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Manual Pages  — DECLARE_MODULE


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:
  The module name, which will be used in the SYSINIT() call to identify the module.
  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.
  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.
  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>).



/usr/include/sys/kernel.h, /usr/share/examples/kld


This manual page was written by Alexander Langer <Mt alex@FreeBSD.org>, inspired by the KLD Facility Programming Tutorial by Andrew Reiter <Mt arr@watson.org>.

DECLARE_MODULE (9) February 13, 2018

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