[Info-vax] What is a "real" Unix ?

[John Dallman]

In article <ud76ih$1vd35$2 at dont-email.me>,
clubley at remove_me.eisner.decus.org-Earth.UFP (Simon Clubley) wrote:

> Given that most of the Linux kernel-level security flaws appear to 
> be in add-on modules/drivers, it's a pity the microkernel approach 
> wasn't taken as IMHO that would have resulted in a even more secure 
> system.

The problem with microkernels is traditionally performance, or rather,
the overheads of lots of inter-process communication. There are a few
systems that work OK on microkernels in spite of this, such as QNX, 
<https://en.wikipedia.org/wiki/QNX#Technology>

Apple's XNU <https://en.wikipedia.org/wiki/XNU> started as a version of
the Mach microkernel. It isn't a microkernel any more, since it
incorporated most of BSD 4.3.

GNU Hurd is the most epic failure of a microkernel project. It was to be
based on Mach, in the mistaken belief that this would save a lot of work.
The alternative plan was to adopt the 4.4BSD-Lite kernel. Had this
happened, Linus would never have needed to write Linux, and the world
would be rather different. 

<https://en.wikipedia.org/wiki/GNU_Hurd#Development_history>

John