Jay,

Sorry, but to me the VM system and ddb are tiny parts of Mach and has not a  
whole lot to do with the Mach way of doing business, which has a radically  
different philosophy on the backend, reflected in its kernel architecture and  
the single- and multi-server architectures.

Mach mk's are a quite different architecture, much more than just a different  
VM system and debugger.  It would help if you look at BSD4.4 from a Mach mk  
perspective to see what Mach mk's allow you to do that BSD4.4 doesn't, and not  
just look at it the other way round.  I'm not saying that BSD4.4 is bad code  
by any stretch of the imagination.  However, the are differences in design and  
application which are quite significant and go far beyond things like VM and  
debugger.

Suggested reading on that can be found at CMU's Mach home, Open Group (OSF)  
and U of Utah's Mach4.  There are things in Mach mk based OS's that are simply  
not possible (unless you would like to revamp a large portion of the kernel  
architecture) with the current kernel engineering in BSD4.4.

That, and my personal work on Mach mk and server implementations over the  
years, makes me stand firmly by my statement. Therefore,  I reject your  
assertion of my remark being "plain wrong".

Best regards,
Chris


On Fri, 07 Feb 97 11:19:52 -0800, "Jay Kistler" <jjk@pa.dec.com> wrote:
> > There are no really relevant, characteristic parts of Mach incorporated
> > into the way NetBSD does business.
>
> This is just plain wrong.  The whole VM system was adapted from Mach,
> as explained in the 4.4BSD book (McKusick et al).  Try grep'ing for
> 'Mach Operating System' in vm/*.[ch].  Managing virtual memory is
> a fundamental aspect of "the way NetBSD does business" in my view.
>
> The current NetBSD kernel debugger, ddb, was also lifted from Mach.
>
>
> -Jay
>
>
--
Christian Kuhtz <chk@gnu.ai.mit.edu>
                                                          ".com is a mistake."