AR# 12245

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4.1i Virtex-II PAR - The placer fails to align carry chain properly if a macro is a subset of the carry chain.

Description

Keywords: carry, chain, place, unrouted, aligned

Urgency: Standard

General Description:
The placer fails to correctly align a carry chain when a subset of the slices in the carry chain belong to a macro.

An example of this would be a carry chain where some of the slices are also assembled into a placer macro in order to properly position some related LUT RAM slices.

Solution

This problem is fixed in the latest 4.1i service pack, available at:
http://support.xilinx.com/support/techsup/sw_updates.
The first service pack containing the fix is 4.1i Service Pack 1.

An alternate work-around is to RLOC the entire carry chain.
AR# 12245
Date 10/22/2008
Status Archive
Type General Article
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