As of this Yocto Project release, the x32 psABI kernel and library interfaces specifications are not finalized.
Future Plans for the x32 psABI in the Yocto Project include the following:
Enhance and fix the few remaining recipes so they work with and support x32 toolchains.
Enhance RPM Package Manager (RPM) support for x32 binaries.
Support larger images.
Integrate x32 recipes, toolchain, and kernel changes from
experimental/meta-x32 into OE-core.