Use the Distribution-Supplied Kernel on CentOS 6 with Grub Legacy

Updated by Nick Brewer

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This guide will show you how to install and use the distribution-supplied kernel for CentOS 6, with our Grub Legacy boot option.

Before you get started, make sure you follow the steps outlined in our Getting Started guide. Your Linode needs to be in a functional state. These steps should be performed as root on your Linode, via an SSH session.

This guide is intended for Linodes running on our KVM hypervisor. For older Xen Linodes, see this guide.

Install the Kernel and Configure Grub

  1. Make sure your package repositories and installed packages are up to date by issuing the following command:

    yum update
  2. Issue the following command to install the default kernel for CentOS6:

    yum install kernel.x86_64
  3. View the content of your /boot directory, and take note of the kernel version number and the name of your initramfs file:

     ls -la /boot
     total 20972
     dr-xr-xr-x  4 root root     4096 Mar 10 18:26 .
     dr-xr-xr-x 22 root root     4096 Mar 10 18:20 ..
     -rw-r--r--  1 root root   108108 Feb 24 14:37 config-2.6.32-642.15.1.el6.x86_64
     drwxr-xr-x  3 root root     4096 Mar 10 18:24 efi
     drwxr-xr-x  2 root root     4096 Mar 10 18:26 grub
     -rw-------  1 root root 14230393 Mar 10 18:24 initramfs-2.6.32-642.15.1.el6.x86_64.img
     -rw-r--r--  1 root root   215528 Feb 24 14:37 symvers-2.6.32-642.15.1.el6.x86_64.gz
     -rw-r--r--  1 root root  2618573 Feb 24 14:37
     -rwxr-xr-x  1 root root  4270000 Feb 24 14:37 vmlinuz-2.6.32-642.15.1.el6.x86_64
     -rw-r--r--  1 root root      171 Feb 24 14:37 .vmlinuz-2.6.32-642.15.1.el6.x86_64.hmac

    In this example, you would grab the kernel version that is appended to the vmlinuz file - 2.6.32-642.15.1.el6.x86_64. You’d also take down the full name of the initramfs file, in this case initramfs-2.6.32-642.15.1.el6.x86_64.img.

  4. Create a file named /boot/grub/menu.lst with the following contents. Adjust the kernel, and initrd lines to reflect the actual file names found in the /boot/ directory.

    timeout 5
    title CentOS 6
    root (hd0)
    kernel /boot/vmlinuz-2.6.32-431.23.3.el6.x86_64 root=/dev/sda console=ttyS0,19200n8
    initrd /boot/initramfs-2.6.32-431.23.3.el6.x86_64.img
  5. In the Linode Manager, edit your Linode’s configuration profile by selecting the Grub (Legacy) option within the Kernel drop-down menu.

  6. Make sure the root device is specified as /dev/sda, and click Save Profile at the bottom of the page to confirm your changes.

  7. Reboot your Linode from the Dashboard tab. Once your Linode has rebooted, log in via SSH and issue the following command:

     uname -a

    You should see output similar to the following, indicating you’re running the native kernel:

     Linux 2.6.32-642.15.1.el6.x86_64 #1 SMP Fri Feb 24 14:31:22 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

This guide is published under a CC BY-ND 4.0 license.