[Android-Frameworks] Analysis init.rc in Android

最新推荐文章于 2024-08-02 18:12:25 发布

原创最新推荐文章于 2024-08-02 18:12:25 发布 · 106 阅读

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本文详细介绍了如何配置init.rc文件，将其从vendor目录下的文件整合到AndroidBoard.mk中。并通过验证步骤检查了文件的位置和关键属性。此外，解释了init.rc文件的解析过程及其在Android启动过程中的作用。

Android Init.rc Anslysis

如何配置init.rc

-
our init.*.rc files to this one via use of the Android.mk
PRODUCT_INIT_RC_FILES variable. See AndroidBoard.mk.
-

-
./vendor/intel/mfld_pr2/AndroidBoard.mk

     - /vendor/intel/common/init.rc

     - Android board dependence
-

-
比较后可能的位置
     /system/core/rootdir/init.rc
          -YES
     /device/intel/aboot/fastboot/etc/init.rc
          -NO
-

-
验证: 添加关键字"LEON_fastboot", "LEON_rootdir"
     *
     on property:sys.usb.config=LEON_ROOTDIR
    stop adbd
     *

     *
     on property:sys.usb.config=LEON_FASTBOOT
    stop adbd
     *
-

find . -name '*.rc' -print | xargs grep -inr 'mtp'

./out/target/product/mfld_pr2/recovery/root/init.rc:89:on property:sys.usb.config=mtp,adb
./out/target/product/mfld_pr2/root/init.rc:829:on property:sys.usb.config=mtp
./out/target/product/mfld_pr2/root/init.rc:842:on property:sys.usb.config=mtp,adb
./out/target/product/mfld_pr2/droidboot/root/init.rc:65:on property:sys.usb.config=mtp,adb
./bootable/recovery/etc/init.rc:89:on property:sys.usb.config=mtp,adb
./bootable/droidboot/init.rc:65:on property:sys.usb.config=mtp,adb
./device/samsung/tuna/init.tuna.usb.rc:11:on property:sys.usb.config=mtp
./device/samsung/tuna/init.tuna.usb.rc:19:on property:sys.usb.config=mtp,adb
./device/intel/aboot/fastboot/etc/init.rc:55:on property:sys.usb.config=mtp,adb
./device/moto/wingray/init.stingray.usb.rc:9:on property:sys.usb.config=mtp
./device/moto/wingray/init.stingray.usb.rc:17:on property:sys.usb.config=mtp,adb
./hardware/intel/factory/etc/init.rc:53:on property:sys.usb.config=mtp,adb
./vendor/intel/medfield/init.mfld.usb.rc:79:on property:sys.usb.config=mtp                    <=== This is what I want!
./vendor/intel/medfield/init.mfld.usb.rc:92:on property:sys.usb.config=mtp,adb

****
./vendor/intel/medfield/init.mfld.usb.rc
****

2. 谁在解析init.rc文件

Android启动后通过init process完成解析init.rc任务，通过search init.rc中调用"int main"入口的代码。即是init process实现代码。

system/core/init/init.c

Android.mk
- LOCAL_SRC_FILES := ... \
- - property_service.c \
  - parser.c \
  - ueventd.c \
  - ueventd_parser.c \
  - init_parser.c \
- LOCAL_MODULE := init
queue buildin action
start property service, create socket, listen it
read init.rc property flagment, add to local queue
when set property, occure MSG_SET to property service

init process invoke property_service, property_service read local 'property', like this

#define PROP_PATH_RAMDISK_DEFAULT "/default.prop"

          #define PROP_PATH_SYSTEM_BUILD "/system/build.prop"
          #define PROP_PATH_SYSTEM_DEFAULT        "/system/default.prop"
          #define PROP_PATH_LOCAL_OVERRIDE "/data/local.prop"
          //niuhuiling add systemprop
          #define PROP_PATH_SYSTEM_PROP "/system/etc/system.prop"