Loop Partition Changed When AC Power Cycling Test

Issue Overview

The issue discussed revolves around the Nvidia Jetson Orin Nano Dev board, specifically concerning the behavior of loop partitions during an AC power cycling test. Users have reported that after performing the test—consisting of 1000 cycles of powering on and off the device at extreme temperatures of -20°C and 60°C—the loop partition changes from loop0 to loop1. This change causes the test to halt unexpectedly.

Specific Symptoms

• The loop partition changes from loop0 to loop1 after repeated power cycling.
• The issue manifests during a controlled testing environment where the system is powered on, allowed to boot, and then powered off after a set duration.

Context

• The problem occurs specifically during AC power cycling tests involving temperature extremes.
• The Jetpack version reported by users is JP5.11, with suggestions to verify against JP5.1.2 (R35.4.1).
• Users have not attempted to replicate this issue on the development kit due to hardware availability constraints.

Frequency and Impact

• The issue appears consistently under the described testing conditions, leading to halted tests and potential data integrity concerns.
• It impacts user experience by introducing uncertainty in testing protocols and may affect reliability assessments of the hardware in extreme conditions.

Possible Causes

• Hardware Incompatibilities or Defects: The Orin Nano 4GB may have specific hardware issues that manifest under high-stress conditions.

• Software Bugs or Conflicts: The Jetpack version might contain bugs that affect device enumeration and management during rapid power cycling.

• Configuration Errors: Incorrect system configurations could lead to improper handling of loop devices upon reboot.

• Driver Issues: Problems with the loopback driver may cause it to mismanage device identifiers during reinitialization.

• Environmental Factors: Extreme temperatures could affect hardware performance and timing, leading to unexpected behavior in device enumeration.

• User Errors or Misconfigurations: Improper setup or expectations regarding loop device behavior could lead to misinterpretation of normal operations as errors.

Troubleshooting Steps, Solutions & Fixes

Step-by-Step Diagnosis

1. Check Device Status:

   • Use the command:

     sudo fdisk -l
     

   • Compare outputs before and after the issue occurs.

2. Inspect System Logs:

   • Review dmesg logs for any relevant messages related to device initialization:

     dmesg > loop1_dmesg.txt
     

3. Verify Jetpack Version:

   • Confirm the Jetpack version in use; consider updating to JP5.1.2 (R35.4.1) if not already done.

4. List Loop Devices:

   • Execute:

     losetup --list | sort
     

   • Capture outputs during normal operation and when the issue occurs for comparison:

     losetup --list | sort | tee log_works_correct.txt
     losetup --list | sort | tee log_fail.txt
     

Isolation Techniques

• Attempt to reproduce the issue on a different board or development kit if available.
• Test with varying temperatures and monitor for differences in behavior.

Potential Fixes

• If using a custom board, consider testing with an official Nvidia development kit (e.g., Nano 8G) to rule out hardware-specific issues.

• Ensure all firmware and software are up-to-date, particularly concerning drivers related to USB and loop devices.

Best Practices

• Implement logging mechanisms in scripts that monitor loop device status before and after power cycling tests.

• Consider adding delays between power cycles to allow for proper device initialization.

Unresolved Aspects

While several users have noted that changing from loop0 to loop1 may not be a bug but rather expected behavior under certain conditions, further investigation is needed into:

• The exact timing mechanisms that dictate loop device enumeration during boot.
• Any residual files or states that may prevent proper reset of loop devices across power cycles.

By following these steps, users can better diagnose and potentially resolve issues related to loop partition changes during AC power cycling tests on the Nvidia Jetson Orin Nano Dev board.