From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f53.google.com (mail-wg0-f53.google.com [74.125.82.53]) by kanga.kvack.org (Postfix) with ESMTP id 8EFB96B00D4 for ; Thu, 13 Nov 2014 18:53:36 -0500 (EST) Received: by mail-wg0-f53.google.com with SMTP id b13so18039039wgh.12 for ; Thu, 13 Nov 2014 15:53:36 -0800 (PST) Received: from pandora.arm.linux.org.uk (pandora.arm.linux.org.uk. [2001:4d48:ad52:3201:214:fdff:fe10:1be6]) by mx.google.com with ESMTPS id dz13si46737846wjb.100.2014.11.13.15.53.35 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Thu, 13 Nov 2014 15:53:35 -0800 (PST) Date: Thu, 13 Nov 2014 23:53:22 +0000 From: Russell King - ARM Linux Subject: Re: [RFC V6 2/3] arm:add bitrev.h file to support rbit instruction Message-ID: <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <35FD53F367049845BC99AC72306C23D103E010D18275@CNBJMBX05.corpusers.net> Sender: owner-linux-mm@kvack.org List-ID: 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'" 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? 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. -- FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up according to speedtest.net. -- 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