ref-manual: New section and updates for runtime dep work

fixes [YOCTO #10248]

The bulk of this change is a new section called "Automatically
Added Runtime Dependencies".  Additionally, changes were made
to the RDEPENDS and DEPENDS variables. Some cross-referencing
to the new material was also added in the do_package task entry,
the do_packagedata task entry, the PKGDATA_DIR glossary entry,
and the PRIVATE_LIBS glossary entry.

(From yocto-docs rev: 16504cd0eb23e102322c6c6096c5b52500a04640)

Signed-off-by: Scott Rifenbark <srifenbark@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
This commit is contained in:
Scott Rifenbark 2016-09-13 11:15:02 -07:00 committed by Richard Purdie
parent 899ea9cb48
commit 8bc6c1c2c8
3 changed files with 196 additions and 70 deletions

View File

@ -334,6 +334,17 @@
<link linkend='var-FILES'><filename>FILES</filename></link>
variables.
</para>
<para>
The <filename>do_package</filename> task, in conjunction with the
<link linkend='ref-tasks-packagedata'><filename>do_packagedata</filename></link>
task, also saves some important package metadata.
For additional information, see the
<link linkend='var-PKGDESTWORK'><filename>PKGDESTWORK</filename></link>
variable and the
"<link linkend='automatically-added-runtime-dependencies'>Automatically Added Runtime Dependencies</link>"
section.
</para>
</section>
<section id='ref-tasks-package_qa'>
@ -408,6 +419,8 @@
<para>
Creates package metadata used by the build system to generate the
final packages.
The data is saved in
<link linkend='var-PKGDATA_DIR'><filename>PKGDATA_DIR</filename></link>.
</para>
</section>

View File

@ -2833,9 +2833,9 @@
add any runtime dependencies between the
packages produced by the two recipes.
However, as explained in the
<link linkend='var-RDEPENDS'><filename>RDEPENDS</filename></link>
glossary entry, runtime dependencies will often
be added automatically, meaning
"<link linkend='automatically-added-runtime-dependencies'>Automatically Added Runtime Dependencies</link>"
section, runtime dependencies will often be
added automatically, meaning
<filename>DEPENDS</filename> alone is
sufficient for most recipes.
</para></listitem>
@ -9651,14 +9651,16 @@ recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
<link linkend='ref-tasks-packagedata'><filename>do_packagedata</filename></link>
task packages data for each recipe and installs it into
this temporary, shared area.
This directory defaults to the following:
This directory defaults to the following, which you should
not change:
<literallayout class='monospaced'>
${STAGING_DIR_HOST}/pkgdata
</literallayout>
</para>
<para>
Do not change this default.
For examples of how this data is used, see the
"<link linkend='automatically-added-runtime-dependencies'>Automatically Added Runtime Dependencies</link>"
section and the
"<link linkend='viewing-package-information-with-oe-pkgdata-util'>Viewing Package Information with <filename>oe-pkgdata-util</filename></link>"
section.
</para>
</glossdef>
</glossentry>
@ -10133,6 +10135,12 @@ recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
libplds4.so"
</literallayout>
</para>
<para>
For more information, see the
"<link linkend='automatically-added-runtime-dependencies'>Automatically Added Runtime Dependencies</link>"
section.
</para>
</glossdef>
</glossentry>
@ -10427,40 +10435,60 @@ recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
<glossentry id='var-RDEPENDS'><glossterm>RDEPENDS</glossterm>
<info>
RDEPENDS[doc] = "Lists a package's runtime dependencies (i.e. other packages) that must be installed for the package to be built. They must be the names of other packages as listed in the PACKAGES variable, not recipe names (PN)."
RDEPENDS[doc] = "Lists runtime dependencies of a package."
</info>
<glossdef>
<para role="glossdeffirst">
<!-- <para role="glossdeffirst"><imagedata fileref="figures/define-generic.png" /> -->
Lists a package's runtime dependencies (i.e. other packages)
that must be installed in order for the built package to run
correctly.
If a package in this list cannot be found during the build,
you will get a build error.
Lists runtime dependencies of a package.
These dependencies are other packages that must be
installed in order for the package to function correctly.
As an example, the following assignment declares that the
package <filename>foo</filename> needs the packages
<filename>bar</filename> and <filename>baz</filename> to
be installed:
<literallayout class='monospaced'>
RDEPENDS_foo = "bar baz"
</literallayout>
The most common types of package runtime dependencies are
automatically detected and added.
Therefore, most recipes do not need to set
<filename>RDEPENDS</filename>.
For more information, see the
"<link linkend='automatically-added-runtime-dependencies'>Automatically Added Runtime Dependencies</link>"
section.
</para>
<para>
When you use the <filename>RDEPENDS</filename> variable
in a recipe, you are essentially stating that the recipe's
The practical effect of the above
<filename>RDEPENDS</filename> assignment is that
<filename>bar</filename> and <filename>baz</filename>
will be declared as dependencies inside the package
<filename>foo</filename> when it is written out by one of
the
<link linkend='ref-tasks-package_write_deb'><filename>do_package_write_*</filename></link>
tasks.
Exactly how this is done depends on the package format used
as described in the
<link linkend='var-PACKAGE_CLASSES'><filename>PACKAGE_CLASSES</filename></link>
variable.
When the corresponding package manager installs the
package, it will know to also install the packages on
which it depends.
</para>
<para>
To ensure that the packages <filename>bar</filename> and
<filename>baz</filename> get built, the previous
<filename>RDEPENDS</filename> assignment also causes a task
dependency to be added.
This dependency is from the recipe's
<link linkend='ref-tasks-build'><filename>do_build</filename></link>
task depends on the existence of a specific package.
Consider this simple example for two recipes named "a" and
"b" that produce similarly named IPK packages.
In this example, the <filename>RDEPENDS</filename>
statement appears in the "a" recipe:
<literallayout class='monospaced'>
RDEPENDS_${PN} = "b"
</literallayout>
Here, the dependency is such that the
<filename>do_build</filename> task for recipe "a" depends
on the
<link linkend='ref-tasks-package_write_ipk'><filename>do_package_write_ipk</filename></link>
task of recipe "b".
This means the package file for "b" must be available when
the output for recipe "a" has been completely built.
More importantly, package "a" will be marked as depending
on package "b" in a manner that is understood by the
package manager.
(not to be confused with the
<link linkend='ref-tasks-compile'><filename>do_compile</filename></link>)
task to the to the <filename>do_package_write_*</filename>
task of the recipes that build <filename>bar</filename> and
<filename>baz</filename>.
</para>
<para>
@ -10480,7 +10508,8 @@ recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
<para>
Because the <filename>RDEPENDS</filename> variable applies
to packages being built, you should always use the variable
in a form with an attached package name.
in a form with an attached package name (remember that a
single recipe can build multiple packages).
For example, suppose you are building a development package
that depends on the <filename>perl</filename> package.
In this case, you would use the following
@ -10508,41 +10537,18 @@ recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
</para>
<para>
The package name you attach to the
<filename>RDEPENDS</filename> variable must appear
as it would in the <filename>PACKAGES</filename>
namespace before any renaming of the output package by
classes like
<link linkend='ref-classes-debian'><filename>debian</filename></link>.
</para>
<para>
In many cases you do not need to explicitly add
runtime dependencies using
<filename>RDEPENDS</filename> since some automatic
handling occurs:
<itemizedlist>
<listitem><para><emphasis><filename>shlibdeps</filename></emphasis>:
If a runtime package contains a compiled binary,
the build processes the binary in order to
determine any shared libraries
(<filename>.so</filename> files) to which it is
dynamically linked.
The build process adds the packages containing
these libraries to <filename>RDEPENDS</filename>
when creating the runtime package.
In addition, if the shared library is versioned,
the dependency will have the version appended to it
in order to force an upgrade to the appropriate
version if needed.
</para></listitem>
<listitem><para><emphasis><filename>pcdeps</filename></emphasis>: If
the package ships a <filename>pkg-config</filename>
information file, the build process uses this file
to add items to the <filename>RDEPENDS</filename>
variable to create the runtime packages.
</para></listitem>
</itemizedlist>
The package names you use with
<filename>RDEPENDS</filename> must appear as they would in
the <filename>PACKAGES</filename> variable.
The
<link linkend='var-PKG'><filename>PKG</filename></link>
variable allows a different name to be used for
the final package (e.g. the
<link linkend='ref-classes-debian'><filename>debian</filename></link>
class uses this to rename packages), but this final package
name cannot be used with <filename>RDEPENDS</filename>,
which makes sense as <filename>RDEPENDS</filename> is meant
to be independent of the package format used.
</para>
<para>

View File

@ -979,6 +979,113 @@
</section>
</section>
<section id='automatically-added-runtime-dependencies'>
<title>Automatically Added Runtime Dependencies</title>
<para>
The OpenEmbedded build system automatically adds common types of
runtime dependencies between packages, which means you do not need to
explicitly declare the packages using
<link linkend='var-RDEPENDS'><filename>RDEPENDS</filename></link>.
Two automatic mechanisms exist (<filename>shlibdeps</filename> and
<filename>pcdeps</filename>) that handle shared libraries and
package configuration (pkg-config) modules, respectively.
For other types of runtime dependencies, you must manually declare
the dependencies.
<itemizedlist>
<listitem><para>
<filename>shlibdeps</filename>:
During the
<link linkend='ref-tasks-package'><filename>do_package</filename></link>
task of each recipe, all shared libraries installed by the
recipe are located.
For each shared library, the package that contains the shared
library is registered as providing the shared library.
More specifically, the package is registered as providing the
<ulink url='https://en.wikipedia.org/wiki/Soname'>soname</ulink>
of the library.
The resulting shared-library-to-package mapping
is saved globally in
<link linkend='var-PKGDATA_DIR'><filename>PKGDATA_DIR</filename></link>
by the
<link linkend='ref-tasks-packagedata'><filename>do_packagedata</filename></link>
task.</para>
<para>Simultaneously, all executables and shared libraries
installed by the recipe are inspected to see what shared
libraries they link against.
For each shared library dependency that is found,
<filename>PKGDATA_DIR</filename> is queried to
see if some package (likely from a different recipe) contains
the shared library.
If such a package is found, a runtime dependency is added from
the package that depends on the shared library to the package
that contains the library.</para>
<para>If the library being linked against is versioned
(i.e. includes a version number), then the automatically added
runtime dependency will specify at least that version, as if
"<replaceable>package</replaceable> (>= <replaceable>version</replaceable>)"
had been added to
<link linkend='var-RDEPENDS'><filename>RDEPENDS</filename></link>.
This dependency forces an upgrade of the package that provides
the shared library when installing the package that depends on
the library, if needed.</para>
<para>If you want to avoid a package being registered as
providing a particular shared library (e.g. because the library
is for internal use only), then add the library to
<link linkend='var-PRIVATE_LIBS'><filename>PRIVATE_LIBS</filename></link>
inside the package's recipe.
</para></listitem>
<listitem><para>
<filename>pcdeps</filename>:
During the
<link linkend='ref-tasks-package'><filename>do_package</filename></link>
task of each recipe, all pkg-config modules
(<filename>*.pc</filename> files) installed by the recipe are
located.
For each module, the package that contains the module is
registered as providing the module.
The resulting module-to-package mapping is saved globally in
<link linkend='var-PKGDATA_DIR'><filename>PKGDATA_DIR</filename></link>
by the
<link linkend='ref-tasks-packagedata'><filename>do_packagedata</filename></link>
task.</para>
<para>Simultaneously, all pkg-config modules installed by the
recipe are inspected to see what other modules on which the
pkg-config modules depend.
A module is seen as depending on another module if it contains
a "Requires:" line that specifies the other module.
For each module dependency,
<filename>PKGDATA_DIR</filename> is queried to see if some
package contains the module.
If such a package is found, a runtime dependency is added from
the package that depends on the module to the package that
contains the module.
<note>
The <filename>pcdeps</filename> mechanism most often infers
dependencies between <filename>-dev</filename> packages.
</note>
</para></listitem>
</itemizedlist>
</para>
<para>
The <filename>do_package</filename> task depends on the
<link linkend='ref-tasks-packagedata'><filename>do_packagedata</filename></link>
task of each recipe in
<link linkend='var-DEPENDS'><filename>DEPENDS</filename></link>
through use of a
<ulink url='&YOCTO_DOCS_BB_URL;#variable-flags'><filename>[vardeps]</filename></ulink>
declaration, which guarantees that the required
shared-library/module-to-package mapping information will be available
when needed as long as <filename>DEPENDS</filename> has been
correctly set.
</para>
</section>
<section id='fakeroot-and-pseudo'>
<title>Fakeroot and Pseudo</title>