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)).

     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>.