Introduction

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 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.

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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.

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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.

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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 backends.

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 over.

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 build_name variable.

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 git describe).

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 vagrant_share directory. This allows rapid iteration on one module. This target is only useful after building Proton.

make dxvk - This will rebuild DXVK and copy it into vagrant_share.

make vkd3d-proton - This will rebuild vkd3d-proton and copy it into vagrant_share.

If you are doing significant Wine development or want to control the build with more fine detail, see the full documentation below.

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Building

At a high level, the build instructions are:

1. Set up your build environment
2. Configure the build
3. Build Proton
4. Install Proton locally (optional)

See below for more details on all of these steps. Please read all of the instructions before proceeding.

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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:

    vagrant up

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:

    vagrant ssh

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 proton 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:

    vagrant halt

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.

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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 using the official Proton SDK images:

    mkdir build/
    cd build
    ../proton/configure.sh

If you want to build with a custom version of the Proton SDK images, then instead use:

    ../proton/configure.sh --proton-sdk-image=registry.gitlab.steamos.cloud/proton/soldier/sdk:<version>

Or, if you want to build without the Proton SDK, then instead use:

    ../proton/configure.sh --no-proton-sdk

Tip: If you are building without the Steam runtime, you should now run make wine-configure64 wine-configure32 and check the files obj-wine64/config.log and obj-wine32/config.log for missing packages. Search for won't be supported. A couple of missing packages are normal: opencv, 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 distributions.

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Build Proton

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 install.

make deploy will package Proton up for distribution via Steamworks.

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Building without the VM

Since most of the build happens inside the Proton SDK container, building without a VM should be mostly safe. It requires a working container engine (Docker / Podman) and few command line tools.

Running configure.sh will check if containers are functional and prompt you if any dependencies are missing.

The build by default uses Docker, but you can switch to another, 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.

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.

Example:

mkdir build && cd build
../proton/configure.sh --container-engine=podman --enable-ccache
make dist

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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 machine. The 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.

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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.

Compat config string	Environment Variable	Description
	PROTON_LOG	Convenience method for dumping a useful debug log to $PROTON_LOG_DIR/steam-$APPID.log For more thorough logging, use user_settings.py.
	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 $PROTON_DEBUG_DIR/proton_$USER/.
	PROTON_DEBUG_DIR	Root directory for the Proton debug scripts, /tmp by default.
	PROTON_CRASH_REPORT_DIR	Write crash logs into this directory. Does not clean up old logs, so may eat all your disk space eventually.
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 FUTEX_WAIT_MULTIPLE support.)
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.
enablenvapi	PROTON_ENABLE_NVAPI	Enable NVIDIA's NVAPI GPU support library.
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 forcelgadd are set, enabled wins.
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.
vkd3dbindlesstb		Put force_bindless_texel_buffer into VKD3D_CONFIG.
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.