Date:	Fri, 23 Jun 2000 08:24:15 +0300 (IDT)
From:	Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
X-Sender:	eliz AT is
To:	djgpp AT delorie DOT com
Subject:	Re: DJGPP and Mapping physical memory from a PCI device
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On Thu, 22 Jun 2000, Ali wrote:

> I am wondering what is the use of the Selector here.

The DPMI server creates the selector to allow you access to the memory 
to which you mapped the device.

> If I want
> to access the mapped physical memory, couldn't I just use
> 
> mapMemory(PciBase,sizeof(REGISTERS),&Selector,&Adapter);
> /* and then just */
> Adapter=0; /*would set the first memory location */

No, you can't do this.  You need to use _farpeek* and _farpoke* functions 
to access the device, because it is not part the usual data DJGPP segment 
(whose selector is loaded into the DS register).  That's why the DPMI 
server returns a selector to you.

I believe the FAQ explains this.

> BTW, when I try this I get a segmentation error.

As expected.

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