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Observer zanabonir
Observer
1,099 Views
Registered: ‎12-07-2013

Reuse Synthesis

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Dear Forum

 

In my desing Im using different IP, where only one of them (a BRAM) need much time for Synthesis...Other IP are "little"

Total time is around 30min circa.

 

When I modify one of the little IP, also very simple modification, and relaunch the Synthesis, again this process take long

time...Seems that Vivado re-Syntetize the BRAM IP that has been not changed.

 

Question is if there is a way to tell Vivado to use old resut of IP mot modified.

 

Thanks again

 

Roberto 

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1 Solution

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Moderator
Moderator
1,570 Views
Registered: ‎11-09-2015

Re: Reuse Synthesis

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Hi @zanabonir,

 

The Out of context option is available in later tools. Why not using a more recent version of vivado?

 

Note: In your case, you have a black box. The solution is nearly this. You would need to synthesis the BRAM alone and then export the synthesis result (using a netlist). Then on the netlist you can disable used for synthesis.

 

However, it is simpler to use vivado 2017.4.

 

Regards,


Florent
Product Application Engineer - Xilinx Technical Support EMEA
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6 Replies
Moderator
Moderator
1,067 Views
Registered: ‎09-15-2016

Re: Reuse Synthesis

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Hi @zanabonir

 

By default Vivado uses IP cache option which enables IP to use already synthesized results referencing the cache and copies the synthesized results. Refer page 14 below link:

https://www.xilinx.com/support/documentation/sw_manuals/xilinx2017_3/ug896-vivado-ip.pdf

 

Regards

Rohit

Regards
Rohit
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Observer zanabonir
Observer
1,055 Views
Registered: ‎12-07-2013

Re: Reuse Synthesis

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Thanks Mr Rohit for reply.

 

When I choose Project Manager -->Project Setting-->IP->IP Cache-->Disabled ( is the default), the Syntesis take circa 40min.

 

Then:

    - I change in .......-> Local (folder is in my project )

    - modify another very little IP ( not the big IP responsible for the long time Synthesis)

    - let inalterate the big IP 

    - Launch Syntesis of all project

 

the time is again the same (circa)..So dont work.

 

Info:  - I did not touch the cache setting of every single IP

         -I not syntetized every single IP, but only all project

        

 

Thanks

 

Roberto

 

 

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Moderator
Moderator
1,030 Views
Registered: ‎11-09-2015

Re: Reuse Synthesis

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Hi @zanabonir,

 

Did you try to set your BRAM as Out-of-context for synthesis?

 

OOC.PNG

 

This way if you do not change it, it won't be re-synthesized.

 

If think this is what you are looking for.

 

Regards,


Florent
Product Application Engineer - Xilinx Technical Support EMEA
**~ Don't forget to reply, give kudos, and accept as solution.~**
Observer zanabonir
Observer
1,022 Views
Registered: ‎12-07-2013

Re: Reuse Synthesis

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Thanks for reply

 

In Vivado 2015.3 I cant find this option .

I find another similar, in the Property window, where I -unceck- the   -Used for Syntesis -

 

In effect, regenerating the OOC files, the IP is not anymore Syntetisez...with a big save of time.

 

Unlucky, a error message arrive in the -Implementation step-, saing this (about the big BRAM that I not syntetized) :

 

Cell ..../BD1_IP_Ram  has undefined contents and is considered a black box. 
The contents of this cell must be defined for opt_design to complete successfully. 

 

I was one step from solution....hhhh

 

Thanks again

 

Roberto

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Moderator
Moderator
1,571 Views
Registered: ‎11-09-2015

Re: Reuse Synthesis

Jump to solution

Hi @zanabonir,

 

The Out of context option is available in later tools. Why not using a more recent version of vivado?

 

Note: In your case, you have a black box. The solution is nearly this. You would need to synthesis the BRAM alone and then export the synthesis result (using a netlist). Then on the netlist you can disable used for synthesis.

 

However, it is simpler to use vivado 2017.4.

 

Regards,


Florent
Product Application Engineer - Xilinx Technical Support EMEA
**~ Don't forget to reply, give kudos, and accept as solution.~**
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Observer zanabonir
Observer
987 Views
Registered: ‎12-07-2013

Re: Reuse Synthesis

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Thanks Again

 

I install the 2017.4  and seems work without problem.

 

Seems that Vivado recognize -alone- what IP has been modified,and when running  the Synthesis,Vivado

first regenerate the OOC  of  only the IP modified, then start the global Syntesis....

 

Thanks for all replies

 

Roberto

 

 

 

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