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| author | Android Partner Docs <noreply@android.com> | 2017-08-22 10:41:24 -0700 |
|---|---|---|
| committer | Clay Murphy <claym@google.com> | 2017-08-22 15:01:44 -0700 |
| commit | f16c42333aa6b2de30a344dd68246d4a33d93e7d (patch) | |
| tree | 311af599312cacb21c888aeae828cae59b0d64a1 /en/devices/architecture/kernel/index.html | |
| parent | 04426e67ca3ee557a0083f9b3c6ba789021bd7a0 (diff) | |
| download | source.android.com-f16c42333aa6b2de30a344dd68246d4a33d93e7d.tar.gz | |
Docs: Changes to source.android.com
- 166080694 Devsite localized content from translation request a3d5a7... by Android Partner Docs <noreply@android.com>
- 166079245 Remove duplicate TOC entry to oob-users.html. by mheco <mheco@google.com>
- 166002955 Update builds for Oreo by Android Partner Docs <noreply@android.com>
- 165977566 Fixing bad conversion by hvm <hvm@google.com>
- 165977199 Edit links to point to public source files in AOSP. by cqn <cqn@google.com>
- 165962883 Add codename to CTS downloads page. by gdimino <gdimino@google.com>
- 165955117 Integration of O branch into mainline. by gdimino <gdimino@google.com>
- 165638251 Update July public Android security bulletin to remove QC... by Android Partner Docs <noreply@android.com>
- 165638198 Update June public Android security bulletin to remove QC... by Android Partner Docs <noreply@android.com>
- 165638174 Update May public Android security bulletin to remove QC ... by Android Partner Docs <noreply@android.com>
- 165638096 Update April public Android security bulletin to remove Q... by Android Partner Docs <noreply@android.com>
- 165528993 Update to Keymaster 2 and remove requirements language by daroberts <daroberts@google.com>
- 165511119 Add Bluetooth verification / debug information by cqn <cqn@google.com>
- 165491345 Fixed link broken by file rename. by cqn <cqn@google.com>
- 165381648 Fixed broken image paths and renamed HCI Requirements file. by cqn <cqn@google.com>
- 165365185 Created high-level Bluetooth directory and added HTML ver... by cqn <cqn@google.com>
- 165335694 Devsite localized content from translation request 66a39c... by Android Partner Docs <noreply@android.com>
- 165246927 Update August 2017 bulletin with CVE-2017-0687 by daroberts <daroberts@google.com>
PiperOrigin-RevId: 166080694
Change-Id: I2d3a8d77fa6a66c2099f13ba2e864545328fd17a
Diffstat (limited to 'en/devices/architecture/kernel/index.html')
| -rw-r--r-- | en/devices/architecture/kernel/index.html | 80 |
1 files changed, 80 insertions, 0 deletions
diff --git a/en/devices/architecture/kernel/index.html b/en/devices/architecture/kernel/index.html new file mode 100644 index 00000000..456662f7 --- /dev/null +++ b/en/devices/architecture/kernel/index.html @@ -0,0 +1,80 @@ +<html devsite> + <head> + <title>Kernel</title> + <meta name="project_path" value="/_project.yaml" /> + <meta name="book_path" value="/_book.yaml" /> + </head> + <body> + <!-- + Copyright 2017 The Android Open Source Project + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + --> + +<p>The Linux kernel is an extremely important part of the software on nearly +every Android device. This section describes Linux kernel development and +release models (below), +<a href="/devices/architecture/kernel/releases.html">stable and long-term +supported (LTS) kernels</a> (including why all Android devices should use stable +releases instead of cherry picking patches), kernel +<a href="/devices/architecture/kernel/config.html">configuration</a> and +<a href="/devices/architecture/kernel/hardening.html">hardening</a>, +requirements for +<a href="/devices/architecture/kernel/reqs-interfaces.html">interfaces</a> and +the +<a href="/devices/architecture/kernel/modular-kernels.html">modular kernels</a> +(introduced in Android O), kernel +<a href="/devices/architecture/kernel/lldb-debug.html">debugging</a> and +<a href="/devices/architecture/kernel/network_tests.html">network testing</a>, +and <a href="/devices/architecture/kernel/squashfs.html">SquashFS</a>.</p> + +<h2 id="linux-kernel-development">Linux kernel development</h2> +<p> +The Linux kernel is the largest collaborative software project ever. In 2016, +over 4,000 different developers from over 450 different companies contributed to +the project and there were 6 releases, each containing between 12,000 and 16,000 +different changes. At the end of 2016 the size of the Linux kernel was just over +56 thousand files, consisting of 22 million lines of code, build scripts, and +documentation (kernel release 4.9). (For full Linux development statistics, +refer to +<a href="https://kernelnewbies.org/DevelopmentStatistics" class="external">https://kernelnewbies.org/DevelopmentStatistics</a>.) +</p> +<p> +While the Linux kernel contains code for all the different chip architectures +and hardware drivers it supports, an individual system runs only a fraction of +the codebase. An average laptop uses around 2 million lines of kernel code from +5 thousand files to function properly, while the Pixel phone uses 3.2 million +lines of kernel code from 6 thousand files (due to the increased complexity of +an SoC). +</p> + +<h2 id="linux-kernel-releases">Linux kernel releases</h2> +<p>The Linux kernel uses a release model that differs substantially from +standard AOSP releases. With the release of the 2.6 kernel in December of 2003, +the kernel developer community switched from the previous model of having a +separate development and stable kernel branch, and moved to a <em>stable +only</em> branch model. In this model, a new release occurred every 2 to 3 +months, and that release was declared <em>stable</em> and recommended for all +users to run. This change in development model was due to the very long +release cycle prior to the 2.6 kernel (almost 3 years), and the struggle to +maintain two different branches of the codebase at the same time.</p> + +<p>The numbering of the kernel releases began at 2.6.x, where x was an +incrementing number that changed on every release (the value of the number has +no meaning, other than it is newer than the previous kernel release). The kernel +version since then has now moved to 4.x accounting for 2 major version changes. +These version numbers are chosen by the maintainer(s) only to avoid confusion +among users caused by higher minor release numbers.</p> + + </body> +</html> |