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 What's the difference between -seed and -svseed in irun? 

Last post Mon, Jan 13 2014 3:05 AM by hannes. 3 replies.
Started by monkeyking 12 Jan 2014 07:00 PM. Topic has 3 replies and 4607 views
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  • Sun, Jan 12 2014 7:00 PM

    • monkeyking
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    What's the difference between -seed and -svseed in irun? Reply

    There are two options to control random seed when using irun: -seed, -svseed.

    It seems that these two options is doing the same thing: set a random seed to RNG. And I tried many times, I can't find difference between these two options. Both can be used to control Verilog/SystemVerilog randomization, for example:

    -seed 123

    -svseed 123

    -seed random

    -svseed random

    So, what's the difference between these two options?

    Thanks!

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  • Mon, Jan 13 2014 12:46 AM

    • hannes
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    Re: What's the difference between -seed and -svseed in irun? Reply

     Regarding irun, one thing which is useful is "irun -helpall | grep <word of interest". So irun-helpall | grep seed gives:

      -seed <seed>               Set the seed value for SystemVerilog and Specman
      -snseed <seed>             Pass seed value to Specman
      -svseed <seed>             Set SystemVerilog default RNG seed
     
    Numbers are seeds, "random" will be randomly generated seeds.
     
    Regards,
    -hannes 
    • Post Points: 20
  • Mon, Jan 13 2014 1:49 AM

    • monkeyking
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    Re: What's the difference between -seed and -svseed in irun? Reply

     Hi, Hannes:

    I know these descriptions given by irun, but I'm still not clear about what's the basic difference between "seed value for SystemVerilog" and "SystemVerilog default RNG seed". It seems that both "-seed random" and "-svseed random" can work when do simulation. Right?

    • Post Points: 20
  • Mon, Jan 13 2014 3:05 AM

    • hannes
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    Re: What's the difference between -seed and -svseed in irun? Reply
    yes, that is correct. There is no difference between -seed and -svseed if you have a SystemVerilog testbench. Since IES also handles e testbenches, you have 2 switches to control them individually (-svseed/-snseed) and one which applies to both. This should give you all the flexibility you need.
    • Post Points: 5
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Started by monkeyking at 12 Jan 2014 07:00 PM. Topic has 3 replies.