Valve Adds FEX and Lepton to Get Past Proton’s x86 Assumption
Proton has always assumed there’s an x86 chip underneath it, which is a problem for the Arm-based Steam Frame headset. Valve is closing that gap with two more compatibility layers, FEX and Lepton, according to TechSpot.
FEX is Valve’s port of fex-emu, an open-source project that emulates x86-64 instructions on Arm hardware. It started as a side project back in 2018 and has grown into what its own site now calls an advanced binary recompiler for the modern x86-64 instruction set, with code caching to reduce stutter and direct calls into OpenGL and Vulkan to cut overhead. Valve engineer Pierre-Loup Griffais told The Verge last year that the company has funded lead developer Ryan Houdek since FEX was a prototype, expecting close to a decade of work before it would be reliable enough to ship.
Lepton is the second layer, built on the existing Waydroid project, and it runs standard Android APKs on SteamOS inside a software container. The reason it exists: a lot of standalone VR titles for Steam Frame were built for Android-based Quest headsets, not Windows. VR.org dug through Steam’s own metadata and found that 52 of the first 120 “Great on Frame” games run as Android executables through Lepton, including the first three Steam games ever listed with no Windows, Mac, or Linux build at all. Valve’s Jeremy Selan told The Verge that many of those are VR developers who “are now free to bring those to Steam, and they’ll just work on this device,” and colleague Lawrence Yang added that Valve hasn’t ruled out non-VR Android apps reaching Steam the same way, though games remain the focus for now.
With FEX in place, Griffais told Rock Paper Shotgun that Valve is now looking at SteamOS on other Arm hardware beyond the Frame, aiming for a future where buyers don’t have to weigh a device’s specs and price against losing part of their existing library.
007 First Light Picks Up FSR 4.1, No Patch Notes
IO Interactive slipped AMD’s FSR 4.1 upscaler into 007 First Light through the game’s recent PC path-tracing update, without mentioning it anywhere in the patch notes, OC3D reports. At launch the game only supported FSR 3.1.5, and not in a way that let AMD’s “FSR Upgrade” driver override kick in, so Radeon owners were left without the newer AI upscaler while the marketing leaned hard on the game’s Nvidia partnership.
One player reported that AMD’s in-game overlay lists 007 First Light as FSR 4.1-supported but never shows it as active during play, even though the visuals reportedly improve with it turned on, which points to a non-standard implementation rather than the feature simply not working. Path tracing in the game still depends on Nvidia’s DLSS Ray Regeneration for its image quality, so Nvidia cards keep the stronger result regardless of the FSR update, and it’s still not clear whether path tracing runs on non-Nvidia hardware at all.