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kernel-dev: Edits to "Working with Out-of-Tree Modules" 

Fixes [YOCTO #3729]

I made an editing pass through this section.  Found some minor
corrections.

(From yocto-docs rev: 314ec3a066de7328b6c6893ce33cc0e5faa8700a)

Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
This commit is contained in:
Scott Rifenbark 2014-06-17 10:09:06 +03:00 committed by Richard Purdie
parent 5112dbd23d
commit 45a1c42e7e
1 changed files with 33 additions and 31 deletions
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64
documentation/kernel-dev/kernel-dev-common.xml
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@ -261,7 +261,7 @@
<!--
<para>
<emphasis>AR - Darrren Hart:</emphasis> This section
<emphasis>AR - Darren Hart:</emphasis> This section
originated from the old Yocto Project Kernel Architecture
and Use Manual.
It was decided we need to put it in this section here.
@ -635,9 +635,9 @@
<title>Working with Out-of-Tree Modules</title>
<para>
This section describes steps you need to take to be able
to build out-of-tree modules on your target and how to
incorporate out-of-tree modules in the build.
This section describes steps to build out-of-tree modules on
your target and describes how to incorporate out-of-tree modules
in the build.
</para>
<section id='building-out-of-tree-modules-on-the-target'>
@ -646,7 +646,7 @@
<para>
If you want to be able to build out-of-tree modules on
the target, there are some steps you need to take
on the target that has your SDK image running.
on the target that is running your SDK image.
Briefly, the <filename>kernel-dev</filename> package
is installed by default on all
<filename>*.sdk</filename> images.
@ -657,15 +657,15 @@
<para>
Prior to attempting to build the out-of-tree modules,
you need to be on the target as root and change to the
<filename>/usr/src/kernel</filename> directory and
then <filename>make</filename> the scripts:
you need to be on the target as root and you need to
change to the <filename>/usr/src/kernel</filename> directory.
Next, <filename>make</filename> the scripts:
<literallayout class='monospaced'>
# cd /usr/src/kernel
# make scripts
</literallayout>
Because all SDK image recipes include
<filename>dev-pkgs</filename> the
<filename>dev-pkgs</filename>, the
<filename>kernel-dev</filename> packages will be installed
as part of the SDK image.
The SDK uses the scripts when building out-of-tree
@ -682,9 +682,9 @@
<para>
While it is always preferable to work with sources integrated
into the Linux kernel sources, if you need an external kernel
module, the <filename>hello-mod.bb</filename> recipe is available
as a template from which you can create your own out-of-tree
Linux kernel module recipe.
module, the <filename>hello-mod.bb</filename> recipe is
available as a template from which you can create your
own out-of-tree Linux kernel module recipe.
</para>
<para>
@ -700,12 +700,12 @@
<para>
To get started, copy this recipe to your layer and give it a
meaningful name (e.g. <filename>mymodule_1.0.bb</filename>).
In the same directory, create a directory named
In the same directory, create a new directory named
<filename>files</filename> where you can store any source files,
patches, or other files necessary for building
the module that do not come with the sources.
Finally, update the recipe as appropriate for the module.
Typically you will need to set the following variables:
Finally, update the recipe as needed for the module.
Typically, you will need to set the following variables:
<itemizedlist>
<listitem><para><ulink url='&YOCTO_DOCS_REF_URL;#var-DESCRIPTION'><filename>DESCRIPTION</filename></ulink>
</para></listitem>
@ -719,11 +719,11 @@
</para>
<para>
Depending on the build system used by the module sources, you might
need to make some adjustments.
For example, a typical module <filename>Makefile</filename> looks
much like the one provided with the <filename>hello-mod</filename>
template:
Depending on the build system used by the module sources,
you might need to make some adjustments.
For example, a typical module <filename>Makefile</filename>
looks much like the one provided with the
<filename>hello-mod</filename> template:
<literallayout class='monospaced'>
obj-m := hello.o
@ -742,27 +742,29 @@
The important point to note here is the
<ulink url='&YOCTO_DOCS_REF_URL;#var-KERNEL_SRC'><filename>KERNEL_SRC</filename></ulink>
variable.
The class <filename>module.bbclass</filename> sets this variable,
as well as the
The
<ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-module'><filename>module</filename></ulink>
class sets this variable and the
<ulink url='&YOCTO_DOCS_REF_URL;#var-KERNEL_PATH'><filename>KERNEL_PATH</filename></ulink>
variable to
<filename>${<ulink url='&YOCTO_DOCS_REF_URL;#var-STAGING_KERNEL_DIR'><filename>STAGING_KERNEL_DIR</filename></ulink>}</filename>
with the necessary Linux kernel build information to build modules.
with the necessary Linux kernel build information to build
modules.
If your module <filename>Makefile</filename> uses a different
variable, you might want to override the
<ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-compile'><filename>do_compile()</filename></ulink>
step, or create a patch to
the <filename>Makefile</filename> to work with the more typical
<filename>KERNEL_SRC</filename> or <filename>KERNEL_PATH</filename>
variables.
<filename>KERNEL_SRC</filename> or
<filename>KERNEL_PATH</filename> variables.
</para>
<para>
After you have prepared your recipe, you will likely want to
include the module in your images.
To do this, see the documentation for the following variables in
the Yocto Project Reference Manual and set one of them as
appropriate in your machine configuration file:
the Yocto Project Reference Manual and set one of them
appropriately for your machine configuration file:
<itemizedlist>
<listitem><para><ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE_ESSENTIAL_EXTRA_RDEPENDS'><filename>MACHINE_ESSENTIAL_EXTRA_RDEPENDS</filename></ulink>
</para></listitem>
@ -776,13 +778,13 @@
</para>
<para>
modules are often not required for boot and can be excluded from
Modules are often not required for boot and can be excluded from
certain build configurations.
The following allows for the most flexibility:
<literallayout class='monospaced'>
MACHINE_EXTRA_RRECOMMENDS += "kernel-module-mymodule"
</literallayout>
Where the value is derived by appending the module filename without
The value is derived by appending the module filename without
the <filename>.ko</filename> extension to the string
"kernel-module-".
</para>
@ -792,8 +794,8 @@
<ulink url='&YOCTO_DOCS_REF_URL;#var-RRECOMMENDS'><filename>RRECOMMENDS</filename></ulink>
and not a
<ulink url='&YOCTO_DOCS_REF_URL;#var-RDEPENDS'><filename>RDEPENDS</filename></ulink>
variable, the build will not fail if this module is not available
to include in the image.
variable, the build will not fail if this module is not
available to include in the image.
</para>
</section>
</section>