[Qemu-discuss] Debugging multi-thread application inside qemu-user

[Alex Barcelo]

[I'm not sure if this is the right list, as I am really using qemu-ppc
and don't know if it's architecture-specific and have no easy way to
check other architectures].

So, my problem is that I have qemu-ppc and some cross-compiled
multi-threaded program[1]. I am debugging in eclipse using the -g
parameter. But... Strange Things Happen (TM)[2] and the debugging is
not consistent with normal execution. The debugging starts to break
(breakpoints lost, tracing jumps, erratic behavior) when a new thread
is spawned. Unfortunately what I have is too complicated to check
easily. I am using gdb powerpc-linux-gnu from the emdebian stable
repositories.

I have a couple of questions:
*) Has someone debugged multithreaded applications this way? Having
this kind of problems is normal? Have I omitted some steps? Does some
things have to be set up before debugging through gdb?
*) Is there some easy test to check multi-thread? I have a test
application to check for multithread support, but it is not
"interesting". And creating a test program without knowing anything
seems futile, and maybe someone has stomped onto this earlier and can
give me some advice.

I know that I'm asking something strange with bad and insufficient
information. I need some light, I don't know where to look. Thanks

[1] What I really I'm trying is working a qemu-system inside a
qemu-user, which I know is a bit complicated, but the difficulty seems
to be generic of multi-thread applications.

[2] I'm currently trying to understand why an application hangs
unresponsively, but when I debug it, a SIGPWR crashes the application.
Googling a little bit shows me that it seems a signal number issue[3],
so... maybe is an issue with the cross-compiled gdb?

[3] http://lists.ozlabs.org/pipermail/linuxppc-embedded/2000-April/001063.html