Re: [SPARSEMEM] confusing uses of SPARSEM_EXTREME (try #2)

["Franck Bui-Huu" <vagabon.xyz@gmail.com>]

Hi Andy

2006/6/12, Andy Whitcroft <apw@shadowen.org>:
> In my mind the positive option is selecting for code supporting EXTREME
> so it seems to make sense to use that option.

well I find it confusing because in my mind, something like this seems
more logical.

#ifndef CONFIG_SPARSEMEM_STATIC
static struct mem_section *sparse_index_alloc(int nid)
{
       return alloc_bootmem_node(...);
}
#else
static struct mem_section *sparse_index_alloc(int nid)
{
       /* nothing to do here, since it has been statically allocated */
       return 0;
}
#endif

This code only deals with section allocation and the way it's achieved
depends only if the section array has been statically allocated.
There's nothing related on the two-level lookups here, is there ?

And use SPARSEMEM_EXTREME when it deals only with two-level lookups:

#ifdef CONFIG_SPARSEMEM_EXTREME
#define SECTIONS_PER_ROOT       (PAGE_SIZE / sizeof (struct mem_section))
#else
#define SECTIONS_PER_ROOT       1
#endif

> Perhaps the confusion
> comes from a lack of comments there to say that the else case is STATIC.

nope but maybe a comment to explain why i386 use SPARSEMEM_STATIC
option could be useful. At least for someone who is not working on
this arch...

Thanks
--
              Franck
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