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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. Android Anatomy
Applications
Home Dialer SMS/MMS IM Browser Camera Alarm Calculator
Contacts Voice Dial Email Calendar Media Player Albums Clock …
Application Framework
Activity Manager Window View Notification
Manager Content Providers System Manager
Telephony Location
Package Manager Manager Resource Manager Manager …
Libraries Android Runtime
Surface Manager Core Libraries
Media Framework SQLite
OpenGL|ES FreeType WebKit Dalvik Virtual Machine
SGL SSL Libc
Linux Kernel
Display Driver Camera Driver Bluetooth Driver Shared Memory Binder (IPC) Driver
Driver
Audio Power
USB Driver Keypad Driver WiFi Driver Drivers Management

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
Shared Memory
Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver
Audio Power
USB Driver Keypad Driver WiFi Driver Drivers Management

6. Linux Kernel
• Standard Linux 2.6.24 Kernel
• Patch of “kernel enhancements” to support Android
Linux Kernel
Shared Memory
Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver
Audio Power
USB Driver Keypad Driver WiFi Driver Drivers Management

7. Why Linux Kernel?
• Great memory and process management
• Permissions-based security model
• Proven driver model
• Support for shared libraries
• It!s already open source!
Linux Kernel
Shared Memory
Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver
Audio Power
USB Driver Keypad Driver WiFi Driver Drivers Management

8. Kernel Enhancements
• Alarm
• Low Memory Killer
• Ashmem
• Kernel Debugger
• Binder
• Logger
• Power Management
Linux Kernel
Shared Memory
Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver
Audio Power
USB Driver Keypad Driver WiFi Driver Drivers Management

9. Binder: Problem
• Applications and Services may run in separate processes
but must communicate and share data
• IPC can introduce significant processing overhead and
security holes
Linux Kernel
Shared Memory
Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver
Audio Power
USB Driver Keypad Driver WiFi Driver Drivers Management

10. Binder: Solution
• 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
Linux Kernel
Shared Memory
Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver
Audio Power
USB Driver Keypad Driver WiFi Driver Drivers Management

11. Binder in Action
Process A Process B
App A Service B

12. Binder in Action
Process A Process B
App A Context Service B

13. Binder in Action
Process A Process B
App A Context Service B
get service

14. Binder in Action
Process A Process B
App A Context Binder Driver Service B
get service
service

15. Binder in Action
Process A Process B
App A Context Binder Driver Service B
get service
service

16. Binder in Action
Process A Process B
App A Context Binder Driver Service B
get service
service
call foo(object)

17. Binder in Action
Process A Process B
App A Context Binder Driver Service B
get service
service
call foo(object) marshal proxy
object

18. Binder in Action
Process A Process B
App A Context Binder Driver Service B
get service
service
call foo(object) marshal proxy
object
relay to
IPC threads

19. Binder in Action
Process A Process B
App A Context Binder Driver Service B
get service
service
call foo(object) marshal proxy
object
relay to
IPC threads
call return

20. Binder
Android Interface Definition Language (AIDL)
• http://code.google.com/android/reference/aidl.html
Linux Kernel
Shared Memory
Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver
Audio Power
USB Driver Keypad Driver WiFi Driver Drivers Management

21. PM Problem
• Mobile devices run on battery power
• Batteries have limited capacity
Linux Kernel
Shared Memory
Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver
Audio Power
USB Driver Keypad Driver WiFi Driver Drivers Management

22. PM Solution
• 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
Linux Kernel
Shared Memory
Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver
Audio Power
USB Driver Keypad Driver WiFi Driver Drivers Management

23. Android PM in Action
App A PowerManager PM Driver

24. Android PM in Action
App A PowerManager PM Driver
new wake lock
PARTIAL

25. Android PM in Action
App A PowerManager PM Driver
new wake lock
PARTIAL create wake lock

26. Android PM in Action
App A PowerManager PM Driver
new wake lock
PARTIAL create wake lock
Turn off
LCD

27. Android PM in Action
App A PowerManager PM Driver
new wake lock
PARTIAL create wake lock
Turn off
LCD
release
release

28. Android PM in Action
App A PowerManager PM Driver
new wake lock
PARTIAL create wake lock
Turn off
LCD
release
release
Turn off
CPU

29. Android PM
android.os.PowerManager
• Use wake locks carefully!
• userActivity(long when, …);
Linux Kernel
Shared Memory
Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver
Audio Power
USB Driver Keypad Driver WiFi Driver Drivers Management

30. Kernel
The Android kernel source is available today
at:
http://git.android.com
Linux Kernel
Shared Memory
Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver
Audio Power
USB Driver Keypad Driver WiFi Driver Drivers Management

31. Agenda
• Android Anatomy
• Linux Kernel
• Native Libraries
• Android Runtime
• Application Framework
• Android Physiology
• Start-up Walkthrough
• Layer Interaction

32. Android Anatomy
Libraries
Surface Manager Media Framework SQLite
OpenGL|ES FreeType WebKit
SGL SSL Libc
Linux Kernel
Display Driver Camera Driver Bluetooth Driver Shared Memory Binder (IPC) Driver
Driver
Audio Power
USB Driver Keypad Driver WiFi Driver Drivers Management

33. Native Libraries
• Bionic Libc
• Function Libraries
• Native Servers
• Hardware Abstraction Libraries
Libraries
Surface Manager Media Framework SQLite WebKit Libc
OpenGL|ES Audio Manager FreeType SSL …

34. Native Libraries
• Bionic Libc
• Function Libraries
• Native Servers
• Hardware Abstraction Libraries
Libraries
Surface Manager Media Framework SQLite WebKit Libc
OpenGL|ES Audio Manager FreeType SSL …

35. What is Bionic?
• What is bionic?
• Custom libc implementation, optimized for embedded use.
Libraries
Surface Manager Media Framework SQLite WebKit Libc
OpenGL|ES Audio Manager FreeType SSL …

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
Surface Manager Media Framework SQLite WebKit Libc
OpenGL|ES Audio Manager FreeType SSL …

37. Bionic libc
• BSD License
• Small size and fast code paths
• Very fast and small custom pthread implementation
Libraries
Surface Manager Media Framework SQLite WebKit Libc
OpenGL|ES Audio Manager FreeType SSL …

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
Surface Manager Media Framework SQLite WebKit Libc
OpenGL|ES Audio Manager FreeType SSL …

39. Bionic libc
• Doesn't support certain POSIX features
• Not compatible with Gnu Libc (glibc)
• All native code must be compiled against bionic
Libraries
Surface Manager Media Framework SQLite WebKit Libc
OpenGL|ES Audio Manager FreeType SSL …

40. Native Libraries
• Bionic Libc
• Function Libraries
• Native Servers
• Hardware Abstraction Libraries
Libraries
Surface Manager Media Framework SQLite WebKit Libc
OpenGL|ES Audio Manager FreeType SSL …

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
Surface Manager Media Framework SQLite WebKit Libc
OpenGL|ES Audio Manager FreeType SSL …

42. Media Framework
• Based on PacketVideo OpenCORE platform
• Supports standard video, audio, still-frame formats
• Support for hardware / software codec plug-ins
Libraries
Surface Manager Media Framework SQLite WebKit Libc
OpenGL|ES Audio Manager FreeType SSL …

43. SQLite
• Light-weight transactional data store
• Back end for most platform data storage
Libraries
Surface Manager Media Framework SQLite WebKit Libc
OpenGL|ES Audio Manager FreeType SSL …

44. Native Libraries
• Bionic Libc
• Function Libraries
• Native Servers
• Hardware Abstraction Libraries
Libraries
Surface Manager Media Framework SQLite WebKit Libc
OpenGL|ES Audio Manager FreeType SSL …

45. Surface Flinger
Surface
App
Surface Frame
Surface Flinger Buffer
App
Surface
• 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
Surface Manager Media Framework SQLite WebKit Libc
OpenGL|ES Audio Manager FreeType SSL …

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
Surface Manager Media Framework SQLite WebKit Libc
OpenGL|ES Audio Manager FreeType SSL …

47. Audio Flinger
Tone Earpeace
Audio
App
Media
Player Audio Flinger Speaker
App
Game Audio Bluetooth
• Manages all audio output devices
• Processes multiple audio streams into PCM audio out paths
• Handles audio routing to various outputs
Libraries
Surface Manager Media Framework SQLite WebKit Libc
OpenGL|ES Audio Manager FreeType SSL …

48. Native Libraries
• Bionic Libc
• Function Libraries
• Native Servers
• Hardware Abstraction Libraries
Libraries
Surface Manager Media Framework SQLite LibWebCore Libc
OpenGL|ES Audio Manager FreeType SSL …

49. Hardware Abstraction Layer
Applications
Home Dialer SMS/MMS IM Browser Camera Alarm Calculator
Contacts Voice Dial Email Calendar Media Player Photo Album Clock …
Application Framework
Activity Manager Window View Notification
Manager Content Providers System Manager
Telephony Location
Package Manager Manager Resource Manager Manager …
Libraries Android Runtime
Surface Media Core Libraries
Manager Framework SQLite WebKit Libc
Audio
OpenGL|ES Manager FreeType SSL … Dalvik Virtual Machine
Hardware Abstraction Layer
Graphics Audio Camera Bluetooth GPS Radio (RIL) WiFi …
Linux Kernel
Shared Memory
Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver
Audio Power
USB Driver Keypad Driver WiFi Driver Drivers Management

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. Android Anatomy
Libraries Android Runtime
Surface Manager Core Libraries
Media Framework SQLite
OpenGL|ES FreeType WebKit Dalvik Virtual Machine
SGL SSL Libc
Linux Kernel
Display Driver Camera Driver Bluetooth Driver Shared Memory Binder (IPC) Driver
Driver
Audio Power
USB Driver Keypad Driver WiFi Driver Drivers Management

56. Dalvik Virtual Machine
• Android!s 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
Core Libraries
Dalvik Virtual Machine

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
Core Libraries
Dalvik Virtual Machine

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
Core Libraries
Dalvik Virtual Machine

59. Agenda
• Android Anatomy
• Linux Kernel
• Native Libraries
• Android Runtime
• Application Framework
• Android Physiology
• Start-up Walkthrough
• Layer Interaction

60. Android Anatomy
Application Framework
Activity Manager Window View Notification
Manager Content Providers System Manager
Telephony Location
Package Manager Manager Resource Manager Manager …
Libraries Android Runtime
Surface Manager Core Libraries
Media Framework SQLite
OpenGL|ES FreeType WebKit Dalvik Virtual Machine
SGL SSL Libc
Linux Kernel
Display Driver Camera Driver Bluetooth Driver Shared Memory Binder (IPC) Driver
Driver
Audio Power
USB Driver Keypad Driver WiFi Driver Drivers Management

61. Core Platform Services
• Services that are essential to the Android platform
• Behind the scenes - applications typically don!t access them
directly
Application Framework
Activity Manager Window View Notification
Manager Content Providers System Manager
Telephony Location
Package Manager Manager Resource Manager Manager …

62. Core Platform Services
• Activity Manager
Application Framework
Activity Manager Window View Notification
Manager Content Providers System Manager
Telephony Location
Package Manager Manager Resource Manager Manager …

63. Core Platform Services
• Activity Manager
• Package Manager
Application Framework
Activity Manager Window View Notification
Manager Content Providers System Manager
Telephony Location
Package Manager Manager Resource Manager Manager …

64. Core Platform Services
• Activity Manager
• Package Manager
• Window Manager
Application Framework
Activity Manager Window View Notification
Manager Content Providers System Manager
Telephony Location
Package Manager Manager Resource Manager Manager …

65. Core Platform Services
• Activity Manager
• Package Manager
• Window Manager
• Resource Manager
Application Framework
Activity Manager Window View Notification
Manager Content Providers System Manager
Telephony Location
Package Manager Manager Resource Manager Manager …

66. Core Platform Services
• Activity Manager
• Package Manager
• Window Manager
• Resource Manager
• Content Providers
Application Framework
Activity Manager Window View Notification
Manager Content Providers System Manager
Telephony Location
Package Manager Manager Resource Manager Manager …

67. Core Platform Services
• Activity Manager
• Package Manager
• Window Manager
• Resource Manager
• Content Providers
• View System
Application Framework
Activity Manager Window View Notification
Manager Content Providers System Manager
Telephony Location
Package Manager Manager Resource Manager Manager …

68. Hardware Services
• Provide access to lower-level hardware APIs
Application Framework
Activity Manager Window View Notification
Manager Content Providers System Manager
Telephony Location
Package Manager Manager Resource Manager Manager …

69. Hardware Services
• Provide access to lower-level hardware APIs
• Typically accessed through local Manager object
LocationManager lm = (LocationManager)
Context.getSystemService(Context.LOCATION_SERVICE);
Application Framework
Activity Manager Window View Notification
Manager Content Providers System Manager
Telephony Location
Package Manager Manager Resource Manager Manager …

70. Hardware Services
• Telephony Service
Application Framework
Activity Manager Window View Notification
Manager Content Providers System Manager
Telephony Location
Package Manager Manager Resource Manager Manager …

71. Hardware Services
• Telephony Service
• Location Service
Application Framework
Activity Manager Window View Notification
Manager Content Providers System Manager
Telephony Location
Package Manager Manager Resource Manager Manager …

72. Hardware Services
• Telephony Service
• Location Service
• Bluetooth Service
Application Framework
Activity Manager Window View Notification
Manager Content Providers System Manager
Telephony Location
Package Manager Manager Resource Manager Manager …

73. Hardware Services
• Telephony Service
• Location Service
• Bluetooth Service
• WiFi Service
Application Framework
Activity Manager Window View Notification
Manager Content Providers System Manager
Telephony Location
Package Manager Manager Resource Manager Manager …

74. Hardware Services
• Telephony Service
• Location Service
• Bluetooth Service
• WiFi Service
• USB Service
Application Framework
Activity Manager Window View Notification
Manager Content Providers System Manager
Telephony Location
Package Manager Manager Resource Manager Manager …

75. Hardware Services
• Telephony Service
• Location Service
• Bluetooth Service
• WiFi Service
• USB Service
• Sensor Service
Application Framework
Activity Manager Window View Notification
Manager Content Providers System Manager
Telephony Location
Package Manager Manager Resource Manager Manager …

76. Application Framework
More Information
• At Google I/O
• “Inside the Android Application Framework”
• Online
• http://code.google.com/android
Application Framework
Activity Manager Window View Notification
Manager Content Providers System Manager
Telephony Location
Package Manager Manager Resource Manager Manager …

77. Android Anatomy
Applications
Home Dialer SMS/MMS IM Browser Camera Alarm Calculator
Contacts Voice Dial Email Calendar Media Player Albums Clock …
Application Framework
Activity Manager Window View Notification
Manager Content Providers System Manager
Telephony Location
Package Manager Manager Resource Manager Manager …
Libraries Android Runtime
Surface Manager Core Libraries
Media Framework SQLite
OpenGL|ES FreeType WebKit Dalvik Virtual Machine
SGL SSL Libc
Linux Kernel
Display Driver Camera Driver Bluetooth Driver Shared Memory Binder (IPC) Driver
Driver
Audio Power
USB Driver Keypad Driver WiFi Driver Drivers Management

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
usbd adbd debuggerd rild
Init

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
usbd
adbd
debuggerd
daemons Zygote
Init

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
Service
Manager
usbd
adbd
debuggerd
daemons runtime Zygote
Init

84. Runtime Walkthrough
Runtime process sends request for Zygote to start System
Service
Service
Manager
usbd
adbd
debuggerd
daemons runtime Zygote
Init

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
Service System
Manager Server
usbd
adbd
debuggerd
daemons runtime Zygote Dalvik VM
Init

86. Runtime Walkthrough
System Service starts the native system servers, including:
• Surface Flinger
• Audio Flinger
Audio Flinger
Surface
Flinger
Service System
Manager Server
usbd
adbd
debuggerd
daemons runtime Zygote Dalvik VM
Init

87. Runtime Walkthrough
Native system servers register with Service Manager as IPC
service targets:
Audio Flinger
Surface
Flinger
Service System
Manager Server
usbd
adbd
debuggerd
daemons runtime Zygote Dalvik VM
Init

88. Runtime Walkthrough
System Service starts the Android managed services:
Content Telephony Bluetooth Connectivity Location
Manager Service Service Service Manager
Window Activity Package Power
Manager Manager Manager Manager …
Camera
Surface
Service
Flinger
Service System
Manager Server
usbd
adbd
debuggerd
daemons runtime Zygote Dalvik VM
Init

89. Runtime Walkthrough
Android managed Services register with Service Manager:
Content Telephony Bluetooth Connectivity Location
Manager Service Service Service Manager
Window Activity Package Power
Manager Manager Manager Manager …
Service
Camera
Manager
Service Camera
Surface
Service
Flinger
Service System
Manager Server
usbd
adbd
debuggerd
daemons runtime Zygote Dalvik VM
Init

90. Runtime Walkthrough
…
Power
Manager
Activity
Manager
Camera
Surface
Service
Flinger
Service System
Manager Server
usbd
adbd
debuggerd
daemons runtime Zygote Dalvik VM
Init

91. Runtime Walkthrough
After system server loads all services, the system is ready…
Init Daemon runtime Zygote System
Processes Server
Activity
Manager
Package
Manager
Window
Manager
…
Dalvik VM
Surface
Flinger
usbd
adbd
Init debuggerd
daemons runtime Zygote Audio
Flinger

92. Runtime Walkthrough
After system server loads all services, the system is ready…
Init Daemon runtime Zygote System Home
Processes Server
Home
Activity
Manager Dalvik VM
Package
Manager
Window
Manager
…
Dalvik VM
Surface
Flinger
usbd
adbd
Init debuggerd
daemons runtime Zygote Audio
Flinger

93. Runtime Walkthrough
After system server loads all services, the system is ready…
Init Daemon runtime Zygote System Home
Processes Server
Activity Home
Manager
Package Dalvik VM
Manager
Window
Manager
…
Dalvik VM
Surface
Flinger
usbd
adbd
Init debuggerd
daemons runtime Zygote Audio
Flinger
libc libc libc libc libc libc

94. Runtime Walkthrough
Each subsequent application is launched in it!s own process
Daemon runtime Zygote System Home Contacts
Processes Server
Activity Home Contacts
Manager
Package Dalvik VM Dalvik VM
Manager
Window
Manager
…
Dalvik VM
Surface
Flinger
usbd
adbd
debuggerd
daemons runtime Zygote Audio
Flinger
libc libc libc libc libc 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. Android Runtime Services
Applications
Application
Binder IPC
Application Framework
Runtime Service
Libraries
Linux Kernel
Kernel Driver

99. Android Runtime Services
Applications
Application
Binder IPC
Application Framework
Runtime Service
JNI
Libraries
Native Service Binding
Linux Kernel
Kernel Driver

100. Android Runtime Services
Applications
Application
Binder IPC
Application Framework
Runtime Service
JNI
Libraries
Native Service Binding
Dynamic load
HAL Library
Linux Kernel
Kernel Driver

101. Android Runtime Services
Applications
Application
Binder IPC
Application Framework
Runtime Service
JNI
Libraries
Native Service Binding
Dynamic load
HAL Library
Linux Kernel
Kernel Driver

102. Example: Location Manager
Applications
Binder IPC
Application
Application Framework
Location Manager Service
GpsLocationProvider
JNI
Libraries
GpsLocationProvider
Dynamic load
libgps.so
Linux Kernel
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. Android Native Services
Applications
Application
Application
Framework Runtime
Service
JNI
Libraries
Native Service
Binding
Linux Kernel

105. Android Native Services
Applications
Application
Application
Framework Runtime
Service
JNI
Libraries
Binder IPC
Native Service Native Service
Binding
Linux Kernel

106. Android Native Services
Applications
Application
Application
Framework Runtime
Service
JNI
Libraries
Binder IPC
Native Service Native Service
Binding
Dynamic load
HAL Library
Linux Kernel

107. Android Native Services
Applications
Application
Application
Framework Runtime
Service
JNI
Libraries
Binder IPC
Native Service Native Service
Binding
Dynamic load
HAL Library
Linux Kernel
Kernel Driver

108. Android Native Services
Applications
Application
Application
Framework MediaPlayer
JNI
Libraries
Binder IPC
MediaPlayer AudioFlinger
Dynamic load
Media
Framework libaudio.so
Linux Kernel
Kernel Driver

109. Android Native Services
Applications
Application
Application
Framework MediaPlayer
JNI
Libraries
Binder IPC
MediaPlayer AudioFlinger
Dynamic load
Media libaudio.so
Framework
ALSA
Linux Kernel
Kernel Driver

110. Android Native Services
Applications
Application
Application
Framework MediaPlayer
JNI
Libraries
Binder IPC
MediaPlayer AudioFlinger
Dynamic load
Media libaudio.so
Framework
Proprietary
Audio Driver
Linux Kernel

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

112. Daemon Connection
Applications
Application
Application
Framework Runtime
Service
JNI
Libraries
Native Service
Binding
Linux Kernel
Kernel Driver

113. Daemon Connection
Applications
Application
Application
Framework Runtime
Service
JNI
Libraries
sockets
Native Service Daemon
Binding
Linux Kernel
Kernel Driver

114. Daemon Connection
Applications
Application
Application
Framework Runtime
Service
JNI
Libraries
sockets
Native Service Daemon
Binding
Dynamic load
HAL Library
Linux Kernel
Kernel Driver

115. Daemon Connection
Applications
Application
Application
Framework Telephony Manager
JNI
Libraries
sockets
Telephony rild
Manager
Dynamic load
libril.so
Linux Kernel
Kernel Driver

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. Android Anatomy
Applications
Home Dialer SMS/MMS IM Browser Camera Alarm Calculator
Contacts Voice Dial Email Calendar Media Player Albums Clock …
Application Framework
Activity Manager Window View Notification
Manager Content Providers System Manager
Telephony Location
Package Manager Manager Resource Manager Manager …
Libraries Android Runtime
Surface Manager Core Libraries
Media Framework SQLite
OpenGL|ES FreeType WebKit Dalvik Virtual Machine
SGL SSL Libc
Linux Kernel
Display Driver Camera Driver Bluetooth Driver Shared Memory Binder (IPC) Driver
Driver
Audio Power
USB Driver Keypad Driver WiFi Driver Drivers Management