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I wrote the section to include a flow diagram using "make" and provided a working example highlighting how to override environment variables. (From yocto-docs rev: 00e8e09a51a1f0305317f38975a9d7695c92bdb5) Signed-off-by: Scott Rifenbark <srifenbark@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
361 lines
17 KiB
XML
361 lines
17 KiB
XML
<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
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[<!ENTITY % poky SYSTEM "../poky.ent"> %poky; ] >
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<chapter id='sdk-working-projects'>
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<title>Using the SDK Toolchain Directly</title>
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<para>
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You can use the SDK toolchain directly with Makefile,
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Autotools, and <trademark class='trade'>Eclipse</trademark>-based
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projects.
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This chapter covers the first two, while the
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"<link linkend='sdk-eclipse-project'>Developing Applications Using <trademark class='trade'>Eclipse</trademark></link>"
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Chapter covers the latter.
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</para>
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<section id='autotools-based-projects'>
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<title>Autotools-Based Projects</title>
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<para>
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Once you have a suitable
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<ulink url='&YOCTO_DOCS_REF_URL;#cross-development-toolchain'>cross-development toolchain</ulink>
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installed, it is very easy to develop a project using the
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<ulink url='https://en.wikipedia.org/wiki/GNU_Build_System'>GNU Autotools-based</ulink>
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workflow, which is outside of the
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<ulink url='&YOCTO_DOCS_REF_URL;#build-system-term'>OpenEmbedded build system</ulink>.
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</para>
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<para>
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The following figure presents a simple Autotools workflow.
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<imagedata fileref="figures/sdk-autotools-flow.png" width="7in" height="8in" align="center" />
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</para>
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<para>
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Follow these steps to create a simple Autotools-based
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"Hello World" project:
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<note>
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For more information on the GNU Autotools workflow,
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see the same example on the
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<ulink url='https://developer.gnome.org/anjuta-build-tutorial/stable/create-autotools.html.en'>GNOME Developer</ulink>
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site.
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</note>
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<orderedlist>
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<listitem><para>
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<emphasis>Create a Working Directory and Populate It:</emphasis>
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Create a clean directory for your project and then make
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that directory your working location.
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<literallayout class='monospaced'>
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$ mkdir $HOME/helloworld
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$ cd $HOME/helloworld
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</literallayout>
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After setting up the directory, populate it with three
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simple files needed for the flow.
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You need a project source file, a file to help with
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configuration, and a file to help create the Makefile:
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<filename>hello.c</filename>,
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<filename>configure.ac</filename>, and
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<filename>Makefile.am</filename>, respectively:
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<itemizedlist>
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<listitem><para>
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<emphasis><filename>hello.c</filename>:</emphasis>
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<literallayout class='monospaced'>
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#include <stdio.h>
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main()
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{
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printf("Hello World!\n");
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}
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</literallayout>
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</para></listitem>
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<listitem><para>
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<emphasis><filename>configure.ac</filename>:</emphasis>
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<literallayout class='monospaced'>
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AC_INIT(hello,0.1)
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AM_INIT_AUTOMAKE([foreign])
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AC_PROG_CC
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AC_CONFIG_FILES(Makefile)
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AC_OUTPUT
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</literallayout>
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</para></listitem>
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<listitem><para>
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<emphasis><filename>Makefile.am</filename>:</emphasis>
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<literallayout class='monospaced'>
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bin_PROGRAMS = hello
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hello_SOURCES = hello.c
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</literallayout>
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</para></listitem>
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</itemizedlist>
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</para></listitem>
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<listitem><para>
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<emphasis>Source the Cross-Toolchain
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Environment Setup File:</emphasis>
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As described earlier in the manual, installing the
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cross-toolchain creates a cross-toolchain
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environment setup script in the directory that the SDK
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was installed.
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Before you can use the tools to develop your project,
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you must source this setup script.
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The script begins with the string "environment-setup"
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and contains the machine architecture, which is
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followed by the string "poky-linux".
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For this example, the command sources a script from the
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default SDK installation directory that uses the
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32-bit Intel x86 Architecture and the
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&DISTRO_NAME; Yocto Project release:
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<literallayout class='monospaced'>
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$ source /opt/poky/&DISTRO;/environment-setup-i586-poky-linux
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</literallayout>
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</para></listitem>
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<listitem><para>
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<emphasis>Generate the Local <filename>aclocal.m4</filename> Files:</emphasis>
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The following command generates the local
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<filename>aclocal.m4</filename> files, which are used
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later with the <filename>autoconf</filename> command:
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<literallayout class='monospaced'>
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$ aclocal
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</literallayout>
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</para></listitem>
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<listitem><para>
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<emphasis>Create the <filename>configure</filename> Script:</emphasis>
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The following command creates the
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<filename>configure</filename> script:
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<literallayout class='monospaced'>
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$ autoconf
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</literallayout>
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</para></listitem>
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<listitem><para>
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<emphasis>Generate Files Needed by GNU Coding
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Standards:</emphasis>
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GNU coding standards require certain files in order
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for the project to be compliant.
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This command creates those files:
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<literallayout class='monospaced'>
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$ touch NEWS README AUTHORS ChangeLog
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</literallayout>
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</para></listitem>
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<listitem><para>
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<emphasis>Generate the <filename>Makefile.in</filename> File:</emphasis>
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This command generates the
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<filename>Makefile.in</filename>, which is used later
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during cross-compilation:
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<literallayout class='monospaced'>
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$ automake -a
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</literallayout>
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</para></listitem>
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<listitem><para>
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<emphasis>Cross-Compile the Project:</emphasis>
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This command compiles the project using the
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cross-compiler.
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The
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<ulink url='&YOCTO_DOCS_REF_URL;#var-CONFIGURE_FLAGS'><filename>CONFIGURE_FLAGS</filename></ulink>
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environment variable provides the minimal arguments for
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GNU configure:
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<literallayout class='monospaced'>
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$ ./configure ${CONFIGURE_FLAGS}
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</literallayout>
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For an Autotools-based project, you can use the
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cross-toolchain by just passing the appropriate host
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option to <filename>configure.sh</filename>.
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The host option you use is derived from the name of the
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environment setup script found in the directory in which you
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installed the cross-toolchain.
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For example, the host option for an ARM-based target that uses
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the GNU EABI is
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<filename>armv5te-poky-linux-gnueabi</filename>.
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You will notice that the name of the script is
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<filename>environment-setup-armv5te-poky-linux-gnueabi</filename>.
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Thus, the following command works to update your project
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and rebuild it using the appropriate cross-toolchain tools:
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<literallayout class='monospaced'>
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$ ./configure --host=armv5te-poky-linux-gnueabi \
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--with-libtool-sysroot=<replaceable>sysroot_dir</replaceable>
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</literallayout>
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<note>
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If the <filename>configure</filename> script results in
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problems recognizing the
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<filename>--with-libtool-sysroot=</filename><replaceable>sysroot-dir</replaceable>
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option, regenerate the script to enable the support by
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doing the following and then run the script again:
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<literallayout class='monospaced'>
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$ libtoolize --automake
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$ aclocal -I ${OECORE_TARGET_SYSROOT}/usr/share/aclocal [-I <replaceable>dir_containing_your_project-specific_m4_macros</replaceable>]
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$ autoconf
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$ autoheader
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$ automake -a
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</literallayout>
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</note>
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</para></listitem>
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<listitem><para>
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<emphasis>Make and Install the Project:</emphasis>
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These two commands generate and install the project
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into the destination directory:
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<literallayout class='monospaced'>
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$ make
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$ make install DESTDIR=./tmp
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</literallayout>
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<note>
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To learn about environment variables established
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when you run the cross-toolchain environment setup
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script and how they are used or overridden when
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the Makefile, see the
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"<link linkend='makefile-based-projects'>Makefile-Based Projects</link>"
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section.
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</note>
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This next command is a simple way to verify the
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installation of your project.
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Running the command prints the architecture on which
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the binary file can run.
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This architecture should be the same architecture that
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the installed cross-toolchain supports.
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<literallayout class='monospaced'>
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$ file ./tmp/usr/local/bin/hello
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</literallayout>
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</para></listitem>
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<listitem><para>
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<emphasis>Execute Your Project:</emphasis>
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To execute the project in the shell, simply enter
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the name.
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You could also copy the binary to the actual target
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hardware and run the project there as well:
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<literallayout class='monospaced'>
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$ ./hello
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</literallayout>
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As expected, the project displays the "Hello World!"
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message.
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</para></listitem>
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</orderedlist>
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</para>
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</section>
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<section id='makefile-based-projects'>
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<title>Makefile-Based Projects</title>
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<para>
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Simple Makefile-based projects use and interact with the
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cross-toolchain environment variables established when you run
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the cross-toolchain environment setup script.
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The environment variables are subject to general
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<filename>make</filename> rules.
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</para>
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<para>
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This section presents a simple Makefile development flow and
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provides an example that lets you see how you can use
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cross-toolchain environment variables to replace or override
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variables used in your Makefile.
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<imagedata fileref="figures/sdk-makefile-flow.png" width="6in" height="7in" align="center" />
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</para>
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<para>
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The main point of this section is to explain the following three
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cases regarding variable behavior:
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<itemizedlist>
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<listitem><para>
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<emphasis>Case 1 - No Variables Set in the
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<filename>Makefile</filename> that Map to Equivalent
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Environment Variables Set in the SDK Setup Script:</emphasis>
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Because matching variables are not specifically set in the
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<filename>Makefile</filename>, the variables retain their
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values based on the environment setup script.
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</para></listitem>
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<listitem><para>
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<emphasis>Case 2 - Variables Are Set in the Makefile that
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Map to Equivalent Environment Variables from the SDK
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Setup Script:</emphasis>
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Specifically setting matching variables in the
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<filename>Makefile</filename> during the build results in
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the environment settings of the variables being
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overwritten.
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In this case, the variables you set in the
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<filename>Makefile</filename> are used.
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</para></listitem>
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<listitem><para>
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<emphasis>Case 3 - Variables Are Set Using the Command Line
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that Map to Equivalent Environment Variables from the
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SDK Setup Script:</emphasis>
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Executing the <filename>Makefile</filename> from the
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command line results in the environment settings of the
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variables being overwritten.
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In this case, the command-line content is used.
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<note>
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The one exception to this is if you use the following
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command-line option:
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<literallayout class='monospaced'>
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$ make -e <replaceable>target</replaceable>
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</literallayout>
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Using the "-e" option with <filename>make</filename>
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causes the environment variables to be used during
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the build.
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</note>
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</para></listitem>
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</itemizedlist>
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</para>
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<para>
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The remainder of this section presents a simple Makefile example
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that demonstrates these variable behaviors.
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</para>
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<para>
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In a new shell environment variables are not established for the
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SDK until you run the setup script.
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For example, the following commands show null values for four
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variables that are set when you run the SDK environment setup
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script for a 64-bit build host and an i586-tuned target
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architecture for a <filename>core-image-sato</filename> image
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using the current &DISTRO; Yocto Project release:
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<literallayout class='monospaced'>
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$ echo ${CC}
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$ echo ${LD}
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$ echo ${CFLAGS}
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$ echo ${CXXFLAGS}
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</literallayout>
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Running the setup script and then echoing the variables shows the
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values established for the SDK:
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<literallayout class='monospaced'>
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$ source /opt/poky/2.5/environment-setup-i586-poky-linux
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$ echo ${CC}
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i586-poky-linux-gcc -m32 -march=i586 --sysroot=/opt/poky/2.5/sysroots/i586-poky-linux
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$ echo ${LD}
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i586-poky-linux-ld --sysroot=/opt/poky/2.5/sysroots/i586-poky-linux
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$ echo ${CFLAGS}
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-O2 -pipe -g -feliminate-unused-debug-types
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$ echo ${CXXFLAGS}
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-O2 -pipe -g -feliminate-unused-debug-types
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</literallayout>
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</para>
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<para role='writernotes'>
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NEED REST OF THE EXAMPLE.
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WORKING ON GETTING IT TO WORK PROPERLY.
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</para>
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<!--
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To illustrate this, consider the following four cross-toolchain
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environment variables:
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<literallayout class='monospaced'>
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<ulink url='&YOCTO_DOCS_REF_URL;#var-CC'>CC</ulink>="i586-poky-linux-gcc -m32 -march=i586 &DASH;&DASH;sysroot=/opt/poky/&DISTRO;/sysroots/i586-poky-linux"
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<ulink url='&YOCTO_DOCS_REF_URL;#var-LD'>LD</ulink>="i586-poky-linux-ld &DASH;&DASH;sysroot=/opt/poky/&DISTRO;/sysroots/i586-poky-linux"
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<ulink url='&YOCTO_DOCS_REF_URL;#var-CFLAGS'>CFLAGS</ulink>="-O2 -pipe -g -feliminate-unused-debug-types"
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<ulink url='&YOCTO_DOCS_REF_URL;#var-CXXFLAGS'>CXXFLAGS</ulink>="-O2 -pipe -g -feliminate-unused-debug-types"
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</literallayout>
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Now, consider the following three cases:
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<note>
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For information on the variables set up by the cross-toolchain
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environment setup script, see the
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"<link linkend='sdk-running-the-extensible-sdk-environment-setup-script'>Running the Extensible SDK Environment Setup Script</link>"
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section.
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</note>
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</para>
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-->
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</section>
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</chapter>
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<!--
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vim: expandtab tw=80 ts=4
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-->
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