xref: /freebsd/share/man/man9/DECLARE_MODULE.9 (revision 190cef3d52236565eb22e18b33e9e865ec634aa3)
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29.\" $FreeBSD$
30.\"
31.Dd February 13, 2018
32.Dt DECLARE_MODULE 9
33.Os
34.Sh NAME
35.Nm DECLARE_MODULE
36.Nd kernel module declaration macro
37.Sh SYNOPSIS
38.In sys/param.h
39.In sys/kernel.h
40.In sys/module.h
41.Fn DECLARE_MODULE "name" "moduledata_t data" "sub" "order"
42.Fn DECLARE_MODULE_TIED "name" "moduledata_t data" "sub" "order"
43.Sh DESCRIPTION
44The
45.Fn DECLARE_MODULE
46macro declares a generic kernel module.
47It is used to register the module with the system, using the
48.Fn SYSINIT
49macro.
50.Fn DECLARE_MODULE
51is usually used within other macros, such as
52.Xr DRIVER_MODULE 9 ,
53.Xr DEV_MODULE 9
54and
55.Xr SYSCALL_MODULE 9 .
56Of course, it can also be called directly, for example in
57order to implement dynamic sysctls.
58.Pp
59A module declared with
60.Fn DECLARE_MODULE_TIED
61will load only if the running kernel version
62(as specified by
63.Dv __FreeBSD_version )
64is identical to that on which it was built.
65This declaration should be used by modules which depend on interfaces beyond
66the stable kernel KBI (such as ABI emulators or hypervisors that rely on
67internal kernel structures).
68.Fn DECLARE_MODULE
69will behave like
70.Fn DECLARE_MODULE_TIED
71when compiled with modules built with the kernel. This allows locks and
72other synchronization primitives to be inlined safely.
73.Pp
74The arguments are:
75.Bl -tag -width indent
76.It Fa name
77The module name, which will be used in the
78.Fn SYSINIT
79call to identify the module.
80.It Fa data
81A
82.Vt moduledata_t
83structure, which contains two main items, the official name of the
84module name, which will be used in the
85.Vt module_t
86structure and a pointer to the event handler function of type
87.Vt modeventhand_t .
88.It Fa sub
89An argument directed to the
90.Fn SYSINIT
91macro.
92Valid values for this are contained in the
93.Vt sysinit_sub_id
94enumeration
95(see
96.In sys/kernel.h )
97and specify the type of system startup interfaces.
98The
99.Xr DRIVER_MODULE 9
100macro uses a value of
101.Dv SI_SUB_DRIVERS
102here for example, since these modules contain a driver for a device.
103For kernel modules that are loaded at runtime, a value of
104.Dv SI_SUB_EXEC
105is common.
106.It Fa order
107An argument for
108.Fn SYSINIT .
109It represents the KLDs order of initialization within the subsystem.
110Valid values are defined in the
111.Vt sysinit_elem_order
112enumeration
113.Pq In sys/kernel.h .
114.El
115.Sh SEE ALSO
116.Xr DEV_MODULE 9 ,
117.Xr DRIVER_MODULE 9 ,
118.Xr module 9 ,
119.Xr SYSCALL_MODULE 9
120.Pp
121.Pa /usr/include/sys/kernel.h ,
122.Pa /usr/share/examples/kld
123.Sh AUTHORS
124.An -nosplit
125This manual page was written by
126.An Alexander Langer Aq Mt alex@FreeBSD.org ,
127inspired by the KLD Facility Programming Tutorial by
128.An Andrew Reiter Aq Mt arr@watson.org .
129