From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753508AbeBKPex (ORCPT ); Sun, 11 Feb 2018 10:34:53 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:57850 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751077AbeBKPew (ORCPT ); Sun, 11 Feb 2018 10:34:52 -0500 Subject: Re: [PATCH v4 2/5] powerpc/mm/slice: Enhance for supporting PPC32 To: Nicholas Piggin , Christophe Leroy Cc: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Scott Wood , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org References: <01e8f783db8f4d4d41df91e0400a8634272b326f.1518226173.git.christophe.leroy@c-s.fr> <0ac518636ae1e601ea0732dd69b48dcd0f347285.1518226173.git.christophe.leroy@c-s.fr> <20180211235944.14c2be39@roar.ozlabs.ibm.com> From: "Aneesh Kumar K.V" Date: Sun, 11 Feb 2018 21:04:42 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 MIME-Version: 1.0 In-Reply-To: <20180211235944.14c2be39@roar.ozlabs.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 18021115-0004-0000-0000-000013A522FF X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00008516; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000251; SDB=6.00988212; UDB=6.00501673; IPR=6.00767566; BA=6.00005825; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00019492; XFM=3.00000015; UTC=2018-02-11 15:34:49 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18021115-0005-0000-0000-0000860A8E06 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-02-11_06:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1802110206 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/11/2018 07:29 PM, Nicholas Piggin wrote: > On Sat, 10 Feb 2018 13:54:27 +0100 (CET) > Christophe Leroy wrote: > >> In preparation for the following patch which will fix an issue on >> the 8xx by re-using the 'slices', this patch enhances the >> 'slices' implementation to support 32 bits CPUs. >> >> On PPC32, the address space is limited to 4Gbytes, hence only the low >> slices will be used. >> >> This patch moves "slices" functions prototypes from page64.h to slice.h >> >> The high slices use bitmaps. As bitmap functions are not prepared to >> handling bitmaps of size 0, the bitmap_xxx() calls are wrapped into >> slice_bitmap_xxx() functions which will void on PPC32 > > On this last point, I think it would be better to put these with the > existing slice bitmap functions in slice.c and just have a few #ifdefs > for SLICE_NUM_HIGH == 0. > We went back and forth with that. IMHO, we should avoid as much #ifdef as possible across platforms. It helps to understand the platform restrictions better as we have less and less access to these platforms. The above change indicates that nohash 32 wants to use the slice code and they have different restrictions. With that we now know that book3s64 and nohash 32 are the two different configs using slice code. -aneesh