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To: "Daniel M. Eischen" <deischen@iworks.InterWorks.org>
cc: krygier@kph.uni-mainz.de, questions@FreeBSD.ORG
Subject: Re: special memory device 
In-reply-to: Your message of "Tue, 15 Apr 1997 04:40:36 CDT."
             <199704150940.EAA15971@iworks.InterWorks.org> 
From: David Greenman <dg@root.com>
Reply-To: dg@root.com
Date: Tue, 15 Apr 1997 02:49:42 -0700
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>> >The problem I have, is that if I create a driver for this chip,
>> >how do I ask the PCI support code for 4 consecutive 16MB regions
>> >of the PCI bus?  From what I can tell, the PCI code will only let
>> >you map an address space as it is defined in the PCI configuration
>> >space registers.  For the Tundra Universe chip, the registers
>> >that configure the special PCI slave image are not in the PCI         
>> >configuration space.  
>>
>>    The obvious question this raises is: How do you do address space conflict
>> resolution if you ignore the assignments made by the PCI BIOS?
>
>Right.  There should probably be a resource list to manage these
>addresses.  Drivers would have to call a set of common functions
>in order to allocate PCI address space.  The Tundra Universe chip
>shares the PCI bus with a DEC 21240 and an Adaptec 7880, so I can't
>allocate an address range without ensuring it doesn't conflict.

   In order to do this you'd have to go poking around in the PCI registers of
all of the devices that were found and create the map. This doesn't sound
like much fun.

-DG

David Greenman
Core-team/Principal Architect, The FreeBSD Project