Chapter 42. Using a specific kernel version in RHEL

The kernel is a core component of a Linux operating system that manages the system resources, and provides the interface between hardware and software applications. In some cases, the kernel might affect the network functionality so it is always recommended to use the latest version of the kernel. If required, it is also possible to downgrade the kernel version to a previous version of the same x-stream kernel and select specific version while system boot-up for troubleshooting.

This section explains how to select a kernel in the GRUB boot loader in case you upgrade or downgrade the kernel.

42.1. Starting RHEL using a previous kernel version

By default, after you update, the system boots the latest version of the kernel. Red Hat Enterprise Linux allows to have three kernel versions installed at the same time. This is defined in the /etc/dnf/dnf.conf file (installonly_limit=3).

If you observe any issues when the system is loaded with the new kernel, you can reboot it with the previous kernel and restore the production machine. Contact support for troubleshooting the issue.

Procedure

  1. Start the system.
  2. In the GRUB boot loader, you see the installed kernels. Use the and keys to select a kernel, and press Enter to boot it.

Additional resources