Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934964AbaKNCBj (ORCPT ); Thu, 13 Nov 2014 21:01:39 -0500 Received: from cnbjrel01.sonyericsson.com ([219.141.167.165]:12020 "EHLO cnbjrel01.sonyericsson.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933518AbaKNCBi convert rfc822-to-8bit (ORCPT ); Thu, 13 Nov 2014 21:01:38 -0500 From: "Wang, Yalin" To: "'Russell King - ARM Linux'" 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'" Date: Fri, 14 Nov 2014 10:01:34 +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: Ac//nQoUxyiR4A/+S1KTxThngzC6WQAET/GA Message-ID: <35FD53F367049845BC99AC72306C23D103E010D1829B@CNBJMBX05.corpusers.net> References: <35FD53F367049845BC99AC72306C23D103E010D18261@CNBJMBX05.corpusers.net> <35FD53F367049845BC99AC72306C23D103E010D18264@CNBJMBX05.corpusers.net> <35FD53F367049845BC99AC72306C23D103E010D18265@CNBJMBX05.corpusers.net> <35FD53F367049845BC99AC72306C23D103E010D18266@CNBJMBX05.corpusers.net> <20141030120127.GC32589@arm.com> <20141030135749.GE32589@arm.com> <35FD53F367049845BC99AC72306C23D103E010D18272@CNBJMBX05.corpusers.net> <35FD53F367049845BC99AC72306C23D103E010D18273@CNBJMBX05.corpusers.net> <35FD53F367049845BC99AC72306C23D103E010D18275@CNBJMBX05.corpusers.net> <20141113235322.GC4042@n2100.arm.linux.org.uk> In-Reply-To: <20141113235322.GC4042@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="us-ascii" 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, November 14, 2014 7:53 AM > To: Wang, Yalin > > On Fri, Oct 31, 2014 at 01:42:44PM +0800, Wang, Yalin wrote: > > This patch add bitrev.h file to support rbit instruction, so that we > > can do bitrev operation by hardware. > > Signed-off-by: Yalin Wang > > --- > > arch/arm/Kconfig | 1 + > > arch/arm/include/asm/bitrev.h | 21 +++++++++++++++++++++ > > 2 files changed, 22 insertions(+) > > create mode 100644 arch/arm/include/asm/bitrev.h > > > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index > > 89c4b5c..be92b3b 100644 > > --- a/arch/arm/Kconfig > > +++ b/arch/arm/Kconfig > > @@ -28,6 +28,7 @@ config ARM > > select HANDLE_DOMAIN_IRQ > > select HARDIRQS_SW_RESEND > > select HAVE_ARCH_AUDITSYSCALL if (AEABI && !OABI_COMPAT) > > + select HAVE_ARCH_BITREVERSE if (CPU_V7M || CPU_V7) > > Looking at this, this is just wrong. Take a moment to consider what > happens if we build a kernel which supports both ARMv6 _and_ ARMv7 CPUs. > What happens if an ARMv6 CPU tries to execute an rbit instruction? Is it possible to build a kernel that support both CPU_V6 and CPU_V7? I mean in Kconfig, CPU_V6 = y and CPU_V7 = y ? If there is problem like you said, How about this solution: select HAVE_ARCH_BITREVERSE if ((CPU_V7M || CPU_V7) && !CPU_V6) > Second point (which isn't obvious from your submissions on-list) is that > you've loaded the patch system up with patches for other parts of the > kernel tree for which I am not responsible for. As such, I can't take > those patches without the sub-tree maintainer acking them. Also, the > commit text in those patches look weird: > > 6fire: Convert byte_rev_table uses to bitrev8 > > Use the inline function instead of directly indexing the array. > > This allows some architectures with hardware instructions for bit reversals > to eliminate the array. > > Signed-off-by: Joe Perches <(address hidden)> > Signed-off-by: Yalin Wang <(address hidden)> > > Why is Joe signing off on these patches? As his is the first sign-off, one > assumes that he was responsible for creating the patch in the first place, > but there is no From: line marking him as the author. Shouldn't his entry > be an Acked-by: ? > > Confused. For this patch, I just cherry-pick from Joe, If you are not responsible for this part, I will submit to the maintainers for these patches . Sorry for that . -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/