After a kernel update Z-Series boots into the previous kernel

This document (000020342) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 12
SUSE Linux Enterprise Server 15

Situation

Only valid for SUSE Linux Enterprise for Z-Series!

A system is updated with a new kernel, but after restarting the system, the old kernel is booted again.
In case of enabled secure boot, booting even fails if the new kernel is signed with a new signing key.

Resolution

Besides the usual grub2 and initrd reinstall, zipl also must be updated to have a record of the new kernel version.
There is a secure way to achieve that.
NOTE: the following immediately boots into the new kernel which interrupts running applications and unmounts all volumes!

1) install new kernel
2) run: 'grub2-emu --kexec' # this calls the grub2 boot menu, there choose the new kernel to reboot
3) repeat step #2 # safety net
4) run: 'update-bootloader --reinit' # this reinstalls the bootloader in all necessary places

Step #4 can be replaced by running 'yast bootloader' but that requires that the new kernel is already booted, like above with 'grub2-emu --kexec'

Cause

Z-Series is special and the above is necessary because the "stage 1" zipl kernel and its initrd are not updated when a kernel update is made.

Status

Reported to Engineering

Additional Information

SUSE Engineering and IBM are aware of the issue but there is not ETA yet for a resolution

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.