IST_UNUSABLE
if (intr[num].intr_sharetype == IST_UNUSABLE) {
case IST_UNUSABLE:
if (jensenio_intr_deftype[eirq] == IST_UNUSABLE) {
if (jensenio_intr_deftype[irq] == IST_UNUSABLE) {
IST_UNUSABLE, /* 2: (cascade) */
IST_UNUSABLE, /* 13: not connected */
IST_UNUSABLE);