| Constrained Source | Unconstrained Destination | Behavior |
|---|---|---|
| GCIO | BUFGCE/MBUFGCE, BUFGCTRL/MBUFGCTRL, BUFGCE_DIV/MBUFGCE_DIV, MMCM/XPLL/DPLL | Automatically placed in same clock region |
| MMCM/XPLL/DPLL | BUFGCE/MBUFGCE, BUFGCTRL/MBUFGCTRL, BUFGCE_DIV/MBUFGCE_DIV | Automatically placed in same clock region |
| GT*_QUAD | BUFG_GT/MBUFG_GT | Automatically placed in same clock region |
| BUFGCTRL | BUFGCTRL |
Automatically placed in same clock region Note: You can override placement within same clock
region by using the CLOCK_REGION constraint.
|
| BUFG*/MBUFG* | BUFG*/MBUFG* |
Unpredictable placement of unconstrained destination BUFG*/MBUFG* Recommend constraining destination BUFG*/MBUFG* using the CLOCK_REGION constraint Note: This excludes BUFGCTRL -> BUFGCTRL.
|
| BUFG*/MBUFG* | MMCM/XPLL/DPLL |
Unpredictable placement of unconstrained destination MMCM/XPLL/DPLL Recommend constraining MMCM/XPLL/DPLL using a LOC constraint Recommend CLOCK_DEDICATED_ROUTE constraint when the route spans adjacent or multiple clock regions |