linux-kernel - Re: [PATCH] kbuild: add endianness flag to CHEKCFLAGS

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Message-ID: <7ce087bc-dd52-bae8-96f2-fad91f5a345e@infradead.org>
Date:   Mon, 28 May 2018 10:31:58 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Luc Van Oostenryck <luc.vanoostenryck@...il.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Jonas Bonn <jonas@...thpole.se>,
        Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
        Stafford Horne <shorne@...il.com>,
        "James E . J . Bottomley" <jejb@...isc-linux.org>,
        Helge Deller <deller@....de>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>
Cc:     Michal Marek <michal.lkml@...kovi.net>,
        linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
        openrisc@...ts.librecores.org, linux-parisc@...r.kernel.org,
        linux-s390@...r.kernel.org
Subject: Re: [PATCH] kbuild: add endianness flag to CHEKCFLAGS

On 05/28/2018 10:00 AM, Luc Van Oostenryck wrote:
> The kernel depends on macros like __BYTE_ORDER__,
> __BIG_ENDIAN__ or __LITTLE_ENDIAN__.
> 
> OTOH, sparse doesn't know about the endianness of the kernel and
> by default uses the same as the machine on which sparse was built.
> 
> Ensure that sparse can predefine the macros corresponding to
> how the kernel was configured by adding -m{big,little}-endian
> to CHECKFLAGS in the main Makefile (and so for all archs).
> Also, remove the equivalent done in arch specific Makefiles.
> 
> Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@...il.com>
> ---
>  Makefile               | 3 +++
>  arch/openrisc/Makefile | 1 -
>  arch/parisc/Makefile   | 2 +-
>  arch/s390/Makefile     | 2 +-
>  4 files changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index 56ba070df..057a278d2 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -878,6 +878,9 @@ ifeq ($(CONFIG_STRIP_ASM_SYMS),y)
>  LDFLAGS_vmlinux	+= $(call ld-option, -X,)
>  endif
>  
> +# insure the checker run with the right endianness
> +CHECKFLAGS += $(if $(CONFIG_CPU_BIG_ENDIAN),-mbig,-mlittle)

Does this need to be                           -mbig-endian,-mlittle-endian)

> +
>  # Default kernel image to build when no specific target is given.
>  # KBUILD_IMAGE may be overruled on the command line or
>  # set in the environment
> diff --git a/arch/openrisc/Makefile b/arch/openrisc/Makefile
> index cf8802962..89076a66e 100644
> --- a/arch/openrisc/Makefile
> +++ b/arch/openrisc/Makefile
> @@ -25,7 +25,6 @@ LDFLAGS_vmlinux :=
>  LIBGCC 		:= $(shell $(CC) $(KBUILD_CFLAGS) -print-libgcc-file-name)
>  
>  KBUILD_CFLAGS	+= -pipe -ffixed-r10 -D__linux__
> -CHECKFLAGS	+= -mbig-endian
>  
>  ifeq ($(CONFIG_OPENRISC_HAVE_INST_MUL),y)
>  	KBUILD_CFLAGS += $(call cc-option,-mhard-mul)
> diff --git a/arch/parisc/Makefile b/arch/parisc/Makefile
> index 34ac503e2..348ae4779 100644
> --- a/arch/parisc/Makefile
> +++ b/arch/parisc/Makefile
> @@ -22,7 +22,7 @@ KBUILD_IMAGE := vmlinuz
>  KBUILD_DEFCONFIG := default_defconfig
>  
>  NM		= sh $(srctree)/arch/parisc/nm
> -CHECKFLAGS	+= -D__hppa__=1 -mbig-endian
> +CHECKFLAGS	+= -D__hppa__=1
>  LIBGCC		= $(shell $(CC) $(KBUILD_CFLAGS) -print-libgcc-file-name)
>  export LIBGCC
>  
> diff --git a/arch/s390/Makefile b/arch/s390/Makefile
> index c79936d02..68a690442 100644
> --- a/arch/s390/Makefile
> +++ b/arch/s390/Makefile
> @@ -18,7 +18,7 @@ KBUILD_CFLAGS	+= -m64
>  KBUILD_AFLAGS	+= -m64
>  UTS_MACHINE	:= s390x
>  STACK_SIZE	:= 16384
> -CHECKFLAGS	+= -D__s390__ -D__s390x__ -mbig-endian
> +CHECKFLAGS	+= -D__s390__ -D__s390x__
>  
>  export LD_BFD
>  
> 


-- 
~Randy