GUC_CTB_HDR_LEN
#define GUC_CTB_MSG_MIN_LEN GUC_CTB_HDR_LEN
GEM_BUG_ON(atomic_read(&ctb->space) < len + GUC_CTB_HDR_LEN);
atomic_sub(len + GUC_CTB_HDR_LEN, &ctb->space);
ret = has_room_nb(ct, len + GUC_CTB_HDR_LEN, g2h_len_dw);
GEM_BUG_ON(len > GUC_CTB_HXG_MSG_MAX_LEN - GUC_CTB_HDR_LEN);
if (unlikely(!h2g_has_room(ct, len + GUC_CTB_HDR_LEN) ||