[dpdk-dev] Questions Questions about hash function enum

[oulijun]

Hi Ferruh Yigit and others

   I am learning data structure defined by dpdk framework and I noticed 
a data structure definition below:

enum rte_eth_hash_function {
    RTE_ETH_HASH_FUNCTION_DEFAULT = 0,
    RTE_ETH_HASH_FUNCTION_TOEPLITZ, /**< Toeplitz */
    RTE_ETH_HASH_FUNCTION_SIMPLE_XOR, /**< Simple XOR */
    /**
     * Symmetric Toeplitz: src, dst will be replaced by
     * xor(src, dst). For the case with src/dst only,
     * src or dst address will xor with zero pair.
     */
    RTE_ETH_HASH_FUNCTION_SYMMETRIC_TOEPLITZ,
    RTE_ETH_HASH_FUNCTION_MAX,
};

I have a little difficulty understanding that for the comment:

   /**
     * Symmetric Toeplitz: src, dst will be replaced by
     * xor(src, dst). For the case with src/dst only,
     * src or dst address will xor with zero pair.
     */

if user configure rss func for symmetric toeplitz, Rss type must be 
updated at the same time?

if user configure rss func for xor, rss type must be empty and the queue 
number is zero?

Must it be restricted like this? If so, what is his benefit?

Looking forward to your reply


Thanks

Lijun Ou