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.\" Copyright (c) 2000 Alexander Langer
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.Dd March 1, 2001
.Dt MODULE 9
.Os FreeBSD
.Sh NAME
.Nm module
.Nd structure describing a kernel module
.Sh DESCRIPTION
Each module in the kernel is described by a
.Vt 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.
.Pp
The
.Xr DECLARE_MODULE 9
macro
registers the module with the system.
When the module is loaded, the event handler function is called with
the
.Fa what
argument set to
.Dv MOD_LOAD .
On unload,
.Fa what
is set to
.Dv MOD_UNLOAD .
When the system is shutting down,
.Fa what
contains the value of
.Dv MOD_SHUTDOWN .
.Sh EXAMPLES
.Bd -literal
#include <sys/param.h>
#include <sys/module.h>

modeventhand_t	foo_handler;

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

DECLARE_MODULE(foo, mod_data, SI_SUB_EXEC, SI_ORDER_ANY);

/* from module.h: */
typedef int (*modeventhand_t)(module_t mod, int /*modeventtype_t*/ what,
                              void *arg);
.Ed
.Sh SEE ALSO
.Xr CDEV_MODULE 9 ,
.Xr DECLARE_MODULE 9 ,
.Xr DRIVER_MODULE 9 ,
.Xr MODULE_DEPEND 9 ,
.Xr MODULE_VERSION 9 ,
.Xr SYSCALL_MODULE 9 ,
.Pa /usr/share/examples/kld
.Sh AUTHORS
This man page was written by
.An Alexander Langer Aq alex@FreeBSD.org .