[Buildroot] [PATCH] Clarify MIPS ABIs support

Thomas Petazzoni thomas.petazzoni at free-electrons.com
Wed Jul 25 16:29:43 UTC 2012 

Hello Gustavo,

If you could have a look at the below patch, and provide your comments
or Acked-by, it would be great.

Thanks a lot!

Thomas

Le Tue, 24 Jul 2012 22:47:08 +0200,
Thomas Petazzoni <thomas.petazzoni at free-electrons.com> a écrit :

> Practically speaking, MIPS has three useful ABIs:
> 
>  * o32 is for 32-bits CPUs, or 64-bit CPUs running only a 32-bit subset
>    of the instruction set.
>  * n32 is for 64-bits CPUs only. It has 32-bits pointers and long
>    integers.
>  * n64 is for 64-bits CPUs only. It has 64-bits pointers and long
>    integers.
> 
> See http://www.linux-mips.org/wiki/MIPS_ABI_History and
> http://www.linux-mips.org/wiki/WhatsWrongWithO32N32N64 for more
> details.
> 
> So, this commit reworks the Buildroot MIPS support by:
> 
>  * Renaming the n32 ABI option to BR2_MIPS_NABI32, for consistency
>    with BR2_MIPS_OABI32.
> 
>  * Renaming the n64 ABI option to BR2_MIPS_NABI64, for consistency
>    with BR2_MIPS_OABI32.
> 
>  * Make the n32 and n64 ABI selections select the BR2_ARCH_IS_64,
>    since those ABIs are valid on 64-bits CPUs only.
> 
>  * Removing the o64 ABI, which is practicaly never used.
> 
>  * Removing the "none" ABI, which really doesn't make sense.
> 
>  * Introduce the mips64 and mips64el architecture names when a 64-bits
>    MIPS ABI is choosen. This will fix build issue like
>    http://autobuild.buildroot.org/results/9b8c5ea86c953a89e85e7b67e9221de41773f652/build-end.log
>    where gmp was confused by the fact of having a 32 bits architecture
>    (detected by the mips- architecture part of the tuple) but 64 bits
>    integer size when compiling.
> 
>  * Adjust the uclibc.mk logic to support the new mips64/mips64el
>    architecture names, and take into account the renaming of the ABI
>    options.
> 
> This has been build tested by generating Buildroot toolchains and
> compiling a few packages for MIPS o32, MIPS n32 and MIPS n64.
> 
> This work is originally based on prior work done by Gustavo Zacarias.
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
> ---
>  package/Makefile.in        |    2 +-
>  target/Config.in.arch      |   28 +++++++++++-----------------
>  toolchain/uClibc/uclibc.mk |    9 ++++++---
>  3 files changed, 18 insertions(+), 21 deletions(-)
> 
> diff --git a/package/Makefile.in b/package/Makefile.in
> index 6fad224..21b8634 100644
> --- a/package/Makefile.in
> +++ b/package/Makefile.in
> @@ -87,7 +87,7 @@ endif
>  
>  TARGET_CFLAGS=$(TARGET_ABI) $(TARGET_OPTIMIZATION) $(TARGET_DEBUGGING)
>  
> -ifeq ($(findstring yy,$(BR2_mips)$(BR2_MIPS_ABI64)),yy)
> +ifeq ($(findstring yy,$(BR2_mips)$(BR2_MIPS_NABI64)),yy)
>  TARGET_CFLAGS+=-fno-pic -mno-abicalls
>  endif
>  
> diff --git a/target/Config.in.arch b/target/Config.in.arch
> index e7aec56..0ef59ef 100644
> --- a/target/Config.in.arch
> +++ b/target/Config.in.arch
> @@ -271,26 +271,20 @@ choice
>  	prompt "Target ABI"
>  	depends on BR2_mips || BR2_mipsel
>  	default BR2_MIPS_OABI32 if BR_mips_32 || BR_mips_32r2
> -	default BR2_MIPS_ABI32 if BR_mips_64 || BR_mips_64r2
> +	default BR2_MIPS_NABI32 if BR_mips_64 || BR_mips_64r2
>  	help
>  	  Application Binary Interface to use
>  
>  config BR2_MIPS_OABI32
>  	bool "o32"
> -config BR2_MIPS_ABI32
> +config BR2_MIPS_NABI32
>  	bool "n32"
> +	select BR2_ARCH_IS_64
>  	depends on BR2_mips_3 || BR2_mips_4 || BR2_mips_64 || BR2_mips_64r2 || BR2_mips_16
> -config BR2_MIPS_ABI64
> +config BR2_MIPS_NABI64
>  	bool "n64"
> +	select BR2_ARCH_IS_64
>  	depends on BR2_mips_3 || BR2_mips_4 || BR2_mips_64 || BR2_mips_64r2 || BR2_mips_16
> -config BR2_MIPS_OABI64
> -	bool "o64"
> -	depends on BR2_mips_3 || BR2_mips_4 || BR2_mips_64 || BR2_mips_64r2 || BR2_mips_16
> -config BR2_MIPS_ABI_none
> -	bool "unspecified"
> -	depends on BR2_mips_16
> -	help
> -	  Unspecified ABI leaves ABI selection blank.
>  endchoice
>  
>  choice
> @@ -688,8 +682,10 @@ config BR2_ARCH
>  	default "i686"		if BR2_x86_athlon_4
>  	default "m68k"		if BR2_m68k
>  	default "microblaze"	if BR2_microblaze
> -	default "mips"		if BR2_mips
> -	default "mipsel"	if BR2_mipsel
> +	default "mips"		if BR2_mips && !BR2_ARCH_IS_64
> +	default "mipsel"	if BR2_mipsel && !BR2_ARCH_IS_64
> +	default "mips64"	if BR2_mips && BR2_ARCH_IS_64
> +	default "mips64el"	if BR2_mipsel && BR2_ARCH_IS_64
>  	default "powerpc"	if BR2_powerpc
>  	default "sh2"		if BR2_sh2
>  	default "sh2a"		if BR2_sh2a
> @@ -904,10 +900,8 @@ config BR2_GCC_TARGET_ABI
>  	default aapcs		if BR2_arm_dunno
>  	default aapcs-linux	if BR2_ARM_EABI
>  	default 32		if BR2_MIPS_OABI32
> -	default n32		if BR2_MIPS_ABI32
> -	default eabi		if BR2_MIPS_EABI
> -	default o64		if BR2_MIPS_OABI64
> -	default 64		if BR2_MIPS_ABI64
> +	default n32		if BR2_MIPS_NABI32
> +	default 64		if BR2_MIPS_NABI64
>  	default mmixware	if BR2_mmix && BR2_MMIX_ABI_native
>  	default gnu		if BR2_mmix && !BR2_MMIX_ABI_native
>  	default altivec		if BR2_powerpc && BR2_PPC_ABI_altivec
> diff --git a/toolchain/uClibc/uclibc.mk b/toolchain/uClibc/uclibc.mk
> index 9d0b6db..aff0a60 100644
> --- a/toolchain/uClibc/uclibc.mk
> +++ b/toolchain/uClibc/uclibc.mk
> @@ -38,6 +38,7 @@ UCLIBC_TARGET_ARCH:=$(shell $(SHELL) -c "echo $(ARCH) | sed \
>  		-e 's/sh[234].*/sh/' \
>  		-e 's/mips.*/mips/' \
>  		-e 's/mipsel.*/mips/' \
> +		-e 's/mips64el.*/mips/' \
>  		-e 's/cris.*/cris/' \
>  		-e 's/xtensa.*/xtensa/' \
>  ")
> @@ -45,6 +46,8 @@ UCLIBC_TARGET_ARCH:=$(shell $(SHELL) -c "echo $(ARCH) | sed \
>  UCLIBC_TARGET_ENDIAN:=$(shell $(SHELL) -c "echo $(ARCH) | sed \
>  		-e 's/armeb/BIG/' \
>  		-e 's/arm/LITTLE/' \
> +		-e 's/mips64el/LITTLE/' \
> +		-e 's/mips64/BIG/' \
>  		-e 's/mipsel/LITTLE/' \
>  		-e 's/mips/BIG/' \
>  		-e 's/sh.*eb/BIG/' \
> @@ -155,13 +158,13 @@ ifeq ($(UCLIBC_TARGET_ARCH),mips)
>  	 /bin/echo "# CONFIG_MIPS_ISA_MIPS32R2 is not set"; \
>  	 /bin/echo "# CONFIG_MIPS_ISA_MIPS64 is not set"; \
>  	) >> $(UCLIBC_DIR)/.oldconfig
> -ifeq ($(BR2_MIPS_OABI),y)
> +ifeq ($(BR2_MIPS_OABI32),y)
>  	$(SED) 's/.*\(CONFIG_MIPS_O32_ABI\).*/\1=y/' $(UCLIBC_DIR)/.oldconfig
>  endif
> -ifeq ($(BR2_MIPS_ABI32),y)
> +ifeq ($(BR2_MIPS_NABI32),y)
>  	$(SED) 's/.*\(CONFIG_MIPS_N32_ABI\).*/\1=y/' $(UCLIBC_DIR)/.oldconfig
>  endif
> -ifeq ($(BR2_MIPS_ABI64),y)
> +ifeq ($(BR2_MIPS_NABI64),y)
>  	$(SED) 's/.*\(CONFIG_MIPS_N64_ABI\).*/\1=y/' $(UCLIBC_DIR)/.oldconfig
>  endif
>  ifeq ($(BR2_mips_1),y)



-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

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