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From: chris@umcp-cs.UUCP (Chris Torek)
Newsgroups: net.unix-wizards
Subject: Re: memory mapping question
Message-ID: <2998@umcp-cs.UUCP>
Date: Sat, 1-Feb-86 22:06:18 EST
Article-I.D.: umcp-cs.2998
Posted: Sat Feb  1 22:06:18 1986
Date-Received: Mon, 3-Feb-86 05:39:31 EST
References: <2134@brl-tgr.ARPA>
Organization: U of Maryland, Computer Science Dept., College Park, MD
Lines: 23

In article <2134@brl-tgr.ARPA> dms@mit-hermes.arpa writes:

> I was wondering if physical memory is mapped into a portion of the
> system address space?

Physical memory has physical addresses, sure.  But there is no really
easy direct way to get at physical memory once you go into mapped mode.

> I guess the answer to this question lies in how the Sysmap is setup? 

Yes, though now you are speaking of specific kernel code, not of
the Vax architecture itself.  There is no one place in Sysmap that
maps all of physical memory, but you can get at it a little bit at
a time by creating a map, dropping it into locore.s, and using

	*(int *)mymap = btop(physaddr) | PG_V | PG_KW;
	mtpr(TBIS, vmymap);

`Just like vax/mem.c.'
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 1415)
UUCP:	seismo!umcp-cs!chris
CSNet:	chris@umcp-cs		ARPA:	chris@mimsy.umd.edu