Kernel Upgrade Introduction

In this KB, we will see how to upgrade the kernel on Red Hat Linux Enterprise systems.  We will show you how to perform a automated upgrades of the kernel using the yum and rpm package management tools.

Before continuing on, a word of caution.  I recommend avoiding kernel updates unless absolutely necessary.  Generally speaking, if it's not broke, don't try and fix it.  So unless there is a vulnerability or lack of hardware/driver support in the currently installed kernel on your system, I would recommend against the installation of a new/updated kernel.  Installing a new kernel could have wide spread and unknown consequences to your system and/or might not be supported by your hardware/installed software.  Now that I got that off my chest, I'll get off my soapbox so we can get to work!

Kernel Upgrade/Update on Red Hat Enterprise Linux

Red Hat use a combination of tools such as yum for package retrieval and rpm for package management.  If you system is registered with the Red Hat Network (RHN), yum will automatically download and resolve dependencies for rpm based installs.  If you system is not registered with RHN, you can still upgrade the kernel, but you will have to manually resolve any dependencies (downloading and installing any dependent rpms.)  Yum will connect to the RHN (Red Hat Network) and scan the repository for updated packages (including your kernel.)  If there are updates available, yum will resolve their dependencies and mark the additional packages for download/installation.  Once yum has downloaded all the package(s), it will begin installing the packages using rpm (this will configure and register the package with the OS.)

1. Before we can use yum, we must first register the server with the RHN (Red Hat Network).
   
   Note: If you registered your OS at the time of installation, you can skip this step
   
   Begin the registration process
   

   [root@RHEL01 ~]# rhn_register

   
   You'll be presented with a screen similar to the following, click Next to continue:
   
   
   Enter your login information for the Red Hat Network (RHN) and click Next:
   
   
   Enter a profile name for the server and click Next:
   
   
   Leave the defaults selected and click Next:
   
   
   Click Next on the Send Profile page:
   
   
   Your system's information will be sent/registered with the Red Hat Network (RHN):
   
   
   Click OK on the subscription details page:
   
   
   Click Finish to complete the registration with the RHN:
   
   
   
   
2. Check to see if there are updates available for the system
   
   Check for updates to the kernel package only:
   

   [root@RHEL01 ~]# yum check-update kernel Loaded plugins: rhnplugin kernel.x86_64 2.6.18-128.1.14.el5 rhel-x86_64-server-5 root@ubuntu:~#

   Note: If there are no updates available, no output will be produced
   
   Or
   
   Check for all packages (including the kernel):
   

   [root@RHEL01 ~]# yum check-update Loading "installonlyn" plugin Loading "rhnplugin" plugin Setting up repositories rhel-x86_64-server-5 100% |=========================| 1.3 kB 00:00 Reading repository metadata in from local files primary.xml.gz 100% |=========================| 2.3 MB 00:01 ################################################## 7019/7019 Deployment_Guide-en-US.noarch 5.2-11 rhel-x86_64-serv NetworkManager.x86_64 1:0.7.0-4.el5_3 rhel-x86_64-serv ORBit2.x86_64 2.14.3-5.el5 rhel-x86_64-serv OUTPUT TRUNCATED kernel.x86_64 2.6.18-128.1.14.el5 rhel-x86_64-serv kernel-headers.x86_64 2.6.18-128.1.14.el5 rhel-x86_64-serv OUTPUT TRUNCATED [root@Linux01 rhn]#

   Note: yum returns a list of all available packages
   
   
3. A quick check of the system reveals we are running on v2.6.18-8.el5 of the Linux kernel
   
   

   [root@RHEL01 ~]# rpm -qi kernel Name : kernel Relocations : (not relocatable) Version : 2.6.18 Vendor : Red Hat, Inc. Release : 8.el5 Build Date : Fri 26 Jan 2007 02:47:08 PM EST Install Date : Wed 24 Jun 2009 8:50:56 AM EDT Build Host : ls20-bc1-14.build.redhat.com Group : System Environment/Kernel Source RPM : kernel-2.6.18-8.el5.src.rpm Size : 75875879 License : GPLv2 Signature : DSA/SHA1, Fri 26 Jan 2007 09:12:24 PM EST, Key ID 5326810137017186 Packager : Red Hat, Inc. <http://bugzilla.redhat.com/bugzilla> Summary : The Linux kernel (the core of the Linux operating system) Description : The kernel package contains the Linux kernel (vmlinuz), the core of any Linux operating system.  The kernel handles the basic functions of the operating system:  memory allocation, process allocation, device input and output, etc. [root@RHEL01 ~

   
   
   

   [root@RHEL01 ~]# uname -a Linux RHEL01 2.6.18-8.el5 #1 SMP Fri Jan 26 14:15:14 EST 2007 x86_64 x86_64 x86_64 GNU/Linux [root@RHEL01 ~]#

   
   
4. Install the new kernel using yum
   
   Update the kernel package only:
   

   [root@RHEL01 ~]# yum update kernel Loading "rhnplugin" plugin Setting up Update Process Resolving Dependencies --> Running transaction check ---> Package kernel.x86_64 0:2.6.18-128.1.14.el5 set to be installed --> Finished Dependency Resolution . Dependencies Resolved ========================================================== Package Arch Version Repository Size ========================================================== Installing: kernel x86_64 2.6.18-128.1.14.el5 rhel-x86_64-server-5 17 M . Transaction Summary ========================================================== Install 1 Package(s) Update 0 Package(s) Remove 0 Package(s) . Total download size: 17 M Is this ok [y/N]: y

   
   Or
   
   Update all packages including the kernel:
   

   [root@RHEL01 ~]# yum update Loading "installonlyn" plugin Loading "rhnplugin" plugin Setting up Update Process Setting up repositories rhel-x86_64-server-5 100% |=========================| 1.3 kB 00:00 Reading repository metadata in from local files primary.xml.gz 100% |=========================| 2.3 MB 00:01 ################################################## 7019/7019 Resolving Dependencies --> Populating transaction set with selected packages. Please wait. ---> Downloading header for redhat-lsb to pack into transaction set. redhat-lsb-3.1-12.3.EL.x8 100% |=========================| 12 kB 00:00 ---> Package redhat-lsb.x86_64 0:3.1-12.3.EL set to be updated OUTPUT TRUNCATED . Transaction Summary ========================================================== Install 33 Package(s) Update 270 Package(s) Remove 0 Package(s) . Total download size: 255 M Is this ok [y/N]: y

   Note: There may also be other available packages that need updating on the system (as seen above.)  Yum should take care of the kernel as well as any other packages and associated dependencies on the system.
   
   After answering yes to the continue question, yum will pull all the new packages and their dependencies from the RHN repository.  It will then configure them, and update your boot loader to use the new kernel (requires a reboot).
   
   
5. The new kernel is now installed and ready for use.  Reboot the system to boot into the new kernel image
   
   

   [root@RHEL01 ~]# init 6

   
   
6. Once the system has come back up, login and verify your running from the new kernel image
   
   

   [root@RHEL01 ~]# uname -a Linux REHL01 2.6.18-128.1.14.el5 #1 SMP Mon Jun 1 15:52:58 EDT 2009 x86_64 x86_64 x86_64 GNU/Linux [root@RHEL01 ~]#

   
   

Good luck on the kernel upgrade!

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Kiran |24/09/2009 04:16:09 Excellent. very detailed and nice article. Thank you very much Tom. Reply | Quote

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