This article explains the log message "SGLINK(RD-err): GBUS error [0x8] at device 0x0, address 0x700140, timeout error".

The log occurs because the CB, as a critical component of the system, detected an operational failure that could impact the device's functionality.

• SG Link Read Error (RD-err):

  • The CB uses the SG Link to manage data transfers between control plane components and other hardware, such as forwarding engines, line cards, and ASICs.
  • A read error signifies that the CB failed to retrieve the required data from a hardware device or memory address over this link.

• GBUS Timeout (Error [0x8]):

  • The GBUS is the internal communication backbone connecting the CB to other components (e.g., PFEs, ASICs, or memory modules).
  • A timeout error (error code [0x8]) means the CB sent a request but did not receive a response from the addressed device (device 0x0) or memory address (0x700140) within the expected timeframe.
    
    

• Address Mapping:

  • The address 0x700140 might represent a specific register, control status, or memory location on a hardware component (e.g., an ASIC or PFE).
  • Failure to access this address could mean:
    • The hardware device at the address is unresponsive or malfunctioning.
    • The address is invalid or improperly mapped.
      
      

• Timeout Handling:

  • When the CB experiences a timeout in accessing critical resources or devices, it triggers an alarm to warn of potential disruptions or degraded performance.

The error message will raise a minor alarm for the Control Board (CB).

> show system alarms
2 alarms currently active
Alarm time Class Description
<time> <date> Minor CB 0 Fabric Chip 0 Not Online
<time> <date> Minor CB 0 Fabric Chip 1 Not Online

Log Message:

<time> <date>  re0.<device-name> kernel: SGLINK(RD-err): GBUS error [0x8] at device 0x0, address 0x700140, timeout error
<time> <date>  re0.<device-name> kernel: SGLINK(RD-err): GBUS error [0x8] at device 0x0, address 0x700140, timeout error
<time> <date>  re0.<device-name> kernel: SGLINK(RD-err): GBUS error [0x8] at device 0x0, address 0x700358, timeout error
<time> <date>  re0.<device-name> kernel: SGLINK(RD-err): GBUS error [0x8] at device 0x0, address 0x700140, timeout error
<time> <date>  re0.<device-name> kernel: SGLINK(RD-err): GBUS error [0x8] at device 0x0, address 0x700140, timeout error

<time> <date> re0.<device-name>kernel: FCHIP_RD: GBUS error [0x8] at device 0x0, address 0x700140, timeout error
<time> <date> re0.<device-name> chassisd[23249]: XFCHIP_IOERR 1: PORT read  XF_DROP 0x40510c -> 0 failed
<time> <date> rre0.<device-name> chassisd[23249]: CHASSISD_SNMP_TRAP10: SNMP trap generated: fabric plane offline (jnxFruContentsIndex 12, jnxFruL1Index 1, jnxFruL2Index 0, jnxFruL3Index 0, jnxFruName CB 0, jnxFruType 5, jnxFruSlot 0, jnxFruOfflineReason 2, jnxFruLastPowerOff 0, jnxFruLastPowerOn 22)
<time> <date> re0.<device-name> alarmd[28405]: Alarm set: CB id=134217846, color=YELLOW, class=CHASSIS, reason=CB 0 Fabric Chip 0 Not Online
<time> <date> re0.<device-name> craftd[23254]:  Minor alarm set, CB 0 Fabric Chip 0 Not Online

Suppose the Control Board (CB) is momentarily overwhelmed with tasks, such as processing high-control traffic or responding to hardware events. In that case, this error may appear temporarily and should be cleared automatically. 

If the log message persists then please collect the output for the below commands:

• show chassis alarms
• show chassis environment cb
• show chassis fabric plane
• show chassis fabric map
• show chassis fabric summary
• show log messages| match fabric
• show log chassisd | match fabric