#include<linux/dma-mapping.h>/* Set this to 1 if there is a HW IOMMU in the system */intiommu_detected__read_mostly;structdma_map_ops*dma_ops;EXPORT_SYMBOL(dma_ops);structdma_map_ops*dma_get_ops(structdevice*dev){returndma_ops;}EXPORT_SYMBOL(dma_get_ops);