A conflict can occur when, the design is routing which, causes the net assigned to the backbone, not to be able to get onto the backbone routing and as such the DRC received is correct.
However, this is still an issue as the tools should be able to handle this configuration.
Note: The routing was incorrect in previous SW versions as well, the DRC is new in 2014.1.
This workaround would also be required with release 2013.4 and prior.
To check whether your net has been correctly placed on the backbone in previous SW versions where the DRC is not flagged, customers can run the following command on an open implemented design.It is clear that no Backbone has been used as in the route properties you should see "BB" used, see the below workaround for an example of a working route.
There is a workaround available for this issue, which is to directly apply a routing property to the net requiring the backbone routing.
The steps below show how this can be achieved:
report_drc -file pre_wa_drc_chk.rptThis performs a DRC check and shows the DRC reported by write_bitstream.
route_design -unrouteUnroutes the entire design.
route_design -nets [get_nets clk_in1]Routes the net reported in the DRC error only.
set_property IS_ROUTE_FIXED 1 [get_nets clk_in1]Locks the net.
route_designRoutes the rest of the design.
report_drc -file post_wa_drc_chk.rptDRC error no longer reported.
With this added, the design will implement and allow bitstream generation.
This AR also applies to 2013.4 designs.
05/07/2014 - Initial Release