Re: [PATCH] Makerules: pass CFLAGS when building .S files, BZ #23273

[Sergei Trofimovich <slyich at gmail dot com>]

On Mon, 11 Jun 2018 15:22:50 +0200
Florian Weimer <fweimer@redhat.com> wrote:

> On 06/11/2018 03:18 PM, Sergei Trofimovich wrote:
> > On Mon, 11 Jun 2018 14:50:24 +0200
> > Florian Weimer <fweimer@redhat.com> wrote:
> >   
> >> On 06/11/2018 02:35 PM, Sergei Trofimovich wrote:  
> >>> On Mon, 11 Jun 2018 08:17:37 -0300
> >>> Adhemerval Zanella <adhemerval.zanella@linaro.org> wrote:
> >>>      
> >>>> On 11/06/2018 07:46, Florian Weimer wrote:  
> >>>>> On 06/11/2018 12:28 PM, Sergei Trofimovich wrote:  
> >>>>>> When glibc is built on armv7 with CFLAGS="-pipe -march=armv7-a -O2 -mfpu=neon"
> >>>>>> rtld fails to link due to missing memcpy symbol.
> >>>>>>
> >>>>>> This happens because .c files are built with -mfpu=neon flag but .S/.s files
> >>>>>> are built without it. Among other things -mfpu=neon defines __ARM_NEON__.
> >>>>>>
> >>>>>> To fix this mismatch CFLAGS should be passed consistently to .c and .S files.  
> >>>>>
> >>>>> Please check if you can fix this by putting the architecture selection flags into the CC and CXX variables when invoking configure.  
> >>>
> >>> I'm not sure just adding an arch flag is enough:
> >>>       https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/arm/armv7/multiarch/memcpy_neon.S;h=1a8d8bbe9e128618105be0652de42a34fbc52d73;hb=HEAD
> >>>      ...
> >>>      2 #ifndef __ARM_NEON__
> >>>      3 # define memcpy __memcpy_neon
> >>> Here memcpy_neon.S explicitly supports both neon-enabled and disabled flags.  
> >>
> >> Does this mean your proposed patch fails to address the issue, too?  
> > 
> > My proposed patch fixes ld.so linkage (and ld.so seems to work).  
> 
> Yes, but what about using CC/CXX setting at configure time to achieve 
> the same effect?

The below works on unmodified glibc as well:

$ ../glibc/configure \
    --build=x86_64-pc-linux-gnu \
    --host=armv7a-hardfloat-linux-gnueabi \
    CC="armv7a-hardfloat-linux-gnueabi-gcc -march=armv7-a -mfpu=neon" \
    CFLAGS="-pipe -O2" \
    --prefix=/usr

-- 

  Sergei

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