Although the kernel may accept a new interrupt signal while handling a previous one, some critical regions exist inside the kernel code where interrupts must be disabled.
尽管内核可以在执行一个中断时,接收一个新的中断信号,内核代码中存在一些临界区域,这里中断必须关闭。
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If high priority interrupts are not disabled during low priority interrupts, users must save the key registers in software during a low priority interrupt.