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Occasional ContributorFitter 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
SeadogThanks. 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_IntelRegular Contributor
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.
