runuser as it is in wrl6 is not working. It needs a missing pam.d config file.
configure --enable-board=intel-x86-64 --enable-kernel=preempt-rt --enable-rootfs=glibc-std --enable-bootimage=ext3 --enable-rm-oldimgs=yes --with-sstate-dir=../intel-x86-64-sstate/ --enable-jobs=8 --enable-parallel-pkgbuilds=8 --enable-doc-pages=target --with-rcpl-version=0017 make build-all log on target, then : # runuser -l root -c ls runuser: Failure setting user credentials