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Android Anatomy google io 2008

Trinh Duy Hung, profile picture
Trinh Duy Hung

The document outlines the architecture of the Android operating system, including a detailed examination of its components such as the Linux kernel, native libraries, Android runtime, and application framework. It discusses the roles of various drivers, inter-process communication mechanisms, power management strategies, and the Android-specific custom libc implementation known as Bionic. Additionally, the document covers the startup process of Android, detailing how services and daemons are initialized and managed within the system.

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Android Anatomy and Physiology
Agenda • Android Anatomy • Linux Kernel • Native Libraries • Android Runtime • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers Android Anatomy Applications Home Dialer Contacts SMS/MMS Email IM Calendar Browser Media Player Albums Camera Clock Calculator …Voice Dial Alarm Android Runtime DalvikVirtual Machine Core Libraries Application Framework View SystemContent Providers Resource Manager … Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager FreeType SGL SSL SQLite WebKit Libc Surface Manager OpenGL|ES Media Framework Libraries
Agenda • Android Anatomy • Linux Kernel • Native Libraries • Android Runtime • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
Linux Kernel • Android is built on the Linux kernel, but Android is not Linux • No native windowing system • No glibc support • Does not include the full set of standard Linux utilities Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers
Linux Kernel • Standard Linux 2.6.24 Kernel • Patch of “kernel enhancements” to support Android Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers
Why Linux Kernel? • Great memory and process management • Permissions-based security model • Proven driver model • Support for shared libraries • Itʼs already open source! Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers
Kernel Enhancements • Alarm • Ashmem • Binder • Power Management • Low Memory Killer • Kernel Debugger • Logger Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers
Binder: Problem Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers • Applications and Services may run in separate processes but must communicate and share data • IPC can introduce significant processing overhead and security holes
Binder: Solution Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers • Driver to facilitate inter-process communication (IPC) • High performance through shared memory • Per-process thread pool for processing requests • Reference counting, and mapping of object references across processes • Synchronous calls between processes
Process BProcess A Binder in Action App A Service B
Process A Process B Binder in Action App A Service BContext
Process BProcess A Binder in Action App A Service BContext get service
Process BProcess A Binder in Action Binder DriverApp A Service BContext get service service
Process BProcess A Binder in Action Binder DriverApp A Service BContext get service service
Process BProcess A Binder in Action Binder DriverApp A Service BContext get service call foo(object) service
Process BProcess A Binder in Action Binder DriverApp A Service BContext get service marshal proxy object call foo(object) service
Process BProcess A Binder in Action Binder DriverApp A Service BContext get service relay to IPC threads marshal proxy object call foo(object) service
Process BProcess A Binder in Action Binder DriverApp A Service BContext get service relay to IPC threads marshal proxy object call return call foo(object) service
Binder Android Interface Definition Language (AIDL) • http://code.google.com/android/reference/aidl.html Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers
PM Problem Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers • Mobile devices run on battery power • Batteries have limited capacity
PM Solution Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers • Built on top of standard Linux Power Management (PM) • More aggressive power management policy • Components make requests to keep the power on through “wake locks” • Supports different types of wake locks
Android PM in Action PM DriverApp A PowerManager
Android PM in Action PM DriverApp A PowerManager new wake lock PARTIAL
Android PM in Action PM DriverApp A PowerManager new wake lock PARTIAL create wake lock
Android PM in Action PM DriverApp A PowerManager new wake lock PARTIAL create wake lock Turn off LCD
Android PM in Action PM DriverApp A PowerManager new wake lock PARTIAL create wake lock Turn off LCD release release
Android PM in Action PM DriverApp A PowerManager new wake lock PARTIAL create wake lock Turn off LCD release release Turn off CPU
Android PM Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers android.os.PowerManager • Use wake locks carefully! • userActivity(long when, …);
Kernel Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers The Android kernel source is available today at: http://git.android.com
Agenda • Android Anatomy • Linux Kernel • Native Libraries • Android Runtime • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers Android Anatomy FreeType SGL SSL SQLite WebKit Libc Surface Manager OpenGL|ES Media Framework Libraries
Native Libraries • Bionic Libc • Function Libraries • Native Servers • Hardware Abstraction Libraries Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
Native Libraries • Bionic Libc • Function Libraries • Native Servers • Hardware Abstraction Libraries Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
What is Bionic? • What is bionic? • Custom libc implementation, optimized for embedded use. Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
Why Bionic? Why build a custom libc library? • License: we want to keep GPL out of user-space • Size: will load in each process, so it needs to be small • Fast: limited CPU power means we need to be fast Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
Bionic libc • BSD License • Small size and fast code paths • Very fast and small custom pthread implementation Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
Bionic libc • Built-in support for important Android-specific services • system properties getprop(“my.system.property”, buff, default); • log capabilities LOGI(“Logging a message with priority ‘Info’”); Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
Bionic libc • Doesn't support certain POSIX features • Not compatible with Gnu Libc (glibc) • All native code must be compiled against bionic Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
Native Libraries • Bionic Libc • Function Libraries • Native Servers • Hardware Abstraction Libraries Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
WebKit • Based on open source WebKit browser: http://webkit.org • Renders pages in full (desktop) view • Full CSS, Javascript, DOM, AJAX support • Support for single-column and adaptive view rendering Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
Media Framework • Based on PacketVideo OpenCORE platform • Supports standard video, audio, still-frame formats • Support for hardware / software codec plug-ins Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
SQLite • Light-weight transactional data store • Back end for most platform data storage Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
Native Libraries • Bionic Libc • Function Libraries • Native Servers • Hardware Abstraction Libraries Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
Surface Flinger • Provides system-wide surface “composer”, handling all surface rendering to frame buffer device • Can combine 2D and 3D surfaces and surfaces from multiple applications Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager … App Surface Surface Surface Surface Flinger Frame Buffer App
Surface Flinger • Surfaces passed as buffers via Binder IPC calls • Can use OpenGL ES and 2D hardware accelerator for its compositions • Double-buffering using page-flip Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
Audio Flinger • Manages all audio output devices • Processes multiple audio streams into PCM audio out paths • Handles audio routing to various outputs Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager … App Tone Audio Media Player Game Audio Audio Flinger App Earpeace Speaker Bluetooth
Native Libraries • Bionic Libc • Function Libraries • Native Servers • Hardware Abstraction Libraries Libraries FreeType SSL SQLite LibWebCore LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
Hardware Abstraction Layer Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers Applications Home Dialer Contacts SMS/MMS Email IM Calendar Browser Media Player Photo Album Camera Clock Calculator …Voice Dial Alarm Android Runtime DalvikVirtual Machine Core Libraries Application Framework View SystemContent Providers Resource Manager … Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager Libraries FreeType SSL SQLite WebKit Libc Surface Manager OpenGL|ES Media Framework Audio Manager … Hardware Abstraction Layer Graphics Audio Camera Bluetooth GPS Radio (RIL) WiFi …
Hardware Abstraction Libraries • User space C/C++ library layer • Defines the interface that Android requires hardware “drivers” to implement • Separates the Android platform logic from the hardware interface Hardware Abstraction Layer Graphics Audio Camera Bluetooth GPS Radio (RIL) WiFi …
Hardware Abstraction Libraries Why do we need a user-space HAL? • Not all components have standardized kernel driver interfaces • Kernel drivers are GPL which exposes any proprietary IP • Android has specific requirements for hardware drivers Hardware Abstraction Layer Graphics Audio Camera Bluetooth GPS Radio (RIL) WiFi …
HAL Header Example // must be provided by each Acme hardware implementation typedef struct { int (*foo)( void ); char (*bar)( void ); … } AcmeFunctions; const AcmeFunctions *Acme_Init(const struct Env *env, int argc, char **argv); Hardware Abstraction Layer Graphics Audio Camera Bluetooth GPS Radio (RIL) WiFi …
Hardware Abstraction Libraries • Libraries are loaded dynamically at runtime as needed dlHandle = dlopen(“/system/lib/libacme.so”, RTLD_NOW); ... acmeInit = (const AcmeFunctions *(*)(const struct Env *, int, char **))dlsym(dlHandle, ”Acme_Init"); ... acmeFuncs = acmeInit(&env, argc, argv); Hardware Abstraction Layer Graphics Audio Camera Bluetooth GPS Radio (RIL) WiFi …
Agenda • Android Anatomy • Linux Kernel • Native Libraries • Android Runtime • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers Android Anatomy Android Runtime DalvikVirtual Machine Core Libraries FreeType SGL SSL SQLite WebKit Libc Surface Manager OpenGL|ES Media Framework Libraries
Dalvik Virtual Machine • Androidʼs custom clean-room implementation virtual machine • Provides application portability and runtime consistency • Runs optimized file format (.dex) and Dalvik bytecode • Java .class / .jar files converted to .dex at build time Android Runtime DalvikVirtual Machine Core Libraries
Dalvik Virtual Machine • Designed for embedded environment • Supports multiple virtual machine processes per device • Highly CPU-optimized bytecode interpreter • Uses runtime memory very efficiently Android Runtime DalvikVirtual Machine Core Libraries
Core Libraries • Core APIs for Java language provide a powerful, yet simple and familiar development platform • Data structures • Utilities • File access • Network Access • Graphics • … Android Runtime DalvikVirtual Machine Core Libraries
Agenda • Android Anatomy • Linux Kernel • Native Libraries • Android Runtime • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers Android Anatomy Libraries FreeType SGL SSL SQLite WebKit Libc Surface Manager OpenGL|ES Media Framework Android Runtime DalvikVirtual Machine Core Libraries Application Framework View SystemContent Providers Resource Manager … Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager
• Services that are essential to the Android platform • Behind the scenes - applications typically donʼt access them directly Application Framework View SystemContent Providers Resource Manager … Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager Core Platform Services
Application Framework View SystemContent Providers Resource Manager … Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager • Activity Manager Core Platform Services
• Activity Manager • Package Manager Core Platform Services Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager …
• Activity Manager • Package Manager • Window Manager Core Platform Services Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager …
• Activity Manager • Package Manager • Window Manager • Resource Manager Core Platform Services Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager …
• Activity Manager • Package Manager • Window Manager • Resource Manager • Content Providers Core Platform Services Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager …
• Activity Manager • Package Manager • Window Manager • Resource Manager • Content Providers • View System Core Platform Services Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager …
• Provide access to lower-level hardware APIs Hardware Services Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager …
• Provide access to lower-level hardware APIs • Typically accessed through local Manager object LocationManager lm = (LocationManager) Context.getSystemService(Context.LOCATION_SERVICE); Hardware Services Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager …
• Telephony Service Hardware Services Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager …
• Telephony Service • Location Service Hardware Services Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager …
• Telephony Service • Location Service • Bluetooth Service Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager … Hardware Services
• Telephony Service • Location Service • Bluetooth Service • WiFi Service Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager … Hardware Services
• Telephony Service • Location Service • Bluetooth Service • WiFi Service • USB Service Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager … Hardware Services
• Telephony Service • Location Service • Bluetooth Service • WiFi Service • USB Service • Sensor Service Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager … Hardware Services
More Information • At Google I/O • “Inside the Android Application Framework” • Online • http://code.google.com/android Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager … Application Framework
Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers Android Anatomy Applications Home Dialer Contacts SMS/MMS Email IM Calendar Browser Media Player Albums Camera Clock Calculator …Voice Dial Alarm Android Runtime DalvikVirtual Machine Core Libraries Application Framework View SystemContent Providers Resource Manager … Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager FreeType SGL SSL SQLite WebKit Libc Surface Manager OpenGL|ES Media Framework Libraries
Agenda • Android Anatomy • Linux Kernel • Native Libraries • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
Agenda • Android Anatomy • Linux Kernel • Native Libraries • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
Runtime Walkthrough It all starts with init… Similar to most Linux-based systems at startup, the bootloader loads the Linux kernel and starts the init process. Init Linux Kernel
Runtime Walkthrough Init starts Linux daemons, including: • USB Daemon (usbd) to manage USB connections • Android Debug Bridge (adbd) to manage ADB connections • Debugger Daemon (debuggerd) to manage debug processes requests (dump memory, etc.) • Radio Interface Layer Daemon (rild) to manage communication with the radio Init usbd adbd debuggerd rild
Runtime Walkthrough Init process starts the zygote process: • A nascent process which initializes a Dalvik VM instance • Loads classes and listens on socket for requests to spawn VMs • Forks on request to create VM instances for managed processes • Copy-on-write to maximize re-use and minimize footprint usbdadbddebuggerddaemons Init Zygote
Runtime Walkthrough Init starts runtime process: • Initializes Service Manager – the context manager for Binder that handles service registration and lookup • Registers Service Manager as default context manager for Binder services runtime Service Manager usbdadbddebuggerddaemons Init Zygote
Runtime Walkthrough Runtime process sends request for Zygote to start System Service runtime Service Manager usbdadbddebuggerddaemons Init Zygote
Runtime Walkthrough Runtime process sends request for Zygote to start System Server • Zygote forks a new VM instance for the System Service process and starts the service Zygote DalvikVM usbdadbddebuggerddaemons System Server runtime Service Manager Init
Runtime Walkthrough System Service starts the native system servers, including: • Surface Flinger • Audio Flinger usbdadbddebuggerddaemons Zygoteruntime Service Manager DalvikVM System Server Init Surface Flinger Audio Flinger
Runtime Walkthrough Native system servers register with Service Manager as IPC service targets: Zygoteruntime Service Manager usbdadbddebuggerddaemons Init DalvikVM System Server Surface Flinger Audio Flinger
Runtime Walkthrough System Service starts the Android managed services: usbdadbddebuggerddaemons Zygoteruntime Service Manager DalvikVM System Server Init Window Manager Activity Manager Package Manager Power Manager … Content Manager Telephony Service Bluetooth Service Connectivity Service Location Manager Camera ServiceSurface Flinger
Runtime Walkthrough Android managed Services register with Service Manager: usbdadbddebuggerddaemons Camera Service Zygoteruntime Service Manager DalvikVM System Server Init Window Manager Activity Manager Package Manager Power Manager … Service Manager Content Manager Telephony Service Bluetooth Service Connectivity Service Location Manager Camera ServiceSurface Flinger
… Runtime Walkthrough usbdadbddebuggerddaemons Zygoteruntime Service Manager DalvikVM System Server Init Power ManagerActivity Manager Camera ServiceSurface Flinger
Runtime Walkthrough After system server loads all services, the system is ready… Init System Server Surface Flinger Audio Flinger DalvikVM Window Manager Activity Manager Package Manager … Init Daemon Processes usbdadbddebuggerddaemons runtime runtime Zygote Zygote
Runtime Walkthrough After system server loads all services, the system is ready… Init Init Daemon Processes usbdadbddebuggerddaemons runtime runtime Zygote Zygote Home DalvikVM Home System Server Surface Flinger Audio Flinger DalvikVM Window Manager Activity Manager Package Manager …
Runtime Walkthrough After system server loads all services, the system is ready… Init Init Daemon Processes usbdadbddebuggerddaemons runtime runtime Zygote Zygote Home DalvikVM Home libc libc libc libc libc System Server Surface Flinger Audio Flinger DalvikVM Window Manager Activity Manager Package Manager libc …
Runtime Walkthrough Each subsequent application is launched in itʼs own process System Server Surface Flinger Audio Flinger DalvikVM Window Manager Activity Manager Package Manager libc … Daemon Processes usbdadbddebuggerddaemons runtime runtime Zygote Zygote Home DalvikVM Home libc libc libc libc Contacts DalvikVM Contacts libc
Agenda • Android Anatomy • Linux Kernel • Native Libraries • Framework Services • Android Physiology • Start-up Walkthrough • Layer Interaction
Layer Interaction There are 3 main flavors of Android layer cake: • App  Runtime Service  lib • App  Runtime Service  Native Service  lib • App  Runtime Service  Native Daemon  lib
Layer Interaction There are 3 main flavors of Android layer cake: • App  Runtime Service  lib • App  Runtime Service  Native Service  lib • App  Runtime Service  Native Daemon  lib
Libraries Linux Kernel Applications Application Framework Android Runtime Services Binder IPC Application Runtime Service Kernel Driver
Libraries Applications Application Framework JNI Android Runtime Services Binder IPC Application Runtime Service Native Service Binding Linux Kernel Kernel Driver
Libraries Linux Kernel Applications Application Framework JNI Android Runtime Services Binder IPC Dynamic load Application Runtime Service Native Service Binding HAL Library Kernel Driver
Libraries Linux Kernel Applications Application Framework JNI Android Runtime Services Binder IPC Dynamic load Application Runtime Service Native Service Binding HAL Library Kernel Driver
Libraries Linux Kernel Applications Application Framework JNI Example: Location Manager Dynamic load Location Manager Service GpsLocationProvider libgps.so GpsLocationProvider Binder IPC Application Kernel Driver
Layer Interaction There are 3 main flavors of Android layer cake: • App  Runtime Service  lib • App  Runtime Service  Native Service  lib • App  Runtime Service  Native Daemon  lib
Libraries Linux Kernel Applications Application Framework JNI Android Native Services Application Runtime Service Native Service Binding
Libraries Linux Kernel Applications Application Framework JNI Android Native Services Application Runtime Service Native Service Binding Native Service Binder IPC
Libraries Linux Kernel Applications Application Framework JNI Android Native Services Application Runtime Service Native Service Binding HAL Library Native Service Binder IPC Dynamic load
Libraries Linux Kernel Applications Application Framework JNI Android Native Services Application Runtime Service Native Service Binding HAL Library Kernel Driver Native Service Binder IPC Dynamic load
Libraries Linux Kernel Applications Application Framework JNI Android Native Services Dynamic load Application MediaPlayer MediaPlayer libaudio.so Kernel Driver AudioFlinger Binder IPC Media Framework
Libraries Linux Kernel Applications Application Framework JNI Android Native Services Dynamic load Application MediaPlayer MediaPlayer libaudio.so AudioFlinger Binder IPC Media Framework ALSA Kernel Driver
Libraries Linux Kernel Applications Application Framework JNI Android Native Services Dynamic load Application MediaPlayer MediaPlayer libaudio.so AudioFlinger Binder IPC Media Framework Proprietary Audio Driver
Layer Interaction There are 3 main flavors of Android layer cake: • App  Runtime Service  lib • App  Runtime Service  Native Service  lib • App  Runtime Service  Native Daemon  lib
Daemon Connection Libraries Linux Kernel Applications Application Framework JNI Application Runtime Service Native Service Binding Kernel Driver
Daemon Connection Libraries Linux Kernel Applications Application Framework JNI Application Runtime Service Native Service Binding Kernel Driver Daemon sockets
Daemon Connection Libraries Linux Kernel Applications Application Framework JNI Dynamic load Application Runtime Service Native Service Binding HAL Library Kernel Driver Daemon sockets
Daemon Connection Libraries Linux Kernel Applications Application Framework JNI Dynamic load Application Telephony Manager Telephony Manager libril.so Kernel Driver rild sockets
Layer Interaction There are 3 main flavors of Android layer cake: • App  Runtime Service  lib • App  Runtime Service  Native Service  lib • App  Runtime Service  Native Daemon  lib
Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers Android Anatomy Applications Home Dialer Contacts SMS/MMS Email IM Calendar Browser Media Player Albums Camera Clock Calculator …Voice Dial Alarm Android Runtime DalvikVirtual Machine Core Libraries Application Framework View SystemContent Providers Resource Manager … Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager FreeType SGL SSL SQLite WebKit Libc Surface Manager OpenGL|ES Media Framework Libraries
The End code.google.com
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Android Anatomy google io 2008

  • 1. Android Anatomy and Physiology
  • 2. Agenda • Android Anatomy • Linux Kernel • Native Libraries • Android Runtime • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
  • 3. Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers Android Anatomy Applications Home Dialer Contacts SMS/MMS Email IM Calendar Browser Media Player Albums Camera Clock Calculator …Voice Dial Alarm Android Runtime DalvikVirtual Machine Core Libraries Application Framework View SystemContent Providers Resource Manager … Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager FreeType SGL SSL SQLite WebKit Libc Surface Manager OpenGL|ES Media Framework Libraries
  • 4. Agenda • Android Anatomy • Linux Kernel • Native Libraries • Android Runtime • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
  • 5. Linux Kernel • Android is built on the Linux kernel, but Android is not Linux • No native windowing system • No glibc support • Does not include the full set of standard Linux utilities Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers
  • 6. Linux Kernel • Standard Linux 2.6.24 Kernel • Patch of “kernel enhancements” to support Android Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers
  • 7. Why Linux Kernel? • Great memory and process management • Permissions-based security model • Proven driver model • Support for shared libraries • Itʼs already open source! Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers
  • 8. Kernel Enhancements • Alarm • Ashmem • Binder • Power Management • Low Memory Killer • Kernel Debugger • Logger Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers
  • 9. Binder: Problem Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers • Applications and Services may run in separate processes but must communicate and share data • IPC can introduce significant processing overhead and security holes
  • 10. Binder: Solution Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers • Driver to facilitate inter-process communication (IPC) • High performance through shared memory • Per-process thread pool for processing requests • Reference counting, and mapping of object references across processes • Synchronous calls between processes
  • 11. Process BProcess A Binder in Action App A Service B
  • 12. Process A Process B Binder in Action App A Service BContext
  • 13. Process BProcess A Binder in Action App A Service BContext get service
  • 14. Process BProcess A Binder in Action Binder DriverApp A Service BContext get service service
  • 15. Process BProcess A Binder in Action Binder DriverApp A Service BContext get service service
  • 16. Process BProcess A Binder in Action Binder DriverApp A Service BContext get service call foo(object) service
  • 17. Process BProcess A Binder in Action Binder DriverApp A Service BContext get service marshal proxy object call foo(object) service
  • 18. Process BProcess A Binder in Action Binder DriverApp A Service BContext get service relay to IPC threads marshal proxy object call foo(object) service
  • 19. Process BProcess A Binder in Action Binder DriverApp A Service BContext get service relay to IPC threads marshal proxy object call return call foo(object) service
  • 20. Binder Android Interface Definition Language (AIDL) • http://code.google.com/android/reference/aidl.html Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers
  • 21. PM Problem Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers • Mobile devices run on battery power • Batteries have limited capacity
  • 22. PM Solution Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers • Built on top of standard Linux Power Management (PM) • More aggressive power management policy • Components make requests to keep the power on through “wake locks” • Supports different types of wake locks
  • 23. Android PM in Action PM DriverApp A PowerManager
  • 24. Android PM in Action PM DriverApp A PowerManager new wake lock PARTIAL
  • 25. Android PM in Action PM DriverApp A PowerManager new wake lock PARTIAL create wake lock
  • 26. Android PM in Action PM DriverApp A PowerManager new wake lock PARTIAL create wake lock Turn off LCD
  • 27. Android PM in Action PM DriverApp A PowerManager new wake lock PARTIAL create wake lock Turn off LCD release release
  • 28. Android PM in Action PM DriverApp A PowerManager new wake lock PARTIAL create wake lock Turn off LCD release release Turn off CPU
  • 29. Android PM Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers android.os.PowerManager • Use wake locks carefully! • userActivity(long when, …);
  • 30. Kernel Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers The Android kernel source is available today at: http://git.android.com
  • 31. Agenda • Android Anatomy • Linux Kernel • Native Libraries • Android Runtime • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
  • 32. Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers Android Anatomy FreeType SGL SSL SQLite WebKit Libc Surface Manager OpenGL|ES Media Framework Libraries
  • 33. Native Libraries • Bionic Libc • Function Libraries • Native Servers • Hardware Abstraction Libraries Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
  • 34. Native Libraries • Bionic Libc • Function Libraries • Native Servers • Hardware Abstraction Libraries Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
  • 35. What is Bionic? • What is bionic? • Custom libc implementation, optimized for embedded use. Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
  • 36. Why Bionic? Why build a custom libc library? • License: we want to keep GPL out of user-space • Size: will load in each process, so it needs to be small • Fast: limited CPU power means we need to be fast Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
  • 37. Bionic libc • BSD License • Small size and fast code paths • Very fast and small custom pthread implementation Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
  • 38. Bionic libc • Built-in support for important Android-specific services • system properties getprop(“my.system.property”, buff, default); • log capabilities LOGI(“Logging a message with priority ‘Info’”); Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
  • 39. Bionic libc • Doesn't support certain POSIX features • Not compatible with Gnu Libc (glibc) • All native code must be compiled against bionic Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
  • 40. Native Libraries • Bionic Libc • Function Libraries • Native Servers • Hardware Abstraction Libraries Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
  • 41. WebKit • Based on open source WebKit browser: http://webkit.org • Renders pages in full (desktop) view • Full CSS, Javascript, DOM, AJAX support • Support for single-column and adaptive view rendering Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
  • 42. Media Framework • Based on PacketVideo OpenCORE platform • Supports standard video, audio, still-frame formats • Support for hardware / software codec plug-ins Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
  • 43. SQLite • Light-weight transactional data store • Back end for most platform data storage Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
  • 44. Native Libraries • Bionic Libc • Function Libraries • Native Servers • Hardware Abstraction Libraries Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
  • 45. Surface Flinger • Provides system-wide surface “composer”, handling all surface rendering to frame buffer device • Can combine 2D and 3D surfaces and surfaces from multiple applications Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager … App Surface Surface Surface Surface Flinger Frame Buffer App
  • 46. Surface Flinger • Surfaces passed as buffers via Binder IPC calls • Can use OpenGL ES and 2D hardware accelerator for its compositions • Double-buffering using page-flip Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
  • 47. Audio Flinger • Manages all audio output devices • Processes multiple audio streams into PCM audio out paths • Handles audio routing to various outputs Libraries FreeType SSL SQLite WebKit LibcSurface Manager OpenGL|ES Media Framework Audio Manager … App Tone Audio Media Player Game Audio Audio Flinger App Earpeace Speaker Bluetooth
  • 48. Native Libraries • Bionic Libc • Function Libraries • Native Servers • Hardware Abstraction Libraries Libraries FreeType SSL SQLite LibWebCore LibcSurface Manager OpenGL|ES Media Framework Audio Manager …
  • 49. Hardware Abstraction Layer Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers Applications Home Dialer Contacts SMS/MMS Email IM Calendar Browser Media Player Photo Album Camera Clock Calculator …Voice Dial Alarm Android Runtime DalvikVirtual Machine Core Libraries Application Framework View SystemContent Providers Resource Manager … Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager Libraries FreeType SSL SQLite WebKit Libc Surface Manager OpenGL|ES Media Framework Audio Manager … Hardware Abstraction Layer Graphics Audio Camera Bluetooth GPS Radio (RIL) WiFi …
  • 50. Hardware Abstraction Libraries • User space C/C++ library layer • Defines the interface that Android requires hardware “drivers” to implement • Separates the Android platform logic from the hardware interface Hardware Abstraction Layer Graphics Audio Camera Bluetooth GPS Radio (RIL) WiFi …
  • 51. Hardware Abstraction Libraries Why do we need a user-space HAL? • Not all components have standardized kernel driver interfaces • Kernel drivers are GPL which exposes any proprietary IP • Android has specific requirements for hardware drivers Hardware Abstraction Layer Graphics Audio Camera Bluetooth GPS Radio (RIL) WiFi …
  • 52. HAL Header Example // must be provided by each Acme hardware implementation typedef struct { int (*foo)( void ); char (*bar)( void ); … } AcmeFunctions; const AcmeFunctions *Acme_Init(const struct Env *env, int argc, char **argv); Hardware Abstraction Layer Graphics Audio Camera Bluetooth GPS Radio (RIL) WiFi …
  • 53. Hardware Abstraction Libraries • Libraries are loaded dynamically at runtime as needed dlHandle = dlopen(“/system/lib/libacme.so”, RTLD_NOW); ... acmeInit = (const AcmeFunctions *(*)(const struct Env *, int, char **))dlsym(dlHandle, ”Acme_Init"); ... acmeFuncs = acmeInit(&env, argc, argv); Hardware Abstraction Layer Graphics Audio Camera Bluetooth GPS Radio (RIL) WiFi …
  • 54. Agenda • Android Anatomy • Linux Kernel • Native Libraries • Android Runtime • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
  • 55. Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers Android Anatomy Android Runtime DalvikVirtual Machine Core Libraries FreeType SGL SSL SQLite WebKit Libc Surface Manager OpenGL|ES Media Framework Libraries
  • 56. Dalvik Virtual Machine • Androidʼs custom clean-room implementation virtual machine • Provides application portability and runtime consistency • Runs optimized file format (.dex) and Dalvik bytecode • Java .class / .jar files converted to .dex at build time Android Runtime DalvikVirtual Machine Core Libraries
  • 57. Dalvik Virtual Machine • Designed for embedded environment • Supports multiple virtual machine processes per device • Highly CPU-optimized bytecode interpreter • Uses runtime memory very efficiently Android Runtime DalvikVirtual Machine Core Libraries
  • 58. Core Libraries • Core APIs for Java language provide a powerful, yet simple and familiar development platform • Data structures • Utilities • File access • Network Access • Graphics • … Android Runtime DalvikVirtual Machine Core Libraries
  • 59. Agenda • Android Anatomy • Linux Kernel • Native Libraries • Android Runtime • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
  • 60. Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers Android Anatomy Libraries FreeType SGL SSL SQLite WebKit Libc Surface Manager OpenGL|ES Media Framework Android Runtime DalvikVirtual Machine Core Libraries Application Framework View SystemContent Providers Resource Manager … Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager
  • 61. • Services that are essential to the Android platform • Behind the scenes - applications typically donʼt access them directly Application Framework View SystemContent Providers Resource Manager … Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager Core Platform Services
  • 62. Application Framework View SystemContent Providers Resource Manager … Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager • Activity Manager Core Platform Services
  • 63. • Activity Manager • Package Manager Core Platform Services Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager …
  • 64. • Activity Manager • Package Manager • Window Manager Core Platform Services Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager …
  • 65. • Activity Manager • Package Manager • Window Manager • Resource Manager Core Platform Services Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager …
  • 66. • Activity Manager • Package Manager • Window Manager • Resource Manager • Content Providers Core Platform Services Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager …
  • 67. • Activity Manager • Package Manager • Window Manager • Resource Manager • Content Providers • View System Core Platform Services Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager …
  • 68. • Provide access to lower-level hardware APIs Hardware Services Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager …
  • 69. • Provide access to lower-level hardware APIs • Typically accessed through local Manager object LocationManager lm = (LocationManager) Context.getSystemService(Context.LOCATION_SERVICE); Hardware Services Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager …
  • 70. • Telephony Service Hardware Services Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager …
  • 71. • Telephony Service • Location Service Hardware Services Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager …
  • 72. • Telephony Service • Location Service • Bluetooth Service Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager … Hardware Services
  • 73. • Telephony Service • Location Service • Bluetooth Service • WiFi Service Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager … Hardware Services
  • 74. • Telephony Service • Location Service • Bluetooth Service • WiFi Service • USB Service Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager … Hardware Services
  • 75. • Telephony Service • Location Service • Bluetooth Service • WiFi Service • USB Service • Sensor Service Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager … Hardware Services
  • 76. More Information • At Google I/O • “Inside the Android Application Framework” • Online • http://code.google.com/android Application Framework View SystemContent Providers Resource Manager Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager … Application Framework
  • 77. Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers Android Anatomy Applications Home Dialer Contacts SMS/MMS Email IM Calendar Browser Media Player Albums Camera Clock Calculator …Voice Dial Alarm Android Runtime DalvikVirtual Machine Core Libraries Application Framework View SystemContent Providers Resource Manager … Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager FreeType SGL SSL SQLite WebKit Libc Surface Manager OpenGL|ES Media Framework Libraries
  • 78. Agenda • Android Anatomy • Linux Kernel • Native Libraries • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
  • 79. Agenda • Android Anatomy • Linux Kernel • Native Libraries • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
  • 80. Runtime Walkthrough It all starts with init… Similar to most Linux-based systems at startup, the bootloader loads the Linux kernel and starts the init process. Init Linux Kernel
  • 81. Runtime Walkthrough Init starts Linux daemons, including: • USB Daemon (usbd) to manage USB connections • Android Debug Bridge (adbd) to manage ADB connections • Debugger Daemon (debuggerd) to manage debug processes requests (dump memory, etc.) • Radio Interface Layer Daemon (rild) to manage communication with the radio Init usbd adbd debuggerd rild
  • 82. Runtime Walkthrough Init process starts the zygote process: • A nascent process which initializes a Dalvik VM instance • Loads classes and listens on socket for requests to spawn VMs • Forks on request to create VM instances for managed processes • Copy-on-write to maximize re-use and minimize footprint usbdadbddebuggerddaemons Init Zygote
  • 83. Runtime Walkthrough Init starts runtime process: • Initializes Service Manager – the context manager for Binder that handles service registration and lookup • Registers Service Manager as default context manager for Binder services runtime Service Manager usbdadbddebuggerddaemons Init Zygote
  • 84. Runtime Walkthrough Runtime process sends request for Zygote to start System Service runtime Service Manager usbdadbddebuggerddaemons Init Zygote
  • 85. Runtime Walkthrough Runtime process sends request for Zygote to start System Server • Zygote forks a new VM instance for the System Service process and starts the service Zygote DalvikVM usbdadbddebuggerddaemons System Server runtime Service Manager Init
  • 86. Runtime Walkthrough System Service starts the native system servers, including: • Surface Flinger • Audio Flinger usbdadbddebuggerddaemons Zygoteruntime Service Manager DalvikVM System Server Init Surface Flinger Audio Flinger
  • 87. Runtime Walkthrough Native system servers register with Service Manager as IPC service targets: Zygoteruntime Service Manager usbdadbddebuggerddaemons Init DalvikVM System Server Surface Flinger Audio Flinger
  • 88. Runtime Walkthrough System Service starts the Android managed services: usbdadbddebuggerddaemons Zygoteruntime Service Manager DalvikVM System Server Init Window Manager Activity Manager Package Manager Power Manager … Content Manager Telephony Service Bluetooth Service Connectivity Service Location Manager Camera ServiceSurface Flinger
  • 89. Runtime Walkthrough Android managed Services register with Service Manager: usbdadbddebuggerddaemons Camera Service Zygoteruntime Service Manager DalvikVM System Server Init Window Manager Activity Manager Package Manager Power Manager … Service Manager Content Manager Telephony Service Bluetooth Service Connectivity Service Location Manager Camera ServiceSurface Flinger
  • 91. Runtime Walkthrough After system server loads all services, the system is ready… Init System Server Surface Flinger Audio Flinger DalvikVM Window Manager Activity Manager Package Manager … Init Daemon Processes usbdadbddebuggerddaemons runtime runtime Zygote Zygote
  • 92. Runtime Walkthrough After system server loads all services, the system is ready… Init Init Daemon Processes usbdadbddebuggerddaemons runtime runtime Zygote Zygote Home DalvikVM Home System Server Surface Flinger Audio Flinger DalvikVM Window Manager Activity Manager Package Manager …
  • 93. Runtime Walkthrough After system server loads all services, the system is ready… Init Init Daemon Processes usbdadbddebuggerddaemons runtime runtime Zygote Zygote Home DalvikVM Home libc libc libc libc libc System Server Surface Flinger Audio Flinger DalvikVM Window Manager Activity Manager Package Manager libc …
  • 94. Runtime Walkthrough Each subsequent application is launched in itʼs own process System Server Surface Flinger Audio Flinger DalvikVM Window Manager Activity Manager Package Manager libc … Daemon Processes usbdadbddebuggerddaemons runtime runtime Zygote Zygote Home DalvikVM Home libc libc libc libc Contacts DalvikVM Contacts libc
  • 95. Agenda • Android Anatomy • Linux Kernel • Native Libraries • Framework Services • Android Physiology • Start-up Walkthrough • Layer Interaction
  • 96. Layer Interaction There are 3 main flavors of Android layer cake: • App  Runtime Service  lib • App  Runtime Service  Native Service  lib • App  Runtime Service  Native Daemon  lib
  • 97. Layer Interaction There are 3 main flavors of Android layer cake: • App  Runtime Service  lib • App  Runtime Service  Native Service  lib • App  Runtime Service  Native Daemon  lib
  • 98. Libraries Linux Kernel Applications Application Framework Android Runtime Services Binder IPC Application Runtime Service Kernel Driver
  • 99. Libraries Applications Application Framework JNI Android Runtime Services Binder IPC Application Runtime Service Native Service Binding Linux Kernel Kernel Driver
  • 100. Libraries Linux Kernel Applications Application Framework JNI Android Runtime Services Binder IPC Dynamic load Application Runtime Service Native Service Binding HAL Library Kernel Driver
  • 101. Libraries Linux Kernel Applications Application Framework JNI Android Runtime Services Binder IPC Dynamic load Application Runtime Service Native Service Binding HAL Library Kernel Driver
  • 102. Libraries Linux Kernel Applications Application Framework JNI Example: Location Manager Dynamic load Location Manager Service GpsLocationProvider libgps.so GpsLocationProvider Binder IPC Application Kernel Driver
  • 103. Layer Interaction There are 3 main flavors of Android layer cake: • App  Runtime Service  lib • App  Runtime Service  Native Service  lib • App  Runtime Service  Native Daemon  lib
  • 104. Libraries Linux Kernel Applications Application Framework JNI Android Native Services Application Runtime Service Native Service Binding
  • 105. Libraries Linux Kernel Applications Application Framework JNI Android Native Services Application Runtime Service Native Service Binding Native Service Binder IPC
  • 106. Libraries Linux Kernel Applications Application Framework JNI Android Native Services Application Runtime Service Native Service Binding HAL Library Native Service Binder IPC Dynamic load
  • 107. Libraries Linux Kernel Applications Application Framework JNI Android Native Services Application Runtime Service Native Service Binding HAL Library Kernel Driver Native Service Binder IPC Dynamic load
  • 108. Libraries Linux Kernel Applications Application Framework JNI Android Native Services Dynamic load Application MediaPlayer MediaPlayer libaudio.so Kernel Driver AudioFlinger Binder IPC Media Framework
  • 109. Libraries Linux Kernel Applications Application Framework JNI Android Native Services Dynamic load Application MediaPlayer MediaPlayer libaudio.so AudioFlinger Binder IPC Media Framework ALSA Kernel Driver
  • 110. Libraries Linux Kernel Applications Application Framework JNI Android Native Services Dynamic load Application MediaPlayer MediaPlayer libaudio.so AudioFlinger Binder IPC Media Framework Proprietary Audio Driver
  • 111. Layer Interaction There are 3 main flavors of Android layer cake: • App  Runtime Service  lib • App  Runtime Service  Native Service  lib • App  Runtime Service  Native Daemon  lib
  • 114. Daemon Connection Libraries Linux Kernel Applications Application Framework JNI Dynamic load Application Runtime Service Native Service Binding HAL Library Kernel Driver Daemon sockets
  • 115. Daemon Connection Libraries Linux Kernel Applications Application Framework JNI Dynamic load Application Telephony Manager Telephony Manager libril.so Kernel Driver rild sockets
  • 116. Layer Interaction There are 3 main flavors of Android layer cake: • App  Runtime Service  lib • App  Runtime Service  Native Service  lib • App  Runtime Service  Native Daemon  lib
  • 117. Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Driver Binder (IPC) Driver Power ManagementUSB Driver Keypad Driver WiFi Driver Audio Drivers Android Anatomy Applications Home Dialer Contacts SMS/MMS Email IM Calendar Browser Media Player Albums Camera Clock Calculator …Voice Dial Alarm Android Runtime DalvikVirtual Machine Core Libraries Application Framework View SystemContent Providers Resource Manager … Activity Manager Package Manager Window Manager Notification Manager Location Manager Telephony Manager FreeType SGL SSL SQLite WebKit Libc Surface Manager OpenGL|ES Media Framework Libraries