Dear all, In NIC driver, to eliminate the overhead of dma_map_single() for DMA packet data, we have statically allocated huge DMA memory buffer ring at once instead of calling dma_map_single() per packet. Considering to further reduce the copy overhead between different NIC(port) ring while forwarding, one packet from a input NIC(port) will be transferred to output NIC(port) with no any copy action. To satisfy this requirement, the packet memory should be mapped into input port and unmapped when leaving input port, then mapped into output port and unmapped later. Whether it's legal to map the same DMA memory into input and output port simultaneously? If it's not, then the zero-copy for packet forwarding is not feasible? Hope PCI expert to post your suggestion. Thanks! --Yanfei -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
