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Observer
Observer
1,412 Views
Registered: ‎08-02-2017

Vivado is reorganizing my pin constraints

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So I've got about 1200 lines of code in our pin constraints file and everything is neatly categorized how I like it. I'm using 2018.1 and it seems to have some 'quirky behavior'

 

I've been running through implementation and working on my timing, I modify some of my constraints in the Vivado text editor, save, and rerun. My constraints say they've been modified and need to be saved, sounds correct since I changed some constraints so I say yes.

 

However, when I open my external editor it says that my pin constraint file has been modified and needs to be reloaded. Doing a compare between the old and new versions it looks like vivado took the liberty of rearranging all of my pins in a haphazzard manner. It looks like they're all there (thank goodness for git). But why were my pin constraints modified. My pin constraints are NOT the target constraint file.

 

How do I keep Vivado from modifying constraints it has no business modifying?

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Advisor
Advisor
1,608 Views
Registered: ‎12-03-2007

Hi @abcarter , 

 

This behavior has been since the beginning of Vivado. It's certainly not new to 2018.1.

Workaround our team is using is to keep pin constraints in a separate .xdc file, and make it read-only. 

 

Thanks,

Evgeni

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Mentor
Mentor
1,399 Views
Registered: ‎02-24-2014

XDC files are "managed" by Vivado, and represent a database dump of the in-memory constraints.   If you want to preserve the format of your constraints, then change the extension to ".TCL" and set them as a pre-synthesis TCL script.   Vivado doesn't attempt to manage external TCL scripts.    Using this method, you can have different constraints for synthesis, placement, and routing.   But bear in mind that constraints loaded in later will typically overwrite earlier ones on the same objects.

Don't forget to close a thread when possible by accepting a post as a solution.
Advisor
Advisor
1,609 Views
Registered: ‎12-03-2007

Hi @abcarter , 

 

This behavior has been since the beginning of Vivado. It's certainly not new to 2018.1.

Workaround our team is using is to keep pin constraints in a separate .xdc file, and make it read-only. 

 

Thanks,

Evgeni

View solution in original post

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Moderator
Moderator
1,218 Views
Registered: ‎06-14-2010

Hello @abcarter,

 

This topic is still open and is waiting for you.

 

If your question is answered and/or your issue is solved, please mark a response that resolved your issue, as Accepted Solution (more info on this can be found here: https://forums.xilinx.com/t5/help/faqpage/faq-category-id/solutions#solutions). This way, the topic can be completed then. 

 

If this is not solved/answered, please reply in the thread.

 

Thanks in advance and have a great day.

Kind Regards,
Anatoli Curran,
Xilinx Technical Support
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