From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3zfXt66Pp3zDq7b for ; Mon, 12 Feb 2018 02:34:54 +1100 (AEDT) Received: from pps.filterd (m0098420.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w1BFY3Mv097296 for ; Sun, 11 Feb 2018 10:34:52 -0500 Received: from e32.co.us.ibm.com (e32.co.us.ibm.com [32.97.110.150]) by mx0b-001b2d01.pphosted.com with ESMTP id 2g2fa3c2cw-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Sun, 11 Feb 2018 10:34:51 -0500 Received: from localhost by e32.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Sun, 11 Feb 2018 08:34:51 -0700 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 MIME-Version: 1.0 In-Reply-To: <20180211235944.14c2be39@roar.ozlabs.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Message-Id: List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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