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authorMichael 'Mickey' Lauer <mickey@vanille-media.de>2009-02-25 01:47:30 +0100
committerMichael 'Mickey' Lauer <mickey@vanille-media.de>2009-02-25 01:47:30 +0100
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tree206e94d12d2fda511c5b383adfec3684829703a1 /docs/usermanual/chapters/recipes.xml
parent6d76191b2021518d2f1ea00c20a1ec3151d93069 (diff)
docs: import usermanual from org.openembedded.documentation.
org.openembedded.documentation is deprecated now; please do all updates here!
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+<?xml version="1.0" encoding="UTF-8"?>
+<chapter id="chapter_recipes" xreflabel="Recipes chapter">
+ <title>Recipes</title>
+
+ <section id="recipes_introduction" xreflabel="introduction">
+ <title>Introduction</title>
+
+ <para>A bitbake recipe is a set of instructions that describe what needs
+ to be done to retrieve the source code for some application, apply any
+ necessary patches, provide any additional files (such as init scripts),
+ compile it, install it and generated binary packages. The end result is a
+ binary package that you can install on your target device, and maybe some
+ intermediate files, such as libraries and headers, which can be used when
+ building other application.</para>
+
+ <para>In many ways the process is similar to creating .deb or .rpm
+ packages for your standard desktop distributions with one major difference
+ - in OpenEmbedded everything is being cross-compiled. This often makes the
+ task far more difficult (depending on how well suited the application is
+ to cross compiling), then it is for other packaging systems and sometime
+ impossible.</para>
+
+ <para>This chapter assumes that you are familiar with working with
+ bitbake, including the work flow, required directory structures, bitbake
+ configuration and the use of monotone. If you are not familiar with these
+ then first take a look at the chapter on bitbake usage.</para>
+ </section>
+
+ <section id="recipes_syntax" xreflabel="syntax">
+ <title>Syntax of recipes</title>
+
+ <para>The basic items that make up a bitbake recipe file are:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>functions</term>
+
+ <listitem>
+ <para>Functions provide a series of actions to be performed.
+ Functions are usually used to override the default implementation of
+ a task function, or to compliment (append or prepend to an existing
+ function) a default function. Standard functions use sh shell
+ syntax, although access to OpenEmbedded variables and internal
+ methods is also available.</para>
+
+ <para>The following is an example function from the sed
+ recipe:</para>
+
+ <para><screen>do_install () {
+ autotools_do_install
+ install -d ${D}${base_bindir}
+ mv ${D}${bindir}/sed ${D}${base_bindir}/sed.${PN}
+}</screen>It is also possible to implement new functions, that are not
+ replacing or complimenting the default functions, which are called
+ between existing tasks. It is also possible to implement functions
+ in python instead of sh. Both of these options are not seen in the
+ majority of recipes.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>variable assignments and manipulations</term>
+
+ <listitem>
+ <para>Variable assignments allow a value to be assigned to a
+ variable. The assignment may be static text or might include the
+ contents of other variables. In addition to assignment, appending
+ and prepending operations are also supported.</para>
+
+ <para>The follow example shows the some of the ways variables can be
+ used in recipes:<screen>S = "${WORKDIR}/postfix-${PV}"
+PR = "r4"
+CFLAGS += "-DNO_ASM"
+SRC_URI_append = "file://fixup.patch;patch=1"</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>keywords</term>
+
+ <listitem>
+ <para>Only a few keywords are used in bitbake recipes. They are used
+ for things such as including common functions
+ (<emphasis>inherit</emphasis>), loading parts of a recipe from other
+ files (<emphasis>include</emphasis> and
+ <emphasis>require</emphasis>) and exporting variables to the
+ environment (export).</para>
+
+ <para>The following example shows the use of some of these
+ keywords:<screen>export POSTCONF = "${STAGING_BINDIR}/postconf"
+inherit autoconf
+require otherfile.inc</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>comments</term>
+
+ <listitem>
+ <para>Any lines that begin with a # are treated as comment lines and
+ are ignored.<screen># This is a comment</screen></para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>The following is a summary of the most important (and most commonly
+ used) parts of the recipe syntax:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>Line continuation: \</term>
+
+ <listitem>
+ <para>To split a line over multiple lines you should place a \ at
+ the end of the line that is to be continued on the next line.</para>
+
+ <screen>VAR = "A really long \
+ line"</screen>
+
+ <para>Note that there must not be anything (no spaces or tabs) after
+ the \.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Comments: #</term>
+
+ <listitem>
+ <para>Any lines beginning with a # are comments and will be
+ ignored.<screen># This is a comment</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Using variables: ${...}</term>
+
+ <listitem>
+ <para>To access the contents of a variable you need to access it via
+ <emphasis>${&lt;varname&gt;}</emphasis>:<screen>SRC_URI = "${SOURCEFORGE_MIRROR}/libpng/zlib-${PV}.tar.gz"</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Quote all assignments</term>
+
+ <listitem>
+ <para>All variable assignments should be quoted with double quotes.
+ (It may work without them at present, but it will not work in the
+ future).<screen>VAR1 = "${OTHERVAR}"
+VAR2 = "The version is ${PV}"</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Conditional assignment</term>
+
+ <listitem>
+ <para>Conditional assignement is used to assign a value to a
+ variable, but only when the variable is currently unset. This is
+ commonly used to provide a default value for use when no specific
+ definition is provided by the machine or distro configuration of the
+ users local.conf configuration.</para>
+
+ <para>The following example:<screen>VAR1 ?= "New value"</screen>will
+ set <emphasis role="bold">VAR1</emphasis> to <emphasis>"New
+ value"</emphasis> if its currently empty. However if it was already
+ set it would be unchanged. In the following <emphasis
+ role="bold">VAR1</emphasis> is left with the value
+ <emphasis>"Original value"</emphasis>:<screen>VAR1 = "Original value"
+VAR1 ?= "New value"</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Appending: +=</term>
+
+ <listitem>
+ <para>You can append values to existing variables using the
+ <emphasis>+=</emphasis> operator. Note that this operator will add a
+ space between the existing content of the variable and the new
+ content.<screen>SRC_URI += "file://fix-makefile.patch;patch=1"</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Prepending: =+</term>
+
+ <listitem>
+ <para>You can prepend values to existing variables using the
+ <emphasis>=+</emphasis> operator. Note that this operator will add a
+ space between the new content and the existing content of the
+ variable.<screen>VAR =+ "Starts"</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Appending: _append</term>
+
+ <listitem>
+ <para>You can append values to existing variables using the
+ <emphasis>_append</emphasis> method. Note that this operator does
+ not add any additional space, and it is applied after all the
+ <emphasis>+=</emphasis>, and <emphasis>=+</emphasis> operators have
+ been applied.</para>
+
+ <para>The following example show the space being explicitly added to
+ the start to ensure the appended value is not merged with the
+ existing value:<screen>SRC_URI_append = " file://fix-makefile.patch;patch=1"</screen>The
+ <emphasis>_append</emphasis> method can also be used with overrides,
+ which result in the actions only being performed for the specified
+ target or machine: [TODO: Link to section on overrides]<screen>SRC_URI_append_sh4 = " file://fix-makefile.patch;patch=1"</screen>Note
+ that the appended information is a variable itself, and therefore
+ it's possible to used <emphasis>+=</emphasis> or
+ <emphasis>=+</emphasis> to assign variables to the
+ <emphasis>_append</emphasis> information:<screen>SRC_URI_append = " file://fix-makefile.patch;patch=1"
+SRC_URI_append += "file://fix-install.patch;patch=1"</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Prepending: _prepend</term>
+
+ <listitem>
+ <para>You can prepend values to existing variables using the
+ _prepend method. Note that this operator does not add any additional
+ space, and it is applied after all the <emphasis>+=</emphasis>, and
+ <emphasis>=+</emphasis> operators have been applied.</para>
+
+ <para>The following example show the space being explicitly added to
+ the end to ensure the prepended value is not merged with the
+ existing value:<screen>CFLAGS_prepend = "-I${S}/myincludes "</screen>The
+ <emphasis>_prepend</emphasis> method can also be used with
+ overrides, which result in the actions only being performed for the
+ specified target or machine: [TODO: Link to section on
+ overrides]<screen>CFLAGS_prepend_sh4 = " file://fix-makefile.patch;patch=1"</screen>Note
+ that the appended information is a variable itself, and therefore
+ it's possible to used <emphasis>+=</emphasis> or
+ <emphasis>=+</emphasis> to assign variables to the
+ <emphasis>_prepend</emphasis> information:<screen>CFLAGS_prepend = "-I${S}/myincludes "
+CFLAGS_prepend += "-I${S}/myincludes2 "</screen>Note also the lack of a space
+ when using += to append to a prepend value - remember that the +=
+ operator is adding space itself.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Spaces vs tabs</term>
+
+ <listitem>
+ <para>Spaces should be used for indentation, not hard tabs. Both
+ currently work, however it is a policy decision of OE that spaces
+ always be used.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Style: oe-stylize.py</term>
+
+ <listitem>
+ <para>To help with using the correct style in your recipes there is
+ a python script in the contrib directory called
+ <emphasis>oe-stylize.py</emphasis> which can be used to reformat
+ your recipes to the correct style. The output will contain a list of
+ warning (to let you know what you did wrong) which should be edited
+ out before using the new file.<screen>contrib/oe-stylize.py myrecipe.bb &gt; fixed-recipe.bb
+vi fixed-recipe.bb
+mv fixed.recipe.bb myrecipe.bb</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Using python for complex operations: ${@...}</term>
+
+ <listitem>
+ <para>For more advanced processing it is possible to use python code
+ during variable assignments, for doing search and replace on a
+ variable for example.</para>
+
+ <para>Python code is indicated by a proceeding @ sign in the
+ variable assignment.<screen>CXXFLAGS := "${@'${CXXFLAGS}'.replace('-frename-registers', '')}"</screen>More
+ information about using python is available in the <xref
+ linkend="recipes_advanced_python" /> section.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Shell syntax</term>
+
+ <listitem>
+ <para>When describing a list of actions to take shell syntax is used
+ (as if you were writing a shell script). You should ensure that you
+ script would work with a generic sh and not require any bash (or
+ other shell) specific functionality. The same applies to various
+ system utilities (sed, grep, awk etc) that you may wish to use. If
+ in doubt you should check with multiple implementations - including
+ those from busybox.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>For a detailed description of the syntax for the bitbake recipe
+ files you should refer to the bitbake use manual.</para>
+ </section>
+
+ <section id="recipes_versioning" xreflabel="versioning">
+ <title>Recipe naming: Names, versions and releases</title>
+
+ <para>Recipes in OpenEmbedded use a standard naming convention that
+ includes the package name and version number in the filename. In addition
+ to the name and version there is also a release number, which is indicates
+ changes to the way the package is built and/or packaged. The release
+ number is contained within the recipe itself.</para>
+
+ <para>The expected format of recipe name is:<screen>&lt;package-name&gt;_&lt;version&gt;.bb</screen></para>
+
+ <para>where <emphasis>&lt;package-name&gt;</emphasis> is the name of the
+ package (application, library, module, or whatever it is that is being
+ packaged) and <emphasis>version</emphasis> is the version number.</para>
+
+ <para>So a typical recipe name would be:<screen>strace_4.5.14.bb</screen>which
+ would be for version <emphasis>4.5.14</emphasis> of the
+ <emphasis>strace</emphasis> application.</para>
+
+ <para>The release version is defined via the package release variable, PR,
+ contained in the recipe. The expected format is:<screen>r&lt;n&gt;</screen>where
+ <emphasis>&lt;n&gt;</emphasis> is an integer number starting from 0
+ initially and then incremented each time the recipe, or something that
+ effects the recipe, is modified. So a typical definition of the release
+ would be:<screen>PR = "r1"</screen>to specify release number
+ <emphasis>1</emphasis> (the second release, the first would have been
+ <emphasis>0</emphasis>). If there is no definition of PR in the recipe
+ then the default value of "r0" is used.</para>
+
+ <para><note>
+ <para>It is good practice to always define PR in your recipes, even
+ for the <emphasis>"r0"</emphasis> release, so that when editing the
+ recipe it is clear that the PR number needs to be updated.</para>
+
+ <para>You should always increment PR when modifying a recipe.
+ Sometimes this can be avoided if the change will have no effect on the
+ actual packages generated by the recipe, such as updating the SRC_URI
+ to point to a new host. If in any doubt then you should increase the
+ PR regardless of what has been changed.</para>
+
+ <para>The PR value should never be decremented. If you accidentally
+ submit a large PR value for example then it should be left at the
+ value and just increased for new releases, not reset back to a lower
+ version.</para>
+ </note></para>
+
+ <para>When a recipe is being processed some variables are automatically
+ set based on the recipe file name and can be used for other purposes from
+ within the recipe itself. These include:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>PN</term>
+
+ <listitem>
+ <para>The package name. Determined from the recipe filename -
+ everything up until the first underscore is considered to be the
+ package name. For the <command>strace_4.5.14.bb</command> recipe the
+ PN variable would be set to <emphasis>"strace"</emphasis>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>PV</term>
+
+ <listitem>
+ <para>The package version. Determined from the recipe filename -
+ everything between the first underscore and the final .bb is
+ considered to be the package version. For the
+ <command>strace_4.5.14.bb</command> recipe the PV variable would be
+ set to <emphasis>"4.5.14"</emphasis>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>PR</term>
+
+ <listitem>
+ <para>The package release. This is explicitly set in the recipe, or
+ if not set it defaults to "<emphasis>r0"</emphasis> if not
+ set.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>P</term>
+
+ <listitem>
+ <para>The package name and versions separated by a hyphen.<screen>P = "${PN}-${PV}"</screen></para>
+
+ <para>For the <command>strace_4.5.14.bb</command> recipe the P
+ variable would be set to
+ <emphasis>"strace-4.5.14"</emphasis>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>PF</term>
+
+ <listitem>
+ <para>The package name, version and release separated by
+ hyphens.<screen>PF = "${PN}-${PV}-${PR}"</screen></para>
+
+ <para>For the s<command>trace_4.5.14.bb recipe</command>, with PR
+ set to <emphasis>"r1"</emphasis> in the recipe, the PF variable
+ would be set to <emphasis>"strace-4.5.14-r1"</emphasis>.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>While some of these variables are not commonly used in recipes (they
+ are used internally though) both PN and PV are used a lot.</para>
+
+ <para>In the following example we are instructing the packaging system to
+ include an additional directory in the package. We use PN to refer to the
+ name of the package rather than spelling out the package name:<screen>FILES_${PN} += "${sysconfdir}/myconf"</screen></para>
+
+ <para>In the next example we are specifying the URL for the package
+ source, by using PV in place of the actual version number it is possible
+ to duplicate, or rename, the recipe for a new version without having to
+ edit the URL:<screen>SRC_URI = "ftp://ftp.vim.org/pub/vim/unix/vim-${PV}.tar.bz2"</screen></para>
+ </section>
+
+ <section id="recipes_variables" xreflabel="variables">
+ <title>Variables</title>
+
+ <para>One of the most confusing part of bitbake recipes for new users is
+ the large amount of variables that appear to be available to change and/or
+ control the behaviour of some aspect of the recipe. Some variables, such
+ as those derived from the file name are reasonably obvious, others are not
+ at all obvious.</para>
+
+ <para>There are several places where these variables are derived from
+ and/or used:</para>
+
+ <orderedlist>
+ <listitem>
+ <para>A large number of variables are defined in the bitbake
+ configuration file conf/bitbake.conf - it's often a good idea to look
+ through that file when trying to determine what a particular variable
+ means.</para>
+ </listitem>
+
+ <listitem>
+ <para>Machine and distribution configuration files in conf/machine and
+ conf/distro will sometimes define some variables specific to the
+ machine and/or distribution. You should look at the appropriate files
+ for your targets to see if anything is being defined that effects the
+ recipes you are building.</para>
+ </listitem>
+
+ <listitem>
+ <para>Bitbake itself will define some variables. The FILE variables
+ that defines the name of the bitbake recipe being processed is set by
+ bitbake itself for example. Refer to the bitbake manual for more
+ information on the variables that bitbake sets.</para>
+ </listitem>
+
+ <listitem>
+ <para>The classes, that are used via the inherit keyword, define
+ and/or use the majority of the remaining variables. A class is a like
+ a library that contain parts of a bitbake recipe that are used by
+ multiple recipes. To make them usable in more situations they often
+ include a large number of variables to control how the class
+ operates.</para>
+ </listitem>
+ </orderedlist>
+
+ <para>Another important aspect is that there are three different types of
+ things that binaries and libraries are used for and they often have
+ different variables for each. These include:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>target</term>
+
+ <listitem>
+ <para>Refers to things built for the target are expected to be run
+ on the target device itself.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>native</term>
+
+ <listitem>
+ <para>Refers to things built to run natively on the build host
+ itself.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>cross</term>
+
+ <listitem>
+ <para>Refers to things built to run natively on the build host
+ itself, but produce output which is suitable for the target device.
+ Cross versions of packages usually only exist for things like
+ compilers and assemblers - i.e. things which are used to produce
+ binary applications themselves.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </section>
+
+ <section id="recipes_header" xreflabel="header">
+ <title>Header</title>
+
+ <para>Practically all recipes start was the header section which describes
+ various aspects of the package that is being built. This information is
+ typically used directly by the package format (such as ipkg or deb) as
+ it's meta data used to describe the package.</para>
+
+ <para>Variables used in the header include:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>DESCRIPTION</term>
+
+ <listitem>
+ <para>Describes what the software does. Hopefully this gives enough
+ information to a use to know if it's the right application for
+ them.</para>
+
+ <para>The default description is: <emphasis>"Version ${PV}-${PR} of
+ package ${PN}"</emphasis>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>HOMEPAGE</term>
+
+ <listitem>
+ <para>The URL of the home page of the application where new releases
+ and more information can be found.</para>
+
+ <para>The default homepage is <emphasis>"unknown"</emphasis>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>SECTION</term>
+
+ <listitem>
+ <para>The section is used to categorise the application into a
+ specific group. Often used by GUI based installers to help users
+ when searching for software.</para>
+
+ <para>See <xref linkend="section_variable" /> for a list of the
+ available sections.</para>
+
+ <para>The default section is <emphasis>"base"</emphasis>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>PRIORITY</term>
+
+ <listitem>
+ <para>The default priority is
+ <emphasis>"optional"</emphasis>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>LICENSE</term>
+
+ <listitem>
+ <para>The license for the application. If it is not one of the
+ standard licenses then the license itself must be included
+ (where?).</para>
+
+ <para>As well as being used in the package meta-data the license is
+ also used by the src_distribute class.</para>
+
+ <para>The default license is <emphasis>"unknown"</emphasis>.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </section>
+
+ <section id="recipes_sources" xreflabel="sources">
+ <title>Sources: Downloading, patching and additional files</title>
+
+ <para>A recipes purpose is to describe how to take a software package and
+ build it for your target device. The location of the source file (or
+ files) is specified via the <xref linkend="src_uri_variable" /> in the
+ recipe. This can describe several types of URI's, the most common
+ are:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>http and https</term>
+
+ <listitem>
+ <para>Specifies files to be downloaded. A copy is stored locally so
+ that future builds will not download the source again.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>cvs, svn and git</term>
+
+ <listitem>
+ <para>Specifies that the files are to be retrieved using the
+ specified version control system.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>files</term>
+
+ <listitem>
+ <para>Plain files which are included locally. These can be used for
+ adding documentation, init scripts or any other files that need to
+ be added to build the package under openembedded.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>patches</term>
+
+ <listitem>
+ <para>Patches are plain files which are treated as patched and
+ automatically applied.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>If a http, https or file URI refers to a compressed file, an archive
+ file or a compressed archive file, such as .tar.gz or .zip, then the files
+ will be uncompressed and extracted from the archive automatically.</para>
+
+ <para>Archive files will be extracted from with the working directory,
+ <emphasis role="bold">${WORKDIR}</emphasis> and plain files will be copied
+ into the same directory. Patches will be applied from within the unpacked
+ source directory, <emphasis role="bold">${S}</emphasis>. (Details on these
+ directories is provided in the next section.)</para>
+
+ <para>The following example from the havp recipe shows a typical <emphasis
+ role="bold">SRC_URI</emphasis> definition:<screen>SRC_URI = "http://www.server-side.de/download/havp-${PV}.tar.gz \
+ file://sysconfdir-is-etc.patch;patch=1 \
+ file://havp.init \
+ file://doc.configure.txt \
+ file://volatiles.05_havp"</screen></para>
+
+ <para>This describes several files</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>http://www.server-side.de/download/havp-${PV}.tar.gz</term>
+
+ <listitem>
+ <para>This is the URI of the havp source code. Note the use of the
+ <emphasis role="bold">${PV}</emphasis> variable to specify the
+ version. This is done to enable the recipe to be renamed for a new
+ version without the need the edit the recipe itself. Because this is
+ a .tar.gz compressed archive the file will be decompressed and
+ extracted in the working dir <emphasis
+ role="bold">${WORKDIR}</emphasis>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>file://sysconfdir-is-etc.patch;patch=1</term>
+
+ <listitem>
+ <para>This is a local file that is used to patch the extracted
+ source code. The patch=1 is what specifies that this is a patch. The
+ patch will be applied from the unpacked source directory, <emphasis
+ role="bold">${S}</emphasis>. In this case <emphasis
+ role="bold">${S}</emphasis> will be <emphasis
+ role="bold">${WORKDIR}/havp-0.82</emphasis>, and luckily the
+ <emphasis role="bold">havp-0.82.tar.gz</emphasis> file extracts
+ itself into that directory (so no need to explicitly change
+ <emphasis role="bold">${S}</emphasis>).</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>file://havp.init file://doc.configure.txt
+ file://volatiles.05_havp"</term>
+
+ <listitem>
+ <para>These are plain files which are just copied into the working
+ directory <emphasis role="bold">${WORKDIR}</emphasis>. These are
+ then used during the install task in the recipe to provide init
+ scripts, documentation and volatiles configuration information for
+ the package.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>Full details on the <emphasis role="bold">SRC_URI</emphasis>
+ variable and all the support URI's is available in the <xref
+ linkend="src_uri_variable" /> section of the reference chapter.</para>
+ </section>
+
+ <section id="recipes_directories" xreflabel="directories">
+ <title>Directories: What goes where</title>
+
+ <para>A large part of the work or a recipe is involved with specifying
+ where files and found and where they have to go. It's important for
+ example that programs do not try and use files from <emphasis
+ role="bold">/usr/include</emphasis> or <emphasis
+ role="bold">/usr/lib</emphasis> since they are for the host system, not
+ the target. Similarly you don't want programs installed into <emphasis
+ role="bold">/usr/bin</emphasis> since that may overwrite your host system
+ programs with versions that don't work on the host!</para>
+
+ <para>The following are some of the directories commonly referred to in
+ recipes and will be described in more detail in the rest of this
+ section:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>Working directory: WORKDIR</term>
+
+ <listitem>
+ <para>This working directory for a recipe is where archive files
+ will be extracted, plain files will be placed, subdirectories for
+ logs, installed files etc will be created.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Unpacked source code directory: S</term>
+
+ <listitem>
+ <para>This is where patches are applied and where the program is
+ expected to be compiled in.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Destination directory: D</term>
+
+ <listitem>
+ <para>The destination directory. This is where your package should
+ be installed into. The packaging system will then take the files
+ from directories under here and package them up for installation on
+ the target.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Installation directories: bindir, docdir, ...</term>
+
+ <listitem>
+ <para>There are a set of variables available to describe all of the
+ paths on the target that you may want to use. Recipes should use
+ these variables rather than hard coding any specific paths.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Staging directories: STAGING_LIBDIR, STAGING_INCDIR, ...</term>
+
+ <listitem>
+ <para>Staging directories are a special area for headers, libraries
+ and other files that are generated by one recipe that may be needed
+ by another recipe. A library package for example needs to make the
+ library and headers available to other recipes so that they can link
+ against them.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>File path directories: FILE, FILE_DIRNAME, FILESDIR,
+ FILESPATH</term>
+
+ <listitem>
+ <para>These directories are used to control where files are found.
+ Understanding these can help you separate patches for different
+ versions or releases of your recipes and/or use the same patch over
+ multiple versions etc.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <section>
+ <title>WORKDIR: The working directory</title>
+
+ <para>The working directory is where the source code is extracted, to
+ which plain files (not patches) are copied and where the logs and
+ installation files are created. A typical reason for needing to
+ reference the work directory is for the handling of non patch
+ files.</para>
+
+ <para>If we take a look at the recipe for quagga we can see an example
+ non patch files for configuration and init scripts:<screen>SRC_URI = "http://www.quagga.net/download/quagga-${PV}.tar.gz \
+ file://fix-for-lib-inpath.patch;patch=1 \
+ file://quagga.init \
+ file://quagga.default \
+ file://watchquagga.init \
+ file://watchquagga.default"</screen>The recipe has two init files
+ and two configuration files, which are not patches, but are actually
+ files that it wants to include in the generated packages. Bitbake will
+ copy these files into the work directory. So to access them during the
+ install task we refer to them via the <emphasis
+ role="bold">WORKDIR</emphasis> variable:<screen>do_install () {
+ # Install init script and default settings
+ install -m 0755 -d ${D}${sysconfdir}/default ${D}${sysconfdir}/init.d ${D}${sysconfdir}/quagga
+ install -m 0644 ${WORKDIR}/quagga.default ${D}${sysconfdir}/default/quagga
+ install -m 0644 ${WORKDIR}/watchquagga.default ${D}${sysconfdir}/default/watchquagga
+ install -m 0755 ${WORKDIR}/quagga.init ${D}${sysconfdir}/init.d/quagga
+ install -m 0755 ${WORKDIR}/watchquagga.init ${D}${sysconfdir}/init.d/watchquagga
+ ...</screen></para>
+ </section>
+
+ <section>
+ <title>S: The unpacked source code directory</title>
+
+ <para>Bitbake expects to find the extracted source for a package in a
+ directory called <emphasis
+ role="bold">&lt;packagename&gt;-&lt;version&gt;</emphasis> in the
+ <emphasis role="bold">WORKDIR</emphasis> directory. This is the
+ directory in which it will change into before patching, compiling and
+ installating the package.</para>
+
+ <para>For example, we have a package called <emphasis
+ role="bold">widgets_1.2.bb</emphasis> which we are extracting from the
+ <emphasis role="bold">widgets-1.2.tar.gz</emphasis> file. Bitbake
+ expects the source to end up in a directory called <emphasis
+ role="bold">widgets-1.2</emphasis> within the work directory. If the
+ source does not end up in this directory then bitbake needs to be told
+ this by explicitly setting <emphasis role="bold">S</emphasis>.</para>
+
+ <para>If <emphasis role="bold">widgets-1.2.tar.gz</emphasis> actually
+ extracts into a directory called <emphasis
+ role="bold">widgets</emphasis>, without the version number, instead of
+ <emphasis role="bold">widgets-1.2</emphasis> then the <emphasis
+ role="bold">S</emphasis> variable will be wrong and patching and/or
+ compiling will fail. Therefore we need to override the default value of
+ <emphasis role="bold">S</emphasis> to specify the directory the source
+ was actually extracted into:<screen>SRC_URI = "http://www.example.com/software/widgets-${PN}.tar.gz"
+S = "${WORKDIR}/widgets"</screen></para>
+ </section>
+
+ <section>
+ <title>D: The destination directory</title>
+
+ <para>The destination directory is where the completed application and
+ all of it's files are installed into in preparation for packaging.
+ Typically an installation would places files in directories such as
+ <emphasis role="bold">/etc</emphasis> and <emphasis
+ role="bold">/usr/bin</emphasis> by default. Since those directories are
+ used by the host system we do not want the packages to install into
+ those locations. Instead they need to install into the directories below
+ the destination directory.</para>
+
+ <para>So instead of installing into <emphasis
+ role="bold">/usr/bin</emphasis> the package needs to install into
+ <emphasis role="bold">${D}/usr/bin</emphasis>.</para>
+
+ <para>The following example from arpwatch shows the make install command
+ being passed a <emphasis role="bold">${D}</emphasis> as the <emphasis
+ role="bold">DESTDIR</emphasis> variable to control where the makefile
+ installs everything:<screen>do_install() {
+ ...
+ oe_runmake install DESTDIR=${D}</screen></para>
+
+ <para>The following example from quagga shows the use of the destination
+ directory to install the configuration files and init scripts for the
+ package:<screen>do_install () {
+ # Install init script and default settings
+ install -m 0755 -d ${D}${sysconfdir}/default ${D}${sysconfdir}/init.d ${D}${sysconfdir}/quagga
+ install -m 0644 ${WORKDIR}/quagga.default ${D}${sysconfdir}/default/quagga
+ install -m 0755 ${WORKDIR}/quagga.init ${D}${sysconfdir}/init.d/quagga</screen><note>
+ <para>You should not use directories such as <emphasis
+ role="bold">/etc</emphasis> and <emphasis
+ role="bold">/usr/bin</emphasis> directly in your recipes. You should
+ use the variables that define these locations. The full list of
+ these variables can be found in the <xref
+ linkend="directories_installation" /> section of the reference
+ chapter.</para>
+ </note></para>
+ </section>
+
+ <section>
+ <title>Staging directories</title>
+
+ <para>Staging is used to make libraries, headers and binaries available
+ for the build of one recipe for use by another recipe. Building a
+ library for example requires that packages be created containing the
+ libraries and headers for development on the target as well as making
+ them available on the host for building other packages that need the
+ libraries and headers.</para>
+
+ <para>Making the libraries, headers and binaries available for use by
+ other recipes on the host is called staging and is performed by the
+ <emphasis>stage</emphasis> task in the recipe. Any recipes that contain
+ items that are required to build other packages should have a
+ <emphasis>stage</emphasis> task to make sure the items are all correctly
+ placed into the staging area. The following example from clamav show the
+ clamav library and header being placed into the staging area:<screen>do_stage () {
+ oe_libinstall -a -so libclamav ${STAGING_LIBDIR}
+ install -m 0644 libclamav/clamav.h ${STAGING_INCDIR}
+}</screen></para>
+
+ <para>The following from the p3scan recipe show the path to the clamav
+ library and header being passed to the configure script. Without this
+ the configure script would either fail to find the library, or worse
+ still search the host systems directories for the library. Passing in
+ the location results in it searching the correct location and finding
+ the clamav library and headers:<screen>EXTRA_OECONF = "--with-clamav=${STAGING_LIBDIR}/.. \
+ --with-openssl=${STAGING_LIBDIR}/.. \
+ --disable-ripmime"</screen>While the staging directories are
+ automatically added by OpenEmbedded to the compiler and linking commands
+ it is sometimes necessary, as in the p3scan example above, to explicitly
+ specify the location of the staging directories. Typically this is
+ needed for autoconf scripts that search in multiple places for the
+ libraries and headers.</para>
+
+ <note>
+ <para>Many of the helper classes, such as pkgconfig and autotools add
+ appropriate commands to the stage task for you. Check with the
+ individual class descriptions in the reference section to determine
+ what each class is staging automatically for you.</para>
+ </note>
+
+ <para>A full list of staging directories can be found in the <xref
+ linkend="directories_staging" /> section in the reference
+ chapter.</para>
+ </section>
+
+ <section id="recipes_filespath_dir" xreflabel="FILESPATH/FILESDIR">
+ <title>FILESPATH/FILESDIR: Finding local files</title>
+
+ <para>The file related variables are used by bitbake to determine where
+ to look for patches and local files.</para>
+
+ <para>Typically you will not need to modify these, but it is useful to
+ be aware of the default values. In particular when searching for patches
+ and/or files (file:// URI's), the default search path is:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>${FILE_DIRNAME}/${PF}</term>
+
+ <listitem>
+ <para>This is the package name, version and release, such as
+ "<emphasis role="bold">strace-4.5.14-r1</emphasis>". This is very
+ rarely used since the patches would only be found for the one
+ exact release of the recipe.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>${FILE_DIRNAME}/${P}</term>
+
+ <listitem>
+ <para>This is the package name and version, such as "<emphasis
+ role="bold">strace-4.5.14</emphasis>". This is by far the most
+ common place to place version specified patches.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>${FILE_DIRNAME}/${PN}</term>
+
+ <listitem>
+ <para>This is the package name only, such as "<emphasis
+ role="bold">strace</emphasis>". This is not commonly used.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>${FILE_DIRNAME}/files</term>
+
+ <listitem>
+ <para>This is just the directory called "<emphasis
+ role="bold">files</emphasis>". This is commonly used for patches
+ and files that apply to all version of the package.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>${FILE_DIRNAME}/</term>
+
+ <listitem>
+ <para>This is just the base directory of the recipe. This is very
+ rarely used since it would just clutter the main directory.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>Each of the paths is relative to <emphasis
+ role="bold">${FILE_DIRNAME}</emphasis> which is the directory in which
+ the recipe that is being processed is located.</para>
+
+ <para>The full set of variables that control the file locations and
+ patch are:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>FILE</term>
+
+ <listitem>
+ <para>The path to the .bb file which is currently being
+ processed.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>FILE_DIRNAME</term>
+
+ <listitem>
+ <para>The path to the directory which contains the FILE which is
+ currently being processed.<screen>FILE_DIRNAME = "${@os.path.dirname(bb.data.getVar('FILE', d))}"</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>FILESPATH</term>
+
+ <listitem>
+ <para>The default set of directories which are available to use
+ for the file:// URI's. Each directory is searched, in the
+ specified order, in an attempt to find the file specified by each
+ file:// URI: <screen>FILESPATH = "${FILE_DIRNAME}/${PF}:${FILE_DIRNAME}/${P}:\
+${FILE_DIRNAME}/${PN}:${FILE_DIRNAME}/files:${FILE_DIRNAME}"</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>FILESDIR</term>
+
+ <listitem>
+ <para>The default directory to search for file:// URI's. Only used
+ if the file is not found in FILESPATH. This can be used to easily
+ add one additional directory to the search path without having to
+ modify the default FILESPATH setting. By default this is just the
+ first directory from FILESPATH. <screen>FILESDIR = "${@bb.which(bb.data.getVar('FILESPATH', d, 1), '.')}" </screen></para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>Sometimes recipes will modify the <emphasis
+ role="bold">FILESPATH</emphasis> or <emphasis
+ role="bold">FILESDIR</emphasis> variables to change the default search
+ path for patches and files. The most common situation in which this is
+ done is when one recipe includes another one in which the default values
+ will be based on the name of the package doing the including, not the
+ included package. Typically the included package will expect the files
+ to be located in a directories based on it's own name.</para>
+
+ <para>As an example the m4-native recipe includes the m4 recipe. This is
+ fine, except that the m4 recipes expects its files and patches to be
+ located in a directory called <emphasis role="bold">m4</emphasis>
+ directory while the native file name results in them being searched for
+ in <emphasis role="bold">m4-native</emphasis>. So the m4-native recipe
+ sets the <emphasis role="bold">FILESDIR</emphasis> variable to the value
+ that of m4 to add the actual m4 directory (where m4 itself has its files
+ stored) to the list of directories search for:<screen> include m4_${PV}.bb
+ inherit native
+ FILESDIR = "${@os.path.dirname(bb.data.getVar('FILE',d,1))}/m4"</screen></para>
+ </section>
+ </section>
+
+ <section id="recipes_examples" xreflabel="examples">
+ <title>Basic examples</title>
+
+ <para>By now you should know enough about the bitbake recipes to be able
+ to create a basic recipe. We'll cover a simple single file recipe and then
+ a more advanced example that uses the autotools helper class (to be
+ described later) to build an autoconf based package.</para>
+
+ <section id="recipes_helloworld_example" xreflabel="hello world example">
+ <title>Hello world</title>
+
+ <para>Now it's time for our first recipe. This is going to be one of the
+ simplest possible recipes: all code is included and there's only one
+ file to compile and one readme file. While this isn't all that common
+ it's a useful example because it doesn't depend on any of the helper
+ classes which can sometime hide a lot of what is going on.</para>
+
+ <para>First we'll create the myhelloworld.c file and a readme file.
+ We'll place this in the files subdirectory, which is one of the places
+ that is searched for file:// URI's:<screen>mkdir packages/myhelloworld
+mkdir packages/myhelloworld/files
+cat &gt; packages/myhelloworld/files/myhelloworld.c
+#include &lt;stdio.h&gt;
+
+int main(int argc, char** argv)
+{
+ printf("Hello world!\n");
+ return 0;
+}
+^D
+cat &gt; packages/myhelloworld/files/README.txt
+Readme file for myhelloworld.
+^D</screen></para>
+
+ <para>Now we have a directory for our recipe, packages/myhelloworld, and
+ we've created a files subdirectory in there to store our local files.
+ We've created two local files, the C source code for our helloworld
+ program and a readme file. Now we need to create the bitbake
+ recipe.</para>
+
+ <para>First we need the header section, which will contain a description
+ of the package and the release number. We'll leave the other header
+ variables out for now:<screen>DESCRIPTION = "My hello world program"
+PR = "r0"</screen></para>
+
+ <para>Next we need to tell it which files we want to be included in the
+ recipe, which we do via file:// URI's and the SRC_URI variable:<screen>SRC_URI = "file://myhelloworld.c \
+ file://README.txt"</screen></para>
+
+ <para>Note the use of the \ to continue a file and the file of file://
+ local URI's, rather than other types such as http://.</para>
+
+ <para>Now we need provide a compile task which tells bitbake how to
+ compile this program. We do this by defining a do_compile function in
+ the recipe and providing the appropriate commands:</para>
+
+ <para><screen>do_compile() {
+ ${CC} ${CFLAGS} ${LDFLAGS} ${WORKDIR}/myhelloworld.c -o myhelloworld
+}</screen></para>
+
+ <para>Note the:</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>use of the pre-defined compiler variables, <emphasis
+ role="bold">${CC}</emphasis>, <emphasis
+ role="bold">${CFLAGS}</emphasis> and <emphasis
+ role="bold">${LDFLAGS}</emphasis>. These are setup automatically to
+ contain the settings required to cross-compile the program for the
+ target.</para>
+ </listitem>
+
+ <listitem>
+ <para>use of <emphasis role="bold">${WORKDIR}</emphasis> to find the
+ source file. As mentioned previously all files are copied into the
+ working directory and can be referenced via the <emphasis
+ role="bold">${WORKDIR}</emphasis> variable.</para>
+ </listitem>
+ </itemizedlist>
+
+ <para>And finally we want to install the program and readme file into
+ the destination directory so that it'll be packaged up correctly. This
+ is done via the install task, so we need to define a do_install function
+ in the recipe to describe how to install the package:<screen>do_install() {
+ install -m 0755 -d ${D}${bindir} ${D}${docdir}/myhelloworld
+ install -m 0644 ${S}/myhelloworld ${D}${bindir}
+ install -m 0644 ${WORKDIR}/README.txt ${D}${docdir}/myhelloworld
+}</screen></para>
+
+ <para>Note the:</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>use the <emphasis role="bold">install</emphasis> command to
+ create directories and install the files, not cp.</para>
+ </listitem>
+
+ <listitem>
+ <para>way directories are created before we attempt to install any
+ files into them. The install command takes care of any
+ subdirectories that are missing, so we only need to create the full
+ path to the directory - no need to create the subdirectories.</para>
+ </listitem>
+
+ <listitem>
+ <para>way we install everything into the destination directory via
+ the use of the <emphasis role="bold">${D}
+ </emphasis>variable.</para>
+ </listitem>
+
+ <listitem>
+ <para>way we use variables to refer to the target directories, such
+ as <emphasis role="bold">${bindir}</emphasis> and <emphasis
+ role="bold">${docdir}</emphasis>.</para>
+ </listitem>
+
+ <listitem>
+ <para>use of <emphasis role="bold">${WORKDIR}</emphasis> to get
+ access to the <emphasis role="bold">README.txt</emphasis> file,
+ which was provided via file:// URI.</para>
+ </listitem>
+ </itemizedlist>
+
+ <para>We'll consider this release 0 and version 0.1 of a program called
+ helloworld. So we'll name the recipe myhelloworld_0.1.bb:<screen>cat &gt; packages/myhelloworld/myhelloworld_0.1.bb
+DESCRIPTION = "Hello world program"
+PR = "r0"
+
+SRC_URI = "file://myhelloworld.c \
+ file://README.txt"
+
+do_compile() {
+ ${CC} ${CFLAGS} ${LDFLAGS} ${WORKDIR}/myhelloworld.c -o myhelloworld
+}
+
+do_install() {
+ install -m 0755 -d ${D}${bindir} ${D}${docdir}/myhelloworld
+ install -m 0644 ${S}/myhelloworld ${D}${bindir}
+ install -m 0644 ${WORKDIR}/README.txt ${D}${docdir}/myhelloworld
+}
+^D</screen>Now we are ready to build our package, hopefully it'll all work
+ since it's such a simple example:<screen>~/oe%&gt; bitbake -b packages/myhelloworld/myhelloworld_0.1.bb
+NOTE: package myhelloworld-0.1: started
+NOTE: package myhelloworld-0.1-r0: task do_fetch: started
+NOTE: package myhelloworld-0.1-r0: task do_fetch: completed
+NOTE: package myhelloworld-0.1-r0: task do_unpack: started
+NOTE: Unpacking /home/lenehan/devel/oe/local-packages/myhelloworld/files/helloworld.c to /home/lenehan/devel/oe/build/titan-glibc-25/tmp/work/myhelloworld-0.1-r0/
+NOTE: Unpacking /home/lenehan/devel/oe/local-packages/myhelloworld/files/README.txt to /home/lenehan/devel/oe/build/titan-glibc-25/tmp/work/myhelloworld-0.1-r0/
+NOTE: package myhelloworld-0.1-r0: task do_unpack: completed
+NOTE: package myhelloworld-0.1-r0: task do_patch: started
+NOTE: package myhelloworld-0.1-r0: task do_patch: completed
+NOTE: package myhelloworld-0.1-r0: task do_configure: started
+NOTE: package myhelloworld-0.1-r0: task do_configure: completed
+NOTE: package myhelloworld-0.1-r0: task do_compile: started
+NOTE: package myhelloworld-0.1-r0: task do_compile: completed
+NOTE: package myhelloworld-0.1-r0: task do_install: started
+NOTE: package myhelloworld-0.1-r0: task do_install: completed
+NOTE: package myhelloworld-0.1-r0: task do_package: started
+NOTE: package myhelloworld-0.1-r0: task do_package: completed
+NOTE: package myhelloworld-0.1-r0: task do_package_write: started
+NOTE: Not creating empty archive for myhelloworld-dbg-0.1-r0
+Packaged contents of myhelloworld into /home/lenehan/devel/oe/build/titan-glibc-25/tmp/deploy/ipk/sh4/myhelloworld_0.1-r0_sh4.ipk
+Packaged contents of myhelloworld-doc into /home/lenehan/devel/oe/build/titan-glibc-25/tmp/deploy/ipk/sh4/myhelloworld-doc_0.1-r0_sh4.ipk
+NOTE: Not creating empty archive for myhelloworld-dev-0.1-r0
+NOTE: Not creating empty archive for myhelloworld-locale-0.1-r0
+NOTE: package myhelloworld-0.1-r0: task do_package_write: completed
+NOTE: package myhelloworld-0.1-r0: task do_populate_staging: started
+NOTE: package myhelloworld-0.1-r0: task do_populate_staging: completed
+NOTE: package myhelloworld-0.1-r0: task do_build: started
+NOTE: package myhelloworld-0.1-r0: task do_build: completed
+NOTE: package myhelloworld-0.1: completed
+Build statistics:
+ Attempted builds: 1
+~/oe%&gt;</screen></para>
+
+ <para>The package was successfully built, the output consists of two
+ .ipkg files, which are ready to be installed on the target. One contains
+ the binary and the other contains the readme file:<screen>~/oe%&gt; ls -l tmp/deploy/ipk/*/myhelloworld*
+-rw-r--r-- 1 lenehan lenehan 3040 Jan 12 14:46 tmp/deploy/ipk/sh4/myhelloworld_0.1-r0_sh4.ipk
+-rw-r--r-- 1 lenehan lenehan 768 Jan 12 14:46 tmp/deploy/ipk/sh4/myhelloworld-doc_0.1-r0_sh4.ipk
+~/oe%&gt;</screen></para>
+
+ <para>It's worthwhile looking at the working directory to see where
+ various files ended up:<screen>~/oe%&gt; find tmp/work/myhelloworld-0.1-r0
+tmp/work/myhelloworld-0.1-r0
+tmp/work/myhelloworld-0.1-r0/myhelloworld-0.1
+tmp/work/myhelloworld-0.1-r0/myhelloworld-0.1/patches
+tmp/work/myhelloworld-0.1-r0/myhelloworld-0.1/myhelloworld
+tmp/work/myhelloworld-0.1-r0/temp
+tmp/work/myhelloworld-0.1-r0/temp/run.do_configure.21840
+tmp/work/myhelloworld-0.1-r0/temp/log.do_stage.21840
+tmp/work/myhelloworld-0.1-r0/temp/log.do_install.21840
+tmp/work/myhelloworld-0.1-r0/temp/log.do_compile.21840
+tmp/work/myhelloworld-0.1-r0/temp/run.do_stage.21840
+tmp/work/myhelloworld-0.1-r0/temp/log.do_configure.21840
+tmp/work/myhelloworld-0.1-r0/temp/run.do_install.21840
+tmp/work/myhelloworld-0.1-r0/temp/run.do_compile.21840
+tmp/work/myhelloworld-0.1-r0/install
+tmp/work/myhelloworld-0.1-r0/install/myhelloworld-locale
+tmp/work/myhelloworld-0.1-r0/install/myhelloworld-dbg
+tmp/work/myhelloworld-0.1-r0/install/myhelloworld-dev
+tmp/work/myhelloworld-0.1-r0/install/myhelloworld-doc
+tmp/work/myhelloworld-0.1-r0/install/myhelloworld-doc/usr
+tmp/work/myhelloworld-0.1-r0/install/myhelloworld-doc/usr/share
+tmp/work/myhelloworld-0.1-r0/install/myhelloworld-doc/usr/share/doc
+tmp/work/myhelloworld-0.1-r0/install/myhelloworld-doc/usr/share/doc/myhelloworld
+tmp/work/myhelloworld-0.1-r0/install/myhelloworld-doc/usr/share/doc/myhelloworld/README.txt
+tmp/work/myhelloworld-0.1-r0/install/myhelloworld
+tmp/work/myhelloworld-0.1-r0/install/myhelloworld/usr
+tmp/work/myhelloworld-0.1-r0/install/myhelloworld/usr/bin
+tmp/work/myhelloworld-0.1-r0/install/myhelloworld/usr/bin/myhelloworld
+tmp/work/myhelloworld-0.1-r0/image
+tmp/work/myhelloworld-0.1-r0/image/usr
+tmp/work/myhelloworld-0.1-r0/image/usr/bin
+tmp/work/myhelloworld-0.1-r0/image/usr/share
+tmp/work/myhelloworld-0.1-r0/image/usr/share/doc
+tmp/work/myhelloworld-0.1-r0/image/usr/share/doc/myhelloworld
+tmp/work/myhelloworld-0.1-r0/myhelloworld.c
+tmp/work/myhelloworld-0.1-r0/README.txt
+~/oe%&gt;</screen>Things to note here are:</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>The two source files are in <emphasis
+ role="bold">tmp/work/myhelloworld-0.1-r0</emphasis>, which is the
+ working directory as specified via the <emphasis
+ role="bold">${WORKDIR}</emphasis> variable;</para>
+ </listitem>
+
+ <listitem>
+ <para>There's logs of the various tasks in <emphasis
+ role="bold">tmp/work/myhelloworld-0.1-r0/temp</emphasis> which you
+ can look at for more details on what was done in each task;</para>
+ </listitem>
+
+ <listitem>
+ <para>There's an image directory at <emphasis
+ role="bold">tmp/work/myhelloworld-0.1-r0/image</emphasis> which
+ contains just the directories that were to be packaged up. This is
+ actually the destination directory, as specified via the <emphasis
+ role="bold">${D}</emphasis> variable. The two files that we
+ installed were originally in here, but during packaging they were
+ moved into the install area into a subdirectory specific to the
+ package that was being created (remember we have a main package and
+ a -doc package being created.</para>
+ </listitem>
+
+ <listitem>
+ <para>The program was actually compiled in the <emphasis
+ role="bold">tmp/work/myhelloworld-0.1-r0/myhelloworld-0.1</emphasis>
+ directory, this is the source directory as specified via the
+ <emphasis role="bold">${S}</emphasis> variable.</para>
+ </listitem>
+
+ <listitem>
+ <para>There's an install directory at <emphasis
+ role="bold">tmp/work/myhelloworld-0.1-r0/install</emphasis> which
+ contains the packages that were being generated and the files that
+ go in the package. So we can see that the myhelloworld-doc package
+ contains the single file <emphasis
+ role="bold">/usr/share/doc/myhelloworld/README.txt</emphasis>, the
+ myhelloworld package contains the single file <emphasis
+ role="bold">/usr/bin/myhelloworld</emphasis> and the -dev, -dbg and
+ -local packages are all empty.</para>
+ </listitem>
+ </itemizedlist>
+
+ <para>At this stage it's good to verify that we really did produce a
+ binary for the target and not for our host system. We can check that
+ with the file command:<screen>~/oe%&gt; file tmp/work/myhelloworld-0.1-r0/install/myhelloworld/usr/bin/myhelloworld
+tmp/work/myhelloworld-0.1-r0/install/myhelloworld/usr/bin/myhelloworld: ELF 32-bit LSB executable, Hitachi SH, version 1 (SYSV), for GNU/Linux 2.4.0, dynamically linked (uses shared libs), for GNU/Linux 2.4.0, not stripped
+~/oe%&gt; file /bin/ls
+/bin/ls: ELF 64-bit LSB executable, AMD x86-64, version 1 (SYSV), for GNU/Linux 2.4.0, dynamically linked (uses shared libs), for GNU/Linux 2.4.0, stripped
+~/oe%&gt;</screen>This shows us that the helloworld program is for an SH
+ processor (obviously this will change depending on what your target
+ system is), while checking the <emphasis role="bold">/bin/ls</emphasis>
+ program on host shows us that the host system is an AMD X86-64 system.
+ That's exactly what we wanted.</para>
+ </section>
+
+ <section id="recipes_autoconf_example" xreflabel="autoconf example">
+ <title>An autotools package</title>
+
+ <para>Now for an example of a package that uses autotools. These are
+ programs that you need to run a configure script for, passing various
+ parameters, and then make. To make these work when cross-compiling you
+ need to provides a lot of variables to the configure script. But all the
+ hard work as already been done for you. There's an <xref
+ linkend="autotools_class" /> which takes care of most of the complexity
+ of building an autotools based packages.</para>
+
+ <para>Let's take a look at the tuxnes recipe which is an example of a
+ very simple autotools based recipe:<screen>%~oe&gt; cat packages/tuxnes/tuxnes_0.75.bb
+DESCRIPTION = "Tuxnes Nintendo (8bit) Emulator"
+HOMEPAGE = "http://prdownloads.sourceforge.net/tuxnes/tuxnes-0.75.tar.gz"
+LICENSE = "GPLv2"
+SECTION = "x/games"
+PRIORITY = "optional"
+PR = "r1"
+
+SRC_URI = "http://heanet.dl.sourceforge.net/sourceforge/tuxnes/tuxnes-0.75.tar.gz"
+
+inherit autotools</screen></para>
+
+ <para>This is a really simple recipe. There's the standard header that
+ describes the package. Then the SRC_URI, which in this case is a http
+ URL that causes the source code to be downloaded from the specified URI.
+ And finally there's an "<emphasis role="bold">inherit
+ autotools</emphasis>" command which loads the autotools class. The
+ autotools class will take care of generating the require configure,
+ compile and install tasks. So in this case there's nothing else to do -
+ that's all there is to it.</para>
+
+ <para>It would be nice if it was always this simple. Unfortunately
+ there's usually a lot more involved for various reasons including the
+ need to:</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>Pass parameters to configure to enable and disable
+ features;</para>
+ </listitem>
+
+ <listitem>
+ <para>Pass parameters to configure to specify where to find
+ libraries and headers;</para>
+ </listitem>
+
+ <listitem>
+ <para>Make modifications to prevent searching for headers and
+ libraries in the normal locations (since they below to the host
+ system, not the target);</para>
+ </listitem>
+
+ <listitem>
+ <para>Make modifications to prevent the configure script from tying
+ to compile and run programs - any programs it compiles will be for
+ the target and not the host and so cannot be run.</para>
+ </listitem>
+
+ <listitem>
+ <para>Manually implement staging scripts;</para>
+ </listitem>
+
+ <listitem>
+ <para>Deal with lots of other more complex issues;</para>
+ </listitem>
+ </itemizedlist>
+
+ <para>Some of these items are covered in more detail in the advanced
+ autoconf section.</para>
+ </section>
+ </section>
+
+ <section id="recipes_depenencies" xreflabel="dependencies">
+ <title>Dependencies: What's needed to build and/or run the
+ package?</title>
+
+ <para>Dependencies should be familiar to anyone who has used an .rpm and
+ .deb based desktop distribution. A dependency is something that a package
+ requires either to run the package (a run-time dependency) or to build the
+ package (a build-time or compile-time, dependency).</para>
+
+ <para>There are two variables provided to allow the specifications of
+ dependencies:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>DEPENDS</term>
+
+ <listitem>
+ <para>Specifies build-time dependencies, via a list of bitbake
+ recipes to build prior to build the recipe. These are programs
+ (flex-native) or libraries (libpcre) that are required in order to
+ build the package.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>RDEPENDS</term>
+
+ <listitem>
+ <para>Specifies run-time dependencies, via a list of packages to
+ install prior to installing the current package. These are programs
+ or libraries that are required in order to run the program. Note
+ that libraries which are dynamically linked to an application will
+ be automatically detected and added to <emphasis
+ role="bold">RDEPENDS</emphasis> and therefore do not need to be
+ explicitly declared. If a library was dynamically loaded then it
+ would need to be explicitly listed.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>If we take openssh for an example, it requires zlib and openssl in
+ order to both built and run. In the recipe we have:<screen>DEPENDS = "zlib openssl"</screen>This
+ tells bitbake that it will need to build and stage zlib and openssl prior
+ to trying to build openssh, since openssh requires both of them. Note that
+ there is no <emphasis role="bold">RDEPENDS</emphasis> even though openssh
+ requires both of them to run. The run time dependencies on libz1 (the name
+ of the package containing the zlib library) and libssl0 (the name of the
+ package containing the ssl library) are automatically determined and added
+ via the auto shared libs dependency code.</para>
+ </section>
+
+ <section id="recipes_methods" xreflabel="methods">
+ <title>Methods: Inbuilt methods to make your life easier</title>
+
+ <para>There are several helper functions defined by the base class, which
+ is included by default for all recipes. Many of these are used a lot in
+ both recipes and other classes.</para>
+
+ <para>The most commonly seen, and most useful functions, include:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>oe_runmake</term>
+
+ <listitem>
+ <para>This function is used to run make. However unlike calling make
+ yourself this will pass the EXTRA_OEMAKE settings to make, will
+ display a note about the make command and will check for any errors
+ generated via the call to make.</para>
+
+ <para>You should never have any reason to call make directly and
+ should also use oe_runmake when you need to run make.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>oe_runconf (autotools only)</term>
+
+ <listitem>
+ <para>This function is used to run the configure script of a package
+ that is using the autotools class. This takes care of passing all of
+ the correct parameters for cross-compiling and for installing into
+ the appropriate target directory.</para>
+
+ <para>It also passes the value of the <emphasis
+ role="bold">EXTRA_OECONF</emphasis> variable to the configure
+ script. For many situations setting <emphasis
+ role="bold">EXTRA_OECONF</emphasis> is sufficient and you'll have no
+ need to define your own configure task in which you call oe_runconf
+ manually.</para>
+
+ <para>If you need to write your own <emphasis>configure</emphasis>
+ task for an autotools package you can use oe_runconf to manually
+ call the configure process when it is required. The following
+ example from net-snmp shows oe_runconf being called manually so that
+ the parameter for specifying the endianess can be computed and
+ passed in to the configure script:<screen>do_configure() {
+ # Additional flag based on target endiness (see siteinfo.bbclass)
+ ENDIANESS="${@base_conditional('SITEINFO_ENDIANESS', 'le', '--with-endianness=little', '--with-endianness=big', d)}"
+ oenote Determined endianess as: $ENDIANESS
+ oe_runconf $ENDIANESS
+}</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>oe_libinstall</term>
+
+ <listitem>
+ <para>This function is used to install <emphasis
+ role="bold">.so</emphasis>, <emphasis role="bold">.a</emphasis> and
+ associated libtool <emphasis role="bold">.la</emphasis> libraries.
+ It will determine the appropriate libraries to install and take care
+ of any modifications that may be require for <emphasis
+ role="bold">.la</emphasis> files.</para>
+
+ <para>This function supports the following options:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>-C &lt;dir&gt;</term>
+
+ <listitem>
+ <para>Change into the specified directory before attempting to
+ install a library. Used when the libraries are in
+ subdirectories of the main package.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>-s</term>
+
+ <listitem>
+ <para>Require the presence of a <emphasis
+ role="bold">.so</emphasis> library as one of the libraries
+ that is installed.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>-a</term>
+
+ <listitem>
+ <para>Require the presence of a <emphasis
+ role="bold">.a</emphasis> library as one of the libraries that
+ is installed.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>The following example from gdbm shows the installation of
+ <emphasis role="bold">.so</emphasis>, <emphasis
+ role="bold">.a</emphasis> (and associated <emphasis
+ role="bold">.la</emphasis>) libraries into the staging library
+ area:<screen>do_stage () {
+ oe_libinstall -so -a libgdbm ${STAGING_LIBDIR}
+ install -m 0644 ${S}/gdbm.h ${STAGING_INCDIR}/
+}</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>oenote</term>
+
+ <listitem>
+ <para>Used to display an informational messages to the user.</para>
+
+ <para>The following example from net-snmp uses oenote to tell the
+ user which endianess it determined was appropriate for the target
+ device:<screen>do_configure() {
+ # Additional flag based on target endiness (see siteinfo.bbclass)
+ ENDIANESS="${@base_conditional('SITEINFO_ENDIANESS', 'le', '--with-endianness=little', '--with-endianness=big', d)}"
+ oenote Determined endianess as: $ENDIANESS
+ oe_runconf $ENDIANESS
+}</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>oewarn</term>
+
+ <listitem>
+ <para>Used to display a warning message to the user, warning of
+ something that may be problematic or unexpected.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>oedebug</term>
+
+ <listitem>
+ <para>Used to display debugging related information. These messages
+ will only be visible when bitbake is run with the <emphasis
+ role="bold">-D</emphasis> flag to enable debug output.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>oefatal</term>
+
+ <listitem>
+ <para>Used to display a fatal error message to the user, and then
+ abort the bitbake run.</para>
+
+ <para>The following example from linux-libc-headers shows the use of
+ oefatal to tell the user when it cannot find the kernel source code
+ for the specified target architecture:<screen>do_configure () {
+ case ${TARGET_ARCH} in
+ alpha*) ARCH=alpha ;;
+ arm*) ARCH=arm ;;
+ cris*) ARCH=cris ;;
+ hppa*) ARCH=parisc ;;
+ i*86*) ARCH=i386 ;;
+ ia64*) ARCH=ia64 ;;
+ mips*) ARCH=mips ;;
+ m68k*) ARCH=m68k ;;
+ powerpc*) ARCH=ppc ;;
+ s390*) ARCH=s390 ;;
+ sh*) ARCH=sh ;;
+ sparc64*) ARCH=sparc64 ;;
+ sparc*) ARCH=sparc ;;
+ x86_64*) ARCH=x86_64 ;;
+ esac
+ if test ! -e include/asm-$ARCH; then
+ oefatal unable to create asm symlink in kernel headers
+ fi
+...</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>base_conditional (python)</term>
+
+ <listitem>
+ <para>The base conditional python function is used to set a variable
+ to one of two values based on the definition of a third variable.
+ The general usage is:<screen>${@base_conditional('&lt;variable-name&gt;', '&lt;value&gt;', '&lt;true-result&gt;', &lt;false-result&gt;', d)}"</screen>where:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>variable-name</term>
+
+ <listitem>
+ <para>This is the name of a variable to check.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>value</term>
+
+ <listitem>
+ <para>This is the value to compare the variable
+ against.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>true-result</term>
+
+ <listitem>
+ <para>If the variable equals the value then this is what is
+ returned by the function.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>false-result</term>
+
+ <listitem>
+ <para>If the variable does not equal the value then this is
+ what is returned by the function.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <note>
+ <para>The ${@...} syntax is used to call python functions from
+ within a recipe or class. This is described in more detail in the
+ <xref linkend="recipes_advanced_python" /> section.</para>
+ </note>
+
+ <para>The following example from the openssl recipe shows the
+ addition of either <emphasis role="bold">-DL_ENDING</emphasis> or
+ <emphasis role="bold">-DB_ENDIAN</emphasis> depending on the value
+ of <emphasis role="bold">SITEINFO_ENDIANESS</emphasis> which is set
+ to le for little endian targets and to be for big endian
+ targets:<screen>do_compile () {
+ ...
+ # Additional flag based on target endiness (see siteinfo.bbclass)
+ CFLAG="${CFLAG} ${@base_conditional('SITEINFO_ENDIANESS', 'le', '-DL_ENDIAN', '-DB_ENDIAN', d)}"
+ ...</screen></para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </section>
+
+ <section id="recipes_packages" xreflabel="packages">
+ <title>Packaging: Defining packages and their contents</title>
+
+ <para>A bitbake recipe is a set of instructions from creating one, or
+ more, packages for installation on the target device. Typically these are
+ .ipkg or .deb packages (although bitbake itself isn't associated with any
+ particular packaging format).</para>
+
+ <para>By default several packages are produced automatically without any
+ special action required on the part of the recipe author. The following
+ example of the packaging output from the helloworld example above shows
+ this packaging in action:<screen>[NOTE: package helloworld-0.1-r0: task do_package_write: started
+NOTE: Not creating empty archive for helloworld-dbg-0.1-r0
+Packaged contents of helloworld into /home/lenehan/devel/oe/build/titan-glibc-25/tmp/deploy/ipk/sh4/helloworld_0.1-r0_sh4.ipk
+Packaged contents of helloworld-doc into /home/lenehan/devel/oe/build/titan-glibc-25/tmp/deploy/ipk/sh4/helloworld-doc_0.1-r0_sh4.ipk
+NOTE: Not creating empty archive for helloworld-dev-0.1-r0
+NOTE: Not creating empty archive for helloworld-locale-0.1-r0
+NOTE: package helloworld-0.1-r0: task do_package_write: completed</screen>We
+ can see from above that the packaging did the following:</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>Created a main package, <emphasis
+ role="bold">helloworld_0.1-r0_sh4.ipk</emphasis>. This package
+ contains the helloworld binary <emphasis
+ role="bold">/usr/bin/helloworld</emphasis>.</para>
+ </listitem>
+
+ <listitem>
+ <para>Created a documentation package, <emphasis
+ role="bold">helloworld-doc_0.1-r0_sh4.ipk</emphasis>. This package
+ contains the readme file <emphasis
+ role="bold">/usr/share/doc/helloworld/README.txt</emphasis>.</para>
+ </listitem>
+
+ <listitem>
+ <para>Considered creating a debug package, <emphasis
+ role="bold">helloworld-dbg-0.1-r0_sh4.ipk</emphasis>, a development
+ package <emphasis role="bold">helloworld-dev-0.1-r0_sh4.ipk</emphasis>
+ and a locale package <emphasis
+ role="bold">helloworld-locale-0.1-r0_sh4.ipk</emphasis>. It didn't
+ create the package due to the fact that it couldn't find any files
+ that would actually go in the package.</para>
+ </listitem>
+ </itemizedlist>
+
+ <para>There are several things happening here which are important to
+ understand:</para>
+
+ <orderedlist>
+ <listitem>
+ <para>There is a default set of packages that are considered for
+ creation. This set of packages is controlled via the <emphasis
+ role="bold">PACKAGES</emphasis> variable.</para>
+ </listitem>
+
+ <listitem>
+ <para>For each package there is a default set of files and/or
+ directories that are considered to belong to those packages. The
+ documentation packages for example include anything found <emphasis
+ role="bold">/usr/share/doc</emphasis>. The set of files and
+ directories is controlled via the <emphasis
+ role="bold">FILES_&lt;package-name&gt;</emphasis> variables.</para>
+ </listitem>
+
+ <listitem>
+ <para>By default packages that contain no files are not created and no
+ error is generated. The decision to create empty packages or not is
+ controlled via the <emphasis role="bold">ALLOW_EMPTY</emphasis>
+ variable.</para>
+ </listitem>
+ </orderedlist>
+
+ <section>
+ <title>Philosophy</title>
+
+ <para>Separate packaging, where possible, is of high importance in
+ OpenEmbedded. Many of the target devices have limited storage space and
+ RAM and giving distributions and users the option of not installing a
+ part of the package they don't need allows them to reduce the amount of
+ storage space required.</para>
+
+ <para>As an example almost no distributions will include documentation
+ or development libraries since they are not required for the day to day
+ operation of the device. In particular if your package provides multiple
+ binaries, and it would be common to only use one or the other, then you
+ should consider separating them into separate packages.</para>
+
+ <para>By default several groups of files are automatically separate out,
+ including:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>dev</term>
+
+ <listitem>
+ <para>Any files required for development. This includes header
+ files, static libraries, the shared library symlinks required only
+ for linking etc. These would only ever need to be installed by
+ someone attempt to compile applications on the target device.
+ While this does happen it is very uncommon and so these files are
+ automatically moved into a separate package</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>doc</term>
+
+ <listitem>
+ <para>Any documentation related files, including man pages. These
+ are files which are of informational purposes only. For many
+ embedded devices there is no way for the user to see any of the
+ documentation anyway, and documentation can consume a lot of
+ space. By separating these out they don't take any space by
+ default but distributions and/or users may choose to install them
+ if they need some documentation on a specific package.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>locale</term>
+
+ <listitem>
+ <para>Locale information provides translation information for
+ packages. Many users do not require these translations, and many
+ devices will only want to provide them for user visible
+ components, such as UI related items, and not for system binaries.
+ By separating these out it is left up to the distribution or users
+ to decide if they are required or not.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </section>
+
+ <section>
+ <title>Default packages and files</title>
+
+ <para>The defaults package settings are defined in <emphasis
+ role="bold">conf/bitbake.conf</emphasis> and are suitable for a lot of
+ recipes without any changes. The following list shows the default values
+ for the packaging related variables:</para>
+
+ <para><variablelist>
+ <varlistentry>
+ <term>PACKAGES</term>
+
+ <listitem>
+ <para>This variable lists the names of each of the packages that
+ are to be generated.<screen>PACKAGES = "${PN}-dbg ${PN} ${PN}-doc ${PN}-dev ${PN}-locale"</screen>Note
+ that the order of packages is important: the packages are
+ processed in the listed order. So if two packages specify the
+ same file then the first package listed in packages will get the
+ file. This is important when packages use wildcards to specify
+ their contents.</para>
+
+ <para>For example if the main package, <emphasis
+ role="bold">${PN}</emphasis>, contains <emphasis
+ role="bold">/usr/bin/*</emphasis> (i.e. all files in <emphasis
+ role="bold">/usr/bin</emphasis>), but you want <emphasis
+ role="bold">/usr/bin/tprogram</emphasis> in a separate package,
+ <emphasis role="bold">${PN}-tpackage</emphasis>, you would need
+ to either ensure that <emphasis
+ role="bold">${PN}-tpackage</emphasis> is listed prior to
+ <emphasis role="bold">${PN}</emphasis> in <emphasis
+ role="bold">PACKAGES</emphasis> or that <emphasis
+ role="bold">FILES_${PN}</emphasis> was modified to not contain
+ the wildcard that matches <emphasis
+ role="bold">/usr/bin/tprogram</emphasis>.</para>
+
+ <para>Note that the -dbg package contains the debugging
+ information that has been extracted from binaries and libraries
+ prior to them being stripped. This package should always be the
+ first package in the package list to ensure that the debugging
+ information is correctly extracted and moved to the package
+ prior to any other packaging decisions being made.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>FILES_${PN}</term>
+
+ <listitem>
+ <para>The base package, this includes everything needed to
+ actually run the application on the target system.<screen>FILES_${PN} = "\
+ ${bindir}/* \
+ ${sbindir}/* \
+ ${libexecdir}/* \
+ ${libdir}/lib*.so.* \
+ ${sysconfdir} \
+ ${sharedstatedir} \
+ ${localstatedir} \
+ /bin/* \
+ /sbin/* \
+ /lib/*.so* \
+ ${datadir}/${PN} \
+ ${libdir}/${PN}/* \
+ ${datadir}/pixmaps \
+ ${datadir}/applications \
+ ${datadir}/idl \
+ ${datadir}/omf \
+ ${datadir}/sounds \
+ ${libdir}/bonobo/servers"</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>FILES_${PN}-dbg</term>
+
+ <listitem>
+ <para>The debugging information extracted from non-stripped
+ versions of libraries and executable's. OpenEmbedded
+ automatically extracts the debugging information into files in
+ .debug directories and then strips the original files.<screen>FILES_${PN}-dbg = "\
+ ${bindir}/.debug \
+ ${sbindir}/.debug \
+ ${libexecdir}/.debug \
+ ${libdir}/.debug \
+ /bin/.debug \
+ /sbin/.debug \
+ /lib/.debug \
+ ${libdir}/${PN}/.debug"</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>FILES_${PN}-doc</term>
+
+ <listitem>
+ <para>Documentation related files. All documentation is
+ separated into it's own package so that it does not need to be
+ installed unless explicitly required.<screen>FILES_${PN}-doc = "\
+ ${docdir} \
+ ${mandir} \
+ ${infodir} \
+ ${datadir}/gtk-doc \
+ ${datadir}/gnome/help"</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>FILES_${PN}-dev</term>
+
+ <listitem>
+ <para>Development related files. Any headers, libraries and
+ support files needed for development work on the target.<screen>FILES_${PN}-dev = "\
+ ${includedir} \
+ ${libdir}/lib*.so \
+ ${libdir}/*.la \
+ ${libdir}/*.a \
+ ${libdir}/*.o \
+ ${libdir}/pkgconfig \
+ /lib/*.a \
+ /lib/*.o \
+ ${datadir}/aclocal"</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>FILES_${PN}-locale</term>
+
+ <listitem>
+ <para>Locale related files.<screen>FILES_${PN}-locale = "${datadir}/locale"</screen></para>
+ </listitem>
+ </varlistentry>
+ </variablelist></para>
+ </section>
+
+ <section>
+ <title>Wildcards</title>
+
+ <para>Wildcards used in the <emphasis role="bold">FILES</emphasis>
+ variables are processed via the python function <emphasis
+ role="bold">fnmatch</emphasis>. The following items are of note about
+ this function:</para>
+
+ <itemizedlist>
+ <listitem>
+ <para><emphasis role="bold">/&lt;dir&gt;/*</emphasis>: This will
+ match all files and directories in the <emphasis
+ role="bold">dir</emphasis> - it will not match other
+ directories.</para>
+ </listitem>
+
+ <listitem>
+ <para><emphasis role="bold">/&lt;dir&gt;/a*</emphasis>: This will
+ only match files, and not directories.</para>
+ </listitem>
+
+ <listitem>
+ <para><emphasis role="bold">/dir</emphasis>: will include the
+ directory <emphasis role="bold">dir</emphasis> in the package, which
+ in turn will include all files in the directory and all
+ subdirectories.</para>
+ </listitem>
+ </itemizedlist>
+
+ <para>Note that the order of packages effects the files that will be
+ matched via wildcards. Consider the case where we have three binaries in
+ the <command>/usr/bin</command> directory and we want the test program
+ in a separate package:<screen>/usr/bin/programa /usr/bin/programb /usr/bin/test</screen>So
+ we define a new package and instruct bitbake to include /usr/bin/test in
+ it.</para>
+
+ <screen>FILES-${PN}-test = "${bindir}/test"
+PACKAGES += "FILES-${PN}-test"</screen>
+
+ <para>When the package is regenerated no <emphasis
+ role="bold">${PN}-test</emphasis> package will be created. The reason
+ for this is that the <emphasis role="bold">PACKAGES</emphasis> line now
+ looks like this:<screen>{PN}-dbg ${PN} ${PN}-doc ${PN}-dev ${PN}-locale ${PN}-test</screen>Note
+ how <emphasis role="bold">${PN}</emphasis> is listed prior to <emphasis
+ role="bold">${PN}-test</emphasis>, and if we look at the definition of
+ <emphasis role="bold">FILES-${PN}</emphasis> it contains the <emphasis
+ role="bold">${bindir}/*</emphasis> wildcard. Since <emphasis
+ role="bold">${PN}</emphasis> is first it'll match that wildcard are be
+ moved into the <emphasis role="bold">${PN}</emphasis> package prior to
+ processing of the <emphasis role="bold">${PN}-test</emphasis>
+ package.</para>
+
+ <para>To achieve what we are trying to accomplish we have two
+ options:</para>
+
+ <orderedlist>
+ <listitem>
+ <para>Modify the definition of <emphasis
+ role="bold">${PN}</emphasis> so that the wildcard does not match the
+ test program.</para>
+
+ <para>We could do this for example:<screen>FILES-${PN} = "${bindir}/p*"</screen>So
+ now this will only match things in the bindir that start with p, and
+ therefore not match our test program. Note that <emphasis
+ role="bold">FILES-${PN}</emphasis> contains a lot more entries and
+ we'd need to add any of the other that refer to files that are to be
+ included in the package. In this case we have no other files, so
+ it's safe to do this simple declaration.</para>
+ </listitem>
+
+ <listitem>
+ <para>Modify the order of packages so that the <emphasis
+ role="bold">${PN}-test</emphasis> package is listed first.</para>
+
+ <para>The most obvious way to do this would be to prepend our new
+ package name to the packages list instead of appending it:<screen>PACKAGES =+ "FILES-${PN}-test"</screen>In
+ some cases this would work fine, however there is a problem with
+ this for packages that include binaries. The package will now be
+ listed before the -dbg package and often this will result in the
+ .debug directories being included in the package. In this case we
+ are explicitly listing only a single file (and not using wildcards)
+ and therefore it would be ok.</para>
+
+ <para>In general it's more common to have to redefine the entire
+ package list to include your new package plus any of the default
+ packages that you require:<screen>PACKAGES = "${PN}-dbg ${PN}-test ${PN} ${PN}-doc ${PN}-dev ${PN}-locale"</screen></para>
+ </listitem>
+ </orderedlist>
+ </section>
+
+ <section>
+ <title>Checking the packages</title>
+
+ <para>During recipe development it's useful to be able to check on
+ exactly what files went into each package, which files were not packaged
+ and which packages contain no files.</para>
+
+ <para>One of easiest method is to run find on the install directory. In
+ the install directory there is one subdirectory created per package, and
+ the files are moved into the install directory as they are matched to a
+ specific package. The following shows the packages and files for the
+ helloworld example:<screen>~/oe%&gt; find tmp/work/helloworld-0.1-r0/install
+tmp/work/helloworld-0.1-r0/install
+tmp/work/helloworld-0.1-r0/install/helloworld-locale
+tmp/work/helloworld-0.1-r0/install/helloworld-dbg
+tmp/work/helloworld-0.1-r0/install/helloworld-dev
+tmp/work/helloworld-0.1-r0/install/helloworld-doc
+tmp/work/helloworld-0.1-r0/install/helloworld-doc/usr
+tmp/work/helloworld-0.1-r0/install/helloworld-doc/usr/share
+tmp/work/helloworld-0.1-r0/install/helloworld-doc/usr/share/doc
+tmp/work/helloworld-0.1-r0/install/helloworld-doc/usr/share/doc/helloworld
+tmp/work/helloworld-0.1-r0/install/helloworld-doc/usr/share/doc/helloworld/README.txt
+tmp/work/helloworld-0.1-r0/install/helloworld
+tmp/work/helloworld-0.1-r0/install/helloworld/usr
+tmp/work/helloworld-0.1-r0/install/helloworld/usr/bin
+tmp/work/helloworld-0.1-r0/install/helloworld/usr/bin/helloworld
+~/oe%&gt;</screen>The above shows that the -local, -dbg and -dev packages are
+ all empty, and the -doc and base package contain a single file each.
+ Uses "<emphasis role="bold">-type f</emphasis>" option to find to show
+ just files will make this clearer as well.</para>
+
+ <para>In addition to the install directory the image directory (which
+ corresponds to the destination directory, <emphasis
+ role="bold">D</emphasis>) will contain any files that were not
+ packaged:<screen>~/oe%&gt; find tmp/work/helloworld-0.1-r0/image
+tmp/work/helloworld-0.1-r0/image
+tmp/work/helloworld-0.1-r0/image/usr
+tmp/work/helloworld-0.1-r0/image/usr/bin
+tmp/work/helloworld-0.1-r0/image/usr/share
+tmp/work/helloworld-0.1-r0/image/usr/share/doc
+tmp/work/helloworld-0.1-r0/image/usr/share/doc/helloworld
+~/oe%&gt;</screen>In this case all files were packaged and so there are no
+ left over files. Using find with "<emphasis role="bold">-type
+ f</emphasis>" makes this much clearer:<screen>~/oe%&gt; find tmp/work/helloworld-0.1-r0/image -type f
+~/oe%&gt;</screen></para>
+
+ <para>Messages reading missing files are also display by bitbake during
+ the package task:<screen>NOTE: package helloworld-0.1-r0: task do_package: started
+NOTE: the following files were installed but not shipped in any package:
+NOTE: /usualdir/README.txt
+NOTE: package helloworld-0.1-r0: task do_package: completed</screen>Except in
+ very unusual circumstances there should be no unpackaged files left
+ behind by a recipe.</para>
+ </section>
+
+ <section>
+ <title>Excluding files</title>
+
+ <para>There's no actual support for explicitly excluding files from
+ packaging. You could just leave them out of any package, but then you'll
+ get warnings (or errors if requesting full package checking) during
+ packaging which is not desirable. It also doesn't let other people know
+ that you've deliberately avoided packaging the file or files.</para>
+
+ <para>In order to exclude a file totally you should avoid installing it
+ in the first place during the install task.</para>
+
+ <para>In some cases it may be easier to let the package install the file
+ and then explicitly remove the file and the end of the install task. The
+ following example from the samba recipe shows the removal of several
+ files that get installed via the default install task generated by the
+ <xref linkend="autotools_class" />. By using
+ <emphasis>do_install_append</emphasis> these commands and run after the
+ autotools generated install task:</para>
+
+ <screen>do_install_append() {
+ ...
+ rm -f ${D}${bindir}/*.old
+ rm -f ${D}${sbindir}/*.old
+ ...
+}</screen>
+ </section>
+
+ <section>
+ <title>Debian naming</title>
+
+ <para>A special <emphasis>debian library name</emphasis> policy can be
+ applied for packages that contain a single shared library. When enabled
+ packages will be renamed to match the debian policy for such
+ packages.</para>
+
+ <para>Debian naming is enabled by including the debian class via either
+ <command>local.conf</command> or your distributions configuration
+ file:<screen>INHERIT += "debian"</screen></para>
+
+ <para>The policy works by looking at the shared library name and version
+ and will automatically rename the package to
+ <emphasis>&lt;libname&gt;&lt;lib-major-version&gt;</emphasis>. For
+ example if the package name (PN) is <command>foo</command> and the
+ package ships a file named <command>libfoo.so.1.2.3</command> then the
+ package will be renamed to <command>libfoo1</command> to follow the
+ debian policy.</para>
+
+ <para>If we look at the <emphasis>lzo_1.08.bb</emphasis> recipe,
+ currently at release 14, it generates a package containing a single
+ shared library :<screen>~oe/build/titan-glibc-25%&gt; find tmp/work/lzo-1.08-r14/install/
+tmp/work/lzo-1.08-r14/install/lzo
+tmp/work/lzo-1.08-r14/install/lzo/usr
+tmp/work/lzo-1.08-r14/install/lzo/usr/lib
+tmp/work/lzo-1.08-r14/install/lzo/usr/lib/liblzo.so.1
+tmp/work/lzo-1.08-r14/install/lzo/usr/lib/liblzo.so.1.0.0</screen>Without
+ debian naming this package would have been called
+ <command>lzo_1.08-r14_sh4.ipk</command> (and the corresponding dev and
+ dbg packages would have been called
+ <command>lzo-dbg_1.08-r14_sh4.ipk</command> and
+ <command>lzo-dev_1.08-r14_sh4.ipk</command>). However with debian naming
+ enabled the package is renamed based on the name of the shared library,
+ which is <command>liblzo.so.1.0.0</command> in this case. So the name
+ <command>lzo</command> is replaced with
+ <command>liblzo1</command>:<screen>~oe/build/titan-glibc-25%&gt; find tmp/deploy/ipk/ -name '*lzo*'
+tmp/deploy/ipk/sh4/liblzo1_1.08-r14_sh4.ipk
+tmp/deploy/ipk/sh4/liblzo-dev_1.08-r14_sh4.ipk
+tmp/deploy/ipk/sh4/liblzo-dbg_1.08-r14_sh4.ipk</screen></para>
+
+ <para>Some variables are available which effect the operation of the
+ debian renaming class:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>LEAD_SONAME</term>
+
+ <listitem>
+ <para>If the package actually contains multiple shared libraries
+ then one will be selected automatically and a warning will be
+ generated. This variable is a regular expression which is used to
+ select which shared library from those available is to be used for
+ debian renaming.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>DEBIAN_NOAUTONAME_&lt;pkgname&gt;</term>
+
+ <listitem>
+ <para>If this variable is set to 1 for a package then debian
+ renaming will not be applied for the package.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>AUTO_LIBNAME_PKGS</term>
+
+ <listitem>
+ <para>If set this variable specifies the prefix of packages which
+ will be subject to debian renaming. This can be used to prevent
+ all of the packages being renamed via the renaming policy.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </section>
+
+ <section>
+ <title>Empty packages</title>
+
+ <para>By default empty packages are ignored. Occasionally you may wish
+ to actually created empty packages, typically done when you want a
+ virtual package which will install other packages via dependencies
+ without actually installing anything itself. The <emphasis
+ role="bold">ALLOW_EMPTY</emphasis> variable is used to control the
+ creation of empty packages:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>ALLOW_EMPTY</term>
+
+ <listitem>
+ <para>Controls if empty packages will be created or not. By
+ default this is <emphasis role="bold">"0"</emphasis> and empty
+ packages are not created. Setting this to <emphasis
+ role="bold">"1"</emphasis> will permit the creation of empty
+ packages (packages containing no files).</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </section>
+ </section>
+
+ <section id="recipes_tasks" xreflabel="tasks">
+ <title>Tasks: Playing with tasks</title>
+
+ <para>Bitbake steps through a series of tasks when building a recipe.
+ Sometimes you need to explicitly define what a class does, such as
+ providing a <emphasis role="bold">do_install</emphasis> function to
+ implement the <emphasis>install</emphasis> task in a recipe and sometimes
+ they are provided for you by common classes, such as the autotools class
+ providing the default implementations of <emphasis>configure</emphasis>,
+ <emphasis>compile</emphasis> and <emphasis>install</emphasis>
+ tasks.</para>
+
+ <para>There are several methods available to modify the tasks that are
+ being run:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>Overriding the default task implementation</term>
+
+ <listitem>
+ <para>By defining your own implementation of task you'll override
+ any default or class provided implementations.</para>
+
+ <para>For example, you can define you own implementation of the
+ compile task to override any default implementation:<screen>do_compile() {
+ oe_runmake DESTDIR=${D}
+}</screen></para>
+
+ <para>If you with to totally prevent the task from running you need
+ to define your own empty implementation. This is typically done via
+ the definition of the task using a single colon:<screen>do_configure() {
+ :
+}</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Appending or prepending to the task</term>
+
+ <listitem>
+ <para>Sometime you want the default implementation, but you require
+ addition functionality. This can done by appending or pre-pending
+ additional functionality onto the task.</para>
+
+ <para>The following example from units shows an example of
+ installing an addition file which for some reason was not installed
+ via the autotools normal <emphasis>install</emphasis> task:<screen>do_install_append() {
+ install -d ${D}${datadir}
+ install -m 0655 units.dat ${D}${datadir}
+}</screen></para>
+
+ <para>The following example from the cherokee recipe show an example
+ of adding functionality prior to the default
+ <emphasis>install</emphasis> task. In this case it compiles a
+ program that is used during installation natively so that it will
+ work on the host. Without this the autotools default
+ <emphasis>install</emphasis> task would fail since it'd try to run
+ the program on the host which was compiled for the target:<screen>do_install_prepend () {
+ # It only needs this app during the install, so compile it natively
+ $BUILD_CC -DHAVE_SYS_STAT_H -o cherokee_replace cherokee_replace.c
+}</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Defining a new task</term>
+
+ <listitem>
+ <para>Another option is define a totally new task, and then register
+ that with bitbake so that it runs in between two of the existing
+ tasks.</para>
+
+ <para>The following example shows a situation in which a cvs tree
+ needs to be copied over the top of an extracted tar.gz archive, and
+ this needs to be done before any local patches are applied. So a new
+ task is defined to perform this action, and then that task is
+ registered to run between the existing <emphasis>unpack</emphasis>
+ and <emphasis>patch</emphasis> tasks:<screen>do_unpack_extra(){
+ cp -pPR ${WORKDIR}/linux/* ${S}
+}
+addtask unpack_extra after do_unpack before do_patch</screen></para>
+
+ <note>
+ <para>The task to add does not have the do_ prepended to it,
+ however the tasks to insert it after and before do have the _do
+ prepended. No errors will be generated if this is wrong, the
+ additional task simple won't be executed.</para>
+ </note>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Using overrides</term>
+
+ <listitem>
+ <para>Overrides (described fully elsewhere) allow for various
+ functionality to be performed conditionally based on the target
+ machine, distribution, architecture etc.</para>
+
+ <para>While not commonly used it is possible to use overrides when
+ defining tasks. The following example from udev shows an additional
+ file being installed for the specified machine only by performing an
+ append to the <emphasis>install</emphasis> task for the h2200
+ machine only:<screen>do_install_append_h2200() {
+ install -m 0644 ${WORKDIR}/50-hostap_cs.rules ${D}${sysconfdir}/udev/rules.d/50-hostap_cs.rules
+}</screen></para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </section>
+
+ <section id="recipes_classes" xreflabel="classes">
+ <title>Classes: The separation of common functionality</title>
+
+ <para>Often a certain pattern is followed in more than one recipe, or
+ maybe some complex python based functionality is required to achieve the
+ desired end result. This is achieved through the use of classes, which can
+ be found in the classes subdirectory at the top-level of on OE
+ checkout.</para>
+
+ <para>Being aware of the available classes and understanding their
+ functionality is important because classes:</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>Save developers time being performing actions that they would
+ otherwise need to perform themselves;</para>
+ </listitem>
+
+ <listitem>
+ <para>Perform a lot of actions in the background making a lot of
+ recipes difficult to understand unless you are aware of classes and
+ how they work;</para>
+ </listitem>
+
+ <listitem>
+ <para>A lot of detail on how things work can be learnt for looking at
+ how classes are implement.</para>
+ </listitem>
+ </itemizedlist>
+
+ <para>A class is used via the inherit method. The following is an example
+ for the <emphasis>curl</emphasis> recipe showing that it uses three
+ classes:<screen>inherit autotools pkgconfig binconfig</screen>In this case
+ it is utilising the services of three separate classes:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>autotools</term>
+
+ <listitem>
+ <para>The <xref linkend="autotools_class" /> is used by programs
+ that use the GNU configuration tools and takes care of the
+ configuration and compilation of the software;</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>pkgconfig</term>
+
+ <listitem>
+ <para>The <xref linkend="pkgconfig_class" /> is used to stage the
+ <emphasis>.pc</emphasis> files which are used by the <emphasis
+ role="bold">pkg-config</emphasis> program to provide information
+ about the package to other software that wants to link to this
+ software;</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>binconfig</term>
+
+ <listitem>
+ <para>The <xref linkend="binconfig_class" /> is used to stage the
+ <emphasis>&lt;name&gt;-config</emphasis> files which are used to
+ provide information about the package to other software that wants
+ to link to this software;</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>Each class is implemented via the file in the <emphasis
+ role="bold">classes</emphasis> subdirectory named <emphasis
+ role="bold">&lt;classname&gt;.bbclass</emphasis> and these can be examined
+ for further details on a particular class, although sometimes it's not
+ easy to understand everything that's happening. Many of the classes are
+ covered in detail in various sections in this user manual.</para>
+ </section>
+
+ <section id="recipes_staging" xreflabel="staging">
+ <title>Staging: Making includes and libraries available for
+ building</title>
+
+ <para>Staging is the process of making files, such as include files and
+ libraries, available for use by other recipes. This is different to
+ installing because installing is about making things available for
+ packaging and then eventually for use on the target device. Staging on the
+ other hand is about making things available on the host system for use by
+ building later applications.</para>
+
+ <para>Taking bzip2 as an example you can see that it stages a header file
+ and it's library files:<screen>do_stage () {
+ install -m 0644 bzlib.h ${STAGING_INCDIR}/
+ oe_libinstall -a -so libbz2 ${STAGING_LIBDIR}
+}</screen></para>
+
+ <para>The <emphasis>oe_libinstall</emphasis> method used in the bzip2
+ recipe is described in the <xref linkend="recipes_methods" /> section, and
+ it takes care of installing libraries (into the staging area in this
+ case). The staging variables are automatically defined to the correct
+ staging location, in this case the main staging variables are used:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>STAGING_INCDIR</term>
+
+ <listitem>
+ <para>The directory into which staged headers files should be
+ installed. This is the equivalent of the standard <emphasis
+ role="bold">/usr/include</emphasis> directory.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>STAGING_LIBDIR</term>
+
+ <listitem>
+ <para>The directory into which staged library files should be
+ installed. This is the equivalent of the standard <emphasis
+ role="bold">/usr/lib</emphasis> directory.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>Additional staging related variables are covered in the <xref
+ linkend="directories_staging" /> section in <xref
+ linkend="chapter_reference" />.</para>
+
+ <para>Looking in the staging area under tmp you can see the result of the
+ bzip2 recipes staging task:<screen>%&gt; find tmp/staging -name '*bzlib*'
+tmp/staging/sh4-linux/include/bzlib.h
+%&gt; find tmp/staging -name '*libbz*'
+tmp/staging/sh4-linux/lib/libbz2.so
+tmp/staging/sh4-linux/lib/libbz2.so.1.0
+tmp/staging/sh4-linux/lib/libbz2.so.1
+tmp/staging/sh4-linux/lib/libbz2.so.1.0.2
+tmp/staging/sh4-linux/lib/libbz2.a</screen></para>
+
+ <para>As well as being used during the stage task the staging related
+ variables are used when building other packages. Looking at the gnupg
+ recipe we see two bzip2 related items:<screen>DEPENDS = "zlib <emphasis
+ role="bold">bzip2</emphasis>"
+...
+EXTRA_OECONF = "--disable-ldap \
+ --with-zlib=${STAGING_LIBDIR}/.. \
+ <emphasis role="bold">--with-bzip2=${STAGING_LIBDIR}/..</emphasis> \
+ --disable-selinux-support"
+</screen></para>
+
+ <para>Bzip2 is referred to in two places in the recipe:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>DEPENDS</term>
+
+ <listitem>
+ <para>Remember that <emphasis role="bold">DEPENDS</emphasis> defines
+ the list of build time dependencies. In this case the staged headers
+ and libraries from bzip2 are required to build gnupg, and therefore
+ we need to make sure the bzip2 recipe has run and staging the
+ headers and libraries. By adding the <emphasis
+ role="bold">DEPENDS</emphasis> on bzip2 this ensures that this
+ happens.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><emphasis role="bold">EXTRA_OECONF</emphasis></term>
+
+ <listitem>
+ <para>This variable is used by the <xref
+ linkend="autotools_class" /> to provide options to the configure
+ script of the package. In the gnupg case it needs to be told where
+ the bzip2 headers and libraries files are, and this is done via the
+ <emphasis>--with-bzip2</emphasis> option. In this case it needs to
+ the directory which include the lib and include subdirectories.
+ Since OE doesn't define a variable for one level above the include
+ and lib directories <emphasis role="bold">..</emphasis> is used to
+ indicate one directory up. Without this gnupg would search the host
+ system headers and libraries instead of those we have provided in
+ the staging area for the target.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>Remember that staging is used to make things, such as headers and
+ libraries, available to used by other recipes later on. While header and
+ libraries are the most common item requiring staging other items such as
+ the pkgconfig files need to be staged as well, while for native packages
+ the binaries also need to be staged.</para>
+ </section>
+
+ <section id="recipes_autoconf" xreflabel="about autoconf">
+ <title>Autoconf: All about autotools</title>
+
+ <para>This section is to be completed:</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>About building autoconf packages</para>
+ </listitem>
+
+ <listitem>
+ <para>EXTRA_OECONF</para>
+ </listitem>
+
+ <listitem>
+ <para>Problems with /usr/include, /usr/lib</para>
+ </listitem>
+
+ <listitem>
+ <para>Configuring to search in the staging area</para>
+ </listitem>
+
+ <listitem>
+ <para>-L${STAGING_LIBDIR} vs ${TARGET_LDFLAGS}</para>
+ </listitem>
+
+ <listitem>
+ <para>Site files</para>
+ </listitem>
+ </itemizedlist>
+ </section>
+
+ <section id="recipes_installation_scripts" xreflabel="installation scripts">
+ <title>Installation scripts: Running scripts during package install and/or
+ removal</title>
+
+ <para>Packaging system such as .ipkg and .deb support pre and post
+ installation and pre and post removal scripts which are run during package
+ install and/or package removal on the target system.</para>
+
+ <para>These scripts can be defined in your recipes to enable actions to be
+ performed at the appropriate time. Common uses include starting new
+ daemons on installation, stopping daemons during uninstall, creating new
+ user and/or group entries during install, registering and unregistering
+ alternative implementations of commands and registering the need for
+ volatiles.</para>
+
+ <para>The following scripts are supported:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>preinst</term>
+
+ <listitem>
+ <para>The preinst script is run prior to installing the contents of
+ the package. During preinst the contents of the package are not
+ available to be used as part of the script. The preinst scripts are
+ not commonly used.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>postinst</term>
+
+ <listitem>
+ <para>The postinst script is run after the installation of the
+ package has completed. During postinst the contents of the package
+ are available to be used. This is often used for the creation of
+ volatile directories, registration of daemons, starting of daemons
+ and fixing up of SUID binaries.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>prerm</term>
+
+ <listitem>
+ <para>The prerm is run prior to the removal of the contents of a
+ package. During prerm the contents of the package are still
+ available for use by the script. The prerm scripts</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>postrm</term>
+
+ <listitem>
+ <para>The postrm script is run after the completion of the removal
+ of the contents of a package. During postrm the contents of the
+ package no longer exist and therefore are not available for use by
+ the script. Postrm is most commonly used for update alternatives (to
+ tell the alternatives system that this alternative is not available
+ and another should be selected).</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>Scripts are registered by defining a function for:</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>pkg_&lt;scriptname&gt;_&lt;packagename&gt;</para>
+ </listitem>
+ </itemizedlist>
+
+ <para>The following example from ndisc6 shows postinst scripts being
+ registered for three of the packages that ndisc6 creates:<screen># Enable SUID bit for applications that need it
+pkg_postinst_${PN}-rltraceroute6 () {
+ chmod 4555 ${bindir}/rltraceroute6
+}
+pkg_postinst_${PN}-ndisc6 () {
+ chmod 4555 ${bindir}/ndisc6
+}
+pkg_postinst_${PN}-rdisc6 () {
+ chmod 4555 ${bindir}/rdisc6
+}</screen></para>
+
+ <note>
+ <para>These scripts will be run via <emphasis
+ role="bold">/bin/sh</emphasis> on the target device, which is typically
+ the busybox sh but could also be bash or some other sh compatible shell.
+ As always you should not use any bash extensions in your scripts and
+ stick to basic sh syntax.</para>
+ </note>
+
+ <para>Note that several classes will also register scripts, and that any
+ script you declare will have the script for the classes append to by these
+ classes. The following classes all generate additional script
+ contents:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>update-rc.d</term>
+
+ <listitem>
+ <para>This class is used by daemons to register there init scripts
+ with the init code.</para>
+
+ <para>Details are provided in the <xref
+ linkend="recipes_initscripts" /> section.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>module</term>
+
+ <listitem>
+ <para>This class is used by linux kernel modules. It's responsible
+ for calling depmod and update-modules during kernel module
+ installation and removal.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>kernel</term>
+
+ <listitem>
+ <para>This class is used by the linux kernel itself. There is a lot
+ of housekeeping required both when installing and removing a kernel
+ and this class is responsible for generating the required
+ scripts.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>qpf</term>
+
+ <listitem>
+ <para>This class is used when installing and/or removing qpf fonts.
+ It register scripts to update the font paths and font cache
+ information to ensure that the font information is kept up to date
+ as fonts and installed and removed.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>update-alternatives</term>
+
+ <listitem>
+ <para>This class is used by packages that contain binaries which may
+ also be available for other packages. It tells that system that
+ another alternative is available for consideration. The alternatives
+ system will create a symlink to the correct alternative from one or
+ more available on the system.</para>
+
+ <para>Details are provided in the <xref
+ linkend="recipes_alternatives" /> section.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>gtk-icon-cache</term>
+
+ <listitem>
+ <para>This class is used by packages that add new gtk icons. It's
+ responsible for updating the icon cache when packages are installed
+ and removed.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>gconf</term>
+
+ <listitem>
+ <para></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>package</term>
+
+ <listitem>
+ <para>The base class used by packaging classes such as those for
+ .ipkg and .deb. The package class may create scripts used to update
+ the dynamic linkers ld cache.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>The following example from p3scan shows and postinst script which
+ ensure that the required user and group entries exist, and registers the
+ need for volatiles (directories and/or files under <emphasis
+ role="bold">/var</emphasis>). In addition to explicitly declaring a
+ postinst script it uses the update-rc.d class which will result in an
+ additional entry being added to the postinst script to register the init
+ scripts and start the daemon (via call to update-rc.d as describes in the
+ <xref linkend="recipes_alternatives" /> section).<screen>inherit autotools update-rc.d
+
+...
+
+# Add havp's user and groups
+pkg_postinst_${PN} () {
+ grep -q mail: /etc/group || addgroup --system havp
+ grep -q mail: /etc/passwd || \
+ adduser --disabled-password --home=${localstatedir}/mail --system \
+ --ingroup mail --no-create-home -g "Mail" mail
+ /etc/init.d/populate-volatile.sh update
+}</screen></para>
+
+ <para>Several scripts in existing recipes will be of the following
+ form:<screen>if [ x"$D" = "x" ]; then
+ ...
+fi</screen></para>
+
+ <para>This is testing if the installation directory, <emphasis
+ role="bold">D</emphasis>, is defined and if it is no actions are
+ performed. The installation directory will not be defined under normal
+ circumstances. The primary use of this test is to permit the application
+ to be installed during root filesystem generation. In that situation the
+ scripts cannot be run since the root filesystem is generated on the host
+ system and not on the target. Any required script actions would need to be
+ performed via an alternative method if the package is to be installed in
+ the initial root filesystem (such as including any required users and
+ groups in the default <emphasis role="bold">passwd</emphasis> and
+ <emphasis role="bold">group</emphasis> files for example.)</para>
+ </section>
+
+ <section id="recipes_conffiles" xreflabel="conf files">
+ <title>Configuration files</title>
+
+ <para>Configuration files that are installed as part of a package require
+ special handling. Without special handling as soon as the user upgrades to
+ a new version of the package then changes they have made to the
+ configuration files will be lost.</para>
+
+ <para>In order to prevent this from happening you need to tell the
+ packaging system which files are configuration files. Such files will
+ result in the user being asked how the user wants to handle any
+ configuration file changes (if any), as shown in this example:<screen>Downloading http://nynaeve.twibble.org/ipkg-titan-glibc//./p3scan_2.9.05d-r1_sh4.ipk
+ Configuration file '/etc/p3scan/p3scan.conf'
+ ==&gt; File on system created by you or by a script.
+ ==&gt; File also in package provided by package maintainer.
+ What would you like to do about it ? Your options are:
+ Y or I : install the package maintainer's version
+ N or O : keep your currently-installed version
+ D : show the differences between the versions (if diff is installed)
+ The default action is to keep your current version.
+ *** p3scan.conf (Y/I/N/O/D) [default=N] ?</screen>To declare a file as a
+ configuration file you need to define the
+ <command>CONFFILES_&lt;pkgname&gt;</command> variable as a whitespace
+ separated list of configuration files. The following example from clamav
+ shows two files being marked as configuration files:<screen>CONFFILES_${PN}-daemon = "${sysconfdir}/clamd.conf \
+ ${sysconfdir}/default/clamav-daemon"</screen>Note
+ the user of <command>${PN}-daemon</command> as the package name. The
+ <command>${PN}</command> variable will expand to <command>clamav</command>
+ and therefore these conf files are declared as being in the clamav-daemon
+ package.</para>
+ </section>
+
+ <section id="recipes_package_relationships"
+ xreflabel="package relationships files">
+ <title>Package relationships</title>
+
+ <para>Explicit relationships between packages are support by packaging
+ formats such as ipkg and deb. These relationships include describing
+ conflicting packages and recommended packages.</para>
+
+ <para>The following variables control the package relationships in the
+ recipes:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>RRECOMMENDS</term>
+
+ <listitem>
+ <para>Used to specify other packages that are recommended to be
+ installed when this package is installed. Generally this means while
+ the recommended packages are not required they provide some sort of
+ functionality which users would usually want.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>RCONFLICTS</term>
+
+ <listitem>
+ <para>Used to specify other packages that conflict with this
+ package. Two packages that conflict cannot be installed at the same
+ time.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>RREPLACES</term>
+
+ <listitem>
+ <para>Used to specify that the current package replaces an older
+ package with a different name. During package installing the package
+ that is being replaced will be removed since it is no longer needed
+ when this package is installed.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>RSUGGESTS</term>
+
+ <listitem>
+ <para>Used to provide a list of suggested packages to install. These
+ are packages that are related to and useful for the current package
+ but which are not actually required to use the package.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>RPROVIDES</term>
+
+ <listitem>
+ <para>Used to explicitly specify what a package provides at runtime.
+ For example hotplug support is provided by several packages, such as
+ udev and linux-hotplug. Both declare that they runtime provide
+ "hotplug". So any packages that require "hotplug" to work simply
+ declare that it RDEPENDS on "hotplug". It's up to the distribution
+ to specify which actual implementation of "virtual/xserver" is
+ used.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>PROVIDES</term>
+
+ <listitem>
+ <para>Used to explicitly specify what a package provides at build
+ time. This is typically used when two or more packages can provide
+ the same functionality. For example there are several different X
+ servers in OpenEmbedded, and each as declared as providing
+ "virtual/xserver". Therefore a package that depends on an X server
+ to build can simply declare that it DEPENDS on "virtual/xserver".
+ It's up to the distribution to specify which actual implementation
+ of "virtual/xserver" is used.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </section>
+
+ <section id="recipes_fakeroot" xreflabel="fakeroot">
+ <title>Fakeroot: Dealing with the need for "root"</title>
+
+ <para>Sometimes packages requires root permissions in order to perform
+ some action, such as changing user or group owners or creating device
+ nodes. Since OpenEmbedded will not keep the user and group information
+ it's usually preferably to remove that from the makefiles. For device
+ nodes it's usually preferably to create them from the initial device node
+ lists or via udev configuration.</para>
+
+ <para>However if you can't get by without root permissions then you can
+ use <xref linkend="fakeroot" /> to simulate a root environment, without
+ the need to really give root access.</para>
+
+ <para>Using <xref linkend="fakeroot" /> is done by prefixing the
+ task:<screen>fakeroot do_install() {</screen>Since this requires fakeroot
+ you also need to add a dependency on
+ <command>fakeroot-native</command>:<screen>DEPENDS = "fakeroot-native"</screen>See
+ the fuse recipe for an example. Further information on <xref
+ linkend="fakeroot" />, including a description of it works, is provided in
+ the reference section: <xref linkend="fakeroot" />.</para>
+ </section>
+
+ <section id="recipes_native" xreflabel="native">
+ <title>Native: Packages for the build host</title>
+
+ <para>This section is to be completed.</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>What native packages are</para>
+ </listitem>
+
+ <listitem>
+ <para>Using require with the non-native package</para>
+ </listitem>
+ </itemizedlist>
+ </section>
+
+ <section id="recipes_development" xreflabel="development">
+ <title>Development: Strategies for developing recipes</title>
+
+ <para>This section is to be completed.</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>How to go about developing recipes</para>
+ </listitem>
+
+ <listitem>
+ <para>How do handle incrementally creating patches</para>
+ </listitem>
+
+ <listitem>
+ <para>How to deal with site file issues</para>
+ </listitem>
+
+ <listitem>
+ <para>Strategies for autotools issues</para>
+ </listitem>
+ </itemizedlist>
+ </section>
+
+ <section id="recipes_advanced_versioning" xreflabel="advanced versioning">
+ <title>Advanced versioning: How to deal with rc and pre versions</title>
+
+ <para>Special care needs to be taken when specify the version number for
+ rc and pre versions of packages.</para>
+
+ <para>Consider the case where we have an existing 1.5 version and there's
+ a new 1.6-rc1 release that you want to add.</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>1.5: Existing version;</para>
+ </listitem>
+
+ <listitem>
+ <para>1.6-rc1: New version.</para>
+ </listitem>
+ </itemizedlist>
+
+ <para>If the new package is given the version number 1.6-rc1 then
+ everything will work fine initially. However when the final release
+ happens it will be called 1.6. If you now create a 1.6 version of the
+ package you'll find that the packages are sorted into the following
+ order:</para>
+
+ <orderedlist>
+ <listitem>
+ <para>1.5</para>
+ </listitem>
+
+ <listitem>
+ <para>1.6</para>
+ </listitem>
+
+ <listitem>
+ <para>1.6-rc1</para>
+ </listitem>
+ </orderedlist>
+
+ <para>This in turn result in packaging system, such as ipkg, considering
+ the released version to be older then the rc version.</para>
+
+ <para>In OpenEmbedded the correct naming of pre and rc versions is to use
+ the previous version number followed by a + followed by the new version
+ number. So the 1.6-rc1 release would be given the version number:</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>1.5+1.6-rc1</para>
+ </listitem>
+ </itemizedlist>
+
+ <para>These would result in the eventually ordering being:</para>
+
+ <orderedlist>
+ <listitem>
+ <para>1.5</para>
+ </listitem>
+
+ <listitem>
+ <para>1.5+1.6-rc1</para>
+ </listitem>
+
+ <listitem>
+ <para>1.6</para>
+ </listitem>
+ </orderedlist>
+
+ <para>This is the correct order and the packaging system will now work as
+ expected.</para>
+ </section>
+
+ <section id="recipes_require" xreflabel="require">
+ <title>Require/include: Reusing recipe contents</title>
+
+ <para>In many packages where you are maintaining multiple versions you'll
+ often end up with several recipes which are either identical, or have only
+ minor differences between them.</para>
+
+ <para>The require and/or include directive can be used to include common
+ content from one file into other. You should always look for a way to
+ factor out common functionality into an include file when adding new
+ versions of a recipe.</para>
+
+ <note>
+ <para>Both require and include perform the same function - including the
+ contents of another file into this recipe. The difference is that
+ require will generate an error if the file is not found while include
+ will not. For this reason include should not be used in new
+ recipes.</para>
+ </note>
+
+ <para>For example the clamav recipe looks like this:<screen>require clamav.inc
+
+PR = "r0"</screen>Note that all of the functionality of the recipe is provided
+ in the clamav.inc file, only the release number is defined in the recipe.
+ Each of the recipes includes the same <emphasis
+ role="bold">clamav.inc</emphasis> file to save having to duplicate any
+ functionality. This also means that as new versions are released it's a
+ simple matter of copying the recipe and resetting the release number back
+ to zero.</para>
+
+ <para>The following example from iproute2 shows the recipe adding
+ additional patches that are not specified by the common included file.
+ These are patches only needed for newer release and by only adding them in
+ this recipe it permits the common code to be used for both old and new
+ recipes:<screen>PR = "r1"
+
+SRC_URI += "file://iproute2-2.6.15_no_strip.diff;patch=1;pnum=0 \
+ file://new-flex-fix.patch;patch=1"
+
+require iproute2.inc
+
+DATE = "060323"</screen></para>
+
+ <para>The following example from cherokee shows a similar method of
+ including additional patches for this version only. However it also show
+ another technique in which the configure task is defined in the recipe for
+ this version, thus replacing the <emphasis>configure</emphasis> task that
+ is provided by the common include:<screen>PR = "r7"
+
+SRC_URI_append = "file://configure.patch;patch=1 \
+ file://Makefile.in.patch;patch=1 \
+ file://Makefile.cget.patch;patch=1 \
+ file://util.patch;patch=1"
+
+require cherokee.inc
+
+do_configure() {
+ gnu-configize
+ oe_runconf
+ sed -i 's:-L\$:-L${STAGING_LIBDIR} -L\$:' ${S}/*libtool
+}</screen></para>
+ </section>
+
+ <section id="recipes_advanced_python" xreflabel="advanced python">
+ <title>Python: Advanced functionality with python</title>
+
+ <para>Recipes permit the use of python code in order to perform complex
+ operations which are not possible with the normal recipe syntax and
+ variables. Python can be used in both variable assignments and in the
+ implementation of tasks.</para>
+
+ <para>For variable assignments python code is indicated via the use of
+ <emphasis>${@...}</emphasis>, as shown in the following example:<screen>TAG = ${@bb.data.getVar('PV',d,1).replace('.', '_')}</screen></para>
+
+ <para>The above example retrieves the PV variable from the bitbake data
+ object, the replaces any dots with underscores. Therefore if the <emphasis
+ role="bold">PV</emphasis> was <emphasis role="bold">0.9.0</emphasis> then
+ <emphasis role="bold">TAG</emphasis> will be set to <emphasis
+ role="bold">0-9-0</emphasis>.</para>
+
+ <para>Some of the more common python code in use in existing recipes is
+ shown in the following table:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>bb.data.getVar(&lt;var&gt;,d,1)</term>
+
+ <listitem>
+ <para>Retrieve the data for the specified variable from the bitbake
+ database for the current recipe.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>&lt;variable&gt;.replace(&lt;key&gt;,
+ &lt;replacement&gt;)</term>
+
+ <listitem>
+ <para>Find each instance of the key and replace it with the
+ replacement value. This can also be used to remove part of a string
+ by specifying <emphasis role="bold">''</emphasis> (two single
+ quotes) as the replacement.</para>
+
+ <para>The following example would remove the <emphasis
+ role="bold">'-frename-registers'</emphasis> option from the
+ <emphasis role="bold">CFLAGS</emphasis> variable:<screen>CFLAGS := "${@'${CFLAGS}'.replace('-frename-registers', '')}"</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>os.path.dirname(&lt;filename&gt;)</term>
+
+ <listitem>
+ <para>Return the directory only part of a filename.</para>
+
+ <para>This is most commonly seen in existing recipes when settings
+ the <emphasis role="bold">FILESDIR</emphasis> variable (as described
+ in the <xref linkend="recipes_filespath_dir" /> section). By
+ obtaining name of the recipe file itself, <emphasis
+ role="bold">FILE</emphasis>, and then using os.path.dirname to strip
+ the filename part:<screen>FILESDIR = "${@os.path.dirname(bb.data.getVar('FILE',d,1))}/make-${PV}"</screen>Note
+ however that this is no longer required as <emphasis
+ role="bold">FILE_DIRNAME</emphasis> is automatically set to the
+ dirname of the <emphasis role="bold">FILE</emphasis> variable and
+ therefore this would be written in new recipes as:<screen>FILESDIR = "$FILE_DIRNAME/make-${PV}"</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>&lt;variable&gt;.split(&lt;key&gt;)[&lt;index&gt;]</term>
+
+ <listitem>
+ <para>Splits are variable around the specified key. Use <emphasis
+ role="bold">[&lt;index&gt;]</emphasis> to select one of the matching
+ items from the array generated by the split command.</para>
+
+ <para>The following example from the recipe g<emphasis
+ role="bold">enext2fs_1.3+1.4rc1.bb</emphasis> would take the
+ <emphasis role="bold">PV</emphasis> of <emphasis
+ role="bold">1.3+1.4rc1</emphasis> and split it around the <emphasis
+ role="bold">+</emphasis> sign, resulting in an array containing
+ <emphasis role="bold">1.3</emphasis> and <emphasis
+ role="bold">1.4rc1</emphasis>. It then uses the index of <emphasis
+ role="bold">[1]</emphasis> to select the second item from the list
+ (the first item is at index <emphasis role="bold">0</emphasis>).
+ Therefore <emphasis role="bold">TRIMMEDV</emphasis> would be set to
+ <emphasis role="bold">1.4rc1</emphasis> for this recipe:</para>
+
+ <screen>TRIMMEDV = "${@bb.data.getVar('PV', d, 1).split('+')[1]}"</screen>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>As well as directly calling built-in python functions, those
+ functions defined by the existing classes may also be called. A set of
+ common functions is provided by the base class in <emphasis
+ role="bold">classes/base.bbclass</emphasis>:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>base_conditional</term>
+
+ <listitem>
+ <para>This functions is used to set a variable to one of two values
+ based on the definition of a third variable. The general usage
+ is:<screen>${@base_conditional('&lt;variable-name&gt;', '&lt;value&gt;', '&lt;true-result&gt;', &lt;false-result&gt;', d)}"</screen>where:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term>variable-name</term>
+
+ <listitem>
+ <para>This is the name of a variable to check.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>value</term>
+
+ <listitem>
+ <para>This is the value to compare the variable
+ against.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>true-result</term>
+
+ <listitem>
+ <para>If the variable equals the value then this is what is
+ returned by the function.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>false-result</term>
+
+ <listitem>
+ <para>If the variable does not equal the value then this is
+ what is returned by the function.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>The following example from the openssl recipe shows the
+ addition of either <emphasis role="bold">-DL_ENDING</emphasis> or
+ <emphasis role="bold">-DB_ENDIAN</emphasis> depending on the value
+ of <emphasis role="bold">SITEINFO_ENDIANESS</emphasis> which is set
+ to le for little endian targets and to be for big endian
+ targets:<screen>do_compile () {
+ ...
+ # Additional flag based on target endiness (see siteinfo.bbclass)
+ CFLAG="${CFLAG} ${@base_conditional('SITEINFO_ENDIANESS', 'le', '-DL_ENDIAN', '-DB_ENDIAN', d)}"
+ ...</screen></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>base_contains</term>
+
+ <listitem>
+ <para>Similar to base_conditional expect that it is checking for the
+ value being an element of an array. The general usage is:<screen>${@base_contains('&lt;array-name&gt;', '&lt;value&gt;', '&lt;true-result&gt;', &lt;false-result&gt;', d)}"</screen></para>
+
+ <para>where:<variablelist>
+ <varlistentry>
+ <term>array-name</term>
+
+ <listitem>
+ <para>This is the name of the array to search.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>value</term>
+
+ <listitem>
+ <para>This is the value to check for in the array.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>true-result</term>
+
+ <listitem>
+ <para>If the value is found in the array then this is what
+ is returned by the function.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>false-result</term>
+
+ <listitem>
+ <para>If the value is not found in the array then this is
+ what is returned by the function.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>The following example from the task-angstrom-x11
+ recipe shows base_contains being used to add a recipe to the runtime
+ dependency list but only for machines which have a
+ touchscreen:</para>
+
+ <screen>RDEPENDS_angstrom-gpe-task-base := "\
+ ...
+ ${@base_contains("MACHINE_FEATURES", "touchscreen", "libgtkstylus", "",d)} \
+ ...</screen>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>Tasks may be implemented in python by prefixing the task function
+ with "python ". In general this should not be needed and should be avoided
+ where possible. The following example from the devshell recipe shows how
+ the compile task is implemented python:<screen>python do_compile() {
+ import os
+ import os.path
+
+ workdir = bb.data.getVar('WORKDIR', d, 1)
+ shellfile = os.path.join(workdir, bb.data.expand("${TARGET_PREFIX}${DISTRO}-${MACHINE}-devshell", d))
+
+ f = open(shellfile, "w")
+
+ # emit variables and shell functions
+ devshell_emit_env(f, d, False, ["die", "oe", "autotools_do_configure"])
+
+ f.close()
+}</screen></para>
+ </section>
+
+ <section id="recipes_defaultpreference" xreflabel="default preference">
+ <title>Preferences: How to disable packages</title>
+
+ <para>When bitbake is asked to build a package and multiple versions of
+ that package are available then bitbake will normally select the version
+ that has the highest version number (where the version number is defined
+ via the <command>PV</command> variable).</para>
+
+ <para>For example if we were to ask bitbake to build procps and the
+ following packages are available:<screen>~/oe%&gt; ls packages/procps
+procps-3.1.15/ procps-3.2.1/ procps-3.2.5/ procps-3.2.7/ procps.inc
+procps_3.1.15.bb procps_3.2.1.bb procps_3.2.5.bb procps_3.2.7.bb
+~/oe%&gt;</screen>then we would expect it to select version
+ <command>3.2.7</command> (the highest version number) to build.</para>
+
+ <para>Sometimes this is not actually what you want to happen though.
+ Perhaps you have added a new version of the package that does not yet work
+ or maybe the new version has no support for your target yet. Help is at
+ hand since bitbake is not only looking at the version numbers to decided
+ which version to build but it is also looking at the preference for each
+ of those version. The preference is defined via the
+ <command>DEFAULT_PREFERENCE</command> variable contained within the
+ recipe.</para>
+
+ <para>The default preference (when no
+ <command>DEFAULT_PREFERENCE</command> is specified) is zero. Bitbake will
+ find the highest preference that is available and then for all the
+ packages at the preference level it will select the package with the
+ highest version. In general this means that adding a positive
+ <command>DEFAULT_PREFERENCE</command> will cause the package to be
+ preferred over other versions and a negative
+ <command>DEFAULT_PREFERENCE</command> will cause all other packages to be
+ preferred.</para>
+
+ <para>Imagine that you are adding procps version 4.0.0, but that it does
+ not yet work. You could delete or rename your new recipe so you can build
+ a working image, but what you really to do is just ignore the new 4.0.0
+ version until it works. By adding:<screen>DEFAULT_PREFERENCE = "-1"</screen>to
+ the recipe this is what will happen. Bitbake will now ignore this version
+ (since all of the existing versions have a preference of 0). Note that you
+ can still call bitbake directly on the recipe:<screen>bitbake -b packages/procps/procps_4.0.0.bb</screen>This
+ enables you to test, and fix the package manually without having bitbake
+ automatically select normally.</para>
+
+ <para>By using this feature in conjunction with overrides you can also
+ disable (or select) specific versions based on the override. The following
+ example from glibc shows that this version has been disabled for the sh3
+ architecture because it doesn't support sh3. This will force bitbake to
+ try and select one of the other available versions of glibc
+ instead:<screen>packages/glibc/glibc_2.3.2+cvs20040726.bb:DEFAULT_PREFERENCE_sh3 = "-99"</screen></para>
+ </section>
+
+ <section id="recipes_initscripts" xreflabel="initscripts">
+ <title>Initscripts: How to handle daemons</title>
+
+ <para>This section is to be completed.</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>update-rc.d class</para>
+ </listitem>
+
+ <listitem>
+ <para>sh syntax</para>
+ </listitem>
+
+ <listitem>
+ <para>stop/stop/restart params</para>
+ </listitem>
+
+ <listitem>
+ <para>samlpe/standard script?</para>
+ </listitem>
+
+ <listitem>
+ <para>volatiles</para>
+ </listitem>
+ </itemizedlist>
+ </section>
+
+ <section id="recipes_alternatives" xreflabel="alternatives">
+ <title>Alternatives: How to handle the same command in multiple
+ packages</title>
+
+ <para>Alternatives are used when the same command is provided by multiple
+ packages. A classic example is busybox, which provides a whole set of
+ commands such as <emphasis role="bold">/bin/ls</emphasis> and <emphasis
+ role="bold">/bin/find</emphasis>, which are also provided by other
+ packages such as coreutils (<emphasis role="bold">/bin/ls</emphasis>) and
+ findutils (<emphasis role="bold">/bin/find</emphasis>).</para>
+
+ <para>A system for handling alternatives is required to allow the user to
+ choose which version of the command they wish to have installed. It should
+ be possible to install either one, or both, or remove one when both are
+ installed etc, and to have no issues with the packages overwriting files
+ from other packages.</para>
+
+ <para>The most common reason for alternatives is to reduce the size of the
+ binaries. But cutting down on features, built in help and error messages
+ and combining multiple binaries into one large binary it's possible to
+ save considerable space. Often users are not expected to use the commands
+ interactively in embedded appliances and therefore these changes have no
+ visible effect to the user. In some situations users may have interactive
+ access, or they may be more advanced users who want shell access on
+ appliances that normal don't provide it, and in these cases they should be
+ able to install the full functional version if they desire.</para>
+
+ <section>
+ <title>Example of alternative commands</title>
+
+ <para>Most distributions include busybox in place of the full featured
+ version of the commands. The following example shows a typical install
+ in which the find command, which we'll use as an example here, is the
+ busybox version:<screen>root@titan:~$ find --version
+find --version
+BusyBox v1.2.1 (2006.12.17-05:10+0000) multi-call binary
+
+Usage: find [PATH...] [EXPRESSION]
+
+root@titan:~$ which find
+which find
+/usr/bin/find</screen>If we now install the full version of find:<screen>root@titan:~$ ipkg install findutils
+ipkg install findutils
+Installing findutils (4.2.29-r0) to root...
+Downloading http://nynaeve.twibble.org/ipkg-titan-glibc//./findutils_4.2.29-r0_sh4.ipk
+Configuring findutils
+
+update-alternatives: Linking //usr/bin/find to find.findutils
+update-alternatives: Linking //usr/bin/xargs to xargs.findutils</screen></para>
+
+ <para>Then we see that the standard version of find changes to the full
+ featured implement ion:<screen>root@titan:~$ find --version
+find --version
+GNU find version 4.2.29
+Features enabled: D_TYPE O_NOFOLLOW(enabled) LEAF_OPTIMISATION
+root@titan:~$ which find
+which find
+/usr/bin/find</screen></para>
+ </section>
+
+ <section>
+ <title>Using update-alternatives</title>
+
+ <para>Two methods of using the alternatives system are available:</para>
+
+ <orderedlist>
+ <listitem>
+ <para>Via the <xref linkend="update-alternatives_class" />. This is
+ the simplest method, but is not usable in all situations.</para>
+ </listitem>
+
+ <listitem>
+ <para>Via directly calling the update-alternatives command.</para>
+ </listitem>
+ </orderedlist>
+
+ <para>The <xref linkend="update-alternatives_class" /> is the provides
+ the simplest method of using alternatives but it only works for a single
+ alternative. For multiple alternatives they need to be manually
+ registered during post install.</para>
+
+ <para>Full details on both methods is provided in the <xref
+ linkend="update-alternatives_class" /> section of the reference
+ manual.</para>
+ </section>
+ </section>
+
+ <section id="recipes_volatiles" xreflabel="volatiles">
+ <title>Volatiles: How to handle the /var directory</title>
+
+ <para>The <emphasis role="bold">/var</emphasis> directory is for storing
+ volatile information, that is information which is constantly changing and
+ which in general may be easily recreated. In embedded applications it is
+ often desirable that such files are not stored on disk or flash for
+ various reasons including:</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>The possibility of a reduced lifetime of the flash;</para>
+ </listitem>
+
+ <listitem>
+ <para>The limited amount of storage space available;</para>
+ </listitem>
+
+ <listitem>
+ <para>To ensure filesystem corruption cannot occur due to a sudden
+ power loss.</para>
+ </listitem>
+ </itemizedlist>
+
+ <para>For these reasons many of the OpenEmbedded distributions use a tmpfs
+ based memory filesystem for <emphasis role="bold">/var</emphasis> instead
+ of using a disk or flash based filesystem. The consequence of this is that
+ all contents of the <emphasis role="bold">/var</emphasis> directory is
+ lost when the device is powered off or restarted. Therefore special
+ handling of <emphasis role="bold">/var</emphasis> is required in all
+ packages. Even if your distrubution does not use a tmpfs based <emphasis
+ role="bold">/var</emphasis> you need to assume it does when creating
+ packages to ensure the package can be used on those distributions that do
+ use a tmpfs based <emphasis role="bold">/var</emphasis>. This special
+ handling is provided via the <emphasis
+ role="bold">populate-volatiles.sh</emphasis> script.</para>
+
+ <note>
+ <para>If your package requires any files, directories or symlinks in
+ <emphasis role="bold">/var</emphasis> then it should be using the
+ populate-volatiles facilities.</para>
+ </note>
+
+ <section>
+ <title>Declaring volatiles</title>
+
+ <para>This section is to be completed.</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>how volatiles work</para>
+ </listitem>
+
+ <listitem>
+ <para>default volatiles</para>
+ </listitem>
+
+ <listitem>
+ <para>don't include any /var stuff in packages</para>
+ </listitem>
+
+ <listitem>
+ <para>even if your distro don't use /var in tmpfs, others do</para>
+ </listitem>
+
+ <listitem>
+ <para>updating the volatiles cache during install</para>
+ </listitem>
+ </itemizedlist>
+ </section>
+
+ <section>
+ <title>Logging and log files</title>
+
+ <para>As a consequence of the non-volatile and/or small capacity of the
+ <emphasis role="bold">/var</emphasis> file system some distributions
+ choose methods of logging other than writing to a file. The most typical
+ is the use of an in-memory circular log buffer which can be read using
+ the <emphasis role="bold">logread</emphasis> command.</para>
+
+ <para>To ensure that each distribution is able to implement logging in a
+ method that is suitable for its goals all packages should be configured
+ by default to log via syslog, and not log directly to a file, if
+ possible. If the distribution and/or end-user requires logging to a file
+ then they can configured syslog and/or your application to implement
+ this.</para>
+ </section>
+
+ <section>
+ <title>Summary</title>
+
+ <para>In summary the following are required when dealing with
+ <command>/var</command>:</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>Configure all logging to use syslog whenever possible. This
+ leaves the decision on where to log upto the individual
+ distributions.</para>
+ </listitem>
+
+ <listitem>
+ <para>Don't include any <command>/var</command> directories, file or
+ symlinks in packages. They would be lost on a reboot and so should
+ not be included in packages.</para>
+ </listitem>
+
+ <listitem>
+ <para>The only directories that you can assume exist are those
+ listed in the default volatiles file:
+ <command>packages/initscripts/initscripts-1.0/volatiles</command>.</para>
+ </listitem>
+
+ <listitem>
+ <para>For any other directories, files or links that are required in
+ <command>/var</command> you should install your own volatiles list
+ as part of the package.</para>
+ </listitem>
+ </itemizedlist>
+ </section>
+ </section>
+
+ <section id="recipes_misc">
+ <title>Miscellaneous</title>
+
+ <para>This section is to be completed.</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>about optimisation</para>
+ </listitem>
+
+ <listitem>
+ <para>about download directories</para>
+ </listitem>
+
+ <listitem>
+ <para>about parallel builds</para>
+ </listitem>
+
+ <listitem>
+ <para>about determining endianess (aka net-snmp, openssl, hping etc
+ style)</para>
+ </listitem>
+
+ <listitem>
+ <para>about PACKAGES_DYNAMIC</para>
+ </listitem>
+
+ <listitem>
+ <para>about LEAD_SONAME</para>
+ </listitem>
+
+ <listitem>
+ <para>about "python () {" - looks like it is always run when a recipe
+ is parsed? see pam/libpam</para>
+ </listitem>
+
+ <listitem>
+ <para>about SRCDATE with svn/cvs?</para>
+ </listitem>
+
+ <listitem>
+ <para>about INHIBIT_DEFAULT_DEPS?</para>
+ </listitem>
+
+ <listitem>
+ <para>about COMPATIBLE_MACHINE and COMPATIBLE_HOST</para>
+ </listitem>
+
+ <listitem>
+ <para>about SUID binaries, and the need for postinst to fix them
+ up</para>
+ </listitem>
+
+ <listitem>
+ <para>about passwd and group (some comment in install scripts section
+ already).</para>
+ </listitem>
+ </itemizedlist>
+
+ <para></para>
+ </section>
+</chapter> \ No newline at end of file