From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f173.google.com (mail-wi0-f173.google.com [209.85.212.173]) by kanga.kvack.org (Postfix) with ESMTP id 55A966B00D4 for ; Fri, 14 Nov 2014 02:03:03 -0500 (EST) Received: by mail-wi0-f173.google.com with SMTP id n3so1713946wiv.12 for ; Thu, 13 Nov 2014 23:03:02 -0800 (PST) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id hj4si47807405wjc.122.2014.11.13.23.03.02 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 13 Nov 2014 23:03:02 -0800 (PST) Date: Fri, 14 Nov 2014 08:03:01 +0100 Message-ID: From: Takashi Iwai Subject: Re: [RFC V6 2/3] arm:add bitrev.h file to support rbit instruction In-Reply-To: <1415948109.5912.12.camel@perches.com> 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> <1415923530.4223.17.camel@perches.com> <1415948109.5912.12.camel@perches.com> MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Joe Perches Cc: Russell King - ARM Linux , "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'" At Thu, 13 Nov 2014 22:55:09 -0800, Joe Perches wrote: > > On Fri, 2014-11-14 at 07:37 +0100, Takashi Iwai wrote: > > At Thu, 13 Nov 2014 16:05:30 -0800, > > Joe Perches wrote: > > > > > > 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. > > > > It was not clear to me whether I should apply it individually from > > others in the whole thread. Your description looked as if it makes > > sense only with ARM's bitrev8 support. > > > > So, again: should I apply this now to my tree? > > I it would be good to apply even if the > bitrev patch for arm is never applied. > > $ git grep -w bitrev8 | wc -l > 110 > > vs > > this last direct use of byte_rev_table. Alright, I picked up your original patch and merged. thanks, Takashi -- 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