man pages section 9: DDI and DKI Kernel Functions

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Updated: July 2014



ddi_add_event_handler - add an NDI event service callback handler


#include <sys/dditypes.h>
#include <sys/sunddi.h>

int ddi_add_event_handler(dev_info_t *dip, ddi_eventcookie_t cookie,
     void (*handler)(dev_info_t *, ddi_eventcookie_t, void *, void *),
     void *arg, ddi_registration_id_t *id);

Interface Level

Solaris DDI specific (Solaris DDI).


dev_info_t *dip

Device node registering the callback.

ddi_eventcookie_t cookie

Cookie returned from call to ddi_get_eventcookie(9F).

void (*handler)(dev_info_t *, ddi_eventcookie_t, void *, void *)

Callback handler responsible for handling an NDI event service notification.

void *arg

Pointer to opaque data supplied by the caller. Typically, this would be a pointer to the driver's softstate structure.

ddi_registration_id_t *id

Pointer to registration ID where a unique registration id will be returned. Registration ID must be saved and used when calling ddi_remove_event_handler(9F) to unregister a callback.


The ddi_add_event_handler() function adds a callback handler to be invoked in the face of the event specifed by cookie. The process of adding a callback handler is also known as subscribing to an event. Upon successful subscription, the handler will be invoked by the system when the event occurs. The handler can be unregistered by using ddi_remove_event_handler(9F).

An instance of a driver can register multiple handlers for an event or a single handler for multiple events. Callback order is not defined and should assumed to be random.

The routine handler will be invoked with the following arguments:

dev_info_t *dip

Device node requesting the notification.

ddi_eventcookie_t cookie

Structure describing event that occurred.

void *arg

Opaque data pointer provided, by the driver, during callback registration.

void *impl_data

Pointer to event specific data defined by the framework which invokes the callback function.

Return Values


Callback handler registered successfully.


Failed to register callback handler. Possible reasons include lack of resources or a bad cookie.


The ddi_add_event_handler() and handler() function can be called from user and kernel contexts only.


See attributes(5) for a description of the following attributes:

Stability Level

See also

attributes(5), ddi_get_eventcookie(9F), ddi_remove_event_handler(9F)

Writing Device Drivers for Oracle Solaris 11.2


Drivers must remove all registered callback handlers for a device instance by calling ddi_remove_event_handler(9F) before detach completes.