Android Avin Notes

8/12/2019 Android Avin Notes

1/8

This document is a self note on Android.Android is open source platform acquired by google in 2007.

Androidis an operating systembased on the Linux kernel,[12]and designed

primarily for touchscreenmobile devices such as smartphonesand tablet

computers. Initially developedbyAndroid, Inc., which Googlebacked

financially and later bought in 2005,[13]Android was unveiled in 2007 along

with the founding of the Open Handset Alliancea consortium of hardware,

software, and telecommunication companies devoted to advancing open

standardsfor mobile devices.[14]The first publicly available smartphone

running Android, theHTC Dream, was released on October 22, 2008.[15]

The user interfaceof Android is based on direct manipulation, using touchinputs that loosely correspond to real-world actions, like swiping, tapping,

pinching andreverse pinching to manipulate on-screen objects. Internal

hardware such as accelerometers, gyroscopesand proximity sensorsare

used by some applications to respond to additional user actions, for example

adjusting the screen from portrait to landscape depending on how the device

is oriented. Android allows users to customize their home screens with

shortcuts to applications and widgets, which allow users to display live

content, such as emails and weather information, directly on the home screen.Applications can further send notifications to the user to inform them of

relevant information, such as new emailsand text messages.

Interface

Notifications are accessed by sliding from the top of the display; individual notifications can

be dismissed by sliding them away, and may contain additionalfunctions (such as on the

"missed call" notification seen here).

Android's user interface is basedon direct manipulation,[47]using touch inputs

that loosely correspond to real-world actions, like swiping, tapping, pinching

and reverse pinching to manipulate on-screen objects.[47]The response to

user input is designed to be immediate and provides a fluidtouch interface,

often using the vibration capabilities of the device to provide haptic feedback

to the user. Internal hardware such as accelerometers,gyroscopesand

proximity sensors[48]areused by some applications to respond to additionaluser actions, for example adjusting the screen from portrait to landscape
http://en.wikipedia.org/wiki/Proximity_sensorhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-48http://en.wikipedia.org/wiki/Accelerometerhttp://en.wikipedia.org/wiki/Gyroscopehttp://en.wikipedia.org/wiki/Haptic_feedbackhttp://en.wikipedia.org/wiki/Haptic_feedbackhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-touch-47http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-touch-47http://en.wikipedia.org/wiki/Direct_manipulation_interfacehttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-touch-47http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-touch-47http://en.wikipedia.org/wiki/File:Android_notification_area.pnghttp://en.wikipedia.org/wiki/Software_widgethttp://en.wikipedia.org/wiki/User_interfacehttp://en.wikipedia.org/wiki/Direct_manipulationhttp://en.wikipedia.org/wiki/User_interfacehttp://en.wikipedia.org/wiki/HTC_Dreamhttp://en.wikipedia.org/wiki/HTC_Dreamhttp://en.wikipedia.org/wiki/Open_standardhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-AndroidAnnouncement-14http://en.wikipedia.org/wiki/Open_Handset_Alliancehttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-AndroidInc-13http://en.wikipedia.org/wiki/Tablet_computerhttp://en.wikipedia.org/wiki/Googlehttp://en.wikipedia.org/wiki/Googlehttp://en.wikipedia.org/wiki/Touchscreenhttp://en.wikipedia.org/wiki/Smartphonehttp://en.wikipedia.org/wiki/Mobile_operating_systemhttp://en.wikipedia.org/wiki/Linux_kernelhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-AndroidOverview-12http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-48http://en.wikipedia.org/wiki/Proximity_sensorhttp://en.wikipedia.org/wiki/Gyroscopehttp://en.wikipedia.org/wiki/Accelerometerhttp://en.wikipedia.org/wiki/Haptic_feedbackhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-touch-47http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-touch-47http://en.wikipedia.org/wiki/Direct_manipulation_interfacehttp://en.wikipedia.org/wiki/File:Android_notification_area.pnghttp://en.wikipedia.org/wiki/Software_widgethttp://en.wikipedia.org/wiki/Proximity_sensorhttp://en.wikipedia.org/wiki/Gyroscopehttp://en.wikipedia.org/wiki/Accelerometerhttp://en.wikipedia.org/wiki/Direct_manipulationhttp://en.wikipedia.org/wiki/User_interfacehttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-gizmodo-g1-15http://en.wikipedia.org/wiki/HTC_Dreamhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-AndroidAnnouncement-14http://en.wikipedia.org/wiki/Open_standardhttp://en.wikipedia.org/wiki/Open_standardhttp://en.wikipedia.org/wiki/Computer_hardwarehttp://en.wikipedia.org/wiki/Open_Handset_Alliancehttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-AndroidInc-13http://en.wikipedia.org/wiki/Googlehttp://en.wikipedia.org/wiki/Tablet_computerhttp://en.wikipedia.org/wiki/Tablet_computerhttp://en.wikipedia.org/wiki/Smartphonehttp://en.wikipedia.org/wiki/Touchscreenhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-AndroidOverview-12http://en.wikipedia.org/wiki/Linux_kernelhttp://en.wikipedia.org/wiki/Mobile_operating_system


2/8

depending on howthedevice is oriented, or allowing the user to steer a

vehicle in a racing game by rotating the device, simulating control of a steering

wheel.[49]

Android devices boot to the homescreen, the primary navigation andinformation point on the device, which is similar to the desktopfound on PCs.

Android homescreens are typically made up of app icons and widgets; app

icons launch the associated app, whereas widgets display live, auto-updating

content such as the weather forecast, the user's email inbox, or a news ticker

directly on the homescreen.[50]A homescreen may be made up of several

pages that the user can swipe back and forth between, though Android's

homescreen interface is heavily customisable, allowing the user to adjust the

look and feel of the device to their tastes.[51]Third-party apps available onGoogle Playand other app stores can extensively re-themethe homescreen,

and even mimic the look of other operating systems, such as Windows Phone.

[52]Most manufacturers, and some wireless carriers, customise the look and

feel of their Android devices to differentiate themselves from their competitors.

[53]

Present along the top of the screen is a status bar, showing information about

the device and its connectivity. This status bar can be "pulled" down to reveal

a notification screen where apps display important information or updates,

such as a newly received email or SMS text, in a way that does not

immediately interrupt or inconvenience the user.[54]Notifications are

persistent until read (by tapping, which opens the relevant app) or dismissed

by sliding it off the screen. Beginning on Android 4.1, "expanded notifications"

can display expanded details or additional functionality; for instance, a music

player can display playback controls, and a "missed call" notification provides

buttons for calling back or sending the caller an SMS message.[55]

Applications

See also: Android software developmentand Google PlayAndroid has a growing selection of third party applications, which can be

acquired by users either through an app store such as Google Playor the

Amazon Appstore, or by downloading and installing the application's APKfile

from a third-party site.[56]The Play Store application allows users to browse,

download and update apps published by Google and third-party developers,

and is pre-installed on devices that comply with Google's compatibilityrequirements.[57]The app filters the list of available applications to those that
http://en.wikipedia.org/wiki/Steering_wheelhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-49http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-57http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-wired_alt_app_stores-56http://en.wikipedia.org/wiki/APK_(file_format)http://en.wikipedia.org/wiki/Amazon_Appstorehttp://en.wikipedia.org/wiki/Google_Playhttp://en.wikipedia.org/wiki/Google_Playhttp://en.wikipedia.org/wiki/Android_software_developmenthttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-notifications-55http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-ui-overview-54http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-53http://en.wikipedia.org/wiki/Mobile_phone_operatorhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-52http://en.wikipedia.org/wiki/Windows_Phonehttp://en.wikipedia.org/wiki/Theme_(computing)http://en.wikipedia.org/wiki/Google_Playhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-51http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-50http://en.wikipedia.org/wiki/News_tickerhttp://en.wikipedia.org/wiki/Software_widgethttp://en.wikipedia.org/wiki/Desktop_metaphorhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-49http://en.wikipedia.org/wiki/Steering_wheelhttp://en.wikipedia.org/wiki/Steering_wheel


3/8

are compatible with the user's device, and developers may restrict their

applications to particular carriers or countries for business reasons.[58]

Purchases of unwanted applications can be refunded within 15 minutes of the

time of download,[59]and some carriers offer direct carrier billing for Google

Play application purchases, where the cost of the application is added to the

user's monthly bill.[60]

As of July 2013, there are more than one million applications available for

Android in the Play Store.[61]As of May 2013, 48 billion apps have been

installed from the Google Play store.[62]

Applications ("apps"), that extend the functionality of devices, are developed

primarily in the Javaprogramming language[63]language using the Android

software developmentkit (SDK). The SDK includes a comprehensive set of

development tools,[64]including a debugger, software libraries, a

handsetemulatorbased on QEMU, documentation, sample code, and

tutorials. The officially supported integrated development environment(IDE) is

Eclipseusing the Android Development Tools (ADT) plugin. Other

development tools are available, including a Native Development Kitfor

applications or extensions in C or C++, Google App Inventor, a visual

environment for novice programmers, and various cross platform mobile web

applications frameworks.

It was announced in January 2014 that ChromeHTML5 web applications

should become available, using a compatibility layer from the open source

Apache Cordovaframework to allow such applications to be wrapped in a

native application shell, enabling their distribution over Google Play.[65]

In order to work around limitations on reaching Google services due to

Internet censorship in the People's Republic of China, Android devices sold in

the PRC are generally customized to use state approved services instead.[66]

Memory management

Since Android devices are usually battery-powered, Android is designed to

manage memory (RAM) to keep power consumption at a minimum, in contrast

to desktop operating systems which generally assume they are connected to

unlimited mains electricity. When an Android app is no longer in use, the

system will automatically suspend it in memory while the app is still

technically "open", suspended apps consume no resources (e.g. battery

power or processing power) and sit idly in the background until needed again.
http://en.wikipedia.org/wiki/Mains_electricityhttp://en.wikipedia.org/wiki/Random-access_memoryhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-66http://en.wikipedia.org/wiki/Internet_censorship_in_the_People%27s_Republic_of_Chinahttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-65http://en.wikipedia.org/wiki/Apache_Cordovahttp://en.wikipedia.org/wiki/Google_Chromehttp://en.wikipedia.org/wiki/Multiple_phone_web_based_application_frameworkhttp://en.wikipedia.org/wiki/Multiple_phone_web_based_application_frameworkhttp://en.wikipedia.org/wiki/Google_App_Inventorhttp://en.wikipedia.org/wiki/Native_development_kithttp://en.wikipedia.org/wiki/Eclipse_(software)http://en.wikipedia.org/wiki/Integrated_development_environmenthttp://en.wikipedia.org/wiki/QEMUhttp://en.wikipedia.org/wiki/Emulatorhttp://en.wikipedia.org/wiki/Software_libraryhttp://en.wikipedia.org/wiki/Debuggerhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-64http://en.wikipedia.org/wiki/Android_software_developmenthttp://en.wikipedia.org/wiki/Android_software_developmenthttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-63http://en.wikipedia.org/wiki/Java_(programming_language)http://en.wikipedia.org/wiki/Mobile_apphttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-48bn-62http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-61http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-60http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-support.google_returning_apps-59http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-android-compatibility-58


4/8

This has the dual benefit of increasing the general responsiveness of Android

devices, since apps don't need to be closed and reopened from scratch each

time, but also ensuring background apps do not consume power needlessly.

[67][68]

Android manages the apps stored in memory automatically: when memory is

low, the system will begin killing apps and processes that have been inactive

for a while, in reverse order since they were last used (i.e. oldest first). This

process is designed to be invisible to the user, such that users do not need to

manage memory or the killing of apps themselves.[69][70]However, confusion

over Android memory management has resulted in third-party task killers

becoming popular on the Google Playstore; these third-party task killers are

generally regarded as doing more harm than good.[71]

Hardware

See also: Android hardware requirements

The main hardware platform for Android is the 32-bit ARMv7architecture. The

Android-x86project provides support for the x86architecture,[7]and Google

TVuses a special x86 version of Android. In 2012, Intelprocessors began to

appear on more mainstream Android platforms, such as phones.[72]In

2013,Freescaleannounced support for Android on its i.MXprocessor,specifically the i.MX5X and i.MX6X series.[73]

As of November 2013, current versions of Android require at least 512MBofRAM,[74]and a 32-bitARMv7, MIPSor x86architecture processor (latter two

through unofficial ports),[7][75]together with an OpenGL ES2.0 compatible

graphics processing unit(GPU).[76]Android supports OpenGL ES 1.1, 2.0 and

3.0. Some applications explicitly require certain version of the OpenGL ES,

thus suitable GPU hardware is required to run such applications.[76]

Android devices incorporate many optional hardware components, including

still or video cameras, GPS, hardware orientation sensors, dedicated gaming

controls, accelerometers, gyroscopes, barometers, magnetometers, proximity

sensors, pressure sensors, thermometers and touchscreens. Some hardware

components are not required, but became standard in certain classes of

devices, such as smartphones, and additional requirements apply if they are

present. Some other hardware was initially required, but those requirements

have been relaxed or eliminated altogether. For example, as Android wasdeveloped initially as a phone OS, hardware such as microphones were
http://en.wikipedia.org/wiki/Touchscreenhttp://en.wikipedia.org/wiki/Pressure_sensorhttp://en.wikipedia.org/wiki/Proximity_sensorhttp://en.wikipedia.org/wiki/Proximity_sensorhttp://en.wikipedia.org/wiki/Magnetometerhttp://en.wikipedia.org/wiki/Gyroscopehttp://en.wikipedia.org/wiki/Accelerometerhttp://en.wikipedia.org/w/index.php?title=Orientation_sensing&action=edit&redlink=1http://en.wikipedia.org/wiki/GPShttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-android-opengl-2.0-76http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-android-opengl-2.0-76http://en.wikipedia.org/wiki/Graphics_processing_unithttp://en.wikipedia.org/wiki/OpenGL_EShttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-75http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-ARMAN-4.0-on-x86-7http://en.wikipedia.org/wiki/X86http://en.wikipedia.org/wiki/MIPS_architecturehttp://en.wikipedia.org/wiki/ARMv7http://en.wikipedia.org/wiki/32-bithttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-74http://en.wikipedia.org/wiki/MiBhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-freescale1-73http://en.wikipedia.org/wiki/I.MXhttp://en.wikipedia.org/wiki/Freescalehttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-72http://en.wikipedia.org/wiki/Intelhttp://en.wikipedia.org/wiki/Google_TVhttp://en.wikipedia.org/wiki/Google_TVhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-ARMAN-4.0-on-x86-7http://en.wikipedia.org/wiki/X86http://en.wikipedia.org/wiki/Android-x86http://en.wikipedia.org/wiki/ARMv7http://en.wikipedia.org/wiki/Android_hardware_requirementshttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-lifehackertask-71http://en.wikipedia.org/wiki/Google_Playhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-70http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-phandroidtask-69http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-68http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-phonedogtask-67


5/8

required, while over time the phone function became optional.[58]Android

used to require an autofocuscamera, which was relaxed to a fixed-focus

camera[58]if it is even present at all, since the camera was dropped as a

requirement entirely when Android started to be used on set-top boxes.

Development

Android green figure, next to its original packaging.

Android is developed in private by Google until the latest changes and

updates are ready to be released, at which point the source code is made

available publicly.[77]This source code will only run without modification on

select devices, usually the Nexusseries of devices. The source code is, in

turn, adapted by OEMs to run on their hardware.[78]Android's source code

does not contain the often proprietary device driversthat are needed for

certain hardware components.[79]

The green Android logo was designed for Google in 2007 by graphic designer

Irina Blok. The design team was tasked with a project to create a universally

identifiable icon with the specific inclusion of a robot in the final design. After

numerous design developments based on science-fictionand space movies,

the team eventually sought inspiration from the human symbol on restroom

doors and modified the figure into a robot shape. As Android is open-sourced,

it was agreed that the logo should be likewise, and since its launch the green

logo has been reinterpreted into countless variations on the original design.[80]

Update schedule

See also: Android version history

Google provides major updates, incremental in nature, to Android every six to

nine months, which most devices are capable of receiving over the air.[81]The

latest major update is Android 4.4 KitKat.[5]

Compared to its chief rival mobile operating system, namely iOS, Android

updates are typically slow to reach actual devices. For devices not under

theNexusbrand, updates often arrive months from the time the given version

is officially released.[82]This is caused partly due to the extensive variation

inhardwareof Android devices, to which each update must be specifically

tailored, as the official Google source code only runs on their flagship

Nexusdevices. PortingAndroid to specific hardware is a time- and resource-
http://en.wikipedia.org/wiki/Portinghttp://en.wikipedia.org/wiki/Google_Nexushttp://en.wikipedia.org/wiki/Computer_hardwarehttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-alliance-82http://en.wikipedia.org/wiki/Google_Nexushttp://en.wikipedia.org/wiki/IOShttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-Google-5http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-81http://en.wikipedia.org/wiki/Over-the-air_programminghttp://en.wikipedia.org/wiki/Android_version_historyhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-androidlogo4-80http://en.wikipedia.org/wiki/Science-fictionhttp://en.wikipedia.org/wiki/Irina_Blokhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-android1-79http://en.wikipedia.org/wiki/Device_driverhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-78http://en.wikipedia.org/wiki/Google_Nexushttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-77http://en.wikipedia.org/wiki/File:Android_green_figure,_next_to_its_original_packaging.jpghttp://en.wikipedia.org/wiki/Set-top_boxhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-android-compatibility-58http://en.wikipedia.org/wiki/Fixed-focus_lenshttp://en.wikipedia.org/wiki/Autofocushttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-android-compatibility-58


6/8

consuming process for device manufacturers, who prioritize their newest

devices and often leave older ones behind.[82]Hence, older smartphones are

frequently not updated if the manufacturer decides it is not worth their time,

regardless of whether the phone is capable of running the update. This

problem is compounded when manufacturers customize Android with their

own interface and apps, which must be reapplied to each new release.

Additional delays can be introduced by wireless carriers who, after receiving

updates from manufacturers, further customize and brand Android to their

needs and conduct extensive testing on their networks before sending the

update out to users.[82]

The lack of after-sale support from manufacturers and carriers has been

widely criticized by consumer groups and the technology media.[83][84]Somecommentators have noted that the industry has a financial incentive not to

update their devices, as the lack of updates for existing devices fuels the

purchase of newer ones,[85]an attitude described as "insulting".[84]The

Guardianhas complained that the complicated method of distribution for

updates is only complicated because manufacturers and carriers have

designed it that way.[84]In 2011, Google partnered with a number of industry

players to announce an "Android Update Alliance", pledging to deliver timely

updates for every device for 18 months after its release;[86]however, thisalliance has never been mentioned since.[82]

In 2012, Google began decoupling certain aspects of the operating system

(particularly core applications) so they could be updated through Google Play

Store, independently of Android itself. One of these components, Google Play

Services, is a system-level process providing APIsfor Google services,

installed automatically on nearly all devices running Android version 2.2 and

higher. With these changes, Google can add new operating system

functionality through Play Services and application updates without having to

distribute an update to the operating system itself. As a result, Android 4.2 and

4.3 contained relatively fewer user-facing changes, focusing more on minor

changes and platform improvements.[3][87]

Linux kernel

As of January 2014, current Android versions consist of a kernelbased on the

Linux kernel's longterm 3.4 branch, varying in version numbers depending on

the actual Android device.[88][89][90]Android versions older than 4.0 Ice Cream
http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-90http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-89http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-88http://en.wikipedia.org/wiki/Linux_kernelhttp://en.wikipedia.org/wiki/Kernel_(computing)http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-ars-googleplayservices-87http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-ars-irongrip-3http://en.wikipedia.org/wiki/APIhttp://en.wikipedia.org/wiki/Google_Play_Serviceshttp://en.wikipedia.org/wiki/Google_Play_Serviceshttp://en.wikipedia.org/wiki/Google_Play_Storehttp://en.wikipedia.org/wiki/Google_Play_Storehttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-alliance-82http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-86http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-gu-updates-84http://en.wikipedia.org/wiki/The_Guardianhttp://en.wikipedia.org/wiki/The_Guardianhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-gu-updates-84http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-85http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-gu-updates-84http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-83http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-alliance-82http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-alliance-82


7/8

Sandwichwere based on the Linux kernel versions 2.6.x.[91][92]

Android's Linux kernel has further architecture changes by Google outside the

typical Linux kernel development cycle.[93]Certain features that Google

contributed back to the Linux kernel, notably a power management featurecalled "wakelocks", were rejected by mainline kernel developers partly

because they felt that Google did not show any intent to maintain its own

code.[94][95][96]Google announced in April 2010 that they would hire two

employees to work with the Linux kernel community,[97]but Greg Kroah-

Hartman, the current Linux kernel maintainer for the stable branch, said in

December 2010 that he was concerned that Google was no longer trying to

get their code changes included in mainstream Linux.[95]Some Google

Android developers hinted that "the Android team was getting fed up with theprocess," because they were a small team and had more urgent work to do on

Android.[98]

In August 2011, Linus Torvaldssaid that "eventually Android and Linux would

come back to a common kernel, but it will probably not be for four to five

years".[99]In December 2011, Greg Kroah-Hartmanannounced the start of

the Android Mainlining Project, which aims to put some Android drivers,

patches and features back into the Linux kernel, starting in Linux 3.3.[100]

Linux included the autosleep and wakelocks capabilities in the 3.5 kernel, after

many previous attempts at merger. The interfaces are the same but the

upstream Linux implementation allows for two different suspend modes: to

memory (the traditional suspend that Android uses), and to disk (hibernate, as

it is known on the desktop).[101]Google maintains a public code repository

that contains their experimental work to re-base Android off the latest stable

Linux versions.[102][103]

The flash storageon Android devices is split into several partitions, such as/

systemfor the operating system itself, and /datafor user data and

application installations.[104]In contrast to desktop Linux distributions, Android

device owners are not given rootaccess to the operating system and sensitive

partitions such as /system are read-only. However, root access can be

obtained by exploiting security flawsin Android, which is used frequently by

the open-source communityto enhance the capabilities of their devices,[105]

but also by malicious parties to install virusesand malware.[106]

Android is a Linux distribution according to the Linux Foundation[107]andGoogle's open-source chief, Chris DiBona.[108]Others, such as Google
http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-108http://en.wikipedia.org/wiki/Chris_DiBonahttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-107http://en.wikipedia.org/wiki/Linux_Foundationhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-106http://en.wikipedia.org/wiki/Malwarehttp://en.wikipedia.org/wiki/Computer_virushttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-105http://en.wikipedia.org/wiki/Android_(operating_system)#Open_source_communityhttp://en.wikipedia.org/wiki/Vulnerability_(computing)http://en.wikipedia.org/wiki/Read-only_memoryhttp://en.wikipedia.org/wiki/Superuserhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-104http://en.wikipedia.org/wiki/Flash_storagehttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-103http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-102http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-101http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-100http://en.wikipedia.org/wiki/Device_driverhttp://en.wikipedia.org/wiki/Greg_Kroah-Hartmanhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-99http://en.wikipedia.org/wiki/Linus_Torvaldshttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-98http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-hartmann-95http://en.wikipedia.org/wiki/Greg_Kroah-Hartmanhttp://en.wikipedia.org/wiki/Greg_Kroah-Hartmanhttp://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-97http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-96http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-hartmann-95http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-hartmann2-94http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-93http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-92http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-91


8/8

engineer Patrick Brady, disagree that it is a Linux distribution, noting the lack

of support for many GNU tools in Android, including glibc.[109]
http://en.wikipedia.org/wiki/Android_(operating_system)#cite_note-109http://en.wikipedia.org/wiki/Glibc

Android Avin Notes

Documents

Transcript of Android Avin Notes