> Right hard_header_len is being overloaded with two meanings.
quoted text
> On the one hand it's used to indicate the length of the header
> managed by the hardware header cache, on the other hand we use
> it to indicate the head room for those devices that don't have
> a cache.
>=20
> Since your device wants both, it fails miserably.

Yeah I guess that is actually the root cause.

quoted text
> There are three ways out of this.  You could have your own cache
> (I haven't looked at your headers so I don't know whether that
> makes sense), have no cache at all, or add a new field that gets
> added to hard_header_len for the purposes of calculating head
> room.

In fact, I should probably add another field for the needed tail length
too since we need that as well.

johannes