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AR# 65279

DDR4/3 UltraScale - UNDEF error occurs upon generating output products when a dual slot, dual rank 72-bit DIMM is generated in an FPGA device containing only 3 vertical I/O banks


When targeting an FPGA that contains only 3 vertical banks within an I/O column, there are not enough I/O available to place a dual rank, dual slot 72-bit DDR4/3 DIMM.

However, the DDR4/3 IP tool currently does not limit this configuration.

After Generating Output Products, the following error is generated:

ERROR: [#UNDEF] There are certain ports which are still unassigned as per the selected data width 72, design generation can be done correctly once all the bytes/sites are assigned.



WARNING: [Mig 66-114] Unable to find the required number (4) of consecutive empty bank(s) to auto place all the memory bytes


Later versions of Vivado will report this error:

"ERROR: UNDEF Not able to find enough and valid I/O's in the device selected to fit this configuration. Require minimum of <MemPortCnt> enough and valid I/O's. Please choose bigger device to accommodate or modify the memory configuration (for eg. reducing Datawidth or opting for low density memory part etc..) to fit in this device."


Please only select a 64-bit dual rank, dual slot DIMM in FPGA devices where there are only 3 vertical banks within an I/O column.

Linked Answer Records

Master Answer Records

AR# 65279
Date 10/13/2016
Status Active
Type Known Issues
  • Kintex UltraScale
  • Virtex UltraScale
  • MIG UltraScale