January 8, 2026
Acronyms vs Orcs: choose your fighter
Support for the TSO memory model on Arm CPUs
Apple’s secret switch, gamer hopes, and acronym chaos collide
TLDR: Arm can enable an x86-like memory mode to make emulators and games behave, but kernel devs balk because Apple’s version isn’t formally documented. The community splits between “give us the switch” pragmatists and skeptics who fear shipping a mystery feature that might change later.
Arm chips can flip a “TSO mode” that makes them behave more like x86 PCs so translated apps (hello, games) don’t glitch. Hacker hero Hector Martin proposed kernel knobs so apps can ask for this mode, but maintainers hit the brakes, warning Apple’s version is undocumented and could change. Cue community fireworks. One camp chants, “Let the gamers play!” — saying only emulators really need it and the fragmentation fear is overblown. Another camp fires back: “Don’t ship mystery magic” — if Apple’s switch isn’t formally defined, you can’t trust it. And yes, the acronym TSO sparked jokes, because on IBM mainframes it means “Time Sharing Option.” Suddenly we’re in a retro-computing comedy club.
In the comments, dmitrygr side-eyes Apple: their TSO bits were built for Rosetta 2 and could be a moving target. slabtickler calls the fragmentation angle “flaky,” arguing today’s need is narrow and practical: emulators and games. rbanffy drops the meme of the day: we need a three-letter-acronym overlord. Meanwhile, nostalgia and drama swirl as one user laments Hector stepping away. The vibe? Switch wars, trust issues, acronym beef, and gamers begging for a turbo button so the orcs stop rubber-banding
Key Points
- •x86 uses a TSO memory model that orders stores and often avoids explicit barriers, while Arm’s weaker model allows more reordering for performance.
- •Emulating x86 on Arm without TSO risks correctness issues in concurrent code; emulating TSO via barriers reduces performance.
- •Some Arm CPU vendors provide hardware TSO: NVIDIA and Fujitsu CPUs run TSO always; Apple’s CPUs offer TSO as an optional runtime feature.
- •A patch series by Hector Martin proposes prctl() interfaces (PR_GET_MEM_MODEL, PR_SET_MEM_MODEL) to let user space query and request TSO on supported CPUs.
- •Efforts to integrate this user-space controllable TSO support into the Linux kernel have encountered opposition.