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Android internals By Rajesh Khetan
The document discusses the Android boot-up process, detailing the roles of kernel, init, zygote, and system server components in starting the system and managing applications. It explains the function of the package manager service in app installation, permissions management, and the workflow involved in handling applications on the device. Additionally, it highlights the initialization sequence and responsibilities of various native daemons essential for Android operations.
Android internals By Rajesh Khetan
- 1. Android Internals RAJESH KHETAN Co-founder@ Bangalore Tech Events
- 2. Agenda Android BootUp Process How Package Manager Service works ?
- 3. A Typical AndroidBoot-Up KERNEL Installd, adbd, servicemanger... System Server Zygote App 1 , App 2 …App N INIT
- 4. A Typical AndroidBoot-Up KERNEL Installd, adbd, servicemanger... System Server Zygote App 1 , App 2 …App N INIT
- 5. Kernel Special forkedversion of Linux Features : Wake locks Low Memory Killer (OOM adjustment) Provides Binder driver
- 6. A Typical AndroidBoot-Up KERNEL Installd, adbd, servicemanger... System Server Zygote App 1 , App 2 …App N INIT
- 7. INIT Root /First User Space process Responsibilities : Set up file system permissions Start native daemons
- 8. A Typical AndroidBoot-Up KERNEL Installd, adbd, servicemanger... System Server Zygote App 1 , App 2 …App N INIT
- 9. A Typical AndroidBoot-Up KERNEL Installd, adbd, servicemanger... System Server Zygote App 1 , App 2 …App N INIT
- 10. Zygote Base ofall other java processes The app_process command invokes Android Runtime to start the first DVM/ART The VM then invokes zygotes main method (ZygoteInit.java)
- 11. Zygote Register Zygote Socket forksystemserver Preloads Classes And Resources Wait for requests fork()
- 12. Zygote Register Zygote Socket forksystemserver Preloads Classes And Resources Wait for requests fork()
- 13. Zygote Register Zygote Socket forksystemserver Preloads Classes And Resources Wait for requests fork()
- 14. Zygote Register Zygote Socket forksystemserver Preloads Classes And Resources Wait for requests fork()
- 15. Zygote Register Zygote Socket forksystemserver Preloads Classes And Resources Wait for requests fork()
- 16. A Typical AndroidBoot-Up KERNEL Installd, adbd, servicemanger... System Server Zygote App 1 , App 2 …App N INIT
- 17. A Typical AndroidBoot-Up KERNEL Installd, adbd, servicemanger... System Server Zygote App 1 , App 2 …App N INIT
- 18. System Server Heartof the Android System Start system services Register services with the service manager
- 19. System Server Creates systemcontext Start bootstrap services Start Other Services Start core services ActivityManagerService PackageManagerService WindowManagerService Wifi/Bluetooth Service SystemUI Loads server library
- 20. System Server Creates systemcontext Start bootstrap services Start Other Services Start core services ActivityManagerService PackageManagerService WindowManagerService Wifi/Bluetooth Service SystemUI Loads server library
- 21. System Server Creates systemcontext Start bootstrap services Start Other Services Start core services ActivityManagerService PackageManagerService WindowManagerService Wifi/Bluetooth Service SystemUI Loads server library
- 22. System Server Creates systemcontext Start bootstrap services Start Other Services Start core services ActivityManagerService PackageManagerService WindowManagerService Wifi/Bluetooth Service SystemUI Loads server library
- 23. System Server Creates systemcontext Start bootstrap services Start Other Services Start core services ActivityManagerService PackageManagerService WindowManagerService Wifi/Bluetooth Service SystemUI Loads server library
- 24. System Server Creates systemcontext Start bootstrap services Start Other Services Start core services ActivityManagerService PackageManagerService WindowManagerService Wifi/Bluetooth Service SystemUI Loads server library
- 25. System Server Creates systemcontext Start bootstrap services Start Other Services Start core services ActivityManagerService PackageManagerService WindowManagerService Wifi/Bluetooth Service SystemUI Loads server library
- 26. System Server Creates systemcontext Start bootstrap services Start Other Services Start core services ActivityManagerService PackageManagerService WindowManagerService Wifi/Bluetooth Service SystemUI Loads server library
- 27. System Server Creates systemcontext Start bootstrap services Start Other Services Start core services ActivityManagerService PackageManagerService WindowManagerService Wifi/Bluetooth Service SystemUI Loads server library
- 28. Package Manager Service Responsibilties : Installation/Uninstallation of apps Managing Permissions & Certificate Handling Exposing APIs to 3rd party applications
- 29. Package Manager Service(Flow) ScanPackages Grant Permissions Initialization Manifest Parsing Perform DexOpt Collect Certificates Generate Package Info Asset Loading
- 30. Package Manager Service(Flow) ScanPackages Grant Permissions Initialization Manifest Parsing Perform DexOpt Collect Certificates Generate Package Info Asset Loading
- 31. Package Manager Service(Flow) ScanPackages Grant Permissions Initialization Manifest Parsing Perform DexOpt Collect Certificates Generate Package Info Asset Loading
- 32. Package Manager Service(Flow) ScanPackages Grant Permissions Initialization Manifest Parsing Perform DexOpt Collect Certificates Generate Package Info Asset Loading
- 33. Package Manager Service(Flow) ScanPackages Grant Permissions Initialization Manifest Parsing Perform DexOpt Collect Certificates Generate Package Info Asset Loading
- 34. Package Manager Service(Flow) ScanPackages Grant Permissions Initialization Manifest Parsing Perform DexOpt Collect Certificates Generate Package Info Asset Loading
- 35. Package Manager Service(Flow) ScanPackages Grant Permissions Initialization Manifest Parsing Perform DexOpt Collect Certificates Generate Package Info Asset Loading
- 36. Package Manager Service(Flow) ScanPackages Grant Permissions Initialization Manifest Parsing Perform DexOpt Collect Certificates Generate Package Info Asset Loading
- 37. Package Manager Service(Flow) ScanPackages Grant Permissions Initialization Manifest Parsing Perform DexOpt Collect Certificates Generate Package Info Asset Loading
- 38. Package Manager Service Package information is cached into /data/system/packages.xml Runtime permissions are cached into /data/system/0/runtime_packages.xml
- 39. PackageIntsaller Offers the abilityto install, upgrade, and remove applications on the device.
- 40. PackageInstallerActivity Launched whena new application is installed via side loading Display parsing errors via a dialog. Enable unknown applications setting. Memory check Check for same existing package Install app
- 41. Installd PMS lacksroot privileges Creating , deleting & changing the ownership of applications directories requires superuser capabilities . The PMS delegates these operations to the installd daemon
- 42. A Quick Recap NativeDaemons Zygote Launcher System Server Activity Manager Android Runtime Kernel Init
- 43. A Quick Recap NativeDaemons Zygote Launcher System Server Activity Manager Android Runtime Kernel - Initialization - Mount root FS - Starts Init Process Init
- 44. A Quick Recap NativeDaemons Zygote Launcher System Server Activity Manager Android Runtime Kernel Init - Set up env variables - Mount FS - Set UP FS perm - Start native daemons
- 45. A Quick Recap NativeDaemons - servicemanager - app_process -X Zygote - adbd - installd Zygote Launcher System Server Activity Manager Android Runtime Kernel Init
- 46. A Quick Recap NativeDaemons Zygote Launcher System Server Activity Manager Android Runtime - Start first VM - Call zygote’s main method Kernel Init
- 47. A Quick Recap NativeDaemons Zygote - Register Zygote socket - Preload classes & res. - Start systemserver process - Listen for connections Launcher System Server Activity Manager Android Runtime Kernel Init
- 48. A Quick Recap NativeDaemons Zygote Launcher System Server - Start services - Register with service manager Activity Manager Android Runtime Kernel Init
- 49. A Quick Recap NativeDaemons Zygote Launcher System Server Activity Manager - Init itself - Send Intent.Category_HOME - Send BOOT_COMPLETE Android Runtime Kernel Init
- 50. A Quick Recap NativeDaemons Zygote Launcher - Init itself - Register OnClick handlers System Server Activity Manager Android Runtime Kernel Init
- 51. A Quick Recap NativeDaemons Zygote Launcher System Server Activity Manager Android Runtime Kernel Init Click
- 52. A Quick Recap NativeDaemons Zygote Launcher System Server Activity Manager Android Runtime Kernel Init Click
- 53. A Quick Recap NativeDaemons Zygote Launcher System Server Activity Manager Android Runtime Kernel Init Click
- 54. A Quick Recap NativeDaemons Zygote Launcher System Server Activity Manager Android Runtime Kernel Init Click
- 55. A Quick Recap NativeDaemons - servicemanager - app_process -X Zygote - adbd - installd Zygote - Register Zygote socket - Preload classes & resources - Start systemserver process - Listen for connections Launcher - Init itself - Register OnClick handlers Click System Server - Start services - Register with servicemanager Activity Manager - Init itself - Send Intent.Category_HOME - Send BOOT_COMPLETE broadcast New app Android Runtime - Start first VM - Call zygote’s main method Kernel - Initialization - Mount root FS - Starts Init Process Init - Set up env variables - Mount FS - Set UP FS perm - Start native daemons
- 56. THANK YOU References: Embedded Android – Karim Yaghmour https://android.googlesource.com/ www.bangaloretechevents.com rajeshkhetan.rk@gmail.com Contact :