EARLY_DRIVER_MODULE_ORDERED (9)

Leading comments

Copyright (c) 2000 Alexander Langer

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(The comments found at the beginning of the groff file "man9/EARLY_DRIVER_MODULE_ORDERED.9freebsd".)

NAME

DRIVER_MODULE DRIVER_MODULE_ORDERED EARLY_DRIVER_MODULE EARLY_DRIVER_MODULE_ORDERED - kernel driver declaration macro

SYNOPSIS

In sys/param.h In sys/kernel.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 Fn EARLY_DRIVER_MODULE name busname driver_t driver devclass_t devclass modeventhand_t evh void *arg enum sysinit_elem_order order int pass Fn 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 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 char or char *

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

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:

Fn DRIVER_MODULE foo isa foo_driver foo_devclass NULL NULL ;

Fn DRIVER_MODULE foo pci foo_driver foo_devclass NULL NULL ;

Fa 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 Fn DRIVER_MODULE .

The Fa devclass argument contains the kernel-internal information about the device, which will be used within the kernel driver module.

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

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

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 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 Fn 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 attach 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 Fa pass argument. Once a driver is registered it is available to attach to devices for all subsequent passes.

The Fn 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), SYSINIT(9)

AUTHORS

This manual page was written by An Alexander Langer Aq alex@FreeBSD.org .