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Bob, How can I constrain optDesign -hold to add buffers on end points only?

eminemshow

Bob,

Things are like this, I am now at the final stage of timing closure, since functional timing is clean and test timing is ongoing. There is not enough time to config a MMMC environment. After investigation, I found that if I can add all the hold buffers at SI pin of DFF at scan shift mode, then functional timing would be un-touched (as you know, at Q pin of DFF, things would be dangerous......). So I want to ask whether I can control optDesign to make end-point only buffer insertion when fixing hold.

Thanks.

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  • BobD

    I should have been clear with the "USEMINSPACING OBS" parameter suggestion.  I was thinking that there might be a "USEMINSPACING OBS" statement present in your tech.lef which was instructing the tool to use min spacing next to obstructions.  Since it wasn't present previously, this is not what's causing the tool to think it's safe to go in spacing next to obstractions.  It must be something else, but I can't think of anything else to ask you to look for.

    If possible I'd suggest you file a service request so you can submit a testcase for us to look at.

    Thanks,
    Bob

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  • BobD

    I should have been clear with the "USEMINSPACING OBS" parameter suggestion.  I was thinking that there might be a "USEMINSPACING OBS" statement present in your tech.lef which was instructing the tool to use min spacing next to obstructions.  Since it wasn't present previously, this is not what's causing the tool to think it's safe to go in spacing next to obstractions.  It must be something else, but I can't think of anything else to ask you to look for.

    If possible I'd suggest you file a service request so you can submit a testcase for us to look at.

    Thanks,
    Bob

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