The document outlines the Android build system, its components, and how developers can navigate it effectively. Key features include the use of folders like 'build/' and 'device/' to manage build rules and device definitions, as well as an introduction to the Ninja build system for improved build times. It also discusses the significance of various configuration files, such as boardconfig.mk and androidproducts.mk, in defining and managing builds for different Android products.

1. The Android Build System
Introduction
Ron Munitz - ron@thepscg.com
Updated: November 12th 2015
Updated: June 22nd 2015
Android Marshmallow / master post android-6.0.0_r26
PSCG

2. The Android Build System
● Host Tools
● Target Tools
● Platform tools
● Documentation Tools
● The Target’s (Android Platform) code base
● Build System
PSCG

3. The Android Build System
● Build Systems are a huge topic.
● A build system
○ Takes a series of rules or recipes
○ Knows how to generate an embedded platform
images/artifacts from source code, configuration
files, BLOBs, ...
○ Allows to easily select a premade configuration and
build a ready to use code without working too hard
○ Allows customizing products and defining new onesPSCG

4. The Android Build System
● Consists of two essential folders:
○ build/ Contains the definitions of the build system,
along with some predefined devices.
○ device/ Contains definitions for devices. The build
system rules really parse them
An optional, out of source control folder may be
added for vendor specific additions (mainly BLOBs).
It is listed as vendor/ PSCG

5. build/
● buildspec.mk.default - template for remake
● CleanSpec.mk - Build cleanup definitions
● core - Build System rules
● envsetup.sh - environment preparation script
● libs - some host helper libs
● target - Target definitions.
● tools - Building, packaging, etc.
● soong, blueprint, kati ⇒ Ninja build systemPSCG

6. The Android Build System
● Main folder: build/
● Based on GNU make / Ninja
○ Makefile on top directory says: #include
build/core/main.mk
○ Then a lot of other files are included.
○ Heavily uses Python and bash.
● Heavily uses environment variables
○ @see build/envsetup.sh
PSCG

7. The Android Build System
● Very easy to use for building:
○ . build/envsetup.sh #sets env vars/functions
○ lunch <config>-<variant> # selects configuration
○ make # That’s gnu make, no customizations**.
● Very easy for flashing via Software tools
○ With emulator (no need to flash…)
○ With fastboot
○ With other custom bootloaders
** Not true for master as per today. See next.PSCG

8. **Introducing Ninja
build/
● blueprint
● kati
● soong
The ninja build system supposedly
reduces incremental build times, and simplifies
the “Makefile” configuration.

9. build/target
● This is what you should probably care about.
● Contains two folders:
○ board/ - board definition file
○ product/ - product definition file
● Build recipes are defined in these folders.
● Device definitions in device/ include files
from these folders, and derive from recipes.
● Or include their own.
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10. Where (some) board magic is defined
build/target/board
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11. build/target/board
● Android.mk - automatically included by build
○ includes the no longer necessary AndroidBoard.
mk file at TARGET_DEVICE_DIR
■ What is required is BoardConfig.mk .
■ @see build/core/config.mk
○ Populates the fastboot read android-info.txt file with
the contents of the devices board.info.txt
■ Or with "board=$(TARGET_BOOTLOADER_BOARD_NAME)"
● Templates for predefined boards
○ @see next slide PSCG

12. build/target/board (cont.)
● Contains build templates for predefined
boards
○ emulator, generic_<arch>, vbox_x86
● Each contains:
○ AndroidBoard.mk (obsolete)
○ BoardConfig.mk - Board definitions (see next slide)
○ device.mk - Some Board/Hardware related
pacakges at device.mk and BoardConfig.mk
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13. A bit about BoardConfig.mk
● TARGET_NO_BOOTLOADER - Self Explaining
● TARGET_NO_KERNEL - use prebuilt kernel
● TARGET_USE_CAMERA_STUB
● ...
● Architecture, ABIs, Partition layout, OpenGL
config, Radio config…
PSCG

14. BoardConfig.mk search path
● The build system searches for BoardConfig.
mk at the following locations:
○ build/target/board/$TARGET_DEVICE/
○ device/*/$TARGET_DEVICE/
○ vendor/*/$TARGET_DEVICE/
● If there is no such file - the build fails.
● If there is more than one match - the build
fails.
PSCG

15. Where (product packages) dreams come true
build/target/product
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16. build/target/product
● AndroidProducts.mk defines a list of products to add
to the build system.
● More products can be added by declaring additional
AndroidProducts.mk files in either
○ device/.../
○ vendor/.../
● security/ includes prebuilt certificates
● Quick Start flow:
○ generic_mips.mk INHERITS generic.mk INHERITS
generic_no_telephony.mk AND telephony.mk ...
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17. build/target/product example
● aosp_x86.mk
INHERITS
○ full_x86.mk
■ INHERITS
● aosp_base_telephony.mk
● board/generic_x86/device.mk
■ INCLUDES
● $(SRC_TARGET_DIR)/product/emulator.mk
● Another example + a full walkthrough are
given in the next slides PSCG

18. product/full.mk
product/aosp_base_telephony.mk
PRODUCT_PACKAGES +=
gralloc.goldfish
qemud
libGLES_android
...
PRODUCT_COPY_FILES +=
device/generic/goldfish/
init.goldfish.rc:root/init.goldfish.rc
...
product/full_base_telephony.mk
product/aosp_arm.mk
(similiar for aosp_x86.mk and aosp_mips.mk)
PRODUCT_NAME := aosp_arm
board/generic/device.mk
PRODUCT_PROPERTY_OVERRIDES :=
ro.ril.hspxa=1
ro.ril.gprsclass=10
ro.adbd.qemu=1
PRDOUCT_COPY_FILES :=
apns_conf.xml
vold.conf
media_profiles.xml
media_codecs.xml
audio_policy.xml
product/emulator.mk

19. product/full.mk
product/aosp_base_telephony.mk
product/full_base_telephony.mk
product/aosp_arm.mk
board/generic/device.mk product/emulator.mk
PRODUCT_PACKAGES :=
Dialer
Mms
rild
product/telephony.mk
product/aosp_base.mk
product/full_base.mk
PRODUCT_PACKAGES
PRODUCT_PROPERTY_OVERRIDES
PRODUCT_LOCALES
product/locales_full.mk
product/languages_full.mk
PRODUCT_LOCALES
frameworks/base/data/
sounds/AllAudio.mk
…
external/svox/pico/lang/
all_pico_languages.mk
…
product/generic_no_telephony.
mk
PRODUCT_LOCALES
PRODUCT_PROPERTY_OVERRIDES :=
keyguard.no_require_sim=true
ro.com.android.dataroaming=true
PRODUCT_COPY_FILES :=
device/generic/goldfish/data/etc/apns-conf.xml:...
frameworks/native/data/etc/handheld_core_hardware.xml:...

20. product/full_base_telephony.mk
product/telephony.mk
product/aosp_base.mk
product/full_base.mk
locales_full.mk
languages_full.mk
AllAudio.mk all_pico_languages.mk
product/generic_no_telephony.mk
.../fonts.mk
# from frameworks/base/data
# from external
.../keyboards.mk
# idc, kcm, kl, ...
chromium.mk product/core.mk
core_base.mk
core_minimal.mk
base.mk
embedded.mk
PRODUCT_PACKAGES +=
app_process pm am wm ...
PRODUCT_BOOT_JARS +=
PRODUCT_RUNTIMES +=
PRODUCT_SYSTEM_SERVER_JARS +=
PRODUCT_DEFAULT_PROPERTY_OVE
RRIDES +=
PRODUCT_PACKAGES
+=...
PRODUCT_COPY_FILE
S += ...
...
PRODUCT_PROPERTY
_OVERRIDES += ...
PRODUCT_DEFAULT_
PROPERTY_OVERRID
ES += ...
…..
runtime_libart.mk
PRODUCT_PACKAGES += … sepolicy file_contexts
seapp_contexts property_contexts mac_permissions.xml
selinux_version service_contexts
init ... libc … adbd … toybox
PRODUCT_COPY_FILES +=...
PRODUCT_DEFAULT_PROPERTY_OVERRIDES += ...
…..
PRODUCT_PACKAGES +=
apache-xml bouncycastle cacerts conscrypt core-junit core-
libart
dalvikvm dex2oat dexdeps dexdump dexlist dmtracedump dx
ext hprof-conv libart libcrypto libexpat libicui18n libicuuc
libjavacore libnativehelper libssl libz oatdump okhttp patchoat
PRODUCT_DEFAULT_PROPERTY_OVERRIDES +=
dalvik.vm.image-dex2oat-Xms=64m
dalvik.vm.image-dex2oat-Xmx=64m
dalvik.vm.dex2oat-Xms=64m
dalvik.vm.dex2oat-Xmx=512m
ro.dalvik.vm.native.bridge=0

21. build/core/build-system.html
The definitive build system document!
Most recent news!
Draft version
From 2006...
Does give a good overview of the design
criteria.
PSCG

22. The nails and hammers of the printed, framed
dream
build/core
PSCG

23. build/core
● Processes the definitions we have discussed
of the product and board
● defines the language for them
● Also applies a lot of other configuration,
compiler rules, and what not...
● @see config.mk ,main.mk, product.mk for
info
PSCG

24. Thank You
Training and Consulting requests:
ron@thepscg.com