android note

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1.重要的property属性

 #define ANDROID_RB_PROPERTY "sys.powerctl"  // 控制启动状态 property_set(ANDROID_RB_PROPERTY, "shutdown,"); property_set(ANDROID_RB_PROPERTY, "reboot,bootloader"); property_set(ANDROID_RB_PROPERTY, "reboot,"); property_set(ANDROID_RB_PROPERTY, "reboot,edl");

2.propety属性的管理

init.c

   if (is_charger)        {                action_for_each_trigger("charger", action_add_queue_tail);        }        else        {                if (is_ffbm)                {                         action_for_each_trigger("ffbm", action_add_queue_tail);                }                else                {                        // 正常开机模式进入最后的 late-init 阶段                        action_for_each_trigger("late-init", action_add_queue_tail);                }        }

init.rc

on late-init     trigger load_all_props_action  // 在late-init阶段加载所有的属性----------on load_all_props_action    load_all_props

keywords.h property_service.c

    KEYWORD(load_all_props,  COMMAND, 0, do_load_all_props)        //keywords.h                                            -> do_load_all_props   // builtins.c                                                ->load_all_props   // property_service.c                                                    // 依次从下面几个路径中加载所有的属性                                                    "system/build.prop"  (常用)                                                    "system/default.prop"

build/tools/buildinfo.sh

☆ 生成 system/build.prop 文件，需要添加prop只需要在这个编译脚本中添加即可！！！

in system/build.prop# begin build properties  3 # autogenerated by buildinfo.sh  4 ro.build.id=LMY47V  5 ro.build.display.id=LMY47V.WW_Phone.12.0.0.020-20160719_userdebug  6 ro.build.display.wtid=LMY47V.WW_Ph

3.属性值的获取设置

1. 在system.prop里面添加需要使用的系统属性，添加完后需要编译生成system.img2. 在native层，使用property_set(...)和property_get(...)来存取系统属性3. 在Java层， 使用SystemProperties.set(...)和SystemProperties.get(...)来存取系统属性4. 在adb shell命令行，使用getprop和setprop来存取系统属性

3.charger

# init.rcon charger    class_start charger----------# init.qcom.rcservice charger /charger    class charger----------#system/core/healthd/Android.mk LOCAL_MODULE := healthd...# Symlink /charger to /sbin/healthd

4.屏幕截图 & 屏幕录制

adb shell screencap /sdcard/test.pngadb shell screenrecord  sdcard/sss.mp4

5.关闭selinux

setenforce 0

6.adb devices 串号

(1)init.rc

 write /sys/class/android_usb/android0/iSerial ${ro.serialno}

(2)cat /pro/cmdline

adb root;adb shell cat /proc/cmdline

androidboot.serialno=YOGABOOK12

(3)init.cpp

process_kernel_cmdline  ->import_kernel_cmdline(false, import_kernel_nv);   ->import_kernel_nv----------    char *value = strchr(name, '=');    (!strncmp(name, "androidboot.", 12) && name_len > 12) {        char *boot_prop_name = name + 12;        char prop[PROP_NAME_MAX];        snprintf(prop, sizeof(prop), "ro.boot.%s", boot_prop_name);           property_set(prop, value);           } ----------static void export_kernel_boot_props() {    struct {        const char *src_prop;        const char *dst_prop;        const char *default_value;    } prop_map[] = {        ...        { "ro.boot.serialno",   "ro.serialno",   "", },        ...    };

7.system/bin/input 命令

demo

 input keyevent   keycodeNum    //4 表示KEYCODE_BACK

常用的几种事件：

//键值对应 android/keycodes.h26 --> KEYCODE_POWER         // 电源 82 -->  "KEYCODE_MENU"     //菜单3 -->  "KEYCODE_HOME"       //返回home4 -->  "KEYCODE_BACK"       //返回上一级菜单19 -->  "KEYCODE_DPAD_UP"           //向上20 -->  "KEYCODE_DPAD_DOWN"     //向下21 -->  "KEYCODE_DPAD_LEFT"     //向左22 -->  "KEYCODE_DPAD_RIGHT"        //向右24 -->  "KEYCODE_VOLUME_UP"     //音量加25 -->  "KEYCODE_VOLUME_DOWN"   //音量减66 -->  "KEYCODE_ENTER"     //确定键

8. 重新挂载某个分区

mount -o remount,rw system system

9.命令行查看分辨率

frameworks/base/cmds/wm/

窗口分辨率

wm size

10.android init阶段 bootanimation之前的一张启动画面

// 在init.c中通过 “console_init” 这个action触发    queue_builtin_action(console_init_action, "console_init");

11.aplog

1.位置

/data/logs/aplog.ndata/local/log/aplog

2.crash信息

//logs\crashlog0_72612f74d4e263a53665\crashfile 中表明了crash原因EVENT=CRASHID=61c96fdba2162a052323SN=4cca94f595db403f749622792dfe73a6167ded48DATE=2016-10-08/08:09:56  UPTIME=0000:00:19BUILD=YB-Q501L_USR_S000014_1610010228_WW12_ROW,Lenovo/yogi_12_row_lte/YOGABOOK12:6.0.1/MMB29M/1610010228:user/release-keys,3.14.55-x86_64,queen@fyy-SMBIOSfyy,unknown,YOGI.T2000AH.V015,,,,BOARD=Lenovo YB-Q501LIMEI=TYPE=SWWDT_UNHANDLED  // crash 类型 看门狗DATA_READY=1OPERATOR=UNKNOWNDATA0=SWWDT_RESET //_END----------EVENT=CRASHID=72612f74d4e263a53665SN=7f406c2f2e2675c73a5a85d52a237d80f747c2eaDATE=2016-10-07/21:23:08  UPTIME=0000:00:22BUILD=YB-Q501L_USR_S000014_1610010228_WW12_ROW,Lenovo/yogi_12_row_lte/YOGABOOK12:6.0.1/MMB29M/1610010228:user/release-keys,3.14.55-x86_64,queen@fyy-SMBIOSfyy,unknown,YOGI.T2000AH.V015,,,,BOARD=Lenovo YB-Q501LIMEI=TYPE=IPANIC    // // crash 类型 kernel panicDATA_READY=1OPERATOR=UNKNOWN_END

3. ” BUG: “

搜索“ BUG： ”会有栈回溯或者null point信息

2.kernel启动信息/重启信息

beginning of kernel
10-07 21:22:46.780 0 0 I KERNEL : [ 0.000000] Initializing cgroup subsys cpuset
10-07 21:22:46.780 0 0 I KERNEL : [ 0.000000] Initializing cgroup subsys cpu
10-07 21:22:46.780 0 0 I KERNEL : [ 0.000000] Initializing cgroup subsys cpuacct
10-07 21:22:46.780 0 0 I KERNEL : [ 0.000000] Linux version 3.14.55-x86_64 (queen@fyy-SMBIOSfyy) (gcc version 4.9.2 (GCC) ) #1 SMP PREEMPT Sat Oct 1 03:04:35 CST 2016
10-07 21:22:46.780 0 0 I KERNEL : [ 0.000000] Command line: androidboot.bootloader=yogi_t2000ah_v015_kernelflinger-02_1f androidboot.diskbus=10.0 androidboot.verifiedbootstate=green androidboot.bootreason=kernel_panic androidboot.mode=0 :

12. 指定工程的 .config

KERNEL_DEFCONFIG

device/intel/cherrytrail/cht_ffd/AndroidBoard.mk

13. Android.mk中添加打印

 $(warning "print info")

14.U盘插入拔出打印

1.mountservice 完整流程

     MountService: Volume public:8,1 broadcasting checking to UserHandle{0}  // 插入后检测挂载     MountService: Volume public:8,1 broadcasting mounted to UserHandle{0}     MountService: Volume public:8,1 broadcasting ejecting to UserHandle{0}  // 点击弹出umount     MountService: Volume public:8,1 broadcasting unmounted to UserHandle{0}     MountService: Volume public:8,1 broadcasting removed to UserHandle{0}  // 拔出U盘

2.kernelU盘插入拔出kernel打印

 usb 2-1: new SuperSpeed USB device number 2 using xhci_hcd       // 插上 30375936 512-byte logical blocks: (15.5 GB/14.4 GiB)             // 读取大小 USB disconnect, device number                                    // 拔出

15.U盘插入拔出mount/umount代码流程

1.监听subsystem为block 的uevent事件

    NetlinkHandler::onEvent        VolumeManager::handleBlockEvent            case add:                Disk::create   // disk.cpp                      disk::readMetadata();                      disk::readPartitions();                      notifyEvent(ResponseCode::DiskCreated, StringPrintf("%d", mFlags));            case chager:                  disk::readMetadata();                  disk::readPartitions();            case remove:                Disk::destroy()                    destroyAllVolumes();                    notifyEvent(ResponseCode::DiskDestroyed);

2.发送广播

    Disk::notifyEvent             VolumeManager::Instance()->getBroadcaster()->sendBroadcast

3.mountService接收来着vold的广播

    MountService.onEvent        MountService.onEventLocked            case VoldResponseCode.VOLUME_STATE_CHANGED:  //每一次状态的改变都会调用这个分支                    onVolumeStateChangedLocked(vol, oldState, newState);  // 状态改变做相应操作                        mHandler.obtainMessage(H_VOLUME_BROADCAST, userVol).sendToTarget();  // mountService发广播给mountService

3.mountService接收来着mountService的广播

MountServiceHandler.handleMessage  //接收广播    case H_VOLUME_MOUNT:         // 挂载        mConnector.execute("volume", "mount", vol.id, vol.mountFlags,vol.mountUserId);    case H_VOLUME_BROADCAST:      // 发送广播给用户告知状态        Slog.d(TAG, "Volume " + userVol.getId() + " broadcasting " + envState + " to "+ userVol.getOwner());        mContext.sendBroadcastAsUser(intent, userVol.getOwner());

16.查看android分区及dd命令烧写分区

#ls /dev/block/by-name/    android_boot    android_bootloader    android_bootloader2    android_cache    android_config    android_data    android_factory    android_metadata    android_misc    android_persistent    android_recovery    android_system----------push boot.img到及机子的任意目录,在此目录执行 ,dd if=boot.img of=/dev/block/by-name/android_boot,重启之后,boot.img烧写成功.其他分区也类似.

11.android 各层次获取时间的方法

1. 在Java层，long now = SystemClock.uptimeMillis();2. 在native层，nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC);3. 在驱动层，s64 time = ktime_to_us(ktime_get());

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