ARC_RA_OUTB_DOORBELL
ob_doorbell = arc_read(sc, ARC_RA_OUTB_DOORBELL);
arc_write(sc, ARC_RA_OUTB_DOORBELL, ob_doorbell);
reg = arc_read(sc, ARC_RA_OUTB_DOORBELL);
while ((reg = arc_read(sc, ARC_RA_OUTB_DOORBELL)) == 0)
arc_write(sc, ARC_RA_OUTB_DOORBELL, reg);
reg = arc_read(sc, ARC_RA_OUTB_DOORBELL);
arc_write(sc, ARC_RA_OUTB_DOORBELL, reg);