New FUTEX Syscalls Revived to Support Valve's ARM64 Gaming Push

The open-source consulting firm Igalia continues its work on the Linux kernel to enable Steam Play gaming on the ARM64 architecture. The main goal is to ensure that the FEX emulator — which lets x86 and x86_64 games run on devices like the Steam Frame — operates efficiently.

The effort dates back to last year. After several months of other kernel work, an updated round of patches has finally appeared, introducing the new get_robust_list2 and set_robust_list2 system calls tied to the FUTEX mechanism.

FUTEX (fast userspace mutex) is a core thread-synchronization primitive in Linux, and the "robust list" helps handle locks cleanly when a thread exits without releasing them. Extending these calls matters for emulation, where x86 semantics must be reproduced carefully on ARM64 so that games run fast and without glitches.

The work fits into Valve's broader ambitions to bring gaming to ARM64. The available details are still modest, but the return of these patches to active development signals that the initiative is moving forward.

Source: Phoronix