Re: [patch 2/3] CONFIG_HIGHPTE vs. sub-page page tables.

Geert Uytterhoeven
2008-01-02T21:24:54Z

On Wed, 2 Jan 2008, Christoph Hellwig wrote:
> On Mon, Nov 12, 2007 at 03:30:11PM +0100, schwidefsky@de.ibm.com wrote:
> > From: Martin Schwidefsky <schwidefsky@de.ibm.com>
> > Solution: The only solution I found to this dilemma is a new typedef:
> > a pgtable_t. For s390 pgtable_t will be a (pte *) - to be introduced
> > with a later patch. For everybody else it will be a (struct page *).
> > The additional problem with the initialization of the ptl lock and the
> > NR_PAGETABLE accounting is solved with a constructor pgtable_page_ctor
> > and a destructor pgtable_page_dtor. The page table allocation and free
> > functions need to call these two whenever a page table page is allocated
> > or freed. pmd_populate will get a pgtable_t instead of a struct page
> > pointer. To get the pgtable_t back from a pmd entry that has been
> > installed with pmd_populate a new function pmd_pgtable is added. It
> > replaces the pmd_page call in free_pte_range and apply_to_pte_range.
>
> Can we please just nuke CONFIG_HIGHPTE? There's only been a small
> amount of 32bit machines with so much memory that they'd need it
> and they can happily stay on the currently supported enterprise
> distro releases instead of dragging this cruft around forever.

And all MMU-equipped FR-V machines with more than 256 MiB of RAM,
according to arch/frv/Kconfig?

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds