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Seadog
Beginner
463 Views

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.

 

0 Kudos
14 Replies
117 Views

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.

 

Seadog
Beginner
117 Views

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.

117 Views

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

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
Beginner
117 Views

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.

117 Views

Hi,

 

Any updates?

 

Thanks.

 

-YY

sstrell
Honored Contributor II
117 Views

Can you post your original .sdc?

 

#iwork4intel

Seadog
Beginner
117 Views

no

117 Views

Hi,

 

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

 

Thanks

Seadog
Beginner
117 Views

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.

117 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.

Seadog
Beginner
117 Views

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

117 Views

Hi,

 

Could you share some simple steps to reproduce the error?

 

Thanks.

117 Views

Hi,

 

May I know if you have any updates?

 

Thanks.

Reply