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Date: Wed, 30 Mar 2005 12:25:06 -0700
From: Scott Long <scottl@samsco.org>
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To: Rajesh Ghanekar <ghanekar_rajesh@hotmail.com>
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cc: freebsd-hackers@freebsd.org
Subject: Re: physical address to virtual address conversion
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Rajesh Ghanekar wrote:
> Hi,
> 
>   I am trying to convert a physical memory location (address 0x000F0000)
> to virtual memory address in kernel module with pmap_map() / pmap_enter().
> Whenever i call these two functions, system hangs. Is this a proper
> way for conversion?
> 
>  The same physical address can be accessed from the userspace by opening
> /dev/mem. The code which does the memory mapping to /dev/mem at kernel
> level is in ./sys/i386/i386/mem.c as mmrw() which also uses pmap_enter().
> 
> kernel = FreeBSD 4.10
> 
> - Rajesh
> 

pmap_mapdev() is probably what you want.  However, what exactly are you
trying to do?  Why do you need access to a specific physical location?

Scott