This document provides a step-by-step guide on modifying kernel configurations, handling module configurations, managing boot partitions, and updating/removing kernel packages in Red Hat Enterprise Linux (RHEL) 8.

Step 1: Modify the /etc/modprobe.d/CIS.conf File

Objective:

Remove the line that disables the vfat module to allow it to load properly.

Procedure:

1. Open the configuration file using a text editor: vi /etc/modprobe.d/CIS.conf
2. Locate the following line and remove it: install vfat /bin/true
3. Save and exit the file:
   • Press Esc
   • Type :wq
   • Press Enter
4. Verify if the vfat module can now be loaded: modprobe -vvv vfat If successful, the output should indicate that vfat.ko.xz is loaded.

Step 2: Mount /dev/sda1 on /boot/efi

Objective:

Ensure that the EFI boot partition is correctly mounted.

Procedure:

1. Mount the partition manually: mount /dev/sda1 /boot/efi
2. Verify that the partition is mounted: mount | grep /boot/efi

Step 3: Remove an Old Kernel Version

Objective:

Remove an outdated or conflicting kernel version.

Procedure:

1. Remove the old kernel version: yum remove kernel-4.18.0-553.30.1.el8_10.x86_64 kernel-core-4.18.0-553.30.1.el8_10.x86_64
2. Resolve any dependency issues if prompted.
3. Confirm the removal by selecting y when prompted.
4. Verify that the old kernel is removed: rpm -qa | grep kernel

Step 4: Modify /etc/fstab to Ensure Persistent EFI Mounting

Objective:

Ensure that the EFI partition mounts at boot.

Procedure:

1. Edit the fstab file: vi /etc/fstab
2. Locate the following line and ensure it is uncommented: UUID=0B3E-F61B /boot/efi vfat umask=0077,shortname=winnt 0 2
3. Save and exit the file.
4. Apply the changes: systemctl daemon-reload

Step 5: Reinstall the Kernel

Objective:

Reinstall the desired kernel version.

Procedure:

1. Install the required kernel packages: yum install kernel-4.18.0-513.18.1.el8_9.x86_64 kernel-core-4.18.0-513.18.1.el8_9.x86_64
2. Confirm installation by selecting y when prompted.
3. Verify the installation: rpm -qa | grep kernel

Step 6: Reboot the System

Objective:

Apply all changes and ensure the system boots with the correct kernel.

Procedure:

1. Reboot the server: reboot
2. After reboot, confirm the active kernel version: uname -r It should return: 4.18.0-513.18.1.el8_9.x86_64

Conclusion

This document outlines the process of modifying module configurations, handling kernel updates, and ensuring a stable boot configuration in RHEL 8. Proper execution of these steps ensures a well-functioning system with minimal downtime.