Release 4.3 (nanbield)

Migration notes for 4.3 (nanbield)

This section provides migration information for moving to the Yocto Project 4.3 Release (codename “nanbield”) from the prior release.

Supported kernel versions

The OLDEST_KERNEL setting has been changed to “5.15” in this release, meaning that out the box, older kernels are not supported. There were two reasons for this. Firstly it allows glibc optimisations that improve the performance of the system by removing compatibility code and using modern kernel APIs exclusively. The second issue was this allows 64 bit time support even on 32 bit platforms and resolves Y2038 issues.

It is still possible to override this value and build for older kernels, this is just no longer the default supported configuration. This setting does not affect which kernel versions SDKs will run against and does not affect which versions of the kernel can be used to run builds.

Layername override implications

Code can now know which layer a recipe is coming from through the newly added FILE_LAYERNAME variable and the layer-<layername> override. This is being used for enabling QA checks on a per layer basis. For existing code this has the side effect that the QA checks will apply to recipes being bbappended from other layers - for example, patches added through such bbappends will now need to have the “Upstream-Status” specified in the patch header.

Compiling changes

  • Code on 32 bit platforms is now compiled with largefile support and 64 bit time_t, to avoid the Y2038 time overflow issue. This breaks the ABI and could break existing programs in untested layers.

Supported distributions

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

  • Ubuntu 22.10

  • Fedora 38

  • Debian 12

  • CentOS Stream 8

  • AlmaLinux 8.8

  • AlmaLinux 9.2

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

  • Fedora 36

  • AlmaLinux 8.7

  • AlmaLinux 9.1

See all supported distributions.

edgerouter machine removed

The edgerouter reference BSP for the MIPS architecture in meta-yocto-bsp has been removed as the hardware has been unavailable for some time. There is no suitable reference MIPS hardware to replace it with, but the MIPS architecture will continue to get coverage via QEMU build/boot testing.

Go language changes

  • Support for the Glide package manager has been removed, as go mod has become the standard.

systemd changes

Upstream systemd is now more strict on filesystem layout and the usrmerge feature is therefore required alongside systemd. The Poky test configurations have been updated accordingly for systemd.

Recipe changes

  • Runtime testing of ptest now fails if no test results are returned by any given ptest.

Deprecated variables

The following variables have been deprecated:

Removed variables

The following variables have been removed:




  • QEMU_USE_SLIRP - add slirp to TEST_RUNQEMUPARAMS instead.

  • SERIAL_CONSOLES_CHECK - no longer necessary because all consoles listed in SERIAL_CONSOLES are checked for their existence before a getty is started.

Removed recipes

The following recipes have been removed in this release:

  • apmd: obsolete (apm in MACHINE_FEATURES also removed).

  • cve-update-db-native: functionally replaced by cve-update-nvd2-native

  • gcr3: no longer needed by core recipes, moved to meta-gnome (gcr, i.e. version 4.x, is still provided).

  • glide: as explained in Go language changes.

  • libdmx: obsolete

  • linux-yocto version 5.15 (versions 6.1 and 6.5 provided instead).

  • python3-async: obsolete - no longer needed by python3-gitdb or any other core recipe

  • rust-hello-world: there are sufficient other Rust recipes and test cases such that this is no longer needed.

Removed classes

The following classes have been removed in this release:

Output file naming changes

In 4.3 there are some minor differences in image and SDK output file names. If you rely on the existing naming (e.g. in external scripts) you may need to either modify configuration or adapt to the new naming. Further details:

  • IMAGE_NAME and IMAGE_LINK_NAME now include the IMAGE_NAME_SUFFIX value directly. In practical terms, this means that .rootfs will now appear in image output file names. If you do not wish to have the .rootfs suffix used, you can just set IMAGE_NAME_SUFFIX to “” and this will now be consistently respected in both the image file and image file symlink names. As part of this change, support for the imgsuffix task varflag has been dropped (mostly an internal implementation detail, but if you were implementing a custom image construction with a task in a similar manner to do_bootimg you may have been using this).

  • SDK_NAME now includes the values of IMAGE_BASENAME and MACHINE so that they are unique when building SDKs for different images and machines.

Versioning changes

  • PR values have been removed from all core recipes - distro maintainers who make use of PR values would need to curate these already so the sparsely set base values would not be that useful anymore. If you have been relying on these (i.e. you are maintaining a binary package feed where package versions should only ever increase), double-check the output (perhaps with the help of the buildhistory class) to ensure that package versions are consistent.

  • The PR value can no longer be set from the recipe file name - this was rarely used, but in any case is no longer supported.

  • PE and PR are no longer included in the work directory path (WORKDIR). This may break some tool assumptions about directory paths, but those should really be querying paths from the build system (or not poking into WORKDIR externally).

  • Source revision information has been moved from PV to PKGV. The user visible effect of this change is that PV will no longer have revision information in it and this will now be appended to the PV value through PKGV when the packages are written out (as long as “+” is present in the PKGV value). Since PV is used in STAMP and WORKDIR, you may notice small directory naming and stamp naming changes.

  • The SRCPV variable is no longer needed in PV, but since the default SRCPV value is now “”, using it is effectively now just a null operation - you can remove it (leaving behind the “+”) , but it is not yet required to do so.

QEMU changes

  • The runqemu script no longer systematically adds two serial ports (--serial null and -serial mon:stdio) to the QEMU emulated machine if the user already adds such ports through the QB_OPT_APPEND setting.

    If the user adds one port, only --serial null is added, and -serial mon:stdio is no longer passed. If the user adds more than one port, --serial null is no longer added either. This can break some existing QEMU based configurations expecting such serial ports to be added when runqemu is executed.

    This change was made to avoid exceeding two serial ports, which interferes with automated testing.

  • runqemu now uses the ip tuntap command instead of tunctl, and thus tunctl is no longer built by the qemu-helper-native recipe; if for some reason you were calling tunctl directly from your own scripts you should switch to calling ip tuntap instead.

Miscellaneous changes

  • The -crosssdk suffix and any MLPREFIX were removed from virtual/XXX provider/dependencies where a PREFIX was used as well, as we don’t need both and it made automated dependency rewriting unnecessarily complex. In general this only affects internal toolchain dependencies so isn’t end user visible, but if for some reason you have custom classes or recipes that rely upon the old providers then you will need to update those.