---
name: "DRIVER_MODULE"
section: "9freebsd"
platform: "linux"
package: "freebsd-manpages"
version: "12.2-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/DRIVER_MODULE/9freebsd"
---

# DRIVER\_MODULE(9freebsd)

kernel driver declaration macro

## 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*, *devclass\_t devclass*, *modeventhand\_t evh*, *void \*arg*);

**DRIVER\_MODULE\_ORDERED**(*name*, *busname*, *driver\_t driver*, *devclass\_t devclass*, *modeventhand\_t evh*, *void \*arg*, *int order*);

**EARLY\_DRIVER\_MODULE**(*name*, *busname*, *driver\_t driver*, *devclass\_t devclass*, *modeventhand\_t evh*, *void \*arg*, *enum sysinit\_elem\_order order*, *int pass*);

**EARLY\_DRIVER\_MODULE\_ORDERED**(*name*, *busname*, *driver\_t driver*, *devclass\_t devclass*, *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*, *foo\_devclass*, *NULL*, *NULL*);

**DRIVER\_MODULE**(*foo*, *pci*, *foo\_driver*, *foo\_devclass*, *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 *devclass* argument contains the kernel-internal information about the device, which will be used within the kernel driver module.

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

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)](/SYSINIT/9.md) 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)](/device/9.md), [driver(9)](/driver/9.md), [module(9)](/module/9.md), [MODULE\_PNP\_INFO(9)](/MODULE_PNP_INFO/9.md), [SYSINIT(9)](/SYSINIT/9.md)

## AUTHORS

This manual page was written by Alexander Langer ⟨*alex@FreeBSD.org*⟩.