Declare a condition variable of type kcondvar_t for each condition. Usually, the condition variables are declared in the driver's soft-state structure. Use cv_init(9F) to initialize each condition variable. Similar to mutexes, condition variables are usually initialized at attach(9E) time. A typical example of initializing a condition variable is:
cv_init(&xsp->cv, NULL, CV_DRIVER, NULL);
For a more complete example of condition variable initialization, see Chapter 6, Driver Autoconfiguration.