_bus_dma_valloc_skewed
vaddr_t _bus_dma_valloc_skewed(size_t, u_long, u_long, u_long);
va = _bus_dma_valloc_skewed(size, 0, align,
dva = _bus_dma_valloc_skewed(sgsize, map->_dm_boundary,
dva = _bus_dma_valloc_skewed(sgsize, map->_dm_boundary,
vaddr_t _bus_dma_valloc_skewed(size_t, u_long, u_long, u_long);