>in Linux parlance, Plan 9 is a "preemptible" kernel. Interrupt handlers can be >interrupted, so to speak.
interrupt handlers are not normally interruptible during the interrupt processing, but rather at the end (eg, when anyhigher, anyready or preempted is called). processes running at non-interrupt level in the kernel can be interrupted unless they are splhi or using ilock. >Except for the clock interrupt handler that's only because the clock interrupt handler directly or indirectly (eg, via sched) calls spllo, and other trap or interrupt handlers could do that.
