From owner-freebsd-hackers  Thu Aug  2 11:49:23 2001
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Date: Thu, 2 Aug 2001 13:55:10 -0700 (PDT)
From: Julian Elischer <julian@elischer.org>
To: Kenneth Wayne Culver <culverk@wam.umd.edu>
Cc: John Baldwin <jhb@FreeBSD.org>, freebsd-hackers@FreeBSD.org,
	craig <craiglei@pasia.com.cn>,
	Terry Lambert <tlambert2@mindspring.com>,
	Rik van Riel <riel@conectiva.com.br>
Subject: Re: How to visit physical memory above 4G?
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No
The space is linear in physical space and if you have PCI/64
capable devices they can access it all too.

(In fact 64 bit addresses have been supported even in 32 bit wide PCI 
since day 1).

On Thu, 2 Aug 2001, Kenneth Wayne Culver wrote:

> BUT, don't the motherboards also have to support this? And isn't it only
> supported through some wierd segmentation thing? 
> 
> KEn
> 
> On Thu, 2 Aug 2001, John Baldwin wrote:
> 
> > 
> > On 02-Aug-01 Kenneth Wayne Culver wrote:
> > > Also, the PIII CAN'T natively support more than 4GB of ram. If a
> > > particular PIII motherboard supports this, then it's using some kind of
> > > wierd chipset that allows this to happen. 4GB is the limit with a 32 bit
> > > chip I believe; and the PIII is a 32-bit chip.
> > > 
> > > Ken
> > 
> > Go look at some Intel docs.  P6 chips since the Pentium Pro (yes, before
> > Pentium II) have supported PAE which allows for a 36-bit physical address.
> > 
> > -- 
> > 
> > John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/
> > PGP Key: http://www.baldwin.cx/~john/pgpkey.asc
> > "Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/
> > 
> 
> 
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