Proton – ValveSoftware

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][steam-play-introduction] 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][changelog].

[steam-play-introduction]: https://steamcommunity.com/games/221410/announcements/detail/1696055855739350561
[changelog]: https://github.com/ValveSoftware/Proton/wiki/Changelog

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 which Proton's build system uses
internally. You should never need to use either container engine manually unless
working on those parts of build system directly.

We highly recommend [the rootless Podman setup][rootless-podman]. Please refer
to your distribution's documentation for setup instructions (e.g. Arch
[Podman][arch-podman] / [Docker][arch-docker], Debian [Podman][debian-podman] /
[Docker][debian-docker]).

[rootless-podman]: https://github.com/containers/podman/blob/main/docs/tutorials/rootless_tutorial.md
[arch-podman]: https://wiki.archlinux.org/title/Podman
[arch-docker]: https://wiki.archlinux.org/title/Docker
[debian-podman]: https://wiki.debian.org/Podman
[debian-docker]: https://wiki.debian.org/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][selinux-labels]. You may pass the --relabel-volumes switch to
configure to cause the [container engine to relabel its
bind-mounts][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.

[selinux-labels]: https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/security-enhanced_linux/sect-security-enhanced_linux-working_with_selinux-selinux_contexts_labeling_files
[bind-mounts]: https://docs.docker.com/storage/bind-mounts/

Building

make

Important make targets:*

make install - install Proton into your user's Steam directory, see the [install Proton
locally](#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

ARM64 Builds

You need an ARM64 build machine and pass --target-arch=arm64 to configure.sh.

It's not possible to use the resulting builds in x86 Steam running via FEX.

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. Wine also generates the file on its own via makedep.

Proton's build system collects all the 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/wine-x86_64/
EOF

ln -s ../build/current-dev/compile_commands/wine-x86_64/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_COMPAT_CONFIG variable.
You can override these options using the environment variables described below.

The best way to set these environment overrides for all games is by renaming
user_settings.sample.py to user_settings.py and modifying it appropriately.
This file is located in the Proton installation directory in your Steam library
(often ~/.steam/steam/steamapps/common/Proton #.#).

If you want to change the runtime configuration for a specific game, you can
use the Set Launch Options setting in the game's Properties dialog in the
Steam client. Set the variable, followed by %command%. For example, input
"PROTON_USE_WINED3D=1 %command%" to use the OpenGL-based wined3d renderer
instead of the Vulkan-based DXVK renderer.

To enable an option, set the variable to a non-0 value. To disable an
option, set the variable to 0. To use Steam's default configuration, do
not specify the variable at all.

All of the below are runtime options. They do not effect permanent changes to
the Wine prefix. Removing the option will revert to the previous behavior.

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