linux-kernel - Re: Conflict between sparse and commit cafa0010cd51f ("Raise the minimum required gcc version to 4.6")

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Date:   Mon, 10 Sep 2018 09:56:33 +0000
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Luc Van Oostenryck <luc.vanoostenryck@...il.com>
Cc:     Nick Desaulniers <ndesaulniers@...gle.com>, joe@...ches.com,
        Kees Cook <keescook@...omium.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-sparse@...r.kernel.org, sparse@...isli.org,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: Conflict between sparse and commit cafa0010cd51f ("Raise the
 minimum required gcc version to 4.6")



On 09/10/2018 09:28 AM, Luc Van Oostenryck wrote:
> On Mon, Sep 10, 2018 at 08:49:07AM +0200, Christophe LEROY wrote:
>> Le 07/09/2018 à 20:19, Nick Desaulniers a écrit :
>>> On Fri, Sep 7, 2018 at 11:13 AM Luc Van Oostenryck wrote:
>>>>
>>>> Sparse expand these macros to the same version than the compiler used
>>>> to compile GCC. I find a bit strange though to have sparse v0.5.2 but
>>>> using an old compiler.
>>>
>>> So Christophe must have a version of gcc < 4.6 installed somewhere?
>>> Does sparse use `cc`? If so, Christophe, does your `ls -l $(which cc)`
>>> point to an old version of gcc maybe?
>>
>> Indeed it looks like sparse expand these macros to the version of
>> the compiler it was compiled with.
>>
>> I'm building kernels for a powerpc platforms, with CROSS_COMPILE set
>> to ppc-linux- and ppc-linux-gcc being version 5.4
>>
>> However my build machine is a CentOS6 and the native gcc has version
>> 4.4.7, so sparse expands that version.
> 
> OK, I see.
>   
>> Is there a way to get sparse in line with my cross compiler version
>> and not with the local native version ?
> 
> When cross-compiling, there is also things like the machine word-size
> and the endianness to take in account (they also default to the
> native compiler used to compile sparse itself) as well as a few
> defines (like __PPC64__). To be in line with your cross-compiler
> you can use to the wrapper 'cgcc' (installed with sparse) and call
> it, for example, like this:
> 	$ export REAL_CC=ppc-linux-gcc
> 	$ cgcc -target=ppcc64 -D_CALL_ELF=2 -D__GCC__=5 -D__GCC_MINOR__=4 ...
> or, since this is for the kernel:
> 	$ export REAL_CC=ppc-linux-gcc
> 	$ make CHECK='cgcc -target=ppcc64 ...
> 
> 
> I think this should solve it. Do not hesitate to report any
> difficulties you may encounter.

# export REAL_CC=ppc-linux-gcc
# make CHECK="cgcc -target=ppc -D_CALL_ELF=2 -D__GCC__=5 
-D__GCC_MINOR__=4" C=2 arch/powerpc/kernel/process.o
scripts/kconfig/conf  --syncconfig Kconfig
#
# configuration written to .config
#
   UPD     include/config/kernel.release
   UPD     include/generated/utsrelease.h
   CC      kernel/bounds.s
   CC      arch/powerpc/kernel/asm-offsets.s
   CALL    scripts/checksyscalls.sh
   CHECK   scripts/mod/empty.c
Can't exec "/bin/sh": Argument list too long at /usr/local/bin/cgcc line 86.
make[2]: *** [scripts/mod/empty.o] Error 1
make[1]: *** [scripts/mod] Error 2
make: *** [scripts] Error 2

Christophe

> 
> -- Luc
>