Moving to the Yocto Project 2.3 Release
=======================================

This section provides migration information for moving to the Yocto
Project 2.3 Release from the prior release.

.. _migration-2.3-recipe-specific-sysroots:

Recipe-specific Sysroots
------------------------

The OpenEmbedded build system now uses one sysroot per recipe to resolve
long-standing issues with configuration script auto-detection of
undeclared dependencies. Consequently, you might find that some of your
previously written custom recipes are missing declared dependencies,
particularly those dependencies that are incidentally built earlier in a
typical build process and thus are already likely to be present in the
shared sysroot in previous releases.

Consider the following:

-  *Declare Build-Time Dependencies:* Because of this new feature, you
   must explicitly declare all build-time dependencies for your recipe.
   If you do not declare these dependencies, they are not populated into
   the sysroot for the recipe.

-  *Specify Pre-Installation and Post-Installation Native Tool
   Dependencies:* You must specifically specify any special native tool
   dependencies of ``pkg_preinst`` and ``pkg_postinst`` scripts by using
   the :term:`PACKAGE_WRITE_DEPS` variable.
   Specifying these dependencies ensures that these tools are available
   if these scripts need to be run on the build host during the
   :ref:`ref-tasks-rootfs` task.

   As an example, see the ``dbus`` recipe. You will see that this recipe
   has a ``pkg_postinst`` that calls ``systemctl`` if "systemd" is in
   :term:`DISTRO_FEATURES`. In the example,
   ``systemd-systemctl-native`` is added to ``PACKAGE_WRITE_DEPS``,
   which is also conditional on "systemd" being in ``DISTRO_FEATURES``.

-  Examine Recipes that Use ``SSTATEPOSTINSTFUNCS``: You need to
   examine any recipe that uses ``SSTATEPOSTINSTFUNCS`` and determine
   steps to take.

   Functions added to ``SSTATEPOSTINSTFUNCS`` are still called as they
   were in previous Yocto Project releases. However, since a separate
   sysroot is now being populated for every recipe and if existing
   functions being called through ``SSTATEPOSTINSTFUNCS`` are doing
   relocation, then you will need to change these to use a
   post-installation script that is installed by a function added to
   :term:`SYSROOT_PREPROCESS_FUNCS`.

   For an example, see the ``pixbufcache`` class in ``meta/classes/`` in
   the :ref:`overview-manual/development-environment:yocto project source repositories`.

   .. note::

      The
      SSTATEPOSTINSTFUNCS
      variable itself is now deprecated in favor of the
      do_populate_sysroot[postfuncs]
      task. Consequently, if you do still have any function or functions
      that need to be called after the sysroot component is created for
      a recipe, then you would be well advised to take steps to use a
      post installation script as described previously. Taking these
      steps prepares your code for when
      SSTATEPOSTINSTFUNCS
      is removed in a future Yocto Project release.

-  *Specify the Sysroot when Using Certain External Scripts:* Because
   the shared sysroot is now gone, the scripts
   ``oe-find-native-sysroot`` and ``oe-run-native`` have been changed
   such that you need to specify which recipe's
   :term:`STAGING_DIR_NATIVE` is used.

.. note::

   You can find more information on how recipe-specific sysroots work in
   the ":ref:`ref-classes-staging`" section.

.. _migration-2.3-path-variable:

``PATH`` Variable
-----------------

Within the environment used to run build tasks, the environment variable
``PATH`` is now sanitized such that the normal native binary paths
(``/bin``, ``/sbin``, ``/usr/bin`` and so forth) are removed and a
directory containing symbolic links linking only to the binaries from
the host mentioned in the :term:`HOSTTOOLS` and
:term:`HOSTTOOLS_NONFATAL` variables is added
to ``PATH``.

Consequently, any native binaries provided by the host that you need to
call needs to be in one of these two variables at the configuration
level.

Alternatively, you can add a native recipe (i.e. ``-native``) that
provides the binary to the recipe's :term:`DEPENDS`
value.

.. note::

   PATH
   is not sanitized in the same way within ``devshell``.
   If it were, you would have difficulty running host tools for
   development and debugging within the shell.

.. _migration-2.3-scripts:

Changes to Scripts
------------------

The following changes to scripts took place:

-  ``oe-find-native-sysroot``: The usage for the
   ``oe-find-native-sysroot`` script has changed to the following:
   ::

      $ . oe-find-native-sysroot recipe

   You must now supply a recipe for recipe
   as part of the command. Prior to the Yocto Project 2.3 release, it
   was not necessary to provide the script with the command.

-  ``oe-run-native``: The usage for the ``oe-run-native`` script has
   changed to the following:
   ::

      $ oe-run-native native_recipe tool

   You must
   supply the name of the native recipe and the tool you want to run as
   part of the command. Prior to the Yocto Project 2.3 release, it
   was not necessary to provide the native recipe with the command.

-  ``cleanup-workdir``: The ``cleanup-workdir`` script has been
   removed because the script was found to be deleting files it should
   not have, which lead to broken build trees. Rather than trying to
   delete portions of :term:`TMPDIR` and getting it wrong,
   it is recommended that you delete ``TMPDIR`` and have it restored
   from shared state (sstate) on subsequent builds.

-  ``wipe-sysroot``: The ``wipe-sysroot`` script has been removed as
   it is no longer needed with recipe-specific sysroots.

.. _migration-2.3-functions:

Changes to Functions
--------------------

The previously deprecated ``bb.data.getVar()``, ``bb.data.setVar()``,
and related functions have been removed in favor of ``d.getVar()``,
``d.setVar()``, and so forth.

You need to fix any references to these old functions.

.. _migration-2.3-bitbake-changes:

BitBake Changes
---------------

The following changes took place for BitBake:

-  *BitBake's Graphical Dependency Explorer UI Replaced:* BitBake's
   graphical dependency explorer UI ``depexp`` was replaced by
   ``taskexp`` ("Task Explorer"), which provides a graphical way of
   exploring the ``task-depends.dot`` file. The data presented by Task
   Explorer is much more accurate than the data that was presented by
   ``depexp``. Being able to visualize the data is an often requested
   feature as standard ``*.dot`` file viewers cannot usual cope with the
   size of the ``task-depends.dot`` file.

-  *BitBake "-g" Output Changes:* The ``package-depends.dot`` and
   ``pn-depends.dot`` files as previously generated using the
   ``bitbake -g`` command have been removed. A ``recipe-depends.dot``
   file is now generated as a collapsed version of ``task-depends.dot``
   instead.

   The reason for this change is because ``package-depends.dot`` and
   ``pn-depends.dot`` largely date back to a time before task-based
   execution and do not take into account task-level dependencies
   between recipes, which could be misleading.

-  *Mirror Variable Splitting Changes:* Mirror variables including
   :term:`MIRRORS`, :term:`PREMIRRORS`,
   and :term:`SSTATE_MIRRORS` can now separate
   values entirely with spaces. Consequently, you no longer need "\\n".
   BitBake looks for pairs of values, which simplifies usage. There
   should be no change required to existing mirror variable values
   themselves.

-  *The Subversion (SVN) Fetcher Uses an "ssh" Parameter and Not an
   "rsh" Parameter:* The SVN fetcher now takes an "ssh" parameter
   instead of an "rsh" parameter. This new optional parameter is used
   when the "protocol" parameter is set to "svn+ssh". You can only use
   the new parameter to specify the ``ssh`` program used by SVN. The SVN
   fetcher passes the new parameter through the ``SVN_SSH`` environment
   variable during the :ref:`ref-tasks-fetch` task.

   See the ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-fetching:subversion (svn) fetcher (\`\`svn://\`\`)`"
   section in the BitBake
   User Manual for additional information.

-  ``BB_SETSCENE_VERIFY_FUNCTION`` and ``BB_SETSCENE_VERIFY_FUNCTION2``
   Removed: Because the mechanism they were part of is no longer
   necessary with recipe-specific sysroots, the
   ``BB_SETSCENE_VERIFY_FUNCTION`` and ``BB_SETSCENE_VERIFY_FUNCTION2``
   variables have been removed.

.. _migration-2.3-absolute-symlinks:

Absolute Symbolic Links
-----------------------

Absolute symbolic links (symlinks) within staged files are no longer
permitted and now trigger an error. Any explicit creation of symlinks
can use the ``lnr`` script, which is a replacement for ``ln -r``.

If the build scripts in the software that the recipe is building are
creating a number of absolute symlinks that need to be corrected, you
can inherit ``relative_symlinks`` within the recipe to turn those
absolute symlinks into relative symlinks.

.. _migration-2.3-gplv2-and-gplv3-moves:

GPLv2 Versions of GPLv3 Recipes Moved
-------------------------------------

Older GPLv2 versions of GPLv3 recipes have moved to a separate
``meta-gplv2`` layer.

If you use :term:`INCOMPATIBLE_LICENSE` to
exclude GPLv3 or set :term:`PREFERRED_VERSION`
to substitute a GPLv2 version of a GPLv3 recipe, then you must add the
``meta-gplv2`` layer to your configuration.

.. note::

   You can ``find meta-gplv2`` layer in the OpenEmbedded layer index at
   https://layers.openembedded.org/layerindex/branch/master/layer/meta-gplv2/.

These relocated GPLv2 recipes do not receive the same level of
maintenance as other core recipes. The recipes do not get security fixes
and upstream no longer maintains them. In fact, the upstream community
is actively hostile towards people that use the old versions of the
recipes. Moving these recipes into a separate layer both makes the
different needs of the recipes clearer and clearly identifies the number
of these recipes.

.. note::

   The long-term solution might be to move to BSD-licensed replacements
   of the GPLv3 components for those that need to exclude GPLv3-licensed
   components from the target system. This solution will be investigated
   for future Yocto Project releases.

.. _migration-2.3-package-management-changes:

Package Management Changes
--------------------------

The following package management changes took place:

-  Smart package manager is replaced by DNF package manager. Smart has
   become unmaintained upstream, is not ported to Python 3.x.
   Consequently, Smart needed to be replaced. DNF is the only feasible
   candidate.

   The change in functionality is that the on-target runtime package
   management from remote package feeds is now done with a different
   tool that has a different set of command-line options. If you have
   scripts that call the tool directly, or use its API, they need to be
   fixed.

   For more information, see the `DNF
   Documentation <http://dnf.readthedocs.io/en/latest/>`__.

-  Rpm 5.x is replaced with Rpm 4.x. This is done for two major reasons:

   -  DNF is API-incompatible with Rpm 5.x and porting it and
      maintaining the port is non-trivial.

   -  Rpm 5.x itself has limited maintenance upstream, and the Yocto
      Project is one of the very few remaining users.

-  Berkeley DB 6.x is removed and Berkeley DB 5.x becomes the default:

   -  Version 6.x of Berkeley DB has largely been rejected by the open
      source community due to its AGPLv3 license. As a result, most
      mainstream open source projects that require DB are still
      developed and tested with DB 5.x.

   -  In OE-core, the only thing that was requiring DB 6.x was Rpm 5.x.
      Thus, no reason exists to continue carrying DB 6.x in OE-core.

-  ``createrepo`` is replaced with ``createrepo_c``.

   ``createrepo_c`` is the current incarnation of the tool that
   generates remote repository metadata. It is written in C as compared
   to ``createrepo``, which is written in Python. ``createrepo_c`` is
   faster and is maintained.

-  Architecture-independent RPM packages are "noarch" instead of "all".

   This change was made because too many places in DNF/RPM4 stack
   already make that assumption. Only the filenames and the architecture
   tag has changed. Nothing else has changed in OE-core system,
   particularly in the :ref:`allarch.bbclass <ref-classes-allarch>`
   class.

-  Signing of remote package feeds using ``PACKAGE_FEED_SIGN`` is not
   currently supported. This issue will be fully addressed in a future
   Yocto Project release. See :yocto_bugs:`defect 11209 </show_bug.cgi?id=11209>`
   for more information on a solution to package feed signing with RPM
   in the Yocto Project 2.3 release.

-  OPKG now uses the libsolv backend for resolving package dependencies
   by default. This is vastly superior to OPKG's internal ad-hoc solver
   that was previously used. This change does have a small impact on
   disk (around 500 KB) and memory footprint.

   .. note::

      For further details on this change, see the
      :yocto_git:`commit message </poky/commit/?id=f4d4f99cfbc2396e49c1613a7d237b9e57f06f81>`.

.. _migration-2.3-removed-recipes:

Removed Recipes
---------------

The following recipes have been removed:

-  ``linux-yocto 4.8``: Version 4.8 has been removed. Versions 4.1
   (LTSI), 4.4 (LTS), 4.9 (LTS/LTSI) and 4.10 are now present.

-  ``python-smartpm``: Functionally replaced by ``dnf``.

-  ``createrepo``: Replaced by the ``createrepo-c`` recipe.

-  ``rpmresolve``: No longer needed with the move to RPM 4 as RPM
   itself is used instead.

-  ``gstreamer``: Removed the GStreamer Git version recipes as they
   have been stale. ``1.10.``\ x recipes are still present.

-  ``alsa-conf-base``: Merged into ``alsa-conf`` since ``libasound``
   depended on both. Essentially, no way existed to install only one of
   these.

-  ``tremor``: Moved to ``meta-multimedia``. Fixed-integer Vorbis
   decoding is not needed by current hardware. Thus, GStreamer's ivorbis
   plugin has been disabled by default eliminating the need for the
   ``tremor`` recipe in :term:`OpenEmbedded-Core (OE-Core)`.

-  ``gummiboot``: Replaced by ``systemd-boot``.

.. _migration-2.3-wic-changes:

Wic Changes
-----------

The following changes have been made to Wic:

.. note::

   For more information on Wic, see the
   ":ref:`dev-manual/common-tasks:creating partitioned images using wic`"
   section in the Yocto Project Development Tasks Manual.

-  *Default Output Directory Changed:* Wic's default output directory is
   now the current directory by default instead of the unusual
   ``/var/tmp/wic``.

   The "-o" and "--outdir" options remain unchanged and are used to
   specify your preferred output directory if you do not want to use the
   default directory.

-  *fsimage Plug-in Removed:* The Wic fsimage plugin has been removed as
   it duplicates functionality of the rawcopy plugin.

.. _migration-2.3-qa-changes:

QA Changes
----------

The following QA checks have changed:

-  ``unsafe-references-in-binaries``: The
   ``unsafe-references-in-binaries`` QA check, which was disabled by
   default, has now been removed. This check was intended to detect
   binaries in ``/bin`` that link to libraries in ``/usr/lib`` and have
   the case where the user has ``/usr`` on a separate filesystem to
   ``/``.

   The removed QA check was buggy. Additionally, ``/usr`` residing on a
   separate partition from ``/`` is now a rare configuration.
   Consequently, ``unsafe-references-in-binaries`` was removed.

-  ``file-rdeps``: The ``file-rdeps`` QA check is now an error by
   default instead of a warning. Because it is an error instead of a
   warning, you need to address missing runtime dependencies.

   For additional information, see the
   :ref:`insane <ref-classes-insane>` class and the
   ":ref:`ref-manual/qa-checks:errors and warnings`" section.

.. _migration-2.3-miscellaneous-changes:

Miscellaneous Changes
---------------------

The following miscellaneous changes have occurred:

-  In this release, a number of recipes have been changed to ignore the
   ``largefile`` :term:`DISTRO_FEATURES` item,
   enabling large file support unconditionally. This feature has always
   been enabled by default. Disabling the feature has not been widely
   tested.

   .. note::

      Future releases of the Yocto Project will remove entirely the
      ability to disable the
      largefile
      feature, which would make it unconditionally enabled everywhere.

-  If the :term:`DISTRO_VERSION` value contains
   the value of the :term:`DATE` variable, which is the
   default between Poky releases, the ``DATE`` value is explicitly
   excluded from ``/etc/issue`` and ``/etc/issue.net``, which is
   displayed at the login prompt, in order to avoid conflicts with
   Multilib enabled. Regardless, the ``DATE`` value is inaccurate if the
   ``base-files`` recipe is restored from shared state (sstate) rather
   than rebuilt.

   If you need the build date recorded in ``/etc/issue*`` or anywhere
   else in your image, a better method is to define a post-processing
   function to do it and have the function called from
   :term:`ROOTFS_POSTPROCESS_COMMAND`.
   Doing so ensures the value is always up-to-date with the created
   image.

-  Dropbear's ``init`` script now disables DSA host keys by default.
   This change is in line with the systemd service file, which supports
   RSA keys only, and with recent versions of OpenSSH, which deprecates
   DSA host keys.

-  The :ref:`buildhistory <ref-classes-buildhistory>` class now
   correctly uses tabs as separators between all columns in
   ``installed-package-sizes.txt`` in order to aid import into other
   tools.

-  The ``USE_LDCONFIG`` variable has been replaced with the "ldconfig"
   ``DISTRO_FEATURES`` feature. Distributions that previously set:
   ::

      USE_LDCONFIG = "0"

   should now instead use the following:

   ::

      DISTRO_FEATURES_BACKFILL_CONSIDERED_append = " ldconfig"

-  The default value of
   :term:`COPYLEFT_LICENSE_INCLUDE` now
   includes all versions of AGPL licenses in addition to GPL and LGPL.

   .. note::

      The default list is not intended to be guaranteed as a complete
      safe list. You should seek legal advice based on what you are
      distributing if you are unsure.

-  Kernel module packages are now suffixed with the kernel version in
   order to allow module packages from multiple kernel versions to
   co-exist on a target system. If you wish to return to the previous
   naming scheme that does not include the version suffix, use the
   following:
   ::

      KERNEL_MODULE_PACKAGE_SUFFIX = ""

-  Removal of ``libtool`` ``*.la`` files is now enabled by default. The
   ``*.la`` files are not actually needed on Linux and relocating them
   is an unnecessary burden.

   If you need to preserve these ``.la`` files (e.g. in a custom
   distribution), you must change
   :term:`INHERIT_DISTRO` such that
   "remove-libtool" is not included in the value.

-  Extensible SDKs built for GCC 5+ now refuse to install on a
   distribution where the host GCC version is 4.8 or 4.9. This change
   resulted from the fact that the installation is known to fail due to
   the way the ``uninative`` shared state (sstate) package is built. See
   the :ref:`uninative <ref-classes-uninative>` class for additional
   information.

-  All native and nativesdk recipes now use a separate
   ``DISTRO_FEATURES`` value instead of sharing the value used by
   recipes for the target, in order to avoid unnecessary rebuilds.

   The ``DISTRO_FEATURES`` for ``native`` recipes is
   :term:`DISTRO_FEATURES_NATIVE` added to
   an intersection of ``DISTRO_FEATURES`` and
   :term:`DISTRO_FEATURES_FILTER_NATIVE`.

   For nativesdk recipes, the corresponding variables are
   :term:`DISTRO_FEATURES_NATIVESDK`
   and
   :term:`DISTRO_FEATURES_FILTER_NATIVESDK`.

-  The ``FILESDIR`` variable, which was previously deprecated and rarely
   used, has now been removed. You should change any recipes that set
   ``FILESDIR`` to set :term:`FILESPATH` instead.

-  The ``MULTIMACH_HOST_SYS`` variable has been removed as it is no
   longer needed with recipe-specific sysroots.