123 lines
3.4 KiB
Groff
123 lines
3.4 KiB
Groff
.\" -*- nroff -*-
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.\"
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.\" Copyright (c) 2000 Alexander Langer
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.\"
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.\" All rights reserved.
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.\"
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.\" This program is free software.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd February 12, 2018
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.Dt MODULE 9
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.Os
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.Sh NAME
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.Nm module
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.Nd structure describing a kernel module
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.Sh DESCRIPTION
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Each module in the kernel is described by a
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.Vt module_t
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structure.
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The structure contains the name of the device, a unique ID number,
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a pointer to an event handler function and to an argument,
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which is given to the event handler,
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as well as some kernel internal data.
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.Pp
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The
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.Xr DECLARE_MODULE 9
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macro
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registers the module with the system.
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.Pp
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When the module is loaded, the event handler function is called with
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the
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.Fa what
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argument set to
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.Dv MOD_LOAD .
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.Pp
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On unload it is first called with
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.Fa what
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set to
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.Dv MOD_QUIESCE .
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If the unload was not forced, a non-zero return will prevent the
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unload from happening.
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.Pp
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If the unload continues
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.Fa what
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is set to
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.Dv MOD_UNLOAD .
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If the module returns non-zero to this, the unload will not happen.
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.Pp
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The difference between
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.Dv MOD_QUIESCE
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and
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.Dv MOD_UNLOAD
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is that the module should fail
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.Dv MOD_QUIESCE
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if it is currently in use, whereas
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.Dv MOD_UNLOAD
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should only fail if it is impossible to unload the module, for instance
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because there are memory references to the module which cannot be revoked.
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.Pp
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When the system is shutting down,
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.Fa what
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contains the value of
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.Dv MOD_SHUTDOWN .
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.Pp
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The module should return
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.Er EOPNOTSUPP
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for unsupported and unrecognized values of
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.Fa what .
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.Sh EXAMPLES
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.Bd -literal
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/module.h>
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static int foo_handler(module_t mod, int /*modeventtype_t*/ what,
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void *arg);
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static moduledata_t mod_data= {
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"foo",
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foo_handler,
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NULL
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};
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MODULE_VERSION(foo, 1);
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MODULE_DEPEND(foo, bar, 1, 3, 4);
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DECLARE_MODULE(foo, mod_data, SI_SUB_EXEC, SI_ORDER_ANY);
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.Ed
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.Sh SEE ALSO
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.Xr DECLARE_MODULE 9 ,
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.Xr DEV_MODULE 9 ,
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.Xr DRIVER_MODULE 9 ,
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.Xr MODULE_DEPEND 9 ,
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.Xr MODULE_PNP_INFO 9 ,
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.Xr MODULE_VERSION 9 ,
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.Xr SYSCALL_MODULE 9
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.Pp
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.Pa /usr/share/examples/kld
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.Sh AUTHORS
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This manual page was written by
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.An Alexander Langer Aq Mt alex@FreeBSD.org .
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