Re: [PATCH] mm: bootmem: use phys_addr_t for physical addresses

[Cyril Chemparathy]

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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