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diff --git a/share/man/man4/watchdog.4 b/share/man/man4/watchdog.4 new file mode 100644 index 000000000000..f19f3a60f6ea --- /dev/null +++ b/share/man/man4/watchdog.4 @@ -0,0 +1,146 @@ +.\" Copyright (c) 2004 Poul-Henning Kamp <phk@FreeBSD.org> +.\" Copyright (c) 2003, 2004 Sean M. Kelly <smkelly@FreeBSD.org> +.\" 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. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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. +.\" +.\" $FreeBSD$ +.\" +.Dd June 25, 2003 +.Dt WATCHDOG 4 +.Os +.Sh NAME +.Nm watchdog +.Nd "hardware and software watchdog" +.Sh SYNOPSIS +.In sys/watchdog.h +.Sh DESCRIPTION +The +.Nm +facility is used for controlling hardware and software watchdogs. +.Pp +.Pa /dev/fido +responds to a single +.Xr ioctl 2 +call, +.Dv WDIOCPATPAT . +It takes a single argument which represents a timeout value specified as a +power of two nanoseconds, or-ed with a flag selecting active or passive control +of the watchdog. +.Pp +.Dv WD_ACTIVE +indicates that the +.Nm +will be kept from timing out from userland, for instance by the +.Xr watchdogd 8 +daemon. +.Dv WD_PASSIVE +indicates that the +.Nm +will be kept from timing out from the kernel. +.Pp +The +.Xr ioctl 2 +call will return success if just one of the available +.Xr watchdog 9 +implementations supports setting the timeout to the specified timeout. This +means that at least one watchdog is armed. If the call fails, for instance if +none of +.Xr watchdog 9 +implementations support the timeout length, all watchdogs are disabled and must +be explicitly re-enabled. +.Pp +To disable the watchdogs pass +.Dv WD_TO_NEVER . +If disarming the watchdog(s) failed an error is returned. The watchdog might +still be armed! +.Sh RETURN VALUES +The ioctl returns zero on success and non-zero on failure. +.Bl -tag -width Er +.It Bq Er EOPNOTSUPP +No watchdog present in the kernel (timeout value other than 0). +.It Bq Er EOPNOTSUPP +Watchdog could not be disabled (timeout value of 0). +.It Bq Er EINVALID +Invalid flag combination passed. +.It Bq Er EINVALID +None of the watchdogs supports the requested timeout value. +.El +.Sh EXAMPLES +.Bd -literal -offset indent +#include <paths.h> +#include <sys/watchdog.h> + +#define WDPATH "/dev/" _PATH_WATCHDOG +int wdfd = -1; + +static void +wd_init(void) +{ + wdfd = open(WDPATH, O_RDWR); + if (wdfd == -1) + err(1, WDPATH); +} +static void +wd_reset(u_int timeout) +{ + if (ioctl(wdfd, WDIOCPATPAT, &timeout) == -1) + err(1, "WDIOCPATPAT"); +} + +/* in main() */ +wd_init(); +wd_reset(WD_ACTIVE|WD_TO_8SEC); +/* potential freeze point */ +wd_reset(WD_TO_NEVER); +.Ed +.Pp +Enables a watchdog to recover from a potentially freezing piece of code. +.Pp +.Bd -literal -offset indent +options SW_WATCHDOG +.Ed +.Pp +in your kernel config adds a software watchdog in the kernel, dropping to KDB +or panic-ing when firing. +.Sh SEE ALSO +.Xr watchdogd 8 , +.Xr watchdog 9 +.Sh HISTORY +The +.Nm +code first appeared in +.Fx 5.1 . +.Sh BUGS +The +.Dv WD_PASSIVE +option has not yet been implemented. +.Sh AUTHORS +.An -nosplit +The +.Nm +facility was written by +.An Poul-Henning Kamp Aq phk@FreeBSD.org . +The software watchdog code and this manual page were written by +.An Sean Kelly Aq smkelly@FreeBSD.org . +Some contributions were made by +.An Jeff Roberson Aq jeff@FreeBSD.org . |