[U-Boot] [RFC V1] arm: config: enforce -fno-pic for gcc

From: Peng Fan <van.freenix@gmail.com>
To: u-boot@lists.denx.de
Subject: [U-Boot] [RFC V1] arm: config: enforce -fno-pic for gcc
Date: Thu, 31 Dec 2015 15:07:47 +0800	[thread overview]
Message-ID: <20151231070745.GA5711@linux-7smt.suse> (raw)
In-Reply-To: <20151214072850.GA22680@shlinux2>

Hi Albert,

Gentle ping! Sorry for missing to mail you when I sent out the patch.

Thanks,
Peng.
On Mon, Dec 14, 2015 at 03:28:56PM +0800, Peng Fan wrote:
>Hi Albert,
>
>Do you have any comments on this patch?
>
>Regards,
>Peng.
>
>On Sat, Dec 05, 2015 at 03:53:46PM +0800, Peng Fan wrote:
>>Android's tool chain enable the -mandroid at default.
>>This option will enable the -fpic, which cause uboot compilation
>>failure:
>>"
>> LD      u-boot
>> u-boot contains unexpected relocations: R_ARM_ABS32
>> R_ARM_RELATIVE
>>"
>>
>>In my testcase, arm-linux-androideabi-gcc-4.9 internally
>>enables '-fpic', so when compiling code, there will be
>>relocation entries using type R_ARM_GOT_BREL and .got
>>section. When linking all the built-in.o using ld, there
>>will be R_ARM_ABS32 relocation entry and .got section
>>in the final u-boot elf image. This can not be handled
>>by u-boot, since u-boot only expects R_ARM_RELATIVE
>>relocation entry.
>>arm-poky-linux-gnueabi-gcc-4.9 default does not enable '-fpic',
>>so there is not .got section and R_ARM_GOT_BREL in built-in.o.
>>And in the final u-boot elf image, all relocation entries are
>>R_ARM_RELATIVE.
>>
>>we can pass '-fno-pic' to xxx-gcc to disable pic. whether
>>the toolchain internally enables or disables pic, '-fno-pic'
>>can work well.
>>
>>Signed-off-by: Peng Fan <Peng.Fan@freescale.com>
>>Cc: Albert Aribaud <albert.u.boot@aribaud.net>
>>---
>> arch/arm/config.mk | 1 +
>> 1 file changed, 1 insertion(+)
>>
>>diff --git a/arch/arm/config.mk b/arch/arm/config.mk
>>index 0550225..2b6322a 100644
>>--- a/arch/arm/config.mk
>>+++ b/arch/arm/config.mk
>>@@ -106,6 +106,7 @@ ALL-y += checkarmreloc
>> # instruction. Relocation is not supported for that case, so disable
>> # such usage by requiring word relocations.
>> PLATFORM_CPPFLAGS += $(call cc-option, -mword-relocations)
>>+PLATFORM_CPPFLAGS += $(call cc-option, -fno-pic)
>> endif
>> 
>> # limit ourselves to the sections we want in the .bin.
>>-- 
>>2.6.2
>>
>>
>
>-- 
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