1-android internals 10305904_nimit

8/10/2019 1-Android Internals 10305904_nimit

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Android Kernel Runtime Walkthrough

Zygote

Binder (IPC) Driver

Layer Interaction JNI

Contents


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Why Linux Kernel ? Good memory and processmanagement

Permission-based security model

Proven driver model

Support for shared libraries

Provide core system services

Android Kernel


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Enhancements to Linux Kernel Binder (IPC) Driver

Ashmem ( Android shared memorydriver )

Alarm Driver and Logger

Power Management

Low Memory Killer


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Zygote

Binder (IPC) Driver


Contents


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Similar to Linux based system Boot-loader loads the Linux kernel

Runtime Walkthrough


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Kernel Initializes environment

Mounts root file system

Starts the Init process

Runtime Walkthrough


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Init starts daemons

Runtime Walkthrough


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Init starts the zygote process Initializes a Dalvik VM instance

Links all core libraries and share it

Use copy-on-write

Runtime Walkthrough


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Init starts runtime process Initializes Service Manager

Context manager for Binder

Runtime Walkthrough


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Start native services Surface and Audio Flinger

Runtime Walkthrough

Image is taken from : https://sites.google.com/site/io/anatomy--physiology-of-an-android


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Runtime Walkthrough



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Zygote

Binder (IPC) Driver


Contents


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What is IPC? Exchanges data with anotherprocess

Why IPC? Owns address space

Provides data isolation

Avoids direct interaction

Inter-Process

Communication IPC)


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Linux Signal

Pipe

Socket Semaphore

Message Queue

Shared Memory

IPC Mechanisms


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Android Binder : Lightweight RPC (RemoteProcedure Call) mechanism

IPC Mechanisms


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Problems with old IPCMechanisms

Separate processes

Security holes

IPC Mechanisms


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SolutionDriver

Shared memory

Per-process thread pool

Synchronous

IPC Mechanisms


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Binder with Service Manager


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Binder in Transaction

Image is taken from : http://www.slideshare.net/jserv/android-ipc-mechanism


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Not ideal for transferringlarge data

Data has to be converted intoParcel

Limitation of Binder


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Zygote

Binder (IPC) Driver

Layer InteractionJNI

Contents


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Application Runtime Service

lib Application Runtime Service

Native Service lib

Application Runtime Service Native Daemon lib

Depends on type of application,and type of native library.

Layer Interaction


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Bridge between Application

framework layer and Libraries.

Call gate for languages, like C orC++

Java Native Interface JNI)


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Runtime

Service


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Example:

Runtime

Service


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Native

Service


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Example:

Native

Service


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Native

Daemon


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Example:

Native

Daemon


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Image is taken from : https://events.linuxfoundation.org/.../abs2011_yaghmour_internals.ppt


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References

A Survey on Android vs. Linux, Frank Maker1 and

Yu-Hsuan Chan

Android Interprocess Communication By, ThorstenSchreiber

Android Devlopers Team, http://developer.android.com/guide/basics/what-is-android.html[Online; accessed on 25-02-2013]

Patrick Brady, https://sites.google.com/site/io/anatomy--physiology-of-an-android [Online;accessed on 25-02-2013]


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References

Jim Huang, http://www.slideshare.net

/jserv/android-ipc-mechanism [Online; accessed on25-02-2013]

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