const __m128i zero = _mm_setzero_si128();
/* mask to shuffle from desc. to mbuf */
const __m128i shuf_msk = _mm_set_epi8
- (0xFF, 0xFF, 0xFF, 0xFF, /* rss not supported */
+ (15, 14, 13, 12, /* octet 12~15, 32 bits rss */
11, 10, /* octet 10~11, 16 bits vlan_macip */
5, 4, /* octet 4~5, 16 bits data_len */
0xFF, 0xFF, /* skip high 16 bits pkt_len, zero out */