进入recovery有两种方式，一种是通过组合键进入recovery，另一种是上层应用设置中执行安装/重置/清除缓存等操作进行recovery。这篇文档主要讲解上层应用是如何进入到recovery的。本文以高通平台为例。
1.app执行安装/重置/清楚缓存操作调用代码文件frameworks/base/core/java/android/os/RecoverySystem.java
不同的操作使用不同的方法：
安装升级包 -------- installPackage
清除用户数据------ rebootWipeUserData
清楚缓存 ----------- rebootWipeCache
上面的所有操作都是往/cache/recovery/command文件中写入不同的命令，在进入recovery后（recovery.cpp）对command的关键字进行判断，执行相应的操作，下文会详细讲解，这里先简单提及。
bootable/recovery/recovery.app
static const struct option OPTIONS[] = { { "send_intent", required_argument, NULL, 'i' }, { "update_package", required_argument, NULL, 'u' },// [FEATURE]-ADD-BEGIN by TCTSH#ifdef TARGET_USE_REDBEND_FOTA { "omadm_package", required_argument, NULL, 'o' },#endif// [FEATURE]-ADD-END { "wipe_data", no_argument, NULL, 'w' }, { "wipe_cache", no_argument, NULL, 'c' }, { "show_text", no_argument, NULL, 't' }, { "sideload", no_argument, NULL, 's' }, { "sideload_auto_reboot", no_argument, NULL, 'a' }, { "just_exit", no_argument, NULL, 'x' }, { "locale", required_argument, NULL, 'l' }, { "stages", required_argument, NULL, 'g' }, { "shutdown_after", no_argument, NULL, 'p' }, { "reason", required_argument, NULL, 'r' }, { NULL, 0, NULL, 0 },};
..................
int
main(int argc, char **argv) {
....
get_args(&argc, &argv); //提取cache/recovery/command中的信息
....
while ((arg = getopt_long(argc, argv, "", OPTIONS, NULL)) != -1) { //解析cache/recovery/command文件中的信息
printf("***** xiaolei 2\n");
switch (arg) {
case 'i': send_intent = optarg; break;
case 'u': update_package = optarg; break;
// [FEATURE]-ADD-BEGIN by TCTSH
case 'o': omadm_package = optarg; break;
// [FEATURE]-ADD-END
case 'w': should_wipe_data = true; break;
case 'c': should_wipe_cache = true; break;
case 't': show_text = true; break;
case 's': sideload = true; break;
case 'a': sideload = true; sideload_auto_reboot = true; break;
case 'x': just_exit = true; break;
case 'l': locale = optarg; break;
case 'g': {
if (stage == NULL || *stage == '\0') {
char buffer[20] = "1/";
strncat(buffer, optarg, sizeof(buffer)-3);
stage = strdup(buffer);
}
break;
}
case 'p': shutdown_after = true; break;
case 'r': reason = optarg; break;
case '?':
LOGE("Invalid command argument\n");
continue;
}
}
}
本文以installPackage为例：
frameworks/base/core/java/android/os/RecoverySystem.java
public static void installPackage(Context context, File packageFile) throws IOException { String filename = packageFile.getCanonicalPath(); //获取升级包路径 String internalPath = Environment.maybeTranslateEmulatedPathToInternal(new File(filename)).getPath(); FileWriter uncryptFile = new FileWriter(UNCRYPT_FILE); try { uncryptFile.write(internalPath + "\n"); } finally { uncryptFile.close(); } Log.w(TAG, "!!! REBOOTING TO INSTALL " + filename + " !!!"); Log.w(TAG, "!!! REBOOTING TO INSTALL REALPATH " + internalPath + " !!!"); // If the package is on the /data partition, write the block map file // If the package is on internal storage sdcard,write the block map file // into COMMAND_FILE instead. if (filename.startsWith("/data/") //加密处理，block.map是解密的映射文件 ||filename.startsWith("/storage/emulated/0/")) { filename = "@/cache/recovery/block.map"; } final String filenameArg = "--update_package=" + filename; //把“--update_package=path” 通过bootCommand方法写入到cache/recovery/command文件中 final String localeArg = "--locale=" + Locale.getDefault().toString(); //recovery显示语言 bootCommand(context, filenameArg, localeArg); }
installPackage方**嗲用bootCommand()方法，此时参数为（context,向cache/recovery/command文件中写入的信息，语言信息）
private static void bootCommand(Context context, String... args) throws IOException { RECOVERY_DIR.mkdirs(); // In case we need it COMMAND_FILE.delete(); // In case it's not writable LOG_FILE.delete(); FileWriter command = new FileWriter(COMMAND_FILE); //向/cache/recovery/command中写入--update_package=path try { for (String arg : args) { if (!TextUtils.isEmpty(arg)) { command.write(arg); command.write("\n"); } } } finally { command.close(); } // Having written the command file, go ahead and reboot PowerManager pm = (PowerManager) context.getSystemService(Context.POWER_SERVICE); pm.reboot(PowerManager.REBOOT_RECOVERY); //PowerManager.REBOOT_RECOVERY的值为字符串"recovery" throw new IOException("Reboot failed (no permissions?)"); }pm.reboot(PowerManager.REBOOT_RECOVERY); 参数为字符串("recovery")
frameworks/base/core/java/android/os/PowerMangager.javapublic void reboot(String reason) { try { mService.reboot(false, reason, true); } catch (RemoteException e) { } } mService.reboot(false, reason, true); 参数为(false,"recovery",true)
frameworks/base/services/core/java/com/android/server/power/PowerManagerService.javapublic void reboot(boolean confirm, String reason, boolean wait) { mContext.enforceCallingOrSelfPermission(android.Manifest.permission.REBOOT, null); if (PowerManager.REBOOT_RECOVERY.equals(reason)) { mContext.enforceCallingOrSelfPermission(android.Manifest.permission.RECOVERY, null); } final long ident = Binder.clearCallingIdentity(); try { shutdownOrRebootInternal(false, confirm, reason, wait); } finally { Binder.restoreCallingIdentity(ident); } }shutdownOrRebootInternal(false, confirm, reason, wait); 参数为(false,false,"recovery",true)
frameworks/base/services/core/java/com/android/server/power/PowerManagerService.java
private void shutdownOrRebootInternal(final boolean shutdown, final boolean confirm, final String reason, boolean wait) { if (mHandler == null || !mSystemReady) { throw new IllegalStateException("Too early to call shutdown() or reboot()"); } Runnable runnable = new Runnable() { @Override public void run() { synchronized (this) { if (shutdown) { //此处shutdown=false ShutdownThread.shutdown(mContext, confirm); } else { ShutdownThread.reboot(mContext, reason, confirm); //执行此处代码 } } } }; // ShutdownThread must run on a looper capable of displaying the UI. Message msg = Message.obtain(mHandler, runnable); msg.setAsynchronous(true); mHandler.sendMessage(msg); // PowerManager.reboot() is documented not to return so just wait for the inevitable. if (wait) { synchronized (runnable) { while (true) { try { runnable.wait(); } catch (InterruptedException e) { } } } } }
ShutdownThread.reboot(mContext, reason, confirm); 参数为(mContex,"recovery",false)
此处开了一个线程处理reboot
frameworks/base/services/core/java/com/android/server/power/ShutdownThread.javapublic static void reboot(final Context context, String reason, boolean confirm) { //方法中的变量为全局变量
mReboot = true; mRebootSafeMode = false; mRebootUpdate = false; mRebootReason = reason; shutdownInner(context, confirm); //此方法是在手机界面上弹出一个确认框，是否重启，此处的代码不再追了 }
//程序一定会执行run()方法
/***********************
mReboot = true;mRebootSafeMode = false;mRebootUpdate = false;mRebootReason = "recovery";
***********************/
public void run() {
BroadcastReceiver br = new BroadcastReceiver() {
@Override public void onReceive(Context context, Intent intent) {
// We don't allow apps to cancel this, so ignore the result.
actionDone();
}
};
/*
* Write a system property in case the system_server reboots before we
* get to the actual hardware restart. If that happens, we'll retry at
* the beginning of the SystemServer startup.
*/
{
String reason = (mReboot ? "1" : "0") + (mRebootReason != null ? mRebootReason : ""); //reason的值为"recovery"
SystemProperties.set(SHUTDOWN_ACTION_PROPERTY, reason); //设置系统属性sys.shutdown.requested = "recovery"
}
/*
* If we are rebooting into safe mode, write a system property
* indicating so.
*/
if (mRebootSafeMode) {
SystemProperties.set(REBOOT_SAFEMODE_PROPERTY, "1");
}
Log.i(TAG, "Sending shutdown broadcast...");
// [BUGFIX]-ADD-BEGIN BY TCTNB.BinhongWang,01/28/2016,Defect-1305415
setBootValue("silent_mode",mAudioManager.isSilentMode() ? "1" : "0");
if(checkAnimationFileExist() && mContext.getResources().
getBoolean(com.android.internal.R.bool.feature_tctfw_shutdown_animation_on) &&
!mRebootUpdate) {
lockDevice();
showShutdownAnimation();
}
// [BUGFIX]-ADD-END BY TCTNB.BinhongWang,01/28/2016,Defect-1305415
// First send the high-level shut down broadcast.
mActionDone = false;
Intent intent = new Intent(Intent.ACTION_SHUTDOWN);
intent.addFlags(Intent.FLAG_RECEIVER_FOREGROUND);
mContext.sendOrderedBroadcastAsUser(intent,
UserHandle.ALL, null, br, mHandler, 0, null, null);
final long endTime = SystemClock.elapsedRealtime() + MAX_BROADCAST_TIME;
synchronized (mActionDoneSync) {
while (!mActionDone) {
long delay = endTime - SystemClock.elapsedRealtime();
if (delay <= 0) {
Log.w(TAG, "Shutdown broadcast timed out");
break;
} else if (mRebootUpdate) {
int status = (int)((MAX_BROADCAST_TIME - delay) * 1.0 *
BROADCAST_STOP_PERCENT / MAX_BROADCAST_TIME);
sInstance.setRebootProgress(status, null);
}
try {
mActionDoneSync.wait(Math.min(delay, PHONE_STATE_POLL_SLEEP_MSEC));
} catch (InterruptedException e) {
}
}
}
if (mRebootUpdate) {
sInstance.setRebootProgress(BROADCAST_STOP_PERCENT, null);
}
Log.i(TAG, "Shutting down activity manager...");
final IActivityManager am =
ActivityManagerNative.asInterface(ServiceManager.checkService("activity"));
if (am != null) {
try {
am.shutdown(MAX_BROADCAST_TIME);
} catch (RemoteException e) {
}
}
if (mRebootUpdate) {
sInstance.setRebootProgress(ACTIVITY_MANAGER_STOP_PERCENT, null);
}
Log.i(TAG, "Shutting down package manager...");
final PackageManagerService pm = (PackageManagerService)
ServiceManager.getService("package");
if (pm != null) {
pm.shutdown();
}
if (mRebootUpdate) {
sInstance.setRebootProgress(PACKAGE_MANAGER_STOP_PERCENT, null);
}
// Shutdown radios.
shutdownRadios(MAX_RADIO_WAIT_TIME);
if (mRebootUpdate) {
sInstance.setRebootProgress(RADIO_STOP_PERCENT, null);
}
// Mod-by-yanxi.liu, for sdcard upgrade uncrypt, Defect-1357392
if (mRebootUpdate) {
sInstance.setRebootProgress(MOUNT_SERVICE_STOP_PERCENT, null);
// If it's to reboot to install update, invoke uncrypt via init service.
uncrypt();
}
// Mod-by-yanxi.liu, for sdcard upgrade uncrypt, Defect-1357392
// Shutdown MountService to ensure media is in a safe state
IMountShutdownObserver observer = new IMountShutdownObserver.Stub() {
public void onShutDownComplete(int statusCode) throws RemoteException {
Log.w(TAG, "Result code " + statusCode + " from MountService.shutdown");
actionDone();
}
};
Log.i(TAG, "Shutting down MountService");
// Set initial variables and time out time.
mActionDone = false;
final long endShutTime = SystemClock.elapsedRealtime() + MAX_SHUTDOWN_WAIT_TIME;
synchronized (mActionDoneSync) {
try {
final IMountService mount = IMountService.Stub.asInterface(
ServiceManager.checkService("mount"));
if (mount != null) {
mount.shutdown(observer);
} else {
Log.w(TAG, "MountService unavailable for shutdown");
}
} catch (Exception e) {
Log.e(TAG, "Exception during MountService shutdown", e);
}
while (!mActionDone) {
long delay = endShutTime - SystemClock.elapsedRealtime();
if (delay <= 0) {
Log.w(TAG, "Shutdown wait timed out");
break;
} else if (mRebootUpdate) {
int status = (int)((MAX_SHUTDOWN_WAIT_TIME - delay) * 1.0 *
(MOUNT_SERVICE_STOP_PERCENT - RADIO_STOP_PERCENT) /
MAX_SHUTDOWN_WAIT_TIME);
status += RADIO_STOP_PERCENT;
sInstance.setRebootProgress(status, null);
}
try {
mActionDoneSync.wait(Math.min(delay, PHONE_STATE_POLL_SLEEP_MSEC));
} catch (InterruptedException e) {
}
}
}
// add by feikuang for defect 1453123 start
isVibrate = mContext.getResources().getBoolean(com.android.internal.R.bool.config_isVibrate);
Log.i(TAG,"isVibrate " + isVibrate);
// add by feikuang for defect 1453123 end
waitShutDownAnimationCompleted();
rebootOrShutdown(mContext, mReboot, mRebootReason); //程序执行到这里
}
rebootOrShutdown(mContext, mReboot, mRebootReason); 参数为(mContext,true,"recovery")
frameworks/base/services/core/java/com/android/server/power/ShutdownThread.javapublic static void rebootOrShutdown(final Context context, boolean reboot, String reason) { deviceRebootOrShutdown(reboot, reason); //[FEATURE]-Add-BEGIN by TSNJ.shu.wang,11/06/2015,TASK-871146 String bootAlarms = SystemProperties.get("sys.boot.alarm"); boolean isBootAlarms = bootAlarms != null && bootAlarms.equals("1"); if (reboot) { Log.i(TAG, "Rebooting, reason: " + reason); PowerManagerService.lowLevelReboot(reason); //程序执行到这里 Log.e(TAG, "Reboot failed, will attempt shutdown instead"); } else if (SHUTDOWN_VIBRATE_MS > 0 && context != null && !isBootAlarms && isVibrate) { //[FEATURE]-Add-END by TSNJ.shu.wang,11/06/2015,TASK-871146 // vibrate before shutting down Vibrator vibrator = new SystemVibrator(context); try { vibrator.vibrate(SHUTDOWN_VIBRATE_MS, VIBRATION_ATTRIBUTES); } catch (Exception e) { // Failure to vibrate shouldn't interrupt shutdown. Just log it. Log.w(TAG, "Failed to vibrate during shutdown.", e); } // vibrator is asynchronous so we need to wait to avoid shutting down too soon. try { Thread.sleep(SHUTDOWN_VIBRATE_MS); } catch (InterruptedException unused) { } } // Shutdown power Log.i(TAG, "Performing low-level shutdown..."); PowerManagerService.lowLevelShutdown(); }PowerManagerService.lowLevelReboot(reason); 参数为"recovery"
frameworks/base/services/core/java/com/android/server/power/PowerManagerService.javapublic static void lowLevelReboot(String reason) { if (reason == null) { reason = ""; } if (reason.equals(PowerManager.REBOOT_RECOVERY)) { // If we are rebooting to go into recovery, instead of // setting sys.powerctl directly we'll start the // pre-recovery service which will do some preparation for // recovery and then reboot for us. SystemProperties.set("ctl.start", "pre-recovery"); //到这里可以知道，一个新的进程会被enable } else { SystemProperties.set("sys.powerctl", "reboot," + reason); } try { Thread.sleep(20 * 1000L); } catch (InterruptedException e) { Thread.currentThread().interrupt(); } Slog.wtf(TAG, "Unexpected return from lowLevelReboot!"); }SystemProperties.set("ctl.start", "pre-recovery"); //到这里可以知道，一个新的进程会被enable
system/core/rootdir/init.rcservice pre-recovery /system/bin/uncrypt --reboot class main disabled oneshot
service pre-recovery /system/bin/uncrypt --reboot system/bin/uncrypt 这个程序会被执行，传入的参数是--reboot
uncrypt的源码位于bootable/recovery/uncrypt/uncrypt.cpp，下面对uncrypt进行分析
bootable/recovery/uncrypt/uncrypt.cpp
int main(int argc, char** argv) { //此处argc为2 argv[1]="--reboot" const char* input_path; const char* map_file; if (argc != 3 && argc != 1 && (argc == 2 && strcmp(argv[1], "--reboot") != 0)) { fprintf(stderr, "usage: %s [--reboot] [<transform_path> <map_file>]\n", argv[0]); return 2; } // When uncrypt is started with "--reboot", it wipes misc and reboots. // Otherwise it uncrypts the package and writes the block map. if (argc == 2) { //程序执行到此处 if (read_fstab() == NULL) { return 1; } wipe_misc(); //擦出misc分区内容 reboot_to_recovery(); //重启到recovery } else { // The pipe has been created by the system server. int status_fd = open(status_file.c_str(), O_WRONLY | O_CREAT | O_SYNC, S_IRUSR | S_IWUSR); if (status_fd == -1) { ALOGE("failed to open pipe \"%s\": %s\n", status_file.c_str(), strerror(errno)); return 1; } std::string package; if (argc == 3) { // when command-line args are given this binary is being used // for debugging. input_path = argv[1]; map_file = argv[2]; } else { if (!find_uncrypt_package(package)) { android::base::WriteStringToFd("-1\n", status_fd); close(status_fd); return 1; } input_path = package.c_str(); map_file = cache_block_map.c_str(); } int status = uncrypt(input_path, map_file, status_fd); if (status != 0) { android::base::WriteStringToFd("-1\n", status_fd); close(status_fd); return 1; } android::base::WriteStringToFd("100\n", status_fd); close(status_fd); } return 0;}
reboot_to_recovery();
bootable/recovery/uncrpty/uncrpty.cppstatic void reboot_to_recovery() { ALOGI("rebooting to recovery"); property_set("sys.powerctl", "reboot,recovery"); sleep(10); ALOGE("reboot didn't succeed?");}property_set("sys.powerctl", "reboot,recovery"); sys.powerctl属性出发开关在init.rc中system/core/rootdir/init.rcon property:sys.powerctl=* powerctl ${sys.powerctl}system/core/init/keywords.h
KEYWORD(powerctl, COMMAND, 1, do_powerctl
system/core/init/builtins.cpp int do_powerctl(int nargs, char **args) //传入的参数为字符串"reboot,recovery"{ char command[PROP_VALUE_MAX]; int res; int len = 0; int cmd = 0; const char *reboot_target; res = expand_props(command, args[1], sizeof(command)); if (res) { ERROR("powerctl: cannot expand '%s'\n", args[1]); return -EINVAL; } if (strncmp(command, "shutdown", 8) == 0) { cmd = ANDROID_RB_POWEROFF; len = 8; } else if (strncmp(command, "reboot", 6) == 0) { //程序走到这，cmd=ANDROID_RB_RESTART2 cmd = ANDROID_RB_RESTART2; len = 6; } else { ERROR("powerctl: unrecognized command '%s'\n", command); return -EINVAL; } if (command[len] == ',') { char prop_value[PROP_VALUE_MAX] = {0}; reboot_target = &command[len + 1]; //设置reboot_target = recovery if ((property_get("init.svc.recovery", prop_value) == 0) && (strncmp(reboot_target, "keys", 4) == 0)) { ERROR("powerctl: permission denied\n"); return -EINVAL; } } else if (command[len] == '\0') { reboot_target = ""; } else { ERROR("powerctl: unrecognized reboot target '%s'\n", &command[len]); return -EINVAL; } return android_reboot(cmd, 0, reboot_target); }android_reboot(cmd, 0, reboot_target); 参数为(ANDROID_RB_RESTART2, 0, "recovery")
system/core/libcutils/android_reboot.cint android_reboot(int cmd, int flags UNUSED, const char *arg){ int ret; sync(); remount_ro(); switch (cmd) { case ANDROID_RB_RESTART: ret = reboot(RB_AUTOBOOT); break; case ANDROID_RB_POWEROFF: ret = reboot(RB_POWER_OFF); break; case ANDROID_RB_RESTART2: //程序跑到这里其中arg="recovery" ret = syscall(__NR_reboot, LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, LINUX_REBOOT_CMD_RESTART2, arg); break; default: ret = -1; } return ret;}ret = syscall(__NR_reboot, LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, LINUX_REBOOT_CMD_RESTART2, arg);
kernel/include/uapi/asm-generic/unistd.h#define __NR_reboot 142__SYSCALL(__NR_reboot, sys_reboot）
__NR_reboot被映射到sys_reboot上,会执行SYSCALL_DEFINE4(),为什么会这么执行还不清楚。
kernel/kernel/sys.cSYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd, void __user *, arg) //对应LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, LINUX_REBOOT_CMD_RESTART2, "recovery"{ struct pid_namespace *pid_ns = task_active_pid_ns(current); char buffer[256]; int ret = 0; /* We only trust the superuser with rebooting the system. */ if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT)) return -EPERM; /* For safety, we require "magic" arguments. */ if (magic1 != LINUX_REBOOT_MAGIC1 || (magic2 != LINUX_REBOOT_MAGIC2 && magic2 != LINUX_REBOOT_MAGIC2A && magic2 != LINUX_REBOOT_MAGIC2B && magic2 != LINUX_REBOOT_MAGIC2C)) return -EINVAL; /* * If pid namespaces are enabled and the current task is in a child * pid_namespace, the command is handled by reboot_pid_ns() which will * call do_exit(). */ ret = reboot_pid_ns(pid_ns, cmd); if (ret) return ret; /* Instead of trying to make the power_off code look like * halt when pm_power_off is not set do it the easy way. */ if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off) cmd = LINUX_REBOOT_CMD_HALT; mutex_lock(&reboot_mutex); switch (cmd) { case LINUX_REBOOT_CMD_RESTART: kernel_restart(NULL); break; case LINUX_REBOOT_CMD_CAD_ON: C_A_D = 1; break; case LINUX_REBOOT_CMD_CAD_OFF: C_A_D = 0; break; case LINUX_REBOOT_CMD_HALT: kernel_halt(); do_exit(0); panic("cannot halt"); case LINUX_REBOOT_CMD_POWER_OFF: kernel_power_off(); do_exit(0); break; case LINUX_REBOOT_CMD_RESTART2: if (strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1) < 0) { ret = -EFAULT; break; } buffer[sizeof(buffer) - 1] = '\0'; kernel_restart(buffer); //程序会跑到这里 break;#ifdef CONFIG_KEXEC case LINUX_REBOOT_CMD_KEXEC: ret = kernel_kexec(); break;#endif#ifdef CONFIG_HIBERNATION case LINUX_REBOOT_CMD_SW_SUSPEND: ret = hibernate(); break;#endif default: ret = -EINVAL; break; } mutex_unlock(&reboot_mutex); return ret;}kernel_restart(buffer); 参数为("recovery")kernel/kernel/sys.cvoid kernel_restart(char *cmd){ kernel_restart_prepare(cmd); migrate_to_reboot_cpu(); syscore_shutdown(); if (!cmd) printk(KERN_EMERG "Restarting system.\n"); else printk(KERN_EMERG "Restarting system with command '%s'.\n", cmd); kmsg_dump(KMSG_DUMP_RESTART); machine_restart(cmd);}machine_restart(cmd); 参数为("recovery")
kernel/arch/arm/kernel/process.cvoid machine_restart(char *cmd){ preempt_disable(); smp_send_stop(); /* Flush the console to make sure all the relevant messages make it * out to the console drivers */ arm_machine_flush_console(); arm_pm_restart(reboot_mode, cmd); /* Give a grace period for failure to restart of 1s */ mdelay(1000); /* Whoops - the platform was unable to reboot. Tell the user! */ printk("Reboot failed -- System halted\n"); local_irq_disable(); while (1);}arm_pm_restart(reboot_mode, cmd);
kernel/drivers/power/reset/msm-poweroff.cstatic int msm_restart_probe(struct platform_device *pdev){ .....arm_pm_restart = do_msm_restart;..... }kernel/drivers/power/reset/msm-poweroff.c
static void do_msm_restart(enum reboot_mode reboot_mode, const char *cmd){ int ret; struct scm_desc desc = { .args[0] = 1, .args[1] = 0, .arginfo = SCM_ARGS(2), }; pr_notice("Going down for restart now\n"); msm_restart_prepare(cmd); //程序走到这里#ifdef CONFIG_MSM_DLOAD_MODE /* * Trigger a watchdog bite here and if this fails, * device will take the usual restart path. */ if (WDOG_BITE_ON_PANIC && in_panic) msm_trigger_wdog_bite();#endif /* Needed to bypass debug image on some chips */ if (!is_scm_armv8()) ret = scm_call_atomic2(SCM_SVC_BOOT, SCM_WDOG_DEBUG_BOOT_PART, 1, 0); else ret = scm_call2_atomic(SCM_SIP_FNID(SCM_SVC_BOOT, SCM_WDOG_DEBUG_BOOT_PART), &desc); if (ret) pr_err("Failed to disable secure wdog debug: %d\n", ret); halt_spmi_pmic_arbiter(); deassert_ps_hold(); mdelay(10000);}
msm_restart_prepare(cmd); 参数为("recovery")kernel/drivers/power/reset/msm-poweroff.cstatic void msm_restart_prepare(const char *cmd){#ifdef CONFIG_MSM_SUBSYSTEM_RESTART extern char panic_subsystem[];#endif /* CONFIG_MSM_SUBSYSTEM_RESTART */ bool need_warm_reset = false;#ifdef CONFIG_MSM_DLOAD_MODE /* Write download mode flags if we're panic'ing * Write download mode flags if restart_mode says so * Kill download mode if master-kill switch is set */ set_dload_mode(download_mode && (in_panic || restart_mode == RESTART_DLOAD));#endif if (qpnp_pon_check_hard_reset_stored()) { /* Set warm reset as true when device is in dload mode * or device doesn't boot up into recovery, bootloader or rtc. */ if (get_dload_mode() || ((cmd != NULL && cmd[0] != '\0') && strcmp(cmd, "recovery") && strcmp(cmd, "bootloader") && strcmp(cmd, "rtc"))) need_warm_reset = true; } else { need_warm_reset = (get_dload_mode() || (cmd != NULL && cmd[0] != '\0')); } /* Hard reset the PMIC unless memory contents must be maintained. */ if (need_warm_reset || restart_mode == RESTART_DLOAD) {// MODIFIED by xin.peng, 2016-03-21, BUG-1761259 qpnp_pon_system_pwr_off(PON_POWER_OFF_WARM_RESET); } else { qpnp_pon_system_pwr_off(PON_POWER_OFF_HARD_RESET); } if (cmd != NULL) { if (!strncmp(cmd, "bootloader", 10)) { qpnp_pon_set_restart_reason( PON_RESTART_REASON_BOOTLOADER); __raw_writel(0x77665500, restart_reason); } else if (!strncmp(cmd, "recovery", 8)) { qpnp_pon_set_restart_reason( PON_RESTART_REASON_RECOVERY); __raw_writel(0x77665502, restart_reason); //********************
else if (!strcmp(cmd, "rtc")) { qpnp_pon_set_restart_reason( PON_RESTART_REASON_RTC); __raw_writel(0x77665503, restart_reason); } else if (!strncmp(cmd, "oem-", 4)) { unsigned long code; int ret; ret = kstrtoul(cmd + 4, 16, &code); if (!ret) __raw_writel(0x6f656d00 | (code & 0xff), restart_reason); if (download_mode && (code & 0xff) == 0x3a) set_dload_mode(1); } else if (!strncmp(cmd, "edl", 3)) { enable_emergency_dload_mode(); } else { __raw_writel(0x77665501, restart_reason); } }#ifdef CONFIG_MSM_SUBSYSTEM_RESTART if (in_panic) { printk(KERN_ERR "subsystem %s crash\n", panic_subsystem); if (!memcmp(panic_subsystem, "modem", 5)) { __raw_writel(0x6f656dc1, restart_reason); } else if (!memcmp(panic_subsystem, "wcnss", 5)) { __raw_writel(0x6f656dc2, restart_reason); } else if (!memcmp(panic_subsystem, "adsp", 4) || !memcmp(panic_subsystem, "ADSP", 4)) { __raw_writel(0x6f656dc3, restart_reason); } else if (!memcmp(panic_subsystem, "venus", 5)) { __raw_writel(0x6f656dc4, restart_reason); } else { __raw_writel(0x6f656dc0, restart_reason); } if (download_mode) set_dload_mode(1); }#endif /* CONFIG_MSM_SUBSYSTEM_RESTART *///add begin by liping.gao,Powering on mode switch to 9008 mode,task:665748 if (restart_mode == RESTART_DLOAD) { enable_emergency_dload_mode(); }//add end by liping.gao flush_cache_all(); /*outer_flush_all is not supported by 64bit kernel*/#ifndef CONFIG_ARM64 outer_flush_all();#endif}__raw_writel(0x77665502, restart_reason); //在地址上0x77665502写入"recovery"
应用执行升级/清缓存/重置等操作导致底层在地址0x77665502写入"recovery"
当开机以后，在lk阶段会判断这个地址的值，如果是recovery，会设置boot_into_recovery=1,然后读取recovery.img镜像，把recovery.img的地址和ramdisk等信息作为参数启动kernel，从而进入recovery模式，下面进行简单的分析。
lk阶段：
bootable/bootloader/lk/app/aboot/aboot.c......#define RECOVERY_MODE 0x77665502......reboot_mode = check_reboot_mode();hard_reboot_mode = check_hard_reboot_mode();if (reboot_mode == RECOVERY_MODE || hard_reboot_mode == RECOVERY_HARD_RESET_MODE) { boot_into_recovery = 1; }.....
原标题：Recovery启动流程
关键词：
我知道了 