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Comment by philwelch | Hacker News Reader

Hurd was a microkernel that was a genuine attempt at something new. Linux’s monolithic design was very safe, very 70’s/80’s, and was criticized by everyone for not being a serious 90’s microkernel design.

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This was covered extensively over 25 years ago, including the classic comment by Linus that "In fact the /whole/ linux kernel is much smaller than the 386-dependent things in [the existing microkernel] mach". https://www.oreilly.com/openbook/opensources/book/appa.html

Mach and Hurd were existing microkernels/projects before Linux development began.

Linux dominated because it (partly) worked and was accessible and a community formed around it. Hurd had none of those. It's the canonical proof of Richard Gabriel's prescient "Worse is Better (1991)" http://dreamsongs.com/WIB.html - "The good news is that in 1995 we will have a good operating system and programming language; the bad news is that they will be Unix and C++."

NeXT mach was a microkernel as well based on CMU’s Mach 2.5 (in the first release) and was in the market in 1988. It was actually fantastic, even when I was running 0.7 of the OS in prerelease at LANL. Hurd started in 1990 so it wasn’t NEW new imho (originally based on Mach 3.0 although NeXT went there too). There are other ideological differences but the core mach microkernel ideology started at CMU in 1985 making microkernels an 80s technology as well.

I'm really stretching to remember, but I recall that initially the Hurd was planning to have a completely distributed user system (i.e., file handles were essentially URLs, they had a system for dealing with users distributed in the network, etc). They were going to use the Mach kernel message passing in really innovative ways and I seem to recall that they had in mind some fairly radical ideas for distributed processing. I don't think they ever really realized any of that (I haven't actually checked what they ended up doing). My impression was that the project was dogged with a lot of problems, some technical and some not. Had they succeeded, it would have been a really amazing system, I think. One of these days I keep thinking I should check out what they actually did.

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