Document how to add kernel params

[agracey]

It would be nice to have it documented how to change the kernel params for a system both before installation (via MachineRegistraion) as well on an existing system.

[agracey]

Editing on a running system is less important as any kernel params should be known in advanced but mistakes happen so it would be nice to not require re-imaging

[Itxaka]

I think this is covered by https://rancher.github.io/elemental-toolkit/docs/customizing/configure_grub/ and https://rancher.github.io/elemental-toolkit/docs/customizing/runtime_persistent_changes/

Before installation (The iso boot params) I dont think its possible unless you create your own derivative as we ship a default bootargs.cfg that contains the default kernel params from elemental-toolkit.

[kkaempf]

Not sure it the elemental-toolkit is the best place for it. The current node-image doesn't use elemental-toolkit at all. 🤔

Does the "elemental" documentation link to the "elemental-toolkit" docs ?

[Itxaka]

Doesnt use any scripts from cos-toolkit? Where does the inmutability comes from? Where does the grub stuff comes from? Its all from the toolkit, and you can get the persistence enabled for root by setting the params provided in those docs.

Not that I dont agree with this, we dont have a proper way of passing extra cloud-configs or other args properly currently. But this card is about docs more than implementation. Implementation wise it probably requires some changes to how we consume, but we can currently do what is asked by following the docs.

See how c3os does it via cloud-init: https://github.com/c3os-io/c3os/blob/master/overlay/files/system/oem/21_grub.yaml

[kkaempf]

Closing as of #224 (comment)
Follow up: rancher/elemental-toolkit#1773