1005 lines
50 KiB
XML
1005 lines
50 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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<chapter id='extendpoky'>
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<title>Extending Poky</title>
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<para>
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This section provides information about how to extend the functionality
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already present in Poky.
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The section also documents standard tasks such as adding new
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software packages, extending or customizing images or porting Poky to
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new hardware (adding a new machine).
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Finally, the section contains advice about how
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to make changes to Poky to achieve the best results.
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</para>
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<section id='usingpoky-extend-addpkg'>
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<title>Adding a Package</title>
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<para>
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To add a package into Poky you need to write a recipe for it.
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Writing a recipe means creating a <filename>.bb</filename> file that sets some
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variables.
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For information on variables that are useful for recipes and for information about recipe naming
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issues, see <link linkend='ref-varlocality-recipe-required'>Recipe Variables - Required</link>
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appendix.
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</para>
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<para>
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Before writing a recipe from scratch it is often useful to check
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whether someone else has written one already.
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OpenEmbedded is a good place to look as it has a wider scope and range of packages.
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Because Poky aims to be compatible with OpenEmbedded, most recipes should
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just work in Poky.
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</para>
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<para>
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For new packages, the simplest way to add a recipe is to base it on a similar
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pre-existing recipe.
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Following are some examples showing how to add standard types of packages:
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</para>
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<section id='usingpoky-extend-addpkg-singlec'>
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<title>Single .c File Package (Hello World!)</title>
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<para>
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Building an application from a single file that is stored locally (e.g. under
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<filename>files/</filename>) requires a recipe that has the file listed in
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the <glossterm><link linkend='var-SRC_URI'>SRC_URI</link></glossterm> variable.
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Additionally, you need to manually write the <function>do_compile</function> and
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<function>do_install</function> tasks.
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The <glossterm><link linkend='var-S'>S</link></glossterm> variable defines the
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directory containing the source code, which is set to <glossterm><link linkend='var-WORKDIR'>
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WORKDIR</link></glossterm> in this case - the directory BitBake uses for the build.
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</para>
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<programlisting>
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DESCRIPTION = "Simple helloworld application"
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SECTION = "examples"
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LICENSE = "MIT"
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PR = "r0"
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SRC_URI = "file://helloworld.c"
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S = "${WORKDIR}"
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do_compile() {
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${CC} helloworld.c -o helloworld
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}
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do_install() {
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install -d ${D}${bindir}
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install -m 0755 helloworld ${D}${bindir}
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}
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</programlisting>
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<para>
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By default, the "helloworld", "helloworld-dbg" and "hellworld-dev"
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packages are built.
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For information on how to customize the packaging process, see
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<link linkend='usingpoky-extend-addpkg-files'>Controlling Package Content</link>.
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</para>
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</section>
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<section id='usingpoky-extend-addpkg-autotools'>
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<title>Autotooled Package</title>
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<para>
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Applications that use autotools such as <filename>autoconf</filename> and
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<filename>automake</filename> require a recipe that has a source archive listed in
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<glossterm><link linkend='var-SRC_URI'>SRC_URI</link></glossterm> and
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<filename>also inherits autotools</filename>, which instructs BitBake to use the
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<filename>autotools.bbclass</filename> containing the definitions of all the steps
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needed to build an autotooled application.
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The result of the build is automatically packaged.
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And, if the application uses NLS for localization, packages with local information are
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generated (one package per language).
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Following is one example (<filename>hello_2.2.bb</filename>)
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</para>
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<programlisting>
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DESCRIPTION = "GNU Helloworld application"
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SECTION = "examples"
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LICENSE = "GPLv2+"
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LIC_FILES_CHKSUM = "file://COPYING;md5=751419260aa954499f7abaabaa882bbe"
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PR = "r0"
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SRC_URI = "${GNU_MIRROR}/hello/hello-${PV}.tar.gz"
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inherit autotools gettext
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</programlisting>
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<para>
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<glossterm><link linkend='var-LIC_FILES_CHKSUM'>LIC_FILES_CHKSUM</link>
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</glossterm> is used to <link linkend='usingpoky-configuring-LIC_FILES_CHKSUM'>
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track source license change</link>.
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You can quickly create autotool-based recipes in a manner similar to the previous example.
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</para>
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</section>
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<section id='usingpoky-extend-addpkg-makefile'>
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<title>Makefile-Based Package</title>
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<para>
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Applications that use GNU <filename>make</filename> also require a recipe that has
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the source archive listed in <glossterm><link linkend='var-SRC_URI'>SRC_URI</link></glossterm>.
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You do not need to add a <function>do_compile</function> step since by default BitBake
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starts the <filename>make</filename> command to compile the application.
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If you need additional <filename>make</filename> options you should store them in the
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<glossterm><link linkend='var-EXTRA_OEMAKE'>EXTRA_OEMAKE</link></glossterm> variable.
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Bitbake passes these options into the <filename>make</filename> GNU invocation.
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Note that a <function>do_install</function> task is still required.
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Otherwise BitBake runs an empty <function>do_install</function> task by default.
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</para>
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<para>
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Some applications might require extra parameters to be passed to the compiler.
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For example the application might need an additional header path.
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You can accomplish this by adding to the <glossterm><link linkend='var-CFLAGS'>CFLAGS</link>
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</glossterm> variable.
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The following example shows this:
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</para>
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<programlisting>
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CFLAGS_prepend = "-I ${S}/include "
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</programlisting>
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<para>
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In the following example <filename>mtd-utils</filename> is a Makefile-based package:
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</para>
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<programlisting>
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DESCRIPTION = "Tools for managing memory technology devices."
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SECTION = "base"
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DEPENDS = "zlib lzo e2fsprogs util-linux"
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HOMEPAGE = "http://www.linux-mtd.infradead.org/"
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LICENSE = "GPLv2"
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SRC_URI = "git://git.infradead.org/mtd-utils.git;protocol=git;tag=v${PV}"
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S = "${WORKDIR}/git/"
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EXTRA_OEMAKE = "'CC=${CC}' 'CFLAGS=${CFLAGS} -I${S}/include -DWITHOUT_XATTR' \
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'BUILDDIR=${S}'"
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do_install () {
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oe_runmake install DESTDIR=${D} SBINDIR=${sbindir} MANDIR=${mandir} \
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INCLUDEDIR=${includedir}
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install -d ${D}${includedir}/mtd/
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for f in ${S}/include/mtd/*.h; do
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install -m 0644 $f ${D}${includedir}/mtd/
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done
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}
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</programlisting>
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</section>
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<section id='usingpoky-extend-addpkg-files'>
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<title>Controlling Package Content</title>
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<para>
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You can use the variables <glossterm><link linkend='var-PACKAGES'>PACKAGES</link></glossterm> and
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<glossterm><link linkend='var-FILES'>FILES</link></glossterm> to split an application into
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multiple packages.
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</para>
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<para>
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Following is an example that uses the "libXpm" recipe (<filename>libxpm_3.5.7.bb</filename>).
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By default, the "libXpm" recipe generates a single package containing the library, along
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with a few binaries.
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You can modify the recipe to split the binaries into separate packages:
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</para>
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<programlisting>
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require xorg-lib-common.inc
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DESCRIPTION = "X11 Pixmap library"
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LICENSE = "X-BSD"
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DEPENDS += "libxext libsm libxt"
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PR = "r3"
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PE = "1"
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XORG_PN = "libXpm"
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PACKAGES =+ "sxpm cxpm"
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FILES_cxpm = "${bindir}/cxpm"
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FILES_sxpm = "${bindir}/sxpm"
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</programlisting>
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<para>
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In the previous example we want to ship the "sxpm" and "cxpm" binaries
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in separate packages.
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Since "bindir" would be packaged into the main
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<glossterm><link linkend='var-PN'>PN</link></glossterm>
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package by default, we prepend the <glossterm><link linkend='var-PACKAGES'>PACKAGES</link>
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</glossterm> variable so additional package names are added to the start of list.
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This results in the extra <glossterm><link linkend='var-FILES'>FILES</link></glossterm>_*
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variables then containing information defining which files and
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directories go into which package.
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Files included by earlier packages are skipped by latter packages.
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Thus, the main <glossterm><link linkend='var-PN'>PN</link></glossterm> package does not include
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the above listed files.
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</para>
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</section>
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<section id='usingpoky-extend-addpkg-postinstalls'>
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<title>Post Install Scripts</title>
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<para>
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To add a post-installation script to a package, add a <function>pkg_postinst_PACKAGENAME()
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</function> function to the <filename>.bb</filename> file and use
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<filename>PACKAGENAME</filename> as the name of the package you want to attach to the
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<filename>postinst</filename> script.
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Normally <glossterm><link linkend='var-PN'>PN</link></glossterm> can be used, which
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automatically expands to PACKAGENAME.
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A post-installation function has the following structure:
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</para>
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<programlisting>
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pkg_postinst_PACKAGENAME () {
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#!/bin/sh -e
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# Commands to carry out
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}
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</programlisting>
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<para>
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The script defined in the post-installation function is called when the rootfs is made.
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If the script succeeds, the package is marked as installed.
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If the script fails, the package is marked as unpacked and the script is
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executed when the image boots again.
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</para>
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<para>
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Sometimes it is necessary for the execution of a post-installation
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script to be delayed until the first boot.
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For example, the script might need to be executed on the device itself.
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To delay script execution until boot time, use the following structure for the
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post-installation script:
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</para>
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<programlisting>
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pkg_postinst_PACKAGENAME () {
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#!/bin/sh -e
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if [ x"$D" = "x" ]; then
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# Actions to carry out on the device go here
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else
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exit 1
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fi
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}
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</programlisting>
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<para>
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The previous example delays execution until the image boots again because the
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<glossterm><link linkend='var-D'>D</link></glossterm> variable points
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to the 'image' directory when the rootfs is being made at build time but
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is unset when executed on the first boot.
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</para>
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</section>
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</section>
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<section id='usingpoky-extend-customimage'>
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<title>Customising Images</title>
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<para>
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You can customize Poky images to satisfy particular requirements.
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This section describes several methods and provides guidelines for each.
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</para>
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<section id='usingpoky-extend-customimage-custombb'>
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<title>Customising Images Using Custom .bb Files</title>
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<para>
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One way to get additional software into an image is to create a custom image.
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The following example shows the form for the two lines you need:
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</para>
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<programlisting>
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IMAGE_INSTALL = "task-poky-x11-base package1 package2"
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inherit poky-image
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</programlisting>
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<para>
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By creating a custom image, a developer has total control
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over the contents of the image.
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It is important to use the correct names of packages in the
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<glossterm><link linkend='var-IMAGE_INSTALL'>IMAGE_INSTALL</link></glossterm> variable.
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You must use the OpenEmbedded notation and not the Debian notation for the names
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(e.g. "glibc-dev" instead of "libc6-dev").
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</para>
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<para>
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The other method for creating a custom image is to modify an existing image.
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For example, if a developer wants to add "strace" into "poky-image-sato", they can use
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the following recipe:
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</para>
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<programlisting>
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require poky-image-sato.bb
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IMAGE_INSTALL += "strace"
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</programlisting>
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</section>
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<section id='usingpoky-extend-customimage-customtasks'>
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<title>Customising Images Using Custom Tasks</title>
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<para>
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For complex custom images, the best approach is to create a custom task package
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that is used to build the image or images.
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A good example of a tasks package is <filename>meta/recipes-sato/tasks/task-poky.bb
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</filename>.
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The <glossterm><link linkend='var-PACKAGES'>PACKAGES</link></glossterm>
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variable lists the task packages to build along with the complementary
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-dbg and -dev packages.
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For each package added, you can use
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<glossterm><link linkend='var-PACKAGES'>RDEPENDS</link></glossterm>
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and <glossterm><link linkend='var-PACKAGES'>RRECOMMENDS</link></glossterm>
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entries to provide a list of packages the parent task package should contain.
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Following is an example:
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</para>
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<para>
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<programlisting>
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DESCRIPTION = "My Custom Tasks"
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PACKAGES = "\
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task-custom-apps \
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task-custom-apps-dbg \
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task-custom-apps-dev \
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task-custom-tools \
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task-custom-tools-dbg \
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task-custom-tools-dev \
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"
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RDEPENDS_task-custom-apps = "\
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dropbear \
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portmap \
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psplash"
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RDEPENDS_task-custom-tools = "\
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oprofile \
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oprofileui-server \
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lttng-control \
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lttng-viewer"
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RRECOMMENDS_task-custom-tools = "\
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kernel-module-oprofile"
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</programlisting>
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</para>
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<para>
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In the previous example, two task packages are created with their dependencies and their
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recommended package dependencies listed: <filename>task-custom-apps</filename>, and
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<filename>task-custom-tools</filename>.
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To build an image using these task packages, you need to add
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"task-custom-apps" and/or "task-custom-tools" to <glossterm><link
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linkend='var-IMAGE_INSTALL'>IMAGE_INSTALL</link></glossterm> or other forms
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of image dependencies as described in other areas of this section.
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</para>
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</section>
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<section id='usingpoky-extend-customimage-imagefeatures'>
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<title>Customising Images Using Custom IMAGE_FEATURES</title>
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<para>
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Ultimately users might want to add extra image "features" as used by Poky with the
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<glossterm><link linkend='var-IMAGE_FEATURES'>IMAGE_FEATURES</link></glossterm>
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variable.
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To create these features, the best reference is
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<filename>meta/classes/poky-image.bbclass</filename>, which shows how poky achieves this.
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In summary, the file looks at the contents of the
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<glossterm><link linkend='var-IMAGE_FEATURES'>IMAGE_FEATURES</link></glossterm>
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variable and then maps them into a set of tasks or packages.
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Based on this information the <glossterm><link linkend='var-IMAGE_INSTALL'> IMAGE_INSTALL</link>
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</glossterm> variable is generated automatically.
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Users can add extra features by extending the class or creating a custom class for use
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with specialized image <filename>.bb</filename> files.
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</para>
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</section>
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<section id='usingpoky-extend-customimage-localconf'>
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<title>Customising Images Using local.conf</title>
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<para>
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It is possible to customise image contents by abusing variables used by distribution
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maintainers in local.conf.
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This method only allows the addition of packages and is not recommended.
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</para>
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<para>
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For example, to add the "strace" package into the image the you would add this to the
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<filename>local.conf</filename> file:
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</para>
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<programlisting>
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DISTRO_EXTRA_RDEPENDS += "strace"
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</programlisting>
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<para>
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However, since the <glossterm><link linkend='var-DISTRO_EXTRA_RDEPENDS'>
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DISTRO_EXTRA_RDEPENDS</link></glossterm> variable is for
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distribution maintainers, adding packages using this method is not as simple as adding
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them using a custom <filename>.bb</filename> file.
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Using the <filename>local.conf</filename> file method could result in some packages
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requiring recreation.
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For example, if packages were previously created and the image was rebuilt then the packages
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would need to be recreated.
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</para>
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<para>
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Cleaning task-* packages is required because they use the
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<glossterm><link linkend='var-DISTRO_EXTRA_RDEPENDS'>
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DISTRO_EXTRA_RDEPENDS</link></glossterm> variable.
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You do not have to build them by hand because Poky images depend on the packages they contain.
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This means dependencies are automatically built when the image builds.
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For this reason we don't use the "rebuild" task.
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In this case the "rebuild" task does does not care about
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dependencies - it only rebuilds the specified package.
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</para>
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<programlisting>
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$ bitbake -c clean task-boot task-base task-poky
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$ bitbake poky-image-sato
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</programlisting>
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</section>
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</section>
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<section id="platdev-newmachine">
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<title>Porting Poky to a New Machine</title>
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<para>
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Adding a new machine to Poky is a straightforward process.
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This section provides information that gives you an idea of the changes you must make.
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The information covers adding machines similar to those Poky already supports.
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Although well within the capabilities of Poky, adding a totally new architecture might require
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changes to <filename>gcc/glibc</filename> and to the site information.
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Consequently, the information is beyond the scope of this manual.
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</para>
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<section id="platdev-newmachine-conffile">
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<title>Adding the Machine Configuration File</title>
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<para>
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To add a machine configuration you need to add a <filename>.conf</filename> file
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with details of the device being added to <filename>conf/machine/</filename>.
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The name of the file determines the name Poky uses to reference the new machine.
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</para>
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<para>
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The most important variables to set in this file are <glossterm>
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<link linkend='var-TARGET_ARCH'>TARGET_ARCH</link></glossterm>
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(e.g. "arm"), <glossterm><link linkend='var-PREFERRED_PROVIDER'>
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PREFERRED_PROVIDER</link></glossterm>_virtual/kernel (see below) and
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<glossterm><link linkend='var-MACHINE_FEATURES'>MACHINE_FEATURES
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</link></glossterm> (e.g. "kernel26 apm screen wifi").
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You might also need other variables like <glossterm><link linkend='var-SERIAL_CONSOLE'>SERIAL_CONSOLE
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</link></glossterm> (e.g. "115200 ttyS0"), <glossterm>
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<link linkend='var-KERNEL_IMAGETYPE'>KERNEL_IMAGETYPE</link>
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</glossterm> (e.g. "zImage") and <glossterm><link linkend='var-IMAGE_FSTYPES'>
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IMAGE_FSTYPES</link></glossterm> (e.g. "tar.gz jffs2").
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You can find full details on these variables in the reference section.
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You can leverage many existing machine <filename>.conf</filename> files from
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<filename>meta/conf/machine/</filename>.
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</para>
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</section>
|
|
|
|
<section id="platdev-newmachine-kernel">
|
|
<title>Adding a Kernel for the Machine</title>
|
|
<para>
|
|
Poky needs to be able to build a kernel for the machine.
|
|
You need to either create a new kernel recipe for this machine, or extend an
|
|
existing recipe.
|
|
You can find several kernel examples in the <filename>meta/recipes-kernel/linux</filename>
|
|
directory that can be used as references.
|
|
</para>
|
|
<para>
|
|
If you are creating a new recipe, the "normal" recipe-writing rules apply for setting
|
|
up a <glossterm><link linkend='var-SRC_URI'>SRC_URI</link></glossterm>.
|
|
This means specifying any necessary patches and setting <glossterm>
|
|
<link linkend='var-S'>S</link></glossterm> to point at the source code.
|
|
You need to create a "configure" task that configures the unpacked kernel with a defconfig.
|
|
You can do this by using a <filename>make defconfig</filename> command or
|
|
more commonly by copying in a suitable defconfig and and then running
|
|
<filename>make oldconfig</filename>.
|
|
By making use of "inherit kernel" and potentially some of the
|
|
<filename>linux-*.inc</filename> files, most other functionality is
|
|
centralized and the the defaults of the class normally work well.
|
|
</para>
|
|
<para>
|
|
If you are extending an existing kernel, it is usually a matter of adding a
|
|
suitable <filename>defconfig</filename> file.
|
|
The file needs to be added into a location similar to <filename>defconfig</filename> files
|
|
used for other machines in a given kernel.
|
|
A possible way to do this is by listing the file in the
|
|
<glossterm><link linkend='var-SRC_URI'>SRC_URI</link></glossterm>
|
|
and adding the machine to the expression in
|
|
<glossterm><link linkend='var-COMPATIBLE_MACHINE'>COMPATIBLE_MACHINE</link></glossterm>:
|
|
</para>
|
|
<programlisting>
|
|
COMPATIBLE_MACHINE = '(qemux86|qemumips)'
|
|
</programlisting>
|
|
</section>
|
|
|
|
<section id="platdev-newmachine-formfactor">
|
|
<title>Adding a Formfactor Configuration File</title>
|
|
<para>
|
|
A formfactor configuration file provides information about the
|
|
target hardware on which Poky is running, and that Poky cannot
|
|
obtain from other sources such as the kernel.
|
|
Some examples of information contained in a formfactor configuration file include
|
|
framebuffer orientation, whether or not the system has a keyboard,
|
|
the positioning of the keyboard in relation to the screen, and
|
|
screen resolution.
|
|
</para>
|
|
<para>
|
|
Reasonable defaults are used in most cases, but if customization is
|
|
necessary you need to create a <filename>machconfig</filename> file
|
|
under <filename>meta/packages/formfactor/files/MACHINENAME/</filename>,
|
|
where <literal>MACHINENAME</literal> is the name for which this infomation
|
|
applies.
|
|
For information about the settings available and the defaults, see
|
|
<filename>meta/packages/formfactor/files/config</filename>.
|
|
Following is an example for qemuarm:
|
|
</para>
|
|
<programlisting>
|
|
HAVE_TOUCHSCREEN=1
|
|
HAVE_KEYBOARD=1
|
|
|
|
DISPLAY_CAN_ROTATE=0
|
|
DISPLAY_ORIENTATION=0
|
|
#DISPLAY_WIDTH_PIXELS=640
|
|
#DISPLAY_HEIGHT_PIXELS=480
|
|
#DISPLAY_BPP=16
|
|
DISPLAY_DPI=150
|
|
DISPLAY_SUBPIXEL_ORDER=vrgb
|
|
</programlisting>
|
|
</section>
|
|
</section>
|
|
|
|
<section id="usingpoky-changes">
|
|
<title>Making and Maintaining Changes</title>
|
|
<para>
|
|
Because Poky offers extreme configurability and fliexibility, we recognize that people will want
|
|
to extend, configure or optimise Poky for their specific uses.
|
|
To best keep pace with future Poky changes we recommend you make controlled changes to Poky.
|
|
</para>
|
|
<para>
|
|
Poky supports the idea of <link linkend='usingpoky-changes-layers'>"layers"</link>.
|
|
If you use layers properly you can ease future upgrades and allow segregation
|
|
between the Poky core and a given developer's changes.
|
|
The following section provides more advice on managing changes to Poky.
|
|
</para>
|
|
|
|
<section id="usingpoky-changes-layers">
|
|
<title>Bitbake Layers</title>
|
|
<para>
|
|
Often, people want to extend Poky either by adding packages
|
|
or by overriding files contained within Poky to add their own
|
|
functionality.
|
|
Bitbake has a powerful mechanism called
|
|
"layers", which provides a way to handle this extension in a fully
|
|
supported and non-invasive fashion.
|
|
</para>
|
|
<para>
|
|
The Poky tree includes several additional layers such as meta-emenlow and meta-extras
|
|
that demonstrate this functionality.
|
|
The meta-emenlow layer is an example layer that by default is enabled.
|
|
However, the meta-extras repostory is not enabled by default.
|
|
It is easy though to enable any layer.
|
|
You simply add the layer's path to the
|
|
<glossterm><link linkend='var-BBLAYERS'>BBLAYERS</link></glossterm> variable in your
|
|
<filename>bblayers.conf</filename> file.
|
|
The following example shows how to enable meta-extras in the Poky build:
|
|
</para>
|
|
<para>
|
|
<literallayout class='monospaced'>LCONF_VERSION = "1"
|
|
|
|
BBFILES ?= ""
|
|
BBLAYERS = " \
|
|
/path/to/poky/meta \
|
|
/path/to/poky/meta-emenlow \
|
|
/path/to/poky/meta-extras \
|
|
"
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
Bitbake parses each <filename>conf/layer.conf</filename> file for each layer in BBLAYERS
|
|
and adds the recipes, classes and configuration contained within the layer to Poky.
|
|
To create your own layer, independent of the main Poky repository,
|
|
simply create a directory with a <filename>conf/layer.conf</filename> file and
|
|
add the directory to your <filename>bblayers.conf</filename> file.
|
|
</para>
|
|
<para>
|
|
The <filename>meta-emenlow/conf/layer.conf</filename> file demonstrates the required syntax:
|
|
<literallayout class='monospaced'># We have a conf and classes directory, add to BBPATH
|
|
BBPATH := "${BBPATH}:${LAYERDIR}"
|
|
|
|
# We have a recipes directory containing both .bb and .bbappend files, add to BBFILES
|
|
BBFILES := "${BBFILES} ${LAYERDIR}/recipes/*/*.bb \
|
|
${LAYERDIR}/recipes/*/*.bbappend"
|
|
|
|
BBFILE_COLLECTIONS += "emenlow"
|
|
BBFILE_PATTERN_emenlow := "^${LAYERDIR}/"
|
|
BBFILE_PRIORITY_emenlow = "6"
|
|
</literallayout>
|
|
</para>
|
|
<para>
|
|
In the previous example, the recipes for the layers are added to
|
|
<glossterm> <link linkend='var-BBFILES'>BBFILES</link></glossterm>.
|
|
The <glossterm><link linkend='var-BBFILE_COLLECTIONS'>BBFILE_COLLECTIONS</link></glossterm>
|
|
variable is then appended with the layer name.
|
|
The <glossterm><link linkend='var-BBFILE_PATTERN'>BBFILE_PATTERN</link></glossterm> variable
|
|
immediately expands with a regular expression used to match files from BBFILES into
|
|
a particular layer, in this case by using the base pathname.
|
|
The <glossterm><link linkend='var-BBFILE_PRIORITY'>BBFILE_PRIORITY</link></glossterm> variable
|
|
then assigns different priorities to the files in different layers.
|
|
This technique useful in situations where the same package might appear in multiple
|
|
layers and allows you to choose what layer should take precedence.
|
|
</para>
|
|
<para>
|
|
Note the use of the <glossterm><link linkend='var-LAYERDIR'>LAYERDIR</link></glossterm>
|
|
variable with the immediate expansion operator.
|
|
The LAYERDIR variable expands to the directory of the current layer and
|
|
requires the immediate expansion operator so that Bitbake does not wait to expand the variable
|
|
when it's parsing a different directory.
|
|
</para>
|
|
<para>
|
|
Bitbake can locate where other bbclass and configuration files are applied through
|
|
the <glossterm><link linkend='var-BBPATH'>BBPATH</link></glossterm>
|
|
environment variable.
|
|
For these cases, Bitake uses the first file with the matching name found in BBPATH.
|
|
This is similar to the way the PATH variable is used for binaries.
|
|
We recommend, therefore, that you use unique bbclass and configuration file names in your
|
|
custom layer.
|
|
</para>
|
|
<para>
|
|
We also recommend the following:
|
|
<itemizedlist>
|
|
<listitem><para>Store custom layers in a git repository that uses the
|
|
meta-prvt-XXXX format.</para></listitem>
|
|
<listitem><para>Clone the repository alongside other meta directories in the Poky
|
|
tree.</para></listitem>
|
|
</itemizedlist>
|
|
Following these recommendations keeps your Poky tree and its configuration entirely
|
|
inside POKYBASE.
|
|
</para>
|
|
</section>
|
|
|
|
<section id="usingpoky-changes-commits">
|
|
<title>Committing Changes</title>
|
|
<para>
|
|
Modifications to Poky are often managed under some kind of source
|
|
revision control system.
|
|
Because some simple practices can significantly improve usability, policy for committing changes
|
|
is important.
|
|
Following are suggestions for committing changes to the Poky core:
|
|
</para>
|
|
<para>
|
|
It helps to use a consistent documentation style when committing changes.
|
|
We have found the following style works well.
|
|
<itemizedlist>
|
|
<listitem><para>The first line of the commit summarizes the change and begins with the
|
|
name of the affected package or packages.
|
|
However, not all changes apply to specific packages.
|
|
Consequently, the prefix could also be a machine name or class name for
|
|
example.</para></listitem>
|
|
<listitem><para>The second part of the commit (if needed) is a longer more detailed
|
|
description of the changes. Placing a blank line between the first and second parts
|
|
helps with readability.</para></listitem>
|
|
</itemizedlist>
|
|
</para>
|
|
<para>
|
|
Following is an example commit:
|
|
</para>
|
|
<literallayout class='monospaced'>
|
|
bitbake/data.py: Add emit_func() and generate_dependencies() functions
|
|
|
|
These functions allow generation of dependency data between funcitons and
|
|
variables allowing moves to be made towards generating checksums and allowing
|
|
use of the dependency information in other parts of bitbake.
|
|
|
|
Signed-off-by: Richard Purdie rpurdie@linux.intel.com
|
|
</literallayout>
|
|
|
|
<para>
|
|
All commits should be self-contained such that they leave the
|
|
metadata in a consistent state that builds both before and after the
|
|
commit is made.
|
|
Besides being a good policy to follow, this helps ensure the autobuilder test results
|
|
are valid.
|
|
</para>
|
|
</section>
|
|
|
|
<section id="usingpoky-changes-prbump">
|
|
<title>Package Revision Incrementing</title>
|
|
<para>
|
|
If a committed change results in changing the package output
|
|
then the value of the <glossterm><link linkend='var-PR'>PR</link>
|
|
</glossterm> variable needs to be increased ('bumped') as part of that commit.
|
|
This means that for new recipes you be sure to add the PR variable and set its initial value
|
|
equal to "r0".
|
|
Not initially defining PR makes makes it easy to miss when you bump a package.
|
|
Note that you can only use integer values for the PR variable.
|
|
</para>
|
|
<para>
|
|
When upgrading the version of a package the (<glossterm><link
|
|
linkend='var-PV'>PV</link></glossterm>) and PR variables should be reset to "r0".
|
|
</para>
|
|
<para>
|
|
Usually a package version only increases.
|
|
However, if for some reason PV changes but does not increase, you can increase the
|
|
<glossterm><link linkend='var-PE'>PE</link></glossterm> variable (Package Epoch).
|
|
The PE variable defaults to '0'.
|
|
</para>
|
|
<para>
|
|
Version numbering strives to follow the
|
|
<ulink url='http://www.debian.org/doc/debian-policy/ch-controlfields.html'>
|
|
Debian Version Field Policy Guidelines</ulink>.
|
|
These guidelines define how versions are compared and what "increasing" a version means.
|
|
</para>
|
|
<para>
|
|
There are two reasons for following these guidelines.
|
|
First, to ensure that when a developer updates and rebuilds, they get all the changes to
|
|
the repository and don't have to remember to rebuild any sections.
|
|
Second, to ensure that target users are able to upgrade their
|
|
devices using package manager commands such as <filename>
|
|
opkg upgrade</filename> (or similar commands for dpkg/apt or rpm-based systems).
|
|
</para>
|
|
<para>
|
|
The goal is to ensure Poky has upgradable packages in all cases.
|
|
</para>
|
|
</section>
|
|
|
|
<section id="usingpoky-changes-collaborate">
|
|
<title>Using Poky in a Team Environment</title>
|
|
<para>
|
|
It may not be immediately clear how you can use Poky in a team environment,
|
|
or scale it for a large team of developers.
|
|
The specifics of any situation determine the best solution.
|
|
Granted that Poky offers immense flexibility regarding this, practices do exist
|
|
that experience has shown work well.
|
|
</para>
|
|
<para>
|
|
The core component of any development effort with Poky is often an
|
|
automated build testing framework and an image generation process.
|
|
You can use these core components to check that the metadata is buildable,
|
|
highlight when commits break the builds, and provide up-to-date images that
|
|
allow people to test the end result and use it as a base platform for further
|
|
development.
|
|
Experience shows that buildbot is a good fit for this role.
|
|
What works well is to configure buildbot to make two types of builds:
|
|
incremental and full (from scratch).
|
|
See <ulink url='http://autobuilder.pokylinux.org:8010'>poky autobuilder</ulink>
|
|
for an example implementation that uses buildbot.
|
|
</para>
|
|
<para>
|
|
You can tie incremental builds to a commit hook that triggers the build
|
|
each time a commit is made to the metadata.
|
|
This practice results in useful acid tests that determine whether a given commit
|
|
breaks the build in some serious way.
|
|
Associating a build to a commit can catch a lot of simple errors.
|
|
Furthermore, the tests are fast so developers can get quick feedback on changes.
|
|
</para>
|
|
<para>
|
|
Full builds build and test everything from the ground up.
|
|
They usually happen at preset times like during the night when the machine
|
|
load is low.
|
|
</para>
|
|
<para>
|
|
Most teams have many pieces of software undergoing active development at any given time.
|
|
You can derive large benefits by putting these pieces under the control of a source
|
|
control system that is compatible with Poky (i.e. git or svn).
|
|
You can then set the autobuilder to pull the latest revisions of the packages
|
|
and test the latest commits by the builds.
|
|
This practice quickly highlights issues.
|
|
Poky easily supports testing configurations that use both a stable known good revision
|
|
and a floating revision.
|
|
Poky can also take just the changes from specific source control branches.
|
|
This capability allows you to track and test specific changes.
|
|
</para>
|
|
<para>
|
|
Perhaps the hardest part of setting this up is defining the software project or
|
|
Poky metadata policies that surround the different source control systems.
|
|
Of course circumstances will be different in each case.
|
|
However, this situation reveals one of Poky's advantages - the system itself does not
|
|
force any particular policy on users, unlike a lot of build systems.
|
|
The system allows the best policy to be chosen for the given circumstances.
|
|
</para>
|
|
</section>
|
|
|
|
<section id="usingpoky-changes-updatingimages">
|
|
<title>Updating Existing Images</title>
|
|
<para>
|
|
Often, rather than reflashing a new image you might wish to install updated
|
|
packages into an existing running system.
|
|
You can do this by first sharing the
|
|
<filename class="directory">tmp/deploy/ipk/</filename> directory
|
|
through a web server and then by changing <filename>/etc/opkg/base-feeds.conf</filename>
|
|
to point at the shared server.
|
|
Following is an example:
|
|
</para>
|
|
<literallayout class='monospaced'>
|
|
src/gz all http://www.mysite.com/somedir/deploy/ipk/all
|
|
src/gz armv7a http://www.mysite.com/somedir/deploy/ipk/armv7a
|
|
src/gz beagleboard http://www.mysite.com/somedir/deploy/ipk/beagleboard</literallayout>
|
|
</section>
|
|
</section>
|
|
|
|
<section id="usingpoky-modifing-packages">
|
|
<title>Modifying Package Source Code</title>
|
|
<para>
|
|
Although Poky is usually used to build software, you can use it to modify software.
|
|
</para>
|
|
<para>
|
|
During building, source is available in the
|
|
<glossterm><link linkend='var-WORKDIR'>WORKDIR</link></glossterm> directory.
|
|
The actual location depends on the type of package and the architecture of the target device.
|
|
For a standard recipe not related to
|
|
<glossterm><link linkend='var-MACHINE'>MACHINE</link></glossterm> the location is
|
|
<filename>tmp/work/PACKAGE_ARCH-poky-TARGET_OS/PN-PV-PR/</filename>.
|
|
For target device-dependent packages you should use the MACHINE variable instead of
|
|
<glossterm><link linkend='var-PACKAGE_ARCH'>PACKAGE_ARCH</link></glossterm>
|
|
in the directory name.
|
|
</para>
|
|
<tip>
|
|
<para>
|
|
Be sure the package recipe sets the
|
|
<glossterm><link linkend='var-S'>S</link></glossterm> variable to something
|
|
other than standard <filename>WORKDIR/PN-PV/</filename> value.
|
|
</para>
|
|
</tip>
|
|
<para>
|
|
After building a package, you can modify the package source code without problems.
|
|
The easiest way to test your changes is by calling the "compile" task as shown in the
|
|
following example:
|
|
</para>
|
|
|
|
<programlisting>
|
|
bitbake -c compile -f NAME_OF_PACKAGE
|
|
</programlisting>
|
|
|
|
<para>
|
|
The "-f" or "--force" option forces re-execution of the specified task.
|
|
You can call other tasks this way as well.
|
|
But note that all the modifications in
|
|
<glossterm><link linkend='var-WORKDIR'>WORKDIR</link></glossterm>
|
|
are gone once you execute "-c clean" for a package.
|
|
</para>
|
|
|
|
<section id="usingpoky-modifying-packages-quilt">
|
|
<title>Modifying Package Source Code with quilt</title>
|
|
<para>
|
|
By default Poky uses <ulink url='http://savannah.nongnu.org/projects/quilt'>quilt</ulink>
|
|
to manage patches in the <filename>do_patch</filename> task.
|
|
This is a powerful tool that you can use to track all modifications to package sources.
|
|
</para>
|
|
<para>
|
|
Before modifying source code, it is important to notify quilt so it can track the changes
|
|
into the new patch file:
|
|
|
|
<programlisting>
|
|
quilt new NAME-OF-PATCH.patch
|
|
</programlisting>
|
|
|
|
After notifying quilt, add all modified files into that patch:
|
|
<programlisting>
|
|
quilt add file1 file2 file3
|
|
</programlisting>
|
|
|
|
You can now start editing.
|
|
Once you are done editing, you need to use quilt to generate the final patch that
|
|
will contain all your modifications.
|
|
<programlisting>
|
|
quilt refresh
|
|
</programlisting>
|
|
|
|
You can find the resulting patch file in the
|
|
<filename class="directory">patches/</filename> subdirectory of the source
|
|
(<glossterm><link linkend='var-S'>S</link></glossterm>) directory.
|
|
For future builds you should copy the patch into Poky metadata and add it into the
|
|
<glossterm><link linkend='var-SRC_URI'>SRC_URI</link></glossterm> of a recipe.
|
|
Here is an example:
|
|
<programlisting>
|
|
SRC_URI += "file://NAME-OF-PATCH.patch"
|
|
</programlisting>
|
|
Finally, don't forget to 'bump' the
|
|
<glossterm><link linkend='var-PR'>PR</link></glossterm> value in the same recipe.
|
|
The resulting packages have changed.
|
|
</para>
|
|
</section>
|
|
|
|
</section>
|
|
|
|
<section id="usingpoky-configuring-LIC_FILES_CHKSUM">
|
|
<title>Track License Change</title>
|
|
<para>
|
|
The license of an upstream project might change in the future.
|
|
To address this situation, Poky uses the
|
|
<glossterm><link linkend='var-LIC_FILES_CHKSUM'>LIC_FILES_CHKSUM</link></glossterm> variable
|
|
to track license changes.
|
|
</para>
|
|
|
|
<section id="usingpoky-specifying-LIC_FILES_CHKSUM">
|
|
<title>Specifying the LIC_FILES_CHKSUM Variable </title>
|
|
<para>
|
|
The <glossterm><link linkend='var-LIC_FILES_CHKSUM'>LIC_FILES_CHKSUM</link></glossterm>
|
|
variable contains checksums of the license text in the recipe source code.
|
|
Poky uses this to track changes in the license text of the source code files.
|
|
Following is an example of LIC_FILES_CHKSUM:
|
|
</para>
|
|
<programlisting>
|
|
LIC_FILES_CHKSUM = "file://COPYING; md5=xxxx \
|
|
file://licfile1.txt; beginline=5; endline=29;md5=yyyy \
|
|
file://licfile2.txt; endline=50;md5=zzzz \
|
|
..."
|
|
</programlisting>
|
|
<para>
|
|
Poky uses the <glossterm><link linkend='var-S'>S</link></glossterm> variable as the
|
|
default directory used when searching files listed in LIC_FILES_CHKSUM.
|
|
The previous example employs the default directory.
|
|
</para>
|
|
<para>
|
|
You can also use relative paths as shown in the following example:
|
|
</para>
|
|
<programlisting>
|
|
LIC_FILES_CHKSUM = "file://src/ls.c;startline=5;endline=16;\
|
|
md5=bb14ed3c4cda583abc85401304b5cd4e"
|
|
LIC_FILES_CHKSUM = "file://../license.html;md5=5c94767cedb5d6987c902ac850ded2c6"
|
|
</programlisting>
|
|
<para>
|
|
In this example the first line locates a file in
|
|
<glossterm><link linkend='var-S'>S</link></glossterm><filename>/src/ls.c</filename>.
|
|
The second line refers to a file in
|
|
<glossterm><link linkend='var-WORKDIR'>WORKDIR</link></glossterm>, which is the parent
|
|
of <glossterm><link linkend='var-S'>S</link></glossterm>.
|
|
</para>
|
|
</section>
|
|
|
|
<section id="usingpoky-LIC_FILES_CHKSUM-explanation-of-syntax">
|
|
<title>Explanation of Syntax</title>
|
|
<para>
|
|
As mentioned in the previous section the LIC_FILES_CHKSUM variable lists all the
|
|
important files that contain the license text for the source code.
|
|
Using this variable you can specify the line on which the license text starts and ends
|
|
by supplyiing "beginline" and "endline" parameters.
|
|
If you do not use the "beginline" parameter then it is assumed that the text begins on the
|
|
first line of the file.
|
|
Similarly, if you do not use the "endline" parameter it is assumed that the license text
|
|
ends as the last line of the file.
|
|
</para>
|
|
<para>
|
|
The "md5" parameter stores the md5 checksum of the license text.
|
|
If the license text changes in any way as compared to this parameter
|
|
then a mis-match occurs.
|
|
This mismatch triggers a build failure and notifies the developer.
|
|
Notification allows the developer to review and address the license text changes.
|
|
Also note that if a mis-match occurs during the build, the correct md5
|
|
checksum is placed in the build log, which can be easily copied to a .bb file.
|
|
</para>
|
|
<para>
|
|
There is no limit to how many files you can specify using the LIC_FILES_CHKSUM variable.
|
|
Generally, however, every project requires a few specifications for license tracking.
|
|
Many projects have a "COPYING" file that stores the license information for all the source
|
|
code files.
|
|
This practice allow you to just track the "COPYING" file as long as it is kept up to date.
|
|
</para>
|
|
<tip>
|
|
If you specify an empty or invalid "md5" parameter, bitback returns an md5 mis-match
|
|
error and displays the correct "md5" parameter value during the build. The correct parameter
|
|
is also captured in the build log.
|
|
</tip>
|
|
<tip>
|
|
If the whole file contains only license text, you do not need to use the "beginline" and
|
|
"endline" parameters.
|
|
</tip>
|
|
</section>
|
|
</section>
|
|
|
|
<section id="usingpoky-configuring-DISTRO_PN_ALIAS">
|
|
<title>Handling Package Name Alias</title>
|
|
<para>
|
|
Sometimes a package name you are using might exist under an alias or as a similarly named
|
|
package in a different distribution.
|
|
Poky implements a distro_check task that automatically connects to major distributions
|
|
and checks for these situations.
|
|
If the package exists under a different name in a different distribution you get a
|
|
distro_check mismatch.
|
|
You can resolve this problem by defining a per-distro recipe name alias using the
|
|
<glossterm><link linkend='var-DISTRO_PN_ALIAS'>DISTRO_PN_ALIAS</link></glossterm> variable.
|
|
</para>
|
|
|
|
<section id="usingpoky-specifying-DISTRO_PN_ALIAS">
|
|
<title>Specifying the DISTRO_PN_ALIAS Variable</title>
|
|
<para>
|
|
Following is an example that shows how you specify the DISTRO_PN_ALIAS variable:
|
|
<programlisting>
|
|
DISTRO_PN_ALIAS_pn-PACKAGENAME = "distro1=package_name_alias1 \
|
|
distro2=package_name_alias2 \
|
|
distro3=package_name_alias3 \
|
|
..."
|
|
</programlisting>
|
|
</para>
|
|
<para>
|
|
If you have more than one distribution alias separate them with a space.
|
|
Note that Poky currently automatically checks the Fedora, OpenSuSE, Debian, Ubuntu,
|
|
and Mandriva distributions for source package recipes without having to specify them
|
|
using the DISTRO_PN_ALIAS variable.
|
|
For example, the following command generates a report that lists the Linux distributions
|
|
that include the sources for each of the Poky recipes.
|
|
<literallayout class='monospaced'>
|
|
$ bitbake world -f -c distro_check
|
|
</literallayout>
|
|
The results are stored in the <filename>build/tmp/log/distro_check-${DATETIME}.results</filename>
|
|
file.
|
|
</para>
|
|
</section>
|
|
</section>
|
|
</chapter>
|
|
|
|
<!--
|
|
vim: expandtab tw=80 ts=4
|
|
-->
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