I've maintained an internal fork of "hostapd" tool. We needed a bunch of additional WiFi features and in some places different behavior due to hardware architec

I've maintained an internal fork of "hostapd" tool. We needed a bunch of additional WiFi features and in some places different behavior due to hardware architecture. Initially it had a normal Git history, which made it a pain to update (as a consequence, this was not done at all except for cherry picking security fixes). Merging any significant upstream changes was impossible and all clients would be limited to using our exact hostapd codebase. The solution was to identify our changes, split them into meaningful feature commits, keeping upstream and our code as separate as possible. After this change, updating the upstream by ~2 years took about 4 days. Most importantly, the history is kept clean by marking what commits go where, and doing cleanup every couple of months (no code diffs are allowed at that moment, only git history may be rewritten). The new history can also be exported as patches, so that any client can (selectively) apply them on top of their own hostapd.