Check user requirements for changes in the priority of SOAs.
检查用户对于更改soa优先权的需求。
2
If you've got a group of passengers queuing at a bus stop, then that's your first priority and you're not perhaps looking at the floor to check who's going on and off.
如果你有一堆乘客在车站等车，那么你第一眼不太可能看下地板，看谁将要上下车。
3
If you are in priority drop mode, writing this number to EOI decreases the priority, writing the same value to DI will retire the interrupt (check GICC_CTLR to confirm your mode).