ttm_bo_reserve
ret = ttm_bo_reserve(bo, true, no_wait, false, 0);
extern int ttm_bo_reserve(struct ttm_buffer_object *bo,
ret = ttm_bo_reserve(bo, false, false, false, 0);
ret = ttm_bo_reserve(bo, true, no_wait, false, 0);
ret = ttm_bo_reserve(bo, true, no_wait, false, 0);