Valve put up a new Steam Linux Runtime 4.0 with a move towards 64-bit

To ensure games run well on Linux either via Native Linux builds or Windows games with Proton, part of the magic is in the Steam Linux Runtime. A new version of it, the Steam Linux Runtime 4.0 was recently put up with some pretty big changes.

What's the point of it? It ensures Steam and games run through Steam on Linux work properly across all the many different Linux distributions. Another secret Valve sauce for Linux. Well, not secret at all but you get my meaning I'm sure.

Steam Linux Runtime 4.0 brings with it a major bump to the version of Debian as the base of the packages to Debian 13.2. Some of the other highlights from the initial release notes:

• Some libraries like libFLAC and OpenSSL are new major versions with a new SONAME. These libraries are not ABI-compatible with their equivalents in sniper, and making use of them might also require code changes due to API compatibility breaks.
• "Classic" SDL 2 has been replaced by sdl2-compat, but porting games to use SDL 3 directly is recommended.
• Many larger and/or older libraries have been removed completely. Some might be added back in at a later date if we find that they are necessary. For example:
  • AT-SPI
  • FLTK
  • GLUT
  • GTK
  • ICU
  • libproxy
  • libsoup
  • ncurses
  • Qt
  • SDL 2 versions of SDL_image, etc. (SDL 3 versions are still available)
• Most libraries that were previously available for both x86_64 and i386 are now only available for x86_64. In general, we only have i386 libraries if they are expected to be needed for Proton or for the steam-runtime-tools diagnostic tools.

And a follow-up update:

Platform libraries

• Update packages from Debian 13.2 point release:
  • cups_2.4.10-3+deb13u2 (Debian#1109471)
  • libxml2_2.12.7+dfsg+really2.9.14-2.1+deb13u2 (CVE-2025-9714)
  • onetbb_2022.1.0-1+deb13u1 (test-suite fixes)
  • openssl_3.5.4-1~deb13u1
  • systemd_257.9-1~deb13u1
  • xorg_1:7.7+24+deb13u1 (Debian#1094494)
• Merge modified packages from Debian 13.2 point release:
  • base-files
  • curl (CVE-2025-9086, CVE-2025-10148, CVE-2025-11563)

SDK

• Update packages from Debian 13.2 point release:
  • Linux kernel headers 6.12.57

You as a gamer and Linux user don't need to do anything, it's all used automatically depending on what Valve set.

They've also confirmed the Steam Linux Runtime 5 is also under development, currently in the prototype stage.