configuration files.
These example files are used as a basis for creating actual
configuration files when you source the build environment
- script
+ script
(i.e.
<link linkend='structure-core-script'><filename>&OE_INIT_FILE;</filename></link>
or
<para>
Because the Poky repository is fundamentally an aggregation of
existing repositories, some users might be familiar with running
- the <filename>&OE_INIT_FILE;</filename> or
- <filename>oe-init-build-env-memres</filename> script in the context
+ the <filename>&OE_INIT_FILE;</filename> or
+ <filename>oe-init-build-env-memres</filename> script in the context
of separate OpenEmbedded-Core and BitBake repositories rather than a
single Poky repository.
This discussion assumes the script is executed from within a cloned
<para>
The following figure shows an expanded representation of the
Metadata, Machine Configuration, and Policy Configuration input
- (layers) boxes of the
+ (layers) boxes of the
<link linkend='general-yocto-environment-figure'>general Yocto Project Development Environment figure</link>:
</para>
<para>
In order for the OpenEmbedded build system to create an image or
any target, it must be able to access source files.
- The
+ The
<link linkend='general-yocto-environment-figure'>general Yocto Project Development Environment figure</link>
represents source files using the "Upstream Project Releases",
"Local Projects", and "SCMs (optional)" boxes.
When the OpenEmbedded build system generates an image or an SDK,
it gets the packages from a package feed area located in the
<ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
- The
+ The
<link linkend='general-yocto-environment-figure'>general Yocto Project Development Environment figure</link>
shows this package feeds area in the upper-right corner.
</para>
<title>Image Generation</title>
<para>
- Once packages are split and stored in the Package Feeds area,
- the OpenEmbedded build system uses BitBake to generate the
+ Once packages are split and stored in the Package Feeds area,
+ the OpenEmbedded build system uses BitBake to generate the
root filesystem image:
<imagedata fileref="figures/image-generation.png" align="center" width="6in" depth="7in" />
</para>
<para>
- The image generation process consists of several stages and
+ The image generation process consists of several stages and
depends on many variables.
The <filename>do_rootfs</filename> task uses these key variables
to help create the list of packages to actually install:
<itemizedlist>
<listitem><para><link linkend='var-IMAGE_INSTALL'><filename>IMAGE_INSTALL</filename></link>:
- Lists out the base set of packages to install from
- the Package Feeds area.</para></listitem>
+ Lists out the base set of packages to install from
+ the Package Feeds area.</para></listitem>
<listitem><para><link linkend='var-PACKAGE_EXCLUDE'><filename>PACKAGE_EXCLUDE</filename></link>:
Specifies packages that should not be installed.
- </para></listitem>
+ </para></listitem>
<listitem><para><link linkend='var-IMAGE_FEATURES'><filename>IMAGE_FEATURES</filename></link>:
- Specifies features to include in the image.
- These features map to additional packages for
+ Specifies features to include in the image.
+ Most of these features map to additional packages for
installation.</para></listitem>
<listitem><para><link linkend='var-PACKAGE_CLASSES'><filename>PACKAGE_CLASSES</filename></link>:
- Specifies the package manager to use and consequently
- helps determine where to locate packages within the
- Package Feeds area.</para></listitem>
+ Specifies the package backend to use and consequently
+ helps determine where to locate packages within the
+ Package Feeds area.</para></listitem>
<listitem><para><link linkend='var-IMAGE_LINGUAS'><filename>IMAGE_LINGUAS</filename></link>:
- Determines the language for which packages are being
- installed.</para></listitem>
+ Determines the language(s) for which additional
+ language support packages are installed.
+ </para></listitem>
</itemizedlist>
</para>
<para>
- Part of the image generation process includes compressing the
- root filesystem image.
- Compression is accomplished through several optimization
- routines designed to reduce the overall size of the image.
- </para>
-
- <para>
- The process runs as many post installation scripts as possible.
- Any scripts that cannot be run are run when the system is
- first booted.
+ The process runs all of the post installation scripts, and
+ any that fail to run on the build host will be run on the
+ target when the target system is first booted.
If you are using a read-only root filesystem, all the post
- installation scripts are run during the package installation
- phase since the root filesystem cannot be written into.
+ installation scripts must succeed during the package
+ installation phase since the root filesystem cannot be
+ written into.
</para>
<para>
- During the Prelink phase, optimization processes are run across
- the image.
- These processes include <filename>mklibs</filename> and
+ During Optimization, optimizing processes are run across
+ the image.
+ These processes include <filename>mklibs</filename> and
<filename>prelink</filename>.
- The <filename>mklibs</filename> optimizes the size of the
- libraries.
- The <filename>prelink</filename> process optimizes the dynamic
- linking of shared libraries to reduce start up time of the
+ The <filename>mklibs</filename> optimizes the size of the
+ libraries.
+ A <filename>prelink</filename> process optimizes the dynamic
+ linking of shared libraries to reduce start up time of the
executables.
- See the
- <link linkend='var-IMAGE_POSTPROCESS_COMMAND'><filename>IMAGE_POSTPROCESS_COMMAND</filename></link>
- and
- <link linkend='var-ROOTFS_POSTPROCESS_COMMAND'><filename>ROOTFS_POSTPROCESS_COMMAND</filename></link>
- variables for additional information.
+ </para>
+
+ <para>
+ Part of the image generation process includes compressing the
+ root filesystem image.
+ Compression is accomplished through several optimization
+ routines designed to reduce the overall size of the image.
</para>
<para>
After the root filesystem has been constructed, the image
- generation process turns everything into an image file or
- a set of image files.
- we need to turn into an image file or set of image files.
- The formats used for the root filesystem depend on the
+ generation process turns everything into an image file or
+ a set of image files.
+ The formats used for the root filesystem depend on the
<link linkend='var-IMAGE_FSTYPES'><filename>IMAGE_FSTYPES</filename></link>
variable.
</para>
<note>
The entire image generation process is run under Pseudo.
- Running under Pseudo ensures that the files in the root
+ Running under Pseudo ensures that the files in the root
filesystem have correct ownership.
</note>
</section>
The images produced by the OpenEmbedded build system
are compressed forms of the
root filesystems that are ready to boot on a target device.
- You can see from the
+ You can see from the
<link linkend='general-yocto-environment-figure'>general Yocto Project Development Environment figure</link>
that BitBake output in part consists of images.
This section is going to look more closely at this output:
<title>Application Development SDK</title>
<para>
- In the
+ In the
<link linkend='general-yocto-environment-figure'>general Yocto Project Development Environment figure</link>,
the output labeled "Application Development SDK" represents an
SDK.
projects / thirdparty / openembedded / openembedded-core-contrib.git / commitdiff
