A Differential Test Harness for Native vs. Generic XDP: Methodology and Baseline

Short summary

This post releases an open differential test harness for comparing native vs generic (SKB-mode) XDP behavior in the Linux kernel, including an eleven-packet corpus and a divergence taxonomy. The same BPF program can pass the verifier yet produce different verdicts or frame bytes depending on which XDP mode the kernel uses, creating operational risk for firewalls or rate-limiters that fall back to generic mode on unsupported drivers. The baseline is established on virtio/veth with Linux 6.8, with a bare-metal follow-up planned.

• •Open differential test harness compares native vs generic XDP outcomes using a fixed eleven-packet corpus
• •Identifies operational risk: same BPF bytecode can yield different verdicts or frame bytes across XDP modes
• •Baseline established on virtio/veth (Linux 6.8); bare-metal NIC divergence results planned for part 2

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