Only doomed on broken hardware. I think that mitigating Spectre and similar attacks via software is a losing battle. Eventually hardware will have to be fixed

Only doomed on broken hardware. I think that mitigating Spectre and similar attacks via software is a losing battle. Eventually hardware will have to be fixed to properly isolate microarchitecture state during speculative execution. Also technically we still don't need separate processes to mitigate spectre, we just need to make sure that microarchitecture state is flushed when changing security domains. This is often accomplished with processes, but it could also just be accomplished by marking system methods in a LispOS as "priviledged" and decorating them to flush the microarchitecture state when called.