I40E_BUF_IPHDR_ALIGNMENT
rx = i40e->i40e_frame_max + I40E_BUF_IPHDR_ALIGNMENT;
mp = allocb(plen + I40E_BUF_IPHDR_ALIGNMENT, 0);
mp->b_rptr += I40E_BUF_IPHDR_ALIGNMENT;
dmap->dmab_size -= I40E_BUF_IPHDR_ALIGNMENT;
dmap->dmab_address += I40E_BUF_IPHDR_ALIGNMENT;
dmap->dmab_dma_address += I40E_BUF_IPHDR_ALIGNMENT;