NAME

DECLARE_GEOM_CLASS — GEOM class declaration macro

SYNOPSIS

#include < 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 g_class structure which describes a GEOM class.

mod_name

A kernel module name (not a class name!).

Structure g_class contains data describing the class. They are:

const char * name

Class name.

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).

g_config_t * config

This field is not used anymore, its functionality was replaced by the ctlreq field.

g_ctl_req_t * ctlreq

Pointer to function used for handling events from userland applications.

g_init_t * init

Pointer to function which is called right after class registration.

g_fini_t * fini

Pointer to function which is called right before class deregistration.

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 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);

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

This manual page was written by Pawel Jakub Dawidek <pjd@FreeBSD.org>.