What are the various kernel rpms installed on redhat servers?

vaquitasos

The kernel is made up of a number of files, these files are installed by way of rpm packages on RedHat.

A quick listing of your kernel rpms will show which ones are installed.

$ rpm -qa | grep kernel
kernel-modules-4.18.0-80.4.2.el8_0.x86_64
kernel-core-4.18.0-147.5.1.el8_1.x86_64
kernel-tools-4.18.0-147.5.1.el8_1.x86_64
kernel-modules-4.18.0-147.5.1.el8_1.x86_64
kernel-4.18.0-147.5.1.el8_1.x86_64
kernel-4.18.0-80.4.2.el8_0.x86_64
kernel-tools-libs-4.18.0-147.5.1.el8_1.x86_64
kernel-core-4.18.0-80.4.2.el8_0.x86_64

uname will show version of the kernel is currently running. In this demo 4.18.0-80.4.2.el8_0.x86_64 is being used.

$ uname -a

The main kernel package is called kernel-* Listing more information on this package shows that it is a meta package. It contains no files itself, it tells the OS which kernel rpms to install via scriplets in the meta package.

Display information on the kernel-* rpm.

$ rpm -qi kernel-4.18.0-80.4.2.el8_0.x86_64
Name        : kernel
Version     : 4.18.0
Release     : 80.4.2.el8_0
Architecture: x86_64
Install Date: Tue 18 Jun 2019 05:06:11 PM UTC
Group       : System Environment/Kernel
Size        : 0
License     : GPLv2 and Redistributable, no modification permitted
Signature   : RSA/SHA256, Fri 14 Jun 2019 05:25:20 PM UTC, Key ID 199e2f91fd431d51
Source RPM  : kernel-4.18.0-80.4.2.el8_0.src.rpm
Build Date  : Fri 14 Jun 2019 01:42:33 PM UTC
Build Host  : x86-vm-08.build.eng.bos.redhat.com
Relocations : (not relocatable)
Packager    : Red Hat, Inc. <http://bugzilla.redhat.com/bugzilla>
Vendor      : Red Hat, Inc.
URL         : http://www.kernel.org/
Summary     : The Linux kernel
Description :
The kernel meta package

Listing the files in the meta package kernel-* show it has no files.

$ rpm -ql kernel-4.18.0-80.4.2.el8_0.x86_64
(contains no files)

Redhat descriptions of each of the kernel rpms. Like the example above your installation may not display all the kernel rpms.

kernel-core - contains a minimal number of kernel modules needed for core functionality. This sub-package alone could be used in virtualized and cloud environments to provide a Red Hat Enterprise Linux 8 kernel with a quick boot time and a small disk size footprint.

kernel-modules - contains further kernel modules.

kernel-modules-extra - specialized modules for rare hardware.

The other common kernel packages are for example:

kernel-debug — Contains a kernel with numerous debugging options enabled for kernel diagnosis, at the expense of reduced performance.

kernel-tools — Contains tools for manipulating the Linux kernel and supporting documentation.

kernel-devel — Contains the kernel headers and makefiles sufficient to build modules against the kernel package.

kernel-abi-whitelists — Contains information pertaining to the Red Hat Enterprise Linux kernel ABI, including a list of kernel symbols that are needed by external Linux kernel modules and a yum plug-in to aid enforcement.
kernel-headers — Includes the C header files that specify the interface between the Linux kernel and user-space libraries and programs. The header files define structures and constants that are needed for building most standard programs.