Initial commit

poky/documentation/migration-guides/migration-4.3.rst

@@ -0,0 +1,119 @@
+.. SPDX-License-Identifier: CC-BY-SA-2.0-UK
+
+Release 4.3 (nanbield)
+========================
+
+Migration notes for 4.3 (nanbield)
+------------------------------------
+
+This section provides migration information for moving to the Yocto
+Project 4.3 Release (codename "nanbield") from the prior release.
+
+.. _migration-4.3-supported-kernel-versions:
+
+Supported kernel versions
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The :term:`OLDEST_KERNEL` setting has been changed to "5.15" in this release, meaning that
+out the box, older kernels are not supported. There were two reasons for this.
+Firstly it allows glibc optimisations that improve the performance of the system
+by removing compatibility code and using modern kernel APIs exclusively. The second
+issue was this allows 64 bit time support even on 32 bit platforms and resolves Y2038
+issues.
+
+It is still possible to override this value and build for older kernels, this is just
+no longer the default supported configuration. This setting does not affect which
+kernel versions SDKs will run against and does not affect which versions of the kernel
+can be used to run builds.
+
+Layername override implications
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Code can now know which layer a recipe is coming from through the newly added
+:term:`FILE_LAYERNAME` variable and the ``layer-<layername> override``. This is being used
+for enabling QA checks on a per layer basis. For existing code this has the
+side effect that the QA checks will apply to things being bbappended to recipes
+from other layers. Those other layers would need to have patch upstream status
+entries for patches being bbappended for example.
+
+.. _migration-4.3-supported-distributions:
+
+Supported distributions
+~~~~~~~~~~~~~~~~~~~~~~~
+
+This release supports running BitBake on new GNU/Linux distributions:
+
+On the other hand, some earlier distributions are no longer supported:
+
+See :ref:`all supported distributions <system-requirements-supported-distros>`.
+
+.. _migration-4.3-go-changes:
+
+Go language changes
+~~~~~~~~~~~~~~~~~~~
+
+-  Support for the Glide package manager has been removed, as ``go mod``
+   has become the standard.
+
+Systemd changes
+~~~~~~~~~~~~~~~
+
+Upstream systemd is now more strict on filesystem layout and the ``usrmerge``
+feature is therefore required alongside systemd. The Poky test configurations
+have been updated accordingly for systemd.
+
+.. _migration-4.3-recipe-changes:
+
+Recipe changes
+~~~~~~~~~~~~~~
+
+-  Runtime testing of ptest now fails if no test results are returned by
+   any given ptest.
+
+.. _migration-4.3-class-changes:
+
+Class changes
+~~~~~~~~~~~~~
+
+-  The ``perl-version`` class no longer provides the ``PERLVERSION`` and ``PERLARCH`` variables
+   as there were no users in any core layer. The functions for this functionality
+   are still available.
+
+.. _migration-4.3-removed-variables:
+
+Removed variables
+~~~~~~~~~~~~~~~~~
+
+The following variables have been removed:
+
+-  ``PERLARCH``
+-  ``PERLVERSION``
+
+.. _migration-4.3-removed-recipes:
+
+Removed recipes
+~~~~~~~~~~~~~~~
+
+The following recipes have been removed in this release:
+
+-  ``glide``, as explained in :ref:`migration-4.3-go-changes`.
+
+.. _migration-4.3-removed-classes:
+
+Removed classes
+~~~~~~~~~~~~~~~
+
+The following classes have been removed in this release:
+
+
+.. _migration-4.3-misc-changes:
+
+Miscellaneous changes
+~~~~~~~~~~~~~~~~~~~~~
+
+-  The ``-crosssdk`` suffix and any :term:`MLPREFIX` were removed from
+   ``virtual/XXX`` provider/dependencies where a ``PREFIX`` was used as well,
+   as we don't need both and it made automated dependency rewriting
+   unnecessarily complex. In general this only affects internal toolchain
+   dependencies so isn't end user visible.
+