Android Things Internals
5 likes3,160 views
This document summarizes the history and evolution of Android for embedded and IoT devices, including: 1) Early embedded Linux systems had no consistent development environment or APIs. Android provided a standardized environment but was initially not designed for embedded. 2) Headless Android and later Brillo were Google's first attempts at an Android variant for IoT. Brillo sources were available but never officially released. 3) Android Things is Google's current strategy, building on the original Android architecture but extending the APIs for IoT and supporting constrained hardware. It allows using existing Android development tools for IoT apps and devices.
![18
/frameworks/base/services/java/...
/frameworks/base/services/jni/
/hardware/libhardware/
/device/[MANUF.]/[DEVICE]
/sdk/emulator/
Kernel or module
/frameworks/base/core/...
AOSP-provided
ASL
Manuf.-provided
Manuf. license
Manuf.-provided
GPL-license](https://image.slidesharecdn.com/android-things-internals-170223-170224005332/85/Android-Things-Internals-18-320.jpg)
Android Things Internals
- 1. 1 Android Things: Internals and cute embedded nonsense hacks Embedded Linux Conference 2017 Karim Yaghmour +karimyaghmour, @karimyaghmour karim.yaghmour@opersys.com
- 2. 2 These slides are made available to you under a Creative Commons Share- Alike 3.0 license. The full terms of this license are here: https://creativecommons.org/licenses/by-sa/3.0/ Attribution requirements and misc., PLEASE READ: ● This slide must remain as-is in this specific location (slide #2), everything else you are free to change; including the logo :-) ● Use of figures in other documents must feature the below “Originals at” URL immediately under that figure and the below copyright notice where appropriate. ● You are free to fill in the “Delivered and/or customized by” space on the right as you see fit. ● You are FORBIDEN from using the default “About” slide as-is or any of its contents. ● You are FORBIDEN from using any content provided by 3rd parties without the EXPLICIT consent from those parties. (C) Copyright 2017, Opersys inc. These slides created by: Karim Yaghmour Originals at: www.opersys.com/community/docs Delivered and/or customized by
- 3. 3 About ● Author of: ● Introduced Linux Trace Toolkit in 1999 ● Originated Adeos and relayfs (kernel/relay.c) ● Training, Custom Dev, Consulting, ...
- 4. 4 Agenda 1. A bit of history 2. Legacy Architectures 3. The Brillo/Weave Intermezzo 4. Now back to your regular programming 5. Hardware 6. “Things” Architecture 7. Images 8. User-Space 9. Services / Daemons 10.APIs 11.Apps 12.What if I told you ... ?
- 5. 5 1. A bit of history ● Embedded Linux ● Android ● Headless Android ● Brillo ● Android Things
- 6. 6 1.1. Embedded Linux ● A set of ad-hoc methods to package the Linux kernel with a (minimal) filesystem. ● FS content “to be determined” case-by-case ● APIs are specific to each device/build ● “Core software”: ● BusyBox ● U-Boot ● GNU Toolchain ● Your flavor of: ● glibc or uClibc or eglibc ● yocto or buildroot or eldk or ltib or ptxdist or ... ● No serious UX framework
- 7. 7 1.2. Android ● ... apart from its ubiquitous UX ... ● Fully-integrated IDE: Android Studio ● SDK/NDK ● ADB ● Fastboot ● Published, well-known, and very rich APIs ● A large and growing developer community ● And still we can use “embedded Linux” components: ● GNU toolchain, BusyBox, u- boot, glibc, ... An actual standardized dev. env. across all product lines
- 8. 8
- 9. 9 1.3. Headless Android + = Android Builders Summit, February 2012
- 10. 10 A few months later ... ro.config.headless
- 11. 11 1.4. Brillo / Weave ● Initial Google platform for IoT* ● Based on Android ● Announced at Google I/O 2015 ● Never officially released ● Remained in “developer preview” mode ● Needed to sign up for developer preview on https://developers.google.com/brillo/ ● Sources available from android.googlesource.com ● “Apps” talk straight to HALs ● Note: Material here based on sources, NOT on developer preview or any information thereof :P * New, hip way of talking about “Embedded Systems”, something that's been around for ~50+ years.
- 12. 12 1.5. Android Things ● “Reboot” of Google's Android IoT strategy ● Announced on Dec 13th, 2016 ● Reinstates full Android environment ● Developers use existing Android dev tools ● C/C++ available through NDK ● Extended APIs for IoT ● Currently at Developer Preview 2 ● Sources not yet available
- 13. 13 2. Legacy Architectures ● Embedded Linux ● Android ● Binder ● System services ● HAL
- 14. 14
- 15. 15
- 16. 16
- 17. 17
- 18. 18 /frameworks/base/services/java/... /frameworks/base/services/jni/ /hardware/libhardware/ /device/[MANUF.]/[DEVICE] /sdk/emulator/ Kernel or module /frameworks/base/core/... AOSP-provided ASL Manuf.-provided Manuf. license Manuf.-provided GPL-license
- 19. 19 3. The Brillo/Weave Intermezzo ● Architecture ● Sources ● Images ● User-Space ● Services/Daemons ● Weave
- 20. 20 3.1. Architecture ● DBus ● Brillo ● Weave
- 21. 21
- 22. 22 Your Code
- 23. 23
- 24. 24 3.2. Sources ● Getting the sources ● Brillo top level ● Removed from Android top level ● Gone from external/ ● New to external
- 25. 25 3.2.1. Getting the sources ● Same project repo as Android: android.googlesource.com ● Different manifest file ● Using “repo”: $ repo init u https://android.googlesource.com/brillo/manifest $ repo sync
- 26. 26 3.2.2. Brillo top level bionic C library replacement bootable Reference bootloader build Build system device Device-specific files and components external Copy of external projects used by AOSP frameworks Native system services and libraries hardware Hardware support libs libnativehelper JNI helpers prebuilts Prebuilt binaries product “Products” running on Brillo system Embedded Linux core tools Brillo Development Kit
- 27. 27 3.2.3. Removed from Android top level art cts dalvik dvelopers development docs frameworks/base and more libcore ndk packages pdk sdk system/vold and more tools/external
- 28. 28 3.2.4. Removed from external/
- 29. 29 3.2.5. Added to external/ bvb Brillo Verified Boot chromite Tools to build Chrome OS gentoo libdivsufsort lightweight suffix array construction algorithm library lzop LZO compression tool
- 30. 30 3.3. Images ● AOSP x86 32-bit: ● 5.1M out/target/product/generic_x86/cache.img ● 1.3M out/target/product/generic_x86/ramdisk.img ● 1.3G out/target/product/generic_x86/system.img ● 12M out/target/product/generic_x86/userdata.img ● 551M out/target/product/generic_x86/userdata-qemu.img ● Brillo x86 64-bit: ● 6.2M out/target/product/brilloemulator_x86_64/boot.img ● 36K out/target/product/brilloemulator_x86_64/partition-table.img ● 158M out/target/product/brilloemulator_x86_64/system.img ● 201M out/target/product/brilloemulator_x86_64/userdata.img ● 551M out/target/product/brilloemulator_x86_64/userdata-qemu.img
- 32. 32 3.5. Services / Daemons ● dbus-daemon ● servicemanager ● avahi-daemon ● keystore ● nativeperms ● peripheralman ● sensorservice ● wpa_supplicant ● brilloaudioservice ● metrics_collector ● metriscsd ● perfprofd ● tlsdated ● tpm_managerd ● trunksd ● update_engine ● weaved ● webservd ● shill ● firewalld ● dhcpd
- 33. 33 3.6. Weave
- 34. 34 4. Now back to your regular programming ● Android Things does away with most of Brillo ● Revert architecture to original ● Weave seems gone from the FS, but site still on ● Go back to system services with HALs ● Extend Android API for IoT ● Use of Android Studio and co. ● Optional Display ● Use of traditional static permissions
- 36. 36 6. “Things” Architecture Peripheral Manager IoTLauncher PIO HAL PIO APIs Your App User-Space Drivers Peripheral Driver Library
- 37. 37 7. Images ● Brillo x86 64-bit emulator: ● 6.2M boot.img ● 36K partition-table.img ● 158M system.img ● 201M userdata.img ● Things x86 Edison: ● 11M boot.img ● 176M gapps.img ● 4.6M oem.img ● 420M system.img ● 376K u-boot-edison.img ● 35M userdata.img ● Things Rpi3: ● 350M root + system ● 150M gapps ● AOSP x86 32-bit: ● 1.3G system.img
- 38. 38 8. User-Space ● Same FS layout as Android ● Mostly same processes ● In short, unlike Brillo, it's still very much Android
- 39. 39 9. Services / Daemons ● /system/bin/peripheralman ● C++ System Service ● Responds to dumpsys: dumpsys com.google.android.things.pio.IPeripheralManager ● Also was in Brillo ● Sources (6 months old): ● https://android.googlesource.com/platform/system/peripheralmanager/ ● New HAL: ● peripheral_io.h ● As with other HALs: ● /system/lib/hw/peripheral_io.<board_name>.so
- 40. 40 10. APIs
- 41. 41
- 42. 42 11. Apps ● New Launcher: IoTLauncher.apk ● Still responds to same intent as LauncherN.apk – Try: aapt l -a IoTLauncher.apk ● Likely party firing android.intent.category.IOT_LAUNCHER – Try: strings IoTLauncher.odex | grep IOT ● Gone: ● Home launcher (replaced by IoTLauncher) ● Status bar ● Settings (at least the content provider ... “ps” says the app is still running ;) ) ● Interesting: ● Google services (some of them at least) ● Try: ● dumpsys gfxinfo
- 43. 43 12. What if I told you ... ? ● What's this IoT thing ... ? ● Consumer ● Industrial/Commercial ● 256MB+ RAM for an embedded device, really? ... ● A long time ago in a galaxy far far away ...
- 46. 46
- 48. 48 ● Vibrator ● Battery ● Audio ● Baseband modem ● Bluetooth ● Camera ● Consumer IR 12.3. Greybus Device Classes ● Display ● GPS ● Keymaster ● Lights ● NFC ● Sensors ● Wifi
- 49. 49 12.4. Bridged PHY Connection Protocols ● USB ● GPIO ● SPI ● UART ● PWM ● I2C ● SDIO
- 50. 50
- 51. 51
- 52. 52 12.5. Greybus for IOT Alexandre Baillon Baylibre
- 53. 53From Alexandre's ELCE 2016 slides
- 54. 54 12.6. Can I haz an Android for real-world IOT ?