linux-kernel - Re: [PATCH 4/8] x86 boot: allow overlapping ebda and efi memmap memory ranges

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Date:	Mon, 16 Jun 2008 11:18:12 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Paul Jackson <pj@....com>
CC:	Yinghai Lu <yhlu.kernel@...il.com>, ying.huang@...el.com,
	mingo@...e.hu, tglx@...utronix.de, steiner@....com, travis@....com,
	linux-kernel@...r.kernel.org, andi@...stfloor.org,
	akpm@...ux-foundation.org
Subject: Re: [PATCH 4/8] x86 boot: allow overlapping ebda and efi memmap memory
 ranges

Paul Jackson wrote:
> Yinghai wrote:
>> like to see to make reserve_ebda_region() more smart like the old
>> way when andi introduced ebda_size... instead of reserve 0x9000 to
>> 0x100000 all the way.
> 
> Looking back at some older kernels, that code seems to have setup an
> ebda region only if there was a non-zero real mode pointer at 0x40E.
> 
> This is rather different than always setting up such a region.
> 

Well, sort of.  Only some very old systems will not have had one.

0x40E contains the pointer to the EBDA; this basically tests for the 
existence of an EBDA at all.

	-hpa

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