1204 lines
61 KiB
XML
1204 lines
61 KiB
XML
<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
|
|
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
|
|
[<!ENTITY % poky SYSTEM "../poky.ent"> %poky; ] >
|
|
|
|
<chapter id='bsp'>
|
|
|
|
<title>Board Support Packages (BSP) - Developer's Guide</title>
|
|
|
|
<para>
|
|
A Board Support Package (BSP) is a collection of information that
|
|
defines how to support a particular hardware device, set of devices, or
|
|
hardware platform.
|
|
The BSP includes information about the hardware features
|
|
present on the device and kernel configuration information along with any
|
|
additional hardware drivers required.
|
|
The BSP also lists any additional software
|
|
components required in addition to a generic Linux software stack for both
|
|
essential and optional platform features.
|
|
</para>
|
|
|
|
<para>
|
|
This chapter (or document if you are reading the BSP Developer's Guide) defines
|
|
a structure for these components
|
|
so that BSPs follow a commonly understood layout.
|
|
The information here also shows how you can create and manage a
|
|
<link linkend='bsp-layers'>BSP Layer</link> using two Yocto Project
|
|
<link linkend='using-the-yocto-projects-bsp-tools'>BSP Tools</link>.
|
|
</para>
|
|
|
|
<para>
|
|
Providing a common form allows end-users to understand and become familiar
|
|
with the layout.
|
|
A common form also encourages standardization
|
|
of software support of hardware.
|
|
</para>
|
|
|
|
<para>
|
|
The proposed format does have elements that are specific to the Yocto Project and
|
|
OpenEmbedded build systems.
|
|
It is intended that this information can be
|
|
used by other systems besides Yocto Project and OpenEmbedded and that it will be simple
|
|
to extract information and convert it to other formats if required.
|
|
Yocto Project, through its standard layers mechanism, can directly accept the format
|
|
described as a layer.
|
|
The BSP captures all
|
|
the hardware-specific details in one place in a standard format, which is
|
|
useful for any person wishing to use the hardware platform regardless of
|
|
the build system they are using.
|
|
</para>
|
|
|
|
<para>
|
|
The BSP specification does not include a build system or other tools -
|
|
it is concerned with the hardware-specific components only.
|
|
At the end-distribution point, you can ship the BSP combined with a build system
|
|
and other tools.
|
|
However, it is important to maintain the distinction that these
|
|
are separate components that happen to be combined in certain end products.
|
|
</para>
|
|
|
|
<section id='bsp-layers'>
|
|
<title>BSP Layers</title>
|
|
|
|
<para>
|
|
The BSP consists of a file structure inside a base directory.
|
|
Collectively, you can think of the base directory and the file structure
|
|
as a BSP Layer.
|
|
BSP Layers use the following naming convention:
|
|
<literallayout class='monospaced'>
|
|
meta-<bsp_name>
|
|
</literallayout>
|
|
"bsp_name" is a placeholder for the machine or platform name.
|
|
</para>
|
|
|
|
<para>
|
|
The layer's base directory (<filename>meta-<bsp_name></filename>) is the root
|
|
of the BSP Layer.
|
|
This root is what you add to the
|
|
<ulink url='&YOCTO_DOCS_REF_URL;#var-BBLAYERS'><filename>BBLAYERS</filename></ulink>
|
|
variable in the <filename>conf/bblayers.conf</filename> file found in the
|
|
<ulink url='&YOCTO_DOCS_DEV_URL;#yocto-project-build-directory'>Yocto Project Build Directory</ulink>.
|
|
Adding the root allows the Yocto Project build system to recognize the BSP
|
|
definition and from it build an image.
|
|
Here is an example:
|
|
<literallayout class='monospaced'>
|
|
BBLAYERS = " \
|
|
/usr/local/src/yocto/meta \
|
|
/usr/local/src/yocto/meta-yocto \
|
|
/usr/local/src/yocto/meta-<bsp_name> \
|
|
"
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
Some BSPs require additional layers on
|
|
top of the BSP's root layer in order to be functional.
|
|
For these cases, you also need to add those layers to the
|
|
<filename>BBLAYERS</filename> variable in order to build the BSP.
|
|
You must also specify in the "Dependencies" section of the BSP's
|
|
<filename>README</filename> file any requirements for additional
|
|
layers and, preferably, any
|
|
build instructions that might be contained elsewhere
|
|
in the <filename>README</filename> file.
|
|
</para>
|
|
|
|
<para>
|
|
For more detailed information on layers, see the
|
|
"<ulink url='&YOCTO_DOCS_DEV_URL;#understanding-and-creating-layers'>Understanding and Creating Layers</ulink>"
|
|
section of the Yocto Project Development Manual.
|
|
You can also see the detailed examples in the appendices of
|
|
<ulink url='&YOCTO_DOCS_DEV_URL;'>The Yocto Project Development Manual</ulink>.
|
|
</para>
|
|
</section>
|
|
|
|
|
|
<section id="bsp-filelayout">
|
|
<title>Example Filesystem Layout</title>
|
|
|
|
<para>
|
|
Below is the common form for the file structure inside a BSP Layer.
|
|
While you can use this basic form for the standard, realize that the actual structures
|
|
for specific BSPs could differ.
|
|
|
|
<literallayout class='monospaced'>
|
|
meta-<bsp_name>/
|
|
meta-<bsp_name>/<bsp_license_file>
|
|
meta-<bsp_name>/README
|
|
meta-<bsp_name>/README.sources
|
|
meta-<bsp_name>/binary/<bootable_images>
|
|
meta-<bsp_name>/conf/layer.conf
|
|
meta-<bsp_name>/conf/machine/*.conf
|
|
meta-<bsp_name>/recipes-bsp/*
|
|
meta-<bsp_name>/recipes-core/*
|
|
meta-<bsp_name>/recipes-graphics/*
|
|
meta-<bsp_name>/recipes-kernel/linux/linux-yocto_<kernel_rev>.bbappend
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
Below is an example of the Crown Bay BSP:
|
|
|
|
<literallayout class='monospaced'>
|
|
meta-crownbay/COPYING.MIT
|
|
meta-crownbay/README
|
|
meta-crownbay/README.sources
|
|
meta-crownbay/binary/
|
|
meta-crownbay/conf/
|
|
meta-crownbay/conf/layer.conf
|
|
meta-crownbay/conf/machine/
|
|
meta-crownbay/conf/machine/crownbay.conf
|
|
meta-crownbay/conf/machine/crownbay-noemgd.conf
|
|
meta-crownbay/recipes-bsp/
|
|
meta-crownbay/recipes-bsp/formfactor/
|
|
meta-crownbay/recipes-bsp/formfactor/formfactor_0.0.bbappend
|
|
meta-crownbay/recipes-bsp/formfactor/formfactor/
|
|
meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay/
|
|
meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay/machconfig
|
|
meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay-noemgd/
|
|
meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay-noemgd/machconfig
|
|
meta-crownbay/recipes-core/
|
|
meta-crownbay/recipes-core/tasks/
|
|
meta-crownbay/recipes-core/tasks/task-core-tools-profile.bbappend
|
|
meta-crownbay/recipes-graphics/
|
|
meta-crownbay/recipes-graphics/xorg-xserver/
|
|
meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config_0.1.bbappend
|
|
meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/
|
|
meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay/
|
|
meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay/xorg.conf
|
|
meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay-noemgd/
|
|
meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay-noemgd/xorg.conf
|
|
meta-crownbay/recipes-kernel/
|
|
meta-crownbay/recipes-kernel/linux/
|
|
meta-crownbay/recipes-kernel/linux/linux-yocto-rt_3.0.bbappend
|
|
meta-crownbay/recipes-kernel/linux/linux-yocto_2.6.37.bbappend
|
|
meta-crownbay/recipes-kernel/linux/linux-yocto_3.0.bbappend
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
The following sections describe each part of the proposed BSP format.
|
|
</para>
|
|
|
|
<section id="bsp-filelayout-license">
|
|
<title>License Files</title>
|
|
|
|
<para>
|
|
You can find these files in the BSP Layer at:
|
|
<literallayout class='monospaced'>
|
|
meta-<bsp_name>/<bsp_license_file>
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
These optional files satisfy licensing requirements for the BSP.
|
|
The type or types of files here can vary depending on the licensing requirements.
|
|
For example, in the Crown Bay BSP all licensing requirements are handled with the
|
|
<filename>COPYING.MIT</filename> file.
|
|
</para>
|
|
|
|
<para>
|
|
Licensing files can be MIT, BSD, GPLv*, and so forth.
|
|
These files are recommended for the BSP but are optional and totally up to the BSP developer.
|
|
</para>
|
|
</section>
|
|
|
|
<section id="bsp-filelayout-readme">
|
|
<title>README File</title>
|
|
<para>
|
|
You can find this file in the BSP Layer at:
|
|
<literallayout class='monospaced'>
|
|
meta-<bsp_name>/README
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
This file provides information on how to boot the live images that are optionally
|
|
included in the <filename>binary/</filename> directory.
|
|
The <filename>README</filename> file also provides special information needed for
|
|
building the image.
|
|
</para>
|
|
|
|
<para>
|
|
At a minimum, the <filename>README</filename> file must
|
|
contain a list of dependencies, such as the names of
|
|
any other layers on which the BSP depends and the name of
|
|
the BSP maintainer with his or her contact information.
|
|
</para>
|
|
</section>
|
|
|
|
<section id="bsp-filelayout-readme-sources">
|
|
<title>README.sources File</title>
|
|
<para>
|
|
You can find this file in the BSP Layer at:
|
|
<literallayout class='monospaced'>
|
|
meta-<bsp_name>/README.sources
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
This file provides information on where to locate the BSP source files.
|
|
For example, information provides where to find the sources that comprise
|
|
the images shipped with the BSP.
|
|
Information is also included to help you find the metadata used to generate the images
|
|
that ship with the BSP.
|
|
</para>
|
|
</section>
|
|
|
|
<section id="bsp-filelayout-binary">
|
|
<title>Pre-built User Binaries</title>
|
|
<para>
|
|
You can find these files in the BSP Layer at:
|
|
<literallayout class='monospaced'>
|
|
meta-<bsp_name>/binary/<bootable_images>
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
This optional area contains useful pre-built kernels and user-space filesystem
|
|
images appropriate to the target system.
|
|
This directory typically contains graphical (e.g. sato) and minimal live images
|
|
when the BSP tarball has been created and made available in the
|
|
<ulink url='&YOCTO_HOME_URL;'>Yocto Project</ulink> website.
|
|
You can use these kernels and images to get a system running and quickly get started
|
|
on development tasks.
|
|
</para>
|
|
|
|
<para>
|
|
The exact types of binaries present are highly hardware-dependent.
|
|
However, a README file should be present in the BSP Layer that explains how to use
|
|
the kernels and images with the target hardware.
|
|
If pre-built binaries are present, source code to meet licensing requirements must also
|
|
exist in some form.
|
|
</para>
|
|
</section>
|
|
|
|
<section id='bsp-filelayout-layer'>
|
|
<title>Layer Configuration File</title>
|
|
<para>
|
|
You can find this file in the BSP Layer at:
|
|
<literallayout class='monospaced'>
|
|
meta-<bsp_name>/conf/layer.conf
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
The <filename>conf/layer.conf</filename> file identifies the file structure as a Yocto
|
|
Project layer, identifies the
|
|
contents of the layer, and contains information about how Yocto Project should use it.
|
|
Generally, a standard boilerplate file such as the following works.
|
|
In the following example, you would replace "<filename>bsp</filename>" and
|
|
"<filename>_bsp</filename>" with the actual name
|
|
of the BSP (i.e. <filename><bsp_name></filename> from the example template).
|
|
</para>
|
|
|
|
<para>
|
|
<literallayout class='monospaced'>
|
|
# We have a conf and classes directory, add to BBPATH
|
|
BBPATH := "${BBPATH}:${LAYERDIR}"
|
|
|
|
# We have a recipes directory, add to BBFILES
|
|
BBFILES := "${BBFILES} ${LAYERDIR}/recipes/*/*.bb \
|
|
${LAYERDIR}/recipes/*/*.bbappend"
|
|
|
|
BBFILE_COLLECTIONS += "bsp"
|
|
BBFILE_PATTERN_bsp := "^${LAYERDIR}/"
|
|
BBFILE_PRIORITY_bsp = "6"
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
To illustrate the string substitutions, here are the last three statements from the Crown
|
|
Bay <filename>conf/layer.conf</filename> file:
|
|
<literallayout class='monospaced'>
|
|
BBFILE_COLLECTIONS += "crownbay"
|
|
BBFILE_PATTERN_crownbay := "^${LAYERDIR}/"
|
|
BBFILE_PRIORITY_crownbay = "6"
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
This file simply makes BitBake aware of the recipes and configuration directories.
|
|
The file must exist so that the Yocto Project build system can recognize the BSP.
|
|
</para>
|
|
</section>
|
|
|
|
<section id="bsp-filelayout-machine">
|
|
<title>Hardware Configuration Options</title>
|
|
<para>
|
|
You can find these files in the BSP Layer at:
|
|
<literallayout class='monospaced'>
|
|
meta-<bsp_name>/conf/machine/*.conf
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
The machine files bind together all the information contained elsewhere
|
|
in the BSP into a format that the Yocto Project build system can understand.
|
|
If the BSP supports multiple machines, multiple machine configuration files
|
|
can be present.
|
|
These filenames correspond to the values to which users have set the
|
|
<ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'><filename>MACHINE</filename></ulink> variable.
|
|
</para>
|
|
|
|
<para>
|
|
These files define things such as the kernel package to use
|
|
(<ulink url='&YOCTO_DOCS_REF_URL;#var-PREFERRED_PROVIDER'><filename>PREFERRED_PROVIDER</filename></ulink>
|
|
of virtual/kernel), the hardware drivers to
|
|
include in different types of images, any special software components
|
|
that are needed, any bootloader information, and also any special image
|
|
format requirements.
|
|
</para>
|
|
|
|
<para>
|
|
Each BSP Layer requires at least one machine file.
|
|
However, you can supply more than one file.
|
|
For example, in the Crown Bay BSP shown earlier in this section, the
|
|
<filename>conf/machine</filename> directory contains two configuration files:
|
|
<filename>crownbay.conf</filename> and <filename>crownbay-noemgd.conf</filename>.
|
|
The <filename>crownbay.conf</filename> file is used for the Crown Bay BSP
|
|
that supports the <trademark class='registered'>Intel</trademark> Embedded
|
|
Media and Graphics Driver (<trademark class='registered'>Intel</trademark>
|
|
EMGD), while the <filename>crownbay-noemgd.conf</filename> file is used for the
|
|
Crown Bay BSP that does not support the <trademark class='registered'>Intel</trademark>
|
|
EMGD.
|
|
</para>
|
|
|
|
<para>
|
|
This <filename>crownbay.conf</filename> file could also include
|
|
a hardware "tuning" file that is commonly used to
|
|
define the package architecture and specify
|
|
optimization flags, which are carefully chosen to give best
|
|
performance on a given processor.
|
|
</para>
|
|
|
|
<para>
|
|
Tuning files are found in the <filename>meta/conf/machine/include</filename>
|
|
directory of the
|
|
<ulink url='&YOCTO_DOCS_DEV_URL;#yocto-project-files'>Yocto Project Files</ulink>.
|
|
Tuning files can also reside in the BSP Layer itself.
|
|
For example, the <filename>ia32-base.inc</filename> file resides in the
|
|
<filename>meta-intel</filename> BSP Layer in <filename>conf/machine/include</filename>.
|
|
</para>
|
|
|
|
<para>
|
|
To use an include file, you simply include them in the machine configuration file.
|
|
For example, the Crown Bay BSP <filename>crownbay.conf</filename> has the
|
|
following statements:
|
|
<literallayout class='monospaced'>
|
|
include conf/machine/include/tune-atom.inc
|
|
include conf/machine/include/ia32-base.inc
|
|
</literallayout>
|
|
</para>
|
|
</section>
|
|
|
|
<section id='bsp-filelayout-misc-recipes'>
|
|
<title>Miscellaneous Recipe Files</title>
|
|
<para>
|
|
You can find these files in the BSP Layer at:
|
|
<literallayout class='monospaced'>
|
|
meta-<bsp_name>/recipes-bsp/*
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
This optional directory contains miscellaneous recipe files for the BSP.
|
|
Most notably would be the formfactor files.
|
|
For example, in the Crown Bay BSP there is the
|
|
<filename>formfactor_0.0.bbappend</filename> file, which is an append file used
|
|
to augment the recipe that starts the build.
|
|
Furthermore, there are machine-specific settings used during the build that are
|
|
defined by the <filename>machconfig</filename> files.
|
|
In the Crown Bay example, two <filename>machconfig</filename> files exist:
|
|
one that supports the
|
|
<trademark class='registered'>Intel</trademark> Embedded
|
|
Media and Graphics Driver (<trademark class='registered'>Intel</trademark>
|
|
EMGD) and one that does not:
|
|
<literallayout class='monospaced'>
|
|
meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay/machconfig
|
|
meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay-noemgd/machconfig
|
|
meta-crownbay/recipes-bsp/formfactor/formfactor_0.0.bbappend
|
|
</literallayout>
|
|
</para>
|
|
|
|
<note><para>
|
|
If a BSP does not have a formfactor entry, defaults are established according to
|
|
the formfactor configuration file that is installed by the main
|
|
formfactor recipe
|
|
<filename>meta/recipes-bsp/formfactor/formfactor_0.0.bb</filename>,
|
|
which is found in the
|
|
<ulink url='&YOCTO_DOCS_DEV_URL;#yocto-project-files'>Yocto Project Files</ulink>.
|
|
</para></note>
|
|
</section>
|
|
|
|
<section id='bsp-filelayout-core-recipes'>
|
|
<title>Core Recipe Files</title>
|
|
<para>
|
|
You can find these files in the BSP Layer at:
|
|
<literallayout class='monospaced'>
|
|
meta-<bsp_name>/recipes-core/*
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
This directory contains recipe files that are almost always necessary to build a
|
|
useful, working Linux image.
|
|
Thus, the term "core" is used to group these recipes.
|
|
For example, in the Crown Bay BSP there is the
|
|
<filename>task-core-tools-profile.bbappend</filename> file, which is an append file used
|
|
to recommend that the
|
|
<ulink url='http://sourceware.org/systemtap/wiki'>SystemTap</ulink>
|
|
package be included as a package when the image is built.
|
|
</para>
|
|
</section>
|
|
|
|
<section id='bsp-filelayout-recipes-graphics'>
|
|
<title>Display Support Files</title>
|
|
<para>
|
|
You can find these files in the BSP Layer at:
|
|
<literallayout class='monospaced'>
|
|
meta-<bsp_name>/recipes-graphics/*
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
This optional directory contains recipes for the BSP if it has
|
|
special requirements for graphics support.
|
|
All files that are needed for the BSP to support a display are kept here.
|
|
For example, the Crown Bay BSP contains two versions of the
|
|
<filename>xorg.conf</filename> file.
|
|
The version in <filename>crownbay</filename> builds a BSP that supports the
|
|
<trademark class='registered'>Intel</trademark> Embedded Media Graphics Driver (EMGD),
|
|
while the version in <filename>crownbay-noemgd</filename> builds
|
|
a BSP that supports Video Electronics Standards Association (VESA) graphics only:
|
|
<literallayout class='monospaced'>
|
|
meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config_0.1.bbappend
|
|
meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay/xorg.conf
|
|
meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay-noemgd/xorg.conf
|
|
</literallayout>
|
|
</para>
|
|
</section>
|
|
|
|
<section id='bsp-filelayout-kernel'>
|
|
<title>Linux Kernel Configuration</title>
|
|
<para>
|
|
You can find these files in the BSP Layer at:
|
|
<literallayout class='monospaced'>
|
|
meta-<bsp_name>/recipes-kernel/linux/linux-yocto_*.bbappend
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
These files append your specific changes to the kernel you are using.
|
|
</para>
|
|
<para>
|
|
For your BSP, you typically want to use an existing Yocto Project kernel found in the
|
|
<ulink url='&YOCTO_DOCS_DEV_URL;#yocto-project-files'>Yocto
|
|
Project Files</ulink> at <filename>meta/recipes-kernel/linux</filename>.
|
|
You can append your specific changes to the kernel recipe by using a
|
|
similarly named append file, which is located in the BSP Layer (e.g.
|
|
the <filename>meta-<bsp_name>/recipes-kernel/linux</filename> directory).
|
|
</para>
|
|
<para>
|
|
Suppose the BSP uses the <filename>linux-yocto_3.0.bb</filename> kernel,
|
|
which is the preferred kernel to use for developing a new BSP using the Yocto Project.
|
|
In other words, you have selected the kernel in your
|
|
<filename><bsp_name>.conf</filename> file by adding the following statements:
|
|
<literallayout class='monospaced'>
|
|
PREFERRED_PROVIDER_virtual/kernel ?= "linux-yocto"
|
|
PREFERRED_VERSION_linux-yocto = "3.0%"
|
|
</literallayout>
|
|
You would use the <filename>linux-yocto_3.0.bbappend</filename> file to append
|
|
specific BSP settings to the kernel, thus configuring the kernel for your particular BSP.
|
|
</para>
|
|
<para>
|
|
As an example, look at the existing Crown Bay BSP.
|
|
The append file used is:
|
|
<literallayout class='monospaced'>
|
|
meta-crownbay/recipes-kernel/linux/linux-yocto_3.0.bbappend
|
|
</literallayout>
|
|
The following listing shows the file.
|
|
Be aware that the actual commit ID strings in this example listing might be different
|
|
than the actual strings in the file from the <filename>meta-intel</filename>
|
|
Git source repository.
|
|
<literallayout class='monospaced'>
|
|
FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
|
|
|
|
COMPATIBLE_MACHINE_crownbay = "crownbay"
|
|
KMACHINE_crownbay = "yocto/standard/crownbay"
|
|
KERNEL_FEATURES_append_crownbay += " cfg/smp.scc"
|
|
|
|
COMPATIBLE_MACHINE_crownbay-noemgd = "crownbay-noemgd"
|
|
KMACHINE_crownbay-noemgd = "yocto/standard/crownbay"
|
|
KERNEL_FEATURES_append_crownbay-noemgd += " cfg/smp.scc"
|
|
|
|
SRCREV_machine_pn-linux-yocto_crownbay ?= "63c65842a3a74e4bd3128004ac29b5639f16433f"
|
|
SRCREV_meta_pn-linux-yocto_crownbay ?= "59314a3523e360796419d76d78c6f7d8c5ef2593"
|
|
|
|
SRCREV_machine_pn-linux-yocto_crownbay-noemgd ?= "63c65842a3a74e4bd3128004ac29b5639f16433f"
|
|
SRCREV_meta_pn-linux-yocto_crownbay-noemgd ?= "59314a3523e360796419d76d78c6f7d8c5ef2593"
|
|
</literallayout>
|
|
This append file contains statements used to support the Crown Bay BSP for both
|
|
<trademark class='registered'>Intel</trademark> EMGD and the VESA graphics.
|
|
The build process, in this case, recognizes and uses only the statements that
|
|
apply to the defined machine name - <filename>crownbay</filename> in this case.
|
|
So, the applicable statements in the <filename>linux-yocto_3.0.bbappend</filename>
|
|
file are follows:
|
|
<literallayout class='monospaced'>
|
|
FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
|
|
|
|
COMPATIBLE_MACHINE_crownbay = "crownbay"
|
|
KMACHINE_crownbay = "yocto/standard/crownbay"
|
|
KERNEL_FEATURES_append_crownbay += " cfg/smp.scc"
|
|
|
|
SRCREV_machine_pn-linux-yocto_crownbay ?= "63c65842a3a74e4bd3128004ac29b5639f16433f"
|
|
SRCREV_meta_pn-linux-yocto_crownbay ?= "59314a3523e360796419d76d78c6f7d8c5ef2593"
|
|
</literallayout>
|
|
The append file defines <filename>crownbay</filename> as the compatible machine and
|
|
defines the <filename>KMACHINE</filename>.
|
|
The file also points to some configuration fragments to use by setting the
|
|
<filename>KERNEL_FEATURES</filename> variable.
|
|
The location for the configuration fragments is the kernel tree itself in the
|
|
<ulink url='&YOCTO_DOCS_DEV_URL;#yocto-project-build-directory'>Yocto Project Build
|
|
Directory</ulink> under <filename>linux/meta</filename>.
|
|
Finally, the append file points to the specific commits in the
|
|
<ulink url='&YOCTO_DOCS_DEV_URL;#yocto-project-files'>Yocto Project Files</ulink> Git
|
|
repository and the <filename>meta</filename> Git repository branches to identify the
|
|
exact kernel needed to build the Crown Bay BSP.
|
|
</para>
|
|
<para>
|
|
One thing missing in this particular BSP, which you will typically need when
|
|
developing a BSP, is the kernel configuration file (<filename>.config</filename>) for your BSP.
|
|
When developing a BSP, you probably have a kernel configuration file or a set of kernel
|
|
configuration files that, when taken together, define the kernel configuration for your BSP.
|
|
You can accomplish this definition by putting the configurations in a file or a set of files
|
|
inside a directory located at the same level as your append file and having the same name
|
|
as the kernel.
|
|
With all these conditions met simply reference those files in a
|
|
<filename>SRC_URI</filename> statement in the append file.
|
|
</para>
|
|
<para>
|
|
For example, suppose you had a set of configuration options in a file called
|
|
<filename>myconfig</filename>.
|
|
If you put that file inside a directory named
|
|
<filename>/linux-yocto</filename> and then added
|
|
a <filename>SRC_URI</filename> statement such as the following to the append file,
|
|
those configuration
|
|
options will be picked up and applied when the kernel is built.
|
|
<literallayout class='monospaced'>
|
|
SRC_URI += "file://myconfig"
|
|
</literallayout>
|
|
</para>
|
|
<para>
|
|
As mentioned earlier, you can group related configurations into multiple files and
|
|
name them all in the <filename>SRC_URI</filename> statement as well.
|
|
For example, you could group separate configurations specifically for Ethernet and graphics
|
|
into their own files and add those by using a <filename>SRC_URI</filename> statement like the
|
|
following in your append file:
|
|
<literallayout class='monospaced'>
|
|
SRC_URI += "file://myconfig \
|
|
file://eth.cfg \
|
|
file://gfx.cfg"
|
|
</literallayout>
|
|
</para>
|
|
<para>
|
|
The <filename>FILESEXTRAPATHS</filename> variable is in boilerplate form in the
|
|
previous example in order to make it easy to do that.
|
|
This variable must be in your layer or BitBake will not find the patches or
|
|
configurations even if you have them in your <filename>SRC_URI</filename>.
|
|
The <filename>FILESEXTRAPATHS</filename> variable enables the build process to
|
|
find those configuration files.
|
|
</para>
|
|
<note>
|
|
<para>
|
|
Other methods exist to accomplish grouping and defining configuration options.
|
|
For example, if you are working with a local clone of the kernel repository,
|
|
you could checkout the kernel's <filename>meta</filename> branch, make your changes,
|
|
and then push the changes to the local bare clone of the kernel.
|
|
The result is that you directly add configuration options to the Yocto kernel
|
|
<filename>meta</filename> branch for your BSP.
|
|
The configuration options will likely end up in that location anyway if the BSP gets
|
|
added to the Yocto Project.
|
|
For an example showing how to change the BSP configuration, see the
|
|
"<ulink url='&YOCTO_DOCS_DEV_URL;#changing-the-bsp-configuration'>Changing the BSP Configuration</ulink>"
|
|
section in the Yocto Project Development Manual.
|
|
For a better understanding of working with a local clone of the kernel repository
|
|
and a local bare clone of the kernel, see the
|
|
"<ulink url='&YOCTO_DOCS_DEV_URL;#modifying-the-kernel-source-code'>Modifying the Kernel
|
|
Source Code</ulink>" section also in the Yocto Project Development Manual.</para>
|
|
<para>
|
|
In general, however, the Yocto Project maintainers take care of moving the
|
|
<filename>SRC_URI</filename>-specified
|
|
configuration options to the kernel's <filename>meta</filename> branch.
|
|
Not only is it easier for BSP developers to not have to worry about putting those
|
|
configurations in the branch, but having the maintainers do it allows them to apply
|
|
'global' knowledge about the kinds of common configuration options multiple BSPs in
|
|
the tree are typically using.
|
|
This allows for promotion of common configurations into common features.</para>
|
|
</note>
|
|
</section>
|
|
</section>
|
|
|
|
<section id='bsp-licensing-considerations'>
|
|
<title>BSP Licensing Considerations</title>
|
|
|
|
<para>
|
|
In some cases, a BSP contains separately licensed Intellectual Property (IP)
|
|
for a component or components.
|
|
For these cases, you are required to accept the terms of a commercial or other
|
|
type of license that requires some kind of explicit End User License Agreement (EULA).
|
|
Once the license is accepted, the Yocto Project build system can then build and
|
|
include the corresponding component in the final BSP image.
|
|
If the BSP is available as a pre-built image, you can download the image after
|
|
agreeing to the license or EULA.
|
|
</para>
|
|
|
|
<para>
|
|
You could find that some separately licensed components that are essential
|
|
for normal operation of the system might not have an unencumbered (or free)
|
|
substitute.
|
|
Without these essential components, the system would be non-functional.
|
|
Then again, you might find that other licensed components that are simply
|
|
'good-to-have' or purely elective do have an unencumbered, free replacement
|
|
component that you can use rather than agreeing to the separately licensed component.
|
|
Even for components essential to the system, you might find an unencumbered component
|
|
that is not identical but will work as a less-capable version of the
|
|
licensed version in the BSP recipe.
|
|
</para>
|
|
|
|
<para>
|
|
For cases where you can substitute a free component and still
|
|
maintain the system's functionality, the Yocto Project website's
|
|
<ulink url='&YOCTO_HOME_URL;/download/all?keys=&download_type=1&download_version='>BSP
|
|
Download Page</ulink> makes available de-featured BSPs
|
|
that are completely free of any IP encumbrances.
|
|
For these cases, you can use the substitution directly and
|
|
without any further licensing requirements.
|
|
If present, these fully de-featured BSPs are named appropriately
|
|
different as compared to the names of the respective
|
|
encumbered BSPs.
|
|
If available, these substitutions are your
|
|
simplest and most preferred options.
|
|
Use of these substitutions of course assumes the resulting functionality meets
|
|
system requirements.
|
|
</para>
|
|
|
|
<para>
|
|
If however, a non-encumbered version is unavailable or
|
|
it provides unsuitable functionality or quality, you can use an encumbered
|
|
version.
|
|
</para>
|
|
|
|
<para>
|
|
A couple different methods exist within the Yocto
|
|
Project build system to satisfy the licensing
|
|
requirements for an encumbered BSP.
|
|
The following list describes them in order of preference:
|
|
<orderedlist>
|
|
<listitem><para><emphasis>Use the <filename>LICENSE_FLAGS</filename> variable
|
|
to define the Yocto Project recipes that have commercial or other types of
|
|
specially-licensed packages:</emphasis>
|
|
For each of those recipes, you can
|
|
specify a matching license string in a
|
|
<filename>local.conf</filename> variable named
|
|
<filename>LICENSE_FLAGS_WHITELIST</filename>.
|
|
Specifying the matching license string signifies that you agree to the license.
|
|
Thus, the build system can build the corresponding recipe and include
|
|
the component in the image.
|
|
See the
|
|
"<ulink url='&YOCTO_DOCS_REF_URL;#enabling-commercially-licensed-recipes'>Enabling
|
|
Commercially Licensed Recipes</ulink>" section in the Yocto Project Reference
|
|
Manual for details on how to use these variables.</para>
|
|
<para>If you build as you normally would, without
|
|
specifying any recipes in the
|
|
<filename>LICENSE_FLAGS_WHITELIST</filename>, the build stops and
|
|
provides you with the list of recipes that you have
|
|
tried to include in the image that need entries in
|
|
the <filename>LICENSE_FLAGS_WHITELIST</filename>.
|
|
Once you enter the appropriate license flags into the whitelist,
|
|
restart the build to continue where it left off.
|
|
During the build, the prompt will not appear again
|
|
since you have satisfied the requirement.</para>
|
|
<para>Once the appropriate license flags are whitelisted
|
|
in the <filename>LICENSE_FLAGS_WHITELIST</filename> variable, you
|
|
can build the encumbered image with no change at all
|
|
to the normal build process.</para></listitem>
|
|
<listitem><para><emphasis>Get a pre-built version of the BSP:</emphasis>
|
|
You can get this type of BSP by visiting the Yocto Project website's
|
|
<ulink url='&YOCTO_HOME_URL;/download'>Download</ulink>
|
|
page and clicking on "BSP Downloads".
|
|
You can download BSP tarballs that contain proprietary components
|
|
after agreeing to the licensing
|
|
requirements of each of the individually encumbered
|
|
packages as part of the download process.
|
|
Obtaining the BSP this way allows you to access an encumbered
|
|
image immediately after agreeing to the
|
|
click-through license agreements presented by the
|
|
website.
|
|
Note that if you want to build the image
|
|
yourself using the recipes contained within the BSP
|
|
tarball, you will still need to create an
|
|
appropriate <filename>LICENSE_FLAGS_WHITELIST</filename> to match the
|
|
encumbered recipes in the BSP.</para></listitem>
|
|
</orderedlist>
|
|
</para>
|
|
|
|
<note>
|
|
Pre-compiled images are bundled with
|
|
a time-limited kernel that runs for a
|
|
predetermined amount of time (10 days) before it forces
|
|
the system to reboot.
|
|
This limitation is meant to discourage direct redistribution
|
|
of the image.
|
|
You must eventually rebuild the image if you want to remove this restriction.
|
|
</note>
|
|
</section>
|
|
|
|
<section id='using-the-yocto-projects-bsp-tools'>
|
|
<title>Using the Yocto Project's BSP Tools</title>
|
|
|
|
<para>
|
|
The Yocto Project includes a couple of tools that enable
|
|
you to create a <link linkend='bsp-layers'>BSP layer</link>
|
|
from scratch and do basic configuration and maintenance
|
|
of the kernel without ever looking at a Yocto Project metadata file.
|
|
These tools are <filename>yocto-bsp</filename> and <filename>yocto-kernel</filename>,
|
|
respectively.
|
|
</para>
|
|
|
|
<para>
|
|
The following sections describe the common location and help features as well
|
|
as details for the <filename>yocto-bsp</filename> and <filename>yocto-kernel</filename>
|
|
tools.
|
|
</para>
|
|
|
|
<section id='common-features'>
|
|
<title>Common Features</title>
|
|
|
|
<para>
|
|
Designed to have a command interface somewhat like
|
|
<ulink url='&YOCTO_DOCS_DEV_URL;#git'>Git</ulink>, each
|
|
tool is structured as a set of sub-commands under a
|
|
top-level command.
|
|
The top-level command (<filename>yocto-bsp</filename>
|
|
or <filename>yocto-kernel</filename>) itself does
|
|
nothing but invoke or provide help on the sub-commands
|
|
it supports.
|
|
</para>
|
|
|
|
<para>
|
|
Both tools reside in the <filename>scripts/</filename> subdirectory
|
|
of the <ulink url='&YOCTO_DOCS_DEV_URL;#yocto-project-files'>Yocto Project
|
|
Files</ulink>.
|
|
Consequently, to use the scripts, you must <filename>source</filename> the
|
|
environment just as you would when invoking a build:
|
|
<literallayout class='monospaced'>
|
|
$ source oe-init-build-env [build_dir]
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
The most immediately useful function is to get help on both tools.
|
|
The built-in help system makes it easy to drill down at
|
|
any time and view the syntax required for any specific command.
|
|
Simply enter the name of the command, or the command along with
|
|
<filename>help</filename> to display a list of the available sub-commands.
|
|
Here is an example:
|
|
<literallayout class='monospaced'>
|
|
$ yocto-bsp
|
|
$ yocto-bsp help
|
|
|
|
Usage:
|
|
|
|
Create a customized Yocto BSP layer.
|
|
|
|
usage: yocto-bsp [--version] [--help] COMMAND [ARGS]
|
|
|
|
The most commonly used 'yocto-bsp' commands are:
|
|
create Create a new Yocto BSP
|
|
list List available values for options and BSP properties
|
|
|
|
See 'yocto-bsp help COMMAND' for more information on a specific command.
|
|
|
|
|
|
Options:
|
|
--version show program's version number and exit
|
|
-h, --help show this help message and exit
|
|
-D, --debug output debug information
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
Similarly, entering just the name of a sub-command shows the detailed usage
|
|
for that sub-command:
|
|
<literallayout class='monospaced'>
|
|
$ yocto-bsp create
|
|
|
|
Usage:
|
|
|
|
Create a new Yocto BSP
|
|
usage: yocto-bsp create <bsp-name> <karch> [-o <DIRNAME> | --outdir <DIRNAME>]
|
|
[-i <JSON PROPERTY FILE> | --infile <JSON PROPERTY_FILE>]
|
|
|
|
This command creates a Yocto BSP based on the specified parameters.
|
|
The new BSP will be a new Yocto BSP layer contained by default within
|
|
the top-level directory specified as 'meta-bsp-name'. The -o option
|
|
can be used to place the BSP layer in a directory with a different
|
|
name and location.
|
|
|
|
...
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
For any sub-command, you can also use the word 'help' just before the
|
|
sub-command to get more extensive documentation:
|
|
<literallayout class='monospaced'>
|
|
$ yocto-bsp help create
|
|
|
|
NAME
|
|
yocto-bsp create - Create a new Yocto BSP
|
|
|
|
SYNOPSIS
|
|
yocto-bsp create <bsp-name> <karch> [-o <DIRNAME> | --outdir <DIRNAME>]
|
|
[-i <JSON PROPERTY FILE> | --infile <JSON PROPERTY_FILE>]
|
|
|
|
DESCRIPTION
|
|
This command creates a Yocto BSP based on the specified
|
|
parameters. The new BSP will be a new Yocto BSP layer contained
|
|
by default within the top-level directory specified as
|
|
'meta-bsp-name'. The -o option can be used to place the BSP layer
|
|
in a directory with a different name and location.
|
|
|
|
The value of the 'karch' parameter determines the set of files
|
|
that will be generated for the BSP, along with the specific set of
|
|
'properties' that will be used to fill out the BSP-specific
|
|
portions of the BSP.
|
|
|
|
...
|
|
|
|
NOTE: Once created, you should add your new layer to your
|
|
bblayers.conf file in order for it to be subsquently seen and
|
|
modified by the yocto-kernel tool.
|
|
|
|
NOTE for x86- and x86_64-based BSPs: The generated BSP assumes the
|
|
presence of the of the meta-intel layer, so you should also have a
|
|
meta-intel layer present and added to your bblayers.conf as well.
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
Now that you know where these two commands reside and how to access information
|
|
on them, you should find it relatively straightforward to discover the commands
|
|
necessary to create a BSP and perform basic kernel maintainence on that BSP using
|
|
the tools.
|
|
The next sections provide a concrete starting point to expand on a few points that
|
|
might not be immediately obvious or that could use further explanation.
|
|
</para>
|
|
</section>
|
|
|
|
|
|
<section id='creating-a-new-bsp-layer-using-the-yocto-bsp-script'>
|
|
<title>Creating a new BSP Layer Using the yocto-bsp Script</title>
|
|
|
|
<para>
|
|
The <filename>yocto-bsp</filename> script creates a new
|
|
<link linkend='bsp-layers'>BSP layer</link> for any architecture supported
|
|
by the Yocto Project, as well as QEMU versions of the same.
|
|
The default mode of the script's operation is to prompt you for information needed
|
|
to generate the BSP layer.
|
|
For the current set of BSPs, the script prompts you for various important
|
|
parameters such as:
|
|
<itemizedlist>
|
|
<listitem><para>which kernel to use</para></listitem>
|
|
<listitem><para>which branch of that kernel to use (or re-use)</para></listitem>
|
|
<listitem><para>whether or not to use X, and if so, which drivers to use</para></listitem>
|
|
<listitem><para>whether to turn on SMP</para></listitem>
|
|
<listitem><para>whether the BSP has a keyboard</para></listitem>
|
|
<listitem><para>whether the BSP has a touchscreen</para></listitem>
|
|
<listitem><para>any remaining configurable items associated with the BSP</para></listitem>
|
|
</itemizedlist>
|
|
</para>
|
|
|
|
<para>
|
|
You use the <filename>yocto-bsp create</filename> sub-command to create
|
|
a new BSP layer.
|
|
This command requires you to specify a particular architecture on which to
|
|
base the BSP.
|
|
Assuming you have sourced the environment, you can use the
|
|
<filename>yocto-bsp list karch</filename> sub-command to list the
|
|
architectures available for BSP creation as follows:
|
|
<literallayout class='monospaced'>
|
|
$ yocto-bsp list karch
|
|
Architectures available:
|
|
arm
|
|
powerpc
|
|
i386
|
|
mips
|
|
x86_64
|
|
qemu
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
The remainder of this section presents an example that uses
|
|
<filename>myarm</filename> as the machine name and <filename>qemu</filename>
|
|
as the machine architecture.
|
|
Of the available architectures, <filename>qemu</filename> is the only architecture
|
|
that causes the script to prompt you further for an actual architecture.
|
|
In every other way, this architecture is representative of how creating a BSP for
|
|
a 'real' machine would work.
|
|
The reason the example uses this architecture is because it is an emulated architecture
|
|
and can easily be followed without requireing actual hardware.
|
|
</para>
|
|
|
|
<para>
|
|
As the <filename>yocto-bsp create</filename> command runs, default values for
|
|
the prompts appear in brackets.
|
|
Pressing enter without supplying anything on the command line or pressing enter
|
|
and providing an invalid response causes the script to accept the default value.
|
|
</para>
|
|
|
|
<para>
|
|
Following is the complete example:
|
|
<literallayout class='monospaced'>
|
|
$ yocto-bsp create myarm qemu
|
|
Which qemu architecture would you like to use? [default: x86]
|
|
1) common 32-bit x86
|
|
2) common 64-bit x86
|
|
3) common 32-bit ARM
|
|
4) common 32-bit PowerPC
|
|
5) common 32-bit MIPS
|
|
3
|
|
Would you like to use the default (3.2) kernel? (Y/n)
|
|
Do you need a new machine branch for this BSP (the alternative is to re-use an existing branch)? [Y/n]
|
|
Getting branches from remote repo git://git.yoctoproject.org/linux-yocto-3.2...
|
|
Please choose a machine branch to base this BSP on => [default: standard/default/common-pc]
|
|
1) base
|
|
2) standard/base
|
|
3) standard/default/arm-versatile-926ejs
|
|
4) standard/default/base
|
|
5) standard/default/beagleboard
|
|
6) standard/default/cedartrailbsp (copy).xml
|
|
7) standard/default/common-pc-64/base
|
|
8) standard/default/common-pc-64/jasperforest
|
|
9) standard/default/common-pc-64/romley
|
|
10) standard/default/common-pc-64/sugarbay
|
|
11) standard/default/common-pc/atom-pc
|
|
12) standard/default/common-pc/base
|
|
13) standard/default/crownbay
|
|
14) standard/default/emenlow
|
|
15) standard/default/fishriver
|
|
16) standard/default/fri2
|
|
17) standard/default/fsl-mpc8315e-rdb
|
|
18) standard/default/mti-malta32-be
|
|
19) standard/default/mti-malta32-le
|
|
20) standard/default/preempt-rt
|
|
21) standard/default/qemu-ppc32
|
|
22) standard/default/routerstationpro
|
|
23) standard/preempt-rt/base
|
|
24) standard/preempt-rt/qemu-ppc32
|
|
25) standard/preempt-rt/routerstationpro
|
|
26) standard/tiny
|
|
3
|
|
Do you need SMP support? (Y/n)
|
|
Does your BSP have a touchscreen? (y/N)
|
|
Does your BSP have a keyboard? (Y/n)
|
|
New qemu BSP created in meta-myarm
|
|
</literallayout>
|
|
Let's take a closer look at the example now:
|
|
<orderedlist>
|
|
<listitem><para>For the <filename>qemu</filename> architecture,
|
|
the script first prompts you for which emulated architecture to use.
|
|
In the example, we use the <filename>arm</filename> architecture.
|
|
</para></listitem>
|
|
<listitem><para>The script then prompts you for the kernel.
|
|
The default kernel is 3.2 and is acceptable.
|
|
So, the example accepts the default.
|
|
If you enter 'n', the script prompts you to further enter the kernel
|
|
you do want to use (e.g. 3.0, 3.2_preempt-rt, etc.).</para></listitem>
|
|
<listitem><para>Next, the script asks whether you would like to have a new
|
|
branch created especially for your BSPin the local
|
|
<ulink url='&YOCTO_DOCS_DEV_URL;#local-kernel-files'>Linux Yocto Kernel</ulink>
|
|
Git repository .
|
|
If not, then the script re-uses an existing branch.</para>
|
|
<para>In this example, the default (or 'yes') is accepted.
|
|
Thus, a new branch is created for the BSP rather than using a common, shared
|
|
branch.
|
|
The new branch is the branch committed to for any patches you might later add.
|
|
The reason a new branch is the default is that typically
|
|
new BSPs do require BSP-specific patches.
|
|
The tool thus assumes that most of time a new branch is required.
|
|
<note>In the current implementation, creation or re-use of a branch does
|
|
not actually matter.
|
|
The reason is because the generated BSPs assume that patches and
|
|
configurations live in recipe-space, which is something that can be done
|
|
with or without a dedicated branch.
|
|
Generated BSPs, however, are different.
|
|
This difference becomes significant once the tool's 'publish' functionality
|
|
is implemented.</note></para></listitem>
|
|
<listitem><para>Regardless of which choice is made in the previous step,
|
|
you are now given the opportunity to select a particular machine branch on
|
|
which to base your new BSP-specific machine branch on
|
|
(or to re-use if you had elected to not create a new branch).
|
|
Because this example is generating an <filename>arm</filename> BSP, the example
|
|
uses <filename>#3</filename> at the prompt, which selects the arm-versatile branch.
|
|
</para></listitem>
|
|
<listitem><para>The remainder of the prompts are routine.
|
|
Defaults are accepted for each.</para></listitem>
|
|
<listitem><para>By default, the script creates the new BSP Layer in the
|
|
<ulink url='&YOCTO_DOCS_DEV_URL;#yocto-project-build-directory'>Yocto Project
|
|
Build Directory</ulink>.</para></listitem>
|
|
</orderedlist>
|
|
</para>
|
|
|
|
<para>
|
|
Once the BSP Layer is created, you must add it to your
|
|
<filename>bblayers.conf</filename> file.
|
|
Here is an example:
|
|
<literallayout class='monospaced'>
|
|
BBLAYERS = " \
|
|
/usr/local/src/yocto/meta \
|
|
/usr/local/src/yocto/meta-yocto \
|
|
/usr/local/src/yocto/meta-myarm \
|
|
"
|
|
</literallayout>
|
|
Adding the layer to this file allows the build system to build the BSP and
|
|
the <filename>yocto-kernel</filename> tool to be able to find the layer and
|
|
other metadata it needs on which to operate.
|
|
</para>
|
|
</section>
|
|
|
|
<section id='managing-kernel-patches-and-config-items-with-yocto-kernel'>
|
|
<title>Managing Kernel Patches and Config Items with yocto-kernel</title>
|
|
|
|
<para>
|
|
Assuming you have created a Yocto Project
|
|
<link linkend='bsp-layers'>BSP Layer</link> using
|
|
<link linkend='creating-a-new-bsp-layer-using-the-yocto-bsp-script'>
|
|
<filename>yocto-bsp</filename></link> and you added it to your
|
|
<ulink url='&YOCTO_DOCS_REF_URL;#var-BBLAYERS'><filename>BBLAYERS</filename></ulink>
|
|
variable in the <filename>bblayers.conf</filename> file, you can now use
|
|
the <filename>yocto-kernel</filename> script to add patches and configuration
|
|
items to the BSP's kernel.
|
|
</para>
|
|
|
|
<para>
|
|
The <filename>yocto-kernel</filename> script allows you to add, remove, and list patches
|
|
and kernel config settings to a Yocto Project BSP's kernel
|
|
<filename>.bbappend</filename> file.
|
|
All you need to do is use the appropriate sub-command.
|
|
Recall that the easiest way to see exactly what sub-commands are available
|
|
is to use the <filename>yocto-kernel</filename> built-in help as follows:
|
|
<literallayout class='monospaced'>
|
|
$ yocto-kernel
|
|
Usage:
|
|
|
|
Modify and list Yocto BSP kernel config items and patches.
|
|
|
|
usage: yocto-kernel [--version] [--help] COMMAND [ARGS]
|
|
|
|
The most commonly used 'yocto-kernel' commands are:
|
|
config list List the modifiable set of bare kernel config options for a BSP
|
|
config add Add or modify bare kernel config options for a BSP
|
|
config rm Remove bare kernel config options from a BSP
|
|
patch list List the patches associated with a BSP
|
|
patch add Patch the Yocto kernel for a BSP
|
|
patch rm Remove patches from a BSP
|
|
|
|
See 'yocto-kernel help COMMAND' for more information on a specific command.
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
The <filename>yocto-kernel patch add</filename> sub-command allows you to add a
|
|
patch to a BSP.
|
|
The following example adds two patches to the <filename>myarm</filename> BSP:
|
|
<literallayout class='monospaced'>
|
|
$ yocto-kernel patch add myarm ~/test.patch
|
|
Added patches:
|
|
test.patch
|
|
|
|
$ yocto-kernel patch add myarm ~/yocto-testmod.patch
|
|
Added patches:
|
|
yocto-testmod.patch
|
|
</literallayout>
|
|
<note>Although the previous example adds patches one at a time, it is possible
|
|
to add multiple patches at the same time.</note>
|
|
</para>
|
|
|
|
<para>
|
|
You can verify patches have been added by using the
|
|
<filename>yocto-kernel patch list</filename> sub-command.
|
|
Here is an example:
|
|
<literallayout class='monospaced'>
|
|
$ yocto-kernel patch list myarm
|
|
The current set of machine-specific patches for myarm is:
|
|
1) test.patch
|
|
2) yocto-testmod.patch
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
You can also use the <filename>yocto-kernel</filename> script to
|
|
remove a patch using the <filename>yocto-kernel patch rm</filename> sub-command.
|
|
Here is an example:
|
|
<literallayout class='monospaced'>
|
|
$ yocto-kernel patch rm myarm
|
|
Specify the patches to remove:
|
|
1) test.patch
|
|
2) yocto-testmod.patch
|
|
1
|
|
Removed patches:
|
|
test.patch
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
Again, using the <filename>yocto-kernel patch list</filename> sub-command,
|
|
you can verify that the patch was in fact removed:
|
|
<literallayout class='monospaced'>
|
|
$ yocto-kernel patch list myarm
|
|
The current set of machine-specific patches for myarm is:
|
|
1) yocto-testmod.patch
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
In a completely similar way, you can use the <filename>yocto-kernel config add</filename>
|
|
sub-command to add one or more kernel config item settings to a BSP.
|
|
The following commands add a couple of config items to the
|
|
<filename>myarm</filename> BSP:
|
|
<literallayout class='monospaced'>
|
|
$ yocto-kernel config add myarm CONFIG_MISC_DEVICES=y
|
|
Added items:
|
|
CONFIG_MISC_DEVICES=y
|
|
|
|
$ yocto-kernel config add myarm KCONFIG_YOCTO_TESTMOD=y
|
|
Added items:
|
|
CONFIG_YOCTO_TESTMOD=y
|
|
</literallayout>
|
|
<note>Although the previous example adds config items one at a time, it is possible
|
|
to add multiple config items at the same time.</note>
|
|
</para>
|
|
|
|
<para>
|
|
You can list the config items now associated with the BSP.
|
|
Doing so shows you the config items you added as well as others associated
|
|
with the BSP:
|
|
<literallayout class='monospaced'>
|
|
$ yocto-kernel config list myarm
|
|
The current set of machine-specific kernel config items for myarm is:
|
|
1) CONFIG_MISC_DEVICES=y
|
|
2) CONFIG_YOCTO_TESTMOD=y
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
Finally, you can remove one or more config items using the
|
|
<filename>yocto-kernel config rm</filename> sub-command in a manner
|
|
completely analogous to <filename>yocto-kernel patch rm</filename>.
|
|
</para>
|
|
</section>
|
|
</section>
|
|
</chapter>
|