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.\" $FreeBSD: src/share/man/man9/DRIVER_MODULE.9,v 1.1.2.5 2001/12/17 11:30:18 ru Exp $
.\"
.Dd May 31, 2022
.Dt DRIVER_MODULE 9
.Os
.Sh NAME
.Nm DRIVER_MODULE ,
.Nm DRIVER_MODULE_ORDERED
.Nd kernel driver declaration macro
.Sh SYNOPSIS
.In sys/types.h
.In sys/bus.h
.In sys/module.h
.Fn DRIVER_MODULE name busname "driver_t driver" "devclass_t devclass" "modeventhand_t evh" "void *arg"
.Fn DRIVER_MODULE_ORDERED name busname "driver_t driver" "devclass_t *devclass" "modeventhand_t evh" "void *arg" "int order"
.Sh DESCRIPTION
The
.Fn DRIVER_MODULE
macro declares a kernel driver.
.Fn DRIVER_MODULE
expands to the real driver declaration, where the phrase
.Fa name
is used as the naming prefix for the driver and its functions.
Note that it is supplied as plain text, and not a
.Li char
or
.Li char * .
.Pp
.Fa busname
is the parent bus of the driver (PCI, ISA, PPBUS and others), e.g.\&
.Ql pci ,
.Ql isa ,
or
.Ql ppbus .
.Pp
The identifier used in
.Fn DRIVER_MODULE
can be different from the driver name.
Also, the same driver identifier can exist on different busses,
which is a pretty clean way of making front ends for different cards
using the same driver on the same or different busses.
For example, the following is allowed:
.Pp
.Fn DRIVER_MODULE foo isa foo_driver foo_devclass NULL NULL ;
.Pp
.Fn DRIVER_MODULE foo pci foo_driver foo_devclass NULL NULL ;
.Pp
.Fa driver
is the driver of type
.Li driver_t ,
which contains the information about the driver and is therefore one of the
two most important parts of the call to
.Fn DRIVER_MODULE .
.Pp
The
.Fa devclass
argument contains the kernel-internal information about the device,
which will be used within the kernel driver module.
.Pp
The
.Fa evh
argument is the event handler which is called when the driver (or module)
is loaded or unloaded (see
.Xr module 9 ) .
.Pp
The
.Fa arg
is unused at this time and should be a
.Dv NULL
pointer.
.Pp
The
.Fn 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
.Fa order
argument should be one of the
.Xr SYSINIT 9
initialization ordering constants
.Pq Dv SI_ORDER_* .
The default order for a driver module is
.Dv SI_ORDER_MIDDLE .
Typically a module will specify an order of
.Dv SI_ORDER_ANY
for a single driver to ensure it is registered last.
.Sh SEE ALSO
.Xr device 9 ,
.Xr driver 9 ,
.Xr module 9 ,
.Xr SYSINIT 9
.Sh AUTHORS
This manual page was written by
.An Alexander Langer Aq Mt alex@FreeBSD.org .