2026-04-08 22:23 UTC
So armed with this knowledge, what exactly are we trying to accomplish here?
Well, we are unfortunately stuck with running Steam through FEX until Valve either publishes an official arm64 client or at least recovery images to the unreleased SteamFrame.
But wouldn’t it be neat, if we could build a custom Arm64EC proton runtime to simply select and reap the performance benefits on arm64 hosts?
So first of all I spent hours cloning and building Proton and one `make redist` later we actually have a proton runtime with arm64 binaries? That was easy, let’s drop it into `.local/share/Steam/compatibilitytools.d` and see what happens.
🧵 3/7
Replies (1)
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@drakulix@social.dreampi.es 2026-04-08 22:25
I picked Celeste as a pretty easy to run and well supported game. So I selected the new runtime, click Launch and…. we get an actually error dialog from Steam. “Compatibility tool failed”, not very helpful, but expected. Browsing through steam log files, we find this in `compat_log.txt`: ``` [2026-04-08 20:35:22] Tool 0 "proton-localbuild" has a dependency on tool 4185400. [2026-04-08 20:35:22] Tool 4185400 "" is unknown for appID 504230. ``` A quick look on steamdb.info is enough to figure out the name of our missing steam app: “Steam Linux Runtime 4.0 - Arm64”. 🧵 4/7