Barring signal routing on layers

[donn]

We're working with an exotic proprietary PDK where there are two routing layers that are strictly for power and not signal routing. We can't seem to be able to stop GRT from creating guides on those layers… we tried set_routing_layers, set_global_routing_layer_adjustment, none of them really work. And DRT in some particularly congested designs does create routes on those layers.

Thoughts?

[maliberty]

Are they above the layers you use for signal routing?

[maliberty]

What type does the layer have in LEF? Is it a mimcap?

[maliberty]

Do you have to put vias on that layer to connect other valid routing layers?

[donn]

Just TYPE ROUTING. I think all standard cells have vias on those layers but all ultimately have access pins on Metal 1 (valid routing.)

[maliberty]

I don't understand what that means. Can you give more of a description of the layer stack?

[eder-matheus]

@donn FYI, if there are pins in a routing layer below these two layers that you don't want routing, GRT will have to stack via guides to access these pins.

[stefanottili]

I once was surprised that routing layer options need to be set separately for both global_route and detailed_route.
set_routing_layers is used by global_route only.
detailed_route has the options -bottom_routing_layer and -top_routing_layer.
Separate options due to historically different tools.

[maliberty]

Also grt has -signal/-clock while drt does not (though the guides from grt will try to steer it in that direction).