i8253_fire
evtimer_set(&i8253_channel[0].timer, i8253_fire, &i8253_channel[0]);
evtimer_set(&i8253_channel[1].timer, i8253_fire, &i8253_channel[1]);
evtimer_set(&i8253_channel[2].timer, i8253_fire, &i8253_channel[2]);
void i8253_fire(int, short, void *);