Path: utzoo!attcan!uunet!husc6!mailrus!rutgers!ucsd!sdcc6!sdcc12!mp1
From: mp1@sdcc12.ucsd.EDU (Leroy Dorman)
Newsgroups: comp.unix.microport
Subject: Re: Physical memory access with SystemV/AT
Summary: Let's get physical . . . Can't get there from here (?)
Message-ID: <1019@sdcc12.ucsd.EDU>
Date: 13 Jun 88 04:49:47 GMT
References: <185@focsys.UUCP>
Distribution: na
Organization: University of California, San Diego
Lines: 22

In article <185@focsys.UUCP>, larry@focsys.UUCP (Larry Williamson) writes:
> I would like to do something like:
> 	shmcreate 0x800000 800000 1048560
> to create a 1Meg shared memory segment at the 8meg address location.

Unless Microport put in a peek/poke-style function in to V/AT,
(the Rel 1.0 from At&t didn't have one)
there's no way to access physical memory from u-space. A device
driver could get to where you want to go by twiddling a selector
to get the right addresses but talking to the driver through
ioctls or writes probably would be too slow

You're right, it sure would be nice to assign a physical memory
location to a segment selector so you can get at it in
large-model user space programs.  Poke, poke, uPort . . :-)
-------------------------------------------------------------------
Eric Dorman				Chekov-"The whole Gamma 7A
University of California, San Diego	   System is, dead, sir.
Scripps Institution of Oceanography	   Just, dead."
 siolmd!eric@sdsioa.ucsd.edu		      From- "The Immunity
 mp1@sdcc12.ucsd.edu  Attn: eric		     Syndrome"
 dorman@mplvax.nosc.mil  Attn: eric