Android 4.2.2 Emulate Sdcard

参考链接: source.android.com

由于官方提供的参考方法不能使用, 所以我把修改的配置贴了出来

init.hardware.rc

on post-fs-data
    mkdir /data/media 0770 media_rw media_rw
    chown media_rw media_rw /data/media

on init
    mkdir /mnt/shell/emulated 0771 system sdcard_rw
    mkdir /mnt/shell/test 0771 system sdcard_rw
    mkdir /storage/emulated 0775 root root

    export EXTERNAL_STORAGE /storage/emulated/0
    export EMULATED_STORAGE_SOURCE /mnt/shell/emulated
    export EMULATED_STORAGE_TARGET /storage/emulated

    # Support legacy paths
    symlink /storage/emulated/0 /sdcard
    symlink /storage/emulated/0 /mnt/sdcard
    symlink /storage/emulated/0 /storage/sdcard0
    symlink /mnt/shell/emulated/0 /storage/emulated/0

service sdcard /system/bin/sdcard /data/media /mnt/shell/emulated 1023 1023
    disabled

on property:dev.bootcomplete=1
    start sdcard

storage_list.xml

<storage
        android:storageDescription="@string/storage_internal"
        android:emulated="true"
        android:mtpReserve="100" />

实际操作

由于我希望把 mtd@user 这个分区挂载为 ext4 格式，以减少使用FAT32格式导致文件系统不稳定的引发的问题；

所以，我总体思路是，把 mnt@user 以 ext4 文件系统格式挂载到 /mnt/user；

然后再使用 /system/bin/sdcard 模拟一个SDcard出来至 /mnt/sdcard/emulated；

最后再软链接到 /storage/emulated 和 /mnt/sdcard;

init.rk30board.rc

on fs
    mkdir /mnt/user 0770 media_rw media_rw
    mount ext4 mtd@user /mnt/user wait noatime nodiratime nosuid nodev noauto_da_alloc

on post-fs
    chown media_rw media_rw /mnt/user

on post-fs-data
    # we will remap this as /mnt/sdcard with the sdcard fuse tool
    mkdir /data/media 0770 media_rw media_rw
    chown media_rw media_rw /data/media

on init

    mkdir /mnt/shell/emulated 0771 system sdcard_rw
    mkdir /mnt/shell/test 0771 system sdcard_rw
    mkdir /storage/emulated 0775 root root

    export EXTERNAL_STORAGE /storage/emulated/0
    export EMULATED_STORAGE_SOURCE /mnt/shell/emulated
    export EMULATED_STORAGE_TARGET /storage/emulated

    # Support legacy paths
    symlink /storage/emulated/0 /sdcard
    symlink /storage/emulated/0 /mnt/sdcard
    symlink /storage/emulated/0 /storage/sdcard0
    symlink /mnt/shell/emulated/0 /storage/emulated/0

    # create virtual SD card at /mnt/sdcard, based on the /data/media directory
    # daemon will drop to user/group system/media_rw after initializing
    # underlying files in /data/media will be created with user and group media_rw (1023)
    service sdcard /system/bin/sdcard /mnt/user /mnt/shell/emulated 1023 1023
       disabled

    # for emulated sdcard
    on property:dev.bootcomplete=1
        start sdcard

storage_list.xml

<storage
        android:storageDescription="@string/storage_internal"
        android:emulated="true"
        android:mtpReserve="100" />