950 lines
42 KiB
XML
950 lines
42 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 gives information about how to extend the functionality
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already present in Poky, documenting standard tasks such as adding new
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software packages, extending or customising images or porting poky to
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new hardware (adding a new machine). It also contains advice about how
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to manage the process of making changes to Poky to achieve 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 package into Poky you need to write a recipe for it.
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Writing a recipe means creating a .bb file which sets various
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variables. The variables
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useful for recipes are detailed in the <link linkend='ref-varlocality-recipe-required'>
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recipe reference</link> section along with more detailed information
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about issues such as recipe naming.
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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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someone else hasn't written one already. OpenEmbedded is a good place
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to look as it has a wider scope and hence a wider range of packages.
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Poky aims to be compatible with OpenEmbedded so 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. There are some examples below of how to add
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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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To build an application from a single file stored locally requires a
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recipe which has the file listed in the <glossterm><link
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linkend='var-SRC_URI'>SRC_URI</link></glossterm> variable. In addition
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the <function>do_compile</function> and <function>do_install</function>
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tasks need to be manually written. The <glossterm><link linkend='var-S'>
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S</link></glossterm> variable defines the directory containing the source
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code which in this case is set equal to <glossterm><link linkend='var-WORKDIR'>
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WORKDIR</link></glossterm>, 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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LIC_FILES_CHKSUM = "file://COPYING;md5=ae764cfda68da96df20af9fbf9fe49bd"
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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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As a result of the build process "helloworld" and "helloworld-dbg"
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packages will be built.
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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 which use autotools (autoconf, automake)
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require a recipe which has a source archive listed in
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<glossterm><link
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linkend='var-SRC_URI'>SRC_URI</link></glossterm> and
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<command>inherit autotools</command> to instruct BitBake to use the
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<filename>autotools.bbclass</filename> which has
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definitions of all the steps
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needed to build an autotooled application.
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The result of the build will be automatically packaged and if
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the application uses NLS to localise then packages with
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locale information will be generated (one package per
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language).
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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=ae764cfda68da96df20af9fbf9fe49bd"
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SRC_URI = "${GNU_MIRROR}/hello/hello-${PV}.tar.bz2"
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inherit autotools
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</programlisting>
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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 which use GNU make require a recipe which has
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the source archive listed in <glossterm><link
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linkend='var-SRC_URI'>SRC_URI</link></glossterm>.
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Adding a <function>do_compile</function> step
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is not needed as by default BitBake will start the "make"
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command to compile the application. If there is a need for
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additional options to make then they should be stored in the
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<glossterm><link
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linkend='var-EXTRA_OEMAKE'>EXTRA_OEMAKE</link></glossterm> variable - BitBake
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will pass them into the GNU
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make invocation. A <function>do_install</function> task is required
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- otherwise BitBake will run an empty <function>do_install</function>
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task by default.
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</para>
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<para>
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Some applications may require extra parameters to be passed to
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the compiler, for example an additional header path. This can
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be done buy adding to the <glossterm><link
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linkend='var-CFLAGS'>CFLAGS</link></glossterm> variable, as in the example below.
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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"
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HOMEPAGE = "http://www.linux-mtd.infradead.org/"
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LICENSE = "GPLv2"
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LIC_FILES_CHKSUM = "file://COPYING;md5=ae764cfda68da96df20af9fbf9fe49bd"
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SRC_URI = "ftp://ftp.infradead.org/pub/mtd-utils/mtd-utils-${PV}.tar.gz"
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CFLAGS_prepend = "-I ${S}/include "
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do_install() {
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oe_runmake install DESTDIR=${D}
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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 packages content</title>
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<para>
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The variables <glossterm><link
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linkend='var-PACKAGES'>PACKAGES</link></glossterm> and
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<glossterm><link linkend='var-FILES'>FILES</link></glossterm> are used to split an
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application into multiple packages.
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</para>
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<para>
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Below the "libXpm" recipe is used as an example. By
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default the "libXpm" recipe generates one package
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which contains the library
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and also a few binaries. The recipe can be adapted to
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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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LIC_FILES_CHKSUM = "file://COPYING;md5=ae764cfda68da96df20af9fbf9fe49bd"
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DEPENDS += "libxext"
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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 this example we want to ship the "sxpm" and "cxpm" binaries
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in separate packages. Since "bindir" would be packaged into the
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main <glossterm><link linkend='var-PN'>PN</link></glossterm>
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package as standard we prepend the <glossterm><link
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linkend='var-PACKAGES'>PACKAGES</link></glossterm> variable so
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additional package names are added to the start of list. The
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extra <glossterm><link linkend='var-PN'>FILES</link></glossterm>_*
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variables then contain information to specify which files and
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directories goes into which package.
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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
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a <function>pkg_postinst_PACKAGENAME()</function>
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function to the .bb file
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where PACKAGENAME is the name of the package to attach
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the postinst script to. 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
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gets called when the rootfs is made. If the script succeeds,
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the package is marked as installed. If the script fails,
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the package is marked as unpacked and the script will be
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executed again on the first boot of the image.
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</para>
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<para>
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Sometimes it is necessary that the execution of a post-installation
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script is delayed until the first boot, because the script
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needs to be executed on the device itself. To delay script execution
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until boot time, the post-installation function should have the
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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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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 structure above delays execution until first boot
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because the <glossterm><link
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linkend='var-D'>D</link></glossterm> variable points
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to the 'image'
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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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Poky images can be customised to satisfy
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particular requirements. Several methods are detailed below
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along with guidelines of when to use them.
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</para>
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<section id='usingpoky-extend-customimage-custombb'>
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<title>Customising Images through a custom image .bb files</title>
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<para>
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One way to get additional software into an image is by creating a
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custom image. The recipe will contain two lines:
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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. It is important to use
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the correct names of packages in the <glossterm><link
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linkend='var-IMAGE_INSTALL'>IMAGE_INSTALL</link></glossterm> variable.
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The names must be in
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the OpenEmbedded notation instead of Debian notation, for example
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"glibc-dev" instead of "libc6-dev" etc.
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</para>
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<para>
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The other method of creating a new image is by modifying
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an existing image. For example if a developer wants to add
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"strace" into "poky-image-sato" the following recipe can
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be used:
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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 through custom tasks</title>
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<para>
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For complex custom images, the best approach is to create a custom
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task package which is then used to build the image (or images). A good
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example of a tasks package is <filename>meta/packages/tasks/task-poky.bb
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</filename>. 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). For each package added,
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<glossterm><link linkend='var-PACKAGES'>RDEPENDS</link></glossterm> and
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<glossterm><link linkend='var-PACKAGES'>RRECOMMENDS</link></glossterm>
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entries can then be added each containing a list of packages the parent
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task package should contain. An example would be:
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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 this example, two tasks packages are created, task-custom-apps and
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task-custom-tools with the dependencies and recommended package dependencies
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listed. To build an image using these task packages, you would then 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 through custom <glossterm><link linkend='var-IMAGE_FEATURES'>IMAGE_FEATURES</link></glossterm></title>
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<para>
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Ultimately users may 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. To create these, the best reference is <filename>meta/classes/poky-image.bbclass</filename>
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which illustrates how poky achieves this. 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 based on this generates the <glossterm><link linkend='var-IMAGE_INSTALL'>
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IMAGE_INSTALL</link></glossterm> variable automatically. Extra features can be added by
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extending the class or creating a custom class for use with specialised image .bb 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 through local.conf</title>
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<para>
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It is possible to customise image contents by abusing
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variables used by distribution maintainers in local.conf.
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This method only allows the addition of packages and
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is not recommended.
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</para>
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<para>
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To add an "strace" package into the image the following is
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added to local.conf:
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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 this method does not make
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adding packages as simple as a custom .bb file. Using
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this method, a few packages will need to be recreated
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and the the image built.
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</para>
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<programlisting>
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bitbake -cclean task-boot task-base task-poky
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bitbake poky-image-sato
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</programlisting>
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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. There is no need to
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build them by hand as Poky images depend on the packages they contain so
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dependencies will be built automatically. For this reason we don't use the
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"rebuild" task in this case since "rebuild" does not care about
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dependencies - it only rebuilds the specified package.
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</para>
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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 and
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this section gives an idea of the changes that are needed. This guide is
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meant to cover adding machines similar to those Poky already supports.
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Adding a totally new architecture might require gcc/glibc changes as
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well as updates to the site information and, whilst well within Poky's
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capabilities, is outside the scope of this section.
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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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A .conf file needs to be added to conf/machine/ with details of the
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device being added. The name of the file determines the name Poky will
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use to reference this 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"). Other variables
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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") might also be
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needed. Full details on what these variables do and the meaning of
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their contents is available through the links.
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</para>
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</section>
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<section id="platdev-newmachine-kernel">
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<title>Adding a kernel for the machine</title>
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<para>
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Poky needs to be able to build a kernel for the machine. You need
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to either create a new kernel recipe for this machine or extend an
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existing recipe. There are plenty of kernel examples in the
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packages/linux directory which can be used as references.
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</para>
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<para>
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If creating a new recipe the "normal" recipe writing rules apply
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for setting up a <glossterm><link linkend='var-SRC_URI'>SRC_URI
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</link></glossterm> including any patches and setting <glossterm>
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<link linkend='var-S'>S</link></glossterm> to point at the source
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code. You will need to create a configure task which configures the
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unpacked kernel with a defconfig be that through a "make defconfig"
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command or more usually though copying in a suitable defconfig and
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running "make oldconfig". By making use of "inherit kernel" and also
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maybe some of the linux-*.inc files, most other functionality is
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centralised and the the defaults of the class normally work well.
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</para>
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<para>
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If extending an existing kernel it is usually a case of adding a
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suitable defconfig file in a location similar to that used by other
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machine's defconfig files in a given kernel, possibly listing it in
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the SRC_URI and adding the machine to the expression in <glossterm>
|
|
<link linkend='var-COMPATIBLE_MACHINE'>COMPATIBLE_MACHINE</link>
|
|
</glossterm>.
|
|
</para>
|
|
</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>
|
|
Sane defaults should be used in most cases, but if customisation 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, please see
|
|
<filename>meta/packages/formfactor/files/config</filename>.
|
|
</para>
|
|
</section>
|
|
</section>
|
|
|
|
<section id='usingpoky-changes'>
|
|
<title>Making and Maintaining Changes</title>
|
|
|
|
<para>
|
|
We recognise that people will want to extend/configure/optimise Poky for
|
|
their specific uses, especially due to the extreme configurability and
|
|
flexibility Poky offers. To ensure ease of keeping pace with future
|
|
changes in Poky we recommend making changes to Poky in a controlled way.
|
|
</para>
|
|
<para>
|
|
Poky supports the idea of <link
|
|
linkend='usingpoky-changes-layers'>"layers"</link> which when used
|
|
properly can massively ease future upgrades and allow segregation
|
|
between the Poky core and a given developer's changes. Some other advice on
|
|
managing changes to Poky is also given in the following section.
|
|
</para>
|
|
|
|
<section id="usingpoky-changes-layers">
|
|
<title>Bitbake Layers</title>
|
|
|
|
<para>
|
|
Often, people want to extend Poky either through adding packages
|
|
or 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 two additional layers which demonstrate
|
|
this functionality, meta-moblin and meta-extras.
|
|
The meta-extras repostory is not enabled by default but enabling
|
|
it is as easy as adding the layers path to the BBLAYERS variable in
|
|
your bblayers.conf, this is how all layers are enabled in Poky builds:
|
|
</para>
|
|
<para>
|
|
<literallayout class='monospaced'>LCONF_VERSION = "1"
|
|
|
|
BBFILES ?= ""
|
|
BBLAYERS = " \
|
|
/path/to/poky/meta \
|
|
/path/to/poky/meta-moblin \
|
|
/path/to/poky/meta-extras \
|
|
"
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
Bitbake parses the conf/layer.conf of each of the layers in BBLAYERS
|
|
to add the layers packages, classes and configuration to Poky.
|
|
To create your own layer, independent of the main Poky repository,
|
|
you need only create a directory with a conf/layer.conf file and
|
|
add the directory to your bblayers.conf.
|
|
</para>
|
|
|
|
<para>
|
|
The meta-extras layer.conf demonstrates the required syntax:
|
|
<literallayout class='monospaced'># We have a conf and classes directory, add to BBPATH
|
|
BBPATH := "${BBPATH}${LAYERDIR}"
|
|
|
|
# We have a packages directory, add to BBFILES
|
|
BBFILES := "${BBFILES} ${LAYERDIR}/packages/*/*.bb"
|
|
|
|
BBFILE_COLLECTIONS += "extras"
|
|
BBFILE_PATTERN_extras := "^${LAYERDIR}/"
|
|
BBFILE_PRIORITY_extras = "5"
|
|
|
|
require conf/distro/include/poky-extras-src-revisions.inc
|
|
</literallayout>
|
|
</para>
|
|
|
|
<para>
|
|
As can be seen, the layers recipes are added to BBFILES. The
|
|
BBFILE_COLLECTIONS variable is then appended to with the
|
|
layer name. The BBFILE_PATTERN variable is immediately expanded
|
|
with a regular expression used to match files from BBFILES into
|
|
a particular layer, in this case by using the base pathname.
|
|
The BBFILE_PRIORITY variable then assigns different
|
|
priorities to the files in different layers. This is useful
|
|
in situations where the same package might appear in multiple
|
|
layers and allows you to choose which layer should 'win'.
|
|
Note the use of LAYERDIR with the immediate expansion operator.
|
|
LAYERDIR expands to the directory of the current layer and
|
|
requires use of the immediate expansion operator so that Bitbake
|
|
does not lazily expand the variable when it's parsing a
|
|
different directory.
|
|
</para>
|
|
|
|
<para>
|
|
Extra bbclasses and configuration are added to the BBPATH
|
|
environment variable. In this case, the first file with the
|
|
matching name found in BBPATH is the one that is used, just
|
|
like the PATH variable for binaries. It is therefore recommended
|
|
that you use unique bbclass and configuration file names in your
|
|
custom layer.
|
|
</para>
|
|
|
|
<para>
|
|
The recommended approach for custom layers is to store them in a
|
|
git repository of the format meta-prvt-XXXX and have this repository
|
|
cloned alongside the other meta directories in the Poky tree.
|
|
This way you can keep your Poky tree and it's 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. The policy for committing to such systems
|
|
is important as some simple policy can significantly improve
|
|
usability. The tips below are based on the policy followed for the
|
|
Poky core.
|
|
</para>
|
|
|
|
<para>
|
|
It helps to use a consistent style for commit messages when committing
|
|
changes. We've found a style where the first line of a commit message
|
|
summarises the change and starts with the name of any package affected
|
|
work well. Not all changes are to specific packages so the prefix could
|
|
also be a machine name or class name instead. If a change needs a longer
|
|
description this should follow the summary.
|
|
</para>
|
|
|
|
<para>
|
|
Any commit should be self contained in that it should leave the
|
|
metadata in a consistent state, buildable before and after the
|
|
commit. This helps ensure the autobuilder test results are valid
|
|
but is good practice regardless.
|
|
</para>
|
|
</section>
|
|
|
|
<section id='usingpoky-changes-prbump'>
|
|
<title>Package Revision Incrementing</title>
|
|
|
|
<para>
|
|
If a committed change will result in changing the package output
|
|
then the value of the <glossterm><link linkend='var-PR'>PR</link>
|
|
</glossterm> variable needs to be increased (commonly referred to
|
|
as 'bumped') as part of that commit. Only integer values are used
|
|
and <glossterm><link linkend='var-PR'>PR</link></glossterm> =
|
|
"r0" should be added into new recipes as, while this is the
|
|
default value, not having the variable defined in a recipe makes
|
|
it easy to miss incrementing it when updating the recipe.
|
|
When upgrading the version of a package (<glossterm><link
|
|
linkend='var-PV'>PV</link></glossterm>), the <glossterm><link
|
|
linkend='var-PR'>PR</link></glossterm> variable should be removed.
|
|
</para>
|
|
|
|
<para>
|
|
The aim is that the package version will only ever increase. If
|
|
for some reason <glossterm><link linkend='var-PV'>PV</link></glossterm>
|
|
will change and but not increase, the <glossterm><link
|
|
linkend='var-PE'>PE</link></glossterm> (Package Epoch) can
|
|
be increased (it defaults to '0'). The version numbers aim to
|
|
follow the <ulink url='http://www.debian.org/doc/debian-policy/ch-controlfields.html'>
|
|
Debian Version Field Policy Guidelines</ulink> which define how
|
|
versions are compared and hence what "increasing" means.
|
|
</para>
|
|
|
|
<para>
|
|
There are two reasons for doing this, the first is 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.
|
|
The second is to ensure that target users are able to upgrade their
|
|
devices via their package manager such as with the <command>
|
|
opkg update;opkg upgrade</command> commands (or similar for
|
|
dpkg/apt or rpm based systems). The aim 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 Poky can work in a team environment,
|
|
or scale to a large team of developers. The specifics of any situation
|
|
will determine the best solution and poky offers immense flexibility in
|
|
that aspect but there are some practises that experience has shown to work
|
|
well.
|
|
</para>
|
|
|
|
<para>
|
|
The core component of any development effort with Poky is often an
|
|
automated build testing framework and image generation process. This
|
|
can be used to check that the metadata is buildable, highlight when
|
|
commits break the builds and provide up to date images allowing people
|
|
to test the end result and use them as a base platform for further
|
|
development. Experience shows that buildbot is a good fit for this role
|
|
and that it works well to configure it to make two types of build -
|
|
incremental builds and 'from scratch'/full builds. The incremental builds
|
|
can be tied to a commit hook which triggers them each time a commit is
|
|
made to the metadata and are a useful acid test of whether a given commit
|
|
breaks the build in some serious way. They catch lots of simple errors
|
|
and whilst they won't catch 100% of failures, the tests are fast so
|
|
developers can get feedback on their changes quickly. The full builds
|
|
are builds that build everything from the ground up and test everything.
|
|
They usually happen at preset times such as at night when the machine
|
|
load isn't high from the incremental builds.
|
|
</para>
|
|
|
|
<para>
|
|
Most teams have pieces of software undergoing active development. It is of
|
|
significant benefit to put these under control of a source control system
|
|
compatible with Poky such as git or svn. The autobuilder can then be set to
|
|
pull the latest revisions of these packages so the latest commits get tested
|
|
by the builds allowing any issues to be highlighted quickly. Poky easily
|
|
supports configurations where there is both a stable known good revision
|
|
and a floating revision to test. Poky can also only take changes from specific
|
|
source control branches giving another way it can be used to track/test only
|
|
specified changes.
|
|
</para>
|
|
<para>
|
|
Perhaps the hardest part of setting this up is the policy that surrounds
|
|
the different source control systems, be them software projects or the Poky
|
|
metadata itself. The circumstances will be different in each case but this is
|
|
one of Poky's advantages - the system itself doesn't force any particular policy
|
|
unlike a lot of build systems, allowing the best policy to be chosen for the
|
|
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. This can be done by sharing the <filename class="directory">tmp/deploy/ipk/</filename> directory through a web server and then on the device, changing <filename>/etc/opkg/base-feeds.conf</filename> to point at this server, for example by adding:
|
|
</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>
|
|
Poky is usually used to build software rather than modifying
|
|
it. However, there are ways Poky can be used to modify software.
|
|
</para>
|
|
|
|
<para>
|
|
During building, the sources are available in <glossterm><link
|
|
linkend='var-WORKDIR'>WORKDIR</link></glossterm> directory.
|
|
Where exactly this is depends on the type of package and the
|
|
architecture of target device. For a standard recipe not
|
|
related to <glossterm><link
|
|
linkend='var-MACHINE'>MACHINE</link></glossterm> it will be
|
|
<filename>tmp/work/PACKAGE_ARCH-poky-TARGET_OS/PN-PV-PR/</filename>.
|
|
Target device dependent packages use <glossterm><link
|
|
linkend='var-MACHINE'>MACHINE
|
|
</link></glossterm>
|
|
instead of <glossterm><link linkend='var-PACKAGE_ARCH'>PACKAGE_ARCH
|
|
</link></glossterm>
|
|
in the directory name.
|
|
</para>
|
|
|
|
<tip>
|
|
<para>
|
|
Check 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, a user can modify the package source code
|
|
without problem. The easiest way to test changes is by calling the
|
|
"compile" task:
|
|
</para>
|
|
|
|
<programlisting>
|
|
bitbake --cmd compile --force NAME_OF_PACKAGE
|
|
</programlisting>
|
|
|
|
<para>
|
|
Other tasks may also be called this way.
|
|
</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 <function>do_patch</function> task.
|
|
It is a powerful tool which can be used to track all
|
|
modifications done to package sources.
|
|
</para>
|
|
|
|
<para>
|
|
Before modifying source code it is important to
|
|
notify quilt so it will track changes into new patch
|
|
file:
|
|
<programlisting>
|
|
quilt new NAME-OF-PATCH.patch
|
|
</programlisting>
|
|
|
|
Then add all files which will be modified into that
|
|
patch:
|
|
<programlisting>
|
|
quilt add file1 file2 file3
|
|
</programlisting>
|
|
|
|
Now start editing. At the end quilt needs to be used
|
|
to generate final patch which will contain all
|
|
modifications:
|
|
<programlisting>
|
|
quilt refresh
|
|
</programlisting>
|
|
|
|
The resulting patch file can be found in the
|
|
<filename class="directory">patches/</filename> subdirectory of the source
|
|
(<glossterm><link linkend='var-S'>S</link></glossterm>) directory. For future builds it
|
|
should be copied into
|
|
Poky metadata and added into <glossterm><link
|
|
linkend='var-SRC_URI'>SRC_URI</link></glossterm> of a recipe:
|
|
<programlisting>
|
|
SRC_URI += "file://NAME-OF-PATCH.patch"
|
|
</programlisting>
|
|
|
|
This also requires a bump of <glossterm><link
|
|
linkend='var-PR'>PR</link></glossterm> value in the same recipe as we changed resulting packages.
|
|
</para>
|
|
|
|
</section>
|
|
|
|
</section>
|
|
<section id='usingpoky-configuring-LIC_FILES_CHKSUM'>
|
|
<title>Configuring the LIC_FILES_CHKSUM variable</title>
|
|
<para>
|
|
The changes in the license text inside source code files is tracked
|
|
using the LIC_FILES_CHKSUM metadata variable.
|
|
</para>
|
|
|
|
<section id='usingpoky-specifying-LIC_FILES_CHKSUM'>
|
|
<title>Specifying the LIC_FILES_CHKSUM variable </title>
|
|
|
|
<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>
|
|
</section>
|
|
|
|
<section id='usingpoky-LIC_FILES_CHKSUM-explanation-of-syntax'>
|
|
<title>Explanation of syntax</title>
|
|
|
|
<para>
|
|
This parameter lists all the important files containing the text
|
|
of licenses for the
|
|
source code. It is also possible to specify on which line the license text
|
|
starts and on which line it ends within that file using the "beginline" and
|
|
"endline" parameters. If the "beginline" parameter is not specified then license
|
|
text begins from the 1st line is assumed. Similarly if "endline" parameter is
|
|
not specified then the license text ends at the last line in the file is
|
|
assumed. So if a file contains only licensing information, then there is no need
|
|
to specify "beginline" and "endline" parameters.
|
|
</para>
|
|
<para>
|
|
The "md5" parameter stores the md5 checksum of the license text. So if
|
|
the license text changes in any way from a file, then it's md5 sum will differ and will not
|
|
match with the previously stored md5 checksum. This mismatch will trigger build
|
|
failure, notifying developer about the license text md5 mismatch, and allowing
|
|
the developer to review the license text changes. Also note that if md5 checksum
|
|
is not matched while building, the correct md5 checksum is printed in the build
|
|
log.
|
|
</para>
|
|
<para>
|
|
There is no limit on how many files can be specified on this parameter. But generally every
|
|
project would need specifying of just one or two files for license tracking.
|
|
Many projects would have a "COPYING" file which will store all the
|
|
license information for all the source code files. If the "COPYING" file
|
|
is valid then tracking only that file would be enough.
|
|
</para>
|
|
<tip>
|
|
<para>
|
|
1. If you specify empty or invalid "md5" parameter; then while building
|
|
the package, bitbake will give md5 not matched error, and also show the correct
|
|
"md5" parameter value in the build log
|
|
</para>
|
|
<para>
|
|
2. If the whole file contains only license text, then there is no need to
|
|
specify "beginline" and "endline" parameters.
|
|
</para>
|
|
</tip>
|
|
</section>
|
|
</section>
|
|
<section id='usingpoky-configuring-DISTRO_PN_ALIAS'>
|
|
<title>Configuring the DISTRO_PN_ALIAS variable</title>
|
|
<para>
|
|
Sometimes the names of the same packages are different in different
|
|
linux distributions; and that can becomes an issue for the distro_check
|
|
task to check if the given recipe package exists in other linux distros.
|
|
This issue is avoided by defining per distro recipe name alias:
|
|
DISTRO_PN_ALIAS
|
|
</para>
|
|
|
|
<section id='usingpoky-specifying-DISTRO_PN_ALIAS'>
|
|
<title>Specifying the DISTRO_PN_ALIAS variable </title>
|
|
|
|
<programlisting>
|
|
DISTRO_PN_ALIAS = "distro1=package_name_alias1; distro2=package_name_alias2 \
|
|
distro3=package_name_alias3; \
|
|
..."
|
|
</programlisting>
|
|
<para>
|
|
Look at the meta/packages/xorg-app/xset_1.0.4.bb recipe file for an example.
|
|
</para>
|
|
<tip>
|
|
<para>
|
|
The current code can check if the src package for a recipe exists in the latest
|
|
releases of these distributions automatically.
|
|
</para>
|
|
<programlisting>
|
|
Fedora, OpenSuSE, Debian, Ubuntu, Mandriva
|
|
</programlisting>
|
|
<para>
|
|
For example, this command will generate a report, listing which linux distros include the
|
|
sources for each of the poky recipe.
|
|
</para>
|
|
<programlisting>
|
|
bitbake world -f -c distro_check
|
|
</programlisting>
|
|
<para>
|
|
The results will be stored in the build/tmp/log/distro_check-${DATETIME}.results file.
|
|
</para>
|
|
</tip>
|
|
</section>
|
|
</section>
|
|
</chapter>
|
|
|
|
<!--
|
|
vim: expandtab tw=80 ts=4
|
|
-->
|