From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932979AbbAIMlB (ORCPT ); Fri, 9 Jan 2015 07:41:01 -0500 Received: from cnbjrel02.sonyericsson.com ([219.141.167.166]:3349 "EHLO cnbjrel02.sonyericsson.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932419AbbAIMlA convert rfc822-to-8bit (ORCPT ); Fri, 9 Jan 2015 07:41:00 -0500 From: "Wang, Yalin" To: "'Russell King - ARM Linux'" CC: "'Ard Biesheuvel'" , "'Will Deacon'" , "'linux-kernel@vger.kernel.org'" , "'akinobu.mita@gmail.com'" , "'linux-mm@kvack.org'" , "'Joe Perches'" , "'linux-arm-kernel@lists.infradead.org'" Date: Fri, 9 Jan 2015 20:40:56 +0800 Subject: RE: [RFC V6 2/3] arm:add bitrev.h file to support rbit instruction Thread-Topic: [RFC V6 2/3] arm:add bitrev.h file to support rbit instruction Thread-Index: AdAr/PXsSIMtzQSaQvaNR/yTI7onlQACpIuA Message-ID: <35FD53F367049845BC99AC72306C23D103EDAF89E198@CNBJMBX05.corpusers.net> References: <20141030135749.GE32589@arm.com> <35FD53F367049845BC99AC72306C23D103E010D18272@CNBJMBX05.corpusers.net> <35FD53F367049845BC99AC72306C23D103E010D18273@CNBJMBX05.corpusers.net> <35FD53F367049845BC99AC72306C23D103E010D18275@CNBJMBX05.corpusers.net> <20141113235322.GC4042@n2100.arm.linux.org.uk> <35FD53F367049845BC99AC72306C23D103E010D1829B@CNBJMBX05.corpusers.net> <20141114095812.GG4042@n2100.arm.linux.org.uk> <35FD53F367049845BC99AC72306C23D103E688B313C6@CNBJMBX05.corpusers.net> <20150108184059.GZ12302@n2100.arm.linux.org.uk> <35FD53F367049845BC99AC72306C23D103EDAF89E195@CNBJMBX05.corpusers.net> <20150109111048.GE12302@n2100.arm.linux.org.uk> In-Reply-To: <20150109111048.GE12302@n2100.arm.linux.org.uk> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: text/plain; charset="iso-2022-jp" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > -----Original Message----- > From: Russell King - ARM Linux [mailto:linux@arm.linux.org.uk] > Sent: Friday, January 09, 2015 7:11 PM > To: Wang, Yalin > Cc: 'Ard Biesheuvel'; 'Will Deacon'; 'linux-kernel@vger.kernel.org'; > 'akinobu.mita@gmail.com'; 'linux-mm@kvack.org'; 'Joe Perches'; 'linux-arm- > kernel@lists.infradead.org' > Subject: Re: [RFC V6 2/3] arm:add bitrev.h file to support rbit instruction > > On Fri, Jan 09, 2015 at 10:16:32AM +0800, Wang, Yalin wrote: > > > -----Original Message----- > > > From: Russell King - ARM Linux [mailto:linux@arm.linux.org.uk] > > > Sent: Friday, January 09, 2015 2:41 AM > > > To: Wang, Yalin > > > Cc: 'Will Deacon'; 'Ard Biesheuvel'; 'linux-kernel@vger.kernel.org'; > > > 'akinobu.mita@gmail.com'; 'linux-mm@kvack.org'; 'Joe Perches'; > > > 'linux-arm- kernel@lists.infradead.org' > > > Subject: Re: [RFC V6 2/3] arm:add bitrev.h file to support rbit > > > instruction > > > > > > The root cause is that the kernel being built is supposed to support > > > both > > > ARMv7 and ARMv6K CPUs. However, "rbit" is only available on > > > ARMv6T2 (thumb2) and ARMv7, and not plain ARMv6 or ARMv6K CPUs. > > > > > In the patch that you applied: > > 8205/1 add bitrev.h file to support rbit instruction > > > > I have add : > > + select HAVE_ARCH_BITREVERSE if ((CPU_V7M || CPU_V7) && !CPU_V6) > > > > If you build kernel support ARMv6K, should CONFIG_CPU_V6=y, isn't it ? > > Then will not build hardware rbit instruction, isn't it ? > > The config has: > > CONFIG_CPU_PJ4=y > # CONFIG_CPU_V6 is not set > CONFIG_CPU_V6K=y > CONFIG_CPU_V7=y > CONFIG_CPU_32v6=y > CONFIG_CPU_32v6K=y > CONFIG_CPU_32v7=y > > And no, the CONFIG_CPU_V* flags refer to the CPUs. The > CONFIG_CPU_32v* symbols refer to the CPU architectures. > Oh, I see, How about change like this: + select HAVE_ARCH_BITREVERSE if ((CPU_V7M || CPU_V7) && !CPU_V6 && !CPU_V6K) I am not sure if I also need add some older CPU types like !CPU_ARM9TDMI &&　!CPU_ARM940T ? Another solution is: + select HAVE_ARCH_BITREVERSE if ((CPU_32V7M || CPU_32V7) && !CPU_32V6 && !CPU_32V5 && !CPU_32V4 && !CPU_32V4T && !CPU_32V3) By the way, I am not clear about the difference between CPU_V6 and CPU_V6K, could you tell me? :) Thank you