Release 4.2 (mickledore)

Migration notes for 4.2 (mickledore)

This section provides migration information for moving to the Yocto Project 4.2 Release (codename “mickledore”) from the prior release.

Supported distributions

This release supports running BitBake on new GNU/Linux distributions:

  • Fedora 36 and 37

  • AlmaLinux 8.7 and 9.1

  • OpenSuse 15.4

On the other hand, some earlier distributions are no longer supported:

  • Debian 10.x

  • Fedora 34 and 35

  • AlmaLinux 8.5

See all supported distributions.

Python 3.8 is now the minimum required Python version version

BitBake and OpenEmbedded-Core now require Python 3.8 or newer, making it a requirement to use a distribution providing at least this version, or to install a buildtools tarball.

gcc 8.0 is now the minimum required GNU C compiler version

This version, released in 2018, is a minimum requirement to build the mesa-native recipe and as the latter is in the default dependency chain when building QEMU this has now been made a requirement for all builds.

In the event that your host distribution does not provide this or a newer version of gcc, you can install a buildtools-extended tarball.

Fetching the NVD vulnerability database through the 2.0 API

This new version adds a new fetcher for the NVD database using the 2.0 API, as the 1.0 API will be retired in 2023.

The implementation changes as little as possible, keeping the current database format (but using a different database file for the transition period), with a notable exception of not using the META table.

Here are minor changes that you may notice:

  • The database starts in 1999 instead of 2002

  • The complete fetch is longer (30 minutes typically)

Rust: mandatory checksums for crates

This release now supports checksums for Rust crates and makes them mandatory for each crate in a recipe. See python3_bcrypt recipe changes for example.

The cargo-update-recipe-crates utility has been extended to include such checksums. So, in case you need to add the list of checksums to a recipe just inheriting the cargo class so far, you can follow these steps:

  1. Make the recipe inherit cargo-update-recipe-crates

  2. Remove all crate:// lines from the recipe

  3. Create an empty ${BPN} file and make your recipe require it

  4. Execute bitbake -c update_crates your_recipe

  5. Copy and paste the output of BitBake about the missing checksums into the ${BPN} file.

Python library code extensions

BitBake in this release now supports a new addpylib directive to enable Python libraries within layers.

This directive should be added to your layer configuration as in the below example from meta/conf/layer.conf:

addpylib ${LAYERDIR}/lib oe

Layers currently adding a lib directory to extend Python library code should now use this directive as BBPATH is not going to be added automatically by OE-Core in future. Note that the directives are immediate operations, so it does make modules available for use sooner than the current BBPATH-based approach.

For more information, see Extending Python Library Code.

Removed variables

The following variables have been removed:

  • SERIAL_CONSOLE, deprecated since version 2.6, replaced by SERIAL_CONSOLES.

  • PACKAGEBUILDPKGD, a mostly internal variable in the ref:ref-classes-package class was rarely used to customise packaging. If you were using this in your custom recipes or bbappends, you will need to switch to using PACKAGE_PREPROCESS_FUNCS or PACKAGESPLITFUNCS instead.

Removed recipes

The following recipes have been removed in this release:

  • python3-picobuild: after switching to python3-build

  • python3-strict-rfc3339: unmaintained and not needed by anything in openembedded-core or meta-openembedded.

  • linux-yocto: removed version 5.19 recipes (6.1 and 5.15 still provided)

Removed classes

The following classes have been removed in this release:

  • rust-bin: no longer used

  • package_tar: could not be used for actual packaging, and thus not particularly useful.

LAYERSERIES_COMPAT for custom layers and devtool workspace

Some layer maintainers have been setting LAYERSERIES_COMPAT in their layer’s conf/layer.conf to the value of LAYERSERIES_CORENAMES to effectively bypass the compatibility check - this is no longer permitted. Layer maintainers should set LAYERSERIES_COMPAT appropriately to help users understand the compatibility status of the layer.

Additionally, the LAYERSERIES_COMPAT value for the devtool workspace layer is now set at the time of creation, thus if you upgrade with the workspace layer enabled and you wish to retain it, you will need to manually update the LAYERSERIES_COMPAT value in workspace/conf/layer.conf (or remove the path from BBLAYERS in conf/bblayers.conf and delete/move the workspace directory out of the way if you no longer need it).

runqemu now limits slirp host port forwarding to localhost

With default slirp port forwarding configuration in runqemu, qemu previously listened on TCP ports 2222 and 2323 on all IP addresses available on the build host. Most use cases with runqemu only need it for localhost and it is not safe to run qemu images with root login without password enabled and listening on all available, possibly Internet reachable network interfaces. Thus, in this release we limit qemu port forwarding to localhost (

However, if you need the qemu machine to be reachable from the network, then it can be enabled via conf/local.conf or machine config variable QB_SLIRP_OPT:

QB_SLIRP_OPT = "-netdev user,id=net0,hostfwd=tcp::2222-:22"

Patch QA checks

The QA checks for patch fuzz and Upstream-Status have been reworked slightly in this release. The Upstream-Status checking is now configurable from WARN_QA / ERROR_QA (patch-status-core for the core layer, and patch-status-noncore for other layers).

The patch-fuzz and patch-status-core checks are now in the default value of ERROR_QA so that they will cause the build to fail if triggered. If you prefer to avoid this you will need to adjust the value of ERROR_QA in your configuration as desired.

Native/nativesdk mesa usage and graphics drivers

This release includes mesa 23.0, and with that mesa release it is not longer possible to use drivers from the host system, as mesa upstream has added strict checks for matching builds between drivers and libraries that load them.

This is particularly relevant when running QEMU built within the build system. A check has been added to runqemu so that there is a helpful error when there is no native/nativesdk opengl/virgl support available.

To support this, a number of drivers have been enabled when building mesa-native. The one major dependency pulled in by this change is llvm-native which will add a few minutes to the build on a modern machine. If this is undesirable, you can set the value of DISTRO_FEATURES_NATIVE in your configuration such that opengl is excluded.

Miscellaneous changes

  • The IMAGE_NAME variable is now set based on IMAGE_LINK_NAME. This means that if you are setting IMAGE_LINK_NAME to “” to disable unversioned image symlink creation, you also now need to set IMAGE_NAME to still have a reasonable value e.g.:

  • In /etc/os-release, the VERSION_CODENAME field is now used instead of DISTRO_CODENAME (though its value is still set from the DISTRO_CODENAME variable) for better conformance to standard os-release usage. If you have runtime code reading this from /etc/os-release it may need to be updated.

  • The kmod recipe now enables OpenSSL support by default in order to support module signing. If you do not need this and wish to reclaim some space/avoid the dependency you should set PACKAGECONFIG in a kmod bbappend (or PACKAGECONFIG:pn-kmod at the configuration level) to exclude openssl.

  • The OEBasic signature handler (see BB_SIGNATURE_HANDLER) has been removed. It is unlikely that you would have selected to use this, but if you have you will need to remove this setting.

  • The package class now checks if package names conflict via PKG:${PN} override during do_package. If you receive the associated error you will need to address the PKG usage so that the conflict is resolved.

  • openssh no longer uses RRECOMMENDS to pull in rng-tools, since rngd is no longer needed as of Linux kernel 5.6. If you still need rng-tools installed for other reasons, you should add rng-tools explicitly to your image. If you additionally need rngd to be started as a service you will also need to add the rng-tools-service package as that has been split out.

  • The cups recipe no longer builds with the web interface enabled, saving ~1.8M of space in the final image. If you wish to enable it, you should set PACKAGECONFIG in a cups bbappend (or PACKAGECONFIG:pn-cups at the configuration level) to include webif.

  • The scons class now passes a MAXLINELENGTH argument to scons in order to fix an issue with scons and command line lengths when ccache is enabled. However, some recipes may be using older scons versions which don’t support this argument. If that is the case you can set the following in the recipe in order to disable this: