Article ID: 000075370 Content Type: Troubleshooting Last Reviewed: 05/25/2017

Why does the runt statistics register of Legacy 40/100G Ethernet IP core read back as "X" in simulation?

Environment

  • Stratix® V GX FPGA
  • Stratix® V GS FPGA
  • Stratix® V GT FPGA
  • Intel® Quartus® Prime Pro Edition
  • Ethernet
  • BUILT IN - ARTICLE INTRO SECOND COMPONENT
    Description

    Due to a change in runt handling behavior in Quartus® Prime v16.1, the runt statistics register may read back as "X" in simulation in the Legacy 40/100G Ethernet Megacore®.

    Normal core behavior is not affected, but when running the KR4 example testbench, the following messages may be seen:

    # DUT 1 Sent                1027 packets
    # DUT 2 Received           1027 packets
    # Runts in RX data
    # DUT 2 Sent                1027 packets
    # DUT 1 Received            1027 packets
    # Runts in RX data

    These messages can be safely ignored.

    Resolution

    This problem will be fixed in a future version of the Quartus prime software.

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