Answers Database MAP M1.4.12: FATAL_ERROR:x4kma:x4kmaclkbuf.c:591:1.25 - No input sig on CLKBUF inst_name. Record #3615 Product Family: Software Product Line: FPGA Implementation Product Part: map Product Version: 1.4 Problem Title: MAP M1.4.12: FATAL_ERROR:x4kma:x4kmaclkbuf.c:591:1.25 - No input sig on CLKBUF inst_name. Problem Description: Urgency: Hot General Description: Targetting a 4000E or Spartan device with M1.4.12, MAP may return with the following error message. FATAL_ERROR:x4kma:x4kmaclkbuf.c:591:1.25 - No input sig on CLKBUF inst_name. This is known MAP issue that concerns driving a global buffer with an internally-generated signal. There will be a patch released soon to address this issue. In the meantime, please use the workaround below. Also, this has been resolved in the the next release of M1. Solution 1: This problem is fixed in the latest M1.4 Core Tools Patch available on the Xilinx Download Area: Solaris: ftp://ftp.xilinx.com/pub/swhelp/M1.4_alliance/core_sol17_m14.tar.Z SunOS ftp://ftp.xilinx.com/pub/swhelp/M1.4_alliance/core_sun17_m14.tar.Z HPUX: ftp://ftp.xilinx.com/pub/swhelp/M1.4_alliance/core_hp17_m14.tar.Z Win95/NT: ftp://ftp.xilinx.com/pub/swhelp/M1.4_alliance/core_nt17.zip Solution 2: The workaround involves telling the tools not to trim out the signal driving the global buffer. This can be done by applying the "KEEP" attribute on the net at the input of the BUFG. In your schematic, apply an attribte name of "KEEP" on the net leaving the value of the attribute blank. Alternatively, this can be be done in a UCF file as follows.   NET BUFG_SRC KEEP; Please refer to the Libraries Guide more information on attributes. End of Record #3615 - Last Modified: 09/28/98 09:10

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