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 will prefer to use Proton provided by the Steam client itself. 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.
Getting Started with Proton from Steam Play
- As the new Steam Play is still in Beta, it is recommended that you opt into the Steam Client Beta for the latest features and fixes.
- Proton works best with the latest graphics drivers. For some cutting edge games and graphical features, you may need drivers newer than what your distribution ships.
- Install and play games! Please refer to this post for more information.
- Visit the changelog for information about recent updates.
Obtaining Proton from source
NOTE: If you are not comfortable in a command line terminal, or if you find any of the information presented in here strange and uncomfortable, then this is probably not for you. The instructions are likely to be incomplete and require some knowledge and skill on your part, and there is no warranty or guarantee that anyone will help you with this process.
We strongly recommend that most users use the production build of Proton.
Acquire Proton's source by cloning https://github.com/ValveSoftware/Proton and checking out the branch you desire. Be sure to update submodules when switching between or updating branches.
You can clone the latest Proton to your system with this command:
git clone --recurse-submodules https://github.com/ValveSoftware/Proton.git proton cd proton
If you wish to change any subcomponent, now is the time to do so. For example, if you wish make changes to Wine, you would apply those changes to the wine/ directory.
Easy build path
Building Proton is quite complicated. We provide a top-level Makefile which will execute most of the build commands for you. This section describes how to use this Makefile for simple Proton builds.
This Makefile uses a virtual machine to create a consistent build environment.
The VM is managed with Vagrant, which you will
need to install and configure before invoking these commands. Proton's build
system is most well tested with Vagrant's VirtualBox and libvirt/qemu backends.
It also requires the vagrant-sshfs plugin. You may run into problems with the
shared folder (
vagrant_share) and/or CPU and memory usage with other
If your build VM gets cluttered, or falls out of date, you can use
vagrant destroy to wipe the VM clean, then invoke one of the below commands to start
After checking out Proton and updating its submodules, you can use these targets to build Proton:
make install - This will build and install Proton into your user's Steam
directory. 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
make redist - This will create a build which you can easily redistribute to
other users. The package will be dropped into a new directory in
vagrant_share/, named after the nearest Git tag (see
git describe). Copying
this directory into
~/.steam/root/compatibilitytools.d/ will make the build
available after restarting the Steam client. If you distribute your build to
other users, be sure to understand and follow your obligations to make your
source code modifications available to your users, see LICENSE.
make deploy - This will create a deployment tarball and set of files which
can be distributed as a Proton package. This is what we use to deploy Proton to
Steam users. The package will be dropped into a new directory in
vagrant_share/, named after the nearest Git tag (see
make clean - This will completely erase the Proton build tree within the VM.
make help - View the Makefile documentation and examples.
We also provide targets useful for simple Wine development:
make proton - This will build Proton without copying its files out of the VM.
make module=<module> module - This will build both 32- and 64-bit versions of
the specified module, and copy the result into the
This allows rapid iteration on one module. This target is only useful after
make dxvk - This will rebuild DXVK and copy it into
make vkd3d-proton - This will rebuild vkd3d-proton and copy it into
If you are doing significant Wine development or want to control the build with more fine detail, see the full documentation below.
At a high level, the build instructions are:
- Set up your build environment
- Configure the build
- Build Proton
- Install Proton locally (optional)
See below for more details on all of these steps. Please read all of the instructions before proceeding.
Set up the build environment
Proton has a lot of build-time dependencies. The following instructions describe how we create the build environment for the production builds of Proton. For reproducibility and security reasons, we will be setting up a Debian virtual machine. However, you should be able to follow these instructions on other distributions as well.
Proton provides a Vagrantfile, which will automatically set up the Debian VM for you. After installing Vagrant, initialize the VM by running from within the Proton directory:
It will take a long time to download and install the Steam runtime containers and so on. Eventually it will complete. You can SSH into the virtual machine with:
At this point you will need to configure the build directory. See below.
The Vagrantfile is set up to rsync the
proton directory into the VM on boot.
On the host machine, you can use
vagrant rsync-auto to have Vagrant
automatically sync changes on your host machine into the build machine. It is
recommended that you make changes on your host machine, and then perform the
build in the VM. Any changes you make in the
proton directory on the VM may
be overwritten by later rsync updates from the host machine.
The Vagrantfile also creates a directory called
vagrant_share in the
directory of your host machine, which is mounted at
/vagrant within the VM.
You can use this shared folder to move your Proton build out of the VM, or as
one way to copy files into the VM.
When you are done with the VM, you can shut it down from the host machine:
Please read the Vagrant documentation for more information about how to use Vagrant VMs.
If you do not wish to use Vagrant, you can read through the Vagrantfile for the list of dependencies and instructions on how to set up your own machine or another VM of your choosing. It is aimed at Debian 10, but you should be able to adapt them for other distributions.
Configure the build
After setting up the build machine, it is time to run the configure script which will generate the Makefile to build your project. Run these steps. You may of course use whatever paths you like.
To build Proton within the Steam Runtime (see
Makefile for the correct
protonsdk_version value to use):
mkdir build/ cd build ../proton/configure.sh --steam-runtime-image=registry.gitlab.steamos.cloud/proton/soldier/sdk:$(protonsdk_version)
Or, if you are building without the Steam runtime, then instead use:
Tip: If you are building without the Steam runtime, you should now run
make obj-wine64/Makefile obj-wine32/Makefile and check the files
obj-wine32/config.log for missing packages.
won't be supported. A couple of missing packages are normal:
oss. More than that may indicate a problem. Please see your
distro's documentation to acquire the considerable build dependencies for Wine.
Be aware that the build you make may not run correctly on other machines and
A couple of Makefile targets are provided.
make dist will create a Proton installation in
dist/ that you can install
manually (see below), or automatically with
make deploy will package Proton up for distribution via Steamworks.
Install Proton locally
Steam ships with several versions of Proton, which games will use by default or
that you can select in Steam Settings's Steam Play page. Steam also supports
running games with local builds of Proton, which you can install on your
install target will perform the below steps for you.
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 contents of
dist into that folder. 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 like 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.
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.py and modifying it appropriately.
This file is located in the Proton installation directory in your Steam library
If you want to change the runtime configuration for a specific game, you can
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.
|Compat config string||Environment Variable||Description|
|PROTON_LOG||Convenience method for dumping a useful debug log to
|PROTON_LOG_DIR||Output log files into the directory specified. Defaults to your home directory.|
|PROTON_DUMP_DEBUG_COMMANDS||When running a game, Proton will write some useful debug scripts for that game into
|PROTON_DEBUG_DIR||Root directory for the Proton debug scripts,
|wined3d||PROTON_USE_WINED3D||Use OpenGL-based wined3d instead of Vulkan-based DXVK for d3d11, d3d10, and d3d9.|
|nod3d11||PROTON_NO_D3D11||Disable d3d11.dll, for d3d11 games which can fall back to and run better with d3d9.|
|nod3d10||PROTON_NO_D3D10||Disable d3d10.dll and dxgi.dll, for d3d10 games which can fall back to and run better with d3d9.|
|noesync||PROTON_NO_ESYNC||Do not use eventfd-based in-process synchronization primitives.|
|nofsync||PROTON_NO_FSYNC||Do not use futex-based in-process synchronization primitives. (Automatically disabled on systems with no
|noxim||PROTON_NO_XIM||Enabled by default. Do not attempt to use XIM (X Input Methods) support. XIM support is known to cause crashes with libx11 older than version 1.7.|
|nativevulkanloader||Use the Vulkan loader shipped with the game instead of Proton's built-in Vulkan loader. This breaks VR support, but is required by a few games.|
|forcelgadd||PROTON_FORCE_LARGE_ADDRESS_AWARE||Force Wine to enable the LARGE_ADDRESS_AWARE flag for all executables. Enabled by default.|
|heapdelayfree||PROTON_HEAP_DELAY_FREE||Delay freeing some memory, to work around application use-after-free bugs.|
|gamedrive||PROTON_SET_GAME_DRIVE||Create an S: drive which points to the Steam Library which contains the game.|
|noforcelgadd||Disable forcelgadd. If both this and
|oldglstr||PROTON_OLD_GL_STRING||Set some driver overrides to limit the length of the GL extension string, for old games that crash on very long extension strings.|
|vkd3dfl12||Force the Direct3D 12 feature level to 12, regardless of driver support.|
|hidenvgpu||PROTON_HIDE_NVIDIA_GPU||Force Nvidia GPUs to always be reported as AMD GPUs. Some games require this if they depend on Windows-only Nvidia driver functionality. See also DXVK's nvapiHack config, which only affects reporting from Direct3D.|
|WINE_FULLSCREEN_INTEGER_SCALING||Enable integer scaling mode, to give sharp pixels when upscaling.|
|cmdlineappend:||Append the string after the colon as an argument to the game command. May be specified more than once. Escape commas and backslashes with a backslash.|
|nowritewatch||PROTON_NO_WRITE_WATCH||Disable support for memory write watches in ntdll. This is a very dangerous hack and should only be applied if you have verified that the game can operate without write watches. This improves performance for some very specific games (e.g. CoreRT-based games).|
|seccomp||PROTON_USE_SECCOMP||Note: Obsoleted in Proton 5.13. In older versions, enable seccomp-bpf filter to emulate native syscalls, required for some DRM protections to work.|
|d9vk||PROTON_USE_D9VK||Note: Obsoleted in Proton 5.0. In older versions, use Vulkan-based DXVK instead of OpenGL-based wined3d for d3d9.|