NAME

       device — an abstract representation of a device

SYNOPSIS

       typedef struct device *device_t;

DESCRIPTION

       The  device  object  represents a piece of hardware attached to the system such as an expansion card, the
       bus which that card is plugged into, disk drives attached to the expansion card etc.  The system  defines
       one  device,  root_bus  and all other devices are created dynamically during autoconfiguration.  Normally
       devices representing top-level buses in the system (ISA, PCI etc.) will be attached directly to  root_bus
       and other devices will be added as children of their relevant bus.

       The   devices   in   a   system   form   a  tree.   All  devices  except  root_bus  have  a  parent  (see
       device_get_parent(9)).   In  addition,   any   device   can   have   children   attached   to   it   (see
       device_add_child(9),   device_add_child_ordered(9),   device_find_child(9),  device_get_children(9),  and
       device_delete_child(9)).

       A device which has been successfully probed and attached to the system  will  also  have  a  driver  (see
       device_get_driver(9) and driver(9)) and a devclass (see device_get_devclass(9) and devclass(9)).  Various
       other  attributes  of  the  device  include  a  unit number (see device_get_unit(9)), verbose description
       (normally supplied by the driver, see device_set_desc(9) and device_get_desc(9)), a set  of  bus-specific
       variables (see device_get_ivars(9)) and a set of driver-specific variables (see device_get_softc(9)).

       Devices can be in one of several states:

       DS_NOTPRESENT  the device has not been probed for existence or the probe failed

       DS_ALIVE       the device probe succeeded but not yet attached

       DS_ATTACHED    the device has been successfully attached

       DS_BUSY        the device is currently open

       The current state of the device can be determined by calling device_get_state(9).

SEE ALSO

       devclass(9), driver(9)

AUTHORS

       This manual page was written by Doug Rabson.

Debian                                          January 15, 2017                                       DEVICE(9)