Subject: Re: [PATCH 28/31] memblock: Export MEMBLOCK_ERROR again
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: David Miller <davem@davemloft.net>
Cc: hpa@zytor.com, yinghai@kernel.org, mingo@elte.hu, tglx@linutronix.de,
        akpm@linux-foundation.org, torvalds@linux-foundation.org,
        hannes@cmpxchg.org, linux-kernel@vger.kernel.org,
        linux-arch@vger.kernel.org
In-Reply-To: <20100727.230120.43037767.davem@davemloft.net>
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	 <20100727.230120.43037767.davem@davemloft.net>
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Date: Wed, 28 Jul 2010 19:25:31 +1000
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On Tue, 2010-07-27 at 23:01 -0700, David Miller wrote:
> > 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.
> 
> 0 is very much possible on sparc64 

Yup, we need to fix that.

For now I made MEMBLOCK_ERROR 0 and added a blurb to prevent allocating
the first page since it would cause other problems with the current code
(0 is after all the normal error result from membloc_alloc(), ie, our
API wasn't quite consistent there).

So I don't think I'm introducing a regression here, on the contrary. But
if we are going to allow lmb_alloc() to return 0, we need to fix all
callers first and then we can look into turning MEMBLOCK_ERROR back to
~0

Cheers,
Ben.


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