<filename>do_package_write_ipk</filename> for IPK packages).
</para>
</section>
+
+ <section id='images-and-application-development-sdk'>
+ <title>Images and Application Development SDK</title>
+
+ <para>
+ The purpose of using the OpenEmbedded build system is to produce
+ an image or a Software Development Kit (SDK).
+ You can see from the main
+ <link linkend='a-closer-look-at-the-yocto-project-development-environment'>Yocto Project Development Environment</link>
+ figure that the output (shown in red) are images and SDKs.
+ This section is going to look more closely at this output:
+ <imagedata fileref="figures/images-sdk.png" align="center" width="5in" depth="4in" />
+ </para>
+
+ <section id='images-dev-environment'>
+ <title>Images</title>
+
+ <para>
+ The images produced by BitBake are compressed forms of the
+ root filesystems that are ready to boot on a target device.
+ You can see the
+ "<link linkend='ref-images'>Images</link>" chapter for a list
+ of example images that the Yocto Project provides.
+ </para>
+
+ <para>
+ Images are kept in the
+ <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>
+ inside the <filename>deploy/images</filename> folder as shown
+ in the figure.
+ This folder contains any files expected to be loaded on the
+ target device.
+ The
+ <link linkend='var-DEPLOY_DIR'><filename>DEPLOY_DIR</filename></link>
+ variable points to the <filename>deploy</filename> directory.
+ <itemizedlist>
+ <listitem><para><filename><image></filename>:
+ A <filename>*.bin</filename> image file.
+ The <link linkend='var-KERNEL_IMAGETYPE'><filename>KERNEL_IMAGETYPE</filename></link>
+ variable setting determines the naming scheme for the
+ image file.
+ Depending on that variable, the file could begin with
+ a variety of naming strings.
+ The <filename>deploy/images</filename> directory can
+ contain multiple image files.</para></listitem>
+ <listitem><para><filename><root-filesystem></filename>:
+ Root filesystems for the target device (e.g.
+ <filename>*.ext3</filename> or <filename>*.bz2</filename>
+ files).
+ The <link linkend='var-IMAGE_FSTYPES'><filename>IMAGE_FSTYPES</filename></link>
+ variable setting determines the root filesystem
+ type.
+ The <filename>deploy/images</filename> directory can
+ contain multiple root filesystems.</para></listitem>
+ <listitem><para><filename><kernel-modules></filename>:
+ Tarballs that contain all the modules used by the
+ kernel.
+ Kernel module tarballs exist for legacy purposes and
+ can be suppressed by setting the
+ <link linkend='var-MODULE_TARBALL_DEPLOY'><filename>MODULE_TARBALL_DEPLOY</filename></link>
+ variable to "0".
+ The <filename>deploy/images</filename> directory can
+ contain multiple kernel module tarballs.
+ </para></listitem>
+ <listitem><para><filename><bootloaders></filename>:
+ Bootloaders supporting the image.
+ The <filename>deploy/images</filename> directory can
+ contain multiple bootloaders.
+ </para></listitem>
+ <listitem><para><filename><symlinks></filename>:
+ The <filename>images/deploy</filename> folder contains
+ a symbolic link for each actual file in the folder.
+ Links exist for all types of files (i.e. images,
+ root filesystems, bootloaders, and kernel module
+ tarballs).
+ The link scheme for images is such that a single link
+ exists for the most recently built image.
+ In addition to that single image link, additional
+ links exist on a one-for-one basis that map to each
+ physical image file.</para></listitem>
+ </itemizedlist>
+ </para>
+ </section>
+
+ <section id='sdk-dev-environment'>
+ <title>Application Development SDK</title>
+
+ <para>
+ An Application Development SDK (referred to as an
+ "SDK installer" in this section) is a self-extracting SDK
+ installer file (<filename>*.sh</filename>) that, when run,
+ installs a cross-development toolchain, a set of libraries
+ and headers, and an SDK environment setup script.
+ Running this installer essentially sets up your
+ cross-development environment.
+ You can think of the cross-toolchains as the "host" part
+ because they run on the SDK machine.
+ You can think of the libraries and headers as the "target"
+ part because they are built for the target hardware.
+ The setup script is added so that you can initialize the
+ environment before using the tools.
+ </para>
+
+ <note>
+ <para>
+ The Yocto Project supports several methods by which you can
+ set up this cross-development environment.
+ These methods include downloading pre-built SDK installers,
+ building and installing your own SKD installer, or running
+ an Application Development Toolkit (ADT) installer to
+ install not just cross-development toolchains
+ but also additional tools to help in this type of
+ development.
+ </para>
+
+ <para>
+ For background information on cross-development toolchains
+ in the Yocto Project development environment, see the
+ "<link linkend='cross-development-toolchain-generation'>Cross-Development Toolchain Generation</link>"
+ section.
+ For information on setting up a cross-development
+ environment, see the
+ "<ulink url='&YOCTO_DOCS_ADT_URL;#installing-the-adt'>Installing the ADT and Toolchains</ulink>"
+ section in the Yocto Project Application Developer's Guide.
+ </para>
+ </note>
+
+ <para>
+ When built using BitBake, the SDK installers are kept in the
+ <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>
+ inside the <filename>deploy/sdk</filename> folder as shown
+ in the figure at the beginning of this section.
+ Several variables exist that help configure these files:
+ <itemizedlist>
+ <listitem><para><link linkend='var-DEPLOY_DIR'><filename>DEPLOY_DIR</filename></link>:
+ Points to the <filename>deploy</filename>
+ directory.</para></listitem>
+ <listitem><para><link linkend='var-SDKMACHINE'><filename>SDKMACHINE</filename></link>:
+ Specifies the architecture of the machine
+ on which the cross-development tools are run to
+ create packages for the target hardware.
+ </para></listitem>
+ <listitem><para><link linkend='var-SDKIMAGE_FEATURES'><filename>SDKIMAGE_FEATURES</filename></link>:
+ Lists the features to include in the libraries.
+ </para></listitem>
+ <listitem><para><link linkend='var-TOOLCHAIN_HOSTS_TASKS'><filename>TOOLCHAIN_HOSTS_TASKS</filename></link>:
+ Lists packages that make up the host
+ part of the SDK installer (i.e. the part that runs on
+ the <filename>SDKMACHINE</filename>).
+ When you use <filename>bitbake sdk_populate</filename>
+ to create the SDK installer, a set of default tasks
+ apply.
+ This variable allows you to add more tasks.
+ </para></listitem>
+ <listitem><para><link linkend='var-TOOLCHAIN_TARGET_TASKS'><filename>TOOLCHAIN_TARGET_TASKS</filename></link>:
+ Lists packages that make up the target part
+ of the SDK installer (i.e. the part built for the
+ target hardware).
+ </para></listitem>
+ </itemizedlist>
+ </para>
+ </section>
+ </section>
</section>
<section id="cross-development-toolchain-generation">
projects / thirdparty / openembedded / openembedded-core-contrib.git / commitdiff
