From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Kumar Gala <galak@kernel.crashing.org>
Cc: linux-ppc list <linuxppc-dev@ozlabs.org>, David Gibson <dwg@au1.ibm.com>
Subject: Re: using different format for hugetlbfs
Date: Fri, 04 Dec 2009 19:58:56 +1100 [thread overview]
Message-ID: <1259917136.2076.1264.camel@pasglop> (raw)
In-Reply-To: <230774E3-2D94-44DA-85AC-151485996789@kernel.crashing.org>
On Fri, 2009-12-04 at 01:18 -0600, Kumar Gala wrote:
> Ben, David,
>
> If we want to support true 4G/4G split on ppc32 using the MSB of the
> address to determine of the pgd_t is for hugetlbfs isn't going to
> work. Since every pointer in the pgd_t -> pud_t -> pmd_t is point to
> at least a 4K page I would think the low order 12-bits should always
> be 0.
On 32 bit maybe. On 64, the pg/u/md's can be smaller. I don't really
want to have a different encoding for both types though.
> Could we use something like:
>
> addr[0:51] || shift [52:59] || flags [60:63]
>
> with the LSB flag being 'normal pointer' vs 'hugetlbfs mangled
> pointer'. Seems like shift will at most be 64 so 8-bits should cover
> it.
Cheers,
Ben.
next prev parent reply other threads:[~2009-12-04 8:59 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-04 7:18 using different format for hugetlbfs Kumar Gala
2009-12-04 8:58 ` Benjamin Herrenschmidt [this message]
2009-12-04 14:09 ` Kumar Gala
2009-12-04 21:25 ` Benjamin Herrenschmidt
2009-12-06 3:05 ` Kumar Gala
2009-12-07 1:04 ` Benjamin Herrenschmidt
2009-12-08 2:28 ` David Gibson
2009-12-08 15:44 ` Kumar Gala
2009-12-09 2:00 ` David Gibson
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=1259917136.2076.1264.camel@pasglop \
--to=benh@kernel.crashing.org \
--cc=dwg@au1.ibm.com \
--cc=galak@kernel.crashing.org \
--cc=linuxppc-dev@ozlabs.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.