1.\" Copyright (c) 1998 Doug Rabson 2.\" 3.\" All rights reserved. 4.\" 5.\" This program is free software. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 17.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 20.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26.\" 27.\" $FreeBSD: src/share/man/man9/device.9,v 1.7.2.4 2001/08/17 13:08:54 ru Exp $ 28.\" $DragonFly: src/share/man/man9/device.9,v 1.4 2004/06/01 11:36:53 hmp Exp $ 29.\" 30.Dd June 16, 1998 31.Dt DEVICE 9 32.Os 33.Sh NAME 34.Nm device 35.Nd an abstract representation of a device 36.Sh SYNOPSIS 37.Vt typedef struct device *device_t ; 38.Sh DESCRIPTION 39The device object represents a piece of hardware attached to the 40system such as an expansion card, the bus which that card is plugged 41into, disk drives attached to the expansion card etc. 42The system defines one device, 43.Dv root_bus 44and all other devices are created dynamically during 45autoconfiguration. Normally devices representing toplevel busses in 46the system (ISA, PCI etc.) will be attached directly to 47.Dv root_bus 48and other devices will be added as children of their relevant bus. 49.Pp 50The devices in a system form a tree. 51All devices except 52.Dv root_bus 53have a parent (see 54.Xr device_get_parent 9 ) . 55In addition, any device can have children attached to it (see 56.Xr device_add_child 9 , 57.Xr device_add_child_ordered 9 , 58.Xr device_find_child 9 , 59.Xr device_get_children 9 , 60and 61.Xr device_delete_child 9 ) . 62.Pp 63A device which has been successfully probed and attached to the 64system will also have a driver (see 65.Xr device_get_driver 9 66and 67.Xr driver 9 ) 68and a devclass (see 69.Xr device_get_devclass 9 70and 71.Xr devclass 9 ) . 72Various other attributes of the device include a unit number (see 73.Xr device_get_unit 9 ) , 74verbose description (normally supplied by the driver, see 75.Xr device_set_desc 9 76and 77.Xr device_get_desc 9 ) , 78a set of bus-specific variables (see 79.Xr device_get_ivars 9 ) 80and a set of driver-specific variables (see 81.Xr device_get_softc 9 ) . 82.Pp 83Devices can be in one of several states: 84.Bl -tag -width DS_NOTPRESENT 85.It Dv DS_NOTPRESENT 86the device has not been probed for existence or the probe failed 87.It Dv DS_ALIVE 88the device probe succeeded but not yet attached 89.It Dv DS_ATTACHED 90the device has been successfully attached 91.It Dv DS_BUSY 92the device is currently open 93.El 94.Pp 95The current state of the device can be determined by calling 96.Xr device_get_state 9 . 97.Sh SEE ALSO 98.Xr devclass 9 , 99.Xr driver 9 100.Sh AUTHORS 101This man page was written by 102.An Doug Rabson . 103