SIR_PREEMPT
softint_trigger(1 << SIR_PREEMPT);
softint_trigger(1 << SIR_PREEMPT);
softint_trigger(1 << SIR_PREEMPT);
ci->ci_isources[SIR_PREEMPT] = isp;
softint_trigger(1 << SIR_PREEMPT);