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+<!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='dev-manual-model'>
+
+<title>Common Development Models</title>
+
+<para>
+ Many development models exist for which you can use the Yocto Project.
+ This chapter overviews simple methods that use tools provided by the
+ Yocto Project:
+ <itemizedlist>
+ <listitem><para><emphasis>System Development:</emphasis>
+ System Development covers Board Support Package (BSP) development
+ and kernel modification or configuration.
+ For an example on how to create a BSP, see the
+ "<ulink url='&YOCTO_DOCS_BSP_URL;#creating-a-new-bsp-layer-using-the-yocto-bsp-script'>Creating a New BSP Layer Using the yocto-bsp Script</ulink>"
+ section in the Yocto Project Board Support Package (BSP)
+ Developer's Guide.
+ For more complete information on how to work with the kernel,
+ see the
+ <ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;'>Yocto Project Linux Kernel Development Manual</ulink>.
+ </para></listitem>
+ <listitem><para><emphasis>User Application Development:</emphasis>
+ User Application Development covers development of applications
+ that you intend to run on target hardware.
+ For information on how to set up your host development system for
+ user-space application development, see the
+ <ulink url='&YOCTO_DOCS_ADT_URL;'>Yocto Project Application Developer's Guide</ulink>.
+ For a simple example of user-space application development using
+ the <trademark class='trade'>Eclipse</trademark> IDE, see the
+ "<link linkend='application-development-workflow'>Application
+ Development Workflow</link>" section.
+ </para></listitem>
+ <listitem><para><emphasis>Temporary Source Code Modification:</emphasis>
+ Direct modification of temporary source code is a convenient
+ development model to quickly iterate and develop towards a
+ solution.
+ Once you implement the solution, you should of course take
+ steps to get the changes upstream and applied in the affected
+ recipes.
+ </para></listitem>
+ <listitem><para><emphasis>Image Development using Toaster:</emphasis>
+ You can use <ulink url='&YOCTO_HOME_URL;/Tools-resources/projects/toaster'>Toaster</ulink>
+ to build custom operating system images within the build
+ environment.
+ Toaster provides an efficient interface to the OpenEmbedded build
+ that allows you to start builds and examine build statistics.
+ </para></listitem>
+ <listitem><para><emphasis>Image Development using Hob:</emphasis>
+ You can use the <ulink url='&YOCTO_HOME_URL;/tools-resources/projects/hob'>Hob</ulink>
+ to build custom operating system images within the build
+ environment.
+ Hob provides an efficient interface to the OpenEmbedded build system.
+ </para></listitem>
+ <listitem><para><emphasis>Using a Development Shell:</emphasis>
+ You can use a <filename>devshell</filename> to efficiently debug
+ commands or simply edit packages.
+ Working inside a development shell is a quick way to set up the
+ OpenEmbedded build environment to work on parts of a project.
+ </para></listitem>
+ </itemizedlist>
+</para>
+
+<section id='system-development-model'>
+ <title>System Development Workflow</title>
+
+ <para>
+ System development involves modification or creation of an image that you want to run on
+ a specific hardware target.
+ Usually, when you want to create an image that runs on embedded hardware, the image does
+ not require the same number of features that a full-fledged Linux distribution provides.
+ Thus, you can create a much smaller image that is designed to use only the
+ features for your particular hardware.
+ </para>
+
+ <para>
+ To help you understand how system development works in the Yocto Project, this section
+ covers two types of image development: BSP creation and kernel modification or
+ configuration.
+ </para>
+
+ <section id='developing-a-board-support-package-bsp'>
+ <title>Developing a Board Support Package (BSP)</title>
+
+ <para>
+ A BSP is a collection of recipes that, when applied during a build, results in
+ an image that you can run on a particular board.
+ Thus, the package when compiled into the new image, supports the operation of the board.
+ </para>
+
+ <note>
+ For a brief list of terms used when describing the development process in the Yocto Project,
+ see the "<link linkend='yocto-project-terms'>Yocto Project Terms</link>" section.
+ </note>
+
+ <para>
+ The remainder of this section presents the basic
+ steps used to create a BSP using the Yocto Project's
+ <ulink url='&YOCTO_DOCS_BSP_URL;#using-the-yocto-projects-bsp-tools'>BSP Tools</ulink>.
+ Although not required for BSP creation, the
+ <filename>meta-intel</filename> repository, which contains
+ many BSPs supported by the Yocto Project, is part of the example.
+ </para>
+
+ <para>
+ For an example that shows how to create a new layer using the tools, see the
+ "<ulink url='&YOCTO_DOCS_BSP_URL;#creating-a-new-bsp-layer-using-the-yocto-bsp-script'>Creating a New BSP Layer Using the yocto-bsp Script</ulink>"
+ section in the Yocto Project Board Support Package (BSP) Developer's Guide.
+ </para>
+
+ <para>
+ The following illustration and list summarize the BSP creation general workflow.
+ </para>
+
+ <para>
+ <imagedata fileref="figures/bsp-dev-flow.png" width="6in" depth="7in" align="center" scalefit="1" />
+ </para>
+
+ <para>
+ <orderedlist>
+ <listitem><para><emphasis>Set up your host development system to support
+ development using the Yocto Project</emphasis>: See the
+ "<ulink url='&YOCTO_DOCS_QS_URL;#the-linux-distro'>The Linux Distribution</ulink>"
+ and the
+ "<ulink url='&YOCTO_DOCS_QS_URL;#packages'>The Build Host Packages</ulink>" sections both
+ in the Yocto Project Quick Start for requirements.</para></listitem>
+ <listitem><para><emphasis>Establish a local copy of the project files on your
+ system</emphasis>: You need this <link linkend='source-directory'>Source
+ Directory</link> available on your host system.
+ Having these files on your system gives you access to the build
+ process and to the tools you need.
+ For information on how to set up the Source Directory,
+ see the
+ "<link linkend='getting-setup'>Getting Set Up</link>" section.</para></listitem>
+ <listitem><para><emphasis>Establish the <filename>meta-intel</filename>
+ repository on your system</emphasis>: Having local copies
+ of these supported BSP layers on your system gives you
+ access to layers you might be able to build on or modify
+ to create your BSP.
+ For information on how to get these files, see the
+ "<link linkend='getting-setup'>Getting Set Up</link>" section.</para></listitem>
+ <listitem><para><emphasis>Create your own BSP layer using the
+ <ulink url='&YOCTO_DOCS_BSP_URL;#creating-a-new-bsp-layer-using-the-yocto-bsp-script'><filename>yocto-bsp</filename></ulink> script</emphasis>:
+ 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 and configurations for your BSP.
+ In fact, a BSP is, in itself, a special type of layer.
+ The simplest way to create a new BSP layer that is compliant with the
+ Yocto Project is to use the <filename>yocto-bsp</filename> script.
+ For information about that script, see the
+ "<ulink url='&YOCTO_DOCS_BSP_URL;#creating-a-new-bsp-layer-using-the-yocto-bsp-script'>Creating a New BSP Layer Using the yocto-bsp Script</ulink>"
+ section in the Yocto Project Board Support (BSP) Developer's Guide.
+ </para>
+ <para>
+ Another example that illustrates a layer is an application.
+ 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 OpenEmbedded build
+ system knows about.
+ For more information on layers, see the
+ "<link linkend='understanding-and-creating-layers'>Understanding and Creating Layers</link>"
+ section.
+ For more information on BSP layers, see the
+ "<ulink url='&YOCTO_DOCS_BSP_URL;#bsp-layers'>BSP Layers</ulink>" section in the
+ Yocto Project Board Support Package (BSP) Developer's Guide.</para>
+ <note>Five BSPs exist that are part of the
+ Yocto Project release: <filename>genericx86</filename>, <filename>genericx86-64</filename>,
+ <filename>beaglebone</filename> (ARM),
+ <filename>mpc8315e</filename> (PowerPC),
+ and <filename>edgerouter</filename> (MIPS).
+ The recipes and configurations for these five BSPs are located and dispersed
+ within the <link linkend='source-directory'>Source Directory</link>.
+ On the other hand, the <filename>meta-intel</filename> layer
+ contains BSP layers for many supported BSPs (e.g.
+ Crystal Forest, Emenlow, Fish River Island 2, Haswell,
+ Jasper Forest, and so forth).
+ Aside from the BSPs in the <filename>meta-intel</filename>
+ layer, the
+ <ulink url='&YOCTO_GIT_URL;'>Source Repositories</ulink>
+ contain additional BSP layers such as
+ <filename>meta-minnow</filename> and
+ <filename>meta-raspberrypi</filename>.</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='&YOCTO_DOCS_BSP_URL;#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 a BSP by examining
+ any supported BSP found in the <filename>meta-intel</filename> layer inside
+ the Source Directory.</para></listitem>
+ <listitem><para><emphasis>Make configuration changes to your new BSP
+ layer</emphasis>: The standard BSP layer structure organizes the files you need
+ to edit in <filename>conf</filename> and several <filename>recipes-*</filename>
+ directories within the BSP layer.
+ Configuration changes identify where your new layer is on the local system
+ and identify which kernel you are going to use.
+ When you run the <filename>yocto-bsp</filename> script, you are able to interactively
+ configure many things for the BSP (e.g. keyboard, touchscreen, and so forth).
+ </para></listitem>
+ <listitem><para><emphasis>Make recipe changes to your new BSP layer</emphasis>: Recipe
+ changes include altering recipes (<filename>.bb</filename> files), removing
+ recipes you do not use, and adding new recipes or append files
+ (<filename>.bbappend</filename>) that you need to support your hardware.
+ </para></listitem>
+ <listitem><para><emphasis>Prepare for the build</emphasis>: Once you have made all the
+ changes to your BSP layer, there remains a few things
+ you need to do for the OpenEmbedded build system in order for it to create your image.
+ You need to get the build environment ready by sourcing an environment setup script
+ (i.e. <filename>oe-init-build-env</filename> or
+ <filename>oe-init-build-env-memres</filename>)
+ and you need to be sure two key configuration files are configured appropriately:
+ the <filename>conf/local.conf</filename> and the
+ <filename>conf/bblayers.conf</filename> file.
+ You must make the OpenEmbedded build system aware of your new layer.
+ See the
+ "<link linkend='enabling-your-layer'>Enabling Your Layer</link>" section
+ for information on how to let the build system know about your new layer.</para>
+ <para>The entire process for building an image is overviewed in the section
+ "<ulink url='&YOCTO_DOCS_QS_URL;#qs-building-images'>Building Images</ulink>" section
+ of the Yocto Project Quick Start.
+ You might want to reference this information.</para></listitem>
+ <listitem><para><emphasis>Build the image</emphasis>: The OpenEmbedded build system
+ uses the BitBake tool to build images based on the type of image you want to create.
+ You can find more information about BitBake in the
+ <ulink url='&YOCTO_DOCS_BB_URL;'>BitBake User Manual</ulink>.
+ </para>
+ <para>The build process supports several types of images to satisfy different needs.
+ See the
+ "<ulink url='&YOCTO_DOCS_REF_URL;#ref-images'>Images</ulink>" chapter
+ in the Yocto Project Reference Manual for information on
+ supported images.</para></listitem>
+ </orderedlist>
+ </para>
+
+ <para>
+ You can view a video presentation on "Building Custom Embedded Images with Yocto"
+ at <ulink url='http://free-electrons.com/blog/elc-2011-videos'>Free Electrons</ulink>.
+ After going to the page, just search for "Embedded".
+ You can also find supplemental information in the
+ <ulink url='&YOCTO_DOCS_BSP_URL;'>
+ Yocto Project Board Support Package (BSP) Developer's Guide</ulink>.
+ Finally, there is helpful material and links on this
+ <ulink url='&YOCTO_WIKI_URL;/wiki/Transcript:_creating_one_generic_Atom_BSP_from_another'>wiki page</ulink>.
+ Although a bit dated, you might find the information on the wiki
+ helpful.
+ </para>
+ </section>
+
+ <section id='modifying-the-kernel'>
+ <title><anchor id='kernel-spot' />Modifying the Kernel</title>
+
+ <para>
+ Kernel modification involves changing the Yocto Project kernel, which could involve changing
+ configuration options as well as adding new kernel recipes.
+ Configuration changes can be added in the form of configuration fragments, while recipe
+ modification comes through the kernel's <filename>recipes-kernel</filename> area
+ in a kernel layer you create.
+ </para>
+
+ <para>
+ The remainder of this section presents a high-level overview of the Yocto Project
+ kernel architecture and the steps to modify the kernel.
+ You can reference the
+ "<link linkend='patching-the-kernel'>Patching the Kernel</link>" section
+ for an example that changes the source code of the kernel.
+ For information on how to configure the kernel, see the
+ "<link linkend='configuring-the-kernel'>Configuring the Kernel</link>" section.
+ For more information on the kernel and on modifying the kernel, see the
+ <ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;'>Yocto Project Linux Kernel Development Manual</ulink>.
+ </para>
+
+ <section id='kernel-overview'>
+ <title>Kernel Overview</title>
+
+ <para>
+ Traditionally, when one thinks of a patched kernel, they think of a base kernel
+ source tree and a fixed structure that contains kernel patches.
+ The Yocto Project, however, employs mechanisms that, in a sense, result in a kernel source
+ generator.
+ By the end of this section, this analogy will become clearer.
+ </para>
+
+ <para>
+ You can find a web interface to the Yocto Project kernel source repositories at
+ <ulink url='&YOCTO_GIT_URL;'></ulink>.
+ If you look at the interface, you will see to the left a grouping of
+ Git repositories titled "Yocto Linux Kernel."
+ Within this group, you will find several kernels supported by
+ the Yocto Project:
+ <itemizedlist>
+ <listitem><para><emphasis>
+ <filename>linux-yocto-3.8</filename></emphasis> - The
+ stable Yocto Project kernel to use with the Yocto
+ Project Release 1.4. This kernel is based on the
+ Linux 3.8 released kernel.
+ </para></listitem>
+ <listitem><para><emphasis>
+ <filename>linux-yocto-3.10</filename></emphasis> - An
+ additional, unsupported Yocto Project kernel used with
+ the Yocto Project Release 1.5.
+ This kernel is based on the Linux 3.10 released kernel.
+ </para></listitem>
+ <listitem><para><emphasis>
+ <filename>linux-yocto-3.14</filename></emphasis> - The
+ stable Yocto Project kernel to use with the Yocto
+ Project Releases 1.6 and 1.7.
+ This kernel is based on the Linux 3.14 released kernel.
+ </para></listitem>
+ <listitem><para><emphasis>
+ <filename>linux-yocto-3.17</filename></emphasis> - An
+ additional, unsupported Yocto Project kernel used with
+ the Yocto Project Release 1.7.
+ This kernel is based on the Linux 3.17 released kernel.
+ </para></listitem>
+ <listitem><para><emphasis>
+ <filename>linux-yocto-3.19</filename></emphasis> - The
+ stable Yocto Project kernel to use with the Yocto
+ Project Release 1.8.
+ This kernel is based on the Linux 3.19 released kernel.
+ </para></listitem>
+ <listitem><para><emphasis>
+ <filename>linux-yocto-dev</filename></emphasis> - A
+ development kernel based on the latest upstream release
+ candidate available.
+ </para></listitem>
+ </itemizedlist>
+ </para>
+
+ <para>
+ The kernels are maintained using the Git revision control system
+ that structures them using the familiar "tree", "branch", and "leaf" scheme.
+ Branches represent diversions from general code to more specific code, while leaves
+ represent the end-points for a complete and unique kernel whose source files,
+ when gathered from the root of the tree to the leaf, accumulate to create the files
+ necessary for a specific piece of hardware and its features.
+ The following figure displays this concept:
+ <para>
+ <imagedata fileref="figures/kernel-overview-1.png"
+ width="6in" depth="6in" align="center" scale="100" />
+ </para>
+
+ <para>
+ Within the figure, the "Kernel.org Branch Point" represents the point in the tree
+ where a supported base kernel is modified from the Linux kernel.
+ For example, this could be the branch point for the <filename>linux-yocto-3.19</filename>
+ kernel.
+ Thus, everything further to the right in the structure is based on the
+ <filename>linux-yocto-3.19</filename> kernel.
+ Branch points to the right in the figure represent where the
+ <filename>linux-yocto-3.19</filename> kernel is modified for specific hardware
+ or types of kernels, such as real-time kernels.
+ Each leaf thus represents the end-point for a kernel designed to run on a specific
+ targeted device.
+ </para>
+
+ <para>
+ The overall result is a Git-maintained repository from which all the supported
+ kernel types can be derived for all the supported devices.
+ A big advantage to this scheme is the sharing of common features by keeping them in
+ "larger" branches within the tree.
+ This practice eliminates redundant storage of similar features shared among kernels.
+ </para>
+
+ <note>
+ Keep in mind the figure does not take into account all the supported Yocto
+ Project kernel types, but rather shows a single generic kernel just for conceptual purposes.
+ Also keep in mind that this structure represents the Yocto Project source repositories
+ that are either pulled from during the build or established on the host development system
+ prior to the build by either cloning a particular kernel's Git repository or by
+ downloading and unpacking a tarball.
+ </note>
+
+ <para>
+ Upstream storage of all the available kernel source code is one thing, while
+ representing and using the code on your host development system is another.
+ Conceptually, you can think of the kernel source repositories as all the
+ source files necessary for all the supported kernels.
+ As a developer, you are just interested in the source files for the kernel on
+ which you are working.
+ And, furthermore, you need them available on your host system.
+ </para>
+
+ <para>
+ Kernel source code is available on your host system a couple of different
+ ways.
+ If you are working in the kernel all the time, you probably would want
+ to set up your own local Git repository of the kernel tree.
+ If you just need to make some patches to the kernel, you can access
+ temporary kernel source files that were extracted and used
+ during a build.
+ We will just talk about working with the temporary source code.
+ For more information on how to get kernel source code onto your
+ host system, see the
+ "<link linkend='local-kernel-files'>Yocto Project Kernel</link>"
+ bulleted item earlier in the manual.
+ </para>
+
+ <para>
+ What happens during the build?
+ When you build the kernel on your development system, all files needed for the build
+ are taken from the source repositories pointed to by the
+ <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink> variable
+ and gathered in a temporary work area
+ where they are subsequently used to create the unique kernel.
+ Thus, in a sense, the process constructs a local source tree specific to your
+ kernel to generate the new kernel image - a source generator if you will.
+ </para>
+ The following figure shows the temporary file structure
+ created on your host system when the build occurs.
+ This
+ <link linkend='build-directory'>Build Directory</link> contains all the
+ source files used during the build.
+ </para>
+
+ <para>
+ <imagedata fileref="figures/kernel-overview-2-generic.png"
+ width="6in" depth="5in" align="center" scale="100" />
+ </para>
+
+ <para>
+ Again, for additional information on the Yocto Project kernel's
+ architecture and its branching strategy, see the
+ <ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;'>Yocto Project Linux Kernel Development Manual</ulink>.
+ You can also reference the
+ "<link linkend='patching-the-kernel'>Patching the Kernel</link>"
+ section for a detailed example that modifies the kernel.
+ </para>
+ </section>
+
+ <section id='kernel-modification-workflow'>
+ <title>Kernel Modification Workflow</title>
+
+ <para>
+ This illustration and the following list summarizes the kernel modification general workflow.
+ </para>
+
+ <para>
+ <imagedata fileref="figures/kernel-dev-flow.png"
+ width="6in" depth="5in" align="center" scalefit="1" />
+ </para>
+
+ <para>
+ <orderedlist>
+ <listitem><para><emphasis>Set up your host development system to support
+ development using the Yocto Project</emphasis>: See
+ "<ulink url='&YOCTO_DOCS_QS_URL;#the-linux-distro'>The Linux Distribution</ulink>" and
+ "<ulink url='&YOCTO_DOCS_QS_URL;#packages'>The Build Host Packages</ulink>" sections both
+ in the Yocto Project Quick Start for requirements.</para></listitem>
+ <listitem><para><emphasis>Establish a local copy of project files on your
+ system</emphasis>: Having the <link linkend='source-directory'>Source
+ Directory</link> on your system gives you access to the build process and tools
+ you need.
+ For information on how to get these files, see the bulleted item
+ "<link linkend='local-yp-release'>Yocto Project Release</link>" earlier in this manual.
+ </para></listitem>
+ <listitem><para><emphasis>Establish the temporary kernel source files</emphasis>:
+ Temporary kernel source files are kept in the
+ <link linkend='build-directory'>Build Directory</link>
+ created by the
+ OpenEmbedded build system when you run BitBake.
+ If you have never built the kernel in which you are
+ interested, you need to run an initial build to
+ establish local kernel source files.</para>
+ <para>If you are building an image for the first time, you need to get the build
+ environment ready by sourcing an environment setup script
+ (i.e. <filename>oe-init-build-env</filename> or
+ <filename>oe-init-build-env-memres</filename>).
+ You also need to be sure two key configuration files
+ (<filename>local.conf</filename> and <filename>bblayers.conf</filename>)
+ are configured appropriately.</para>
+ <para>The entire process for building an image is overviewed in the
+ "<ulink url='&YOCTO_DOCS_QS_URL;#qs-building-images'>Building Images</ulink>"
+ section of the Yocto Project Quick Start.
+ You might want to reference this information.
+ You can find more information on BitBake in the
+ <ulink url='&YOCTO_DOCS_BB_URL;'>BitBake User Manual</ulink>.
+ </para>
+ <para>The build process supports several types of images to satisfy different needs.
+ See the "<ulink url='&YOCTO_DOCS_REF_URL;#ref-images'>Images</ulink>" chapter in
+ the Yocto Project Reference Manual for information on supported images.
+ </para></listitem>
+ <listitem><para><emphasis>Make changes to the kernel source code if
+ applicable</emphasis>: Modifying the kernel does not always mean directly
+ changing source files.
+ However, if you have to do this, you make the changes to the files in the
+ Build Directory.</para></listitem>
+ <listitem><para><emphasis>Make kernel configuration changes if applicable</emphasis>:
+ If your situation calls for changing the kernel's
+ configuration, you can use
+ <ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#generating-configuration-files'><filename>menuconfig</filename></ulink>,
+ which allows you to interactively develop and test the
+ configuration changes you are making to the kernel.
+ Saving changes you make with
+ <filename>menuconfig</filename> updates
+ the kernel's <filename>.config</filename> file.
+ <note><title>Warning</title>
+ Try to resist the temptation to directly edit an
+ existing <filename>.config</filename> file, which is
+ found in the Build Directory at
+ <filename>tmp/sysroots/<replaceable>machine-name</replaceable>/kernel</filename>.
+ Doing so, can produce unexpected results when the
+ OpenEmbedded build system regenerates the configuration
+ file.
+ </note>
+ Once you are satisfied with the configuration
+ changes made using <filename>menuconfig</filename>
+ and you have saved them, you can directly compare the
+ resulting <filename>.config</filename> file against an
+ existing original and gather those changes into a
+ <link linkend='creating-config-fragments'>configuration fragment file</link>
+ to be referenced from within the kernel's
+ <filename>.bbappend</filename> file.</para>
+
+ <para>Additionally, if you are working in a BSP layer
+ and need to modify the BSP's kernel's configuration,
+ you can use the
+ <ulink url='&YOCTO_DOCS_BSP_URL;#managing-kernel-patches-and-config-items-with-yocto-kernel'><filename>yocto-kernel</filename></ulink>
+ script as well as <filename>menuconfig</filename>.
+ The <filename>yocto-kernel</filename> script lets
+ you interactively set up kernel configurations.
+ </para></listitem>
+ <listitem><para><emphasis>Rebuild the kernel image with your changes</emphasis>:
+ Rebuilding the kernel image applies your changes.
+ </para></listitem>
+ </orderedlist>
+ </para>
+ </section>
+ </section>
+</section>
+
+<section id='application-development-workflow'>
+ <title>Application Development Workflow</title>
+
+ <para>
+ Application development involves creating an application that you want
+ to run on your target hardware, which is running a kernel image created using the
+ OpenEmbedded build system.
+ The Yocto Project provides an
+ <ulink url='&YOCTO_DOCS_ADT_URL;#adt-intro'>Application Development Toolkit (ADT)</ulink>
+ and stand-alone
+ <ulink url='&YOCTO_DOCS_ADT_URL;#the-cross-development-toolchain'>cross-development toolchains</ulink>
+ that facilitate quick development and integration of your application into its runtime environment.
+ Using the ADT and toolchains, you can compile and link your application.
+ You can then deploy your application to the actual hardware or to the QEMU emulator for testing.
+ If you are familiar with the popular <trademark class='trade'>Eclipse</trademark> IDE,
+ you can use an Eclipse Yocto Plug-in to
+ allow you to develop, deploy, and test your application all from within Eclipse.
+ </para>
+
+ <para>
+ While we strongly suggest using the ADT to develop your application, this option might not
+ be best for you.
+ If this is the case, you can still use pieces of the Yocto Project for your development process.
+ However, because the process can vary greatly, this manual does not provide detail on the process.
+ </para>
+
+ <section id='workflow-using-the-adt-and-eclipse'>
+ <title>Workflow Using the ADT and <trademark class='trade'>Eclipse</trademark></title>
+
+ <para>
+ To help you understand how application development works using the ADT, this section
+ provides an overview of the general development process and a detailed example of the process
+ as it is used from within the Eclipse IDE.
+ </para>
+
+ <para>
+ The following illustration and list summarize the application development general workflow.
+ </para>
+
+ <para>
+ <imagedata fileref="figures/app-dev-flow.png"
+ width="7in" depth="8in" align="center" scale="100" />
+ </para>
+
+ <para>
+ <orderedlist>
+ <listitem><para><emphasis>Prepare the host system for the Yocto Project</emphasis>:
+ See
+ "<ulink url='&YOCTO_DOCS_REF_URL;#detailed-supported-distros'>Supported Linux Distributions</ulink>"
+ and
+ "<ulink url='&YOCTO_DOCS_REF_URL;#required-packages-for-the-host-development-system'>Required Packages for the Host Development System</ulink>" sections both
+ in the Yocto Project Reference Manual for requirements.
+ In particular, be sure your host system has the
+ <filename>xterm</filename> package installed.
+ </para></listitem>
+ <listitem><para><emphasis>Secure the Yocto Project kernel target image</emphasis>:
+ You must have a target kernel image that has been built using the OpenEmbedded
+ build system.</para>
+ <para>Depending on whether the Yocto Project has a pre-built image that matches your target
+ architecture and where you are going to run the image while you develop your application
+ (QEMU or real hardware), the area from which you get the image differs.
+ <itemizedlist>
+ <listitem><para>Download the image from
+ <ulink url='&YOCTO_MACHINES_DL_URL;'><filename>machines</filename></ulink>
+ if your target architecture is supported and you are going to develop
+ and test your application on actual hardware.</para></listitem>
+ <listitem><para>Download the image from
+ <ulink url='&YOCTO_QEMU_DL_URL;'>
+ <filename>machines/qemu</filename></ulink> if your target architecture is supported
+ and you are going to develop and test your application using the QEMU
+ emulator.</para></listitem>
+ <listitem><para>Build your image if you cannot find a pre-built image that matches
+ your target architecture.
+ If your target architecture is similar to a supported architecture, you can
+ modify the kernel image before you build it.
+ See the
+ "<link linkend='patching-the-kernel'>Patching the Kernel</link>"
+ section for an example.</para></listitem>
+ </itemizedlist></para>
+ <para>For information on pre-built kernel image naming schemes for images
+ that can run on the QEMU emulator, see the
+ "<ulink url='&YOCTO_DOCS_QS_URL;#downloading-the-pre-built-linux-kernel'>Downloading the Pre-Built Linux Kernel</ulink>"
+ section in the Yocto Project Application Developer's Guide.</para></listitem>
+ <listitem><para><emphasis>Install the ADT</emphasis>:
+ The ADT provides a target-specific cross-development toolchain, the root filesystem,
+ the QEMU emulator, and other tools that can help you develop your application.
+ While it is possible to get these pieces separately, the ADT Installer provides an
+ easy, inclusive method.
+ You can get these pieces by running an ADT installer script, which is configurable.
+ For information on how to install the ADT, see the
+ "<ulink url='&YOCTO_DOCS_ADT_URL;#using-the-adt-installer'>Using the ADT Installer</ulink>"
+ section
+ in the Yocto Project Application Developer's Guide.</para></listitem>
+ <listitem><para><emphasis>If applicable, secure the target root filesystem
+ and the Cross-development toolchain</emphasis>:
+ If you choose not to install the ADT using the ADT Installer,
+ you need to find and download the appropriate root filesystem and
+ the cross-development toolchain.</para>
+ <para>You can find the tarballs for the root filesystem in the same area used
+ for the kernel image.
+ Depending on the type of image you are running, the root filesystem you need differs.
+ For example, if you are developing an application that runs on an image that
+ supports Sato, you need to get a root filesystem that supports Sato.</para>
+ <para>You can find the cross-development toolchains at
+ <ulink url='&YOCTO_TOOLCHAIN_DL_URL;'><filename>toolchains</filename></ulink>.
+ Be sure to get the correct toolchain for your development host and your
+ target architecture.
+ See the "<ulink url='&YOCTO_DOCS_ADT_URL;#using-an-existing-toolchain-tarball'>Using a Cross-Toolchain Tarball</ulink>"
+ section in the Yocto Project Application Developer's Guide for information
+ and the
+ "<ulink url='&YOCTO_DOCS_QS_URL;#installing-the-toolchain'>Installing the Toolchain</ulink>"
+ in the Yocto Project Application Developer's Guide for information on finding and installing
+ the correct toolchain based on your host development system and your target
+ architecture.
+ </para></listitem>
+ <listitem><para><emphasis>Create and build your application</emphasis>:
+ At this point, you need to have source files for your application.
+ Once you have the files, you can use the Eclipse IDE to import them and build the
+ project.
+ If you are not using Eclipse, you need to use the cross-development tools you have
+ installed to create the image.</para></listitem>
+ <listitem><para><emphasis>Deploy the image with the application</emphasis>:
+ If you are using the Eclipse IDE, you can deploy your image to the hardware or to
+ QEMU through the project's preferences.
+ If you are not using the Eclipse IDE, then you need to deploy the application
+ to the hardware using other methods.
+ Or, if you are using QEMU, you need to use that tool and
+ load your image in for testing.
+ See the
+ "<link linkend='dev-manual-qemu'>Using the Quick EMUlator (QEMU)</link>"
+ chapter for information on using QEMU.
+ </para></listitem>
+ <listitem><para><emphasis>Test and debug the application</emphasis>:
+ Once your application is deployed, you need to test it.
+ Within the Eclipse IDE, you can use the debugging environment along with the
+ set of user-space tools installed along with the ADT to debug your application.
+ Of course, the same user-space tools are available separately if you choose
+ not to use the Eclipse IDE.</para></listitem>
+ </orderedlist>
+ </para>
+ </section>
+
+ <section id='adt-eclipse'>
+ <title>Working Within Eclipse</title>
+
+ <para>
+ The Eclipse IDE is a popular development environment and it fully
+ supports development using the Yocto Project.
+ <note>
+ This release of the Yocto Project supports both the Luna
+ and Kepler versions of the Eclipse IDE.
+ Thus, the following information provides setup information for
+ both versions.
+ </note>
+ </para>
+
+ <para>
+ When you install and configure the Eclipse Yocto Project Plug-in
+ into the Eclipse IDE, you maximize your Yocto Project experience.
+ Installing and configuring the Plug-in results in an environment
+ that has extensions specifically designed to let you more easily
+ develop software.
+ These extensions allow for cross-compilation, deployment, and
+ execution of your output into a QEMU emulation session as well as
+ actual target hardware.
+ You can also perform cross-debugging and profiling.
+ The environment also supports a suite of tools that allows you
+ to perform remote profiling, tracing, collection of power data,
+ collection of latency data, and collection of performance data.
+ </para>
+
+ <para>
+ This section describes how to install and configure the Eclipse IDE
+ Yocto Plug-in and how to use it to develop your application.
+ </para>
+
+ <section id='setting-up-the-eclipse-ide'>
+ <title>Setting Up the Eclipse IDE</title>
+
+ <para>
+ To develop within the Eclipse IDE, you need to do the following:
+ <orderedlist>
+ <listitem><para>Install the optimal version of the Eclipse
+ IDE.</para></listitem>
+ <listitem><para>Configure the Eclipse IDE.
+ </para></listitem>
+ <listitem><para>Install the Eclipse Yocto Plug-in.
+ </para></listitem>
+ <listitem><para>Configure the Eclipse Yocto Plug-in.
+ </para></listitem>
+ </orderedlist>
+ <note>
+ Do not install Eclipse from your distribution's package
+ repository.
+ Be sure to install Eclipse from the official Eclipse
+ download site as directed in the next section.
+ </note>
+ </para>
+
+ <section id='installing-eclipse-ide'>
+ <title>Installing the Eclipse IDE</title>
+
+ <para>
+ It is recommended that you have the Luna SR2 (4.4.2)
+ version of the Eclipse IDE installed on your development
+ system.
+ However, if you currently have the Kepler 4.3.2 version
+ installed and you do not want to upgrade the IDE, you can
+ configure Kepler to work with the Yocto Project.
+ </para>
+
+ <para>
+ If you do not have the Luna SR2 (4.4.2) Eclipse IDE
+ installed, you can find the tarball at
+ <ulink url='&ECLIPSE_MAIN_URL;'></ulink>.
+ From that site, choose the appropriate download from the
+ "Eclipse IDE for C/C++ Developers".
+ This version contains the Eclipse Platform, the Java
+ Development Tools (JDT), and the Plug-in Development
+ Environment.
+ </para>
+
+ <para>
+ Once you have downloaded the tarball, extract it into a
+ clean directory.
+ For example, the following commands unpack and install the
+ downloaded Eclipse IDE tarball into a clean directory
+ using the default name <filename>eclipse</filename>:
+ <literallayout class='monospaced'>
+ $ cd ~
+ $ tar -xzvf ~/Downloads/eclipse-cpp-luna-SR2-linux-gtk-x86_64.tar.gz
+ </literallayout>
+ </para>
+ </section>
+
+ <section id='configuring-the-eclipse-ide'>
+ <title>Configuring the Eclipse IDE</title>
+
+ <para>
+ This section presents the steps needed to configure the
+ Eclipse IDE.
+ </para>
+
+ <para>
+ Before installing and configuring the Eclipse Yocto Plug-in,
+ you need to configure the Eclipse IDE.
+ Follow these general steps:
+ <orderedlist>
+ <listitem><para>Start the Eclipse IDE.</para></listitem>
+ <listitem><para>Make sure you are in your Workbench and
+ select "Install New Software" from the "Help"
+ pull-down menu.</para></listitem>
+ <listitem><para>Select
+ <filename>Luna - &ECLIPSE_LUNA_URL;</filename>
+ from the "Work with:" pull-down menu.
+ <note>
+ For Kepler, select
+ <filename>Kepler - &ECLIPSE_KEPLER_URL;</filename>
+ </note>
+ </para></listitem>
+ <listitem><para>Expand the box next to "Linux Tools"
+ and select the
+ <filename>Linux Tools LTTng Tracer Control</filename>,
+ <filename>Linux Tools LTTng Userspace Analysis</filename>,
+ and
+ <filename>LTTng Kernel Analysis</filename> boxes.
+ If these selections do not appear in the list,
+ that means the items are already installed.
+ <note>
+ For Kepler, select
+ <filename>LTTng - Linux Tracing Toolkit</filename>
+ box.
+ </note>
+ </para></listitem>
+ <listitem><para>Expand the box next to "Mobile and
+ Device Development" and select the following boxes.
+ Again, if any of the following items are not
+ available for selection, that means the items are
+ already installed:
+ <itemizedlist>
+ <listitem><para><filename>C/C++ Remote Launch (Requires RSE Remote System Explorer)</filename></para></listitem>
+ <listitem><para><filename>Remote System Explorer End-user Runtime</filename></para></listitem>
+ <listitem><para><filename>Remote System Explorer User Actions</filename></para></listitem>
+ <listitem><para><filename>Target Management Terminal (Core SDK)</filename></para></listitem>
+ <listitem><para><filename>TCF Remote System Explorer add-in</filename></para></listitem>
+ <listitem><para><filename>TCF Target Explorer</filename></para></listitem>
+ </itemizedlist></para></listitem>
+ <listitem><para>Expand the box next to "Programming
+ Languages" and select the
+ <filename>C/C++ Autotools Support</filename>
+ and <filename>C/C++ Development Tools</filename>
+ boxes.
+ For Luna, these items do not appear on the list
+ as they are already installed.
+ </para></listitem>
+ <listitem><para>Complete the installation and restart
+ the Eclipse IDE.</para></listitem>
+ </orderedlist>
+ </para>
+ </section>
+
+ <section id='installing-the-eclipse-yocto-plug-in'>
+ <title>Installing or Accessing the Eclipse Yocto Plug-in</title>
+
+ <para>
+ You can install the Eclipse Yocto Plug-in into the Eclipse
+ IDE one of two ways: use the Yocto Project's Eclipse
+ Update site to install the pre-built plug-in or build and
+ install the plug-in from the latest source code.
+ </para>
+
+ <section id='new-software'>
+ <title>Installing the Pre-built Plug-in from the Yocto Project Eclipse Update Site</title>
+
+ <para>
+ To install the Eclipse Yocto Plug-in from the update
+ site, follow these steps:
+ <orderedlist>
+ <listitem><para>Start up the Eclipse IDE.
+ </para></listitem>
+ <listitem><para>In Eclipse, select "Install New
+ Software" from the "Help" menu.
+ </para></listitem>
+ <listitem><para>Click "Add..." in the "Work with:"
+ area.</para></listitem>
+ <listitem><para>Enter
+ <filename>&ECLIPSE_DL_PLUGIN_URL;/luna</filename>
+ in the URL field and provide a meaningful name
+ in the "Name" field.
+ <note>
+ If you are using Kepler, use
+ <filename>&ECLIPSE_DL_PLUGIN_URL;/kepler</filename>
+ in the URL field.
+ </note></para></listitem>
+ <listitem><para>Click "OK" to have the entry added
+ to the "Work with:" drop-down list.
+ </para></listitem>
+ <listitem><para>Select the entry for the plug-in
+ from the "Work with:" drop-down list.
+ </para></listitem>
+ <listitem><para>Check the boxes next to
+ <filename>Yocto Project ADT Plug-in</filename>,
+ <filename>Yocto Project Bitbake Commander Plug-in</filename>,
+ and
+ <filename>Yocto Project Documentation plug-in</filename>.
+ </para></listitem>
+ <listitem><para>Complete the remaining software
+ installation steps and then restart the Eclipse
+ IDE to finish the installation of the plug-in.
+ <note>
+ You can click "OK" when prompted about
+ installing software that contains unsigned
+ content.
+ </note>
+ </para></listitem>
+ </orderedlist>
+ </para>
+ </section>
+
+ <section id='zip-file-method'>
+ <title>Installing the Plug-in Using the Latest Source Code</title>
+
+ <para>
+ To install the Eclipse Yocto Plug-in from the latest
+ source code, follow these steps:
+ <orderedlist>
+ <listitem><para>Be sure your development system
+ is not using OpenJDK to build the plug-in
+ by doing the following:
+ <orderedlist>
+ <listitem><para>Use the Oracle JDK.
+ If you don't have that, go to
+ <ulink url='http://www.oracle.com/technetwork/java/javase/downloads/jdk7-downloads-1880260.html'></ulink>
+ and download the latest appropriate
+ Java SE Development Kit tarball for
+ your development system and
+ extract it into your home directory.
+ </para></listitem>
+ <listitem><para>In the shell you are going
+ to do your work, export the location of
+ the Oracle Java.
+ The previous step creates a new folder
+ for the extracted software.
+ You need to use the following
+ <filename>export</filename> command
+ and provide the specific location:
+ <literallayout class='monospaced'>
+ export PATH=~/<replaceable>extracted_jdk_location</replaceable>/bin:$PATH
+ </literallayout>
+ </para></listitem>
+ </orderedlist>
+ </para></listitem>
+ <listitem><para>In the same shell, create a Git
+ repository with:
+ <literallayout class='monospaced'>
+ $ cd ~
+ $ git clone git://git.yoctoproject.org/eclipse-poky
+ </literallayout>
+ </para></listitem>
+ <listitem><para>Be sure to checkout the correct
+ tag.
+ For example, if you are using Luna, do the
+ following:
+ <literallayout class='monospaced'>
+ $ git checkout luna/yocto-1.8
+ </literallayout>
+ This puts you in a detached HEAD state, which
+ is fine since you are only going to be building
+ and not developing.
+ <note>
+ If you are building kepler, checkout the
+ <filename>kepler/yocto-1.8</filename>
+ branch.
+ </note>
+ </para></listitem>
+ <listitem><para>Change to the
+ <filename>scripts</filename>
+ directory within the Git repository:
+ <literallayout class='monospaced'>
+ $ cd scripts
+ </literallayout>
+ </para></listitem>
+ <listitem><para>Set up the local build environment
+ by running the setup script:
+ <literallayout class='monospaced'>
+ $ ./setup.sh
+ </literallayout>
+ </para></listitem>
+ <listitem><para>When the script finishes execution,
+ it prompts you with instructions on how to run
+ the <filename>build.sh</filename> script, which
+ is also in the <filename>scripts</filename>
+ directory of the Git repository created
+ earlier.
+ </para></listitem>
+ <listitem><para>Run the <filename>build.sh</filename>
+ script as directed.
+ Be sure to provide the tag name, documentation
+ branch, and a release name.
+ Here is an example that uses the
+ <filename>luna/yocto-1.8</filename> tag, the
+ <filename>master</filename> documentation
+ branch, and
+ <filename>&DISTRO_NAME;</filename> for the
+ release name:
+ <literallayout class='monospaced'>
+ $ ECLIPSE_HOME=/home/scottrif/eclipse-poky/scripts/eclipse ./build.sh luna/yocto-1.8 master &DISTRO_NAME; 2>&1 | tee -a build.log
+ </literallayout>
+ After running the script, the file
+ <filename>org.yocto.sdk-</filename><replaceable>release</replaceable><filename>-</filename><replaceable>date</replaceable><filename>-archive.zip</filename>
+ is in the current directory.
+ </para></listitem>
+ <listitem><para>If necessary, start the Eclipse IDE
+ and be sure you are in the Workbench.
+ </para></listitem>
+ <listitem><para>Select "Install New Software" from
+ the "Help" pull-down menu.
+ </para></listitem>
+ <listitem><para>Click "Add".</para></listitem>
+ <listitem><para>Provide anything you want in the
+ "Name" field.
+ </para></listitem>
+ <listitem><para>Click "Archive" and browse to the
+ ZIP file you built in step eight.
+ This ZIP file should not be "unzipped", and must
+ be the <filename>*archive.zip</filename> file
+ created by running the
+ <filename>build.sh</filename> script.
+ </para></listitem>
+ <listitem><para>Click the "OK" button.
+ </para></listitem>
+ <listitem><para>Check the boxes that appear in
+ the installation window to install the
+ <filename>Yocto Project ADT Plug-in</filename>,
+ <filename>Yocto Project Bitbake Commander Plug-in</filename>,
+ and the
+ <filename>Yocto Project Documentation plug-in</filename>.
+ </para></listitem>
+ <listitem><para>Finish the installation by clicking
+ through the appropriate buttons.
+ You can click "OK" when prompted about
+ installing software that contains unsigned
+ content.
+ </para></listitem>
+ <listitem><para>Restart the Eclipse IDE if
+ necessary.
+ </para></listitem>
+ </orderedlist>
+ </para>
+
+ <para>
+ At this point you should be able to configure the
+ Eclipse Yocto Plug-in as described in the
+ "<link linkend='configuring-the-eclipse-yocto-plug-in'>Configuring the Eclipse Yocto Plug-in</link>"
+ section.</para>
+ </section>
+ </section>
+
+ <section id='configuring-the-eclipse-yocto-plug-in'>
+ <title>Configuring the Eclipse Yocto Plug-in</title>
+
+ <para>
+ Configuring the Eclipse Yocto Plug-in involves setting the
+ Cross Compiler options and the Target options.
+ The configurations you choose become the default settings
+ for all projects.
+ You do have opportunities to change them later when
+ you configure the project (see the following section).
+ </para>
+
+ <para>
+ To start, you need to do the following from within the
+ Eclipse IDE:
+ <itemizedlist>
+ <listitem><para>Choose "Preferences" from the
+ "Window" menu to display the Preferences Dialog.
+ </para></listitem>
+ <listitem><para>Click "Yocto Project ADT" to display
+ the configuration screen.
+ </para></listitem>
+ </itemizedlist>
+ </para>
+
+ <section id='configuring-the-cross-compiler-options'>
+ <title>Configuring the Cross-Compiler Options</title>
+
+ <para>
+ To configure the Cross Compiler Options, you must select
+ the type of toolchain, point to the toolchain, specify
+ the sysroot location, and select the target
+ architecture.
+ <itemizedlist>
+ <listitem><para><emphasis>Selecting the Toolchain Type:</emphasis>
+ Choose between
+ <filename>Standalone pre-built toolchain</filename>
+ and
+ <filename>Build system derived toolchain</filename>
+ for Cross Compiler Options.
+ <itemizedlist>
+ <listitem><para><emphasis>
+ <filename>Standalone Pre-built Toolchain:</filename></emphasis>
+ Select this mode when you are using
+ a stand-alone cross-toolchain.
+ For example, suppose you are an
+ application developer and do not
+ need to build a target image.
+ Instead, you just want to use an
+ architecture-specific toolchain on
+ an existing kernel and target root
+ filesystem.</para></listitem>
+ <listitem><para><emphasis>
+ <filename>Build System Derived Toolchain:</filename></emphasis>
+ Select this mode if the
+ cross-toolchain has been installed
+ and built as part of the
+ <link linkend='build-directory'>Build Directory</link>.
+ When you select
+ <filename>Build system derived toolchain</filename>,
+ you are using the toolchain bundled
+ inside the Build Directory.
+ </para></listitem>
+ </itemizedlist>
+ </para></listitem>
+ <listitem><para><emphasis>Point to the Toolchain:</emphasis>
+ If you are using a stand-alone pre-built
+ toolchain, you should be pointing to where it is
+ installed.
+ If you used the ADT Installer script and
+ accepted the default installation directory, the
+ toolchain will be installed in the
+ <filename>&YOCTO_ADTPATH_DIR;</filename>
+ directory.
+ Sections "<ulink url='&YOCTO_DOCS_ADT_URL;#configuring-and-running-the-adt-installer-script'>Configuring and Running the ADT Installer Script</ulink>"
+ and
+ "<ulink url='&YOCTO_DOCS_ADT_URL;#using-an-existing-toolchain-tarball'>Using a Cross-Toolchain Tarball</ulink>"
+ in the Yocto Project Application Developer's
+ Guide describe how to install a stand-alone
+ cross-toolchain.</para>
+ <para>If you are using a system-derived
+ toolchain, the path you provide for the
+ <filename>Toolchain Root Location</filename>
+ field is the
+ <link linkend='build-directory'>Build Directory</link>.
+ See the
+ "<ulink url='&YOCTO_DOCS_ADT_URL;#using-the-toolchain-from-within-the-build-tree'>Using BitBake and the Build Directory</ulink>"
+ section in the Yocto Project Application
+ Developer's Guide for information on how to
+ install the toolchain into the Build
+ Directory.</para></listitem>
+ <listitem><para><emphasis>Specify the Sysroot Location:</emphasis>
+ This location is where the root filesystem for
+ the target hardware resides.
+ If you used the ADT Installer script and
+ accepted the default installation directory,
+ then the location in your home directory
+ in a folder named
+ <filename>test-yocto/</filename><replaceable>target_arch</replaceable>.
+ Additionally, when you use the ADT Installer
+ script, the
+ <filename>/opt/poky/&DISTRO;/sysroots</filename>
+ location is used for the QEMU
+ user-space tools and the NFS boot process.
+ </para>
+ <para>If you used either of the other two
+ methods to install the toolchain or did not
+ accept the ADT Installer script's default
+ installation directory, then the location of
+ the sysroot filesystem depends on where you
+ separately extracted and installed the
+ filesystem.</para>
+ <para>For information on how to install the
+ toolchain and on how to extract and install the
+ sysroot filesystem, 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></listitem>
+ <listitem><para><emphasis>Select the Target Architecture:</emphasis>
+ The target architecture is the type of hardware
+ you are going to use or emulate.
+ Use the pull-down
+ <filename>Target Architecture</filename> menu
+ to make your selection.
+ The pull-down menu should have the supported
+ architectures.
+ If the architecture you need is not listed in
+ the menu, you will need to build the image.
+ See the
+ "<ulink url='&YOCTO_DOCS_QS_URL;#qs-building-images'>Building Images</ulink>"
+ section of the Yocto Project Quick Start for
+ more information.</para></listitem>
+ </itemizedlist>
+ </para>
+ </section>
+
+ <section id='configuring-the-target-options'>
+ <title>Configuring the Target Options</title>
+
+ <para>
+ You can choose to emulate hardware using the QEMU
+ emulator, or you can choose to run your image on actual
+ hardware.
+ <itemizedlist>
+ <listitem><para><emphasis>QEMU:</emphasis>
+ Select this option if you will be using the
+ QEMU emulator.
+ If you are using the emulator, you also need to
+ locate the kernel and specify any custom
+ options.</para>
+ <para>If you selected
+ <filename>Build system derived toolchain</filename>,
+ the target kernel you built will be located in
+ the Build Directory in
+ <filename>tmp/deploy/images/<replaceable>machine</replaceable></filename>
+ directory.
+ If you selected
+ <filename>Standalone pre-built toolchain</filename>,
+ the pre-built image you downloaded is located
+ in the directory you specified when you
+ downloaded the image.</para>
+ <para>Most custom options are for advanced QEMU
+ users to further customize their QEMU instance.
+ These options are specified between paired
+ angled brackets.
+ Some options must be specified outside the
+ brackets.
+ In particular, the options
+ <filename>serial</filename>,
+ <filename>nographic</filename>, and
+ <filename>kvm</filename> must all be outside the
+ brackets.
+ Use the <filename>man qemu</filename> command
+ to get help on all the options and their use.
+ The following is an example:
+ <literallayout class='monospaced'>
+ serial ‘<-m 256 -full-screen>’
+ </literallayout></para>
+ <para>
+ Regardless of the mode, Sysroot is already
+ defined as part of the Cross-Compiler Options
+ configuration in the
+ <filename>Sysroot Location:</filename> field.
+ </para></listitem>
+ <listitem><para><emphasis>External HW:</emphasis>
+ Select this option if you will be using actual
+ hardware.</para></listitem>
+ </itemizedlist>
+ </para>
+
+ <para>
+ Click the "OK" to save your plug-in configurations.
+ </para>
+ </section>
+ </section>
+ </section>
+
+ <section id='creating-the-project'>
+ <title>Creating the Project</title>
+
+ <para>
+ You can create two types of projects: Autotools-based, or
+ Makefile-based.
+ This section describes how to create Autotools-based projects
+ from within the Eclipse IDE.
+ For information on creating Makefile-based projects in a
+ terminal window, see the section
+ "<ulink url='&YOCTO_DOCS_ADT_URL;#using-the-command-line'>Using the Command Line</ulink>"
+ in the Yocto Project Application Developer's Guide.
+ <note>
+ Do not use special characters in project names
+ (e.g. spaces, underscores, etc.). Doing so can
+ cause configuration to fail.
+ </note>
+ </para>
+
+ <para>
+ To create a project based on a Yocto template and then display
+ the source code, follow these steps:
+ <orderedlist>
+ <listitem><para>Select "Project" from the "File -> New" menu.
+ </para></listitem>
+ <listitem><para>Double click <filename>CC++</filename>.
+ </para></listitem>
+ <listitem><para>Double click <filename>C Project</filename>
+ to create the project.</para></listitem>
+ <listitem><para>Expand <filename>Yocto Project ADT Autotools Project</filename>.
+ </para></listitem>
+ <listitem><para>Select <filename>Hello World ANSI C Autotools Project</filename>.
+ This is an Autotools-based project based on a Yocto
+ template.</para></listitem>
+ <listitem><para>Put a name in the <filename>Project name:</filename>
+ field.
+ Do not use hyphens as part of the name.
+ </para></listitem>
+ <listitem><para>Click "Next".</para></listitem>
+ <listitem><para>Add information in the
+ <filename>Author</filename> and
+ <filename>Copyright notice</filename> fields.
+ </para></listitem>
+ <listitem><para>Be sure the <filename>License</filename>
+ field is correct.</para></listitem>
+ <listitem><para>Click "Finish".</para></listitem>
+ <listitem><para>If the "open perspective" prompt appears,
+ click "Yes" so that you in the C/C++ perspective.
+ </para></listitem>
+ <listitem><para>The left-hand navigation pane shows your
+ project.
+ You can display your source by double clicking the
+ project's source file.</para></listitem>
+ </orderedlist>
+ </para>
+ </section>
+
+ <section id='configuring-the-cross-toolchains'>
+ <title>Configuring the Cross-Toolchains</title>
+
+ <para>
+ The earlier section,
+ "<link linkend='configuring-the-eclipse-yocto-plug-in'>Configuring the Eclipse Yocto Plug-in</link>",
+ sets up the default project configurations.
+ You can override these settings for a given project by following
+ these steps:
+ <orderedlist>
+ <listitem><para>Select "Change Yocto Project Settings" from
+ the "Project" menu.
+ This selection brings up the Yocto Project Settings
+ Dialog and allows you to make changes specific to an
+ individual project.</para>
+ <para>By default, the Cross Compiler Options and Target
+ Options for a project are inherited from settings you
+ provided using the Preferences Dialog as described
+ earlier in the
+ "<link linkend='configuring-the-eclipse-yocto-plug-in'>Configuring the Eclipse Yocto Plug-in</link>" section.
+ The Yocto Project Settings Dialog allows you to override
+ those default settings for a given project.
+ </para></listitem>
+ <listitem><para>Make your configurations for the project
+ and click "OK".
+ </para></listitem>
+ <listitem><para>Right-click in the navigation pane and
+ select "Reconfigure Project" from the pop-up menu.
+ This selection reconfigures the project by running
+ <filename>autogen.sh</filename> in the workspace for
+ your project.
+ The script also runs <filename>libtoolize</filename>,
+ <filename>aclocal</filename>,
+ <filename>autoconf</filename>,
+ <filename>autoheader</filename>,
+ <filename>automake --a</filename>, and
+ <filename>./configure</filename>.
+ Click on the "Console" tab beneath your source code to
+ see the results of reconfiguring your project.
+ </para></listitem>
+ </orderedlist>
+ </para>
+ </section>
+
+ <section id='building-the-project'>
+ <title>Building the Project</title>
+
+ <para>
+ To build the project select "Build Project" from the
+ "Project" menu.
+ The console should update and you can note the cross-compiler
+ you are using.
+ </para>
+ </section>
+
+ <section id='starting-qemu-in-user-space-nfs-mode'>
+ <title>Starting QEMU in User-Space NFS Mode</title>
+
+ <para>
+ To start the QEMU emulator from within Eclipse, follow these
+ steps:
+ <note>
+ See the
+ "<link linkend='dev-manual-qemu'>Using the Quick EMUlator (QEMU)</link>"
+ chapter for more information on using QEMU.
+ </note>
+ <orderedlist>
+ <listitem><para>Expose and select "External Tools" from
+ the "Run" menu.
+ Your image should appear as a selectable menu item.
+ </para></listitem>
+ <listitem><para>Select your image from the menu to launch
+ the emulator in a new window.
+ </para></listitem>
+ <listitem><para>If needed, enter your host root password in
+ the shell window at the prompt.
+ This sets up a <filename>Tap 0</filename> connection
+ needed for running in user-space NFS mode.
+ </para></listitem>
+ <listitem><para>Wait for QEMU to launch.</para></listitem>
+ <listitem><para>Once QEMU launches, you can begin operating
+ within that environment.
+ One useful task at this point would be to determine the
+ IP Address for the user-space NFS by using the
+ <filename>ifconfig</filename> command.
+ </para></listitem>
+ </orderedlist>
+ </para>
+ </section>
+
+ <section id='deploying-and-debugging-the-application'>
+ <title>Deploying and Debugging the Application</title>
+
+ <para>
+ Once the QEMU emulator is running the image, you can deploy
+ your application using the Eclipse IDE and then use
+ the emulator to perform debugging.
+ Follow these steps to deploy the application.
+ <orderedlist>
+ <listitem><para>Select "Debug Configurations..." from the
+ "Run" menu.</para></listitem>
+ <listitem><para>In the left area, expand
+ <filename>C/C++Remote Application</filename>.
+ </para></listitem>
+ <listitem><para>Locate your project and select it to bring
+ up a new tabbed view in the Debug Configurations Dialog.
+ </para></listitem>
+ <listitem><para>Enter the absolute path into which you want
+ to deploy the application.
+ Use the "Remote Absolute File Path for
+ C/C++Application:" field.
+ For example, enter
+ <filename>/usr/bin/<replaceable>programname</replaceable></filename>.
+ </para></listitem>
+ <listitem><para>Click on the "Debugger" tab to see the
+ cross-tool debugger you are using.</para></listitem>
+ <listitem><para>Click on the "Main" tab.</para></listitem>
+ <listitem><para>Create a new connection to the QEMU instance
+ by clicking on "new".</para></listitem>
+ <listitem><para>Select <filename>TCF</filename>, which means
+ Target Communication Framework.</para></listitem>
+ <listitem><para>Click "Next".</para></listitem>
+ <listitem><para>Clear out the "host name" field and enter
+ the IP Address determined earlier.</para></listitem>
+ <listitem><para>Click "Finish" to close the
+ New Connections Dialog.</para></listitem>
+ <listitem><para>Use the drop-down menu now in the
+ "Connection" field and pick the IP Address you entered.
+ </para></listitem>
+ <listitem><para>Click "Debug" to bring up a login screen
+ and login.</para></listitem>
+ <listitem><para>Accept the debug perspective.
+ </para></listitem>
+ </orderedlist>
+ </para>
+ </section>
+
+ <section id='running-user-space-tools'>
+ <title>Running User-Space Tools</title>
+
+ <para>
+ As mentioned earlier in the manual, several tools exist that
+ enhance your development experience.
+ These tools are aids in developing and debugging applications
+ and images.
+ You can run these user-space tools from within the Eclipse
+ IDE through the "YoctoProjectTools" menu.
+ </para>
+
+ <para>
+ Once you pick a tool, you need to configure it for the remote
+ target.
+ Every tool needs to have the connection configured.
+ You must select an existing TCF-based RSE connection to the
+ remote target.
+ If one does not exist, click "New" to create one.
+ </para>
+
+ <para>
+ Here are some specifics about the remote tools:
+ <itemizedlist>
+ <listitem><para><emphasis><filename>OProfile</filename>:</emphasis>
+ Selecting this tool causes the
+ <filename>oprofile-server</filename> on the remote
+ target to launch on the local host machine.
+ The <filename>oprofile-viewer</filename> must be
+ installed on the local host machine and the
+ <filename>oprofile-server</filename> must be installed
+ on the remote target, respectively, in order to use.
+ You must compile and install the
+ <filename>oprofile-viewer</filename> from the source
+ code on your local host machine.
+ Furthermore, in order to convert the target's sample
+ format data into a form that the host can use, you must
+ have OProfile version 0.9.4 or greater installed on the
+ host.</para>
+ <para>You can locate both the viewer and server from
+ <ulink url='&YOCTO_GIT_URL;/cgit/cgit.cgi/oprofileui/'></ulink>.
+ You can also find more information on setting up and
+ using this tool in the
+ "<ulink url='&YOCTO_DOCS_PROF_URL;#profile-manual-oprofile'>oprofile</ulink>"
+ section of the Yocto Project Profiling and Tracing
+ Manual.
+ <note>The <filename>oprofile-server</filename> is
+ installed by default on the
+ <filename>core-image-sato-sdk</filename> image.</note>
+ </para></listitem>
+ <listitem><para><emphasis><filename>Lttng2.0 trace import</filename>:</emphasis>
+ Selecting this tool transfers the remote target's
+ <filename>Lttng</filename> tracing data back to the
+ local host machine and uses the Lttng Eclipse plug-in
+ to graphically display the output.
+ For information on how to use Lttng to trace an
+ application,
+ see <ulink url='http://lttng.org/documentation'></ulink>
+ and the
+ "<ulink url='&YOCTO_DOCS_PROF_URL;#lttng-linux-trace-toolkit-next-generation'>LTTng (Linux Trace Toolkit, next generation)</ulink>"
+ section, which is in the Yocto Project Profiling and
+ Tracing Manual.
+ <note>Do not use
+ <filename>Lttng-user space (legacy)</filename> tool.
+ This tool no longer has any upstream support.</note>
+ </para>
+ <para>Before you use the
+ <filename>Lttng2.0 trace import</filename> tool,
+ you need to setup the Lttng Eclipse plug-in and create a
+ Tracing project.
+ Do the following:
+ <orderedlist>
+ <listitem><para>Select "Open Perspective" from the
+ "Window" menu and then select "Other..." to
+ bring up a menu of other perspectives.
+ Choose "Tracing".
+ </para></listitem>
+ <listitem><para>Click "OK" to change the Eclipse
+ perspective into the Tracing perspective.
+ </para></listitem>
+ <listitem><para>Create a new Tracing project by
+ selecting "Project" from the "File -> New" menu.
+ </para></listitem>
+ <listitem><para>Choose "Tracing Project" from the
+ "Tracing" menu and click "Next".
+ </para></listitem>
+ <listitem><para>Provide a name for your tracing
+ project and click "Finish".
+ </para></listitem>
+ <listitem><para>Generate your tracing data on the
+ remote target.</para></listitem>
+ <listitem><para>Select "Lttng2.0 trace import"
+ from the "Yocto Project Tools" menu to
+ start the data import process.</para></listitem>
+ <listitem><para>Specify your remote connection name.
+ </para></listitem>
+ <listitem><para>For the Ust directory path, specify
+ the location of your remote tracing data.
+ Make sure the location ends with
+ <filename>ust</filename> (e.g.
+ <filename>/usr/mysession/ust</filename>).
+ </para></listitem>
+ <listitem><para>Click "OK" to complete the import
+ process.
+ The data is now in the local tracing project
+ you created.</para></listitem>
+ <listitem><para>Right click on the data and then use
+ the menu to Select "Generic CTF Trace" from the
+ "Trace Type... -> Common Trace Format" menu to
+ map the tracing type.</para></listitem>
+ <listitem><para>Right click the mouse and select
+ "Open" to bring up the Eclipse Lttng Trace
+ Viewer so you view the tracing data.
+ </para></listitem>
+ </orderedlist></para></listitem>
+ <listitem><para><emphasis><filename>PowerTOP</filename>:</emphasis>
+ Selecting this tool runs PowerTOP on the remote target
+ machine and displays the results in a new view called
+ PowerTOP.</para>
+ <para>The "Time to gather data(sec):" field is the time
+ passed in seconds before data is gathered from the
+ remote target for analysis.</para>
+ <para>The "show pids in wakeups list:" field corresponds
+ to the <filename>-p</filename> argument passed to
+ <filename>PowerTOP</filename>.</para></listitem>
+ <listitem><para><emphasis><filename>LatencyTOP and Perf</filename>:</emphasis>
+ LatencyTOP identifies system latency, while
+ Perf monitors the system's performance counter
+ registers.
+ Selecting either of these tools causes an RSE terminal
+ view to appear from which you can run the tools.
+ Both tools refresh the entire screen to display results
+ while they run.
+ For more information on setting up and using
+ <filename>perf</filename>, see the
+ "<ulink url='&YOCTO_DOCS_PROF_URL;#profile-manual-perf'>perf</ulink>"
+ section in the Yocto Project Profiling and Tracing
+ Manual.
+ </para></listitem>
+ <listitem><para><emphasis><filename>SystemTap</filename>:</emphasis>
+ Systemtap is a tool that lets you create and reuse
+ scripts to examine the activities of a live Linux
+ system.
+ You can easily extract, filter, and summarize data
+ that helps you diagnose complex performance or
+ functional problems.
+ For more information on setting up and using
+ <filename>SystemTap</filename>, see the
+ <ulink url='https://sourceware.org/systemtap/documentation.html'>SystemTap Documentation</ulink>.
+ </para></listitem>
+ <listitem><para><emphasis><filename>yocto-bsp</filename>:</emphasis>
+ The <filename>yocto-bsp</filename> tool lets you
+ quickly set up a Board Support Package (BSP) layer.
+ The tool requires a Metadata location, build location,
+ BSP name, BSP output location, and a kernel
+ architecture.
+ For more information on the
+ <filename>yocto-bsp</filename> tool outside of Eclipse,
+ see the
+ "<ulink url='&YOCTO_DOCS_BSP_URL;#creating-a-new-bsp-layer-using-the-yocto-bsp-script'>Creating a new BSP Layer Using the yocto-bsp Script</ulink>"
+ section in the Yocto Project Board Support Package
+ (BSP) Developer's Guide.
+ </para></listitem>
+ </itemizedlist>
+ </para>
+ </section>
+ </section>
+
+ <section id='workflow-using-stand-alone-cross-development-toolchains'>
+ <title>Workflow Using Stand-Alone Cross-Development Toolchains</title>
+
+ <para>
+ If you want to develop an application without prior installation
+ of the ADT, you still can employ the
+ <link linkend='cross-development-toolchain'>Cross Development Toolchain</link>,
+ the QEMU emulator, and a number of supported target image files.
+ You just need to follow these general steps:
+ <orderedlist>
+ <listitem><para><emphasis>Install the cross-development
+ toolchain for your target hardware:</emphasis>
+ For information on how to install the toolchain, see the
+ "<ulink url='&YOCTO_DOCS_ADT_URL;#using-an-existing-toolchain-tarball'>Using a Cross-Toolchain Tarball</ulink>"
+ section in the Yocto Project Application Developer's
+ Guide.</para></listitem>
+ <listitem><para><emphasis>Download the Target Image:</emphasis>
+ The Yocto Project supports several target architectures
+ and has many pre-built kernel images and root filesystem
+ images.</para>
+ <para>If you are going to develop your application on
+ hardware, go to the
+ <ulink url='&YOCTO_MACHINES_DL_URL;'><filename>machines</filename></ulink>
+ download area and choose a target machine area
+ from which to download the kernel image and root filesystem.
+ This download area could have several files in it that
+ support development using actual hardware.
+ For example, the area might contain
+ <filename>.hddimg</filename> files that combine the
+ kernel image with the filesystem, boot loaders, and
+ so forth.
+ Be sure to get the files you need for your particular
+ development process.</para>
+ <para>If you are going to develop your application and
+ then run and test it using the QEMU emulator, go to the
+ <ulink url='&YOCTO_QEMU_DL_URL;'><filename>machines/qemu</filename></ulink>
+ download area.
+ From this area, go down into the directory for your
+ target architecture (e.g. <filename>qemux86_64</filename>
+ for an <trademark class='registered'>Intel</trademark>-based
+ 64-bit architecture).
+ Download kernel, root filesystem, and any other files you
+ need for your process.
+ <note>In order to use the root filesystem in QEMU, you
+ need to extract it.
+ See the
+ "<ulink url='&YOCTO_DOCS_ADT_URL;#extracting-the-root-filesystem'>Extracting the Root Filesystem</ulink>"
+ section for information on how to extract the root
+ filesystem.</note></para></listitem>
+ <listitem><para><emphasis>Develop and Test your
+ Application:</emphasis> At this point, you have the tools
+ to develop your application.
+ If you need to separately install and use the QEMU
+ emulator, you can go to
+ <ulink url='http://wiki.qemu.org/Main_Page'>QEMU Home Page</ulink>
+ to download and learn about the emulator.
+ You can see the
+ "<link linkend='dev-manual-qemu'>Using the Quick EMUlator (QEMU)</link>"
+ chapter for information on using QEMU within the Yocto
+ Project.</para></listitem>
+ </orderedlist>
+ </para>
+ </section>
+</section>
+
+<section id="dev-modifying-source-code">
+ <title>Modifying Source Code</title>
+
+ <para>
+ A common development workflow consists of modifying project source
+ files that are external to the Yocto Project and then integrating
+ that project's build output into an image built using the
+ OpenEmbedded build system.
+ Given this scenario, development engineers typically want to stick
+ to their familiar project development tools and methods, which allows
+ them to just focus on the project.
+ </para>
+
+ <para>
+ Several workflows exist that allow you to develop, build, and test
+ code that is going to be integrated into an image built using the
+ OpenEmbedded build system.
+ This section describes two:
+ <itemizedlist>
+ <listitem><para><emphasis><filename>devtool</filename>:</emphasis>
+ A set of tools to aid in working on the source code built by
+ the OpenEmbedded build system.
+ Section
+ "<link linkend='using-devtool-in-your-workflow'>Using <filename>devtool</filename> in Your Workflow</link>"
+ describes this workflow.
+ If you want more information that showcases the workflow, click
+ <ulink url='https://drive.google.com/a/linaro.org/file/d/0B3KGzY5fW7laTDVxUXo3UDRvd2s/view'>here</ulink>
+ for an excellent presentation by Trevor Woerner that
+ provides detailed background information and a complete
+ working tutorial.
+ </para></listitem>
+ <listitem><para><emphasis><ulink url='http://savannah.nongnu.org/projects/quilt'>Quilt</ulink>:</emphasis>
+ A powerful tool that allows you to capture source
+ code changes without having a clean source tree.
+ While Quilt is not the preferred workflow of the two, this
+ section includes it for users that are committed to using
+ the tool.
+ See the
+ "<link linkend='using-a-quilt-workflow'>Using Quilt in Your Workflow</link>"
+ section for more information.
+ </para></listitem>
+ </itemizedlist>
+ </para>
+
+ <section id='using-devtool-in-your-workflow'>
+ <title>Using <filename>devtool</filename> in Your Workflow</title>
+
+ <para>
+ As mentioned earlier, <filename>devtool</filename> helps
+ you easily develop projects whose build output must be part of
+ an image built using the OpenEmbedded build system.
+ The remainder of this section presents the workflow you would
+ use that includes <filename>devtool</filename>.
+ <footnote>
+ <para>
+ Kudos and thanks to
+ <ulink url='mailto:twoerner@gmail.com'>Trevor Woerner</ulink>
+ whose
+ "<ulink url='https://drive.google.com/file/d/0B3KGzY5fW7laTDVxUXo3UDRvd2s/view'>Yocto Project Developer Workflow Tutorial</ulink>"
+ paper contributed nicely towards the development of this
+ section.
+ </para>
+ </footnote>
+ </para>
+
+ <para>
+ The steps in this section assume you have a previously built
+ image that is already either running in QEMU or running on actual
+ hardware.
+ Also, it is assumed that for deployment of the image to the
+ target, SSH is installed in the image and if the image is running
+ on real hardware that you have network access to and from your
+ development machine.
+ </para>
+
+ <section id='update-your-external-source'>
+ <title>Update Your External Source</title>
+
+ <para>
+ Part of the development flow using
+ <filename>devtool</filename> of course involves updating
+ your source files.
+ Several opportunities exist in the workflow to extract and
+ work on the files.
+ For now, just realize that you need to be able to have
+ access to and edit files.
+ One obvious solution is to initially extract the code into an
+ isolated area in preparation for modification.
+ </para>
+
+ <para>
+ Another option is to use the
+ <filename>devtool modify</filename> command.
+ This command makes use of a "workspace" layer where much of
+ the transitional work occurs, which is needed for setting up
+ Metadata used by the OpenEmbedded build system that lets you
+ build your software.
+ Options (i.e. "-x") exist using <filename>devtool</filename>
+ that enable you to use the tool to extract source code.
+ </para>
+ </section>
+
+ <section id='use-devtool-to-integrate-your-code-with-the-image'>
+ <title>Use <filename>devtool add</filename> to Integrate Your Code with the Image</title>
+
+ <para>
+ The <filename>devtool add</filename> command automatically
+ generates the needed Metadata that allows the OpenEmbedded
+ build system to build your code into the image.
+ <note>
+ If a package or packages produced by the recipe on which
+ you are working are not already in
+ <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_INSTALL'><filename>IMAGE_INSTALL</filename></ulink>
+ for the image, you must add them.
+ The <filename>devtool add</filename> command does not
+ add them for you.
+ </note>
+ Use the following command form:
+ <literallayout class='monospaced'>
+ $ devtool add <replaceable>your-project-name</replaceable> <replaceable>path-to-source</replaceable>
+ </literallayout>
+ </para>
+
+ <para>
+ Running <filename>devtool</filename> for the first time
+ creates a workspace layer through the
+ <filename>bblayers.conf</filename> file that
+ is based on your project's location:
+ <literallayout class='monospaced'>
+ <replaceable>path-to-source</replaceable>/<replaceable>build-directory</replaceable>/<replaceable>workspace-layer</replaceable>
+ </literallayout>
+ By default, the name of the workspace layer is "workspace".
+ </para>
+
+ <para>
+ For details on the workspace layer created in the
+ <replaceable>build-directory</replaceable>,
+ see the
+ "<link linkend='devtool-adding-a-new-recipe-to-the-workspace'>Adding a New Recipe to the Workspace Layer</link>"
+ section.
+ </para>
+
+<!--
+ <para>
+ Of course, each layer must have a
+ <filename>layer.conf</filename> configuration file.
+ <filename>devtool</filename> also creates this configuration
+ file:
+ <literallayout class='monospaced'>
+ $ cat workspace/conf/layer.conf
+ # ### workspace layer autogenerated by devtool ###
+ BBPATH =. "${LAYERDIR}:"
+ BBFILES += "${LAYERDIR}/recipes/*/*.bb \
+ ${LAYERDIR}/appends/*.bbappend"
+ BBFILE_COLLECTIONS += "workspacelayer"
+ BBFILE_PATTERN_workspacelayer = "^${LAYERDIR}/"
+ BBFILE_PATTERN_IGNORE_EMPTY_workspacelayer = "1"
+ BBFILE_PRIORITY_workspacelayer = "99"
+ </literallayout>
+ </para>
+-->
+
+ <para>
+ Running <filename>devtool add</filename> automatically
+ generates your recipe:
+ <literallayout class='monospaced'>
+ $ cat workspace/recipes/<replaceable>your-project-name</replaceable>/<replaceable>your-project-name</replaceable>.bb
+ # Recipe created by recipetool
+ # This is the basis of a recipe and may need further editing in order to be fully functional.
+ # (Feel free to remove these comments when editing.)
+ #
+ # Unable to find any files that looked like license statements. Check the accompanying
+ # documentation and source headers and set LICENSE and LIC_FILES_CHKSUM accordingly.
+ LICENSE = "CLOSED"
+ LIC_FILES_CHKSUM = ""
+
+ # No information for SRC_URI yet (only an external source tree was
+ # specified)
+ SRC_URI = ""
+
+ DEPENDS = "libx11"
+ # NOTE: if this software is not capable of being built in a separate build directory
+ # from the source, you should replace autotools with autotools-brokensep in the
+ # inherit line
+ inherit autotools
+
+ # Specify any options you want to pass to the configure script using EXTRA_OECONF:
+ EXTRA_OECONF = ""
+ </literallayout>
+ </para>
+
+ <para>
+ Lastly, the <filename>devtool add</filename> command creates the
+ <filename>.bbappend</filename> file:
+ <literallayout class='monospaced'>
+ $ cat workspace/appends/<replaceable>your-project-name</replaceable>.bbappend
+ inherit externalsrc
+ EXTERNALSRC = "/<replaceable>path-to-source</replaceable>/<replaceable>your-project-name</replaceable>"
+
+ # initial_rev: <replaceable>commit-ID</replaceable>
+ </literallayout>
+ </para>
+ </section>
+
+ <section id='build-your-project'>
+ <title>Build Your Project</title>
+
+ <para>
+ You can use BitBake or <filename>devtool build</filename> to
+ build your modified project.
+ </para>
+
+ <para>
+ To use BitBake, use the following:
+ <literallayout class='monospaced'>
+ $ bitbake <replaceable>your-project-name</replaceable>
+ </literallayout>
+ Alternatively, you can use
+ <filename>devtool build</filename>, which is equivalent to
+ <filename>bitbake -c populate_sysroot</filename>.
+ For example:
+ <literallayout class='monospaced'>
+ $ devtool build <replaceable>your-project-name</replaceable>
+ </literallayout>
+ </para>
+ </section>
+
+<!--
+ <section id='dev-build-the-image'>
+ <title>Build the Image</title>
+
+ <para>
+ The final step before testing is to rebuild the base image
+ with your project changes as part of the image.
+ Simply run BitBake again on your image.
+ Here is an example:
+ <literallayout class='monospaced'>
+ $ bitbake <replaceable>image</replaceable>
+ </literallayout>
+ </para>
+ </section>
+
+ <section id='dev-testing-the-image'>
+ <title>Testing the Image</title>
+
+ <para>
+ Once you have the image, you can test it using QEMU.
+ Here is an example assuming "qemux86":
+ <literallayout class='monospaced'>
+ $ runqemu qemux86 <replaceable>image</replaceable>
+ </literallayout>
+ For information on how to test an image using QEMU, see the
+ "<link linkend='dev-manual-qemu'>Using the Quick EMUlator (QEMU)</link>"
+ section.
+ </para>
+ </section>
+-->
+ </section>
+
+ <section id='devtool-quick-reference'>
+ <title><filename>devtool</filename> Quick Reference</title>
+
+ <para>
+ <filename>devtool</filename> has more functionality than simply
+ adding a new recipe and the supporting Metadata to a temporary
+ workspace layer.
+ This section provides a short reference on
+ <filename>devtool</filename> for most of the commands.
+ </para>
+
+ <section id='devtool-getting-help'>
+ <title>Getting Help</title>
+
+ <para>
+ The easiest way to get help with the
+ <filename>devtool</filename> command is using the
+ <filename>--help</filename> option:
+ <literallayout class='monospaced'>
+ $ devtool --help
+ usage: devtool [-h] [--basepath BASEPATH] [-d] [-q] [--color COLOR]
+ <subcommand> ...
+
+ OpenEmbedded development tool
+
+ optional arguments:
+ -h, --help show this help message and exit
+ --basepath BASEPATH Base directory of SDK / build directory
+ -d, --debug Enable debug output
+ -q, --quiet Print only errors
+ --color COLOR Colorize output (where COLOR is auto, always, never)
+
+ subcommands:
+ <subcommand>
+ create-workspace Set up a workspace
+ deploy-target Deploy recipe output files to live target machine
+ undeploy-target Undeploy recipe output files in live target machine
+ add Add a new recipe
+ modify Modify the source for an existing recipe
+ extract Extract the source for an existing recipe
+ update-recipe Apply changes from external source tree to recipe
+ status Show workspace status
+ build Build a recipe
+ reset Remove a recipe from your workspace
+
+ Use devtool <subcommand> --help to get help on a specific command
+ </literallayout>
+ </para>
+
+ <para>
+ As directed in the general help output, you can get more
+ syntax on a specific command by providing the command
+ name and using <filename>--help</filename>:
+ <literallayout class='monospaced'>
+ $ devtool add --help
+ usage: devtool add [-h] [--same-dir] [--fetch URI] [--version VERSION]
+ recipename srctree
+
+ Adds a new recipe
+
+ positional arguments:
+ recipename Name for new recipe to add
+ srctree Path to external source tree
+
+ optional arguments:
+ -h, --help show this help message and exit
+ --same-dir, -s Build in same directory as source
+ --fetch URI, -f URI Fetch the specified URI and extract it to create the
+ source tree
+ --version VERSION, -V VERSION
+ Version to use within recipe (PV)
+ </literallayout>
+ </para>
+ </section>
+
+ <section id='devtool-adding-a-new-recipe-to-the-workspace'>
+ <title>Adding a New Recipe to the Workspace Layer</title>
+
+ <para>
+ Use the <filename>devtool add</filename> command to add a new recipe
+ to the workspace layer.
+ The recipe you add should not exist -
+ <filename>devtool</filename> creates it for you.
+ The source files the recipe uses should exist in an external
+ area.
+ </para>
+
+ <para>
+ The following example creates and adds a new recipe named
+ <filename>jackson</filename> to the workspace layer.
+ The source code built by the recipes resides in
+ <filename>/home/scottrif/sources/jackson</filename>:
+ <literallayout class='monospaced'>
+ $ devtool add jackson /home/scottrif/sources/jackson
+ </literallayout>
+ <note>
+ For complete syntax, use the
+ <filename>devtool add --help</filename> command.
+ </note>
+ </para>
+
+ <para>
+ If you add a recipe and the workspace layer does not exist,
+ the command creates the layer and populates it as follows:
+ </para>
+
+ <para>
+ <imagedata fileref="figures/build-workspace-directory.png"
+ width="6in" depth="4in" align="center" scale="100" />
+ </para>
+
+ <para>
+ <literallayout class='monospaced'>
+ README - Provides information on what is in workspace layer and how to
+ manage it.
+
+ appends - A directory that contains *.bbappend files, which point to
+ external source.
+
+ conf - A configuration directory that contains the layer.conf file.
+
+ recipes - A directory containing recipes. This directory contains a
+ folder for each directory added whose name matches that of the
+ added recipe. devtool places the <replaceable>recipe</replaceable>.bb file
+ within that sub-directory.
+ </literallayout>
+ </para>
+
+ <para>
+ Running <filename>devtool add</filename> when the
+ workspace layer exists causes the tool to add the recipe
+ and append files into the existing workspace layer.
+ The <filename>.bbappend</filename> file is created to point
+ to the external source tree.
+ </para>
+ </section>
+
+ <section id='devtool-modifying-a-recipe'>
+ <title>Modifying an Existing Recipe</title>
+
+ <para>
+ Use the <filename>devtool modify</filename> command to begin
+ modifying the source of an existing recipe.
+ This command is very similar to the
+ <link linkend='devtool-adding-a-new-recipe-to-the-workspace'><filename>add</filename></link>
+ command except that it does not physically create the
+ recipe in the workspace layer because the recipe already
+ exists in an another layer.
+ </para>
+
+ <para>
+ The <filename>devtool modify</filename> command extracts the
+ source for a recipe, sets it up as a Git repository if the
+ source had not already been fetched from Git, checks out a
+ branch for development, and applies any patches from the recipe
+ as commits on top.
+ You can use the following command to checkout the source
+ files:
+ <literallayout class='monospaced'>
+ $ devtool modify -x <replaceable>recipe</replaceable> <replaceable>path-to-source</replaceable>
+ </literallayout>
+ Using the above command form, the default development branch
+ would be "devtool".
+ <note>
+ For complete syntax, use the
+ <filename>devtool modify --help</filename> command.
+ </note>
+ </para>
+ </section>
+
+ <section id='devtool-updating-a-recipe'>
+ <title>Updating a Recipe</title>
+
+ <para>
+ Use the <filename>devtool update-recipe</filename> command to
+ update your recipe with patches that reflect changes you make
+ to the source files.
+ For example, if you know you are going to work on some
+ code, you could first use the
+ <link linkend='devtool-modifying-a-recipe'><filename>devtool modify</filename></link>
+ command to extract the code and set up the workspace.
+ After which, you could modify, compile, and test the code.
+ </para>
+
+ <para>
+ When you are satisfied with the results and you have committed
+ your changes to the Git repository, you can then
+ run the <filename>devtool update-recipe</filename> to create the
+ patches and update the recipe:
+ <literallayout class='monospaced'>
+ $ devtool update-recipe <replaceable>recipe</replaceable>
+ </literallayout>
+ If you run the <filename>devtool update-recipe</filename>
+ without committing your changes, the command ignores the
+ changes.
+ </para>
+
+ <para>
+ Often, you might want to apply customizations made to your
+ software in your own layer rather than apply them to the
+ original recipe.
+ If so, you can use the
+ <filename>-a</filename> or <filename>--append</filename>
+ option with the <filename>devtool update-recipe</filename>
+ command.
+ These options allow you to specify the layer into which to
+ write an append file:
+ <literallayout class='monospaced'>
+ $ devtool update-recipe <replaceable>recipe</replaceable> -a <replaceable>base-layer-directory</replaceable>
+ </literallayout>
+ The <filename>*.bbappend</filename> file is created at the
+ appropriate path within the specified layer directory, which
+ may or may not be in your <filename>bblayers.conf</filename>
+ file.
+ If an append file already exists, the command updates it
+ appropriately.
+ <note>
+ For complete syntax, use the
+ <filename>devtool update-recipe --help</filename> command.
+ </note>
+ </para>
+ </section>
+
+ <section id='devtool-resetting-a-recipe'>
+ <title>Resetting a Recipe</title>
+
+ <para>
+ Use the <filename>devtool reset</filename> command to remove a
+ recipe and its configuration (e.g. the corresponding
+ <filename>.bbappend</filename> file) from the workspace layer.
+ Realize that this command deletes the recipe and the
+ append file.
+ The command does not physically move them for you.
+ Consequently, you must be sure to physically relocate your
+ updated recipe and the append file outside of the workspace
+ layer before running the <filename>devtool reset</filename>
+ command.
+ </para>
+
+ <para>
+ If the <filename>devtool reset</filename> command detects that
+ the recipe or the append files have been modified, the
+ command preserves the modified files in a separate "attic"
+ subdirectory under the workspace layer.
+ <note>
+ For complete syntax, use the
+ <filename>devtool reset --help</filename> command.
+ </note>
+ </para>
+ </section>
+
+ <section id='devtool-building-your-software'>
+ <title>Building Your Software</title>
+
+ <para>
+ Use the <filename>devtool build</filename> command to cause the
+ OpenEmbedded build system to build your software based
+ on the recipe file.
+ The <filename>devtool build</filename> command is equivalent to
+ <filename>bitbake -c populate_sysroot</filename>.
+ Here is an example:
+ <literallayout class='monospaced'>
+ $ devtool build <replaceable>recipe</replaceable>
+ </literallayout>
+ <note>
+ For complete syntax, use the
+ <filename>devtool update-recipe --help</filename> command.
+ </note>
+ Building your software using <filename>devtool build</filename>
+ is identical to using BitBake to build the software.
+ </para>
+ </section>
+
+ <section id='devtool-deploying-your-software-on-the-target-machine'>
+ <title>Deploying Your Software on the Target Machine</title>
+
+ <para>
+ Use the <filename>devtool deploy-target</filename> command to
+ deploy the recipe's build output to the live target machine:
+ <literallayout class='monospaced'>
+ $ devtool deploy-target <replaceable>recipe</replaceable> <replaceable>target</replaceable>
+ </literallayout>
+ The <replaceable>target</replaceable> is the address of the
+ target machine, which must be running an SSH server (i.e.
+ <filename>user@hostname[:destdir]</filename>).
+ </para>
+
+ <para>
+ This command deploys all files installed during the
+ <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-install'><filename>do_install</filename></ulink>
+ task.
+ Furthermore, you do not need to have package management enabled
+ within the target machine.
+ If you do, the package manager is bypassed.
+ <note><title>Notes</title>
+ <para>
+ The <filename>deploy-target</filename>
+ functionality is for development only.
+ You should never use it to update an image that will be
+ used in production.
+ </para>
+
+ <para>
+ For complete syntax, use the
+ <filename>devtool deploy-target --help</filename>
+ command.
+ </para>
+ </note>
+ </para>
+ </section>
+
+ <section id='devtool-removing-your-software-from-the-target-machine'>
+ <title>Removing Your Software from the Target Machine</title>
+
+ <para>
+ Use the <filename>devtool undeploy-target</filename> command to
+ remove deployed build output from the target machine.
+ For the <filename>devtool undeploy-target</filename> command to
+ work, you must have previously used the
+ <link linkend='devtool-deploying-your-software-on-the-target-machine'><filename>devtool deploy-target</filename></link>
+ command.
+ <literallayout class='monospaced'>
+ $ devtool undeploy-target <replaceable>recipe</replaceable> <replaceable>target</replaceable>
+ </literallayout>
+ The <replaceable>target</replaceable> is the address of the
+ target machine, which must be running an SSH server (i.e.
+ <filename>user@hostname</filename>).
+ <note>
+ For complete syntax, use the
+ <filename>devtool undeploy-target --help</filename> command.
+ </note>
+ </para>
+ </section>
+
+ <section id='devtool-creating-the-workspace'>
+ <title>Creating the Workspace Layer in an Alternative Location</title>
+
+ <para>
+ Use the <filename>devtool create-workspace</filename> command to
+ create a new workspace layer in your
+ <link linkend='build-directory'>Build Directory</link>.
+ When you create a new workspace layer, it is populated with the
+ <filename>README</filename> file and the
+ <filename>conf</filename> directory only.
+ </para>
+
+ <para>
+ The following example creates a new workspace layer in your
+ current working and by default names the workspace layer
+ "workspace":
+ <literallayout class='monospaced'>
+ $ devtool create-workspace
+ </literallayout>
+ <note>
+ For complete syntax, use the
+ <filename>devtool create-workspace --help</filename> command.
+ </note>
+ </para>
+
+ <para>
+ You can create a workspace layer anywhere by supplying
+ a pathname with the command.
+ The following command creates a new workspace layer named
+ "new-workspace":
+ <literallayout class='monospaced'>
+ $ devtool create-workspace /home/scottrif/new-workspace
+ </literallayout>
+ </para>
+ </section>
+ </section>
+
+ <section id="using-a-quilt-workflow">
+ <title>Using Quilt in Your Workflow</title>
+
+ <para>
+ <ulink url='http://savannah.nongnu.org/projects/quilt'>Quilt</ulink>
+ is a powerful tool that allows you to capture source code changes
+ without having a clean source tree.
+ This section outlines the typical workflow you can use to modify
+ source code, test changes, and then preserve the changes in the
+ form of a patch all using Quilt.
+ <note><title>Tip</title>
+ With regard to preserving changes to source files if you
+ clean a recipe or have <filename>rm_work</filename> enabled,
+ the workflow described in the
+ "<link linkend='using-devtool-in-your-workflow'>Using <filename>devtool</filename> in Your Workflow</link>"
+ section is a safer development flow than than the flow that
+ uses Quilt.
+ </note>
+ </para>
+
+ <para>
+ Follow these general steps:
+ <orderedlist>
+ <listitem><para><emphasis>Find the Source Code:</emphasis>
+ Temporary source code used by the OpenEmbedded build system
+ is kept in the
+ <link linkend='build-directory'>Build Directory</link>.
+ See the
+ "<link linkend='finding-the-temporary-source-code'>Finding Temporary Source Code</link>"
+ section to learn how to locate the directory that has the
+ temporary source code for a particular package.
+ </para></listitem>
+ <listitem><para><emphasis>Change Your Working Directory:</emphasis>
+ You need to be in the directory that has the temporary source code.
+ That directory is defined by the
+ <ulink url='&YOCTO_DOCS_REF_URL;#var-S'><filename>S</filename></ulink>
+ variable.</para></listitem>
+ <listitem><para><emphasis>Create a New Patch:</emphasis>
+ Before modifying source code, you need to create a new patch.
+ To create a new patch file, use <filename>quilt new</filename> as below:
+ <literallayout class='monospaced'>
+ $ quilt new my_changes.patch
+ </literallayout></para></listitem>
+ <listitem><para><emphasis>Notify Quilt and Add Files:</emphasis>
+ After creating the patch, you need to notify Quilt about the files
+ you plan to edit.
+ You notify Quilt by adding the files to the patch you just created:
+ <literallayout class='monospaced'>
+ $ quilt add file1.c file2.c file3.c
+ </literallayout>
+ </para></listitem>
+ <listitem><para><emphasis>Edit the Files:</emphasis>
+ Make your changes in the source code to the files you added
+ to the patch.
+ </para></listitem>
+ <listitem><para><emphasis>Test Your Changes:</emphasis>
+ Once you have modified the source code, the easiest way to
+ your changes is by calling the
+ <filename>do_compile</filename> task as shown in the
+ following example:
+ <literallayout class='monospaced'>
+ $ bitbake -c compile -f <replaceable>package</replaceable>
+ </literallayout>
+ The <filename>-f</filename> or <filename>--force</filename>
+ option forces the specified task to execute.
+ If you find problems with your code, you can just keep editing and
+ re-testing iteratively until things work as expected.
+ <note>All the modifications you make to the temporary source code
+ disappear once you run the
+ <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-clean'><filename>do_clean</filename></ulink>
+ or
+ <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-cleanall'><filename>do_cleanall</filename></ulink>
+ tasks using BitBake (i.e.
+ <filename>bitbake -c clean <replaceable>package</replaceable></filename>
+ and
+ <filename>bitbake -c cleanall <replaceable>package</replaceable></filename>).
+ Modifications will also disappear if you use the <filename>rm_work</filename>
+ feature as described in the
+ "<ulink url='&YOCTO_DOCS_QS_URL;#qs-building-images'>Building Images</ulink>"
+ section of the Yocto Project Quick Start.
+ </note></para></listitem>
+ <listitem><para><emphasis>Generate the Patch:</emphasis>
+ Once your changes work as expected, you need to use Quilt to generate the final patch that
+ contains all your modifications.
+ <literallayout class='monospaced'>
+ $ quilt refresh
+ </literallayout>
+ At this point, the <filename>my_changes.patch</filename> file has all your edits made
+ to the <filename>file1.c</filename>, <filename>file2.c</filename>, and
+ <filename>file3.c</filename> files.</para>
+ <para>You can find the resulting patch file in the <filename>patches/</filename>
+ subdirectory of the source (<filename>S</filename>) directory.</para></listitem>
+ <listitem><para><emphasis>Copy the Patch File:</emphasis>
+ For simplicity, copy the patch file into a directory named <filename>files</filename>,
+ which you can create in the same directory that holds the recipe
+ (<filename>.bb</filename>) file or the
+ append (<filename>.bbappend</filename>) file.
+ Placing the patch here guarantees that the OpenEmbedded build system will find
+ the patch.
+ Next, add the patch into the
+ <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'>SRC_URI</ulink></filename>
+ of the recipe.
+ Here is an example:
+ <literallayout class='monospaced'>
+ SRC_URI += "file://my_changes.patch"
+ </literallayout></para></listitem>
+ </orderedlist>
+ </para>
+ </section>
+
+ <section id='finding-the-temporary-source-code'>
+ <title>Finding Temporary Source Code</title>
+
+ <para>
+ You might find it helpful during development to modify the
+ temporary source code used by recipes to build packages.
+ For example, suppose you are developing a patch and you need to
+ experiment a bit to figure out your solution.
+ After you have initially built the package, you can iteratively
+ tweak the source code, which is located in the
+ <link linkend='build-directory'>Build Directory</link>, and then
+ you can force a re-compile and quickly test your altered code.
+ Once you settle on a solution, you can then preserve your changes
+ in the form of patches.
+ If you are using Quilt for development, see the
+ "<link linkend='using-a-quilt-workflow'>Using Quilt in Your Workflow</link>"
+ section for more information.
+ </para>
+
+ <para>
+ During a build, the unpacked temporary source code used by recipes
+ to build packages is available in the Build Directory as
+ defined by the
+ <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-S'>S</ulink></filename> variable.
+ Below is the default value for the <filename>S</filename> variable as defined in the
+ <filename>meta/conf/bitbake.conf</filename> configuration file in the
+ <link linkend='source-directory'>Source Directory</link>:
+ <literallayout class='monospaced'>
+ S = "${WORKDIR}/${BP}"
+ </literallayout>
+ You should be aware that many recipes override the <filename>S</filename> variable.
+ For example, recipes that fetch their source from Git usually set
+ <filename>S</filename> to <filename>${WORKDIR}/git</filename>.
+ <note>
+ The
+ <ulink url='&YOCTO_DOCS_REF_URL;#var-BP'><filename>BP</filename></ulink>
+ represents the base recipe name, which consists of the name and version:
+ <literallayout class='monospaced'>
+ BP = "${BPN}-${PV}"
+ </literallayout>
+ </note>
+ </para>
+
+ <para>
+ The path to the work directory for the recipe
+ (<ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink>)
+ is defined as follows:
+ <literallayout class='monospaced'>
+ ${TMPDIR}/work/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR}
+ </literallayout>
+ The actual directory depends on several things:
+ <itemizedlist>
+ <listitem><ulink url='&YOCTO_DOCS_REF_URL;#var-TMPDIR'><filename>TMPDIR</filename></ulink>:
+ The top-level build output directory</listitem>
+ <listitem><ulink url='&YOCTO_DOCS_REF_URL;#var-MULTIMACH_TARGET_SYS'><filename>MULTIMACH_TARGET_SYS</filename></ulink>:
+ The target system identifier</listitem>
+ <listitem><ulink url='&YOCTO_DOCS_REF_URL;#var-PN'><filename>PN</filename></ulink>:
+ The recipe name</listitem>
+ <listitem><ulink url='&YOCTO_DOCS_REF_URL;#var-EXTENDPE'><filename>EXTENDPE</filename></ulink>:
+ The epoch - (if
+ <ulink url='&YOCTO_DOCS_REF_URL;#var-PE'><filename>PE</filename></ulink>
+ is not specified, which is usually the case for most
+ recipes, then <filename>EXTENDPE</filename> is blank)</listitem>
+ <listitem><ulink url='&YOCTO_DOCS_REF_URL;#var-PV'><filename>PV</filename></ulink>:
+ The recipe version</listitem>
+ <listitem><ulink url='&YOCTO_DOCS_REF_URL;#var-PR'><filename>PR</filename></ulink>:
+ The recipe revision</listitem>
+ </itemizedlist>
+ </para>
+
+ <para>
+ As an example, assume a Source Directory top-level folder
+ named <filename>poky</filename>, a default Build Directory at
+ <filename>poky/build</filename>, and a
+ <filename>qemux86-poky-linux</filename> machine target
+ system.
+ Furthermore, suppose your recipe is named
+ <filename>foo_1.3.0.bb</filename>.
+ In this case, the work directory the build system uses to
+ build the package would be as follows:
+ <literallayout class='monospaced'>
+ poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0
+ </literallayout>
+ </para>
+
+ <para>
+ Now that you know where to locate the directory that has the
+ temporary source code, you can use a Quilt as described in section
+ "<link linkend='using-a-quilt-workflow'>Using Quilt in Your Workflow</link>"
+ to make your edits, test the changes, and preserve the changes in
+ the form of patches.
+ </para>
+ </section>
+</section>
+
+<section id='image-development-using-toaster'>
+ <title>Image Development Using Toaster</title>
+
+ <para>
+ Toaster is a web interface to the Yocto Project's OpenEmbedded build
+ system.
+ You can initiate builds using Toaster as well as examine the results
+ and statistics of builds.
+ See the
+ <ulink url='&YOCTO_DOCS_TOAST_URL;#toaster-manual-intro'>Toaster User Manual</ulink>
+ for information on how to set up and use Toaster to build images.
+ </para>
+</section>
+
+<section id='image-development-using-hob'>
+ <title>Image Development Using Hob</title>
+
+ <para>
+ The <ulink url='&YOCTO_HOME_URL;/tools-resources/projects/hob'>Hob</ulink> is a graphical user interface for the
+ OpenEmbedded build system, which is based on BitBake.
+ You can use the Hob to build custom operating system images within the Yocto Project build environment.
+ Hob simply provides a friendly interface over the build system used during development.
+ In other words, building images with the Hob lets you take care of common build tasks more easily.
+ </para>
+
+ <para>
+ For a better understanding of Hob, see the project page at
+ <ulink url='&YOCTO_HOME_URL;/tools-resources/projects/hob'></ulink>
+ on the Yocto Project website.
+ If you follow the "Documentation" link from the Hob page, you will
+ find a short introductory training video on Hob.
+ The following lists some features of Hob:
+ <itemizedlist>
+ <listitem><para>You can setup and run Hob using these commands:
+ <literallayout class='monospaced'>
+ $ source oe-init-build-env
+ $ hob
+ </literallayout></para></listitem>
+ <listitem><para>You can set the
+ <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'><filename>MACHINE</filename></ulink>
+ for which you are building the image.</para></listitem>
+ <listitem><para>You can modify various policy settings such as the
+ package format with which to build,
+ the parallelism BitBake uses, whether or not to build an
+ external toolchain, and which host to build against.
+ </para></listitem>
+ <listitem><para>You can manage
+ <link linkend='understanding-and-creating-layers'>layers</link>.</para></listitem>
+ <listitem><para>You can select a base image and then add extra packages for your custom build.
+ </para></listitem>
+ <listitem><para>You can launch and monitor the build from within Hob.</para></listitem>
+ </itemizedlist>
+ </para>
+</section>
+
+<section id="platdev-appdev-devshell">
+ <title>Using a Development Shell</title>
+
+ <para>
+ When debugging certain commands or even when just editing packages,
+ <filename>devshell</filename> can be a useful tool.
+ When you invoke <filename>devshell</filename>, source files are
+ extracted into your working directory and patches are applied.
+ Then, a new terminal is opened and you are placed in the working directory.
+ In the new terminal, all the OpenEmbedded build-related environment variables are
+ still defined so you can use commands such as <filename>configure</filename> and
+ <filename>make</filename>.
+ The commands execute just as if the OpenEmbedded build system were executing them.
+ Consequently, working this way can be helpful when debugging a build or preparing
+ software to be used with the OpenEmbedded build system.
+ </para>
+
+ <para>
+ Following is an example that uses <filename>devshell</filename> on a target named
+ <filename>matchbox-desktop</filename>:
+ <literallayout class='monospaced'>
+ $ bitbake matchbox-desktop -c devshell
+ </literallayout>
+ </para>
+
+ <para>
+ This command spawns a terminal with a shell prompt within the OpenEmbedded build environment.
+ The <ulink url='&YOCTO_DOCS_REF_URL;#var-OE_TERMINAL'><filename>OE_TERMINAL</filename></ulink>
+ variable controls what type of shell is opened.
+ </para>
+
+ <para>
+ For spawned terminals, the following occurs:
+ <itemizedlist>
+ <listitem><para>The <filename>PATH</filename> variable includes the
+ cross-toolchain.</para></listitem>
+ <listitem><para>The <filename>pkgconfig</filename> variables find the correct
+ <filename>.pc</filename> files.</para></listitem>
+ <listitem><para>The <filename>configure</filename> command finds the
+ Yocto Project site files as well as any other necessary files.</para></listitem>
+ </itemizedlist>
+ </para>
+
+ <para>
+ Within this environment, you can run configure or compile
+ commands as if they were being run by
+ the OpenEmbedded build system itself.
+ As noted earlier, the working directory also automatically changes to the
+ Source Directory (<ulink url='&YOCTO_DOCS_REF_URL;#var-S'><filename>S</filename></ulink>).
+ </para>
+
+ <para>
+ When you are finished, you just exit the shell or close the terminal window.
+ </para>
+
+ <note>
+ <para>
+ It is worth remembering that when using <filename>devshell</filename>
+ you need to use the full compiler name such as <filename>arm-poky-linux-gnueabi-gcc</filename>
+ instead of just using <filename>gcc</filename>.
+ The same applies to other applications such as <filename>binutils</filename>,
+ <filename>libtool</filename> and so forth.
+ BitBake sets up environment variables such as <filename>CC</filename>
+ to assist applications, such as <filename>make</filename> to find the correct tools.
+ </para>
+
+ <para>
+ It is also worth noting that <filename>devshell</filename> still works over
+ X11 forwarding and similar situations.
+ </para>
+ </note>
+</section>
+
+</chapter>