Hi,
This problem has been solved. I found an ip core that can convert gmii to rgmii interface.
This ip core supports Ultrascale+ FPGA (exclude Zynq Ultrascale+), I do not know if it supports other FPGA familys.
Another question is that the ip core symbol:
Ethernet_hub_gmii_0's input port: ref_reset looks it should be active low, However, it's active high.
