Undocumented commands

[TEEkohl]

In scripts for controlling Openroad (e.g. from Openroad-flow-scripts or OpenLane) I see a lot of undocumented commands, especially those commands which are within a specific TCL namespace. Some examples:

ord::get_db_tech
ord::get_db_block
odb::dbBlockage_create
getDbUnitsPerMicron

Is there any command reference available? I can't find anything on
https://openroad.readthedocs.io etc.

[maliberty]

The first two are more commonly used in scripting as a way to get the tech & block. We should probably make a wrapper in the public namespace as they are necessary.

odb is a straight swig wrapping of db.h. It would be far too tedious to make wrapper for all of these so it is ok to use them directly. It is best to read the header directly.

getDbUnitsPerMicron is probably part of OL and not OR (odb has something similar but not in the global namespace afaik).

I don't think there is more formal documentation but there are a lot of examples in the unit tests and ORFS. Feel free to ask questions.

[TEEkohl]

1. Is it possible to restrict the odb::dbBlockage_create command to only block placement, but not routing etc. ?
2. Is there a similar command with which to delete all previously defined blockages on the die ?

Background information:
Reading through header files is very cryptic for me since I am not a C programmer but Asic designer.
In another P&R tool command options are available to instruct the placer not to place cells underneath specified metall layers, e.g. not underneath vertical power stripes. This might avoid routing congestion. Since this is not available in Openroad (or is undocumented), I am creating blockages underneath all
vertical stripes after floorplanning and PDN insertion and then do the placement. But then I have to remove these blockages again to enable the signal routing to pass underneath or beyond the vertical stripes.

[maliberty]

From the class comments in src/odb/include/odb/db.h :
dbBlockage : A dbBlockage is the element that represents a placement blockage in a block.
dbObstruction : A dbObstruction is the element that represents a routing obstruction in a block.

So a blockage is placement only. I don't believe there is a command to remove previous blockages.

The detailed placer was recently enhanced to add awareness of PDN straps blocking pin access so this may all be moot. Please see if you have such issues with the head of OR.

[TEEkohl]

I can confirm that the blockages created with odb::dbBlockage_create do not block the routing as long as they are applied after initial floorplanning. Applied before initial floorplanning they are blocking everything including rows, tracks and the PDN.
But now the problem remains that at the end of the layout run the insertion of filler cells is still blocked. To remove the blockages I found the command odb::dbBlockage_destroy. But I can't figure out how the exact syntax must be for this command. If I type it in without further arguments at the TCL console of the Openroad GUI I only get the error message

[ERROR GUI-0070] Wrong number or type of arguments for overloaded function 'dbBlockage_destroy'.
Possible C/C++ prototypes are:
odb::dbBlockage::destroy(odb::dbBlockage *)
odb::dbBlockage::destroy(dbSet< odb::dbBlockage >::iterator &)

That is unfortunately no help for me.

[maliberty]

I believe it swig's to dbBlockage_destroy (similar to create and all static methods)

[b224hisl]

But it seems that odb::dbObstruction_create doesn't work. I have set the routing blockage region before CTS after placement, the final routing also passes the obstruction region

[maliberty]

Please open an issue with a test case

[b224hisl]

Okay, I have filed this issue . Appreciate your assistance!!😊