Android system shutdown process

The Android system has a shutdown button. If you press this button long, the system will shut down. The specific implementation process is as follows:

On the android layer, call reboot (ARG) to call sys_reboot in the kernel. The procedure is as follows:
Reboot --> sys_reboot () --> kernel_power_off () --> machine_power_off () --> pm_power_off ();
Pm_power_off is a function pointer pointing to the shutdown operation function related to a specific hardware platform.

 

System calls related to sys_reboot are implemented in source/kernel/sys. C.

Add the system call number in source/ASM-arm/unistd. h.

Then in the source/ARCH/ARM/kernel/entry-common.S for sys_call_table (system call table)

The specific table is implemented in source/ARCH/ARM/kernel/call. S.

 

Android system shutdown and restart
1. Shut down the Android system, and the restart code is located in frameworks/base/CORE/JNI/android_ OS _power.cpp, which contains

Static void android_ OS _power_shutdown (jnienv * ENV, jobject clazz)
{/* Shut down */
Sync ();
# Ifdef have_android_ OS
Reboot (rb_power_off );
# Endif
}

Static void android_ OS _power_reboot (jnienv * ENV, jobject clazz, jstring reason)
{/* Restart */
Sync ();
# Ifdef have_android_ OS
If (reason = NULL ){
Reboot (rb_autoboot );
} Else {
Const char * chars = env-> getstringutfchars (reason, null );
_ Reboot (linux_reboot_magic1, linux_reboot_magic2,
Linux_reboot_cmd_restart2, (char *) chars );
Env-> releasestringutfchars (reason, chars); // in case it fails.
}
Jnithrowioexception (ENV, errno );
# Endif
}

2. sys_reboot will be called in Linux, so we can add the restart function to Android;

Which functions are implemented by shutdown and restart in Linux kernel.
The final implementation of reboot is implemented in the arch_reset () function, which is usually defined in arch/ARM/Mach-xxx/include/Mach/system. h. System. H is applied by the Public Code of ARM kernel. Therefore, you need to define this header file and implement it.
The function prototype of arch_reset is
Void arch_reset (char Mode)
Void arch_reset (char Mode)
To shut down, point the pm_power_off function pointer to your own implementation function. The function pointer is defined in this way.
Void (* pm_power_off) (void );......

 

 

From: http://blog.csdn.net/yanzheng1113/article/details/7178067