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Applies to SUSE Linux Enterprise Server 11 SP4

12 Installing Multiple Kernel Versions

SUSE Linux Enterprise Server supports the parallel installation of multiple kernel versions. When installing a second kernel, a boot entry and an initrd are automatically created, so no further manual configuration is needed. When rebooting the machine, the newly added kernel is available as an additional boot option.

Using this functionality, you can safely test kernel updates while being able to always fall back to the proven former kernel. To do so, do not use the update tools (such as the YaST Online Update or the updater applet), but instead follow the process described in this chapter.

Warning: Support Entitlement

Please be aware that you loose your entire support entitlement for the machine when installing a self-compiled or a third-party kernel. Only kernels shipped with SUSE Linux Enterprise Server and kernels delivered via the official update channels for SUSE Linux Enterprise Server are supported.

Tip: Check Your Bootloader Configuration Kernel

It is recommended to check your boot loader config after having installed another kernel in order to set the default boot entry of your choice. See Section 11.2, “Configuring the Boot Loader with YaST” for more information. To change the default append line for new kernel installations, adjust /etc/sysconfig/bootloader prior to installing a new kernel. For more information refer to Section 11.1.4, “The File /etc/sysconfig/bootloader.

12.1 Enabling and Configuring Multiversion Support

Installing multiple versions of a software package (multiversion support) is not enabled by default. To enable this feature, proceed as follows:

  1. Open /etc/zypp/zypp.conf with the editor of your choice as root.

  2. Search for the string multiversion. To enable multiversion for all kernel packages capable of this feature, uncomment the following line

    # multiversion = provides:multiversion(kernel)
  3. To restrict multiversion support to certain kernel flavors, add the package names as a comma-separated list, to the multiversion option in /etc/zypp/zypp.conf—for example

    multiversion = kernel-default,kernel-default-base,kernel-source
  4. Save your changes.

12.1.1 Automatically Deleting Unused Kernels

When frequently testing new kernels with multiversion support enabled, the boot menu quickly becomes confusing. Since a /boot usually has got limited space you also might run into trouble with /boot overflowing. While you may delete unused kernel versions manually with YaST or Zypper (as described below), you can also configure libzypp to automatically delete kernels no longer used. By default no kernels are deleted.

  1. Open /etc/zypp/zypp.conf with the editor of your choice as root.

  2. Search for the string multiversion.kernels and activate this option by uncommenting the line. This option takes a comma separated list of the following values keep the kernel with the specified version number

    latest keep the kernel with the highest version number

    latest-N keep the kernel with the Nth highest version number

    running keep the running kernel

    oldest keep the kernel with the lowest version number (the one that was originally shipped with SUSE Linux Enterprise Server)

    oldest+N keep the kernel with the Nth lowest version number

    Here are some examples

    multiversion.kernels = latest,running

    Keep the latest kernel and the one currently running one. This is similar to not enabling the multiversion feature at all, except that the old kernel is removed after the next reboot and not immediately after the installation.

    multiversion.kernels = latest,latest-1,running

    Keep the last two kernels and the one currently running.

    multiversion.kernels = latest,running,3.0.rc7-test

    Keep the latest kernel, the one currently running and 3.0.rc7-test.

    Tip: Keep the running Kernel

    Unless using special setups, you probably always want to keep the running kernel.

12.2 Installing/Removing Multiple Kernel Versions with YaST

  1. Start YaST and open the software manager via Software › Software Mannagment.

  2. List all packages capable of providing multiple versions by choosing View › Package Groups › Multiversion Packages.

    The YaST Software Manager - Multiversion View
    Figure 12.1: The YaST Software Manager - Multiversion View
  3. Select a package and open its Version tab in the bottom pane on the left.

  4. To install a package, click its check box. A green check mark indicates it is selected for installation.

    To remove an already installed package (marked with a white check mark), click its check box until a red X indicates it is selected for removal.

  5. Click Accept to start the installation.

12.3 Installing/Removing Multiple Kernel Versions with zypper

  1. Use the command zypper se -s 'kernel*' to display a list of all kernel packages available:

    S | Name           | Type       | Version         | Arch   | Repository        
    v | kernel-default | package    | | x86_64 | Alternative Kernel
    i | kernel-default | package    |  | x86_64 | (System Packages) 
      | kernel-default | srcpackage | | noarch | Alternative Kernel
    i | kernel-default | package    |  | x86_64 | (System Packages)
  2. Specify the exact version when installing:

    zypper in kernel-default-
  3. When uninstalling a kernel, use the commands zypper se -si 'kernel*' to list all kernels installed and zypper rm PACKAGENAME-VERSION to remove the package.

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