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Subject: Re: [PATCH v2 2/2] powerpc/mm: Change the swap encoding in pte.
From: Scott Wood <scottwood@freescale.com>
To: Michael Ellerman <mpe@ellerman.id.au>
CC: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>,
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Date: Wed, 17 Jun 2015 16:14:22 -0500
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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@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