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.Dd November 11, 2021 30.Dt MODULE 9 31.Os 32.Sh NAME 33.Nm module 34.Nd structure describing a kernel module 35.Sh DESCRIPTION 36Each module in the kernel is described by a 37.Vt module_t 38structure. 39The structure contains the name of the device, a unique ID number, 40a pointer to an event handler function and to an argument, 41which is given to the event handler, 42as well as some kernel internal data. 43If the event handler function is 44.Dv NULL , 45the module will use a no-operation function handler instead. 46.Pp 47The 48.Xr DECLARE_MODULE 9 49macro 50registers the module with the system. 51.Pp 52When the module is loaded, the event handler function is called with 53the 54.Fa what 55argument set to 56.Dv MOD_LOAD . 57.Pp 58On unload it is first called with 59.Fa what 60set to 61.Dv MOD_QUIESCE . 62If the unload was not forced, a non-zero return will prevent the 63unload from happening. 64.Pp 65If the unload continues 66.Fa what 67is set to 68.Dv MOD_UNLOAD . 69If the module returns non-zero to this, the unload will not happen. 70.Pp 71The difference between 72.Dv MOD_QUIESCE 73and 74.Dv MOD_UNLOAD 75is that the module should fail 76.Dv MOD_QUIESCE 77if it is currently in use, whereas 78.Dv MOD_UNLOAD 79should only fail if it is impossible to unload the module, for instance 80because there are memory references to the module which cannot be revoked. 81.Pp 82When the system is shutting down, 83.Fa what 84contains the value of 85.Dv MOD_SHUTDOWN . 86.Pp 87The module should return 88.Er EOPNOTSUPP 89for unsupported and unrecognized values of 90.Fa what . 91.Sh EXAMPLES 92.Bd -literal 93#include <sys/param.h> 94#include <sys/kernel.h> 95#include <sys/module.h> 96 97static int foo_handler(module_t mod, int /*modeventtype_t*/ what, 98 void *arg); 99 100static moduledata_t mod_data= { 101 "foo", 102 foo_handler, 103 NULL 104}; 105 106MODULE_VERSION(foo, 1); 107MODULE_DEPEND(foo, bar, 1, 3, 4); 108 109DECLARE_MODULE(foo, mod_data, SI_SUB_EXEC, SI_ORDER_ANY); 110.Ed 111.Sh SEE ALSO 112.Xr DECLARE_MODULE 9 , 113.Xr DEV_MODULE 9 , 114.Xr DRIVER_MODULE 9 , 115.Xr MODULE_DEPEND 9 , 116.Xr MODULE_PNP_INFO 9 , 117.Xr MODULE_VERSION 9 , 118.Xr SYSCALL_MODULE 9 119.Pp 120.Pa /usr/share/examples/kld 121.Sh AUTHORS 122This manual page was written by 123.An Alexander Langer Aq Mt alex@FreeBSD.org . 124