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WATCHDOG(4) | Device Drivers Manual | WATCHDOG(4) |
NAME¶
watchdog
—
hardware and software watchdog
SYNOPSIS¶
#include
<sys/watchdog.h>
DESCRIPTION¶
Thewatchdog
facility is used for controlling
hardware and software watchdogs.
The device /dev/fido responds to a single
ioctl(2) call,
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.
WD_ACTIVE
indicates that the
watchdog
will be kept from timing out from
userland, for instance by the watchdogd(8)
daemon. WD_PASSIVE
indicates that the
watchdog
will be kept from timing out from
the kernel.
The ioctl(2) call will return success if just one
of the available 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
watchdog(9) implementations support the timeout
length, all watchdogs are disabled and must be explicitly re-enabled.
To disable the watchdogs pass WD_TO_NEVER
. If
disarming the watchdog(s) failed an error is returned. The watchdog might
still be armed!
RETURN VALUES¶
The ioctl returns zero on success and non-zero on failure.- [
EOPNOTSUPP
] - No watchdog present in the kernel or none of the watchdogs supports the requested timeout value (timeout value other than 0).
- [
EOPNOTSUPP
] - Watchdog could not be disabled (timeout value of 0).
- [
EINVAL
] - Invalid flag combination passed.
EXAMPLES¶
#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);
options SW_WATCHDOG
SEE ALSO¶
watchdogd(8), watchdog(9)HISTORY¶
Thewatchdog
code first appeared in
FreeBSD 5.1.
AUTHORS¶
Thewatchdog
facility was written by
Poul-Henning Kamp
⟨phk@FreeBSD.org⟩. The software watchdog code and this manual
page were written by Sean Kelly
⟨smkelly@FreeBSD.org⟩. Some contributions were made by
Jeff Roberson
⟨jeff@FreeBSD.org⟩.
BUGS¶
TheWD_PASSIVE
option has not yet been
implemented.December 21, 2009 | Debian |