On Thu, Feb 28, 2019 at 12:04:08PM +0000, Steven Price wrote:
On 28/02/2019 11:53, Geert Uytterhoeven wrote:
Hi Mike,
On Thu, Feb 28, 2019 at 12:37 PM Mike Rapoport <rppt@xxxxxxxxxxxxx> wrote:
On Wed, Feb 27, 2019 at 08:27:40PM +0100, Geert Uytterhoeven wrote:
On Wed, Feb 27, 2019 at 6:07 PM Steven Price <steven.price@xxxxxxx> wrote:
walk_page_range() is going to be allowed to walk page tables other than
those of user space. For this it needs to know when it has reached a
'leaf' entry in the page tables. This information is provided by the
p?d_large() functions/macros.
For m68k, we don't support large pages, so add stubs returning 0
CC: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
CC: linux-m68k@xxxxxxxxxxxxxxxxxxxx
Signed-off-by: Steven Price <steven.price@xxxxxxx>
Thanks for your patch!
arch/m68k/include/asm/mcf_pgtable.h | 2 ++
arch/m68k/include/asm/motorola_pgtable.h | 2 ++
arch/m68k/include/asm/pgtable_no.h | 1 +
arch/m68k/include/asm/sun3_pgtable.h | 2 ++
4 files changed, 7 insertions(+)
Maybe I'm missing something, but why the stubs have to be defined in
arch/*/include/asm/pgtable.h rather than in include/asm-generic/pgtable.h?
That would even make more sense, given most architectures don't
support huge pages.
Where the architecture has folded a level stubs are provided by the
asm-generic layer, see this later patch:
https://lore.kernel.org/lkml/20190227170608.27963-25-steven.price@xxxxxxx/
However just because an architecture port doesn't (currently) support
huge pages doesn't mean that the architecture itself can't have large[1]
mappings at higher levels of the page table. For instance an
architecture might use large pages for the linear map but not support
huge page mappings for user space.
Well, I doubt m68k can support large mappings at higher levels at all.
This, IMHO, applies to many other architectures and spreading p?d_large all
over those architecture seems wrong to me...
My previous posting of this series attempted to define generic versions
of p?d_large(), but it was pointed out to me that this was fragile and
having a way of knowing whether the page table was a 'leaf' is actually
useful, so I've attempted to implement for all architectures. See the
discussion here:
https://lore.kernel.org/lkml/20190221113502.54153-1-steven.price@xxxxxxx/T/#mf0bd0155f185a19681b48a288be212ed1596e85d
I'll reply on that thread, somehow I missed it then.
Steve
--
Sincerely yours,
Mike.
