SYNOPSIS

In geom/geom.h Fn DECLARE_GEOM_CLASS class mod_name

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, BSD disklabel and RAID5 classes. Fn 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 Fn DECLARE_GEOM_CLASS are:

Fa class

The Vt g_class structure which describes a GEOM class.

Fa 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 Fa 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 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);

AUTHORS

An -nosplit This manual page was written by An Pawel Jakub Dawidek Aq [email protected] .