ld64.so present in ldd, missing at runtime

Question

I am compiling some code, and for various reasons I'm doing it statically. On my Ubuntu 12.04 / gcc 4.6.3 machine it compiles executes fine, and is fully static:

> ldd mycode
    not a dynamic executable

So far so good. But I also need to run it on another machine, a Scientific Linux 5 system, running gcc 4.5.3. For some reason here, ldd has some dynamic libs left over:

> ldd mycode
    linux-vdso.so.1 =>  (0x00007fffd75fd000)
    libstdc++.so.6 => /usr/local/swift/gcc-4.5.3/lib64/libstdc++.so.6 (0x00002b4bafab2000)
    libm.so.6 => /lib64/libm.so.6 (0x000000398ca00000)
    libc.so.6 => /lib64/libc.so.6 (0x000000398c600000)
    /lib/ld64.so.1 => /lib64/ld-linux-x86-64.so.2 (0x000000398c200000)
    libgcc_s.so.1 => /usr/local/swift/gcc-4.5.3/lib64/libgcc_s.so.1 (0x00002b4bafdb8000)

Which is, in itself, fine. The code compiles and links OK, and as you can see from ldd, all the dependencies are resolved. However, when I try to execute it on the SL machine, it fails:

> ./mycode
  /lib/ld64.so.1: bad ELF interpreter: No such file or directory

As far as I can see therefore, at execute time for some reason the /lib/ld64.so.1 => /lib64/ld-linux-x86-64.so.2 link is not being resolved, even though ldd does it. Of course, on machines where I have root access I can solve this by making a sym link from ld-linux-x84..blah to /lib/ld64.so.1 but this is a rather pants solution and I can't apply it to our cluster. If I compile the whole thing dynamically it works fine, but this means installing all the 3rd party libraries I'm compiling against on a bunch of machines which I wanted to avoid. Finally, all the dependencies against which I compile are also used by another project, also compiled with cmake, and in that case I have no problem, and ldd actually lists the /lib64/ld-linux...blah direct, not a call to /lib/ld64.so.

So - why is this happening? Why can I compile and link the code OK, ldd it OK, and yet not execute it? Any ideas would be gratefully received!

Answer 1

OK, I think I cracked this in the end. It was basically the linker arguments being passed by cmake, which were a nasty combination of static and dynamic ones, However, adding the following lines to my CMakeLists.txt fixed it:

SET_TARGET_PROPERTIES (mytarget PROPERTIES LINK_SEARCH_START_STATIC 1)
SET_TARGET_PROPERTIES (mytarget PROPERTIES LINK_SEARCH_END_STATIC 1)