AOSP Building Blocks (December 2014)

[As seen on Droidcon NL 2014 and GDG Lyon Android UG]

Most of the Android developers are able to build awesome apps, but do we really know how the Android OS works? In some cases, as when developing a new product, adding customised apps is not enough, and OS modifications are required.
To be able to modify Android at its core, this talk will guide you through the complete process, from setting the correct environment, configuring the different Google’s repositories and downloading the source code, to understand the structure of the source code and how to modify it.

Transcript

1. AOSP building blocks
   

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2. Daniele Bonaldo
   @danybony_
   +DanieleBonaldo
   danybony
   Android Software Craftsman
   

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4. Repo and manifest
   Usually a single project
   =
   single repository
   

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5. Repo and manifest
   AOSP = more than 450 repositories
   

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6. Repo and manifest
   Enter repo
   

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7. Repo and manifest
   repo init
   -u http://your.company.repo/manifest
   -b working_branch
   -m manifest_name.xml
   

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8. Repo and manifest
   
   
   fetch="https://android.googlesource.com/" />
   fetch="ssh://git@github.com/third_party/" />
   remote="aosp"
   sync-j="4" />
   
   
   
   
   
   
   
   [...]
   
   

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9. Repo and manifest
   path="packages/apps/Settings"
   remote="company"
   name="firmware-settings"
   revision="other_branch"
   />
   

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10. Repo and manifest
    path="packages/apps/Settings"
    remote="company"
    name="firmware-settings"
    revision="other_branch"
    />
    fetch="ssh://git@github.com/third_party/" />
    

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11. Repo and manifest
    path="packages/apps/Settings"
    remote="company"
    name="firmware-settings"
    revision="other_branch"
    />
    

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12. Repo and manifest
    path="packages/apps/Settings"
    remote="company"
    name="firmware-settings"
    revision="other_branch"
    />
    

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13. Repo and manifest
    repo sync
    -j (--jobs)
    

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14. AOSP Source Code
    http://elinux.org/Master-android
    

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15. AOSP Source Code
    Some examples:
    ● development
    ● frameworks
    ● packages
    ● vendor
    

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16. Edit the source
    Jack M. on Flickr
    

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17. IDE
    ./development/tools/idegen/idegen.sh
    Project definition files generated in
    the root of the working dir
    

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18. Search the source
    

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19. @hide
    Context.sendBroadcastAsUser(Intent, UserHandle);
    Context.startActivityAsUser(Intent, UserHandle);
    Context.startServiceAsUser(Intent, UserHandle);
    @hide
    public UserHandle(int userId)
    

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20. @hide
    public UserHandle(int userId)
    @hide
    

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21. @hide
    public static UserHandle getUserHandleForUser(int userId) {
    try {
    Class userHandleClass = UserHandle.class;
    Constructor constructor = userHandleClass.getDeclaredConstructor(int.class);
    constructor.setAccessible(true);
    return constructor.newInstance(userId);
    } catch (InvocationTargetException e) {
    logUnableToFetchUserHandleForUser(userId, e);
    } catch (NoSuchMethodException e) {
    logUnableToFetchUserHandleForUser(userId, e);
    } catch (InstantiationException e) {
    logUnableToFetchUserHandleForUser(userId, e);
    } catch (IllegalAccessException e) {
    logUnableToFetchUserHandleForUser(userId, e);
    }
    return null;
    }
    REFLECTION
    

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22. Build environment
    https://source.android.com/
    source/initializing.html
    

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23. Mac OS X build environment
    Case-sensitive disk
    image
    Chris McVeigh on Flickr
    

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24. source build/envsetup.sh
    Setting up the build environment
    Check for missing dependencies
    

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25. lunch
    Choose the target product and build variant
    ● eng
    ● userdebug
    ● release
    

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26. make
    export USE_CCACHE=1
    make -jX
    X = # of working threads
    

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27. Build for devices
    Additional proprietary libraries required
    Placed under vendor/
    

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28. Install
    In out/target/product/DEVICE_NAME/
    ● recovery.img
    ● boot.img
    ● system.img
    ● userdata.img
    

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29. Install
    adb reboot bootloader
    fastboot flashall -w
    

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30. Speeding up the dev cycle
    make alias for single projects
    m = make from the top of the tree
    mm = make from the current directory
    mmm = make from the given directory
    mmma = make from the given directory WITH dependencies
    

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31. Speeding up the dev cycle
    adb shell stop
    adb sync
    adb shell start
    

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32. Contributing to AOSP
    https://source.android.com/
    source/contributing.html
    

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33. Contributing to AOSP
    

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34. Questions?
    Daniele Bonaldo on G+
    

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35. We’re hiring!
    join@novoda.com
    

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