Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!auspex!guy
From: guy@auspex.auspex.com (Guy Harris)
Newsgroups: comp.unix.questions
Subject: Re: Virt Mem on V.4
Message-ID: <1870@auspex.auspex.com>
Date: 1 Jul 89 04:37:10 GMT
References: <1515@ncr-sd.SanDiego.NCR.COM>
Reply-To: guy@auspex.auspex.com (Guy Harris)
Distribution: usa
Organization: Auspex Systems, Santa Clara
Lines: 30

>I am working in a kernel group which is porting AT&T's V.4 to our
>new  hardware.   I  am  trying  to  understand  the  new Virt Mem
>architecture  in  V.4  and  would  appretiate  any  recomendation
>regarding  articles  which describe this topic.  I am looking for
>papers which describe the data structures and algorithms used.

Try:

	*Virtual Memory Architecture in SunOS*, from the Summer 1987
	    USENIX proceedings

	*SunOS Virtual Memory Implementation*, from either the most
	    recent EUUG proceedings or the one before that, I think

(V.4's VM implementation is derived from the SunOS 4.0 one, although
there are differences in a few details).  They aren't extremely
detailed, but they do cover a fair bit at a relatively high level.

With any luck, all you'll have to do is write a "hat (Hardware Address
Translation) layer" for your MMU, which'll just plug into the rest of
the VM subsystem.  (If the new hardware uses a 68020+PMMU, or a 68030 or
so - i.e., if it's using a Motorola-style MMU - you might just see if
Sun'll sell you their 4.0 implementation; I have no idea if they will,
but it's worth a try....)  If you *do* have to do more, let AT&T (and
possibly Sun) know, so that with any luck the implementation can be
modified to let the new "hat layer" plug into it in the future.

While you're at it, point the languages people at *Shared Libraries in
SunOS* in the Summer 1987 USENIX proceedings for some information on how
the shared library mechanism works in V.4....