Manually start android in the google android emulator

The google android kernel will invoke services listed in the file /etc/init.rc after the kernel is started up. The /etc/init.rc is included in the ramdisk.img. Find the ramdisk.img in $EMULATOR_SDK_FOLDER/tools/lib/images/. One can change the ramdisk.img to change the init.rc and so to change the google android startup sequence.

Follow the tips in Step by step to create/modify ramdisk.img to change ramdisk.img.

Following is the items to comment out in init.rc to stop the android to be loaded at the initial time:

1. Find the service section in the init.rc (following the startup section)
2. Comment out the zygote sub-section, and runtime sub-section
3. Recreate the ramdisk.img and replace the original ramdisk.img (backup the original if you want)
4. Restart the google android emulator, use -debug-kernel to see more information

Comment out lines are listed for your reference:

#zygote {
#exec /system/bin/app_process
#args {
#0 -Xzygote
#1 /system/bin
#2 --zygote
#}
#autostart 1
#}
#runtime {
#exec /system/bin/runtime
#autostart 1
#}

After the google android emulator is started up, manually start up the google android services below:

1. # adb shell to create a console
   
2. # /system/bin/app_process -Xzygote /system/bin --zygote &
3. # /system/bin/runtime &

Upload a strace tool to trace the above services:

1. # strace -ff -F -tt -s 200 -o /tmp/log/zygote /system/bin/app_process -Xzygote /system/bin --zygote &
2. # strace -ff -F -tt -s 200 -o /tmp/log/runtime /system/bin/runtime &

Get start playing with Google Android

The Android platform is a software stack for mobile devices including an operating system, middleware and key applications. Developers can create applications for the platform using the Android SDK. Applications are written using the Java programming language and run on Dalvik, a custom virtual machine designed for embedded use which runs on top of a Linux kernel.

Google provides Android SDK for three platforms: Windows, Mac OS X (intel), Linux (i386). There is Android emulator included in the SDK package. So first find a Android SDK for your platform: Download the Android SDK from Google.

Next, extract the Android SDK package into your system, let's say the root folder is $ANDROID_SDK.

Open a command window (shell window), change the working directory to $ANDROID_SDK/tools/. You will see tens of executable files, one is emulator. Simply start it with the following command:
# emulator
If you want to see the emulator kernel boot up detail information, start it with the following command:
# emulator -debug-kernel

When the Android started up, the following window is shown.
You can open a Android shell by the command:
# adb shell

It is a Linux kernel 2.6.23 (Android is linux kenel based) shell, play with it in the same way as linux.







Here is the Android kernel boot up log fyi:
Uncompressing Linux.............................................................
.................... done, booting the kernel.
Linux version 2.6.23-gcc3bc3b4 (arve@arvelnx.corp.google.com) (gcc version 4.2.1
) #3 Tue Oct 30 16:28:18 PDT 2007
CPU: ARM926EJ-S [41069265] revision 5 (ARMv5TEJ), cr=00003137
Machine: Goldfish
Memory policy: ECC disabled, Data cache writeback
CPU0: D VIVT write-through cache
CPU0: I cache: 4096 bytes, associativity 4, 32 byte lines, 32 sets
CPU0: D cache: 65536 bytes, associativity 4, 32 byte lines, 512 sets
Built 1 zonelists in Zone order. Total pages: 24384
Kernel command line: qemu=1 console=ttyS0 android.checkjni=1 keycharmap=qwerty2
android.ril=ttyS1
Unknown boot option `android.checkjni=1': ignoring
Unknown boot option `android.ril=ttyS1': ignoring
PID hash table entries: 512 (order: 9, 2048 bytes)
Console: colour dummy device 80x30
Dentry cache hash table entries: 16384 (order: 4, 65536 bytes)
Inode-cache hash table entries: 8192 (order: 3, 32768 bytes)
Memory: 96MB = 96MB total
Memory: 94280KB available (2268K code, 458K data, 96K init)
Mount-cache hash table entries: 512
CPU: Testing write buffer coherency: ok
android_power_init
android_power_init done
NET: Registered protocol family 16
NET: Registered protocol family 2
IP route cache hash table entries: 1024 (order: 0, 4096 bytes)
TCP established hash table entries: 4096 (order: 3, 32768 bytes)
TCP bind hash table entries: 4096 (order: 2, 16384 bytes)
TCP: Hash tables configured (established 4096 bind 4096)
TCP reno registered
checking if image is initramfs... it is
Freeing initrd memory: 228K
goldfish_new_pdev goldfish_interrupt_controller at ff000000 irq -1
goldfish_new_pdev goldfish_device_bus at ff001000 irq 1
goldfish_new_pdev goldfish_timer at ff003000 irq 3
goldfish_new_pdev goldfish_rtc at ff010000 irq 10
goldfish_new_pdev goldfish_tty at ff002000 irq 4
goldfish_new_pdev goldfish_tty at ff011000 irq 11
goldfish_new_pdev smc91x at ff012000 irq 12
goldfish_new_pdev goldfish_fb at ff013000 irq 13
goldfish_new_pdev goldfish_audio at ff004000 irq 14
goldfish_new_pdev goldfish_events at ff014000 irq 15
goldfish_new_pdev goldfish_nand at ff015000 irq -1
goldfish_new_pdev goldfish-switch at ff016000 irq 16
goldfish_new_pdev goldfish-switch at ff017000 irq 17
goldfish_pdev_worker registered goldfish-switch
goldfish_pdev_worker registered goldfish-switch
goldfish_pdev_worker registered goldfish_nand
goldfish_pdev_worker registered goldfish_events
goldfish_pdev_worker registered goldfish_audio
goldfish_pdev_worker registered goldfish_fb
goldfish_pdev_worker registered smc91x
goldfish_pdev_worker registered goldfish_tty
goldfish_pdev_worker registered goldfish_tty
goldfish_pdev_worker registered goldfish_rtc
goldfish_pdev_worker registered goldfish_timer
goldfish_pdev_worker registered goldfish_device_bus
goldfish_pdev_worker registered goldfish_interrupt_controller
goldfish_audio_probe
Installing knfsd (copyright (C) 1996 okir@monad.swb.de).
yaffs Oct 30 2007 16:24:34 Installing.
io scheduler noop registered
io scheduler anticipatory registered (default)
io scheduler deadline registered
io scheduler cfq registered
allocating frame buffer 320 * 480, got ffc10000
Console: switching to colour frame buffer device 40x30
console [ttyS0] enabled
RAMDISK driver initialized: 16 RAM disks of 8192K size 1024 blocksize
loop: module loaded
nbd: registered device at major 43
smc91x.c: v1.1, sep 22 2004 by Nicolas Pitre
No IRQF_TRIGGER set_type function for IRQ 12 (goldfish)
eth0: SMC91C11xFD (rev 1) at c6800000 IRQ 12 [nowait]
eth0: Ethernet addr: 52:54:00:12:34:56
goldfish nand dev0: size 4000000, page 2048, extra 64, erase 131072
goldfish nand dev1: size 4000000, page 2048, extra 64, erase 131072
mice: PS/2 mouse device common for all mice
*** events probe ***
events_probe() addr=0xc6804000 irq=15
input: goldfish-events-keyboard as /class/input/input0
goldfish_rtc goldfish_rtc: rtc core: registered goldfish_rtc as rtc0
logger: created 64K log 'log_main'
logger: created 64K log 'log_events'
logger: created 64K log 'log_radio'
IPv4 over IPv4 tunneling driver
GRE over IPv4 tunneling driver
TCP cubic registered
NET: Registered protocol family 1
NET: Registered protocol family 17
802.1Q VLAN Support v1.8 Ben Greear
All bugs added by David S. Miller
VFP support v0.3: implementor 41 architecture 1 part 10 variant 9 rev 0
goldfish_rtc goldfish_rtc: setting the system clock to 2008-01-12 02:48:13 (1200
106093)
Freeing init memory: 96K
init: HOW ARE YOU GENTLEMEN
init: reading config file
init: device init
init: mtd partition -1,
init: mtd partition 0, "system"
yaffs: dev is 32505856 name is "mtdblock0"
yaffs: passed flags ""
yaffs: Attempting MTD mount on 31.0, "mtdblock0"
init: mtd partition 1, "userdata"
yaffs: dev is 32505857 name is "mtdblock1"
yaffs: passed flags ""
yaffs: Attempting MTD mount on 31.1, "mtdblock1"
eth0: link up
sh: can't access tty; job control turned off
# binder_open(c0833428 c0a0a4a0) (pid 468) got c5f13000
binder_open(c0833428 c5a6b9e0) (pid 460) got c5bbf000
binder_open(c0833428 c5a6b2e0) (pid 474) got c4716000
android_power: auto off timeout set to 604800 seconds
Descriptor2Node failed secondary: desc=4, max=32, node=c5bc0350, weak=0
binder_open(c0833428 c4f533a0) (pid 510) got c4754000
binder_open(c0833428 c4f53920) (pid 511) got c3a30000
binder_open(c0833428 c3421860) (pid 527) got c3428000