看门狗

这篇文档介绍如何在Ubuntu系统中设置看门狗。

使能看门狗

看门狗默认是关闭的，你可以按如下步骤来使能看门狗：

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khadas@Khadas:~$ sudo ln -s  /lib/systemd/system/watchdog.service /etc/systemd/system/multi-user.target.wants/watchdog.service
khadas@Khadas:~$ sudo systemctl enable watchdog.service
khadas@Khadas:~$ sudo systemctl start watchdog.service
注意

这里需要手动设置服务链接，是Debian的一个bug，参考这里。

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khadas@Khadas:~$ sudo systemctl enable watchdog.service
khadas@Khadas:~$ sudo systemctl start watchdog.service

设置看门狗超时时间

默认超时时间是15秒，你可以编辑/etc/watchdog.conf中的watchdog-timeout字段来修改。

重启看门狗服务使其生效。

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khadas@Khadas:~$ sudo systemctl restart watchdog

查看看门狗服务

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khadas@Khadas:~$ systemctl status watchdog.service
● watchdog.service - watchdog daemon
     Loaded: loaded (/lib/systemd/system/watchdog.service; enabled; vendor pres>
     Active: active (running) since Fri 2021-03-26 10:00:38 UTC; 15min ago
    Process: 3381 ExecStartPre=/bin/sh -c [ -z "${watchdog_module}" ] || [ "${w>
    Process: 3382 ExecStart=/bin/sh -c [ $run_watchdog != 1 ] || exec /usr/sbin>
   Main PID: 3385 (watchdog)
      Tasks: 1 (limit: 2932)
     Memory: 864.0K
     CGroup: /system.slice/watchdog.service
             └─3385 /usr/sbin/watchdog -s -v -c /etc/watchdog.conf

Mar 26 10:15:38 Khadas watchdog[3385]: still alive after 120 interval(s)
Mar 26 10:15:39 Khadas watchdog[3385]: still alive after 121 interval(s)
Mar 26 10:15:40 Khadas watchdog[3385]: still alive after 122 interval(s)
Mar 26 10:15:41 Khadas watchdog[3385]: still alive after 123 interval(s)
Mar 26 10:15:42 Khadas watchdog[3385]: still alive after 124 interval(s)
Mar 26 10:15:43 Khadas watchdog[3385]: still alive after 125 interval(s)
Mar 26 10:15:44 Khadas watchdog[3385]: still alive after 126 interval(s)
Mar 26 10:15:45 Khadas watchdog[3385]: still alive after 127 interval(s)
Mar 26 10:15:46 Khadas watchdog[3385]: still alive after 128 interval(s)
Mar 26 10:15:47 Khadas watchdog[3385]: still alive after 129 interval(s)
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测试看门狗

  • 手动触发内核奔溃。
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khadas@Khadas:~$ sudo -i
root@Khadas:~# echo c > /proc/sysrq-trigger

如果看门狗设置成功，系统会在你上面设置的超时时间后重启。

  • 终止看门狗喂狗进程

还可以通过异常终止看门狗喂狗进程来触发看门狗复位。

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khadas@Khadas:~$ sudo pkill -9 watchdog
khadas@Khadas:~$ sudo pkill -9 wd_keepalive
khadas@Khadas:~$
khadas@Khadas:~$
khadas@Khadas:~$ G12B:BL:6e7c85:2a3b91;FEAT:E0F83180:402000;POC:F;RCY:0;EMMC:0;READ:0;0.
bl2_stage_init 0x01
bl2_stage_init 0x81
hw id: 0x0000 - pwm id 0x01
bl2_stage_init 0xc1
bl2_stage_init 0x02

L0:00000000
L1:20000703
L2:00008067
L3:14000000
B2:00402000
B1:e0f83180

TE: 207260

BL2 Built : 15:22:05, Aug 28 2019. g12b g1bf2b53 - luan.yuan@droid15-sz
...

关闭看门狗

  • 关闭看门狗服务
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khadas@Khadas:~$ sudo systemctl disable watchdog
khadas@Khadas:~$ sudo reboot
  • 关闭看门狗驱动【可选】

你还可以选择关闭看门狗驱动。编辑文件/boot/env.txt，移除overlays节点里面的watchdog，然后保存文件并重启系统。