linux-kernel - Re: kexec load failure introduced by "x86, memblock: Replace e820_/_early string with memblock

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Date:	Mon, 27 Sep 2010 20:46:42 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Vivek Goyal <vgoyal@...hat.com>
CC:	Yinghai Lu <yinghai@...nel.org>, Ingo Molnar <mingo@...e.hu>,
	kexec <kexec@...ts.infradead.org>, caiqian@...hat.com,
	linux-kernel@...r.kernel.org
Subject: Re: kexec load failure introduced by "x86, memblock: Replace e820_/_early
 string with memblock_"

On 09/27/2010 05:53 PM, Vivek Goyal wrote:
> 
> Actually, hardcoding the upper limit to 4G is probably not the best idea.
> Kexec loads the the relocatable binary (purgatory) and I remember that
> one of the generated relocation type was signed 32 bit and allowed max value
> to be 2G only. So IIRC, purgatory code always needed to be loaded below 2G.
> 
> I liked HPA's other idea better of introducing memblock_find_in_range_lowest() 
> so that we search bottom up and not rely on a specific upper limit.
> 

No, it's just another crappy hack which is broken in the same way.  It's
better than open-coding, but it's still a hack.

The Right Thing[TM] to do is for kexec to communicate the topmost
address it wants to this code, so it has both the upper and the lower
boundaries available to it instead of just one.

	-hpa

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

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