SW TLB MMU rework and SMP issues (pte read/write)

[Kumar Gala]

On Jul 16, 2008, at 4:41 PM, Benjamin Herrenschmidt wrote:

> On Wed, 2008-07-16 at 15:57 -0500, Kumar Gala wrote:
>> This makes sense.  I think we need to order the stores in set_pte_at
>> regardless of CONFIG_SMP.
>
> Nah, that shouldn't be necessary.

Yeah I finally came to that realization.

>> Also, I think we should change pte_clear to
>> use pte_update() so we only clear the low-order flag bits.  Patch  
>> will
>> be sent shortly for review.
>
> Well... at one point at least we did rely on a PTE page with all PTEs
> cleared to be blank. It don't know if that's still the case, I need to
> look.

Doesn't look like we do anything special, we just call free_pages or  
__free_pages in arch/powerpc/mm/pgtable_32.c.

- k