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3.4 FPGA Express - FPGA Express writes the IOB attribute on every flip-flop in a Virtex design
Keywords: IOB, true, false, Virtex, flip, flop, ff, map
FPGA Express will write out an IOB attribute on every flip-flop in a Virtex
design. This causes the 'map -pr' option to be obsolete.
Change the IOB attribute setting to either TRUE or FALSE in the FPGA Express
constraints editor. The UCF will also override this particular constraint.
If you want no attribute to be placed on the flip-flop, the only known
workaround is to manually edit the EDIF file to remove the IOB attributes.