# 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.

## 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 rising from too many files in the same directory. Also, native sstate-cache packages 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 or Hob 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 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 "Package Groups - 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, `bitbake -c rootfs some-image` from shared state no longer populates the target sysroot since that is not necessary. 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 1.7.5+

- 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 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 a 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 task, you should rename them from `task-*` to `packagegroup-*` and inherit packagegroup instead.

For more information, see the "Package Groups - `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 `&dash;&dash;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.