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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='sdk-extensible'>
- <title>Using the Extensible SDK</title>
- <para>
- This chapter describes the extensible SDK and how to install it.
- Information covers the pieces of the SDK, how to install it, and
- presents a look at using the <filename>devtool</filename>
- functionality.
- The extensible SDK makes it easy to add new applications and libraries
- to an image, modify the source for an existing component, test
- changes on the target hardware, and ease integration into the rest of
- the
- <ulink url='&YOCTO_DOCS_REF_URL;#build-system-term'>OpenEmbedded build system</ulink>.
- <note>
- For a side-by-side comparison of main features supported for an
- extensible SDK as compared to a standard SDK, see the
- "<link linkend='sdk-manual-intro'>Introduction</link>"
- section.
- </note>
- </para>
- <para>
- In addition to the functionality available through
- <filename>devtool</filename>, you can alternatively make use of the
- toolchain directly, for example from Makefile, Autotools, and
- <trademark class='trade'>Eclipse</trademark>-based projects.
- See the
- "<link linkend='sdk-working-projects'>Using the SDK Toolchain Directly</link>"
- chapter for more information.
- </para>
- <section id='sdk-extensible-sdk-intro'>
- <title>Why use the Extensible SDK and What is in It?</title>
- <para>
- The extensible SDK provides a cross-development toolchain and
- libraries tailored to the contents of a specific image.
- You would use the Extensible SDK if you want a toolchain experience
- supplemented with the powerful set of <filename>devtool</filename>
- commands tailored for the Yocto Project environment.
- </para>
- <para>
- The installed extensible SDK consists of several files and
- directories.
- Basically, it contains an SDK environment setup script, some
- configuration files, an internal build system, and the
- <filename>devtool</filename> functionality.
- </para>
- </section>
- <section id='sdk-setting-up-to-use-the-extensible-sdk'>
- <title>Setting Up to Use the Extensible SDK</title>
- <para>
- The first thing you need to do is install the SDK on your host
- development machine by running the <filename>*.sh</filename>
- installation script.
- </para>
- <para>
- You can download a tarball installer, which includes the
- pre-built toolchain, the <filename>runqemu</filename>
- script, the internal build system, <filename>devtool</filename>,
- and support files from the appropriate directory under
- <ulink url='&YOCTO_TOOLCHAIN_DL_URL;'></ulink>.
- Toolchains are available for 32-bit and 64-bit x86 development
- systems from the <filename>i686</filename> and
- <filename>x86_64</filename> directories, respectively.
- The toolchains the Yocto Project provides are based off the
- <filename>core-image-sato</filename> image and contain
- libraries appropriate for developing against that image.
- Each type of development system supports five or more target
- architectures.
- </para>
- <para>
- The names of the tarball installer scripts are such that a
- string representing the host system appears first in the
- filename and then is immediately followed by a string
- representing the target architecture.
- An extensible SDK has the string "-ext" as part of the name.
- <literallayout class='monospaced'>
- poky-glibc-<replaceable>host_system</replaceable>-<replaceable>image_type</replaceable>-<replaceable>arch</replaceable>-toolchain-ext-<replaceable>release_version</replaceable>.sh
- Where:
- <replaceable>host_system</replaceable> is a string representing your development system:
- i686 or x86_64.
- <replaceable>image_type</replaceable> is the image for which the SDK was built.
- <replaceable>arch</replaceable> is a string representing the tuned target architecture:
- i586, x86_64, powerpc, mips, armv7a or armv5te
- <replaceable>release_version</replaceable> is a string representing the release number of the
- Yocto Project:
- &DISTRO;, &DISTRO;+snapshot
- </literallayout>
- For example, the following SDK installer is for a 64-bit
- development host system and a i586-tuned target architecture
- based off the SDK for <filename>core-image-sato</filename> and
- using the current &DISTRO; snapshot:
- <literallayout class='monospaced'>
- poky-glibc-x86_64-core-image-sato-i586-toolchain-ext-&DISTRO;.sh
- </literallayout>
- <note>
- As an alternative to downloading an SDK, you can build the
- SDK installer.
- For information on building the installer, see the
- "<link linkend='sdk-building-an-sdk-installer'>Building an SDK Installer</link>"
- section.
- Another helpful resource for building an installer is the
- <ulink url='https://wiki.yoctoproject.org/wiki/TipsAndTricks/RunningEclipseAgainstBuiltImage'>Cookbook guide to Making an Eclipse Debug Capable Image</ulink>
- wiki page.
- This wiki page focuses on development when using the Eclipse
- IDE.
- </note>
- </para>
- <para>
- The SDK and toolchains are self-contained and by default are
- installed into the <filename>poky_sdk</filename> folder in your
- home directory.
- You can choose to install the extensible SDK in any location when
- you run the installer.
- However, the location you choose needs to be writable for whichever
- users need to use the SDK, since files will need to be written
- under that directory during the normal course of operation.
- </para>
- <para>
- The following command shows how to run the installer given a
- toolchain tarball for a 64-bit x86 development host system and
- a 64-bit x86 target architecture.
- The example assumes the SDK installer is located in
- <filename>~/Downloads/</filename>.
- <note>
- If you do not have write permissions for the directory
- into which you are installing the SDK, the installer
- notifies you and exits.
- Be sure you have write permissions in the directory and
- run the installer again.
- </note>
- <literallayout class='monospaced'>
- $ ./poky-glibc-x86_64-core-image-minimal-core2-64-toolchain-ext-&DISTRO;.sh
- Poky (Yocto Project Reference Distro) Extensible SDK installer version &DISTRO;
- ===================================================================================
- Enter target directory for SDK (default: ~/poky_sdk):
- You are about to install the SDK to "/home/scottrif/poky_sdk". Proceed[Y/n]? Y
- Extracting SDK......................................................................done
- Setting it up...
- Extracting buildtools...
- Preparing build system...
- done
- SDK has been successfully set up and is ready to be used.
- Each time you wish to use the SDK in a new shell session, you need to source the environment setup script e.g.
- $ . /home/scottrif/poky_sdk/environment-setup-core2-64-poky-linux
- </literallayout>
- </para>
- </section>
- <section id='sdk-running-the-extensible-sdk-environment-setup-script'>
- <title>Running the Extensible SDK Environment Setup Script</title>
- <para>
- Once you have the SDK installed, you must run the SDK environment
- setup script before you can actually use it.
- This setup script resides in the directory you chose when you
- installed the SDK, which is either the default
- <filename>poky_sdk</filename> directory or the directory you
- chose during installation.
- </para>
- <para>
- Before running the script, be sure it is the one that matches the
- architecture for which you are developing.
- Environment setup scripts begin with the string
- "<filename>environment-setup</filename>" and include as part of
- their name the tuned target architecture.
- As an example, the following commands set the working directory
- to where the SDK was installed and then source the environment
- setup script.
- In this example, the setup script is for an IA-based
- target machine using i586 tuning:
- <literallayout class='monospaced'>
- $ cd /home/scottrif/poky_sdk
- $ source environment-setup-core2-64-poky-linux
- SDK environment now set up; additionally you may now run devtool to perform development tasks.
- Run devtool --help for further details.
- </literallayout>
- When you run the setup script, many environment variables are
- defined:
- <literallayout class='monospaced'>
- <ulink url='&YOCTO_DOCS_REF_URL;#var-SDKTARGETSYSROOT'><filename>SDKTARGETSYSROOT</filename></ulink> - The path to the sysroot used for cross-compilation
- <ulink url='&YOCTO_DOCS_REF_URL;#var-PKG_CONFIG_PATH'><filename>PKG_CONFIG_PATH</filename></ulink> - The path to the target pkg-config files
- <ulink url='&YOCTO_DOCS_REF_URL;#var-CONFIG_SITE'><filename>CONFIG_SITE</filename></ulink> - A GNU autoconf site file preconfigured for the target
- <ulink url='&YOCTO_DOCS_REF_URL;#var-CC'><filename>CC</filename></ulink> - The minimal command and arguments to run the C compiler
- <ulink url='&YOCTO_DOCS_REF_URL;#var-CXX'><filename>CXX</filename></ulink> - The minimal command and arguments to run the C++ compiler
- <ulink url='&YOCTO_DOCS_REF_URL;#var-CPP'><filename>CPP</filename></ulink> - The minimal command and arguments to run the C preprocessor
- <ulink url='&YOCTO_DOCS_REF_URL;#var-AS'><filename>AS</filename></ulink> - The minimal command and arguments to run the assembler
- <ulink url='&YOCTO_DOCS_REF_URL;#var-LD'><filename>LD</filename></ulink> - The minimal command and arguments to run the linker
- <ulink url='&YOCTO_DOCS_REF_URL;#var-GDB'><filename>GDB</filename></ulink> - The minimal command and arguments to run the GNU Debugger
- <ulink url='&YOCTO_DOCS_REF_URL;#var-STRIP'><filename>STRIP</filename></ulink> - The minimal command and arguments to run 'strip', which strips symbols
- <ulink url='&YOCTO_DOCS_REF_URL;#var-RANLIB'><filename>RANLIB</filename></ulink> - The minimal command and arguments to run 'ranlib'
- <ulink url='&YOCTO_DOCS_REF_URL;#var-OBJCOPY'><filename>OBJCOPY</filename></ulink> - The minimal command and arguments to run 'objcopy'
- <ulink url='&YOCTO_DOCS_REF_URL;#var-OBJDUMP'><filename>OBJDUMP</filename></ulink> - The minimal command and arguments to run 'objdump'
- <ulink url='&YOCTO_DOCS_REF_URL;#var-AR'><filename>AR</filename></ulink> - The minimal command and arguments to run 'ar'
- <ulink url='&YOCTO_DOCS_REF_URL;#var-NM'><filename>NM</filename></ulink> - The minimal command and arguments to run 'nm'
- <ulink url='&YOCTO_DOCS_REF_URL;#var-TARGET_PREFIX'><filename>TARGET_PREFIX</filename></ulink> - The toolchain binary prefix for the target tools
- <ulink url='&YOCTO_DOCS_REF_URL;#var-CROSS_COMPILE'><filename>CROSS_COMPILE</filename></ulink> - The toolchain binary prefix for the target tools
- <ulink url='&YOCTO_DOCS_REF_URL;#var-CONFIGURE_FLAGS'><filename>CONFIGURE_FLAGS</filename></ulink> - The minimal arguments for GNU configure
- <ulink url='&YOCTO_DOCS_REF_URL;#var-CFLAGS'><filename>CFLAGS</filename></ulink> - Suggested C flags
- <ulink url='&YOCTO_DOCS_REF_URL;#var-CXXFLAGS'><filename>CXXFLAGS</filename></ulink> - Suggested C++ flags
- <ulink url='&YOCTO_DOCS_REF_URL;#var-LDFLAGS'><filename>LDFLAGS</filename></ulink> - Suggested linker flags when you use CC to link
- <ulink url='&YOCTO_DOCS_REF_URL;#var-CPPFLAGS'><filename>CPPFLAGS</filename></ulink> - Suggested preprocessor flags
- </literallayout>
- </para>
- </section>
- <section id='using-devtool-in-your-sdk-workflow'>
- <title>Using <filename>devtool</filename> in Your SDK Workflow</title>
- <para>
- The cornerstone of the extensible SDK is a command-line tool
- called <filename>devtool</filename>.
- This tool provides a number of features that help
- you build, test and package software within the extensible SDK, and
- optionally integrate it into an image built by the OpenEmbedded
- build system.
- <note><title>Tip</title>
- The use of <filename>devtool</filename> is not limited to
- the extensible SDK.
- You can use <filename>devtool</filename> to help you easily
- develop any project whose build output must be part of an
- image built using the OpenEmbedded build system.
- </note>
- </para>
- <para>
- The <filename>devtool</filename> command line is organized
- similarly to
- <ulink url='&YOCTO_DOCS_OM_URL;#git'>Git</ulink> in that it
- has a number of sub-commands for each function.
- You can run <filename>devtool --help</filename> to see all the
- commands.
- <note>
- See the
- "<ulink url='&YOCTO_DOCS_REF_URL;#ref-devtool-reference'><filename>devtool</filename> Quick Reference</ulink>"
- in the Yocto Project Reference Manual for a
- <filename>devtool</filename> quick reference.
- </note>
- </para>
- <para>
- Three <filename>devtool</filename> subcommands that provide
- entry-points into development are:
- <itemizedlist>
- <listitem><para>
- <emphasis><filename>devtool add</filename></emphasis>:
- Assists in adding new software to be built.
- </para></listitem>
- <listitem><para>
- <emphasis><filename>devtool modify</filename></emphasis>:
- Sets up an environment to enable you to modify the source of
- an existing component.
- </para></listitem>
- <listitem><para>
- <emphasis><filename>devtool upgrade</filename></emphasis>:
- Updates an existing recipe so that you can build it for
- an updated set of source files.
- </para></listitem>
- </itemizedlist>
- As with the OpenEmbedded build system, "recipes" represent software
- packages within <filename>devtool</filename>.
- When you use <filename>devtool add</filename>, a recipe is
- automatically created.
- When you use <filename>devtool modify</filename>, the specified
- existing recipe is used in order to determine where to get the source
- code and how to patch it.
- In both cases, an environment is set up so that when you build the
- recipe a source tree that is under your control is used in order to
- allow you to make changes to the source as desired.
- By default, both new recipes and the source go into a "workspace"
- directory under the SDK.
- </para>
- <para>
- The remainder of this section presents the
- <filename>devtool add</filename>,
- <filename>devtool modify</filename>, and
- <filename>devtool upgrade</filename> workflows.
- </para>
- <section id='sdk-use-devtool-to-add-an-application'>
- <title>Use <filename>devtool add</filename> to Add an Application</title>
- <para>
- The <filename>devtool add</filename> command generates
- a new recipe based on existing source code.
- This command takes advantage of the
- <ulink url='&YOCTO_DOCS_REF_URL;#devtool-the-workspace-layer-structure'>workspace</ulink>
- layer that many <filename>devtool</filename> commands
- use.
- The command is flexible enough to allow you to extract source
- code into both the workspace or a separate local Git repository
- and to use existing code that does not need to be extracted.
- </para>
- <para>
- Depending on your particular scenario, the arguments and options
- you use with <filename>devtool add</filename> form different
- combinations.
- The following diagram shows common development flows
- you would use with the <filename>devtool add</filename>
- command:
- </para>
- <para>
- <imagedata fileref="figures/sdk-devtool-add-flow.png" align="center" />
- </para>
- <para>
- <orderedlist>
- <listitem><para><emphasis>Generating the New Recipe</emphasis>:
- The top part of the flow shows three scenarios by which
- you could use <filename>devtool add</filename> to
- generate a recipe based on existing source code.</para>
- <para>In a shared development environment, it is
- typical where other developers are responsible for
- various areas of source code.
- As a developer, you are probably interested in using
- that source code as part of your development using
- the Yocto Project.
- All you need is access to the code, a recipe, and a
- controlled area in which to do your work.</para>
- <para>Within the diagram, three possible scenarios
- feed into the <filename>devtool add</filename> workflow:
- <itemizedlist>
- <listitem><para><emphasis>Left</emphasis>:
- The left scenario represents a common situation
- where the source code does not exist locally
- and needs to be extracted.
- In this situation, you just let it get
- extracted to the default workspace - you do not
- want it in some specific location outside of the
- workspace.
- Thus, everything you need will be located in the
- workspace:
- <literallayout class='monospaced'>
- $ devtool add <replaceable>recipe fetchuri</replaceable>
- </literallayout>
- With this command, <filename>devtool</filename>
- creates a recipe and an append file in the
- workspace as well as extracts the upstream
- source files into a local Git repository also
- within the <filename>sources</filename> folder.
- </para></listitem>
- <listitem><para><emphasis>Middle</emphasis>:
- The middle scenario also represents a situation where
- the source code does not exist locally.
- In this case, the code is again upstream
- and needs to be extracted to some
- local area - this time outside of the default
- workspace.
- If required, <filename>devtool</filename>
- always creates
- a Git repository locally during the extraction.
- Furthermore, the first positional argument
- <replaceable>srctree</replaceable> in this case
- identifies where the
- <filename>devtool add</filename> command
- will locate the extracted code outside of the
- workspace:
- <literallayout class='monospaced'>
- $ devtool add <replaceable>recipe srctree fetchuri</replaceable>
- </literallayout>
- In summary, the source code is pulled from
- <replaceable>fetchuri</replaceable> and extracted
- into the location defined by
- <replaceable>srctree</replaceable> as a local
- Git repository.</para>
- <para>Within workspace, <filename>devtool</filename>
- creates both the recipe and an append file
- for the recipe.
- </para></listitem>
- <listitem><para><emphasis>Right</emphasis>:
- The right scenario represents a situation
- where the source tree (srctree) has been
- previously prepared outside of the
- <filename>devtool</filename> workspace.
- </para>
- <para>The following command names the recipe
- and identifies where the existing source tree
- is located:
- <literallayout class='monospaced'>
- $ devtool add <replaceable>recipe srctree</replaceable>
- </literallayout>
- The command examines the source code and creates
- a recipe for it placing the recipe into the
- workspace.</para>
- <para>Because the extracted source code already exists,
- <filename>devtool</filename> does not try to
- relocate it into the workspace - just the new
- the recipe is placed in the workspace.</para>
- <para>Aside from a recipe folder, the command
- also creates an append folder and places an initial
- <filename>*.bbappend</filename> within.
- </para></listitem>
- </itemizedlist>
- </para></listitem>
- <listitem><para><emphasis>Edit the Recipe</emphasis>:
- At this point, you can use <filename>devtool edit-recipe</filename>
- to open up the editor as defined by the
- <filename>$EDITOR</filename> environment variable
- and modify the file:
- <literallayout class='monospaced'>
- $ devtool edit-recipe <replaceable>recipe</replaceable>
- </literallayout>
- From within the editor, you can make modifications to the
- recipe that take affect when you build it later.
- </para></listitem>
- <listitem><para><emphasis>Build the Recipe or Rebuild the Image</emphasis>:
- At this point in the flow, the next step you
- take depends on what you are going to do with
- the new code.</para>
- <para>If you need to take the build output and eventually
- move it to the target hardware, you would use
- <filename>devtool build</filename>:
- <literallayout class='monospaced'>
- $ devtool build <replaceable>recipe</replaceable>
- </literallayout></para>
- <para>On the other hand, if you want an image to
- contain the recipe's packages for immediate deployment
- onto a device (e.g. for testing purposes), you can use
- the <filename>devtool build-image</filename> command:
- <literallayout class='monospaced'>
- $ devtool build-image <replaceable>image</replaceable>
- </literallayout>
- </para></listitem>
- <listitem><para><emphasis>Deploy the Build Output</emphasis>:
- When you use the <filename>devtool build</filename>
- command to build out your recipe, you probably want to
- see if the resulting build output works as expected on target
- hardware.
- <note>
- This step assumes 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.
- </note>
- You can deploy your build output to that target hardware by
- using the <filename>devtool deploy-target</filename> command:
- <literallayout class='monospaced'>
- $ devtool deploy-target <replaceable>recipe target</replaceable>
- </literallayout>
- The <replaceable>target</replaceable> is a live target machine
- running as an SSH server.</para>
- <para>You can, of course, also deploy the image you build
- using the <filename>devtool build-image</filename> command
- to actual hardware.
- However, <filename>devtool</filename> does not provide a
- specific command that allows you to do this.
- </para></listitem>
- <listitem><para>
- <emphasis>Finish Your Work With the Recipe</emphasis>:
- The <filename>devtool finish</filename> command creates
- any patches corresponding to commits in the local
- Git repository, moves the new recipe to a more permanent
- layer, and then resets the recipe so that the recipe is
- built normally rather than from the workspace.
- <literallayout class='monospaced'>
- $ devtool finish <replaceable>recipe layer</replaceable>
- </literallayout>
- <note>
- Any changes you want to turn into patches must be
- committed to the Git repository in the source tree.
- </note></para>
- <para>As mentioned, the <filename>devtool finish</filename>
- command moves the final recipe to its permanent layer.
- </para>
- <para>As a final process of the
- <filename>devtool finish</filename> command, the state
- of the standard layers and the upstream source is
- restored so that you can build the recipe from those
- areas rather than the workspace.
- <note>
- You can use the <filename>devtool reset</filename>
- command to put things back should you decide you
- do not want to proceed with your work.
- If you do use this command, realize that the source
- tree is preserved.
- </note>
- </para></listitem>
- </orderedlist>
- </para>
- </section>
- <section id='sdk-devtool-use-devtool-modify-to-modify-the-source-of-an-existing-component'>
- <title>Use <filename>devtool modify</filename> to Modify the Source of an Existing Component</title>
- <para>
- The <filename>devtool modify</filename> command prepares the
- way to work on existing code that already has a recipe in
- place.
- The command is flexible enough to allow you to extract code,
- specify the existing recipe, and keep track of and gather any
- patch files from other developers that are
- associated with the code.
- </para>
- <para>
- Depending on your particular scenario, the arguments and options
- you use with <filename>devtool modify</filename> form different
- combinations.
- The following diagram shows common development flows
- you would use with the <filename>devtool modify</filename>
- command:
- </para>
- <para>
- <imagedata fileref="figures/sdk-devtool-modify-flow.png" align="center" />
- </para>
- <para>
- <orderedlist>
- <listitem><para><emphasis>Preparing to Modify the Code</emphasis>:
- The top part of the flow shows three scenarios by which
- you could use <filename>devtool modify</filename> to
- prepare to work on source files.
- Each scenario assumes the following:
- <itemizedlist>
- <listitem><para>The recipe exists in some layer external
- to the <filename>devtool</filename> workspace.
- </para></listitem>
- <listitem><para>The source files exist upstream in an
- un-extracted state or locally in a previously
- extracted state.
- </para></listitem>
- </itemizedlist>
- The typical situation is where another developer has
- created some layer for use with the Yocto Project and
- their recipe already resides in that layer.
- Furthermore, their source code is readily available
- either upstream or locally.
- <itemizedlist>
- <listitem><para><emphasis>Left</emphasis>:
- The left scenario represents a common situation
- where the source code does not exist locally
- and needs to be extracted.
- In this situation, the source is extracted
- into the default workspace location.
- The recipe, in this scenario, is in its own
- layer outside the workspace
- (i.e.
- <filename>meta-</filename><replaceable>layername</replaceable>).
- </para>
- <para>The following command identifies the recipe
- and by default extracts the source files:
- <literallayout class='monospaced'>
- $ devtool modify <replaceable>recipe</replaceable>
- </literallayout>
- Once <filename>devtool</filename>locates the recipe,
- it uses the
- <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>
- variable to locate the source code and
- any local patch files from other developers are
- located.
- <note>
- You cannot provide an URL for
- <replaceable>srctree</replaceable> when using the
- <filename>devtool modify</filename> command.
- </note>
- With this scenario, however, since no
- <replaceable>srctree</replaceable> argument exists, the
- <filename>devtool modify</filename> command by default
- extracts the source files to a Git structure.
- Furthermore, the location for the extracted source is the
- default area within the workspace.
- The result is that the command sets up both the source
- code and an append file within the workspace with the
- recipe remaining in its original location.
- </para></listitem>
- <listitem><para><emphasis>Middle</emphasis>:
- The middle scenario represents a situation where
- the source code also does not exist locally.
- In this case, the code is again upstream
- and needs to be extracted to some
- local area as a Git repository.
- The recipe, in this scenario, is again in its own
- layer outside the workspace.</para>
- <para>The following command tells
- <filename>devtool</filename> what recipe with
- which to work and, in this case, identifies a local
- area for the extracted source files that is outside
- of the default workspace:
- <literallayout class='monospaced'>
- $ devtool modify <replaceable>recipe srctree</replaceable>
- </literallayout>
- As with all extractions, the command uses
- the recipe's <filename>SRC_URI</filename> to locate the
- source files.
- Once the files are located, the command by default
- extracts them.
- Providing the <replaceable>srctree</replaceable>
- argument instructs <filename>devtool</filename> where
- to place the extracted source.</para>
- <para>Within workspace, <filename>devtool</filename>
- creates an append file for the recipe.
- The recipe remains in its original location but
- the source files are extracted to the location you
- provided with <replaceable>srctree</replaceable>.
- </para></listitem>
- <listitem><para><emphasis>Right</emphasis>:
- The right scenario represents a situation
- where the source tree
- (<replaceable>srctree</replaceable>) exists as a
- previously extracted Git structure outside of
- the <filename>devtool</filename> workspace.
- In this example, the recipe also exists
- elsewhere in its own layer.
- </para>
- <para>The following command tells
- <filename>devtool</filename> the recipe
- with which to work, uses the "-n" option to indicate
- source does not need to be extracted, and uses
- <replaceable>srctree</replaceable> to point to the
- previously extracted source files:
- <literallayout class='monospaced'>
- $ devtool modify -n <replaceable>recipe srctree</replaceable>
- </literallayout>
- </para>
- <para>Once the command finishes, it creates only
- an append file for the recipe in the workspace.
- The recipe and the source code remain in their
- original locations.
- </para></listitem>
- </itemizedlist>
- </para></listitem>
- <listitem><para><emphasis>Edit the Source</emphasis>:
- Once you have used the <filename>devtool modify</filename>
- command, you are free to make changes to the source
- files.
- You can use any editor you like to make and save
- your source code modifications.
- </para></listitem>
- <listitem><para><emphasis>Build the Recipe</emphasis>:
- Once you have updated the source files, you can build
- the recipe.
- </para></listitem>
- <listitem><para><emphasis>Deploy the Build Output</emphasis>:
- When you use the <filename>devtool build</filename>
- command to build out your recipe, you probably want to see
- if the resulting build output works as expected on target
- hardware.
- <note>
- This step assumes 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.
- </note>
- You can deploy your build output to that target hardware by
- using the <filename>devtool deploy-target</filename> command:
- <literallayout class='monospaced'>
- $ devtool deploy-target <replaceable>recipe target</replaceable>
- </literallayout>
- The <replaceable>target</replaceable> is a live target machine
- running as an SSH server.</para>
- <para>You can, of course, also deploy the image you build
- using the <filename>devtool build-image</filename> command
- to actual hardware.
- However, <filename>devtool</filename> does not provide a
- specific command that allows you to do this.
- </para></listitem>
- <listitem><para>
- <emphasis>Finish Your Work With the Recipe</emphasis>:
- The <filename>devtool finish</filename> command creates
- any patches corresponding to commits in the local
- Git repository, updates the recipe to point to them
- (or creates a <filename>.bbappend</filename> file to do
- so, depending on the specified destination layer), and
- then resets the recipe so that the recipe is built normally
- rather than from the workspace.
- <literallayout class='monospaced'>
- $ devtool finish <replaceable>recipe layer</replaceable>
- </literallayout>
- <note>
- Any changes you want to turn into patches must be
- committed to the Git repository in the source tree.
- </note></para>
- <para>Because there is no need to move the recipe,
- <filename>devtool finish</filename> either updates the
- original recipe in the original layer or the command
- creates a <filename>.bbappend</filename> in a different
- layer as provided by <replaceable>layer</replaceable>.
- </para>
- <para>As a final process of the
- <filename>devtool finish</filename> command, the state
- of the standard layers and the upstream source is
- restored so that you can build the recipe from those
- areas rather than the workspace.
- <note>
- You can use the <filename>devtool reset</filename>
- command to put things back should you decide you
- do not want to proceed with your work.
- If you do use this command, realize that the source
- tree is preserved.
- </note>
- </para></listitem>
- </orderedlist>
- </para>
- </section>
- <section id='sdk-devtool-use-devtool-upgrade-to-create-a-version-of-the-recipe-that-supports-a-newer-version-of-the-software'>
- <title>Use <filename>devtool upgrade</filename> to Create a Version of the Recipe that Supports a Newer Version of the Software</title>
- <para>
- The <filename>devtool upgrade</filename> command upgrades
- an existing recipe to that of a more up-to-date version
- found upstream.
- Throughout the life of software, recipes continually undergo
- version upgrades by their upstream publishers.
- You can use the <filename>devtool upgrade</filename>
- workflow to make sure your recipes you are using for builds
- are up-to-date with their upstream counterparts.
- <note>
- Several methods exist by which you can upgrade recipes.
- <filename>devtool upgrade</filename> happens to be one.
- You can read about all the methods by which you can
- upgrade recipes in the
- "<ulink url='&YOCTO_DOCS_DEV_URL;#gs-upgrading-recipes'>Upgrading Recipes</ulink>"
- section of the Yocto Project Development Tasks Manual.
- </note>
- </para>
- <para>
- The <filename>devtool upgrade</filename> command is flexible
- enough to allow you to specify source code revision and
- versioning schemes, extract code into or out of the
- <filename>devtool</filename>
- <ulink url='&YOCTO_DOCS_REF_URL;#devtool-the-workspace-layer-structure'>workspace</ulink>,
- and work with any source file forms that the fetchers support.
- </para>
- <para>
- Depending on your particular scenario, the arguments and
- options you use with <filename>devtool upgrade</filename> form
- different combinations.
- The following diagram shows a common development flow
- you would use with the <filename>devtool upgrade</filename>
- command:
- </para>
- <para>
- <imagedata fileref="figures/sdk-devtool-upgrade-flow.png" align="center" />
- </para>
- <para>
- <orderedlist>
- <listitem><para>
- <emphasis>Initiate the Upgrade</emphasis>:
- The top part of the flow shows a typical scenario by
- which you could use
- <filename>devtool upgrade</filename>.
- The following conditions exist:
- <itemizedlist>
- <listitem><para>
- The recipe exists in some layer external
- to the <filename>devtool</filename> workspace.
- </para></listitem>
- <listitem><para>
- The source files for the new release
- exist adjacent to the same location pointed to
- by
- <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>
- in the recipe (e.g. a tarball with the new
- version number in the name, or as a different
- revision in the upstream Git repository).
- </para></listitem>
- </itemizedlist>
- A common situation is where third-party software has
- undergone a revision so that it has been upgraded.
- The recipe you have access to is likely in your own
- layer.
- Thus, you need to upgrade the recipe to use the
- newer version of the software:
- <literallayout class='monospaced'>
- $ devtool upgrade -V <replaceable>version recipe</replaceable>
- </literallayout>
- By default, the <filename>devtool upgrade</filename>
- command extracts source code into the
- <filename>sources</filename> directory in the
- <ulink url='&YOCTO_DOCS_REF_URL;#devtool-the-workspace-layer-structure'>workspace</ulink>.
- If you want the code extracted to any other location,
- you need to provide the
- <replaceable>srctree</replaceable> positional argument
- with the command as follows:
- <literallayout class='monospaced'>
- $ devtool upgrade -V <replaceable>version recipe srctree</replaceable>
- </literallayout>
- <note>
- In this example, the "-V" option specifies the new
- version.
- If you don't use "-V", the command upgrades the
- recipe to the latest version.
- </note>
- If the source files pointed to by the
- <filename>SRC_URI</filename> statement in the recipe
- are in a Git repository, you must provide the "-S"
- option and specify a revision for the software.</para>
- <para>Once <filename>devtool</filename> locates the
- recipe, it uses the <filename>SRC_URI</filename>
- variable to locate the source code and any local patch
- files from other developers are located.
- The result is that the command sets up the source
- code, the new version of the recipe, and an append file
- all within the workspace.
- </para></listitem>
- <listitem><para><emphasis>
- Resolve any Conflicts created by the Upgrade</emphasis>:
- At this point, conflicts could exist due to the
- software being upgraded to a new version.
- Conflicts occur if your recipe specifies some patch
- files in <filename>SRC_URI</filename> that conflict
- with changes made in the new version of the software.
- If this is the case, you need to resolve the conflicts
- by editing the source and following the normal
- <filename>git rebase</filename> conflict resolution
- process.</para>
- <para>Before moving onto the next step, be sure to
- resolve any such conflicts created through use of a
- newer or different version of the software.
- </para></listitem>
- <listitem><para>
- <emphasis>Build the Recipe</emphasis>:
- Once you have your recipe in order, you can build it.
- You can either use <filename>devtool build</filename>
- or <filename>bitbake</filename>.
- Either method produces build output that is stored
- in
- <ulink url='&YOCTO_DOCS_REF_URL;#var-TMPDIR'><filename>TMPDIR</filename></ulink>.
- </para></listitem>
- <listitem><para>
- <emphasis>Deploy the Build Output</emphasis>:
- When you use the <filename>devtool build</filename>
- command or <filename>bitbake</filename> to build
- your recipe, you probably want to see if the resulting
- build output works as expected on target hardware.
- <note>
- This step assumes 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.
- </note>
- You can deploy your build output to that target
- hardware by using the
- <filename>devtool deploy-target</filename> command:
- <literallayout class='monospaced'>
- $ devtool deploy-target <replaceable>recipe target</replaceable>
- </literallayout>
- The <replaceable>target</replaceable> is a live target
- machine running as an SSH server.</para>
- <para>You can, of course, also deploy the image you
- build using the
- <filename>devtool build-image</filename> command
- to actual hardware.
- However, <filename>devtool</filename> does not provide
- a specific command that allows you to do this.
- </para></listitem>
- <listitem><para>
- <emphasis>Finish Your Work With the Recipe</emphasis>:
- The <filename>devtool finish</filename> command creates
- any patches corresponding to commits in the local
- Git repository, moves the new recipe to a more
- permanent layer, and then resets the recipe so that
- the recipe is built normally rather than from the
- workspace.
- If you specify a destination layer that is the same as
- the original source, then the old version of the
- recipe and associated files will be removed prior to
- adding the new version.
- <literallayout class='monospaced'>
- $ devtool finish <replaceable>recipe layer</replaceable>
- </literallayout>
- <note>
- Any changes you want to turn into patches must be
- committed to the Git repository in the source tree.
- </note></para>
- <para>As a final process of the
- <filename>devtool finish</filename> command, the state
- of the standard layers and the upstream source is
- restored so that you can build the recipe from those
- areas rather than the workspace.
- <note>
- You can use the <filename>devtool reset</filename>
- command to put things back should you decide you
- do not want to proceed with your work.
- If you do use this command, realize that the source
- tree is preserved.
- </note>
- </para></listitem>
- </orderedlist>
- </para>
- </section>
- </section>
- <section id='sdk-a-closer-look-at-devtool-add'>
- <title>A Closer Look at <filename>devtool add</filename></title>
- <para>
- The <filename>devtool add</filename> command automatically creates a
- recipe based on the source tree with which you provide it.
- Currently, the command has support for the following:
- <itemizedlist>
- <listitem><para>
- Autotools (<filename>autoconf</filename> and
- <filename>automake</filename>)
- </para></listitem>
- <listitem><para>
- CMake
- </para></listitem>
- <listitem><para>
- Scons
- </para></listitem>
- <listitem><para>
- <filename>qmake</filename>
- </para></listitem>
- <listitem><para>
- Plain <filename>Makefile</filename>
- </para></listitem>
- <listitem><para>
- Out-of-tree kernel module
- </para></listitem>
- <listitem><para>
- Binary package (i.e. "-b" option)
- </para></listitem>
- <listitem><para>
- Node.js module
- </para></listitem>
- <listitem><para>
- Python modules that use <filename>setuptools</filename>
- or <filename>distutils</filename>
- </para></listitem>
- </itemizedlist>
- </para>
- <para>
- Apart from binary packages, the determination of how a source tree
- should be treated is automatic based on the files present within
- that source tree.
- For example, if a <filename>CMakeLists.txt</filename> file is found,
- then the source tree is assumed to be using
- CMake and is treated accordingly.
- <note>
- In most cases, you need to edit the automatically generated
- recipe in order to make it build properly.
- Typically, you would go through several edit and build cycles
- until you can build the recipe.
- Once the recipe can be built, you could use possible further
- iterations to test the recipe on the target device.
- </note>
- </para>
- <para>
- The remainder of this section covers specifics regarding how parts
- of the recipe are generated.
- </para>
- <section id='sdk-name-and-version'>
- <title>Name and Version</title>
- <para>
- If you do not specify a name and version on the command
- line, <filename>devtool add</filename> attempts to determine
- the name and version of the software being built from
- various metadata within the source tree.
- Furthermore, the command sets the name of the created recipe
- file accordingly.
- If the name or version cannot be determined, the
- <filename>devtool add</filename> command prints an error and
- you must re-run the command with both the name and version
- or just the name or version specified.
- </para>
- <para>
- Sometimes the name or version determined from the source tree
- might be incorrect.
- For such a case, you must reset the recipe:
- <literallayout class='monospaced'>
- $ devtool reset -n <replaceable>recipename</replaceable>
- </literallayout>
- After running the <filename>devtool reset</filename> command,
- you need to run <filename>devtool add</filename> again and
- provide the name or the version.
- </para>
- </section>
- <section id='sdk-dependency-detection-and-mapping'>
- <title>Dependency Detection and Mapping</title>
- <para>
- The <filename>devtool add</filename> command attempts to
- detect build-time dependencies and map them to other recipes
- in the system.
- During this mapping, the command fills in the names of those
- recipes in the
- <ulink url='&YOCTO_DOCS_REF_URL;#var-DEPENDS'><filename>DEPENDS</filename></ulink>
- value within the recipe.
- If a dependency cannot be mapped, then a comment is placed in
- the recipe indicating such.
- The inability to map a dependency might be caused because the
- naming is not recognized or because the dependency simply is
- not available.
- For cases where the dependency is not available, you must use
- the <filename>devtool add</filename> command to add an
- additional recipe to satisfy the dependency and then come
- back to the first recipe and add its name to
- <filename>DEPENDS</filename>.
- </para>
- <para>
- If you need to add runtime dependencies, you can do so by
- adding the following to your recipe:
- <literallayout class='monospaced'>
- RDEPENDS_${PN} += "dependency1 dependency2 ..."
- </literallayout>
- <note>
- The <filename>devtool add</filename> command often cannot
- distinguish between mandatory and optional dependencies.
- Consequently, some of the detected dependencies might
- in fact be optional.
- When in doubt, consult the documentation or the configure
- script for the software the recipe is building for further
- details.
- In some cases, you might find you can substitute the
- dependency for an option to disable the associated
- functionality passed to the configure script.
- </note>
- </para>
- </section>
- <section id='sdk-license-detection'>
- <title>License Detection</title>
- <para>
- The <filename>devtool add</filename> command attempts to
- determine if the software you are adding is able to be
- distributed under a common open-source license and sets the
- <ulink url='&YOCTO_DOCS_REF_URL;#var-LICENSE'><filename>LICENSE</filename></ulink>
- value accordingly.
- You should double-check this value against the documentation
- or source files for the software you are building and update
- that <filename>LICENSE</filename> value if necessary.
- </para>
- <para>
- The <filename>devtool add</filename> command also sets the
- <ulink url='&YOCTO_DOCS_REF_URL;#var-LIC_FILES_CHKSUM'><filename>LIC_FILES_CHKSUM</filename></ulink>
- value to point to all files that appear to be license-related.
- However, license statements often appear in comments at the top
- of source files or within documentation.
- Consequently, you might need to amend the
- <filename>LIC_FILES_CHKSUM</filename> variable to point to one
- or more of those comments if present.
- Setting <filename>LIC_FILES_CHKSUM</filename> is particularly
- important for third-party software.
- The mechanism attempts to ensure correct licensing should you
- upgrade the recipe to a newer upstream version in future.
- Any change in licensing is detected and you receive an error
- prompting you to check the license text again.
- </para>
- <para>
- If the <filename>devtool add</filename> command cannot
- determine licensing information, the
- <filename>LICENSE</filename> value is set to "CLOSED" and the
- <filename>LIC_FILES_CHKSUM</filename> value remains unset.
- This behavior allows you to continue with development but is
- unlikely to be correct in all cases.
- Consequently, you should check the documentation or source
- files for the software you are building to determine the actual
- license.
- </para>
- </section>
- <section id='sdk-adding-makefile-only-software'>
- <title>Adding Makefile-Only Software</title>
- <para>
- The use of <filename>make</filename> by itself is very common
- in both proprietary and open source software.
- Unfortunately, Makefiles are often not written with
- cross-compilation in mind.
- Thus, <filename>devtool add</filename> often cannot do very
- much to ensure that these Makefiles build correctly.
- It is very common, for example, to explicitly call
- <filename>gcc</filename> instead of using the
- <ulink url='&YOCTO_DOCS_REF_URL;#var-CC'><filename>CC</filename></ulink>
- variable.
- Usually, in a cross-compilation environment,
- <filename>gcc</filename> is the compiler for the build host
- and the cross-compiler is named something similar to
- <filename>arm-poky-linux-gnueabi-gcc</filename> and might
- require some arguments (e.g. to point to the associated sysroot
- for the target machine).
- </para>
- <para>
- When writing a recipe for Makefile-only software, keep the
- following in mind:
- <itemizedlist>
- <listitem><para>
- You probably need to patch the Makefile to use
- variables instead of hardcoding tools within the
- toolchain such as <filename>gcc</filename> and
- <filename>g++</filename>.
- </para></listitem>
- <listitem><para>
- The environment in which <filename>make</filename> runs
- is set up with various standard variables for
- compilation (e.g. <filename>CC</filename>,
- <filename>CXX</filename>, and so forth) in a similar
- manner to the environment set up by the SDK's
- environment setup script.
- One easy way to see these variables is to run the
- <filename>devtool build</filename> command on the
- recipe and then look in
- <filename>oe-logs/run.do_compile</filename>.
- Towards the top of this file you will see a list of
- environment variables that are being set.
- You can take advantage of these variables within the
- Makefile.
- </para></listitem>
- <listitem><para>
- If the Makefile sets a default for a variable using "=",
- that default overrides the value set in the environment,
- which is usually not desirable.
- In this situation, you can either patch the Makefile
- so it sets the default using the "?=" operator, or
- you can alternatively force the value on the
- <filename>make</filename> command line.
- To force the value on the command line, add the
- variable setting to
- <ulink url='&YOCTO_DOCS_REF_URL;#var-EXTRA_OEMAKE'><filename>EXTRA_OEMAKE</filename></ulink>
- or
- <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGECONFIG_CONFARGS'><filename>PACKAGECONFIG_CONFARGS</filename></ulink>
- within the recipe.
- Here is an example using <filename>EXTRA_OEMAKE</filename>:
- <literallayout class='monospaced'>
- EXTRA_OEMAKE += "'CC=${CC}' 'CXX=${CXX}'"
- </literallayout>
- In the above example, single quotes are used around the
- variable settings as the values are likely to contain
- spaces because required default options are passed to
- the compiler.
- </para></listitem>
- <listitem><para>
- Hardcoding paths inside Makefiles is often problematic
- in a cross-compilation environment.
- This is particularly true because those hardcoded paths
- often point to locations on the build host and thus
- will either be read-only or will introduce
- contamination into the cross-compilation by virtue of
- being specific to the build host rather than the target.
- Patching the Makefile to use prefix variables or other
- path variables is usually the way to handle this.
- </para></listitem>
- <listitem><para>
- Sometimes a Makefile runs target-specific commands such
- as <filename>ldconfig</filename>.
- For such cases, you might be able to simply apply
- patches that remove these commands from the Makefile.
- </para></listitem>
- </itemizedlist>
- </para>
- </section>
- <section id='sdk-adding-native-tools'>
- <title>Adding Native Tools</title>
- <para>
- Often, you need to build additional tools that run on the
- build host system as opposed to the target.
- You should indicate this using one of the following methods
- when you run <filename>devtool add</filename>:
- <itemizedlist>
- <listitem><para>
- Specify the name of the recipe such that it ends
- with "-native".
- Specifying the name like this produces a recipe that
- only builds for the build host.
- </para></listitem>
- <listitem><para>
- Specify the "‐‐also-native" option with the
- <filename>devtool add</filename> command.
- Specifying this option creates a recipe file that still
- builds for the target but also creates a variant with
- a "-native" suffix that builds for the build host.
- </para></listitem>
- </itemizedlist>
- <note>
- If you need to add a tool that is shipped as part of a
- source tree that builds code for the target, you can
- typically accomplish this by building the native and target
- parts separately rather than within the same compilation
- process.
- Realize though that with the "‐‐also-native" option, you
- can add the tool using just one recipe file.
- </note>
- </para>
- </section>
- <section id='sdk-adding-node-js-modules'>
- <title>Adding Node.js Modules</title>
- <para>
- You can use the <filename>devtool add</filename> command two
- different ways to add Node.js modules: 1) Through
- <filename>npm</filename> and, 2) from a repository or local
- source.
- </para>
- <para>
- Use the following form to add Node.js modules through
- <filename>npm</filename>:
- <literallayout class='monospaced'>
- $ devtool add "npm://registry.npmjs.org;name=forever;version=0.15.1"
- </literallayout>
- The name and version parameters are mandatory.
- Lockdown and shrinkwrap files are generated and pointed to by
- the recipe in order to freeze the version that is fetched for
- the dependencies according to the first time.
- This also saves checksums that are verified on future fetches.
- Together, these behaviors ensure the reproducibility and
- integrity of the build.
- <note><title>Notes</title>
- <itemizedlist>
- <listitem><para>
- You must use quotes around the URL.
- The <filename>devtool add</filename> does not require
- the quotes, but the shell considers ";" as a splitter
- between multiple commands.
- Thus, without the quotes,
- <filename>devtool add</filename> does not receive the
- other parts, which results in several "command not
- found" errors.
- </para></listitem>
- <listitem><para>
- In order to support adding
- Node.js modules, a
- <filename>nodejs</filename> recipe must be part of your
- SDK in order to provide Node.js
- itself.
- </para></listitem>
- </itemizedlist>
- </note>
- </para>
- <para>
- As mentioned earlier, you can also add Node.js modules
- directly from a repository or local source tree.
- To add modules this way, use <filename>devtool add</filename> in
- the following form:
- <literallayout class='monospaced'>
- $ devtool add https://github.com/diversario/node-ssdp
- </literallayout>
- In this example, <filename>devtool</filename> fetches the specified
- Git repository, detects that the code is Node.js code, fetches
- dependencies using <filename>npm</filename>, and sets
- <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>
- accordingly.
- </para>
- </section>
- </section>
- <section id='sdk-working-with-recipes'>
- <title>Working With Recipes</title>
- <para>
- When building a recipe with <filename>devtool build</filename>, the
- typical build progression is as follows:
- <orderedlist>
- <listitem><para>
- Fetch the source
- </para></listitem>
- <listitem><para>
- Unpack the source
- </para></listitem>
- <listitem><para>
- Configure the source
- </para></listitem>
- <listitem><para>
- Compiling the source
- </para></listitem>
- <listitem><para>
- Install the build output
- </para></listitem>
- <listitem><para>
- Package the installed output
- </para></listitem>
- </orderedlist>
- For recipes in the workspace, fetching and unpacking is disabled
- as the source tree has already been prepared and is persistent.
- Each of these build steps is defined as a function, usually with a
- "do_" prefix.
- These functions are typically shell scripts but can instead be written
- in Python.
- </para>
- <para>
- If you look at the contents of a recipe, you will see that the
- recipe does not include complete instructions for building the
- software.
- Instead, common functionality is encapsulated in classes inherited
- with the <filename>inherit</filename> directive, leaving the recipe
- to describe just the things that are specific to the software to be
- built.
- A <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-base'><filename>base</filename></ulink>
- class exists that is implicitly inherited by all recipes and provides
- the functionality that most typical recipes need.
- </para>
- <para>
- The remainder of this section presents information useful when
- working with recipes.
- </para>
- <section id='sdk-finding-logs-and-work-files'>
- <title>Finding Logs and Work Files</title>
- <para>
- When you are debugging a recipe that you previously created using
- <filename>devtool add</filename> or whose source you are modifying
- by using the <filename>devtool modify</filename> command, after
- the first run of <filename>devtool build</filename>, you will
- find some symbolic links created within the source tree:
- <filename>oe-logs</filename>, which points to the directory in
- which log files and run scripts for each build step are created
- and <filename>oe-workdir</filename>, which points to the temporary
- work area for the recipe.
- You can use these links to get more information on what is
- happening at each build step.
- </para>
- <para>
- These locations under <filename>oe-workdir</filename> are
- particularly useful:
- <itemizedlist>
- <listitem><para><filename>image/</filename>:
- Contains all of the files installed at the
- <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-install'><filename>do_install</filename></ulink>
- stage.
- Within a recipe, this directory is referred to by the
- expression
- <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-D'><filename>D</filename></ulink><filename>}</filename>.
- </para></listitem>
- <listitem><para><filename>sysroot-destdir/</filename>:
- Contains a subset of files installed within
- <filename>do_install</filename> that have been put into the
- shared sysroot.
- For more information, see the
- "<link linkend='sdk-sharing-files-between-recipes'>Sharing Files Between Recipes</link>"
- section.
- </para></listitem>
- <listitem><para><filename>packages-split/</filename>:
- Contains subdirectories for each package produced by the
- recipe.
- For more information, see the
- "<link linkend='sdk-packaging'>Packaging</link>" section.
- </para></listitem>
- </itemizedlist>
- </para>
- </section>
- <section id='sdk-setting-configure-arguments'>
- <title>Setting Configure Arguments</title>
- <para>
- If the software your recipe is building uses GNU autoconf,
- then a fixed set of arguments is passed to it to enable
- cross-compilation plus any extras specified by
- <ulink url='&YOCTO_DOCS_REF_URL;#var-EXTRA_OECONF'><filename>EXTRA_OECONF</filename></ulink>
- or
- <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGECONFIG_CONFARGS'><filename>PACKAGECONFIG_CONFARGS</filename></ulink>
- set within the recipe.
- If you wish to pass additional options, add them to
- <filename>EXTRA_OECONF</filename> or
- <filename>PACKAGECONFIG_CONFARGS</filename>.
- Other supported build tools have similar variables
- (e.g.
- <ulink url='&YOCTO_DOCS_REF_URL;#var-EXTRA_OECMAKE'><filename>EXTRA_OECMAKE</filename></ulink>
- for CMake,
- <ulink url='&YOCTO_DOCS_REF_URL;#var-EXTRA_OESCONS'><filename>EXTRA_OESCONS</filename></ulink>
- for Scons, and so forth).
- If you need to pass anything on the <filename>make</filename>
- command line, you can use <filename>EXTRA_OEMAKE</filename> or the
- <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGECONFIG_CONFARGS'><filename>PACKAGECONFIG_CONFARGS</filename></ulink>
- variables to do so.
- </para>
- <para>
- You can use the <filename>devtool configure-help</filename> command
- to help you set the arguments listed in the previous paragraph.
- The command determines the exact options being passed, and shows
- them to you along with any custom arguments specified through
- <filename>EXTRA_OECONF</filename> or
- <filename>PACKAGECONFIG_CONFARGS</filename>.
- If applicable, the command also shows you the output of the
- configure script's "‐‐help" option as a reference.
- </para>
- </section>
- <section id='sdk-sharing-files-between-recipes'>
- <title>Sharing Files Between Recipes</title>
- <para>
- Recipes often need to use files provided by other recipes on
- the build host.
- For example, an application linking to a common library needs
- access to the library itself and its associated headers.
- The way this access is accomplished within the extensible SDK is
- through the sysroot.
- One sysroot exists per "machine" for which the SDK is being built.
- In practical terms, this means a sysroot exists for the target
- machine, and a sysroot exists for the build host.
- </para>
- <para>
- Recipes should never write files directly into the sysroot.
- Instead, files should be installed into standard locations
- during the
- <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-install'><filename>do_install</filename></ulink>
- task within the
- <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-D'><filename>D</filename></ulink><filename>}</filename>
- directory.
- A subset of these files automatically go into the sysroot.
- The reason for this limitation is that almost all files that go
- into the sysroot are cataloged in manifests in order to ensure
- they can be removed later when a recipe is modified or removed.
- Thus, the sysroot is able to remain free from stale files.
- </para>
- </section>
- <section id='sdk-packaging'>
- <title>Packaging</title>
- <para>
- Packaging is not always particularly relevant within the
- extensible SDK.
- However, if you examine how build output gets into the final image
- on the target device, it is important to understand packaging
- because the contents of the image are expressed in terms of
- packages and not recipes.
- </para>
- <para>
- During the
- <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-package'><filename>do_package</filename></ulink>
- task, files installed during the
- <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-install'><filename>do_install</filename></ulink>
- task are split into one main package, which is almost always named
- the same as the recipe, and several other packages.
- This separation is done because not all of those installed files
- are always useful in every image.
- For example, you probably do not need any of the documentation
- installed in a production image.
- Consequently, for each recipe the documentation files are separated
- into a <filename>-doc</filename> package.
- Recipes that package software that has optional modules or
- plugins might do additional package splitting as well.
- </para>
- <para>
- After building a recipe you can see where files have gone by
- looking in the <filename>oe-workdir/packages-split</filename>
- directory, which contains a subdirectory for each package.
- Apart from some advanced cases, the
- <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGES'><filename>PACKAGES</filename></ulink>
- and
- <ulink url='&YOCTO_DOCS_REF_URL;#var-FILES'><filename>FILES</filename></ulink>
- variables controls splitting.
- The <filename>PACKAGES</filename> variable lists all of the
- packages to be produced, while the <filename>FILES</filename>
- variable specifies which files to include in each package,
- using an override to specify the package.
- For example, <filename>FILES_${PN}</filename> specifies the files
- to go into the main package (i.e. the main package is named the
- same as the recipe and
- <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PN'><filename>PN</filename></ulink><filename>}</filename>
- evaluates to the recipe name).
- The order of the <filename>PACKAGES</filename> value is significant.
- For each installed file, the first package whose
- <filename>FILES</filename> value matches the file is the package
- into which the file goes.
- Defaults exist for both the <filename>PACKAGES</filename> and
- <filename>FILES</filename> variables.
- Consequently, you might find you do not even need to set these
- variables in your recipe unless the software the recipe is
- building installs files into non-standard locations.
- </para>
- </section>
- </section>
- <section id='sdk-restoring-the-target-device-to-its-original-state'>
- <title>Restoring the Target Device to its Original State</title>
- <para>
- If you use the <filename>devtool deploy-target</filename>
- command to write a recipe's build output to the target, and
- you are working on an existing component of the system, then you
- might find yourself in a situation where you need to restore the
- original files that existed prior to running the
- <filename>devtool deploy-target</filename> command.
- Because the <filename>devtool deploy-target</filename> command
- backs up any files it overwrites, you can use the
- <filename>devtool undeploy-target</filename> to restore those files
- and remove any other files the recipe deployed.
- Consider the following example:
- <literallayout class='monospaced'>
- $ devtool undeploy-target lighttpd root@192.168.7.2
- </literallayout>
- If you have deployed multiple applications, you can remove them
- all at once thus restoring the target device back to its
- original state:
- <literallayout class='monospaced'>
- $ devtool undeploy-target -a root@192.168.7.2
- </literallayout>
- Information about files deployed to the target as well as any
- backed up files are stored on the target itself.
- This storage of course requires some additional space
- on the target machine.
- <note>
- The <filename>devtool deploy-target</filename> and
- <filename>devtool undeploy-target</filename> command do not
- currently interact with any package management system on the
- target device (e.g. RPM or OPKG).
- Consequently, you should not intermingle operations
- <filename>devtool deploy-target</filename> and the package
- manager operations on the target device.
- Doing so could result in a conflicting set of files.
- </note>
- </para>
- </section>
- <section id='sdk-installing-additional-items-into-the-extensible-sdk'>
- <title>Installing Additional Items Into the Extensible SDK</title>
- <para>
- The extensible SDK typically only comes with a small number of tools
- and libraries out of the box.
- If you have a minimal SDK, then it starts mostly empty and is
- populated on-demand.
- However, sometimes you will need to explicitly install extra items
- into the SDK.
- If you need these extra items, you can first search for the items
- using the <filename>devtool search</filename> command.
- For example, suppose you need to link to libGL but you are not sure
- which recipe provides it.
- You can use the following command to find out:
- <literallayout class='monospaced'>
- $ devtool search libGL
- mesa A free implementation of the OpenGL API
- </literallayout>
- Once you know the recipe (i.e. <filename>mesa</filename> in this
- example), you can install it:
- <literallayout class='monospaced'>
- $ devtool sdk-install mesa
- </literallayout>
- By default, the <filename>devtool sdk-install</filename> assumes the
- item is available in pre-built form from your SDK provider.
- If the item is not available and it is acceptable to build the item
- from source, you can add the "-s" option as follows:
- <literallayout class='monospaced'>
- $ devtool sdk-install -s mesa
- </literallayout>
- It is important to remember that building the item from source takes
- significantly longer than installing the pre-built artifact.
- Also, if no recipe exists for the item you want to add to the SDK, you
- must instead add it using the <filename>devtool add</filename> command.
- </para>
- </section>
- <section id='sdk-updating-the-extensible-sdk'>
- <title>Updating the Extensible SDK</title>
- <para>
- If you are working with an extensible SDK that gets occasionally
- updated (e.g. typically when that SDK has been provided to you by
- another party), then you will need to manually pull down those
- updates to your installed SDK.
- </para>
- <para>
- To update your installed SDK, run the following:
- <literallayout class='monospaced'>
- $ devtool sdk-update
- </literallayout>
- The previous command assumes your SDK provider has set the default
- update URL for you.
- If that URL has not been set, you need to specify it yourself as
- follows:
- <literallayout class='monospaced'>
- $ devtool sdk-update <replaceable>path_to_update_directory</replaceable>
- </literallayout>
- <note>
- The URL needs to point specifically to a published SDK and not an
- SDK installer that you would download and install.
- </note>
- </para>
- </section>
- <section id='sdk-creating-a-derivative-sdk-with-additional-components'>
- <title>Creating a Derivative SDK With Additional Components</title>
- <para>
- You might need to produce an SDK that contains your own custom
- libraries for sending to a third party (e.g., if you are a vendor with
- customers needing to build their own software for the target platform).
- If that is the case, then you can produce a derivative SDK based on
- the currently installed SDK fairly easily.
- Use these steps:
- <orderedlist>
- <listitem><para>If necessary, install an extensible SDK that
- you want to use as a base for your derivative SDK.
- </para></listitem>
- <listitem><para>Source the environment script for the SDK.
- </para></listitem>
- <listitem><para>Add the extra libraries or other components
- you want by using the <filename>devtool add</filename>
- command.
- </para></listitem>
- <listitem><para>Run the <filename>devtool build-sdk</filename>
- command.
- </para></listitem>
- </orderedlist>
- The above procedure takes the recipes added to the workspace and
- constructs a new SDK installer containing those recipes and the
- resulting binary artifacts.
- The recipes go into their own separate layer in the constructed
- derivative SDK, leaving the workspace clean and ready for users
- to add their own recipes.
- </para>
- </section>
- </chapter>
- <!--
- vim: expandtab tw=80 ts=4
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