From: "Aneesh Kumar K.V" <aneesh.kumar@linux•vnet.ibm.com>
To: Paul Mackerras <paulus@samba•org>
Cc: linuxppc-dev@lists•ozlabs.org
Subject: Re: [PATCH -V4 11/12] arch/powerpc: properly offset the context bits for 1T segemnts
Date: Mon, 30 Jul 2012 11:06:27 +0530 [thread overview]
Message-ID: <873949n738.fsf@skywalker.in.ibm.com> (raw)
In-Reply-To: <20120730005803.GB21364@bloggs.ozlabs.ibm.com>
Paul Mackerras <paulus@samba•org> writes:
> On Wed, Jul 25, 2012 at 06:28:04PM +0530, Aneesh Kumar K.V wrote:
>> From: "Aneesh Kumar K.V" <aneesh.kumar@linux•vnet.ibm.com>
>>
>> We should do rldimi r10,r9,USER_ESID_BITS,0 only after populating
>> r10 with ESID bits.
>
> This needs a lot more explanation as to what the problem is that this
> patch aims to fix. Is it a problem today without your other patches,
> or is it introduced by previous patches?
>
> In any case I think there is an error in the patch, see below...
>
>> 0: /* user address: proto-VSID = context << 15 | ESID. First check
>> @@ -155,13 +157,16 @@ END_MMU_FTR_SECTION_IFCLR(MMU_FTR_1T_SEGMENT)
>> ld r9,PACACONTEXTID(r13)
>> BEGIN_FTR_SECTION
>> cmpldi r10,0x1000
>> + bge 9f
>> END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEGMENT)
>> rldimi r10,r9,USER_ESID_BITS,0
>> + b slb_finish_load
>> BEGIN_FTR_SECTION
>> - bge slb_finish_load_1T
>> +9:
>> + srdi r10,r10,40-28 /* get 1T ESID */
>> + rldimi r10,r9,USER_ESID_BITS,0
>
> Shouldn't this one be USER_ESID_BITS_1T? And in that case, since
> USER_ESID_BITS == USER_ESID_BITS_1T + 12, I think the patch would
> then introduce no change in behaviour (other than being slightly
> slower than the current code). Or am I missing something? -- in
> that case we really need a longer and better explanation with the
> patch.
Ok I missed that we used USER_ESID_BITS there. This patch can be
dropped. I looked at the 1T code, and assumed that we were wrongly
shifting the context bits there.
-aneesh
next prev parent reply other threads:[~2012-07-30 5:37 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-25 12:57 [PATCH -V4 0/12] arch/powerpc: Add 64TB support to ppc64 Aneesh Kumar K.V
2012-07-25 12:57 ` [PATCH -V4 01/12] arch/powerpc: Use hpt_va to compute virtual address Aneesh Kumar K.V
2012-07-25 12:57 ` [PATCH -V4 02/12] arch/powerpc: Simplify hpte_decode Aneesh Kumar K.V
2012-07-25 12:57 ` [PATCH -V4 03/12] arch/powerpc: Convert virtual address to vpn Aneesh Kumar K.V
2012-07-25 12:57 ` [PATCH -V4 04/12] arch/powerpc: Rename va " Aneesh Kumar K.V
2012-07-25 12:57 ` [PATCH -V4 05/12] arch/powerpc: Make KERN_VIRT_SIZE not dependend on PGTABLE_RANGE Aneesh Kumar K.V
2012-07-25 12:57 ` [PATCH -V4 06/12] arch/powerpc: Increase the slice range to 64TB Aneesh Kumar K.V
2012-07-25 12:58 ` [PATCH -V4 07/12] arch/powerpc: Make some of the PGTABLE_RANGE dependency explicit Aneesh Kumar K.V
2012-07-25 12:58 ` [PATCH -V4 08/12] arch/powerpc: Use the rquired number of VSID bits in slbmte Aneesh Kumar K.V
2012-07-25 12:58 ` [PATCH -V4 09/12] arch/powerpc: Use 32bit array for slb cache Aneesh Kumar K.V
2012-07-25 12:58 ` [PATCH -V4 10/12] arch/powerpc: Add 64TB support Aneesh Kumar K.V
2012-07-25 12:58 ` [PATCH -V4 11/12] arch/powerpc: properly offset the context bits for 1T segemnts Aneesh Kumar K.V
2012-07-30 0:58 ` Paul Mackerras
2012-07-30 5:36 ` Aneesh Kumar K.V [this message]
2012-07-25 12:58 ` [PATCH -V4 12/12] arch/powerpc: properly isolate kernel and user proto-VSID Aneesh Kumar K.V
2012-07-25 15:21 ` Aneesh Kumar K.V
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=873949n738.fsf@skywalker.in.ibm.com \
--to=aneesh.kumar@linux$(echo .)vnet.ibm.com \
--cc=linuxppc-dev@lists$(echo .)ozlabs.org \
--cc=paulus@samba$(echo .)org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
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