I do some more tests. Stream mode, Vivado 2018.3.1, Ubuntu 18.04.1(Kernel 4.15.0-91) , use dma_from_device cmd. 1MB one count: ./dma_from_device -d /dev/xdma0_c2h_0 -s 0x100000 -c 1 4KB 4096 count: ./dma_from_device -d /dev/xdma0_c2h_0 -s 0x1000 -c 4096 ...