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From: Catalin Marinas <catalin.marinas@arm.com>
To: "Shi, Yang" <yang.shi@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
	linaro-kernel@lists.linaro.org, Will Deacon <will.deacon@arm.com>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] arm64: remove redundant FRAME_POINTER kconfig option
Date: Fri, 6 Nov 2015 17:51:20 +0000	[thread overview]
Message-ID: <20151106175119.GD7637@e104818-lin.cambridge.arm.com> (raw)
In-Reply-To: <563CE5BB.2080701@linaro.org>

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.

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

-- 
Catalin

WARNING: multiple messages have this Message-ID (diff)
From: catalin.marinas@arm.com (Catalin Marinas)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] arm64: remove redundant FRAME_POINTER kconfig option
Date: Fri, 6 Nov 2015 17:51:20 +0000	[thread overview]
Message-ID: <20151106175119.GD7637@e104818-lin.cambridge.arm.com> (raw)
In-Reply-To: <563CE5BB.2080701@linaro.org>

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.

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

-- 
Catalin

  reply	other threads:[~2015-11-06 17:51 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-04 17:37 [PATCH] arm64: remove redundant FRAME_POINTER kconfig option Yang Shi
2015-11-04 17:37 ` Yang Shi
2015-11-06 12:30 ` Will Deacon
2015-11-06 12:30   ` Will Deacon
2015-11-06 12:50   ` Mark Rutland
2015-11-06 12:50     ` Mark Rutland
2015-11-06 15:42     ` Will Deacon
2015-11-06 15:42       ` Will Deacon
2015-11-06 16:21     ` Catalin Marinas
2015-11-06 16:21       ` Catalin Marinas
2015-11-06 16:25       ` Will Deacon
2015-11-06 16:25         ` Will Deacon
2015-11-06 17:23         ` Shi, Yang
2015-11-06 17:23           ` Shi, Yang
2015-11-06 17:35           ` Catalin Marinas
2015-11-06 17:35             ` Catalin Marinas
2015-11-06 17:39             ` Shi, Yang
2015-11-06 17:39               ` Shi, Yang
2015-11-06 17:51               ` Catalin Marinas [this message]
2015-11-06 17:51                 ` Catalin Marinas
2015-11-06 17:55                 ` Shi, Yang
2015-11-06 17:55                   ` Shi, Yang
2015-11-09 15:58                   ` Catalin Marinas
2015-11-09 15:58                     ` Catalin Marinas
2015-11-06 16:12   ` Catalin Marinas
2015-11-06 16:12     ` Catalin Marinas
2015-11-06 16:19     ` Will Deacon
2015-11-06 16:19       ` Will Deacon

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