Condroid

Android Container

Detailed steps

Step I :Compile Android Kernel

  1. Download source code;Kernel's subproject has kernel source code corresponding to the devices here:

     https://android.googlesource.com

    You can find kernel source code path corresponding to your device here

     http://source.android.com/source/building-kernels.html

    Download of this git project is slow,you can use bitbucket or deveo to transfer

  2. checkout branch;Change to the source directory,use

     $ git branch -a

    View all branches,then use

     $ git checkout <branch_name>

    Check codes,here branch_name may have remotes/origin prefix,and there is no need to add -b option,else it will create a new branch

  3. Configuration compiling environment;Clone this repo(you may need transfer):

     https://android.googlesource.com/platform/prebuilts/gcc/linux-x86/arm/arm-eabi-4.6

    set PATH environment variable,add bin directory beneath repo

  4. Compile source code

     $ export ARCH=arm
 $ export SUBARCH=arm
 $ export CROSS_COMPILE=arm-eabi-
 $ make xx_defconfig # (Here you can find) config：http://source.android.com/source/building-kernels.html)
 $ make

    Compiled kernel is arch/arm/boot/zImage（Nexus 5 is zImage-dtb）

  5. Flush a new ROM

    • Method One:set TARGET_PREBUILT_KERNEL environment variable as compiled kernel,then m make boot.img,using

        $ fastboot flash boot boot.img

      Flush

    • Method Two:copy compiled kernel to out/x/x/x/ directory,named after kernel,then m make boot.img,flush with fastboot

Step II :Compile Android Source Code

  1. Download source code;Here you can find Android versions which devices support:

     https://developers.google.com/android/nexus/drivers

  2. Download driver;Here has driver corresponding to devices:

     https://developers.google.com/android/nexus/drivers

    Get a script after download and extract,put it in Android directory to execute

  3. Configuration compiling environment

     System：Ubuntu x86_64 EN
 Package：
     build-essential/gcc&g++/lib32stdc++6
     jdk6
     python 2.6.x/2.7.x
     gperf
     libzip/zlib1g&zlib1g-dev/libzzip-dev
     lib32z1
     bison
     flex
     libxml2-utils
     git
     bc
     zip
     squashfs-tools
     libncurses5-dev

  4. Enter Android source code directory;Execute following command to compile source code:

     $ source build/envsetup.sh
 $ lunch # (choose target corresponding to device)
 $ m

  5. Connecting devices;Execute following command to flush a new ROM(you need run as root):

     $ adb reboot bootloader
 $ fastboot devices
 $ fastboot flashall -w

Step III :Kernel Modification

Conbinder Driver

  1. Enter drivers/staging/android/ directory
  2. Create conbinder.h and conbinder.c
  3. Move the header file of binder.c to conbinder.h,then include "conbinder.h"
  4. Remove static from binder_fops struct's function,then add its declaration in conbinder.h
  5. Add CONBINDER_GET_CURRENT_CONTAINER macro definition in conbinder.h(ioctl operation gets container's ID in which current process is)
  6. Add virtual driver code in conbinder.c
  7. Modify binder_ioctl function in binder.c,add treatment codes of CONBINDER_GET_CURRENT_CONTAINER command
  8. Modify Kconfig,add ANDROID_CONBINDER_IPC option
  9. Modify Makefile,add conbinder.o compilation configuration

Conalarm Driver

  1. Enter drivers/rtc/ directory
  2. Modify alarm-dev.c,add conalarm_fops and conalarm_device data struct,initialize code and customize conalarm_open function
  3. Using macro definition-ANDROID_CONALARM to control relevant conalarm code if compiled
  4. Modify Kconfig,add ANDROID_CONALARM_DEV option
  5. Modify Makefile,add compilation configuration(ccflags) of macro definition ANDROID_CONALARM

Container Driver

  1. Enter drivers/staging/android/ directory
  2. Create container.h and container.c
  3. Add macro definition of ioctl command in container.h
  4. Add driver function,data struct and initialization code of container device in container.c
  5. Modify Kconfig,add ANDROID_CONTAINER option
  6. Modify Makefile,add container.o compilation configuration

Compile Configuration

  1. Modify .config,add following compilation configuration options

     ANDROID_CONBINDER_IPC
 ANDROID_CONALARM_DEV
 ANDROID_CONTAINER
 IKCONFIG
 IKCONFIG_PROC
  2. According to lxc-checkconfig,add compilation configuration options
  3. According toStep II,compile

Step IV :ramdisk modification

init.rc

  1. Remove

     mount rootfs rootfs / ro remount

  2. Add

     mount tmpfs tmpfs /run
 symlink /system/bin /bin

  3. Add it after PATH environment variable

     :/system/busybox/bin:/system/busybox/sbin:/system/local/bin

  4. Add it after LD_LIBRARY_PATH:

     :/system/local/lib

  5. Add

     export ANDROID_CT /system/local/var/lib/lxc/android4.x.x

uevent.rc

  1. Add

     /dev/conbinder1         0666    root        root
 ...
 /dev/conbinder9         0666    root        root

  2. Add

     /dev/conalarm           0664   system     radio

  3. Add

     /dev/container          0666    root        root

Step V ：LXC Modification and Compilation

Code modification

  1. Use chroot to replace pivot_root system call

Cross compilinglxc

  1. Download Android NDK

  2. Extract NDK,then execute in it

     $ build/tools/make-standalone-toolchain.sh

    Find tool chain in /tmp directory

  3. Add tool chain directory after PATH environment variable

  4. Download lxc-1.0.0.alpha* source code

  5. Execute in lxc source code

     $ autogen.sh

  6. Execute

     $ ./configure --host=arm-linux-androideabi --prefix=/system/local CC=arm-linux-androideabi-gcc --disable-capabilities
  7. Execute 'make',ignore relevant lua wrong

  8. Execute

     $ sudo make prefix=/system/local install

    You can find compiled procedure in /system/local

Step VI ：Modify system partitions

Busybox

Put compiled busybox in system directory

LXC

Pack the folders in lxc's installation directory,then extractit in /system/local directory

Cgroups

  1. Create cgroup directory beneath /system/,and Create following directory beneath cgroup

     cpuset
 memory
 blkio
 freezer
 device

  2. Create script file mount-cgroups.sh beneath /system/local/bin,to mount cgroups and ashmem;command is following:

     for t in `ls /system/cgroup`
 do
     mount -t cgroup -o $t cgroup /system/cgroup/$t
 done

 mkdir /dev/shm
 mount -t tmpfs -o nodev,noexec tmpfs /dev/shm

ServiceManager

  1. Modify filter rule of service name,allow registering modified service

Container configure and root filesystem

  1. Create folder androidx.x.x beneath /system/local/var/lib/lxc to save container system
  2. Create file config and directory rootfs within the folder

config

lxc.utsname = android4.1.2
lxc.tty = 0
lxc.rootfs = /system/local/var/lib/lxc/android4.1.2/rootfs
lxc.cgroup.devices.allow = a

rootfs

  1. Copy all files beneath original system root directory to rootfs directory
  2. Create symbolic Links corresponding to original system root directory

  3. Create directories beneath system root directory,following the principles:(copy means copying directories of host;empty means creating a empty directory；the same below)

     /firmware       copy
 /persist        copy
 /storage        empty
 /config         copy
 /cache          empty
 /acct           empty
 /mnt            empty
 /sys            empty
 /sbin           empty
 /run            empty
 /res            copy
 /proc           empty
 /data           empty
 /root           empty
 /dev            empty
 /system         empty
  4. Create device nodes in rootfs/dev,according to filename,device number,permission and owner of all device files

  5. Create folder and directory beneath system directory,as following rules:

     app                 empty
 bin                 copy
 build.prop          copy
 busybox             copy
 etc                 copy
 fonts               copy
 framework           empty
 lib                 empty
 media               empty
 priv-app            empty
 tts                 copy
 usr                 copy
 vendor              copy
 xbin                copy

Other Script

  1. Create script file mount-bind.sh in android4.x.x directory,Enter the following command：

     mount -o bind /system/app rootfs/system/app
 mount -o bind /system/framework rootfs/system/framework
 mount -o bind /system/lib rootfs/system/lib
 mount -o bind /system/media rootfs/system/media
 mount -o bind /system/priv-app rootfs/system/priv-app

 mount -o bind /dev/conbinder1 rootfs/dev/binder
 mount -o bind /dev/conalarm rootfs/dev/alarm

  2. Create script file share.sh in android4.x.x directory,Enter the following command：

     echo "SurfaceFlinger" >>/proc/conbinder/sharedservices

init

  1. Forbid creating /dev directory
  2. Forbid mounting tmpfs on /dev directory

init.rc

  1. Forbidden ueventd
  2. Forbidden servicemanager

Step VII :Start Container

  1. Start host

  2. Enter shell using following command as root:

     # adb root
 # adb shell

  3. Execute following command to mount various folders:

     # mount-rw.sh
 # mount-cgroups.sh

  4. Enter directory in which container is,and execute following command:

     # ./mount-bind.sh
 # ./share.sh

  5. Execute following command to clear log:

     # dmesg -c
 # logcat -c

  6. Execute following command to start container：

     lxc-start -n <container name>