Claude Code takes on QNX Big Kernel Lock removal, starting with userspace contention stats

A developer on r/ClaudeAI shared their experience using Claude Code to tackle a major kernel engineering challenge: removing the Big Kernel Lock (BKL) from the QNX microkernel and proc subsystem. The conversation kicked off with a direct question to Claude Code: "What will it take to re-design the QNX microkernel and proc to get rid of the Big Kernel Lock?"

Claude Code responded: "Roughly, 3 months of intensive work of a top-developer [human]." The developer replied, "Let's get started then," and the AI assistant got to work.

First step: measurement infrastructure

Instead of diving into code changes, Claude Code's first move was to design comprehensive statistics about locking and contention, made available from userspace — similar to Linux's /proc entries. This instrumentation allowed the developer to measure where contention was actually happening before attempting any fixes.

Incremental subsystem-by-subsystem fixes

After gathering measurements, Claude Code began meticulously fixing kernel subsystems one by one. Each major change was followed by thorough testing. The developer notes: "Let's see where this leads to."

The post is an early-stage report; the full removal of the BKL is still in progress. The approach — instrument first, then fix — mirrors established kernel development best practices.