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From: Alexey Pialkin <pialkin@abel.pdmi.ras.ru>
Message-Id: <199609201033.OAA19193@abel.pdmi.ras.ru>
Subject: Re: New doscmd available for testing/munching
To: msmith@atrad.adelaide.edu.au (Michael Smith)
Date: Fri, 20 Sep 1996 14:33:46 +0400 (MSD)
Cc: sos@freebsd.org, j_mini@efn.org, msmith@atrad.adelaide.edu.au,
        emulation@freebsd.org
In-Reply-To: <199609201011.TAA14497@genesis.atrad.adelaide.edu.au> from "Michael Smith" at Sep 20, 96 07:41:14 pm
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> sos@freebsd.org stands accused of saying:
> > > 
> > > The problem is not with just screen mapping for drawing something(open 
> > > screen memory for drawing is simple just mmap some part of /dev/mem & viola ...)
> > > My problem is that i am unabl to properly map some shadow screen for 0xA0000-0xB0000 address.... It's highly needable for programs working with screen background..
> > 
> > Hmm, I'm not sure we can do that, try ask John Dyson about that, he
> > is out "mastermind" in vm stuff...
> 
> My 'conceptual model' for this went something like :
> 
> - allocate 128K in the emulation process for screen memory.
> - when vt is activated, copy the area that falls under the physical screen
>   memory to a temporary store.
> - mmap the screen memory onto your emulation's buffer.
> - copy your temporary store back.
> - when vt is deactivated, reverse the process.

Great.. The most funny thing that i am trying to do the same thing :( And no
result.. BTW problem is with mmap the screen memory onto emulation buffer ..
Somthing wrong there .. But what ?
 
> ... but I really don't know what happens when you mmap() screen memory
> onto a section of your process' space that is already mapped.  Or would

The only one thing i know :) - mmap() doesn't return any error. And mmaping
porion of /dev/mem works fine.

> you swap between a mapping to screen memory and a file?  Or could you
> map to _both_ screen memory and a file...?

What do you mean by file ? The only one way is to map something is to play with
files.. So all works with emulator buffer will begin from file.
Or am i wrong ?

Alexey Pialkin