>The behavior seems contradictory to the flag's description. Am I reading it
>right? Should the comment be read only in the context of the lwip core, or
>maybe it only applies to transmitted packets?
Yes, it only applies to tx packets.
There's not much point in copying on the Rx side: the netif driver is responsible to create pbufs that can live longer. You could argue that pbufs might have to be copied when really enqueueing (e.g. in TCP Rx ooseq and the like), but if you need to copy for tcpip_input, the driver has to do it.
Noted. Makes sense. Thank you.