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When using AlarmManager, Android device can wake up from sleeping at some time.

How does Android schedule the wakeup at lower level?

I tried using rtcwake, but it fails with rtcwake: /dev/rtc0 not enabled for wakeup events (if I force rtcwake to proceed and make necessary ioctls I still don't see the device being woken up on time)

Which syscalls does Android use to set up an alarm and how to do them from console myself?

Vi.
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1 Answers1

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Android uses /dev/alarm device to setup alarms that can wakeup the system from suspend state. From JNI it can access this device using ioctl. See frameworks/base/services/jni/com_android_server_AlarmManagerService.cpp file. Android has exclusive access to this device and from what I understand the interface is available only from Java using AlarmManager service. If you need to setup these alarms at java level you can get access to this service using getSystemservice(ALARM_SERVICE), from native it is little tricky, I am also currently having the same issue. I need alarms in a native process and I am using sockets to communicate with java service to schedule alarms. This may not be the answer you are looking for but I would like to share my experience with this.

Arun
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