One upside of kernel modules: you can build a very small kernel without having a ton of features. If you actually need the xbox one controller support - you can enable the module. Really useful on small footprint devices.

The only downside is that the kernel doesn't have a stable API, so the open source code of kernel modules becomes gradually more useless if not actively maintained as it won't compile against the kernel headers anymore requiring more and more work to fix.

The Xbox One driver is also in a kernel module: xpad.ko.

Got it. So some kernel modules are "official" and part of the release notes?

90% of all modules in existence are part of the official kernel release. So, as they ship in the same bundle, they also use the same release note.

Some kernel modules may not be distributed as part of the kernel for license compatibility reasons, or just by preference of the authors. In some cases they may only be distributed in binary form, with an open-source "wrapper" that is compiled to match your local kernel, like nvidia video drivers.

Also worth mentioning is that large amounts of the linux kernel can be either 'built-in' or built 'as modules'- I think most distros prefer modules where possible.

Run shell command 'lsmod' to see all the modules you currently have loaded, and check out the .ko files under '/lib/modules' to see the modules provided.