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[WATCHDOG] Pre-Timeout flags

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Some watchdog timers support the concept of a "pretimeout" which
occurs some time before the real timeout.  The pretimeout can
be delivered via an interrupt or NMI and can be used to panic
the system when it occurs (so you get useful information instead
of a blind reboot).

Signed-off-by: Corey Minyard <minyard@acm.org>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Andrew Morton <akpm@osdl.org>
This commit is contained in:
Corey Minyard 2006-04-19 22:40:53 +02:00 committed by Wim Van Sebroeck
parent 427abfa28a
commit e05b59fe79
2 changed files with 32 additions and 1 deletions
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30
Documentation/watchdog/watchdog-api.txt
View file

@ -110,7 +110,31 @@ current timeout using the GETTIMEOUT ioctl.
ioctl(fd, WDIOC_GETTIMEOUT, &timeout);
printf("The timeout was is %d seconds\n", timeout);
Envinronmental monitoring:
Pretimeouts:
Some watchdog timers can be set to have a trigger go off before the
actual time they will reset the system. This can be done with an NMI,
interrupt, or other mechanism. This allows Linux to record useful
information (like panic information and kernel coredumps) before it
resets.
pretimeout = 10;
ioctl(fd, WDIOC_SETPRETIMEOUT, &pretimeout);
Note that the pretimeout is the number of seconds before the time
when the timeout will go off. It is not the number of seconds until
the pretimeout. So, for instance, if you set the timeout to 60 seconds
and the pretimeout to 10 seconds, the pretimout will go of in 50
seconds. Setting a pretimeout to zero disables it.
There is also a get function for getting the pretimeout:
ioctl(fd, WDIOC_GETPRETIMEOUT, &timeout);
printf("The pretimeout was is %d seconds\n", timeout);
Not all watchdog drivers will support a pretimeout.
Environmental monitoring:
All watchdog drivers are required return more information about the system,
some do temperature, fan and power level monitoring, some can tell you
@ -169,6 +193,10 @@ The watchdog saw a keepalive ping since it was last queried.
WDIOF_SETTIMEOUT Can set/get the timeout
The watchdog can do pretimeouts.
WDIOF_PRETIMEOUT Pretimeout (in seconds), get/set
For those drivers that return any bits set in the option field, the
GETSTATUS and GETBOOTSTATUS ioctls can be used to ask for the current

3
include/linux/watchdog.h
View file

@ -28,6 +28,8 @@ struct watchdog_info {
#define WDIOC_KEEPALIVE _IOR(WATCHDOG_IOCTL_BASE, 5, int)
#define WDIOC_SETTIMEOUT _IOWR(WATCHDOG_IOCTL_BASE, 6, int)
#define WDIOC_GETTIMEOUT _IOR(WATCHDOG_IOCTL_BASE, 7, int)
#define WDIOC_SETPRETIMEOUT _IOWR(WATCHDOG_IOCTL_BASE, 8, int)
#define WDIOC_GETPRETIMEOUT _IOR(WATCHDOG_IOCTL_BASE, 9, int)
#define WDIOF_UNKNOWN -1 /* Unknown flag error */
#define WDIOS_UNKNOWN -1 /* Unknown status error */
@ -41,6 +43,7 @@ struct watchdog_info {
#define WDIOF_POWEROVER 0x0040 /* Power over voltage */
#define WDIOF_SETTIMEOUT 0x0080 /* Set timeout (in seconds) */
#define WDIOF_MAGICCLOSE 0x0100 /* Supports magic close char */
#define WDIOF_PRETIMEOUT 0x0200 /* Pretimeout (in seconds), get/set */
#define WDIOF_KEEPALIVEPING 0x8000 /* Keep alive ping reply */
#define WDIOS_DISABLECARD 0x0001 /* Turn off the watchdog timer */