Answers Database
2.1i Virtex Map/PAR- Error:Place:871 - Carry chain placement conflicts with floor planned register LOCs.
Record #8032
Product Family: Software
Product Line: FPGA Implementation
Product Part: map
Product Version: 2.1i
Problem Title:
2.1i Virtex Map/PAR- Error:Place:871 - Carry chain placement conflicts with floor planned
register LOCs.
Problem Description:
Using Floorplanner to place location constraint on a 16bit register gives
an error in PAR :
ERROR:Place:871 - Some of the slices in the carry chain
containing the slice <name> have LOC constraints that make
it impossible to place the chain legally. Please either fix or
remove the constraints.
This problem is caused by three factors:
1. Non-RLOC'd carry chain
2. FloorPlanned registers
3. The device is full enough to require un-related merges in order to fit the design.
The unrelated merge is causing a portion of the non-RLOC'd carry chain to be
merged with one of the slices with floorplanned registers. The rest of the carry
chain is not being merged with the registers, so it is not possible to satisfy both
the carry chain alignment and the register LOCs.
Solution 1:
The work around for this problem is to either RLOC the carry chain, or to use
XBLKNM properties on the registers to prevent the unrelated merge.
A map fix to address the unrelated merge of carry chains with floorplanned (or LOC'd)
registers will be included in the next major release (as yet unnamed) after 2.1i. It is
scheduled to become available on March 21, 2000.
End of Record #8032 - Last Modified: 12/01/99 08:49 |
