Maybe few applications that use FreeRTOS-Plus-TCP take advantage of no copy buffers as it is a significant effort to implement. I can’t imagine a MAC on any processor that wouldn’t have an (4/8) alignment requirement for it’s receive and transmit buffers however I could imagine a MAC having an option to automatically offset (pad) the beginning of a packet within a word boundary when receiving. This is only speculation of course as I haven’t written any other MAC drivers.