1.\" -*- nroff -*- 2.\" 3.\" Copyright (c) 1998 Doug Rabson 4.\" 5.\" All rights reserved. 6.\" 7.\" This program is free software. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 19.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 22.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28.\" 29.\" $FreeBSD$ 30.\" 31.Dd June 16, 1998 32.Dt DEVICE 9 33.Os FreeBSD 34.Sh NAME 35.Nm device 36.Nd an abstract representation of a device 37.Sh SYNOPSIS 38.Dv typedef struct device *device_t; 39.Sh DESCRIPTION 40.Pp 41The device object represents a piece of hardware attached to the 42system such as an expansion card, the bus which that card is plugged 43into, disk drives attached to the expansion card etc. 44The system defines one device, 45.Dv root_bus 46and all other devices are created dynamically during 47autoconfiguration. Normally devices representing toplevel busses in 48the system (ISA, PCI etc.) will be attached directly to 49.Dv root_bus 50and other devices will be added as children of their relevant bus. 51.Pp 52The devices in a system form a tree. All devices except 53.Dv root_bus 54have a parent (see 55.Xr device_get_parent 9 ). 56In addition, any device can have children attached to it (see 57.Xr device_add_child 9 , 58.Xr device_add_child_ordered 9 , 59.Xr device_find_child 9 , 60.Xr device_get_children 9 , 61and 62.Xr device_delete_child 9 ). 63.Pp 64A device which has been successfully been probed and attached to the 65system will also have a driver (see 66.Xr device_get_driver 9 67and 68.Xr driver 9 ) 69and a devclass (see 70.Xr device_get_devclass 9 71and 72.Xr devclass 9 ). 73Various other attributes of the device include a unit number (see 74.Xr device_get_unit 9 ), 75verbose description (normally supplied by the driver, see 76.Xr device_set_desc 9 77and 78.Xr device_get_desc 9 ), 79a set of bus-specific variables (see 80.Xr device_get_ivars 9 ) 81and a set of driver-specific variables (see 82.Xr device_get_softc 9 ). 83.Pp 84Devices can be in one of several states: 85.Bl -tag -width DS_NOTPRESENT 86.It Ar DS_NOTPRESENT 87the device has not been probed for existence or the probe failed 88.It Ar DS_ALIVE 89the device probe succeeded but not yet attached 90.It Ar DS_ATTACHED 91the device has been successfully attached 92.It Ar DS_BUSY 93the device is currently open 94.El 95.Pp 96The current state of the device can be determined by calling 97.Xr device_get_state 9 . 98.Sh SEE ALSO 99.Xr devclass 9 , 100.Xr driver 9 101.Sh AUTHORS 102This man page was written by 103.An Doug Rabson . 104