[openstack-dev] [infra][neutron] - best way to load 8021q kernel module into cirros

Scott Moser smoser at ubuntu.com
Tue Aug 16 13:35:23 UTC 2016

On Mon, 8 Aug 2016, Jeremy Stanley wrote:

> On 2016-08-08 11:20:54 +0200 (+0200), Miguel Angel Ajo Pelayo wrote:
> > The problem with the other projects image builds is that they are
> > based for bigger systems, while cirros is an embedded-device-like
> > image which boots in a couple of seconds.
> Yep, smaller is certainly better when it comes to trying to run Nova
> in a virtual machine.
> > Couldn't we contribute to cirros to have such module load by default [1]?
> It's worth chatting with them, for sure, and see what they say about
> it.

Kevin opened a bug at
I responded with a one option that we could pursue to avoid others having
to build their own images.
The suggestion was to provide a command line utility in inside cirros that
would download additional kernel modules.  Then, user-data could be fed to
instruct it to do so.  That would allow you to keep using unmodified
cirros kernels and initramfs.

Another option would be for cirros to provide other ways to patch itself
to your needs.  For example, the injected files support in nova could be
used to insert the necessary modules.  The difficulty there is that then
you're dependent upon knowing what version of the kernel is inside the

Another option is for cirros to simply include those modules by default.
That comes at the cost of 100k or so.  Its not a huge thing, but its
definitely an increase.

We can work something out.


> > Or may be it's time for Openstack to build their own "cirros-like"
> > image with all the capabilities we may be missing for general tempest
> > testing? (ipv6, vlan, etc..? )
> I haven't personally tested the CirrOS build instructions, but have
> a feeling writing a diskimage-builder element wrapper for that
> wouldn't be particularly challenging.

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