Ubuntu – Why kernel version doesn’t match Ubuntu version in a Docker container

containerdockerkernel

I have a Docker container built from Ubuntu 14.10. When I log in to the container to check the Ubuntu version and kernel version I see the following:

root@~$>> lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 14.10
Release:    14.10
Codename:   utopic   

root@~$>> uname -a
    Linux ambiata-aws 3.13.0-24-generic #47-Ubuntu SMP Fri May 2 23:30:00 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

I thought that Ubuntu 14.10 was supposed to be kernel version 3.16 (as stated here), so why do I have kernel version 3.13.0-24-generic ?

The reason I am asking is because there is a patch in 3.13.0-29-generic that I would like to have (that is, having fallocate working on AUFS in my docker container) which is discussed here.

Best Answer

From What is Docker?:

LIGHTWEIGHT

Containers running on a single machine share the same operating system kernel; they start instantly and use less RAM. Images are constructed from layered filesystems and share common files, making disk usage and image downloads much more efficient.

Containers run on the host OS kernel. In your case, the host could be a Ubuntu 14.04 (running the original kernel) or a Ubuntu 12.04 (running kernel from trusty's hardware enablement stack).

If the host is Ubuntu 14.04 you could install kernel 3.16:

sudo apt-get install linux-generic-lts-utopic

Or kernel 3.19:

sudo apt-get install linux-generic-lts-vivid

For Ubuntu 12.04, kernel 3.13 is latest official one.

Related Solutions

Ubuntu – How to replace ubuntu 20.04 kernel with clearlinux kernel

I don't have specific experience with ClearLinux, but it looks like you can:

# It's best to first compile their gcc (https://github.com/clearlinux-pkgs/gcc)
mkdir ~/patched_source
git clone https://github.com/clearlinux-pkgs/linux ~/clearlinux_patches
cd ~/clearlinux_patches
./scripts/develop.sh linux.spec ~/patched_source

That should download the upstream kernel to a folder below ~/patched_source (it will tell you the exact name) and apply ClearLinux's own patches and default config.

You can then proceed to compile the kernel as usual, for instance:

cd that_folder
CC=/the/clearlinux/gcc make -j4 bindeb-pkg
# This will take a while and create a few linux-xxx.deb files in the parent directory
sudo dpkg -i ../*.deb   # Or just the latest

Disabling the CONFIG_RETPOLINE mitigation makes it possible to compile with Ubuntu's gcc (at a cost, obviously).

The usual warnings apply: try in a VM first, secure boot can be tricky, there might be some Ubuntu-specific patches missing, ...

If you feel adventurous you can also add some of their own cmdline options to /etc/default/grub (like the ones in lines 8-15)

Best Answer

Related Solutions

Ubuntu – How to replace ubuntu 20.04 kernel with clearlinux kernel

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