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DECLARE_GEOM_CLASS (9) | Kernel routines | Unix Manual Pages | :man

NAME

DECLARE_GEOM_CLASS - "GEOM class declaration macro"

CONTENTS

Synopsis
Description
Restrictions/conditions
Examples
See Also
Authors

SYNOPSIS


.In geom/geom.h DECLARE_GEOM_CLASS "class" "mod_name"

DESCRIPTION

The 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, BSD disklabel and RAID5 classes. DECLARE_GEOM_CLASS can be used both for compiled in and loaded as kld(4) modules GEOM classes and it is the only official way for class registration.

The arguments to DECLARE_GEOM_CLASS are:

class The
.Vt g_class structure which describes a GEOM class.
mod_name A kernel module name (not a class name!).

Structure
.Vt g_class contains data describing the class. They are:

Vt "const char *" name Class name.
Vt "g_taste_t *" taste Pointer to function used for taste event handling. If it is non- NULL it is called in three situations:

On class activation, all existing providers are offered for tasting.
When new provider is created it is offered for tasting.
After last write access to a provider is closed it is offered for retasting (on first write open event "spoil" was sent).
Vt "g_config_t *" config This field is not used anymore, its functionality was replaced by the ctlreq field.
Vt "g_ctl_req_t *" ctlreq Pointer to function used for handling events from userland applications.
Vt "g_init_t *" init Pointer to function which is called right after class registration.
Vt "g_fini_t *" fini Pointer to function which is called right before class deregistration.
Vt "g_ctl_destroy_geom_t *" 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.

Only a name field is required; the rest are optional.

RESTRICTIONS/CONDITIONS

The fields of
.Vt g_class should always be initialized using C99-style field naming (see the initialization of example_class below).

EXAMPLES

Example class declaration.
static struct 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);

SEE ALSO

geom(4), g_attach(9), g_bio(9), g_consumer(9), g_data(9), g_event(9), g_geom(9), g_provider(9), g_provider_by_name(9), g_wither_geom(9)

AUTHORS


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