gdbserver: coredump image of a multi-threaded program: seeing only one thread

Hi,

I have trouble to 'debug' a coredump image of a multi-threaded program with
gdbserver. I am using gcc-3.4.1/glibc-2.3.3 and gdb 6.3. Target is a
PowerPC board
running Linux 2.4.25. If I start my program under gdbserver, I can
remotely debug it
fine, i.e. I see all the threads and debug them fine. But if I have a
coredump,
I can then see only the thread at fault...

My .gdbinit:
set auto-solib-add 1
set solib-absolute-prefix /dummy
set solib-search-path
/opt/crosstool/powerpc-linux/gcc-3.4.1-glibc-2.3.3/powerpc-linux/lib
set confirm off

I call gdb like this:
powerpc-linux-gdb --core=test_task.11.238 --se=test_task

BTW, If I debug the running process (gdbserevr --attach), when the
program crashes,
I can see all the threads from gdb, so I have only the issue with the
coredump...

Any idea what I might do wrong or missing ?

Thanks,
Olivier