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Mail Archives: djgpp/1999/04/13/11:08:04

Message-Id: <m10X4mC-000S8gC@inti.gov.ar>
Comments: Authenticated sender is <salvador AT natacha DOT inti DOT gov DOT ar>
From: "Salvador Eduardo Tropea (SET)" <salvador AT inti DOT gov DOT ar>
Organization: INTI
To: yjtseng <yjtseng AT micron DOT com>, djgpp AT delorie DOT com
Date: Tue, 13 Apr 1999 12:11:25 +0000
MIME-Version: 1.0
Subject: Re: cwsdpr0.exe
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yjtseng <yjtseng AT micron DOT com> asked:

> I wrote inline assembly to access CR0. There was general protection fault at
> run time. After suggestions given by Salvador Eduardo Tropea and Nate
> Eldredge, I tried cwsdpr0.exe and it worked. I was able to access CR0. 
> 
> Questions:
> 
> First:
> Acording to cwsdpmi.doc, cwsdpr0.exe runs with virtual memory disabled. But,
> the value of CR0 that I read is 0x80000011 which means the paging mechanism
> is on. Any idea anybody?

Paging mechanism isn't virtual memory. If I remmember OK the EMM386 driver 
uses it in DOS. It allows to remap the memory using pages, of course that's 
needed for virtula memory but not the reverse.
There are a DPMI call to know if VM is available.
 
> Second:
> How can I pick cwsdpr0.exe as the DPMI host at compilation instead of using 
> 	stubedit  my.exe dpmi=cwsdpr0.exe
> after the executable is generated?

I think there is no easier way, you could tell the linker to use an external 
stub file, but I think the stubedit step is easier.

SET

P.S. As you can see that's a priviledged instruction ;-) 
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Salvador Eduardo Tropea (SET). (Electronics Engineer)
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