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To: davidm@hpl.hp.com
cc: Andi Kleen <ak@suse.de>,
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       Riley Williams <Riley@williams.name>
Reply-To: Gerrit Huizenga <gh@us.ibm.com>
From: Gerrit Huizenga <gh@us.ibm.com>
Subject: Re: [Lse-tech] Re: maximum possible memory limit .. 
In-reply-to: Your message of Mon, 28 Apr 2003 10:53:53 PDT.
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Date: Mon, 28 Apr 2003 11:31:04 -0700
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On Mon, 28 Apr 2003 10:53:53 PDT, David Mosberger wrote:
> >>>>> On Mon, 28 Apr 2003 19:13:53 +0200, Andi Kleen <ak@suse.de> said:
> 
>   >> Cool. Sorry to be pestering about the 64-bit limits, but can we
>   >> really use 2^64 bytes of memory on ia64/ppc64/x86-64 etc.?
>   >> (AFAIK, 64-bit arches don't suffer from a small ZONE_LOWMEM.)
> 
>   Andi> No. The hardware have far smaller physical limits.
> 
>   Andi> Current AMD64 CPUs are limited to 40bit physical, 48bit virtal
>   Andi> (the virtual limit per process in the current Linux kernel is
>   Andi> 39bits)
> 
>   Andi> Itanium 2 afaik support a bit more 50bits (51 or 52, I forgot)
>   Andi> physical, probably more virtual.
> 
> Itanium 2 supports all 64 virtual address bits and 50 physical bits
> (in what way is "1024 times more" "a bit more"? ;-).
> 
> 	--david

0x400 is just one more bit, albeit slid around a byte or two.  ;)

gerrit