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

Seadog
Beginner
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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.

 

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KhaiChein_Y_Intel
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Hi,

 

You can use either of the following to indicate the source node for the generated clock

  • get_keepers
  • get_nets
  • get_pins
  • get_ports
  • get_registers

You may refer to https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/manual/mnl_sdctmq.pdf Chapter 2 to check the differences.

 

Thanks.

 

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Seadog
Beginner
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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.

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KhaiChein_Y_Intel
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Can you share the error messages, steps to reproduce the error, the software edition (Pro/Standard/Lite) and the software version ?
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sstrell
Honored Contributor III
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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

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Seadog
Beginner
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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.

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KhaiChein_Y_Intel
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Hi,

 

Any updates?

 

Thanks.

 

-YY

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sstrell
Honored Contributor III
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Can you post your original .sdc?

 

#iwork4intel

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Seadog
Beginner
1,445 Views

no

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KhaiChein_Y_Intel
1,445 Views

Hi,

 

Can you provide a sample test case to reproduce the error?

 

Thanks

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Seadog
Beginner
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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.

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KhaiChein_Y_Intel
1,445 Views

Hi,

 

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

 

Thanks.

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Seadog
Beginner
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I can't say what IP (if any) caused it.

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KhaiChein_Y_Intel
1,445 Views

Hi,

 

Could you share some simple steps to reproduce the error?

 

Thanks.

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KhaiChein_Y_Intel
1,445 Views

Hi,

 

May I know if you have any updates?

 

Thanks.

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