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Printk Should Be Your Last Resort - Sundeep Subbaraya, Marvell
This session will provide a walkthrough of Linux kernel tracing capabilities, demonstrating live debugging techniques for Linux drivers using a dummy netdev driver. We will explore various kernel debugging facilities and how to infer real-time insights without relying on printk debugging.
Attendees will gain hands-on exposure to:
ftrace: Understanding code execution paths.
Tracepoints in driver code: Gaining insights into driver internals.
Using ftrace + tracepoints to analyze kernel behavior efficiently.
kprobes & kretprobes: Hooking into kernel functions for deeper debugging.
perf: Checking variable values inside a driver function.
bpftrace: Advanced tracing capabilities.
Live demo of a custom kernel eBPF program and userspace counter part (written in C) to detect memory leaks in the dummy netdev driver.
Motivation:
As a seasoned Linux driver developer with 14+ years of experience, I’ve been frustrated with traditional printk-based debugging—especially when collaborating with customers. Over time, I’ve mastered more efficient debugging techniques using built-in kernel tracing tools.