[PATCH v9 2/4] ethdev: introduce protocol hdr based buffer split

[Thomas Monjalon]

13/06/2022 12:25, wenxuanx.wu at intel.com:
> --- a/lib/ethdev/rte_ethdev.h
> +++ b/lib/ethdev/rte_ethdev.h
> @@ -1176,6 +1176,9 @@ struct rte_eth_txmode {
>   *   specified in the first array element, the second buffer, from the
>   *   pool in the second element, and so on.
>   *
> + * - The proto_hdrs in the elements define the split position of
> + *   received packets.
> + *
>   * - The offsets from the segment description elements specify
>   *   the data offset from the buffer beginning except the first mbuf.
>   *   The first segment offset is added with RTE_PKTMBUF_HEADROOM.
> @@ -1197,12 +1200,21 @@ struct rte_eth_txmode {
>   *     - pool from the last valid element
>   *     - the buffer size from this pool
>   *     - zero offset
> + *
> + * - Length based buffer split:
> + *     - mp, length, offset should be configured.
> + *     - The proto_hdr field should not be configured.
> + *
> + * - Protocol header based buffer split:
> + *     - mp, offset, proto_hdr should be configured.
> + *     - The length field should not be configured.
>   */
>  struct rte_eth_rxseg_split {
>  	struct rte_mempool *mp; /**< Memory pool to allocate segment from. */
>  	uint16_t length; /**< Segment data length, configures split point. */
>  	uint16_t offset; /**< Data offset from beginning of mbuf data buffer. */
> -	uint32_t reserved; /**< Reserved field. */
> +	/**< Supported ptypes mask of a specific pmd, configures split point. */

The doxygen syntax is wrong: remove the "<" which is for post-comment.

> +	uint32_t proto_hdr;
>  };

How do we know it is a length or buffer split?
Is it based on checking some 0 value?