Finding shared library dependencies when linking executable - gcc

Question

I am attempting to cross-compile gstreamer for ARM hosts on a Ubuntu 12.04 (32-bit) build system. None of what I'm about to describe happens with the i686-linux-gnu GCC. I am compiling on Ubuntu 12.04 using this gcc:
> arm-linux-gnueabihf-gcc -v
Using built-in specs.
COLLECT_GCC=arm-linux-gnueabihf-gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/arm-linux-gnueabihf/4.6/lto-wrapper
Target: arm-linux-gnueabihf
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.6.3-1ubuntu5'
--with-bugurl=file:///usr/share/doc/gcc-4.6/README.Bugs
--enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.6
--enable-shared --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib
--without-included-gettext --enable-threads=posix
--with-gxx-include-dir=/usr/arm-linux-gnueabihf/include/c++/4.6.3 --libdir=/usr/lib
--enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes
--enable-gnu-unique-object --enable-plugin --enable-objc-gc --enable-multilib
--disable-sjlj-exceptions --with-arch=armv7-a --with-float=hard --with-fpu=vfpv3-d16
--with-mode=thumb --disable-werror --enable-checking=release --build=i686-linux-gnu
--host=i686-linux-gnu --target=arm-linux-gnueabihf --program-prefix=arm-linux-gnueabihf-
--includedir=/usr/arm-linux-gnueabihf/include
--with-headers=/usr/arm-linux-gnueabihf/include
--with-libs=/usr/arm-linux-gnueabihf/lib
Thread model: posix
gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5)
And this ld:
arm-linux-gnueabihf-ld -v
GNU ld (GNU Binutils for Ubuntu) 2.22
GCC was installed from the default Ubuntu 12.04 PPAs. When the build system gets to linking the gst-discoverer-1.0 executable, I get the following error:
/usr/lib/gcc/arm-linux-gnueabihf/4.6/../../../../arm-linux-gnueabihf/bin/ld: warning: liborc-0.4.so.0, needed by ../gst-libs/gst/video/.libs/libgstvideo-1.0.so, not found (try using -rpath or -rpath-link)
../gst-libs/gst/video/.libs/libgstvideo-1.0.so: undefined reference to `orc_program_compile'
../gst-libs/gst/video/.libs/libgstvideo-1.0.so: undefined reference to `orc_program_set_backup_function'
../gst-libs/gst/video/.libs/libgstvideo-1.0.so: undefined reference to `orc_program_new_from_static_bytecode'
../gst-libs/gst/video/.libs/libgstvideo-1.0.so: undefined reference to `orc_program_free'
../gst-libs/gst/video/.libs/libgstvideo-1.0.so: undefined reference to `orc_once_mutex_lock'
../gst-libs/gst/video/.libs/libgstvideo-1.0.so: undefined reference to `orc_program_take_code'
../gst-libs/gst/video/.libs/libgstvideo-1.0.so: undefined reference to `orc_once_mutex_unlock'
collect2: ld returned 1 exit status
gst-discoverer-1.0 depends on libgstvideo-1.0.so. libgstvideo-1.0.so (which was built successfully earlier in the process) has a dependency on liborc-0.4.so. Inspecting the libgstvideo-1.0.so with arm-linux-gnueabihf-readelf -a yields the following snippet:
Dynamic section at offset 0x29ed8 contains 33 entries:
Tag Type Name/Value
0x00000001 (NEEDED) Shared library: [libgstbase-1.0.so.0]
0x00000001 (NEEDED) Shared library: [libgstreamer-1.0.so.0]
0x00000001 (NEEDED) Shared library: [libgobject-2.0.so.0]
0x00000001 (NEEDED) Shared library: [libglib-2.0.so.0]
0x00000001 (NEEDED) Shared library: [liborc-0.4.so.0]
0x00000001 (NEEDED) Shared library: [libgcc_s.so.1]
0x00000001 (NEEDED) Shared library: [libpthread.so.0]
0x00000001 (NEEDED) Shared library: [libc.so.6]
0x0000000e (SONAME) Library soname: [libgstvideo-1.0.so.0]
0x0000000f (RPATH) Library rpath: [/home/test/gst/gstreamer/gstreamer/libs/gst/base/.libs:/
home/test/gst/gstreamer/gstreamer/gst/.libs:/home/test/gst/gstreamer/orc/orc/.libs]
The path to liborc-0.4.so in the RPATH entry is correct. The link line for gst-discoverer-1.0 does not contain references to liborc because it is not directly dependent on it (only indirectly dependent via libgstvideo-1.0.so). I have tried adding "-rpath-link=/home/test/gst/gstreamer/orc/orc/.libs" to my LDFLAGS, but it didn't work. Any ideas about why the cross-compile linker is not able to find a dependency of this shared library?

Answer 1

It seems I was on the right track, but I was passing -rpath-link to ld (using LDFLAGS on my configure line). Since it is gcc that is actually doing the linking, I need to use CFLAGS and the -Wl argument like this:
./configure CFLAGS="-Wl,-rpath=/home/test/gst/gstreamer/orc/orc/libs"
According to some, there might be a bug in the cross-linker.