HI Adhemerval,

Thanks a lot for the response.

If you look into the arm preconfgure.ac , (
https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/arm/preconfigure.ac;h=a70738526311c0b0ed21b175eec0bee90c850025;hb=9e2ff880f3cbc0b4ec8505ad2ce4a1c92d7f6d56)
, you would notice :

 CFLAGS="$CFLAGS -fno-unwind-tables" or -fno-unwind-tables is getting added
to the cflags during configure.

This is conflicting with -fasynchronous-unwind-tables that I passed. And I
am getting following error :
=======================================================================================

arm-linux-gnueabihf-gcc  -march=armv7ve -mthumb -mfpu=neon -mfloat-abi=hard
 --sysroot=/yocto/build/tmp/work/armv7vet2hf-neon-poky-linux-gnueabi/glibc/linaro-2.25-r0/recipe-sysroot
 -isystem/opt/archive-pkgs/gcc-linaro-7.4.1-2019.02-x86_64_arm-linux-gnueabihf/arm-linux-gnueabihf/include
-I/yocto/build/tmp/work/armv7vet2hf-neon-poky-linux-gnueabi/glibc/linaro-2.25-r0/recipe-sysroot/usr/include
-O2 -pipe -g -feliminate-unused-debug-types
-fdebug-prefix-map=/yocto/build/tmp/work/armv7vet2hf-neon-poky-linux-gnueabi/glibc/linaro-2.25-r0=/usr/src/debug/glibc/linaro-2.25-r0
-fdebug-prefix-map=/yocto/build/tmp/work/armv7vet2hf-neon-poky-linux-gnueabi/glibc/linaro-2.25-r0/recipe-sysroot=
-fdebug-prefix-map=/yocto/build/tmp/work/armv7vet2hf-neon-poky-linux-gnueabi/glibc/linaro-2.25-r0/recipe-sysroot-native=
* -fasynchronous-unwind-tables -fno-unwind-tables *
-L/opt/archive-pkgs/gcc-linaro-7.4.1-2019.02-x86_64_arm-linux-gnueabihf/arm-linux-gnueabihf/lib
-Wl,-rpath-link,/opt/archive-pkgs/gcc-linaro-7.4.1-2019.02-x86_64_arm-linux-gnueabihf/arm-linux-gnueabihf/lib
-Wl,-O1 -Wl,--hash-style=gnu -Wl,--as-needed  -Wl,-z,relro,-z,now
-fno-stack-protector -o conftest
               conftest.c -static -nostartfiles -nostdlib
               1>&5
/tmp/ccbJ1zoJ.o:(.ARM.exidx+0x0): undefined reference to
`__aeabi_unwind_cpp_pr0'
/tmp/ccbJ1zoJ.o:(.ARM.exidx.text.startup+0x0): undefined reference to
`__aeabi_unwind_cpp_pr0'
/tmp/ccbJ1zoJ.o:(.ARM.exidx.text.exit+0x0): undefined reference to
`__aeabi_unwind_cpp_pr0'
collect2: error: ld returned 1 exit status
configure:5687: $? = 1
configure:5707: error: missing __attribute__ ((constructor)) support??
======================================================================================

I am interested to know your config.log after you built. Can you please
share ?

Thanks in Advance,
-Abhijit

On Wed, Mar 15, 2023 at 12:17 AM Adhemerval Zanella Netto <
adhemerval.zanella@linaro.org> wrote:

>
>
> On 09/03/23 07:04, Abhijit Ray Chaudhury via Libc-help wrote:
> > Hi ,
> >
> > I am trying to compile glibc-2.25 with -fasynchronous-unwind-tables flag
> > for correctly generating backtrace . But during configure, it conflicts
> > with -fno-unwind-tables passed by sysdeps/arm/preconfigure and generates
> > link error during conftest.
> >
> > My gcc does not enable -fasynchronous-unwind-tables by default. How do I
> > compile entire libc using unwind-tables ?
> >
> > Thanks in Advance,
> > -Abhijit
>
>
> I don't see any build issue on master with:
>
> CC="arm-glibc-linux-gnueabihf-gcc -fasynchronous-unwind-tables" \
> CXX="arm-glibc-linux-gnueabihf-g++ -fasynchronous-unwind-tables" \
> configure --prefix=/usr
>
> With gcc 11.3.1.  I am not sure about 2.25, this is a quite old version;
> but
> I also don't see anything on git history that might affect it.
>