Debugging with GDB over several processes

Question

Without getting into to to much detail, I'm working on a program that consists of several separate processes all running on embedded QNX RTOS. They don't have a parent-child relationship, they are all spawned using spawnlp(P_NOWAIT, ...) and they all communicate with each other using the IPC mechanism provided by the OS.

When I'm debugging with GDB and I hit a breakpoint in the process I'm working in, all of my threads are paused, which is great. But is there a way to also have it pause execution of my other processes? Right now what's happening is all the other processes keep on truckin' while my process is paused and so all the IPC queues get full etc. etc.

Thanks in advance,

HF

Answer 1

You can associate a list of GDB commands with each breakpoint. So when you hit a breakpoint in process A, you can for example send a SIGTRAP to process B, which should drop it into the debugger:

(gdb) b main
Breakpoint 1 at 0x804834a: file testA.c, line 40.
(gdb) command
Type commands for when breakpoint 1 is hit, one per line.
End with a line saying just "end".
>shell kill -s TRAP `pidof testB`
>end
(gdb) 

More info at Breakpoint Command Lists