[Libc-help] Build glibc linking libunwind

[Fabio]

Hi all,
I am trying to build glibc and link libunwind to get a backtrace at
the beginning of some glibc function like strcpy for example, but I
can't get it to build.
I include -lunwind in the CFLAGS and I export
LD_LIBRARY_PATH=/usr/local/lib, but when it comes to build ld.so it
fails:

usr/bin/gcc-4.3   -nostdlib -nostartfiles -shared -I/usr/local/lib      \
         -Wl,-z,combreloc -Wl,-z,relro -Wl,--hash-style=both -Wl,-z,defs
-Wl,--verbose 2>&1 |    \
         LC_ALL=C \
         sed -e '/^=========/,/^=========/!d;/^=========/d'    \
             -e 's/\. = .* + SIZEOF_HEADERS;/& _begin = . - SIZEOF_HEADERS;/' \
         > /home/wintermute/tesi/glibc/2.14/custom/glibc-build/elf/ld.so.lds
/usr/bin/gcc-4.3   -nostdlib -nostartfiles -shared -I/usr/local/lib -o
/home/wintermute/tesi/glibc/2.14/custom/glibc-build/elf/ld.so
         \
         -Wl,-z,combreloc -Wl,-z,relro -Wl,--hash-style=both -Wl,-z,defs       \
         /home/wintermute/tesi/glibc/2.14/custom/glibc-build/elf/librtld.os
-Wl,--version-script=/home/wintermute/tesi/glibc/2.14/custom/glibc-build/ld.map
\
         -Wl,-soname=ld-linux.so.2 -T
/home/wintermute/tesi/glibc/2.14/custom/glibc-build/elf/ld.so.lds
/home/wintermute/tesi/glibc/2.14/custom/glibc-build/elf/librtld.os: In
function `strcpy':
/home/wintermute/tesi/glibc/2.14/custom/glibc-2.14/string/strcpy.c:43:
undefined reference to `_Ux86_getcontext'
/home/wintermute/tesi/glibc/2.14/custom/glibc-2.14/string/strcpy.c:44:
undefined reference to `_ULx86_init_local'
collect2: ld returned 1 exit status

Am I missing something? Sorry for asking a dumb question and thanks in advance.

--
Kind regards,
Fabio Pozzi