From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: Scott Wood <scottwood@freescale.com>,
Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org, benh@kernel.crashing.org,
paulus@samba.org
Subject: Re: [PATCH v2 2/2] powerpc/mm: Change the swap encoding in pte.
Date: Thu, 18 Jun 2015 10:50:46 +0530 [thread overview]
Message-ID: <871th9h9sh.fsf@linux.vnet.ibm.com> (raw)
In-Reply-To: <1434575662.2353.107.camel@freescale.com>
Scott Wood <scottwood@freescale.com> writes:
> 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?
Yes, we should be able to use >= 1. But then our _PAGE_USER is also used
to indicate prot_none. It should really be _PAGE_PRESENT set and
_PAGE_USER cleared. So for the swap case we should be ok to use
_PAGE_USER. But i didn't want to audit all the asm code. So i decided to
leave _PAGE_USER as it is.
>
>> I booted it on our p5020ds FWIW.
>
> Actively using swap?
>
-aneesh
prev parent reply other threads:[~2015-06-18 5:20 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-17 2:43 [PATCH v2 1/2] powerpc/mm: PTE_RPN_MAX is not used, remove the same Aneesh Kumar K.V
2015-06-17 2:43 ` [PATCH v2 2/2] powerpc/mm: Change the swap encoding in pte Aneesh Kumar K.V
2015-06-17 2:51 ` Aneesh Kumar K.V
2015-06-17 9:45 ` Michael Ellerman
2015-06-17 21:14 ` Scott Wood
2015-06-18 4:16 ` Michael Ellerman
2015-06-18 5:20 ` Aneesh Kumar K.V [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=871th9h9sh.fsf@linux.vnet.ibm.com \
--to=aneesh.kumar@linux.vnet.ibm.com \
--cc=benh@kernel.crashing.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mpe@ellerman.id.au \
--cc=paulus@samba.org \
--cc=scottwood@freescale.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).