On Fri, 19 Feb 2010 15:10:12 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
> 1. re-implement pfn_valid() which returns correct value.
> maybe not difficult. but please take care of defining CONFIG_HOLES_IN_....
> etc.
>
> 2. use DISCONTIGMEM and treat each bank and NUMA node.
> There will be no waste for memmap. But other complication of CONFIG_NUMA.
>
> 3. use SPARSEMEM.
> You have even 2 choisce here.
> a - Set your MAX_ORDER and SECTION_SIZE to be proper value.
> b - waste some amount of memory for memmap on the edge of section.
> (and don't free memmap for the edge.)
>
I read ARM's code briefly. In 2.6.32, ...I think (1) is implemented. As
==
#ifndef CONFIG_SPARSEMEM
int pfn_valid(unsigned long pfn)
{
struct meminfo *mi = &meminfo;
unsigned int left = 0, right = mi->nr_banks;
do {
unsigned int mid = (right + left) / 2;
struct membank *bank = &mi->bank[mid];
if (pfn < bank_pfn_start(bank))
right = mid;
else if (pfn >= bank_pfn_end(bank))
left = mid + 1;
else
return 1;
} while (left < right);
return 0;
}
EXPORT_SYMBOL(pfn_valid);
==
So, what you should do is upgrade to 2.6.32 or backport this one.
See this.
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=b7cfda9fc3d7aa60cffab5367f2a72a4a70060cd
Thanks,
-Kame
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