90 lines
3.0 KiB
Groff
90 lines
3.0 KiB
Groff
.\" $NetBSD: swwdog.4,v 1.8 2011/06/08 12:19:14 pgoyette Exp $
|
|
.\"
|
|
.\" Copyright (c) 2004, 2005 Steven M. Bellovin
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed by the NetBSD
|
|
.\" Foundation, Inc. and its contributors.
|
|
.\" 4. Neither the name of the author nor the names of its
|
|
.\" contributors may be used to endorse or promote products derived
|
|
.\" from this software without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS
|
|
.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
|
|
.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
|
|
.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
|
|
.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
.\" POSSIBILITY OF SUCH DAMAGE.
|
|
.\"
|
|
.Dd June 8, 2011
|
|
.\" Written by Steven M. Bellovin
|
|
.Dt SWWDOG 4
|
|
.Os
|
|
.Sh NAME
|
|
.Nm swwdog
|
|
.Nd software watchdog timer
|
|
.Sh SYNOPSIS
|
|
.Cd "pseudo-device swwdog"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm
|
|
driver provides a software watchdog timer that works with
|
|
.Xr wdogctl 8 .
|
|
If the timer expires, the system reboots if the boolean variable
|
|
.Va swwdog_reboot
|
|
is
|
|
.Dv true ;
|
|
otherwise, the system will panic.
|
|
.Va swwdog_reboot
|
|
is accessible as a
|
|
.Xr sysctl 8
|
|
variable, hw.swwdog.reboot and defaults to
|
|
.Dv false .
|
|
.Pp
|
|
The default period of
|
|
.Nm
|
|
is 60 seconds.
|
|
.Pp
|
|
As with other watchdog timers, the
|
|
.Nm
|
|
driver prevents a system from suspending when the watchdog is armed.
|
|
.Sh SEE ALSO
|
|
.Xr sysctl 8 ,
|
|
.Xr wdogctl 8
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
driver was written by
|
|
.An Steven M. Bellovin .
|
|
.Sh BUGS
|
|
Only one watchdog timer can be active at any given time.
|
|
(Arguably, this is a bug in the watchdog timer framework.)
|
|
Therefore, only a single instance of the
|
|
.Nm
|
|
device can be created.
|
|
.Pp
|
|
Kernel tickle mode is useless with
|
|
.Nm
|
|
and arguably should be rejected, since both it and
|
|
this driver rely on the same callout mechanism; if one is
|
|
blocked, almost certainly the other is as well.
|
|
.Pp
|
|
The alarm option to
|
|
.Xr wdogctl 8
|
|
isn't implemented.
|