apix_get_avail_vector_oncpu
vector = apix_get_avail_vector_oncpu(0, APIX_IPI_MIN, APIX_IPI_MAX);
vector = apix_get_avail_vector_oncpu(tocpu, APIX_AVINTR_MIN,
static int apix_get_avail_vector_oncpu(uint32_t, int, int);