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documentation/dev-manual/dev-manual-bsp-appendix.xml: removed redundancies

Browse Source 
Some of the more general BSP development information was more appropriate
in the dev-manual-cases chapter.  I removed this information and left
example-specific (mostly) text.

(From yocto-docs rev: d44c0fa8bdea9a2cad51ae3ca4b861a12d9fcdf9)

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
2011-07-27 11:50:26 -07:00
committed by Richard Purdie
parent 5b8301a3b8
commit fd02be8686
1 changed files with 11 additions and 139 deletions
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150
documentation/dev-manual/dev-manual-bsp-appendix.xml
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@@ -54,29 +54,15 @@
<title>Choosing a Base BSP</title>
<para>
The Yocto Project ships with several BSPs that support various hardware.
It is best to base your new BSP on an existing BSP rather than create all the
recipes and configuration files from scratch.
While it is possible to create everything from scratch, basing your new BSP
on something that is close is much easier.
Or, at a minimum, it gives you some structure with which to start.
For this example, the base BSP is the Intel Atom Processor E660 with Intel Platform
Controller Hub EG20T Development Kit, which is otherwise referred to as "Crown Bay."
The BSP layer is <filename>meta-crownbay</filename>.
</para>
<para>
At this point you need to understand your target hardware well enough to determine which
existing BSP it most closely matches.
Things to consider are your hardware’s on-board features such as CPU type and graphics support.
You should look at the README files for supported BSPs to get an idea of which one
you could use.
A generic Atom-based BSP to consider is the Crown Bay that does not support
the Intel® Embedded Media Graphics Driver (EMGD).
The remainder of this example uses that base BSP.
</para>
<para>
To see the supported BSPs, go to the Yocto Project
<ulink url='http://www.yoctoproject.org/download'>download page</ulink> and click
on “BSP Downloads.”
For information on how to choose a base BSP, see
<xref linkend='developing-a-board-support-package-bsp'>Developing a Board Support Package (BSP)</xref>
earlier in this manual.
</para>
</section>
@@ -90,7 +76,7 @@
download the BSP tarball and extract it, or set up a local Git repository that
has the Yocto Project BSP layers.
You should use the same method that you used to get the local Yocto Project files earlier.
See the <xref linkend='getting-setup'>Getting Setup</xref> earlier in this manual
See <xref linkend='getting-setup'>Getting Setup</xref> earlier in this manual
for information on how to get the BSP files.
</para>
@@ -119,48 +105,11 @@
<para>
Now that you have the local Yocto Project files and the base BSP files you need to create a
new layer for your BSP.
</para>
<para>
Layers are ideal for isolating and storing work for a given piece of hardware.
A layer is really just a location or area in which you place the recipes for your BSP.
In fact, a BSP is, in itself, a special type of layer.
Consider an application as another example that illustrates a layer.
Suppose you are creating an application that has library or other dependencies in
order for it to compile and run.
The layer, in this case, would be where all the recipes that define those dependencies
are kept. The key point for a layer is that it is an isolated area that contains
all the relevant information for the project that the Yocto Project build system knows about.
</para>
<note>
The Yocto Project supports four BSPs that are part of the
Yocto Project release: <filename>atom-pc</filename>, <filename>beagleboard</filename>,
<filename>mpc8315e</filename>, and <filename>routerstationpro</filename>.
The recipes and configurations for these four BSPs are located and dispersed
within local Yocto Project files.
Consequently, they are not totally isolated in the spirit of layers unless you think
of <filename>meta-yocto</filename> as a layer itself.
On the other hand, BSP layers for Crown Bay, Emenlow, Jasper Forest,
N450, and Sugar Bay are isolated.
</note>
<para>
When you set up a layer for a new BSP you should follow a standard layout.
This layout is described in the
<ulink url='http://www.yoctoproject.org/docs/1.1/bsp-guide/bsp-guide.html#bsp-filelayout'>
Example Filesystem Layout</ulink> section of the Board Support Package (BSP) Development
Guide.
In the standard layout you will notice a suggested structure for recipes and
configuration information.
You can see the standard layout for the Crown Bay BSP in this example by examining the
directory structure of the <filename>meta-crownbay</filename> layer inside the
local Yocto Project files.
</para>
<para>
To create your BSP layer you simply copy the <filename>meta-crownbay</filename>
layer to a new layer.
layer to a new layer.
</para>
<para>
For this example the new layer will be named <filename>meta-mymachine</filename>.
The name must follow the BSP layer naming convention, which is
<filename>meta-&lt;name&gt;</filename>.
@@ -485,22 +434,6 @@
<section id='preparing-for-the-build-app'>
<title>Preparing for the Build</title>
<para>
Once you have made all the changes to your BSP layer there remains a few things
you need to do for the Yocto Project build system in order for it to create your image.
You need to get the build environment ready by sourcing an environment setup script
and you need to be sure two key configuration files are configured appropriately.
</para>
<para>
The entire process for building an image is overviewed in the
<ulink url='http://www.yoctoproject.org/docs/1.1/yocto-project-qs/yocto-project-qs.html#building-image'>
Building an Image</ulink> section of the Yocto Project Quick Start.
You might want to reference this information.
The remainder of this section will apply to our example of the
<filename>meta-mymachine</filename> layer.
</para>
<para>
To get ready to build your image that uses the new layer you need to do the following:
<orderedlist>
@@ -559,67 +492,6 @@
<section id='building-the-image-app'>
<title>Building the Image</title>
<para>
The Yocto Project uses the BitBake tool to build images based on the type of image
you want to create.
You can find more information on BitBake
<ulink url='http://bitbake.berlios.de/manual/'>here</ulink>.
</para>
<para>
The build process supports several types of images to satisfy different needs.
When you issue the BitBake command you provide a “top-level” recipe that essentially
starts the process off of building the type of image you want.
</para>
<para>
[WRITER'S NOTE: Consider moving this to the Poky Reference Manual.]
</para>
<para>
You can find these recipes in the <filename>meta/recipes-core/images</filename> and
<filename>meta/recipes-sato/images</filename> directories of your local Yocto Project
file structure (Git repository or extracted release tarball).
Although the recipe names are somewhat explanatory, here is a list that describes them:
<itemizedlist>
<listitem><para><emphasis>Base</emphasis> – A foundational basic image without support
for X that can be reasonably used for customization.</para></listitem>
<listitem><para><emphasis>Core</emphasis> – A foundational basic image with support for
X that can be reasonably used for customization.</para></listitem>
<listitem><para><emphasis>Direct Disk</emphasis> – An image that you can copy directory to
the disk of the target device.</para></listitem>
<listitem><para><emphasis>Live</emphasis> – An image you can run from a USB device or from
a CD without having to first install something.</para></listitem>
<listitem><para><emphasis>Minimal</emphasis> – A small image without a GUI.
This image is not much more than a kernel with a shell.</para></listitem>
<listitem><para><emphasis>Minimal Development</emphasis> – A Minimal image suitable for
development work.</para></listitem>
<listitem><para><emphasis>Minimal Direct Disk</emphasis> – A Minimal Direct Disk image.</para></listitem>
<listitem><para><emphasis>Minimal RAM-based Initial Root Filesystem</emphasis> – A minimal image
that has the <filename>initramfs</filename> as part of the kernel, which allows the
system to find the first “init” program more efficiently.</para></listitem>
<listitem><para><emphasis>Minimal Live</emphasis> – A Minimal Live image.</para></listitem>
<listitem><para><emphasis>Minimal MTD Utilities</emphasis> – A minimal image that has support
for the MTD utilities, which let the user interact with the MTD subsystem in
the kernel to perform operations on flash devices.</para></listitem>
<listitem><para><emphasis>Sato</emphasis> – An image with Sato support, a mobile environment
and visual style that works well with mobile devices.</para></listitem>
<listitem><para><emphasis>Sato Development</emphasis> – A Sato image suitable for
development work.</para></listitem>
<listitem><para><emphasis>Sato Direct Disk</emphasis> – A Sato Direct Disk image.</para></listitem>
<listitem><para><emphasis>Sato Live</emphasis> – A Sato Live image.</para></listitem>
<listitem><para><emphasis>Sato SDK</emphasis> – A Sato image that includes the Yocto Project
toolchain and development libraries.</para></listitem>
<listitem><para><emphasis>Sato SDK Direct Disk</emphasis> – A Sato SDK Direct
Disk image.</para></listitem>
<listitem><para><emphasis>Sato SDK Live</emphasis> – A Sato SDK Live image.</para></listitem>
</itemizedlist>
</para>
<para>
The remainder of this section applies to our example of the <filename>meta-mymachine</filename> layer.
</para>
<para>
To build the image for our <filename>meta-mymachine</filename> BSP enter the following command
from the same shell from which you ran the setup script.