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

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Message-ID: <48569D62.9050107@zytor.com>
Date:	Mon, 16 Jun 2008 10:05:38 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Paul Jackson <pj@....com>
CC:	ying.huang@...el.com, mingo@...e.hu, tglx@...utronix.de,
	yhlu.kernel@...il.com, 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:
> hpa wrote:
>> Realistically, we need the infrastructure to be able to make paranoia 
>> reservations, and you need to be able to deal with later finding they 
>> are actually in use.
> 
> While the tone of your reply sounds like something I would naturally
> agree with, I can't actually figure out what you mean in this case ;).
> 
> In particular, Peter, would you agree/disagree/other with the direction
> that Huang and I agreed to last night:
> 
>> Would you recommend doing this with code in arch/x86/kernel/head.c,
>> that did not invoke reserve_ebda_region() if efi_enabled was set?

I disagree with it, I do not consider it safe.  I think you have to 
consider the difference between a "safety reservation" and a "actual 
reservation", with the latter being allowed to overlap the former.

	-hpa
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