Android internals By Rajesh Khetan
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There are many books, articles and paper publications about Android and related applications but only a few are related to how Android operating system works internally.In this talk we will see how android boots up , an overview of zygote , how system server and package manager works. This talk will be extremely helpful to foster understanding among android developers about Android Internals as well as everybody else who desires a general understanding of the internal working of Android powered devices.
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Android internals By Rajesh Khetan
- 1. Android Internals RAJESH KHETAN Co-founder @ Bangalore Tech Events
- 2. Agenda Android Boot Up Process How Package Manager Service works ?
- 3. A Typical Android Boot-Up KERNEL Installd, adbd, servicemanger... System Server Zygote App 1 , App 2 …App N INIT
- 4. A Typical Android Boot-Up KERNEL Installd, adbd, servicemanger... System Server Zygote App 1 , App 2 …App N INIT
- 5. Kernel Special forked version of Linux Features : Wake locks Low Memory Killer (OOM adjustment) Provides Binder driver
- 6. A Typical Android Boot-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 Android Boot-Up KERNEL Installd, adbd, servicemanger... System Server Zygote App 1 , App 2 …App N INIT
- 9. A Typical Android Boot-Up KERNEL Installd, adbd, servicemanger... System Server Zygote App 1 , App 2 …App N INIT
- 10. Zygote Base of all 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 fork systemserver Preloads Classes And Resources Wait for requests fork()
- 12. Zygote Register Zygote Socket fork systemserver Preloads Classes And Resources Wait for requests fork()
- 13. Zygote Register Zygote Socket fork systemserver Preloads Classes And Resources Wait for requests fork()
- 14. Zygote Register Zygote Socket fork systemserver Preloads Classes And Resources Wait for requests fork()
- 15. Zygote Register Zygote Socket fork systemserver Preloads Classes And Resources Wait for requests fork()
- 16. A Typical Android Boot-Up KERNEL Installd, adbd, servicemanger... System Server Zygote App 1 , App 2 …App N INIT
- 17. A Typical Android Boot-Up KERNEL Installd, adbd, servicemanger... System Server Zygote App 1 , App 2 …App N INIT
- 18. System Server Heart of the Android System Start system services Register services with the service manager
- 19. System Server Creates system context Start bootstrap services Start Other Services Start core services ActivityManagerService PackageManagerService WindowManagerService Wifi/Bluetooth Service SystemUI Loads server library
- 20. System Server Creates system context Start bootstrap services Start Other Services Start core services ActivityManagerService PackageManagerService WindowManagerService Wifi/Bluetooth Service SystemUI Loads server library
- 21. System Server Creates system context Start bootstrap services Start Other Services Start core services ActivityManagerService PackageManagerService WindowManagerService Wifi/Bluetooth Service SystemUI Loads server library
- 22. System Server Creates system context Start bootstrap services Start Other Services Start core services ActivityManagerService PackageManagerService WindowManagerService Wifi/Bluetooth Service SystemUI Loads server library
- 23. System Server Creates system context Start bootstrap services Start Other Services Start core services ActivityManagerService PackageManagerService WindowManagerService Wifi/Bluetooth Service SystemUI Loads server library
- 24. System Server Creates system context Start bootstrap services Start Other Services Start core services ActivityManagerService PackageManagerService WindowManagerService Wifi/Bluetooth Service SystemUI Loads server library
- 25. System Server Creates system context Start bootstrap services Start Other Services Start core services ActivityManagerService PackageManagerService WindowManagerService Wifi/Bluetooth Service SystemUI Loads server library
- 26. System Server Creates system context Start bootstrap services Start Other Services Start core services ActivityManagerService PackageManagerService WindowManagerService Wifi/Bluetooth Service SystemUI Loads server library
- 27. System Server Creates system context 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) Scan Packages Grant Permissions Initialization Manifest Parsing Perform DexOpt Collect Certificates Generate Package Info Asset Loading
- 30. Package Manager Service(Flow) Scan Packages Grant Permissions Initialization Manifest Parsing Perform DexOpt Collect Certificates Generate Package Info Asset Loading
- 31. Package Manager Service(Flow) Scan Packages Grant Permissions Initialization Manifest Parsing Perform DexOpt Collect Certificates Generate Package Info Asset Loading
- 32. Package Manager Service(Flow) Scan Packages Grant Permissions Initialization Manifest Parsing Perform DexOpt Collect Certificates Generate Package Info Asset Loading
- 33. Package Manager Service(Flow) Scan Packages Grant Permissions Initialization Manifest Parsing Perform DexOpt Collect Certificates Generate Package Info Asset Loading
- 34. Package Manager Service(Flow) Scan Packages Grant Permissions Initialization Manifest Parsing Perform DexOpt Collect Certificates Generate Package Info Asset Loading
- 35. Package Manager Service(Flow) Scan Packages Grant Permissions Initialization Manifest Parsing Perform DexOpt Collect Certificates Generate Package Info Asset Loading
- 36. Package Manager Service(Flow) Scan Packages Grant Permissions Initialization Manifest Parsing Perform DexOpt Collect Certificates Generate Package Info Asset Loading
- 37. Package Manager Service(Flow) Scan Packages 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 ability to install, upgrade, and remove applications on the device.
- 40. PackageInstallerActivity Launched when a 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 lacks root 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 Native Daemons Zygote Launcher System Server Activity Manager Android Runtime Kernel Init
- 43. A Quick Recap Native Daemons Zygote Launcher System Server Activity Manager Android Runtime Kernel - Initialization - Mount root FS - Starts Init Process Init
- 44. A Quick Recap Native Daemons 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 Native Daemons - servicemanager - app_process -X Zygote - adbd - installd Zygote Launcher System Server Activity Manager Android Runtime Kernel Init
- 46. A Quick Recap Native Daemons Zygote Launcher System Server Activity Manager Android Runtime - Start first VM - Call zygote’s main method Kernel Init
- 47. A Quick Recap Native Daemons 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 Native Daemons Zygote Launcher System Server - Start services - Register with service manager Activity Manager Android Runtime Kernel Init
- 49. A Quick Recap Native Daemons Zygote Launcher System Server Activity Manager - Init itself - Send Intent.Category_HOME - Send BOOT_COMPLETE Android Runtime Kernel Init
- 50. A Quick Recap Native Daemons Zygote Launcher - Init itself - Register OnClick handlers System Server Activity Manager Android Runtime Kernel Init
- 51. A Quick Recap Native Daemons Zygote Launcher System Server Activity Manager Android Runtime Kernel Init Click
- 52. A Quick Recap Native Daemons Zygote Launcher System Server Activity Manager Android Runtime Kernel Init Click
- 53. A Quick Recap Native Daemons Zygote Launcher System Server Activity Manager Android Runtime Kernel Init Click
- 54. A Quick Recap Native Daemons Zygote Launcher System Server Activity Manager Android Runtime Kernel Init Click
- 55. A Quick Recap Native Daemons - 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 [email protected] Contact :