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Observer
Observer
12,945 Views
Registered: ‎03-02-2015

Timing passes and all nets route, but I get a warning about not meeting hold time on unroutable nets anyways

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The subject is, I hope, a pretty good description, but for completeness here's the log:

 

Phase 8 Route finalize

Router Utilization Summary
  Global Vertical Routing Utilization    = 8.62186 %
  Global Horizontal Routing Utilization  = 9.24715 %
  Routable Net Status*
  *Does not include unroutable nets such as driverless and loadless.
  Run report_route_status for detailed report.
  Number of Failed Nets               = 0
  Number of Unrouted Nets             = 0
  Number of Partially Routed Nets     = 0
  Number of Node Overlaps             = 0

Phase 8 Route finalize | Checksum: a5d6d9cb

Time (s): cpu = 00:07:42 ; elapsed = 00:02:00 . Memory (MB): peak = 3396.734 ; gain = 0.000 ; free physical = 1743 ; free virtual = 22715

Phase 9 Verifying routed nets

 Verification completed successfully
Phase 9 Verifying routed nets | Checksum: a5d6d9cb

Time (s): cpu = 00:07:42 ; elapsed = 00:02:00 . Memory (MB): peak = 3396.734 ; gain = 0.000 ; free physical = 1743 ; free virtual = 22715

Phase 10 Depositing Routes
Phase 10 Depositing Routes | Checksum: 15b15948e

Time (s): cpu = 00:07:46 ; elapsed = 00:02:04 . Memory (MB): peak = 3396.734 ; gain = 0.000 ; free physical = 1743 ; free virtual = 22715

Phase 11 Post Router Timing
INFO: [Route 35-20] Post Routing Timing Summary | WNS=0.069  | TNS=0.000  | WHS=0.043  | THS=0.000  |

INFO: [Route 35-61] The design met the timing requirement.
Phase 11 Post Router Timing | Checksum: 106eacd36

Time (s): cpu = 00:08:27 ; elapsed = 00:02:13 . Memory (MB): peak = 3396.734 ; gain = 0.000 ; free physical = 1741 ; free virtual = 22713
WARNING: [Route 35-426] Router was unable to fix hold violation on unroutable pins. The router cannot add routing detours to improve hold time because the pins are part of one or more of the following unroutable types: partition pins, fixed routes and intra-site connections.
Resolution: Run report_timing_summary to analyze the hold violations.

When I run report_timing_summary or report_timing, no violations are found and all nets are reported as routed.

 

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Xilinx Employee
Xilinx Employee
24,112 Views
Registered: ‎09-20-2012

Re: Timing passes and all nets route, but I get a warning about not meeting hold time on unroutable nets anyways

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Hi @tas-genia

 

Thanks for sharing the DCP files.

 

I was able to recreate the issue in vivado 2016.1 internal build. I have filed CR 948651 and addressed this issue to factory.

Thanks,
Deepika.
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Observer
Observer
12,940 Views
Registered: ‎03-02-2015

Re: Timing passes and all nets route, but I get a warning about not meeting hold time on unroutable nets anyways

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I forgot to mention that I'm using Vivado 2015.4.

 

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Xilinx Employee
Xilinx Employee
12,902 Views
Registered: ‎02-16-2014

Re: Timing passes and all nets route, but I get a warning about not meeting hold time on unroutable nets anyways

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Hi @tas-genia

 

Did you run report_route_status on implemented design?

Do you see any nets with routing errors when you run this command?

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Xilinx Employee
Xilinx Employee
12,900 Views
Registered: ‎09-20-2012

Re: Timing passes and all nets route, but I get a warning about not meeting hold time on unroutable nets anyways

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Hi @tas-genia

 

This looks to like false message. Can you share the post place or post place phys opt DCP file?

Thanks,
Deepika.
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Observer
Observer
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Registered: ‎03-02-2015

Re: Timing passes and all nets route, but I get a warning about not meeting hold time on unroutable nets anyways

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report_route_status
Design Route Status
                                               :      # nets :
   ------------------------------------------- : ----------- :
   # of logical nets.......................... :      114339 :
       # of nets not needing routing.......... :       38318 :
           # of internally routed nets........ :       29632 :
           # of nets with no loads............ :        8686 :
       # of routable nets..................... :       76021 :
           # of fully routed nets............. :       76021 :
       # of nets with routing errors.......... :           0 :
   ------------------------------------------- : ----------- :

 

This is report_route_status against my post-route checkpoint.

 

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Observer
Observer
12,860 Views
Registered: ‎03-02-2015

Re: Timing passes and all nets route, but I get a warning about not meeting hold time on unroutable nets anyways

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Deepika,

 

I am using a custom batch-mode flow rather than a project. I save 3 checkpoints, here is the order of operations:

 

1. Synthesize design, read OOC IP cores (netlist is complete)

2. Save post_synth.dcp

 

3. Run tandem PROM TCL script from PCIe IP core

4. opt_design

5. place_design

6. Save post_place.dcp

 

7. phys_opt_design

8. route_design

9. Save post_route.dcp

 

Let me know whether you'd like post_place or post_route, and how to get it to you.

 

I can also edit in additional checkpoints, but I have to inform you that I've just re-run my build script and I didn't get the warning this time. No changes to IP cores or RTL. The utilization report shows a small difference in the number of LUTs and FFs from the run yesterday which generated the warning. I'm guessing there is run-to-run variance due to dynamically partitioning work to threads.

 

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Xilinx Employee
Xilinx Employee
12,739 Views
Registered: ‎09-20-2012

Re: Timing passes and all nets route, but I get a warning about not meeting hold time on unroutable nets anyways

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Hi @tas-genia

 

You can send me post place checkpoint. I will send you ezmove package to upload file.

Thanks,
Deepika.
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Xilinx Employee
Xilinx Employee
24,113 Views
Registered: ‎09-20-2012

Re: Timing passes and all nets route, but I get a warning about not meeting hold time on unroutable nets anyways

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Hi @tas-genia

 

Thanks for sharing the DCP files.

 

I was able to recreate the issue in vivado 2016.1 internal build. I have filed CR 948651 and addressed this issue to factory.

Thanks,
Deepika.
--------------------------------------------------------------------------------------------
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Xilinx Employee
Xilinx Employee
12,611 Views
Registered: ‎09-20-2012

Re: Timing passes and all nets route, but I get a warning about not meeting hold time on unroutable nets anyways

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Hi @tas-genia

 

If your query is addressed, please close the thread by marking the answer.

Thanks,
Deepika.
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Observer
Observer
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Registered: ‎10-06-2015

Re: Timing passes and all nets route, but I get a warning about not meeting hold time on unroutable nets anyways

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 ask what the resolution to this issue was? I'm currently seeing the exact same issue in 2017.1.

 

David

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Xilinx Employee
Xilinx Employee
2,183 Views
Registered: ‎09-20-2012

Re: Timing passes and all nets route, but I get a warning about not meeting hold time on unroutable nets anyways

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Hi @dwoods

 

The CR which I filed was fixed in vivado 2016.3. 

 

You might be running in to different issue. If the timing is met on the design, this message can be ignored. Which device are you using?

Thanks,
Deepika.
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Moderator
Moderator
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Registered: ‎01-16-2013

Re: Timing passes and all nets route, but I get a warning about not meeting hold time on unroutable nets anyways

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@dwoods,

 

For better responses, Can you please create a new forum topic for this query? 

 

--Syed

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Give Kudos to a post which you think is helpful and reply oriented.

Did you check our new quick reference timing closure guide (UG1292)?
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