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MODULE(9)	       FreeBSD Kernel Developer's Manual	     MODULE(9)

NAME
     module -- structure describing a kernel module

DESCRIPTION
     Each module in the	kernel is described by a module_t structure.  The
     structure contains	the name of the	device,	a unique ID number, a pointer
     to	an event handler function and to an argument, which is given to	the
     event handler, as well as some kernel internal data.

     The DECLARE_MODULE(9) macro registers the module with the system.

     When the module is	loaded,	the event handler function is called with the
     what argument set to MOD_LOAD.

     On	unload it is first called with what set	to MOD_QUIESCE.	 If the	unload
     was not forced, a non-zero	return will prevent the	unload from happening.

     If	the unload continues what is set to MOD_UNLOAD.	 If the	module returns
     non-zero to this, the unload will not happen.

     The difference between MOD_QUIESCE	and MOD_UNLOAD is that the module
     should fail MOD_QUIESCE if	it is currently	in use,	whereas	MOD_UNLOAD
     should only fail if it is impossible to unload the	module,	for instance
     because there are memory references to the	module which cannot be
     revoked.

     When the system is	shutting down, what contains the value of
     MOD_SHUTDOWN.

     The module	should return EOPNOTSUPP for unrecognized values of what.

EXAMPLES
     #include <sys/param.h>
     #include <sys/kernel.h>
     #include <sys/module.h>

     static int	foo_handler(module_t mod, int /*modeventtype_t*/ what,
			    void *arg);

     static moduledata_t mod_data= {
	     "foo",
	     foo_handler,
	     0
     };

     MODULE_VERSION(foo, 1);
     MODULE_DEPEND(foo,	bar, 1,	3, 4);

     DECLARE_MODULE(foo, mod_data, SI_SUB_EXEC,	SI_ORDER_ANY);

SEE ALSO
     DECLARE_MODULE(9),	DEV_MODULE(9), DRIVER_MODULE(9), MODULE_DEPEND(9),
     MODULE_VERSION(9),	SYSCALL_MODULE(9)

     /usr/share/examples/kld

AUTHORS
     This manual page was written by Alexander Langer <alex@FreeBSD.org>.

FreeBSD	9.3			 March 1, 2001			   FreeBSD 9.3

NAME | DESCRIPTION | EXAMPLES | SEE ALSO | AUTHORS

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<http://www.freebsd.org/cgi/man.cgi?query=module&sektion=9&manpath=FreeBSD+6.1-RELEASE>

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