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Date:      Sun, 22 Apr 2007 11:32:56 +0200
From:      Erik Trulsson <ertr1013@student.uu.se>
To:        Artem Kuchin <matrix@itlegion.ru>
Cc:        freebsd-stable@freebsd.org
Subject:   Re: PAE does not give any ram increase, why?
Message-ID:  <20070422093256.GA43926@owl.midgard.homeip.net>
In-Reply-To: <001e01c784be$9b969c20$0c00a8c0@Artem>
References:  <462A78F5.3090904@samsco.org> <001e01c784be$9b969c20$0c00a8c0@Artem>

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On Sun, Apr 22, 2007 at 01:14:17PM +0400, Artem Kuchin wrote:
> 
> >>the number do not change with or without PAE
> >>
> >>Maybe i look in the wrong place?
> >>
> >
> >I'm not going to waste my time explaining for the hundredth time how
> >the x86 memory layout works.  If you want to recover the missing
> >256MB, go look in your BIOS for an option about memory hole remapping.
> 
> No need, i know this stuff. Problem is that asus p5p800-vm bios does not
> have such option (no memory remapping support in chipset)
> , so, and simply assumed that  in PAE mode this simply
> does not matter and it will give me whole 4GB. Isn't it so?
> Is it true for 64bit mode (amd64)?

It is not so for either of PAE or 64-bit mode.
What those give you is the ability to address memory above
the 4GB limit.

In order to access memory below the 4GB boundary that is shadowed
by various I/O-devices, the RAM will have to be remapped to somewehere else.


So if you could remap the memory then PAE or 64-bit mode would give you the
ability to access it.  If you can't remap it you can't get hold of it.




-- 
<Insert your favourite quote here.>
Erik Trulsson
ertr1013@student.uu.se



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