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Creation involved removing the overview-manual and replacing it with the getting-started manual. All links to the string "&YOCTO_DOCS_OVERVIEW_URL" had to be replaced with "&YOCTO_DOCS_GS_URL" across the entire YP manual set. I renamed files used to create the manual with prefixes suited for the new manual name, which is "Getting Started With Yocto Project". The style sheet for the new manual needed updating to display the new .PNG image for the title page. The mega-manual file had to be updated to include the files. The mega-manual.sed file had to be updated to include the new manual and not use the overview manual. (From yocto-docs rev: 6c7abf9192390121000f577d6c98f259d290d15d) Signed-off-by: Scott Rifenbark <srifenbark@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
165 lines
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165 lines
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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<title>3.4. Automatically Added Runtime Dependencies</title>
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<meta name="generator" content="DocBook XSL Stylesheets V1.76.1">
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<link rel="home" href="index.html" title="Getting Started With Yocto Project">
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<link rel="up" href="overview-concepts.html" title="Chapter 3. Yocto Project Concepts">
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<link rel="prev" href="invalidating-shared-state.html" title="3.3.4.2. Invalidating Shared State">
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<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="section" title="3.4. Automatically Added Runtime Dependencies">
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<div class="titlepage"><div><div><h2 class="title" style="clear: both">
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<a name="automatically-added-runtime-dependencies"></a>3.4. Automatically Added Runtime Dependencies</h2></div></div></div>
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<p>
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The OpenEmbedded build system automatically adds common types of
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runtime dependencies between packages, which means that you do not
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need to explicitly declare the packages using
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<a class="link" href="../ref-manual/var-RDEPENDS.html" target="_self"><code class="filename">RDEPENDS</code></a>.
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Three automatic mechanisms exist (<code class="filename">shlibdeps</code>,
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<code class="filename">pcdeps</code>, and <code class="filename">depchains</code>)
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that handle shared libraries, package configuration (pkg-config)
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modules, and <code class="filename">-dev</code> and
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<code class="filename">-dbg</code> packages, respectively.
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For other types of runtime dependencies, you must manually declare
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the dependencies.
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</p>
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<div class="itemizedlist"><ul class="itemizedlist" type="disc">
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<li class="listitem">
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<p>
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<code class="filename">shlibdeps</code>:
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During the
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<a class="link" href="../ref-manual/ref-tasks-package.html" target="_self"><code class="filename">do_package</code></a>
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task of each recipe, all shared libraries installed by the
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recipe are located.
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For each shared library, the package that contains the
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shared library is registered as providing the shared
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library.
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More specifically, the package is registered as providing
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the
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<a class="ulink" href="https://en.wikipedia.org/wiki/Soname" target="_self">soname</a>
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of the library.
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The resulting shared-library-to-package mapping
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is saved globally in
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<a class="link" href="../ref-manual/var-PKGDATA_DIR.html" target="_self"><code class="filename">PKGDATA_DIR</code></a>
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by the
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<a class="link" href="../ref-manual/ref-tasks-packagedata.html" target="_self"><code class="filename">do_packagedata</code></a>
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task.</p>
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<p>Simultaneously, all executables and shared libraries
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installed by the recipe are inspected to see what shared
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libraries they link against.
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For each shared library dependency that is found,
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<code class="filename">PKGDATA_DIR</code> is queried to
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see if some package (likely from a different recipe)
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contains the shared library.
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If such a package is found, a runtime dependency is added
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from the package that depends on the shared library to the
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package that contains the library.</p>
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<p>The automatically added runtime dependency also
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includes a version restriction.
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This version restriction specifies that at least the
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current version of the package that provides the shared
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library must be used, as if
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"<em class="replaceable"><code>package</code></em> (>= <em class="replaceable"><code>version</code></em>)"
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had been added to
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<a class="link" href="../ref-manual/var-RDEPENDS.html" target="_self"><code class="filename">RDEPENDS</code></a>.
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This forces an upgrade of the package containing the shared
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library when installing the package that depends on the
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library, if needed.</p>
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<p>If you want to avoid a package being registered as
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providing a particular shared library (e.g. because the library
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is for internal use only), then add the library to
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<a class="link" href="../ref-manual/var-PRIVATE_LIBS.html" target="_self"><code class="filename">PRIVATE_LIBS</code></a>
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inside the package's recipe.
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</p>
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</li>
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<li class="listitem">
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<p>
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<code class="filename">pcdeps</code>:
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During the
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<a class="link" href="../ref-manual/ref-tasks-package.html" target="_self"><code class="filename">do_package</code></a>
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task of each recipe, all pkg-config modules
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(<code class="filename">*.pc</code> files) installed by the recipe
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are located.
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For each module, the package that contains the module is
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registered as providing the module.
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The resulting module-to-package mapping is saved globally in
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<a class="link" href="../ref-manual/var-PKGDATA_DIR.html" target="_self"><code class="filename">PKGDATA_DIR</code></a>
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by the
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<a class="link" href="../ref-manual/ref-tasks-packagedata.html" target="_self"><code class="filename">do_packagedata</code></a>
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task.</p>
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<p>Simultaneously, all pkg-config modules installed by
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the recipe are inspected to see what other pkg-config
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modules they depend on.
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A module is seen as depending on another module if it
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contains a "Requires:" line that specifies the other module.
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For each module dependency,
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<code class="filename">PKGDATA_DIR</code> is queried to see if some
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package contains the module.
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If such a package is found, a runtime dependency is added
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from the package that depends on the module to the package
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that contains the module.
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</p>
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<div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;">
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<h3 class="title">Note</h3>
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The <code class="filename">pcdeps</code> mechanism most often
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infers dependencies between <code class="filename">-dev</code>
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packages.
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</div>
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<p>
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</p>
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</li>
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<li class="listitem">
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<p>
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<code class="filename">depchains</code>:
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If a package <code class="filename">foo</code> depends on a package
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<code class="filename">bar</code>, then <code class="filename">foo-dev</code>
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and <code class="filename">foo-dbg</code> are also made to depend on
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<code class="filename">bar-dev</code> and
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<code class="filename">bar-dbg</code>, respectively.
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Taking the <code class="filename">-dev</code> packages as an
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example, the <code class="filename">bar-dev</code> package might
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provide headers and shared library symlinks needed by
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<code class="filename">foo-dev</code>, which shows the need
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for a dependency between the packages.</p>
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<p>The dependencies added by
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<code class="filename">depchains</code> are in the form of
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<a class="link" href="../ref-manual/var-RRECOMMENDS.html" target="_self"><code class="filename">RRECOMMENDS</code></a>.
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</p>
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<div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;">
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<h3 class="title">Note</h3>
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By default, <code class="filename">foo-dev</code> also has an
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<code class="filename">RDEPENDS</code>-style dependency on
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<code class="filename">foo</code>, because the default value of
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<code class="filename">RDEPENDS_${PN}-dev</code> (set in
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<code class="filename">bitbake.conf</code>) includes
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"${PN}".
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</div>
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<p>To ensure that the dependency chain is never broken,
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<code class="filename">-dev</code> and <code class="filename">-dbg</code>
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packages are always generated by default, even if the
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packages turn out to be empty.
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See the
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<a class="link" href="../ref-manual/var-ALLOW_EMPTY.html" target="_self"><code class="filename">ALLOW_EMPTY</code></a>
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variable for more information.
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</p>
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</li>
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</ul></div>
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<p>
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</p>
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<p>
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The <code class="filename">do_package</code> task depends on the
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<a class="link" href="../ref-manual/ref-tasks-packagedata.html" target="_self"><code class="filename">do_packagedata</code></a>
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task of each recipe in
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<a class="link" href="../ref-manual/var-DEPENDS.html" target="_self"><code class="filename">DEPENDS</code></a>
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through use of a
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<code class="filename">[</code><a class="link" href="../bitbake-user-manual/variable-flags.html" target="_self"><code class="filename">deptask</code></a><code class="filename">]</code>
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declaration, which guarantees that the required
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shared-library/module-to-package mapping information will be available
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when needed as long as <code class="filename">DEPENDS</code> has been
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correctly set.
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</p>
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</div></body>
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</html>
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