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, 446 insertions, 0 deletions

diff --git a/documentation/migration-guides/migration-2.2.rst b/documentation/migration-guides/migration-2.2.rst
new file mode 100644
index 0000000000..76311107ec
--- /dev/null
+++ b/documentation/migration-guides/migration-2.2.rst
@@ -0,0 +1,446 @@
+Release 2.2 (morty)
+===================
+
+This section provides migration information for moving to the Yocto
+Project 2.2 Release (codename "morty") from the prior release.
+
+.. _migration-2.2-minimum-kernel-version:
+
+Minimum Kernel Version
+----------------------
+
+The minimum kernel version for the target system and for SDK is now
+3.2.0, due to the upgrade to ``glibc 2.24``. Specifically, for
+AArch64-based targets the version is 3.14. For Nios II-based targets,
+the minimum kernel version is 3.19.
+
+.. note::
+
+   For x86 and x86_64, you can reset :term:`OLDEST_KERNEL`
+   to anything down to 2.6.32 if desired.
+
+.. _migration-2.2-staging-directories-in-sysroot-simplified:
+
+Staging Directories in Sysroot Has Been Simplified
+--------------------------------------------------
+
+The way directories are staged in sysroot has been simplified and
+introduces the new :term:`SYSROOT_DIRS`,
+:term:`SYSROOT_DIRS_NATIVE`, and
+:term:`SYSROOT_DIRS_BLACKLIST`. See the
+:oe_lists:`v2 patch series on the OE-Core Mailing List
+</pipermail/openembedded-core/2016-May/121365.html>`
+for additional information.
+
+.. _migration-2.2-removal-of-old-images-from-tmp-deploy-now-enabled:
+
+Removal of Old Images and Other Files in ``tmp/deploy`` Now Enabled
+-------------------------------------------------------------------
+
+Removal of old images and other files in ``tmp/deploy/`` is now enabled
+by default due to a new staging method used for those files. As a result
+of this change, the ``RM_OLD_IMAGE`` variable is now redundant.
+
+.. _migration-2.2-python-changes:
+
+Python Changes
+--------------
+
+The following changes for Python occurred:
+
+.. _migration-2.2-bitbake-now-requires-python-3.4:
+
+BitBake Now Requires Python 3.4+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+BitBake requires Python 3.4 or greater.
+
+.. _migration-2.2-utf-8-locale-required-on-build-host:
+
+UTF-8 Locale Required on Build Host
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+A UTF-8 locale is required on the build host due to Python 3. Since
+C.UTF-8 is not a standard, the default is en_US.UTF-8.
+
+.. _migration-2.2-metadata-now-must-use-python-3-syntax:
+
+Metadata Must Now Use Python 3 Syntax
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The metadata is now required to use Python 3 syntax. For help preparing
+metadata, see any of the many Python 3 porting guides available.
+Alternatively, you can reference the conversion commits for Bitbake and
+you can use :term:`OpenEmbedded-Core (OE-Core)` as a guide for changes. Following are
+particular areas of interest:
+
+  - subprocess command-line pipes needing locale decoding
+
+  - the syntax for octal values changed
+
+  - the ``iter*()`` functions changed name
+
+  - iterators now return views, not lists
+
+  - changed names for Python modules
+
+.. _migration-2.2-target-python-recipes-switched-to-python-3:
+
+Target Python Recipes Switched to Python 3
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Most target Python recipes have now been switched to Python 3.
+Unfortunately, systems using RPM as a package manager and providing
+online package-manager support through SMART still require Python 2.
+
+.. note::
+
+   Python 2 and recipes that use it can still be built for the target as
+   with previous versions.
+
+.. _migration-2.2-buildtools-tarball-includes-python-3:
+
+``buildtools-tarball`` Includes Python 3
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+``buildtools-tarball`` now includes Python 3.
+
+.. _migration-2.2-uclibc-replaced-by-musl:
+
+uClibc Replaced by musl
+-----------------------
+
+uClibc has been removed in favor of musl. Musl has matured, is better
+maintained, and is compatible with a wider range of applications as
+compared to uClibc.
+
+.. _migration-2.2-B-no-longer-default-working-directory-for-tasks:
+
+``${B}`` No Longer Default Working Directory for Tasks
+------------------------------------------------------
+
+``${``\ :term:`B`\ ``}`` is no longer the default working
+directory for tasks. Consequently, any custom tasks you define now need
+to either have the
+``[``\ :ref:`dirs <bitbake:bitbake-user-manual/bitbake-user-manual-metadata:variable flags>`\ ``]`` flag
+set, or the task needs to change into the appropriate working directory
+manually (e.g using ``cd`` for a shell task).
+
+.. note::
+
+   The preferred method is to use the
+   [dirs]
+   flag.
+
+.. _migration-2.2-runqemu-ported-to-python:
+
+``runqemu`` Ported to Python
+----------------------------
+
+``runqemu`` has been ported to Python and has changed behavior in some
+cases. Previous usage patterns continue to be supported.
+
+The new ``runqemu`` is a Python script. Machine knowledge is no longer
+hardcoded into ``runqemu``. You can choose to use the ``qemuboot``
+configuration file to define the BSP's own arguments and to make it
+bootable with ``runqemu``. If you use a configuration file, use the
+following form::
+
+   image-name-machine.qemuboot.conf
+
+The configuration file
+enables fine-grained tuning of options passed to QEMU without the
+``runqemu`` script hard-coding any knowledge about different machines.
+Using a configuration file is particularly convenient when trying to use
+QEMU with machines other than the ``qemu*`` machines in
+:term:`OpenEmbedded-Core (OE-Core)`. The ``qemuboot.conf`` file is generated by the
+``qemuboot`` class when the root filesystem is being build (i.e. build
+rootfs). QEMU boot arguments can be set in BSP's configuration file and
+the ``qemuboot`` class will save them to ``qemuboot.conf``.
+
+If you want to use ``runqemu`` without a configuration file, use the
+following command form::
+
+   $ runqemu machine rootfs kernel [options]
+
+Supported machines are as follows:
+
+  - qemuarm
+  - qemuarm64
+  - qemux86
+  - qemux86-64
+  - qemuppc
+  - qemumips
+  - qemumips64
+  - qemumipsel
+  - qemumips64el
+
+Consider the
+following example, which uses the ``qemux86-64`` machine, provides a
+root filesystem, provides an image, and uses the ``nographic`` option::
+
+   $ runqemu qemux86-64 tmp/deploy/images/qemux86-64/core-image-minimal-qemux86-64.ext4 tmp/deploy/images/qemux86-64/bzImage nographic
+
+Following is a list of variables that can be set in configuration files
+such as ``bsp.conf`` to enable the BSP to be booted by ``runqemu``:
+
+.. note::
+
+   "QB" means "QEMU Boot".
+
+::
+
+   QB_SYSTEM_NAME: QEMU name (e.g. "qemu-system-i386")
+   QB_OPT_APPEND: Options to append to QEMU (e.g. "-show-cursor")
+   QB_DEFAULT_KERNEL: Default kernel to boot (e.g. "bzImage")
+   QB_DEFAULT_FSTYPE: Default FSTYPE to boot (e.g. "ext4")
+   QB_MEM: Memory (e.g. "-m 512")
+   QB_MACHINE: QEMU machine (e.g. "-machine virt")
+   QB_CPU: QEMU cpu (e.g. "-cpu qemu32")
+   QB_CPU_KVM: Similar to QB_CPU except used for kvm support (e.g. "-cpu kvm64")
+   QB_KERNEL_CMDLINE_APPEND: Options to append to the kernel's -append
+                             option (e.g. "console=ttyS0 console=tty")
+   QB_DTB: QEMU dtb name
+   QB_AUDIO_DRV: QEMU audio driver (e.g. "alsa", set it when support audio)
+   QB_AUDIO_OPT: QEMU audio option (e.g. "-soundhw ac97,es1370"), which is used
+                 when QB_AUDIO_DRV is set.
+   QB_KERNEL_ROOT: Kernel's root (e.g. /dev/vda)
+   QB_TAP_OPT: Network option for 'tap' mode (e.g.
+               "-netdev tap,id=net0,ifname=@TAP@,script=no,downscript=no -device virtio-net-device,netdev=net0").
+                runqemu will replace "@TAP@" with the one that is used, such as tap0, tap1 ...
+   QB_SLIRP_OPT: Network option for SLIRP mode (e.g. "-netdev user,id=net0 -device virtio-net-device,netdev=net0")
+   QB_ROOTFS_OPT: Used as rootfs (e.g.
+                  "-drive id=disk0,file=@ROOTFS@,if=none,format=raw -device virtio-blk-device,drive=disk0").
+                  runqemu will replace "@ROOTFS@" with the one which is used, such as
+                  core-image-minimal-qemuarm64.ext4.
+   QB_SERIAL_OPT: Serial port (e.g. "-serial mon:stdio")
+   QB_TCPSERIAL_OPT: tcp serial port option (e.g.
+                     " -device virtio-serial-device -chardev socket,id=virtcon,port=@PORT@,host=127.0.0.1 -device      virtconsole,chardev=virtcon"
+                     runqemu will replace "@PORT@" with the port number which is used.
+
+To use ``runqemu``, set :term:`IMAGE_CLASSES` as
+follows and run ``runqemu``:
+
+.. note::
+
+   For command-line syntax, use ``runqemu help``.
+
+::
+
+   IMAGE_CLASSES += "qemuboot"
+
+.. _migration-2.2-default-linker-hash-style-changed:
+
+Default Linker Hash Style Changed
+---------------------------------
+
+The default linker hash style for ``gcc-cross`` is now "sysv" in order
+to catch recipes that are building software without using the
+OpenEmbedded :term:`LDFLAGS`. This change could result in
+seeing some "No GNU_HASH in the elf binary" QA issues when building such
+recipes. You need to fix these recipes so that they use the expected
+``LDFLAGS``. Depending on how the software is built, the build system
+used by the software (e.g. a Makefile) might need to be patched.
+However, sometimes making this fix is as simple as adding the following
+to the recipe::
+
+   TARGET_CC_ARCH += "${LDFLAGS}"
+
+.. _migration-2.2-kernel-image-base-name-no-longer-uses-kernel-imagetype:
+
+``KERNEL_IMAGE_BASE_NAME`` no Longer Uses ``KERNEL_IMAGETYPE``
+--------------------------------------------------------------
+
+The ``KERNEL_IMAGE_BASE_NAME`` variable no longer uses the
+:term:`KERNEL_IMAGETYPE` variable to create the
+image's base name. Because the OpenEmbedded build system can now build
+multiple kernel image types, this part of the kernel image base name as
+been removed leaving only the following::
+
+   KERNEL_IMAGE_BASE_NAME ?= "${PKGE}-${PKGV}-${PKGR}-${MACHINE}-${DATETIME}"
+
+If you have recipes or
+classes that use ``KERNEL_IMAGE_BASE_NAME`` directly, you might need to
+update the references to ensure they continue to work.
+
+.. _migration-2.2-bitbake-changes:
+
+BitBake Changes
+---------------
+
+The following changes took place for BitBake:
+
+-  The "goggle" UI and standalone image-writer tool have been removed as
+   they both require GTK+ 2.0 and were not being maintained.
+
+-  The Perforce fetcher now supports :term:`SRCREV` for
+   specifying the source revision to use, be it
+   ``${``\ :term:`AUTOREV`\ ``}``, changelist number,
+   p4date, or label, in preference to separate
+   :term:`SRC_URI` parameters to specify these. This
+   change is more in-line with how the other fetchers work for source
+   control systems. Recipes that fetch from Perforce will need to be
+   updated to use ``SRCREV`` in place of specifying the source revision
+   within ``SRC_URI``.
+
+-  Some of BitBake's internal code structures for accessing the recipe
+   cache needed to be changed to support the new multi-configuration
+   functionality. These changes will affect external tools that use
+   BitBake's tinfoil module. For information on these changes, see the
+   changes made to the scripts supplied with OpenEmbedded-Core:
+   :yocto_git:`1 </poky/commit/?id=189371f8393971d00bca0fceffd67cc07784f6ee>`
+   and
+   :yocto_git:`2 </poky/commit/?id=4a5aa7ea4d07c2c90a1654b174873abb018acc67>`.
+
+-  The task management code has been rewritten to avoid using ID
+   indirection in order to improve performance. This change is unlikely
+   to cause any problems for most users. However, the setscene
+   verification function as pointed to by
+   ``BB_SETSCENE_VERIFY_FUNCTION`` needed to change signature.
+   Consequently, a new variable named ``BB_SETSCENE_VERIFY_FUNCTION2``
+   has been added allowing multiple versions of BitBake to work with
+   suitably written metadata, which includes OpenEmbedded-Core and Poky.
+   Anyone with custom BitBake task scheduler code might also need to
+   update the code to handle the new structure.
+
+.. _migration-2.2-swabber-has-been-removed:
+
+Swabber has Been Removed
+------------------------
+
+Swabber, a tool that was intended to detect host contamination in the
+build process, has been removed, as it has been unmaintained and unused
+for some time and was never particularly effective. The OpenEmbedded
+build system has since incorporated a number of mechanisms including
+enhanced QA checks that mean that there is less of a need for such a
+tool.
+
+.. _migration-2.2-removed-recipes:
+
+Removed Recipes
+---------------
+
+The following recipes have been removed:
+
+-  ``augeas``: No longer needed and has been moved to ``meta-oe``.
+
+-  ``directfb``: Unmaintained and has been moved to ``meta-oe``.
+
+-  ``gcc``: Removed 4.9 version. Versions 5.4 and 6.2 are still present.
+
+-  ``gnome-doc-utils``: No longer needed.
+
+-  ``gtk-doc-stub``: Replaced by ``gtk-doc``.
+
+-  ``gtk-engines``: No longer needed and has been moved to
+   ``meta-gnome``.
+
+-  ``gtk-sato-engine``: Became obsolete.
+
+-  ``libglade``: No longer needed and has been moved to ``meta-oe``.
+
+-  ``libmad``: Unmaintained and functionally replaced by ``libmpg123``.
+   ``libmad`` has been moved to ``meta-oe``.
+
+-  ``libowl``: Became obsolete.
+
+-  ``libxsettings-client``: No longer needed.
+
+-  ``oh-puzzles``: Functionally replaced by ``puzzles``.
+
+-  ``oprofileui``: Became obsolete. OProfile has been largely supplanted
+   by perf.
+
+-  ``packagegroup-core-directfb.bb``: Removed.
+
+-  ``core-image-directfb.bb``: Removed.
+
+-  ``pointercal``: No longer needed and has been moved to ``meta-oe``.
+
+-  ``python-imaging``: No longer needed and moved to ``meta-python``
+
+-  ``python-pyrex``: No longer needed and moved to ``meta-python``.
+
+-  ``sato-icon-theme``: Became obsolete.
+
+-  ``swabber-native``: Swabber has been removed. See the :ref:`entry on
+   Swabber <migration-guides/migration-2.2:swabber has been removed>`.
+
+-  ``tslib``: No longer needed and has been moved to ``meta-oe``.
+
+-  ``uclibc``: Removed in favor of musl.
+
+-  ``xtscal``: No longer needed and moved to ``meta-oe``
+
+.. _migration-2.2-removed-classes:
+
+Removed Classes
+---------------
+
+The following classes have been removed:
+
+-  ``distutils-native-base``: No longer needed.
+
+-  ``distutils3-native-base``: No longer needed.
+
+-  ``sdl``: Only set :term:`DEPENDS` and
+   :term:`SECTION`, which are better set within the
+   recipe instead.
+
+-  ``sip``: Mostly unused.
+
+-  ``swabber``: See the :ref:`entry on
+   Swabber <migration-guides/migration-2.2:swabber has been removed>`.
+
+.. _migration-2.2-minor-packaging-changes:
+
+Minor Packaging Changes
+-----------------------
+
+The following minor packaging changes have occurred:
+
+-  ``grub``: Split ``grub-editenv`` into its own package.
+
+-  ``systemd``: Split container and vm related units into a new package,
+   systemd-container.
+
+-  ``util-linux``: Moved ``prlimit`` to a separate
+   ``util-linux-prlimit`` package.
+
+.. _migration-2.2-miscellaneous-changes:
+
+Miscellaneous Changes
+---------------------
+
+The following miscellaneous changes have occurred:
+
+-  ``package_regex.inc``: Removed because the definitions
+   ``package_regex.inc`` previously contained have been moved to their
+   respective recipes.
+
+-  Both ``devtool add`` and ``recipetool create`` now use a fixed
+   :term:`SRCREV` by default when fetching from a Git
+   repository. You can override this in either case to use
+   ``${``\ :term:`AUTOREV`\ ``}`` instead by using the
+   ``-a`` or ``--autorev`` command-line option
+
+-  ``distcc``: GTK+ UI is now disabled by default.
+
+-  ``packagegroup-core-tools-testapps``: Removed Piglit.
+
+-  ``image.bbclass``: Renamed COMPRESS(ION) to CONVERSION. This change
+   means that ``COMPRESSIONTYPES``, ``COMPRESS_DEPENDS`` and
+   ``COMPRESS_CMD`` are deprecated in favor of ``CONVERSIONTYPES``,
+   ``CONVERSION_DEPENDS`` and ``CONVERSION_CMD``. The ``COMPRESS*``
+   variable names will still work in the 2.2 release but metadata that
+   does not need to be backwards-compatible should be changed to use the
+   new names as the ``COMPRESS*`` ones will be removed in a future
+   release.
+
+-  ``gtk-doc``: A full version of ``gtk-doc`` is now made available.
+   However, some old software might not be capable of using the current
+   version of ``gtk-doc`` to build documentation. You need to change
+   recipes that build such software so that they explicitly disable
+   building documentation with ``gtk-doc``.
+
+