Forum Discussion

Seadog's avatar
Seadog
Icon for Occasional Contributor rankOccasional Contributor
6 years ago

Fitter error due to 'get_combs' command in .sdc file

I am getting a fitter error caused by a 'get_combs' command in the .sdc file; the get_combs command is part of a create_generated_clock command:

-source [get_combs {blah_blah_blah\

|blah_blah_bla\

|blah_blah_bla\

|blah_blah_bla\

|altera_xcvr_10gkr_a10\

|CHANNEL\

|RX_CLK_MUX_LS.gf_rx_clk_mux_inst\

|reduce_or_0~0~la_mlab/laboutt[6]}]

The create_generated _clock command was automatically generated by Timing Analyzer; the chip built without issues before I added the SDC file. The SDC reference manual I have makes no mention of a 'get_combs' command.

I tied replacing the 'get_combs' with a 'get_pins', which seems to work (fitter is still running) but I don't know what effect that might have on the actual application of timing constraints. Any ideas? thanks.

14 Replies

  • Seadog's avatar
    Seadog
    Icon for Occasional Contributor rankOccasional Contributor
    6 years ago

    Thanks. I have that document, but as I wrote above it does not mention a 'get_combs' command. And any time Quartus/Timing Analyzer has occasion to write the .sdc file, it puts that 'get_combs' command back in there. Replacing the 'get_combs' instances with 'get_nets' seems to work, but I don't understand why the tool inserts a command which it can't process; it seems to me that this is a bug which needs to be addressed.

  • KhaiChein_Y_Intel's avatar
    KhaiChein_Y_Intel
    Icon for Regular Contributor rankRegular Contributor
    6 years ago
    Can you share the error messages, steps to reproduce the error, the software edition (Pro/Standard/Lite) and the software version ?
  • sstrell's avatar
    sstrell
    Icon for Super Contributor rankSuper Contributor
    6 years ago

    I don't understand. Something in your design is generating this .sdc file? get_combs is not a valid collection. You say "any time Quartus/Timing Analyzer has occasion to write the .sdc file". Are you saying you're doing a "Write SDC" command in the timing analyzer to generate this or is it getting generated in some other way?

    #iwork4intel

    • Seadog's avatar
      Seadog
      Icon for Occasional Contributor rankOccasional Contributor
      6 years ago

      As you probably know, if you use the TA GUI to create a timing constraint, you can then cue TA to write out the updated .sdc file. When TA writes to the .sdc file, it is overwriting the edits I made to eliminate the offending 'get_combs' command. Then I have to manually edit the .sdc file, or Quartus errors out again when I try to do a build.

  • Seadog's avatar
    Seadog
    Icon for Occasional Contributor rankOccasional Contributor
    6 years ago

    I cannot post my design, so I would have to create something which has the same problem, and right now I don't have the spare time for that task.

  • KhaiChein_Y_Intel's avatar
    KhaiChein_Y_Intel
    Icon for Regular Contributor rankRegular Contributor
    6 years ago

    Hi,

    It would be difficult to duplicate the error if we cannot have the test case. Is this happened only for some IP?

    Thanks.