This solves the following error message with Kirkstone:

Bitbake Fetcher Error: FetchError("Recipe uses a floating tag/branch 'rel_1.9.0' for repo 'git.kontron-electronics.de/sw/misc/apps/sparkle.git' without a fixed SRCREV yet doesn't call bb.fetch2.get_srcrev() (use SRCPV in PV for OE).", None)

In the future we will reference the BSP as meta-ked-bsp. Adjust names
of layers, files, etc. accordingly. Only some OE metadata like image,
distro or machine override names are keeping the 'ktn' for now.

KED stands for Kontron Electronics Deutschland GmbH where the BSP
is maintained. Nowadays it support only products of the KED branch
and products of the Kontron Europe GmbH or other branches are not
supported.