At times, MAP introduces DRC errors in DSP48Es when absorbing registers. The following is an example of the error:
"ERROR:PhysDesignRules:1525 - Unsupported programming for DSP48E. The DSP48E
block Maddsub__mult0000/Maddsub__mult0000 has attributes AREG and ACASCREG
set to incompatible values. The attributes must have have the value to be
compatible or AREG set 2 is compatible with ACASCREG set 1."
To work around this issue, set the environment variable "XIL_MAP_NO_DSP48E_AUTOREG" to "1".
For general information about setting ISE environment variables, see (Xilinx Answer 11630).
This problem has been fixed in the latest 8.2i Service Pack available at:
The first service pack containing the fix is 8.2i Service Pack 1.