DECLARE_MODULE
—
kernel module declaration macro
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/module.h>
DECLARE_MODULE
(name,
moduledata_t data,
sub,
order);
DECLARE_MODULE_TIED
(name,
moduledata_t data,
sub,
order);
The DECLARE_MODULE
() macro declares a generic kernel
module. It is used to register the module with the system, using the
SYSINIT
() macro.
DECLARE_MODULE
() is usually used within other macros,
such as
DRIVER_MODULE(9),
DEV_MODULE(9)
and
SYSCALL_MODULE(9).
Of course, it can also be called directly, for example in order to implement
dynamic sysctls.
A module declared with
DECLARE_MODULE_TIED
() will load only if the running
kernel version (as specified by __FreeBSD_version
)
is identical to that on which it was built. This declaration should be used
by modules which depend on interfaces beyond the stable kernel KBI (such as
ABI emulators or hypervisors that rely on internal kernel structures).
DECLARE_MODULE
() will behave like
DECLARE_MODULE_TIED
() when compiled with modules
built with the kernel. This allows locks and other synchronization
primitives to be inlined safely.
The arguments are:
- name
- The module name, which will be used in the
SYSINIT
() call to identify the module.
- data
- A moduledata_t structure, which contains two main
items, the official name of the module name, which will be used in the
module_t structure and a pointer to the event
handler function of type modeventhand_t.
- sub
- An argument directed to the
SYSINIT
() macro. Valid
values for this are contained in the sysinit_sub_id
enumeration (see
<sys/kernel.h>
) and
specify the type of system startup interfaces. The
DRIVER_MODULE(9)
macro uses a value of SI_SUB_DRIVERS
here for
example, since these modules contain a driver for a device. For kernel
modules that are loaded at runtime, a value of
SI_SUB_EXEC
is common.
- order
- An argument for
SYSINIT
(). It represents the KLDs
order of initialization within the subsystem. Valid values are defined in
the sysinit_elem_order enumeration
(<sys/kernel.h>
).
This manual page was written by Alexander Langer
<alex@FreeBSD.org>,
inspired by the KLD Facility Programming Tutorial by Andrew
Reiter
<arr@watson.org>.