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pjmlp 2 days ago

OS X was never a proper micro-kernel, rather an hybrid one like Windows NT, using still a micro-kernel like approach but with subsystems on the same process space.

https://fahrplan.events.ccc.de/congress/2007/Fahrplan/attach...

https://www.amazon.de/-/en/Mac-OS-Internals-Approach-paperba...

If anything it is going more into that direction, after Apple announced removing all kernel extensions, and having userspace counterparts to them.

https://developer.apple.com/documentation/SystemExtensions

https://developer.apple.com/documentation/systemextensions/i...

Usually it takes one OS version between introducing new userspace APIs, and removing the old way on the following version.

wpm 2 days ago | parent [-]

Apple removed third-party kernel extensions (and even so only removed the ability to install them without going into recovery and changing a scary box). There are still lots of .kext files in the /System folder for hardware drivers.

pjmlp 2 days ago | parent [-]

Yes, however that brings it closer to a micro-kernel model, if no one else is allowed to change the kernel as shipped from factory, having everything else done in userspace.

Additionally, if there is a userspace extension to an existing kernel extension, the userspace one will take precedence.