We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

AR# 13177

4.1i Virtex-II MAP - Packer creates shapes that are inconsistent with carry logic placement, leading to unroutes and "WARNING:Place:1855"


Keywords: WARNING:Place:1855, carry, unrouted, unroutable

Urgency: Standard

General Description:
MAP is creating shapes that made it impossible for the placer to align the carry chain involved. This leads to the following warning from the placer:

"WARNING:Place:1855 - The structured logic associated with a carry chain could not be placed in such a way as to use all of the fast carry connections due to a placement constraint. A sub optimal placement will be performed. You may wish to verify that the sub-optimal placement will be satisfactory."


This problem is fixed in the latest 4.1i Service Pack, available at:
The first service pack containing the fix is 4.1i Service Pack 3.
AR# 13177
Date 08/20/2003
Status Archive
Type General Article
Page Bookmarked