过程分两大步
1. Main system 往/cache/recovery/command写命令wipe-data，重启手机
2. bootloader引导到recovery分区，执行wipe-data, 重启手机
1. Main system 往/cache/recovery/command写命令wipe-data，重启手机
packages/apps/Settings/src/com/android/settings/MasterClearConfirm.java
getActivity().sendBroadcast(new Intent(“android.intent.action.MASTER_CLEAR”));
packages/apps/Settings/src/com/android/settings/MasterClear.java
frameworks/base/services/java/com/android/server/MasterClearReceiver.java
new Thread(“Reboot”)
RecoverySystem.rebootWipeUserData(context)
frameworks/base/core/java/android/os/RecoverySystem.java
bootCommand(context, “–wipe_data\n–locale=” + Locale.getDefault().toString());
bootCommand
write command wipe-data to /cache/recovery/command
pm.reboot(“recovery”);
frameworks/base/core/java/android/os/PowerManager.java
frameworks/base/services/java/com/android/server/power/PowerManagerService.java
frameworks/base/services/java/com/android/server/power/ShutdownThread.java
PowerManager pm = (PowerManager) context.getSystemService(Context.POWER_SERVICE);
pm.reboot(“recovery”);
mService.reboot(false, reason, true)
shutdownOrRebootInternal(false, confirm, reason, wait);
ShutdownThread.shutdown(mContext, confirm); (shutdown)
ShutdownThread.reboot(mContext, reason, confirm); (reboot)
shutdownInner(context, confirm);
beginShutdownSequence(context)
setprop sys.shutdown.requested recovery
rebootOrShutdown(mReboot, mRebootReason);
PowerManagerService.lowLevelReboot(reason)
SystemProperties.set(“sys.powerctl”, “reboot,” + reason); Thread.sleep(20000);
system/core/rootdir/init.rc
on property:sys.powerctl=*
powerctl ${sys.powerctl}
KEYWORD(powerctl, COMMAND, 1, do_powerctl) system/core/init/keywords.h
do_powerctl() system/core/init/builtins.c
do_reboot(cmd, 0, reboot_target); cmd = ANDROID_RB_RESTART2; system/core/init/reboot.c
__reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2,LINUX_REBOOT_CMD_RESTART2, arg);
__reboot bionic/libc/arch-arm/syscalls/__reboot.S
kernel/kernel/sys.c
SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,void __user *, arg)
kernel_restart(char *cmd)
machine_restart(char *cmd) kernel/arch/arm/kernel/process.c
machine_shutdown()
arm_pm_restart(reboot_mode,cmd) kernel/arch/arm/kernel/process.c
pm_power_off = msm_pm_power_off;
arm_pm_restart = msm_pm_restart; /kernel/arch/arm/mach-msm/restart_7k.c
setup_mm_for_reboot kernel/arch/unicore32/mm/mmu.c
msm_proc_comm /kernel/arch/arm/mach-msm/proc_msm.c
2. bootloader引导到recovery分区，执行wipe-data, 重启手机
bootable/recovery/etc/init.rc
service recovery /sbin/recovery
bootable/recovery/recovery.c
读取/cache/recovery/command,判定哪种命令，如果是wipe-data,
erase_volume(“/data”);
erase_volume(“/cache”);
reboot();
check master reset log: /cache/recovery/log