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.Dd January 15, 2017 30.Dt DEVICE 9 31.Os 32.Sh NAME 33.Nm device 34.Nd an abstract representation of a device 35.Sh SYNOPSIS 36.Vt typedef struct _device *device_t ; 37.Sh DESCRIPTION 38The device object represents a piece of hardware attached to the 39system such as an expansion card, the bus which that card is plugged 40into, disk drives attached to the expansion card etc. 41The system defines one device, 42.Va root_bus 43and all other devices are created dynamically during 44autoconfiguration. 45Normally devices representing top-level buses in 46the system (ISA, PCI etc.) will be attached directly to 47.Va 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.Va 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 manual page was written by 102.An Doug Rabson . 103