客户在Android5.1 ROM上开发的应用，想适配到定制的Android8.1版本上，由不想多改app代码，那只能在ROM端想办法解决了。以下就是碰到问题以及解决方法。

1.连续点击某些页面跳转时候，页面各种乱跳。

原因参考: windowIsTranslucent引发的血案
找到原因就好办，由于app使用了windowIsTranslucent导致，framework把获取windowIsTranslucent配置地方处理掉。

ALPS/frameworks/base/services/core/java/com/android/server/am/ActivityRecord.java 
public final class ActivityRecord extends ConfigurationContainer implements
 
         Entry ent = AttributeCache.instance().get(packageName,
                 realTheme, com.android.internal.R.styleable.Window, userId);
+        /*
         final boolean translucent = ent != null && (ent.array.getBoolean(
                 com.android.internal.R.styleable.Window_windowIsTranslucent, false)
                 || (!ent.array.hasValue(
                         com.android.internal.R.styleable.Window_windowIsTranslucent)
                         && ent.array.getBoolean(
                                 com.android.internal.R.styleable.Window_windowSwipeToDismiss,
-                                        false)));
+                                        false)));*/
+        final boolean translucent = false;                                
+
         fullscreen = ent != null && !ent.array.getBoolean(
                 com.android.internal.R.styleable.Window_windowIsFloating, false) && !translucent;

2.app在其他平台使用的是ttyMFD1串口通信，固定了，库没法修改

解决方法在init.rc使用软链接（前提是我们平台没有ttyMFD1串口）

 symlink /dev/ttyMT1 /dev/ttyMFD1

3.app后台服务被频繁杀死

原因参考:Android8.0 启动后台Service问题
ROM修改

 ALPS/frameworks/base/services/core/java/com/android/server/am/ActiveServices.java 
             r.fgWaiting = false;
             mAm.mHandler.removeMessages(
                     ActivityManagerService.SERVICE_FOREGROUND_TIMEOUT_MSG, r);
+            /*
             if (r.app != null) {
                 Message msg = mAm.mHandler.obtainMessage(
                         ActivityManagerService.SERVICE_FOREGROUND_CRASH_MSG);
                 msg.obj = r.app;
                 mAm.mHandler.sendMessage(msg);
             }
+            */
         }
 
         if (DEBUG_SERVICE) {

 ALPS/frameworks/base/services/core/java/com/android/server/am/ActiveServices.java 
index 184a7a8..f9c9841 100755
@@ -106,7 +106,7 @@ public final class ActiveServices {
 
     // How long the startForegroundService() grace period is to get around to
     // calling startForeground() before we ANR + stop it.
-    static final int SERVICE_START_FOREGROUND_TIMEOUT = 5*1000;
+    static final int SERVICE_START_FOREGROUND_TIMEOUT = 10*1000;
 
     final ActivityManagerService mAm;
 
@@ -3421,11 +3421,14 @@ public final class ActiveServices {
         if (r.app.executingServices.size() == 0 || r.app.thread == null) {
             return;
         }
+
+        /*
         Message msg = mAm.mHandler.obtainMessage(
                 ActivityManagerService.SERVICE_FOREGROUND_TIMEOUT_MSG);
         msg.obj = r;
         r.fgWaiting = true;
         mAm.mHandler.sendMessageDelayed(msg, SERVICE_START_FOREGROUND_TIMEOUT);
+        */
     }
 
     final class ServiceDumper {

4.App悬浮上层，权限报错

 ALPS/frameworks/base/core/java/android/app/AppOpsManager.java
@@ -915,7 +915,7 @@ public class AppOpsManager {
             AppOpsManager.MODE_ALLOWED,
             AppOpsManager.MODE_ALLOWED,
             AppOpsManager.MODE_DEFAULT, // OP_WRITE_SETTINGS
-            AppOpsManager.MODE_DEFAULT, // OP_SYSTEM_ALERT_WINDOW
+            AppOpsManager.MODE_ALLOWED, // OP_SYSTEM_ALERT_WINDOW
             AppOpsManager.MODE_ALLOWED,
             AppOpsManager.MODE_ALLOWED,
             AppOpsManager.MODE_ALLOWED,

5.句柄泄漏

进程默认的句柄上线是1024，可以调整延缓出错崩溃，当然更需要找到原因。
延缓方法init.rc

setrlimit 7 4096 4096

监控句柄方法

#!/system/bin/sh
array=(
com.xxx.xxx.xxx.settings
com.xxx.xxx.xxx.settings:remote
)

#超过上限值报警
fdcritical=800

#2秒检测一次
sleeptime=2

function check_fd()
{
    process=$1
    pid=$(pidof $1)
    fdnum=""
    if [ ! -n "$pid" ]; then
        pid="null"
    else
        fdnum=$(ls /proc/$pid/fd/ | wc -w)
        if [ $fdnum -ge $fdcritical ];then
            echo "warning!" $process $pid $fdnum
        fi
    fi
}
while [ "1" = "1" ]
do
for element in ${array[@]}
do
check_fd $element
done
sleep $sleeptime
done

6.USB TP插拔会界面会闪烁

--- ALPS/frameworks/base/core/java/android/content/res/Configuration.java ----
old mode 100644
new mode 100755
index f7cccd5..f7cd2b7
@@ -388,9 +388,11 @@ public final class Configuration implements Parcelable, Comparable

Android8.1 适配Android5.1 APP