What is the ring concept for placement blockage?

I came across a Cadence command "create_place_blockage" for Innovus tools, which is like this:

create_place_blockage -hinst DT_INST/RESS_CONV_INST -inner_ring_by_side {10 10 10 10} -outer_ring_by_side {5 5 5 5}

But I did not find the documentation of this command, so I am trying to understand what these three options mean:
(1) -hinst something : Does it mean the other two options are dependent on this one? It is like we are going to create a blockage on this hier instance, and the shape of the blockage is determined by the other two options?
(2) I thought "blockages" are just rectangular chunks, in other words, it is just big squares. But what does "inner_ring/outer_ring" mean?

Thanks

check the manual for createPlaceBlockage

these options you mention help you to cover some macro with a placement screen. the ring options are like an offset that can be applied to every edge or side. I agree that ring is not a good name, but it is what it is.

ThisIsNotSam said:

check the manual for createPlaceBlockage

these options you mention help you to cover some macro with a placement screen. the ring options are like an offset that can be applied to every edge or side. I agree that ring is not a good name, but it is what it is.

Click to expand...

Thank you so much for your response. However, I still have some trouble with visualizing it in my mind, because I don't understand how it works when both "inner_ring_by side" and "outer_ring_by _side" are specified, like this:

create_place_blockage -hinst something -inner_ring_by_side {10 10 10 10} -outer_ring_by_side {5 5 5 5}

Let us assume hinst named something has an initial shape {llx, lly, urx, ury = 100 100 200 200}. When applying inner_ring_by_side to it , it shrinks to {llx, lly, urx, ury = 110 110 190 190}
, but when applying outer_ring_by_side to it, it then grows to {llx, lly, urx, ury = 105 105 195 195}.

I am new to placement. So when people say "to apply a blockage on an hinst", what does it really mean? To my understanding, the blockage was first put there, and then placer needs to put instances somewhere else to avoid this region, but this "inner/outer ring offset" thing really confused me, because it sound like "You first have instances put somewhere, and then your blockage shape will be calculated from the instances coordinate and inner/outer ring offsets".

I can't think of an use for inner ring off the top of my head, also can't think of an use for both at the same time. But the outer ring is useful. Sometimes you are in charge of putting power rings around macros. You can extend your placement blockage to cover your macro + power ring area too.