steam runtime SDK

A binary compatible runtime environment for Steam applications on Linux.

Introduction

The Linux version of Steam runs on many Linux distributions, ranging from the latest rolling-release distributions like Arch Linux to older LTS distributions like Ubuntu 14.04. To achieve this, it uses a special library stack, the Steam Runtime, which is installed in ~/.steam/root/ubuntu12_32/steam-runtime. This is Steam Runtime version 1, codenamed scout after the Team Fortress 2 character class.

The Steam client itself is run in an environment that adds the shared libraries from Steam Runtime 1 'scout' to the library loading path, using the LD_LIBRARY_PATH environment variable. This is referred to as the LD_LIBRARY_PATH runtime. Most native Linux games available through Steam are also run in this environment.

A newer approach to cross-distribution compatibility is to use Linux namespace (container) technology, to run games in a more predictable environment, even when running on an arbitrary Linux distribution which might be old, new or unusually set up. This is implemented as a series of Steam Play compatibility tools, and is referred to as the Steam container runtime, or as the Steam Linux Runtime.

The Steam Runtime is also used by the Proton Steam Play compatibility tools, which run Windows games on Linux systems. Older versions of Proton (5.0 or earlier) use the same 'scout' LD_LIBRARY_PATH runtime as most native Linux games. Newer versions of Proton (5.13 or newer) use a container runtime with newer library versions: this is Steam Runtime version 2, codenamed 'soldier'.

More information about the LD_LIBRARY_PATH runtime and container runtime is available as part of the steam-runtime-tools documentation.

Reporting bugs and issues

Please report issues to the steam-runtime issue tracker.

The container runtimes have some known issues which do not need to be reported again.

The container runtime is quite complicated, so we will need additional information to be able to make progress on resolving issues.

Steam-runtime Repository

The Steam-runtime SDK relies on an APT repository that Valve has created that holds the packages contained within the steam-runtime. A single package, steamrt-dev, lists all the steam-runtime development packages (i.e. packages that contain headers and files required to build software with those libraries, and whose names end in -dev) as dependencies. Conceptually, a base chroot environment is created in the traditional way using debootstrap, steamrt-dev is then installed into this, and then a set of commonly used compilers and build tools are installed. It is expected that after this script sets the environment up, developers may want to install other packages / tools they may need into the chroot environment. If any of these packages contain runtime dependencies, then you will have to make sure to satisfy these yourself, as only the runtime dependencies of the steamrt-dev packages are included in the steam-runtime.

Installation

Steam Runtime version 1, 'scout' is automatically installed as part of the Steam Client for Linux.

Each version of the Steam container runtime is automatically downloaded to your Steam library if you install a game or a version of Proton that requires it. They can also be downloaded by opening steam:// links with Steam:

• Steam Linux Runtime 1.0 (scout): steam steam://install/1070560
• Steam Linux Runtime 2.0 (soldier): steam steam://install/1391110
• Steam Linux Runtime 3.0 (sniper): steam steam://install/1628350

All the software that makes up the Steam Runtime is available in both source and binary form in the Steam Runtime repository https://repo.steampowered.com/steamrt

Included in this repository are scripts for building local copies of the Steam Runtime for testing and scripts for building Linux chroot environments suitable for building applications.

Building in the runtime

To prevent libraries from development and build machines 'leaking' into your applications, you should build within a Steam Runtime container or chroot environment.

We recommend using a Toolbx, rootless Podman or Docker container for this:

podman pull registry.gitlab.steamos.cloud/steamrt/scout/sdk

or

sudo docker pull registry.gitlab.steamos.cloud/steamrt/scout/sdk

For more details, please consult the Steam Runtime SDK documentation.

Using a debugger in the build environment

To get the detached debug symbols that are required for gdb and similar tools, you can download the matching com.valvesoftware.SteamRuntime.Sdk-amd64,i386-scout-debug.tar.gz, unpack it (preserving directory structure), and use its files/ directory as the schroot or container's /usr/lib/debug.

For example, with Docker, you might unpack the tarball in /tmp/scout-dbgsym-0.20191024.0 and use something like:

sudo docker run \
--rm \
--init \
-v /home:/home \
-v /tmp/scout-dbgsym-0.20191024.0/files:/usr/lib/debug \
-e HOME=/home/user \
-u $(id -u):$(id -g) \
-h $(hostname) \
-v /tmp:/tmp \
-it \
steamrt_scout_amd64:latest \
/dev/init -sg -- /bin/bash

or with schroot, you might create /var/chroots/steamrt_scout_amd64/usr/lib/debug/ and move the contents of files/ into it.

Using detached debug symbols

Please see doc/debug-symbols.md.