The way I understand it is a hard realtime system does not solve that problem but does ensure the process with too much work does not prevent any other process from meeting its obligations. In other words, the failure to meet demand is isolated & prevented from cascading into other tasks.

Of course, if the process that is overloaded is the process responsible for keeping the system from crashing into the Sun, this doesn't quite fix the problem.

Then it would be not an hard real time system.

With non-maskable hardware interrupts?