I think this Android Source is a great documentation for understanding it.
And here is a list of changes done from mainline kernel for android kernel 4.14.
The largest features include:
- 19.8% Energy Aware Scheduling (kernel/sched)
- 13.8% Networking (net/netfilter)
- 13.5% Sdcardfs (fs/sdcardfs)
- 9.4% USB (drivers/usb)
- 7.2% SoC (arch/arm64, arch/x86)
- 6.2% f2fs (fs/f2fs -- backports from upstream)
- 6.1% Input (drivers/input/misc)
- 5.4% FIQ Debugger (drivers/staging/android/fiq_debugger)
- 3.6% Goldfish Emulator (drivers/platform/goldfish)
- 3.4% Verity (drivers/md)
- 11.6% Other
Differences from LTS
When compared to LTS (4.14.0), the Android common kernel has 355 changes, 32266 insertions, and 1546 deletions (as of February 2018).
