In other words, an FIQ is just a higher priorityinterrupt request, that is prioritized by disabling IRQ and other FIQ handlers during request servicing.
If high priority interrupts are not disabled during low priority interrupts, users must save the key registers in software during a low priorityinterrupt.
如果在响应低优先级中断时高优先级中断使能,用户必须在低优先级中断响应程序中保存那些关键的寄存器值。
3
These changes provide a fully preemptible kernel, threaded interrupt handlers, high-resolution timers, priority inheritance, and robust mutexes.