unblock [true|false]
The command sets the policy for handling pins that have been found to be not routable (for one of a number of reasons) but which surround grid points that are cleanly inside the pin boundary. The default method is to mark such grid points as unroutable, unless doing so causes the pin to be completely unroutable. Then these positions are re-marked as routable.If the unblock policy is set to true, then all grid points that are cleanly inside pin geometry will be re-marked as routable, regardless of whether there may have been other grid positions marked as belonging to the same pin, and routable.
The purpose of this command is mainly to work around the problem of obstruction layers that are defined in unusual ways and which may end up blocking pins in a way that is a false positive obstruction. The usual reason for this is that parts of a pin that are off-grid or considered by the designer to be unsuitable for routing have been assigned to obstruction layers rather than being marked in the LEF macro as belonging to the pin. When that is the case, it is generally true that the smaller areas marked as pins are known good positions to terminate a route, and can always be trusted to be cleanly routable. But use this command with caution, as it can cause positions that are truly obstructed in some way to be treated as routable, resulting in DRC or LVS errors in the routed design.
This command must be issued before read_def to be effective.
unblock is implemented as a built-in command in qrouter, only in the Tcl version.
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Last updated: September 17, 2019 at 10:05pm