190 lines
5.7 KiB
Groff
190 lines
5.7 KiB
Groff
.\" $NetBSD: wdogctl.8,v 1.24 2011/08/11 08:00:05 mbalmer Exp $
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.\"
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.\" Copyright (c) 2000 Zembu Labs, Inc.
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.\" All rights reserved.
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.\"
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.\" Author: Jason R. Thorpe <thorpej@zembu.com>
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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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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by Zembu Labs, Inc.
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.\" 4. Neither the name of Zembu Labs nor the names of its employees may
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.\" be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY ZEMBU LABS, INC. ``AS IS'' AND ANY EXPRESS
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.\" OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WAR-
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.\" RANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DIS-
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.\" CLAIMED. IN NO EVENT SHALL ZEMBU LABS BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd August 11, 2011
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.Dt WDOGCTL 8
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.Os
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.Sh NAME
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.Nm wdogctl
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.Nd Watchdog timer control utility
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.Sh SYNOPSIS
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.Nm
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.Nm
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.Fl d
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.Nm
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.Fl e
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.Op Fl A
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.Op Fl p Ar seconds
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.Ar timer
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.Nm
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.Fl k
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.Op Fl A
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.Op Fl p Ar seconds
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.Ar timer
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.Nm
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.Fl t
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.Nm
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.Fl u
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.Op Fl A
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.Op Fl p Ar seconds
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.Ar timer
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.Nm
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.Fl x
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.Op Fl A
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.Op Fl p Ar seconds
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.Ar timer
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.Sh DESCRIPTION
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.Nm
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is used to manipulate watchdog timers.
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Watchdog timers provide a means of ensuring that a system
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continues to make progress.
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This is accomplished by use of a timer, provided by either hardware or
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software; when the timer expires, the watchdog resets the system.
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In this case of a hardware watchdog timer, this is accomplished by
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asserting the system's hardware reset signal.
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In the case of a software watchdog timer,
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this is accomplished by calling the kernel's normal reboot path.
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In order to prevent the system from rebooting,
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something must refresh the timer to prevent it from expiring.
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.Pp
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The
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.Nx
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kernel provides three basic modes in which watchdog timers may
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operate: kernel tickle mode, user tickle mode, and external tickle mode.
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In kernel tickle mode, a timer in the kernel refreshes the watchdog timer.
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In user tickle mode,
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.Nm
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runs in the background and refreshes the watchdog timer.
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In kernel tickle mode, progress of the kernel is ensured.
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In user tickle mode, the ability for user programs to run within a known
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period of time is ensured.
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Note that user tickle mode must be used with caution;
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on a heavily loaded system, the timer may
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expire accidentally, even though user programs may be making
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(very slow) progress.
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A user-mode timer is disarmed (if possible) when the device is closed,
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unless the timer is activated with the
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.Fl x
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option.
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.Pp
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External-mode watchdogs are similar to user-mode watchdogs, except
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that the tickle must be done explicitly by a separate invocation of
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the program with the
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.Fl t
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option.
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.Pp
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In the first two modes, an attempt is made to refresh the watchdog timer
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in one half the timer's configured period.
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That is, if the watchdog timer has a period of 30 seconds, a refresh attempt
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is made every 15 seconds.
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.Pp
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If called without arguments,
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.Nm
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will list the timers available on the system.
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When arming a watchdog timer, the
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.Ar timer
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argument is the name of the timer to arm.
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.Pp
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Only one timer may be armed at a time; if an attempt is made
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to arm a timer when one is already armed, an error message
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will be displayed and no action will be taken.
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.Pp
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The options are as follows:
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.Bl -tag -offset indent -width XpXperiodXX
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.It Fl A
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When arming a timer, this flag indicates that an audible alarm is
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to sound when the watchdog timer expires and resets the system.
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If the selected timer does not support an audible alarm, this
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option will be silently ignored.
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.It Fl d
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This flag disarms the currently active timer.
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Note that not all watchdog timers can be disabled once armed.
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If the selected timer can not be disabled,
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an error message will be displayed and the
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timer will remain armed.
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.It Fl e
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Arm
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.Ar timer
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in external tickle mode.
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.It Fl k
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Arm
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.Ar timer
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in kernel tickle mode.
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.It Fl p Ar period
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When arming a timer, this flag configures the timer period to
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.Ar period
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seconds.
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If the specified period is outside the timer's range,
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an error message will be displayed and no action will be taken.
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.It Fl t
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This flag tickles an external mode timer.
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.It Fl u
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Arm
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.Ar timer
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in user tickle mode.
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.It Fl x
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Arm
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.Ar timer
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in a modified user tickle mode: closing the device will not disarm
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the timer.
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.El
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.Sh FILES
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.Pa /dev/watchdog
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-- the system monitor watchdog timer device
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.Sh SEE ALSO
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.Xr acpiwdrt 4 ,
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.Xr evbarm/iopwdog 4 ,
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.Xr i386/elansc 4 ,
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.Xr i386/gcscpcib 4 ,
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.Xr i386/geodewdog 4 ,
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.Xr ipmi 4 ,
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.Xr itesio 4 ,
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.Xr pcweasel 4 ,
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.Xr pwdog 4 ,
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.Xr swwdog 4 ,
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.Xr x86/ichlpcib 4
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.Sh HISTORY
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The
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.Nm
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command first appeared in
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.Nx 1.6 .
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.Sh AUTHORS
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The
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.Nm
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command and the
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.Nx
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watchdog timer framework were written by
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.An Jason R. Thorpe
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.Aq thorpej@zembu.com ,
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and contributed by Zembu Labs, Inc.
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