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AR# 9709

3.1i Foundation ISE - XST issues regarding the register_duplication switch


Keywords: Foundation, ISE, process, properties, register, duplication

Urgency: Standard

General Description:
The register_duplication switch is not available from the XST "Process Properties" dialogue window in Foundation ISE. Furthermore, XST does not recognize the register_duplication constraint when it is passed through Verilog.


The register_duplication option is only available in:

1. Constraint file format:

attribute register_duplication of <entity_name> : string is <"YES"|"NO">;

2. HDL format:


// synthesis attribute register_duplication of <module_name> is <"YES"|"NO">;

(XST does not currently recognize the Verilog format of this constraint. This problem will be resolved in a future release)


attribute register_duplication : string;
attribute register_duplication of <entity_name> : string is <"YES"|"NO">;

3. Command line mode:

-register_duplication <YES|NO>

In the 4.1i software release, the register_duplication is an ISE GUI option for XST. In addition, XST recognizes the switch when it is passed through Verilog.

For more information on passing constraints through XST, please see (Xilinx Solution 9457).
AR# 9709
Date Created 07/17/2000
Last Updated 08/19/2002
Status Archive
Type General Article