# Migrating to a Newer Yocto Project Release

This chapter provides information you can use to migrate work to a newer Yocto Project release. You can find the same information in the release notes for a given release.

## General Migration Considerations

Some considerations are not tied to a specific Yocto Project release. This section presents information you should consider when migrating to any new Yocto Project release.

- Dealing with Customized Recipes: Issues could arise if you take older recipes that contain customizations and simply copy them forward expecting them to work after you migrate to new Yocto Project metadata. For example, suppose you have a recipe in your layer that is a customized version of a core recipe copied from the earlier release, rather than through the use of an append file. When you migrate to a newer version of Yocto Project, the metadata (e.g. perhaps an include file used by the recipe) could have changed in a way that would break the build. Say, for example, a function is removed from an include file and the customized recipe tries to call that function.

  You could "forward-port" all your customizations in your recipe so that everything works for the new release. However, this is not the optimal solution as you would have to repeat this process with each new release if changes occur that give rise to problems.

  The better solution (where practical) is to use append files (`*.bbappend`) to capture any customizations you want to make to a recipe. Doing so, isolates your changes from the main recipe making them much more manageable. However, sometimes it is not practical to use an append file. A good example of this is when introducing a newer or older version of a recipe in another layer.

- Updating Append Files: Since append files generally only contain your customizations, they often do not need to be adjusted for new releases. However, if the `.bbappend` file is specific to a particular version of the recipe (i.e. its name does not use the % wildcard) and the version of the recipe to which it is appending has changed, then you will at a minimum need to rename the append file to match the name of the recipe file. A mismatch between an append file and its corresponding recipe file (`.bb`) will trigger an error during parsing.

  Depending on the type of customization the append file applies, other incompatibilities might occur when you upgrade. For example, if your append file applies a patch and the recipe to which it is appending is updated to a newer version, the patch might no longer apply. If this is the case and assuming the patch is still needed, you must modify the patch file so that it does apply.

## Moving to the Yocto Project 1.3 Release

This section provides migration information for moving to the Yocto Project 1.3 Release from the prior release.

### Local Configuration

Differences include changes for `SSTATE_MIRRORS` and `bblayers.conf`.

#### SSTATE_MIRRORS

The shared state cache (sstate-cache), as pointed to by `SSTATE_DIR`, by default now has two-character subdirectories to prevent issues arising from too many files in the same directory. Also, native sstate-cache packages, which are built to run on the host system, will go into a subdirectory named using the distro ID string. If you copy the newly structured sstate-cache to a mirror location (either local or remote) and then point to it in `SSTATE_MIRRORS`, you need to append "PATH" to the end of the mirror URL so that the path used by BitBake before the mirror substitution is appended to the path used to access the mirror. Here is an example:

         SSTATE_MIRRORS = "file://.* http://someserver.tld/share/sstate/PATH"

#### bblayers.conf

The `meta-yocto` layer consists of two parts that correspond to the Poky reference distribution and the reference hardware Board Support Packages (BSPs), respectively: `meta-yocto` and `meta-yocto-bsp`. When running BitBake for the first time after upgrading, your `conf/bblayers.conf` file will be updated to handle this change and you will be asked to re-run or restart for the changes to take effect.

### Recipes

Differences include changes for the following:

- Python function whitespace

- `proto=` in `SRC_URI`

- `nativesdk`

- Task recipes

- `IMAGE_FEATURES`

- Removed recipes

#### Python Function Whitespace

All Python functions must now use four spaces for indentation. Previously, an inconsistent mix of spaces and tabs existed, which made extending these functions using `_append` or `_prepend` complicated given that Python treats whitespace as syntactically significant. If you are defining or extending any Python functions (e.g. `populate_packages`, `do_unpack`, `do_patch` and so forth) in custom recipes or classes, you need to ensure you are using consistent four-space indentation.

#### proto= in SRC_URI

Any use of `proto=` in `SRC_URI` needs to be changed to `protocol=`. In particular, this applies to the following URIs:

- `svn://`

- `bzr://`

- `hg://`

- `osc://`

Other URIs were already using `protocol=`. This change improves consistency.

#### nativesdk

The suffix `nativesdk` is now implemented as a prefix, which simplifies a lot of the packaging code for `nativesdk` recipes. All custom `nativesdk` recipes, which are relocatable packages that are native to `SDK_ARCH`, and any references need to be updated to use `nativesdk-*` instead of `*-nativesdk`.

#### Task Recipes

"Task" recipes are now known as "Package groups" and have been renamed from `task-*.bb` to `packagegroup-*.bb`. Existing references to the previous `task-*` names should work in most cases as there is an automatic upgrade path for most packages. However, you should update references in your own recipes and configurations as they could be removed in future releases. You should also rename any custom `task-*` recipes to `packagegroup-*`, and change them to inherit `packagegroup` instead of `task`, as well as taking the opportunity to remove anything now handled by `packagegroup.bbclass`, such as providing `-dev` and `-dbg` packages, setting `LIC_FILES_CHKSUM`, and so forth. See the "`packagegroup.bbclass`" section for further details.

#### IMAGE_FEATURES

Image recipes that previously included "apps-console-core" in `IMAGE_FEATURES` should now include "splash" instead to enable the boot-up splash screen. Retaining "apps-console-core" will still include the splash screen but generates a warning. The "apps-x11-core" and "apps-x11-games" `IMAGE_FEATURES` features have been removed.

#### Removed Recipes

The following recipes have been removed. For most of them, it is unlikely that you would have any references to them in your own Metadata. However, you should check your metadata against this list to be sure:

- `libx11-trim`: Replaced by `libx11`, which has a negligible size difference with modern Xorg.

- `xserver-xorg-lite`: Use `xserver-xorg`, which has a negligible size difference when DRI and GLX modules are not installed.

- `xserver-kdrive`: Effectively unmaintained for many years.

- `mesa-xlib`: No longer serves any purpose.

- `galago`: Replaced by telepathy.

- `gail`: Functionality was integrated into GTK+ 2.13.

- `eggdbus`: No longer needed.

- `gcc-*-intermediate`: The build has been restructured to avoid the need for this step.

- `libgsmd`: Unmaintained for many years. Functionality now provided by `ofono` instead.

- contacts, dates, tasks, eds-tools: Largely unmaintained PIM application suite. It has been moved to `meta-gnome` in `meta-openembedded`.

In addition to the previously listed changes, the `meta-demoapps` directory has also been removed because the recipes in it were not being maintained and many had become obsolete or broken. Additionally, these recipes were not parsed in the default configuration. Many of these recipes are already provided in an updated and maintained form within the OpenEmbedded community layers such as `meta-oe` and `meta-gnome`. For the remainder, you can now find them in the `meta-extras` repository, which is in the Yocto Project Source Repositories.

### Linux Kernel Naming

The naming scheme for kernel output binaries has been changed to now include `PE` as part of the filename:

         KERNEL_IMAGE_BASE_NAME ?= "${KERNEL_IMAGETYPE}-${PE}-${PV}-${PR}-${MACHINE}-${DATETIME}"

Because the `PE` variable is not set by default, these binary files could result with names that include two dash characters. Here is an example:

         bzImage--3.10.9+git0+cd502a8814_7144bcc4b8-r0-qemux86-64-20130830085431.bin

## Moving to the Yocto Project 1.4 Release

This section provides migration information for moving to the Yocto Project 1.4 Release from the prior release.

### BitBake

Differences include the following:

- Comment Continuation: If a comment ends with a line continuation (\) character, then the next line must also be a comment. Any instance where this is not the case, now triggers a warning. You must either remove the continuation character, or be sure the next line is a comment.

- Package Name Overrides: The runtime package specific variables `RDEPENDS`, `RRECOMMENDS`, `RSUGGESTS`, `RPROVIDES`, `RCONFLICTS`, `RREPLACES`, `FILES`, `ALLOW_EMPTY`, and the pre, post, install, and uninstall script functions `pkg_preinst`, `pkg_postinst`, `pkg_prerm`, and `pkg_postrm` should always have a package name override. For example, use `RDEPENDS_${PN}` for the main package instead of `RDEPENDS`. BitBake uses more strict checks when it parses recipes.

### Build Behavior

Differences include the following:

- Shared State Code: The shared state code has been optimized to avoid running unnecessary tasks. For example, the following no longer populates the target sysroot since that is not necessary:

           $ bitbake -c rootfs some-image

  Instead, the system just needs to extract the output package contents, re-create the packages, and construct the root filesystem. This change is unlikely to cause any problems unless you have missing declared dependencies.

- Scanning Directory Names: When scanning for files in `SRC_URI`, the build system now uses `FILESOVERRIDES` instead of `OVERRIDES` for the directory names. In general, the values previously in `OVERRIDES` are now in `FILESOVERRIDES` as well. However, if you relied upon an additional value you previously added to `OVERRIDES`, you might now need to add it to `FILESOVERRIDES` unless you are already adding it through the `MACHINEOVERRIDES` or `DISTROOVERRIDES` variables, as appropriate. For more related changes, see the "Variables" section.

### Proxies and Fetching Source

A new `oe-git-proxy` script has been added to replace previous methods of handling proxies and fetching source from Git. See the `meta-yocto/conf/site.conf.sample` file for information on how to use this script.

### Custom Interfaces File (netbase change)

If you have created your own custom `etc/network/interfaces` file by creating an append file for the `netbase` recipe, you now need to create an append file for the `init-ifupdown` recipe instead, which you can find in the Source Directory at `meta/recipes-core/init-ifupdown`. For information on how to use append files, see the "Using .bbappend Files" in the Yocto Project Development Manual.

### Remote Debugging

Support for remote debugging with the Eclipse IDE is now separated into an image feature (`eclipse-debug`) that corresponds to the `packagegroup-core-eclipse-debug` package group. Previously, the debugging feature was included through the `tools-debug` image feature, which corresponds to the `packagegroup-core-tools-debug` package group.

### Variables

The following variables have changed:

- `SANITY_TESTED_DISTROS`: This variable now uses a distribution ID, which is composed of the host distributor ID followed by the release. Previously, `SANITY_TESTED_DISTROS` was composed of the description field. For example, "Ubuntu 12.10" becomes "Ubuntu-12.10". You do not need to worry about this change if you are not specifically setting this variable, or if you are specifically setting it to "".

- `SRC_URI`: The `${` `PN` `}`, `${` `PF` `}`, `${` `P` `}`, and `FILE_DIRNAME` directories have been dropped from the default value of the `FILESPATH` variable, which is used as the search path for finding files referred to in `SRC_URI`. If you have a recipe that relied upon these directories, which would be unusual, then you will need to add the appropriate paths within the recipe or, alternatively, rearrange the files. The most common locations are still covered by `${BP}`, `${BPN}`, and "files", which all remain in the default value of `FILESPATH`.

### Target Package Management with RPM

If runtime package management is enabled and the RPM backend is selected, Smart is now installed for package download, dependency resolution, and upgrades instead of Zypper. For more information on how to use Smart, run the following command on the target:

         smart --help

### Recipes Moved

The following recipes were moved from their previous locations because they are no longer used by anything in the OpenEmbedded-Core:

- `clutter-box2d`: Now resides in the `meta-oe` layer.

- `evolution-data-server`: Now resides in the `meta-gnome` layer.

- `gthumb`: Now resides in the `meta-gnome` layer.

- `gtkhtml2`: Now resides in the `meta-oe` layer.

- `gupnp`: Now resides in the `meta-multimedia` layer.

- `gypsy`: Now resides in the `meta-oe` layer.

- `libcanberra`: Now resides in the `meta-gnome` layer.

- `libgdata`: Now resides in the `meta-gnome` layer.

- `libmusicbrainz`: Now resides in the `meta-multimedia` layer.

- `metacity`: Now resides in the `meta-gnome` layer.

- `polkit`: Now resides in the `meta-oe` layer.

- `zeroconf`: Now resides in the `meta-networking` layer.

### Removals and Renames

The following list shows what has been removed or renamed:

- `evieext`: Removed because it has been removed from `xserver` since 2008.

- Gtk+ DirectFB: Removed support because upstream Gtk+ no longer supports it as of version 2.18.

- `libxfontcache / xfontcacheproto`: Removed because they were removed from the Xorg server in 2008.

- `libxp / libxprintapputil / libxprintutil / printproto`: Removed because the XPrint server was removed from Xorg in 2008.

- `libxtrap / xtrapproto`: Removed because their functionality was broken upstream.

- linux-yocto 3.0 kernel: Removed with linux-yocto 3.8 kernel being added. The linux-yocto 3.2 and linux-yocto 3.4 kernels remain as part of the release.

- `lsbsetup`: Removed with functionality now provided by `lsbtest`.

- `matchbox-stroke`: Removed because it was never more than a proof-of-concept.

- `matchbox-wm-2 / matchbox-theme-sato-2`: Removed because they are not maintained. However, `matchbox-wm` and `matchbox-theme-sato` are still provided.

- `mesa-dri`: Renamed to `mesa`.

- `mesa-xlib`: Removed because it was no longer useful.

- `mutter`: Removed because nothing ever uses it and the recipe is very old.

- `orinoco-conf`: Removed because it has become obsolete.

- `update-modules`: Removed because it is no longer used. The kernel module `postinstall` and `postrm` scripts can now do the same task without the use of this script.

- `web`: Removed because it is not maintained. Superseded by `web-webkit`.

- `xf86bigfontproto`: Removed because upstream it has been disabled by default since 2007. Nothing uses `xf86bigfontproto`.

- `xf86rushproto`: Removed because its dependency in `xserver` was spurious and it was removed in 2005.

- `zypper / libzypp / sat-solver`: Removed and been functionally replaced with Smart (`python-smartpm`) when RPM packaging is used and package management is enabled on the target.

## Moving to the Yocto Project 1.5 Release

This section provides migration information for moving to the Yocto Project 1.5 Release from the prior release.

### Host Dependency Changes

The OpenEmbedded build system now has some additional requirements on the host system:

- Python 2.7.3+

- Tar 1.24+

- Git 1.7.8+

- Patched version of Make if you are using 3.82. Most distributions that provide Make 3.82 use the patched version.

If the Linux distribution you are using on your build host does not provide packages for these, you can install and use the Buildtools tarball, which provides an SDK-like environment containing them.

For more information on this requirement, see the "Required Git, tar, and Python Versions" section.

### `atom-pc` Board Support Package (BSP)

The `atom-pc` hardware reference BSP has been replaced by a `genericx86` BSP. This BSP is not necessarily guaranteed to work on all x86 hardware, but it will run on a wider range of systems than the `atom-pc` did.

Additionally, a `genericx86-64` BSP has been added for 64-bit Atom systems.

### BitBake

The following changes have been made that relate to BitBake:

- BitBake now supports a `_remove` operator. The addition of this operator means you will have to rename any items in recipe space (functions, variables) whose names currently contain `_remove_` or end with `_remove` to avoid unexpected behavior.

- BitBake's global method pool has been removed. This method is not particularly useful and led to clashes between recipes containing functions that had the same name.

- The "none" server backend has been removed. The "process" server backend has been serving well as the default for a long time now.

- The `bitbake-runtask` script has been removed.

- `${` `P` `}` and `${` `PF` `}` are no longer added to `PROVIDES` by default in `bitbake.conf`. These version-specific `PROVIDES` items were seldom used. Attempting to use them could result in two versions being built simultaneously rather than just one version due to the way BitBake resolves dependencies.

### QA Warnings

The following changes have been made to the package QA checks:

- If you have customized `ERROR_QA` or `WARN_QA` values in your configuration, check that they contain all of the issues that you wish to be reported. Previous Yocto Project versions contained a bug that meant that any item not mentioned in `ERROR_QA` or `WARN_QA` would be treated as a warning. Consequently, several important items were not already in the default value of `WARN_QA`. All of the possible QA checks are now documented in the "`insane.bbclass`" section.

- An additional QA check has been added to check if `/usr/share/info/dir` is being installed. Your recipe should delete this file within `do_install` if "make install" is installing it.

- If you are using the buildhistory class, the check for the package version going backwards is now controlled using a standard QA check. Thus, if you have customized your `ERROR_QA` or `WARN_QA` values and still wish to have this check performed, you should add "version-going-backwards" to your value for one or the other variables depending on how you wish it to be handled. See the documented QA checks in the "`insane.bbclass`" section.

### Directory Layout Changes

The following directory changes exist:

- Output SDK installer files are now named to include the image name and tuning architecture through the `SDK_NAME` variable.

- Images and related files are now installed into a directory that is specific to the machine, instead of a parent directory containing output files for multiple machines. The `DEPLOY_DIR_IMAGE` variable continues to point to the directory containing images for the current `MACHINE` and should be used anywhere there is a need to refer to this directory. The `runqemu` script now uses this variable to find images and kernel binaries and will use BitBake to determine the directory. Alternatively, you can set the `DEPLOY_DIR_IMAGE` variable in the external environment.

- When buildhistory is enabled, its output is now written under the Build Directory rather than `TMPDIR`. Doing so makes it easier to delete `TMPDIR` and preserve the build history. Additionally, data for produced SDKs is now split by `IMAGE_NAME`.

- The `pkgdata` directory produced as part of the packaging process has been collapsed into a single machine-specific directory. This directory is located under `sysroots` and uses a machine-specific name (i.e. `tmp/sysroots/machine/pkgdata`).

### Shortened Git `SRCREV` Values

BitBake will now shorten revisions from Git repositories from the normal 40 characters down to 10 characters within `SRCPV` for improved usability in path and file names. This change should be safe within contexts where these revisions are used because the chances of spatially close collisions is very low. Distant collisions are not a major issue in the way the values are used.

### `IMAGE_FEATURES`

The following changes have been made that relate to `IMAGE_FEATURES`:

- The value of `IMAGE_FEATURES` is now validated to ensure invalid feature items are not added. Some users mistakenly add package names to this variable instead of using `IMAGE_INSTALL` in order to have the package added to the image, which does not work. This change is intended to catch those kinds of situations. Valid `IMAGE_FEATURES` are drawn from `PACKAGE_GROUP` definitions, `COMPLEMENTARY_GLOB` and a new "validitems" varflag on `IMAGE_FEATURES`. The "validitems" varflag change allows additional features to be added if they are not provided using the previous two mechanisms.

- The previously deprecated "apps-console-core" `IMAGE_FEATURES` item is no longer supported. Add "splash" to `IMAGE_FEATURES` if you wish to have the splash screen enabled, since this is all that apps-console-core was doing.

### `/run`

The `/run` directory from the Filesystem Hierarchy Standard 3.0 has been introduced. You can find some of the implications for this change here. The change also means that recipes that install files to `/var/run` must be changed. You can find a guide on how to make these changes here.

### Removal of Package Manager Database Within Image Recipes

The image `core-image-minimal` no longer adds `remove_packaging_data_files` to `ROOTFS_POSTPROCESS_COMMAND`. This addition is now handled automatically when "package-management" is not in `IMAGE_FEATURES`. If you have custom image recipes that make this addition, you should remove the lines, as they are not needed and might interfere with correct operation of postinstall scripts.

### Images Now Rebuild Only on Changes Instead of Every Time

The `do_rootfs` and other related image construction tasks are no longer marked as "nostamp". Consequently, they will only be re-executed when their inputs have changed. Previous versions of the OpenEmbedded build system always rebuilt the image when requested rather when necessary.

### Task Recipes

The previously deprecated `task.bbclass` has now been dropped. For recipes that previously inherited from this class, you should rename them from `task-*` to `packagegroup-*` and inherit packagegroup instead.

For more information, see the "`packagegroup.bbclass`" section.

### BusyBox

By default, we now split BusyBox into two binaries: one that is suid root for those components that need it, and another for the rest of the components. Splitting BusyBox allows for optimization that eliminates the `tinylogin` recipe as recommended by upstream. You can disable this split by setting `BUSYBOX_SPLIT_SUID` to "0".

### Automated Image Testing

A new automated image testing framework has been added through the `testimage.bbclass` class. This framework replaces the older `imagetest-qemu` framework.

You can learn more about performing automated image tests in the "Performing Automated Runtime Testing" section.

### Build History

Following are changes to Build History:

- Installed package sizes: `installed-package-sizes.txt` for an image now records the size of the files installed by each package instead of the size of each compressed package archive file.

- The dependency graphs (`depends*.dot`) now use the actual package names instead of replacing dashes, dots and plus signs with underscores.

- The `buildhistory-diff` and `buildhistory-collect-srcrevs` utilities have improved command-line handling. Use the `--help` option for each utility for more information on the new syntax.

For more information on Build History, see the "Maintaining Build Output Quality" section.

### `udev`

Following are changes to `udev`:

- `udev` no longer brings in `udev-extraconf` automatically through `RRECOMMENDS`, since this was originally intended to be optional. If you need the extra rules, then add `udev-extraconf` to your image.

- `udev` no longer brings in `pciutils-ids` or `usbutils-ids` through `RRECOMMENDS`. These are not needed by `udev` itself and removing them saves around 350KB.

### Removed and Renamed Recipes

- The `linux-yocto` 3.2 kernel has been removed.

- `libtool-nativesdk` has been renamed to `nativesdk-libtool`.

- `tinylogin` has been removed. It has been replaced by a suid portion of Busybox. See the "BusyBox" section for more information.

- `external-python-tarball` has been renamed to `buildtools-tarball`.

- `web-webkit` has been removed. It has been functionally replaced by `midori`.

- `imake` has been removed. It is no longer needed by any other recipe.

- `transfig-native` has been removed. It is no longer needed by any other recipe.

- `anjuta-remote-run` has been removed. Anjuta IDE integration has not been officially supported for several releases.

### Other Changes

Following is a list of short entries describing other changes:

- `run-postinsts`: Make this generic.

- `base-files`: Remove the unnecessary `media/`xxx directories.

- `alsa-state`: Provide an empty `asound.conf` by default.

- `classes/image`: Ensure `BAD_RECOMMENDATIONS` supports pre-renamed package names.

- `classes/rootfs_rpm`: Implement `BAD_RECOMMENDATIONS` for RPM.

- `systemd`: Remove `systemd_unitdir` if `systemd` is not in `DISTRO_FEATURES`.

- `systemd`: Remove `init.d` dir if `systemd` unit file is present and `sysvinit` is not a distro feature.

- `libpam`: Deny all services for the `OTHER` entries.

- `image.bbclass`: Move `runtime_mapping_rename` to avoid conflict with `multilib`. See `YOCTO #4993` in Bugzilla for more information.

- `linux-dtb`: Use kernel build system to generate the `dtb` files.

- `kern-tools`: Switch from guilt to new `kgit-s2q` tool.

## Moving to the Yocto Project 1.6 Release

This section provides migration information for moving to the Yocto Project 1.6 Release from the prior release.

### `archiver` Class

The `archiver` class has been rewritten and its configuration has been simplified. For more details on the source archiver, see the "Maintaining Open Source License Compliance During Your Product's Lifecycle" section in the Yocto Project Development Manual.

### Packaging Changes

The following packaging changes have been made:

- The `binutils` recipe no longer produces a `binutils-symlinks` package. `update-alternatives` is now used to handle the preferred `binutils` variant on the target instead.

- The tc (traffic control) utilities have been split out of the main `iproute2` package and put into the `iproute2-tc` package.

- The `gtk-engines` schemas have been moved to a dedicated `gtk-engines-schemas` package.

- The `armv7a` with thumb package architecture suffix has changed. The suffix for these packages with the thumb optimization enabled is "t2" as it should be. Use of this suffix was not the case in the 1.5 release. Architecture names will change within package feeds as a result.

### BitBake

The following changes have been made to BitBake.

#### Matching Branch Requirement for Git Fetching

When fetching source from a Git repository using `SRC_URI`, BitBake will now validate the `SRCREV` value against the branch. You can specify the branch using the following form:

         SRC_URI = "git://server.name/repository;branch=branchname"

If you do not specify a branch, BitBake looks in the default "master" branch.

Alternatively, if you need to bypass this check (e.g. if you are fetching a revision corresponding to a tag that is not on any branch), you can add ";nobranch=1" to the end of the URL within `SRC_URI`.

#### Python Definition substitutions

BitBake had some previously deprecated Python definitions within its `bb` module removed. You should use their sub-module counterparts instead:

- `bb.MalformedUrl`: Use `bb.fetch.MalformedUrl`.

- `bb.encodeurl`: Use `bb.fetch.encodeurl`.

- `bb.decodeurl`: Use `bb.fetch.decodeurl`

- `bb.mkdirhier`: Use `bb.utils.mkdirhier`.

- `bb.movefile`: Use `bb.utils.movefile`.

- `bb.copyfile`: Use `bb.utils.copyfile`.

- `bb.which`: Use `bb.utils.which`.

- `bb.vercmp_string`: Use `bb.utils.vercmp_string`.

- `bb.vercmp`: Use `bb.utils.vercmp`.

#### SVK Fetcher

The SVK fetcher has been removed from BitBake.

#### Console Output Error Redirection

The BitBake console UI will now output errors to `stderr` instead of `stdout`. Consequently, if you are piping or redirecting the output of `bitbake` to somewhere else, and you wish to retain the errors, you will need to add `2>&1` (or something similar) to the end of your `bitbake` command line.

#### `task-`taskname Overrides

`task-`taskname overrides have been adjusted so that tasks whose names contain underscores have the underscores replaced by hyphens for the override so that they now function properly. For example, the task override for `do_populate_sdk` is `task-populate-sdk`.

### Changes to Variables

The following variables have changed. For information on the OpenEmbedded build system variables, see the "Variables Glossary" Chapter.

#### `TMPDIR`

`TMPDIR` can no longer be on an NFS mount. NFS does not offer full POSIX locking and inode consistency and can cause unexpected issues if used to store `TMPDIR`.

The check for this occurs on startup. If `TMPDIR` is detected on an NFS mount, an error occurs.

#### `PRINC`

The `PRINC` variable has been deprecated and triggers a warning if detected during a build. For `PR` increments on changes, use the PR service instead. You can find out more about this service in the "Working With a PR Service" section in the Yocto Project Development Manual.

#### `IMAGE_TYPES`

The "sum.jffs2" option for `IMAGE_TYPES` has been replaced by the "jffs2.sum" option, which fits the processing order.

#### `COPY_LIC_MANIFEST`

The `COPY_LIC_MANIFEST` variable must now be set to "1" rather than any value in order to enable it.

#### `COPY_LIC_DIRS`

The `COPY_LIC_DIRS` variable must now be set to "1" rather than any value in order to enable it.

#### `PACKAGE_GROUP`

The `PACKAGE_GROUP` variable has been renamed to `FEATURE_PACKAGES` to more accurately reflect its purpose. You can still use `PACKAGE_GROUP` but the OpenEmbedded build system produces a warning message when it encounters the variable.

#### Preprocess and Post Process Command Variable Behavior

The following variables now expect a semicolon separated list of functions to call and not arbitrary shell commands:

         ROOTFS_PREPROCESS_COMMAND
         ROOTFS_POSTPROCESS_COMMAND
         SDK_POSTPROCESS_COMMAND
         POPULATE_SDK_POST_TARGET_COMMAND
         POPULATE_SDK_POST_HOST_COMMAND
         IMAGE_POSTPROCESS_COMMAND
         IMAGE_PREPROCESS_COMMAND
         ROOTFS_POSTUNINSTALL_COMMAND
         ROOTFS_POSTINSTALL_COMMAND

For migration purposes, you can simply wrap shell commands in a shell function and then call the function. Here is an example:

         my_postprocess_function() {
            echo "hello" > ${IMAGE_ROOTFS}/hello.txt
         }
         ROOTFS_POSTPROCESS_COMMAND += "my_postprocess_function; "

### Package Test (ptest)

Package Tests (ptest) are built but not installed by default. For information on using Package Tests, see the "Setting up and running package test (ptest)" section in the Yocto Project Development Manual. For information on the `ptest` class, see the "`ptest.bbclass`" section.

### Build Changes

Separate build and source directories have been enabled by default for selected recipes where it is known to work (a whitelist) and for all recipes that inherit the `cmake` class. In future releases the `autotools` class will enable a separate build directory by default as well. Recipes building Autotools-based software that fails to build with a separate build directory should be changed to inherit from the `autotools-brokensep` class instead of the `autotools` or `autotools_stage`classes.

### `qemu-native`

`qemu-native` now builds without SDL-based graphical output support by default. The following additional lines are needed in your `local.conf` to enable it:

         PACKAGECONFIG_pn-qemu-native = "sdl"
         ASSUME_PROVIDED += "libsdl-native"

The default `local.conf` contains these statements. Consequently, if you are building a headless system and using a default `local.conf` file, you will need comment these two lines out.

### `core-image-basic`

`core-image-basic` has been renamed to `core-image-full-cmdline`.

In addition to `core-image-basic` being renamed, `packagegroup-core-basic` has been renamed to `packagegroup-core-full-cmdline` to match.

### Licensing

The top-level `LICENSE` file has been changed to better describe the license of the various components of OE-Core. However, the licensing itself remains unchanged.

Normally, this change would not cause any side-effects. However, some recipes point to this file within `LIC_FILES_CHKSUM` (as `${COREBASE}/LICENSE`) and thus the accompanying checksum must be changed from 3f40d7994397109285ec7b81fdeb3b58 to 4d92cd373abda3937c2bc47fbc49d690. A better alternative is to have `LIC_FILES_CHKSUM` point to a file describing the license that is distributed with the source that the recipe is building, if possible, rather than pointing to `${COREBASE}/LICENSE`.

### `CFLAGS` Options

The "-fpermissive" option has been removed from the default `CFLAGS` value. You need to take action on individual recipes that fail when building with this option. You need to either patch the recipes to fix the issues reported by the compiler, or you need to add "-fpermissive" to `CFLAGS` in the recipes.

### Custom Image Output Types

Custom image output types, as selected using `IMAGE_FSTYPES`, must declare their dependencies on other image types (if any) using a new `IMAGE_TYPEDEP` variable.

### Tasks

The `do_package_write` task has been removed. The task is no longer needed.

### `update-alternative` Provider

The default `update-alternatives` provider has been changed from `opkg` to `opkg-utils`. This change resolves some troublesome circular dependencies. The runtime package has also been renamed from `update-alternatives-cworth` to `update-alternatives-opkg`.

### `virtclass` Overrides

The `virtclass` overrides are now deprecated. Use the equivalent class overrides instead (e.g. `virtclass-native` becomes `class-native`.)

### Removed and Renamed Recipes

The following recipes have been removed:

- `packagegroup-toolset-native` - This recipe is largely unused.

- `linux-yocto-3.8` - Support for the Linux yocto 3.8 kernel has been dropped. Support for the 3.10 and 3.14 kernels have been added with the `linux-yocto-3.10` and `linux-yocto-3.14` recipes.

- `ocf-linux` - This recipe has been functionally replaced using `cryptodev-linux`.

- `genext2fs` - `genext2fs` is no longer used by the build system and is unmaintained upstream.

- `js` - This provided an ancient version of Mozilla's javascript engine that is no longer needed.

- `zaurusd` - The recipe has been moved to the `meta-handheld` layer.

- `eglibc 2.17` - Replaced by the `eglibc 2.19` recipe.

- `gcc 4.7.2` - Replaced by the now stable `gcc 4.8.2`.

- `external-sourcery-toolchain` - this recipe is now maintained in the `meta-sourcery` layer.

- `linux-libc-headers-yocto 3.4+git` - Now using version 3.10 of the `linux-libc-headers` by default.

- `meta-toolchain-gmae` - This recipe is obsolete.

- `packagegroup-core-sdk-gmae` - This recipe is obsolete.

- `packagegroup-core-standalone-gmae-sdk-target` - This recipe is obsolete.

### Removed Classes

The following classes have become obsolete and have been removed:

- `module_strip`

- `pkg_metainfo`

- `pkg_distribute`

- `image-empty`

### Reference Board Support Packages (BSPs)

The following reference BSPs changes occurred:

- The BeagleBoard (`beagleboard`) ARM reference hardware has been replaced by the BeagleBone (`beaglebone`) hardware.

- The RouterStation Pro (`routerstationpro`) MIPS reference hardware has been replaced by the EdgeRouter Lite (`edgerouter`) hardware.

The previous reference BSPs for the `beagleboard` and `routerstationpro` machines are still available in a new `meta-yocto-bsp-old` layer in the Source Repositories at http://git.yoctoproject.org/cgit/cgit.cgi/meta-yocto-bsp-old/.

## Moving to the Yocto Project 1.7 Release

This section provides migration information for moving to the Yocto Project 1.7 Release from the prior release.

### Changes to Setting QEMU `PACKAGECONFIG` Options in `local.conf`

The QEMU recipe now uses a number of `PACKAGECONFIG` options to enable various optional features. The method used to set defaults for these options means that existing `local.conf` files will need to be be modified to append to `PACKAGECONFIG` for `qemu-native` and `nativesdk-qemu` instead of setting it. In other words, to enable graphical output for QEMU, you should now have these lines in `local.conf`:

         PACKAGECONFIG_append_pn-qemu-native = " sdl"
         PACKAGECONFIG_append_pn-nativesdk-qemu = " sdl"

### Minimum Git version

The minimum Git version required on the build host is now 1.7.8 because the `--list` option is now required by BitBake's Git fetcher. As always, if your host distribution does not provide a version of Git that meets this requirement, you can use the `buildtools-tarball` that does. See the "Required Git, tar, and Python Versions" section for more information.

### Autotools Class Changes

The following `autotools` class changes occurred:

- A separate build directory is now used by default: The `autotools` class has been changed to use a directory for building (`B`), which is separate from the source directory (`S`). This is commonly referred to as `B != S`, or an out-of-tree build.

  If the software being built is already capable of building in a directory separate from the source, you do not need to do anything. However, if the software is not capable of being built in this manner, you will need to either patch the software so that it can build separately, or you will need to change the recipe to inherit the `autotools-brokensep` class instead of the `autotools` or `autotools_stage` classes.

- The `--foreign` option is no longer passed to `automake` when running `autoconf`: This option tells `automake` that a particular software package does not follow the GNU standards and therefore should not be expected to distribute certain files such as `ChangeLog`, `AUTHORS`, and so forth. Because the majority of upstream software packages already tell `automake` to enable foreign mode themselves, the option is mostly superfluous. However, some recipes will need patches for this change. You can easily make the change by patching `configure.ac` so that it passes "foreign" to `AM_INIT_AUTOMAKE()`. See this commit for an example showing how to make the patch.

### Binary Configuration Scripts Disabled

Some of the core recipes that package binary configuration scripts now disable the scripts due to the scripts previously requiring error-prone path substitution. Software that links against these libraries using these scripts should use the much more robust `pkg-config` instead. The list of recipes changed in this version (and their configuration scripts) is as follows:

         directfb (directfb-config)
         freetype (freetype-config)
         gpgme (gpgme-config)
         libassuan (libassuan-config)
         libcroco (croco-6.0-config)
         libgcrypt (libgcrypt-config)
         libgpg-error (gpg-error-config)
         libksba (ksba-config)
         libpcap (pcap-config)
         libpcre (pcre-config)
         libpng (libpng-config, libpng16-config)
         libsdl (sdl-config)
         libusb-compat (libusb-config)
         libxml2 (xml2-config)
         libxslt (xslt-config)
         ncurses (ncurses-config)
         neon (neon-config)
         npth (npth-config)
         pth (pth-config)
         taglib (taglib-config)

Additionally, support for `pkg-config` has been added to some recipes in the previous list in the rare cases where the upstream software package does not already provide it.

### `eglibc 2.19` Replaced with `glibc 2.20`

Because `eglibc` and `glibc` were already fairly close, this replacement should not require any significant changes to other software that links to `eglibc`. However, there were a number of minor changes in `glibc 2.20` upstream that could require patching some software (e.g. the removal of the `_BSD_SOURCE` feature test macro).

`glibc 2.20` requires version 2.6.32 or greater of the Linux kernel. Thus, older kernels will no longer be usable in conjunction with it.

For full details on the changes in `glibc 2.20`, see the upstream release notes here.

### Kernel Module Autoloading

The `module_autoload_*` variable is now deprecated and a new `KERNEL_MODULE_AUTOLOAD` variable should be used instead. Also, `module_conf_*` must now be used in conjunction with a new `KERNEL_MODULE_PROBECONF` variable. The new variables no longer require you to specify the module name as part of the variable name. This change not only simplifies usage but also allows the values of these variables to be appropriately incorporated into task signatures and thus trigger the appropriate tasks to re-execute when changed. You should replace any references to `module_autoload_*` with `KERNEL_MODULE_AUTOLOAD`, and add any modules for which `module_conf_*` is specified to `KERNEL_MODULE_PROBECONF`.

For more information, see the `KERNEL_MODULE_AUTOLOAD` and `KERNEL_MODULE_PROBECONF` variables.

### QA Check Changes

The following changes have occurred to the QA check process:

- Additional QA checks `file-rdeps` and `build-deps` have been added in order to verify that file dependencies are satisfied (e.g. package contains a script requiring `/bin/bash`) and build-time dependencies are declared, respectively. For more information, please see the "QA Error and Warning Messages" chapter.

- Package QA checks are now performed during a new `do_package_qa` task rather than being part of the `do_package` task. This allows more parallel execution. This change is unlikely to be an issue except for highly customized recipes that disable packaging tasks themselves by marking them as `noexec`. For those packages, you will need to disable the `do_package_qa` task as well.

- Files being overwritten during the `do_populate_sysroot` task now trigger an error instead of a warning. Recipes should not be overwriting files written to the sysroot by other recipes. If you have these types of recipes, you need to alter them so that they do not overwrite these files.

  You might now receive this error after changes in configuration or metadata resulting in orphaned files being left in the sysroot. If you do receive this error, the way to resolve the issue is to delete your `TMPDIR` or to move it out of the way and then re-start the build. Anything that has been fully built up to that point and does not need rebuilding will be restored from the shared state cache and the rest of the build will be able to proceed as normal.

### Removed Recipes

The following recipes have been removed:

- `x-load`: This recipe has been superseded by U-boot SPL for all Cortex-based TI SoCs. For legacy boards, the `meta-ti` layer, which contains a maintained recipe, should be used instead.

- `ubootchart`: This recipe is obsolete. A `bootchart2` recipe has been added to functionally replace it.

- `linux-yocto 3.4`: Support for the linux-yocto 3.4 kernel has been dropped. Support for the 3.10 and 3.14 kernels remains, while support for version 3.17 has been added.

- `eglibc` has been removed in favor of `glibc`. See the "`eglibc 2.19` Replaced with `glibc 2.20`" section for more information.

### Miscellaneous Changes

The following miscellaneous change occurred:

- The build history feature now writes `build-id.txt` instead of `build-id`. Additionally, `build-id.txt` now contains the full build header as printed by BitBake upon starting the build. You should manually remove old "build-id" files from your existing build history repositories to avoid confusion. For information on the build history feature, see the "Maintaining Build Output Quality" section.

## Moving to the Yocto Project 1.8 Release

This section provides migration information for moving to the Yocto Project 1.8 Release from the prior release.

### Removed Recipes

The following recipes have been removed:

- `owl-video`: Functionality replaced by `gst-player`.

- `gaku`: Functionality replaced by `gst-player`.

- `gnome-desktop`: This recipe is now available in `meta-gnome` and is no longer needed.

- `gsettings-desktop-schemas`: This recipe is now available in `meta-gnome` and is no longer needed.

- `python-argparse`: The `argparse` module is already provided in the default Python distribution in a package named `python-argparse`. Consequently, the separate `python-argparse` recipe is no longer needed.

- `telepathy-python, libtelepathy, telepathy-glib, telepathy-idle, telepathy-mission-control`: All these recipes have moved to `meta-oe` and are consequently no longer needed by any recipes in OpenEmbedded-Core.

- `linux-yocto_3.10` and `linux-yocto_3.17`: Support for the linux-yocto 3.10 and 3.17 kernels has been dropped. Support for the 3.14 kernel remains, while support for 3.19 kernel has been added.

- `poky-feed-config-opkg`: This recipe has become obsolete and is no longer needed. Use `distro-feed-config` from `meta-oe` instead.

- `libav 0.8.x`: `libav 9.x` is now used.

- `sed-native`: No longer needed. A working version of `sed` is expected to be provided by the host distribution.

### BlueZ 4.x / 5.x Selection

Proper built-in support for selecting BlueZ 5.x in preference to the default of 4.x now exists. To use BlueZ 5.x, simply add "bluez5" to your `DISTRO_FEATURES` value. If you had previously added append files (`*.bbappend`) to make this selection, you can now remove them.

Additionally, a `bluetooth` class has been added to make selection of the appropriate bluetooth support within a recipe a little easier. If you wish to make use of this class in a recipe, add something such as the following:

         inherit bluetooth
         PACKAGECONFIG ??= "${@bb.utils.contains('DISTRO_FEATURES', 'bluetooth', '${BLUEZ}', '', d)}
         PACKAGECONFIG[bluez4] = "--enable-bluetooth,--disable-bluetooth,bluez4"
         PACKAGECONFIG[bluez5] = "--enable-bluez5,--disable-bluez5,bluez5"

### Kernel Build Changes

The kernel build process was changed to place the source in a common shared work area and to place build artifacts separately in the source code tree. In theory, migration paths have been provided for most common usages in kernel recipes but this might not work in all cases. In particular, users need to ensure that `${S}` (source files) and `${B}` (build artifacts) are used correctly in functions such as `do_configure` and `do_install`. For kernel recipes that do not inherit from `kernel-yocto` or include `linux-yocto.inc`, you might wish to refer to the `linux.inc` file in the `meta-oe` layer for the kinds of changes you need to make. For reference, here is the commit where the `linux.inc` file in `meta-oe` was updated.

Recipes that rely on the kernel source code and do not inherit the module classes might need to add explicit dependencies on the `do_shared_workdir` kernel task, for example:

         do_configure[depends] += "virtual/kernel:do_shared_workdir"

### SSL 3.0 is Now Disabled in OpenSSL

SSL 3.0 is now disabled when building OpenSSL. Disabling SSL 3.0 avoids any lingering instances of the POODLE vulnerability. If you feel you must re-enable SSL 3.0, then you can add an append file (`*.bbappend`) for the `openssl` recipe to remove "-no-ssl3" from `EXTRA_OECONF`.

### Default Sysroot Poisoning

`gcc's` default sysroot and include directories are now "poisoned". In other words, the sysroot and include directories are being redirected to a non-existent location in order to catch when host directories are being used due to the correct options not being passed. This poisoning applies both to the cross-compiler used within the build and to the cross-compiler produced in the SDK.

If this change causes something in the build to fail, it almost certainly means the various compiler flags and commands are not being passed correctly to the underlying piece of software. In such cases, you need to take corrective steps.

### Rebuild Improvements

Changes have been made to the `base`, `autotools`, and `cmake` classes to clean out generated files when the `do_configure` task needs to be re-executed.

One of the improvements is to attempt to run "make clean" during the `do_configure` task if a `Makefile` exists. Some software packages do not provide a working clean target within their make files. If you have such recipes, you need to set `CLEANBROKEN` to "1" within the recipe, for example:

         CLEANBROKEN = "1"

### QA Check and Validation Changes

The following QA Check and Validation Changes have occurred:

- Usage of `PRINC` previously triggered a warning. It now triggers an error. You should remove any remaining usage of `PRINC` in any recipe or append file.

- An additional QA check has been added to detect usage of `${D}` in `FILES` values where `D` values should not be used at all. The same check ensures that `$D` is used in `pkg_preinst/pkg_postinst/pkg_prerm/pkg_postrm` functions instead of `${D}`.

- `S` now needs to be set to a valid value within a recipe. If `S` is not set in the recipe, the directory is not automatically created. If `S` does not point to a directory that exists at the time the `do_unpack` task finishes, a warning will be shown.

- `LICENSE` is now validated for correct formatting of multiple licenses. If the format is invalid (e.g. multiple licenses are specified with no operators to specify how the multiple licenses interact), then a warning will be shown.

### Miscellaneous Changes

The following miscellaneous changes have occurred:

- The `send-error-report` script now expects a "-s" option to be specified before the server address. This assumes a server address is being specified.

- The `oe-pkgdata-util` script now expects a "-p" option to be specified before the `pkgdata` directory, which is now optional. If the `pkgdata` directory is not specified, the script will run BitBake to query `PKGDATA_DIR` from the build environment.

## Moving to the Yocto Project 2.0 Release

This section provides migration information for moving to the Yocto Project 2.0 Release from the prior release.

### 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. The standard `linux-yocto` kernel source tree already has a workaround for the same issue.

For further details, see and the porting guide at .

Alternatively, you can switch back to GCC 4.9 or 4.8 by setting `GCCVERSION` in your configuration, as follows:

         GCCVERSION = "4.9%"

### 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.

### 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`.

### 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.

### 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`.

### 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.

### Recipe Maintenance Tracking Data Moved to OE-Core

Maintenance tracking data for recipes that was previously part of `meta-yocto` has been moved to 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.

### 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 `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"

### `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 `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.

### 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. `DESCRIPTION`, `SUMMARY`, `LICENSE`, and `SECTION`). Some package managers do not support these characters.

- Added an "invalid-packageconfig" check for any options specified in `PACKAGECONFIG` that do not match any `PACKAGECONFIG` option defined for the recipe.

### Miscellaneous Changes

These additional changes exist:

- `gtk-update-icon-cache` has been renamed to `gtk-icon-utils`.

- The `tools-profile` `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 `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`.

## Moving to the Yocto Project 2.1 Release

This section provides migration information for moving to the Yocto Project 2.1 Release from the prior release.

### Variable Expansion in Python Functions

Variable expressions, such as `${`VARNAME`}` no longer expand automatically within Python functions. Suppressing expansion was done to allow Python functions to construct shell scripts or other code for situations in which you do not want such expressions expanded. For any existing code that relies on these expansions, you need to change the expansions to expand the value of individual variables through `d.getVar()`. To alternatively expand more complex expressions, use `d.expand()`.

### Overrides Must Now be Lower-Case

The convention for overrides has always been for them to be lower-case characters. This practice is now a requirement as BitBake's datastore now assumes lower-case characters in order to give a slight performance boost during parsing. In practical terms, this requirement means that anything that ends up in `OVERRIDES` must now appear in lower-case characters (e.g. values for `MACHINE`, `TARGET_ARCH`, `DISTRO`, and also recipe names if `_pn-`recipename overrides are to be effective).

### Expand Parameter to `getVar()` and `getVarFlag()` is Now Mandatory

The expand parameter to `getVar()` and `getVarFlag()` previously defaulted to False if not specified. Now, however, no default exists so one must be specified. You must change any `getVar()` calls that do not specify the final expand parameter to calls that do specify the parameter. You can run the following `sed` command at the base of a layer to make this change:

         sed -e 's:\(\.getVar([^,()]*\)):\1, False):g' -i `grep -ril getVar *`
         sed -e 's:\(\.getVarFlag([^,()]*, [^,()]*\)):\1, False):g' -i `grep -ril getVarFlag *`

The reason for this change is that it prepares the way for changing the default to True in a future Yocto Project release. This future change is a much more sensible default than False. However, the change needs to be made gradually as a sudden change of the default would potentially cause side-effects that would be difficult to detect.

### Makefile Environment Changes

`EXTRA_OEMAKE` now defaults to "" instead of "-e MAKEFLAGS=". Setting `EXTRA_OEMAKE` to "-e MAKEFLAGS=" by default was a historical accident that has required many classes (e.g. `autotools`, `module`) and recipes to override this default in order to work with sensible build systems. When upgrading to the release, you must edit any recipe that relies upon this old default by either setting `EXTRA_OEMAKE` back to "-e MAKEFLAGS=" or by explicitly setting any required variable value overrides using `EXTRA_OEMAKE`, which is typically only needed when a Makefile sets a default value for a variable that is inappropriate for cross-compilation using the "=" operator rather than the "?=" operator.

### `libexecdir` Reverted to `${prefix}/libexec`

The use of `${libdir}/${BPN}` as `libexecdir` is different as compared to all other mainstream distributions, which either uses `${prefix}/libexec` or `${libdir}`. The use is also contrary to the GNU Coding Standards (i.e. ) that suggest `${prefix}/libexec` and also notes that any package-specific nesting should be done by the package itself. Finally, having `libexecdir` change between recipes makes it very difficult for different recipes to invoke binaries that have been installed into `libexecdir`. The Filesystem Hierarchy Standard (i.e. ) now recognizes the use of `${prefix}/libexec/`, giving distributions the choice between `${prefix}/lib` or `${prefix}/libexec` without breaking FHS.

### `ac_cv_sizeof_off_t` is No Longer Cached in Site Files

For recipes inheriting the `autotools` class, `ac_cv_sizeof_off_t` is no longer cached in the site files for `autoconf`. The reason for this change is because the `ac_cv_sizeof_off_t` value is not necessarily static per architecture as was previously assumed. Rather, the value changes based on whether large file support is enabled. For most software that uses `autoconf`, this change should not be a problem. However, if you have a recipe that bypasses the standard `do_configure` task from the `autotools` class and the software the recipe is building uses a very old version of `autoconf`, the recipe might be incapable of determining the correct size of `off_t` during `do_configure`.

The best course of action is to patch the software as necessary to allow the default implementation from the `autotools` class to work such that `autoreconf` succeeds and produces a working configure script, and to remove the overridden `do_configure` task such that the default implementation does get used.

### Image Generation is Now Split Out from Filesystem Generation

Previously, for image recipes the `do_rootfs` task assembled the filesystem and then from that filesystem generated images. With this Yocto Project release, image generation is split into separate `do_image_*` tasks for clarity both in operation and in the code.

For most cases, this change does not present any problems. However, if you have made customizations that directly modify the `do_rootfs` task or that mention `do_rootfs`, you might need to update those changes. In particular, if you had added any tasks after `do_rootfs`, you should make edits so that those tasks are after the `do_image_complete` task rather than after `do_rootfs` so that the your added tasks run at the correct time.

A minor part of this restructuring is that the post-processing definitions and functions have been moved from the `image` class to the `rootfs-postcommands` class. Functionally, however, they remain unchanged.

### Removed Recipes

The following recipes have been removed in the 2.1 release:

- `gcc` version 4.8: Versions 4.9 and 5.3 remain.

- `qt4`: All support for Qt 4.x has been moved out to a separate `meta-qt4` layer because Qt 4 is no longer supported upstream.

- `x11vnc`: Moved to the `meta-oe` layer.

- `linux-yocto-3.14`: No longer supported.

- `linux-yocto-3.19`: No longer supported.

- `libjpeg`: Replaced by the `libjpeg-turbo` recipe.

- `pth`: Became obsolete.

- `liboil`: Recipe is no longer needed and has been moved to the `meta-multimedia` layer.

- `gtk-theme-torturer`: Recipe is no longer needed and has been moved to the `meta-gnome` layer.

- `gnome-mime-data`: Recipe is no longer needed and has been moved to the `meta-gnome` layer.

- `udev`: Replaced by the `eudev` recipe for compatibility when using `sysvinit` with newer kernels.

- `python-pygtk`: Recipe became obsolete.

- `adt-installer`: Recipe became obsolete. See the "ADT Removed" section for more information.

### Class Changes

The following classes have changed:

- `autotools_stage`: Removed because the `autotools` class now provides its functionality. Recipes that inherited from `autotools_stage` should now inherit from `autotools` instead.

- `boot-directdisk`: Merged into the `image-vm` class. The `boot-directdisk` class was rarely directly used. Consequently, this change should not cause any issues.

- `bootimg`: Merged into the `image-live` class. The `bootimg` class was rarely directly used. Consequently, this change should not cause any issues.

- `packageinfo`: Removed due to its limited use by the Hob UI, which has itself been removed.

### Build System User Interface Changes

The following changes have been made to the build system user interface:

- Hob GTK+-based UI: Removed because it is unmaintained and based on the outdated GTK+ 2 library. The Toaster web-based UI is much more capable and is actively maintained. See the "Using the Toaster Web Interface" section in the Yocto Project Toaster User Manual for more information on this interface.

- "puccho" BitBake UI: Removed because is unmaintained and no longer useful.

### ADT Removed

The Application Development Toolkit (ADT) has been removed because its functionality almost completely overlapped with the standard SDK and the extensible SDK. For information on these SDKs and how to build and use them, see the Yocto Project Software Development Kit (SDK) Developer's Guide.

The Yocto Project Eclipse IDE Plug-in is still supported and is not affected by this change.

### Poky Reference Distribution Changes

The following changes have been made for the Poky distribution:

- The `meta-yocto` layer has been renamed to `meta-poky` to better match its purpose, which is to provide the Poky reference distribution. The `meta-yocto-bsp` layer retains its original name since it provides reference machines for the Yocto Project and it is otherwise unrelated to Poky. References to `meta-yocto` in your `conf/bblayers.conf` should automatically be updated, so you should not need to change anything unless you are relying on this naming elsewhere.

- The `uninative` class is now enabled by default in Poky. This class attempts to isolate the build system from the host distribution's C library and makes re-use of native shared state artifacts across different host distributions practical. With this class enabled, a tarball containing a pre-built C library is downloaded at the start of the build.

  The `uninative` class is enabled through the `meta/conf/distro/include/yocto-uninative.inc` file, which for those not using the Poky distribution, can include to easily enable the same functionality.

  Alternatively, if you wish to build your own `uninative` tarball, you can do so by building the `uninative-tarball` recipe, making it available to your build machines (e.g. over HTTP/HTTPS) and setting a similar configuration as the one set by `yocto-uninative.inc`.

- Static library generation, for most cases, is now disabled by default in the Poky distribution. Disabling this generation saves some build time as well as the size used for build output artifacts.

  Disabling this library generation is accomplished through a `meta/conf/distro/include/no-static-libs.inc`, which for those not using the Poky distribution can easily include to enable the same functionality.

  Any recipe that needs to opt-out of having the "--disable-static" option specified on the configure command line either because it is not a supported option for the configure script or because static libraries are needed should set the following variable:

           DISABLE_STATIC = ""

- The separate `poky-tiny` distribution now uses the musl C library instead of a heavily pared down `glibc`. Using musl results in a smaller distribution and facilitates much greater maintainability because musl is designed to have a small footprint.

  If you have used `poky-tiny` and have customized the `glibc` configuration you will need to redo those customizations with musl when upgrading to the new release.

### Packaging Changes

The following changes have been made to packaging:

- The `runuser` and `mountpoint` binaries, which were previously in the main `util-linux` package, have been split out into the `util-linux-runuser` and `util-linux-mountpoint` packages, respectively.

- The `python-elementtree` package has been merged into the `python-xml` package.

### Tuning File Changes

The following changes have been made to the tuning files:

- The "no-thumb-interwork" tuning feature has been dropped from the ARM tune include files. Because interworking is required for ARM EABI, attempting to disable it through a tuning feature no longer makes sense.

  Support for ARM OABI was deprecated in gcc 4.7.

- The `tune-cortexm*.inc` and `tune-cortexr4.inc` files have been removed because they are poorly tested. Until the OpenEmbedded build system officially gains support for CPUs without an MMU, these tuning files would probably be better maintained in a separate layer if needed.

### Supporting GObject Introspection

This release supports generation of GLib Introspective Repository (GIR) files through GObject introspection, which is the standard mechanism for accessing GObject-based software from runtime environments. You can enable, disable, and test the generation of this data. See the "Enabling GObject Introspection Support" section for more information.

### Miscellaneous Changes

These additional changes exist:

- The minimum Git version has been increased to 1.8.3.1. If your host distribution does not provide a sufficiently recent version, you can install the buildtools, which will provide it. See the "Required Git, tar, and Python Versions" section for more information on the buildtools tarball.

- The buggy and incomplete support for the RPM version 4 package manager has been removed. The well-tested and maintained support for RPM version 5 remains.

- Previously, the following list of packages were removed if package-management was not in `IMAGE_FEATURES`, regardless of any dependencies:

           update-rc.d
           base-passwd
           shadow
           update-alternatives
           run-postinsts

  With the Yocto Project 2.1 release, these packages are only removed if "read-only-rootfs" is in `IMAGE_FEATURES`, since they might still be needed for a read-write image even in the absence of a package manager (e.g. if users need to be added, modified, or removed at runtime).

- The `devtool modify` command now defaults to extracting the source since that is most commonly expected. The "-x" or "--extract" options are now no-ops. If you wish to provide your own existing source tree, you will now need to specify either the "-n" or "--no-extract" options when running `devtool modify`.

- If the formfactor for a machine is either not supplied or does not specify whether a keyboard is attached, then the default is to assume a keyboard is attached rather than assume no keyboard. This change primarily affects the Sato UI.

- The `.debug` directory packaging is now automatic. If your recipe builds software that installs binaries into directories other than the standard ones, you no longer need to take care of setting `FILES_${PN}-dbg` to pick up the resulting `.debug` directories as these directories are automatically found and added.

- Inaccurate disk and CPU percentage data has been dropped from `buildstats` output. This data has been replaced with `getrusage()` data and corrected IO statistics. You will probably need to update any custom code that reads the `buildstats` data.

- The `meta/conf/distro/include/package_regex.inc` is now deprecated. The contents of this file have been moved to individual recipes.

  #### Tip

  Because this file will likely be removed in a future Yocto Project release, it is suggested that you remove any references to the file that might be in your configuration.

- The `v86d/uvesafb` has been removed from the `genericx86` and `genericx86-64` reference machines, which are provided by the `meta-yocto-bsp` layer. Most modern x86 boards do not rely on this file and it only adds kernel error messages during startup. If you do still need to support `uvesafb`, you can simply add `v86d` to your image.

- Build sysroot paths are now removed from debug symbol files. Removing these paths means that remote GDB using an unstripped build system sysroot will no longer work (although this was never documented to work). The supported method to accomplish something similar is to set `IMAGE_GEN_DEBUGFS` to "1", which will generate a companion debug image containing unstripped binaries and associated debug sources alongside the image.

## Moving to the Yocto Project 2.2 Release

This section provides migration information for moving to the Yocto Project 2.2 Release from the prior release.

### 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.

For x86 and x86_64, you can reset `OLDEST_KERNEL` to anything down to 2.6.32 if desired.

### Staging Directories in Sysroot Has Been Simplified

The way directories are staged in sysroot has been simplified and introduces the new `SYSROOT_DIRS`, `SYSROOT_DIRS_NATIVE`, and `SYSROOT_DIRS_BLACKLIST`. See the v2 patch series on the OE-Core Mailing List for additional information.

### 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.

### Python Changes

The following changes for Python occurred:

#### BitBake Now Requires Python 3.4+

BitBake requires Python 3.4 or greater.

#### 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.

#### 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 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

#### 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.

Python 2 and recipes that use it can still be built for the target as with previous versions.

#### `buildtools-tarball` Includes Python 3

`buildtools-tarball` now includes Python 3.

### 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.

### `${B}` No Longer Default Working Directory for Tasks

`${` `B` `}` is no longer the default working directory for tasks. Consequently, any custom tasks you define now need to either have the `[` `dirs` `]` flag set, or the task needs to change into the appropriate working directory manually (e.g using `cd` for a shell task).

The preferred method is to use the `[dirs]` flag.

### `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 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`:

"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 `IMAGE_CLASSES` as follows and run `runqemu`:

For command-line syntax, use `runqemu help`.

         IMAGE_CLASSES += "qemuboot"

### 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 `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}"

### `KERNEL_IMAGE_BASE_NAME` no Longer Uses `KERNEL_IMAGETYPE`

The `KERNEL_IMAGE_BASE_NAME` variable no longer uses the `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.

### 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 `SRCREV` for specifying the source revision to use, be it `${` `AUTOREV` `}`, changelist number, p4date, or label, in preference to separate `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: 1 and 2.

- 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.

### 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.

### 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 entry on Swabber.

- `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`

### Removed Classes

The following classes have been removed:

- `distutils-native-base`: No longer needed.

- `distutils3-native-base`: No longer needed.

- `sdl`: Only set `DEPENDS` and `SECTION`, which are better set within the recipe instead.

- `sip`: Mostly unused.

- `swabber`: See the entry on Swabber.

### 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.

### 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 `SRCREV` by default when fetching from a Git repository. You can override this in either case to use `${` `AUTOREV` `}` instead by using the `-a` or `&dash;&dash;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`.