From e05b59fe7927bc648ac3af3d59dc64a7ee6b22e2 Mon Sep 17 00:00:00 2001 From: Corey Minyard Date: Wed, 19 Apr 2006 22:40:53 +0200 Subject: [WATCHDOG] Pre-Timeout flags 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 Signed-off-by: Wim Van Sebroeck Signed-off-by: Andrew Morton --- Documentation/watchdog/watchdog-api.txt | 30 +++++++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-) (limited to 'Documentation/watchdog/watchdog-api.txt') diff --git a/Documentation/watchdog/watchdog-api.txt b/Documentation/watchdog/watchdog-api.txt index 21ed511..7dc2c1c 100644 --- a/Documentation/watchdog/watchdog-api.txt +++ b/Documentation/watchdog/watchdog-api.txt @@ -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 -- cgit v1.1 From 58b519f3e5e491d5a3e320dc525f58ac439bdde4 Mon Sep 17 00:00:00 2001 From: Wim Van Sebroeck Date: Sun, 21 May 2006 12:48:44 +0200 Subject: [WATCHDOG] add WDIOC_GETTIMELEFT ioctl Some watchdog drivers have the ability to report the remaining time before the system will reboot. With the WDIOC_GETTIMELEFT ioctl you can now read the time left before the watchdog would reboot your system. The following drivers support this new IOCTL: i8xx_tco.c, pcwd_pci.c and pcwd_usb.c . Signed-off-by: Wim Van Sebroeck Signed-off-by: Andrew Morton --- Documentation/watchdog/watchdog-api.txt | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'Documentation/watchdog/watchdog-api.txt') diff --git a/Documentation/watchdog/watchdog-api.txt b/Documentation/watchdog/watchdog-api.txt index 7dc2c1c..d738ec2 100644 --- a/Documentation/watchdog/watchdog-api.txt +++ b/Documentation/watchdog/watchdog-api.txt @@ -134,6 +134,15 @@ There is also a get function for getting the pretimeout: Not all watchdog drivers will support a pretimeout. +Get the number of seconds before reboot: + +Some watchdog drivers have the ability to report the remaining time +before the system will reboot. The WDIOC_GETTIMELEFT is the ioctl +that returns the number of seconds before reboot. + + ioctl(fd, WDIOC_GETTIMELEFT, &timeleft); + printf("The timeout was is %d seconds\n", timeleft); + Environmental monitoring: All watchdog drivers are required return more information about the system, -- cgit v1.1 From 56fb9e5346b99bc6b77def79b3739097bc13ea8a Mon Sep 17 00:00:00 2001 From: Randy Dunlap Date: Sun, 21 May 2006 20:58:10 -0700 Subject: [WATCHDOG] Documentation/watchdog update Documentation/watchdog/: Expose example and tool source files in the Documentation/ directory in their own files instead of being buried (almost hidden) in readme/txt files. This will make them more visible/usable to users who may need to use them, to developers who may need to test with them, and to janitors who would update them if they were more visible. Also, if any of these possibly should not be in the kernel tree at all, it will be clearer that they are here and we can discuss if they should be removed. Signed-off-by: Randy Dunlap Signed-off-by: Wim Van Sebroeck Signed-off-by: Andrew Morton --- Documentation/watchdog/watchdog-api.txt | 17 +---------------- 1 file changed, 1 insertion(+), 16 deletions(-) (limited to 'Documentation/watchdog/watchdog-api.txt') diff --git a/Documentation/watchdog/watchdog-api.txt b/Documentation/watchdog/watchdog-api.txt index d738ec2..958ff3d 100644 --- a/Documentation/watchdog/watchdog-api.txt +++ b/Documentation/watchdog/watchdog-api.txt @@ -34,22 +34,7 @@ activates as soon as /dev/watchdog is opened and will reboot unless the watchdog is pinged within a certain time, this time is called the timeout or margin. The simplest way to ping the watchdog is to write some data to the device. So a very simple watchdog daemon would look -like this: - -#include -#include - -int main(int argc, const char *argv[]) { - int fd=open("/dev/watchdog",O_WRONLY); - if (fd==-1) { - perror("watchdog"); - exit(1); - } - while(1) { - write(fd, "\0", 1); - sleep(10); - } -} +like this source file: see Documentation/watchdog/src/watchdog-simple.c A more advanced driver could for example check that a HTTP server is still responding before doing the write call to ping the watchdog. -- cgit v1.1