> Why not go all they way and let everything run in ring 0? How would you get memory protection or debugger support then? Or the very-likely use-case of rende

> Why not go all they way and let everything run in ring 0? How would you get memory protection or debugger support then? Or the very-likely use-case of rendering live (i.e. untrusted) web-content in-game? That would require a modern engine like Chromium which in-turn necessitates per-process isolation. Also, no-one wants to have to reboot their entire computer system just because some application code crashed. Even if preemptive scheduling and the MMU works in ring 0 all processes in ring 0 can manipulate the MMU registers, so a misbehaving process can still bring down the entire system. Bad idea. Even dedicated HPC applications need it - remember that the HPC/scientific-computing/batch-job-processing model is the whole reason that operating-systems exist today: they're highly evolved successors to job-control programs (e.g. Chippewa Operating System). So I don't think they'd want to give up all the improvements of the past 50+ years. Ultimately we're just arguing about the principle of how the user who owns the computer should be in ultimate control over the hardware - but unfortunately Apple has demonstrated that principle is unnecessary to make obscene profits and also runs contrary to the realities of running a large secure platform today. We shall see how this ends-up...