上面是說到 activity的啟動，看到程序啟動的地方就結束了。
現在看看process的啟動過程

  final ProcessRecord startProcessLocked(String processName, ApplicationInfo info,
            boolean knownToBeDead, int intentFlags, String hostingType, ComponentName hostingName,
            boolean allowWhileBooting, boolean isolated, int isolatedUid, boolean
 
 keepIfLarge,
            String abiOverride, String entryPoint, String[] entryPointArgs, Runnable crashHandler) {
        long startTime = SystemClock.elapsedRealtime();
        ProcessRecord app;

   //app ==null的時候，是全新啟動一個應用，上面的程式碼略過

        if (app == null) {
            checkTime(startTime, "startProcess: creating new process record"
 
);

 //根據上面 啟動activity 讀到的 ApplicationInfo 建立相應的processinfo
 //在系統的pkglist中 註冊應用的packagename 等等，填寫相應的uid 之類的資訊。

            app = newProcessRecordLocked(info, processName, isolated, isolatedUid);
            if (app == null) {
                Slog.w(TAG, "Failed making new process record for "
                        + processName + "/"
 
 + info.uid + " isolated=" + isolated);
                return null;
            }

            //此時的crashHandler 還是null

            app.crashHandler = crashHandler;
            mProcessNames.put(processName, app.uid, app);
            if (isolated) {
                mIsolatedProcesses.put(app.uid, app);
            }
            checkTime(startTime, "startProcess: done creating new process record");
        } else {
            // If this is a new package in the process, add the package to the list
            app.addPackage(info.packageName, info.versionCode, mProcessStats);
            checkTime(startTime, "startProcess: added package to existing proc");
        }

        // If the system is not ready yet, then hold off on starting this
        // process until it is.
        if (!mProcessesReady
                && !isAllowedWhileBooting(info)
                && !allowWhileBooting) {
            if (!mProcessesOnHold.contains(app)) {
                mProcessesOnHold.add(app);
            }
            if (DEBUG_PROCESSES) Slog.v(TAG, "System not ready, putting on hold: " + app);
            checkTime(startTime, "startProcess: returning with proc on hold");
            return app;
        }

        checkTime(startTime, "startProcess: stepping in to startProcess");
        startProcessLocked(
                app, hostingType, hostingNameStr, abiOverride, entryPoint, entryPointArgs);
        checkTime(startTime, "startProcess: done starting proc!");
        return (app.pid != 0) ? app : null;
    }



真正的啟動 startProcessLocked（）

private final void startProcessLocked(ProcessRecord app, String hostingType,
String hostingNameStr, String abiOverride, String entryPoint, String[] entryPointArgs) {
long startTime = SystemClock.elapsedRealtime();
if (DEBUG_PROCESSES && mProcessesOnHold.contains(app)) Slog.v(TAG,
“startProcessLocked removing on hold: ” + app);
mProcessesOnHold.remove(app);

    //喚醒cpu
    updateCpuStats();


    try {
        int uid = app.uid;

//略過 給process 標記debug 標誌

//cpu 型別
String requiredAbi = (abiOverride != null) ? abiOverride : app.info.primaryCpuAbi;
if (requiredAbi == null) {
requiredAbi = Build.SUPPORTED_ABIS[0];
}

        String instructionSet = null;
        if (app.info.primaryCpuAbi != null) {
            instructionSet = VMRuntime.getInstructionSet(app.info.primaryCpuAbi);
        }

//填寫配置檔案

        boolean isActivityProcess = (entryPoint == null);
        if (entryPoint == null) entryPoint = "android.app.ActivityThread";
        checkTime(startTime, "startProcess: asking zygote to start proc");

//這個就是大名鼎鼎的 孵化器了
//zygote process 大概描述一下，向zygote process傳送請求，申請一個新
//的程序，並把這個程序的pid返回回來，這樣一個新的程序就被創建出來了。
//連同這activitythread 直接被創建出來process 直接執行main函式，主執行緒也被創建出來

        Process.ProcessStartResult startResult = Process.start(entryPoint,
                app.processName, uid, uid, gids, debugFlags, mountExternal,
                app.info.targetSdkVersion, app.info.seinfo, requiredAbi, instructionSet,
                app.info.dataDir, entryPointArgs);
        checkTime(startTime, "startProcess: returned from zygote!");

        if (app.isolated) {
            mBatteryStatsService.addIsolatedUid(app.uid, app.info.uid);
        }
        mBatteryStatsService.noteProcessStart(app.processName, app.info.uid);
        checkTime(startTime, "startProcess: done updating battery stats");

        EventLog.writeEvent(EventLogTags.AM_PROC_START,
                UserHandle.getUserId(uid), startResult.pid, uid,
                app.processName, hostingType,
                hostingNameStr != null ? hostingNameStr : "");

        if (app.persistent) {
            Watchdog.getInstance().processStarted(app.processName, startResult.pid);
        }

        checkTime(startTime, "startProcess: building log message");
        StringBuilder buf = mStringBuilder;
        buf.setLength(0);
        buf.append("Start proc ");
        buf.append(startResult.pid);
        buf.append(':');
        buf.append(app.processName);
        buf.append('/');
        UserHandle.formatUid(buf, uid);
        if (!isActivityProcess) {
            buf.append(" [");
            buf.append(entryPoint);
            buf.append("]");
        }
        buf.append(" for ");
        buf.append(hostingType);
        if (hostingNameStr != null) {
            buf.append(" ");
            buf.append(hostingNameStr);
        }
        Slog.i(TAG, buf.toString());
        app.setPid(startResult.pid);
        app.usingWrapper = startResult.usingWrapper;
        app.removed = false;
        app.killed = false;
        app.killedByAm = false;
        checkTime(startTime, "startProcess: starting to update pids map");
        synchronized (mPidsSelfLocked) {
            this.mPidsSelfLocked.put(startResult.pid, app);
            if (isActivityProcess) {
                Message msg = mHandler.obtainMessage(PROC_START_TIMEOUT_MSG);
                msg.obj = app;
                mHandler.sendMessageDelayed(msg, startResult.usingWrapper
                        ? PROC_START_TIMEOUT_WITH_WRAPPER : PROC_START_TIMEOUT);
            }
        }
        checkTime(startTime, "startProcess: done updating pids map");
    } catch (RuntimeException e) {
        // XXX do better error recovery.
        app.setPid(0);
        mBatteryStatsService.noteProcessFinish(app.processName, app.info.uid);
        if (app.isolated) {
            mBatteryStatsService.removeIsolatedUid(app.uid, app.info.uid);
        }
        Slog.e(TAG, "Failure starting process " + app.processName, e);
    }
}

“`