Category Archives: CentOS 6

CentOS, CentOS 6, Linux, Linux Kernel, RedHat, Shell Scripting

Installing the default Linux Kernel on a Linode CentOS 6 box

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While creating the new web-server for my employers, to replace a Fedora 10 box which gets no security updates, I needed to compile some software from source, meaning I needed the kernel sources.

Since I couldn’t easily obtain these I needed to install the Kernel provided by the distribution rather than the more recent kernel provided by Linode themselves.

The Linode Library provided a way of doing this for CentOS 5 but not for CentOS 6, thus I adapted the provided script for v5 into one that works with CentOS 6 et voila, distro provided kernel.

Here’s the full source available as a gist on github:

### Starting from a fresh CentOS 6 or newer Linode
### Enable the native kernel to boot from pvgrub
### It will autoconfigure itself with each yum update.
### This is adapted from a previous script for CentOS 5.5 found here:
### http://www.linode.com/docs/assets/542-centos5-native-kernel-selinux-enforcing.sh
### Provided via the linode wiki
### https://www.linode.com/docs/tools-reference/custom-kernels-distros/run-a-distributionsupplied-kernel-with-pvgrub#centos-5
### Provided without warranty, although since it should only be run
### on first box build if your box gets broken simply rebuild it

mkdir /boot/grub/

DISTRO_PLATFORM=`uname -p`
AWK_VERSION_MATCH="{if(\$1==\"kernel.$DISTRO_PLATFORM\") print \$2}"
KERNEL_VERSION=`yum -q list kernel | awk "$AWK_VERSION_MATCH"`

### Write template grub.conf
cat > /boot/grub/grub.conf << EOF
# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE:  You have a /boot partition.  This means that
#          all kernel and initramfs paths are relative to /boot/, eg.
#          root (hd0)
#          kernel /boot/vmlinuz-version ro root=/dev/xvda
#          initrd /boot/initramfs-version.img
#boot=/dev/xvda
default=0
timeout=3
title CentOS ($KERNEL_VERSION.$DISTRO_PLATFORM)
        root (hd0)
        kernel /boot/vmlinuz-$KERNEL_VERSION.$DISTRO_PLATFORM root=/dev/xvda
        initrd /boot/initramfs-$KERNEL_VERSION.$DISTRO_PLATFORM.img
EOF

ln -s /boot/grub/grub.conf /boot/grub/menu.lst
yum -y install kernel
if [ $? -ne 0 ]; then
    echo "ERROR aborting..."
    exit 1
fi