From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f172.google.com (mail-ig0-f172.google.com [209.85.213.172]) by kanga.kvack.org (Postfix) with ESMTP id 2D88C6B00D2 for ; Thu, 13 Nov 2014 19:05:35 -0500 (EST) Received: by mail-ig0-f172.google.com with SMTP id a13so593899igq.17 for ; Thu, 13 Nov 2014 16:05:34 -0800 (PST) Received: from smtprelay.hostedemail.com (smtprelay0249.hostedemail.com. [216.40.44.249]) by mx.google.com with ESMTP id mx4si1202101igb.20.2014.11.13.16.05.33 for ; Thu, 13 Nov 2014 16:05:34 -0800 (PST) Message-ID: <1415923530.4223.17.camel@perches.com> Subject: Re: [RFC V6 2/3] arm:add bitrev.h file to support rbit instruction From: Joe Perches Date: Thu, 13 Nov 2014 16:05:30 -0800 In-Reply-To: <20141113235322.GC4042@n2100.arm.linux.org.uk> 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> Content-Type: text/plain; charset="ISO-8859-1" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Russell King - ARM Linux , Takashi Iwai Cc: "Wang, Yalin" , 'Will Deacon' , 'Ard Biesheuvel' , "'linux-kernel@vger.kernel.org'" , "'akinobu.mita@gmail.com'" , "'linux-mm@kvack.org'" , "'linux-arm-kernel@lists.infradead.org'" On Thu, 2014-11-13 at 23:53 +0000, Russell King - ARM Linux wrote: > 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? > > 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? > Shouldn't his entry be an Acked-by: ? I didn't sign off on or ack the "add bitrev.h" patch. I created 2 patches that converted direct uses of byte_rev_table to that bitrev8 static inline. One of them is already in -next 7a1283d8f5298437a454ec477384dcd9f9f88bac carl9170: Convert byte_rev_table uses to bitrev8 The other hasn't been applied. https://lkml.org/lkml/2014/10/28/1056 Maybe Takashi Iwai will get around to it one day. -- 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