Constant esp_idf_sys::pbuf_type_PBUF_POOL

pub const pbuf_type_PBUF_POOL: pbuf_type = 386;

pbuf payload refers to RAM. This one comes from a pool and should be used for RX. Payload can be chained (scatter-gather RX) but like PBUF_RAM, struct pbuf and its payload are allocated in one piece of contiguous memory (so the first payload byte can be calculated from struct pbuf). Don’t use this for TX, if the pool becomes empty e.g. because of TCP queuing, you are unable to receive TCP acks!