device_is_alive (9)

Leading comments

Copyright (c) 1998 Doug Rabson

All rights reserved.

This program is free software.

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modification, are permitted provided that the following conditions
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1. Redistributions of source code must retain the above copyright
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   notice, this list of conditions and the following disclaimer in...

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

NAME

device_get_state device_busy device_unbusy device_is_alive device_is_attached - manipulate device state

SYNOPSIS

In sys/param.h In sys/bus.h Ft device_state_t Fn device_get_state device_t dev Ft void Fn device_busy device_t dev Ft void Fn device_unbusy device_t dev Ft int Fn device_is_alive device_t dev Ft int Fn device_is_attached device_t dev

DESCRIPTION

The current state of a device is accessed by calling Fn device_get_state which returns DS_NOTPRESENT DS_ALIVE DS_ATTACHED or DS_BUSY (described in device(9)). To test see if a device was successfully probed, call Fn device_is_alive which simply returns if the state is greater or equal to DS_ALIVE To test see if a device was successfully attached, call Fn device_is_attached which simply returns if the state is greater or equal to DS_ATTACHED

Each device has a busy count which is incremented when Fn device_busy is called and decremented when Fn device_unbusy is called. Both routines return an error if the device state is less than DS_ATTACHED

When Fn device_busy is called on a device in the DS_ATTACHED state, the device changes to the DS_BUSY state. When Fn device_unbusy is called and after decrementing, the busy count for the device is zero, the device changes to the DS_ATTACHED state.

SEE ALSO

device(9)

AUTHORS

This manual page was written by An Doug Rabson .