The following error occurred during the MAP process.
ERROR:Pack:2811 - Directed packing was unable to obey the user design
constraints (BLKNM=5) which requires the combination of the symbols listed
below to be packed into a single SLICE component.
The directed pack was not possible because: There are more than four XORCY
The symbols involved are:
fu/gme/sad/un15_curr_sad_8_0_cry_8_outext" (Output Signal =
fu/gme/sad/un15_curr_sad_6_0_axb_4_lut6_2_o5" (Output Signal =
fu/gme/sad/un15_curr_sad_6_0_axb_4_lut6_2_o6" (Output Signal =
...... (hundreds of XorCY/LUT symbols listed here)
The Synthesis tool is Synplify Pro.
However, there is no BLKNM constraint in the top level and submodule netlists or the UCF/NCF files.
What is the problem?
A cause of this error can be if "COMP" is used in the HDL code.
COMP is an obsolete Xilinx property.
It is incorrectly converted to BLKNM by the tool.
To workaround this issue, do not use "COMP" in the HDL code.
This issue has been resolved in ISE 13.2 and later.