How to set the default kernel version?

Environment

• Red Hat Enterprise Linux 10
• Red Hat Enterprise Linux 9
• Red Hat Enterprise Linux 8
• Red Hat Enterprise Linux 7

Issue

• How to set the default kernel version?

Resolution

• To set a specific kernel as the default boot entry, use the grubby --set-default <full path to kernel vmlinuz file> command.

  # grubby --set-default /boot/vmlinuz-5.14.0-427.33.1.el9_4.x86_64
  

  Note: The above command set the default kernel to version 5.14.0-427.33.1.el9_4.x86_64, replace the version with the version of the kernel to set as default.

Notes:

• List available kernels on the system using the ls -1 /boot/vmlinuz-* command.
• grubby sets the save_entry value in the /boot/grub2/grubenv file to the specified kernel. For this to work, ensure GRUB_DEFAULT=saved is configured in the /etc/default/grub file.
• After setting the default kernel, reboot the system to boot into the newly configured default kernel.

Diagnostic Steps

• How to check the kernel version in use?
• How to check the default kernel version?
• Why is the system not using the kernel set with grubby?

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