Answers Database
2.1i Virtex Map - Mapper creates unroutable connection when F6mux is driven by two F5muxes.
Record #7466
Product Family: Software
Product Line: FPGA Implementation
Product Part: map
Product Version: 2.1i
Problem Title:
2.1i Virtex Map - Mapper creates unroutable connection when F6mux is driven by two F5muxes.
Problem Description:
Urgency: Hot
General Description:
When two F5muxes drive an F6mux, the mapper incorrectly configures the two F5muxes in two slices, wi
th both using the F5 pin. It is not possible for both of these F5 pins to reach the F6mux. One of th
e F5muxes needs to be configured to use the connection to the X output pin so that it can use genera
l routing resources.
Solution 1:
A change request is being considered for a future service pack. Meanwhile, the
following rigorous work around exists:
1. Identify all F5MUX's that are being configured to drive other than F5IN pins.
2. Apply XBLKN attributes to these F5MUX's to prevent them from being merged
into slices with logic that could end up using the X output pin. Logic that won't be
in contention for the X pin and is needed in the slice can be given the same XBLKNM
attribute.
3. Re-Map the design.
4. Using FPGA Editor, re-configure the slice and net connectivity so that the
X output pin in used rather than the F5 output pin.
5. Submit design to PAR for place and route.
Solution 2:
This problem is fixed in the latest 2.1i Service Pack available at:
http://support.xilinx.com/support/techsup/sw_updates/
End of Record #7466 - Last Modified: 10/18/99 09:36 |
