Re: [PATCH 28/31] memblock: Export MEMBLOCK_ERROR again

From: David Miller
Date: Wed Jul 28 2010 - 02:01:20 EST


From: "H. Peter Anvin" <hpa@xxxxxxxxx>
Date: Tue, 27 Jul 2010 22:53:21 -0700

> 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.

0 is very much possible on sparc64
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