This problem affects UniPHY-based DDR3, LPDDR2, QDR II, RLDRAM II and RLDRAM 3 products.
When you create a new external memory interface in the Quartus II software, you may see the following warning message:
Warning: ... pll_bridge.pll_sharing cannot be both connected
The above warning message is not harmful.
The workaround for this issue is to ignore the displayed warning message.
This issue will be fixed in a future version.