ref-manual: move migration guides to separate document

This makes the reference manual much lighter by moving
the migration guides to a separate document.

The migration guides are also reordered from last to first,
and they appear directly in the left bar, making them easier
to find in the documentation.

(From yocto-docs rev: 5121b86ee97eb62a0c69c9ad1fc0e3fabbe3e934)

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 278 insertions, 0 deletions

diff --git a/documentation/migration-guides/migration-2.0.rst b/documentation/migration-guides/migration-2.0.rst
new file mode 100644
index 0000000000..22d0752226
--- /dev/null
+++ b/documentation/migration-guides/migration-2.0.rst
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+Release 2.0 (jethro)
+====================
+
+This section provides migration information for moving to the Yocto
+Project 2.0 Release (codename "jethro") from the prior release.
+
+.. _migration-2.0-gcc-5:
+
+GCC 5
+-----
+
+The default compiler is now GCC 5.2. This change has required fixes for
+compilation errors in a number of other recipes.
+
+One important example is a fix for when the Linux kernel freezes at boot
+time on ARM when built with GCC 5. If you are using your own kernel
+recipe or source tree and building for ARM, you will likely need to
+apply this
+`patch <https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit?id=a077224fd35b2f7fbc93f14cf67074fc792fbac2>`__.
+The standard ``linux-yocto`` kernel source tree already has a workaround
+for the same issue.
+
+For further details, see https://gcc.gnu.org/gcc-5/changes.html
+and the porting guide at
+https://gcc.gnu.org/gcc-5/porting_to.html.
+
+Alternatively, you can switch back to GCC 4.9 or 4.8 by setting
+``GCCVERSION`` in your configuration, as follows::
+
+   GCCVERSION = "4.9%"
+
+.. _migration-2.0-Gstreamer-0.10-removed:
+
+Gstreamer 0.10 Removed
+----------------------
+
+Gstreamer 0.10 has been removed in favor of Gstreamer 1.x. As part of
+the change, recipes for Gstreamer 0.10 and related software are now
+located in ``meta-multimedia``. This change results in Qt4 having Phonon
+and Gstreamer support in QtWebkit disabled by default.
+
+.. _migration-2.0-removed-recipes:
+
+Removed Recipes
+---------------
+
+The following recipes have been moved or removed:
+
+-  ``bluez4``: The recipe is obsolete and has been moved due to
+   ``bluez5`` becoming fully integrated. The ``bluez4`` recipe now
+   resides in ``meta-oe``.
+
+-  ``gamin``: The recipe is obsolete and has been removed.
+
+-  ``gnome-icon-theme``: The recipe's functionally has been replaced by
+   ``adwaita-icon-theme``.
+
+-  Gstreamer 0.10 Recipes: Recipes for Gstreamer 0.10 have been removed
+   in favor of the recipes for Gstreamer 1.x.
+
+-  ``insserv``: The recipe is obsolete and has been removed.
+
+-  ``libunique``: The recipe is no longer used and has been moved to
+   ``meta-oe``.
+
+-  ``midori``: The recipe's functionally has been replaced by
+   ``epiphany``.
+
+-  ``python-gst``: The recipe is obsolete and has been removed since it
+   only contains bindings for Gstreamer 0.10.
+
+-  ``qt-mobility``: The recipe is obsolete and has been removed since it
+   requires ``Gstreamer 0.10``, which has been replaced.
+
+-  ``subversion``: All 1.6.x versions of this recipe have been removed.
+
+-  ``webkit-gtk``: The older 1.8.3 version of this recipe has been
+   removed in favor of ``webkitgtk``.
+
+.. _migration-2.0-bitbake-datastore-improvements:
+
+BitBake datastore improvements
+------------------------------
+
+The method by which BitBake's datastore handles overrides has changed.
+Overrides are now applied dynamically and ``bb.data.update_data()`` is
+now a no-op. Thus, ``bb.data.update_data()`` is no longer required in
+order to apply the correct overrides. In practice, this change is
+unlikely to require any changes to Metadata. However, these minor
+changes in behavior exist:
+
+-  All potential overrides are now visible in the variable history as
+   seen when you run the following::
+
+      $ bitbake -e
+
+-  ``d.delVar('VARNAME')`` and
+   ``d.setVar('VARNAME', None)`` result in the variable and all
+   of its overrides being cleared out. Before the change, only the
+   non-overridden values were cleared.
+
+.. _migration-2.0-shell-message-function-changes:
+
+Shell Message Function Changes
+------------------------------
+
+The shell versions of the BitBake message functions (i.e. ``bbdebug``,
+``bbnote``, ``bbwarn``, ``bbplain``, ``bberror``, and ``bbfatal``) are
+now connected through to their BitBake equivalents ``bb.debug()``,
+``bb.note()``, ``bb.warn()``, ``bb.plain()``, ``bb.error()``, and
+``bb.fatal()``, respectively. Thus, those message functions that you
+would expect to be printed by the BitBake UI are now actually printed.
+In practice, this change means two things:
+
+-  If you now see messages on the console that you did not previously
+   see as a result of this change, you might need to clean up the calls
+   to ``bbwarn``, ``bberror``, and so forth. Or, you might want to
+   simply remove the calls.
+
+-  The ``bbfatal`` message function now suppresses the full error log in
+   the UI, which means any calls to ``bbfatal`` where you still wish to
+   see the full error log should be replaced by ``die`` or
+   ``bbfatal_log``.
+
+.. _migration-2.0-extra-development-debug-package-cleanup:
+
+Extra Development/Debug Package Cleanup
+---------------------------------------
+
+The following recipes have had extra ``dev/dbg`` packages removed:
+
+-  ``acl``
+
+-  ``apmd``
+
+-  ``aspell``
+
+-  ``attr``
+
+-  ``augeas``
+
+-  ``bzip2``
+
+-  ``cogl``
+
+-  ``curl``
+
+-  ``elfutils``
+
+-  ``gcc-target``
+
+-  ``libgcc``
+
+-  ``libtool``
+
+-  ``libxmu``
+
+-  ``opkg``
+
+-  ``pciutils``
+
+-  ``rpm``
+
+-  ``sysfsutils``
+
+-  ``tiff``
+
+-  ``xz``
+
+All of the above recipes now conform to the standard packaging scheme
+where a single ``-dev``, ``-dbg``, and ``-staticdev`` package exists per
+recipe.
+
+.. _migration-2.0-recipe-maintenance-tracking-data-moved-to-oe-core:
+
+Recipe Maintenance Tracking Data Moved to OE-Core
+-------------------------------------------------
+
+Maintenance tracking data for recipes that was previously part of
+``meta-yocto`` has been moved to :term:`OpenEmbedded-Core (OE-Core)`. The change
+includes ``package_regex.inc`` and ``distro_alias.inc``, which are
+typically enabled when using the ``distrodata`` class. Additionally, the
+contents of ``upstream_tracking.inc`` has now been split out to the
+relevant recipes.
+
+.. _migration-2.0-automatic-stale-sysroot-file-cleanup:
+
+Automatic Stale Sysroot File Cleanup
+------------------------------------
+
+Stale files from recipes that no longer exist in the current
+configuration are now automatically removed from sysroot as well as
+removed from any other place managed by shared state. This automatic
+cleanup means that the build system now properly handles situations such
+as renaming the build system side of recipes, removal of layers from
+``bblayers.conf``, and :term:`DISTRO_FEATURES`
+changes.
+
+Additionally, work directories for old versions of recipes are now
+pruned. If you wish to disable pruning old work directories, you can set
+the following variable in your configuration::
+
+   SSTATE_PRUNE_OBSOLETEWORKDIR = "0"
+
+.. _migration-2.0-linux-yocto-kernel-metadata-repository-now-split-from-source:
+
+``linux-yocto`` Kernel Metadata Repository Now Split from Source
+----------------------------------------------------------------
+
+The ``linux-yocto`` tree has up to now been a combined set of kernel
+changes and configuration (meta) data carried in a single tree. While
+this format is effective at keeping kernel configuration and source
+modifications synchronized, it is not always obvious to developers how
+to manipulate the Metadata as compared to the source.
+
+Metadata processing has now been removed from the
+:ref:`kernel-yocto <ref-classes-kernel-yocto>` class and the external
+Metadata repository ``yocto-kernel-cache``, which has always been used
+to seed the ``linux-yocto`` "meta" branch. This separate ``linux-yocto``
+cache repository is now the primary location for this data. Due to this
+change, ``linux-yocto`` is no longer able to process combined trees.
+Thus, if you need to have your own combined kernel repository, you must
+do the split there as well and update your recipes accordingly. See the
+``meta/recipes-kernel/linux/linux-yocto_4.1.bb`` recipe for an example.
+
+.. _migration-2.0-additional-qa-checks:
+
+Additional QA checks
+--------------------
+
+The following QA checks have been added:
+
+-  Added a "host-user-contaminated" check for ownership issues for
+   packaged files outside of ``/home``. The check looks for files that
+   are incorrectly owned by the user that ran BitBake instead of owned
+   by a valid user in the target system.
+
+-  Added an "invalid-chars" check for invalid (non-UTF8) characters in
+   recipe metadata variable values (i.e.
+   :term:`DESCRIPTION`,
+   :term:`SUMMARY`, :term:`LICENSE`, and
+   :term:`SECTION`). Some package managers do not support
+   these characters.
+
+-  Added an "invalid-packageconfig" check for any options specified in
+   :term:`PACKAGECONFIG` that do not match any
+   ``PACKAGECONFIG`` option defined for the recipe.
+
+.. _migration-2.0-miscellaneous:
+
+Miscellaneous Changes
+---------------------
+
+These additional changes exist:
+
+-  ``gtk-update-icon-cache`` has been renamed to ``gtk-icon-utils``.
+
+-  The ``tools-profile`` :term:`IMAGE_FEATURES`
+   item as well as its corresponding packagegroup and
+   ``packagegroup-core-tools-profile`` no longer bring in ``oprofile``.
+   Bringing in ``oprofile`` was originally added to aid compilation on
+   resource-constrained targets. However, this aid has not been widely
+   used and is not likely to be used going forward due to the more
+   powerful target platforms and the existence of better
+   cross-compilation tools.
+
+-  The :term:`IMAGE_FSTYPES` variable's default
+   value now specifies ``ext4`` instead of ``ext3``.
+
+-  All support for the ``PRINC`` variable has been removed.
+
+-  The ``packagegroup-core-full-cmdline`` packagegroup no longer brings
+   in ``lighttpd`` due to the fact that bringing in ``lighttpd`` is not
+   really in line with the packagegroup's purpose, which is to add full
+   versions of command-line tools that by default are provided by
+   ``busybox``.
+
+