199 lines
6.0 KiB
Groff
199 lines
6.0 KiB
Groff
.\" $NetBSD: deviter.9,v 1.5 2014/03/18 18:20:40 riastradh Exp $
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.\"
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.\" Copyright (c) 2009 David Young <dyoung@NetBSD.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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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.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY David Young ``AS IS'' AND ANY EXPRESS
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.\" OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL David Young BE LIABLE FOR ANY
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.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
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.\" GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
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.\" IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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.\" OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
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.\" IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" NetBSD: pmf.9,v 1.12 2009/10/21 16:06:59 snj Exp
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.\"
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.\" Copyright (c) 2007 Jared D. McNeill <jmcneill@invisible.ca>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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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.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd November 4, 2009
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.Dt DEVITER 9
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.Os
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.Sh NAME
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.Nm deviter ,
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.Nm deviter_first ,
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.Nm deviter_init ,
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.Nm deviter_next ,
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.Nm deviter_release
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.Nd machine-independent device iteration API
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.Sh SYNOPSIS
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.In sys/device.h
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.Ft void
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.Fn deviter_init "deviter_t *di" "deviter_flags_t flags"
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.Ft device_t
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.Fn deviter_first "deviter_t *di" "deviter_flags_t flags"
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.Ft device_t
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.Fn deviter_next "deviter_t *di"
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.Ft void
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.Fn deviter_release "deviter_t *di"
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.Sh DESCRIPTION
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The machine-independent
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.Nm
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API lets interrupt handlers running at any priority level and kernel
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threads iterate over the devices attached to the kernel.
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Using
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.Nm ,
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it is safe for an interrupt handler or a thread to iterate over
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devices attached to the kernel while another thread attaches or
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detaches the devices.
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.Sh DATA TYPES
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Kernel subsystems using
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.Nm
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may make use of the following data types:
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.Bl -tag -width compact
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.It Fa deviter_flags_t
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The kernel can iterate over devices for different purposes and in
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different orders.
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The following flags affect device iteration:
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.Bl -item -compact -offset indent
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.It
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.Dv DEVITER_F_RW
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.It
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.Dv DEVITER_F_SHUTDOWN
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.It
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.Dv DEVITER_F_LEAVES_FIRST
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.It
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.Dv DEVITER_F_ROOT_FIRST
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.El
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.It Fa deviter_t
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This is a device iteration
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.Dq cursor
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or
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.Dq iterator .
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It holds iteration state such as the next device to visit.
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.El
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.Sh FUNCTIONS
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.Bl -tag -width compact
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.It Fn deviter_init "di" "flags"
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Initialize the device iterator,
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.Fa di .
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Set bits in
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.Fa flags
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to affect the order of iteration.
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Set
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.Dv DEVITER_F_LEAVES_FIRST
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to visit each device only after visiting its children (visit the
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leaves of the device tree, first).
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Set
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.Dv DEVITER_F_ROOT_FIRST
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to visit each device before visiting its children (visit the root
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of the device tree, first).
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If you set neither
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.Dv DEVITER_F_LEAVES_FIRST
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nor
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.Dv DEVITER_F_ROOT_FIRST ,
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.Nm
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returns devices in an arbitrary order.
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.Pp
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Set
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.Dv DEVITER_F_RW
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if your purpose for iterating over devices is to modify the device
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tree by attaching or detaching devices.
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Set
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.Dv DEVITER_F_SHUTDOWN
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if your purpose for iterating over devices is to detach all of
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the devices during system shutdown.
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.Dv DEVITER_F_SHUTDOWN
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implies
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.Dv DEVITER_F_RW .
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.It Fn deviter_next "di"
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Advance the iterator
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.Fa di
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to the next device.
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.Fn deviter_next
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returns the current device or
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.Dv NULL
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if there are no more devices.
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.Fn deviter_next
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is undefined if
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.Fa di
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has not been initialized using
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.Fn deviter_init
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or
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.Fn deviter_first .
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.It Fn deviter_first "di" "flags"
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Initialize the iterator
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.Fa di
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with
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.Fa flags .
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Return the first device according to the ordering
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indicated by
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.Fa flags
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and advance
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.Fa di
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to the second device, or
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return
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.Dv NULL
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if there are no devices.
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This is equivalent to calling
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.Fn deviter_init "di" "flags"
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and then
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.Fn deviter_next "di" .
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.It Fn deviter_release "di"
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Release all resources held by the iterator
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.Fa di .
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Every iterator that is initialized with
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.Fn deviter_first
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or
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.Fn deviter_init
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MUST be released.
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.El
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.Sh CODE REFERENCES
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Device iteration is implemented within the files
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.Pa sys/sys/device.h
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and
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.Pa sys/kern/subr_autoconf.c .
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.Sh SEE ALSO
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.Xr autoconf 9 ,
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.Xr driver 9
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.Sh HISTORY
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.Nm
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appeared in
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.Nx 5.0 .
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.Sh AUTHORS
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.An David Young Aq Mt dyoung@NetBSD.org
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