There is a bug in the installer of Red Hat Enterprise Linux 6 which results in one or more
invalid records added to zipl.conf if kernel-kdump package was part of the 
initial installation.  If these invalid records persist, the system may not
be able to boot into upgraded Red Hat Enterprise Linux 7.

Review the zipl.conf file and remove the invalid
records manually. Otherwise, redhat-upgrade-tool will attempt to remove
them.
