ECN backports

[Scheffenegger, Richard]

Hi guys,

I'm currently reviewing the pending backports from all the Diffs I have supplied so far.

One major one is D22497, where all the ECN-related flags got moved from TF_ (t_flags) to TF2_ (t_flags2), and subsequently, all other ECN-related patches will have merge conflicts.

However, since there was a major interop issue around CWR flag not being set according to RFC (D23364) which I backported out-of-line all the way to releng 11.4, stable/11 and stable/12 (manually adjusting the proper flag references), I am now wondering:

Do we want to backport that (major) change into stable/12, where ECN-flags move between the tcpcb fields?

Or shall we retain the old TF flags for ECN in stable/12, manually patching any backports from TF2 to TF, for binary compatibility reasons (although I guess there aren't that many people who go debugging the TCPCB without recompiling the correctly matching tools)?

Best regards,

Richard Scheffenegger