Building AOKP for the Nexus S

Building any AOSP variant for a Nexus device is pretty straightforward, as the device tree is already included by Goole and they are well tested & supported devices. In order to build AOKP (AOSP variant with some tweaks):

The source code is here (check the README below):
https://github.com/AOKP/vendor_aokp

First of, clone the whole code from git

mkdir ~/bin
PATH=~/bin:$PATH
curl https://dl-ssl.google.com/dl/googlesource/git-repo/repo > ~/bin/repo
chmod a+x ~/bin/repo
repo init -u https://github.com/AOKP/platform_manifest.git -b jb

Then sync:

repo sync -j16

-jNN will speed up things for multicore - fast - connected build environments, BUT it may lock on Ubuntu because of its broken python impementation. To avoid this problem:

sudo sysctl -w net.ipv4.tcp_window_scaling=0
repo sync -j1

For building AOKP I prepare a handy script that set ups ccache (to speedup things) and builds for "crespo" that is Nexus S. This script might be on vendor/aokp/build.sh for instance:

export USER=alienmind
export USE_CCACHE=1
export CCACHE_DIR=/$HOME/.ccache
prebuilts/misc/linux-x86/ccache/ccache -M 40G
source build/envsetup.sh
lunch aokp_crespo-userdebug
make -j1 otapackage # bacon
#brunch $DEV

There are three build types:

Buildtype	Use
user	limited access; suited for production
userdebug	like "user" but with root access and debuggability; preferred for debugging
eng	development configuration with additional debugging tools

References:  http://source.android.com/source/building-devices.html

Android preferences

Reworking icetool preferences the proper way ...

Modding boot.img

Modding boot.img can be useful for changing kernel or init scripts on ramdisk.

The ramdisk itself contains - for instance - default.prop that can be edited to unsecure the image - that means having adb shell directly as root, or ability to use adb remount
Boot partition can be extracted with dd if=/dev/mtd/mtd2 (on Nexus S) or as generic way, from recovery using flash_dump boot boot.img

Needed steps are:

$ unpack-bootimg.pl boot.img 
kernel written to boot.img-kernel.gz
ramdisk written to boot.img-ramdisk.cpio.gz

removed old directory boot.img-ramdisk

gzip: ../boot.img-ramdisk.cpio.gz: decompression OK, trailing garbage ignored
529 blocks

extracted ramdisk contents to directory boot.img-ramdisk/

$ cd boot.img-ramdisk/
# ... do whatever edits you need ...

# Repack
$ find . | cpio -o  -H newc | gzip > ../boot.img-ramdisk-new.cpio.gz
$ cd ..
$ mkbootimg --kernel boot.img-kernel.gz --ramdisk boot.img-ramdisk-new.cpio.gz --base 0x30000000 --pagesize 4096 -o boot.img.new

Looks like base / pagesize parameters are device dependent. Above are for Nexus S only

Example 1 - Unsecuring boot.img

After unpacking the img, we can chdir to unpacked ramdisk folder and change in default.prop:

ro.secure=1

to

ro.secure=0

EDIT: This example is useless, as someone pointed me how to properly gain root access with just running "adb root" and nothing else

Example 2 - Adding init.d support

At the end of init.rc we may add (if we also add busybox to system.img of course):

# Execute files in /etc/init.d before booting
service userinit /system/xbin/busybox run-parts /system/etc/init.d
    oneshot
    class late_start
    user root
    group root

Attach: mkbootimg.zip containing all needed tools