Go to main content

man pages section 9: DDI and DKI Driver Entry Points

Exit Print View

Updated: July 2017



_fini, _info, _init - loadable module configuration entry points


#include <sys/modctl.h>

int _fini(void)
int _info(struct modinfo *modinfop);
int _init(void)

Interface Level

Solaris DDI specific (Solaris DDI). These entry points are required. You must write them.


_info( )


A pointer to an opaque modinfo structure.


_init() initializes a loadable module. It is called before any other routine in a loadable module. _init() returns the value returned by mod_install(9F). The module may optionally perform some other work before the mod_install(9F) call is performed. If the module has done some setup before the mod_install(9F) function is called, then it should be prepared to undo that setup if mod_install(9F) returns an error.

_info() returns information about a loadable module. _info() returns the value returned by mod_info(9F).

_fini() prepares a loadable module for unloading. It is called when the system wants to unload a module. If the module determines that it can be unloaded, then _fini() returns the value returned by mod_remove(9F). Upon successful return from _fini() no other routine in the module will be called before _init() is called.

Return Values

_init() should return the appropriate error number if there is an error, otherwise it should return the return value from mod_install(9F).

_info() should return the return value from mod_info(9F)

_fini() should return the return value from mod_remove(9F). _fini() is permitted to return EBUSY prior to calling mod_remove(9F) if the driver should not be unloaded. Driver global resources, such as mutexes and calls to ddi_soft_state_fini(9F), should only be destroyed in _fini() after mod_remove() returns successfully.


Example 1 Initializing and Freeing a Mutex

The following example demonstrates how to initialize and free a mutex(9F).

#include <sys/modctl.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>
static struct dev_ops  drv_ops;
 * Module linkage information for the kernel.
static struct modldrv modldrv = {
     &mod_driverops,     /* Type of module.  This one is a driver */
    "Sample Driver",
    &drv_ops       /* driver ops */

static struct modlinkage modlinkage = {

 * Global driver mutex
static kmutex_t   xx_global_mutex;

        int     i;

          * Initialize global mutex before mod_install'ing driver.
          * If mod_install() fails, must clean up mutex initialization
        mutex_init(&xx_global_mutex, NULL,
                MUTEX_DRIVER, (void *)NULL);

        if ((i = mod_install(&modlinkage)) != 0) {

        return (i);
_info(struct modinfo *modinfop)
        return (mod_info(&modlinkage, modinfop));

        int       i;
          * If mod_remove() is successful, we destroy our global mutex
        if ((i = mod_remove(&modlinkage)) == 0) {
        return (i);

See Also

add_drv(1M), mod_info(9F), mod_install(9F), mod_remove(9F), mutex(9F), modldrv(9S), modlinkage(9S), modlstrmod(9S)

Writing Device Drivers for Oracle Solaris 11.3


Do not change the structures referred to by the modlinkage structure after the call to mod_install(), as the system may copy or change them.


Even though the identifiers _fini(), _info(), and _init() appear to be declared as globals, their scope is restricted by the kernel to the module that they are defined in.


On some implementations _info() may be called before _init().