[uClibc] uclibc gdb and threads

[Andrew de Quincey]

Hi - I'm having slightly more progress here. I'm getting symbols now. Although 
objdump still claims there aren't any - my guess is a crosscompiled objdump 
has a bug.

I'm remote debugging using gdb/gdbserver 6.2.1, compiled with roughly these 
instructions: http://www.kegel.com/linux/gdbserver.txt. 

Note I'm not using hardhat - as I said previously its gcc 3.3.4 from the 
uclibc "toolchain" scripts. GDB is compiled against this version of uclibc.

First issue is that breakpoints dont seem to be working - I can set them, but 
the execution never stops. However I don't need those right now, although 
they would be *useful*.

The main concern for me is now threaded debugging. I keep getting "Program 
received signal SIG32, Real-time event 32." messages in GDB.

I've seen these before, and generally its caused by problems with 
libthread_db.so.1 - but that library is definitely resident on the target 
machine. 

If I run crosscompile gdb and run it on the target machine, I can see it 
claims to load libthread_db.so.1 ok:

This GDB was configured as "ppc-405-linux"...Using host libthread_db library 
"/mnt/core/lib/libthread_db.so.1".

However when I actually run the program, I still get "Program received signal 
SIG32, Real-time event 32.". In fact, I get about 3 of those, followed by:

warning: Cannot initialize thread debugging library: generic error
warning: Cannot initialize thread debugging library: generic error
warning: Cannot initialize thread debugging library: generic error
warning: Cannot initialize thread debugging library: generic error
warning: Cannot initialize thread debugging library: generic error
warning: Cannot initialize thread debugging library: generic error
This GDB was configured as "ppc-405-linux"...Using host libthread_db library 
"/mnt/core/lib/libthread_db.so.1".

I don't see how the libthread_db can be returning an error - I looked at the 
code, and the init function just returns "OK" always.