cothread_create
sc->cotd = cothread_create(vkd_io_thread, vkd_io_intr,
sc->cotd_tx = cothread_create(vke_tx_thread, vke_tx_intr, sc, "vke_tx");
sc->cotd_rx = cothread_create(vke_rx_thread, vke_rx_intr, sc, "vke_rx");
cothread_t cothread_create(void (*thr_func)(cothread_t cotd),
vktimer_cotd = cothread_create(vktimer_thread, NULL, NULL, "vktimer");