gdbserver crash

[Thomas . E . Daley]

OVERVIEW
--------
gdbserver keeps crashing with:

  thread getmsg err: no event message for getmsg
  Segmentation fault

when trying to debug threaded applications.


THE DETAILS
-----------
I have been trying to get gdbserver working from a i686-linux host
to a powerpc-linux target.  I have built the cross development tools
myself from:

binutils-2.13.1
gcc-3.2.3
glibc-2.3.2
glibc-linuxthreads-2.3.2


I have built the Linux kernel with the tools and have had no kernel
problems.

I started with insight-5.3 and had several problems.
1) solib-absolute-prefix, solib-search-path not set.
2) Realtime signal not recognized, had to add REALTIME_LO, REALTIME_HI to
   gdbserver/server.h, then got SIG32 messages.
   Then set "handle SIG32 nostop".
3) Can't interrupt a running program.
4) gdbserver crashes with "thread getmsg err: no event message for getmsg"

Problems 1 and 2 I fixed.

Then I got the latest snapshot insight+dejagnu-20030522 and things are
better.  I added REALTIME_LO, REALTIME_HI to gdbserver/server.h and
configured and built.

cd gdb/gdbserver
mkdir powerpc-linux
cd powerpc-linux
CC=powerpc-linux-gcc ../configure powerpc-linux
make
# Copy executable to nfs mounted target /bin

Now I don't get the SIG32 messages and I can break into a running program.
The only problem left is the gdbserver crash.


PROBLEM DETAILS
---------------
The crash does not always happen at the same place in the program, so may
be timing related.  Using "set debug remote 1" I see that gdbserver
always crashes after the same packet exchange:

Sending packet: $M1001a3b4,4:7d821008#a1...Ack
Packet received: OK
Sending packet: $m3000c0d8,4#bf...Ack
Packet received: 9421ffe0
Sending packet: $M3000c0d8,4:7d821008#a7...Ack
Packet received: OK
Sending packet: $Hc0#db...Ack
Packet received: OK
Sending packet: $c#63...Ack


in thread_db_create_event() I see that the message is from the failure of
the td_ta_event_getmsg() call.  gdbserver crashes because the td_event_msg_t
doesn't have valid data.


CONCLUSION
----------
Can someone shed some light on this prolem?  I'll keep digging into it
but would like some help if anyone has a suggestion.

Thanks in advance!

t o m . d a l e y @ s e a g a t e . c o m