[RFC DOCUMENT 03/12] kubevirt-and-kvm: Add Hotplug page

https://gitlab.com/abologna/kubevirt-and-kvm/-/blob/master/Hotplug.md # Hotplug In Kubernetes, pods are defined to be immutable, so it's not possible to perform hotplug of devices in the same way as with the traditional virtualization stack. This limitation is a result of KubeVirt's guiding principle of integrating with Kubernetes as much as possible and making VMs appear the same as containers from the user's point of view. There have been several attempts at lifting this restriction in Kubernetes over the years, but they have all been unsuccessful so far. ## Existing hotplug support When working with containers, changing the amount of resources associated with a pod will result in it being destroyed and a new pod with the updated resource allocation being created in its place. This works fine for containers, which are designed to be clonable and disposable, but when it comes to VMs they usually can't be destroyed on a whim and running multiple instances in parallel is generally not wise even when possible. ## Possible workarounds Until a proper hotplug API makes its way into Kubernetes, one possible way to implement hotplug could be to perform migration to a container compliant with the new allocation request, and only then perform the QEMU-level hotplug operation.