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2,830 Views
Registered: ‎07-24-2018

Meaning of synthesis warning: [Constraints 18-5210] No constraint will be written out.

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Hi all,

 

I get this warning (since vivado 2018.2):

[Constraints 18-5210] No constraint will be written out.

 

What does it mean? I guess it can be ignored as I don't see any issue and I have my usual constraints set (physical, timing, ...) which should not require any changes in/after synthesis. So, I'm not sure what to do with this warning other than suppressing.

 

 

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Explorer
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2,907 Views
Registered: ‎11-23-2009

Re: Meaning of synthesis warning: [Constraints 18-5210] No constraint will be written out.

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Hi @hemangd,

 

I also see this warning. It came with 2018.2, I don't see it with 2018.1, 2017.4 and 2017.2.

It comes at the very end of synthesis

synth_design completed successfully
synth_design: Time (s): cpu = 00:02:50 ; elapsed = 00:03:41 . ...
WARNING: [Constraints 18-5210] No constraint will be written out.
INFO: [Common 17-1381] The checkpoint '....dcp' has been generated.

So this message does not refer to a cell. it refers to the whole design.

And 'no constraint written' sounds at first scary.

Further inspection of my case showed that implementation seems properly constrained, so it seems to be true that this message can be safely ignored.

 

This message text should imho at least be rephrased, to be more specific, giving a chance to understand what is behind, to indicate the case where this message better not be ignored. It is imho sub-optimal to write out scary sounding warnings which should generally be ignored.

8 Replies
Moderator
Moderator
2,811 Views
Registered: ‎03-16-2017

Re: Meaning of synthesis warning: [Constraints 18-5210] No constraint will be written out.

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Hi daniel.widmer@varian.com,

 

This WARNING message is expected when there is no constraints in top-level related to those cells.

 

You can safely ignore it. 

 

Regards,

hemangd

 

If your issue has been resolved, than please close this thread by marking as accepted solution.

 

Regards,
hemangd

Don't forget to give kudos and mark it as accepted solution if your issue gets resolved.
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Explorer
Explorer
2,908 Views
Registered: ‎11-23-2009

Re: Meaning of synthesis warning: [Constraints 18-5210] No constraint will be written out.

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Hi @hemangd,

 

I also see this warning. It came with 2018.2, I don't see it with 2018.1, 2017.4 and 2017.2.

It comes at the very end of synthesis

synth_design completed successfully
synth_design: Time (s): cpu = 00:02:50 ; elapsed = 00:03:41 . ...
WARNING: [Constraints 18-5210] No constraint will be written out.
INFO: [Common 17-1381] The checkpoint '....dcp' has been generated.

So this message does not refer to a cell. it refers to the whole design.

And 'no constraint written' sounds at first scary.

Further inspection of my case showed that implementation seems properly constrained, so it seems to be true that this message can be safely ignored.

 

This message text should imho at least be rephrased, to be more specific, giving a chance to understand what is behind, to indicate the case where this message better not be ignored. It is imho sub-optimal to write out scary sounding warnings which should generally be ignored.

Moderator
Moderator
2,733 Views
Registered: ‎03-16-2017

Re: Meaning of synthesis warning: [Constraints 18-5210] No constraint will be written out.

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Hi @wfjmueller,

 

Can you share a small test case which consists of a source file and constraints file (.xdc) to debug this warning in detail?

 

If this warning and its message is not relevant/need a rephrase than we may discuss this issue with the factory on it and may ask for necessary changes in the tool. 

 

Regards,

hemangd 

Regards,
hemangd

Don't forget to give kudos and mark it as accepted solution if your issue gets resolved.
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Visitor patneva
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2,689 Views
Registered: ‎07-30-2018

Re: Meaning of synthesis warning: [Constraints 18-5210] No constraint will be written out.

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I am also getting the same error - but what is meaning of ignoring it? coz it doesnt generate bit file so cant run the program on hardware

I am doing simple program of led blinking from you tube. I am using zedboard as reference hardware

bitstream error.jpg
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Explorer
Explorer
2,578 Views
Registered: ‎11-23-2009

Re: Meaning of synthesis warning: [Constraints 18-5210] No constraint will be written out.

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Hi @hemangd

 

please find attached a Vivado 2018.2 project which shows the [Constraints 18-5210] message.

The project definitively has constraints, starting with pin assignments.

 

With best regards,   Walter

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Moderator
Moderator
2,562 Views
Registered: ‎11-04-2010

Re: Meaning of synthesis warning: [Constraints 18-5210] No constraint will be written out.

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Hi @patneva ,

Please create a new thread for your Design Initialization Error. 

Warning [Constraints 18-5210] is not the cause for your error you met.

 

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Moderator
Moderator
2,561 Views
Registered: ‎11-04-2010

Re: Meaning of synthesis warning: [Constraints 18-5210] No constraint will be written out.

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Hi, @wfjmueller ,

The warning can be seen in the example design in Vivado.

Actually Warning [Constraints 18-5210] reminders you that the synth.dcp generated in ./project_name.runs/synth_1/ dir doesn't contain any constraint. 

When you generate the synth.dcp with the below method, the warning disappears and no constraints are missing:

<1>. Open synthesized design

<2>. write_checkpoint synth.dcp

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Explorer
Explorer
895 Views
Registered: ‎05-25-2016

Re: Meaning of synthesis warning: [Constraints 18-5210] No constraint will be written out.

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@hongh I have this exact same problem.  I don't understand your answer regarding why constraint error 18-5210 is generated.  

 

Why wouldn't the dcp contain a constraint if there is a constraint correctly added to the project?  I've run synthesis and implementation on this and I can't get rid of this warning?  I am also creating this project from a script usually so I don't save the dcp or anyof that project related data.  What is the appropriate manner for satisfying this warning?  

Questions

1. Why doesn't the dcp have a constriant when the dcp is created with a project that has a top level constriant?

2. How do you correctly satisfy this warning when building your project from a TCL script?  

2.a. How do you tell vivado to build a TCL script that will prevent this warning from appearing?  I'm using "write_project_tcl" right now.

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