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Dealing with ThreadSanitizer Fails on Startup

A typical iconic Kyrgyzstan view.

Usually, you need just a few lines to initialize TSan in your project: you compile with the sanitizer flags, run the tests, and get a clear report of which threads touched which memory locations. On a modern Linux system, that simple expectation can fail in a very non-obvious way.

FATAL: ThreadSanitizer: unexpected memory mapping 0x...

In my case, I attached TSan to a not-so-young C++ codebase and immediately encountered a fatal runtime error from the sanitizer, long before any of the project's code executed. No race report, no helpful stack trace, just a hard abort complaining about an "unexpected memory mapping."

If you can upgrade your toolchain to LLVM 18.1 or newer, this problem effectively disappears, because newer TSan builds know how to recover from the incompatible memory layout. Suppose you are pinned to an older LLVM (by CI images, production constraints, or corporate distro policy). In that case, you are in the same situation I was: you have to understand what the sanitizer is trying to do with the address space, and work around the failure mode yourself.

Cross-Compiling Rust for Raspberry Pi

I just started a new embedded pet project on the Raspberry Pi, and I expect it'll be a pretty big one, so I've been thinking about the technology from the beginning. The overall goal is to create a glass-to-glass video pipeline example. Let's see how it's going. For now, I'm using a USB V4L2 camera while waiting for the native Pi modules to arrive, but it's enough to sketch the capture loop and start testing the build pipeline. The application itself is minimal—open /dev/video0, request YUYV at 1280x720, set up MMAP buffers, and iterate over frames—but the real challenge occurs when v4l triggers bindgen, and the build must cross-compile cleanly for aarch64. 

The language choice immediately becomes part of the equation right away. Go is my favorite and, usually, is not considered as an option by many embedded developers. But it's a good choice for small embedded utilities because its cross-compilation story is nearly effortless. Need an ARM binary? One command and you have it!

GOOS=linux GOARCH=arm64 go build

Minimal CI for Go library with GitHub actions

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Continuous Integration (CI) has become an essential part of modern software development, and for good reason. It ensures code quality, speeds up development, and catches potential issues early. However, you can get started without an elaborate CI setup. Even a minimal CI setup can significantly improve your workflow. Here's why every project should have at least minimal CI and how to implement it effectively using GitHub Actions.

What Constitutes Minimal CI?

For a project to benefit from CI without excessive complexity, it should include the following essential components:

  1. Project Compilation: Verify that the codebase is always in a buildable state.
  2. Unit Test Execution: Ensure the core functionality works as expected.
  3. Static Code Analysis: Catch bugs and enforce coding standards before they become an issue.