关于Linux watchdog

/*
 * Watchdog usage.
 * Author: Serval Li
 * Date: Jun 27th, 2012
 * */
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <signal.h>
#include <linux/types.h>
#include <linux/watchdog.h>
int main(void)
{
        int fd;
        int timeout, flag;
        char cmd[256];
        if ((fd = open("/dev/watchdog", O_RDWR)) < 0) {
                perror("");
                exit(1);
        }
        ioctl(fd, WDIOC_GETTIMEOUT, &timeout);
        printf("Default timeout: %d\n", timeout);
        timeout = 12;
        printf("Set timeout to %d\n", timeout);
        ioctl(fd, WDIOC_SETTIMEOUT, &timeout);
        ioctl(fd, WDIOC_GETTIMEOUT, &timeout);
        printf("New timeout: %d\n", timeout);
        flag = fcntl(0, F_GETFL, 0);
        flag |= O_NONBLOCK;
        if (fcntl(0, F_SETFL, flag) < 0) {      /* fgets no-block now */
                perror("Set stdin to non-block fails.");
                exit(1);
        }
        while (1) {
                ioctl(fd, WDIOC_KEEPALIVE, 0);
                fgets(cmd, sizeof(cmd) - 1, stdin);
                if(strncmp(cmd, "stop", 4) == 0)
                        goto stopwd;
                sleep(timeout / 2);
        }
stopwd:
        write(fd, "V", 1);      /* This is "V", not "v"! */
        close(fd);
        printf("Close watchdog!");
        return 0;
}

代码先存下来，使用的是softdog.c实现的Watchdog。其内核模块名为softdog.ko，位于/lib/modules/$kernelver/kernel/drivers/watchdog下面。