Course: Android Internals Lecture 2: High-level architecture, version control system

1. Android internals
Egor Elizarov
SPbSU 2012

2. Legal info
 Android internals by Egor Elizarov is licensed under a
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 All pictures and trademarks are the property of their respective owners. Use of
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 Corrections, suggestions, contributions and translations are welcome!
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3. Lecture 2
High level Android architecture.
Android control version system.
yegor.yelizarov(at)gmail.com
Rev: 1.1
Last update: 05/30/2012 http://vk.com/android_internals
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4. Previous time

OS functions

Mobile OS features

Perepherial devices
Source: beagleboard.org

SoC, BSP, Single Board Computer, Eval. Board
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5. Android history

2004 - Android Inc. by Andy Rubin

2005 - Android Inc. acquisition

2007 - Open Handset Alliance

September 2008 - Android 1.0 on HTC G1

February 2011 - Android 3.0 for tablets Source:
http://en.wikipedia.org/wiki/Andy_Rubin

October 2011 - Android 4.0 (merge phone and tablet
versions)
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6. Some acronyms

Android Open Source Project (AOSP)

Android Software Development Kit (SDK)

Native Development Kit (NDK)

API Level (current 15)
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7. Android versions

Cupcake (1.5) 
Gingerbread (2.3)

Donut (1.6) 
Honeycomb (3.0-3.2)
Android Open Source Project (AOSP)
Android Software Development Kit (SDK)
Native Development Kit (NDK)

Eclair (2.0 - 2.1) 
Ice cream sandwich (4.0)

FroYo (2.2) 
Jelly Bean (5.0) ?
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8. High level architecture
Android Open Source Project (AOSP)
Android Software Development Kit (SDK)
Native Development Kit (NDK)
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9. High level architecture (2)
Android Open Source Project (AOSP)
Android Software Development Kit (SDK)
Native Development Kit (NDK)
Source: developer.android.com
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10. Android OS development
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11. Android OS bring up
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12. Code licenses

GNU GPLv2 (kernel)

LGPL & GPL (external libraries)

BSD (bionic, toolbox)

Apache 2.0 license (framework)
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13. Android compatibility

Google apps only on branded devices

Google logo only on branded devices

Compatibility Test Suite

Compatibility Definition Document
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14. Android version control
system

Based on repo & git

~ 220 git trees

Repo provides functionality to work with
multiple git trees

Gerrit code review system
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15. Git workflow
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16. Git workflow (2)

git clone

git branch -a

git checkout -b local_branch remote_branch

Make changes

git add list_of_files

git commit

git push
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17. Manifest file

Project - single project

Remote - server description description

Fetch - server URL 
Path — directory to unpack
Android Open Source Project (AOSP)

Revisoin - git branch 
Name — project name to
Android Software Development Kit (SDK)
Native Development Kit (NDK)
obtain sources
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18. Repo workflow

repo init -u URL -m Manifest.xml -b Branch

repo sync

repo start --all local_branch

Make changes -> git add -> git commit

repo upload
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19. Patch life

Create patch

Send for review (repo upload)

Recieve review & approve in Gerrit

Patch will be automatically uploaded by Gerrit
after approve
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20. Repo tricks

repo forall -c 'env'

repo manifest -r -o descriptive-name.xml
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21. Android code lines
Source: http://source.android.com/source/code-lines.html
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22. Getting ICS AOSP code

curl https://dl-ssl.google.com/dl/googlesource/git-repo/repo >
~/bin/repo

chmod a+x ~/bin/repo

mkdir AOSP

cd AOSP

repo init -u https://android.googlesource.com/platform/manifest -b
android-4.0.3_r1

repo sync
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23. Code layout

Frameworks — framework's
code

Build — build system files

External — external projects
and libraries

Device — device specific
build/runtime configuration

System — ”Embedded linux”
platform part
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24. Next time

Android build system

Android Emulator
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25. Useful links

http://vk.com/android_internals

http://www.openhandsetalliance.com

http://source.android.com/compatibility/cts-intro.html

http://source.android.com/source/overview.html

http://source.android.com/source/using-repo.html

K. Yaghmour. Embedded Android. Early Release, O'Reilly, October 2011

http://source.android.com/source/downloading.html

http://source.android.com/source/code-lines.html

http://code.google.com/p/gerrit/
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26. Thanks to

Sergey Matyukevich for review and advices
(www.linkedin.com/pub/sergey-
matyukevich/31/889/769)

Nikolay F. Fominykh for review and advices
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