ACPI in Practice: a Power Button Driver for FreeBSD 15.0

⚡ The gist in 5 seconds - Habr has published a detailed write-up on developing a Power button driver for FreeBSD 15.0 via ACPI. - The test bench is a working HP Laptop 15s, on which the author persuaded a colleague to install FreeBSD 15.0. - This is an educational piece on ACPI and drivers, not an announcement of a patch in the FreeBSD source tree. ### 🔍 What was found Habr has published a piece titled “Learning ACPI through developing a Power button driver for FreeBSD.” The starting point is a hands-on experiment: the author persuaded a colleague to install FreeBSD 15.0 on a work HP Laptop 15s; the colleague, according to the author, was already somewhat familiar with the OS. It is on this configuration that ACPI is dissected — from tables and the event mechanism to writing a driver that handles power button presses. The mechanics are presented through driver development: how the FreeBSD kernel receives ACPI events, how to intercept them, and what it takes to make the Power button behave predictably rather than only through the default handler. Exact flag names, code structure, and build commands are in the article itself at the link. ### 💡 Why it matters ACPI is a weak spot not only for FreeBSD but for any OS on laptops: manufacturers test primarily against Windows, and non-standard event handling (power, lid, sleep) surfaces precisely on “non-native” systems. Write-ups like this are rare: they show driver development not on an abstract board but on a mass-market consumer laptop, and give a starting point to anyone who wants to fix Power button behavior or get to grips with ACPI in the FreeBSD 15.0 kernel.