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Visitor puertask
Visitor
1,520 Views
Registered: ‎02-07-2017

PR static_checpoint overlaps problem

Hi, 

I'm working with Vivado 2015.2 (can't upgrade to the latest version unless is strictly necessary).

I'm generating a PR solution over a Kintex 7. The process to generate the static checkpoint goes smoothly, synth and impl the design, update PR region to a black box, lock the routing and generate the static_base.dcp. Until here everything is normal (as it has been for the last couple of years I've been doing that). But from here is where the strange behaviour happens.

Once I've saved the static_base dcp, If I load the same PR dcp I used to implement the design the first time (without closing the project), I can implement the project without any problem.
But If I open the static_base checkpoint, load the PR checkpoint and then implement the design, I get stuck with almost 1k net overlaps when routing. Most of those nets are placed at an interconnect in the static region (which was supposed to be locked..).

 

Have anyone experienced something similar? As I've said, I've been working with PR for almost two years and this is the first time I've seen something like this (few times I've seen 1-2 nets overlaps at the PR region due to high congestion).

 

Best regards

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4 Replies
Xilinx Employee
Xilinx Employee
1,474 Views
Registered: ‎04-16-2008

Re: PR static_checpoint overlaps problem

Hi @puertask

 

It could be a bug in the 2015.2 tools, or it could be a matter of how the DCPs are being added opened.  If you could provide the exact Tcl you're running, it may help.

 

Here is something quick to check.  If you close the in-memory design between the first and the second configuration (which I would recommend you do), make sure you use a "close_project" command. This is the way the PR scripts (UG947) run the tools.  If you close the in-memory design using close_design, the in-memory fileset is not cleared (ie. [get_files ] will still return previously added files).  If you aren't doing this, it could be that you aren't loaded the set of DCPs you may think.  An even simpler test is to completely close Vivado between the two configurations.  If you do this, do you still get the routing overlaps? 

 

If you make a clean break between the to implementations, and still see the issue, I would try the same thing in the latest tools. I don't believe I've ever seen the issue you're describing, and I'm guessing/hoping this is more of a methodology issue that will be easily resolved with a quick edit to your run scripts.

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Visitor puertask
Visitor
1,424 Views
Registered: ‎02-07-2017

Re: PR static_checpoint overlaps problem

Hi @woodsd,

 

Every time I open the satic_base dcp I do it from a freshly open Vivado.

The TCL commands I use are:

 

Generation:

 

synth_design -flatten_hierarchy rebuilt -top [top_file] -part xc7k325tffg676-2

opt_design

place_design -directive SpreadLogic_medium (I've also tried with no directive at all)

route_design

update_design -cell [pr_cell] -black_box

lock_design -level routing

write_checkpoint [...]/static_base.dcp

 

Implementation

 

open_checkpoint [...]/static_base.dcp

read_checkpoint -cell [pr_cell] [...]/pr_checkpoint.dcp (same included in the generation project).

otp_design

place_design -directive SpreadLogic_medium (I've also tried with no directive at all)

route_design

 

I tried the same process with Vivado 2017.2 and it worked just fine, but as I mentioned, I rather not update the tool unless is strictly necessary. 

 

The same flow I described is used in another 5 projects and they don't show any of the problems I have with this one.

 

It's also odd that the nets that are suffering from overlaps are placed in the static region, which was supposed to be locked..

 

 

 

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Xilinx Employee
Xilinx Employee
1,416 Views
Registered: ‎04-16-2008

Re: PR static_checpoint overlaps problem

Hi @puertask,

 

Yes, I agree this is a strange error. Just to clarify, in your run scripts do you issue a close_project command in between the two runs?  Make sure you close the in-memory project before creating a new one (which open_checkpoint command will do)?

synth_design -flatten_hierarchy rebuilt -top [top_file] -part xc7k325tffg676-2
opt_design
place_design -directive SpreadLogic_medium (I've also tried with no directive at all)
route_design
update_design -cell [pr_cell] -black_box
lock_design -level routing
write_checkpoint [...]/static_base.dcp
 
close_project
 
open_checkpoint [...]/static_base.dcp
read_checkpoint -cell [pr_cell] [...]/pr_checkpoint.dcp (same included in the generation project).
otp_design
place_design -directive SpreadLogic_medium (I've also tried with no directive at all)
route_design

If this doesn't resolve it, I would recommend you take the hit and upgrade to the latest software.

 

 

 

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Visitor puertask
Visitor
1,408 Views
Registered: ‎02-07-2017

Re: PR static_checpoint overlaps problem

Hi @woodsd,

 

I tried it and keeps failing.. almos 1,2k nets with overlaps in the static region.. weird.

I think I'll have to give 2017.2 a try, is 2017.3 close to release? because if so, I would wait ;)

Thanks!

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