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Instances with placement status "unplaced"

RVERP

I have a bunch of instances in my layout with placement status "unplaced". They aren't shown in virtuoso, but they appear in my stream out gds, causing a lot of DRC errors.

I can simply remove them with dbRemoveObject, so this is easy to fix. But I don't know how they got there. How do you end up with an unplaced instance?

  • rajeshcad
    If someone does that deliberately in virtuoso a warning is issued saying that instance will become invisible. If the design was taken outside virtuoso environment then that could be the cause. Or, if someone tried a misadventure with SKILL :-)
  • Alex Soyer

    Hello,

    If you used Generate Physical Hierarchy and you have generated soft blocks then you could have 'unplaced' instances but when opening or descending into that instance you should be warned for 'unplaced' instances.

    In stream out you have an option not to stream out 'unplaced' instances.

    I need to check but I think if you use some verilog2oa commands you could as well have teh same type of issues with 'unplaced' instances.

    Thanks,

    Alex

  • RVERP
    I have used the physical hierarchy and soft blocks. So at what point in the flow using soft blocks is the status changed?
  • Alex Soyer
    When generating the soft blocks the instances are set to 'unplaced' in order to make easier the floorplanning at the top level and not having a big content of the soft blocks displayed. Actually when generating the soft blocks content we do a Gen From Source inside the instance and then make them 'unplaced'. When you open the layout of that soft block then you need first make the instances all visible. You can do it manually in Navigator, or when you have the warning just click to make all instances visible, the last solution is to use the Floorplan > Reinitialize commands just on instances.

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