Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!uakari.primate.wisc.edu!aplcen!visual1.jhuapl.edu!dave
From: dave@visual1.jhuapl.edu (Dave Weintraub)
Newsgroups: comp.lang.asm370
Subject: Re: New System/3x0 Instruction
Message-ID: <1991Mar13.145359.8430@aplcen.apl.jhu.edu>
Date: 13 Mar 91 14:53:59 GMT
References: <9103130448.AA28489@ucbvax.Berkeley.EDU>
Sender: news@aplcen.apl.jhu.edu (USENET News System)
Reply-To: dave@visual1.jhuapl.edu (Dave Weintraub)
Distribution: inet
Organization: Johns Hopkins University
Lines: 34

YIn article <9103130448.AA28489@ucbvax.Berkeley.EDU>, USERALVE@RPITSMTS.BITNET (Brian Eliot) writes (in replay to Bruce Richardson's comments
on my suggested Move and Discard instruction):

|> MVPG is not a fully-documented instruction.  Only its behavior from
|> the viewpoint of the virtual-address-space program is described.
|> Extensions to the page-table-entry format and such to support mapping
|> pages into expanded storage are not in the Principles of Operation.
|> Therefore, I don't see how Dave Weintraub or anyone else for that
|> matter can tell whether MVPG will meet a particular need.
|> 
|> Perhaps if Amdahl has reverse-engineered MVPG you could give us a
|> description of how it works?
|> 
|> Brian Eliot
|> Information Technology Services
|> Rensselaer Polytechnic Institute

Thank you, thank you Brian, for expressing what I have been trying to
compose for a day now.  Our chief systems programmer and I got into
a disagreement about exactly what Move Page DOES, let alone whether
it would satisfy the intent of my requirement (as our 5890 does not
support Move Page (we cannot justify the upgrade), I could not
run a test, to see whether "replacement"  is to be taken literally,
as Bruce Richardson's post would indicate (and which would
take care of a part of my requirement), or if it means "copy").

Of course, Move Page does not appear in the Index yet (at least in the -0
documentation, and the TNLs do not update the index pages),
and I should point out that in discussion at SHARE with about a dozen
IBM systems types, not one suggested the Move Page as a way of handling the
requirement.

I concur that I would love to see more explanation of the intent and effect
of this instruction, certainly before proceeding with the MDCL requirement.