ARM-ContexM3/4 groups of priority and sub-priority preemption rules, arm-contexm3 Preemption

ARM-ContexM3/4 groups of priority and sub-priority preemption rules, arm-contexm3 Preemption

When multiple interrupt sources have the same preemptible priority, the subpriority is the same or not. If an interrupt is already in the service, no other interrupt source can interrupt it; only an interruption with a higher preemptible priority can interrupt the interruption with a lower preemptible priority.

That is to say,

When the Group priority is different, the high priority can seize the low priority process.

When the Group priority is the same, the sub-priority cannot be preemptible.