The thing you have to understand about “AIX” is that historically it was not a single codebase, it was just a common brand for multiple unrelated IBM Unix offerings. (DB2 is the same story.) One of those offerings was AIX/ESA for IBM mainframes - and that was indeed based on the OSF/1 microkernel. But AIX/ESA died in the early 1990s-it was replaced by turning MVS aka OS/390 into a certified Unix, a role carried on by z/OS today, and later on by z/Linux as well. Whereas, the only AIX that survives to this day is the RS/6000 branch which isn’t based on OSF/1, and has a classic monolithic kernel design. Its distant ancestor, AIX version 1 for the RT PC, did use a microkernel (VRM), but that microkernel was very different from Mach and OSF/1 (it was written in a PL/I dialect, PL.8, that’s how alien it was)
This is incorrect.
The thing you have to understand about “AIX” is that historically it was not a single codebase, it was just a common brand for multiple unrelated IBM Unix offerings. (DB2 is the same story.) One of those offerings was AIX/ESA for IBM mainframes - and that was indeed based on the OSF/1 microkernel. But AIX/ESA died in the early 1990s-it was replaced by turning MVS aka OS/390 into a certified Unix, a role carried on by z/OS today, and later on by z/Linux as well. Whereas, the only AIX that survives to this day is the RS/6000 branch which isn’t based on OSF/1, and has a classic monolithic kernel design. Its distant ancestor, AIX version 1 for the RT PC, did use a microkernel (VRM), but that microkernel was very different from Mach and OSF/1 (it was written in a PL/I dialect, PL.8, that’s how alien it was)