xref: /freebsd/share/man/man9/DECLARE_MODULE.9 (revision a3557ef0)
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29.\" $FreeBSD$
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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.
72This allows locks and other synchronization primitives
73to be inlined safely.
74.Pp
75The arguments are:
76.Bl -tag -width indent
77.It Fa name
78The module name, which will be used in the
79.Fn SYSINIT
80call to identify the module.
81.It Fa data
82A
83.Vt moduledata_t
84structure, which contains two main items, the official name of the
85module name, which will be used in the
86.Vt module_t
87structure and a pointer to the event handler function of type
88.Vt modeventhand_t .
89.It Fa sub
90An argument directed to the
91.Fn SYSINIT
92macro.
93Valid values for this are contained in the
94.Vt sysinit_sub_id
95enumeration
96(see
97.In sys/kernel.h )
98and specify the type of system startup interfaces.
99The
100.Xr DRIVER_MODULE 9
101macro uses a value of
102.Dv SI_SUB_DRIVERS
103here for example, since these modules contain a driver for a device.
104For kernel modules that are loaded at runtime, a value of
105.Dv SI_SUB_EXEC
106is common.
107.It Fa order
108An argument for
109.Fn SYSINIT .
110It represents the KLDs order of initialization within the subsystem.
111Valid values are defined in the
112.Vt sysinit_elem_order
113enumeration
114.Pq In sys/kernel.h .
115.El
116.Sh SEE ALSO
117.Xr DEV_MODULE 9 ,
118.Xr DRIVER_MODULE 9 ,
119.Xr module 9 ,
120.Xr SYSCALL_MODULE 9
121.Pp
122.Pa /usr/include/sys/kernel.h ,
123.Pa /usr/share/examples/kld
124.Sh AUTHORS
125.An -nosplit
126This manual page was written by
127.An Alexander Langer Aq Mt alex@FreeBSD.org ,
128inspired by the KLD Facility Programming Tutorial by
129.An Andrew Reiter Aq Mt arr@watson.org .
130