1：配置ebaz4205的网口
set_property IOSTANDARD LVCMOS33 [get_ports ENET0_GMII_RX_CLK_0]
set_property PACKAGE_PIN U14 [get_ports ENET0_GMII_RX_CLK_0]
set_property PACKAGE_PIN U15 [get_ports ENET0_GMII_TX_CLK_0]
set_property PACKAGE_PIN W19 [get_ports {ENET0_GMII_TX_EN_0[0]}]
set_property PACKAGE_PIN W18 [get_ports {ENET0_GMII_TXD[0]}]
set_property PACKAGE_PIN Y18 [get_ports {ENET0_GMII_TXD[1]}]
set_property PACKAGE_PIN V18 [get_ports {ENET0_GMII_TXD[2]}]
set_property PACKAGE_PIN Y19 [get_ports {ENET0_GMII_TXD[3]}]
set_property PACKAGE_PIN W16 [get_ports ENET0_GMII_RX_DV_0]
set_property PACKAGE_PIN W15 [get_ports MDIO_ETHERNET_0_0_mdc]
set_property PACKAGE_PIN Y14 [get_ports MDIO_ETHERNET_0_0_mdio_io]
set_property PACKAGE_PIN Y16 [get_ports {ENET0_GMII_RXD[0]}]
set_property PACKAGE_PIN V16 [get_ports {ENET0_GMII_RXD[1]}]
set_property PACKAGE_PIN V17 [get_ports {ENET0_GMII_RXD[2]}]
set_property PACKAGE_PIN Y17 [get_ports {ENET0_GMII_RXD[3]}]
set_property IOSTANDARD LVCMOS33 [get_ports ENET0_GMII_TX_CLK_0]
set_property IOSTANDARD LVCMOS33 [get_ports {ENET0_GMII_RXD[3]}]
set_property IOSTANDARD LVCMOS33 [get_ports {ENET0_GMII_RXD[2]}]
set_property IOSTANDARD LVCMOS33 [get_ports {ENET0_GMII_RXD[1]}]
set_property IOSTANDARD LVCMOS33 [get_ports {ENET0_GMII_RXD[0]}]
set_property IOSTANDARD LVCMOS33 [get_ports {ENET0_GMII_TX_EN_0[0]}]
set_property IOSTANDARD LVCMOS33 [get_ports {ENET0_GMII_TXD[3]}]
set_property IOSTANDARD LVCMOS33 [get_ports {ENET0_GMII_TXD[2]}]
set_property IOSTANDARD LVCMOS33 [get_ports {ENET0_GMII_TXD[1]}]
set_property IOSTANDARD LVCMOS33 [get_ports {ENET0_GMII_TXD[0]}]
set_property IOSTANDARD LVCMOS33 [get_ports ENET0_GMII_RX_DV_0]
set_property IOSTANDARD LVCMOS33 [get_ports MDIO_ETHERNET_0_0_mdc]
set_property IOSTANDARD LVCMOS33 [get_ports MDIO_ETHERNET_0_0_mdio_io]2：sdk中tcp echo server实验是成功的。有一个问题不明白：xdc约束中MDIO_ETHERNET_0_0_mdio_io是哪来的？？？？后来通过代码也可以通过open implemented design图看来这两个信号没有约束：
3：当将配置中的ETH0的MDIO和MDC两个信号去掉之后（xdc中约束也当然去掉），再export到sdk中，创建echo server应用时出现：
4：重新再配置上MDC和MDIO，
1). 导入hardware后，先regenerate BSP. 进入BSP设置看下stdout/stdin 有没有被改成别的uart?
2). 先clean工程再重新编译。
实验又成功了：
这说明lwip其实是用到了MDC和MDIO的。
来源：oschina
链接：https://my.oschina.net/u/2963604/blog/3288507