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Introduction

Proton is a tool for use with the Steam client which allows games which are exclusive to Windows to run on Linux and macOS operating systems. 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

• Make sure you are opted into the Steam Client Beta!
• Proton requires graphics drivers that are more recent than what is typically packaged in most distributions; please read the list of requirements and quickstart for Ubuntu 18.04 users
• Install and play games! Please refer to this post for more information.

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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.

The most current source for Proton is here: https://github.com/ValveSoftware/Proton

Which you can clone to your system with this command:

   git clone https://github.com/ValveSoftware/Proton.git proton

After cloning the Proton git repository, the next step will be to obtain the various submodules that go into building Proton:

    cd proton
    #for linux:
    git submodule update --init wine dxvk ffmpeg openal-soft openvr
    #for macos:
    git submodule update --init

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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Building for Linux

To build Proton for Linux, set up a Debian machine with the Steam runtime and chroots as documented in the Steam Runtime repository:

https://github.com/ValveSoftware/steam-runtime

In addition, you will need to install gcc-5 and a long list of dependencies required for Wine. The following set of commands is an example session, and may not be complete.

    cd ~
    git clone https://github.com/ValveSoftware/steam-runtime.git
    cd steam-runtime
    #install the end-user steam runtime:
    ./build-runtime.py
    #install the 32-bit scout_beta runtime:
    ./setup_chroot.sh --beta --i386
    #enter the 32-bit runtime:
    schroot --chroot steamrt_scout_beta_i386

This will enter the chroot environment, where you would issue the following commands:

    sudo apt-get install gcc-5 g++-5 g++-5-multilib flex bison libosmesa6-dev libpcap-dev libhal-dev libsane-dev libv4l-dev libgphoto2-2-dev libcapi20-dev libgsm1-dev libmpg123-dev libvulkan-dev libxslt1-dev nasm yasm
    sudo update-alternatives --install `which gcc` gcc `which gcc-5` 50
    sudo update-alternatives --set gcc `which gcc-5`
    sudo update-alternatives --install `which g++` g++ `which g++-5` 50
    sudo update-alternatives --set g++ `which g++-5`
    sudo update-alternatives --install `which cpp` cpp-bin `which cpp-5` 50
    sudo update-alternatives --set cpp-bin `which cpp-5`
    exit

Next, you need to repeat the process, but for amd64:

    ./setup_chroot.sh --beta --amd64
    schroot --chroot steamrt_scout_beta_amd64

And then repeat all of the commands to install gcc and Wine dependencies again.

In addition, your host system will need to be able to run Wine in both 64- and 32-bit modes in order to create the default prefix. It is recommended to install Wine from your package manager, including its optional dependencies.

The openal-soft build system requires cmake 3.0.2 or later, which is newer than the Steam runtime SDK provides. You will need to build and install a newer cmake into each of the runtimes. For convenience, the build_proton.sh script will attempt to use cmake from ~/opt32/bin/ and ~/opt64/bin/, if available.

The following example session obtained and built cmake:

  cd /tmp
  wget https://cmake.org/files/v3.11/cmake-3.11.4.tar.gz
  schroot --chroot steamrt_scout_beta_i386
  tar -xzf cmake-3.11.4.tar.gz
  cd cmake-3.11.4
  ./configure --parallel=4 --prefix=~/opt32
  make -j 4 && make install
  exit
  rm -rf cmake-3.11.4
  schroot --chroot steamrt_scout_beta_amd64
  tar -xzf cmake-3.11.4.tar.gz
  cd cmake-3.11.4
  ./configure --parallel=4 --prefix=~/opt64
  make -j 4 && make install
  exit

Finally, change your directory back to proton, and run:

    cd ../proton
    ./build_proton.sh

That should configure and build Wine, and then package the result up into dist/. It is important to examine the output near the end of build/wine.win{64,32}/config.log to ensure that you have all of the relevant libraries in each chroot. Search for 'executing Makefile commands' in config.log to find messages about missing libraries. It is normal to be missing a few libraries, including OpenCL, OSS, and libav.

NOTE: The build_proton.sh script builds most components inside the Steam runtime chroot. However, dxvk will not build in that environment, so the build_proton.sh script will build it on your local system. This will require you to be able to build dxvk on your local system; refer to the dxvk README.md for more details.

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Building for macOS

To build Proton for macOS, install the latest Xcode command line tools, as well as cmake (for openal-soft) and a recent nasm (for libjpeg-turbo), libtool, and automake. You can use a packager like Homebrew to find these packages.

    brew install cmake nasm libtool automake

Then run:

    ./build_proton.sh

TODO - Surely there are other dependencies we have not listed there.

It is important to examine the output near the end of build/wine.win{64,32}/config.log to ensure that you have all of the relevant libraries required to build Wine properly.

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Deploying

Once built, the dist/ directory will contain the files which can be distributed through Steam. For testing purposes, you should be able to clear out the files in your steamapps/common/Proton directory and replace them with the contents of dist/. The proton script will unpack the files on first run. Note that if you use the Steam client to verify local files, it will restore the production version of Proton.

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.

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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. If you want to set different PROTON_ variables than the "user_settings.py" for a specific game, use the Set Launch Options under the games Properties. You can launch the game as you would with PROTON_VARIABLE=1 %command% (source).

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
wined3d11	PROTON_USE_WINED3D11	Use OpenGL-based wined3d instead of Vulkan-based DXVK for d3d11.
nod3d11	PROTON_NO_D3D11	Disable d3d11.dll, for games which can fall back to and run better with d3d9.
noesync	PROTON_NO_ESYNC	Do not use eventfd-based in-process synchronization primitives.