NetBSD/share/man/man4/swwdog.4

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.\" $NetBSD: swwdog.4,v 1.3 2005/01/12 15:16:33 drochner Exp $
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.\" Copyright (c) 2004, 2005 Steven M. Bellovin
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.Dd January 6, 2005
.\" Written by Steven M. Bellovin
.Dt SWWDOG 4
.Os
.Sh NAME
.Nm swwdog
.Nd software watchdog timer
.Sh SYNOPSIS
.Cd "pseudo-device swwdog" Op Ar count
.Sh DESCRIPTION
The
.Nm
driver provides a software watchdog timer that works with
.Xr wdogctl 8 .
If the timer expires, the system reboots unless the variable
.Va swwdog_panic
is non-zero; if it is, the system will panic instead.
.Pp
The default period of
.Nm
is 60 seconds.
.Sh SEE ALSO
.Xr wdogctl 8
.Sh HISTORY
The
.Nm
driver was written by
.An Steven M. Bellovin .
.Sh BUGS
Although more than one
.Nm
timer can be configured, it's a pointless thing to do, since only
one watchdog timer can be active at any given time.
Arguably, this is a bug in the watchdog timer framework.
.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.