CONFIG_FORCE_MAX_ZONEORDER settable for all ARM architectures

[Eric Miao]

On Fri, Nov 5, 2010 at 9:41 PM, Daniel Mack <zonque at gmail.com> wrote:
> Hi,
>
> on a PXA3xx based platform, we want to allocate 8MByte of physically
> contiguous memory for the framebuffer device.
>
> However, alloc_pages() fails because MAX_ORDER is hard-coded to 11 for
> this architecture.
>
> Is there any reason why CONFIG_FORCE_MAX_ZONEORDER is constrained to
> ARCH_SHMOBILE in arch/arm/Kconfig? Would a patch to remove this
> limitation be accepted? Or is there any better way to allocate that
> amount and type of memory?
>

There is actually an on-going discussion of memory region allocator,
basically can
be used to solve the allocation of large chunk of physically
contiguous memory by
memory migration at run-time. Some of the ideas were mentioned in a previous
patch of CMA (contiguous memory allocator)? Though I didn't look too much into
that thread.

However, I'm not really sure about how the size of the memory region is chosen
and if the MAX_ORDER issue can be solved as well. So I guess before that
happens in mainline, would be acceptable to adjust MAX_ZONEORDER in a
hackish way.

> Thanks,
> Daniel
>
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