[rescue] OS X is certified UNIX

[Patrick Giagnocavo]

On Jun 14, 2007, at 4:05 AM, Geoffrey S. Mendelson wrote:
> In the non BSD world, they merged around 1990 with System V release  
> 3.2 which included
> many of the BSD commands in /usr/ucb/bin, which could be added to  
> your path as an option.
> It also included TCP compatability with BSD STREAMS. System V  
> release 4 was the real
> combination, just about everything included in BSD was included in  
> UNIX.
>
I think you need to go back and research some stuff - you might be  
mis-remembering a few things.

BSD did not have STREAMS, that was something that came from ATT.  BSD  
had sockets, which STREAMS was an attempt to get away from because  
sockets were believed to be too specific to TCP/IP, which was only  
one of several different popular networking protocols at the time.

> Next's BSD was based on a modified BSD Kernel with the Mach (is it  
> an acronym or
> named after the scientist?) Kernel on top of it. It also included  
> BSD commands.
>

No.

Mach is a microkernel with a BSD compatibility layer on top of it.   
The kernel has messaging primitives in it called "ports" that  
different programs could use to communicate with each other.   As far  
as including BSD commands, those would be in userland of course.

Mach v2.5 still had most stuff, including BSD layer and hardware  
drivers, all in the kernel.  Mach 3.0 came out and generated a decent  
amount of interest, but then Apple bought Next and they were focused  
on the GUI and integration with MacOS 9.  Not sure how much of Mach  
3.0 is in later versions of OSX.

Part of the Mach design was different enough that efficient shared- 
memory in the style of other Unices was difficult to implement.  They  
also had some other issues, like slow task switching due to needing  
to check permissions on ports for each access.

Patrick Giagnocavo
patrick at zill.net