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AR# 57061

2013.2 Vivado - Aurora 8B10B OOC XDC uses lower case and the core has upper cases which causes critical warning when using the DCP

Description

I generated synthesized dcp DCP for IP Aurora 8B10B (target language set to Verilog) and added the DCP to other projects for IP re-use. However, the following critical warnings are seen in implementation.

[Vivado 12-1387] No valid object(s) found for set_max_delay constraint with option 'from'. ["C:/example_project/aurora_8b10b_0_example/aurora_8b10b_0_example.srcs/sources_1/ip/aurora_8b10b_0_0/aurora_8b10b_0_clocks.xdc":57]
[Vivado 12-1387] No valid object(s) found for set_max_delay constraint with option 'from'. ["C:/example_project/aurora_8b10b_0_example/aurora_8b10b_0_example.srcs/sources_1/ip/aurora_8b10b_0_0/aurora_8b10b_0_clocks.xdc":63]
[Vivado 12-1387] No valid object(s) found for set_max_delay constraint with option 'from'. ["C:/example_project/aurora_8b10b_0_example/aurora_8b10b_0_example.srcs/sources_1/ip/aurora_8b10b_0_0/aurora_8b10b_0_clocks.xdc":66]

The corresponding XDC constraints are similar to the following:

set_max_delay -from [get_clocks -of_objects [get_ports USER_CLK]] -to [get_clocks -of_objects [get_ports INIT_CLK_IN]] -datapath_only 5.000
set_max_delay -from [get_clocks -of_objects [get_ports INIT_CLK_IN]] -to [get_clocks -of_objects [get_ports DRPCLK_IN]] -datapath_only 20.000
set_max_delay -from [get_clocks -of_objects [get_ports USER_CLK]] -to [get_clocks -of_objects [get_ports DRPCLK_IN]] -datapath_only 20.000

Solution

When generating the synthesized DCP for the IP, OOC XDC is applied. The create_clock commands in the OOC XDC are attached to port name with lower case.

## USER_CLK constraint
create_clock -name user_clk_i -period 12.8 [get_ports user_clk]
## 50 MHz INIT_CLK constraint
create_clock -name init_clk_i -period 20.000 [get_ports init_clk_in]
# 50 MHz DRP Clock Constraint
create_clock -name drp_clk_i -period 20.000 [get_ports drpclk_in]

The IP core has upper case for these (looking in aurora_8b10b_0_core.v).

Since the OOC XDC is scoped to the core inst, it fails to create the clocks and incurs the critical warnings. A CR has been filed against the inconsistency.

Two possible work-arounds:

  • Manually modify the OOC XDC to use upper case and regenerate DCP for the IP OOC module.
  • Ensure clocks at the Aurora's ports are created at the user-defined XDC.
AR# 57061
Date Created 08/09/2013
Last Updated 10/29/2013
Status Active
Type Known Issues
Tools
  • Vivado Design Suite - 2013.2
IP
  • Aurora 8B/10B