BUS_DMAMAP_IOMMU_KMEM_ALLOC
map->flags |= BUS_DMAMAP_IOMMU_KMEM_ALLOC;
KASSERT((map->flags & BUS_DMAMAP_IOMMU_KMEM_ALLOC) != 0,
map->flags &= ~BUS_DMAMAP_IOMMU_KMEM_ALLOC;