android emulator初探

android emulator基于qemu开发. 源码位于external/qemu目录下.
但从使用上看,看不出qemu的影子.但实现上emulator与qemu没有太大区别.

以命令行解析为例
使用 ./emulator -debug all 启动,可以看到类似下面的打印:
emulator: argv[00] = "./emulator"
emulator: argv[01] = "-kernel"
emulator: argv[02] = "/home/dybbuk/work/android_dev/mydroid/prebuilt/android-arm/kernel/kernel-qemu"
emulator: argv[03] = "-initrd"
emulator: argv[04] = "/home/dybbuk/work/android_dev/mydroid/out/target/product/generic//ramdisk.img"
emulator: argv[05] = "-nand"
emulator: argv[06] = "system,size=0x4200000,initfile=/home/dybbuk/work/android_dev/mydroid/out/target/product/generic//system.img"
emulator: argv[07] = "-nand"
emulator: argv[08] = "userdata,size=0x4200000,file=/tmp/android/emulator-YrPtDf"
emulator: argv[09] = "-nand"
emulator: argv[10] = "cache,size=0x4200000"
emulator: argv[11] = "-serial"
emulator: argv[12] = "android-kmsg"
emulator: argv[13] = "-serial"
emulator: argv[14] = "stdio"
emulator: argv[15] = "-serial"
emulator: argv[16] = "android-qemud"
emulator: argv[17] = "-append"
emulator: argv[18] = "qemu=1 console=ttyS0 androidboot.console=ttyS1 android.checkjni=1 android.qemud=ttyS2 android.ndns=3"
emulator: argv[19] = "-m"
emulator: argv[20] = "96"
emulator: argv[21] = "-clock"
emulator: argv[22] = "unix"
这些参数就是emulator调用qemu时所用的参数. 你如果用过qemu的话,会对部分参数有些印象.
所以从命令行参数来看,emulator 只不过是对qemu 作了封装, 使得易于使用.

以qemu的文档来分析各个参数的作用:
‘-kernel bzImage’
    Use bzImage as kernel image.
‘-append cmdline’
    Use cmdline as kernel command line
‘-initrd file’
    Use file as initial ram disk.
‘-clock method’
    Force the use of the given methods for timer alarm. To see what timers are available use -clock ?.
‘-m megs’
    Set virtual RAM size to megs megabytes. Default is 128 MiB. Optionally, a suffix of “M” or “G” can be used to signify a value in megabytes or gigabytes respectively.
‘-serial dev’
    Redirect the virtual serial port to host character device dev. The default device is vc in graphical mode and stdio in non graphical mode.
    This option can be used several times to simulate up to 4 serial ports.
‘-nand’
    这个应该是android版的qemu新增的参数.

emulator使用tip:
1.  以终端作为虚拟机的串口以及串口控制台.
添加: -show-kernel -shell 选项.

2. 使用其它的kernel image 文件:
 /home/dybbuk/work/android_dev/mydroid/out/host/linux-x86/bin/emulator -sysdir /home/dybbuk/work/android_dev/mydroid/out/target/product/generic/ -system /home/dybbuk/work/android_dev/mydroid/out/target/product/generic/system.img -ramdisk /home/dybbuk/work/android_dev/mydroid/out/target/product/generic//ramdisk.img -kernel /home/dybbuk/work/android_dev/mydroid/kernel/arch/arm/boot/zImage

fedora 9 编译 Android

android
    主站:http://www.android.com/
    application develop based on the platform: http://developer.android.com/
    platform develop:http://source.android.com/  


源代码的下载说明页面是：http://source.android.com/download
最新的release:Release features


(1) 配置repo账户
git config --global user.email "xxxxx@xxxxxxx"
git config --global user.name "xxxxxx"

（2）开始准备下载android
cd ~/work/android_dev
mkdir mydroid
cd mydroid
../bin/repo init -u git://android.git.kernel.org/platform/manifest.git -b android-1.5

（3）开始下载android platform的源代码
repo sync
这个操作会持续一段时间，看网速了,只有800M左右。

（4）编译
make
我这边编译时间在一小时以上
编译完毕以后，会发现在代码目录下多了一个目录:
~/work/android_dev/mydroid/out

如果报错:
which: no javac in (/usr/lib/qt-3.3/bin:/usr/kerberos/bin:/usr/lib/ccache:/usr/local/bin:/usr/bin:/bin:/opt/real/RealPlayer:/home/dybbuk/bin:/sbin/:/usr/sbin/:/opt/real/RealPlayer)
 则说明你没有安装 jdk 5.0..  去 http://java.sun.com/javase/downloads/5/jdk  下载 jdk  安装后,  设置环境变量:
export ANDROID_JAVA_HOME=/usr/java/jdk1.5.0_18
export PATH=/usr/java/jdk1.5.0_18/bin:$PATH

（5）开始验证生成的结果
export ANDROID_PRODUCT_OUT=~/work/android_dev/mydroid/out/target/product/generic
~/work/android_dev/mydroid/out/host/linux-x86/bin/emulator
应该看到开机的画面(第一次开启的时候，应该还有一个向google反馈的一个对话框，按下确定即可)。


paltform source layout:
Project
    Description
bionic
    C runtime: libc, libm, libdl, dynamic linker
bootloader/legacy
    Bootloader reference code
build
    Build system
dalvik
    Dalvik virtual machine
development
    High-level development and debugging tools
frameworks/base
    Core Android app framework libraries
frameworks/policies/base
    Framework configuration policies
hardware/libhardware
    Hardware abstraction library
hardware/ril
    Radio interface layer
kernel
    Linux kernel
prebuilt     Binaries to support Linux and Mac OS builds
recovery
    System recovery environment
system/bluetooth
    Bluetooth tools
system/core     Minimal bootable environment
system/extras
    Low-level debugging/inspection tools
system/wlan/ti     TI 1251 WLAN driver and tools

===============================================
kernel
===============================================
下载的kernel为manifest 的kernel
用于模拟器的板型为goldfish,所以要编译kernel需要把kernel切换到 goldfish 的分支.
[dybbuk@localhost kernel]$ git branch -r
  korg/android-2.6.25
  korg/android-2.6.27
  korg/android-2.6.29
  korg/android-goldfish-2.6.27
  korg/android-goldfish-2.6.29
  m/android-1.5
  m/master
[dybbuk@localhost kernel]$ git checkout korg/android-goldfish-2.6.29
toolchain:
直接用android里自带的:
 export PATH=/home/dybbuk/work/android_dev/mydroid/prebuilt/linux-x86/toolchain/arm-eabi-4.3.1/bin:$PATH
make ARCH=arm CROSS_COMPILE=arm-eabi- goldfish_defconfig
make ARCH=arm CROSS_COMPILE=arm-eabi-
即可生成emulator所用的zImage