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cross-gdb: fix a mismatch between libthread_db and libpthread

I' ve a cross-gdb configured with --host=i686-pc-linux-gnu --target=powerpc-e300c3-linux-gnu. i can correctly debug an application on a remote board with gdbserver but i get an error about a version mismatch between libthread_db and libpthread so i can't debug threads correctly (gdb recognizes only one thread instead of three threads). Maybe it's is due to a different version of libc: on host machine i've libc2.15 and on target machine lib2.5. I tried to rebuid libc2.5 for host in order to link gdb against to it but it's an hell. Before i get crazy to rebuild it, could someone confirm that it's a libc problem?

Solution

  • I tried to rebuid libc2.5 for host in order to link gdb against to it

    That's not what you need.

    What you need, is for gdb to find and load libthread_db.so.1, that matches your target libpthread.so.0.

    For this, you need to

    1. build libc-2.5 for host, and
    2. set GDB's libthread-db-search-path such that it finds the libthread_db.so.1 built in step 1.

    You don't actually need to build the entire libc in step 1. Something like this should suffice:

    mkdir build && cd build
../configure --prefix=/usr
make -C ../nptl_db objdir=`pwd`

    Update:

    i have GDB 6.6 and there isn't libthread-db-search-path. What is another way to specify that path?

    That GDB will just dlopen("libthread_db.so.1", ...). So to make it find the right libthread_db.so.1, you need to adjust LD_LIBRARY_PATH. Using bash:

    LD_LIBRARY_PATH=/tmp/glibc-2.5/build/nptl_db gdb /path/to/target/a.out