to run the program with an "&" to run it in the background!)
If you want to write a program to be compatible with the PC Watchdog
- driver, simply do the following:
-
--- Snippet of code --
-/*
- * Watchdog Driver Test Program
- */
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
-#include <fcntl.h>
-#include <sys/ioctl.h>
-#include <linux/types.h>
-#include <linux/watchdog.h>
-
-int fd;
-
-/*
- * This function simply sends an IOCTL to the driver, which in turn ticks
- * the PC Watchdog card to reset its internal timer so it doesn't trigger
- * a computer reset.
- */
-void keep_alive(void)
-{
- int dummy;
-
- ioctl(fd, WDIOC_KEEPALIVE, &dummy);
-}
-
-/*
- * The main program. Run the program with "-d" to disable the card,
- * or "-e" to enable the card.
- */
-int main(int argc, char *argv[])
-{
- fd = open("/dev/watchdog", O_WRONLY);
-
- if (fd == -1) {
- fprintf(stderr, "Watchdog device not enabled.\n");
- fflush(stderr);
- exit(-1);
- }
-
- if (argc > 1) {
- if (!strncasecmp(argv[1], "-d", 2)) {
- ioctl(fd, WDIOC_SETOPTIONS, WDIOS_DISABLECARD);
- fprintf(stderr, "Watchdog card disabled.\n");
- fflush(stderr);
- exit(0);
- } else if (!strncasecmp(argv[1], "-e", 2)) {
- ioctl(fd, WDIOC_SETOPTIONS, WDIOS_ENABLECARD);
- fprintf(stderr, "Watchdog card enabled.\n");
- fflush(stderr);
- exit(0);
- } else {
- fprintf(stderr, "-d to disable, -e to enable.\n");
- fprintf(stderr, "run by itself to tick the card.\n");
- fflush(stderr);
- exit(0);
- }
- } else {
- fprintf(stderr, "Watchdog Ticking Away!\n");
- fflush(stderr);
- }
-
- while(1) {
- keep_alive();
- sleep(1);
- }
-}
--- End snippet --
+ driver, simply use of modify the watchdog test program:
+ Documentation/watchdog/src/watchdog-test.c
+
Other IOCTL functions include:
--- /dev/null
+#include <stdlib.h>
+#include <fcntl.h>
+
+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);
+ fsync(fd);
+ sleep(10);
+ }
+}
--- /dev/null
+/*
+ * Watchdog Driver Test Program
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <linux/types.h>
+#include <linux/watchdog.h>
+
+int fd;
+
+/*
+ * This function simply sends an IOCTL to the driver, which in turn ticks
+ * the PC Watchdog card to reset its internal timer so it doesn't trigger
+ * a computer reset.
+ */
+void keep_alive(void)
+{
+ int dummy;
+
+ ioctl(fd, WDIOC_KEEPALIVE, &dummy);
+}
+
+/*
+ * The main program. Run the program with "-d" to disable the card,
+ * or "-e" to enable the card.
+ */
+int main(int argc, char *argv[])
+{
+ fd = open("/dev/watchdog", O_WRONLY);
+
+ if (fd == -1) {
+ fprintf(stderr, "Watchdog device not enabled.\n");
+ fflush(stderr);
+ exit(-1);
+ }
+
+ if (argc > 1) {
+ if (!strncasecmp(argv[1], "-d", 2)) {
+ ioctl(fd, WDIOC_SETOPTIONS, WDIOS_DISABLECARD);
+ fprintf(stderr, "Watchdog card disabled.\n");
+ fflush(stderr);
+ exit(0);
+ } else if (!strncasecmp(argv[1], "-e", 2)) {
+ ioctl(fd, WDIOC_SETOPTIONS, WDIOS_ENABLECARD);
+ fprintf(stderr, "Watchdog card enabled.\n");
+ fflush(stderr);
+ exit(0);
+ } else {
+ fprintf(stderr, "-d to disable, -e to enable.\n");
+ fprintf(stderr, "run by itself to tick the card.\n");
+ fflush(stderr);
+ exit(0);
+ }
+ } else {
+ fprintf(stderr, "Watchdog Ticking Away!\n");
+ fflush(stderr);
+ }
+
+ while(1) {
+ keep_alive();
+ sleep(1);
+ }
+}
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 <stdlib.h>
-#include <fcntl.h>
-
-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.
Minor numbers are however allocated for it.
-Example Watchdog Driver
------------------------
-
-#include <stdio.h>
-#include <unistd.h>
-#include <fcntl.h>
-
-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);
- fsync(fd);
- sleep(10);
- }
-}
+Example Watchdog Driver: see Documentation/watchdog/src/watchdog-simple.c
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