DECLARE_GEOM_CLASS9
Geom class declaration macro
Usage
#include <geom/geom.h>
DECLARE_GEOM_CLASS(class, mod_name);
Overview
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);
Releases
52 releases since FreeBSD 5.3-RELEASE; the text changed 35 times.