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AR# 63537

2014.4 Vivado Placer - Placer fails due to a miscalculation of LUTRAM utilization for a clock domain


A case has been seen where the placer fails on a feasible design due to a miscalculation of LUTRAM placement requirements.

Phase 3 Global Placement
ERROR: [Place 30-504] Global clock placer failed to legalize CLOCKREGION_X1Y2 for clock loads of type LUTRAM. This region contains 3800 available LUTRAM sites, however there are 5216 such loads in the region and clock legalizer could not move enough loads out of the region to legalize it. The following clock nets have loads of type LUTRAM in this region:
Clock846871 net: DBF_CLK1/Pclk
Driver: DBF_CLK1/Pclk_buf
Number of LUTRAM loads: 233
Clock net: DBF_CLK1/Pclk_div2
Driver: DBF_CLK1/Pclkd2_buf
Number of LUTRAM loads: 2656
Clock net: control/mig/norm.MIG/u_mig_7series_Verilog/u_ddr3_infrastructure/ui_clk
Driver: control/mig/norm.MIG/u_mig_7series_Verilog/u_ddr3_infrastructure/u_bufg_clkdiv0
Number of LUTRAM loads: 614
Clock net: control/txbf_lmp_link/clk_module/sync_clk
Driver: control/txbf_lmp_link/clk_module/user_clk_buf_i
Number of LUTRAM loads: 72
Clock net: dsp/core_gen.0.core_i/BS_linik_out/clock_module/SYNC_CLK
Driver: dsp/core_gen.0.core_i/BS_linik_out/clock_module/user_clk_buf_i
Number of LUTRAM loads: 385
If the clock net(s) are regional, try using global clock buffers to drive the loads so they are not restricted to specific clock regions and have more freedom to move.
Phase 3 Global Placement | Checksum: 1352e47a1

Time (s): cpu = 00:07:14 ; elapsed = 00:05:43 . Memory (MB): peak = 2384.734 ; gain = 124.051
ERROR: [Place 30-99] Placer failed with error: 'Exit after global placer


This problem has been fixed for the 2015.1 release.

In the mean-time a patch is available for 2014.4.

See the attached file which contains patch files for all platforms.

Method 1: (Vivado 2014.4 and later only)
   a. Navigate to the $XILINX_VIVADO/patches directory (create this directory if it does not exist)
   b. Extract the contents of the ".zip" archive to a directory starting with the name AR63537
       Note: most extraction tools will allow you to automatically create a directory with the same name as the zip file.
   c. Run Vivado software tools from the original install location.

Method 2:
   a. Creating a separate directory containing patched files
   b. Extract the contents of the ".zip" archive to the desired patch directory location.
   c. Set the MYVIVADO environment variable to point to the Vivado directory under this patch directory:
       For example:

set MYVIVADO=C:\MYVIVADO\vivado-patch-AR63537\vivado\


setenv MYVIVADO /path/to/patch_dir/vivado

   d. Run Vivado software tools from the original install location.


Associated Attachments

Name File Size File Type
AR63537_vivado_2014_4_rev1.zip 31 MB ZIP
AR# 63537
Date Created 02/10/2015
Last Updated 02/16/2015
Status Active
Type General Article
  • Artix-7
  • Kintex-7
  • Virtex-7
  • Vivado Design Suite - 2014.4