...how closely tied it is to the x86 memory model & the PC in general. Is it, though? Linux has had NOMMU (running without an MMU at all) support since the ear

...how closely tied it is to the x86 memory model & the PC in general. Is it, though? Linux has had NOMMU (running without an MMU at all) support since the early 2000s, and the atomics / barriers are more based on Alpha's memory model than anything else - several of those primitives just compile out to a compiler barrier or nothing at all on x86. Most heavyweight things you don't need in an IoT context can be compiled-out completely - I think probably the major bit of infrastructure you can't is support for multiple user IDs?