Answers Database

MAP M1.4: x4kma:312 - The following symbols could not be constrained to a single CLB (Two F-LUT's, an H-LUT, and carry logic).


Record #3766

Product Family:  Software

Product Line:  FPGA Implementation

Problem Title:
MAP M1.4: x4kma:312 - The following symbols could not be constrained to
a single CLB (Two F-LUT's, an H-LUT, and carry logic).



Problem Description:

Keywords: MAP, legal, pack, constrain, CLB

Urgency: Standard

General Description:

This solution record involves one case where the following
error message is encountered during MAP.

-----
ERROR: x4kma:312 - The following symbols could not be
constrained to a single CLB:
   	CY4 symbol "$1I243" (output signal=C6)
   	CY4_12 symbol "$1I196" (output signal=$1N232)
   	FMAP symbol "$1I221" (output signal=S6)
   	HMAP symbol "$1I345" (output signal=S7)
   	FMAP symbol "$1I222" (output signal=S)
   There are two resources that require the F function
generator.  These symbols share the same RLOC attribute value,
which requires them to be mapped to the same CLB.
-----

In this specific case, all three lookup tables and the carry
logic are being utilized.  The carry mode is ADDSUB.  The CIN
input is driven and also goes to the F-LUT.  The carry goes to
the G-LUT.  The F-LUT utilizes all four inputs and the output
goes out of the CLB.  The G-LUT uses all four inputs.  The
H-LUT has all three inputs driven: one comes from the output
of the G-LUT, and the other two from outside the CLB.  The
H-LUT output goes out of the CLB.
This looks to be a legal pack.


Solution 1:


MAP M1.4 cannot perform this legal CLB pack.
It has been addressed and fixed for the next Core Tools
release, M1.5.



End of Record #3766