Documentation/process/howto.rst

3 HOWTO do Linux kernel development
7 instructions on how to become a Linux kernel developer and how to learn
8 to work with the Linux kernel development community.  It tries to not
9 contain anything related to the technical aspects of kernel programming,
20 So, you want to learn how to become a Linux kernel developer?  Or you
27 The kernel is written mostly in C, with some architecture-dependent
29 kernel development.  Assembly (any architecture) is not required unless
38 The kernel is written using GNU C and the GNU toolchain.  While it
40 not featured in the standard.  The kernel is a freestanding C
44 difficult to understand the assumptions the kernel has on the toolchain
62 The Linux kernel source code is released under the GPL.  Please see the file
63 COPYING in the main directory of the source tree. The Linux kernel licensing
67 not ask on the Linux kernel mailing list.  The people on the mailing lists are
78 The Linux kernel source tree has a large range of documents that are
79 invaluable for learning how to interact with the kernel community.  When
80 new features are added to the kernel, it is recommended that new
82 When a kernel change causes the interface that the kernel exposes to
86 linux-api@vger.kernel.org.
88 Here is a list of files that are in the kernel source tree that are
92     This file gives a short background on the Linux kernel and describes
93     what is necessary to do to configure and build the kernel.  People
94     who are new to the kernel should start here.
98     packages that are necessary to build and run the kernel
102     This describes the Linux kernel coding style, and some of the
125 	"Linux kernel patch submission format"
130     not have a stable API within the kernel, including things like:
134       - Mitigating rapid change within the kernel source tree (or
142     If you feel you have found a security problem in the Linux kernel,
143     please follow the steps in this document to help notify the kernel
147     This document describes how Linux kernel maintainers operate and the
149     for anyone new to kernel development (or anyone simply curious about
151     about the unique behavior of kernel maintainers.
153   :ref:`Documentation/process/stable-kernel-rules.rst <stable_kernel_rules>`
154     This file describes the rules on how the stable kernel releases
158   :ref:`Documentation/process/kernel-docs.rst <kernel_docs>`
159     A list of external documentation that pertains to kernel
161     are looking for within the in-kernel documentation.
165     apply it to the different development branches of the kernel.
167 The kernel also has a large number of documents that can be
170 full description of the in-kernel API, and rules on how to handle
178 respectively from the main kernel source directory.
186 Becoming A Kernel Developer
189 If you do not know anything about Linux kernel development, you should
195 of basic kernel development question (make sure to search the archives
199 learning about Linux kernel development.
203 some basic logistical information, like how to compile a kernel and
207 some task to start doing to join into the kernel development community,
208 go to the Linux Kernel Janitor's project:
213 problems that need to be cleaned up and fixed within the Linux kernel
215 will learn the basics of getting your patch into the Linux kernel tree,
219 Before making any actual modifications to the Linux kernel code, it is
226 repository of the kernel code may be found at:
234 Linux kernel development process currently consists of a few different
235 main kernel "branches" and lots of different subsystem-specific kernel
247 https://kernel.org or in the repo.  Its development process is as follows:
249   - As soon as a new kernel is released a two week window is open,
253     is using git (the kernel's source management tool, more information
256   - After two weeks a -rc1 kernel is released and the focus is on making the
257     new kernel as rock solid as possible.  Most of the patches at this point
268     release a new -rc kernel every week.
269   - Process continues until the kernel is considered "ready", the
272 It is worth mentioning what Andrew Morton wrote on the linux-kernel
273 mailing list about kernel releases:
275 	*"Nobody knows when a kernel will be released, because it's
289 kernel and are not interested in helping test development/experimental
292 Stable trees are maintained by the "stable" team <stable@vger.kernel.org>, and
298 The file :ref:`Documentation/process/stable-kernel-rules.rst <stable_kernel_rules>`
299 in the kernel tree documents what kinds of changes are acceptable for
305 The maintainers of the various kernel subsystems --- and also many
306 kernel subsystem developers --- expose their current state of
308 happening in the different areas of the kernel.  In areas where
310 onto such a subsystem kernel tree so that conflicts between the
316 of them can be browsed at https://git.kernel.org/.
320 respective section below).  For several kernel subsystems, this review
325 https://patchwork.kernel.org/.
335 	https://git.kernel.org/?p=linux/kernel/git/next/linux-next.git
338 expected to go into the mainline kernel at the next merge period.
345 https://bugzilla.kernel.org is where the Linux kernel developers track kernel
347 tool.  For details on how to use the kernel bugzilla, please see:
349 	https://bugzilla.kernel.org/page.cgi?id=faq.html
352 in the main kernel source directory has a good
353 template for how to report a possible kernel bug, and details what kind
354 of information is needed by the kernel developers to help track down the
362 bugs reported by other people. Not only you will help to make the kernel
368 To work in the already reported bug reports, go to https://bugzilla.kernel.org.
374 As some of the above documents describe, the majority of the core kernel
375 developers participate on the Linux Kernel Mailing list.  Details on how
378 	http://vger.kernel.org/vger-lists.html#linux-kernel
383 	http://dir.gmane.org/gmane.linux.kernel
390 Most of the individual kernel subsystems also have their own separate
395 Many of the lists are hosted on kernel.org. Information on them can be
398 	http://vger.kernel.org/vger-lists.html
419 Kernel developers don't want to deal with
433 The goal of the kernel community is to provide the best possible kernel
444 Remember, this is part of getting your patch into the kernel.  You have
461 the kernel.  Or at least be willing to prove your idea is worth it.
472 Differences between the kernel community and corporate structures
475 The kernel community works differently than most traditional corporate
501 Another way the kernel community is different than most traditional
505 The Linux kernel work environment is accepting of women and minorities
509 Most women who have worked in the Linux kernel and have expressed an
522 The Linux kernel community does not gladly accept large chunks of code
550 Here is an analogy from kernel developer Al Viro:
559 	*The same is true of kernel development. The maintainers and