> on nommu, you don't have any application isolation
That isn't necessarily the case. You can have memory protection without a MMU - for instance, most ARM Cortex-M parts have a MPU which can be used to restrict a thread's access to memory ranges or to hardware. What it doesn't get you is memory remapping, which is necessary for features like virtual memory.
Yeah, nommu absolutely doesn't imply zero memory isolation. I have a kernel port to an architecture with a nonstandard way of doing memory isolation and the existing nommu infrastructure is the only reason it can exist.
That isn't necessarily the case. You can have memory protection without a MMU - for instance, most ARM Cortex-M parts have a MPU which can be used to restrict a thread's access to memory ranges or to hardware. What it doesn't get you is memory remapping, which is necessary for features like virtual memory.