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SubjectRe: [PATCH] mm: bootmem: use phys_addr_t for physical addresses
Hi Tejun,

On 9/12/2012 4:39 PM, Tejun Heo wrote:
> Hello,
>
> On Wed, Sep 12, 2012 at 12:06:48PM -0400, Cyril Chemparathy wrote:
>> static void * __init alloc_bootmem_core(unsigned long size,
>> unsigned long align,
>> - unsigned long goal,
>> - unsigned long limit)
>> + phys_addr_t goal,
>> + phys_addr_t limit)
>
> So, a function which takes phys_addr_t for goal and limit but returns
> void * doesn't make much sense unless the function creates directly
> addressable mapping somewhere.
>

On the 32-bit PAE platform in question, physical memory is located
outside the 4GB range. Therefore phys_to_virt takes a 64-bit physical
address and returns a 32-bit kernel mapped lowmem pointer.

> The right thing to do would be converting to nobootmem (ie. memblock)
> and use the memblock interface. Have no idea at all whether that
> would be a realistic short-term solution for arm.
>

I must plead ignorance and let wiser souls chime in on ARM architecture
plans w.r.t. nobootmem. As far as I can tell, the only thing that
blocks us from using nobootmem at present is the need for sparsemem on
some platforms.

--
Thanks
- Cyril


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