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

[Yinghai Lu <yinghai@kernel.org>]

On 07/27/2010 11:01 PM, David Miller wrote:
> From: "H. Peter Anvin" <hpa@zytor.com>
> 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

So still keep MEMBLOCK_ERROR to (~(phys_addr_t)0) ?

We can change some variable from unsigned long to phys_addr_t that will be
 assigned by memblock_find_base().

that could avoid casting too.

Thanks

Yinghai