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$FreeBSD: head/share/man/man9/DECLARE_GEOM_CLASS.9 235371 2012-05-12 20:41:40Z gjb $
.Dd August 13, 2007 .Dt DECLARE_GEOM_CLASS 9 .Os .Sh NAME .Nm DECLARE_GEOM_CLASS .Nd "GEOM class declaration macro" .Sh SYNOPSIS n geom/geom.h .Fn DECLARE_GEOM_CLASS "class" "mod_name" .Sh DESCRIPTION The .Fn DECLARE_GEOM_CLASS macro registers a GEOM class in GEOM. A GEOM class itself implements one particular kind of transformation. Typical examples are: MBR disk partition, x disklabel and RAID5 classes. .Fn DECLARE_GEOM_CLASS can be used both for compiled in and loaded as .Xr kld 4 modules GEOM classes and it is the only official way for class registration.
p The arguments to .Fn DECLARE_GEOM_CLASS are: l -tag -offset indent -width Fa t Fa class The .Vt g_class structure which describes a GEOM class. t Fa mod_name A kernel module name (not a class name!). .El
p Structure .Vt g_class contains data describing the class. They are: l -tag -offset indent -width indent t Vt "const char *" Va name Class name. t Vt "g_taste_t *" Va taste Pointer to function used for taste event handling. If it is
f non- Dv NULL it is called in three situations:
p l -dash -compact t On class activation, all existing providers are offered for tasting. t When new provider is created it is offered for tasting. t After last write access to a provider is closed it is offered for retasting (on first write open event .Dq spoil was sent). .El t Vt "g_config_t *" Va config This field is not used anymore, its functionality was replaced by the .Va ctlreq field. t Vt "g_ctl_req_t *" Va ctlreq Pointer to function used for handling events from userland applications. t Vt "g_init_t *" Va init Pointer to function which is called right after class registration. t Vt "g_fini_t *" Va fini Pointer to function which is called right before class deregistration. t Vt "g_ctl_destroy_geom_t *" Va destroy_geom Pointer to a function which is called for every geom on class unload. If this field is not set, the class can not be unloaded. .El
p Only a .Fa name field is required; the rest are optional. .Sh RESTRICTIONS/CONDITIONS The fields of .Vt g_class should always be initialized using C99-style field naming (see the initialization of .Va example_class below). .Sh EXAMPLES Example class declaration. d -literal -offset indent static struct g_geom * g_example_taste(struct g_class *mp, struct g_provider *pp, int flags __unused) { g_topology_assert(); [...] } static void g_example_ctlreq(struct gctl_req *req, struct g_class *cp, char const *verb) { [...] } static int g_example_destroy_geom(struct gctl_req *req, struct g_class *cp, struct g_geom *gp) { g_topology_assert(); [...] } static void g_example_init(struct g_class *mp) { [...] } static void g_example_fini(struct g_class *mp) { [...] } struct g_class example_class = { .name = "EXAMPLE", .taste = g_example_taste, .ctlreq = g_example_ctlreq, .init = g_example_init, .fini = g_example_fini, .destroy_geom = g_example_destroy_geom }; DECLARE_GEOM_CLASS(example_class, g_example); .Ed .Sh SEE ALSO .Xr geom 4 , .Xr g_attach 9 , .Xr g_bio 9 , .Xr g_consumer 9 , .Xr g_data 9 , .Xr g_event 9 , .Xr g_geom 9 , .Xr g_provider 9 , .Xr g_provider_by_name 9 , .Xr g_wither_geom 9 .Sh AUTHORS .An -nosplit This manual page was written by .An Pawel Jakub Dawidek Aq pjd@FreeBSD.org .