Unloading Drivers

Normally, the system automatically unloads device drivers when they are no longer in use. During development, it might be necessary to use modunload(1M) to unload the driver explicitly. In order for modunload(1M) to be successful, the device driver must not be active; there must be no outstanding references to the device, such as through open(2) or mmap(2).

Use modunload(1M) to unload a driver from the system. modunload takes a module_id that is run time dependent as an argument. It can be found by grepping the output of modinfo for the driver name in question and looking at the first column.

# modunload -i module_id

To unload all currently unloadable modules, specify module ID zero:

# modunload -i 0

In addition to being inactive, the driver must have working detach(9E) and _fini(9E) routines for modunload(1M) to succeed.