[PATCH v2 2/2] powerpc/mm: Change the swap encoding in pte.

Scott Wood scottwood at freescale.com
Thu Jun 18 07:14:22 AEST 2015


On Wed, 2015-06-17 at 19:45 +1000, Michael Ellerman wrote:
> On Wed, 2015-06-17 at 08:21 +0530, Aneesh Kumar K.V wrote:
> > "Aneesh Kumar K.V" <aneesh.kumar at linux.vnet.ibm.com> writes:
> > 
> > 
> > Hi Scott,
> > 
> > > Current swap encoding in pte can't support large pfns
> > > above 4TB. Change the swap encoding such that we put
> > > the swap type in the PTE bits. Also add build checks
> > > to make sure we don't overlap with HPTEFLAGS.
> > > 
> > 
> > Can you please review this w.r.t 64bit booke ? 

It looks OK.

I'm curious why _PAGE_BIT_SWAP_TYPE is 2 -- it seems like it could be 
any value >= 1 that isn't large enough to cause a conflict. Does 
something get stored in that second bit?

> I booted it on our p5020ds FWIW.

Actively using swap?

-Scott




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