FEX-emu – Run x86 applications on ARM64 Linux devices

Post by wmf » Fri, Nov 21, 2025, 2:46 AM UTC

astrange wrote: post #16

jsheard wrote: post #10

Earlier quoted context omitted.

My understanding is that Rosetta sidesteps a bunch of tricky memory model issues by using non-standard hardware extensions only present in Apple Silicon, so even if Apple did share Rosetta, which they certainly won't, it wouldn't work properly on Valves hardware anyway.

It's not only present in Apple Silicon, it's just not required by the ARM standard. Fujitsu also has an ARM64 CPU with TSO.

Post by snvzz » Fri, Nov 21, 2025, 3:12 AM UTC

geerlingguy wrote: post #8

sitkack wrote: post #6

Earlier quoted context omitted.

Too bad Arm doesn't allow architectural licenses, because this is exactly the kind of thing Valve and the FEX developers would want to extend the ISA to support. I bet we see a RISC-V backend to FEX in the next 6 months, it probably already exists in a private repo. FEX is the shootstring, extra special discount budget (not maligning) version of Rosetta. Apple should sell Rosetta to Valve.

Box64 already runs on RISC-V. Just, the available processors are so slow it's hard to even play 5-10 year old games.

Post by paulryanrogers » Fri, Nov 21, 2025, 3:23 AM UTC

jasonjmcghee wrote: post #23

Curious how this will impact the major games that are incompatible due to denuvo type stuff

Post by adgjlsfhk1 » Fri, Nov 21, 2025, 3:34 AM UTC

globalnode wrote: post #25

open-paren wrote: post #2

> FEX allows you to run x86 applications on ARM64 Linux devices, similar to qemu-user and box64. It offers broad compatibility with both 32-bit and 64-bit binaries, and it can be used alongside Wine/Proton to play Windows games. > It supports forwarding API calls to host system libraries like OpenGL or Vulkan to reduce emulation overhead. An experimental code cache helps minimize in-game stuttering as much as possibl…

Does that mean I can run windows games on my rpi? (In theory at least)

Post by trollbridge » Fri, Nov 21, 2025, 3:35 AM UTC

fooblaster wrote: post #13

How does fex deal with the fact that the memory model on arm is weak and x86 is total store ordering. It seems like would need to hammer performance by putting memory barriers everywhere to handle all cases. Perhaps fex only works when there are well defined mutexes it can gain visibility into? anyone know?