com/ValveSoftware/Proton and checking out the branch you desire.

You can clone the latest Proton to your system with this command:

git clone --recurse-submodules https://github.com/ValveSoftware/Proton.git proton

Be sure to update submodules when switching between branches:

git checkout experimental_6.3
git submodule update --init --recursive

If you want to change any subcomponent, now is the time to do so. For example, if you wish to make changes to Wine, you would apply them to the wine/ directory.

Building Proton

Most of Proton builds inside the Proton SDK container with very few dependencies on the host side.

Preparing the build environment

You need either a Docker or a Podman setup. We highly recommend the rootless Podman setup. Please refer to your distribution's documentation for setup instructions (e.g. Arch Podman / Docker, Debian Podman / Docker).

The Easy Way

We provide a top-level Makefile which will execute most of the build commands for you.

After checking out the repository and updating its submodules, assuming that you have a working Docker or Podman setup, you can build and install Proton with a simple:

make install

If your build system is missing dependencies, it will fail quickly with a clear error message.

After the build finishes, you may need to restart the Steam client to see the new Proton tool. The tool's name in the Steam client will be based on the currently checked out branch of Proton. You can override this name using the build_name variable.

See make help for other build targets and options.

Manual building

Configuring the build

mkdir ../build && cd ../build
../proton/configure.sh --enable-ccache --build-name=my_build

Running configure.sh will create a Makefile allowing you to build Proton. The scripts checks if containers are functional and prompt you if any host-side dependencies are missing. You should run the command from a directory created specifically for your build.

The configuration script tries to discover a working Docker or Podman setup to use, but you can force a compatible engine with --container-engine=<executable_name>.

You can enable ccache with --enable-cache flag. This will mount your $CCACHE_DIR or $HOME/.ccache inside the container.

--proton-sdk-image=registry.gitlab.steamos.cloud/proton/soldier/sdk:<version> can be used to build with a custom version of the Proton SDK images.

Check --help for other configuration options.

NOTE: If SELinux is in use, the Proton build container may fail to access your user's files. This is caused by SELinux's filesystem labels. You may pass the --relabel-volumes switch to configure to cause the container engine to relabel its bind-mounts and allow access to those files from within the container. This can be dangerous when used with system directories. Proceed with caution and refer your container engine's manual.

Building

make

Important make targets:

make install - install Proton into your user's Steam directory, see the install Proton locally section for details.

make redist - create a redistribute build (redist/) that can be copied to ~/.steam/root/compatibilitytools.d/.

make deploy - create a deployment build (deploy/). This is what we use to deploy Proton to Steam users via Steamworks.

make module=<module> module - build both 32- and 64-bit versions of the specified wine module. This allows rapid iteration on one module. This target is only useful after building Proton.

make dxvk / make vkd3d-proton - rebuild DXVK / vkd3d-proton.

Figuring Out What Failed To Build

Proton build system invokes builds of many subprojects in parallel. If one subprojects fails there can be thousands of lines printed by other sub-builds before the top level exits. This can make the real reason of the build failing hard to find.

Appending 2>&1 | tee build.log will log the full build output to a build.log file. Searching that file from the bottom up for occurrences of Error should point to the right area. E.g.:

make 2>&1 | tee build.log
grep -n '] Error [0-9]' build.log

11220:make: *** [../Makefile.in:465: /builds/proton/proton/build-dir/.kaldi-i386-configure] Error 1
12427:make: *** [../Makefile.in:1323: deploy] Error 2

Debug Builds

To prevent symbol stripping add UNSTRIPPED_BUILD=1 to the make invocation. This should be used only with a clean build directory.

E.g.:

mkdir ../debug-proton-build && cd ../debug-proton-build
../proton/configure.sh --enable-ccache --build-name=debug_build
make UNSTRIPPED_BUILD=1 install

Install Proton locally

Steam ships with several versions of Proton, which games will use by default or that you can select in Steam Settings' Steam Play page. Steam also supports running games with local builds of Proton, which you can install on your machine.

To install a local build of Proton into Steam, make a new directory in ~/.steam/root/compatibilitytools.d/ with a tool name of your choosing and place the directory containing your redistributable build under that path.

The make install target will perform this task for you, installing the Proton build into the Steam folder for the current user. You will have to restart the Steam client for it to pick up on a new tool.

A correct local tool installation should look similar to this:

compatibilitytools.d/my_proton/
├── compatibilitytool.vdf
├── filelock.py
├── LICENSE
├── proton
├── proton_dist.tar
├── toolmanifest.vdf
├── user_settings.sample.py
└── version

To enable your local build in Steam, go to the Steam Play section of the Settings window. If the build was correctly installed, you should see "proton-localbuild" in the drop-down list of compatibility tools.

Each component of this software is used under the terms of their licenses. See the LICENSE files here, as well as the LICENSE, COPYING, etc files in each submodule and directory for details. If you distribute a built version of Proton to other users, you must adhere to the terms of these licenses.

Debugging

Proton builds have their symbols stripped by default. You can switch to "debug" beta branch in Steam (search for Proton in your library, Properties... -> BETAS -> select "debug") or build without stripping (see Debug Builds section).

The symbols are provided through the accompanying .debug files which may need to be explicitly loaded by the debugging tools. For GDB there's a helper script wine/tools/gdbinit.py (source it) that provides load-symbol-files (or lsf for short) command which loads the symbols for all the mapped files.

For tips on debugging see docs/DEBUGGING-LINUX.md and docs/DEBUGGING-WINDOWS.md.

compile_commands.json

For use with clangd LSP server and similar tooling.

Projects built using cmake or meson (e.g. vkd3d-proton) automatically come with compile_commands.json. For autotools (e.g. wine) you have to configure the build with --enable-bear that uses bear to create the compilation database. It's not on by default as it make the build slightly slower.

The build system collects all the created compile_commands.json files in a build subdirectory named compile_commands/.

The paths are translated to point to the real source (i.e. not the rsynced copy). It still may depend on build directory for things like auto-generated config.h though and for wine it may be beneficial to run tools/make_requests in you source directories as those changes are not committed.

You can then configure your editor to use that file for clangd in a few ways:

1. directly - some editors/plugins allow you to specify the path to compile_commands.json
2. via .clangd file, e.g.

cd src/proton/wine/
cat > .clangd <<EOF
CompileFlags:
  CompilationDatabase: ../build/current-dev/compile_commands/wine64/
EOF

3. by symlinking:

ln -s ../build/current-dev/compile_commands/wine64/compile_commands.json .

Runtime Config Options

Proton can be tuned at runtime to help certain games run. The Steam client sets some options for known games using the `STEAM_COM