That's a fun map.

The Linux kernel has more device drivers embedded in the core than I anticipated. I'm guessing most are used for bootstrapping/fallback (e.g. loading the "actual" drivers)? Such as ext4, ipw2100, ac97, i8042, etc.

Just to be clear, I'd imagine most of the above are common enough to have on almost all but the most niche Linux distributions. My question relates around having them this high up in the source tree, rather than why they're useful/what they do.