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28 .Dt DECLARE_GEOM_CLASS 9
31 .Nm DECLARE_GEOM_CLASS
32 .Nd "GEOM class declaration macro"
35 .Fn DECLARE_GEOM_CLASS "class" "mod_name"
38 .Fn DECLARE_GEOM_CLASS
39 macro registers a GEOM class in GEOM.
40 A GEOM class itself implements one particular kind of transformation.
41 Typical examples are: MBR disk partition, BSD disklabel and RAID5 classes.
42 .Fn DECLARE_GEOM_CLASS
43 can be used both for compiled in and loaded as
45 modules GEOM classes and it is the only official way for class registration.
48 .Fn DECLARE_GEOM_CLASS
50 .Bl -inset -offset indent
54 structure which describes a GEOM class.
56 is a kernel module name (not a class name!).
61 contains data describing the class.
63 .Bl -inset -offset indent
64 .It Vt "const char *" Va name
66 .It Vt "g_taste_t *" Va taste
67 Pointer to function used for taste event handling.
70 it is called in three situations:
71 .Bl -dash -offset indent -compact
73 On class activation, all existing providers are offered for tasting.
75 When new provider is created it is offered for tasting.
77 After last write access to a provider is closed it is offered for retasting
78 (on first write open event
82 .It Vt "g_config_t *" Va config
83 This field is not used anymore, its functionality was replaced by the
86 .It Vt "g_ctl_req_t *" Va ctlreq
87 Pointer to function used for handling events from userland applications.
88 .It Vt "g_init_t *" Va init
89 Pointer to function which is called right after class registration.
90 .It Vt "g_fini_t *" Va fini
91 Pointer to function which is called right before class deregistration.
92 .It Vt "g_ctl_destroy_geom_t *" Va destroy_geom
93 Pointer to a function which is called for every geom on class unload.
94 If this field is not set, the class can not be unloaded.
99 is required, the rest is optional.
101 .Sh RESTRICTIONS/CONDITIONS
104 initialization one must use C99 initialization (just like in the example below).
107 Example class declaration.
108 .Bd -literal -offset indent
110 g_example_taste(struct g_class *mp, struct g_provider *pp,
119 g_example_ctlreq(struct gctl_req *req, struct g_class *cp,
127 g_example_destroy_geom(struct gctl_req *req, struct g_class *cp,
137 g_example_init(struct g_class *mp)
144 g_example_fini(struct g_class *mp)
150 struct g_class example_class = {
152 .taste = g_example_taste,
153 .ctlreq = g_example_ctlreq,
154 .init = g_example_init,
155 .fini = g_example_fini,
156 .destroy_geom = g_example_destroy_geom
159 DECLARE_GEOM_CLASS(example_class, g_example);
170 .Xr g_provider_by_name 9 ,
174 This manual page was written by
175 .An Pawel Jakub Dawidek Aq pjd@FreeBSD.org .