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Date:   Mon, 10 Sep 2018 15:56:05 +0200
From:   Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
To:     Christophe Leroy <christophe.leroy@c-s.fr>
Cc:     Nick Desaulniers <ndesaulniers@google.com>, joe@perches.com,
        Kees Cook <keescook@chromium.org>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-sparse@vger.kernel.org, sparse@chrisli.org,
        linuxppc-dev@lists.ozlabs.org
Subject: Re: Conflict between sparse and commit cafa0010cd51f ("Raise the
 minimum required gcc version to 4.6")
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On Mon, Sep 10, 2018 at 01:19:07PM +0000, Christophe Leroy wrote:
> 
> 
> On 09/10/2018 11:34 AM, Luc Van Oostenryck wrote:
> > On Mon, Sep 10, 2018 at 09:56:33AM +0000, Christophe Leroy wrote:
> > > 
> > > # 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
> > 
> > OK. Clearly nobody has ever used it so :(
> > There is an infinite loop because cgcc use the env var CHECK
> > to call sparse while kbuild use CHECK to call cgcc here.
> > 
> > The following seems to work here.
> > $ export REAL_CC=ppc-linux-gcc
> > $ make CHECK="CHECK=sparse cgcc -target=ppc ...
> 
> Not yet ...
> 
> [root@pc16082vm linux-powerpc]# export REAL_CC=ppc-linux-gcc
> [root@pc16082vm linux-powerpc]# make CHECK="CHECK=sparse cgcc
> -target=ppc -D_CALL_ELF=2 -D__GNUC__=5 -D__GNUC_MINOR__=4" C=2
> arch/powerpc/kernel/process.o
>   CALL    scripts/checksyscalls.sh
>   CHECK   scripts/mod/empty.c
> <command-line>:0:0: warning: "__STDC__" redefined
> <built-in>: note: this is the location of the previous definition
> /opt/cldk-1.4.0/lib/gcc/ppc-linux/5.4.0/../../../../ppc-linux/lib/crt1.o:(.rodata+0x4):
> undefined reference to `main'
> collect2: error: ld returned 1 exit status
> make[2]: *** [scripts/mod/empty.o] Error 1
> make[1]: *** [scripts/mod] Error 2
> make: *** [scripts] Error 2

OK. Using cgcc creates more problems that it solves and this file
scripts/mod/empty.c is weird.
Dropping cgcc and simply giving the GCC version to sparse works for
me here (the needed defines are given by arch/powerpc/Makefile) but
for sure I don't have the same environment as you have:
  $ make CHECK="sparse -D__GNUC__=5 -D__GNUC_MINOR__=4" ...

Bonne chance,
-- Luc