/***************************************************************************                       Qt 控制watchdog app hacking* 声明：*     本文主要是为了查看之前朋友留下的Qt控制watchdog软件运作机制。**                                       2015-12-31 深圳 南山平山村 曾剑锋*************************************************************************/

一、参考文档：1. Qt Documentation：http://doc.qt.io/qt-4.8/qbasictimer.html2. QTimer和QBasicTimer使用：http://blog.csdn.net/thinkme2010/article/details/91127853. stm32独立看门狗和窗口看门狗的区别是什么？http://www.zhixinrui.com/thread-1192-1-1.html4. Linux下Watchdoghttp://blog.csdn.net/hshl1214/article/details/6248942

二、QBasicTimer Class：This is a fast, lightweight, and low-level class used by Qt internally. We recommend using the higher-level QTimer class rather than this class if you want to use timers in your applications. Note that this timer is a repeating timer that will send subsequent timer events unless the stop() function is called.三、Linux下watchdog的工作原理Watchdog在实现上可以是硬件电路也可以是软件定时器，能够在系统出现故障时自动重新启动系统。在Linux 内核下, watchdog的基本工作原理是：当watchdog启动后(即/dev/watchdog 设备被打开后)，如果在某一设定的时间间隔内/dev/watchdog没有被执行写操作, 硬件watchdog电路或软件定时器就会重新启动系统。四、cat mainwindow.cpp#include "mainwindow.h"#include "ui_mainwindow.h"#include <unistd.h>#include <fcntl.h>#include <sys/ioctl.h>#include <linux/types.h>#include <linux/watchdog.h>#include <QMessageBox>MainWindow::MainWindow(QWidget *parent) :QMainWindow(parent),ui(new Ui::MainWindow){ui->setupUi(this);fd = 0;times = 0;}MainWindow::~MainWindow(){delete ui;::close(fd);}void MainWindow::timerEvent(QTimerEvent *){int dummy;QString str;times++;/*** timer每次都会执行，有点不合理*/if(ui->checkBox->isChecked())::ioctl(fd,WDIOC_KEEPALIVE,&dummy);ui->times->setText(str.sprintf("%d",times));}void MainWindow::on_pushButton_clicked(){// 打开watchdog设备文件，就相当于开机了watchdog，并设置了一个默认值// 这个默认值是多少，目前不知道，去跟一下驱动，应该是可以获知的。if(ui->pushButton->text() == QString("open watchdog")){ui->pushButton->setText("close watchdog");ui->checkBox->setDisabled(true);fd = ::open("/dev/watchdog",O_WRONLY);if(fd < 0){QMessageBox::about(this,"error","open watchdog failure");exit(-1);}times = 0;ui->times->setText("0");timer.start(1000,this);}else    // 关闭fd，就相当于关闭了watchdog
        {ui->pushButton->setText("open watchdog");ui->checkBox->setEnabled(true);timer.stop();::close(fd);}}void MainWindow::moveEvent(QMoveEvent *){this->move(QPoint(0,0));}void MainWindow::resizeEvent(QResizeEvent *){this->showMaximized();}void MainWindow::closeEvent(QCloseEvent *){exit(0);}