cross-linker behaviour differs from native linked

This requires a bit of background to understand. From the man page of ld(1).

-snip-
       -rpath-link=dir
           When using ELF or SunOS, one shared library may require another.
           This happens when an "ld -shared" link includes a shared library as
           one of the input files.

           When the linker encounters such a dependency when doing a non-
           shared, non-relocatable link, it will automatically try to locate
           the required shared library and include it in the link, if it is
           not included explicitly. In such a case, the -rpath-link option
           specifies the first set of directories to search. The -rpath-link
           option may specify a sequence of directory names either by
           specifying a list of names separated by colons, or by appearing
           multiple times.

           This option should be used with caution as it overrides the search
           path that may have been hard compiled into a shared library. In
           such a case it is possible to use unintentionally a different
           search path than the runtime linker would do.

           The linker uses the following search paths to locate required
           shared libraries:

           1. Any directories specified by -rpath-link options.

           2. Any directories specified by -rpath options. The difference
               between -rpath and -rpath-link is that directories specified by
               -rpath options are included in the executable and used at
               runtime, whereas the -rpath-link option is only effective at
               link time. Searching -rpath in this way is only supported by
               native linkers and cross linkers which have been configured
               with the --with-sysroot option.

           3. On an ELF system, for native linkers, if the -rpath and
               -rpath-link options were not used, search the contents of the
               environment variable "LD_RUN_PATH".

           4. On SunOS, if the -rpath option was not used, search any
               directories specified using -L options.

           5. For a native linker, the search the contents of the environment
               variable "LD_LIBRARY_PATH".

           6. For a native ELF linker, the directories in "DT_RUNPATH" or
               "DT_RPATH" of a shared library are searched for shared
               libraries needed by it. The "DT_RPATH" entries are ignored if
               "DT_RUNPATH" entries exist.

           7. The default directories, normally /lib and /usr/lib.

           8. For a native linker on an ELF system, if the file
               /etc/ld.so.conf exists, the list of directories found in that
               file.

           If the required shared library is not found, the linker will issue
           a warning and continue with the link.
-snip-

Our concern are the sections 3, 5, 6, 8 and indirectly 7 (/usr/lib/arm-linux-gnueabi isn't apparently considered default directory).

The problem is, that while we search for libraries in /usr/lib/arm-linux-gnueabi, the search is not _recursive_. Take case that we link against -lhi, which in turn uses symbols from -lhi. With a native toolchain, we can just build by giving "gcc -lhi". With current cross-toolchain, that is not enough.

The attached testcase, which succeeds on native ld, will fail with the cross-toolchain with:

-snip-
/usr/lib/gcc/arm-linux-gnueabi/4.6/../../../../arm-linux-gnueabi/bin/ld: warning: liblo.so, needed by /usr/lib/arm-linux-gnueabi/libhi.so, not found (try using -rpath or -rpath-link)
/usr/lib/arm-linux-gnueabi/libhi.so: undefined reference to `alowcall'
collect2: ld returned 1 exit status
-snip-

Changing the last line to either:

arm-linux-gnueabi-gcc hiuser.c -llo -lhi -o foouser
arm-linux-gnueabi-gcc hiuser.c -Wl,-rpath-link=/usr/lib/arm-linux-gnueabi -lhi -o foouser

Will make the build succeed.

We have a bunch of options here:

1) patch ld to make cross-ld behave identically to ld. This can be done by setting "NATIVE=yes" in genscripts.sh of binutils
2) add /usr/lib/arm-linux-gnueabi to default directories (after quick search didn't find out how). This could still risk breaking if there are packages that use LD_LIBRARY_PATH during buildtime
3) tell people to change their buildscripts to add all libraries to the linking command line. This is tricky, as most people don't select the -lflags them self, they come from pkg-config et all. Further more, people have been actively endorsing doing the complete opposite, eg. removing all unnecessary -lflags to cut down package dependencies.
4) copy the ld wrapper from scratchbox that adds the default directories and LD_LIBRARY_PATH with -rpath-link to the real linkier... I don't think we want that, but just for sake of completeness lets mention it ;)

Discuss.