Ubuntu 12.04 - Install the 3.8 kernel

Update

This tutorial is deprecated ever since Ubuntu 14.04 came out. Readers should upgrade to the Trusty Tahr kernel instead, or deploy a new 14.04 server.

To update to 14.04's kernel, run the following commands.

sudo apt-get install linux-image-generic-lts-trusty linux-headers-generic-lts-trusty
sudo reboot

You may want to use the "revert" section below to remove the older kernel(s).

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Many services, such as Amazon Web Services, will deploy Ubuntu 12.04 with the paravirtual 3.2 (Xen) based kernel rather than use the 3.8 generic kernel. This is because paravirtual images perform better than generic ones on a hypervisor. I only mention Xen because AFAIK, paravirtualization is Xen specific (i.e. you won't find it on a KVM based provider). However, you meay need to install the 3.8 kernel in order to run things like Docker or BTRFS. Luckily, this is very easy to do:

Install the kernel

sudo apt-get install linux-image-generic-lts-raring linux-headers-generic-lts-raring

Reboot

sudo reboot

With Amazon Web Services, your EC2 instance will still be listed as "paravirtual" although it is now actually not if the original AMI you deployed from was a paravirtual instance.

Reverting

If you ever want to undo this and go back to the 3.2 kernel, just run the following commands:

sudo apt-get purge linux-image-3.8.*
sudo update-grub
sudo reboot

References

• Xen Project- Paravirtualization
• Stack Overflow - lxc-attach failed to enter the namespace - EC2 Instances
• LinuxG.net - How To Install Kernel 3.5 / Kernel 3.8 On Ubuntu 12.04