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Date: Tue, 03 Jul 2001 09:56:24 -0500
From: Eli Carter <eli.carter@inet.com>
Organization: Inet Technologies, Inc.
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To: Guillaume Lancelin <guillaumelancelin@yahoo.es>
CC: linux-kernel@vger.kernel.org
Subject: Re: Memory access
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Guillaume Lancelin wrote:
> 
> Writing a device driver for a IO card, I have the following message from
> the kernel:
> Unable to handle kernel paging request at virtual address 000d0804.
> [then it gives the register values]
> Segmentation fault."
> 
> This address (0xd0804) is the location of a "mailbox" reserved by the IO
> card, and from which commands are passed to the card.
> 
> My question: is the kernel using or protecting this area of the memory,
> and is there a way to deprotect it??? (how dangerous!)

Sounds like you may want to look into ioremap() and maybe buy Linux
Device Drivers by Rubini (O'Reilly).

Have fun!

Eli 
-----------------------.   No wonder we didn't get this right first time
Eli Carter             |      through. It's not really all that horribly 
eli.carter(at)inet.com `- complicated, but the _details_ kill you. Linus
-
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