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AR# 29547

9.2i Virtex-5 MAP - "ERROR:Pack:679 - Unable to obey design constraints (LUTNM=fpgac)" with -global_opt

Description

When I run MAP using the Global Optimization option, the following error occurs:

" ERROR:Pack:679 - Unable to obey design constraints (LUTNM=fpgac)

which require the combination of the following symbols into a single SLICE

component:

LUT symbol "N_102137_i" (Output Signal = N_102137_i)

LUT symbol "un1_ftcfo_phase_count_11_0" (Output Signal =un1_ftcfo_phase_count_11_0/O)

Function generators N_102137_i and un1_ftcfo_phase_count_11_0 are not compatible.

The two function generators can not share a LUT site.

Please correct the design constraints accordingly."

I have checked the netlist and these LUTs appear to be compatible. Why am I getting this error?

Solution

There is an issue with the global optimization algorithms where they do not consider LUTNM constraints during optimization, and can cause LUTs with this constraint to become incompatible. This will be fixed in a future software version.

In the meantime, to work around this issue, please disable the global optimization option.

AR# 29547
Date Created 10/28/2007
Last Updated 12/15/2012
Status Active
Type General Article