A novel PCI Express direct memory access (DMA) transaction method using the PEX 8011 bridge chip is proposed to deal with bus-efficiency and DMA-efficiency. The method proposed has been successfully applied into a high speed PCI Express communication card.
A finite state machine (FSM) responding for data and address cycles on PCI Express bus is used to achieve a continuous data burst, which greatly promote bus-efficiency.
In the software design, a driver framework based on Windows driver model (WDM) and three DMA optimizing options for the proposed PCI Express interface are presented to improve DMA-efficiency.
Experiments show that both read and write hardware transaction speed in this paper exceed PCI theoretical maximum speed (133 MBytes/s).
Notably, the DMA method in this paper depends on continuous physical memory, which means it may be of interest to try using scatter/gather DMA, when continuous physical memory is not available.
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