AR# 38620

ISE 12.2 Pack Virtex-6 - Pack:2784 - Directed packing was unable to obey the user design constraint

The following error is being received during Map:

ERROR:Pack:2784 - Directed packing was unable to obey the user design constraint

(LUTNM=Transceiver/INST_PROCESSING_CHAIN.TRX_Data_Chain/INST_FFT_IFFT.FFT_IFF

T_1/V6_FFT_Core_Gen.FFT_Core/blk00000003/U0/non_floating_point.arch_d.xfft_in

st/pe_gen[3].natural_order_input.PE/delay_addr_bf2/SRL16_2) which requires

combining the symbols listed below into a single SLICEM component.

...

The directed pack was not possible because:

The top reasons for failure were:

-> A legal placement was never found for shift register symbol

...

How can I resolve this error?

This is a known issue which has been resolved in ISE 12.3.

The issue can be worked around by disabling power optimization (Removing the -power switch) of Map.

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AR# 38620
Date	07/30/2014
Status	Active
Type	General Article
Devices	Virtex-6 CXT Virtex-6 HXT Virtex-6 LX More Virtex-6 LXT Virtex-6 SXT Less
Tools	ISE Design Suite - 12.1 ISE Design Suite - 12.2

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