AR #33743 - 11.3 Virtex-6 FPGA MAP - Change in trimming behavior related to IBUFDS_GTXE1 components
11.3 Virtex-6 FPGA MAP - Change in trimming behavior related to IBUFDS_GTXE1 components
| AR# | 33743 |
| Part | SW-MAP |
| Last Modified | 2009-11-10 00:00:00.0 |
| Status | Active |
| Keywords | undriven, IBUFDS_GTXE1, regression, trimmed, trimming, Synplify, Pro, PCIe |
Description
Keywords: undriven, IBUFDS_GTXE1, regression, trimmed, trimming, Synplify, Pro, PCIe
My PCIe design was working properly in ISE software 11.2, but fails in 11.3 with trimming issues related to some GTXE1 components. I am using Synplify Pro.
Is there a known problem in 11.3 that leads to this trimming?
Solution
This problem is related to the way the ISE tools handle undriven IBUFDS_GTXE1 inputs. In 11.2, NGDBuild would automatically insert PADs to these unconnected inputs and MAP would automatically insert IBUFs. This behavior was changed for 11.3 because XST is now inserting IBUFs on the IBUFDS_GTX inputs. This behavioral change overlooked the fact that Synplify Pro still passes IBUFDS_GTXE1 with an undriven input and the original 11.2 behavior still needs to be supported.This problem is scheduled to be fixed by Synplicity in their December release (D--2009.12). Meanwhile, to work around the issue, instantiate IBUFs for the undriven IBUFDS_GTX inputs.