I'm new to isolated design flow(IDF) and trying an example project on it. The very small example design was created with vivado 2018.2, and it is in attachments. I get the following error while running placement:
[DRC HDIS-18] No Pblock range for cell: HD.ISOLATED primitive cell 'idf0/OBUF_c' is not ranged by Pblock 'pblock_idf0'. An isolation Pblock must range all of its cell primitive types. A 'IOB' range needs to be added to the Pblock. Alternatively the HD.ISOLATED_EXEMPT property can be used if necessary to allow the cell outside of the Pblock.
Once I added the following two lines in the xdc file, the project was then OK and finish without error: