FSR 4 support comes to SteamOS and Proton, hinting at Steam Machine support

For those running Linux or SteamOS, Valve's Proton compatibility layer for DirectX 12 translation (that is, to get Windows games and APIs to run without issue) has just received a significant update. VKD3D-Proton version 3.0, check out the GitHub page here, features several changes, but the ones that caught our attention were the addition of AMD FSR 4 support and Anti-Lag.

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"We added support for AGS WMMA intrinsics through VK_KHR_cooperative_matrix and VK_KHR_shader_float8, which is enough to support FSR 4," the update writes. Like the Windows-based version of FSR 4, support is officially limited to RDNA 4 GPUs and the Radeon RX 9000 Series, but the update also includes a fallback mode that makes FSR 4 work on older RDNA 3 and even RDNA 2 GPUs that use int8 and float16.

However, per the release notes, running FSR 4 on previous-generation Radeon hardware results in a "significant performance cost" and a reduction in overall image fidelity. This emulation path won't be included in the official Proton build, but it does pave the way for the technology to arrive in time for the launch of Valve's new Steam Machine in early 2026.

• Read more: Is the Steam Machine's RDNA 3 GPU powerful enough to run every game on Steam in 4K?
• Read more: AMD's FSR 4 could work on Xbox Series X but not PlayStation 5
• Read more: FSR 4 is still RDNA 4 only, are Radeon gamers with RDNA 2 or RDNA 3 GPUs being left behind?

During Valve's big reveal event for its upcoming PC-console hybrid, which is powered by an RDNA 3 GPU that is reportedly over six times as powerful as the Steam Deck, Digital Foundry asked the company if FSR 4 support was possible on the mini PC, as it's going to rely heavily on FSR to achieve a 4K output resolution. Although it didn't confirm that it was coming, the company did indicate that it's hoping FSR 4 support will come to the RDNA 3 generation, and if it does, the Steam Machine will be ready.

One reason the int8 fallback for FSR 4 exists is to run on older RDNA hardware. In fact, the only reason people have been emulating FSR 4 to run on RDNA 3 and RDNA 2 GPUs is that AMD accidentally leaked the source code. That said, for an optimized version of FSR 4 to run on something like the Steam Deck, AMD would need to do additional work to improve performance.

Ultimately, FSR 4 coming to Proton is a step toward this, and we wouldn't be surprised if AMD announces something like FSR 4 Light for all Radeon gamers.