linux-kernel - Re: why choose 896MB to the start point of ZONE

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Message-ID: <4BBC2086.6090708@zytor.com>
Date:	Tue, 06 Apr 2010 23:04:54 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Venkatram Tummala <venkatram867@...il.com>
CC:	Chetan Nanda <chetannanda@...il.com>,
	Joel Fernandes <agnel.joel@...il.com>,
	Frank Hu <frank.hu.2001@...il.com>,
	hayfeng Lee <teklife.kernel@...il.com>,
	linux-kernel@...r.kernel.org, linux-kernel@...kernel.org,
	kernelnewbies@...linux.org
Subject: Re: why choose 896MB to the start point of ZONE_HIGHMEM

On 04/06/2010 10:57 PM, Venkatram Tummala wrote:
> Just a note Chetan.
> 
> We can't exactly say that we require "page table settings" to map that
> 896 MB of physical ram. It is an identity mapped segment (1-1 mapping).
> So, we dont require the "page tables".  Virtual address will be equal to
> Physical Address + Page Offset. It is just an addition of offset
> 

No, we still need page tables for the identity-mapped segment.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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