Android (operating system): Difference between revisions

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Android's variant of the Linux kernel has further architectural changes that are implemented by Google outside the typical Linux kernel development cycle, such as the inclusion of components like device trees, ashmem, ION, and different [[out of memory]] (OOM) handling.<ref>{{cite web |title=What Are The Major Changes That Android Made To The Linux Kernel? |url=https://www.forbes.com/sites/quora/2013/05/13/what-are-the-major-changes-that-android-made-to-the-linux-kernel/ |website=[[Forbes]] |date=May 13, 2013 |access-date=June 20, 2017 |url-status=live |archive-url=https://web.archive.org/web/20170104090354/http://www.forbes.com/sites/quora/2013/05/13/what-are-the-major-changes-that-android-made-to-the-linux-kernel/ |archive-date=January 4, 2017 }}</ref><ref>{{cite web |title=LMG Upstreaming |url=https://wiki.linaro.org/LMG/Kernel/Upstreaming |website=Linaro |date=December 5, 2016 |url-status=dead |archive-url=https://web.archive.org/web/20180109063643/https://wiki.linaro.org/LMG/Kernel/Upstreaming |archive-date=January 9, 2018 |access-date=June 26, 2017 }}</ref> Certain features that Google contributed back to the Linux kernel, notably a power management feature called "wakelocks",<ref>{{cite web |first=Brian |last=Proffitt |title=Garrett's LinuxCon Talk Emphasizes Lessons Learned from Android/Kernel Saga |url=https://www.linux.com/news/garretts-linuxcon-talk-emphasizes-lessons-learned-androidkernel-saga |website=[[LinuxCon]] |publisher=[[Linux Foundation]] |date=August 10, 2010 |access-date=June 20, 2017 |url-status=live |archive-url=https://web.archive.org/web/20170629190535/https://www.linux.com/news/garretts-linuxcon-talk-emphasizes-lessons-learned-androidkernel-saga |archive-date=June 29, 2017 }}</ref> were initially rejected by [[Mainline Linux|mainline kernel]] developers partly because they felt that Google did not show any intent to maintain its own code.<ref>{{cite web |first=David |last=Meyer |title=Linux developer explains Android kernel code removal |url=https://www.zdnet.com/article/linux-developer-explains-android-kernel-code-removal/ |website=[[ZDNet]] |publisher=[[CBS Interactive]] |date=February 3, 2010 |access-date=March 11, 2017 |url-status=live |archive-url=https://web.archive.org/web/20161015045139/http://www.zdnet.com/article/linux-developer-explains-android-kernel-code-removal/ |archive-date=October 15, 2016 }}</ref><ref name="hartman">{{cite web |first=Greg |last=Kroah-Hartman |author-link=Greg Kroah-Hartman |title=Android and the Linux kernel community |url=http://www.kroah.com/log/linux/android-kernel-problems.html |website=Linux kernel monkey log |date=December 9, 2010 |access-date=June 20, 2017}}</ref> Google announced in April 2010 that they would hire two employees to work with the Linux kernel community,<ref>{{cite web |first=Paula |last=Rooney |title=DiBona: Google will hire two Android coders to work with kernel.org |url=https://www.zdnet.com/article/dibona-google-will-hire-two-android-coders-to-work-with-kernel-org/ |archive-url=https://web.archive.org/web/20100617005554/http://www.zdnet.com/blog/open-source/dibona-google-will-hire-two-android-coders-to-work-with-kernelorg/6274 |website=[[ZDNet]] |publisher=[[CBS Interactive]] |date=April 15, 2010 |archive-date=June 17, 2010 |url-status=live |access-date=March 11, 2017}}</ref> 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.<ref name="hartman" /> Google engineer Patrick Brady once stated in the company's developer conference that "Android is not Linux",<ref name="ars introduction developer">{{cite web |first=Ryan |last=Paul |title=Dream(sheep++): A developer's introduction to Google Android |url=https://arstechnica.com/gadgets/2009/02/an-introduction-to-google-android-for-developers/ |website=[[Ars Technica]] |publisher=[[Condé Nast]] |date=February 24, 2009 |access-date=June 20, 2017 |url-status=live |archive-url=https://web.archive.org/web/20170704115615/https://arstechnica.com/gadgets/2009/02/an-introduction-to-google-android-for-developers/ |archive-date=July 4, 2017 }}</ref> with ''[[Computerworld]]'' adding that "Let me make it simple for you, without Linux, there is no Android".<ref>{{cite web |first=Steven J. |last=Vaughan-Nichols |title=Android/Linux kernel fight continues |url=http://www.computerworld.com/article/2469087/mobile-apps/android-linux-kernel-fight-continues.html |website=[[Computerworld]] |publisher=[[International Data Group]] |date=September 7, 2010 |access-date=June 20, 2017 |url-status=live |archive-url=https://web.archive.org/web/20170214190045/http://www.computerworld.com/article/2469087/mobile-apps/android-linux-kernel-fight-continues.html |archive-date=February 14, 2017 }}</ref> ''[[Ars Technica]]'' wrote that "Although Android is built on top of the Linux kernel, the platform has very little in common with the conventional desktop Linux stack".<ref name="ars introduction developer" />

In August 2011, [[Linus Torvalds]] said that "eventually Android and Linux would come back to a common kernel, but it will probably not be for four to five years".<ref>{{cite web |first=Steven J. |last=Vaughan-Nichols |title=Linus Torvalds on Android, the Linux fork |url=https://www.zdnet.com/article/linus-torvalds-on-android-the-linux-fork/ |website=[[ZDNet]] |publisher=[[CBS Interactive]] |date=August 18, 2011 |access-date=March 11, 2017 |url-status=live |archive-url=https://web.archive.org/web/20170218053104/http://www.zdnet.com/article/linus-torvalds-on-android-the-linux-fork/ |archive-date=February 18, 2017 }}</ref> (that has not happened yet, while some code has been [[upstream (software development)|upstreamed]], not all of it has, so modified kernels keep being used). In December 2011, Greg Kroah-Hartman announced the start of Android Mainlining Project, which aims to put some Android [[Device driver|drivers]], patches and features back into the Linux kernel, starting in Linux 3.3.<ref>{{cite web |url=http://www.h-online.com/open/news/item/Android-drivers-to-be-included-in-Linux-3-3-kernel-1400996.html|archive-url=https://web.archive.org/web/20131208130029/http://www.h-online.com/open/news/item/Android-drivers-to-be-included-in-Linux-3-3-kernel-1400996.html|archive-date=December 8, 2013 |title=Android drivers to be included in Linux 3.3 kernel |author=Chris von Eitzen |work=h-online.com |date=December 23, 2011 |access-date=February 15, 2012}}</ref> Linux included the autosleep and wakelocks capabilities in the 3.5 kernel, after many previous attempts at a 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).<ref>{{cite web|last=Jonathan|first=Corbet|title=Autosleep and wakelocks|url=https://lwn.net/Articles/479841/|publisher=LWN|url-status=live|archive-url=https://web.archive.org/web/20120826165126/http://lwn.net/Articles/479841/|archive-date=August 26, 2012}}</ref> Google maintains a public code repository that contains their experimental work to [[rebasing|re-base]] Android off the latest stable Linux versions.<ref>{{cite web |url=https://www.phoronix.com/scan.php?page=news_item&px=MTMxMzc |title=Google Working On Android Based On Linux 3.8 |date=February 28, 2013 |access-date=February 28, 2013 |url-status=live |archive-url=https://web.archive.org/web/20130302004730/http://www.phoronix.com/scan.php?page=news_item&px=MTMxMzc |archive-date=March 2, 2013 }}</ref><ref>{{cite web |url=http://www.pocketdroid.net/google-working-on-experimental-linux-kernel-3-10-for-android/ |title=Google working on experimental Linux Kernel 3.10 for Android |publisher=Pocketdroid.net |access-date=September 3, 2013 |url-status=dead |archive-url=https://web.archive.org/web/20130827220633/http://www.pocketdroid.net/google-working-on-experimental-linux-kernel-3-10-for-android/ |archive-date=August 27, 2013 }}</ref>

Android is a [[Linux distribution]] according to the [[Linux Foundation]],<ref>{{cite web|url=http://www.linuxfoundation.org/news-media/blogs/browse/2012/12/what-year-linux-please-join-us-celebration |title=What a Year for Linux: Please Join us in Celebration |first=Amanda |last=McPherson |publisher=Linux Foundation |date=December 13, 2012 |access-date=April 16, 2014 |url-status=dead |archive-url=https://web.archive.org/web/20140417232521/http://www.linuxfoundation.org/news-media/blogs/browse/2012/12/what-year-linux-please-join-us-celebration |archive-date=April 17, 2014 }}</ref> Google's open-source chief [[Chris DiBona]],<ref>{{cite web |url=http://derstandard.at/1308186313932/Interview-Google-Android-is-the-Linux-desktop-dream-come-true |title=Google: "Android is the Linux desktop dream come true" |first=Andreas |last=Proschofsky |work=derStandard.at |date=July 10, 2011 |access-date=March 14, 2013 |url-status=live |archive-url=https://web.archive.org/web/20130422021245/http://derstandard.at/1308186313932/Interview-Google-Android-is-the-Linux-desktop-dream-come-true |archive-date=April 22, 2013 }}</ref> and several journalists.<ref>{{cite web |first=Jerry |last=Hildenbrand |title=Ask AC: Is Android Linux? |url=http://www.androidcentral.com/ask-ac-android-linux |website=Android Central |publisher=Mobile Nations |date=November 8, 2012 |access-date=March 11, 2017 |url-status=live |archive-url=https://web.archive.org/web/20170408213437/http://www.androidcentral.com/ask-ac-android-linux |archive-date=April 8, 2017 }}</ref><ref>{{cite web |url=http://www.itworld.com/open-source/369810/android-really-linux-distribution |title=Is Android really a Linux distribution? |first=Jim |last=Lynch |work=ITworld |date=August 20, 2013 |access-date=April 17, 2014 |url-status=dead |archive-url=https://web.archive.org/web/20140205165359/http://www.itworld.com/open-source/369810/android-really-linux-distribution |archive-date=February 5, 2014 }}</ref> Others, such as Google engineer Patrick Brady, say that Android is not Linux in the traditional [[Unix-like]] Linux distribution sense; Android does not include the [[GNU C Library]] (it uses [[Bionic (software)|Bionic]] as an alternative C library) and some other components typically found in Linux distributions.<ref name="APIs">{{cite web |first=Ryan |last=Paul |title=Dream(sheep++): A developer's introduction to Google Android |url=https://arstechnica.com/gadgets/2009/02/an-introduction-to-google-android-for-developers/ |website=[[Ars Technica]] |publisher=[[Condé Nast]] |date=February 24, 2009 |access-date=March 11, 2017 |url-status=live |archive-url=https://web.archive.org/web/20170312064709/https://arstechnica.com/gadgets/2009/02/an-introduction-to-google-android-for-developers/ |archive-date=March 12, 2017 }}</ref>