[disordinary]

Basically Linux and then BSD took all the wind out of Hurds sails. A lot of that was timing, and also because those projects were much more attractive to big business who put a tremendous amount of development resources behind them.

As far as I know QNX is the only usable OS based on a microkernel.

[buserror]

Errr... OSX and iOS are also MACH based. I'd call them 'usable' ? :-)

Funny bit is, back in the 90's when Apple bough NeXT, they trashed the NeXT version of MACH and used the one that was in... mklinux instead!

I bet very few people remember that bit. I remember because I had written the framebuffer console driver for mklinux back then, and seeing my init message when booting the earlier version of OSX (<=10.1 ish, perhaps a bit later too)

So I had the privilege of printing kernel crash logs and panics on zillions of devices! I'm so proud! :-)

[disordinary]

It's classed as a hybrid though, not a pure microkernel. There's significant amounts of BSD in there.

Also, thanks for the anecdote :)

[pjmlp]

Quite a few embedded OSes are microkernels, L4 being one of them.

[disordinary]

Interestingly L4 is being used to power the secure enclave on iOS devices so it's probably the most distributed microkernel.

[lokedhs]

There was a plan to move Hurd to use L3 instead of Mach, but apparently that project was cancelled.