DRIVER_MODULE(9)       FreeBSD Kernel Developer's Manual      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, 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, 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)).

     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)

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

FreeBSD 13.1-RELEASE-p6          May 24, 2021          FreeBSD 13.1-RELEASE-p6