1.\" -*- nroff -*- 2.\" 3.\" Copyright (c) 2000 Alexander Langer 4.\" 5.\" All rights reserved. 6.\" 7.\" This program is free software. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 19.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 22.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28.\" 29.\" $FreeBSD$ 30.\" 31.Dd February 12, 2018 32.Dt MODULE 9 33.Os 34.Sh NAME 35.Nm module 36.Nd structure describing a kernel module 37.Sh DESCRIPTION 38Each module in the kernel is described by a 39.Vt module_t 40structure. 41The structure contains the name of the device, a unique ID number, 42a pointer to an event handler function and to an argument, 43which is given to the event handler, 44as well as some kernel internal data. 45.Pp 46The 47.Xr DECLARE_MODULE 9 48macro 49registers the module with the system. 50.Pp 51When the module is loaded, the event handler function is called with 52the 53.Fa what 54argument set to 55.Dv MOD_LOAD . 56.Pp 57On unload it is first called with 58.Fa what 59set to 60.Dv MOD_QUIESCE . 61If the unload was not forced, a non-zero return will prevent the 62unload from happening. 63.Pp 64If the unload continues 65.Fa what 66is set to 67.Dv MOD_UNLOAD . 68If the module returns non-zero to this, the unload will not happen. 69.Pp 70The difference between 71.Dv MOD_QUIESCE 72and 73.Dv MOD_UNLOAD 74is that the module should fail 75.Dv MOD_QUIESCE 76if it is currently in use, whereas 77.Dv MOD_UNLOAD 78should only fail if it is impossible to unload the module, for instance 79because there are memory references to the module which cannot be revoked. 80.Pp 81When the system is shutting down, 82.Fa what 83contains the value of 84.Dv MOD_SHUTDOWN . 85.Pp 86The module should return 87.Er EOPNOTSUPP 88for unsupported and unrecognized values of 89.Fa what . 90.Sh EXAMPLES 91.Bd -literal 92#include <sys/param.h> 93#include <sys/kernel.h> 94#include <sys/module.h> 95 96static int foo_handler(module_t mod, int /*modeventtype_t*/ what, 97 void *arg); 98 99static moduledata_t mod_data= { 100 "foo", 101 foo_handler, 102 NULL 103}; 104 105MODULE_VERSION(foo, 1); 106MODULE_DEPEND(foo, bar, 1, 3, 4); 107 108DECLARE_MODULE(foo, mod_data, SI_SUB_EXEC, SI_ORDER_ANY); 109.Ed 110.Sh SEE ALSO 111.Xr DECLARE_MODULE 9 , 112.Xr DEV_MODULE 9 , 113.Xr DRIVER_MODULE 9 , 114.Xr MODULE_DEPEND 9 , 115.Xr MODULE_PNP_INFO 9 , 116.Xr MODULE_VERSION 9 , 117.Xr SYSCALL_MODULE 9 118.Pp 119.Pa /usr/share/examples/kld 120.Sh AUTHORS 121This manual page was written by 122.An Alexander Langer Aq Mt alex@FreeBSD.org . 123