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AR# 14830

4.2i Virtex-II MAP - As of software version 4.2i, the mapper no longer pushes inverters and buffers through area group boundaries

Description

Keywords: push, merge, pack, optimize, inversion, inverter, buffer

Urgency: Standard

General Description:
As of software version 4.2i, MAP no longer pushes inverters and buffers across module boundaries by default. This can cause a problem if an inverted clock or CE signal has loads that are not in the same area group as the inverter -- the inversion is not pushed forward into the clock/CE mux, but is implemented in a LUT instead.

Solution

1

In software version 5.1i (due out in September, 2002), you may set an environment that will change the default behavior so that MAP has the freedom to push inverters and buffers across area group boundaries.

Workstation:
setenv XIL_MAP_ALLOW_AG_BUFINV 1

PC:
set XIL_MAP_ALLOW_AG_BUFINV=1

2

A tactical patch has been developed for 4.2i Service Pack 3; this patch supports an environment variable that can be set to change the default behavior so that MAP has the freedom to push inverters and buffers across area group boundaries.

(Service Pack 3 is available at http://support.xilinx.com/support/techsup/sw_updates.)

PC:
http://www.xilinx.com/txpatches/pub/swhelp/ise4_updates/42isp3_map_pc_14664.zip

- Install 4.2i Service Pack 3 if you have not already installed it.
- Unzip 42isp3_map_pc_14830.zip in the XILINX install directory while maintaining the directory structure.

set XIL_MAP_ALLOW_AG_BUFINV=1

Solaris:
http://www.xilinx.com/txpatches/pub/swhelp/ise4_updates/42isp3_map_sol_14664.tar.gz

- Install 4.2i Service Pack 3 if you have not already installed it.

cd $XILINX
gzip -d 42isp3_map_sol_14830.tar.gz
tar xvf 42isp3_map_sol_14830.tar
setenv XIL_MAP_ALLOW_AG_BUFINV 1
AR# 14830
Date Created 06/06/2002
Last Updated 08/20/2003
Status Archive
Type General Article