GUC_NUM_DOORBELLS
DECLARE_BITMAP(doorbell_bitmap, GUC_NUM_DOORBELLS);
#define GUC_DOORBELL_INVALID (GUC_NUM_DOORBELLS)
end = GUC_NUM_DOORBELLS / 2;
for (db_id = 0; db_id < GUC_NUM_DOORBELLS; ++db_id)