No Loopback Is Configured, and Error Code -8005 or -8001 Is Reported During the Stream Test or Diagnosis

Symptom

[****@******]# ascend-dmi --dg -i prbs -q
Summary:
    Arch: aarch64
    Mode: *****
    Time: 20250414-15:16:43

Hardware:
    prbs:
        FAIL
        *** error occured on device 0
        *** error occured on device 1

The following error information is displayed in the log:

[WARN][2025-04-14 15:15:46][76270][prbs_thread.cpp ControlTransPrbsCodeStream:86] call dcmi_prbs_operate failed. type=8, direction=1, cardId=3, chipId=0, ret=-8005
[WARN][2025-04-14 15:15:46][76270][prbs_thread.cpp ExecPrbsCodeStream:229] start prbs trans failed on device 3
[WARN][2025-04-14 15:15:47][76270][prbs_thread.cpp ControlTransPrbsCodeStream:86] call dcmi_prbs_operate failed. type=8, direction=1, cardId=6, chipId=0, ret=-8001
[WARN][2025-04-14 15:15:47][76270][prbs_thread.cpp ExecPrbsCodeStream:229] start prbs trans failed on device 6

Possible Causes

The driver version is 25.0.RC1 or later, loopback is not configured, and the SNR verification fails when a stream is sent.

Solution

Configure a CDR loopback or external fiber optic circulator. After the network port is up, send streams again.