DRIVER_MODULE(9)

NAME
DRIVER_MODULE, DRIVER_MODULE_ORDERED, EARLY_DRIVER_MODULE, EARLY_DRIVER_MODULE_ORDERED - kernel driver declaration macro

SYNOPSIS
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/bus.h>
#include <sys/module.h>
DRIVER_MODULE(name, busname, driver_t driver, modeventhand_t evh, void *arg);
DRIVER_MODULE_ORDERED(name, busname, driver_t driver, modeventhand_t evh, void *arg, int order);
EARLY_DRIVER_MODULE(name, busname, driver_t driver, modeventhand_t evh, void *arg, int pass);
EARLY_DRIVER_MODULE_ORDERED(name, busname, driver_t driver, modeventhand_t evh, void *arg, enum sysinit_elem_order order, int pass);

DESCRIPTION
The DRIVER_MODULE() macro declares a kernel driver. DRIVER_MODULE() expands to the real driver declaration, where the phrase name is used as the naming prefix for the driver and its functions. Note that it is supplied as plain text, and not a char or char *.

busname is the parent bus of the driver (PCI, ISA, PPBUS and others), e.g. ‘pci’, ‘isa’, or ‘ppbus’.

The identifier used in DRIVER_MODULE() can be different from the driver name. Also, the same driver identifier can exist on different buses, which is a pretty clean way of making front ends for different cards using the same driver on the same or different buses. For example, the following is allowed:

DRIVER_MODULE(foo, isa, foo_driver, NULL, NULL);

DRIVER_MODULE(foo, pci, foo_driver, NULL, NULL);

driver is the driver of type driver_t, which contains the information about the driver and is therefore one of the two most important parts of the call to DRIVER_MODULE().

The evh argument is the event handler which is called when the driver (or module) is loaded or unloaded (see module(9)).

The arg is unused at this time and should be a NULL pointer.

The DRIVER_MODULE_ORDERED() macro allows a driver to be registered in a specific order. This can be useful if a single kernel module contains multiple drivers that are inter-dependent. The order argument should be one of the SYSINIT(9) initialization ordering constants (SI_ORDER_*). The default order for a driver module is SI_ORDER_MIDDLE. Typically a module will specify an order of SI_ORDER_ANY for a single driver to ensure it is registered last.

The EARLY_DRIVER_MODULE() macro allows a driver to be registered for a specific pass level. The boot time probe and attach process makes multiple passes over the device tree. Certain critical drivers that provide basic services needed by other devices are attached during earlier passes. Most drivers are attached in a final general pass. A driver that attaches during an early pass must register for a specific pass level (BUS_PASS_*) via the pass argument. Once a driver is registered it is available to attach to devices for all subsequent passes.

The EARLY_DRIVER_MODULE_ORDERED() macro allows a driver to be registered both in a specific order and for a specific pass level.

SEE ALSO
device(9), driver(9), module(9), MODULE_PNP_INFO(9), SYSINIT(9)

HISTORY
Prior to FreeBSD 14.0, these macros accepted an additional devclass_t argument after driver.

AUTHORS
This manual page was written by Alexander Langer <alex@FreeBSD.org>.