slow_path_element
pdev->sq_info.sq_chain.bd_left = USABLE_BDS_PER_PAGE(sizeof(struct slow_path_element), TRUE); /* prod == cons means empty chain */
struct slow_path_element command;
struct slow_path_element *sq_chain_virt;
struct slow_path_element *prod_bd;
struct slow_path_element *last_bd;
struct slow_path_element *elem;
sizeof(struct slow_path_element),
struct slow_path_element elem;
(CORE_SPQE_PAGE_SIZE_BYTES / sizeof(struct slow_path_element))