[U-Boot] GCC5.x support for old u-boot version

[Ayoub Zaki]

Hello,

we have an am335x based custom board that use for our Project.
At the moment only a customized version of uboot-2013.01.01 supports this
board.
As we use Yocto toolchains and we plan to upgrade to latest Yocto-2.0 that
comes with GCC5.2.

I would like to be able to build this custom old version with newer
toolchains.

For that I added from new u-boot the file :
 include/linux/compiler-gcc5.h

But still having some compile errors :

| arm-poky-linux-gnueabi-gcc  --sysroot=/yocto/build/tmp/sysroots/shc  -g
-Os   -fno-common -ffixed-r8 -msoft-float  -D__KERNEL__
-DCONFIG_SYS_TEXT_BASE=0x80800000 -DCONFIG_SPL_TEXT_BASE=0x402F0400
-I/yocto/build/tmp/work/shc-poky-linux-gnueabi/u-boot-shc/1.0-r1/git/include
-fno-builtin -ffreestanding -nostdinc -isystem
/yocto/build/tmp/sysroots/x86_64-linux/usr/lib/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/5.2.0/include
-pipe  -DCONFIG_ARM -D__ARM__ -marm -mno-thumb-interwork -mabi=aapcs-linux
-march=armv7-a -mcpu=cortex-a8 -Wall -Wstrict-prototypes
-fno-stack-protector -Wno-format-nonliteral -Wno-format-security
-fstack-usage     -o s_record.o s_record.c -c
| main.c:62:6: error: 'show_boot_progress' aliased to external symbol
'__show_boot_progress'
|  void show_boot_progress (int val) __attribute__((weak,
alias("__show_boot_progress")));
|       ^
| make[1]: *** [main.o] Error 1
| make[1]: Leaving directory
`/yocto/build/tmp/work/shc-poky-linux-gnueabi/u-boot/1.0-r1/git/common'
| make: *** [common/libcommon.o] Error 2

Any chance to backport GCC5 support to old u-boot version ?

Thank you for suggestions.

Best regards,

Ayoub Zaki