From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f51.google.com (mail-pa0-f51.google.com [209.85.220.51]) by kanga.kvack.org (Postfix) with ESMTP id 297A96B00E6 for ; Thu, 13 Nov 2014 21:01:42 -0500 (EST) Received: by mail-pa0-f51.google.com with SMTP id kq14so16589708pab.38 for ; Thu, 13 Nov 2014 18:01:41 -0800 (PST) Received: from cnbjrel01.sonyericsson.com (cnbjrel01.sonyericsson.com. [219.141.167.165]) by mx.google.com with ESMTPS id sv10si15426080pab.161.2014.11.13.18.01.39 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 13 Nov 2014 18:01:40 -0800 (PST) From: "Wang, Yalin" Date: Fri, 14 Nov 2014 10:01:34 +0800 Subject: RE: [RFC V6 2/3] arm:add bitrev.h file to support rbit instruction 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> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: 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'" > -----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) >=20 > 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 =3D y and CPU_V7 =3D y ? If there is problem like you said, How about this solution: select HAVE_ARCH_BITREVERSE if ((CPU_V7M || CPU_V7) && !CPU_V6) =20 > 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: >=20 > 6fire: Convert byte_rev_table uses to bitrev8 >=20 > Use the inline function instead of directly indexing the array. >=20 > This allows some architectures with hardware instructions for bit reversa= ls > to eliminate the array. >=20 > Signed-off-by: Joe Perches <(address hidden)> > Signed-off-by: Yalin Wang <(address hidden)> >=20 > Why is Joe signing off on these patches? As his is the first sign-off, o= ne > 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 entr= y > be an Acked-by: ? >=20 > 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org