When implementing the Ethernet MAC with either a GMII or RGMII physical interface, regional clocking methodologies are used. This means that there are the following requirements:
- The receive-side physical interface clock (GMII_RX_CLK for GMII, or RGMII_RXC for
RGMII) must be placed at a clock-capable I/O (CCIO) pin. If this requirement is not
met, an error similar to the following one might be seen during
implementation:
ERROR: [Vivado 12-1411] Cannot set LOC property of ports, Could not legally place instance trimac_fifo_block/trimac_sup_block/tri_mode_ethernet_mac_i/inst/gmii_interface/gmii_rx_clk_ibuf_i at Y14 (IOB_X1Y49) since it belongs to a shape containing instance trimac_fifo_block/trimac_sup_block/tri_mode_ethernet_mac_i/inst/gmii_interface/bufio_gmii_rx_clk. The shape requires relative placement between trimac_fifo_block/trimac_sup_block/tri_mode_ethernet_mac_i/inst/gmii_interface/gmii_rx_clk_ibuf_i and trimac_fifo_block/trimac_sup_block/tri_mode_ethernet_mac_i/inst/gmii_interface/bufio_gmii_rx_clk that cannnot be honored because it would result in an invalid location for trimac_fifo_block/trimac_sup_block/tri_mode_ethernet_mac_i/inst/gmii_interface/bufio_gmii_rx_clk. - All receive-side physical interface signals must be placed at package pins that
correspond to the same clock region as the receive-side physical interface. If this
requirement is not met, a warning similar to the following might be seen during
implementation:
For more information on these requirements, see the Vivado Design Suite, See I/O Standard and Placement.CRITICAL WARNING: [Vivado 12-1411] Cannot set LOC property of ports, Illegal to place instance trimac_fifo_block/trimac_sup_block/tri_mode_ethernet_mac_i/inst/gmii_interface/bufio_gmii_rx_clk on site TIEOFF_X101Y96. The location site type does not match the instance type. Instance trimac_fifo_block/trimac_sup_block/tri_mode_ethernet_mac_i/inst/gmii_interface/bufio_gmii_rx_clk belongs to a shape with reference instance trimac_fifo_block/trimac_sup_block/tri_mode_ethernet_mac_i/inst/gmii_interface/bufio_gmii_rx_clk. Shape elements have relative placement respect to each other. The invalid location might results from a constraint on any of the instance in the shape. [/home/username/dev_proj/test/warning_recreate/tri_mode_ethernet_mac_0_example/tri_mode_ethernet_mac_0_example.srcs/constrs_1/imports/example_design/tri_mode_ethernet_mac_0_example_design.xdc:125]