Answers Database
2.1i Virtex Map - A case has been seen where map does not pack CYMUX and XORCY with the register they drive.
Record #7124
Product Family: Software
Product Line: FPGA Implementation
Product Part: map
Product Version: 2.1i
Problem Title:
2.1i Virtex Map - A case has been seen where map does not pack CYMUX and XORCY with the
register they drive.
Problem Description:
Urgency: Standard
General Description:
The design has no RLOCs. In 1.5i, map successfully packed the
CYMUX and XORCY in the same slice as the registers they drive.
In 2.1i the carry chain ends up in different slices except for the XORCY
at the end of the chain. The result is an un-placeable design because
he registers are LOC'd in a column, but only the last element of the carry
chain is in that column. The first part of the carry chain can not be aligned
with the last element.
I have been able to work around this by forcing the last XORCY out of it's slice using a KEEP
property, creating a placable, but sub-optimal design.
Solution 1:
This problem is scheduled to be fixed in the next (as yet unnamed)
release following version 2.1i. This release is currently scheduled
for May, 2000.
End of Record #7124 - Last Modified: 12/21/99 15:56 |
