From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161852AbbKFRz5 (ORCPT ); Fri, 6 Nov 2015 12:55:57 -0500 Received: from mail-pa0-f44.google.com ([209.85.220.44]:36360 "EHLO mail-pa0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161695AbbKFRz4 (ORCPT ); Fri, 6 Nov 2015 12:55:56 -0500 Message-ID: <563CE9AA.8050905@linaro.org> Date: Fri, 06 Nov 2015 09:55:54 -0800 From: "Shi, Yang" User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Catalin Marinas CC: Mark Rutland , linaro-kernel@lists.linaro.org, Will Deacon , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] arm64: remove redundant FRAME_POINTER kconfig option References: <1446658671-16238-1-git-send-email-yang.shi@linaro.org> <20151106123008.GK6087@arm.com> <20151106125002.GA8116@leverpostej> <20151106162109.GZ7637@e104818-lin.cambridge.arm.com> <20151106162538.GU6087@arm.com> <563CE21A.6060803@linaro.org> <20151106173558.GC7637@e104818-lin.cambridge.arm.com> <563CE5BB.2080701@linaro.org> <20151106175119.GD7637@e104818-lin.cambridge.arm.com> In-Reply-To: <20151106175119.GD7637@e104818-lin.cambridge.arm.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/6/2015 9:51 AM, Catalin Marinas wrote: > On Fri, Nov 06, 2015 at 09:39:07AM -0800, Shi, Yang wrote: >> On 11/6/2015 9:35 AM, Catalin Marinas wrote: >>> On Fri, Nov 06, 2015 at 09:23:38AM -0800, Shi, Yang wrote: >>>> On 11/6/2015 8:25 AM, Will Deacon wrote: >>>>> However, the patch would allow one to >>>>> disable FRAME_POINTERS (not sure it has any effect on the aarch64 gcc >>>>> though). >>>> >>>> No, it doesn't. Actually, FRAME_POINTER could be disabled regardless of the >>>> patch. >>> >>> In which case I suggest that we always select it just as a clearer >>> statement that the feature cannot be disabled (and you never know what >>> the compiler people decide to do in the future). >> >> Do you mean select FRAME_POINTER in ARCH_WANT_FRAME_POINTERS? >> >> Yes, we could, but this may cause other architectures which select >> ARCH_WANT_FRAME_POINTERS to have FRAME_POINTER selected too. > > This would have been the ideal option, something like: > > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -322,7 +322,7 @@ config ARCH_WANT_FRAME_POINTERS > help > > config FRAME_POINTER > - bool "Compile the kernel with frame pointers" > + bool "Compile the kernel with frame pointers" if !ARCH_WANT_FRAME_POINTERS > depends on DEBUG_KERNEL && \ > (CRIS || M68K || FRV || UML || \ > AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \ > > But, as you said, we would need to check the other architectures > selecting ARCH_WANT_FRAME_POINTERS. How about: diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 1d1521c..709255a 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -319,6 +319,7 @@ config DEBUG_SECTION_MISMATCH # config ARCH_WANT_FRAME_POINTERS bool + select FRAME_POINTER if ARM64 help config FRAME_POINTER If other architectures want the same behavior, they could easily append to the is statement. If all arches which selects ARCH_WANT_FRAME_POINTERS, the if statement could be just removed. Yang > > In the meantime: > > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -27,6 +27,7 @@ config ARM64 > select CPU_PM if (SUSPEND || CPU_IDLE) > select DCACHE_WORD_ACCESS > select EDAC_SUPPORT > + select FRAME_POINTER > select GENERIC_ALLOCATOR > select GENERIC_CLOCKEVENTS > select GENERIC_CLOCKEVENTS_BROADCAST >