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dev-manual, kernel-dev: Moved the kernel build hierarchy section

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Fixes [YOCTO #11630]

The section that presented the Yocto Linux kernel file structure
resulting from a build using BitBake needed to be in the kernel-dev
manual.  I moved it over.  This required transferring over a
figure as well.

(From yocto-docs rev: 0abc6c7d87a6aa10dac28fefbb280eb51fea61a7)

Signed-off-by: Scott Rifenbark <srifenbark@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
This commit is contained in:
Scott Rifenbark
2017-06-29 15:54:35 -07:00
committed by Richard Purdie
parent 0e92314239
commit b643938bde
4 changed files with 91 additions and 70 deletions
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87
documentation/kernel-dev/kernel-dev-concepts-appx.xml
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@@ -380,6 +380,93 @@
cloning and building the kernel.
</para>
</section>
<section id='kernel-build-file-hierarchy'>
<title>Kernel Build File Hierarchy</title>
<para>
Upstream storage of all the available kernel source code is
one thing, while representing and using the code on your host
development system is another.
Conceptually, you can think of the kernel source repositories
as all the source files necessary for all the supported
Yocto Linux kernels.
As a developer, you are just interested in the source files
for the kernel on which you are working.
And, furthermore, you need them available on your host system.
</para>
<para>
Kernel source code is available on your host system several
different ways:
<itemizedlist>
<listitem><para>
<emphasis>Files Accessed While using <filename>devtool</filename>:</emphasis>
<filename>devtool</filename>, which is available with the
Yocto Project, is the preferred method by which to
modify the kernel.
See the
"<ulink url='&YOCTO_DOCS_DEV_URL;#kernel-modification-workflow'>Kernel Modification Workflow</ulink>"
section in the Yocto Project Development Manual for
information.
</para></listitem>
<listitem><para>
<emphasis>Cloned Repository:</emphasis>
If you are working in the kernel all the time, you probably
would want to set up your own local Git repository of the
Yocto Linux kernel tree.
For information on how to clone a Yocto Linux kernel
Git repository, see the
"<ulink url='&YOCTO_DOCS_DEV_URL;#local-kernel-files'>Setting Up to Work On a Kernel</ulink>"
section in the Yocto Project Development Manual.
</para></listitem>
<listitem><para>
<emphasis>Temporary Source Files from a Build:</emphasis>
If you just need to make some patches to the kernel using
a traditional BitBake workflow (i.e. not using the
<filename>devtool</filename>), you can access temporary
kernel source files that were extracted and used during
a kernel build.
</para></listitem>
</itemizedlist>
</para>
<para>
The temporary kernel source files resulting from a build using
BitBake have a particular hierarchy.
When you build the kernel on your development system, all files
needed for the build are taken from the source repositories
pointed to by the
<ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>
variable and gathered in a temporary work area where they are
subsequently used to create the unique kernel.
Thus, in a sense, the process constructs a local source tree
specific to your kernel from which to generate the new kernel
image.
</para>
<para>
The following figure shows the temporary file structure
created on your host system when you build the kernel using
Bitbake.
This
<ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>
contains all the source files used during the build.
<imagedata fileref="figures/kernel-overview-2-generic.png"
width="6in" depth="5in" align="center" scale="100" />
</para>
<para>
Again, for additional information on the Yocto Project kernel's
architecture and its branching strategy, see the
"<link linkend='yocto-linux-kernel-architecture-and-branching-strategies'>Yocto Linux Kernel Architecture and Branching Strategies</link>"
section.
You can also reference the
"<ulink url='&YOCTO_DOCS_DEV_URL;#patching-the-kernel'>Patching the Kernel</ulink>"
section in the Yocto Project Development Manual for a detailed
example that modifies the kernel.
</para>
</section>
</appendix>
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