Solving the Raspberry Pi HW CSum Failure Issue

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Today when I logged into my Raspberry Pi and ran df to check disk space as usual, I discovered the TF card was almost full. Initially I thought I had misconfigured settings, causing download files to save to the TF card instead of the external hard drive. After troubleshooting, I found that log files under /var/log occupied a staggering 18G of space. Checking the logs revealed continuous error messages like:

Jan 25 22:51:15 lantian-rpi3 kernel: [   22.143274] eth0: hw csum failure
... [original log content unchanged] ...
Jan 25 22:51:15 lantian-rpi3 kernel: [   22.143755] 3fe0: 76f2ace4 7e9b5cc0 76b29dd4 0006ac00 60000010 ffffffff

That is, the Raspberry Pi's Ethernet interface was generating massive errors, causing the kernel to continuously output stack traces that bloated the log files. Since my Raspberry Pi was used for on-campus PT seeding with sustained 5MB/s+ upload/download traffic, the log volume was substantial.

The "HW CSum" error refers to "Hardware Checksum Offloading" – a feature that offloads packet checksum verification to the NIC to reduce CPU usage. To troubleshoot, I disabled this feature using ethtool:

apt-get install ethtool
ethtool --offload eth0 rx off tx off

After disabling, dmesg stopped showing these errors. Re-enabling the feature:

ethtool --offload eth0 rx on tx on

Immediately caused the errors to reappear in dmesg, confirming HW CSum as the culprit.

While disabling HW CSum is a temporary fix, this should ideally be resolved through kernel/driver updates. However, after running raspi-update to update the kernel and drivers, the issue persisted, forcing me to keep HW CSum disabled.

Edit /etc/network/interfaces.d/eth0 (create it if missing) and add:

allow-hotplug eth0
iface eth0 inet dhcp
    offload-rx off
    offload-tx off

This will automatically disable HW CSum via ethtool during system startup.