linux-kernel - Re: [PATCH 28/31] memblock: Export MEMBLOCK

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Message-ID: <4C4FC5D1.3070708@zytor.com>
Date:	Tue, 27 Jul 2010 22:53:21 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
CC:	Yinghai Lu <yinghai@...nel.org>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Miller <davem@...emloft.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Johannes Weiner <hannes@...xchg.org>,
	linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org
Subject: Re: [PATCH 28/31] memblock: Export MEMBLOCK_ERROR again

On 07/27/2010 10:19 PM, Benjamin Herrenschmidt wrote:
> 
> Screw it, I don't like it but I'll just split your patch in two for now
> and keep 0. It's a bit fishy but memblock does mostly top-down
> allocations and so shouldn't hit 0, and in practice the region at 0 is,
> I beleive, reserved, but we need to be extra careful and might need to
> revisit that a bit.
> 
> That's an area where I don't completely agree with Linus, ie, 0 is a
> perfectly valid physical address for memblock to return :-)
> 

On x86, physical address 0 contains the real-mode IVT and will thus be
reserved, at least for the forseeable future.  Other architectures may
very well have non-special RAM there.

	-hpa

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

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