Answers Database
2.1i Virtex Map - Device utilization appears to increase because of new default packing rules.
Record #6572
Product Family: Software
Product Line: FPGA Implementation
Product Part: map
Product Version: 2.1i
Problem Title:
2.1i Virtex Map - Device utilization appears to increase because of new default packing
rules.
Problem Description:
Virtex Map in version 2.1i uses a different default pack factor than version 1.5i. Version 1.5i did
not restrict the packing of unrelated logic. Version 2.1i will only pack unrelated logic in order to
fit the device, so utilization of slices is more likely to approach 100%. This apparent degradation
in mapping results actually leads to better place and route results.
Solution 1:
If denser packing is wanted, there is a command line switch that can be used to modify this behavior
(-c n) where n is desired utilization percentage.
Examples:
map -c 1 design.ngd (Pack unrelated logic as much as possible)
map -c 80 design.ngd (Target 80% utilization)
This switch can be accessed through DM/FE by using the Template Manager to define a Custom Template.
End of Record #6572 - Last Modified: 06/26/99 13:36 |
