Re: gdbstub initial code, another approach

[Jan Kratochvil <jan.kratochvil@redhat.com>]

On Wed, 28 Jul 2010 20:17:02 +0200, Oleg Nesterov wrote:
> 	- the testing was very limited. I played with it about
> 	  an hour and didn't find any problems, vut that is all.
[...]
> Btw, gdb crashes very often right after
> 
> 	(gdb) set target-async on
> 	(gdb) set non-stop
> 	(gdb) file mt-program
> 	(gdb) target extended-remote :port
> 	(gdb) attach its_pid
> 
> I didn't even try to investigate (this doesn't happen when
> it works with the real gdbserver). Just retry, gdb is buggy.

Trying it with both /bin/sleep and a threaded testcase and I never got a crash
(kernel-2.6.33.6-147.fc13.x86_64 as both host and KVM guest OS).

$ killall gdbstub;~/redhat/threadit&p=$!;~/redhat/gdbstub &>~/redhat/out&sleep 0.1;./gdb -nx -ex 'set target-async on' -ex 'set non-stop' -ex "file $HOME/redhat/threadit" -ex 'target extended-remote :2000' -ex "attach $p" -ex 'set confirm no';kill $p; 
gdbstub: no process killed
[6] 22822
[7] 22823
GNU gdb (GDB) 7.2.50.20100802-cvs
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This GDB was configured as "x86_64-unknown-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Reading symbols from /home/jkratoch/redhat/threadit...done.
Remote debugging using :2000
Attached to process 22822
[New Thread 22822.22822]
[New Thread 22822.22825]
Reading symbols from /lib64/libpthread.so.0...Reading symbols from /usr/lib/debug/lib64/libpthread-2.12.so.debug...done.
done.
Loaded symbols for /lib64/libpthread.so.0
Reading symbols from /lib64/libc.so.6...Reading symbols from /usr/lib/debug/lib64/libc-2.12.so.debug...done.
done.
Loaded symbols for /lib64/libc.so.6
Reading symbols from /lib64/ld-linux-x86-64.so.2...Reading symbols from /usr/lib/debug/lib64/ld-2.12.so.debug...done.
done.
Loaded symbols for /lib64/ld-linux-x86-64.so.2
0x00007fead8db6fbd in pthread_join (threadid=140646633633552, thread_return=0x0) at pthread_join.c:89
89	    lll_wait_tid (pd->tid);
(gdb) 
[Thread 22822.22825] #2 stopped.
0x00007fead8ad6a6d in nanosleep () at ../sysdeps/unix/syscall-template.S:82
82	T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)
Current language:  auto
The current source language is "auto; currently asm".
info threads 
  2 Thread 22822.22825  0x00007fead8ad6a6d in nanosleep () at ../sysdeps/unix/syscall-template.S:82
* 1 Thread 22822.22822  0x00007fead8db6fbd in pthread_join (threadid=140646633633552, thread_return=0x0) at pthread_join.c:89
(gdb) q
[7]+  Done                    ~/redhat/gdbstub &>~/redhat/out
[6]+  Terminated              ~/redhat/threadit


Thanks,
Jan