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AR# 9810

3.1i XST - Attributes KEEP, NOREDUCE, BUFG, FAST, SLOW and PIN_ASSIGN are ignored in a CPLD design.

Description

Keywords: attributes, KEEP, NOREDUCE, BUFG, FAST, SLOW, PIN_ASSIGN, CPLD, constraints

Urgency: Standard

General Description:
Six attributes that are supported by CPLDs are being ignored by XST:

- BUFG
- FAST
- KEEP
- NOREDUCE
- PIN_ASSIGN
- SLOW

Solution

Where applicable, use a UCF to assign the constraints. In the case of NOREDUCE, please see (Xilinx Solution 9912).

The PIN_ASSIGN attribute will not propagate the constraint properly on a non-standard bus such as (15 downto 8) instead of (7 downto 0). Please see (Xilinx Solution 10363) for more information.

NOTE: This problem is fixed in the 4.1i software release.
AR# 9810
Date Created 07/31/2000
Last Updated 08/20/2002
Status Archive
Type General Article