Messages in this thread | | | Date | Fri, 1 Aug 2008 03:11:37 +0200 | From | Nick Piggin <> | Subject | Re: [PATCH] powerpc/mm: Implement _PAGE_SPECIAL & pte_special() for 32-bit |
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On Thu, Jul 31, 2008 at 01:48:31PM -0500, Kumar Gala wrote: > Implement _PAGE_SPECIAL and pte_special() for 32-bit powerpc. This bit will > be used by the fast get_user_pages() to differenciate PTEs that correspond > to a valid struct page from special mappings that don't such as IO mappings > obtained via io_remap_pfn_ranges(). > > We currently only implement this on sub-arch that support SMP or will so > in the future (6xx, 44x, FSL-BookE) and not (8xx, 40x). > > Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Cool
> --- > Nick, do you forsee using _PAGE_SPECIAL for other applications that would > be of interested to non-SMP hw? > > We can look at adding it into 8xx and 40x, but was being lazy as I assume > there is no point.
I don't forsee it being used for anything else, but it is possible I guess.
We currently will also use it in the VM (vm_normal_page), turning that function into a much more compact and simple version. It doesn't do a great deal for performance, but you _may_ want to consider using it just so the entire powerpc architecture takes this same path.
Not a big deal though.
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