# Mach kernel

7 Hacker News commenters recommended Mach kernel and 10 criticized it, November 2025 to November 2026. It was recommended in 6 of 13 months.

**Verdict:** Old free microkernel praised for its virtual memory API and design, but critics say its IPC overhead is high and it lags newer microkernels like L4.

## Why people recommend it

- Useful for building real projects (2 comments): "In Mach we are able to just zig build to build GUI apps against an ~8 year old glibc version" ([source](https://news.ycombinator.com/item?id=49355879)) "It's been a great boon to this project and I have zero regrets" ([source](https://news.ycombinator.com/item?id=48462672))
- Appealing design and virtual memory API (2 comments): "IMO the Mach virtual memory API is much nicer than the Linux one." ([source](https://news.ycombinator.com/item?id=49519077)) "I've always liked the Mach approach." ([source](https://news.ycombinator.com/item?id=48432972))

## What people warn about

- High microkernel IPC overhead (6 comments): "So is Mach, by the way, if you can afford the microkernel performance overhead." ([source](https://news.ycombinator.com/item?id=46536747)) "the old microkernels, like Mach and all those inspired by it, was indeed too high due to context switches" ([source](https://news.ycombinator.com/item?id=49056402)) "Mach is not a very good microkernel at all, because the overhead is much higher than necessary." ([source](https://news.ycombinator.com/item?id=46537081))
- Dated design versus newer microkernels (4 comments): "the negative aspects of Mach’s design are a technical albatross around the neck of any kernel" ([source](https://news.ycombinator.com/item?id=46859865)) "dramatic performance improvements of L4 over first-generation microkernels like Mach" ([source](https://news.ycombinator.com/item?id=48008276)) "Mach is not a representative proxy for microkernels in 2026." ([source](https://news.ycombinator.com/item?id=49057756))

## Alternatives hackers recommend

- [Windows](https://hackerapproved.com/p/windows.md): 1287 recommend
- [macOS](https://hackerapproved.com/p/macos.md): 1041 recommend
- [Linux](https://hackerapproved.com/p/linux.md): 745 recommend
- [Haiku](https://hackerapproved.com/p/haiku-os.md): 115 recommend
- [NetBSD](https://hackerapproved.com/p/netbsd.md): 100 recommend

## Cite as

Hacker Approved, "Mach kernel", https://hackerapproved.com/p/mach/ (counts from 1,795,640 Hacker News comments, November 2025 to November 2026).