From mboxrd@z Thu Jan  1 00:00:00 1970
From: Will Wagner <will_wagner@carallon.com>
Date: Mon, 03 Sep 2007 15:12:45 +0100
Subject: [Buildroot] debugging threads
Message-ID: <46DC165D.3000407@carallon.com>
List-Id: <buildroot.busybox.net>
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To: buildroot@busybox.net

Hello,

I am trying to debug a multithreaded app and am having some problems. 
I've hunted around how to do this and have done the following:

Built uClibc with debug threads on so have a libthread_db.so
Built gdbserver for target

I then execute gdbserver with:
gdbserver 192.168.42.15:2345 /usr/sbin/threaded_test

On the host machine I run:
~/buildroot/build_i686/staging_dir/usr/bin/i686-linux-gdb ~/threaded_test

Once gdb starts I point it to the shared libs with:
set solib-absolute-prefix ~/buildroot/project_build_i686/uclibc/root

Then connect to gdbserver with
target remote 192.168.42.101:2345

I am able to debug the application until a call to create a thread 
(pthread_create) when I get the following error:

Program received signal SIG32, Real-time event 32.
0xb7ef0175 in sigsuspend ()
    from
/home/willw/buildroot/project_build_i686/uclibc/root/lib/libc.so.0
(gdb) bt
#0  0xb7ef0175 in sigsuspend ()
    from
/home/willw/buildroot/project_build_i686/uclibc/root/lib/libc.so.0
#1  0xb7faf6a4 in __pthread_wait_for_restart_signal ()
    from
/home/willw/buildroot/project_build_i686/uclibc/root/lib/libpthread.so.0
#2  0xb7faf6cc in ?? ()
    from
/home/willw/buildroot/project_build_i686/uclibc/root/lib/libpthread.so.0
#3  0xb7fb6040 in ?? ()
    from
/home/willw/buildroot/project_build_i686/uclibc/root/lib/libpthread.so.0
#4  0xb7fb1de8 in ?? ()
    from
/home/willw/buildroot/project_build_i686/uclibc/root/lib/libpthread.so.0
#5  0xbf871718 in ?? ()
#6  0xb7fafda8 in pthread_create ()
    from
/home/willw/buildroot/project_build_i686/uclibc/root/lib/libpthread.so.0
Backtrace stopped: frame did not save the PC


Can anyone tell me what step I am missing to get thread debugging 
working? From searching on the net it seems the libthread_db is needed 
but it doesn't seem to be loaded by gdb.

Many thanks,

Will.

-- 
------------------------------------------------------------------------
Will Wagner                                     will_wagner at carallon.com
Senior Project Engineer                  Office Tel: +44 (0)20 7371 2032
Carallon Ltd, Studio G20, Shepherds Building, Rockley Rd, London W14 0DA
------------------------------------------------------------------------